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United States
Environmental Protection
Agency
Air Pollution Training Institute
MD20
Environmental Research Center
Research Triangle Park NC 27711
EPA 450/2-80-068
March 1980
Air
APTI
Course 413
Control of Paniculate
Emissions
Instructor's Guide
Prepared By:
D. Beachler
G. Aldina
J. Jahnke
Northrop Services, Inc.
P.O. Box 12313
Research Triangle Park, NC 27709
Under Contract No.
68-02-2374
EPA Project Officer
R. E. Townsend
United States Environmental Protection Agency
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
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Notice
This is not an official policy and standards document. The opinions, findings, and
conclusions are those of the authors and not necessarily those of the Environmental
Protection Agency. Every attempt has been made to represent the present state of
the art as well as subject areas still under evaluation. Any mention of products or
organizations does not constitute endorsement by the United States Environmental
Protection Agency.
Availability of Copies of This Docutaient
This document is issued by the Manpower and Technical Information Branch, Con-
trol Programs Development Division, Office of Air Quality Planning and Standards,
USEPA. It was developed for use in training courses presented by the EPA Air Pollu-
tion Training Institute and others receiving contractual or grant support from the
Institute. Other organizations are welcome to use the document for training purposes.
Schools or governmental air pollution control agencies establishing training programs
may receive single copies of this document, free of charge, from the Air Pollution
Training Institute, USEPA, MD-20, Research Triangle Park, NC 27711. Others may
obtain copies, for a fee, from the National Technical Information Service, 5825 Port
Royal Road, Springfield, VA 22161.
ii
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%
AIR POLLUTION TRAINING INSTITUTE
MANPOWER AND TECHNICAL INFORMATION BRANCH
CONTROL PROGRAMS DEVELOPMENT DIVISION
OFFICE OF AIR QUALITY PLANNING AND STANDARDS
The Air Pollution Training Institute (1) conducts training for personnel working on the develop-
ment and improvement of state, and local governmental, and EPA air pollution control programs,
as well as for personnel in industry and academic institutions; (2) provides consultation and other
training assistance to governmental agencies, educational institutions, industrial organizations, and
others engaged in air pollution training activities; and (3) promotes the development and improve-
ment of air pollution training programs in educational institutions and state, regional, and local
governmental air pollution control agencies. Much of the program is now conducted by an on-site
contractor, Northrop Services, Inc.
One of the principal mechanisms utilized to meet the Institute's goals is the intensive short term
technical training course. A full-time professional staff is responsible for the design, development,
and presentation of these courses. In addition the services of scientists, engineers, and specialists
from other EPA programs governmental agencies, industries, and universities are used to augment
and reinforce the Institute staff in the development and presentation of technical material.
Individual course objectives and desired learning outcomes are delineated to meet specific program
needs through training. Subject matter areas covered include air pollution source studies, atmos-
pheric dispersion, and air quality management. These courses are presented in the Institute's resi-
dent classrooms and laboratories and at various field locations.
R. Alan Schueler
Program Manager
Northrop Services, Inc.
/James A. Jahnfke
Technical Director
Northrop Sendees, Inc.
Jeanjf Schueneman
Chief, Manpower & Technical
Information Branch
iii
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TABLE OF CONTENTS
Page
Introductory Material 1
Course Description and Prerequisites 1
Background, Origin, and Philosophy 1
Instruction for Preparation and Presentation of Course 3
Checklists 8
Course Goal and Objectives . . . 10
Sample Agenda 15
Pre-test and Key 18
Post-test and Key 38
WELCOME AND REGISTRATION 56
LESSON 1 - Review of the Basics 60
LESSON 2 - Particle Dynamics 71
LESSON 2a - Problem Session I - Particle Dynamics 84
LESSON 3 - Particle Sizing—Measurement arid Mathematical Methods .... 87
LESSON 3a - Problem Session II-Particle Sizing 101
LESSON 4 - Methods for Reducing Particulate Emissions Ill
LESSON 5 - Settling Chamber—Principles, Operation, and Applications . . 119
LESSON 5a - Problem Session Ill-Settling Chambers 128
LESSON 6 - Cyclones: Principles, Operation, and Applications 131
LESSON 6a - Problem Session IV-Cyclones 144
LESSON 7 - Electrostatic Precipitator Principles and Operation 158
LESSON 8 - ESP - Design and Applications 175
LESSON 8a - Problem Session V-Electrostatic Precipitator 190
LESSON 9 - Fabric Filter Principles 196
LESSON 10 - Fabric Filter Applications 217
LESSON lOa - Problem Session VI-Fabric Filters 226
LESSON 11 _ Wet Collector Theory 233
LESSON lla - Problem Session VH-Wet Collector 252
LESSON 12 - Wet Collector Design 264
LESSON 13 - Operation, Maintenance and Inspection of Air Pollution
Control Equipment 281
LESSON 14 - Estimating the Cost of Control Equipment 294
iv
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Introductory Material
Instructions for Preparation and Presentation of Course #413
Control of Particulate Emissions
This guide is to provide you as Course Moderator with assistance in the
preparation and presentation of Course #413 - Control of Particulate Emissions.
It will provide you with guidelines, instructions and some general information
that should facilitate your efforts in staging this course.
I. Course Description and Prerequisites
This training course is a four-day lecture course dealing with the
mechanisms and design parameters of devices for control of particulate
emissions to the atmosphere. Major emphasis is placed on basic theory,
with problem sessions in which the student calculates the effects of
particle size distribution on efficiency and determines the efficiency
of devices such as wet collectors, cyclones, fabric filtration systems
and electrostatic precipitators. Knowledge gained in the course will
assist the student in reviewing plans and specifications for particulate
emission control systems with respect to their probable effectiveness,
and in making inspections of installations with operating particulate
emission control devices.
II. Background, Origin, and Philosophy
The Environmental Protection Agency Air Pollution Training Institute
(APTI) provides courses in air pollution control technology, ambient and
source monitoring, and air quality management. In July, 1976, Northrop
Services, Inc. was contracted to both present Training Institute courses
and to provide support and technical services for the Institute as a whole.
Courses of particular importance to governmental and industrial personnel
concerned with air pollution problems received early efforts of instruc-
tional development to design the best possible training experiences for
the students. This required thorough examination of both the materials
for instruction and an examination of the characteristics of the student
audience. From such studies, the courses have been revised and developed
to provide training that enables every student to achieve specific course
objectives.
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The students attending Course 413 generally characterize themselves
as engineers and are employed by a federal, state, or local pollution
control agency. The student makeup for attendees in seven course
offerings from October 1, 1978 through September 30, 1979 was as follows:
Profession
Administrator
Chemist
Engineer
Meteorologist
Physical Scientist
Sanitarian
Statistician
Technician
Others
Percent
1.0
3.9
63.2
1.0
3.2
2.3
0.3
7.5
17.6
Employer
Federal EPA
Other Fed. Gov.
State Gov.
Local
Industry
Consultant
Others
Percent
19.9
1.9
50.5
15.6
9.8
2.0
0.3
100.0
100.0
Educational
Background
High School
Bachelor
Master
Ph.D.
Percent
Percent
Years
Experience
0-1
2-4
5-7
8-10
> 10
The course has been designed for the engineer in a governmental air
pollution control agency. The course records indicate that the attendees
are in fact those for which the course has been developed. This
instructional package has therefore been prepared with this student
population in mind.
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Student intellectual studies performed during the initial contract
year have indicated that for APTI courses, the course content and
instructional methods should be explicit rather than implicit.
Although formal educational level tends to be generally high, the
ability testing has indicated the need for the course content to be
presented in a careful and logical and consistent order with the
underlying principles and relationships of given concepts being
taught directly. At critical junctures where students are required
to visualize a concept, infer a relationship, or visualize an added
dimension, instruction is mediated with the use of:
• Graphic illustrations, usually in the form of 35mm slides
• Lecture demonstrations
• In-class problem-solving sessions
• Constant repetition and review of fundamental concepts.
III. Instructions for Preparation and Presentation of Course
A. Responsibilities of Course Moderator
This course generally requires 4 days for a complete presentation.
It can also be expected 10 to 20 hours of additional preparation will
be required by the individual designated Course Moderator. Preparation
and continuity are the principle responsibilities of the Course Moderator
who will coordinate all on-site activities both before and during the
course presentation. The actual tasks that are considered the direct
responsibility of the Course Moderator are:
1. Scheduling the course presentation
2. Recruiting (hiring) and briefing instructors
3. Preparation of classroom and teaching facilities
4. Preparation of and distribution of course materials
5. Presentation of introduction and other appropriate lectures
6. Maintaining continuity throughout the course.
B. Scheduling
The course itself is designed around a format using 14 lectures and
7 problem sessions, all of which are designed to fit into a 4 day time
frame of morning and afternoon classes. Because the course contains
a concentrated level of involvement with rather technical material, it
is recommended that no more than seven (7) hours of class instruction
be presented in one day.
This Instructor's Guide contains lesson plans for all instruction, each
listed below with its recommended time and schedule placement.
DAY 1
Welcome and Registration 30 minutes
Lesson 1 Review of the Basics 90 minutes
Lesson 2 Particle Dynamics 60 minutes
Lesson 2a Problem Session I - Particle Dynamics 30 minutes
3
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Lesson 3
Lesson 3a
DAY 2
Lesson 4
Lesson 5
Lesson 5a
Lesson 6
Lesson 6a
Lesson 7
Lesson 8
Lesson 8a
DAY 3
Lesson 9
Lesson 10
Lesson lOa
Lesson 11
Lesson Ha
Lesson 12
DAY 4
Lesson 13
Particle Sizing - Measurement and Mathematical
Methods
Problem Session II - Particle Sizing
Homework Review
Methods for Reducing Particulate Emissions
Settling Chamber: Principles, Operation and
Applications
Problem Session III - Settling Chamber
Cyclones: Principles, Operation and Applications
Problem Session IV - Cyclones
Electrostatic Precipitator Principles and
Operation
ESP: Design and Applications
Problem Session V - Electrostatic Precipitator
Homework Review
Fabric Filter Principles
Fabric Filter Applications
Problem Session VI - Fabric Filter
Wet Collector Theory
Problem Session VII - Wet Collector
Wet Collector Design
Homework Review
Operations Maintenance and Inspection of
Air Pollution Control Equipment
Lesson 14 Estimating the Cost of Control Equipment
Pre-test Review
Course Overview
C. Instructors
60 minutes
30 minutes
30 minutes
30 minutes
30 minutes
15 minutes
45 minutes
45 minutes
75 minutes
60 minutes
60 minutes
15 minutes
90 minutes
30 minutes
60 minutes
75 minutes
60 minutes
60 minutes
30 minutes
60 minutes
60 minutes
45 minutes
30 minutes
The four most important criteria in the selection of faculty for
this course are:
1. A knowledge of the current methods and procedures used in
control of particulate emissions
2. Recent practical experience
3. Experience (and ability) to instruct adults using traditional
and non-traditional methods, materials, and techniques
4. A positive attitude toward air quality management.
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Before instructors are actually involved with instruction in the
classroom, the Course Moderator should conduct thorough briefing and
preparation sessions in which an overview of the entire course presen-
tation is given. Specific discussion of course and lesson objectives
should result in an assurance that the instructors are well prepared
and familiar with the materials, procedures, and techniques that they
will be using.
The Course Moderator should stress the difference in the role that
the instructor plays as compared to traditional university instruction
situations. All instructors should fully understand the function of the
course and lesson objectives and the relationship of each objective to
their particular materials and to the pre- and post-testing.
It may be particularly helpful to the instructors if they are able to
sit in on early sessions of the course presentation, so that they get a
feel for the way the students are oriented to the material and be able to
incorporate the strengths and background experiences of the students into
the various instructional sessions.
Preparation must be stressed to all prospective instructors. Thorough
familiarization with all the prepared materials is essential for even
"expert" instructors. Problem sessions require additional preparation
and should include a complete run-through to check out the methods used
before presenting them to the students.
D. Physical Setting
Classroom - 1200-1500 sq. ft. to accomodate 38-40 people (34-36 students,
3 instructors, 1 evaluator); all students should have desks
or tables - others need chairs only
- 35mm slide projector
- overhead projector
- screen at least 6 feet by 6 feet
- chalk board, erasers and chalk
E. Course Materials
In addition to the course lecture and lesson outlines, the pre-test,
post-test, keys, and the audiovisual materials provided with this instructor's
guide, this package also contains the following materials:
1. APTI Course 413 Student Manual, EPA-450/2-80-066
2. APTI Course 413 Student Problem Workbook, EPA-450/2-80-067
F. Audiovisual Materials
The visuals package accompanying these materials includes 384 35mm
slides. The specific lessons are as follows:
Lesson 1 33 slides 413-1-1 through 413-1-33
Lesson 2 30 slides 413-2-1 through 413-2-30
Lesson 3 36 slides 413-3-1 through 413-3-36
Lesson 4 14 slides 413-4-1 through 413-4-14
Lesson 5 13 slides 413-5-1 through 413-5-13
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15 slides
39 slides
34 slides
45 slides
9 slides
44 slides
39 slides
33 slides
no slides
413-6-1
413-7-1
413-8-1
413-9-1
413-10-1
413-11-1
413-12-1
413-13-1
through
through
through
through
through
through
through
through
413-6-15
413-7-39
413-8-34
413-9-45
413-10-9
413-11-44
413-12-39
413-13-33
Lesson 6
Lesson 7
Lesson 8
Lesson 9
Lesson 10
Lesson 11
Lesson 12
Lesson 13
Lesson 14
TOTAL 384 slides
Complete listings of the slides for each lesson are included
with the lesson plans. These slides are either supplied as a part
of the instructional resource package or are available on loan
for reproduction through the Air Pollution Training Institute.
Lesson Plan Use
Each lesson plan module is designed to serve as:
A. Source of lesson objectives
B. Content guide for instructor
C. Lecture outline
D. Directions for use of visual aids
E. Guidelines for approach to the lesson.
Generally, the lesson plans are organized as straight outlines with
additional instructions and keys to the visuals found on the right
hand border of the page. On occasion it was felt that the instructor
might need more specific information and a more narrative format is
used for the subject matter to be adequately covered.
Each lecture plan outline is carefully timed. Instructors should
give attention to observing time schedules and "pace" of the lessons
to be given.
Instructors must be familiar with the visual aids and handout
materials before attempting to present any lesson.
The visuals are keyed using number references that are also found
on the slides. The number identifies the lecture and sequence of the
slide. Thus, 413-16-5 identifies a slide in Lecture 16 that comes before
413-16-6 and after 413-16-4. Also, each slide is provided with a "thumb
spot" that should be in the upper right hand corner of the frame (under
your thumb) as the slide is loaded into a carousel. This should prevent
slides from being loaded backwards or upside-down.
Instructors may wish to vary slightly from the format or content for
a given lesson, but should be cautioned that the schedules and lesson
objectives must be maintained. Variations should be in the direction of
greater student participation. Instructors should remember that the
exams reflect the lesson objectives as presented through these lesson
outlines.
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H. Grading Philosophy
The guidelines for grading student's performance in "Control of
Particulate Emissions," and granting Continuing Education Units (CEU's)
are as follows:
The student must:
• attend a minimum of 95% of all scheduled class sessions
• complete and hand in copies of all homework =10 points
• achieve average course grade of 70%
course grade = final exam score + homework points
I. Other Logistics
Since the Course Moderator will netid to consider a great variety of
logistic and instructional concerns, the following checklist is provided
to serve as a guide to meeting these responsibilities.
The course developers have tried to provide you with as much
information and materials as possible to enable you to present a
successful and exciting educational venture.
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CHECKLIST
OF ACTIVITIES
FOR PRESENTING THE COURSE
A. Pre-course Responsibilities:
1. Reserve and confirm classroom(s) and laboratories, including
size, "set-up", location and costs (if any).
2. Contact and confirm all faculty (speakers) for the course(s),
including their AV requirements. Send material (i.e., slides
and instructor's manual) to them. One or more pre-course
instructor's meetings are advisable.
3. Reserve hotel accommodations for faculty.
4. Arrange for and confirm food service needs (i.e., meals,
coffee breaks, water, etc., if appropriate)-
5. Prepare and reproduce final ("revise" if appropriate) copy
of the detailed program schedule.
6. Reproduce final registration/attendance roster, including
observers (if any).
7. Prepare name badges and name "tents" for students and faculty.
8. Identify, order, and confirm all AV equipment needs.
9. Prepare two or three 12 in. x 15 in. signs on posterboard for
posting at meeting area.
10. Arrange for and confirm any special administrative assistance
needs on-site for course, including "local" Address of Welcome,
etc.
11. Obtain copies of EPA manuals and pamphlets.
12. Pack and ship box of supplies and materials one week prior
to beginning of course (if appropriate).
B. On-Site Course Responsibilities
1. Check on and determine final room arrangements (i.e., tables,
chairs, lectern, water, cups, etc.).
2. Set up AV equipment required each day and brief operator (if
supplied).
3. Post signs where needed.
4. Alert receptionist, phone operator(s), watchmen, etc., of
name, location, and schedule of program.
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5. Conduct a new speaker(s) (i.e., instructor) briefing session
on a daily basis.
&• Verify and make final food services/coffee arrangements (where
appropriate).
7. Identify and arrange for other physical needs as required (i.e.,
coat racks, ashtrays, etc.).
8. Make a final check on arrival of guest speakers (instructors)
for the day.
C. Post-course Responsibilities
1. Request honorarium and expense statements from faculty; order
and process checks.
2. Write thank-you letters and send checks to paid faculty.
3. Write thank-you letters to non-paid guest speakers and others
who may have contributed to the success of the course.
4. Prepare evaluation on each course (including instructions,
content, facilities, etc.).
5. Make sure AV equipment is returned.
6. Return unused materials to your office.
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COURSE 413
CONTROL OF PARTICULATE EMISSIONS
COURSE GOAL
Upon completion of the course, the student will be able to make decisions
about the suitability of particulate emissions control systems in terms of
their availability to meet emission control regulations. In order to be able
to make the required decisions about control systems, the student must learn
the principles of equipment operation, control efficiency parameters, typical
equipment cost information and typical industrial applications of control
equipment. Equipment design will be used as an instructional tool to teach
the principles and mechanisms of equipment operation. Developing proficiency
in equipment design per se is not a goal of this course. Developing ability
to act on applications for a permit to construct an air pollution source and
emission control system, as a governmental official, is a goal of this course.
COURSE OBJECTIVES
The student should be able:
(1) to explain briefly in 3 short paragraphs the origin, effects and
basic measurement methods of particulates in the atmosphere.
(2) to use the ideal gas law, laws pertaining to temperature, pressure
and volume corrections of gases, and the property of viscosity and
Reynolds number in particulate control calculations.
(3) to recall the air pollution control standards and regulations
relevant to particulate control and to use them as critieria in
the evaluation of particulate control equipment.
(4) to describe the hydrodynamic principles and physical processes
occurring in the separation of particulate matter from waste gas
streams such as diffusion, impaction, interception, gravity, electro-
static and magnetic forces.
(5) to describe the common methods of particle sizing and to choose the
appropriate method in calculating the efficiency of a particular
emission control device.
(6) to evaluate the design plans for a particulate control device
(including: a. settling chambers, b. cyclones, c. wet collection
devices, d. electrostatic precipitators, and e. fabric filters).
The student should be able to evaluate the design plans in terms
of collection efficiency, problems which may impair efficiency
and appropriateness of the control technique for the particular
source. Once this assessment is completed, the student should be
able to determine whether the particulate control device complies
with governmental emission control regualtions.
(7) to compare equipment features such as reliability, efficiency,
energy use, capital costs, operation costs, construction materials,
corrosion, and space requirements; given several particulate control
device options for a specific source.
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LESSON OBJECTIVES
Lesson 1 - Review of the Basic Concepts
• Recall the problems involved with nomenclature used in the numerous
theoretical calculations for control equipment.
• Define in general terms
• Temperature
Pressure
• Ideal gas law
• Reynolds number
• Molecular weight
• Gas viscosity
Lesson 2 - Particle Dynamics
• Describe the basic forces of gravity and buoyancy and
their relationship on a particle.
• Describe the aerodynamic drag force on a particle in motion and
the drag coefficient.
• List the three regimes that a particle flows in and their
relationships in calculating the drag force for each regime.
• Describe the Cunningham correction factor for the drag coefficient
in the laminar regime.
• Describe an overall equation for motion including gravity, buoyancy,
and drag.
• Recognize the equation to calculate the terminal settling velocity
for a particle in each regime.
• Determine the proper regime by calculating the factor "K".
Lesson 3 - Particle Sizing - Measurement and Mathematical Methods
• Recognize five methods of measuring the size of a particle and
briefly describe their operation.
• List the three most important parameters used to rate a particle
sizing device.
• Describe the major advantages and disadvantages of each of the
five particle measuring devices.
• Describe the aerodynamic diameter of a particle.
• Recognize three typical mathematical methods dealing with particle
size distribution.
• Describe the log-normal distribution and the shape of the curves
when plotted on various scales.
• Describe the geometric mean and standard deviation and how they can
be calculated for a log-normal distribution.
» Discuss how one can estimate a typical particle size distribution
from a proposed new source.
• Discuss how one can obtain the actual sample from a source and the
subsequent analysis for particle size distributions for each of the
measuring devices. n
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Lesson 4 - Methods for Reducing Particle Emissions
• List four major ways to eliminate or reduce emissions from an air
pollution stationary source.
• List three modifications in the operation of a source to reduce the
emissions without the use of air pollution control equipment.
• Recognize the five basic types of control equipment used for control
of particulate emissions.
• Describe the forces used in the collection mechanisms of particle
collection.
Lesson 5 - Settling Chamber: Principles, Operation and Applications
• Describe the collection mechanisms which cause particles to be
collected in a settling chamber.
• List three types of settling chambers.
• Recognize Stokes Law for determining the settling velocity and
calculate the settling velocity of a particle in a settling chamber.
• Recognize and use the equation for determining the minimum particle
size collected in a settling chamber.
• Calculate the collection efficiency of a settling chamber.
• Describe the process design parameters used in designing settling
chambers.
Lesson 6 - Cyclones: Principles, Operation and Applications
• Briefly describe the simple operation of a cyclone for a particle
collection and describe how the gas flows in a cyclone.
• Name the two collection mechanisms used for the collection of
particles in a cyclone.
• Describe the cut size and critical size of a particle.
• Recognize the formula for cut size and calculate the cut size for
a. specific cyclone.
• Calculate the pressure drop across a cyclone using the pressure
drop equation.
• Calculate the collection efficiency of a cyclone using efficiency
curves and particle size distribution data.
Lesson 7 - Electrostatic Precipitator Principles and Operation
• List three structural components of an ESP.
• List three different types of ESP's.
• Identify the three basic functions of an electrostatic precipitator.
• Describe each of the following basic mechanisms of the electrostatic
precipitation process:
• Gas ionization by corona discharge
12
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• Particle charging
• Particle migration to the collection electrode
• Loss of the particle electric charge at the collection electrode
• Electric wind
• Describe the ESP collection electrode cleaning process.
• Write an equation for ESP efficiency calculations.
• List the advantages of the ESP that make it a desirable control device.
Lesson 8 - ESP: Design and Applications
• Describe factors affecting the operation of an electrostatic
precipitator.
• Particle resistivity
• Gas stream parameters
• Gas flow distribution
• Discuss common operating problems of ESP's.
• Describe controls used for the ESP.
• List recommended maintenance and operating procedures for assuring
optimum ESP performance.
Lesson 9 - Fabric Filter Principles
• List three collection mechanisms used in fabric filtration.
• List three simple designs for baghouses.
• List four cleaning mechanisms and briefly describe their operation.
• Name two types of fabric filter material construction and the use
of different fiber types to guard against failure of fabric materials.
• Define pressure drop and recall the simplified formulas for measurement
across the cake and across the fabric.
• Describe the sieving action and the formation of the cake and the
role played in terms of collection efficiency.
• Define filtration velocity and air to cloth ratio and their
role played in terms of fabric filtration performance.
Lesson 10 - Fabric Filter Applications
• Recall the advantages and disadvantages of using fabric filters for
collection of particulates.
• Recall the important design factors that are basic to the design of
the control system.
• Recognize the various industries where baghouses can be used to
collect particulate emissions.
Lesson 11 - Wet Collector Theory
• List the dominant physical mechanisms involved in wet scrubbing.
• Describe the relative effect of particle size, relative velocity and
droplet size on the dimensionless "separation numbers" (target
efficiency) for each mechanism.
13
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• Calculate the average droplet size of a gas atomized spray using
the Nukiyama-Tanasawa relation.
• Define the terms, "inertial impaction parameter", "penetration",
"liquid to gas ratio", "cut diameter", and "transfer on".
• Calculate the collection efficiency for a venturi scrubber using
the Johnstone correlation.
• State the "cut-power" rule developed by Calvert and give the
assumptions associated with the rule.
• Calculate the penetration associated with a given particle cut
diameter and scrubber type using the cut-power rule.
Lesson 12 - Wet Collector Design
• Group the different types of wet scrubbers according to their
mechanism of power input.
• Describe the operation of at least 5 of the following types of
scrubbers using appropriate diagrams.
• Plate
• Gas-atomized spray • Moving bed
• Centrifugal • Preformed spray
• Baffle • Mechanically aided
• Self-induced spray • Packed
• Discuss the performance characteristics of at least 4 different
types of wet collectors, including pressure drop, liquid to gas
ratio and problems associated with the design.
Lesson 13 - Operation and Maintenance of Air Pollution Control Equipment
• Define what an operation/maintenance and inspection program is
and list three major reasons why such a program should be implemented.
• Recognize the Illinois Environmental Protection Agency's proposed
rule dealing with 0/M/I programs.
• List three ways an 0/M/I program can be cost effective.
• Describe the basic steps of an 0/M/I program for a fabric filter
collector and identify the important features of the program.
• Identify two typical inspection reporting forms for fabric filter
collectors.
Lesson 14 - Estimating the Cost of Control Equipment
• List the major economic factors to be considered in selecting
particulate control equipment.
• Estimate the installation cost/ACFM of some types of control equipment.
• Recall generalized formulas for estimating yearly maintenance costs
of various control devices.
14
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SAMPLE AGENDA
Course location
Name and address of
agency conducting course
413 - Control of Particulate Emissions
(Dates of course)
Acknowledgement
of role of other
agencies, if any,
in conduct or
support of
presentation.
Name of course
moderator
DAY & TIME
SUBJECT
SPEAKER
Monday
8:30 - 9:00
9:00 - 10:00
10:00 - 10:15
10:15 - 10:30
10:30 - 12:00
Tuesday
8:30 - 9:00
9:00 - 9:30
9:30 - 10:00
10:00 - 10:15
Introduction and Welcome - Registration
Pre-test
Break
Course Overview
Review of the Basic Concepts
Temp. Pressure, Ideal Gas Law, Conservation Laws
12:00 -
1:00 -
2:00 -
2:30 -
2:45 -
3:45 -
4:15 -
HOMEWORK:
1:00
2:00
2:30
2:45
3:45
4:15
4:30
Lunch
Particle Dynamics
Particle Dynamics, Problem Session I
Break
Particle Sizing
Particle Sizing, Problem Session II
Homework Assignment
Problem 2-3, 413 Student Workbook, p. 5.
Homework Review
Methods for Reducing Particulate Emissions
Settling Chamber Principles, Operation and
Applications
Break
15
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#413 - CONTROL OF PARTICULATE EMISSIONS
Page 2
DAY & TIME
SUBJECT
SPEAKER
Tuesday (continued)
10:15 - 10:30
10:30 - 11:15
11:15 - 12:00
12:00 - 1:00
1:00 - 2:15
2:15 -
2:30 -
3:30 -
2:30
3:30
4:30
Settling Chamber, Problem Session III
Cyclone Principles, Operation & Applications
Cyclone, Problem Session IV
Lunch
Electrostatic Precipitator Principles
and Operation
Break
Electrostatic Precipitator Applications
Electrostatic Precipitator, Problem
Session V
HOMEWORK:
Problem 5-4, 413 Student Workbook, p. 20.
Wednesday
8:30 - 8:45
8:45 - 10:15
10:15 - 10:30
10:30 - 11:00
11:00 - 12:00
12:00 - 1:00
1:00 - 2:15
2:15 - 2:30
2130 - 3:30
3:30 - 4:30
Homework Review
Fabric Filter Principles
Break
Fabric Filter Applications
Fabric Filter, Problem Session VI
Lunch
Wet Collector Theory
Break
Wet Collector, Problem Session VII
Wet Collector Design
HOMEWORK:
Problem 7-4, 413 Student Workbook, p. 29.
Thursday
8:30 - 9:00
9:00 - 10:00
10:00
10:15
11:15
12:00
1:00
1:30
2:30
2:45
10:15
11:15
12:00
1:00
1:30
2:30
2:45
Homework Review
Operation & Maintenance of Air Pollution
Control Equipment
Break
Estimating the Cost of Control Equipment
Pre-test Review
Lunch
Course Overview
Post-test
Course Evaluation
16
ADJOURN
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COURSE #413
REQUIREMENTS FOR AWARD OF CERTIFICATE OF COURSE
COMPLETION AND CONTINUING EDUCATION UNITS
Three (3) Continuing Education Units (CEU's) will be awarded along
with certificate to those students who:
• attend a minimum of 95% of all scheduled class sessions
• complete and hand in copies of all homework exercises = 10 points
• achieve average course grade of 70%
course grade = final exam s-core + homework points
ALL PRE-TESTS, POST-TESTS, AND QUIZZES IN THIS COURSE ARE INTENDED TO
BE OPEN-BOOK. STUDENTS ARE ALLOWED TO USE ANY ADDITIONAL MATERIAL, INCLUDING
SCIENTIFIC CALCULATORS. SUGGESTED TIME ALLOTMENTS FOR EACH ARE AS FOLLOWS:
PRE-TEST 60 minutes
FINAL EXAM 60 minutes
17
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COURSE #413 CONTROL OF PARTICULATE EMISSIONS
PRE—TEST
This Pre-Test is designed to measure how much you know about particulate control
as you begin Course #413. Your score does not affect your final grade in the course.
This exam is intended to be OPEN-BOOK; you may use your books, notes, and
scientific calculator. All answers should be indicated on the attached answer
sheet. You will have sixty minutes to complete the test.
1. A coal fifed power plant sends 2400 ACFM through its electrostatic preci-
pitation. Particle migration velocity is known to be 0.35 feet/second. What
is the collection area if the overall unit efficiency is 99.78%
a. 699.35 ft2
b. 669 ft3
c. 448 ft2
d. 288 ft2
2. An ESP has a single duct with plates 20 ft. high by 24 ft. wide. Inlet grain
loading is 2.82 grains/ft^ and outlet data shows a dust concentration of
0.333 grains/ft^. What is the particle migration velocity if the flow rate
through the ESP is 4,200 ACFM?
a. 0.156 ft/sec
b. 0.328 ft/sec
c. 0.427 ft/sec
d. 0.228 ft/sec
3. Which of the following statements does not apply to a description of the
corona discharge phenomenon in an electrostatic precipitator?
a. A high d-c voltage of negative polarity is applied to the
corona discharge wire
b. The voltage is set for maximum power yet below the level of
excessive sparkover
c. Electrical breakdown of the gas surrounding the discharge wire
occurrs owing to the action of positive ions striking the
discharge wire
d. The intense electrical field near the discharge wire accelerates
electrons
4. Avalanche multiplication describes the action of:
a. Accelerated positive ions striking the discharge wire and
producing free electrons by secondary emissions
b. Corona discharge starting voltage
c. Accelerated electrons ionizing gas molecules by freeing a
valence electron
d. Current density gradient between the discharge electrode and
collection electrode
5. Particles subjected to the electric field and ion bombardment in the area
near the corona discharge will migrate toward the collection electrode
when they reach:
a. The proper dielectric constant
b. Saturation charge
c. Field charge
d. Diffusion charge
18
3/20/80
-------
6. Dust particles with resistivity below 10* ohm-cm are difficult to collect:
a. They rapidly lose their negative charge at the collection electrode
but they can acquire a strong positive charge and spring off the
plate.
b. They act as a resistor in series and lower corona current density
c. They may experience electrical breakdown and produce back corona
d. They do not readily dissipate negative charge and cling to the
collection electrode. They eventually effects the potential
difference between electrodes causing intense sparkover
7. Gas conditioning radically effects particle resistivity. The most common
conditioning agents are:
a. Steam and low resistivity particles
b. Steam and as much as 200 ppm I^SO^
c. Steam and as much as 20 ppm HNCL
d. Steam and as little as 20 ppm NH3 or 863
8. The ESP has very low draft losses. A designer may assure proper gas flow
into the machine by which of the following?
a. Gas turning vanes in the duct elbows
b. Gas turning vanes and an expansion section
c. Turning vanes at duct elbows, an expansion section, and
diffusion screens
d. Smaller induced draft fans
9. Electrical sectionalization improves ESP efficiency for which of the
following reasons?
a. It assures proper spark rate in all sections of the machine
b. Eliminates problems with strong space charge lowering current
density in sections near the ESP outlet
c. Maintains optimum voltage and current density in all sections
d. Both a and c
10. The aspect ratio of a ESP is important for maintaining desired efficiency
for the machine. It is defined as:
a. Ratio of the length to the width for collection plates
b. Ratio of the collection plate height to the length
c. Ratio of the primary power input to collection efficiency
d. Ratio of the inlet dust concentration to collection plate area
11. An inspector in Emit, N. C. examined the control panel of an ESP installed at
a steam generator. The primary voltmeter indicated abnormally low voltage.
The primary ammeter showed cycling current in the machines. What do you
think was the problem with the ESP?
a. Broken wire swinging in a bus section
b. Open transformer
c. Faulty rectifier
d. High dust level in the hoppers
12. An ESP has very low internal power requirements owing to the fact that it:
a. Ionizes incoming gas reducing the total mass that must be cleaned
b. Applies forces as much as 3000 times the force of gravity directly
to particles suspended in a gas stream
c. Corona starting voltage is easily achieved with modern discharge
wire designs
d. Most steam generators have an abundance of cheap power for gas
cleaning operations
19
-------
13. A plant wants to install a cyclone to collect particles from a grinding
operation. If the gas viscosity is 1.34 x 10~° Ib/ft-sec and the inlet
grain loading is 3 grains/ft3, what is the cut size of the particle?
Cyclone inlet width 3 ft.
Effective number of turns 5
Inlet gas velocity 40 ft/sec
Specific gravity of the particle 2.9
Density of water 62.4
a. 1.59 x 10~J° ft.
b. 1.59 x 10~ ft.
c. 9.9 x 10 .ft.
d. 1.26 x 10 ft.
14. The true test of a log normal distribution is:
a. The data plots out as a straight line on semi log paper
b. The area under the curve represents different mass concentrations
between d and d max.
P P
c. The data plots out as a straight line on log probability paper
d. The data plots out bell shaped on log probability paper
15. Industries contemplating the purchase of a wet scrubber system, will
most often obtain an estimated value of the pressure drop by:
a. using the cut-power role
b. guessing
c. using data from a pilot plant
d. using the cut power theory
e. using the Johnstone equation
16. The smallest particle size collected at 100% efficiency by a cyclone is
the:
a. cut size
b. geometric size
c. critical size
d. aerodynamic mean size
20
-------
17. Theoretically, each stage of a cascade impactor would have a particle
diameter cut point which is:
a. 100% efficient
b. 50% efficient
c. .84% efficient
d. 15.87% efficient
18. A 72.7 ym diameter particle moving at it's terminal settling velocity has a
drag coefficient in 70°F air determined to be 12 for the Stokes Law regime
and 12 for the transition regime. What is the Reynolds number?
a. 18.5
b. 2
c. 500
d. 24
19. At some point during its acceleration in a force field, a 500 ym particle,
suspended in a fluid with viscosity y=1.23 x 10~5, and density p=0.075
is characterized by aCjj=0.44 calculated with a transition regime equation.
The Reynolds number corresponds to the dividing point between the transition
regime and Newton's regime. What is the particle velocity?
a. 50 ft/sec
b. 40 ft/sec
c. 100 ft/sec
d. 2.19 ft/sec
20. The cut-power rule assumes that penetration is equal to:
a. in .
i-n
n
b. exp (-A dpa )
21. Contact Power Theory states that:
a. As pressure drop increases, efficiency increases
b. As pressure drop decreases, efficiency increases
c. Complexity of design increases efficiency
d. Complexity of design decreases efficiency
22. What would be a fast way to check the efficiency of an operating wet
scrubber?
a. Compare its operation to that of a pilot unit
b. Do a particle size analysis at the inlet and outlet
c. Use an empirical formulation along with the operating data
d. Use a basic theoretical formulation such as the Johnstone formula
21
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23. At absolute zero a gas has:
a. A temperature of-273.16°C
b. No kinetic energy
c. No pressure
d. All of the above
24. The primary quantities measured in an absolute dimensional system are:
a. Mass, length, force
b. Force, length, time, and mass
c. Mass, length, and time
d. Force, length, and time
25. Absolute pressure when measured at an elevation above sea level is:
a. Measured above a perfect vacuum
b. 29.92 in Hg
c. Required for proper gage pressure readings
d. Pabs - Patm. + Pg
26. If a settling chamber is 20 feet wide, 15 feet high, and 30 feet long,
and the gas flow rate is 25 ft /sec. Calculate the smallest particle
droplet (spherical in shape) that will be entirely collected by the
settler. The specific gravity of the particle is 1.5 and the viscosity
is 1.24 x lO"^ Ib . Assume Stokes law applies
ft-sec
a. 5.39 x 10~5 ft
b. 1.81 x 10~7 ft
c. 2.90 x 10~9 ft
d. 4.25 x HT4 ft
27. Settling chambers are generally used as a pre cleaner to another type
of control equipment. As a general rule of thumb, the through put
velocity should be:
a. at least 50 ft/sec
b. below 10 ft/sec
c. greater than the pick up velocity
d. less than 1 inch H00
22
-------
17. Theoretically, each stage of a cascade impactor would have a particle
diameter cut point which is:
a. 100% efficient
b. 50% efficient
c. .84% efficient
d. 15.87% efficient
18. A 72.7 urn diameter particle moving at it's terminal settling velocity has a
drag coefficient in 70°F air determined to be 12 for the Stokes Law regime
and 12 for the transition regime. What is the Reynolds number?
a. 18.5
b. 2
c. 500
d. 24
19. At some point during its acceleration in a force field, a 500 um particle,
suspended in a fluid with viscosity V-1.23 x 10~5, and density p-0.075 lb/ft3
is characterized by aCD-0.44 calculated with a transition regime equation.
The Reynolds number corresponds to the dividing point between the transition
regime and Newton's regime. What is the particle velocity?
a. 50 ft/sec
b. 40 ft/sec
c. 100 ft/sec
d. 2.19 ft/sec
20. The cut-power rule assumes that penetration is equal to:
1
a. Sin
1-n
•o
b. exp (-A dpa )
c. M p c 1 d
d* Pg + PL
21. Contact Power Theory states that:
a. As pressure drop increases, efficiency increases
b. As pressure drop decreases, efficiency increases
c. Complexity of design increases efficiency
d. Complexity of design decreases efficiency
22. What would be a fast way to check the efficiency of an operating wet
scrubber?
a. Compare its operation to that of a pilot unit
b. Do a particle size analysis at the inlet and outlet
c. Use an empirical formulation along with the operating data
d. Use a basic theoretical formulation such as the Johnstone formula
21
-------
23. At absolute zero a gas has:
a. A temperature of-273.16°C
b. No kinetic energy
c. No pressure
d. All of the above
24. The primary quantities measured in an absolute dimensional system are:
a. Mass, length, force
b. Force, length, time, and mass
c. Mass, length, and time
d. Force, length, and time
25. Absolute pressure when measured at an elevation above sea level is:
a. Measured above a perfect vacuum
b. 29.92 in Hg
c. Required for proper gage pressure readings
d. Pabs = Pa tin. + Pg
26. If a settling chamber is 20 feet wide, 15 feet high, and 30 feet long,
and the gas flow rate is 25 ft /sec. Calculate the smallest particle
droplet (spherical in shape) that will be entirely collected by the
settler. The specific gravity of the particle is 1.5 and the viscosity
is 1.24 x 10~5 Ib . Assume Stokes law applies
ft-sec
a. 5.39 x 10~5 ft
b. 1.81 x 10~ 7 ft
c. 2.90 x 10~9 ft
d. 4.25 x ID'4 ft
27. Settling chambers are generally used as a pre cleaner to another type
of control equipment. As a general rule of thumb, the through put
velocity should be:
a. at least 50 ft/sec
b. below 10 ft/sec
c. greater than the pick up velocity
d. less than 1 inch H^O
22
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28. The collection mechanisms responsible for approximately 99% of the filtering
in a Fabric Filtration system are:
a. diffusion and centrifugal
b. • impaction and interception
c. electrostatic attraction
d. agglomeration and direct interception
29. Bags are cleaned in a baghouse that utilizes a shaking motion by:
a. rapping with a hammer and anvil set-up
b. electrifying the bag cage
c. sonic horns, oscillating motion, or vertical motion
d. rinsing the bags with water
30. Reverse air is a type of cleaning mechanism to clean the bag by:
a. reversing the -air, causing the bag to collapse
b. causing the bag to vibrate, releasing the dust
c. blowing a jet of aircausing the bag to bubble and release
the dust
d. pressurizing the bag
31. Natural fibers used for bags in a baghouse such as cotton and wool have
a. ability to be used for a power plant particle collector
b. a low temperature limitation
c. are very expensive to purchase
d. good resistance to fluoride
32. A fiber that has very good resistance to acidic and alkaline attack
and has a high temperature limitation is
a. cotton
b. Teflon
c. fiberglass
d. wool
33. The pressure drop across the baghouse can be calculated by
a' AP ' APFilter + APcake
b. Ap = Q •* A
c. Ap = (K3-l) * K3
d. Ap = S/v
23
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34. when using a woven material for a bag in a baghouse the efficiency will
be low before
a. high pressure drops occur
b. the open spaces in the weave are bridged and the cake is
formed
c. - an air to cloth ratio 16 to 1 is reached
d. the temperature in the baghouse reaches 300°F
35. In a baghouse a cage for the bag is used in a pressure jet or pulse jet
unit to:
a. help the bags collapse
b. help the bag shake
c. support the bag
d. keep the squirrels out
36. Typical units describing the air to cloth ratio are:
a. cfm/ft^min
b. cfm/ft*
c. ft3/ft2
d. cfm/ft
O
37. A plant has an inlet loading into a baghouse of 10 grains/ft . The
average filtration velocity is 10 ft/min and the gas flow rate is
25,000 ACFM. What is the air to cloth ratio of the system?
a. 250 ft/min
b. 10 cfm/ft2
c. 2500 ft2/min
d. 5 ft/min
38. If a plant has a volumetric flow rate of 18,000 ACFM and a dust loading
of 2 Ib/ft-* of gas filtered, how much filtering area would be required
if the filtration velocity is 2.5 ft/min?
a. 45,000 ft2
b. 36,000 ft2
c. 7200 ft2
d. 9000 ft2
39. How many cylindrical bags, 6 inches in diameter and 25 feet long would be
needed to filter a particulate laden gas stream; the total filtering surface
area is 4045 square feet.
a. 300
b. 162
c. 15
d. 103
24
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40. The geometric standard deviation is calculated for a log normal
distribution by dividing
a. 50% size
b. 50% size/84.13% size
c. ' 15.87 size/2.28% size
d. dp max/Alog dp max
41. The geometric mean particle diameter occurs at:
a . 15.87% fraction
b. 50% fraction
c. 84.13% fraction
d. 97.72% fraction
42. In a cyclone, the cut size of a particle is the size of the particle
a. collected with 100% efficiency
b. less than 20 microns
c. collected with 50% efficiency
d. which will not be collected
43. In a cyclone the eddie currents can be eliminated by use of
a. vortex arrester
b. outer vortex
c. eductor
d. dust hopper
44. In a cyclone the inlet gas velocity is transformed into a vortex which
is confined within the structure. The particles are collected when
a. the particles are thrown against the wall by centrifugal
force and fall into the dust hopper
b. the spiral of the vortex changes direction
c. Drag force is greater than the centrifugal force
d. vortex finder corrects with the vortex arrestor
45. The energy used to contact particulates with liquid in an impingement
plate scrubber is supplied by
a. the gas stream
b. the liquid stream
c. a mechanically driven motor
d. a thin film
46. An example of a high energy scrubber would be
a. a countercurrent spray tower
b. a turbulent contact absorber
c. a centrifugal scrubber
d. a venturi scrubber
25
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47. What would be a characteristic pressure drop for a medium energy
scrubber such as a self-induced spray scubber (impingement-entrainment
scrubber?
a. 1" H20
b. 5" H20
c. 20" H20
d. 100" H20
48. The Nukiyama-Tanasawa relationship is used to estimate
a. particle size
b. liquid to gas ratio
c. water droplet size
d. the relative velocity of particulate matter to water
droplets
49. Which one of the methods give below uses the transfer number N = ^
to estimate scrubber collection efficiency?
a. the cut-power rule
b. the Johnstone equation
c. The Nukiyama-Tanasama correlation
d. the contact-power theory
50. What is the most common collection mechanism employed in wet scrubbers?
a. inertial impaction
b. direct interception
c. Brownian diffusion
d. gravitation
26
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Name
COURSE #413 CONTROL OF PARTICIPATE EMISSIONS
PRE-TEST
ANSWER SHEET
1. a b c d 25. a b c d 49. a b c d
2. a b c d 26. a b c d 50. a b c d
3. a b c d 27. a b c d
4. a b c d 28. a b c d
5. a b c d 29. a b c d
6. a b c d 30. a b c d
7. abed 31. abed
8. a b c d 32. a b c d
9. a b c d 33. a b c d
10. a b c d 34. a b c d
11. a b c d 35. a b c d
12. a b c d 36. a b c d
13. a b c d 37. a b c d
14. a b c d 38. a b c d
15. a b c d e 39. a b c d
16. a b c d 40. a b c d
17. a b c d 41. a b c d
18. a b c d 42. a b c d
19. a b c d 43. a b c d
20. a b c d 44. a b c d
21. a b c d 45. a b c d
22. a b c d 46. a b c d
23. a b c d 47. a b c d
24. abed 48. abed
27
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COURSE #413 CONTROL OF PARTICULATE EMISSIONS
KEY
PRE-TEST
This Pre-Test is designed to measure how much you know about particulate control
as you begin Course #413. Your score does not affect your final grade in the course.
This exam is intended to be OPEN-BOOK; you may use your books, notes, and
scientific calculator. All answers should be indicated on the attached answer
sheet . " — — —
1. A coal fifed power plant sends 2400 ACFM through its electrostatic preci-
pitation. Particle migration velocity is known to be 0.35 feet/second. What
is the collection area if the overall unit efficiency is 99.78%
0 699.35 ft2
b. 669 ft3
c. 448 ft2
d. 288 ft2
2. An ESP has a single duct with plates 20 ft. high by 24 ft. wide. Inlet grain
loading is 2.82 grains/ft3 and outlet data shows a dust concentration of
0.333 grains/ft3. What is the particle migration velocity if the flow rate
through the ESP is 4,200 ACFM?
(g) 0.156 ft/sec
b. 0.328 ft/sec
c. 0.427 ft/sec
d. 0.228 ft/sec
3. Which of the following statements does not apply to a description of the
corona discharge phenomenon in an electrostatic precipitator?
a. A high d-c voltage of negative polarity is applied to the
corona discharge wire
b. The voltage is set for maximum power yet below the level of
excessive sparkover
(c) Electrical breakdown of the gas surrounding the discharge wire
occurrs owing to the action of positive ions striking the
discharge wire
d. The intense electrical field near the discharge wire accelerates
electrons
4. Avalanche multiplication describes the action of:
a. Accelerated positive ions striking the discharge wire and
producing free electrons by secondary emissions
b. Corona discharge starting voltage
(c) Accelerated electrons ionizing gas molecules by freeing a
valence electron
d. Current density gradient between the discharge electrode and
collection electrode
5. Particles subjected to the electric field and ion bombardment in the area
near the corona discharge will migrate toward the collection electrode
when they reach:
a. The proper dielectric constant
(£) Saturation charge
c. Field charge
d. Diffusion charge
28
/ 3/20/80
-------
6. Dust particles with resistivity below 104 ohm-cm are difficult to collect:
(a) They rapidly lose their negative charge at the collection electrode
but they can acquire a strong positive charge and spring off the
plate.
b. They act as a resistor in series and lower corona current density
c. They may experience electrical breakdown and produce back corona
d. They do not readily dissipate negative charge and cling to the
collection electrode. They eventually effects the potential
difference between electrodes causing intense sparkover
7. Gas conditioning radically effects particle resistivity. The most common
conditioning agents are:
a. Steam and low resistivity particles
b. Steam and as much as 200 ppm I^SO^
c. Steam and as much as 20 ppm HN03
(JT) Steam and as little as 20 ppm NH3 or 803
8. The ESP has very low draft losses. A designer may assure proper gas flow
into the machine by which of the following?
a. Gas turning vanes in the duct elbows
b. Gas turning vanes and an expansion section
(^ Turning vanes at duct elbows, an expansion section, and
diffusion screens
d. Smaller induced draft fans
9. Electrical sectionalization improves ESP efficiency for which of the
following reasons?
a. It assures proper spark rate in all sections of the machine
b. Eliminates problems with strong space charge lowering current
density in sections near the ESP outlet
c. Maintains optimum voltage and current density in all sections
(S\ Both a and c
10. The aspect ratio of a ESP is important for maintaining desired efficiency
for the machine. It is defined as:
a. Ratio of the length to the width for collection plates
(S\ Ratio of the collection plate height to the length
c. Ratio of the primary power input to collection efficiency
d. Ratio of the inlet dust concentration to collection plate area
11. An inspector in Emit, N. C. examined the control panel of an ESP installed at
a steam generator. The primary voltmeter indicated abnormally low voltage.
The primary ammeter showed cycling current in the machines. What do you
think was the problem with the ESP?
(a) Broken wire swinging in a bus section
b. Open transformer
c. Faulty rectifier
d. High dust level in the hoppers
12. An ESP has very low internal power requirements owing to the fact that it:
a. Ionizes incoming gas reducing the total mass that must be cleaned
(b) Applies forces as much as 3000 times the force of gravity directly
to particles suspended in a gas stream
c. Corona starting voltage is easily achieved with modern discharge
wire designs
d. Most steam generators have an abundance of cheap power for gas
cleaning operations
29
-------
COURSE #413 CONTROL OF PARTICTJLATE EMISSIONS
KEY
PRE-TEST
This Pre-Test is designed to measure how much you know about particulate control
as you begin Course #413. Your score does not affect your final grade in the course.
This exam is intended to be OPEN-BOOK; you may use your books, notes, and
scientific calculator. All answers should be indicated on the attached answer
sheet . ~~
1. A coal fired power plant sends 2400 ACFM through its electrostatic preci-
pitation. Particle migration velocity is known to be 0.35 feet/second. What
is the collection area if the overall unit efficiency is 99.78%
2
699.35 ft
b. 669 ft3
c. 448 ft2
d. 288 ft2
2. An ESP has a single duct with plates 20 ft. high by 24 ft. wide. Inlet grain
loading is 2.82 grains /ft^ and outlet data shows a dust concentration of
0.333 grains/ft^. What is the particle migration velocity if the flow rate
through the ESP is 4,200 ACFM?
(g) 0.156 ft/sec
b. 0.328 ft/sec
c. 0.427 ft/sec
d. 0.228 ft/sec
3. Which of the following statements does not apply to a description of the
corona discharge phenomenon in an electrostatic precipitator?
a. A high d-c voltage of negative polarity is applied to the
corona discharge wire
b. The voltage is set for maximum power yet below the level of
excessive sparkover
(^ Electrical breakdown of the gas surrounding the discharge wire
occurrs owing to the action of positive ions striking the
discharge wire
d. The intense electrical field near the discharge wire accelerates
electrons
4. Avalanche multiplication describes the action of:
a. Accelerated positive ions striking the discharge wire and
producing free electrons by secondary emissions
b. Corona discharge starting voltage
(c) Accelerated electrons ionizing gas molecules by freeing a
valence electron
d. Current density gradient between the discharge electrode and
collection electrode
5( Particles subjected to the electric field and ion bombardment in the area
near the corona discharge will migrate toward the collection electrode
when they reach:
a. The proper dielectric constant
(b) Saturation charge
c. Field charge
d. Diffusion charge
28
/ 3/20/80
-------
17- Theoretically, each stage of a cascade impactor would have a particle
diameter cut point which is:
0 100% efficient
b. 50% efficient
c. .84% efficient
d. 15.87% efficient
18. A 72.7 urn diameter particle moving at it's terminal settling velocity has a
drag coefficient in 70°F air determined to be 12 for the Stokes Law regime
and 12 for the transition regime. What is the Reynolds number?
a. 18.5
® 2
c. 500
d. 24
19. At some point during its acceleration in a force field, a 500 um particle,
suspended in a fluid with viscosity P=1.23 x 10"^, and density p=0.075 Ib/ft
is characterized by aCD=0.44 calculated with a transition regime equation.
The Reynolds number corresponds to the dividing point between the transition
regime and Newton's regime. What is the particle velocity?
(a) 50 ft/sec
b. 40 ft/sec
c. 100 ft/sec
d. 2.19 ft/sec
20. The cut-power rule assumes that penetration is equal to:
a . in -,
1-n
^•^ TJ
(jy exp (-A dpa )
d. pg + pL
21. Contact Power Theory states that:
(a) As pressure drop increases, efficiency increases
b. As pressure drop decreases, efficiency increases
c. Complexity of design increases efficiency
d. Complexity of design decreases efficiency
22. What would be a fast way to check the efficiency of an operating wet
scrubber?
a. Compare its operation to that of a pilot unit
b. Do a particle size analysis at the inlet and outlet
(c) Use an empirical formulation along with the operating data
d. Use a basic theoretical formulation such as the Johnstone formula
31
-------
13. A plant wants to install a cyclone to collect particles from a grinding
operation. If the gas viscosity is 1.34 x 1(T° Ib/ft-sec and the inlet
grain loading is 3 grains/ft3, what is the cut size of the particle?
Cyclone inlet width 3 ft.
Effective number of turns 5
Inlet gas velocity 40 ft/sec
Specific gravity of the particle 2.9
Density of water 62.4
a. 1.59 x 10~J° ft.
b. 1.59 x 10'^ ft.
c. 9.9 x 10 ft.
0 1.26 x 10 ft.
14. The true test of a log normal distribution is:
a. The data plots out as a straight line on semi log paper
b. The area under the curve represents different mass, concentrations
between d and d max.
P P
(c) The data plots out as a straight line on log probability paper
d. The data plots out bell shaped on log probability paper
15. Industries contemplating the purchase of a wet scrubber system, will
most often obtain an estimated value of the pressure drop by:
a. using the cut-power rule
b. guessing
Q using data from a pilot plant
d. using the cut power theory
e. using the Johnstone equation
16. The smallest particle size collected at 100% efficiency by a cyclone is
the:
a. cut size
b. geometric size
(c) critical size
cU aerodynamic mean size
30
-------
23. At absolute zero a gas has:
a. A temperature of-273.16°C
b. Ho kinetic energy
c. No pressure
(a) All of the above
24. The primary quantities measured in an absolute dimensional system are:
a. Mass, length, force
b. Force, length, time, and mass
(£) Mass, length, and time
d. Force, length, and time
25. Absolute pressure when measured at an elevation above sea level is:
a. Measured above a perfect vacuum
b. 29.92 in Hg
c. Required for proper gage pressure readings
(3) Pabs = Patm. + Pg
26. If a settling chamber is 20 feet wide, 15 feet high, and 30 feet long,
and the gas flow rate is 25 ft3/sec. Calculate the smallest particle
droplet (spherical in shape) that will be entirely collected by the
settler. The specific gravity of the particle is 1.5 and the viscosity
is 1.24 x 10~5 lb . Assume Stokes law applies
ft-sec
(a) 5.39 x 10"5 ft
b; 1.81 x 10-7 ft
c. 2.90 x 10~9 ft
d. 4.25 x lO-4 ft
27. Settling chambers are generally used as a pre cleaner to another type
of control equipment. As a general rule of thumb, the through put
velocity should be:
a. at least 50 ft/sec
(b) below 10 ft/sec
c. greater than the pick up velocity
d. less than 1 inch H.O
32
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28. The collection mechanisms responsible for approximately 99% of the filtering
in a Fabric Filtration system are:
a. diffusion and centrifugal
(D)• impaction and interception
c. electrostatic attraction
d. agglomeration and direct interception
29. Bags are cleaned in a baghouse that utilizes a shaking motion by:
a. rapping with a hammer and anvil set-up
b. electrifying the bag cage
(c^ sonic horns, oscillating motion, or vertical motion
a. rinsing the bags with water
30. Reverse air is a type of cleaning mechanism to clean the bag by:
(a) reversing the -air, causing the bag to collapse
D. causing the bag to vibrate, releasing the dust
c. blowing a jet of aircausing the bag to bubble and release
the dust
d. pressurizing the bag
31. Natural fibers used for bags in a baghouse such as cotton and wool have
a. ability to be used for a power plant particle collector
(b) a low temperature limitation
c. are very expensive to purchase
d. good resistance to fluoride
32. A fiber that has very good resistance to acidic and alkaline attack
and has a high temperature limitation is
a. cotton
(fj) Teflon
c. fiberglass
d. wool
33. The pressure drop across the baghouse can be calculated by
© *P • APFilter + APcake
b. Ap « Q * A
c. Ap - (K3-l) * K3
d. Ap « S/vt
33
-------
34. When using a woven material for a bag in a baghouse the efficiency will
be low before
a. high pressure drops occur
(S) the open spaces in the weave are bridged and the cake is
formed
c. • an air to cloth ratio 16 to 1 is reached
d. the temperature in the baghouse reaches 300°F
35. In a baghouse a cage for the bag is used in a pressure jet or pulse jet
unit to:
a. help the bags collapse
b. help the bag shake
(c^ support the bag
a. keep the squirrels out
36. Typical units describing the air to cloth ratio are:
a. cfm/ft-min
© cfm/ft2
c. ftj/ft2
d. cfm/ft
«5
37. A plant has an inlet loading into a baghouse of 10 grains/ft . The
average filtration velocity is 10 ft/min and the gas flow rate is
25,000 ACFM. What is the air to cloth ratio of the system?
a. 250 ft/min
(£) 10 cfm/ft
c. 2500 ft2/min
d. 5 ft/min
38. If a plant has a volumetric flow rate of 18,000 ACFM and a dust loading
of 2 lb/ft^ of gas filtered, how much filtering area would be required
if the filtration velocity is 2.5 ft/min?
a. 45,000 ft2
b. 36,000 ft2
Q 7200 ft2
d. 9000 ft2
39. How many cylindrical bags, 6 inches in diameter and 25 feet long would be
needed to filter a particulate laden gas stream; the total filtering surface
area is 4045 square feet.
a. 300
b. 162
c. 15
(5) 103
34
-------
AO. The geometric standard deviation is calculated for a log normal
distribution by dividing
a. 50% size
0 50% size/84.13% size
c. ' 15.87 size/2.28% size
d. dp max/Alog dp max
41. The geometric mean particle diameter occurs at:
a . 15.87% fraction
@ 50% fraction
c. 84.13% fraction
d. 97.72% fraction
42. In a cyclone, the cut size of a particle is the size of the particle
a. collected with 100% efficiency
b. less than 20 microns
^) collected with 50% efficiency
d. which will not be collected
43. In a cyclone the eddie currents can be eliminated by use of
a. vortex arrestor
b. outer vortex
(£) eductor
d. dust hopper
44. In a cyclone the inlet gas velocity is transformed into a vortex which
is confined within the structure. The particles are collected when
(a) the particles are thrown against the wall by centrifugal
force and fall into the dust hopper
b. the spiral of the vortex changes direction
c. Drag force is greater than the centrifugal force
d. vortex finder corrects with the vortex arrestor
45. The energy used to contact particulates with liquid in an impingement
plate scrubber is supplied by
(a) the gas stream
b. the liquid stream
c. a mechanically driven motor
d. a thin film
46. An example of a high energy scrubber would be
a. a countercurrent spray tower
b. a turbulent contact absorber
c. a centrifugal scrubber
(d) a venturi scrubber
35
-------
47. What would be a characteristic pressure drop for a medium energy
scrubber such as a self-induced spray scubber (impingement-entrainment
scrubber?
a. 1" H20
0 5" H20
c. 20" H20
d. 100" H20
48. The Nukiyama-Taaasawa relationship is used to estimate
a. particle size
b. liquid to gas ratio
@ water droplet size
a. the relative velocity of particulate matter to water
droplets
49. Which one of the methods give below uses the transfer number N = in (--3--1
to estimate scrubber collection efficiency? * '
a. the cut-power rule
b. the Johnstone equation
c. The Nukiyama-Tanasama correlation
(3) the contact-power theory
50. What is the most common collection mechanism employed in wet scrubbers?
(a) inertial impaction
b. direct interception
c. Brownian diffusion
d. gravitation
36
-------
Name GRADING KEY
COURSE #413 CONTROL OF PARTICULATE EMISSIONS
PRE-TEST
All questions are 2 Points
SHEET
1. © b c d
2. © b c d
3. a b © d
4. a b © d
5. a © c d
6. © bed
7. a b c ©
8. a b © d
9. a b c (d)
10. a © c d
11. © b c d
12. a © c d
13. a b c ©
14. a b © d
15. a b © d e
16. a b © d
17. © b c d
18. a © c d
19. © b c d
20. a © c d
21. © bed
22. a b © d
23. a b c 0
24. a b © d
25. a b
26. © b
27. a ©
28. a ©
29. a b
30. © b
31. a ©
32. a ©
33. © b
34. a ©
35. a b
36. a ©
37. a ©
38. a b
39. a b
40. a ©
41. a ©
42. a b
43. a b
44. © b
45. © b
46. a b
47. a ©
48. a b
37
c (a)
c d
c d
c d
© d
c d
c d
c d
c d
c d
© d
c d
c d
© d
c (d)
c d
c d
© d
© d
c d
c d
c (d)
c d
fa d
49. a b c (d)
50. (a) b c d
3/20/80
-------
COURSE #413 CONTROL OF PARTICULATE EMISSIONS
POST-TEST
This exam Is designed to measure how well the objectives for Course #413
have been met. It is intended to be an OPEN-BOOK exam; you should use your
notes and books. You may also use a scientific calculator. Indicate all your
answers on the attached answer sheet. YOU will have sixty minutes to complete
the test.
1. The cut diameter for a particular dust was found to be 25 microns
using a given cyclone. If the inlet velocity were doubled, what
would the cut diameter be?
a. 21.6 microns
b. 14.5 microns
c. 17.7 microns
d. 10.2 microns
2. Tests showed that filtration of a dusty air stream containing 2 grains
of particulates,per cubic foot of air gave a maximum pressure drop of
10 inches of water at a flow rate of 3 ft per square foot of filtering
surface. What is the number of 1 ft diameter by 20 ft filtering bags
required if the exhaust volume is 10,000 ACFM?
a. 45 bags
b. 53 bags
c. 100 bags
d. 65 bags
3. The size of the particle which is removed with 50% efficiency is the:
a. mean size
b. critical size
c. cut size
d. mode
4. The presence of S0_ in the carrier gas favors the electrostatic
precipitator process by:
a. increasing resistivity
b. aiding surface conduction of electricity conditioning for high resistivity
c. improving agglomeration
d. increasing electrical wind
5. Shaking, reverse-air, pulse jet, and sonic horns are methods used for:
a. evacuating buildings
b. cleaning fabric filters
c. reducing dust loads
d. collecting moist particulates
6. The larger the mean particle size of a dust through a cyclone, the higher
the value of the:
a. pressure drop
b. inlet velocity
c. dust concentration
d. efficiency 38
3/20/80
-------
7. In an electrostatic precipitator the migration velocity is 0.5 ft/sec
and the plate area is 10,000 sq. ft. The efficiency of the precipitator
is 95.5%. What was the flow rate through the precipitation?
a. 71,500 cfm
b. 65,000 cfm
c. 1,100 cfs
d. 1,600 cfs
8. The pressure drop through a filter is 2.5 inches of water with a filter
velocity of 3 ft. per minute. If the velocity dropped to 2.7 ft. per
minute, what would the pressure drop be assuming that the filter drag
remains constant?
a. 1.67
b. 1.33
c. 3.75
d. 2.25
9. Weight efficiency is defined as:
-z
a.
b.
c.
E = 1
W.
p i
«i
W
E^
- e
- W
o
- W
c
W. - W
d. E=-
10. An increase in the collecting area of an electrostatic precipitator will:
a. increase flow rate
b. decrease migration velocity
c. have no effect
d. increase efficiency
1-1. The effectiveness of control equipment for different particle sizes
is shown by:
a. size efficiency curves
b. overall efficiency
c. log-probability plots
d. cumulative distribution curves
12. The Reynold's Number (ND ):
Ke
a. describes fluid flow and is equal to yC /pDQ
b. equals 6.02 x 10 P
c. describes how a fluid behaves while flowing and is defined as
the inertial forces divided by the viscous forces (Dvp/y)
d. is generally used only for liquids
39
-------
13. When a free-falling particle has attained its terminal velocity:
a. air resistance is negligible
b. gravity is the only force acting on the particle
c. the particle must have stopped on the surface of a stationary object -
d. the air resistance is just balanced by gravitational attraction
14. The smallest particle size which is collected at 100% efficiency by a
cyclone is the
a. cut size
b. geometric mean
c. critical size
d. design efficiency size
15. The units of the air-to-cloth ratio in fabric filter design are
a. volumetric flow rate units
b. volume/area units
c. unitless
d. volumetric flow rate/area units
16. A cyclone spray scrubber is an example of a scrubber where contacting power
is obtained from
a. the gas stream only
b. the liquid stream only
c.' both the gas and liquid stream
d. a mechanically driven rotor
17. Which of the following theories expresses the pressure drop across a wet
scrubber without an empirical correlation?
a. contact power theory
b. cut-power theory
c. the Johnstone equation
d. Nukiyama-Tanasawa relationship
e. none of the above
18. If a 200 ml container of gas is heated from 40°C to 80 C at constant pressure,
what is the volume of the gas?
a. 225.6 ml
b. 258-. 6
c. 100 ml
d. 400 ml
19. To remove particulate matter of lym diameter, venturi scrubbers commonly
operate with a pressure drop in the range of
a. 20-30 inches of water
b. 90-100 inches of water
c. .5-1.5 inches of water
d. 60-80 inches of water
40
-------
20. The ideal gas law can be represented as:
a. Pi-T^
if
b. V = — at constant T
c. P = K T at constant V
d. PV = | RT
21. Cunningham correction factor is used to:
a. correct the stack gas to standard conditions
b. correct the drag coefficient for fluid flow in the laminar regime
c. determine the settling velocity of a particle in the turbulent regime
d. determine the aerodynamic drag force on a particle
22. A major advantage in using an electrostatic precipitator is that the
force for collection is
a. impaction on the collection plate with good collection efficiency
b. centrifugal and gravity to fall into the hopper
c. electrical force with subsequent interception on the discharge electrode
d. applied only to the particle enabling low pressure drops through the
collector
23. When collecting particle size data using an in-stack inertial impactor,
the size of the particle data collected is given as the:
a. aerodynamic diameter of the particle
b. geometric diameter of the particle
c. Martin's diameter
d. extended area of the particle
24. In a self-induced spray scrubber
a. liquid is injected as high pressure
b. the gas atomizes the liquid
c. particulate matter is removed by cyclonic deposition on the packing
d. gas flow is counter-current
25. Particles collected at the collection electrode of an electrostatic
precipitator are usually removed by
a. reversing the flow of air in the collector
b. rapping the electrode by mechanical or electrical mechanism
c. reversing the charge of collection plate
d. creating a vacuum and pulling dust into the hopper
26. In the contact power and cut-power rule, penetration is defined as:
a. 1 - n (where n = efficiency)
b. C./C (inlet particle concentration/outlet particle concentration)
c. equal to the total pressure loss, PT
d. being a constant equal to 2.0 for most inertial wet scrubbers
41
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33. The geometric standard deviation of a log-normal distribution:
a. is the average particle diameter of the distribution
b. can be obtained directly from a plot of particle size versus
cumulative percent greater than, on log-probability paper
c. is the 50% size on the log-probability paper
d. given as the 84.13% size divided by the 15.87% size
34. A dominant mechanism in the wet collection of particulate matter is:
a. gravitational force
b. electrostatic force
c. inertial impaction
d. direct interception
35. The migration velocity for a typical design for an ESP is described as
a. effective drift speed of the particle towards the collection electrode
b. being dependent on back corona and spark over
c. being independent of the particle size
d. speed in which the rappers must be activated
36. Particles in a gas stream with high resistivity will
a. migrate to collection electrode and take on the charge of the plate
b. rapidly lose a negative charge
c. readily accept the charge from the discharge wire
d. cause electrical breakdown and spark over
37. Contact power theory is based on the observation that:
a. collection efficiency increases as pressure drop increases
b. condensation of water on particulate matter increases particle size
c. penetration is an exponential function of the cut diameter
d. pilot system parameters may be scaled to larger units
38. In pulse-jet baghouses the cleaning mechanism used for cleaning the
bags is:
a. reversing the flow of air through the compartment
b. blast of air into each bag knocking the dust away from the bag
c. blast of air to the outside of the bag
d. pulsating air causing the bags to shake
39. Proper air-to-cloth ratio is
a. the measure of amount of dust deposited on the filter
b. imperative for good design and prevention of premature bag failure
c. often referred to as low filter drag
d. is less than 8 inches of water
43
-------
27. Which of the following is not an integral component in an electrostatic
precipitator?
a. rappers
b. collection plate
c. discharge electrode
d. venturi control rod
28. The settling velocity of a particle collected in a settling chamber can
be determined by the following formula:
a v -
a* v
g d 2(p -p)
b' V= 18yP
, dv
a. v = -7— ma
dt
29. A common liquid to gas ratio for a preformed spray scrubber would be
a. 5-20 gal/1000 ft3
b. .01-.5 gal/1000 ft3
c. 50-70 gal/1000 ft3
d. >80 gal/1000 ft3
30. A Raschig ring would be used
a. around the throat of a venturi scrubber
b. in a cyclonic separator before the pad demister
c. at the top of a cyclonic spray scrubber
d. in a crossflow packed scrubber
31. A log-normal distribution plot is a straight line on:
a. arithmetic graph paper
b. semi-log paper
c. log-probability paper
d. log-log paper
32. Particles are charged in an ESP by
a. subjecting the particles to high humidity
b. corona produced by the discharge electrode when a high voltage
is applied
c. positive corona generated by the collection electrode
d. intense electrical field by applying a-c voltage to discharge wire
42
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Name
COURSE #413 CONTROL OF PARTICULATE EMISSIONS
POST-TEST
ANSWER SHEET
1. a b c d 26. a b c d
2. a b c d 27. a b c d
3. abed 28. abed
4. a b c d 29. a b c d
5. a b c d 30. a b c d
6. a b c d 31. a b c d
7. a b c d 32. a b c d
8. a b c d 33. a b c d
9. a b c d 34. a b c d
10. a b c d 35. a b c d
11. abed 36. abed
12. a b c d 37. a b c d
13. a b c d 38. a b c d
14. a b c d 39. a b c d
15. a b c d 40. a b c d
16. a b c d 41. a b c d
17. a b c d e 42. a b c d
18. a b c d 43. a b c d
19. a b c d 44. a b c d
20. a b c d 45. a b c d
21. abed 46. abed
22. a b c d 47. a b c d
23. a b c d 48. a b c d
24. a b c d 49. a b c d
25. a b c d 50. a b c d
46
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40. Ingot Iron and Steel Company has submitted particle size data for dust
from their basic oxygen furnace. The data was collected using a Bahco
microparticle classifier. The instrument:
a. measures the geometric diameter of the particle collected with an
EPA Method 5 sampling train
b. measures particle size by passing the particle through a light beam
c. measures the particle's mobility due to its charge
d. uses a combination of elutriation and centrifugation to separate
particles from a weighted sample yielding subsequent particle size data
41. The sieving action plays an important role in
a. measurement of pressure drop across a felted filter
b. eliminating the need for woven fabrics
c. designing multi-compartment baghouses
d. collecting large particles to build the cake for subsequent collection
of small particles
42. In a venturi scrubber, efficiency increases when the relative gas to
liquid velocity
a. fluctuates
b. decreases
c. increases
d. stabilizes
43. An advantage of using felted material for bag construction in a baghouse
is:
a. that larger air-to-cloth ratios are possible
b. they provide lower pressure drops
c. they take longer for the cake to form
d. resistant to acidic gas streams
44. Using contact power theory, estimate the total pressure loss in the
system if the pressure drop is 5" H_0 and the liquid to gas ratio is
15 gal/1000 ft , with a liquid inlet pressure of lOOOpsi.
a. 8750
b. 1005
c. 8.75
d. 9.53
45. The pressure drop across a baghouse for shaker or reverse air cleaning
type baghouses is:
a. pressure drop across the cake
b. pressure drop across the shell
c. pressure drop across the cake plus the filter
d. inlet pressure plus the outlet pressure
44
-------
46. Filter drag for fabric filters is a function of
a. quantity of dust accumulated on the filter
b. resistance to air from the filter
c. zone of cake repair
d. force opposing filtration
47- What is the efficiency of a wet scrubber if the overall penetration
was found to be .02 by the cut-power theory?
a. 20%
b. 98%
c. 2%
d. 99%
48. The specific collecting area for an Electrostatic Precipitator is given by
a. the electrical wind
b. migration velocity
c. resistivity of the particle
d. A/Q, area divided by the gas volume
49. The dust from a cement kiln is sent to an electrostatic precipitator
at 1,600 cfm. The particle migration velocity was measured to be .25
ft/sec. What is the collection efficiency if the collection area is
8000 sq. ft.?
a. 95.8%
b. 95.0%
c. 4.8%
d. 98.2%
50. A multicyclone is used in many applications for collecting dust. The
efficiency of a multicyclone for particles greater than 10 microns can
be as high as
a. 100%
b. 65%
c. 80%
d. 90%
45
-------
COURSE #413 CONTROL OF PARTICIPATE EMISSIONS
POST-TEST ANSWER KEY
This exam is designed to measure how well the objectives for Course #413
have been met. It is intended to be an OPEN-BOOK exam; you should use your
notes and books. You may also use a scientific calculator. Indicate all your
answers on the attached answer sheet.
1. The cut diameter for a particular dust was found to be 25 microns
using a given cyclone. If the inlet velocity were doubled, what
would the cut diameter be?
a. 21.6 microns
b. 14.5 microns
(c) 17.7 microns
d. 10.2 microns
2. Tests showed that filtration of a dusty air stream containing 2 grains
of particulates per cubic foot of air gave a maximum pressure drop of
10 inches of water at a flow rate of 3 ft per square foot of filtering
surface. What is the number of 1 ft diameter by 20 ft filtering bags
required if the exhaust volume is 10,000 ACFM?
a. 45 bags
(D 53 bags
c. 100 bags
d. 65 bags
3. The size of the particle which is removed with 50% efficiency is the:
a. mean size
b. critical size
(c) cut size
a. mode
4. The presence of SO- in the carrier gas favors the electrostatic
precipitator process by:
a. increasing resistivity
(B)i aiding surface conduction of electricity conditioning for high resistivity
c. improving agglomeration
d. increasing electrical wind
5. Shaking, reverse-air, pulse jet, and sonic horns are methods used for:
a. evacuating buildings
(S) cleaning fabric filters
c. reducing dust loads
d. collecting moist particulates
6. The larger the mean particle size of a dust through a cyclone, the higher
the value of the:
a. pressure drop
b. inlet velocity
c. dust concentration
(dj efficiency
47
-------
7. In an electrostatic precipitator the migration velocity is 0.5 ft/sec
and the plate area is 10,000 sq. ft. The efficiency of the precipitator
is 95.5%. VThat was the flow rate through the precipitation?
a. 71,500 cfm
b. 65,000 cfm
c. 1,100 cfs
0 1,600 cfs
8. The pressure drop through a filter is 2.5 inches of water with a filter
velocity of 3 ft. per minute. If the velocity dropped to 2.7 ft. per
minute, what would the pressure drop be assuming that the filter drag
remains constant?
a. 1.67
b. 1.33
c. 3.75
@) 2.25
9. Weight efficiency is defined as:
a. E = 1 - e~z
W. - W
w. - w
1 C
w
c. E -
W. - W
10. An increase in the collecting area of an electrostatic precipitator will:
a. increase flow rate
b. decrease migration velocity
c. have no effect
(3)i increase efficiency
tl. The effectiveness of control equipment for different particle sizes
is shown by:
(a) size efficiency curves
b. overall efficiency
c. log-probability plots
d. cumulative distribution curves
12. The Reynold's Number (N_ ):
Ke
a. describes fluid flow and is equal to yC /pDQ
b. equals 6.02 x 10 P
(c\ describes how a fluid behaves while flowing and is defined as
the inertial forces divided by the viscous forces (Dvp/y)
d. is generally used only for liquids
48
-------
13. When a free-falling particle has attained its terminal velocity:
a. air resistance is negligible
b. gravity is the only force acting on the particle
c. the particle must have stopped on the surface of a stationary object
(3) the air resistance is just balanced by gravitational attraction
14. The smallest particle size which is collected at 100% efficiency by a
cyclone is the
a. cut size
b. geometric mean
(c) critical size
d. design efficiency size
15. The units of the air-to-cloth ratio in fabric filter design are
a. volumetric flow rate units
b. volume/area units
c. unitless
(3) volumetric flow rate/area units
16. A cyclone spray scrubber is an example of a scrubber where contacting power
is obtained from
a. the gas stream only
b. the liquid stream only
(£)• both the gas and liquid stream
cf. a mechanically driven rotor
17- Which of the following theories expresses the pressure drop across a wet
scrubber without an empirical correlation?
a. contact power theory
b. cut-power theory
c. the Johnstone equation
d. Nukiyama-Tanasawa relationship
(e\ none of the above
18. If a 200 ml container of gas is heated from 40°C to 80°C at constant pressure,
what is the volume of the gas?
@ 225.6 ml
b. 258.6
c. 100 ml
d. 400 ml
19. To remove particulate matter of lym diameter, venturi scrubbers commonly
operate with a pressure drop in the range of
(a) 20-30 inches of water
b. 90-100 inches of water
c. .5-1.5 inches of water
d. 60-80 inches of water
49
-------
20. The ideal gas law can be represented as:
a. Pi-T^
£
b. V « — at constant T
c. P = K T at constant V
(3> pV = g RT
^—^ n
21. Cunningham correction factor is used to:
a. correct the stack gas to standard conditions
(B) correct the drag coefficient for fluid flow in the laminar regime
c. determine the settling velocity of a particle in the turbulent regime
d. determine the aerodynamic drag force on a particle
22. A major advantage in using an electrostatic precipitator is that the
force for collection is
a. impaction on the collection plate with good collection efficiency
b. centrifugal and gravity to fall into the hopper
c. electrical force with subsequent interception oi\ the discharge electrode
(3) applied only to the particle enabling low pressure drops through the
collector
23. When collecting particle size data using an in-stack inertial impactor,
the size of the particle data collected is given as the:
(3\ aerodynamic diameter of the particle
b. geometric diameter of the particle
c. Martin's diameter
d. extended area of the particle
24. In a self-induced spray scrubber
a. liquid is injected as high pressure
(B). the gas atomizes the liquid
c. particulate matter is removed by cyclonic deposition on the packing
d. gas flow is counter-current
25. Particles collected at the collection electrode of an electrostatic
precipitator are usually removed by
a. reversing the flow of air in the collector
(E) rapping the electrode by mechanical or electrical mechanism
c. reversing the charge of collection plate
d. creating a vacuum and pulling dust into the hopper
26. In the contact power and cut-power rule, penetration is defined as:
(a) 1 - TI (where n = efficiency)
b. C./C (inlet particle concentration/outlet particle concentration)
c. equal to the total pressure loss, P_
d. being a constant equal to 2.0 for most inertial wet scrubbers
50
-------
27. Which of the following is not an integral component in an electrostatic
precipitator?
a. rappers
b. collection plate
c. discharge electrode
(3 venturi control rod
28. The settling velocity of a particle collected in a settling chamber can
be determined by the following formula:
v -
V
v .
ASL
18y
c.
, dv
d. v = -j— ma
at
29. A common liquid to gas ratio for a preformed spray scrubber would be
3
5-20 gal/1000 ft3
b. .01-.5 gal/1000 ff
c. 50-70 gal/1000 ft3
d. >80 gal/1000 ft3
30. A Raschig ring'would be used
a. around the throat of a venturi scrubber
b. in a cyclonic separator before the pad demister
c. at the top of a cyclonic spray scrubber
(3) in a crossflow packed scrubber
31. A log-normal distribution plot is a straight line on:
a. arithmetic graph paper
b. semi-log paper
(c) log-probability paper
a. log-log paper
32. Particles are charged in an ESP by
a. subjecting the particles to high humidity
(S) corona produced by the discharge electrode when a high voltage
is applied
c. positive corona generated by the collection electrode
d. intense electrical field by applying a-c voltage to discharge wire
51
-------
33. The geometric standard deviation of a log-normal distribution:
a. is the average particle diameter of the distribution
(S) can be obtained directly from a plot of particle size versus
cumulative percent greater than, on log-probability paper
c. is the 50% size on the log-probability paper
d. given as the 84.13% size divided by the 15.87% size
34. A dominant mechanism in the wet collection of particulate matter is:
a. gravitational force
b. electrostatic force
(c) inertial impaction
d. direct interception
35. The migration velocity for a typical design for an ESP is described as
(a) effective drift speed of the particle towards the collection electrode
D. being dependent on back corona and spark over
c. being independent of the particle size
d. speed in which the rappers must be activated
36. Particles in a gas stream with high resistivity will
a. migrate to collection electrode and take on the charge of the plate
b. rapidly lose a negative charge
c. readily accept the charge from the discharge wire
(3) cause electrical breakdown and spark over
37. Contact power theory is based on the observation that:
(a) collection efficiency increases as pressure drop increases
b. condensation of water on particulate matter increases particle size
c. penetration is an exponential function of the cut diameter
d. pilot system parameters may be scaled to larger units
38. In pulse-jet baghouses the cleaning mechanism used for cleaning the
bags is:
a. reversing the flow of air through the compartment
(S) blast of air into each bag knocking the dust away from the bag
c. blast of air to the outside of the bag
d. pulsating air causing the bags to shake
39. Proper air-to-cloth ratio is
a. the measure of amount of dust deposited on the filter
^) imperative for good design and prevention of premature bag failure
c. often referred to as low filter drag
d. is less than 8 inches of water
52
-------
40. Ingot Iron and Steel Company has submitted particle aize data for dust
from their basic oxygen furnace. The data was collected using a Bahco
microparticle classifier. The instrument:
a. measures the geometric diameter of the particle collected with an
EPA Method 5 sampling train
b. measures particle size by passing the particle through a light beam
c. measures the particle's mobility due to its charge
(3) uses a combination of elutriation and centrifugation to separate
particles from a weighted sample yielding subsequent particle size data
41. The sieving action plays an important role in
a. measurement of pressure drop across a felted filter
b. eliminating the need for woven fabrics
c. designing multi-compartment baghouses
(3) collecting large particles to build the cake for subsequent collection
of small particles
42. In a venturi scrubber, efficiency increases when the relative gas to
liquid velocity
a. fluctuates
b. decreases
(c) increases
d. stabilizes
43. An advantage of using felted material for bag construction in a baghouse
is:
(a) that larger air-to-cloth ratios are possible
b. they provide lower pressure drops
c. they take longer for the cake to form
d. resistant to acidic gas streams
44. Using contact power theory, estimate the total pressure loss in the
system if the nressure drop is 5" H^O and the liquid to gas ratio is
15 gal/1000 ft , with a liquid inlet pressure of lOOOpsi.
a. 8750
b. 1005
c. 8.75
(S\ 9.53
45. The pressure drop across a baghouse for shaker or reverse air cleaning
type baghouses is:
a. pressure drop across the cake
b. pressure drop across the shell
(c) pressure drop across the cake plus the filter
d. inlet pressure plus the outlet pressure
53
-------
46. Filter drag for fabric filters is a function of
(a) quantity of dust accumulated on the filter
b. resistance to air from the filter
c. zone of cake repair
d. force opposing filtration
47. What is the efficiency of a wet scrubber if the overall penetration
was found to be .02 by the cut-power theory?
a. 20%
(B> 98%
c. 2%
d. 99%
48. The specific collecting area of an Electrostatic Precipitator is given by
a. the electrical wind
b. migration velocity
c. resistivity of the particle
(jp A/Q, area divided by the gas volume
49. The dust from a cement kiln is sent to an electrostatic precipitator
at 1,600 cfm. The particle migration velocity was measured to be .25
ft/sec. What is the collection efficiency if the collection area is
8000 sq. ft.?
a. 95.8%
(B). 95.0%
c. 4.8%
d. 98.2%
50. A multicyclone is used in many applications for collecting dust. The
efficiency of a multicyclone for particles greater than 10 microns can
be as high as
a. 100%
b. 65%
c. 80%
(S\ 90%
54
-------
COURSE #413 CONTROL OF PARTICULATE EMISSIONS
POST-TEST
ANSWER SHEET
ALL QUESTIONS ARE 2 POINTS EACH
1. a b © d
2. a (g) c d
3. a b 0 d
4. a (B) c d
5. a (E) c d
6. a b c (d)
7- a b c @
8. a b c (3)
9. a b c (d)
10. a b c ©
11. 0 b c d
12. a b 0 d
13. a b c (3)
14. a b (c) d
15. a b c (3)
16. a b (c) d
17. a b c d 0
18. 0 b c d
19. 0 b c d
20. a b c 0
21. a (]>) c d
22. a b c 0
23. 0 b c d
24. a 0 c d
25. a OB) c d
26. 0 b
27. a b
28. a 0
29. 0 b
30. a b
31. a b
32. a 0
33. a (§)
34. a b
35. @ b
36. a b
37. ® b
38. a 0
39. a 0
40. a b
41. a b
42. a b
43. 0 b
44. a b
45. a b
46. 0 b
47. a ©
48. a b
49. a ®
50. a b
c d
c d
c d
0 d
c d
c d
© d
c d
c d
c d
c d
0 d
c d
0 d
c d
c d
c d
55
3/20/80
-------
LESSON PLAN
TOPIC: WELCOME AND REGISTRATION
COURSE: 413
LESSON TIME: 30 minutes
PREPARED BY: DATE:
David S. Beachler
4/79
LESSON GOAL:
Allow students to introduce themselves to the class;
determine the actual level of job experience in the
class.
LESSON OBJECTIVES: Each student should know:
1. The name of the organization conducting the course; any other
contributing organization; the source of the course materials
and any similar information.
2. The name of all instructors and their affiliations
3. The name and employer of each student in the class
4. The phone number where a student may receive messages
5. That the requirements for passing the course are:
a. Completed registration card
b. 95% attendance - minimum
c. All homework completed and turned in » 10 points
d. Achieve course grade of 70%
e. Course grade = final exam score + homework points
6. That the teaching method in the course is one of problem
solving using the basics learned in these lectures.
7. The nature and uses of class materials:
a. Course 413 Student Workbook
b. Course 413 Student Manual
56
-------
c. Agenda
d. Selected handouts
e. Note paper
f. Registration card
g. APTI chronological course schedule
7. The location of:
a. Restrooms
b. Refreshments
c. Restaurant s
d. Transportation facilities
8. Address and phone number (919-541-2766) of EPA - APTI
MD-20, Research Triangle Park, NC 27711
SUPPORT MATERIALS;
1. Student materials package
2. Blackboard and chalk
57
-------
CONTENT OUTLINE
Course:413
Lecture Title: WELCOME AND REGISTRATION
Page—L-of.
NOTES
ii.
Introduce self and other instructors present; Identify
others
A. Names and affiliation
B. Experience >
C. Areas of expertise of entity conducting the course
Explain relationship to the USEPA, Manpower and Technical
Information Branch and the Air Pollution Training
Institute. (If appropriate)
III. Logistics of the course location
A. Message phone number
B. Restrooms
C. Refreshments and restaurants
D. Encourage students to get together and share
experiences, etc.
E. Transportation
IV. Introductions - Have each student stand and
A. Give name, hometown, and employer
B. Describe their air pollution experience; what their
job involves.
C. Explain what they expect to get from the course.
V. Description of teaching methods
A. Training
1. Course directed at training students to perform
a specific skill
2. Methods used in the course will be explicit not
implicit
B. Instructors
1. Will be there to help student become trained
2. Will add their experience and expertise to the
training
3. Encourage questions; but avoid use of whole class
time for individual interests.
C. Approach
1. Teach the basic operation and design features of
particulate control equipment
2. Teach the fundamental formulas for efficiency, Ap,
and other design parameters
3. Solve problems by applying these fundamentals
58
Write on Board
Write names on the
Board
-------
CONTENT OUTLINE
Course: 413
Lecture Title: WELCOME AND REGISTRATION
Page I-of.
NOTES
VL. Course Requirements
A. Completed registration card
B. Pre-test
C. 95% attendance - minimum
D. All homework completed and turned in
E. Post-test
F. Course critique completed and turned in
G. Homework problems will count as 10 points
H. Final grade will be post-test score plus homework
points; 70% minimum passing grade.
VII. Materials - have students check that they have:
A. Manual
B. Workbook
C. Agenda
D. Note paper
E. Registration card
F. APTI Chronological Course Schedule f
G. Local information sheet (phones, addresses, restaurants
etc.)
VIII. Pre-test and registration
A. Explain that the pre-test
1. Tests what they know as they enter the course
2. Does not count in the final course grade
3. Will be correlated to post-test grade to measure
actual learning in the course- to improve course anfe tests.
4. Students should not guess at answers
B. Registration card - completely filled out
C. Begin the pre-test and tell students to take a break
after the test
D. Collect all tests and registration cards - grade tests
promptly and report low, high, and average grades.
E. Instructor will collect the tests (so as to eliminate
an agency from building a test file).
59
-------
LESSON PLAN
TOPIC: REVIEW OF THE BASICS
COURSE-- 413 - Lesson 1
LESSON TIME: 1 hour
PREPARED BY: DATE: 4/19/79
David Beachler
LESSON GOAL:
LESSON OBJECTIVES:
PRE-REQUISITE SKILLS:
LEVEL OF INSTRUCTION:
INTENDED STUDENT
BACKGROUND:
SUPPORT MATERIALS
AND EQUIPMENT:
REFERENCES:
To explain the meaning of numerous symbols and basic
concepts that are used when performing particulate emission
control calculations.
At the end of the lesson the student should be able:'
* Define in general terms
Pressure — gage, barometric, absolute
Temperature — Centigrade, Farenheit, Kelvin,
Rankine
Density
Ideal Gas Law
Molecular weight
Gas viscosity
Reynolds Number
* Calculate pressure, temperature and volume changes
* Calculate the Reynolds Number
Engineering or physical science background
College undergraduate science
College math and science
1. Slide projector
2. Chalkboard
3. Pocket calculator for each student — or slide
rule to do calculations
4. 413 Student Workbook
1. 413 Student Manual
2. 413 Student Workbook
60
-------
AUDIO-VISUAL MATERIALS FOR LESSON 1
Lesson 1 Review of the Basic Physical Constants
413-1-1 Properties of gases
413-1-2 Temperature
413-1-3 Temperature conversion
413-1-4 Temperature conversion
413-1-5 Absolute temperature
413-1-6 Atmospheric pressure
413-1-7 Gauge pressure
413-1-8 Absolute pressure
413-1-9 Density
413-1-10 Specific gravity
413-1-11 Atomic number—oxygen
413-1-12 Atomic weight—oxygen
413-1-13 Molecular weight
413-1-14 Mole—molecular weight
413-1-15 Mole—oxygen
413-1-16 Boyles law
413-1-17 Problem—volume change at constant temperature
413-1-18 Solution—volume change
413-1-19 Charles-Gay Lussac law
413-1-20 Problem—volume change at constant pressure
413-1-21 Solution—volume change
413-1-22 Ideal gas law
413-1-23 Volume of one mole-standard conditions
413-1-24. Viscosity—definition
413-1-25. Viscosity—high, low
413-1-26 Temperature effect on viscosity for liquids
413-1-27 Temperature effect on viscosity of gases
413-1-28 Kinematic viscosity
413-1-29 Reynolds number
413-1-30 Reynolds number range-pipe flow
413-1-31 Review
61
-------
CONTENT OUTLINE
Course: 413 - Lesson 1
Lecture Title: REVIEW OF THE BASICS
Page l_ of.
NOTES
I. Introduction - fundamentals
Some of the Important properties of gases one must consider
when working with gaseous emission control equipment include:
Temperature
Pressure
Density
Molecular weight
Ideal Gas Law
Viscosity
Reynolds Number
A. Temperature
1.
2.
3.
Defined as the degree of hotness or coldness measured
on a definite scale.
The temperature range in Fahrenheit and Celsius scales
is based on the freezing and boiling point of water,.
For Fe it is 180 and for C° it is 100.
The following relationships convert from one scale
to another
3F - 1.8 C .+ 32
3C - (°F -32)/I.8
Absolute temperature
r •
B.
Experiments have shown that a perfect gas under
constant P, for each change in °F below 32°F -
the volume of gas changes 1/491.67
b. Similarily for each "C, volume changes 1/273
c. If change in volume per degree is constant, what
volume of gas.theoretically would become zero
at 491.6°F below 32°F or at -460°F. For
Centigrade it would be -273°C
d. Absolute temperatures determined by °F are
expressed as "F or Rankine.
°R - °F + 460°
e. Absolute temperatures determined by °C are
^- expressed as °K or Kelvin.
-K - °C + 273
Gas Pressure
1. Defined as application of force to something else in
direct contact with it. Pressure is usually ex- _
pressed in units of force divided by area. I- .-
2. Barometric pressure — pressure measured with a
barometer, synomous with atmospheric pressure,
usually expressed in inches, mm, of mercury.
62
413-1-1
413-1-2
413-1-3
413-1-4
413-1-5
413-1-6
-------
CONTENT OUTLINE
Course: 413 - Lesson 1
Lecture Title: REVIEW OF THE BASICS
Page.
NOTES
(weight
exerted by
atmospheric
air)
4.
?
Standard barometric pressure is 14.7 Ibs/in exerted at a
base of a column of mercury 29.9 inches high. Weather
and altitude are responsible for barometric pressure
^changes.
Guage Pressure — is measured by a guage and In-
dicates the difference in pressure above or below the
atmospheric pressure, (expressed in psig).
a. If pressure of system > atmospheric pressure
then guage pressure is +.
b. If pressure of system < atmospheric pressure
then guage pressure is - (a vacuum)
Absolute Pressure — since guage pressure is the
pressure of the system relative to the atmosphere
then the algebraic sum of gage pressure plus
atmospheric pressure yields
(1 atm or 760 mrr
Hg Standard
Pressure)
413-1-7
413-1-8
ABS
- P
guage
+ P
atm
(Psia)
C. Density
1* Defined as the mass per unit volume
m
o
2. Units expressed in g/cc, g/iiter» lb/ft
3. In the case of liquids and solids the temperature
at which the density was measured is denoted in
the table of physical data (tables in books such
as Perry's Chemical Engineer Handbook).
4/1 Gas densities refer to the density of that
— particular gas at 0°C and 1 atmosphere pressure.
15. a. A related concept to density is specific gravity
which is defined as the ratio m/V/m /V where
m and m are the true weights of thi substance
and of water in the same volume.
b. For gases, specific gravity of a gas is referred
to dry air at the same pressure and temperature
(instead of water) usually at 32°F, 29.291 in Hg,
or 0°C, 760 mm Hg.
6. An example of specific gravity of a gas He - .1368
Density - (.1368)(1.2928 g/1) - .1769 g/1,
' sp. gravity density of air
413-1-9
413-1-10
Example: do on
overhead or
blackboard
63
-------
CONTENT OUTLINE
Course: 413 - Lesson 1
Lecture Title: REVIEW OE THE BASICS
Page—L_ Of.
NOTES
7.
For gases the specific gravity can be defined as
the ratio of the molecular weight of the gas to the
molecular weight of air which is 29. i.e.
specific gravity He 4.00
29
.137
D.
E.
Molecular Weight
1. Atomic number of an element (on the periodic chart)
is the number of protons contained in the nucleus.
2. Atomic weight — is the average isotopic mass. i.e.
8^— atomic no.
0
atomic wt. —+»16
3.
Atomic Mass Units
Molecular Weight - now is sum of the atomic weight
of all the atoms in a molecule, i.e.
\^>-~~n^^^^^X ^J^
16 16
'2
M.W. - 2(16) - 32 AMU
oxygen
1 molecule of 0.
32
4.
b.
Mole or gram mole — is the amount of a substance
that contains as many atoms, molecules or ions
as 12 grams of Carbon 12. The number of ,3
elementary particles in 12 grams C ±B 6.02 x 10 .
i.e. 1 mole of oxygen 0, has 32 g, 1 mole H90 has
18 g. Z Z
Each mole or gram-mole contains an Avogadro's .3
number of molecules (atoms or ions), 6.02 x 10 ,
and each mole of a gas at standard conditions 0°C
and 1 atm pressure occupies 22.4 liters in volume.
Ideal Gas Law
1.
Boyles' Law — at a constant temperature, a
fixed weight of a particular gas occupies a
volume that is inversely proportional to the
pressure exerted on it.
pl - V2
]T V. Pinitial x yinitial
pfinal x Vfinal
64
Ni
p. gtf - m.w. gas
m.w. air
• 4.00
29
.137
413-1-11
No te: Mendeleev
(Russian chemist
developed the
periodic chart)
413-1-12
Note AMU
413-1^13
413-1-14
413-1-15
OTE:
ole-gram mole of
413-1-16
-------
S CONTENT OUTLINE /S\
c ™"^^"^^ 1 vB& ?
Lee fare Title: REVIEW OF THE BASICS %PROI«^
b. \ Example .
@ constant temp, the volume of gas measured at 745
mmHg was 200 ml, what is the volume of gas at
760 mmHg?
(1) p^ - p2V2
(2) (745) (200) - (760) (V2)
(3) V. - (745) (200) 1Q, ,
2 760 196 ml
a. Charles Law — states that when the volume is
I j held constant, the absolute pressure of a given
\_) mass of an ideal gas of a given composition
varies directly as the absolute temperature.
p a T
pl P2 p,» initial pressure
T T
1 2 Pjm final pressure
T,« initial temperature
T - final temperature
C-> ^
b. Charles-Gay Lussac Law — volume is directly
proportional to temperature at constant pressure
V a T or V- - V2
c. Example: @ constant pressure, the volume of a
gas measured at 20°C was 200 ml. What is the
volume at 25°C
200 x 298 - V, - 203 ml
- — 293
.3. Ideal Gas Law
a. Both Boyles and Charles Law are satisfied by
the Ideal Gas Law
pV - mRT
M
p absolute pressure of gas
V volume of gas
m mass of gas
T absolute temperature of gas
M gas molecular weight
R universal gas constant
b. It Is very important that the value of R is
not dimensionless .
65
Page—h— 0/__Z__
mi^i
' 413-1-17
413-1-18
Write on overhead:
Charles Law
413-1-19
413-1-20
413-1-21
413-1-22
413-1-23
-------
CONTENT OUTLINE
Course: 413 - Lesson 1
Lecture Title: REVIEW OF THE BASICS
Page 5 of
NOTES
c. Values of the universal gas constant R are:
R value Units
1.987 Ifu7(ib.mole)(eR) or
Cal/(gram mole)(°K)
0.730 (atmKft3)/(lb.mole)(°R)
10.73 (psia)(ft3)/(lb/nole)(°R)
82.06 (atm)(cm3)/(gram mole)(°K)
F. Viscosity
1. Viscosity is a proportionality constant associated
with a fluid resistance to flow.
2. Viscosity is the result of two phenomena
a. Intennolecular cohesive forces
b. Momentum transfer between layers of fluid
caused by molecular agitation perpendicular to
the'direction of motion
c. Point out for liquids — intermolecular cohesive
forces most Important
d. Gases momentum — transfer most important
3. Between the adjacent layers, a shearing stress
occurs which is directly proportional to the velocity
gradient
Point out R
values
413-1-24
Point out c.
Point out d.
where: T - unit shearing stress between
adjacent layers
-2- • velocity gradient
y • proportionality constant
Liquid --..for liquids the momentum between layers is
•mall compared to the cohesive forces between the
molecules.' Hence T is predominantly a result of
in.termolecules attraction. Since intermolecular
cohesion rapidly decrease with temperature, the shear
force decreases with increase in temperature '."Toy
.*. y decreases with increase in T.
66
413-1-25
413-1-26
-------
CONTENT OUTLINE
Course: 413 - Lesson 1
Lecture Title: REVIEW OF THE BASICS
Page-&—of.
NOTES
5. Gases — In gas, the molecules are too far apart for
inter-molecular cohesion to be effective. So the shear
stress is predominantly the result of an exchange of
momentum between flowing layers caused by molecular
activity. Since molecular activity increases with T,
T increases with temperature, Increasing y.
Units — one unit used to describe viscosity is the
centipoise - 1/100 gm/cm-sec.
English units are obtained by multiplying the value
of centipoise by 6.72 x 10~4. The english units for
viscosity are Ib /ft.sec.
m ^
., By knowing the temperature of gas^ y can be obtained from
7^ a reference book such as "Ferry's Chemical Engineer's
Handbook".
6. Kinematic viscosity is given by the symbol v
v - y/p
where v » kinematic viscosity
p » viscosity
p - density
G. Reynolds Number
1. The Reynolds Number is a dlmensionless quantity
frequently encountered in A.P. and characterizes
the nature of fluid flow.
Re # is defined as inertia! forces Re
viscous forces
vDp
P
where:
Re - Reynolds Number
D - diameter of duct gas flowing in
v - gas velocity
p - gas density
y « gas viscosity
2. For flow of gases in a circular pipe:
Re < 2000 flow is laminar
Re > 2500 flow is turbulent
67
413-1-27
413-1-28
413-1-29
413-1-30
-------
CONTENT OUTLINE
Course: 413 - Lesson 1
Lecture Title: REVIEW OF THE BASICS
Page-I of-2-
NOTES
y
II. Review
The past hour we've talked about the following concepts:
• Temperature
• Pressure
• Density
• Ideal Gas Law
• Molecular weight
• Viscosity
• Reynolds Number
413-1-31
68
-------
• MM* «••
Lnr
fiAUAE PMSSURE
ABSOLUTE PRESSURE
of system
DENSITY
(DM MM
OXYCINATOM
(one molecule)
BOYLE** LAW
•<•« 7«» «•»»(« w»t
*»* b «M Mknw •* CM
MIM
CHARLES' LAW
LIQUID
IDEAL CAS LAW
KINEMATIC VISCOSITY
RCVNOUMNUMMOI
MEYNOLOS NUMBER RAN«E -
PIPE FLOW
vtecootty
69
-------
70
-------
LESSON PLAN
TOPIC: PARTICLE DYNAMICS
COURSE: 413 - Lesson 2
LESSON TIME; i hour . ._.
PREPARED BY: DATE: 4/79
David S. Beachler
LESSON GOAL:
Describe particle behavior in a fluid due to external forces
such as gravity, buoyancy and drag force.
LESSON OBJECTIVES: At the end of the lesson, the student should be able to:
• Describe the basic forces of gravity and buoyancy and their
relationship to a particle and its motion.
• Describe the aerodynamic drag force on a particle in motion
and the drag coefficient.
• List the three regimes that a particle may flow in and
their relationships in calculating the drag force for
each regime.
• Describe the Cunningham correction factor for the drag
coefficient in the Laminar regime.
• Describe an overall equation for motion including
gravity, buoyancy, and drag.
• Recognize the equation to calculate the terminal
settling velocity for a particle in each regime.
• Determine the proper regime by calculating the factor "K".
STUDENT PREREQUISITE SKILLS:
Ability to understand basic principles of physical science.
LEVEL OF INSTRUCTION:
Advanced
INTENDED STUDENT PROFESSIONAL BACKGROUND:
Engineering or Physical Science
SUPPORT MATERIALS AND EQUIPMENT:
1. Slide Projector
2. Overhead Projector
3. Chalkboard
4. 413 S tuderit"Manual
71
-------
REFERENCES:
1. 413 Student Manual
2. 413 Student Workbook pp. 1-2
3. "Fluid Mechanics", Victor L. Streeter, and E. Benjamin Wylie, sixth
edition, McGraw-Hill Book Company, New York, 1975, pp 1-710.
4. Lecture notes prepared by Cliff I. Davidson, Carnegie Mellon
University, March 1, 1979.
72
-------
AUDIO-VISUAL MATERIALS FOR LESSON 2
Lesson 2 Particle Dynamics
413-2-1 Particle force
413-2-2 Forces applied to a particle
413-2-3 Gravity—equation
413-2-4 Buoyancy—equation
413-2-5 Buoyant force
413-2-6 Aerodynamic drag force
413-2-7 Aerodynamic drag force—equation
413-2-8 Drag coefficient
413-2-9 Reynolds number
413-2-10 Flow regimes
413-2-11 Drag coefficient versus Reynolds number
413-2-12 Flow regimes—drag coefficients and Reynolds number
413-2-13 Drag force—transition regime
413-2-14 Drag force—turbulent regime
413-2-15 Laminar regime
413-2-16 Drag coefficient and Cunningham correction factor in laminar regime
413-2-17 Drag force—laminar regime
413-2-18 Terminal settling velocity
413-2-19 Settling velocity—laminar regime
413-2-20 Settling velocity—transition regime
413-2-21 Settling velocity—turbulent regime
413-2-22 Determining the proper regime
413-2-23 Determining the proper K value
413-2-24 Calculating the K value
413-2-25 K values for various regimes
413-2-26 Review—flow regimes
413-2-27 Review
413-2-28; Review
73
-------
CONTENT OUTLINE
Course: 413 - Lesson 2
Lecture Title: PARTICLE DYNAMICS
rttD 87^
-------
CONTENT OUTLINE
Course: 413 - Lesson 2
Lecture Title: PARTICLE DYNAMICS
PROt
Page
NOTES
2. We can see that the force due to gravity is
dimensionality consistent and given F in units
lbf G
C. Force Due to Buoyancy
1.
The buoyant force (on a particle) is equal to the
weight of the displaced fluid and can be given by
the equation
F = V
B Vp
£_
*"c
where p = density of the fluid Ib m/ft
V 3
p = volume of particle ft
2. An example of the buoyant force can be shown by
two buckets one filled with air, the other with
water.
and let's place identical objects in each bucket.
Since the p air « p water
then FB(alr) « FB(water) and the object rises in
water bucket.
III. Aerodynamic Drag Force
A. Forces on a Particle
1. Let's say there are several forces acting on a
particle:
electrostatic or
magnetic
If the vector sum of these forces is not zero, ther
the particle will move.
75
413-2r4
413-2.5
413-2-6
-------
CONTENT OUTLINE
Course: 413 - Lesson 2
Lecture Title: PARTICLE DYNAMICS
Page.
of.
NOTES
2. Whenever there Is particle motion, there will be
a resistive force caused by the fluid molecules
resisting the motion of the particle.
F,,
Resistive force of fluid
• drag force FD
resultant
3. The equation for calculating drag force is given
by:
FD - CD
2 8
projected
(A . . is the area of the particle in
direction of flow)
where:
A . ^ , = ird
proj ected p
for spherical particles
of diameter d
P
= particle velocity relative to the fluid
= drag coefficient
413-2.7
4. Cn is a function of particle velocity, particle
and characteristics of the fluid. But it has
been found that C_ is a unique function of a
dimensionless combination of these parameters:
C_ = function of Re (Reynolds Number)
where Re = v d p
p
dia neter
'413.2.8
413-1.9
y = fluid viscosity
p - density of fluid
d • particle diameter
v - velocity
76
-------
CONTENT OUTLINE
Course: 413 - Lesson 2
Lecture Title: PARTICLE DYNAMICS
\
10
Page.
of.
NOTES
5. If we look at a graph of C_. versus Re we can see
three regimes
Drag
Coefficient
1000
100 •
10 •
1 .
Turbulent
flow
Laminar
flow
10
~z
2.0 10 10 10 10 10
Re - Reynolds Number
This figure is given in the 413 Manual as
Figure 2.2.1 on page 2-16.
6. We can now write the equation for this curve in
each region
a. Laminar, (Re < 2) C = 24
(Stokes Law)
Re
b. Transition ( 2 < Re < 500) C_ = 18.5
Re'6
c. Turbulent (500 < Re < 2 x 105) CD : 0.44
(Newtons regime)
In general the equation can be written
-b
a Re
Where a and b take on different values in each
regime.
7. Drag Force Equations
In order to calculate the drag force on a particle
we merely have to substitute the proper C,
expression into the equation for F
77
413-r2.10
413-2.11
413-2.12
-------
CONTENT OUTLINE
Course: 413 - Lesson 2
Lecture Title: PARTICLE DYNAMICS
Page.
.<*
NOTES
7 . cont ' d
a v"b dp~b p"b
,rd
substitute for _a and 1>, and simplifying we get
(fi) Transition Regime ( a = 18.5, b = 0.6)
413-2.13
= 18.5TT
8
(V d
g.
Newtons Regime (a = 0.44, b = 0)
2
413-2.14
P (v dp)
8-
C. Laminar Regime
1. There is a problem when the particle gets very
small.
appe ars
(a) if d is much greater than 1 ym the fluid -rr-
and the particle is not affected by collisions
with individual air molecules.
continuous
413-2.15
(collisions occur very frequently on all sides
of the particle)
(b) If the particle is much smaller than 1 jam
Collisions on one side of the particle
are more likely to occur. This will cause
particle to move in a direction related to the
combined forces acting on the particle.
-------
CONTENT OUTLINE
Course: 413 - Lesson 2
Lecture Title: PARTICLE DYNAMICS
Page.
of.
Thus the particle will slip between air molecules
(when it is very small) and C will reduce to:
24
NOTES
413-2.16
Re
Where:
is the Cunningham correction factor
2. Now we can write F as
F_ = 24ir y v d
D 8~C7 E.
f
413-2.17
for d > 1 pm
Cf > 1 for d < 1 ym
r
IV. Equation of particle Motion
A. Forces
We discussed several forces individually so far
FB (buoyancy)
D
FD (drag)
FG (gravity)
F (external, such as gravity)
Let's combine all of these forces into a single
equation and then examine the resultant force.
FR - FG -FB "FD = i £
We often define f - force per unit mass of the particle
m
m
The 413 manual discusses other external forces, such as
electrostatic and centrifugal forces. We won't be
considering these, but rather let's examine the motion
of a particle subjected to the three forces above.
79
-------
ir-
CONTENT OUTLINE
Course: 413 - Lesson 2
Lecture Title: PARTICLE DYNAMICS
Page.
of.
NOTES
B. Drag Force
If we have a particle which has a greater density than
air, (like most particles), then the particle will
accelerate according to the equation.
But, what happens to the size of F<. as the particle
accelerates?
Remember F Increases as v Increases. Thus there will
be some value of v where F is as large as the other
forces. At that point, the resultant force will be
zero and the particle will no longer accelerate.
We can determine the value of v where all forces
balance. Called terminal settling velocity.
F I
9
FG -F -F = 0 (at terminal
settling velocity
Defining force per unit mass = f
C. Terminal Settling Velocity
1. Now substitute for F from each regime (equations
previously giver) and solve for terminal settling
velocity v.
2. For Stokes Law (Re< 2)
- - F_ =0
g_
8,
Pp *
80
413-2.18
-------
CONTENT OUTLINE
Course.,-413 _ Lesson 2
Lecture Title; PARTICLE DYNAMICS
Page
UzfiJ
P..
3ir u vd /IT
^*7'
Solving for v, and defining v as v the terminal settling
/ v
? I
).29
velocity«we obtain
vt" 8 dp (PP"P) Cf
18y
3. For the Transition Regime
v= . 153g°-71 d.,1-14
4. For the Newton's Regime
vt= 1.74 (g dp pp
D. Determining the Proper Regime
1. It is necessary to determine which regime is
correct for the particle when one is attempting
to calculate the settling velocity.
2. One can't just solve for Re, and determine the
regime, since you need to know the velocity to
calculate the Re, yet you're trying to solve for
v.
^3. In the 413 Manual, the author explains that one
can calculate a new parameter K
where: K = d
when: K < 3.3 we're in Stokes Law Regime
3.3 < K < 43.6 we're in Transition Regime
K> 43.6 we're in Newton's Regime
4. Once we determine the proper regime (by calculating
K) we then know which equation to use for calculat-
ing drag force and settling velocity.
81
413-2.19
413-2.20
413-2.21
413-2.22
413-2.23
413-2.24
413-2.25
-------
CONTENT OUTLINE
Course: 413- Lesson 2
Lecture Title: PARTICLE DYNAMICS
Page-2—of
NOTES
V. REVIEW - Handout Lecture outline
We talked about the following subjects the past
hours.
* Forces of Gravity and Buoyancy
* Aerodynamic Drag force on a particle in motion
* Drag Coefficient
* The three Regimes a particle flows in
• Laminar - Stokes Law Regime
• Transition Regime
• Turbulent - Newton's Regime
* Cunningham correction factor for drag coefficient
in the Laminar regime.
Handout
outline to students
413-2.26
413-2.27
413-2-28
* The terminal settling velocity
* The parameter K - to determine the proper regime
82
-------
' PARTICLE FORCE
FORCES APPLIEI
TO A PAH
YANCY
BUOYAMT FORCE
WHERE
mr - ma»» of purllde
•- = acceleration at particle
1AIHICDRAGFOHC*
WHERE C, = Cimoln»ll«i
DRAG COEFFICIENT:
TURBULENT REGIME
IMINAL SETTLING
EfA Contr.rtMo «C41 2374
3.3 a.3'K43.6 K -43.6
^<-< i Dyn •: •-'•
03
-------
LESSON PLAN
TOPIC: PROBLEM SESSION I
PARTICLE DYNAMICS
COURSE; *13 ~ Lesson 2a
LESSON TIME: 30 minutes
PREPARED BY: DATE:
David Beachler
7/79
LESSON GOAL:
SUPPORT MATERIAL
AND EQUIPMENT
Briefly describe the use of the settling velocity, drag
coefficient and drag force formulas by solving two
problems.
1. Chalkboard
2. 413 Student Workbook, pp 1-2
84
-------
CONTENT OUTLINE
Course: 413 ~ Lesson 2*
Lecture Title: PARTICLE DYNAMICS-PROBLEM SESSI
Page—L—of
NOTES
I. PROBLEM 1-1
A. Work out problem 1-1 for the students. The solution for
1-1 is:
1.1 Drag Coefficient and Settling Velocity
A spherical limestone particle is 400 urn in diameter, specific
gravity - 2.67. Calculate the drag coefficient C and the
settling velocity vfc in 70° F air.
SOLUTION:
TOTE: See problem
1-1 on page 1 of thi ,
413 Student Workbook
1. Convert dp to feet
400 ym x 1 ft
0.00131 ft
3.05 x
2. Calculate K to determine regime
T 2~1 l/2
K - dp [g pp p/y J
- 0.00131 f 32.1 x 2.67 x 62.4 x 0.075 7(1.23 x
ft \ftt 2 Ib Wf3 Ibm/^3/ Ibm/ft sec
•A-
-18.2 •*• transition
3.3
-------
CONTENT OUTLINE
Course: 413 - Lesson 2a
Lecture Title: PARTICLE DYNAMICS - PROBLEM SESS
Page
of.
NOTES
II. Problem 1-2
A. Allow students 15 minutes to work on problem 1-2.
B. Go over the solution of problem 1-2. The solution is:
1-2. Settling Velocity and Drag Force
Particles 20 microns in diameter at 70°F with a specific
gravity of 1.8 flow in a duct. The density of H«0 is 62.4, the
density of air is 0.075 lb. and the viscosity of air is
1.23 x 10~5 lb ftj
ft-sec.
(a) Calculate the settling velocity
1. Convert to feet
TOTE: See problem
-2 on page 2 of the
413 Student Workbook
20 ym x 1 ft
- .000065 ft.
3.05 x lO'' ym
2. Calculate K to determine the regime
. . U/3
gp p/y
r 2r
[gppp/y J
F32.1 x 1.8 x 62.4 x .075 1
L(1.23 x 10-3)*J
0.5
K = .000065
K - 87.6
3. Use v, => 1.74 (g dp Pp/p)
0.5
1.74 x F32.1 x .0000
L •
000065 x 62.4 x
075
).5
v - 3.089 ft/sec
(b) Calculate the Drag Force
FD - 0.055 TT (dp v)2 p/g(.
- 0.055 TT x (0.000065 x 3.089)2 x 0.075
32.1
- 1.63 x 10"11 lb.
86
-------
LESSON PLAN
TOPIC: PARTICLE SIZING -
MEASUREMENT AND MATHEMATICAL
METHODS
COURSE: 413 - Lesson 3
LESSON TIME; i hour
PREPARED BY: DATE:
David Beachler 4/18/79
LESSON GOAL:
LESSON OBJECTIVES:
Describe the common particle measuring methods and describe
the mathematical methods for determining particle size
focusing on the log-normal distribution.
At the end of the lesson the student should be able to:
• Recognize five methods of measuring the size of a
particle and briefly describe their operation.
• List the three most important parameters used to rate
a particle sizing device.
• Describe the major advantages and disadvantages of each
of the five particle measuring devices.
• Discuss how one can obtain the actual sample from a
source and the subsequent analysis for particle size
distributions for each of the measuring devices
• Describe the aerodynamic diameter of a particle.
• Discuss how one can estimate a typical particle size
distribution from a proposed new source.
• Recognize three typical mathematical methods dealing
with particle size distribution.
• Describe the log-normal distribution and the shape of
the curves when plotted on various scales.
• Describe the geometric mean and standard deviation and
how they can be calculated for a log-normal distribution.
87
-------
STUDENT PREREQUISITE SKILLS
Ability to understand basic principles of physical science.
LEVEL OF INSTRUCTION
Advanced
INTENDED STUDENT PROFESSIONAL BACKGROUND
Engineering or physical science
SUPPORT MATERIALS AND EQUIPMENT
1. Slide projector
2. Overhead projector
3. Chalkboard
4. 413 Student Manual
REFERENCES:
1. 413 Student Manual
2. 413 Student Workbook pp. 3-5
3. Lecture notes prepared by Cliff I. Davidson, Carnegie Mellon University,
March 1979.
4. "Particle Size Analysis", John D. Stockham and Edward G. Fochtman,
Ann Arbor Science, 1977, pp. 1-127.
5. "Proceedings: Advances in Particle Sampling and Measurement",
EPA-600-7-79-065, February 1979, IERL, RTF, NC 27711.
88
-------
AUDIO-VISUAL MATERIALS FOR LESSON 3
Lesson 3 Particle Sizing
413-3-1 Manual measurement methods
413-3-2 Mathematical treatment of data
413-3-3 Aerodynamic diameter
413-3-4 Ideal measuring device
413-3-5 Ideal measuring device
413-3-6 Ideal measuring device
413-3-7 Rating measuring devices—key
413-3-8 Rating measuring devices—key
413-3-9 Rating measuring devices—key
413-3-10 Ideal measuring device
413-3-11 Microscopy
413-3-12 Microscopy rating
413-3-13 Microscope measuring size range
413-3-14 Optical particle counter
413-3-15 Optical particle counter rating
413-3-16 Optical particle counter measuring size range
413-3-17 Electrical aerosol analyzer
413-3-18 Electrical aerosol analyzer rating
413-3-19 Electrical aerosol analyzer measuring size range
413-3-20 Banco sampler
413-3-21 Bahco sampler rating
413-3-22 Bahco sampler measuring size range
413-3-23 Cascade impactor
413-3-24 Cascade impactor rating
413-3-25 Cascade impactor measuring size range
413-3-26 Normal distribution
413-3-27 Log-normal distribution—linear d plot
413-3-28 Log normal distribution—log scale d plot
413-3-29 Cumulative log-normal distribution
413-3-30 Expansion of scale
413-3-31 Log-normal distribution—plot on log probability paper
413-3-32 Log-normal distribution—geometric mean on .plot
413-3-33 Geometric standard deviation
413-3-34 Geometric standard deviation
89
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CONTENT OUTLINE
Course: 413 Lesson 3
Lecture Title: PARTICLE SIZING
I. Introduction
A. When trying to design air pollution control equipment
to control partlculate emissions from an industrial
source, it is necessary to determine the size distri-
bution of the particles being collected in order to
accurately calculate the efficiency of the control
device.
Bl Basically there are two ways to determine particle
size distribution that we will talk about:
1. Measurement methods
2. Mathematical treatment of data
Size - In discussing particle size we want to first take
a look at what "size" or what "diameters" one can consider
c
II.
A. An average diameter is the diameter of a hypothetical
particle which in some way represents the total number
of particles in the sample.
B. Diameters representing length, surface area, volume,
specific surface, weight, and falling speed can be
determined.
C. The average diameter that best characterizes the proceis
variable under study should be chosen, i.e., projected
area is Important to pigments, while total surface is
important for chemical reactants.
D. With many aerosols, interest is centered on the
aerodynamic behavior of the particle, this is also
called the Stokes diameter and is a function of
geometric diameter, shape, and density of the particle
This tells us how a particle behaves on an air stream.
Aerodynamic diameter is more useful than the geometric
diameter and is usually measured by an Impactor which
will be discussed later in the lecture.
Ill . Measurement Methods
A. The ideal particle measuring device would:
1. Measure exact size of each individual particle
2. Yield instantaneous response - NO LAG TIME
or averaging time
3. Determine complete composition of each particle
(i.e., shape, density, etc.)
90
Page I ofJL
NOTES
413-3.1
413-3.2
413-3.3
413-3.4
413-3.5
413-3.6
-------
CONTENT OUTLINE
Course: 413 - Lesson 3
Lecture Title: PARTICLE SIZING
Page.
of.
NOTES
B. Examine five measurement devices and compare the
advantages and disadvantages of each, by rating each
for size, time, composition.
1. Rating scale denoting resolution
at single particle level (Is represented by Slide)
i.e., size of each particle
2. Discrete ranges — (denoted by slide)
i.e., size ranges of particles
3. Integrated average (denoted by Slide)
i.e., total mass of particles
of all sizes
4. The ideal device would be
C. We will also consider the various measurement devices
as to their effectiveness for different size diameters.
i.e., some devices are quite useful for submicron
particles, others are not.
Individual Particle Measuring Devices
A. There are many ways (devices) one can use to measure
the size of a particle but we will only consider five
different kinds and try to compare these devices.
(The 413 Manual discusses some additional devices).
B. Types of Devices
1. Microscope - optical or electron microscope
a. Individual particle sizing, but very long
and tedious process. Not very useful for
routine measurements.
b. The particles can be collected on a
filter by using an EPA Method 5 sampling
train. The filter is then taken to the
lab to be analyzed under the microscope.
c. The size is measured at the individual level.
d. Time - that measuring occurs is averaged.
* 413-3.7
413-3.8
413-3.9
413-3. 10
413-3.11
413-3.12
e.
f.
Little information on the composition of the
particle. Generally speaking one is not able
to obtain the chemical composition of the
particle when using an optical microscope.
When using an electron microscope one can get a
detailed chemical analysis of the individual particle.
The microscope measures the geometric
diameter of the particle - measured dis-
tance across the particle.
The optical microscope can measure par- 413-3.13
tides from about .5 microns to about 100
microns. The electronic microscope can
measure particles as small as .001 microns.
91
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CONTENT OUTLINE
Course: 413 - Lesson 3
Lecture Title: PARTICLE SIZING
Page.
of.
NOTES
Optical Particle Counter - Light scattering
a. The optical counter can be used for taking a
sample from a source stack by inserting a probe
into the stack.
b. The flow stream into the measuring device must be
diluted with air — so that one can insure that
one particle passes through the sensing volume
(chamber) at a time.
c. Particles pass individually through a light beam;
split second measurement; scattering of light
is related to particle size.
d. Instrument categorizes particles into size ranges,
discrete size ranges
e. Perfect time resolution - if there is an in-
stantaneous burst of particle emissions from a
source, it can be detected.
f. No particle composition information since the
particles pass through the sensing volume and
are not collected.
g. The optical counter is difficult to use for source
sampling (requires dilution) and interferences
due to variations in particle shape, index of
refraction and optical adsorptivity can affect
readings.
h. The optical counter measures particles from about
.01 microns to 10 microns in diameter.
3. Electrical Aerosol Analyzer
a. Measuring mobilities of charged aerosols. Aerosols
pass through an electric field and the charged
particles migrate over to a collecting surface.
b. Mobility depends on particle size — therefore
divided into size ranges
c. You have to wait for enough particles to pass
through the instrument to get a detectable
charge — therefore time Increments while charge
builds up.
d. This type of analyzer has been used in a stack by
pulling the particles from the stack into a
chamber and introducing this gas stream into the
analyzer. However usefulness of the data obtainec
from this type of analyzer is very skeptical due
to the complexity of measuring the charge of an
individual particle.
e. This analyzer is used mostly for controlled lab
experiments where aerosols are generated and
introduced into the analyzer.
92
413-3.14
413-3.15
413-3.16
413-3.17
413-3.18
-------
CONTENT OUTLINE
Course: 413 - Lesson 3
Lecture Title: PARTICLE SIZING
Page.
of.
NOTES
f . No information on composition since the particles
are not collected.
g. A major advantage is that size information can be
obtained for very small particles down to .005
Vim in diameter.
Bahco - microparticle classifier
a. The particles can be collected (grab sample) by
using a Method 5 type sampling train onto a
filter and then taken back to the lab for analysis
b. The Bahco uses a combination of elutri'ation and
centrifugation to separate particles in an air
stream.
(1) The weighed sample is introduced into a
spiral-shaped air current flowing towards
the center.
(2) The spiral current of air has suitable values
of tangential and radial velocities so that
a certain part of the sample is accelerated
by the centrifugal force toward the pheripheijy
of the whirl, the other part of the sample
being carried by the air current toward the
center of the whirl by means of friction
between the air and the dust particle.
(3) The size, shape and density of the particle
determine which direction it will take. By
varying the flow, the material can be
divided into a number of fractions.
Size - measured in size ranges — therefore dis-
crete ranges.
Time - it takes several hours to complete the
fraction analysis — therefore average time values
Can do a chemical analysis on each size range of
collected particles.
Bahco provides information on the aerodynamic
size of particles, which can be translated into
settling velocity information useful for design-
ing emission control devices.
The major drawbacks are:
(1) The working range is from 1 to 60 microns
in diameter
(2) Care must be exercised when measuring cer-
tain type particles especially those which
are friable and hygroscopic.
93
413-3.19
413-3.20
c.
d.
e.
f .
413-3.21
413-3.22
-------
CONTENT OUTLINE
Course: 413 - Lesson 3
Lecture Title: PARTICLE SIZING;
Page 5 of-L
NOTES
5. Impactor - inertial impactor
Collects and separates particles into size ranges
This device actually collects particles, so we can do
chemical analysis to determine composition for
different size ranges..
a. The Inertial Impactor can be attached to a stan-
dard sampling train (Method 5) and Inserted Into
the stack.
b. The particles are collected on Individual stages
(usually with filters made of paper or aluminum
foil — prewelghed) and once the sample is com-
plete, the collection filters are weighed
giving particle size distribution data for the
various collection stages.
c. Description — Device operates on the principle
rv, of inertial impaction — large particles cannot
follow air streamlines around an obstacle:
d. Size - measured In size ranges — discrete
ranges
e> Time - averaged values
f. Can do chemical analysis on collected particles
in each size range
g. Impactor measures the aerodynamic diameter. This
is a function of geometric diameter, shape and
density of the particle. This tells us how a
particle behaves in an airstream. Aerodynamic
diameter is a more useful value than the geo-
metric diameter.
h. The effective cut off range is around .02 to 20
microns in diameter.
i. This is probably most useful device for the contro
agency or source operator to use to determine the
particle size distribution from a particular source
This is due to the fact that these instruments have
been used for some time, the ability to draw a
sample directly from a stack and the relative in-
expensiveness of the equipment.
413-3.23
413-3.24
413-3.25
94
-------
CONTENT OUTLINE
Course.-413 - Lesson 3
Lecture Title: PARTICLE SIZING
Obtaining Size Distribution Data from a New Source
A. Sometimes the source operator or control agency
officer is in the perplexing position of trying to
obtain particle size data from a process that has not
yet been built.
B. Under these circumstances they are left with no
option but to obtain the data from published size
distribution data of similar installations already
in operation.
C. Some useful sources of information include:
1. Many EPA publications on particle size.
2. "Particulates and Fine. Dust Removal", Marshall
J Sittig, Pollution Control Review No. 34, published
by Noyes Data Corporation, Park Ridge, New Jersey,
1977.
VI. Mathematical Treatment of Data
In dealing with particle size distributions, the 413
Manual discusses several typical size distributions.
Some include:
A. Normal Distribution; bell-shaped on a linear d scale
versus percent of total particle mass.
B. Bi-model Distribution —with two bell shaped peaks
413-3.26
95
-------
CONTENT OUTLINE
Course: 413 - Lesson 3
Lecture Title: PARTICLE SIZING
PRO**
Page 7 ofJL
NOTES
C. Log-normal Distribution—we will focus on this one more
1. Log-normal distribution plotted on a liner d scale
is skewed
2. Log-normal distribution plotted on a logarithmic d
scale is a symmetrical bell shaped curve p
3. The log-normal distribution is often plotted as a
cumulative distribution. Cumulative log-normal
plotted on linear percentage scale approaches
0% and 100% values asymptotically when d is on
a logarithmic scale. ( The ends of the*1 curve
0% has d > ~ , 100% has d > 0)
4. Using a special type of graph paper called:
a. log probability paper, one can expand the
cumulative distribution axis near 0% and near
100%. By expanding the axis, we can force
the bell-shaped curve to be a straight line.
b. The plot is identical to the previous plot,
except that the percentage scale is expanded
near 0% and 100%.
(Note the straight line does not have to cross
the graph at the 50% point)
5. . Geometric mean and standard deviation of a log-
normal distribution.
(a) On a plot of particle diameter d (log scale)
versus cumulative percent largerpthan the
maximum diameter d max;
P
(1) the geometric mean is midway between the
v_ 84.13% size and the 15.8% size — or at
the 50% size
413-3.27
413-3.28
413-3.29
413-3.30
413-3.31
413-3.32
96
-------
CONTENT OUTLINE
*<>*
Course: 413 - Lesson 3
Lecture Title: PARTICLE SIZING
Ssn^
1
O
'/
of.
NOTES
(2) The standard deviation is the root-mean-
square deviation about the mean value.
It's derivation and application in
significant testing and setting of
confidence levels can be found in most
textbooks on statistics.
413-3.33
geometric standard deviation is the:
= 15.87% size
413-3.34
o =50% size
gm
84.13% size 50% size
b. The utility and importance of the log-normal
l^y distribution of particle sizes is summarized:
(1) The distribuiton is completely specified
by the two parameters, the geometric
median particle size, d , and the
geometric standard deviition, a
gm.
(2) The geometric standard deviation is
identical for all methods for specifying
the particle size distribution, whether
by particle number, surface, mass or any
other quantity of the form kdn, where d
is the diameter and k is a parameter
common to all particles. Plots of the
cumulative distribution on log-probabili|ty
paper are then parallel straight lines
for number, mass or surface which leads
to a great simplification and simple
graphical technique.
(3) Transformations among the various
particle size paramters and statistical
diameters are greatly facilitated both
analytically and graphically.
(4) The geometric mean diameter, d , and the
geometric standard deviation, a , may
be found by a simple graphical "^
procedure as illustrated in Figure 2.
Figure //I
IO
100
Particle tlz«, microns
(5) The geometric mean diameter, d
equal to the median or central*
of the distribution.
Figure 1. Particle size
distribution of Figure 2
plotted with logarithm of
particle size.
97
, is
value
Figure #2
40
20
10
9
I » 90 90
Cumutatlvt % Lnt Than
99
-------
CONTENT OUTLINE
Course: 413 _ Lesson 3
Lecture Title: PARTICLE SIZING
Page 9 of—
NOTES
VI. Review
We have talked for the past 1 hour about the following
subjects:
* Five methods of measuring particles
* Three parameters to rate a particle sizing
device.
* Aerodynamic diameter of a particle
* Sampling methods for taking the particles from a
source and measuring their size,
* Methods of estimating particle size data from
new sources.
* Mathematical methods dealing with particle size
distribution
* Lognormal distribution
* Geometric mean and standard deviation of a log-
normal distribution
98
-------
AERODYNAMIC DIAMETER :
IDEAL MEASUWMG DtVlCt OCAl M
of unH dwnitty having th*
some tailing ip**<* ^ air
IDEAL MEASURING DEVICE
MICROSCOPY
CASCADE IMPAOOK
PTICAl PARTICLE COUMTCK
OAHCO
SAMPLER
EXPANStON
Of SCALE
(Out*f Ends)
99
-------
100
-------
LESSON PLAN
TOPIC: PROBLEM SESSION II
PARTICLE SIZING
COURSE: 413 - Lesson 3a
LESSON TIME; 1/2 hour
PREPARED BY: D> Beachler DATE:
,.,.
7/79
LESSON GOAL:
Briefly describe the use of log-normal distribution data
and calculate the geometric mean and standard deviation by
solving two problems.
SUPPORT MATERIALS
AND EQUIPMENT:
1.
2.
Chalkboard
413 Student Workbook pp. 3-5.
101
-------
CONTENT OUTLINE
Course: 413 - Lesson 3a
Lecture Title: PARTICLE SIZING - PROBLEM SESSION**
Page
of.
NOTES
I. Problem 2-1.
A. Work out problem 2-1 for the students.
The solution for 2-1 is:
(See Next Page)
Note; See problem
2-1 on page 3 of
the 413 Student
Workbook.
102
-------
2 of 9
2.1 Log-normal distribution
Let's say you have collected some data on particle mass concentration
with an optical particle counter or an Anderson Impactor. The
following-' data was collected.
S range concentration
ym
0.1 - 0.2
0.2 - 0.5
0.5 - 2
2-5
5-10
10
13.2
20
13.2
10
How can you tell if these data represent a log normal distribution
or some other distribution?
temt.
SOLUTION:
1. Plot mass concentration on a linear d scale.
P
*:
Mt- ""*
»jK 10
-
skewed shape
which 413 Manual says is characteristic
of a lognormal curve.
0 i
2. Log d scale
Jj>
10
We do get an appropriate bell-shaped
curve. But is the distribution
lognormal?
(throwing a curve on this one)
.* l s 10
Let's say that our instrument just measures 4 size ranges, lowest range is 0.1 - 0.5 ym
New device
same
dp range
0.1 - 0.5 ym
0.5 - 2.0
2.0 - 5.0
5 - 10
concentration
23.2 yg/m3
20.0
13.2
10
Actual size distribution is the
same, but we just have a different
measurement device
103
-------
GftMC.
3 of 9
•I «S I S 10
Problem: each size range covers t± different interval.
So"we can make any shape distribution we want just by using instruments
with certain size range intervals!
Obviously, there is a "true" distribution. Add new column in table:
d range
0.1 - 0.2
0.2 - 0.5
0.5 - 2
2 - 5
5-10
Cone
10
13
20
13.2
10
Cone * A log d
10 * (log 0.2 - log 0.1)
33.2
33.2
33.2
33.2
33.2
33-1
True distribution
uniform in log d
to
We can easily recover the mass concentration by integrating:
Mass cone, between 0.1 ym and 0.2 ym
log 0.2
Mass cone d log d
log dp
log 0.1
So area under this curve is equal to mass in any size interval.
104
-------
CONTENT OUTLINE
Course: 413 - Lesson 3a
Lecture Title: PARTICLE SIZING - PROBLEM SESSION* w°*
of.
NOTES
II. Problem 2-2.
A. Allow students 10 minutes to work on problem 2-2.
B. Go over the solution for 2-2.
The solution for 2-2 is:
(See Next Page)
Note; See problem
2-2 on page ,4 of
the 413 Student
Workbook.
105
-------
5 of 9
2.2 Log-normal distribution, geometric mean and standard deviation
Given the following particle size data:
Size Range Mass Concentration
dp in ym yg/m
< 0.1 0.04
0.1 - 0.2 0.76
0.2 - 0.5 15.07
0.5 - 2.0 68.26
2.0 - 5.0 15.07
5.0 -10.0 0.76
< 10.0 0.04
Verify that this distribution is approximately log-normal, and find
the geometric mean and the geometric standard deviation.
Hint: determine the percentage mass larger than d. max in each size
range. You don't need log probability paper to do this problem.
SOLUTION;
Mass
Verify bell-shaped curve Cone * A log d
0.76 * 0.301 - 2.52
37.9
113.4
37.9
2.52
(bell-shaped with a peak between\
0.5 and 2 ym 1
Better to use log probability paper and see if you get a straight line.
To find geom. mean and standard deviation, list % mass larger than d max.
mass cone.
Alog dp % Mass > d max Geom. mean = size
0.04 99.96%P midway between 15.87% size and
0 76 2 52 99 2 84.13% size on a log scale
15.07 37.9 84.13 Geometric mean = midway between
68.26 113.4 15.87 °'5 and 2 = l um
<0.1
0.1
0.2
0.5
2
5
>10
- 0.2
- 0.5
- 2
- 5
-10
0.04
0.76
15.07
68.26
15.07
0.76
0.04
15.07 37.9 0.8 Geometric Standard deviation
0.76 2.52 0.04 =o " 50% size = Ui5L
gm 84.13% size 0.5 .ym
0.04
Total 100.00 ye 106
-------
CONTENT OUTLINE
Course: 413 - Lesson 3a
Lecture Title: PARTICLE SIZING - PROBLEM
Page—§_of.
NOTES
III. Problem 2-3
A. Have students do problem 2-3 for homework.
B. Go over the solution for 2r3. The solution is:
(See Next Page)
Note; See problem
2-3 on page 5 in
the 413 Student
Workbook.
107
-------
7 of 9
2.3 Given the following distributions obtained from size differentiating
equipment:
Particle Size Distribution A Distribution B
dp (microns)
<.0.62
0.62 - 1.0
1.0 - 1.2
1.2 - 3.0
3.0 - 8.0
8.0 -10.0
< 10.0
3
yg/m
25.5
33.15
17.85
102.0
63.75
5.1
7.65
yg/m
8.5
11.05
7.65
40.8
15.3
1.692
0.008
(a) Is either distribution A or distribution B log-normal?
(b) If so, what is the geometric mean and standard deviation.
(Use the sheet of log probability paper provided on page 6 of 413
Workbook if necessary.)
SOLUTION;
Make a cumulative distribution plot on log-probability paper.
Distribution A
< 0.62 25.5 =
255
0.62 - 1.0
1.0 - 1.2
1.2 - 3.0
3.0 - 8.0
8.0 -10.0
>10
< 0.62 8.5 =
85
6.62 - 1.0
1.0 - 1.2
1.2 - 3.0
3.0 - 8.0
8.0 - 10.0
»10
% of total = 255 yg
m3
.10%
13
7
40
25
2
3
Distribution B
% of total = 85%
10%
13
9
48
18
2
0.01
cum % larger than
d mas
P
90
77
70
30
5
3
0
Cum %
90
77
68
20
2
0.01
0
108
-------
KME
PROOABILITV X LOUADITHMIC 359-24
KEUFFEL • ISSIH CO. ««OI l« U.i.H.
1 CYCLE*
10
99.99
99.9 998
I \ 0.5 02 0.1 O.OS 0.01
0.01
-------
9 of 9
2731 SOLUTIONS (cont'd)
1. Plot cumulative % larger than dp max versus d max on log probability
paper. "
2. If the flot yields a straight line the distribution is log normal.
Distribution A is log normal, distribution is not.
3. Geometric mean (for distribution A)
a - 50% size
** 84.13% size
0 = 1.9 ym 0 ,.
gm - _0 r— = 2.44
6 0.78 ym
110
-------
LESSON PLAN
TOPIC: METHODS FOR REDUCING
PARTICULATE EMISSIONS
COURSE: 413
LESSON TIME:
PREPARED BY:
Lesson 4
1/2 hour
. Beachler
4/79
LESSON GOAL:
Introduce the main methods for collection of particulate
emissions; emission reduction methods without the use of
emission control equipment.
LESSON OBJECTIVES:
At the end of the lesson the student should be able to:
* List four major ways to eliminate or reduce emissions
from an air pollution stationary source.
* List three modifications in the operation of a source
to reduce the emissions without the use of air pollu-
tion control equipment.
* Name the five basic types of emission control equip-
ment used for control of particulate emissions.
* List the forces used in the removal of particles
from exhaust gas streams.
* Recall the formula to calculate the efficiency of an
air pollution control device by weight.
STUDENT PREREQUISITE
SKILLS: Ability to understand basic principles of physical science.
LEVEL OF INSTRUCTION: Intermediate
INTENDED STUDENT
PROFESSIONAL BACKGROUND:
Engineering or Physical Science
SUPPORT MATERIALS
AND EQUIPMENT:
1. slide projector
2. overhead projector
3. chalkboard
4. 413 Student Manual
111
-------
REFERENCES: 1. 413 Student Manual
2. "Air Pollution Control Technology, an Engineering
Analysis Point of View," by Robert M. Bethea, Van
Nostrand Reinhold Company, New York, 1978.
pp. 61-105.
112
-------
AUDIO-VISUAL MATERIALS FOR LESSON 4
Lesson 4 Methods for Reducing Particulate Emissions
413-4-1 Reducing emissions
413-4-2 Dry collectors
413-4-3 Wet collectors
413-4-4 Forces used in collection equipment
413-4-5 Gravitation
413-4-6 Centrifugal force
413-4-7 Impaction
413-4-8 Direct interception
413-4-9 Diffusion
413-4-10 Electrostatic attraction
413-4-11 Evaluating a control device
413-4-12 Efficiency of a control device
113
-------
CONTENT OUTLINE
Course: 413
Lecture Title:
Lesson 4
METHODS OF PARTICLE COLLECTION
Page.
of-±
NOTES
I. Control Methodology
The technology of source control consists of all of the
sciences and techniques that can be brought to bear on
the problem of controlling air pollution. To eliminate
or reduce emissions from a polluting operation or to
reduce their impact, there are four major courses of
action.
• Substitute a different process, fuel, material,
or device
• Regulate the location of the operation
• Modify the operation
• Apply air pollution control devices
A. Substitute a different process, fuel, material or device;
1. The emissions from an operation or activity can be
removed by eliminating the operation. Examples:
(a) open burning - use of sanitary landfill
(b) single chamber incinerators — the use of
multiple chamber incinerators
(c) hand fired coal burning boilers — automatic
coal stokers or use of natural gas or oil.
(d) bee hive coke ovens — use of by-product
coke batteries.
B. Regulate the location of operation
1. Applying zoning ordinance to locate or distribute
sources of air pollution,
2. Imposing area limits on emissions rates that have
been derived from air quality standards.
Both approaches 1. and 2. may be implemented by
regulatory standards, land use planning and zoning
controls, and by special handling i.e. land use
permit cases.
3. New source construction permit programs which
prohibit emissions which cause NAAQS or PSD
increments to be exceeded.
4. Special handling option, i.e. can locate the air
pollution source downwind of the urban area of the
town — create uninhabited areas around the source.
114
Slide: 413 - 4-1
-------
CONTENT OUTLINE
Course: 413 Lesson 4
Lecture Title: METHODS OF PARTICLE COLLECTION
Page-2 of-J
NOTES
C. Modification of Operation
1. Control methods (without control devices)
2. Process change
(a) control of fugitive dust
(1) watering of roads
(2) paving roads with asphalt
(3) covering open bodied trucks that haul —
coal in or fly ash out
(4) storage piles of materials — control
sprays, cover, etc.
(5) enclosing of operation, i.e. sandblasting
from outside — to enclose area and use
hoods, fans, and ducting
3. Good operating practices — maintenance
(a) odors from food processing plants can be
eliminated by good housekeeping
(b) operating the equipment at the designed rate —
i.e. a rotary sand and stone drier for asphalt
plants when operated above design rate tends
to increase the dust emissions greater than
the increase in gas flow
(c) reclaiming scrap steel — strip the cars of
uphplstery, plastic, rubber before melting —
smoke from oily scrap can be avoided
4. Use of tall stacks
(a) use the appropriate stack height to eliminate
downwash and eddies from stack.
5. Change in fuel source
(a) use of oil or natural gas instead of coal — for
smaller sources
(b) use of low sulfur fuels
(c) pre-cleanlng — or washing of coals
115
-------
CONTENT OUTLINE
Course: 413
Lecture Title:
Lesson 4
METHODS OF PARTICLE COLLECTION
Page.
NOTES
6. Use CO from cat cracker for boiler fuel and eliminate
CO emissions
7. Use water instead of HC for carrier in paint operation.
8. Use atomizing burners instead of rotary cup burners
in process boilers.
9. Plant shutdown — as last resort
D. Apply Air Pollution Control Devices
This is what we will be dealing with most in this course —
the application of particulate air pollution control devices
1. We'll talk about the various types of control devices
(a) dry collectors
- gravity settling chambers
- Inertial separators ».
- cyclones
- electrostatic preclpitators
- fabric filters
(b) wet collectors, i.e.,
- wet scrubbers
- spray towers
- venturi scrubbers
- impingement plate scrubbers
- dynamic centrifugal scrubbers
2. We'll take a look at how the particles are collected
in each type of equipment and the forces used to remove
particles from a gas stream for each control device
such as:
* gravitational
* centrifugal
* impaction
* interception
* diffusion
* electrostatic
Slide: 413 - 4-2
413 - 4-3
Slides: 413 - 4-3
413 - 4-5
413 - 4-6
413 - 4-7
413 - 4-8
413 - 4-9
413 - 4-10
116
-------
CONTENT OUTLINE
Course: 413 - Lesson 4
Lecture Title: METHODS OF PARTICLE COLLECTION
NOTES
We'll look at each type of particulate control device
and characterize the equipment by looking at:
* particle size (specific efficiency)
* mass rate efficiency
* pressure drop
* space required
* initial cost
* operating cost
When calculating the collection efficiency (by weight)
of a specific type of control equipment in general
one would use the formula:
wt. in - wt. out
Slide:
413 - 4-11
Eff.
wt. in
Slide: 413 - 4-12
II. Review
The Important things we will be doing in looking at the various
types of particulate control devices will be
1. Look at the device and describe its basic operation
2. Look at the basic parameters of design and how to
utilize these parameters to calculate the efficiency
of the unit.
3. Work problems specific to each type of particulate control
device calculating:
a. pressure drop
b. efficiency
c. sizing dimension
Take a look at where these units are used in industries
and the restrictions of use of equipment.
4.
117
-------
118
-------
LESSON PLAN
TOPIC: SETTLING CHAMBER - PRINCIPLES,
OPERATION, AND APPLICATIONS
COURSE; 413 - Lesson 5
LESSON TIME: 1/2 hour
PREPARED BY: DATE:
David S. Beachler
4/79
LESSON GOAL:
Briefly describe the theory behind the collection
of particulates by settling chambers, their operation
and calculations.
LESSON OBJECTIVES:
At the end of the lesson the student should be able to:
* Describe the collection mechanisms which cause
particles to be collected in a settling chamber
* List two types of settling chambers.
* Recognize Stokes Law for determining the settling
velocity and calculate the settling velocity of
a particle in a settling chamber.
* Recognize and use the equation for determining the
minimum particle size collected in a settling
chamber.
* Calculate the collection efficiency of a settling
chamber.
* Describe the system design parameters used in
designing settling chambers.
STUDENT PREREQUISITE
SKILLS:
Ability to understand basic principles of physical
science
LEVEL OF INSTRUCTION:
Intermediate
INTENDED STUDENT
PROFESSIONAL BACKGROUND:
Engineering or Physical Science
119
-------
SUPPORT MATERIALS
AND EQUIPMENT:
1. slide projector
2. overhead projector
3. chalkboard
4. 413 Student Manual
REFERENCES:
1. 413 Student Manual
2. "Air Pollution Control Technology, an Engineering
Analysis Point of View", by Robert M. Bethea, Van
Nostrand Reinhold Company, New York, 1978, pp.106-116.
120
-------
AUDIO-VISUAL MATERIALS FOR LESSON 5
Lesson 5 Settling Chamber—Principles, Operation and Applications
413-5-1 Simple settling chamber
413-5-2 Collection mechanisms
413-5-3 Settling chamber
413-5-4 Howard settling chamber
413-5-5 Baffle chamber
413-5-6 Particle behavior in a settling chamber
413-5-7 Theoretical efficiency
413-5-8 Stokes law
413-5-9 Determining minimum particle size
413-5-10 Efficiency formula
413-5-11 Process design parameters
121
-------
CONTENT OUTLINE
Course: 413 - Reason 5 ,
Lecture Title: SETTLING CHAMBER PRINCIPLES
Page
of
NOTES
I. Introduction
Settling Chambers - used in industry to remove large solids
and .liquid waste from gas streams. Composed of very simple
design, low cost and maintenance, low pressure losses, and
simple disposal of collected materials — *used generally
as precleaner, spark arresters and sometimes used to cool down
exhaust gases.
II. Collection mechanisms — 2 main simple mechanisms — gravity
and inertia.
A. Gravity — Particle velocity reduced to such an extent
that particle will settle out under action of gravity.
Separation provided free by nature — generally limited
by particles > 40 microns in size.
B. Inertial forces — or momentum effect. In addition to
gravity successful separation depends on inertial or
momentum effect. This occurs by changing the direction
of the velocity of the gas and imparting a downward
motion to the particle.
III. Two types of gravity settler
A. Simple expansion chamber — consists long parallel box
with suitable inlets and outlet parts — gas enters one
end, larger particles settle out due to gravity forces,
gas exits other end. Velocity of gas slowed down due
to expansion in chambers, enabling particles to fall out
due to gravity.
B. Another type of gravity settler is called a Howard
Settling Chamber.
- consists of several thin horizontal collection
plates, to reduce the excessive volume requirements
to collect particles.
- vertically distance for collection has decreased
(may be as little as 1 inch).
- uniform distribution of gas is achieved by use of guide
vanes, distributor screens, or perforated plates.
One problem with Howard Settling Chamber is cleaning,
and also warping of trays possible when gas
temperature high.
Slide: 413 - 5-1
Slide: 413 - 5-2
Slide: 413 - 5-3
Slide: 413 - 5-4
-------
CONTENT OUTLINE
Course: 413 - Lesson 5
Lecture Title: SETTLING CHAMBER PRINCIPLES
Page.
of-L
NOTES
IV. Momentum separators
Use inertial or momentum forces in addition to gravity to
collect particles. Particules down to/W-20/y can be
4—_/
collected. Physical arrangement involves use of baffle.
Pressure losses .1 to 1 in H.O.
V. Particle velocity
Understanding the principles of collection in a gravity
settler begins with examining the behavior of a single
spherical particle.
Looking at a box to represent the settling chamber:
Inlet
Outlet
Dust x
let t =
Q = gas flow rate
H = height of chamber
B = width of chamber
let t = time required for particle to settle
8 _ H - distance
s~ v - terminal velocity
(same as v )
for captive t < t
S t
in the limit
„.
H/Vt =
LBH
v =
. t LB
Slide: 413 - 5-5
Slide: 413 - 5-6
Dust
= distance particle falls for capture
= horizontal velocity of gas
= vertical velocity of particle
residence time assume v particle velocity is (l)
X
equal to gas velocity
Note: See 413
Manual p.3-13 to
3-17 for derivation
123
-------
CONTENT OUTLINE
Course: 413 - Lesson 5
Lecture Title: SETTLING CHAMBER PRINCIPLES
Page.
of.
NOTES
VI. Particle Settling Theory — Efficiency
Now expressing the efficiency of the unit
« - \L x 100% Theoretical efficiency (3.2.9 in book)
v H
x
T) = fractional efficiency of particles
size d (one size)
P
v - vertical settling velocity
v = horizontal gas velocity
L = chamber length
H = distance particle must settle to be collected —
Chamber Height
Now, we had seen that the settling velocity given from
Stokes Law previously discussed as:
Slide: 413 - 5-7
assumption
is that the flow
through the settlin
chamber is laminar,
but that is not
.always the case.
This is the
theoretical
efficiency.
g
- p)
3.2.6 in manual
Slide: 413 - 5-8
Where v - settling velocity
g - acceleration due to gravity
d - particle diameter
p - density of particle
p • density of gas
M = gas viscosity
* Remember v applicable for Re# - 1.9
and a/18_JL4
5PpBL I
d *
P
1/2
3.2.7 in manual
where vt - ^
* - represents the limiting value since particles equal toj
or greater than the value will reach the collection
surface
* NOTE: (p - p) reduces to p because
Slider 413 - 5-9
NOTE: Equation\3.2.
assumes that 100%
collection '
efficiency of size
d will occur. How
ever, Stokes law
does not always
apply and this
equation can yield
some errors.
r
particle density
gas density
124
-------
CONTENT OUTLINE
Course: 413 - Lesson 5
Lecture Title: SETTLING CHAMBER PRINCIPLES
of—L
NOTES
Now we can state the efficiency
"g (Pp ~ p) L B
18 y Q
3.2.10 note
brackets
Slide: 413 - 5-10
NOTE: N = // of
parallelcchambers
where term in brackets is constant and is multiplied
by K which is an empirical factor (usually .5) when
test information is not available
Factors (1) all particles do not have free fall
(2) agglomeration during settling changes
particle size
(3) some particles are re-entrained
VII^ Equation for determining the effiency for a settling chamber
- Turbulent Flow
1. The flow through a settling chamber is almost always
turbulent.
2. The equation for efficiency is thus given by:
n - 1 - exp ~ t
L x J
where n = efficiency
L • length of chamber
H - height particle must fall (chamber height)
V = settling velocity
V = horizontal gas velocity
125
-------
CONTENT OUTLINE
Course: 413 - Lesson 5
Lecture Title: SETTLING CHAMBER
VIII. Process — Design parameters
1.
2.
3.
4.
Length -
Width -
Height -
Volume •
^•usually designed by Industry to
remove all particles above a specified
Slide: 413 - 5-11
1 particle size d *
^ P
(which involves above 1, 2, & 3)
Should be that sufficient residence time
for volume rate gas treated is provided
for capture of all particles of designed
size
5. Through-put velocity - rule of thumb
below 10 ft/sec
6. Through-put velocity should not exceed pick up velocity
given in Table 3.2.1.
IX. Review
The past 45 minutes we've talked about:
* collection mechanisms
* two types of settling chambers
* Stokes law for determining the settling velocity
of a particle
* The equation to determine the minimum particle size
collected in a settling chamber
* The equation to calculate the collection efficiency
of a settling chamber
* ..The system design parameters used in designing
settling chambers
126
-------
127
-------
LESSON PLAN
TOPIC: PROBLEM SESSION III
SETTLING CHAMBERS
COURSE: 413 - Lesson 5a
LESSON TIME: 15 minutes
PREPARED BY: D. Beachler DATE :
6/79
LESSON GOAL: Briefly describe the use of the settling velocity and
efficiency equations covered in the previous lecture
by solving two short problems.
SUPPORT MATERIALS
AND EQUIPMENT:
(1) chalk board
(2) 413 Student Workbook pp. 8-9
128
-------
CONTENT OUTLINE
Course: 413 - Lesson 5a
Lecture Title: SETTLING CHAMBERS - PROBLEM SESS'
Page—I—of.
NOTES
I. Problem 3-1
A. Have students turn to page 8 in the 413 Student
Workbook and begin working the problem 3-1.
B. Allow students 5 minutes to work problem then go
over the solution.
The solution to problem 3-1 is:
3.1 Settling Chamber — Minimum Particle Size
A hydrocholoric acid mist in air at 25°C is to be collected in a
gravity settler. The unit is 30 ft wide, 20 ft high, and 50 ft long.
The actual volumetric flow rate of the "acidic" gas is 50 ft^/sec.
Calculate the smallest mist droplet (spherical in shape) that will
be entirely collected by the settler. The specific gravity of the
acid is equal to 1.6. Assume the acid concentration to be uniform
through the inlet cross section of the unit.
Note; See page
8 in 413 in
Student Workbook
Assume Stoke's Law applies and at 25°C V
1 cp
6.72 x 10~4 lb
0.0185 cp,
ft-sec
SOLUTION:
The Important data are tabulated below:
T - 25°C (1) at 25°C
B - 30 ft
H - 20 ft
L • 50 ft
Q - 50 ft3/sec
p - 1.6
- .0185 cp x 6.72 x 10 lb .
ft-sec /
- 1.24 x 10"5 lb
ft-sec
cp
(2) The describing equation (since Stokes law applies)
dp(min)
dP
18yQ
% pp BL
]
'(18) (1.24 x 1(T5 lb ) 60 ft3)
ft-aec * sec'
(32.2 ft ) (1.6) x 62.4 lb (30 ft)(50 ft]
sec^ ft^
m
4.81 x 10"5 ft
129
spec Gravity
of air
or H20
1.0
.*. multiply by
62.4
-------
CONTENT OUTLINE
Course: 413 - Lesson 5a
•A
Lecture Title: SETTLING CHAMBERS - PROBLEM SESS
Page——of.
NOTES
II. Problem 3-2
A. Have students turn to page 9 In the 413 Student Workbook
and begin working on problem 3-2.
B. Allow students 5 minutes to solve problem and then go
over the solution.
The solution for problem 3-2 is:
3.2 Settling Chamber - Operating Efficiency
A gravity settler 5 meters wide, 10 meters long, and 2 meters high,
is used to trap particles with diameters of 10 ym. The gas flow
rate is 0.4 m /sec. Calculate the operating efficiency
of a settling chamber for the data given, below. Assume Stokes law
regime and a Cunningham correction factor pf 1.0.
p » 1.10 gin/cm
P _3
p - 1.2 x 10 gm/cm
Vi - 1.8 x 10~4
Note; See page 9
in 413 Student
Workbook.
cm - sec
SOLUTION:
n(d.
,) - f"g pp BL Nc"j
L 18 VQ J
- 980 cm/sec2 x 1.10 gm/cm x 500 cm x 1000 cm x 1 K (10 y x 1 x 10"
18 x 1.8 x 10-
.415 x 100%
41.5%
cm-sec
x 04 m3 x 106 cm3
sec
m
130
-------
LESSON PLAN
TOPIC: CYCLONES: PRINCIPLES,
OPERATION, AND APPLICATIONS
COURSE: 413 - Lesson 6
LESSON TIME: 45 minutes
PREPARED BY: DATE:
David S. Beachler
4/79
LESSON GOAL:
LESSON OBJECTIVES:
Briefly describe the basic design and principles of a
cyclone used for collection of particulate emissions.
At the end of the lesson the student should be able to:
1. Briefly describe a simple cyclone for particle collection
and describe how the gas stream and particles flow in
a cyclone.
2. Name two mechanisms used for the collection of particles in
a cyclone.
3. Describe the cut size and critical size of a particle.
4. Recognize the formula for cut size and calculate the
cut size for a specific cyclone.
5. Calculate the pressure drop across the cyclone using
the pressure drop equation.
6. Describe in general terms the physical features and mode
of operation of multiple cyclones.
7. Calculate the collection efficiency of a cyclone using
efficiency curves and particle size distribution data.
8. Recognize the sources where cyclones can and can't be
used in industry to collect dust.
STUDENT PREREQUISITE
SKILLS: Ability to understand basic principles of physical science
LEVEL OF INSTRUCTION:
Advanced
INTENDED STUDENT
PROFESSIONAL
BACKGROUND:
Engineering or Physical Science
131
-------
SUPPORT MATERIALS
AND EQUIPMENT:
1. slide projector
2. overhead projector
3. chalkboard
4. 413 Student Manual
REFERENCES:
1. 413 Student Manual
2. 413 Student Workbook
3. "Air Pollution Control Technology, an Engineering
Analysis Point of View," by Robert M. Bethea, Van
Nostrand Reinhold Company, New York, 1978.
4. "New Design Approach Boosts Cyclone Efficiency,"
Chemical Engineering November 7, 1978, by
Wolfgang H. Koch and William Licht. pp. 117-143
5. Leith, David and Mehta, Dilip, Cyclone Performance
and Design Atmospheric Environment Vol 7, pp 527-549,
1973.
132
-------
AUDIO-VISUAL MATERIALS FOR LESSON 6
Lesson 6 Cyclone Theory and Applications
413-6-1 Cyclone—live shot
413-6-2 Collection mechanisms
413-6-3 Cyclone—main parts
413-6-4 Simple cyclone—flow of gas
413-6-5 Cyclone with fines eductor
413-6-6 Critical size
413-6-7 Cut size
413-6-8 Cut size particle diameter equation
413-6-9 Size efficiency curve
413-6-10 Simple cyclone—typical dimensions
413-6-11 Pressure drop equation
413-6-12 Multiple cyclone
413-6-13 Cut size particle diameter equation
133
-------
CONTENT OUTLINE
Course: 413 Lesson 6
Lecture Title: CYCLONE THEORY AND APPLICATIONS
Page
NOTES
I. Introduction
A cyclone is known as a mechanical collector — a structure
without moving parts — that separates particulate matter from
the gas stream.
•
II. Collection Mechanisms
The collection mechanisms used for collecting particles
are 1. centrifugal force and 2. gravity
1. Centrifugal force — outward force created by the
cyclone arrangement — particles are forced to the
outside wall of the collector
2. Gravity — once the particles reach the wall,
the heavier particles are overcome by a
gravitational force and fall to the bottom of
the chamber
III. Description of cyclone
1. Inlet gas velocity is transformed (mechanically) into
a vortex which is confined within a structure
(a) gas enters the cyclone tangentially
(b) vortex spirals downward (main vortex) and near
bottom of cone — reverses in direction and spirals
upward — core vortex. Spiralling action of gases
causes particles to be driven to the walls where
they collect (on the surface) and move downward by
force of gravity.
(c) Spiral motion of both vortexes spirals in the same
direction. Tangential velocity (gas swirl spread)
is lowest near the wall and at the center of the
cyclone. It reaches the maximum approx. 60-70% in
from the wall towards the center of cyclone.
(d) Two opposing forces — outward centrifugal force and
inward drag force which is a function of the
[FD = K_^v4 y]density, particle shape and diameter;
K. i p
whenever centrifugal force > drag force, particles
will reach walls and be collected.
134
4U-6-1
413-6-2
413-6-3
413-6-4
NOTE: Centrifugal
3 2"
F = p d J v
s P P P
-------
CONTENT OUTLINE
Course: 413 - Lesson 6
Lecture Title: CYCLONE THEORY AND APPLICATIONS
(e) Vortex arrestor (is the hopper) at the bottom —
where the gases reverses bulk flow directions
(f) (1)
Back
fixing
(g)
(h)
Eddy currents (plagues efficiency) generate at
top of unit where dirty gas is introduced.
Turbulence of eddies causes some dirty gas to
be mixed with clean gas. Problem can be partiall
eliminated by use of a vortex finder — projects
into body of cylinder.
(2)
(3)
Also can add a fines eductor or skimmer — bleeds
out very fine particulates which tend to
accumulate at top. The small purge stream of
gas is re-introduced close to the wall just
before start of the tapered section. Fines
are fed into the wall where they are bombarded
by other particles being thrown against the
wall and .'. increased efficiency.
Particles have a tendency to bounce off
cylinder wall back into inner vortex — can be
eliminated by water sprays along the sides of
the cyclone. Walls should be smooth for good
efficiency and low pressure drop.
Inlets — air inlets also play a major role in
reducing eddy currents. Air is squeezed to about
half of the inlet width to reduce the interference
of the incoming gas and the vortex finder —
Helical and involute inlets are used *[see p. 4-10
in manual]. Also used are vanes (inlet vanes) called
axial inlet. Vanes must resist erosion and plugging.
Discharge Bin — (can be a problem)
Since static pressure in core is slightly negative,
the collected dust will be drawn up into vortex core
to discharge to the atmosphere.
Solution is a mechanical device
(1) rotary valve
(2) double flap valve
(3) screw conveyer
*>
-------
CONTENT OUTLINE
Course: 413 Lesson 6
Lecture Title: CYCLONE THEORY AND APPLICATIONS "**Pnot
Page-1 of.
NOTES
The function of this device is for the continuous
complete immediate dust removal and prevent inflow
of air from hopper.
IV. Determination of critical particle size and cut size
When performing calculations for the efficiency of a cyclone
we need to look at the critical size and cut size.
1. Two sizes used to relate to the efficiency of the
cyclone. Their derivation is not presented here in the
lecture. NOTE: They should not be used for original
calculations, but rather to compare efficiencies of
similar cyclones.
2. Critical particle size is defined as the size of the
smallest particle which can be removed completely. 100%
efficiency.
3. Also a convenient way to define the efficiency is by
use of the term cut size. It is the size of particle
collected with 50% efficiency. The cut size depends
on the gas and particle properties, the cyclone size
and operating conditions
[d ] cut = /9 u B
P
where [d ] cut =
P
B = width of gas inlet (ft)
N = Number of revolution gas stream
makes - (3-10) generally 5
(dimensionless) unless manufacturer
states otherwise
v. • inlet velocity, ft/sec
3
p = particle density #/ft
3
p = gas density #/ft
136
413-6-6
NOTE: Red particle
on slide represents
of
413-6-7
NOTE: Red particle
on slide represents
the particle of cut
size.
413-6-8 -
NOTE:
\Zq. 4.2.1 in
Manual)
NOTE:
N can be calculatec
See pages 4-23 -
4-24 in 413 Manual
-------
CONTENT OUTLINE
Course: 413 Lesson 6
Lecture Title: CYCLONE THEORY AND APPLICATIONS
Page.
of.
NOTES
4. Looking at a size-efficiency curve is a plot of different
particle sizes related to removal efficiencies for a
certain cyclone
collection
efficiency
100-
50
0
C (90u)
critical size
2040 6080 100
Particle size, microns
IV.
Size efficiency curve
Relative Dimensions
Several dimensional proportions are used in a cyclone
design (see slide) (See example in book 4.2.1, 4.2.2, 4.2.3)
1. Usually start out specifying body diameter D
2. Dimensional proportions
(a) height to width of inlet
(b) vortex finder diameter to cyclone body diameter
(c) body diameter to vortex arrestor diameter
(d) length of cylindrial body to tapered section
(e) length of vortex finder to body diameter and
inlet height.
*Principal dimension is the body diameter because
it governs capacity of the cyclone at a reasonable
pressure drop.
The overall length determines the # of turns gas makes
The inlet dimension determines the velocity and thus
centrifugal force applied to the particles.
Note these and other dimensions are fixed by the
designer in accordance with particle collection require-
ments and volume of gas handled.
V. Pressure Drop Determination
1. Pressure drop across a cyclone varies from 1 to 7
inches of water
137
*3.
4.
5.
6.
413-6-9
Point out
1. cut size
2. critical size
413-6-10
Point out in
manual 4.2.1,
4.2.2, 4.2.3
NOTE:
(B is real importai
GSee IV-3)
-------
CONTENT OUTLINE
Course: 413 Lesson 6
Lecture Title: CYCLONE THEORY AND APPLICATIONS
NOTES
VI.
2. An equation does exist for computing pressure drop
for several conditions. For geometrically similar
cyclones.
.0027 Q
k D
equation 4.2.7 In manual
1/3
where:
Ap = pressure drop, in H.O
Q = volumetric flow rate at the inlet, ft /sec
diameter of gas
inlet width, ft
D = diameter of gas outlet, ft
B
c
H
inlet height, ft
height of cylinder, ft
D = cyclone diameter, ft
Z = height of cone, ft (tapered section)
c
k = diamensionless factor descriptive of cyclone
inlet vanes - 0.5 without vanes, 1 for vanes
that do not expand the entering gas or touch
the gas outlet wall (a in Figure 4.2.12), and
2.0 for vanes that expand and touch the gas
outlet wall (b in Figure 4.2.12).
Remember that the cyclone dimensions (6 , H , etc.) are
c c
the inner dimensions. For example, B is the inside
width of the duct, not including any lining, etc.
*(Figure 4.2.12)*
Types and arrangements of cyclones
1. Individual high efficiency cyclone must be small
in diameter and have a small capacity — thus they are
operated in parallel multiples to handle typical gas volume
Battery has common inlet chamber (plenum), common
outlet plenum, and common dust collection system.
Chambers must be designed for constant AP in each
138
413-6-11
-------
CONTENT OUTLINE ,
^——— I
Course: 413 Lesson 6 \
Lecture Title: CYCLONE THEORY AND APPLICATIONS
Page—b—of
NOTES
VII.
cyclone to avoid channeling of dirty gases to any one
cyclone or group (least resistance effect.)
Multicyclone (vane axial cyclone) 413-6-12
(a) common gas inlet
gas outlet
hopper
(b) virtually no eddies and loss of fines because there
is no tangential or involute entrance.
(c) pressure drop in multicyclones is 4-6 in H«0.
(d) should not be used for hygroscopic or other "sticky" materials because
vanes would plug up causing pressure drop problems.
Cyclones in series
(a) additional pressure drop makes series arrangement
a disadvantage.
(b) single large cyclones may be used as a precleaner
for multiple cyclones to prevent them from plugging.
Determination of Overall Efficiency
1. To predict the overall efficiency (collection). The
size-efficiency curve and a particle size distribution
are required.
2. Note that the size efficiency curve applies to that
designed cyclone collecting a certain type dust and
would only apply to a cyclone with similar gas and
particulate conditions.
3. Method for determining efficiency
(a)
(1)
(2) * Lapple's technique — using Figure 4.2.4
p. 4-20 conventional cyclone
determine [d ] cut
P
can do by equation [d ] cut
* For other conditions multiply [d ] cut by
correction factors 4.2.5, 4.2.6
(b) Use a size efficiency curve
(1) cyclone efficiency vs. particle size
ratio — Lapple 1951. Using a graph like 4.2.7
* Particle size as a function of the particle
size ratio.
139
Work problem
4.1 in workbook
413-6-13
See figures
4.2.4 and 4.2.5
in 413 manual
See figures
4.2.7 in 413
manual
-------
CONTENT OUTLINE
Course: 413 - Lesson 6
Lecture Title: CYCLONE THEORY AND APPLICATIONS
Page
NOTES
(c)
(2) Particle size distribution
Divide the particle-size distribution of
the dust to be collected into ranges OR can
use a curve like figure 4.2.8 — "Typical
Particle Size Distribution"
Multiply the weight fraction for each size range by
the collection efficiency determined (above). The
summation gives the overall collection efficiency.
See figure 4.2.8
in 413 manual
VIII. Cyclone performance - other methods for efficiency determination
1. The following information was taken from a paper written
by David Leith and Dillip Mehta (see reference listing).
CYCLONE COLLECTION EFFICIENCY
NOTE: This section
Ls optional and can
>e included in this
Lesson.
Cyclone fractional efficiency is the weight of particles
of a stated size collected in the cyclone, divided by the total
weight of particles of that size going to the cyclone.
Experience in dealing with cyclones has shown that collection
efficiency increases with:
(1) Increasing particle size and density.
(2) Increasing speed of rotation in the cyclone vortex.
Decreasing cyclone diameter.
Increasing cyclone length
(3)
(4)
(5)
Drawing some of the gas from the cyclone through the dust
exit duct.
(6)
Wetting the cyclone's walls.
A cyclone's grade efficiency curve relates size of particlejs
going to the cyclone to the cyclone's efficiency on particles
of that size. Note that efficiency continuously increases
with increasing particle diameter, and approaches 100 per cent
asymptotically for sufficiently large particles.
140
-------
CONTENT OUTLINE
Course: 413 - Lesson 6
Lecture Title:
CYCLONE THEORY AND APPLICATIONS
Page.
of.
NOTES
Critical size approach to cyclone efficiency
The efficiency of a cyclone is sometimes characterized by
its. particle "critical size" (the size of particles calculated
to be collected with 100 per cent efficiency), or by its "cut
size" (the size of particles calculated with 50 per cent
efficiency). As discussed above, actual collection efficiency
approaches 100 per cent asymptotically for larger particles.
The critical size particle then, while calculable from theory,
is not observed experimentally.
2. Leith has given an equation to calculate the efficiency
of a cyclone:
= 1 - exp -2(C>O
l/(2n+2)
The terms in this equation are C
Which can be calculated or picked from a table for standard
design cyclones; ¥ is a term for the inertial impaction
parameter and given by
p d v
_P P
! (n + 1)
18uGD
and the value of n can be picked from a single figure and
depends on cyclone diameter and gas temperature.
IX- Applications
1. Cyclones generally used to collect larger particles
(> 20 microns in size). Multicyclones can collect down to
5-10 microns in size.
2. Sometimes used as pre-cleaners to a baghouse, ESP or scrubber
HI
-------
CONTENT OUTLINE
Course: 413 Lesson 6
Lecture Title: CYCLONE THEORY AND APPLICATIONS
Page .3.— of.
NOTES
3. Cyclone pressure drops vary depending on the size and the
design.
a. low efficiency cyclones - 2-4 inches of water
b. medium efficiency cyclones - 4-6 inches of water
c. high efficiency cyclones - 8-10 inches of water
d. multicyclones - 4-6 inches of water
4. Cyclone sizes vary depending on their use and design.
a. 5000 - 10,000 CFM per unit (up to six in a group)
for cyclones.
b. 25,000 -100,000 CFM for multicyclones.
5. Cyclones can be used in various industries such as iron
and steel, asphalt, grain milling, cement, paper, chemical,
coal cleaning, etc. The efficiency of the collectors will
be dependent on the particles being handled, the gas volume
and the size of the unit. Table 4.3.1 on page 4-34 of the
manual lists various cyclone applications in industry.
X. Review
We have discussed the past hour the following subjects:
* collection mechanisms involved for particle capture
* basic operation of the cyclone including the
• inlet
• vortex spiral
• vortex arrestor
• vortex finder
• discharge bin
* defined the cut size and the critical size
* the equation used to calculate the cut size
* the equation used to calculate the pressure
drop across a cyclone
* cyclone collection efficiency using efficiency
curves and particle size distribution data.
142
-------
143
-------
LESSON PLAN
TOPIC: PROBLEM SESSION IV
CYCLONES
COURSE: 413 - Lesson 6a
LESSON TIME: 45 minutes
PREPARED BY: DATE: 6/79
David S. Beachler
LESSON GOAL:
Briefly describe the use of the cut size determination,
pressure drop, and collection efficiency equations
covered in the previous lecture by solving four problems.
SUPPORT MATERIALS
AND EQUIPMENT:
1. Chalkboard
2. 413 Student Workbook pp. 10-16
144
-------
CONTENT OUTLINE
Course: 413 - Lesson 6a
Lecture Titles
CYCLONES - PROBLFM SESSION IV
Page
of.
13
NOTES
I. Problem 4-1
A. Work out problem 4-1 for the students. The solution for
4-1 is:
See attached sheets
145
NOTE:
See problems 4-1
on page 10 of the
413 Student Work-
book.
-------
2 of 13
4.1 Cyclone — Overall Collection Efficiency Using Lapple's Method
The particle size distribution of a dust from a cement kiln is provided
below:
Particle Size
(Average size in range)
microns
1
5
10
20
30
40
50
60
> 60
% Wt
3
20
15
20
16
10
6
3
7
The following information is also known:
Gas Viscosity
Particle Specific Gravity
Inlet Gas Velocity to Cyclone
Effective Number of Turns within Cyclone
Cyclone Diameter
Cyclone Inlet Width
0.02 centipoise (cp)
2.9
50 ft/sec
5
10 ft
2.5 ft
(a) Determine the cut size particle diameter, I.e., diameter
of particle collected at 50% efficiency, and estimate the overall
collection efficiency using Lapple's Method.
(b) If the same cyclone is used, but the inlet gas velocity is
increased to 60 ft/sec and the gas viscosity changes to 0.018 cp
due to a temperature decrease (all else remaining the same), find
the new cut size particle diameter and determine the new overall
collection efficiency using Lapple's Method.
SOLUTION:
(a)
P cut
9 U B,
2 Nt
(Pp-p) *
9 x (.02 x 6.72 x 10 ~41b ) x 2.5
cp
sec ft
2 x (5) x 50 ft x (2.9 x 62.4 Ib ) (IT)
sec Tt7
.5
3.2 x 10~5 ft x 30.48 x 104 um/ft.
Note:
= 9.9 urn
p gas much less
than p
Pp-P
P' '
P.
146
-------
3 of 13
A.I (a) cont'd
Alternatively Lapple provides a curve to determine the cut size particle
diameter Figure 4.2.4 in the manual. From Figure 4.2.4 d cut is approximately
9.9 (NOTE: one must project graph to be able to read out size for a 10 ft diameter
cyclone).
construct table
microns
1
5
10
20
30
40
50
60
760
wt%
3
20
15
20
16
10
6
3
7
P dp cut
.0101
.505
1.01
2.02
3.03
4.04
5.05
6.06
T\ % from
Figure 4.2.7
nil
20%
50%
80%
90%
94%
97%
99%
100%
wt fraction %
x n%
0
.040
.075
.160
.144
.094
.058
.030
.07
.671
Collection efficiency = 67%
4.1 (b) Since inlet conditions have varied, it is necessary to apply the
correction factors to the particle cut size diameter previously
determined
Inlet velocity correction (from 4.2.5)
= .92
Viocosity correction (from 4.2.5)
= .95
Corrected cut size = (dp)cut (.92)(.95)
= 9.02
147
-------
A.I (b) cont'd
4 of 13
wt
p cut (new)
1
5
10
20
30
40
50
60
760
3
20
15
20
16
10
6
3
7
.111
.554
.90
2.22
3.33
4.43
5.54
6.65
_ — _
n% (from)
(4.2.7)
__„
24 (.20)(.24)
45
83
91
94
96
98
100
Wt fraction
x TI %
0.0
= 0.048
.0675
.167
.146
.094
.058
.029
.07
.680
New overall collection efficiency is approximately 68%
148
-------
CONTENT OUTLINE
Course: 413 - Lesson 6a
Lecture Title:
CYCLONES - PROBLPM SESSION IV
Page.
of.
13
NOTES
II. Problem 4-2
A. Work out problem 4-2 for the students. The solution for
4-2 is:
NOTE: See problem
4-2 on page 11 of
the 413 Student
Workbook
4.2 Cyclone — Dimensions and Number of New Cyclones Required
A large-diameter conventional cyclone (no vanes) handles 5,000 ACFM
of a particulate-laden gas exhaust stream (p. «• 0.076 Ib/ft ) from
b
a certain metallurgical operation. The cyclone diameter is 4 ft.
The remaining dimensions may be found from Figure 4.2.1 (in the manual),
In an attempt to increase efficiency, a group of new cyclones is to be
designed with the same geometrical proportions and pressure drop
as the single cyclone. If the diameter of the small cyclone is to
be 6 in., what will the dimensions of the new group be? How many
cyclones will be needed to handle the original flow rate at the same
pressure drop?
SOLUTION; Cyclone Dimensions (ft) - ?
From
4.2.1
Ap
old
OLD
4
1
2
2
8
8
.0027 Q2
Dimension
D
c
B
c
Hc
De
Lc
i z
c
New
.5
.125
.25
.25
1.0
1.0
BCHC
.5 No vanes
Ap
- 2.95 in H20
149
-------
CONTENT OUTLINE
Course: 413 - Lesson 6a
Lecture Title: CYCLONES - PROBLEM SESSION iv
SglgZ?
Sv^"^^^rf
~«F
NOTES
4.2 cont'd
Ap
new
- 2.95 - .0027 (Q)2
(.5)(.25)2(.125)(.25)( ±
»3
Q
Q
1.7
1.3 ft3/sec per new 6" tube
5000 ACFM
60aec/min
/ l.rtubT ' 6A «u»ber of tubes
Note that the inlet velocities for the old and new cyclones will be exactly
the same.
(V^ old - 83.3/(l)(2) - 41.6 ft
,+ 4 aec
Bc Hc
(v1) new - 1.3/(.125)(.25) • 41.6 ft
sc
Bc Hc
III. Problem 4-3
A. Have students turn to page 12 in the 413 Student Workbook
and begin working problem 4-3.
B. Allow students 10 minutes to work the problem; and then go
over the solution.
The solution to problem 4-3 is:
(See next 2 pages)
150
NOTE: See problem
4-3 on page 12 of
the 413 Student
Workbook
-------
7 of 13
4.3 Cyclone — Overall Collection Efficiency
(a) The size, mass, and cyclone collection efficiency data for a gas containing
limestone dust are given below.
Particle diameter, ym
0-5
5-10
10-20
20-30
30-50
50-75
75-100
100-200
200-
Wt %
2
8
13
26
12
11
9
8
11
Collection efficiency.
4
6
20
32
78
89
95
98
99+
Calculate the overall collection efficiency of the unit.
SOLUTION: is given by the product of the weight fraction and the collection
efficiency for each size range. The following table provides the
results.
Weight
d urn
P
0- 5
5-10
10-20
20-30
30-50
50-75
75-100
100-200
200-
fract:
.02
.08
.13
.26
.12
.11
.09
.08
.11
n %
4
6
20
32
78
89
95
98
99
(weight fraction)(n % )
(.02)(4%) =
(.08)(6%)
.08
.48
2.60
8.32
9.36
9.79
8.55
7.84
10.89
57.91%
151
-------
4.3 Cyclone — Mass of Dust Collected
If the inlet dust loading in the previous problem is 2.2 grains/ft
and the quantity of gas processed is 150,000 ACFM, calculate the
mass of limestone collected daily.
o
SOLUTION; * Since the grain loading is 2.2 grains/ft , the mass collected per
cubic foot of air is given by
(2.2X.58) = 1.28 grains/ACpM
f
efficiency
Daily mass collected is
150,000 ACFM x 1.28 grains x 60 min x 24 hr = 276,480,000 grains
ACFM hr day day
2.76xj.O^ - 39,497 Ib/day
7000 grains/lb limestone collected
152
-------
CONTENT OUTLINE
Course: 413 - Lesson 6a
Lecture Title: CYCLONES - PROBLEM SESSION iv
Page*. of
NOTES
IV. Problem 4-4
A. If time permits, have students turn to problem 4-4
on page 14 of the 413 Student Workbook and begin solving
for the collection efficiency.
B. Allow students 10 minutes to solve problem 4-4; then go over
the solution.
The solution for problem 4-4 is:
(See next 4 pages)
NOTE:
See problem 4-4
on page 14 of the
413 Student Workboo
153
-------
10 of 13
A. A Cyclone Collection Efficiency
Determine loss and collection efficiency for a cyclone from the
following information.
(1) size-efficiency curve
(2) size distribution by weight
Particle size % by Wt
Micron Less than
10 .1
15 1.0
26 10.0
AO 32.0
67 70.0
100 90.0
+100 100.0
(3) weight of inlet loading - 50 Ib/hr.
154
-------
11 of 13
4.4
SOLUTION
Using the size efficiency curve provided and data given, the following table
can be constructed:
Particle
Size
Range
0
10
15
26
40
67
>
- 10
- 15
- 26
- 40
- 67
-100
100
Mean Size % by
Particle Efficiency Weight
Size in range Curve Within range
% collected
5
12.5
20.5
33
53.5
83.5
28
52
68
82
93
99
100
.1 1
.9
9.0
22.0
38.0
20.0
10.0
Inlet
lb
hr.
M%)(50)= .05
.45
4.5
11.0
19.0
10.0
5.0
Outlet
lb
hr.
(.72) (.05
.22
1.44
2.00
1.65
.1
0
50.00
5.44
AEfficiency = inlet - outlet x 100%
inlet
- 50 - 5.44 x 100
50
155
-------
100
o
5'
9
o
§
microns size-efficiency curve for medium-efficiency
high throughput cyclone
O
Ml
U)
-------
Par
cle
Oi
crons
1UU
90
HO
70
60
50
40
30
20
2
0.
_^
S^
.
f
X
X
/
S
S
_^
/
/
_^
/
/
rS
LT
X
,x
7
^
-------
LESSON PLAN
TOPIC: ELECTROSTATIC PRECIPITATOR
PRINCIPLES AND OPERATION
COURSE: 413 - Lesson 7
LESSON TIME: 1 hour 15 minutes
PREPARED BY: DATE:
G. J. Aldina
Revised by David Beachler 2/21/80
LESSON GOAL:
LESSON OBJECTIVES:
SPECIAL INSTRUCTIONS:
To familiarize the student with the basic theory of
electrostatic precipitation of particles and the
fundamental design considerations for building an ESP.
The student should be able to:
1. List three structural components of an ESP
List three different types of ESP's
2.
3.
5.
6.
Identify the three basic functions of an electrostatic
precipitator.
Describe each of the following basic mechanisms
of the electrostatic precipitation process:
• Gas ionization by corona discharge
• Particle charging
• Particle migration to the collection electrode
• Loss of the particle electric charge at the
collection electrode
• Electric wind
Describe the ESP collection electrode cleaning process
Write an equation for ESP efficiency calculations
7. List the advantages of the ESP that make it a
desirable control device.
This lecture is intended to introduce the student to
principles and operation of an electrostatic precipitator.
The intent of this lecture is to focus on how the precipitator
charges the particles and their subsequent collection at the
collection plate.
In the following lecture, "Design and Applications", the
intent will be to cover the finer design aspects of the ESP.
The focus will be on typical design parameters, particle
resistivity, common operating problems, operation and
maintenance techniques and some applications of ESP's
used for control of particulate emissions.
158
-------
REFERENCES: 1. 413 Student Manual
2. Nichols, G. B., Seminar on ESP Theory
3. Gothchlich, C. F., Removal of Particulate Matter
from Gaseous Wastes, American Petroleum Inst.,
N. Y., N. Y., 1961, Report on ESP
4. 413 Student Workbook
159
-------
AUDIO-VISUAL MATERIALS FOR LESSON 7
Lesson 7 Electrostatic Precipitator Principles and Operation
413-7-1 ESP live shot
413-7-2 ESP schematic
413-7-3 Types of ESP
413-7-4 ESP schematic—single stage
413-7-5 Types of ESP
413-7-6 ESP—two stage
413-7-7 Types of ESP
413-7-8 ESP—water walled
413-7-9 Functions of an ESP
413-7-10 Discharge wire
413-7-11 Electric field increased
413-7-12 Corona discharge forms
413-7-13 Corona discharge—free electrons collide with gas molecules
413-7-14 Avalanche multiplication
413-7-15 Avalanche multiplication
413-7-16 Avalanche multiplication
413-7-17 Particle migration
413-7-18 Particle migration to collection electrode
413-7-19 Migration velocity
413-7-20 Particle removal—rapping
413-7-21 Particle removal—falling into hopper
413-7-22 Particle removal—removal from hopper
413-7-23 Probability of particle in the boundary capture layer
413-7-24 Collection efficiency formula
413-7-25 Power requirements
413-7-26 Power requirements—work on particle
413-7-27 Particle reached the terminal velocity
413-7-28 Work—power requirement
413-7-29 Particle migration velocity
413-7-30 Relationships between particle size, particle migration velocity,
ESP power required
413-7-31 High collection efficiency
413-7-32 Economical to operate
160
-------
413-7-33 Treat large volumes of gas
413-7-34 Flexible for various gas temperatures
413-7-35 Long useful life
413-7-36 Long useful life
413-7-37 Long useful life
161
-------
CONTENT OUTLINE
Course: 413 - Lesson 7
Lecture Title: ESP _ PRINCIPLES AND OPERATION
Page J— of-L
NOTES
413-7-1
NOTE: make sure
all structural
component are
described
I. Lecture Introduction Live shots
The fundamental principles underlying the application of
electrostatic forces to precipitate particles suspended in a
gas were known in the 18th century. The successful development
of a device that employed electrical gas cleaning methods did not
take place until professor Fredrick Cottrell designed and built
the first industrial ESP at the Detroit-Edison Trenton Channel
Steam generator in 1923. Today there are more than 1300 ESP's in
operation for the control of fly ash emissions from steam generator
The ESP is also an effective device for controlling emissions from
cement kilns, pulp and paper plants, acid plants, sintering
operations, etc. It is extensively used where dust emissions are
less than 10-20 ym in size with a predominant portion in the
submicron range.
The electrostatic precipitator is comprised of basically three
essential components which we will discuss in detail later in the 413-7-2
lecture.
They are:
1. Discharge electrode
2. Collection electrode
3. Rappers
1. Discharge electrode - wires that vary in shape, but are
usually a small diameter wire (.1 in.) where the corona
discharge occurs. We will discuss this in greater detail a
little later.
2. Collection electrode - consist of either a tube of flat plate
which is oppositely charged (relative to discharge electrode)
and it is the surface where the charged particles are collected
3. Rappers - are used to dislodge the dust at the collection
electrode.
[I. There are several types of ESP to consider. We will deal with the
type used most by power plants.
1. Negative discharge single-stage ESP
a. Discharge (corona) electrode has negative polarity.
b. High-voltage is used to creat stronger electric field
before reaching spark-over
c. Particle charging and migration field created in one area
simultaneously.
NOTE: Point out
components
413-7-3
413-7-4
162
J
-------
CONTENT OUTLINE
Course: 413 - Lesson 7
Lecture Title:
ESP - PRINCIPLES AND OPERATION
Page 2 of-lL
NOTES
d. Not used for air conditioning applications because of
high ozone formation
e. Two types - tube; plate
2. Two-stage ESP
a. Generally used for air purification or air conditioning
applications
b. Separate charging and collecting areas
c. Positive polarity to cut ozone
d. Lower voltage drop
3. Wet-walled Precipitator — cleaning is achieved by H20 spray
or agglomerated E~0 droplets.
III.The precipitator provides three essential functions
A. Charging suspended particles
1. Particle charging accomplished by ions
2. Ions produced by high voltage direct current corona
B. Charged particles are subjected to an electric field which
drives them to the collection electrode
1. Collection forces are applied directly to the particle;
% 3000 times force of gravity
2. Mechanical collectors treat the whole mass of gas
a. Precipitators much lower energy requirements
b. Extremely low draft losses
C. Particles at the collection electrode must be removed and
carried away
1. Dry ESP - rapping (impact or vibration)
2. Wet ESP - water walled collection electrode
D. This gives basic overview of the ESP. We want to get into the
fundamentals of these operations.
IV. Gas lonization and Particle Charging
A. Accumulated charge — most particles have some
1. Frictional electrification
2. Flame ionization
3. These are not large enough for economical operation of
the ESP
B. Corona Discharge (Assume plate type ESP)
1. Corona is produced by applying a high d-c electrical field
between two electrodes
163
413-7-5
413-7-6
413-7-7
413-7-8
413-7-9
413-7-10
-------
CONTENT OUTLINE
Course: 413 - Lesson 7
Lecture Title: ESP - PRINCIPLES AND OPERATION
Page.
NOTES
a. High negative voltage is applied to the electrode with
a small radius
b. The other electrode is a large plate (relative to wire
c. The large electrode or plate is the collecting
electrode
2. The electric field is increased until corona starting
voltage is reached
a. No current flows between electrodes until this point
b. Electrical breakdown of gas surrounding the discharge
electrode begins
c. Blue glow around electrode — ultraviolet radiation
from positive ions striking the wire.
3. Increased voltage continues until spark-over voltage is
reached
a. Corona discharge — is intense electrical breakdown
of gas adjacent to small radius electrode
b. Spark over — electrical breakdown of gas only in
narrow paths of spark to collection electrode
4. The intense electric field close to the discharge
electrode accelerates electrons
a. Electrons can be emitted from wire
b. Some ion-pairs exist in a gas at STP
c. Sluggish positive ions move toward discharge
electrode (produce electrons by secondary emissions -
photoemission)
d. Free electrons are accelerated and collide with gas
molecules (particles)
5. When the applied electric field reached a critical value
the free electrons acquire enough energy between
collisions to remove a gas molecule valence electron.
6. The free electrons continue to accelerate and ionize
other neutral gas molecules
a. This is called Avalanche Multiplication
b. The corona starting voltage can be calculated - but
we will not cover that here
c. This voltage (power) requirement is uniquely
determined by gas density.
164
413-7-11
413-7-12
Slides are
organizers. Use
notes (add or sub-
tract as necessary)
413-7-13
413-7-14
413-7-15
413-7-16
-------
CONTENT OUTLINE
^o SB,,
Course: 413 - Lesson 7
Lecture Title:
ESP - PRINCIPLES AND OPERATION
Page—L—of-L
NOTES
d. Pressure and temperature effect corona through their
effect on gas density.
e. To get lowest starting voltage you need smallest
radius discharge electrode possible. Usually
0.05 - 0.15 in.
7. a. As the electrons leave the corona region and enter the
inter-electrode region, where the magnitude of
electric field is diminished, electron velocity
decreases.
b. When electrons impact on gas molecules in the inter-
electrode region, they are captured, and negative gas
ions are created.
c. The stable concentration of negative ions migrating
toward the grounded electrode produces a small space
charge in the inter-electrode region.
d. Increases in applied voltage will increase electric
field strength and ion formation, until the avalanche
formation of positive ions extends across the inter-
electrode region and spark over occurs.
C. Field charging (particles > 2.0 microns) 0.5 ym too
1. Field charging of particles suspended in the gas stream is
related to directed flow of ions in the interelectrode
space.
2. Partlculate in the interelectrode space
a. Dielectric constant greater than 1
b. Local electric field lines will be distorted toward
the particle
c. Ions follow the electric field lines - maximum
voltage gradient
d. Ions impact on the particles and are held by image
charge forces
e. Particle gains charges - negative ions
3. This charge is negative because it is acquired in the
area close to the discharge electrode where negative ions
are moving toward the collection electrode
165
413-7-17
-------
CONTENT OUTLINE
Course: 413 - Lesson 7
Lecture Title: ESP - PRINCIPLES AND OPERATION
NOTES
The charge on the particle is usually acquired in ^ 0.01
seconds
4 IT e r E
o cp
e • permittivitity of free
space 8.86 x 10~12 F/M
Maximum
charge
? = 12 ir
3 ^P - 2[(K-l)/K+2] + 1 E = charging field V/m
K - particle dielectric constant
V.
e r2E
o c
5. As the particle is bombarded it gains enough charge to
create a self-field until it reaches saturation charge
2.
3.
6. It will then move toward the collection electrode
D. Diffusion Charging (particles < 0.2 urn)
1. Related to random motion of ions owing to their thermal
velocity
Average gas molecule velocity related to temperature
Some molecules will have very high velocity and collide
with the small particles
Particle Migration
A. Migration Velocity
1. Once a particle is charged the particle will migrate
toward the collection electrode.
2. An indicator of how the particle migrates is call the
migration velocity to.
3. The migration velocity parameter represents the collect-
ability of the particle within the confines of a specific
collector.
B. Migration velocity value
1. The migration velocity is comprised of
w
d E E
pop
4lT|J
166
NOTE: This is for
theoretical
interest. No
emphasis is
necessary.
413-7-18
413-7-19
-------
CONTENT OUTLINE
Course: 413 - Lesson 7
Lecture Title: ESP _ PRINCIPLES AND OPERATION
** \
m*
Page.
.of-lL
NOTES
where d - the diameter of the particle, microns
E = strength of field in which particles are
0 charged, stat-volts per cm. (represented by
peak voltage)
E = strength of field in which particles are
collected, stat-volts per cm. (normally the
field close to the collecting plate/s)
V = viscosity of gas, poises
C. Migration velocity is quite sensitive to the voltage since
the electric field appears twice in the previous equation.
Therefore one must design the precipitator using the maximum
voltage fields with proper corona current flow for a maximum
collection efficiency.
VI. Particle Removal From Collection Plates
A. Forces acting on the particle at the collection plate
1. Particles that are good conductors
a. Lose negative charge to collection electrode
b. Begin to gain positive charge and be repelled
from the collection electrode
2. Particles that are poor conductors
a. Lose negative charge slowly
b. Negative gas ion rain on dust layer keeps particle
negative and attracted to electrode
3. Short range intermolecular forces between adjacent
particles and the electrode
a. Hold particles to the electrode
b. Cause deposited dust to form aggregates
4. Gas velocity gradient tends to lift dust from the electrodi
5. Electric wind produced by gas ions can re-entrain dust
6. Too frequent or intense rapping causes dust to fall as
small aggregates
a. If done right large aggregates would fall into hopper
b. Smaller aggregates can be re-entrained
B. Effects of accumulated dust layer on ESP efficiency
1. If the dust accumulates to an excessive thickness gas
velocity in the decreased passage will increase
2. Dust on both electrodes reduces corona discharge current.
167
-------
CONTENT OUTLINE
Course: 413 - Lesson 7
Lecture Title: ESP - PRINCIPLES AND OPERATION
Page.
of-lL
NOTES
«*"*
Increasing voltage to restore current can create back
corona.
3. Dust layer acts as a resistor in series decreasing field
strength
4. Dust layers can have high field strength. If high
resistivity dust is present back corona results
5. Dust on the discharge electrode quenches the corona
Collection Electrode Cleaning Methods
1. Several types
a. Electrode rapping
b. Water film
2. Electrode rapping
a. This is the most common system
b. Electrodes are joined by a rapping bar
(1) Bar is struck by a weight or vibrated
(2) Dust falls from electrodes into hopper
c. It is important to rap the electrodes so that the
dust layer falls off as large aggregates
(1) Otherwise dust can be re-entrained
(2) Rapping should be gentle and infrequent but
thorough (50g); usually more frequent on the
first section to handle higher particulate
build-up.
d. Dust aggregates will be larger and are composed of
fine particles
(1) Fine particles form aggregates better
(2) Large particles have greater tendency to
re-entrain but are easier to recapture.
e. Optimum rapping cycle cannot be well predicted
during ESP design
(1) Rapping cycle determined by empirical data
(2) While machine operates
(3) Rappers must be adjustable
(4) Typical times 5 min. rapping/60 min.
f. Common practice to sectionalize rapping
(1) Sections rapped independently
(2) Prevents puffing
168
413-7-20
-------
CONTENT OUTLINE
Course: 413 - Lesson 7
Lecture Title: ESP _ PRINCIPLES AND OPERATION
Png* 8 nf 11
NOTES
g. Rapper types
(1) Impulse ,
(2) Hammer
(3) Vibrator - least desirable; can be self
destructive when hard-to-remove dust is present
3. Water wall cleaning
a. Usually for tube type precipitators
b. H^O distributed evenly over collecting surface
c. Resistivity and re-entrainment problems greatly reducec
D. Dust Hoppers
1. Dust dislocated from plates falls into hoppers
2. Hoppers should be frequently cleaned to prevent dust
build-up
3. Baffles are effective in preventing gas sneakage
4. Hoppers should be insulated to prevent caking if dry
ash removal is used
5. Hoppers should have steep side walls to prevent
accumulation and plugging
VII.Collection Efficiency
1. The equation for collection efficiency holds the following
assumptions
a. Particle charge time is negligible - we have seen it
is small
b. Migration velocity is constant for all particles and
large compared to bulk flow velocity near plate
c. Particle concentration is uniform in any ESP cross section
d. Uniform gas flow velocity except at boundary regions
near collection plate
e. No disturbances (i.e. re-entrainment, back corona, etc.)
2. In the boundary layer near the collection electrode gas
flow is laminar
a. Friction between gas and wall
b. Particle velocity toward wall is resultant of
vector sum of gas velocity and electric force
c. 6 = w(At) boundary layer thickness
3. The equation for efficiency is derived from the particle
169
413-7-21
413-7-22
-------
CONTENT OUTLINE
Course: 413 - Lesson 7
Lecture Title: ESP - PRINCIPLES AND OPERATION
Page.
NOTES
migration velocity in the boundary layer and the distance it
moves in the precipitator
a. This is simply the probability the particle is in the
boundary capture layer
b. Diagram of concept
(Sbounda
layer
gas flow.
Discharge
electrode
Slide of Derivatioi
for added student
interest (optional]
Use board for rest
of Derivation.
This derivation
may not be necessai
413-7-23
wafer
sections = —
£1
c. The gas will move through the ESP
AZ = v( At)
d. The thickness of the layer then is
6 = w(At) - w -y-
e. The probability is then (S = perimeter of tube)
S6 Sw AZ SwL
V A v
c c
A vn
c
1 -
SwL
A vn
c
f. For the entire precipitator
g. As n approaches °°
f~ \n
llm
n-H»
SL
- w
e A v
c
h. A V = Q and SL = collection area so
_ e
170
-------
CONTENT OUTLINE
Course: 413 - Lesson 7
Lecture Title: ESP _ PRINCIPLES AND OPERATION
10
NOTES
4. Deutsch-Anderson Equation
a. This equation describes the factors involved in the
collection efficiency of the precipitator:
n = l - e (Q)W
where n = collection efficiency
A = effective collecting electrode
Q = gas flow rate through the precipitator
w = migration velocity
b. This shows that precipitator size is
1. Inversely proportional to particle migration velocity
2. Directly proportional to gas-handling capacity but
independent of gas velocity (this is not true because
velocity effects re-entrainment)
c. While this equation is scientifically valid, there are a
number of instances that can cause the exponent to be in
error as much as a factor of two or more. Care must be
taken when using this equation.
5. There are more sophisticated methods for calculating
efficiency but this is good for estimation. Effects not
included:
a. Concentration distribution
b. Particle size distribution
(1) All considered one size
(2) Uniform size throughout machine
c. Variation in electrostatic force
d. Reynold Number effect on particle drag
e. Slip correction factor
f. Gas velocity variation
VIII. Power Requirements
1. Theoretical power can be calculated by
a. Work = Force x Distance
The work to move the particle by electrostatic
force to the collection electrode
b. Work = F,,(s) s = distance
Ci
171
413-7-24
Slide of efficiency
equation must be
shown, do it at enc
of series.
413-7-25
413-7-26
-------
CONTENT OUTLINE
Course: 413 - Lesson 7
Lecture Title: ESP _ PRINCIPLES AND OPERATION
Page -1I_ 0/_LL
NOTES
c. The particle Is at terminal velocity so
FE - FD and FD - 6 irprw
d. Therefore: work - 6 iryrw(s)/per particle
e. This may be rearranged to show
Power - VI - 6 iryr(w)(s)
f. The key then is the particle migration velocity
6 iryr .'. VI = qE (s)
g. These items illustrate the relationships between
(1) particle size
(2) particle migration velocity
(3) ESP power requirements
IX. The features of the ESP which make it particularly attractive are:
1. They can be designed for high collection
efficiency for particles of all sizes
2. They are economical to operate since they have
relatively low internal power requirements and
inherently low draft losses (pressure drop)
3. They can treat large gas volumes
4. They are very flexible in gas operating
temperature used — 200°F - 800°F
5. They have a long useful life
413-7-27
413-7-28
413-7-29
413-7-30
413-7-31
413-7-32
413-7-33
413-7-34
413-7-35
413-7-36
413-7-37
172
-------
FltCTKOSlAllf PSIUPItAKHt
3 TYPES OF ISP
UCnOfTAIX FKKintAfO*
ti-W
COMPONENT!
OF STANDARD
TWO-STAGE
PHtClPTIATO*
AVAIAM HI Wl TIPIK AIK>N
AVA1ANCHL MUTVUCATION
AV JUANCm MlxrUK AWT
MIGRATION
VELOCITY
COLLECTION FFFICIENCY
I.' " vokunvlric Kow
SUBSTITUTING:
rARTKJf MK.RATION VIIOOTY
-tec.rift.
-------
174
-------
LESSON PLAN
TOPIC': ESP: DESIGN AND APPLICATIONS
COURSE: 413 - Lesson 8
LESSON TIME; 1 hour
PREPARED BY: G. j.
Revised by David S. Beachler 12/1/79
LESSON GOAL:
This lesson is an extension of the ESP Theory lecture.
It will point out problems affecting the ESP, controls
for the machine, and uses of the unit.
LESSON OBJECTIVES:
The student should be able to:
* Describe factors affecting the operation of an
electrostatic precipitator.
• Particle resistivity
• Gas stream parameters
• Gas flow distribution
* Discuss common operating problems of ESP's.
* Describe controls used for the ESP.
* List recommended maintenance and operating
procedures for assuring optimum ESP performance.
REFERENCES:
Theodore, L. and Buonicore, A. J., Industrial Air
Pollution Control Equipment for Particulates, CDC Press,
Cleveland, Ohio, 1976, pp. 174 - 178
175
-------
AUDIO-VISUAL MATERIALS FOR LESSON 8
Lesson 8 Electrostatic Precipitator Design and Applications
A13-8-1 Electrostatic precipitator
413-8-2 Resistivity - definition
413-8-3 Normal resistivity
413-8-4 Low resistivity
413-8-5 High resistivity
413-8-6 Conditioning high resistivity
413-8-7 Effects of temperature and moisture on resistivity
413-8-8 Low sulfur coal - generally has high resistivity
413-8-9 Typical flow distribution
413-8-10 Live shot of flow distributors
413-8-11 Stage or field construction
413-8-12 Parallel sections
413-8-13 ESP - shell
413-8-14 Live shot - ESP shell
413-8-15 Electrodes
413-8-16 Typical collection plates
413-8-17 Discharge electrodes
413-8-18 Live shot - discharge wires and collection plates
413-8-19 Rappers
413-8-20 Live shot - rappers
413-8-21 Live shot - rappers
413-8-22 High voltage equipment
413-8-23 Live shot - high voltage equipment
413-8-24 Live shot - ESP metering .equipment
413-8-25 Broken wires
413-8-26 Primary emters
413-8-27 Secondary meters
413-8-28 Live shot of insulator
413-8-29 Live shot of rapper and protective bad weather caps •
413-8-30 Live shot of protective bad weather caps; not in proper position
413-8-31 Hoppers
413-8-32 Review
176
-------
CONTENT OUTLINE
Course: 413 - Lesson 8
Lecture Title: ESP: DESIGN AND APPLICATIONS
Page.
of-lL
NOTES
The preceeding lecture has covered the basic theory of electro-
static precipitation of particles suspended in a gas stream. This
lecture is directed at pointing out various particle and gas stream
characteristics that effect the operation of the ESP. Knowledge of
ESP theory will make this discussion of operating problems easier
and more meaningful.
I. Particle Resistivity
A. Definitions
1. Resistance - property of a circuit or substance opposing
the flow of current and causing heat when current flows.
Unit is Ohm. 1 amp flowing through 1 ohm resistance causes
1 watt (107 erg/sec) of heat.
2. Particle resistivity is the term used to describe the
ability of particles to take on a charge.
3. Measuring resistivity of a dust sample
a. Apparatus is a plate with a needle discharge
electrode suspended above it
b. Collected dust is suspended in a gas stream then
passed thru the plate and needle apparatus
c. The needle produces a strong corona, precipitating
the dust
d. When • ^ 20 KV/cm
j. Resistivity is calculated from the equation
B. Particle resistivity can vary between 10"^ to 10 ohm-cm
177
413-8-1
(413-7-2)
Note: Review of
the previous
lecture would be
helpful -
discussion of
discharge wires,
electrodes,
rappers, etc.
413-8-2
Note: This topic
can be touched
upon lightly.
413-8-3
-------
CONTENT OUTLINE
Course: 413 - Lesson 8
Lecture Title: ESp. DESIGN AND APPLICATIONS
Page.
NOTES
c.
1. Dust below 10 ohm-cm is difficult to retain on collecting
electrode - Low Resistivity
a. This dust is readily charged and migrates to the
collection electrode
b. Rapidly loses negative charge then acquires heavy
positive charge
c. Particle can spring back into gas stream if positive
charge gets high enough
Dust above 10 ohm-cm - High Resitivity
a. Collected dust is subjected to a rain of negative ions
and particles
b. Accumulated charge must be dissipated by current flow
413-8-4
2.
413-8-5
through the dust layer
Voltage drop = PB x D1
A
20 KV
f .
g.
h.
This is the area in which electrical breakdown of the
dust occurs
Observed as glowing spots on plate. Sharp points at
which intense spark-over takes place
Break down produces electron-positive ion pairs
Positive ions toward corona; negative electrons toward
plate
Results
(1) Decreases charge on particles migrating toward
collection electrode
Particle re-entrainment (of collected dust)
Total current Increase; voltage decreases and so
does field strength
Conditioning - to lower resistivity
1. Resistivity- problems can be reduced by
a. Lowering current density - not enough charge to
particles so this is poor choice
b. Lowering resistivity
2. Lowering resistivity is accomplished
a. Spraying dust with H-O or steam
(1) Adheres to dust surfaces
(2) Electrolytic film allows surface conduction
178
I = 2 x 10"8 a/cm2
PB = 1012 ohm-cm
L - 1 cm
(2)
(3)
413-8-6
-------
CONTENT OUTLINE
Course: 413 - Lesson 8
Lecture Title: ESP: DESIGN AND APPLICATIONS
Page.
of-LL
NOTES
b.
Dust that do not absorb H?0 can be conditioned
S03 for basic dusts """)
for acidic dusts _)
as little as 20 ppm
works
(1)
(2) NH
3. Prevent air in leakage - lowers temp and humidity
4. H_0 effects electrical discharge
a. Each % H»0 increases spark voltage 5%
b.
Reduces corona current 7% for each % H_0
5. Particles that readily conduct charge could be added to
the gas stream but this is usually not practical
D. Temperature Effects on Resistivity
10J
io12H
Resistivity
ohm-cm
10UJ
101"-
io9-
io8-
413-8-7
0 100 200 300 400 500 600 700°F
1. Temperature increases but R~Q is evaporated
2. At maximum surface conduction is important compared to
volume conduction.
II. Gas Stream Parameters
A. Temperature
1. Gas temperature affects particle resistivity
2. Gas temperature decrease generally lowers ash (particle)
resistivity
3. Some problems could arise, however
a. plume bouyancy resulting from decrease
b. possible corrosion
B. SO. Content of the Gas
1. In general, low sulfur coal will have high resistivity.
179
413-8-8
-------
CONTENT OUTLINE
Course: 413 - Lesson 8
Lecture Title: ESP: DESIGN AND APPLICATIONS
Page.
of-LL
NOTES
2. The controlled addition of sulfur trioxide (SO™) has been
reported to improve the performance of ESP's used for
collection of fly ash from western coals (less than 1
percent sulfur content).
3. Careful control of the sulfur trioxide addition rate is
required to avoid releasing of the gas.
III. Gas Flow Distribution
A. An ESP is essentially a large box
1. Gas flows through it
2. The gas should flow slowly and evenly
Low pressure drop ducts
1. Keep total length to a minimum
2. As few bends as possible
3. Bends should have straightening vanes
B.
413-8-9
2.
3.
C. Gas Distribution in the ESP (gas velocity 2-8 ft/sec)
1. For the exponential efficiency equation for the ESP it
can be shown that the gas must be equally distributed to
passages for max. efficiency.
Good distribution of entering gas is tough to obtain
Ideally gas distribution would be
a. Plug - flow — perfectly flat velocity profile
Factors preventing this
(1) process distortions of the flow
(2) duct effects - bends, friction
duct velocity much higher than ESP so need
expansion section
expansion section will need diffuser-perforated
plate
180
413-8-10
b.
(3)
(4)
-------
CONTENT OUTLINE
Course: 413 - Lesson 8
Lecture Title: ESP: DESIGN AND APPLICATIONS
Page _J_ of_LL
NOTES
IV. Electrical Sectionalization
A. Maximum field voltage depends on
1. Gas and particle properties 413-8-11
2. These can vary from point to point within the ESP
3. To maintain ESP at optimum efficiency the unit should
be divided into stages
4. Each section has separate power supply and controls
B. Controls
1. Higher voltage produces high spark rate between electrodes
2. Optimum spark rate/section 50-150/min.
a. Corona power at best possible setting
b. Gains in particle charging are just offset by corona
current losses from spark-over
3. Above this spark rate
a. Input power is wasted in sparking
b. Less power applied to the dust
4. The spark rate is maintained at optimum setting by
momentarily lowering corona power when excessive
sparking occurs
C. Need for Stage or Fields (in series)
1. Power needs differ at different ESP locations
2. Inlet field or stage dust concentration is heavy
a. Heavy dust suppresses corona current
b. Requires great deal of power here to generate
adequate corona discharge
3. Downstream dust concentration is lower
a. Corona current flows more freely
b. If same power applied for it as at inlet excessive
sparking will limit particle charging
c. One>power supply would probably limit spark rate in
downstream stages reducing inlet section efficiency
d. Individual controls and power supplies work much bettejr
e. Also if a given state or field is out other fields
are not as severely effected
D. Parallel sectionalization - chamber 413-8-12
1. Copes with different power needs at inlet to ESP created by
a. Poor gas distribution
181
413-8-11
(keep up same slide)
-------
CONTENT OUTLINE
Course: 413 - Lesson 8
Lecture Title: ESP.- DESIGN AND APPLICATIONS
Page.
NOTES
b. Uneven dusfdistribution
2. Adds only small increase in efficiency
3. Allows on-line maintenance of shorted sections
V. ESP Construction - Typical Design Parameters
A.
Typical Design Parameters for Electrostatic
Precipitators
Parameter
Precipitation rate
(effective migration
velocity)
Plate spacing
Gas velocity
Plate height
Plate length
Applied voltage
Corona strength
Field strength
Residence (treatment)
time
Draft loss (pressure
drop)
Efficiencies
Gas temperature
B.
Range of values
0.1 - 0.7 ft/sec
8-11 in.
2-8 ft/sec
12 - 45 ft
0.5 - 2.0 times height
30 - 75 kV
0.01 - 1.0 mA/ft of wire
7-15 kV/in.
2-10 sec
0.1 - 0.5 in. water
to 99.9+%
to 700°F (standard)
1,000°F (high temperature)
1,300°F (special)
Power =
l/2(V
I = corone current
c
V = Peak voltage
V = Minimum
m ,
voltage
(This calculation is for theoretical interest.)
simplified electric field = 2 ^ R
o
i = current/lenght
K = ion mobility
K = dielectric constant of a vacuum
o
Shell structure 413-8-13
1. Encloses the electrodes and supports them in a rigid frame 413-8-14
2. Structure and foundation should be conservatively designed
a. Especially critical for hot ESP's
b. Must be able to withstand thermal and structural stresjs
c. Plant in Wilmington, NC is rebuilding one that took
this for granted
182
-------
CONTENT OUTLINE
Course: 413 - Lesson 8
Lecture Title: ESP: DESIGN AND APPLICATIONS
NOTES
3. Convectional practice supports plates from top
4. Shell must be thoroughly insulated including hopper
a. Conserve heat
b. Prevent condensation - and subsequent possible
corrosion
5. Easy access to the machine internals for repair and
inspection
6. Connecting ducts must be insulated
C. Electrodes
1. Ducts range between 8-12 inches wide
a. 20-30 ft high use % 9 in. spacing
b. 35-45 ft high use £ 10-12 in. spacing
2. Aspect ratio - ratio of plate length to height
a. Particle rapped from plate may take several seconds
to fall into hopper
b. Do not want it to be carried out of precipitation
area before it can fall into the hopper
c. Design aspect ratio for 99% + efficiency
between 1 and 1.5
3. Collection electrodes - collection plates
a. Solid sheet metal plates
b. Some have baffles to improve gas flow
c. Must be rigid enough to maintain electrode spacing
tolerances + 5%
d. Distorted or misaligned electrodes cause
reduced operating voltage and efficiency
4. Discharge electrodes (many types of design)
a. Traditionally round wire (0.1 in diameter)
b. The size (usually .1 - .15 in diameter) and shape of
the discharge wires are governed by the corona and
mechanical requirements of the system. Discharge
wires can have many configurations, twisted, barbed,
ribbon and other types are commonly used.
c. Wires are held taught at the bottom by weight as to
maintain consistent critical distance between wires
and plates. (4 - 11 in spacing)
d. Should have shroud on bottom and top part of wire to
413-8-15
413-8-16
413-8-17
413-8-18
Note: This live
shot shows both
discharge and
collection
electrodes.
protect it
183
-------
CONTENT OUTLINE
Course: 413 - Lesson 8
Lecture Title: ESP: DESIGN AND APPLICATIONS
NOTES
D. Rappers
1. Rapping can be done electromagnetically, pneumatically
or mechanically.
2. Rapping causes the dust to slough away from the
electrode surfaces and fall into the collection
hoppers. Rapping is done while the unit is on-line.
3. Rappers can be spaced every 5 feet along the plates.
4. Rapping must be done to the collection plates but also
to the discharge wires (gently rapping) to prevent dust
build up on the wires.
5. Dust will sometime accumulate on the discharge wires.
Occasionally the dust must be removed, usually by gentle
vibration of the electrodes.
E. High Voltage Equipment
1. Must be able to provide intense electrical fields
and corona currents
a. Must be reliable and stable
b. Proper wave form (voltage waveform)
c. Today this means silicon rectifiers
2. Metering should include
a. Primary meters for
(1) Total ESP volts
(2) Total ESP milliamperes
b. Secondary meters'for each bus section
(1) Voltmeter
(2) Milliammeter
(3) Spark rate meter
VI. Trouble shooting ESP operation - operation and maintenance
A. Discharge wire breakage
1. Causes
a. Kinks or knicks in wire
b. Spit arcs at ends (prevented by shrouds)
c. Fatigue - swinging
d. Localized arcing
e. Corrosion
2. Indications of broken wires
a. Full load current with reduced primary voltage
184
413-8-19
413-8-20
413-8-21
413-8-22
413-8-23
413-8-24
413-8-25
-------
CONTENT OUTLINE
Course: 413 - Lesson 8
Lecture Title: ESP: DESIGN AND APPLICATIONS
Page.
ofJd.
NOTES
b. Rhythmic and repetitive arcing bursts
B. Ash resistivity problems are Indicated
1. Sparking at low current densities
2. Low voltage, high current, steep corona characteristic
could mean back corona formation
C. Reading high voltage Instrumentation
1. Primary Voltmeter
a. No voltage — open primary circuit
b. High voltage — faulty rectifier; open
transformer; poor connection to ESP; open
bus section
c. Low voltage — insulator leak; high dust level
in hoppers; poorly cleaned electrodes; swinging wires
2. Primary Ammeter
a. No current, high voltage — open primary circuit
b. Very low current, high voltage — open transformer
primary
c. Irregular current, low voltage — short
d. Broken wire shows low voltage, cycling current
3. Secondary Voltmeter — Located between rectifier
and discharge wire
a. No voltage — could be open primary circuit
b. High voltage — open precipitator bus section;
faulty rectifier
c. Low voltage — same as Primary
4. Secondary Ammeter
a. No current, no voltage — open circuit primary
b. Low current, high voltage — open transformer
primary or open secondary circuit
c. Irregular current, low secondary voltage —
excessive dust arcing etc. Broken wire in the
swinging field shows cycling current
5. Spark meter — above 100/min shows excessive power loss
D. Insulator Problems
1. Cracked or dust covered insulators cause problems
with proper electrical operation
2. Can be prevented by careful operation of ESP
185
413-8-26
413-8-27
413-8-28
-------
CONTENT OUTLINE
Course: 413 - Lesson 8
Lecture Title: ESP: DESIGN AND APPLICATIONS
Page J°_ of'JLL
NOTES
a. Keep insulators above dew point of gas
b. Do not subject them to intense rapping
c. Pressurize compartment with warm air
d. Inspect regularly
E. Protective Covers
1. Rubber covers protect the rappers from adverse
weather conditions, (see slide)
2. Covers should be tightened in correct position to
avoid water leakage and shorting-out problems.
F. Hoppers
1. Adequate hopper capacity must be provided to receive
the dust after rapping and to contain it far enough
below the baffles to preclude reentrainment.
2. Screw conveyors are normally used for emptying;
adjustments might be necessary for design for sticky
dusts.
3. Access doors and striker plates are useful for
maintenance needs.
VII. Applications
A. Use of electrostatic precipitators have been applied to many
industries over the year.
1. Can achieve 99.9+% collection efficiency
2. Can handle exhaust gas up to 1100 F.
3. Very efficient for even submicron data.
B. Selected Various Processes
a. Use in coal fired utilities and industrial boilers.
Size range according to selected industrial application.
b. Usual efficiency 98 - 99.9+
c. Gas temperature 275 - 600 (usually 300 - 350)
2. Steel Industry
a. Blast furnace gas
b. Coke oven gas (tars)
c. Basic oxygen furnaces
d. Sinter plants
e. Collect submicron particles for above industries
f. Usual efficiencies vary from 95 - 99+%
186
413-8-29
413-8-30
413-8-31
-------
CONTENT OUTLINE
Course: 413 - Lesson 8
Lecture Title: Esp: DESIGN AND APPLICATIONS
NOTES
3. Cement
a. Used frequently on cement kilns, both wet and dry
processes.
b. Can collect sub micron particles up to 99+ efficiency
c. Also used for dryers
4. Pulp and Paper Industry
a. Used on black liquor recovery furnace
b. 99% efficiency for sub micron particles
VII. Review
The past hour we've talked about the following subjects.
* Resistivity
* Flow distribution
* Sectionalization
- Parallel
- Fields or Stages
* Design Features
- Shell
- Collection Electrodes
- Discharge Electrodes
- Rappers
- High Voltage Equipment
413-8-32
187
-------
18G
-------
189
-------
LESSON PLAN
I TOPIC: PROBLEM SESSION V -
I ELECTROSTATIC PRECIPITATOR
COURSE: 413 - Lesson 8a
LESSON TIME: i hour
PREPARED BY:
G.J. Aldina
DATE:
7/79
LESSON GOAL:
SUPPORT MATERIAL
AND EQUIPMENT
Briefly describe the use of electrostatic precipitator
formulas such as migration velocity and collection
efficiency by solving four problems.
1. Chalkboard
2. 413 Student Workbook pp 17-20.
190
-------
CONTENT OUTLINE
Course:413 - Lesson 8a
Lecture Title • PROBLEM SESSION v -
ELECTROSTATIC PRECIPITATOR-
I. Problem 5-1
A. Work our problem 5-1 for the students. The solution is:
Of.
NOTES
NOTE: See problem
5-1 on page 17 in
the 413 Student
Workbook
5.1 ESP Problem
An electrostatic precipitator consists of two parallel 10 ft
high by 16 ft wide plates with corona wires positioned half way
between the plates. Find the effective migration velocity at a
flow rate of 35 acfs if the required collection efficiency is 0.95.
SOLUTION:
*
ESP has 2 plates 10 ft high and 16 ft wide. What is migration velocity if flow
rate is 35 acfs and efficiency is 0.95.?
w
^ - to (1 - n)
- ? (1 -1) - -
35ft/sec
(ioft)(16ft)(2)
An (1-0.95)
w = 0.328 ft/sec
191
-------
CONTENT OUTLINE
Course: 413 - Lesson 8a
Lecture Title: PROBLEM SESSION v -
ELECTROSTATIC PRECIPITATOR-
II. Problem 5-2
A. Work out problem 5-2 for the students.
Problem 5-2 Is:
The solution for
Page J of-
NOTES
NOTE: See problem
5-2 on page 18 of
the 413 Student
Workbook
5.2 ESP Problem*
A horlzontal-flow-single-Btage electrostatic precipltator is used to
remove participates from a dry process gas stream of a Portland cement
manufacturing plant. The precipltator consists of multiple ducts formed
by collecting plates 14 ft wide by 16 ft high and placed 9 inches apart.
The rate of flow through each duct is estimated to be 2400 acfm and the
content of dust is 5 grains/ft3.
a. Calculate the collection efficiency.
b. Calculate the amount of dust collected by a duct each day.
•Assume w- 0.19 ft/sec
SOLUTION:
(a) n - 1 -
-(A/Q)w
A - 2(14)(16) - 448 ft*
Q - 2400ACFM - 40 ft3/sec
60 sec/in
= 0.881
(b) #/day - 0.88(5 gr/ft3) x (2400 ft3/min) x (60 min/hr) 24 hr/day
7000 gr/#
- 2175 ///day
192
-------
CONTENT OUTLINE
Course: 413 - Lesson 8a
Lecture Title' PROBLEM SESSION v -
— ELECTROSTATIC PRECIPITATOR.
III. Problem 5-3
A. Allow students 20 minutes to work on problem 5-3
B. Go over the solution of problem 5-3. The solution is:
Page
of-L
NOTES
NOTE:
See problem 5-3 on
page 19 of the
413 Student Workboo
5.3 ESP Problem
An electrostatic precipitator has three ducts with plates 12 ft wide
and 12 ft high. The plates are 8 inches apart.
a. Assuming a uniform distribution of particles and a
drift velocity of 0.4 ft/sec, calculate the collection
efficiency at a rate of flow of 4,000 acfm at 20°C and
: 1 atm.
b. Calculate the efficiency if one duct were fed 50% of
the gas and the others 25% each.
SOLUTION:
(a) A - 2(12)2 - 288 ft2/duct
Q -
i - 22.2 ft3/sec for each duct
j
- ;W.4> (288/22.2) _ ^ _ ^ x lfl-
(b) A = 288ft2/duct
Q = 4000 x 1 = 33.33 ft3/sec
60 2
(.4)(288/33.33)
n - 1 - e
25% Duct
1 -
(3.1 x 10~2)
.9684
A - 288 ft2/duct
60 4 *v" "
n . 1 - .-(.4X288/16.7) . i _ (1>fll x 10-3j . <9989
Overall Efficiency
n = 0.5 (.9684) + 2(.25 x .9989) x 100 - 98.37%
193
-------
CONTENT OUTLINE
Course:M3 . Lesson 8a
Lecture Title: PROBLEM SESSION v -
ELECTROSTATIC PRECIPITATOR-
IV. Problem 5-4
A. Have students do problem 5-4 for homework.
B. Go over the solution for Problem 5-4. The solution is:
5.4 A precipitator consists of two stages, eacH witfi five
plates in • aeries (••• figure below). The coronjt vires between
any two plates are independently controlled ao that the remainder
of the unit can be operated in the event of a wire failure.
The following operating conditions exist:
NOTES
NOTE: See problem
5-4 on page 20 of
the 413 Student
Workbook
Gas Flow Rate
Plate Dimensions
Drift Velocity
10,000 acfm
10 ft x 15 ft
19.0 ft/min Section 1
16.3 ft/min Section 2
Top Vitw
Dirty
Gas
STAGE I
STAGE 2
a. Determine the normal operating efficiency.
b. During operation, a wire breaks to Stage 1. As a
result, all of the wires in that row are shorted and ineffective,
but the others function normally. Calculate the collection ef-
ficiency under these conditions.
e. Similarly, a wire breaks in Stage 2 after Stage 1
is repaired. What is the overall collection efficiency of the
unit under these conditions?
194
-------
or
5.4
SOLUTION:
(a) A - 10 x 15 x 8 = 1200 ft2
Q = 10,000 ACFM
nl= 1-e- (1200/10,000X19)
- -(1200/10.000) (16.3)
\otal
= 1 - (1-0. 89772) (1 - 0.85858) = 0.98554
nTotal
1 -[l-(0.75)(.897722J [l - 0.85858] = 0.95380
(c) n = 1 - I - 0.89772J [l-(0.75)(0.85858)J = .96358
195
-------
LESSON PLAN
TOPIC: FABRIC FILTER PRINCIPLES
COURSE: 413 - Lesson 9
LESSON TIME' 1 1/2 hours
PREPARED BY: DATE:
David S. Beachler
4/79
I
5
\
.sszy
^^^v. *^^
^Q / *<*^"^^
i/ Cinj^i\^^
LESSON GOAL:
Briefly describe the principles involved in the collection
of particulates by fabric filtration and describe
the main aspects of a baghouse such as filtering,
cleaning of the bags, filter materials, pressure drop
and collection efficiency.
LECTURE OBJECTIVE:
At the end of the lesson the student should be able to:
* List three collection mechanisms used in fabric
filtration.
* Briefly describe the three general designs for baghouses.
* List four cleaning mechanisms and briefly describe
their operation.
* Name two types of fabric filter material con-
struction and the use of different fiber types to
guard against failure of fabric materials.
* Define pressure drop and recall the simplified
formulas for determination of Ap across the cake and
across the fabric.
* Describe the sieving action and the formation of
the cake, and the role played in terms of collection
efficiency.
* Define filtration velocity and air to cloth ratio
and the role they play in terms of fabric filtration
performance.
STUDENT PREREQUISITE
SKILLS:
Ability to understand basic principles of physical
science and perform calculations with logarithms and
exponential functions
IQfi
-------
LEVEL OF INSTRUCTION:
Advanced
INTENDED STUDENT
PROFESSIONAL BACKGROUND:
Engineering or Physical Science
SUPPORT MATERIALS
AND EQUIPMENT:
1. slide projector
2. overhead projector
3. chalkboard
4. 413 Student Manual
REFERENCES:
1. 413 Student Manual
2. "Air Pollution Control Technology, An
Engineering Analysis Point of View", by
Robert M. Bethea, Van Nostrand Reinhold
Company, New York, 1978.
3. "Particulates and Fine Dust Removal", by
Marshall Sittig, Noyes Data Corporation,
Park Ridge, New Jersey, 1977.
4. "Procedures Manual for Fabric Filter
Evaluation," EPA 600/7-78-113, IERL Research
Triangle Park, N. C., June 1978.
5. "Proceedings The User and Fabric Filtration
Equipment Specialty Conference", the
Niagara Frontier Section, Air Pollution Control
Association, Pittsburgh, PA, October 1973.
6. "Proceedings The User and Fabric Filtration II
Equipment Speciality Conference", the Niagara
Frontier Section, Air Pollution Control
Association, Pittsburgh, PA, October 1975.
7- "Proceedings The User and Fabric Filtration III
Equipment Speciality Conference", The Niagara
Frontier Section, Air Pollution Control
Association, Pittsburg, PA, October 1978.
8. "Industrial Air Pollution Control Equipment for
Particulates", by L. Theodore and A. J. Bounicore,
CRC Press, Inc., Cleveland, OH, 1976.
197
-------
9. "Handbook of Fabric Filter Technology. Vol. I.
Fabric Filter Systems Study", Charles E. Billings,
et. al., distributed by NTIS, PA-200-648,
December, 1970.
10. "Appendices to Handbook of Fabric Filter
Technology, Vol. II. Fabric Filter Systems
Study", GCA Corporation, Bedford, Massachusetts,
distributed by NTIS. PA-200-649, December 1970.
11. "Fabric Filter Cleaning Studies", EPA Technology
Series, EPA 650/2-75-009, January 1975.
198
-------
AUDIO-VISUAL MATERIALS FOR LESSON 9
Lesson 9 Fabric Filter Principles
413-9-1 Baghouse—live shot
413-9-2 Baghouse—live shot
413-9-3 Collection mechanisms
413-9-4 Impaction
413-9-5 Interception
413-9-6 Diffusion
413-9-7 Gravitation
413-9-8 Electrostatic attraction
413-9-9 Filter designs
413-9-10 Interior filtration
413-9-11 Exterior filtration
413-9-12 Bags—hanging in baghouse
413-9-13 Support cages for bags
413-9-14 Single units—interior shot of a pulse jet baghouse
413-9-15 Compartmental baghouse units
413-9-16 Hoppers and cleanout pipes
413-9-17 Cleaning sequences
413-9-18 Types of cleaning mechanisms
413-9-19 Shaking for cleaning bags
413-9-20 Reverse air cleaning
413-9-21 Reverse jet—blow ring
413-9-22 Pressure jet or pulse jet cleaning
413-9-23 Pressure jet with use of venturi for cleaning bags
413-9-24 Woven fabric filter material
413-9-25 Felted fabric filter material
413-9-26 Types of fibers
413-9-27 Causes for bag failure
413-9-28 Pressure drop expression—across the fabric
413-9-29 Pressure loss due to the cake
413-9-30 Total pressure drop (across the filter and the cake)
413-9-31 Filter drag expression
413-9-32 Filter seiving mechanism
413-9-33 Filter cake—cake buildup
413-9-34 Performance curve—filter resistance versus the buildup of the cake
199
-------
413-9-35 Overall pressure drop for a multi-component baghouse
413-9-36 Filtration velocity—air to cloth ratio
413-9-37 Air to cloth ratio—the delicate balance that affects the
performance of the baghouse
413-9-38 Factors affecting baghouse performance
413-9-39 Gas conditioning—cooling
413-9-40 Review—collection mechanisms
413-9-41 Review—filtering designs
413-9-42 Review—collection mechanisms
413-9-43 Review
200
-------
CONTENT OUTLINE
Course: 413 - Lesson 9
Lecture Title: FABRIC FILTER PRINCIPLES
NOTES
I. Introduction
A. References — pass out listing of references
B. Description — baghouses are like huge vacuum cleaners
to collect particulates with a high efficiency
1. Baghouses also called fabric filter collectors,
bag filters, fabric dust collectors, filter
collectors, dust collectors, cloth collectors
and filter houses.
2. Types
a. disposable — deep bed, panel, and mat filter
are discarded rather than reused or cleaned.
i.e. furnace or AC filter
b. fabric filter — where dust bearing gases
are passed unidirectionally through a fabric
which consists of:
(1) filter medium and support
(2) cleaning device
(3) dust collection hopper
(4) isolation closure - or housing
(5) prime gas mover - fans
(6) necessary sensing devices and
operational controls
3. Two ways to operate the baghouse
a. Pushthrough - gases pushed through the
collector - by fan
. Pullthrough - gases pulled through the collector
- fan on back side of baghouse - most baghouses
designed this way can use backward curve blade
fans, which are more efficient and also lessen
the chance of particle damage to fan blades
-- and bearings.
c. Advantages and disadvantages of pushthrough and
pullthrough
II. Collection Mechanisms - way particles collected
A. Impaction - particles have too much inertia to follow
streamlines around filter fiber and thus impact on the
surface.
201
Slide: 413-9-1
NOTE:
point out
collection hopper
Slide: 413-9-2
NOTE: point out
housing
Slide: 413-9-3
Slide: 413-9-4
NOTE: usually
account for 99.<
particles > ly
-------
CONTENT OUTLINE
Course: 413 - Lesson 9
Lecture Title: FABRIC FILTER PRINCIPLES
Page-2. of.
NOTES
14
B. Interception - particles having very small inertia
(smaller particles) can barely follow streamlines around
obstruction. Particle is immersed in the viscous
stream, slows down and touches the barrier (filter fiber
or dust cake) and stops.
C. Diffusion - important for particles that are below 1 urn
in aerodynamic diameter. Particles in the range of .ly
in diameter are in the Brownian motion range —
particles are so small their individual motion can be
affected by collisons on a molecular or atomic level —
collection is a result of random motion causing inter"'
ception with fiber or dust cake.
D. Gravitational settling and agglomeration - some
particles - larger particles settle on initial entry.
E. Electrostatic attraction - particles having a (+) or (-)
charge attracted to cloth of the opposite charge -
' slight effect - sometimes referred to a triboelectric
effect.
F. Other effects - particle agglomeration can be promoted
by decrease in temp - shock cooling, i.e. shock cooling
by water sprays, fine particles agglomerate together -
must not let gas reach dew temp, and must keep relative
humidity < than 90%.
III. Filtration Process
A. Systems
1. Bottom feed - gases enter the bottom, directed
into bags, filtered and exit through bags - clean
air on outside of bag
2. Top Feed - dust laden gases enter through the
top of the baghouse filter tubes, filtered and
exit through bags - clean air on outside of bag
3. Exterior filtration - gases pass from the outside of
tubes (filter) to the inside or clean air side.
This type of arrangement requires inner bag support
202
Slide: 413-9-5
Slide: 413-9-6
Slide: 413-9-7
Slide: 413-9-8
Slide: 413-9-9
Slide: 413-9-10
Slide: 413-9-11
-------
CONTENT OUTLINE
Course: 413 _ Lesson 9
Lecture Title: FABRIC FILTER PRINCIPLES
Page.
NOTES
B.
1. Bags - generally tubular in shape, vary in length
and diameter 6" - 18" diameter up to 40 ft. long.
Ratio of bag length to diameter generally from
4:1 to 16:1
2. Bags - hung or attached - depends on type of
cleaning involved - but secured at either top or
bottom or both, usually hang vertically, i.e.
* shaker hold at top and sheath at bottom
* some supported by inner cage
C. Housing
1. Single units - all gases into single housed unit.
2. Compartmental units - consist of more than one
compartment
D. Hoppers to collect dust
1. Manual clean out
2. Screw conveyer
3. Rotary valves
IV. Cleaning Mechanisms
A. Sequences
1. Intermittant - done on a demand basis - entire
compartment is passed by (gases) and bags cleaned
row by row, or simultaneously
(a) used for batch processes
(b) usually cleaned in low pressure mode such as
shaking, or reverse air.
(c) intermittant cleaned baghouse is shut down
in between process batches
2. Periodic - sections are compartmented and cleaned
alternating filtering - cleaning cycles, i.e. one
compartment cleaning while other two filtering.
(a) usually low pressure mode cleaning
203
Slide: 413-9-12
NOTE: mention bag
configurations
Slide: 413-9-13
Slide: 413-9-14
413-9-15
Slide: 413-9-16
Slide: 413-9-17
-------
CONTENT OUTLINE
Course: 413 - Lesson 9
Lecture Title: FABRIC FILTER PRINCIPLES
Page.
of.
14
NOTES
3. Continuous - fully automatic, high pressure cleaning
methods, bags cleaned with compressed air, 2.3 sec.,
filtering process interrupted momentarily. The blast
of air will oppose the flow of cleaned air through
the bag i.e. A/C ratio may be 16:1, velocity from
pulse jet may be 50 ft./min.
(a) bags supported by cages - dust cake is cracked
and popped off the bags
(b) higher dust loading permitted
(c) larger A/C ratio - always a row of bags being
cleaned somewhere in baghouse
(d) generally compartmentalized with (n + 1) extra
to guard against failures.
Types of cleaning mechanisms
1. Shaking - low energy process - (low filtering
velocity 1-5 ft/sec) shaking cleaners hold bag at
the top of the bag and shake the entire tube sheath
at the bottom. Shaking can be horizontal concave
upwards or downwards, vertical, 90° arc swing -
oscillating flexing motion - involves top of bag
moved back and forth creating in relatively flat
arc causing ripples in filter bag dislodging dust.
(a) greatest wear at top where support loop attaches
(b) not used for sticky dust - would have to shake
too hard
(c) can not use glass bags
Sonic cleaning - employs sound generator to produce
low frequency sound, causing bags to vibrate
gently, noise level barely discernable outside filter
compartment
(d) used with heavy denser carbonaceous dusts
2. Reverse air
Bag collapse - simply collapsing the bag by
reversing the air flow in the entire compartment —
backwash
(a) backwash can cause rapid deterioration due to
frequent flexing and creasing
204
Slide: 413-9-18
Slide: 413-9-19
Slide: 413-9-20
-------
CONTENT OUTLINE
Course: 413 _ LeSson 9
Lecture Title: FABRIC FILTER PRINCIPLES
Page
NOTES
(b) However, many manufacturers of reverse air
units are finding that bag life can be as
high as three to four years on this type
of filter in the coal fired boiler business
and the metallurgical industry. All other
things being equal bag life is generally a
function of good low air-to-cloth ratio.
(c) utilize filter velocities 1:1 to 6:1
3. Reverse jets - travelling blow rings involves
reversing air flow but not depend on bag collapsing
- series of rings,! for each bag travel up and
down bag blowing a stream of compressed air into
the bag from outside. Bags are normally cleaned
by rows.
(a) disadvantage of blow ring - mechanical
linkage and individual air hose attachments
required for each bag
(b) high maintenance involved .'. use is decreasing
(c) another disadvantage - blow rings use low
reverse air pressure .'. felted bags cannot be
cleaned adequately
(d) filtration velocities as high as 15 ft/sec
4. Pressure jet or pulse jet
(a) pulse jet - pressure jet
- high pressure air jet to create a low pressure
inside the bag and then transfer momentum to
the clean air
- jet (1) stops normal filtering flow
(2) developes a standing wave in fabric
of the bag which mechanically induces
cake disintegration and discharge
(3) reverse air flow through the bag
for complete fabric cleaning
- felted fabric used and allows collection of
fine, particles
- felted fabrics have high permeability in use
to allow high air to cloth ratios
Slide: 413-9-21
Slide: 413-9-22
205
-------
CONTENT OUTLINE
Course: 413 - Lesson 2
Lecture Title: FABRIC FILTER PRINCIPLES
rftD S7W
-------
CONTENT OUTLINE
Course: 413 - Lesson 9
Lecture Title: FABRIC FILTER PRINCIPLES
Page.
NOTES
(2) twill weave goes over two and under 1 in
one direction only - stronger and more
durable
(3) Satin - over 1 and under 3 - very compact,
can use fine yarn; give fabric less
porosity
(4) different weaving patterns decrease open
area between fiber intersection .'.
.*. influences both strength and permeability
of the fabric
2. Felted — composed of randomly oriented fibers,
compressed into a mat and sealed to some loosely
woven backing material — depend to lesser degree
on initial dust deposits than woven.
(a) generally 2-3 times thicker than woven
(b) more severe cleaning methods required
(c) higher pressure drops
(d) higher A/C ratios
(e) can reduce the exhaust burden down to .005 gr/SCF
(f) should not be used in high humidity especially
if particles are hygroscopic to avoid clogging
and binding of filter.
(g) felted material sometimes napped — fuzz
projecting at end of fabric, can be used to
collect tarry particulates
207
Permeability is the
volume of air which
can be passed throuj
1 ft2 filter medium
with a Ap of no
more than .5 inches
Slide: 413-9-25
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CONTENT OUTLINE
Course: 413 ~ LeB80n 9
Lecture Title: FABRIC FILTER PRINCIPLES
Page-JL—of.
NOTES
B. Types of Fiber
1. Natural
(a) cotton — cheap, readily available
- temperature is limitation •> gases <1808F
- also not recommended for high alkali or acids
- used for abrasive blasting, rock crushing,
conveying
(b) wool — used in metalurigical operations
- resist acid attack
- temperature limitation 220°F
2. Synthetics — nylons, polyesters
(a) nylon - relatively high initial cost
- excellent resistance to abrasion, flexing
and resistance to many chemicals
- thermal restrictions to 220°F
(b) dynel - acrylic fiber
- has low moisture absorption, good strength
- resist many chemicals, mildew, bacteria
- temperature limitation 175°F
(c) orlon and dacron
- good chemical resistance - heat resistance
- temperature limit 275°
(d) teflon - flurocarbon $expensive$
- used for high temperature gases
- 450°F to 500°F
- inert to most chemicals except Cl and Fl
- flex and abrasion strength only fair
(e) Nomex \
- good to excellent resistance to alkali attack
- poor resistance to acid attack
- good resistance to abrasion
- can withstand temperatures to 400°F
- used quite frequently for bag material
208
Slide: 413-9-26
NOTE: Point out
to students
See page 6-21
Table 6.1.2.
-------
CONTENT OUTLINE
Course: 413 ~ Lesson 9
Lecture Title: FABRIC FILTER PRINCIPLES
Page-1-
NOTES
3. Fiberglass
- highest resistance to chemicals and heat
- up to 530°F
- low resistance to abrasion and crushing
- filtering velocity less
- .'. cleaning cycle usually pulse jet
!. Failure Mechanisms — distinct failure mechanisms
affect fabric filters
1. Upper temperature limit of process exhaust pre-
treatment may or may not be feasible because of
problems of hygroscopicity
2. Abrasion — can occur when:
(a) bags rubbing against each other
(b) traveling blow rings mechanism - slight
juggling and rubbing each pass
(c) support rings - filter contacts ring
(d) attach points of bag at top or bottom
(e) 25%/yr. replacement due to this wear
3. Chemical attack — could occur when:
(a) poor fiber selection
(b) change in process (and thus exhaust)
particularly temperature and dust composition
- acid dew point reached etc.
VI. j Design Variables
A. Pressure drop - most talked about variable
1. Pressure drop expressed as: pressure drop per unit
area is a function of the characteristics of a
particular filter medium.
Slide: 413-9-27
209
-------
CONTENT OUTLINE
Course: 413 - Lesson 9
Lecture Title: FABRIC FILTER PRINCIPLES
PRCftf
10
of.
14
NOTES
klvf
In general measurement of the air flow through a
fabric and the pressure drop is by Darcy's Law
directly proportional to flow
(No particulates)Ap,
where
Apf = pressure drop across the fabric usually
expressed in inch of H.O
k- = inch H 0/ft.min.
k- = fabric resistance (inches H20) and is a
function of gas viscosity and filter
characteristics such as thickness and
porosity (permeability)
v- = filtration velocity (ft./min.)
(Say where going to get around
to defining more specifically later)
Pressure drop across the cake:
For the filtration head loss through a dust cake
formed on a fabric filtering particle laden air.
Can be expressed in simplified form as:
Apc = K2c±vf2t
Ap - pressure loss across cake in H.O
C • i
-------
CONTENT OUTLINE
Course: *13 ~ Lesson 9
Lecture Title: FABRIC FILTER PRINCIPLES
^^
s>
Page?—of2L
NOTES
B. Filter Resistance
1. Want to define the filter drag
S - A£ as the filter drag across the fabric - dust
' f layer, and it is a function of the quantity
of dust accumulated on the filter.
2. In industrial filtration - weave important. New fib-
er has considerable interfiber area - open. The true
filtering surface is not the bag itself — but the
dust layer itself. The bag merely provides the
mechanisms for coarse sieving to remove large particle;
by supporting the dust layer. Dust bridges the pores
and the drag increases rapidly. The resistance to
flow-filter drag Ap/Vf is plotted versus the area cake
density PiCft (weight/unit area of cloth)—see figure.
Typically the curve is composed of two zones:
(a) the zone of cake repair
(b) the zone of homogeneous cake formation
3. The drag increases until the total pressure drop
reaches a value set by the system design for
activation of the cleaning cycle. At this point
pressure drop decreases (almost vertically on the
preformance curve) to the initial point cake repair
begins when the cleaning cycle ceases and the
cycle repeats.
4. For multicompartment baghouses — where compartments
are cleaned one at a time. The preformance curve
has a slight sawtooth shape for the net pressure
losses across the entire baghouse. *Note the
average value.
In order to maintain high filtration rate and a high
collection efficiency •*• must select a fabric and
cleaning mechanism which gives a optimal preformance
curve (decrease slope).
211
Slide: 413-9-31
NOTE:
S = A£
v.
v, = filtration
velocity
Slide: 413-9-32
Slide: 413-9-33
Slide: 413-9-34
Slide: 413-9-35
-------
CONTENT OUTLINE
Course: 413 - Lesson 9
Lecture Title: FABRIC FILTER PRINCIPLES
NOTES
(a) If we can minimize the residual drag
(b) Minimize the cake repair time .'. the filtering
surface will rapidly form, collector has a
low pressure drop and the length of the time
between cycles will be longer.
C. Performance Factor
1. Conslstant pressure drop is a critical design factor.
System Ap may be twice the total drag of the cake due
to skin friction and form friction between emission
source and baghouse effluent discharge. Could be as
much as 2-4 in H.O and should be considered when
designing the system.
2. Filtering velocity v. is defined as the actual
volumetric gas flow rate Q divided by the filtering
area A.
v = (£
A
This is the superficial filtering velocity or the
air to cloth ratio which is expressed as a
function of the pressure drop thru the fabric
itself.
Collection Efficiency - High 99.9+
1. Baghouse is only device that is not designed with
use of fractional efficiency curves.
2. Baghouse designed and sized strictly on experience.
- manufacturers can only guarantee to meet opacity
regulations and to meet regulations (grain loading)
3. The manual gives an equation to find
the efficiency (page 6-26 in manual). The equation
uses (4) four empirical constants designated by the
various manufacturers.
VII. Preformance Factors
A. Correct A/C Ratio ~ the delicate balance
1. This is one of the most important factor in design of
baghouses. Good air-to-cloth ratio is imperative for
effective collection efficiency and can prevent pre-
mature hag failure and subsequent replacement.
Slide: 413-9-36
NOTE: mention
table 6.2.1
6.2.2
6.2.3
6.2.4
give recommended
filtering
velocities
Ask question —
Does anyone know
formula for
efficiency design?
Note: 6.2.5
N = (K3-1)/K3
= aLbpCVfd
Slide: 413-9-37
212
-------
CONTENT OUTLINE
Course: 413 " Lesson 9
Lecture Title: FABRIC FILTER PRINCIPLES
Page _!!_ of.
NOTES
a. Again the air to cloth ratio is a term commonly used
to express the cubic feet per minute of air that can
be passed through one square foot of cloth.
8. Performance factors
1. Balancing Form, Headers, Dampers
- must be properly designed. Dampers used to change
bulk gas from one compartment to another
2. Timing devices for cleaning — filtering-cleaning
cycle should be at least 10:1 or greater
3. Allow for dust removal various type of baghouses,
i.e., pulse jet requires conveyers or rotating screws
- size of hopper governed by dust loading, filtration
volume and required dust removal rate.
VIII. Gas Conditioning
A. Cooling - necessary sometimes
1. Dilution - by air - cheapest, especially at high
temperature - but higher air handled as a result
of dilution requires larger baghouse - plus it is
hard to control the intake of ambient moisture
and control other contaminents
2. Radiation — use of duct walls long uninsulated
ducts. Ducts can also be U shaped.
- Radiation below 1000°F requires substantial surface
areas, lengthy duct runs, and increased fan
horsepower.
- Precise temperature control difficult to maintain -
also there is a possibility of plugging by
sedimentation.
3. Evaporative cooling — injecting fine water droplets -
droplets evaporate, absorbing heat from the gas.
(a) add gaseous volume of HJ) .to exhaust stream
therefore bigger baghouse than with radiation
(b) gives greatest amount of cooling at low
installation cost.
(c) temperature control flexible and precise
213
NOTE: recommended
filtering
velocities
Table 6.2.1
6.2.2
6.2.3
6.2.4
in 413 manual
Slide: 413-9-38
Slide: 413-9-39
-------
CONTENT OUTLINE
Course: 413 - Lesson 9
Lecture Title: FABRIC FILTER PRINCIPLES
Page I4— of!_!*_
NOTES
(d) must not let temperature go below the dew point
of the gas - chemical attack
(e) must evaporate all H-0 before gases reach
baghouse •+• to guard against corrosion and
fabric plugging
4. Heat exchangers
5. Combination of all of the above
IX. Review:
The past 1 1/2 hour we have talked briefly about the
following subjects
* Collection Mechanisms
• impaction
• direct Interception
• diffusion
• gravitation
• electrostatic attraction
* Various Filtering Designs
* Cleaning Mechanisms
• Shaking
• Reverse air
• Reverse jet; blow ring
• Pressure jet or pulse jet
* Various fabrics used for baghouses
* Pressure drop
* Cake formation
* Filtering velocity commonly referred to as air to
cloth ratio.
Slide: 413-9-40
Slide: 413-9-41
Slide: 413-9-42
Slide: 413-9-43
214
-------
cottier ton MCCHANISM*
• (Hr*ct Interception
• DWlMlon
VfTATION
0.£Cn»0»T»TtC ATTIACTM*
CXTERKMt
FILTRATION
•cvcjnc irr
•LOWUMC
CUAMN*
CLCANINC MCCHANBMS
• R«v 11 •• Air
• R»v«r»«->«t; Blow Rlfif
TTKSOF FI1CIK
OAitcrs LAW
• ii tTiti
215
-------
= filter drag - or filter
reiitUnee acro»t tin
fabric • dH*tlayer
OVOMU. mtuuiM
FK.1IMTION VELOCITY
IMr lo Ctoth Hot*}
THC
DELICATE
BALANCE
e Direct lnterc*ptt«B
• IMffMlM
• OmibMlM
riLTERIHC DEIGNS
> E»trrlor Filtr.tlor,
CLEANING MECHANISMS
e Sink in t
e R«vert«-J«t. .
* Pr«»»ure-jel
• Fabric MaterUi
e Pressure Drop
e Cake F»rm*t
• Filtration Velocity •
"atto
CPACwilnctNe.
216
-------
LESSON PLAN
TOPIC: FABRIC FILTER APPLICATIONS
COURSE: 413 - Lesson 10
LESSON TIME: 30 minutes
PREPARED BY: DATE.
David S. Beachler
4/79
LECTURE GOAL:
Briefly describe the design factors and criteria
necessary for fabric filter particulate collection
and the various applications where the use of a
baghouse is and.is not appropriate.
LECTURE OBJECTIVES:
STUDENT PREREQUISITE
SKILLS:
At the end of this lesson the students should be able to:
* Recall the advantages and disadvantages of using fabric
filters for collection of particulates.
* Recall the important design factors that are basic to
the design of the control system.
* Recognize the various industries where baghouses can
be used to collect particulate emissions and those types
(or classes) of sources for which baghouses are not
suitable.
Ability to understand basic principles of physical
science and perform calculations using logathrithms
and exponential functions.
LEVEL OF INSTRUCTION: Advanced
INTENDED STUDENT
PROFESSIONAL
BACKGROUND:
Engineering or physical science
SUPPORT MATERIALS
AND EQUIPMENT:
1. slide projector
2. overhead projector
3. chalkboard
4. 413 Student Manual
217
-------
SPECIAL INSTRUCTIONS: The material concerning the use of fabric filters
should be covered briefly, as the problems will take
up most of the time. The author lists in the
413 Manual the various industries where fabric filters
can be applied for particulate emission control. For
additional information concerning emission sources
and rates, control practices and equipment the
student should refer to the reference listed below
titled "Particulates and Fine Dust Removal" by
Sittig.
REFERENCES: 1. 413 Student Manual
2. 413 Student Workbook pp. 20-24
^—^
/ 3. "Air Pollution Control Technology, An Engineering
Analysis Point of View", by Robert M. Bethea, Van
Nostrand Reinhold Company, New York, 1978, pp. 145-208.
"-\
/ 4. "Particulates and Fine Dust Removal", by Marshall
!.»"~
Sittig, Noyes Data Corporation, Park Ridge,
New Jersey, 1977.
5. "Procedures Manual for Fabric Filter Evaluation",
EPA 600/7-78-113, IERL Research Triangle Park,
N. C., June 1978.
6. "Proceedings The User and Fabric Filtration
Equipment Specialty Conference", the Niagara
Frontier Section, Air Pollution Control Association,
Pittsburgh, PA, October 1973.
7. "Proceedings The User and Fabric Filtration II
Equipment Specialty Conference", the Niagara
Frontier Section, Air Pollution Control Association,
Pittsburgh, PA, October 1975.
8. "Proceedings The User and Fabric Filtration III
Equipment Specialty Conference", the Niagara
Frontier Section, Air Pollution Control Association,
Pittsburgh, PA, October 1978.
9. "Industrial Air Pollution Control Equipment for
Particulates", by L. Theodore and A. J. Buonicore,
CRC Press, Inc., Cleveland, OH, 1976.
218
-------
10. "Handbook of Fabric Filter Technology. Vol. I.
Fabric Filter Systems Study", Charles E. Billings,
et. al., distributed by NTIS, PB-200-648, December,
1970.
11. "Appendices to Handbook of Fabric Filter Technology,
Vol. II. Fabric Filter Systems Study", GCA Corporation,
Bedford, Massachusetts, distributed by NTIS.
PB-200-649, December 1970.
12. "Fabric Filter Cleaning Studies", EPA Technology
Series, EPA 650/2-75-009, January 1975.
219
-------
AUDIO-VISUAL MATERIALS FOR LESSON 10
Lesson 10 Fabric Filter Applications
413-10-1 Principal advantages
413-10-2 Principal advantages
413-10-3 Principal disadvantages
413-10-4 Principal disadvantages
413-10-5 Design factors
413-10-6 Design factors continued
413-10-7 Live shot of baghouse
220
-------
CONTENT OUTLINE
Course: 413 - Lesson 10
Lecture Title: FABRIC FILTER APPLICATIONS
Of-JL
NOTES
i.
A. Principal Advantages
1. Collection efficiency high— 99.9% can reduce
effluent down to .005 gr/SCF
2. Efficiency and pressure drop — unaffected by
changes in inlet loadings - cyclic process rates
3. Filtered air can be recirculated within plant —
heating purposes (if gases are not toxic)
4. Collected material dry for subsequent disposal
or reprocessing
5. Eliminates major H^O pollution problems, liquid waste
liquid freezing
6. Corrosion and rusting of components usually
no problem
7- No hazzard of high voltage — simplifying
maintanence and repair — and permitting collection
of flammable dusts
8. Low initial costs — compared to ESP and scrubbers
9. Moderate power comsumption
B. Principal Disadvantages
1. Large size — installation space
2. High maintenance requirement — broken bags
difficult to detect
3. Fabric life can be shortened by acidic or alkaline
particle or gas constituent
4. Upper temperature limit — some filters will operate
in 550°F range
5. Hygroscopic materials, condensation of moisture or
tarry adhesive components may cause crusty caking
or plugging of the fabric or require special
additives
413-10-1
>r
413-10-2
413-10-3
413-10-4
221
-------
CONTENT OUTLINE
Course: 413 - Lesson 10
Lecture Title:
FABRIC FILTER APPLICATIONS
Page 2 of-J*
NOTES
III,
6. Concentrations of some dusts in the collector may
represent a fire or explosion hazzard if spark or
flame is admitted by accident. Fabrics will
thus burn.
7. Fabric must maintain mechanical durability — tensile
2,
3.
4.
and flex strength. *Bag life is simple most important
problem
8. Replacement of fabric (bags) may require respiratory
protection for maintenance personnel.
II. Name the important design factors that must be considered
when designing a baghouse for emission control of a
specific process.
1. Space restrictions
Method of cleaning - shaking, reverse air, pulse jet
Use of negative or positive system - toxic materials
require negative
Construction of system - field, shop, modular, panel,
5. Types of fabrics - natural, synthetic, glass
6. Air to cloth ratio
7. Need for gas cooling or preconditioning
8. Provision for maintenance and access—one must be
able to get to bags for replacement.
9. Problem of emission capture - hoods, ducts, fans
10. Material handling equipment - hoppers, screw
conveyers, dust removal, etc.
11. Effluent discharge - stack, single or double
12. Electrical controls - for cleaning mechanisms, etc.
from a single timed cycle to one that cleans when
Ap is at design level.
Design Criteria
The principal design criterion is the 8a8 flow rate,
measured in actual cubic feet per min. ACFM. The volume
to be treated is fixed by the process (source) but the
filtration velocity or air to cloth is up to the designers.
A. The velocity depends on:
1. Dust loading
413-10-5
compartment •
413-10-6
-------
CONTENT OUTLINE
Course: 413 - Lesson 10
Lecture Title: FABRIC FILTER APPLICATIONS
Page.
NOTES
2. Type, shape and density of dust
3. Type of fabric - natural, synthetic, etc.
4. Fabric construction - woven or nonwoven, thickness
2
of fabric, fiber size, fiber density - fibers/area ,
napping, allowable pressure drop before initiation
of cleaning, residual drag of freshly cleaned medium
5. Cleaning method - high AP cleaning methods (pulse jet)
allows high A/C ratio
6. Amount of flexing and creasing is a result of
cleaning - higher A/C causes more cleaning thus more
flexing and creasing
7. Fraction of bags out of service due to leaks
B. Cleaning time
1. Ratios of filtering time to cleaning time is the
measure of the % of time filter is performing
effectively should be at least 10:1 or greater
C. Power requirement - keep pressure drop low - by
minimizing residual drag C
D. Bag spacing important — there must be enough room
for proper inspection of bag failures.
E. Allowance for proper cleaning of bags - N + 1 components
1. Allow reserve capacity for off-line cleaning
2. Inspection and maintenance for broken bags
IV. Selected applications - fabric filter applications are
as varied as the type of systems and the fabrics available
Some possible uses for baghouse in industry are:
1. Steel industry:
• Electric arc furnaces
. . ... _T^^* cooling first
• Open hearth furnaces *—•*•" B
• Boiler operations
2. Foundry cupolas:
• Gases cooled from +1000°F to 500°F
3. Nonferrous metal furnaces:
• Lead
• Copper smelters
• Zinc 223
413-10-7
-------
CONTENT OUTLINE
Course: 413 ~ Lesson 10
Lecture Title: FABRIC FILTER APPLICATIONS
Page.
of—L
NOTES
Must be careful not
to permit baghouse
to reach explosive
concentrations.
4. Grain handling operations:
• Cleaning
• Handling
• Grinding
• Blending
5. Chemical industry:
• Dryers
• Grinding mills
6. Carbon black plants
• Gases must first be cooled (steam injection)
• Carbon black generated by burning oil or tar
in furnaces and collecting the dust load
7. Cement kilns:
• Collection of dust from rotary cement kilm
8. Power plants:
• Successful operation on the gudburyPower Plant, PA
175 msr.
• Nucela Station - Colorado
9. There is a table in the 413 Manual that lists some seljected
fabric filter applications, and lists such variables
as:
* Dust type - process name
,* Efficiency
* Average particle size
* Inlet temperatures
* A/C ratio
* Pressure difference AP
* Cloth type
10. Mention sources that a baghouse would not be
appropriate.
a. liquid or water-laden gaseous streams
b. high temperature gas streams where proper
cooling was not economically feasible.
(open hearth or basic oxygen furnaces)
X 224
Point out
Table 6.3.1
-------
225
-------
LESSON PLAN
TOPIC: PROBLEM SESSION VI
FABRIC FILTERS
COURSE: 413 - Lesson lOa
LESSON TIME: 1 hour
PREPARED BY: DATE:
David Beachler
6/79
LESSON GOAL:
Briefly describe the use of the pressure drop and
collection efficiency formulas covered in the Fabric
Filter lessons by solving four problems.
SUPPORT MATERIALS
AND EQUIPMENT
1. Chalkboard
2. 413 Student Workbook pp. 20-24.
226
-------
CONTENT OUTLINE
*
^ff2
Course: 413 " Lesson lOa ^^sMttsV^
Lecture Title: FABRIC FILTERS - PROBLEM SESSION*?!
***£
nfO&
-^QfjL
NOTES
I. Problem 6-1
A. Work out problem 6-1 for students. The solution for 6-1 is:
NOTE: See problem
6-1 on page 20 of
the 413 Student
Workbook.
6.1 Fabric Filters — Number of Bag Calculation
Snail scale tests showed that filtration of an air stream containing
one grain of particulates per cubic foot of air gave a maximum
pressure drop of 5 inches of water at a flow rate of 3 ft3/min per
square foot of filtering surface .
a. Calculate the horsepower required for a fan for a flow
rate of 6,000 ft3/min.' through the baghouse.
b. Calculate the number of 0.5 ft diameter by 10 ft
filtering bags required for the system.
Assume an over-all fan-motor efficiency of 63%.
SOLUTION:
(a) hp
If low rate] _ -i r- -j
= LCFM J x [Ap inches H2OJ [1.575 x 10~J
(Chemical Engr. Handbook)
efficiency (fan)
hp -
hp
(6000 ftj ) x
min
5 inches
H20 x 1.575 x 10~4
.63
7.5
(b) Area of Bag « 2irrH or ffDH
- (3.14)(.5 ft)(10 ft)
- 15.7 ft2
3
Total filtering area - 6000 ft /min
3 ft3/min/ft2 filtering surface
- 2000 ft2 (filtering surface)
.3
// bags required
filtering surface - 2000 ft"
area/bag 15.7 ft2/bag
- 128 bags
227
-------
CONTENT OUTLINE
Course: 413 - Lesson 10a
Lecture Title: FABRIC FILTERS - EROBLEM SESSION
nf fi
NOTES
II. Problem 6-2
NOTE: See problem
A. Work out problem 6-2 for the students *~2
B. The solution for problem 6-2 is:
6.2 Fabric Filters - Number of Bags and Pressure Drop
the
Workbook
A plywood mill plans to install a fabric filter as an air cleaning
device.
a. How many bags, each 8 inches in diameter and 12 ft long,
must be used to treat the exhaust gas which has a particulate
loading of 2 grains/ft and the exhaust fan is rated at 7,000
ftJ/min?
b. If the pressure drop is given by the formula
Ap = Ap , + Ap.
* *clean 'oust
fabric cake
Estimate the pressure drop after four hours of operation if
the resistance coefficients of the filter and dust cake are,
respectively, K., s 0.8 inches water/ft min. and K- • 3 inches
water/(Ib/dust/ft cloth area)(ft/min, filtering velocity).
Assume velocity is 2 ft/min.
| SOLUTION: I
(a) With 2 ft/min as the filtration velocity
(1) Total area - 2
required - 7000 ft3/min - 3500 ft
2 ft/min
(2) Area of each Bag - IT D H
- (3.14) (B in. \ x 12 ft
\12 in/ft/
- 25.13 ft^/bag
(3) # bags required -
Total Area - 3500 ft2 - 139 bags
area ea. bag 25.13
(b) The pressure drop is given by the following realtionships
clean
Ap « Ap fabric + Ap (of dust cake)
Ap - kv + k c v2t
2 grains
-/.8 inches H20\ /2ft/minj + 3 inches H20 x ft3 x/2 ft \2 x 4 hr x 60 min
V ft-min / \ / lb dust/ft*(ft/min) 7000 gr \ n»in/ hr
lb
Ap - 2.42 in H,0
v 2 228
-------
CONTENT OUTLINE
Course: A13 ~ Lesson 10a
Lecture Title: FABRIC FILTERS - PHOBLEM SESSI
Surf*
Page.
of.
NOTES
III. Problem 6-3
A. Have students work problem 6-3 on page 22 of the 413
Problem Workbook
B. Allow the students 10 minutes to solve the problem; then
go over the solution. The solution to 6-3 is:
6.3 Fabric Filters — Number of Bags and Cleaning Frequency
o
A plant emits 50,000 acfm of gas with a dust leading of 5 grains/ft .
The dust is collected by a fabric filter at 98% efficiency when the
average filtration velocity is 10 ft/min. The pressure drop is
given by
NOTE: See problem
6-3 on page 22 of
the 413 Student
Workbook
Ap - 0.2v
5c.v2t
where:
Ap IB the pressure drop in inches of water,
v is the filtration velocity in ft/min,
c. is the dust concentration in lb/ft3 of gas,
t is the time in minutes since bags were cleaned.
a. How many cylindrical bags, 1 ft in diameter and 15 ft high
will be needed?
b. The system is designed to'begin cleaning when the pressure
drop reaches 8 inches of water. How frequently should the
bags be cleaned?
SOLUTION:
(a) The required surface area of the bags is
Total area = 50.000 ft3/min - 5000 ft2
10 ft/min
area of each bag = IT D H
- 3.14 x 1 ft x 15 ft
- 47.12 ft2/bag
Number of bags needed
- 5000 - 106 bags
47.12
(b) Ap - .2v + 5 c., v2t
Ap - .2v
5 c< v'
t - 6 inches H20 - .2 in. H^O x 10 ft
ft/min min
_ _
(5 in. H,0 _ \ , , \ / \
Ib dust x ft /x/ 5gr/ft3 WlOft ]
"ft* min7 \7000 gr/lbj \ min/
t - 16.8 min. between cleaning
229
-------
CONTENT OUTLINE
Course: 413 - Lesson lOa
Lecture Title: FABRIC FILTERS
PROBLEM SESSION'V
PageJi ofJi.
NOTES
IV. Problem 6-4
A. Have students work problem 6-4 on page 24 of the 413
Problem Workbook.
B. Allow the students 10 minutes to solve the problem; then
go over the solution with the student. The solution to
6-4 is:
(See following sheets)
NOTE: See problem
6-4 on page 24 of
the 413 Student
Workbook
230
-------
6.4 Fabric Filters — Design of Filter Bag
It is proposed to install a pulse-j.et fabric filter system to clean
a 10,000 scfm air stream at 250°F, containing 4 grains/ft3 of pollutant.
For a 99% efficiency, the average air-to-cloth ratio is 2.5 cfm/ft2
cloth. The following information, given by filter bag manufacturers,
is available at the beginning of the selection process:
Filter *ag A ^ C D
Tensile Strength Excellent Average Fair Excellent
Recommended
Maximum Operation 260 275 260 220
Temperature, °F
Resistance n 0 , _ _ _
Factor °'9 1'° °'5 °'9
Relative Cost
Per Bag 2.6 3.8 1.0 2.0
Standard Size 8" x 16' 10" x 16f 1" x 16' I1 x 20'
a. Determine the filtering area required for this operation.
b. Based on the required area and the above information, select
the most suitable filter bag and calculate'the number of them
that should be used. The proposal of a pulsed jet device
using strong forces to clean the bags necessitates the
selection of a fabric with at least above average tensile
strength.
SOLUTION:
(a) A = ACFM
CFM/ft-3 cloth or ft/min
Must change SCFM to ACFM
= (10,000 SCFM) x 250° + 460 - 13,654 ACFM
520
A = 13.654 ft3/min = 5462 ft2
2.5 ft^
min/ft2 or (ft/min)
(b) The temperature of the gas stream is 250°F. Material D can't be used
because it shows a maximum bag temp of 220°F.
Since a pulsed jet unit is being used and requires a selection of fabric
with at least above average tensile strength, material C can be eliminated
Therefore A and B should be considered.
231
-------
6 of 6
6.4 (b) cont'd
Area/bag = if D H
= (3.14) /8 in N (16) - 34 ft2/bag - Filter Bag A
\12 in/ft/
- 3'. 14 /10\ (16) - 42 ft2/bag ~ Fllter Ba* B
#/bags A - 5462/34
B = 5462/42
Filter Bag
A
B
Area/bag
ft2
34
42
# bags
161
130
cost/bag
(2.6)
(3.8)
Relative
Cost
418
494
Based on calculations the choice would be filter A because of its lower
relative cost.
and 161 bags are required.
232
-------
LESSON PLAN
TOPIC: WET COLLECTOR THEORY
COURSE: 413 - Lesson 11
LESSON TIME: 1% hour
PREPARED BY: DATE:
J. A. Jahnke
3/14/79
LESSON GOAL:
To present the hydrodynamic principles occurring in
wet collector applications and to introduce the various
methods used to estimate collection efficiency from
such systems.
LESSON OBJECTIVES:
The student will be able to:
* List the dominant physical mechanisms involved in
wet scrubbing.
* Describe the relative effect of particle size,
relative velocity and droplet size on the
dimensionless "separation numbers" (target
efficiency) for each mechanism.
* Calculate the average droplet size of a gas
atomized spray using the Nukiyama-Tanasawa relation.
* Define the terms, "Inertial impaction parameter,"
"penetration," "liquid to gas ratio,"
and "transfer unit."
* Calculate the collection efficiency for a venturi
scrubber using the Johnstone correlation.
* State the "cut-power" rule developed by Calvert
and give the assumptions associated with the rule.
* Calculate the penetration associated with a given
particle cut diameter and scrubber type using the
cut power rule.
233
-------
* State the fundamental assumption associated with
the contact-power rule.
* Calculate the efficiency of a scrubber by the
contact-power rule, given the appropriate
input parameters.
* Discuss the use of pilot plants for the selection
and evaluation of wet scrubber systems.
STUDENT PREREQUISITE
SKILLS:
Ability to understand basic physical science
principals and perform calculations with logarithms
and exponential functions
LEVEL OF INSTRUCTION:
Advanced
INTENDED STUDENT
PROFESSIONAL BACKGROUND: High school math and general science. Understanding
of first day's course lecture material
SUPPORT MATERIALS
AND EQUIPMENT:
1. overhead projector
2. slide projector
3. chalk board
4. 413 Student Manual
SPECIAL INSTRUCTIONS:
This is a rather involved lecture. The students, however,
should not be made to feel lost since most of the
equations are empirical in nature. A detailed under-
standing of the theoretical bases behind the efficiency
correlations is not within the scope of the course and
is not of particular interest to the students in any case.
The central point of the lecture is to present the
empirical expressions currently in vogue for the
calculation of particulate collection efficiency for wet
scrubbers. Since the contact power rule is most commonly
used in industry, it should receive the major emphasis
in the lecture.
234
-------
The lecturer may wish to combine the problem session
with this lecture, breaking up the lecture by introducing
appropriate problems after the discussion of each
theoretical approach.
REFERENCES: 1. 413 Student Manual
2. Calvert, S.s "How to Choose a Particulate
Scrubber," Chemical Engineering, August 29, 1977,
pp. 54-68.
3. Semrau, K. T., "Practical Process Design of
Particulate Scrubbers", Chemical Engineering,
September 26, 1977, pp. 87-91 (and references
therein).
4. Mcllvaine, R. W., "When to Pilot and When to Use
Theoretical Predictions of Required Venturi
Pressure Drop." APCA paper #77-17.1 70th Annual
Meeting of APCA, Toronto, Ontario, June 20-24, 1977.
5. Perry, R. H. and Chilton, C. H., Chemical Engineer's
Handbook Fifth Edition, 1973, McGraw-Hill, N.Y.,
pp. 20-94 - 20-97.
6. Kashdan, E. R. and Ranade, M. B., "Design
Guidelines for an Optimum Scrubber System",
EPA-600/7-79-018, Jan. 1979.
235
-------
AUDIO-VISUAL MATERIALS FOR LESSON 11
Lesson 11 Wet Collector Theory
413-11-1 Wet collector theory—topics to be covered
413-11-2 Wet collector theory—collection mechanisms
413-11-3 Contact zone and separation zone
413-11-4 Advantages for using scrubbers
413-11-5 Advantages for using scrubbers
413-11-6 Disadvantages of scrubbers
413-11-7 Forces used in collection equipment
413-11-8 Direct interception
413-11-9 Impaction
413-11-10 Diffusion
413-11-11 Dominant collection mechanisms—direct interception and diffusion
413-11-12 Separation number or impaction parameter
413-11-13 Target efficiency—defined
413-11-14 Collection probability
413-11-15 Estimation of target efficiency
413-11-16 General target efficiency for direct interception
413-11-17 Impaction parameter for inertial impaction
413-11-18 Target efficiency for diffusion
413-11-19 Diffusion collection mechanism important—graph of collection
efficiency versus particle size
413-11-20 Johnstone equation
413-11-21 Johnstone equation for venturi collection efficiency
413-11-22 Japanese literature search
413-11-23 Estimating d from the Nukiyama-Tanasawa relationship
413-11-24 Cut power theory—an emperical approach
413-11-25 Particle penetration
413-11-26 Cut diameter definition
413-11-27 Graph cut diameter versus physical size of particle
413-11-28 Cut power rule expression
413-11-29 Performance cut-diameter plot
413-11-30 Scrubber selection plot—cut power relationship for gas
atomized spray scrubbers
236
-------
413-11-31 Contact power
413-11-32 Wet collector theory—contact power
413-11-33 Fundamental assumption of contact power theory
413-11-34 Number of transfer units
413-11-35 Relation of efficiency to number of transfer units
413-11-36 Total pressure loss expression: PT
413-11-37 Gas pressure drop
413-11-38 Power derived from liquid stream
413-11-39 Total pressure loss equation
413-11-40 Relationship between transfer units and contacting power
413-11-41 Wet collector theory—pilot systems
413-11-42 Methods for predicting venturi scrubber pressure requirements
237
-------
CONTENT OUTLINE
Course: 413 - Lesson 11
Lecture Title: WET COLLECTOR THEORY
Poge-L—of-i:
NOTES
I. Introduction
A. The device in general
1. The scrubber is a device using a liquid for
removing substances from a gas stream.
2. Can remove both gaseous and particulate matter.
3. Have many different types of scrubbers
(like in a Chinese restaurant - have
many choices, but only a small number or basic
ingredients).
4. In a wet scrubber, aerosol particles are
confronted with "impaction" targets -»• can be wetted
surfaces or individual droplets.
5. Therefore, have a contact zone and a separation zone.
6. Scrubbers have advantages and disadvantages
a. Some Relative Advantages
• No secondary dust sources
• Small space requirements
• Ability to collect gas as well as particulate
• Ability to handle high temperature, high
humidity gas streams.
• Ability to humidify a gas stream
• Fire and explosion hazard at a minimum
b. Some Relative Disadvantages
• Corrosion problems
• Ability to humidify a gas stream (meteorologica
• Pressure drop and power requirement
• Water pollution
• Difficulty of by-product recovery
II. Mechanisms involved in wet collection
A. Note = will get to specific scrubber designs later in the
afternoon, first want to understand some of the
principles
238
Slide:413- 11-1
NOTE: An expert
could spend a day
on each of these
topics. Here you
have 1*5 hour to do
all five. Good
Luck!
413- 11-2
Chem Eng, Calvert
p. 55
413- U-3
413- 11-4
413- 11-5
413-11-6
Describe mechanisms
first
413- .11-7
-------
CONTENT OUTLINE
Course: 413 ~ Lesson 11
Lecture Title: WET COLLECTOR THEORY
Page-2.— of 12
NOTES
B. Possible Mechanisms
1. Gravitational Force
2. Centrifugal Force
3. Inertial Impaction
4. Direct Interception
5. Diffusion
6. Electrostatic Force
C. Dominant Mechanisms for particle - droplet interception
1. Direct Interception
dr
D.
E.
> 100 pm becomes Important as _P •*• 1 Where dn is part Lcle diameter
in general d . ^50 °
o mxn u
d is drop
but d < 5
P
2. Inertial Impaction - Most scrubbers designed to
utilize this mechanism
>1 Um (impingement)
3. Diffusion (Brownian Motion)
Important only < .5 urn
4. Dominant Mechanisms./ Inertial impaction
^•Diffusion
Separation Number:
Associated with these mechanisms, have a dimensionless
group called the "separation number", "impaction parameter
This is related to the "target efficiency" for one obstacle
(drop) for a given particle size.
1. Defined — the percentage of particles in the total
cross-section swept out by the droplet, that will
be collected by the droplet.
or
the ratio of the cross-sectional area of the gas
stream cleaned of particles (all of which are alike)
to the projected area of the obstacle.
239
Slide:413- 11-8
et diameter
413-11-9
413-11-10
413-11-11
413-11-12
413-11-13
-------
CONTENT OUTLINE
Course: 413 - Lesson 11
Lecture Title: WET COLLECTOR THEORY
PHO«*
Page— _
NOTES
2.
Slide 413-11-14
define a distance d' (depends on particle diameter). If
the initial position of the particle (diameter d ), is
P
within + d.', it will be collected. If it's magnitude
2
is greater than d'/2, it will escape impingement
For large particles, >d >d'
as d increases, will reach a point where d1/, •*• 1
P do
If d decreases, particle behaves more like a gas
molecule and will diverge and not impinge
d' •*• 0 /interested at most, ]
d I where d *- .1 d ]
o ^ p o /
3. Quantitative Estimation of target efficiency nT
~" ^&fi^-
2 Xfc£j\ Area swept
= clean
1
-^~
413-11-15
collection
area
nT a fen of particle diameter, just as d' was.
4. Now d' is a nebulous thing -*• it is characterized in
terms of the collection mechanism. For each collection:
mechanism is associated an impaction parameter —
Target efficiencies are analytically and experimentally
correlated with the impaction parameter
a. Direct interception
¥ = d and n_ •
^
Where r\ is the fractional collection efficiency of
particles of size d by drops of size d
b. Inertial impaction - (derived from continuum
mechanics Stoke1s Law considerations)
240
413-11-16
NOTE: n,
So"
\ is a
function of the
quantity dn
-------
CONTENT OUTLINE
Course: 413 - Lesson 11
Lecture Title: WET COLLECTOR THEORY
PageJl of 12.
NOTES
constant particle density
ft - K ? d 2
*•
at venturi throat
gas viscosity *drop diameter
want small collector, high relative velocity, large
particles. (Venturi' s are efficient because they have
a high relative velocity)
c. Diffusion
V = RT
yg v
MB
, d d
p/o o p
-V
v , d d
p/o o p
down to 2-3y size particles, continuum mechanics
breaks down, talk instead of kinetics
2
no longer has physical meaning, but
is defined the same way for conveniei
/d'l
_ = \~T~\
ce
Note, when diffusion becomes important efficiency
increases with decreasing particle size
413-11-17
413-11-18
413-11-19
III. Johnstone Equation for Venturi Scrubbers
Equation developed for estimating Venturi Scrubber
efficiency -»• are many others^most have empirical constants,
In any wet scrubber, have a number of collecting particles. Have
to generalize from a single collector to a number of collectors.
Exposure 1
Fraction Captured
Fraction Escaped
An attempt to
describe scrubber
performance from
basic mechanisms
The derivation from
this point to the
Johnstone expressioi
is optional. It
should only be givei
if you have an
attentive class. A
group of non-
engineers will be
lost from the start.
241
-------
CONTENT OUTLINE
Course. 413 - Lesson 11
Lecture Title: WET COLLECTOR THEORY
SO
\
5 „/ 12
NOTES
Exposure 2
Fraction Captured
nj (1 -nj)
Exposure 3
' nl ~
Fraction Escaped
rij (l - nz)
' n
or
Generalizing
g
get (1 - n-r) o
In General:
- nz)
where S is the number of exposures
-x x2 x3
e x = 1 - x + |y - |j •"
for small x -x f n
S Q
U\ ° ~IT"~
— *\-r) = e l o
Total efficiency is then *
np
generally don't know S -»• depends upon type of scrubber.
For a venturi Q
-v-
n - 1 - e
where 1* = Cpvd
d is estimated from the Nukiyama-Tanasawa relationship
for droplet size from high-pressure atomization.
Note that n, is a
function of
particle size and i
quantitatively
described in terms
of the collection
mechanisms given in
II of this lecture.
413^1-20
See page 5-44 of
Manual
413-.11-21
Johnstone came up
with this semi-
empirical expressio
using the concepts
of II-4 and the
expression n =
i -s nT p
1 -e o I
413-11-22
242
-------
CONTENT OUTLINE
Course: 413 - Lesson 11
Lecture Title: WET COLLECTOR THEORY
Poge 6 nf 12
NOTES
/2
For a venturi
d = 16,400
o
•f 1.45
1.5
v = gas velocity at venturi throat (ft/sec)
JL = ratio of liquid-to-gas flow rates (gal/1,000 ft )
QG
IV. Cut-Power Rule
(Another way of describing scrubber efficiency - more
general than the Johnstons formalism)
A. Introduction
1. A semi-theoretical approach - general approach
given by Calvert
2. Relates scrubber fractional efficiency to power
consumption. Estimates scrubber performance
B. Definition necessary for understanding "Cut-Power"
Rule
1. Particle Penetration (Pt) *
Pt = c 0 = Outlet particle concentration
Inlet particle concentration
note, efficiency
n-1-* =i-co = Ci.co
2. "Cut diameter" (d )
pa
Review:
Cut diameter = diameter of particle which is
collected at 50% efficiency
243
413-11-23
Note that Johnstone
eq. has limitations
— there are other
approaches made by
other people
413-11-24
An empirical approach
See Calvert
Chem. Eng.
p. 54-68
August 29, 1977
413-11-25
413-11-26
Figure 413-A1-27
-------
CONTENT OUTLINE
Course.-413 - Lesson 11
Lecture Title: WET COLLECTOR THEORY
7 „/ 12
NOTES
V
physical particle
size
i Particle
Density
Cunn
C.
ingham
correction
factor
Aerodynamics
diameter
3. Define
d _ as the cut diameter required for a specific
application.
i.e., the diameter of the particle which must be
collected at 50% efficiency to obtain desired
scrubber operation.
4. Define
d Geometric-mean particle diameter
Pg
5. Define
0g standard geometric deviation of the particle
size distribution.
The "Cut-Power" Rule
(a) Most scrubbers, where collection is by inertial
impaction, follow the exponential relation.
- exp t-."-— '
Where 1 - i"" particle size
A = constant depending primarily on the liquid
to gas ratio, droplet size, and particle density.
B = a constant which may be taken as 2.0 for most
Inertial wet scrubbers.
(Get fractional efficiency curve)
244
Note: This should
have been given
in 1st day lecture.
May need to review.
413-11-28
-------
CONTENT OUTLINE
Course: 413 - Lesson 11
Lecture Title: WET COLLECTOR THEORY
\
Page 8 o/-Jg_
NOTES
Pt
(b) Integrating this over the particle size distri-
bution (assuming a lognormal distribution), obtaii
the performance cut-diameter plot
A function of the shape of the size distribution
as measured by the standard geometric deviation,
Overall Pt
it = ^ Ptl + K2 8t2 = Z M± Pti
Where :
M, = mass of particles having side i.
Where:
413-0.1-29
dRC is the required cut-diameter
d is the geometric-mean particle diameter
D. Example
Suppose that the size distribution has d = 10u
Pg
and ag « 3.0 and EPA requires 99% collection
efficiency.
Now —
Pt • = 1 - n
?F " i ~ '"
= .01
from the performance cut-diameter plot for P = .03
ag = 3.0
d.,,.
[mass-median diamete
.063
Since d = 10 y
Pg
RC
Need to have a scrubber with a cut diameter of .63y
or less to achieve 99% collection efficiency.
245
-------
CONTENT OUTLINE
Course: 413 - Lesson 11
Lecture Title: wj> COLLECTOR THEORY
NOTES
E. Scrubber Selection Plot
1. Gives type of scrubber whose performance will give
the required cut diameter
2. Gas phase pressure drop and scrubber power are also
given.
3. Cut power relationship given in Figure
a. Derived from performance test on industrial
installations combined with mathematical
modeling.
b. Cut diameter given as a fen of power input
hp/10 ft-Vmin or gas phase pressure drop
(H20)
c. Devised and tested on basis of published
data available
d. Back to example:
only "unaided" scrubbers capable of giving
a .6 ym cut diameter are the gas atomized and
fibrous - packed-bed types.
Require 13" lUO for gas-atomized scrubber
e. Power axis is based on 50% efficiency for a
fan and motor combination.
F. Limitation of the Technique
In general, the limitations of the techniques for
measuring flyash size distributions, undermine
the usefulness of the cut-power approach.
V. Contact Power Theory (Another general way of describing scrubber
performance)
413-11-30
413-11-31
A. Introduction
1. Developed by Semrauupon observation of
earlier work done by Lapple and Kamak.
2. A completely empirical approach to the design
of partlculate scrubbers.
246
See page 5-44 of
Manual
413- 11-32
Another empirical
approach
Note that this is
the most widely use
semi-theoretical
approach used today
However, do need
prior information
from similar
systems
-------
CONTENT OUTLINE
Course: 413 - Lesson 11
Lecture Title: WET COLLECTOR THEORY
Page 10
NOTES
B.
3. The Fundamental Assumption of Contact Power Theory
"When compared at the same power consumption, all
scrubbers give substantially the same degree of
collection of a given dispersed dust, regardless
of the mechanism involved and regardless of whether
the pressure drop is obtained by high gas flow
rates or high water flow rates."
Collection efficiency increases as pressure drop
increases — only significant departure is when
steam is condensed in the scrubber.
Definitions
1. Contacting Power - The power which is dissipated
in mixing the dirty gas with the scrubbing liquid.
(it does not include mechanical power losses in
motors, bearings, etc., nor does it include frictioji
loss in gas flow in the dry state.)
2.
Transfer Units
Remember Penetration?
Penetration = 1 - n
(Note: efficiency is usually an exponential
function of the process variables for most types of
collectors and hence is for correlation purposes
an Insensitive function in the high efficiency
range). (Penetration, is generally preferable
under these conditions).
Still better is the number of transfer units
413-11-33
3. Total Pressure Loss (P_)
(Note P_ is not penetration in this formalism)
413^11-34
413-11-35
Note analogy to
Johnstone eq.
Table 1
JAPCA June I960,
10-3 p.200
247
-------
CONTENT OUTLINE
Course: 413 - Lesson 11
Lecture Title: WET COLLECTOR THEORY
X!!%
:*
-------
CONTENT OUTLINE
Course: 413 - Lesson 11
Lecture Title: WET COLLECTOR THEORY
NOTES
VI. PILOTING
A. Place of pilot plant data in scrubber design
1. Most large scrubber installations are designed
with aide of pilot, plant data.
2. Limitations to theoretical approaches for example
Contact Power Theory applies only whan energy is-
confined to one scrubbing area--not good for
packed tower s.
B.
Types of pilot plants
1/10 full-scale plants
413.11.41
Refer to:
R.W. Mcllvance "When
to pilot and when to
use theoretical
>redictions of re-
quired venturi
pressure drop"
APCA paper 77-17.1,
presented at 70th
Annual Meeting of
APCA, Toronto, 1977.
1.
2.
3.
4.
example: TVA-Shawnee, 30,000 CFM scrubbers
(millions of dollars involved)
2000 CFM plants
Common size available from many scrubber
manufacturers ($20-60,000)
100 CFM plants
Some skepticism, but have been shown to give
accurate predictions
1 CFM miniature scrubber
New - evidence around to show that it can give
accurate predicitons.
VII. LECTURE SUMMARY
Methods for Predicting Venturi Scrubber Pressure Requirements
Most Reliable
DESCRIPTION"
EXPENSE TIME
(Relative Scale) (Mos)
413-11.42
*1/10 size full-scale plants
*2000 CFM pilot units
*100 CFM pilot units
*1 CFM mini-scrubber
Empirical curves based on
similar processes
Impactor in situ particle
sizing
Less expensive prediction
methods
100-1000
30
5
1
0.2
1
0.2
12-24
3-6
2-3
1
0.2
0.5
0.2
Theoretical calculations
Least Reliable
*A11 of equal reliability for determining just the
pressure requirement.
249
-------
250
-------
25J
-------
LESSON PLAN
TOPIC: PROBLEM SESSION VII -
WET COLLECTOR
COURSE: 413 ~ Lesson lla
LESSON TIME: 1 hour
PREPARED BY: DATE: 3/14/79
J.A. Jahnke
LESSON GOAL :
LESSON OBJECTIVES:
To review the basic concepts of wet collector theory given in
the previous lecture, by direct application of the theory
in problem session.
The student will be able to:
1. Calculate the efficiency of a scrubber by the Contact
Power Rule, given the appropriate input parameters.
2. Calculate the penetration associated with a given
particle cut diameter and scrubber type, using the
cut power rule and also to calculate the pressure
drop across the system.
3. Calculate the collection efficiency for a venturi
scrubber, using the Johnstone Correlation.
STUDENT PREREQUISITE SKILLS:
Ability to understand basic physical science principles and
to pertorm calculations with logarithms and exponential
functions. A basic understanding of the previous lecture on
Wet Collector Theory.
LEVEL OF INSTRUCTION: Advanced
INTENDED STUDENT
PROFESSIONAL BACKGROUND:
High school math and general science. Understanding of first
day's course lecture material.
SUPPORT MATERIALS
AND EQUIPMENT:
1. Chalkboard or overhead projector
with acetate for working problems.
2. 413 Student Workbook
3. Slide projector
252
-------
SPECIAL INSTRUCTIONS: Problems 7.1, 7.2, 7.3, and 7.4 deal with wet collector
applications. Major emphasis should be placed on the
problems dealing with Contact Power Theory.
It is advisable for the instructor to work along with the
students in these problems. Get them started, let them
work on one step of the problem alone, then after 5 or 10
minutes, explain how the step is to be done. Proceed to
the next step of the problem, and so on. Do problem 7.1
in this manner. They should then be able to do problem 7.2
on their own.
Problem 7.3 is difficult for the students to do alone.
Although the solution is simple, some of the non-engineering
students may find the graphical manipulations unfamiliar.
Lead the students on to the solution.
Problem 7.4 should not be done in class, but should be
assigned as homework. It will take approximately 1 to 2
hours for the student to solve. Give hints as to how to
approach the problem and review the problem in the
review session the next morning.
NOTE: The instructor should not view this problem session
as "time-off". A good instructor will be present the entire
time, assisting the students and leading them in the right
direction.
Good students will require less effort, poorer students will
demand more effort on the part of the instructor.
REFERENCES: 1. 413 Student Manual
2. Calvert, S., "How to Choose a Particulate
Scrubber," Chemical Engineering, August 29, 1977,
pp. 54-68.
3. Semrau, K. T., "Practical Process Design of
Particulate Scrubbers", Chemical Engineering,
September 26, 1977, pp. 87-91 (and references
therein).
4. Mcllvaine, R. W., "When to Pilot and When to Use
Theoretical Predictions of Required Venturi
Pressure Drop." APCA paper #77-17.1 70th Annual
Meeting of APCA, Toronto, Ontario, June 20-24, 1977.
5. Perry, R. H. and Chilton, C. H., Chemical Engineer's
Handbook Fifth Edition, 1973, McGraw-Hill, N.Y.,
pp. 20-94 - 20-97.
6. Kashdan, E. R. and Ranade, M. B., "Design
Guidelines for an Optimum Scrubber System",
EPA-600/7-79-018, Jan. 1979.
253
-------
CONTENT OUTLINE
Course: 413 - Lesson lla
Lecture Title: PROBLEM SESSION vn - WET COLLECTORS*
Page.
of.
10
NOTES
I. Introduction
A. Application of Theory
1. Note role of theoretical calculations in wet collector
design.
2. Note that a knowledgeable environmental engineer should]
be familiar with the calculations and terminology used
in the problems.
B. Tell how you will conduct the problem session.
II. Problem 7.1 - Contact Power Theory Application
page 25 of 413 Student Workbook
A render propose* to use a spray tower on a lime nip
operation to reduce the discharge of solids to the
ataosphere. The inlet loading of the gas stream from the
kiln is 5.0 grains/ft3 and is to be reduced to 0.05 In
order to Beet state regulations. The vendor's design
calls for a water pressure drop of 80 psi and a pressure
drop across the tower of 5.0 in. ffgO. The gas flow rate
la 10,000 ACFM, and a water rate of 50 gal/mln is proposed.
Assume the contact power theory to apply. *
ft. Will the apray tower Beet regulations?
2. what total pressure loss is required to »eet
regulations?
3. Propose a set of operating conditions that will t
•eet the standard. The •saciaun gas and water
pressure drop across the unit are 15 In. 820 and
100 £•!, respectively.
,4. what conclusions can he drawn concerning the use
of a apray tower for 'this application.
This problem and
the solution are
given on pages
5-49 to 5-53 of the|
Course 413 Manual.
The students
probably will not
realize this - if
some do, ask them
to solve the
problem with the
book closed.
254
-------
™~ Solution
CONTENT OUTLINE
Course: 413 _ Leaaon lla
Lecture Title: PROBLEM SESSION vn - WET COLLECTOR«^*-C
\
2 10
Page of
NOTES
For part 1, the collection efficiency !• calculated from
Equation 5.2.8.
•t -In
- n)]
—
P..i> calculated aa follows:
PT ' *G
PG
0.157 AP
p.157 (5)— 0.785
rL
PT
0.583^
0.583 (80) (50/10,000) » 0.233
1.018 hp/1,000 ACTM
Per a liac kiln duct and/or fuma, a • 1.47 and 8 - 1.05
CTabla 5.2.1). Thua.
Mt - 1.47 (1.018) M5 . 1.50
Substitution Into Equation 5.2.6
1.5 - In [1/U -
H - 77.7X
Sine* the regulation* raquire (5.0 - 00.5)/5.0 - 99Z, the
apray tower will not meet the regulation*.
*
For part 2,. calculate PT for n • 0.99.
Ht - In (1/(1 - 0.99)3 • 4.605
4.605 - 1.47 (PT) 1.°5
2.96 hp/1,000 ACFM
255
-------
CONTENT OUTLINE
Course: 413 - Lesson lla
Lecture Title: PROBLEM SESSION vn - WET COLLECTOR
NOTES
For part 3, aaauna the Mziaum gaa and vatar praaaure
drop acres* tha unit to ba 15 in. B20 and 100 pal,
raapactiraly. Caleulata P. and P.
w L.
PG - 2.36
' P. - 0.60
.*• *
Calculata (0^/0^) la gallon* par 1,000 ACT
• Pj/0.583 PJ^ - 0.6 (1,000)70.583 (100)
• 10.3 1*1/1,000 ACFM
Dataradna nav vatar flow rate.
(10.3 gal/1, 000 ACFM) (10,000 ACFM) - 103 gal/mln
For part 4, tha unit has Halted, at baat applicability
for high collection afflclancy oparatlona.
III. Problem 7.2 Contact Power Theory Application
page 26 of 413 Student Workbook
Tha Installation of a vanturl acrubbar la propoaad to -,
raduca tha dlacharge of partlculataa froa an opan-haarth *
•taal fnrnaca oparatlon. Preliminary daalgn Infonation
•nggaata a vatar and^ gaa praaaura drop acroaa tha acrubber
of 5.0 pal and 36 In. IjO, raapectlvaly. A llquld-to-ga*
ratio of 6.0 gal/«ln/l,000 ACFM la uaoally anployad In
tola .application. latiaata tha collactlon afficiancy of
tha propoaad vanturl acrubbar. Aaauma contact- power '
thaory to apply.
256
This problem and
solution is also
given in the 413
Course Manual.
Depending on the
time situation,
have the students
work the problem
alone, or assign
it as homework.
-------
CONTENT OUTLINE
Course: 413 - Lesson lla
Lecture Title: PROBLEM SESSION vn - WET COLLECTOR****
Page
NOTES
Due to tht low water pressure 'drop, it can be assumed
that
with
PG - 0.157 (AP)
Solving for PG gives
PG - 0.157 (36)
- 5.65 hp/1.000 ACTM
The number of transfer units is calculated from
where o and 6 are 1.26 and 0.57, respectively, for this
Industry (Table 5.2.1). Thus,
Mt - 1.26 (5.65) °-57
• 3.38
The collection efficiency can now be calculated.
"t - In CL/(1- U)]
H » 0.966 • 96.6Z
257
-------
CONTENT OUTLINE
Course: 413 - Lesson lla
Lecture Title: PROBLEM SESSION vn - WET COLLECTOR
Page
10
NOTES
IV. Problem 7.3 Cut Power Rule
page 27 of the 413 Student Workbook
What would be the pressure drop required on a Venturi scrubber to
achieve en overall collection efficiency of 99.3X for particulate
matter having a mass-median diameter of 5 ymA with particle size
deviation, o , of 2.0 ym?
P.S. VII-1
1.0
0.1
Is:
c
ce.
z
u:
SL
< n.oi
n.nni
I | I I I I
I I T I I
Pt - exp (-A dja)
n.nni
n.oni
Figure 1
258
-------
CONTENT OUTLINE
Course: 413 - Lesson lla
Lecture Title: PROBLEM SESSION vn - WET COLLECTOR «on*-(
10
Page *L-of.
NOTES
SOLUTION:
Required efficiency n - .993
.'. penetration
Pt = 0.007
From Figure 1., with Pt = .007 and a = 2.0 ym
O
Find da = 0.13 = aerodynamic cut diameter required
dg particle mass mean diameter
da = dg (0.13)
dg is given as 5 ym
.'. da = 5 x .13
= .65 ym
259
If you have not
already done so in
the lecture, it
may be necessary
to review the
definitions of
cut diameter and
mass mean diameter.
-------
CONTENT OUTLINE
Course: 413 - Lesson lla
Lecture Title: PROBLEM SESSION vn - WET COLLECTOR "**
\
flage.
of.
10
NOTES
0.4 0.6
1.0
t
1.0
0.5
0.4
0.3
0.2
0.1
Scrubber power, hp/1,000 tt'/mln
? »«!....
20 30
u
J_
P.S. VII
2
1.0
46 10 20
Gw-phwe prawiri drop, in. HjO
30 40 60
100
Figure 2
From Figure 2 find the pressure drop for a venturi (Curve #4)
Ap * 12" H20
260
After you have
completed problem
Note the
empirical nature
of the theory to
the student. Also
note the similari-
ties to Contact
Power Theory
-------
CONTENT OUTLINE
Course: 413 - Lesson lla
Lecture Title: PROBLEM SESSION vn - WET COLLECTOR*
7*4 Johnstone Equation for Venturi ^...
Page 29 of the 413 Student Workbook
A fly ash laden gas stream is to be clei
10
NOTES
56d -y * venturi acrubber using
"*"" can be
QT
d . (microns)
0.1 -
0.6 -
1.1 -
6.0 -
11.0 -
16.0 -
« 0.10
0.5
1.0
5.0
10.0
15.0
20.0
20.0
* by Weight
0.01
0.21
0.78
13.0
16.0
12.0
8.0
50.0
Make use of the Nukiyama and Tanasawa relationship.
261
NOTE:
This is a classical
problem. Although
the method may not
be used extensively
in the industry, it
gives an estimate
for Venturi's. The
method points out
a number of
important factors
that should be
considered in
control equipment
design. Besides
it's good for the
student's soul.
Assign as homework
don't attempt to
solve it in class.
Review the
following morning.
-------
CONTENT OUTLINE
Course: 413 - Lesson lla
Lecture Title: PROBLEM SESSION vn - WET COLLECTOR
\
of.
10
NOTES
SOLUTION to Problem 7.4
a. Mean droplet diameter
The Nukiyama-Tanasawa correlation can be used for an air-
water system:
d - 16400 + 1.45 [-^
u
= 16400
272 ft/sec
+1.45 (8.5 gal/1000 ft3) im5
d =96.23 microns
b. Inertial impaction number
» - d p u
i P yp
8 yde
2 o
= d (0.7 x 62.4 Ib/ft )(272 ft/sec)
P
8 (1.5 x 10~5 Ib/ft sec)(96.23y)(25400 u/inch)(12 inc
2
- 1.500 d
i P
c. Individual efficiencies, TK
Q,
*»< - 1-exp [-fcr- /?~]
i W/-. 1 •;
1000 ft'
gal
= 1-exp [-(0.2 x gal ) (8.5 1000 ftj
n± = 1-exp [-2.082 dp]
262
-------
H CONTENT OUTLINE /X"
Course: 413 - Lesson lla \^\t^.
Lecture Title: PROBLEM SESSION vn - WET COLLECTOR *0fP
d.
Overall Efficiency
d
(microns)
0.05 0.
0.30 0.
0.80 0.
3.0 0.
8.0 1.
13.0 1.
18.0 1.
80.0 1.
n± x± (%)
0989 0.01
4645 0.21
8109 0.78
9981 13.0
0000 16.0
0000 12.0
0000 8.0
0000 50.0
100.0
"1*1
9.886 x 10~6
9.755 x 10"4
6.325 x 10~3
1.298 x 10"1
0.16
0.12
0.08
0.50
nT = 0.9971
263
!
Pug* 10 „/ 10
NOTES
-------
LESSON PLAN
TOPIC:
COLLECTOR DESIGN
COURSE: 413 - Lesson 12
LESSON TIME: 1 hour
PREPARED BY: DATE:
J. A. Jahnke 2/19/79
LESSON GOAL:
To present the basic types of commercially marketed
particulate wet scrubbers and to describe their basic
modes of operation along with the advantages and
disadvantages associated with each type.
LESSON OBJECTIVES:
The student will be able to:
* Group the different types of wet scrubbers according
to their mechanism of power input.
* Describe the operation of at least 5 of the following
types of scrubbers using appropriate diagrams.
• Plate • Moving bed
• Gas-atomized spray • Performed spray
• Centrifugal • Mechanically aided
• Baffle • Packed
• Self-induced spray
* Discuss the performance characteristics of at least
4 different types of wet collectors, including
pressure drop, liquid to gas ratio and problems
associated with the design.
* List at least 5 source categories where wet collectors
could be suitable applied to control particulate emissions,
* Describe some typical example installations.
* Discuss some typical operation and maintenance problems
associated with wet collectors.
264
-------
SUPPORT MATERIALS
AND EQUIPMENT:
1. slide projector
2. chalkboard
3. 413 Student Manual
SPECIAL INSTRUCTIONS:
REFERENCES:
Best Reference
This lecture is rather descriptive and can get somewhat tedious
to the student. It would be helpful for the instructor to
use slides from his personal collection, if available, of wet
scrubber installations, and to "punch-up" the lecture with
some personal anecdotes.
1. 413 Student Manual
2. Calvert, S., "How to Choose a Particulate
Scrubber", Chemical Engineering, August 29, 1977,
pp. 54-68.
3. Semrau, K. T., "Practical Process Design of
Particulate Scrubbers", Chemical Engineering,
Sept. 26, 1977 pp. 87-91.
4. Strauss, W., Industrial Gas Cleaning (2nd edition)
Pergamon Press, Oxford, Chapter 9, pp. 367-407-
5. Bethea, R. M., Air Pollution Control Technology,
Van Nostrand Reinhold Co., N.Y., 1978.
6. Perry, R. H. and Chilton, E. H., Chemical
Engineers Handbook, Fifth Edition, 1973, McGraw Hill,
N.Y. pp. 20-94 — 20-97
7. Mcllvaine, R.W., "Scrubber Operation and Maintenance
Survey", Paper 79-49.5 presented at 72nd Annual Meeting
of Air Pollution Control Association, Cincinnati , OH,
June 24-29, 1979.
265
-------
AUDIO-VISUAL MATERIALS FOR LESSON 12
Lesson 12 Wet Collector Design
413-12-1 Wet Scrubbers for Particulate Control
413-12-2 Types of Scrubbers
413-12-3 Particulate Scrubber Descriptions
413-12-4 Scrubbers Using Energy from Gas Stream
413-12-5 Sieve Plate Scrubber
413-12-6 Impingement Scrubber
413-12-7 Detail of a Baffle Plate
413-12-8 Detail of a Bubble Cap Plate
413-12-9 Venturi Scrubber ( Peabody )
413-12-10 Swirl Venturi Scrubber
413-12-11 Spray Venturi Scrubber
413-12-12 Venturi Scrubber ( Flexi-Venturi )
413-12-13 Venturi-Rod Scrubber
413-12-14 Swirl Orifice Scrubber
413-12-15 Detail of Orifice Action
413-12-16 Impingement Scrubber (External View)
413-12-17 Scrubbers Using Energy from Liquid Stream
413-12-18 Simple Spray Chamber
413-12-19 Ejector Scrubber
266
-------
413-12-20 Scrubbers Using Energy from Liquid and Gas Streams
413-12-21 Moving Bed Scrubber
413-12-22 Baffle Spray Chamber
413-12-23 Cyclonic Spray Scrubber
413-12-24 Irrigated Cyclone
413-12-25 Scrubbers Using Energy from Mechanically Driven Rotor
413-12-26 Mechanical Scrubber
413-12-27 Vertical Spray Rotor
413-12-28 Scrubbers Using Other Configurations
413-12-29 Packed Tower
413-12-30 Common Tower Packing Materials
413-12-31 Packing Materials
413-12-32 Tellerite Packing
413-12-33 Cross Flow Scrubber
413-12-34 Solid Cone Spray Nozzle/Pin Jet Impingement Spray Nozzle
413-12-35 Fiber Bed Scrubber
413-12-36 Charged Wet Scrubber
413-12-37 Operation/Maintenance for Wet Scrubbers
267
-------
CONTENT OUTLINE
Course: *13- Lesson 12
Lecture Title: WET COLLECTOR DESIGN
Page
NOTES
I. Introduction
A. Many types of designs — will give major types here
B. Because of implications of contact power theory,
i.e. that efficiency is determined by
power dissipation — independent of
scrubber geometry
efficiency is independent of scrubber geometry and
the way the power is applied to the gas-liquid
contacting.
C. Manufacturers and users have turned to a few relatively
simple designs primarily:
Venturis
Orifice Scrubbers
II. Characterization of Scrubber Types
A. Characterize in terms of how energy for gas-liquid
contacting is supplied
1. From the energy of the gas stream
2. From the energy of the liquid stream
3. From a mechanically driven rotor
4. Combination devices
B. Underlying mechanisms are essentially the same
within each grouping. "High energy" scrubbers used
to collect fine particulates are not fundamentally
different from other scrubbers, but
incorporate mechanical arrangements that aide power
input
C. Types of scrubbers will talk about:
1. Energy from gas stream (gas-phase contacting
power)
(a) Plate Scrubbers — sieve
bubble cap
impingement
(b) Gas-atomized spray - venturi
orifice
rod Bank
268
Slide 413-12 -1
413-12"2
Write on chalk
board
NOTE: can also
separate in terms
of energy.
Low energy
< 5" pressure
drop
-------
CONTENT OUTLINE
Course: 413 - Lesson 12
Lecture Title: WET COLLECTOR DESIGN
Page.
of 1L
NOTES
(c) Self-induced spray
(Impingement and entrainment)
(d) Baffle
2. Energy from the liquid stream (liquid-phase contacting
power)
(a) Preformed spray - spray tower cocurrent,
(b) countercurrent
(b) centrifugal - cyclone spray
(c) ejector venturi
3. Energy from mechanically driven rotor (mechanical
contacting power)
(a) Motor driven devices (wet dynamic)
(b) Disintegration scrubber
4. Miscellaneous scrubbers
(a) Wet film collectors - massive packed
fibrous packed
(b) Combination devices
5. Have about 20 types of scrubber designs that want to
talk about. For each, will describe
(a) How it works
(b) Gas velocity
(c) Pressure drop
(d) Efficiency - cut diameter
(e) Liquid to gas ratio
(f) Source categories which scrubber design is most
commonly used.
III. Scrubbers ( Gas - Phase Contacting)
A. Plate Scrubbers
1. Sieve Plate
(a) How it works: vertical tower with one or more
plates (trays) mounted transversly inside —
liquid flows over plates gas contacts liquid
through perforations - 600-3000 holes/ft2 —
holes not aligned.
269
ligh energy <15"
Example - low-spray
towers
Medium-centrifugal
atomized-impinge-
ment packed bed
High - venturi
413-12-3
413-12-4
413-12-5
-------
CONTENT OUTLINE
Course: 413 - Lesson 12
Lecture Title: WET COLLECTOR DESIGN
Page.
of.
10
NOTES
00 Gas velocity range
(c) Pressure drop
(d) Efficiency - cut diameter - -\d.O ym for 1/8"
diameter holes
(e) Liquid to gas ratio
(f) Source category usage
Drying processes, nonferrous metals
2. Impingement Plate
(a) How it works - impingement baffles placed above each
perforation on a sieve plate. Bubble caps and
other configurations. Some have moveable caps for
high turn-down ratios.
(b) Gas velocity range - 15-20 ft/sec through each
orifice is common.
(c) Pressure drop - 1 to 8" H-O, 1.5" H20 common
(d) Efficiency - cut diameter - 2*3 ym cut diameter,
90*98% efficiency for 1 ym particle /plate.
'(e) Liquid to gas ratio - 3 •> 15 gal H20/1000 ft3 gas
5 psig water pressure common', some can go to
50,000 ACFM
(f) Usage - drying processes, cupolas, kilns, fertilizer
Gas atomized spray scrubbers
1. Venturi
(a) How it works - contraction to increase gas veloci
introduce liquid at throat or along the walls of
the inlet to the throat. Gas shears off water from
nozzles or walls and atomizes.
(b) Gas velocity - 12,000 24000 ft/min through the
throat
(c) pressure drop - 6 +20 +60 -»-100"
(25-30" is common)
(d) Efficiency - cut diameter
100% for !•> 2 ym at 10" H20
99% for.3 - .4 at 60" H20
Cut diameter .05 - .1" at 60 to 100" H-0
L 3
(e) Liquid to gas ratio - 3 - 10 gal/1000 ft
Droplet sizes usually about 10 ym in diameter
270
413-12-6
413-12-7
413-12-8
413-12-9
413-12-10
413-12-11
See pp 5-32 & 5-33
of Manual for
efficiency curves
-------
Venturi Scrubbers
TABLE 1
TYPICAL PERFORMANCE DATA FOR VENTURI SCRUBBER1
Source of Gas
IRON 1 STEEL INDUSTRY
Ciay Iron Cupola
OiyRtm Steel Convene*
Steel Upun Hcjrtli 1 jrrui.-r '.Si i.i|n
Steel Ojicii Hearth FJII«C.
(Oi)gen Lanced)
Bhut Furnace (Iron)
Electric Furnace
Electric Furnace
Rotary Kiln— Iron Reduction
Crushing t Screening
CHEMICAL INDUSTRY
Acid-Huwdinod SO,
(a) Scrub with Water
r
llUl OliUl!
iron & /nit D>inV
lion Onue
Iron Ore t Cake Dust
Ferro-Manganese Fume
Ferro-Silicon Dust
Von, Carbon
Taconite Iron Ore Dust
rUO. Mill
IWO. Mist
H.SO. Mist
IWO, Mist
Amir* Fog
Tar t Acetic Acid
TWrMCI Fumes
Detergents, Fume t Odor
Furfural Oust
WO. Mist
lead Compounds
Lead t Tin Compounds
Aluminum Chloride
Zinc t Lead Oxida Dust*
Zinc Oxide Fume
Lime Dust
Soda Fume
limestone t Rock Dust
Cement Dust
Catalyst Dust
(WO. Mut
Oil Fumes
Ammonium Chloride Fumes
Fluorine Compounds
Lime Dust
Soda Fume
Salt Cake
HCI Fumes
Fly Ash
Sodium Oiloe Fumes
pproximati
ize Range
(Microns)
110
5?
.08-1
5-lr
.520
.1-1
.1-1
.5-50
.5-100
_
_
_
_
«
—
—
3-1
.1-1
—
.1-1
!l-.9
.1-1
JS-.5
1-50
J-l
1-50
5-55
3-50
.05-1
~"
.1-50
.1-2
1-3
J-.l
» Load
(Grain
Inlet
i 'i
810
.5-1.5
1-6
3-24
10-12
1-5
3-10
5-25
303*
406*
136*
198*
756"
25*
1080*
1-5
MS
192'
2-6
1-2
3-5
1-5
14
5-10
7-5
5-15
1-2
.OR
136*
756'
.1-5
309*
MO
2-5
44
25*
1-2
.5-1
ing
s/ cf)
Exit
.05,15
05-08
03 Ob
.01-.07
.008- .05
.0+-.08
.1 J
.1-J
.005-.01
1.7*
2J'
3J*
2.0*
7J*
2JJ*
58.0*
.05-.!
IK-M
33'
JK-.K
.12
.02-.05
.05-.1
.\-S
.05-.15
X1-.05
J5-.15
.05-.!
OK
3J*
tO"
M
5.5'
J05-.15
J1-.05
.4-i
2J*
.05-.08
.02
Average
Removal
Efficiency (%)
95
98.3
35
99
99
99
92
99
99.9
99.4
99.3
97.5
99
98.9
90+
95
95
95
95+
98+
99
91
95
98
95
99+
99
•98+
97+
95+
975
98+
85+
98+
99+
99
90
90+
98
98
Note: Tke egtdimeiei thown O*»M «r» avengt value* for a particular
plant tr group of iiatallationt oprnting under • ipemfe tft of condition*.
' Milligrams per cubit ft
*Chemico Gas Scrubbers for Industry, Bulletin M-104, Chemical
Construction Corp., 525 West 43 St., NY, NY.
271
-------
CONTENT OUTLINE
Course: 413 - Lesson 12
Lecture Title; WET COLLECTOR DESIGN
PageJL-.of.J2-
NOTES
(f) Source category usuage - see table attached
in general - pulverized coal, abrasives, rotary
kilns, foundries, flue gas, cupola gas, fertilizers
lime kilns, etc.
2. Orifice (variable float Venturis)
Can adjust pressure drop and scrubber efficiency
3. Rod bank
Parallel rods - can rotate - spray water on rods -
cocurrent with gas flow — a series of parallel venturd
throats Ap = 2" -»• 150" H20, 90 •* 600,000 ACFM units.
L/G = 2 -»- 15 gal/1000 ft3
C. Self-Induced Spray - Impingement and Entrainment - Also
called orifice wet scrubber (in manual)
1. How it works: Gas impinges on and skims over liquid
in turn, atomizes the liquid
2. Gas velocity - 50 ft/sec gives droplets 300 to 400 urn
in size,can go to 600 ft/sec for submicron size
particles.
3. Pressure drop - 3 •*• 10" (drop size - 60 pm)
4. Efficiency - cut diameter - .8 to 1 pm at 3 -> 6" H20,
can handle high dust concentrations
5. Liquid to gas ratio - get water recirculation, so have
around 1-3 gal/1000 ft3
6. Source Category Usage
calcining operations, combustion sources
coal mining, ore mining, explosive dusts, incineration.
IV. Scrubber (Liquid-Phase Contacting) or Preformed Spray Scrubber
A. Spray towers
1. How it works:
Most common low-energy scrubber. Collects
particles on liquid droplets which are preformed.
Properties of droplets are determined by:
• configuration of the nozzle
• liquid atomized
• pressure to the nozzle
272
pick out examples
from table
413-12-12
413-12-13
- 413-12-14
413-12-15
413-12-16
413-12-17
413-12-18
-------
CONTENT OUTLINE
Course: 413 - Lesson 12
Lecture Title: WET COLLECTOR DESIGN
Page 5 of 1D_
NOTES
In vertical towers, the terminal settling velocity
corresponds to the relative velocity between
particles and the gas.
In practice — verticle gas velocity 2-5 fps for
good collection, need high V
3TG.L •
small size drops
conditions, however, are incompatible:
small drops •»• low free-falling velocity
.". have an optimum droplet size for a given
particle size for maximum collection efficiency
Maximum efficiency for particles <5y is at water
droplet size ^ 80y
2. Gas velocity - 1 -»• 5 ft/sec
3. Pressure drop - .5 -»• 2" H20
4. Efficiency - low efficiency 70% > 5 um
5. Liquid to gas ratio - .5 ->• 8 gal/1000 ft
can handle large gas volumes - often used as a
pre-qooler
6. Usage - dust cleaning, electroplating, phosphate
fertilizer, kraft paper, smoke abatement, pre-
cooler, blast furnace gas.
B. Ejector Venturi(jet venturi)
1. How it works: Water pumped through a nozzle at high
velocity. Dirty gas accelerated by the action of
the jet. Causes considerable turbulence and a
lowering of the pressure - development of a mist.
2. Gas velocity - 15-50 ft/sec
3. Pressure Drop - 1-3" H20
4. Efficiency - cut diameter ^ .8 urn
5. Liquid to gas ratio - 50-100 gal/1000 ft
6. Usage - Fertilizer manufacture, odor control,
smoke control.
273
Different designs
co-current
countercurrent
cross-flow
Note: could also
use heated water
in jet. page 5-28
of Manual
413-12-19
-------
CONTENT OUTLINE
Course: 413 _ Lesson 12
Lecture Title: WET COLLECTOR DESIGN
Page
NOTES
V. Scrubbers (gas phase - liquid phase contacting)
1. Moving bed scrubbers - (also turbulent contact
absorbers - TCA)
a. How it works - have zone of movable packing where
gas and liquid can mix packing may be 1%" diameter
polyethylene or polypropylene spheres may use
several stages.
b. Gas velocity
c. Pressure drop - 3 •> 5" H-0
d. Efficiency - 99% for particles down to 2 um
e. Liquid to gas ratio
f. Source category usage - Kraft paper, basic oxygen
steel, fertilizer, aluminum ore reduction
aluminum refineries, asphalt manufacturing.
2. Baffle Scrubber and Secondary flow scrubbers
a. How it works — change direction of flow by solid
surfaces, louvres, zig-zags, etc. may use sprays
or wetted walls and baffles to remove particulates.
b. Gas velocity
c. Pressure drop - low
d. Efficiency - cut diameter - cut diameter
5-10 ym, low for fine
particles
e. Liquid to gas ratio
f. Source category Usage
Coke quenching, Kraft paper manufacture, plating,
useful as precleaners and entrainment separators.
3. Centrifugal Collectors
a. How it works: Usually cylindrical in shape
impart a spinning motion to the gas passing through
them. Spinning comes from tangential introduction
direction of gas stream against stationary swirl
vanes. Particle collection operates by centrifugal
deposition caused by the rotating gas stream
274
413-12-20
NOTE: may use
sprays so have
combination of
processes both gas
phase and liquid
phase contacting
413-12-21
Energy of removal
can come from both
gas phase and liqui
phase
413-12-22
ross between a spra
chamber and a cycle
413-12-23
413-12-24
-------
CONTENT OUTLINE
Course: 413 - Lesson 12
Lecture Title: WET COLLECTOR DESIGN
Page.
NOTES
b. Gas velocity - gas velcities 200 -»• 500 ft/sec
c. Pressure drop - 1.5 to 3" H,0 are typical
d. Efficiency - cut-diamter - cut diameter generally
2 to 3 ym. 90% efficient for particles <5 wm
e. Liquid to gas ratio - 2 to 10 gal/1000 ft capacity
•v 50,000 ACFM/unit
f. Source category Useage
Spray dryers, calciners, crushers, classifiers,
fluid bed processors, kraft papers, fly ash.
VI. Scrubbers (Mechanical Contacting Power)
A. Incorporate a motor-driven device between the inlet and
the outlet of the scrubber body
Example - Disintegrator Scrubber
1. How it works: uses a submerged, motor-driven impelle
to atomize liquid into small drops. Drops spin off
the impeller across the gas stream, collecting
particles on the way.
2. Gas Velocity
3. Pressure Drop - <1"
4. Efficiency - ^ 1 pm at 90% efficiency
5. Liquid to gas ratio
6. Usage - blast furnace gas
Polycon cyclone
spray
Irrigated cyclone
cyclonic - internal
spray - outer wall
Multiwash scrubber
(vanes)
centripetal vortex
contactor
(p. 5-34 of manual)
413-12-25
413-12-26
413-12-27
275
-------
CONTENT OUTLINE
Course: 413 - Lesson 12
Lecture Title: WET COLLECTOR DESIGN
Page-*—of-™-
NOTES
VII.
Another example: Submerged Rotor (page 5-39 of Manual)
Droplets mechanically Induced 4-5 gal/1000 ft - low
liquid levels small in size, but get abrasion and errosi^n
Usage - iron foundry, cupolas chemical fume control,
paint spray.
Miscellaneous Scrubbers
A. Wet Film Collectors
1. Massive Packed
a. How it works: get centrifugal deposition
through flow channels - have several designs:
co-current, countercurrent , crossflow.
Gas velocity
foot
b.
c.
Pressure drop - ^ 4" H20(or .5" H20 per
of packing) may be 2-10" overall
packing) may
d. Efficiency - cut diameter of 1.5 urn with 1" H,0
fieri saddles - the smaller the packing, the
higher the efficiency.
3
e. Liquid to gas ratio - 2-5 gal/1000 ft gas
rates ^ 35,000 CFM or less
f. Usage - More often for gases
2. Fibrous Packed
a. How it works: Plastic, glass, and steel fibers
97-99% void space - impaction is the dominant
mechanism - efficiency increases as fiber gets
smaller and gas velocity increases.
b. Gas velocity
c. Pressure drop * 4" H^O
d. Efficiency - cut diameter 1-2 pm for .01"
diameter fibers
e. Usage -
3. Flooded Bed
Operated co-current - dirty gas and scrubber liquid
enter from bottom - sprays flood bottom of packed
layer. Upward gas velocity keeps bed expanded to
prevent plugging. Cut diameter of 2 - 3 pm
with pressure drops as high as 10-15" H^O
276
413-12-28
Note: Bethea has
good summary p. 281
413-12-29
413-12-30
413-12-31
413-12-32
413-12-33
413-12-34
413-12-35
-------
CONTENT OUTLINE
Course: 413 - Lesson 12
Lecture Title: WET COLLECTOR DESIGN
10
NOTES
B. Combination Categories
1. Use a combination of scrubber types. Maintenance
problems are the same as those of the individual
types which they are made up of.
2. Examples
a. Foam Scrubbers
Use surfactants to encapsulate the airstream into
bubbles.
b. Steam Assisted Scrubbers
Steam or high-temperature water is driven from
nozzle at high speed
c. Charged Wet Scrubbers
combine advantages of scrubbers and precipitators
d. Condensation Scrubbers
Condense droplets from the gas stream
VIII. Operation and Maintenance for Scrubbers
A. The scrubber situation is considerably more complex
than the fabric filter or precipitator situation.
This is because of the wide variety of scrubber design
Maintenance characteristics are considerably different
for each type. Therefore, it is not meaningful to
generalize on scrubber maintenance problems but only
to draw conclusions about the maintenance characterist
of a specific type.
Mechanically-aided scrubbers are likely to have high
maintenance because of the more complex design and
moving parts. Venturi scrubbers are also vulnerable
because of the high velocity in the venturi throat.
Spray towers are among the most maintenance-free
scrubber designs and for this reason are finding
increasing use in flue gas desulfurization.
413-12-36
413-12-37
cs
277
-------
CONTENT OUTLINE
Course: 413 - Lesson 12
Lecture Title: WET COLLECTOR DESIGN
Page -10- of 10-
NOTES
B. Specific Operations and Maintenance problems for gas-
atomized spray scrubbers.
Among the most widely used of the gas atomized types is tjhe
venturi scrubber.
1. The velocities through venturi throats may be as
high as 40,000 fpm. At these velocities, the wear
rates are quite high in the throat section unless
abrasion resistant construction materials are used.
2. Throats are often lined with silicon carbide brick
to extend throat life. Replaceable wear liners are
another feature that prevents deterioration of the
throat section. High wear occurs in areas downstream
of the acceleration zone.
3. The distance from the throat through which high wear
potential exists is related to the throat diameter.
In larger Venturis, erosion potential exists to a
distance farther downstream.
4. Abrasion can be reduced if large particulate is re-
moved prior to high gas acceleration. Quench
chambers can serve this function while also humidi-
fying the gas. An orifice supplied with 1-2 gallons
per 1000 cfm and operating at 2" pressure drop will
perform both these functions.
5. Abrasion is reduced downstream from the throat by use
of the flooded elbow. The gas stream impacts on
a reservoir of liquor, thereby effectively reducing
velocity without abrasion of the shell. This design
is shown in Figure 6. The flow is downward through
the throat with a right angle turn at the flooded
elbow.
6. Nozzles for liquor distribution give better
efficiency, but can cause maintenance headaches.
Liquid introduction through weirs offers maintenance
advantages with some sacrifice in efficiency. When
heavy slurries are recirculated, such as process
liquor in a pulpmill recovery furnace, it is
necessary to use the open-type liquor introduction.
7. Fan erosion becomes severe as the pressure drop
requirements for venturi scrubbers are increased.
A common problem is fan imbalance caused by even the
slightest buildup of material on the fan blades
rotating at very high rpm (required to develop the
high pressures).
278
-------
279
-------
280
FIBER Bf O S< *t >BBfR
-------
LESSON PLAN
TOPIC:OPERATION, MAINTENANCE AND
INSPECTION OF AIR POLLUTION
CONTROL EQUIPMENT
COURSE; 413 - Lesson 13
LESSON TIME: 1 hour . .,„
PREPARED BY: DATE: 4/79
David S. Beachler
LECTURE GOAL:
Describe the need for an operation/maintenance/and inspection
program for Particulate Emission Control equipment and describe
the benefits gained by initiating such a program.
LECTURE OBJECTIVES;
At the end of the lesson, the student should be able to:
• Define what an operation/maintenance and inspection
program is and list three major reasons why such a program
should be implemented.
• Recognize the Illinois Environmental Protection Agency
proposed rule dealing with 0/M/I programs.
• List three ways an 0/M/I program can be cost effective.
• Describe the basic steps of an 0/M/I program for a fabric
filter collector and identify the important features of
the program.
• Identify two typical inspection reporting forms for fabric
filter collectors.
STUDENT PREREQUISITE SKILLS:
Ability to understand basic principles of Physical Science
LEVEL OF INSTRUCTION;
Intermediate
INTENDED STUDENT PROFESSIONAL BACKGROUND:
Engineering or Physical Science
SUPPORT MATERIALS AND EQUIPMENT;
1. Slide Projector
2. Overhead Projector
3. Chalkboard
4. 413 Student Manual
281
-------
REFERENCES:
1. "Handbook for the Operation and Maintenance of Air Pollution
Control Equipment", edited by Frank L. Cross, Jr., and Howard
E. Hesketh, Technomic Publishing Co. Inc., Westport, Conn. 1975.
2. "Training Personnel to Operate and Maintain Air Pollution
Control Equipment", by Frank L. Cross, Jr. and Frank Cross, for
presentation at the 71st Annual Meeting of the Air Pollution
Control Association, 78-11.4, Pittsburgh, PA. 1978.
3. "Industrial Pollution Control Handbook", edited by Herbert F. Lund,
chapter 22. McGraw-Hill Book Company, New York, 1971.
4. "Operation and Maintenance of Particulate Control Devices on Coal-Fired
Utility Boilers", EPA-600/2-77-129, July 1977.
5. "Tips and Techniques on Air Pollution Control Equipment 0 & M", by
David B. Rimberg, Pollution Engineering, March 1978, pp. 32-35.
6. "ESP Operation and Maintenance, by Frank L. Cross, Jr., Pollution
Engineering, March, 1978, pp. 37-39.
282
-------
AUDIO-VISUAL MATERIALS FOR LESSON 13
Lesson 13
413-13-1
413-13-2
413-13-3
413-13-4
413-13-5
413-13-6
413-13-7
413-13-8
413-13-9
413-13-10
413-13-11
413-13-12
413-13-13
413-13-14
413-13-15
413-13-16
413-13-17
413-13-18
413-13-19
413-13-20
413-13-21
413-13-22
413-13-23
413-13-24
413-13-25
413-13-26
413-13-27
413-13-28
413-13-29
413-13-30
413-13-31
Operation, Maintenance, and Inspection of Control Equipment
Historical stages of air pollution control
Definition of an operation maintenance and inspection program (0/M/I)
Why 0/M/I?~legal requirements
Proposed rule for 0/M/I
Why 0/M/I?—insure NAAQS and SIP
Why 0/M/I?—in-plant benefits
In-plant benefits of 0/M/I
Cost effectiveness—0/M/I justification
Training
Administration
Inspection
Preventive maintenance
Corrective action
Spare parts
Baghouse—live shot
Hoppers
Screw conveyers
Pressure drop manometer—bad location
Manometer located in control room—good location
Bag maintenance—individual bag replacement
Module—complete bag change out
Complete bag compartment change out
Complete bag compartment change out
View of empty frame
Complete bag compartment change out
Complete bag compartment change out
Complete bag compartment change out
Fluorescent powder and portable black light for bag leak inspection
Inspecting for leaks with black light
Inspecting for cracks in baghouse cell plate
Opacity monitor use for baghouse leak determination
283
-------
CONTENT OUTLINE
Cot/rse:413 - Lesson 13
Lecture Title: O/M/I
of.
NOTES
1940
to
1950
1950
to
1970
I. References
II. Introduction
The national air pollution control program can be thought
of as having gone through three functional stages of
development over the past 30 years.
Each of the steps in the figure represented an initiation
period for a stepped up effort in this activity, which is
continuously on-going.
A. Monitoring Stage - quantified the air pollution
problem through
Detection of Pollutants
1. Types of material
2. concentration - monitored ambient air
3. sources of emissions - identification
4. evaluating effects - then setting of standards
Once regulations and standards are established,
start control of emissions through intiation
Handout copy to
students
Slide/413-13-1
IOTE: This stage wel
underway but we're
still setting NSPS
B. Installation of Equipment
of Emissions
1. planning
2. conceptual engineering
3. construction
4. startup
- with resulting control
period of
improving
air qualitjy
Around
1970
to
Present
C.
To accomplish more improvement in air quality in an
economically and environmentally acceptable manner.
Must increase consideration of control equipment.
Operation and Maintenance - with resulting continued
surveillance
1. minimize shutdown
2. stop malfunctions
3. Maximize production
4. Avoid enforcement actio
iction^
further improve air
quality and necessary tc
meet SIP requirements &
guard against malfunctic ns
and process shutdowns
III. O/M/I Program
A. Definition: O/M/I Program is a program set up for
personnel interested in insuring proper and
efficient performance of the control equipment.
B. An O/M/I program would involve
1.
2.
3.
4.
5.
6.
Training of personnel
Administration activities
Inspection schedule
Preventive Maintenance schedule
Corrective action procedures
Spare parts and essential equipment
284
Slide: 413-13-2
-------
CONTENT OUTLINE
Course: 413 ~ Lesson 13
Lecture Title: O/M/I
Page.
NOTES
IV. Reasons for Implementing an O/M/I Program
A. Suggested in documents, proposed revision to state and
Federal regulations, and the probability of being
written into the regulations.
Slide/ 413-13-3
1.
2.
EPA's Division of Stationary Sources Enforcement and
the office of Air Quality, Planning and Standards are
looking into the feasibility of initiating O/M/I programs.
B.
Illinois (EPA) State Agency
Proposed revision to rule 103b — setting up an
0/M Program that includes:
(a) complete preventive maintenance schedule
(b) inspection—persons responsible
equipment inspected, frequency of inspections
(c) replacement parts — on hand
(d) monitoring variables—surveillance procedures
(e) corrective action procedures
Needed to insure meeting NAAQS and SIPs
1. Without proper O/M/I, control equipment installed
on major facilities will not meet SIP requirements
and will continue to have excessive malfunctions
and process shutdown. Equipment leaks are signifi-
cant sources in areas where oxidant NAAQS are likely
to be violated.
2. Compliance with State and Federal Regulations
State programs set up a phase to achieve compliance
by conducting:
(a) emission inventory
(b) determining regulations
(c) selecting and installing proper control
equipment
(d) compliance test
(e) installing and certifying continuous monitors
(f) setting up ambient monitoring network
with the need of an O/M/I program to insure compliai
Examples of Impact on Air Quality
(a) Analysis by EPA Region IV and State of Alabama
& local agencies indicate that Mobile and
Jefferson counties are not meeting ambient air
quality TSP emissions — commissioned study by
PEDCO to Procure information on specific sites &
to recommend RACT.
(b) Through application of RACT on cement plants and
foundauies of $1,217,000 emissions reduced 46%.
Much of suggested reduction in emissions related
to the operation and maintenance of existing air
pollution control systems and installation of
simple devices on fugitive sources that have been
partially or not controlled in the past.
285
Slide/ 413-13-4
tote: This rule doe
lot provide the
igency with an enfor
:ement provision—
Industry must only
srovide information
(asked in rule).
Slide/ 413-13-5
ce
-------
CONTENT OUTLINE
Course: 413 ~ Lesson 13
Lecture Title: O/M/I
Page J—of.
NOTES
c.
• duct work
• broken bags
• water sprays for storage piles
and road dust
Benefits - that can be realized by an Industry from
an O/M/I program.
Slide: 413'13-6
413-13-7
a. Reduction of operating costs through reduction
of power, fuel, services, equipment replacement
and parts inventory.
b. Compliance with emission regulations and standards
c. Extension of operating life of control equip-
ment.
d. Continued recovery of valuable products
e. Early detection of malfunctions
f. Reduction and prevention of equipment
failures
g. Prevention of damage to equipment
h. Sustained reduction in emissions
1. Safety
D. Examples of lost benefits due to insufficient 0 & M
1. Poor equipment operation more detrimental to efficiency
than poor operation of other process equipment.
i.e., 10% plugging of spray nozzle in absorption unit
might cause 40% reduction in collection efficiency.
2. On a large power plant scrubber which cost
approximately 102 million, improper 0/M of mist
eliminators, and incorrect lime-acid balance
caused:
a. film CaSO, to line flue
b. fallout -after unit was started up from a routine inspection
c. flue lining to disintegrate which caused shutdown,
of #1 unit .*. no electricity, replacement of
flue lining $$, denial of operating permit,
alienation with neighbors.
E.
Cost Effectiveness
1. Justification of an OM & I Program.
a. Initial investment—millions of $ —100 million
for control equipment — S0« scrubber for a power
plant.
b. Process control - better
c. Material recovery
286
Slide: 413r-13-8
-------
CONTENT OUTLINE
Course: 413 - Lesson 13
Lecture Title: O/M/I
)
Page
of.
NOTES
v.
Outline Program -- Several key factors will ultimately
determine the effectiveness of the program.
A. Training of Personnel
1. Who; a. Supervisors
b. Operators (equipment
c. Maintenance - electrical
- mechanical
- technician
d. Agency enforcement personnel
2. What Type
a. Short course - given by vendor, agency
b. on- the- job
c. classroom - Trade School Educ.
d. Self-instruction
e. May be a variation of all above
3. How long or what depth is needed
a. Estimates have been made range from
40 -50 manhours for a full-time
technician.
b. One way to eliminate inhouse-training
of personnel is to contract services
of equipment vendor or a company that
specializes in maintenance of control
equipment. Major disadvantage here is
response time.
Administration Activities • — Support activities which
include :
B.
C.
Slide/ 413-13-9
1. Logging of equipment-Equipment in use
2. Scheduling inspections
3. Reporting data - equipment breaks
4. Scheduling specific corrective repairs when
breakdown occurs.
Inspection Schedule— prepared for by administration
support groups, should Include:
1. Who does the inspection—technician, electrical
engineer, mechanical engineer, maintenance personnel
2. What kind of equipment needs to be inspected —
what areas — valves, nuts, bolts, etc.
3. What to look for — Corrosion, excessive wear,
erosion of parts, frayed wires or bad electrical
connections , etc.
287
Slide/
-13-10
Slide/ 413^13-11
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CONTENT OUTLINE
Course: 4^3 - Lesson 13
Lecture Title: O/M/I
NOTES
Preventive Maintenance
steps to include:
a schedule listing several
Slide 413-13-12
a.
Slide 413-13-13
Slide 413-13-14
How often? —»• vendor of control equipment could
give preventive maintenance schedules & procedures
b. Previous experience with equipment
5. Corrective Action Procedures — Repair of broken or
malfunctioning equipment
a. vendor experience — what type of action is needed
b. Books — Repair Manual—sectioned off for various
equipment sections—electrical, mechanical parts
etc.
c. Keep repair manuals in an appropriate place —
near or around the area in a protective cover.
6. Spare Parts — should keep on hand:
a. Parts that will most likely wear and need
replacing frequently should be inventoried •—
determination of such should be recommended by
vendor or from past experience.
b. Good maintenance (preventive) will help keep the
inventory of spare parts down — One will know
and have a better feel for what parts are really
necessary.
VI. Specific example of the type of O/M/I that would be done
on a typical baghouse in a steel mill or (power plant for
that matter) .
A. Compliance and Monitoring initiated by: Illinois
proposed revision to rule 103 - setting up an 0/M program including:
1. Complete maintenance schedule
2. Inspection (persons responsible, equipment
inspected, frequency of inspections)
3. Replacement parts (list of parts on hand)
4. Monitoring variables - (surveillance procedures)
5. Corrective action procedures
B. Routine Operation (of a system served by a baghouse)
1. Initial Start-up
a. conduct a pre-start-up inspection, not only
baghouse, but entire process and exhaust
system such as fans, motor rotation, electrical
functions, etc.
288
Slide: 413-13-15
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CONTENT OUTLINE
Course: 413 - Lesson 13
Lecture Title: O/M/I
3SK
Page J?—of.
NOTES
b. Inspect baghouse for debris -- nuts, welding rods,
garbage
c. Check baghouse for leaks (interior) easy way to walk
into baghouse, close doors, and look for STARS (ligpt coming in)
d. Check bolts, nuts and tighten bag clamps.
e. Bag tensioning system - gaskets
f. Make sure all timing devices are set properly
g. Check screw conveyors —- hoppers
C. Routine Start-up and Shutdown (of the baghouse)
1. Preheat the baghouse to raise inside temperature above
the dewpoint of gases to prevent corrosion —
by heaters, or some fuel that wouldn't cause dust or
acid dewpoint (gas or oil when bringing on line for
coal use)
2. Routine shutdown — keep fan running after process
shutdown to purge corrosive gases from system -- also
want clean bags enough — so that cake won't be allowed
to set up. Moisture' could set up like concrete.
lide 413-13-16
413-13-17
D. Routine Monitoring (of a baghouse)
*Two major indicators of baghouse performance
1. pressure drop
2. Emission opacity (as an index of efficiency)
* Pressure drop - with manometer or magnehelic gage
should be in a readable place
* Collection efficiency can be indicated by use of
continuous opacity monitors
E. Routine Maintenance
1. Keep record of all inspection and maintenance
2. Inspection intervals - recommended by vendor or past
experience
F. Bag Maintenance
Singularly most important routine maintenance item on
properly operating baghouse.
1. Bag life ranges from a few months to 5 or more years.
2. Bag maintenance divided into 2 categories:
a. location and repair of individual bags - can be
tedious
b. individual bag pullout
c. complete bag change-out of entire unit
289
Slide: 413-13-18
NOTE: This is not a
good location for
nanometer.
lide: 413-13-19
TOTE: Manometer in
control room, good
readable spot.
NOTE: Explain look-
ing through bags
Slide: 413-13-20
Slide: 413-13-21
thru 413-13-27
NOTE: Complete unit
change out (7 slide
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CONTENT OUTLINE
Course:413 - Lesson 13
Lecture Title: O/M/I
Page
NOTES
3. Can check for bag leaks by:
a. hunt for hole Itself
b. hunt for accumulation of dust which can be related
to a nearby hole
c. Use some type of detecting device, (such as floresceit dust, etc.)
VII.
*Newest and most effective technique is to inject a
quantity of florescent or phoshorescent dust with baghoust
and then inspect the clean plenum with black light. The
dust from even very small leaks is easily visible as it
glows under the black light.
A. Inside bag collectors - necessary to scan the entire
length of the bag to pinpoint the failure.
B. Outside units - florescent powder will be drawn
through the hole in the bag and will be visible on
the venturi or around the blow pipe around the ventrui.
C. Can also detect broken welds in baghouse tube sheet,
cellplate, or housing.
D. Broken Bags should be replaced when found! Broken
bags can move about ripping adjacent ones. "Domino
Effect". Recently however, it has been found that new
ones in vicinity of old ones will be forced to take
higher % of air (least resistance)
E. Sometimes best to just tie off or plug up (hole) the
cell plate than to replace bag due to maintenance cost.
Slide/ 413-13-28
s
Slide/ 413-13-29
Slide/ 413-13-30
VIII. Typical Monitoring and Indicating Devices should include:
A. Pilot lights to show that the baghouse is operating
properly. Pilot lights show what motors are operating,
which compartments are off or on-line, which rows of
bags are being pulsed, frequency of pulsing, etc.
B. Opacity meters which can show even a slight drop in
filtering efficiency which would not be detectable by
the human eye.
C. Pressure drop indicators such as magnehelic gages or
manometers to show any change in pressure drop during
operation. Recorders may also be used for a permanent
record of pressure drop.
D. Temperature indicators and/or records to show when
maximum operating temperatures are reached.
E. Gas flow meters indicate the amount of air moving
through the system.
290
[for a baghouse)
Slide/ 413-13-31
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CONTENT OUTLINE
Course:413 - Lesson 13
Lecture Title: O/M/I
o
Page *-ofJL
NOTES
F. Corrosion chips can be placed at strategic points in
the dirty air stream. These should be made of the
same metal as the baghouse and should be inspected
and measured regularly to predict if corrosion could
become a serious problem.
IX. Trouble Shooting Charts
A. Can be obtained from vendors ~ should make sure the
operation and service manuals are "in hand" before
paying last 10% of contract.
B. Can also get trouble shooting charts from Q/M short
course.
X. Reporting
A. Typical inspect report sheets
B. Standard
XI. Mention O/M/I short courses offered by:
A. EPA - ERIC
B. Consultant at a University continuing education program
XII. REVIEW
The past hour we have talked abou the following subjects:
• Defined what an O/M/I program is
• Stated 3 reasons why an O/M/I program should be
implemented
• Illinois Environmental Protection Agency - Rule 103b
• O/M/I Program - can be cost effective
• The basic steps an O/M/I program for a baghouse would
include.
291
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292
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293
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LESSON PLAN
TOPIC: ESTIMATING THE COST OF
CONTROL EQUIPMENT
COURSE; 413 - Lesson 14
LESSON TIME: 30 minutes
PREPARED BY: DATE:
G. J. Aldina
LESSON GOAL:
Provide students with methods of estimating the
cost of control equipment
LESSON OBJECTIVES:
The student should be able to:
1. List the major economic factors to be considered
in selecting particulate control equipment
2. Estimate the installation cost/ACFM of some
types of control equipment
3. Recall generalized formulas for estimating yearly
maintenance costs of various control devices
There are many references available for estimating control equipment costs.
These may have a confidence limit ± 200% depending whether estimates include
auxiliary equipment costs, installation and transporation, site preparation,
and a host of other possible hidden costs. The EPA recently did a study on
equipment costs, EPA-450/3-76-014, May 1976 exerpts of which have been printed
in the APCA journal 8/78 - 12/78 which break out actual costs of control
systems according to materials, auxiliary equipment, installation, and
operation. This is a very good and extensive study and if you need very
close estimates it is a good resource.
Our discussion will be geared more toward a "ball park" estimate of installation
and operating costs. In the time alloted this is the best we can attempt.
294
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CONTENT OUTLINE
/
Page.
of.
Course: 413 - Lesson 14
Lecture Title:
COSTS
NOTES
I. Economic Factors
A. Need to select the optimum system for a particular
application
1. Choice Is predicated on source parameters
(a) Effluent characteristics
(1) Temperature
(2) H.O content
(3) Volumetric flow rate
(b) Pollutant characteristics
(1) Types in the effluent - SO , SO ,
particulates
(2) Particle size, properties, electrical
conductivity
2. Site limitations
(a) Space at the plant
(b) Waste disposal problems
B. Operating and maintenance costs of the system
1. Yearly costs
2. Useful life of the machine
C. Conversion of the equipment for possible future
applications
D. Process changes and effects
1. Expansion or contraction practical in the future
2. Will special modifications be necessary
II. General cost estimates of installed equipment
A. Baghouse - greater than 99% efficiency
1. 250°F -$1.35- 2.70/ACFM
2. 500°F - $2.70 - 5.40/ACFM
B. Cyclones
1. Fly ash (55-95% efficiency) - $0.20 - 0.40/ACFM
2. General (65 - 95% efficiency) - $0.80 - $1.04/ACFM
295
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CONTENT OUTLINE
Course: 413 ~ Lesson 14
Lecture Title: COSTS
Page.
.of-*.
NOTES
III.
C. ESP
1. Single stage to 99.9% E $2.25 - $6.50/ACFM
2. Special applications $6.50 - $30.00/ACFM
D. Wet collectors
1. Cyclone scrubber - $1.00 - $3.00/ACFM
2. Venturi scrubber
(a) mild steel $1.00 - $4.00/ACFM
(b) stainless steel $2.00 - $6.00/ACFM
Maintenance Cost
A. General cost/ACFM
Cents
B.
Collector
Baghouse
Precipitators
High Volt
Low Volt
Cyclones
Wet Collectors
Low ACFM
4
2
1
1
4
Medium ACFM
10
4
3
3
8
High ACFM
16
6
5
5
12
Maintenance formulas
1. Baghouses and Cyclones
Cost - S[0.7457(P)KH + M]
6356E
P = Pressure drop in H.O
H
K
M
E
S
Hours of annual operation
$/Kilowatt-hour
Maintenance $/ACFM
Fan decimal efficiency
ACFM design capacity
Precipitator
Cost = S[JHK + M]
J = Kilowatts /ACFM
Wet collectors
Cost = S[0.7457 HK(Z
Q
h
t WHL + M
H20 circulated gallons/ACFM
Height of pumping liquor = feet
296
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CONTENT OUTLINE
Page.
of.
Course: 413 - Lesson 14
Lecture Title: COSTS
Ill
*
NOTES
Z = Total power input for scrubbing efficiency
in horsepower/ACFM
L = Liquor cost $/ACFM
Reference: Applying Air Pollution Control Equipment,
Pollution Engineering Magazine
297
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
. REPORT NO. IT
EPA 450/2-80-068 J_
4. TITLE AND SUBTITLE ~ "
APTI Course 413
Control of Particulate Emissions
Student Workbook
3. RECIPIENT'S ACCESSION-NO.
5. REPORT DATE
March 1980
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
D. Beachler, G. Aldina, J. Jahnke
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Northrop Services, Inc.
P. 0. Box 12313
Research Triangle Park, NC 27709
10. PROGRAM ELEMENT NO.
B18A2C
11. CONTRACT/GRANT NO.
68-02^2374
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Manpower and Technical Information Branch
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Instructor^ Guide
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
EPA Project Officer for this Instructor's Guide is R. E. Townsend, EPA<-ERC,
MD-20, Research Triangle Park, NC 27711
16. ABSTRACT
The Instructor's Guide for the Air Pollution Training Institute
Course 413, "Control of Particulate Emissions," contains complete
information for conducting a 4 day course in particulate emissions
control. The Guide contains course goals and objectives, preparation
instructions, lesson plans, exams and exam keys, solutions to problem
sets, and copies of handout materials. The lesson plans include keys
to 35mm slides developed for the course and suggested instructional
techniques.
This Guide is intended for use in conjunction with the Student Manual
(EPA 450/2-80-066) and the Student Workbook (EPA 450/2-80-067) for
APTI Course 413.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COSATI Field/Group
Personnel training
Air pollution control
Dust collectors
Instructor's guide
13B
51
68A
18. DISTRIBUTION
Available from National Technical
Information Service, 5285 Port Royal Rd.,
gr,v-i no field. VA 22161
19. SECURITY CLASS (ThisReport)
21. NO. OF PAGES
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
298
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