PB-226 551
SIZE-REDUCTION EQUIPMENT FOR MUNICIPAL SOLID WASTE
VOLUME I. PROCEDURES FOR EVALUATING AND COMPARING
EQUIPMENT
VOLUME II, INVENTORY OF EQUIPMENT
Midwest Research Institute
PREPARED FOR
Environmental Protection Agency
(Solid Waste Management Office)
1973
DISTRIBUTED BY:
National Technical Information Service
U. S. DEPARTMENT OF COMMERCE
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BIBLIOGRAPHIC DATA
SHEET
1. Report No.
F.PA/5-W/SU-SV
4. T itle and Subtitle
Size-reduction equipment for municipal solid waste
3. Recipient's Accession Nn
PB-226 551
5. Report Date
1973
6.
7. Author(s)
Midwest Research Institute
8. Performing Organization Rept.
No.
9. Performing Organization Name and Address
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
10. Project/Task/Work Unit No.
11. Contract/
14.
15. Supplementary Notes
16. Abstracts
The objective of the study reported on was twofold: (1) to develop a comprehensive
procedure for evaluating and comparing equipment used to effect size reduction of
municipal solid waste; (2) to compile an inventory of current manufacturers and
users of such equipment. The report is intended for use by administrative personnel
(or other equipment, purchasers lacking a technical background). Volume I discusses
the role of size-reduction equipment in solid waste management, general guidelines for
developing a basic design for a size-reduction facility, a reliable numerical rating
prodedure, and test procedures to be used. Volume II provides a discussion of
information sources for the inventory, data sheets from each responding manufacturer
and supplier,, and a listing of solid waste processing or disposal facilities that
use size-reduction equipment in their system.
17. Key Words and Document Analysis. 17o. Descriptors
*Waste disposal, Urban areas, ^Crushers, Comminution, Grinding mills
17b. Identifiers/Open-Ended Terms
*Solid waste disposal, size reduction equipment rating
17e. COSATI Field/Group 13B
18. Availability Statement
19.. Security Class (This
Report)
UNCLASSIFIED
20. Security Class (This
Page
UNCLASSIFIED
21. No. of Pages
22. Price
FORM NTIS-3S CREV. 3-72)
USCOMM'DC I4BS2-P72
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This report has been reviewed by the U.S. Environmental
Protection Agency and approved for publication.. Approval
does not signify that the contents necessarily reflect the
views and -policies of the U.S. Environmental Protection
Agency, nor does mention of commercial products constitute
endorsement or recommendation for use by the U.S. Government.
An environmental protection publication (SW-53c) in the
solid waste management series
Preceding page blank
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TABLE OF CONTENTS
VOLUME I
STANDARIZED PROCEDURES FOR EVALUATING AND COMPARING
SIZE-REDUCTION EQUIPMENT
Page
Chapter I-Introduction 1
A. Background . 1
B. Objective of. the Study 1
C. Technical Approach ..... 2
Chapter II-Size-Reduction of Municipal Solid Waste 3
A. Introduction 3
B. Reasons for Size-Reduction in Solid Waste Management 3
C. Size-Reduction Equipment . ...... 4
D. Wet vs Dry Systems . 6
Chapter Ill-Solid Waste Size-Reduction Facility Design . 7
A. Introduction . * 7
B. Size-Reduction as Part of a System . 7
C. Design of a Typical Size-Reduction Facility 8
D. Size and Power Requirements 22
Chapter IV-Niimerical Rating Procedure 30
A. Introduction 30
B. Numerical Procedures 30
C. Development of the Numerical Rating System 31
D. Summary of the Numerical Rating Procedure. . 35
E. Application of the Numerical Rating System . 35
F. Evaluation of the Results. . . 38
Chapter V-Size-Reduction Technical and Economic
Performance Test Program 45
A. Introduction . . 45
B. Recommended Testing Facilities . . . . 45
C. Summary of the Test Program 47
D. Technical and Economic Performance Tests . 47
E. Performance and Evaluation of Test Program ............ 49
Chapter Vl-Conclusions and Recommendations 53
A. Conclusions ..... 53
B. Recommendations 54
1'T
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APPENDICES
Page
I Persons Interviewed Concerning the
Numerical Rating Procedure .............. 55
II Numerical Rating Procedure for the Comparative
Evaluation of Solid Waste Size-Reduction Equipment 57
III Test Procedure No. 1, Technical Performance Test
and Test Procedure Wo. 2, Economic Performance Test. . . 67
TABLES
1 Solid Waste Management Systems' . 8
2 Solid Waste Categories . 3
3 Suggested Minimum Shredder Horsepower 24
4 Purchase.Aspect Factors. ... 32
5 Operating Aspect Factors 33
6 Relative Weight of Individual Indexes 41
FIGURES
1 Size-Reduction Facility Flow Chart 9
2 Typical Size-Reduction Facility.. .• 10
3 Layout of St. Louis, Missouri, Solid Waste
Size-Reduction Facility 14
4 Solid Waste Size-Reduction Power Equipment . ....... 25
5 Shredder Selection Nomograph 28
6 Numerical Rating Procedure Individual Worksheet. . 37
7 Numerical Rating .Procedure Individual Factor Average . . 39
8 Numerical Rating Procedure Data Summary Sheet. . . 40
9 Sample Entries on Numerical Rating Procedure Data
Summary Sheet 43
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VOLUME II
INVENTORY OF SIZE-REDUCTION EQUIPMENT
Page
Chapter I-Introduction ..... 73
Chapter II-Size-Reduction Equipment 75
Chapter Ill-Sources of Information . ^ . 84
Chapter IV-Selection Guides . 87
Chapter V-Manufacturers' Data. Sheets. . . . . 94
APPENDICES
I Existing Municipal Solid Waste Size-Reduction
Installations. ....................... 19
II Manufacturers of Size-Reduction Equipment ..... . . 123
TABLES
1 Companies Furnishing Data for the Inventory 85
FIGURES
1 Crushers 77
2 Cage Disintegrators 77
3 Shears . 78
4 Shredders, Cutters, and Chippers . 78
5 Rasp Mills . 80
6 Drum Pulverizers ....................... 80
7 Disk Mills 81
8 Wet Pulper 81
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SIZE-REDUCTION EQUIPMENT FOR MUNICIPAL SOLID WASTE
VOLUME I
STANDARDIZED PROCEDURES FOR EVALUATING AND COMPARING
.SIZE-REDUCTION EQUIPMENT
CHAPTER I
INTRODUCTION
A. Background
The Solid Waste Disposal Act of 1965 has concentrated
considerable interest on the question of what to do with the huge
quantities of municipal solid waste generated in the United States
each year. Recent activity has centered on the utilization of this
great quantity of material as a national resource. Thus, emphasis
in solid waste management has changed in recent years from disposal
to recovery, recycling, or reuse. Many systems for the recovery
and reuse of solid waste require that the waste components be
physically separated from each other and that a reduction in the
particle size of the waste precede recovery or reuse operations.
Even in those geographic areas where disposal will continue to be
the only economic solution to the solid waste problem, size reduction
may increase the capacity of the disposal system.
Size reduction is an operation that is common to many
solid waste management systems-reuse, recovery, or disposal. It
is also an operation that can be accomplished with off-the-shelf
commercially available equipment. Thus, size reduction is a logical
starting place for a comparative study of solid waste management
systems or equipment. This report presents the result of a study
to develop a standardized procedure for the comparison and evaluation
of size reduction equipment.
B. Objective of the Study
The objective of this study was twofold: (1) to compile
an inventory of current manufacturers and users of solid waste size
reduction equipment; and (2) to develop a comprehensive procedure
for evaluating and comparing equipment used for size reduction of solid
waste. This report is intended for use by administrative personnel
(or other equipment purchasers without technical backgrounds)
as an aid in the comparison, evaluation, and selection of equipment.
It will also be Incorporated into a state-of-the-art report on size
reduction and a selection criteria document for use by solid waste
management organizations.
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C. Technical Approach
A three-phase effort was used to meet the objectives of
the study. Phase I was a collection of data and information on current
size reduction equipment and manufacturers. Phase 11 was a development
of a numerical rating procedure for the comparative evaluation of
size reduction equipment. Phase III was a development of a test
procedure to generate base-line, technical, economic, and performance
data needed for the numerical rating procedure.
1. Phase I-Equipment Inventory. <4An Inventory of Municipal
Solid Waste Size Reduction Equipment,'' was previously presented by MRI
in a separate report to EPA dated 2 October 1972. The. report includes a
general background of size reduction equipment, design, a discussion
of the sources of information for the inventory, selection guidelines
based on the experience of operators of municipal solid waste size'
equipment, data sheets from each of the manufacturers and suppliers of
size reduction equipment, and a listing of solid waste processing or
disposal facilities that include size reduction in their system.
2. Phase II-Numerical Rating Procedure. In the process of
gathering data for the inventory of Phase I, numerous contacts were
made with operators, users, consultants, sellers, and manufacturers of
size reduction equipment. The information gained from these contacts was
combined with the knowledge of the MRI project staff to develop a list of
the factors to be considered in selecting size reduction equipment. This
list was reviewed by the project staff to develop a preliminary model of
the rating system. The preliminary model was then reviewed in detail
with knowledgeable persons in the field of size reduction. Their comments
were incorporated with the preliminary model into the final model of the
Numerical Rating Procedure.
3. Phase Ill-Test Procedure. Several factors in the Numerical
Rating Procedure required comparison to performance norm's (i.e.,
'•base-line'' data). In many instances the base-line data will not exist,
or are not available because they are proprietary. Thus, a plan was
developed to use existing EPA demonstration grant or pilot plant
projects to develop sufficient base-line data for use with the
Numerical Rating Procedure.
The following chapters present the results of this project.
Chapter II includes a definition of the role of size reduction in solid
waste management"-and a brief description of the equipment used. Chapter
III discusses the general guidelines for developing a basic design for
a size reduction facility. Chapter IV presents the Numerical Rating
Procedure. Chapter V reports the test procedures to be used to develop
the base-line data for size reduction machinery. Chapter VI presents
the results, conclusions, and recommendations of the study.
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CHAPTER II
SIZE REDUCTION OF MUNICIPAL SOLID WASTE
A. Introduction
Size reduction is defined as operations or processes which
reduce the size of influent materials through division into two or more
subunits. For the purpose of this study, only size reduction by the
application of mechanical forces is considered. Size reduction of
municipal solid wastes (often called shredding, grinding, or pulverizing)
is a new concept and much of the technology has been borrowed from the
mining and rock-crushing industry. Because solid waste is a hetrogenous
mixture (unlike rock), much of the technology is not directly
transferable and size reduction of solid waste has not been efficient
or widely practiced. However, as more solid waste systems are built, the
technology of solid waste size reduction is being advanced.
B. Reasons for Size Reduction in Solid Waste Management
More than 300 billion pounds of municipal waste are produced
annually in the United States and the traditional methods of disposal
are becoming inadequate. Land areas suitable for landfill near urban
areas where the bulk of the solid waste is generated are becoming
scarce and expensive. Open burning and open dumping have been outlawed
in many areas because of pollution and health hazards. Incineration is
becoming increasingly more expensive because of sophisticated pollution
control equipment required to meet acceptable air quaiity standards.
Current emphasis in solid waste management, therefore, has centered on
both disposal of this great quantity of material and its utilization as
a national resource. The volume of waste produced each year dictates
that disposal or recovery of the waste be mechanized to reduce ever
increasing costs. This has, in turn, created a need for size reduction
of solid waste to accomplish reduction of bulk and permit easier
mechanical handling.
Current research and development work in solid waste
management technology is concerned with resource recovery. Numerous
resource recovery systems have been proposed and pilot plants have
been built in some instances. These recovery systems can be grouped
into two classes-materials recovery systems and energy recovery systems.
In many of the proposed recovery systems size reduction is one operation
that is common. Size reduction does not in itself increase the value of
the waste, but it may reduce bulk and increase ease of handling. These
features make size reduction a desirable feature of solid waste
management.
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1. Bulk reduction; Prior to size reduction, municipal solid
waste has a low and nonuniform density. Size reduction increases the
heterogeneity and the bulk density. The process of size reduction yields
a smaller range of particle sizes, and thoroughly mixes the solid waste.
The net result is that the waste can be easily compacted to a uniform
density, and voids formed by bulky items are eliminated. The amount of
reduction in bulk can vary depending on the final processing of the
waste; however, discussions with landfill operators has indicated that
shredded waste placed in a landfill and compacted in a manner similar to
unshredded landfill, can have the density increased by up to 25% over
that of unshredded landfill.
It. is the bulk reduction and mixing of the waste that gives
size reduction its most promising potential for immediate application.
Solid waste that has been shredded and compacted generally has fewer
voids than unshredded landfill, has no objectionable odor, does not
attract vermin, and has been used in landfill without a daily cover of
soil on an experimental basis. The combined effect of the elimination
ot the daily cover and the bulk reduction can increase the solid waste
mass capacity of a landfill area by a factor of two or more.
2. Ease of handling: Size reduction of solid waste is of
major importance in many solid waste processing systems because it
permits more efficient handling of the waste. Shredded waste has a
smaller range of particle size, is uniform in density, and is a more
homogenous mixture, thus permitting it to be easily handled and
processed by mechanical equipment. The mechanical and chemical
processes used by most recovery systems require separation of various
components. This separation is easier and more efficient when particle
size range is controlled.
C. Size Reduction Equipment
There are 10 basic types of size reduction equipment
commercially available-crushers, cage disintegrators, shears, shredders,
cutters and chippers, rasp mills, drum pulverizers, disk mills, wet
pulpers, and hammermills. Of these types we believe that only
hammermills and wet pulpers will be important for future application
in either primary or secondary municipal solid waste size reduction.
To date, only hammermills and wet pulpers have been used in the United
States, although the rasp mill has been used in Europe. Further details
on the designs of each type of equipment can be found in Ref. 1. Only
the hammermill and wet pulper types will be discussed in this report.
1. Wet pulpers: A wet pulper is similar in design and
operation to a common household blender. In operation, a slurry of
about 90% water and 10% solid waste is placed in the pulper. The
interior of the pulper may be lined with protruding hardened impact
pins, but often the interior is a smooth surface. A central rotating
element (either a disk or a set of blades) spins at high speed
(peripheral speed of 5,000 ft/min) forming a vortex in the slurry.
Repeated impact of the solids with the rotating element reduces the
solid waste to a pulp. Unpulpable items, such as rubber tires are
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rejected. Wet pulpers can operate as a batch process or a continuous
process. After pulping the slurry is removed from the pulper and the
majority of the water is removed by squeezing and is reused.
The use of a wet pulper for size reduction has not found
widespread acceptance. Many experts object to the concept of adding
water and then removing it after size reduction. Only one facility using
a wet pulper to process solid wastes is in operation in the United
States. The plant is located in Franklin, Ohio, and uses the Black-Clawson
Hydropulper. The Franklin plant is a small pilot plant having a capacity
of 6 tons/hr. Larger plants have been proposed; however, their plans
usually include the use of a mechanical shredder ahead of the pulper
to increase pulper efficiency and to reduce wear and possible damage
to the pulper.
2. Hammermills; The most common type of equipment currently
used for size reduction of solid waste is the hammermill. A hammermill
consists of a central rotor with radial arms (hammers) protruding from
the rotor circumference. The rotor is enclosed in a heavy duty housing
and the housing may be lined with hard metal members. Some hammermills
may also have stationary breaker plates or cutter bars mounted inside
the housing. Input material is reduced in size by being mechanically
beaten and torn by the hammers.
There are two basic types of hammermills-the horizontal shaft
type and the vertical shaft type. The horizontal shaft hammermill is
the more common type. As the name implies, the rotor shaft is
horizontal and supported on each end. Input is at the top and
material flows through.the machine by gravity. Most horizontal
hammermills also have a grate placed across the output opening. Input
material cannot pass through this grate until it has been sufficiently
reduced in size. Output particle size is primarily controlled by the
size of openings in the grate.
The vertical shaft hammermills have the rotor shaft placed
in a vertical position. The input material moves parallel to the shaft
axis and flow is by gravity. The lower shaft bearing must be a thrust
bearing to support the weight of the rotor. These machines may have a
decreasing cross-sectional area between the rotor and the stationary
housing. Thus, size reduction of the input is progressive as the material
moves through the machine.
There are three basic variations of both the vertical or
horizontal shaft hammermills-the swing-hammer type, the rigid-hammer
type, and the rolling-element type. The swing-hammer type is the most
common, and has hammers free to pivot mounted on pins. The swing-hammer
concept reduces damage to the machine from hammer impact with a very
hard or strong piece of input material. However, the hammers can
also create a severe balance problem if they become entangled with
the input material and do not swing freely. The rigid-hammer type is
generally used in smaller sized machines not specifically designed for
solid waste. For both the fixed- and rigid-hammer types, hammer designs
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vary from sharp choppers to blunt rectangular beaters. The latter are
often used in machines for processing solid waste materials. In
rolling-element type machines, the hammers are usually in the form of
star wheels which grind up the input refuse by rolling it between the
wheels and the housing side walls.
D. Wet vs Dry Systems
The hammermill and the wet pulper represent two different
concepts in solid waste size reduction-the dry system (the hammermill)
and the wet system (the wet pulper). For any given solid waste
management system, the two concepts are not interchangeable; that is,
in any given size reduction system you cannot directly replace one with
the other. The wet system requires extensive auxiliary equipment for
addition and removal of the water, and this equipment is not needed by
the dry system. In addition, the wet system is more expensive and it is
therefore only usually considered where recovery of a salable product
is concerned. Also, most of the proposed wet systems using a wet pulper
have included in their plans a ''solid waste shredder'' ahead of the
pulper to Increase efficiency and prevent damage. Because of its limited
use, the wet system, or wet pulper, was not considered a primary method
of size reduction and was not included in further efforts of the
program.
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CHAPTER III
SOLID WASTE SIZE REDUCTION FACILITY DESIGN
A. Introduction
The use of size reduction equipment to process municipal solid
waste is an emerging technology. As.a result, many of the installations
now operating in the United States are small pilot-plant operations, and
many were largely supported by government funds. Because of the newness
of the technology, there is no accumulated body of formal knowledge.
Each new installation thus draws heavily on the experience of earlier
installations. However, several general trends in plant layout and
design have been developed and some of them are already accepted as
standard. This chapter presents a brief discussion of the current state
of the art for design of size reduction facilities. The information
contained in this chapter was obtained from personal visits to many, of
the solid waste processing installations now in operation, from
discussions with knowledgeable people, and from a review,-of the
pertinent literature. Any plants or installations referred to in the
discussion are described in further detail in the report entitled,
''An Inventory of Municipal Solid Waste Size Reduction Equipment''
(Ref 1).
B. Size Reduction as Part of a System
A solid waste size reduction facility is only one part of a
system of solid waste management. As such, the facility must be
integrated into the system and designed to fit the needs of the system.
Before the size reduction facility can be designed, it is first
necessary to know the characteristics of the solid waste. Then the
role that size reduction is to fill in the solid waste management
system can be determined, and the technical and economic performance
requirements of the facility can be specified.
There is a variety of solid waste management systems now being
used or developed in the United States. They range from the simple open
dump, through the common sanitary landfill, to the technically
complicated total recovery or reuse system (i.e., Franklin, Ohio).
However, all of these systems can be grouped into-one of two general
categories-those systems where disposal is the.primary goal, and those
systems where recovery, recycling, or reuse is the primary goal. Table 1
presents a summary of the more common systems.
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TABLE 1
SOLID WASTE MANAGEMENT SYSTEMS
Disposal Systems
Landfill
Incineration
Recovery, Reuse, or Recycle Systems
Energy
Materials
Pyrolysis
Compost
Size reduction of the solid waste can be used to increase the
efficiency of each of the systems listed in Table 1 by (t) reducing
bulk, (2) providing a narrow range of particle size, and (3) thoroughly
mixing the waste (however, size reduction may be detrimental to
grate-type incinerators). Further, the size reduction facility can be
designed so that it will affect each of these factors to the degree
required for optimization of system efficiency. Therefore, size
reduction is a ''service'' component of the system-i.e., it does not
determine what the operation parameters of the system are, it simply
adjusts the physical characteristics of the solid waste to optimize the
efficiency of the system.
Ah. important step in designing a solid waste size reduction
facility is to determine what functions the facility is expected to
perform in the solid waste management system. This involves determining
what input the facility will receive and what output it is expected to
deliver. Of the two-input and output-an exact definition of the output
requirements is the more critical, for the output requirements determine
the performance specifications for the size reduction facility-capacity
in tons per hour, output particle size, composition, etc.
C. Design of a Typical Size Reduction Facility
Once the input and output requirements of the size reduction
facility have been determined, the basic design of the facility can
be developed. The following paragraphs describe a typical solid waste
size reduction facility utilizing the most recent state-of-the-art
concepts.
The functions of a typical facility are shown in the block
diagram flow chart of Figure 1 and the facility layout is shown
in Figure 2. The facility consists of the following basic operations:
1. Receiving and holding-receiving input waste, premixing,
sorting, separation of bulky itenvs, temporary storage for processing;
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Figure 1 - Size Reduction Facility Flow Chart
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Feed
Conveyor
Receiving and Holding
Input- Conveyor
u ~
Separation and Sorting
Shredder
Discharge Conveyor
Figure 2 - Typical Size Reduction Facility Layout
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2. Input conveying-raaterial transfer, inspection,
sorting, separation;
3. Feed control-material flow rate control;
4. Size reduction-shredding of the solid waste;
5. Discharge conveying-material transfer, separation of
unwanted components; and
6. Removal-disposition or disposal of shredded waste.
1. Receiving and holding: The receiving and holding area
of the size reduction facility serves the function of accepting the
input of solid waste from the refuse collection system (usually
packer trucks), and storing the material until it is processed by
the shredder. This function is necessary because the input is usually
in batches (i.e., individual packer,trucks) with variable quantities
of waste at different times. However, maximum efficiency of the shredder
usually requires continuous feeding at a uniform rate. Thus, a
buffer on temporary storage is needed between the waste collection
and the shredder operations.
The most successful procedure developed for receiving and
handling the input solid waste material has been the open receiving
pad. The open receiving pad is simply an open, level and paved area
adjacent to the waste shredder. In some installations, the pad is
enclosed so that operations are not affected by bad weather. Packer
trucks deposit the waste on the pad at the direction of _m operator.
The pad operator uses a bucket-equipped hi-loader, or other piece of
waste moving equipment, to pile and mix the waste, and to place the
waste on the input conveyor. The operator controls the feed rate to the
shredder by the amount of waste he places on the conveyor. He can
also increase the efficiency of the shredder by mixing the waste, and
distributing bulky and difficult-to-process i,terns throughout, the
was te.
The open receiving pad has proven to be the most successful
input system because it provides an easy and economical means of
presorting and mixing the input waste. Although municipal .solid
waste is generally considered to be a heterogeneous mixture, it
is not a thorough mixture as received, and it will have occasional
bulky items, such as appliances or pieces of furniture. There will
also be difficult-to-shred items such as tires, rolled-up rugs,
tree trunks, heavy metal pieces, etc. Any of-these items can cause
trouble for almost any size or type of reduction machine. With an
open receiving pad, the operator can easily remove the items that
he does not want to enter the machine, distribute the remainder
of the bulky items, and thoroughly mix the refuse before feeding
it to the shredder.
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Other input receiving systems have been tried but have
generally not been as successful as the open receiving pads. One
frequently used procedure has been to have the packer trucks discharge
the waste directly into a feed hopper or storage bin. Both of these
techniques have proven troublesome because the unshredded waste
tends to bridge and to jam hoppers and is difficult to feed continuously
and uniformly from a storage pile. Another common system is to discharge
the waste from the packer trucks directly onto the shredder input
conveyor. This system subjects the input conveyor to considerable
abuse and causes uneven feeding of the shredder-sometimes producing
motor overloads, machine jamming, and shutdowns.
2. Input conveying: Input conveying consists of those
components of the facility that transfer the solid waste from the
receiving and holding area to the shredder. It is in the conveying
operations where material flow rate is established and initial
mechanical separation is performed. The input conveying will frequently
consist of two or more conveyors-the input conveyor that receives
material directly from the receiving pad, and the feed conveyor(s)
that changes the elevation of the material and feeds the material into
the shredder.
a. Input conveyors: Heavy duty metal pan-type
conveyors have proven to be the only reliable type of input conveyors.
The input conveyors receive considerable abuse, mainly due to dropping
and dumping of the solid waste into the conveyor. Operating life of
flexible belt conveyors has, in general, not been adequate in this
application (one exception is St. Louis, which has obtained satisfactory
performance with a flexible belt). The typical input conveyor arrangement
places the conveyor in a horizontal position at the bottom of a
feed trench. The trench is approximately 5 ft. deep with inward
sloping sides. The solid waste material is simply pushed off the
receiving pad into the trench where it then falls onto the input
conveyor.
The input conveyor normally operates at a fixed speed
and the waste feed rate to the shredder is adjusted by the depth
of waste the operator places in the trench. Several installations
have installed variable speed conveyors, but experience has shown
that only one speed is used in actual operation. However, the input
conveyor should be interlocked to the feed conveyor and they both
should be electrically interlocked to the shredder motor. These interlock
will stop the conveyors If the shredder motor overloads. This gives
the shredder an opportunity to clear itself before receiving additional
input that could cause a jam.
b. Feed conveyors: Flow through a shredder is generally
by gravity and thus is vertical. Therefore, it is necessary to raise
the waste to the input opening of the shredder. This is usually
accomplished by an inclined feed conveyor. The Inclined conveyor
can be a flexible or rubber belt conveyor since this conveyor
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is not subject to the abuse that the input conveyor receives. A
common problem with many inclined conveyors is the tendency of the
waste to slide back down the conveyor. This problem can be minimized
by using less slope or a belt with a textured surface or with cleats.
One such example is the Z-bar conveyor used at the New Castle County,
Delaware, facility.
c. Sorting and separating; Some amount of separation
of the waste can be done at the input and feed conveyors. Separation
at this point is usually a protective measure designed to prevent
undesirable materials from entering the shredder. Because of the
depth of material on the conveyc the presence of numerous closed
bags and boxes, and the tangled nature of the material before
shredding, a thorough separation is not practical. Magnetic separation
or a metal detecting system can be used to prevent large pieces
from entering the shredder. However, the generally accepted procedure
is to sort undesirable items at the receiving area and have an operator
visually monitor the input conveyor directly ahead of the shredder.
The operator will manually remove any undesirable material he detects.
3. Feed control techniques; Control of the rate at which
the solid waste is fed to the shredder is probably the most important
aspect of daily operation of a size reduction facility. Feed rate
control is of major importance because it has a large effect upon
the efficiency and life of the shredder. It is also difficult to
perform accurately and reliably. Several techniques have been tried
and all have achieved only limited success. Several of the more
common techniques are discussed in the following paragraphs.
a. Vibratory feeders; The vibratory feeder has long
been used in the ore and rock-crushing industry to feed aggregate
material of variable composition. It will agitate the input and tend
to distribute it evenly over the feeder surface. It thus tends to
4'smooth out'' variations in flow rate. One example of a vibratory
feeder installation for solid waste is at the St. Louis, Missouri,
Refuse Plant. A diagram of the installation is shown in Figure 3.
The vibratory feeder is installed in the bottom of a trench with
sloping sides. The feeder is shorter than a normal input conveyor
and can be fed from three sides. The waste material is simply pushed
off the pad and onto the feeder which then feeds the inclined belt
that raises the solid waste to the shredder input. Structural problems
from the vibrations have occurred with this installation, however,
and a flexible belt unit has replaced the vibratory feeder.
b. Leveling bars; Leveling bars, or "doctor''
blades, have also been used with an input conveyor to control the
depth of waste on the conveyor. In general, these devices have not
been successful because of the tendency of the waste to jam,
bridge, and hang up on items caught on the bar or blade. One
successful application has been at the Milford, Connecticut,
plant. This installation has a direct feed from the input conveyor
13
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Inclined Flexible Belt
Feed Conveyor
Figure 3 - Layout of St. Louis, Missouri, Solid Waste
Size Reduction Facility
14
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to a shredder mounted in a pit. A hydraulically operated blade is
located over.the input conveyor just ahead of the.shredder* An operator
continuously monitors the input and controls feed rate to the shredder
by adjusting the height of the b-lade. Minor jams at the blade are
frequent, but they are easily controlled by operator action.
c. Compression feed rollers: Several manufacturers of
size reduction equipment offer, as an optional device, an input
compression feed roller. This device is simply a roller that compresses
the input waste and literally "force feeds*' it into the machine.
It usually has a hydraulic power drive with a variable speed control.
This device serves three functions:
(1) It controls the rate of feed;
(2) It physically ''grabs'' the waste and prevents
the shredder from pulling too much material from the feed conveyor,
and possibly jamming itself, and
(3) It obstructs the input opening and reduces
''backfire'' or ejection of material out the input opening.
Several manufacturers recommend the use of a compression
feed roller (to protect their machine from bulky objects) and
some require one to be included before they will submit a bid.
However, the devices have not been found to improve performance
enough to justify their high cost, and are not used in most installations.
4. Size reduction equipment: The size reduction equipment
consists of those components of the system directly involved in the
physical application of the size reduction force to the input waste.
The components include the shredder, the drive motor, the motor
controls, and the related auxiliary equipment. The following paragraphs
include a discussion of some of the factors to be considered in
designing the shredder installation. Technical considerations in
sizing the shredder and motor capacity are presented in Section D
of this chapter.
a. Shredder installation: Three concepts for physical
location of the shredder are in general use. They are: (1) below
ground (in a pit); (2) at or above ground level; and (3) on the side
of a hill. All three concepts have been used successfully and neither
has a distinct advantage over the others. Oftentimes the choice
of installation is determined by site, restrictions or geography
rather than by technical or performance factors.
Installation of the shredder at ground level Is the
simplest and the most common type of installation. The shredder Is
usually mounted on a concrete base and has easy access for all sides.
The major disadvantage with this type of installation is that it
requires an inclined feed conveyor to lift the waste to the shredder
15
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input. A unique approach to this problem, used by Ecology, Inc.,
Brooklyn, New York, was to put the Input receiving pad on the roof.
The Inclined conveyor was thus eliminated and the shredder feed
is directly from the input feed conveyor. This approach has an
obvious appeal for facilities located in congested urban areas where
space for a receiving pad is at a premium.
Installation of the shredder below ground or in a
pit is a concept that has been used at several installations. The
logic behind this choice is that noise is significantly reduced,
and plant personnel are protected from fires or explosions that
may occur due to flammable materials in the waste and also from
flying debris from the shredder. There is also the consideration
that the inclined conveyor is moved from the input to the output
(to lift the waste out of the pit) thus resulting in a cost savings
because of the less complicated equipment required for conveying the
shredded waste. However, access to the shredder for maintenance
becomes limited, especially for horizontal shaft hammermills.
These units are usually designed so that removal of the top housing
is required for access to the hammers. Thus, if installed in a
pit, the overhead chutes and conveyors must be removed for access.
Vertical shaft hammermills do not have this problem as they usually
have side access doors and can be easily serviced in a pit. For
either type of unit, major repair (I.e., removal of a rotor or
motor, etc.) requires a crane to lift components out of the pit.
Examples of plants with the shredder mounted in a pit are Milford,
Connecticut, and San Diego, California.
If the plant site has a hill or a pronounced slope,
it may be wise to mount the unit on the side of the hill. The input
pad is then located at the top of the hill and the discharge area
is located at the bottom. The inclined conveyors are eliminated and
the shredder feed is directly from the input conveyor. Although
this concept has an obvious appeal in simplicity and equipment cost
saving, structural costs may be increased if the plant is to be
enclosed. Examples of facilities built on the side of a hill are
Tacoma, and Vancouver, Washington.
b. Shredder type: There are two types of shredders
currently available—the horizontal shaft type and the vertical shaft
type-and the horizontal shaft hammermill is by far the more common
type of machine. Both types of machines operate at about the same
mechanical efficiency (power per ton) and both types of machines
have generally been successful. However, there are some distinct
differences in their performance, especially in relation to output
particle size control, handling of difficult to shred items, wear
rates, and surge capacities.
(1) Particle size control: The horizontal shaft
hammermill has a positive control over maximum output particle size.
All input material will remain inside the machine until it Is
16
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sufficiently reduced in size to pass through the discharge gate.
Thus, only minor variations in particle size will occur with
changes in material flow rate or composition. This factor can be
of critical importance if the shredded waste is to be used in a
system where maximum particle size is important, i.e., a pneumatic
feed burner. The disadvantage is that the horizontal shaft hammermill
is hot a 4'free-flowing'' shredder and is thus subject to high wear
rates and is easily overloaded.
The vertical shaft hammermill does not necessarily
have positive control over particle size. Thus, a unique feature of
these machines is that the average output particle size will change
as the flow rate or material composition changes. Although this
factor would appear, at first glance, to be a disadvantage, for systems
that do not require accurate particle size control, it may be of
minor importance.
(2) Shredding of difficult items: Because the
horizontal shaft hammermills have a restricted discharge (i.e., an
output grate) they are subject to damage from difficult to process
items. The shredder will "try" to reduce the item to the output
size or to ''extrude'' it through the grate. Items such as heavy
steel, rolled-up rugs, large tree limbs, etc., which require power
inputs beyond the capabilities of the machine, can cause jams.
Thus, for these machines, presorting of input material and separation
of undesirable items is required.
These machines normally have metal traps where
heavy steel or other nonprocessable items are collected, but these
devices are not reliable protection devices. A hardened gear, for
example, may make numerous revolutions in the machine, damaging
hammers, levers and grates, before it enters the metal trap.
Metal traps must be manually emptied at regular intervals.
The vertical shaft machine, on the other hand,
is much less subject to damage because it will pass difficult items
through the machine. This means that presorting of the input can be
less thorough and only obviously undesirable items that are physically
too large to pass through the machine opening need be separated.
However, it is possible that some items may go through the machine
with only minor reduction in size.
Neither type of machine will satisfactorily
process items with high tensile strength such as rolled-up rugs,
yard goods, etc. Also, both machines are subject to jamming by rope-like
items such as cable, wire, bedsprings, tubing, etc. These items can
wrap around the rotor and create unbalance problems.
(3) Wear rates; The vertical shaft hammermills
usually operate on a progressive size reduction principle, i.e., the
input material is gradually reduced in particle size as it passes
17
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from Input to discharge. Several operators claim, therefore, that the
vertical shaft hammermill has a more even distribution of wear than the
horizontal shaft hammermill and significantly lower hammer wear rates.
These claims have not been substantiated; however, the trend of the
limited data available indicates that the vertical shaft hammermill
may have lower hammer wear rates than a horizontal shaft hammermill.
c. Drive motors; Most size reduction equipment
designed for shredding municipal solid waste requires a main drive
motor in the range of 500 to 1,500 hp. The electric motor is the
most common type of motor selected, although diesel drives have been
proposed for some installations. A major factor to consider in choosing
the motor type is installation cost. A typical large size electric
motor draws substantial current and power companies will require
that a separate substation be installed. If the size reduction facility
is located at a remote site, the cost of providing electrical service
can become a significant part of the total capital investment. In
such cases, diesel power units may be more cost effective.
The usual procedure for connecting the drive motor to
the shredder is direct drive, i.e., the motor shaft is coupled
directly to the shredder rotor shaft. ThiB procedure is generally the
most simple and least expensive connection that can be made. Almost
all manufacturers of horizontal shaft hammermills recommend direct
coupling. However, one manufacturer does use a belt drive from the
motor shaft to the rotor with a large flywheel mounted on the other
end of the rotor. There does not appear to be any significant problems
with the belt drive system, although it is more complicated than the
direct drive. The belt drive does allow some flexibility in motor
locations, and may be advantageous in locations where space is at a
premium.
The vertical shaft hammermills generally use a gear or
belt drive system. Direct coupling of the motor shaft to the vertical
rotor is not practical. Thus, for most vertical shaft hammermills,
the motor is located along side the unit and a gear drive unit is
utilized. One manufacturer, E1DAL, uses the gear box as an integral
part of the shredder structure. Gear units, depending on specific
designs, will require additional support equipment (such as lubricant
pumps and temperature control devices), that are not required for
direct or belt drives. They will also increase the maintenance of the
shredder facility.
d. Motor controls; In addition to the necessary motor
switch gear, installation of several other items of control instrumentation
is becoming standard procedure. These items include indicating and
recording power meters, input and discharge conveyor interlocks, and
bearing temperature interlocks.
Indicating amp-meters are a standard item at most
shredder installations. The amp-meter indicates the motor current draw
-------
and is the easiest way to determine overloads. The operator can watch
the amp-meter and adjust the feed rate to obtain maximum efficiency
of the shredder. Many installations have indicating or warning devices
connected to the amp-meter to signal the operator when overloads
occur. Several installations have recording amp- or watt"meters.
These are not considered necessary and are only used when continuous
records of power consumption are desired.
Drive motor interlocks to the input conveyor are becoming
the standard device for protecting the shredder and drive motor from
overloads. These devices stop the input conveyor when the shredder
drive motor overloads. This prevents further feeding of material into
the shredder, reduces the load, and gives the shredder an opportunity
to '*clean out'' a potential jam before it occurs. Standard design
procedure is to have an automatic cutoff that stops the input conveyor
with the restart being manual, thus requiring operator attention to
the cause of the stoppage. Many operators of size reduction facilities
consider the drive motor-input conveyor interlock the single most
important automatic control in the entire facility. Even those installations
that did not originally include the interlock have now installed them
because damage to the shredder and drive motor has resulted from overfeeding.
The shredder bearing temperature sensor is another
protective device that is gaining wide acceptance. At most installations,
the device is designed to issue a warning if the shredder bearing
overheats, and it will continue to give the warning until the temperature
returns to the safe range. The warning tells the operator to stop the
feed conveyor and reduce the load on the shredder (and bearings) until
the temperature drops. Some Installations have included a bearing
temperature interlock that will turn off the shredder drive motor if
the bearings continue to overheat or exceed a critical temperature.
e. Auxiliary eguipment: Most manufacturers offer
several optional items or pieces of auxiliary equipment that can be
purchased with the shredder. Some of the more desirable ones are
discussed below.
(1) Power assist devices; Any shredder that has a
pressurized bearing lubrication system, has the basis for hydraulic
power assist devices. These devices include:
-Power cylinders for opening assist doors:
These items are especially helpful on horizontal shaft hammermills where
access to the hammers requires opening the top housing. Several
manufacturers include these door openers as standard equipment.
-Hammer pin extractors: These devices are
used to pull the hammer pivot pins from their mounting so that worn
hammers may be replaced. These devices are most helpful as it is
difficult to manually remove the hammer pins after extensive use of
the shredder.
19
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-External adjustments for wear; Several
hammermills have stationary breaker bars or cutter bars whose clearance
with the hammers can be adjusted from outside the shredder. Standard
equipment for these shredders is manual adjusters, however, hydraulic
adjusters are available and have been well received by operators who
have used them.
(2) Fire control systems: Due to the high
percentage of flammable materials in municipal solid wastes, fires in
the shredder are a common occurrence. Normally, a fire can be
''snuffed out" by continued feeding of the shredder; however, fires
associated with jams or stoppages must be extinguished. Manually
activated carbon dioxide or water extinguisher systems are available
and are recommended.
(3) Dust control systems: Dust and small particle
debris are a constant problem around a solid waste shredder. Two
techniques are used to control and minimize the problem. The simplest
procedure is to use a continuous water spray inside the shreddef. The
water reduces the amount of dust generated and causes most debris to
exit the shredder with the discharge. There are some experts who believe
the water also reduces the wear on the hammers.
Pneumatic dust collectors are the other form of dust
control technique used. They are most often used in systems where the
shredded waste is being used in an incinerator or boiler and any water
content is undesirable.
5. Discharge conveying: The discharge conveying elements of
the shredder serve the function of collecting the shredded waste from
the shredder and conveying it to the removal of disposal area. There are
normally two elements to the discharge area-the discharge chute or
collector and the discharge conveyor.
a. The discharge chute: The shredded waste material
being discharged from the shredder may possess considerable energy and
be moving at high velocities. Therefore, it is not practical to discharge
directly onto a conveyor. For horizontal shaft hammermills with bottom
discharge, a simple chute or deflection plate is placed directly under
the discharge and absorbs most of the energy from the waste. The waste
then slides down the chute or plate onto the discharge conveyor.
However, it is possible for the waste to "stick'' to the chute and
cause a jam. :To avoid this potential problem, the chute or deflector
plate can be replaced by a vibxator conveyor. The vibratory conveyor can
take the abuse and impacts from the discharged waste and still provide a
positive method of carrying the waste away from the shredder.
b. Discharge conveyor: The discharge conveyor transports
the waste from the shreddex to the removal or disposal operation of the
size reduction facility. This conveyor is usually a flexible belt that
moves at a much faster speed than the input conveyor. A flexible belt
20
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conveyor can be used in this application because the shredded waste has
a homogenous composition and contains no bulky objects to subject the
conveyor to abnormal physical abuse. The conveyor moves at a faster speed
to assure that the discharge of the shredder is always clear. The speed
may cause blowing and strewing of the waste so conveyor sides and covers
are frequently used.
c. Separation: If separation of the waste products is
required for subsequent operations, it is usually done at some location
in the discharge conveyor system. At this point the waste is shredded,
has a narrow range of particle size, is not very deep on the conveyor,
and has not been compacted or compressed. A wide variety of separation
devices including magnetic, pneumatic, and vibratory can and have been
used. A thorough discussion of separation techniques can be found in
Ref. 2.
6. Removal or disposal; The final operation of the size
reduction facility is removal-i.e., disposition or disposal of the
shredded waste. There are three removal systems now in use at various
size reduction facilities in the United States. The waste can be:
a. Directly conveyed to the next operation in the
solid waste management system; or
b. Loaded into transfer vehicles for bulk transport
to the next operation; or
c. Placed in intermediate storage to await transfer
and the next operation.
Direct conveyance of the shredded waste to the next operation
is not a frequently used removal operation. In fact, it is generally
only used when the next operation is landfill and the size reduction
facility is located at the landfill site. Even then, it is not a common
operation because of the capital investment required for long conveyor
runs, and the fact that the waste will still have to be spread at the
conveyor end. However, this procedure is used at Vancouver, Washington,
and New Castle County, Delaware.
Loading the shredded waste into transfer vehicles for bulk
transport to the next operation is a typical procedure, especially
in landfill systems. This procedure offers a direct cost savings
when the landfill is at a remote location. The size reduction facility
can be placed at a convenient location within the collection system
and serve as a shredding plant and a transfer station. Due to the
reduced bulk of shredded waste and the large capacity of transfer
vehicles, the cost of transporting the waste to the landfill can be
significantly reduced. This type of system is in use at Milford,
Connecticut; Madison, Wisconsin; Tacoma, Washington; and several
other locations.
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Placing the shredded waste in temporary storage prior to
transfer to the next operation is currently the most common removal
technique. The simple reason for this is the difficulty in synchronizing
operations at the size reduction facility with the next operation in
the system. Thus, a storage or buffer zone is needed. However, a
major problem occurs in feeding the shredded waste out of the storage
facility. The waste is easily compacted, does not readily flow, will
bridge across openings and is, in general, difficult to handle in bulk.
Only two procedures for feeding waste from bulk storage are
known to be in use. The first system is to extract the waste from the
bottom of a storage tank with an auger or screw-feeder. The storage
tank will have diverging sides to prevent bridging in the tank as material
is removed from the bottom. The auger is horizontal and travels
parallel to the bottom of the tank so that it ''sweeps'' the entire
bottom surface of the tank. Examples of this type of installation
are at St. Louis, Missouri; and Ecology, Inc., at Brooklyn, New York.
The other feeding system is a proprietary device marketed
under the trade name "Atlas Feeding Systems." In this device, the waste
is stored in an ''open'' pile inside a circular tank. Buckets that
travel around the inside circumference of the tank scoop waste from
the edge of the pile and dump it onto a moving conveyor. The device
apparently works quite successfully, although it has not yet been
installed in a large-scale, municipal solid waste system.
D. Size and Power Requirements
The machine size and the power required for a solid waste
shredder are determined by the size and nature of the input material,
the processing rate (in tons per hour) desired, and the output
particle size required. The output particle size determines the degree
of size reduction required and the minimum theoretical energy required.
The size and nature of the input material determines the minimum
horsepower required to obtain at least minimum levels of performance
without frequent jams or damage to the machine. The processing rate
determines the physical size of the machine and the total horsepower
required.
The following paragraphs present general guidelines for the
selection of machine size and horsepower. The data presented in these
paragraphs were developed from analysis of existing solid waste size
reduction installations, contacts with machine manufacturers and users,
and a review of the technical literature. The guidelines necessarily
represent averages and are therefore believed to be conservative,
i.e., use of the guidelines will yield specifications for a shredder that
is more than adequate for the desired performance.
1. Input material: Determining the size and nature of the
input material is the first step in selecting a properly sized shredder.
22
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a. Categories of. solid waste; A characteristic of
solid waste 1s that it consists of a mixture with entire automobiles
at one extreme and lightweight paper at the other. To simplify discussion
of the problem, four categories of solid waste have evolved from
common usage are in general use throughput the industry. The categories
are shown in Table 2.
b. Municipal solid waste: Current per capita solid
waste production in the United States is about 1 ton/year. Approximately
75% of this waste is light waste, about 20% is bulky waste, and about
¦5% is medium waste. (Heavy waste has been excluded because it
represents a form of waste that is generally not collected and processed
by government agencies and is not considered as municipal solid waste
in the accepted understanding of the phrase.) This 75%-20%-5% mixture
can be expected to ''show up" at the input area of a solid waste
size reduction operation that processes all municipal solid waste. This
mixture will be referred to as combined municipal solid waste.
TABLE 2
SOLID WASTE CATEGORIES
Solid Waste Category
light
Medium
Bulky
Heavy
Composition
Sorted packer truck wastes, such as-paper,
cardboard; bottles, cans, garbage, and
lawn trimmings.
Normal packer truck wastes, such as-the above
plus small crating, small appliances, small
furniture, bicycles, tree trimmingis, and
occasional auto tires.
Oversize and bulky wastes of the above plus
items such as-stoves, refrigerators, washers,
dryers, doors, large furniture, springs,
mattresses, tree limbs, and truck tires.
Large and dense materials, all of the above plus
items such as-demolition rubble, automobiles,
logs, and i3tumps.
c. Minimum horsepower requirements: Experience has
indicated that there is a minimum horsepower that is required to reliably
and efficiently process municipal solid waste within a reasonable time
and with a minimum of trouble and delay. The data shown in Table 3
represent the suggested minimum shredder horsepower for each waste
category. These data are based on analysis of existing shredder
operations.
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TABLE 3
SUGGESTED MINIMUM SHREDDER HORSEPOWER
Class of Minimum
Waste Horsepower
Light 250
Medium 400
Combined 600
Bulky 800
Heavy 2,000
2. Particle size: The nominal or average particle size of
the output material directly affects the power requirements of the
shredder. The smaller the particle size, the larger the motor required
for a given capacity or conversely, the smaller the capacity for a given
motor size. Particle size is usually specified as a sieve size, for
example a -5 in. size indicating that the product should pass through
a sieve with 5 in. square openings. For many solid waste systems,
particle size is relatively unimportant and a single specification
is given. For example, a specification for shredded waste for a landfill
might require a nominal -8 in. particle size. In another instance, such
as boiler firing, particle size is quite important and is specified as
some percentage of a nominal size and a maximum size for the remainder.
For example, the specifications for. the St. Louis, Missouri, installation
which shreds waste for a fired boiler required 95* output with a
nominal -1.5 in. size and TOGS with a nominal -5.0 in. size.
Some, limited data are available on the effects of particle
size on power requirements. These data are shown in Figure 4 which plots
unit input unit power (horsepower-hours per ton) vs particle size for
the various categories of solid waste. For example, the data indicate
that to obtain a minimal -6-in. particle size with the combined waste,
a machine with a unit power of 17 to 18 hp-hr/ton is required. The
data for Figure 4 were obtained from discussions with shredder users and
manufacturers, from analysis of existing shredder installations, and
from Ref. 2. These data are tentative and should not be considered as
final until verified by test (see Chapter V).
One other consideration must be made when determining the
power requirements for size reduction. The data indicate that power
requirements increase exponentially as particle size decreases. Thus,
for any given category of waste, there will be a particle size below
which it becomes more economical to use two-stage size reduction (i.e., a
primary and secondary shredder operated in series) than to use one large
machine. Current practice in the industry indicates that for the
combined bulky and medium waste, the minimum particle size economically
feasible in a single stage reduction is in the range of 2 in. to 4 in.
However, there is almost no available technical data (except manufacturers
proprietary design data) on this subject and no standard procedures have
24
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OUTPUT PARTICLE SIZE < In)
Figure 4 - Solid Waste Size Reduction Power Requirement
25
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been developed. Each case must be examined individually, looking at such
factors as power costs, vear factors, maintenance, labor costs, and
capital investment.
3. Total throughput (tons per day and tons per hour): In
addition to the category of waste, the particle size, and the power
requirements, the total anticipated throughput must be known before the
shredder can be sized. In many instances, this is a trivial question
since the plant may be originally conceived and designed for a certain
capacity in tons per day. This capacity is usually based upon some Input
parameter (i.e., the tons per day is known by previous collection data)
or upon some output parameter (i.e., the size reduction plant is to
supply shredded waste for a process that requires a given volume per
day).
It is also necessary to establish irtiat the nominal capacity of
the machine will be in tons per hour. This requires an analysis of such
factors as number of days per week, number of hours per day, and the
normal working schedules of the collection system. Three major factors
should be considered at this point-(1) TWenty-four hour operation is not
practical; (2) There is a lag between collection of the waste and its
delivery to the size reduction plant; and (3) There are practical limits
on' the capacity of a single processing line or facility.
Twenty-four hour operation is not feasible because the size
reduction machines tequire constant and regular preventive maintenance.
Hammers require frequent retipping, lubrication systems need refilling,
mechanical adjustments must be made, etc. In some instances, where
service application is severe (e.g., reduction to a small particle size
in a single stage operation), one shift for maintenance is required for
each shift of operation.
There is also a time lag between the collection of waste and
its delivery to the size reduction facility. The packer trucks start
each day empty as they do not normally store waste overnight. It is not
uncommoni therefore, for the first packer truck to arrive at the size
reduction facility with a load of waste 2 to 3 hr after the start of
normal working hours. The last packer trucks may also arrive well before
the close of normal working hours to allow time for return to their
headquarters. Thus, all deliveries of waste to the size reduction facility
would be made In a 5 to 6 hr period. It is common to schedule shredder
operations beyond collection hours to completely process all of the day's
input. However, due to health and safety hazards, unshredded waste is
not usually left overnight for processing the next morning. Common
practice has been to schedule the shredder for 6 to 8 hr operation a day,
5 days a week. However, most of these operations have been small plants
processing 150 to 500 tons/day and, consequently, have smaller capital
investments. As bigger and more expensive plants are designed and built
(1,000-1,500 tons/day) the trend seems to be to a two-shift operation
with 12-14 hr work periods each day.
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General experience indicates that there is a practical limit
to the capacity of a single size reduction operation. A capacity of 40
to 60 tona/hr begins to approach the limit for reasonable conveying and.
feeding systems. The volume of material represented by 40 to 60 tons/hr
begins to present such severe logistical problems that efficient
operation may require subdividing into two or more units if larger
capacities are desired.
4. Total horsepower: After all pf the above considerations
on waste categories, particle size, power requirements, and! machine
capacity have been determined, total machine horsepower is simply the
product of capacity in tons per hour and unit power required in
horsepower hours per ton. For example, a 50-ton/hr machine processing
waste with a unit power requirement of 20 hp-hr/ton would need a 1,000-hp
motor.
Most knowledgeable persons in the field of solid waste size
reduction believe that the 1,000-hp machine is an optimum size for
processing solid waste. If total horsepower requirements exceeds 1,000
hp because of capacity, then as discussed above, consideration should be
given to use of two or more processing lines. If total horsepower
requirements exceed 1,000 hp due to particle size, then consideration
should be given to use of two-stage size reduction or even three-stage
operation in extreme applications.
5. Shredder selection nomograph: The data from Table 3 and
Figure 4, and all of the above procedures, considerations and techniques
for sizing and selecting a shredder have been combined into the nomograph
shown in Figure 5. Use of the nomograph requires only knowledge of the
category of solid waste to the processed, the output particle size
desired, the capacity in tons per day and the nominal hours per day of
operation. If the tons per day are not known they can be estimated by
use of the right-hand side of the nomograph. These data represent the
average ton per day per person of waste generated in the United States
and should be used for planning and estimating only. Exact figures for
the particular locality should be used for final specifications.
Use of the nomograph requires the following steps:
a. Estimate the shredding facility capacity by
extending a line from the population to be served on the Population
Graph, through the type .of waste to be processed on the Waste Collected
Graph, to the intersection of the 8-hr Throughput Graph.
b. Determine processing rate. If an 8 hr/day shift is
anticipated, use the Tons per day intersection determined in step a
above. If a 6-hr shift is anticipated, extend the intersection with the
8 hr/day horizontally to tne 6 hr/day graph. Both the 8 hr/day and
6 hr/day graphs have the same vertical scale but are displaced
horizontally to indicate the larger machine required for a 6 hr day.
27
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Output
Size
(in)
10 r
Energy
Hp-Hr
Ton
r 100
-80
MSW
Class
Shredded
•¦Heavy
¦•Bulky
Combined
Meduim
Light
¦ 60
-40
"30
-20
10
Horsepower
10.000
7,000
5,000
3,000
2,000
1,000
700
500
300 -
200
100 L
Throughput
Tons Per Day
6 hr 8 hr
- 1 ,000-
- 800 -
- 600
Suggested
Minimum
'Horsepowers
Heavy
Bulky
- Combined
Meduim
Light
- 400 ~
- 300 -
- 200 -
- 160 -
- 120 -
- 100 -
- 80
MSW
Class
Collected
¦ -Combined
- - Meduim
Light
-L Bulky
Population
1,000's
Figure 5 - Shredder Selection Nomograph
28
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c. Estimate the unit power of the shredder by extending
a line from the desired output particle size on the output size graph,
through the type of waste to be processed on the Waste Shredded graph, to
the intersection with the Energy graph.
d. Connect the intersection point on the Throughput
graph with the Intersection point on the Energy graph. Read machine size
where the line crosses the Total Horsepower graph. Note If the total
horsepower exceeds the recommended minimum horsepower for the type of
waste to be processed. If not, use a larger machine.
Use of the nomograph will be demonstrated using as an example
a community of 100,000 population planning to shred combined solid waste
to a 5 in. particle size with 6 hr/day, 5 day/week.
a. At the right-hand size of the nomograph, extend a
line from 100,000 on the population graph, through the combined waste
point on the waste category graph, until It intersects the throughput
8 hr/day graph (380 tons/day.) Extend the intersection horizontally to
the 6 hr/day throughput graph (also 380 tons/day.)
b. At the left-hand side of the nomograph extend a line
from 5 in. on the particle size graph through the "combined'' point on
the waste category graph, until it intersects the unit power graph at
23 hp-hr/ton.
c. Connect the previously determined point on the 6
hr/day throughput graph with that on the unit power graph. Read total
horsepower of 1,250 at the intersection of the horsepower graph.
d. Note that the total horsepower of 1,250 is larger
than the 600 hp minimum recommended for combined solid waste.
29
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CHAPTER IV
NUMERICAL RATING PROCEDURE
A. Introduction
This chapter presents a numerical rating system that has been
developed for the comparison and evaluation of municipal solid waste size
reduction equipment. The rating system is intended to be used by local
government organizations that are responsible for the implementation of
size reduction in a solid waste management system. The system is designed
to provide a guide that will aid in selecting a specific size reduction
machine from two or more candidates,
B. Numerical Procedures
The numerical rating system developed is the result of
application of proprietary systematic numerical rating methods, which
have been perfected at MRI. These methods were initially designed for
use in highly specific applications in the metal fabrication field and
have been developed and expanded for general application in recent years
under the name ^Scaled Comparison Evaluation Techniques-SCET.
SCET is a remarkably effective method of collecting, articulating,
and utilizing specific reference data—statistical information, performance
data, specifications, and other so-called "hard*' data-along with
knowledgeable, but plainly subjective, human judgments (expressed in
compatible form) to produce accurate indications of the comparative merits
of candidate items being considered for selection under different sets
of circumstances or applications.
In its elementary form, SCET converts information of heterogeneous
variety into homogeneous "stuff of analysis "-zero to 10 numerical
ratings-which are easily processed manually or by computer to reveal
significant correlations and patterns. In all cases-regardless of the
nature of the product, process or proposal being evaluated-a zero rating
represents the "nadir" of evaluation, complete failure, a most
unfavorable assessment. A five represents the horizon connotation
(specifically described in every instance), the normal, the average,
equal to typical competition. A 10 represents the "zenith" of evaluation,
the best, the most favorable, clear industry leadership. Interim numbers
are used to express shades of judgment upon these specifically described
points of reference
Since these basic evaluation ratings seldom express the full
measure of available information or knowledge about items being
evaluated, companion scales are usually employed to provide ancillary
30
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assessments or qualifications. In a typical SCET evaluation, for
example, we may use a " confidence*' rating (''What is the confidence
that the evaluation is correct?'') which ranges from zero as a ''wild
guess,'' to five as a ''fair estimate," to 10 as an ''absolute known
fact,'' Most SCET evaluation models provide differential weights
according to the credibility of the ratings, either as to the reliability
of hard data or the relative qualifications of the evaluators.
A typical SCET evaluation begins with the identification of as
many factors as possible that might influence the results, and then, .the
relative importance of these factors is determined. Next, a preliminary
model (a carefully structured list) is developed which defines the zero,
five and 10 levels-the ''specific reference frames''-for all of the
individual factors being evaluated. Proper design of the model and careful
description of individual reference frames are the keys to accurate
comparative evaluation, and a generous proportion of project time is
spent here-learning what data to include and how to use the data so that
answers can be fairly expressed as numerical ratings between zero and 10.
Next, trial rating sessions are conducted to test the relevance
of the factors and the fairness and validity of evalution reference
scales, as they apply to performance data, specifications, and subjective
opinions based upon actual operating experience. Criticisms of.the
preliminary model are openly invited during these trial rating sessions.
All the knowledge gained in the preliminary phases is used to design a
final model which addresses the many factors involved, properly balanced
and weighted.
C. Development of the Numerical Rating System
Preliminary rating model; In the process of collecting data
for the equipment inventory, numerous contacts were made with equipment
manufacturers, size reduction plant operators, engineering consultants,
and government agencies. All of these people were asked to list the
factors they believed should be considered in selecting a piece of size
reduction equipment. All persons were instructed to list all possible
factors, no matter how minor, and to also include any special factors that
may be unique to their experience. The main objective at this time was
to develop as complete a list as possible for later analysis. No attempt
was made at this time to evaluate or weigh the comments or to group
them into an organized format.
The factors that were developed as a result of the above
contacts were combined with those contributed by the project staff to
form an initial list. This list included over 60 factors which were
grouped into two distinct categories-Purchase Aspects and Operating
Aspects. These factors are presented in Tables A and 5. The techniques
of SCET were applied to the list by the program staff to determine the
relative importance of each factor. As a result of the initial SCET
analysis, the factors were reorganized into a new format containing
five groups:
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a. System Requirements Profile; The potential capability
of the machine, as determined by analysis of the manufacturer's advertising,
to inset or exceed the minimum performance requirements of the customer;
b. Suitability: The general capability of the. machine
to be integrated into the customers' solid waste management system;
c- Manufacturer's Reliability: The manufacturer's
financial strength, relevant experience, and general reputation;
d. Specification Fulfillment J The known technical
performance of the machine witti regard to the technical specifications
of the customer; and
e. Economy Index? The cost of purchasing, installing,
and operating the machine.
TABLE 4
PURCHASE ASPECT FACTORS
Machine Weight
Machine Size
Rated Tons/Hour
Kated Tons/Shift
Batch: Process
Input Location
Unique Design Features
Horsepower
Delivery Cost
Service Policy Availability
Delivery Schedule
Spare Parts Availability
Manufacturers Reputation
Existing Installations
Special Installation Requirements
Output Particle Size
Size Reduction Surfaces
Weather Treatment
Contours Process
Output Location
Control Systems
FOB Price
Installation Costs
Type of Motor
Performance Bond
Fire Control Systems
Field Service
Safety Features
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TABLE 5
OPERATING ASPECT FACTORS
Actual Capacity (tons/hour)
Unit Power (hp-hr/ton)
Maximum Output Particle Size
Maximum Input Particle Size
Tons/Repair
Backfire (ejection.out the
input)
All-Weather Operation
Labor Costs
Repair Skills Required
Power Assist Devices
Access for Maintenance
Noise, Smoke or Odor
Rotor Inertia
Weight
Effect of Moisture Control
Motor Machine Interface
Rejection of Nonprocessables
Peak Power
Power Cost
Number of Personnel
Operating Availability
Lubrication Systems
Complexity of Partis
Operating ''Headaches''
2. Major revision of the preliminary model; The techniques of
SCET development were again applied to the preliminary model.
Knowledgeable persons, including equipment manufacturers, users, and
consultants were interviewed to gain their input into the rating
procedure. The interviews were recorded for later review by the entire
project staff. The recorded interviews wete reviewed several times by
the program staff and it was found that several significant trends in
the interviews were apparent. These trends were:
a. Most of these knowledgeable persons-ineluding
equipment manufacturers and users-are of the firm opinion that only
the hammermill can successfully and reliably process a material with
the widely variable characteristics of municipal solid waste. Hammermills
are the only type of solid waste size reduction equipment now being used
in existing installations or being considered for future installations.
b. All hammermills currently being manufactured in the
United States are either vertical shaft or horizontal shaft designs.
Some persons contend that there are significant differences in the
technical and economic performance of these two types of machines.
c. Most of these people believe that there will be
little or no measurable difference in the performance of various
machines of the same type (but from different manufacturers) that
are being considered in response to the same set of performance
specifications. For example, there will be no significant differences
in the technical capabilities of three or four different horizontal
shaft hammermills that have been proposed for a given application
that is adequately described by proper performance specifications.
d. Variations in the cost of operating different size
reduction machines cannot be fully attributed to differences in the
33
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machine's performance. All machines of the same type (i.e., horizontal
or vertical shaft) operate at about the same mechanical efficiency,
use the same amount of power, and experience the same amount of wear
per ton of throughput. Many of the cost differences can be directly
attributed to the management policy of the facility and the accounting
procedures used. Factors in this category include availability
(working hours), service and maintenance practices, number of personnel,
power costs, safety standards, etc. Although costs of these items can be
measured, comparison of data from two different installations may not
be valid because of different operational policies.
e. Any purchaser of a size reduction machine is
interested in only three questions:
(1) Is the manufacturer a reputable organization?
(2) Is the machine adequate in size and power
to do the job?
(3) What dues it coat to buy and operflf-fi
the machine?
The five factors (''a" through ''e'') described above
are considered major findings of this report. They represent a general
opinion held by many knowledgeable people in the field of size reduction.
These factors led the project staff to the conclusion that the
Numerical Rating Procedure would be of most use if it helped the user
answer the three questions in item "e". As a result, major revisions
in the preliminary rating model were made. Several of the more
specific technical factors were eliminated. Because of the many
similarities in the design and performance of the various types of
hammermills, emphasis was shifted from technical considerations to
answering the question: "Is the manufacturer a reputable organization?''
Technical considerations were reduced to rating the machine's size,
power, and capacity against the available state-of-the-art design
data and a test program was developed to improve the accuracy of the
design data. Because of the variations in operating costs, economic
considerations were limited to purchase cost and maintenance cost.
Thus, the final rating procedure consists of 18 factors
arranged in three Indexes that can be considered individually or
collectively. The three indexes are the Manufacturers Index (factors
that relate to the technical and financial qualifications of the
manufacturer), the Technical Index (factors that relate to the
technical performance of the machine), and the Economics Index
(factors that relate to the cost of purchasing and operating the
machine). The final model was again submitted to various knowledgeable
persons for their opinions and comments. A list of the people who
participated in the development of the numerical rating procedure is
presented in Appendix I.
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D. Summary of the Numerical Rating Procedure
The numerical rating procedure consists of three individual
indexes that yield comparative ratings of two or more size reduction
machines in three areas—a Manufacturer's Index, a Technical Index,
and an Economic Index. Each index contains several ratings that
consider specific aspects within the general topic. The complete text
of the Numerical Rating Procedure for Comparative Evaluation of Solid
Waste Size Reduction Equipment is presented in Appendix II. The
following paragraphs present a brief review of the format and
content of the system.
1. Section I ~ Manufacturer's Index: This index is
designed to provide a relative rating of the technical and financial
qualifications of the manufacturer of a size reduction machine. The
rating will provide a measure of the capability of the manufacturer to
design, build, install* and service a reliable piece of equipment. The
index is composed of six Individual ratings: Financial Strength,
Shredder Experience, Existing Installations, Equipment Endorsements,
Service Endorsements, and Industry Reputation.
2. Section II ~ Technical Index! This index is designed to
provide a relative rating of the engineering expertise demonstrated in
the design and fabrication of a size reduction machine. The rating
will provide a direct measure of the capability of the machine to
meet the required performance specifications of the customer. The
index is composed of nine individual ratings: Horsepower, Input
Limitations, Maintenance Intervals, Machine Weight, Rotor Inertia,
Design Simplicity, Wear Adjustment, Power Assists, and UnproceBsables
Rejection.
3. Section III - Economic Index: This index is designed
to provide a relative rating of the capital investment and operating
expenses related to a size reduction machine. The rating will provide
a measure of the effects on the net cost (in dollars per ton) of
operating a size reduction facility that is directly incurred in the
purchase and use of each machine. The Index is composed of three
ratings: Installed Cost, Operating Costs, and Service Expectation.
E. Application of the Numerical Rating System
The numerical rating system is intended to be applied
to two or more machines being considered for the same application.
It is assumed that the user will have developed a comprehensive set of
machine performance requirements including capacity (tons per hour),
waste category, particle size, etc. In response to these performance
specifications, he will receive bids from two or more manufacturers.
The system represents a carefully structured list of
questions that should be answered for each machine under consideration.
Each question is "answered" by rating, on a scale of zero to 10,
the given aspect of the machine or its manufacturer.. Some of the
ratines can be determined objectively by the application of predetermined
35
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guidelines. They require no Interpretation or analysis on the part of
the user. Most of the ratings, however, are subjective. They require
that the user solicit value judgments from knowledgeable people.
Obtaining accurate value judgements is the most critical
aspect of the rating procedure. It .is essential that the user make
sure each person understands the rating criteria and how to apply
them. At the samd time, the user should present the criteria fairly
and honestly with no bias or attempts to slant the answers. It is also
essential that the criteria be presented in the same manner to each
person being questioned. Only in this way can accurate and comparable
data be obtained.
By following certain established procedures, much of the
guesswork inherent in.such procedures can be eliminated. The following
instructions present general guidelines that the user should observe
when obtaining ratings for the subjective factors in the numerical
rating procedure.
1. Develop a list of knowledgeable people who are qualified
to participate in the rating procedure, in general, this list will
consist of manufacturers, users, and consultants. Names of manufacturers
and existing installations can be found in the equipment inventory
(Ref. 1). Names of additional users or consultants can often be obtained
from each contact. The user should also try to include different
persons from the same source, for example, the plant manager, the
plant engineer, and the plant operator at an existing facility.
2. Contact each person on the list and request their
assistance. Explain to them who you are, what you are doing, and
why you want their help. Assure them that all conversations are
strictly confidential.
3. Use an individual worksheet similar to the one shown
in Figure 6 to record the rating for each person. If possible,
tape record all conversations for additional analysis.
4. Record all data on the data sheet yourself. Do not
ask the person to fill out the rating sheet:.
5. Ask each question individually. Thoroughly explain
what the question is and what it is Intended to measure. Explain
the rating criteria and make sure the 0, 5, and 10 level criteria
are understood.
6. For eacn question, ask the person to rate the machine
on a scale of zero to 10 using the rating criteria presented with
the question.
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Machine Manufacturer
Make and Model No.
Source (Person Supplying Ratings)
Date Evaluator ;
Factor Rating Confidence Rating
Manufacturer's Index
1. Financial Strength
2. Shredder Experience
3. Existing Installations
4. Equipment Endorsements
5. Service Endorsements
6. Industry Reputation
Technical Index
7. HP at Spec Tons/Hour
8. Input Limitations
9. Maintenance Intervals •
10. Machine Weight
11. Rotor Inertia
12. Design Simplicity
13. Wear Adjustments
14. Power Assists
15. Unprocessable Rejection
Economic Index
16. Installed Cost
17. Operating Cost, $/Ton
18. Service Expectation
Figure 6 - Numerical Rating Procedure Individual Worksheet
37
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7. Each person should answer every question, even
those he may not be knowledgeable about. He should then be asked
to evaluate the strength of his answer. A simple procedure Is to
ask him to rate his own answer (the confidence rating on Figure 6)
from zero as a "wild guess," to 5 as a "fair estimate" to 10
as a known fact. These data can be used as weighting factors
when averaging the ratings of several persons to the same question;
8. After completion of all questions, review the entire
set of questions. Many persons may wish to make minor revisions of
their ratings.
9. Try to obtain ratings from at least three persons
for each question. Additional ratings should be sought if the Initial
three show widely differing values, or if the raters themselves
have qualification ratings of less than 5.
10. Use a data sheet similar to the one shown in Figure 7
to determine the final rating for factors where two or more individual
ratings are obtained. The rating and confidence rating from each
evaluator for a factor are transferred from the individual worksheet
(Figure 6) to the Factor Average worksheet (Figure 7). For each
machine being evaluated, there will be 18 each of Figure 7 (i.e.,
one for each of the 18 factors).
11. Examine the pattern of ratings that are received.
Disregard or de-emphasize the ratings of any one person if they are
consistently out of line with the general trend.
F. Evaluation of the Results
1. Summary Sheet: The summary evaluation sheet for the
Numerical Rating Procedure is shown in Figure 8. The 18 rating
factors are listed on the left-hand side of the sheets. Spaces are
provided to enter the individual ratings for each factor for up to
eight machines. Each machine is identified by a code letter, and
space for the code identification of the machine manufacturers is
provided in the lower right-hand corner of the sheet. The ratings
from the individual rating Factor Average sheets (Figure 7) should
be transferred to this Summary Sheet for evaluation of the results.
Additional spaces are provided on the Summary Sheet for entering
individual index subtotals and the total ratings.
After the individual ratings for each machine are entered
on the data sheet, the index subtotals are computed. The index
subtotal for a machine is simply the arithmetic sum of all the
individual ratings within the index.
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2. Minimum qualifications: It is the opinion of the project
staff that each machine should score above a certain minimum total
for each index to be considered for further evaluation* Any machine
that scores significantly below average on any factor represents a
questionable Investment and consideration should be given to eliminating
it from further evaluation. The following minimum totals for each
index are recotnmended: Manufacturer's Index-30 points of a possible
60; Technical Index-35 points of a possible 90; Economic Index-12
points of a possible 30. These minimums should be considered as
guidelines and adjusted, if necessary, to fit each user's special
needs. The purpose of the minimum's is to draw attention to a potential
danger, not to arbitrarily eliminate any one machine.
3. Weighting factors: The Numerical Rating Procedure
consists of 18 individual ratings grouped in three categories. The
18 ratings are not of equal importance and, further, their relative
Importance will vary from one situation to another. The user will
have to determine the true importance of each rating as it applies
to his situation. However, experience has indicated that a fair
approximation can be obtained if each factor is treated as equal and
a multiplier applied to the index subtotal. The recommended multipliers
and their effect on the relative weight of the index are shown in
Table 7. These rating factors tend to emphasize the Manufacturer's
Index; however, it was the opinion of the project staff that a fair
application of this procedure would indicate that the greatest difference
will occur in the Manufacturer's Index, and therefore this index
should carry a high weight.
TABLE 7
RELATIVE WEIGHT OF INDIVIDUAL INDEXES
Index Number of Ratings Index Multiplier Relative Weight
Manufacturer
6
2
12
Technical
9
1
9
Economic
3
2
6
Total
27
4. Sample Rating: It will be helpful to make a sample
evaluation to explain the rating system and how it can be used to
greatest advantage. For example, it is assumed that a potential
purchaser of a machine has developed an adequate set of performance
specifications, requested bids of all eligible manufacturers and
receives five bids. The user has then applied the numerical rating
procedure and developed the basic ratings for each machine, entered
them on the data Summary Sheet and calculated the index subtotals
39
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Factor Date_
Evaluator
2.
3.
4.
Source Rating Confidence Total
1. X
5. X
6. X
Average Rating = Total
N x 10
where N = Number of sources
Total =
* Transfer this value to summary data sheet.
Figure 7 - Numerical Rating Procedure Individual Factor Average
40
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MUNICIPAL SOLID WASTE SHREDDER EVALUATION RATING SHEET
Evaluates
Date
MACHINES
A B C D EF.GH
No. Rating Factor
1. Financial Strength
2. Shredder Experience
3. Existing Installations
4. Equipment Endorsements
5. Service Endorsements
6; Industry Reputation
7. HP at Spec Tons/Hour
8. Input Limitations
9. Maintenance Intervals
10. Machine Height
11. Rotor Inertia
12. Design Simplicity
13. Wear Adjustment
14. Power Assists
15. Unprocessable Rejection
16. Installed Cost
L7. Operating Cost, $/Ton
18. Service Expectation
Index
INDEX SUBTOTALS Multipliers
30 ________ x 2
MIN* ABCDEFGH
Manufacturer's Index
35
MIN* ABCDEFGH
Technical Index
x 1
. 12
MIN* A B C D E F G
Economic Index
x 2
TOTAL RATINGS
ABCDEFGH
Machine
Code Identification:
* Minimum acceptable Index.
Figure 8 - Numerical Rating Procedure Data Summary Sheet
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and total ratings. The example data are shown In Figure 9. The question
now is, "What does this information reveal?''
Bidders A and B are marginal (2 and 0) in the aspect of
financial strength. B has a dangerous lack of experience in manufacturing
and selling the desired kind of equipment. A and B are deficient
in service endorsements and reputation,' a common penalty for lack of
size. A tally of Manufacturers Index ratings for A (24) and B (11)
shows that both companies have fewer than the minimum number (30) of
points recommended for further consideration. Unless there is some
other reason to continue their evaluation, it may be wise to close
their files at this juncture, and do not bother to evaluate them
further. Even if all of their subsequent aspects were to be rated
as 10's, it may be dangerous to deal with A and B on this contract.
Bidder C has no experience (0) in the municipal waste
shredding field; and this weakness pulls its Manufacturer's Index
down to the bare minimum (30 points) required for further consideration.
Judging by its ratings for installed cost (8) and service expectation
(10), it is probably a local firm-but the pattern of ratings in the
Technical portion discloses unmistakably that the company does not
make machinery rugged enough for waste. Unless there are very extraordinary
overriding considerations, do not involve the community's basic
solid waste processing problems in a local firm's research and
development program.
In the presence of proposals from D (196 total points)
and E (192), Bidder C (140) should be rejected.
Up to this point, the evaluation rating system has been
used merely as a screening mechanism. It is more than that. Bidders
D and E, at 196 and 192 total points, respectively, are for all
practical purposes equally qualified. The evaluation system contains
many plainly subjective ratings which are not accurate to within plus
or minus 1 on a zero to 10 scale. Subjective evaluation simply does not
deal in measurements more sensitive than that. Differences of 5% in
the total ratings are probably not as significant as some of the
differences in the patterns of aspect ratings.
Examine the differences between D's and E's aspect ratings,
very carefully, with a view toward the municipality's particular
needs:
Bidder E has done more municipal shredding; and since it
is a tough pioneering ^field, this might explain its 8's
(compared with'D's 10's) in equipment endorsements and
industry reputation. The company's 3 (vs 5) in horsepower
at specification, tons per hour and its 4 (vs 7) in input
restrictions may simp ly'-re fleet judgment which comes with
the greater experience in processing municipal solid waste.
The E unit is generally at a disadvantage in the technical
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MUNICIPAL SOLID WASTE SHREDDER EVALUATION RATING SHEET
Evaluator Harold Donnelly
Date 7/17/73
No. Rating Factor
1. Financial Strength
2. Shredder Experience
3. Existing Installations
4. Equipment Endorsements
5. Service Endorsements
6.- Industry Reputation
BASIC RATINGS
ABCD EFGH
2 Q. 11 fL
20il£i 10
1121 1_ _ _
5 6 7 10
3 2 4 8
4 2 5 10
8 .
IP.
8
7. HP at Spec Tons/Hour x x '2 J5 ^
8. Input Limitations £ ]_ ;4^
9. Maintenance Intervals' _ _ 2 A Z
10. Machine Weight 2 7 6
•11. Rotor Inertia 2 8 5_
12. Design Simplicity 2. Z. .
13. Wear Adjustment 4 10 7^
14. Power Assists ^ £ £
15. Unprocessable Rejection L,
16. Installed Cost 8 5 5
17. Operating Cost, $/Ton 3 ^5 6
18. Service Expectation 10 7_
INDEX SUBTOTALS
Index
Multipliers
30 _ 30 50 51
MIN* A BCDE FGH
. Manufacturer's Index
x 2
35 x.a. 29 to 54 _ . _ _ xi
MIN* A BCD E F G H
Technical Index
12 x ' x . 22 15 18 _ _ • _
MIN* A BCD E . F . G H
Economic Index
x 2
TOTAL RATINGS
x x 141 196 1J2_
ABCD EFGH
Code Identification:
A Worldwide Shredder
B Ajax Size Reduction
C National Crusher
D Jones and Amer
E Shredders, Inc.
F
* Minimum acceptable Index.
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group of aspects, except for slight edges in maintenance
Intervals and power assists. The economic aspects give a
slight advantage to E. Which would you choose, D or E?
Probably either one would be a safe choice-so the decision
might be swung by considerations which are subtle and
beyond the scope of a formal evaluation. Our own preference
would go to E because of its greater experience in municipal
waste processing and its high service endorsements and
service expectations.
Note also that the 3 in horsepower might merely be a
statistical aberation due to C's rating of 7-and C has be rejected.
It is possible that E would be 7 or 8 (and D a 9 or 10) on a different
list of candidate shredders.
Regardless of which one is chosen, the pattern of ratings
will continue to be a useful monitoring tool through the periods of
purchase, installation and early operations* The ratings.comprise a
working roadmap of potential pitfalls in either case. If I) is chosen,
note the weakness in municipal waste experience—and immediately get
on the phone to managers of present installations and find out about
their problems and how they resolve them. Make probing inquiries
about horsepower at specification performance levels and maintenance
intervals. And, set in motion a continuing effort to improve the
service situation and establish several key personal service contacts
within the company.
If the choice is E, see what can be done to accommodate-or
relieve-the input restrictions, and whether the low rating In the
horsepower rating (3) is merely, the result of engineering conservatism
in designing surge capacity with a light rotor.
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CHAPTER V
SIZE REDUCTION TECHNICAL AND ECONOMIC PERFORMANCE TEST PROGRAM
A. Introduction
This chapter presents a test program to develop accurate and
impartial technical and economic performance data for size reduction of
solid waste. The object of the test program is to verify the technical
design data presented in Chapter III, Paragraph D, to replace it where
inaccurate, and to develop net operating cost factors. Such data are
needed to intelligently plan, design, and fabricate a size reduction
facility. Limited technical performance data for shredding of solid
waste are available, but the majority have been accumulated from
different sources and under uncontrolled conditions. Such data are
subject to question and should only be used to indicate trends. The
operating cost data that are available have also been unreliable
because the information has been generally supplied by facility
operators and is subject to various "bookkeeping" practices.
Accurate technical and economic data are known by private processors,
but they consider such data proprietary and confidential and will
not make it available. Therefore, there is an obvious need for accurate
and impartial information that is fully available to all organizations
or municipalities considering size reduction of solid waste.
B. Recommended Testing Facilities
The original concept of the test program was to have a
field facility where individual machines could be thoroughly tested
to accurately measure their technical and economic performance. Very
early in the conduct of this study, it became apparent that individual
testing of each machine by each manufacturer was neither feasible nor
desirable. Such a concept was found to be costly, time consuming,
cumbersome, and inefficient. The capital equipment investment alone
was estimated to exceed $2,000,000 and studies indicated that the
support equipment, especially conveyors, would not be adaptable to all
possible shredder designs.. However, the most Important fact was that
the cost of a complete test on a single shredder was estimated to be
approximately $25,000. Since the purchase price of the machines is in
the $50,000 to $100,000 range, it was believed that no manufacturer
could afford to participate in the test program. Thus, need for an
alternate test program was indicated.
As the program continued, one important conclusion about
solid waste shredders developed and became a major factor in the
formation of a test program. That conclusion, discussed in Chapter IV,
45
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Faragraph C, was that all shredders of the same type and size would
perform at about the same technical level when operated at equal
conditions. This meant that for a given installation, similar shredders
from different manufacturers would exhibit similar technical levels
of performance. Thus, it should only be necessary to establish these
performance levels once for each type of shredder. Fortunately, both
privately and publicly owned or supported installations with different
types and sizes of shredders are already in existence in the United
States.
1. Public installations: In the process of preparing the
equipment catalog, it was determined that many of the solid waste size
reduction facilities were partially supported by public funds-either
federal, local or state taxes. It would therefore appear that these
sites would be logical choices as test program facilities. They are
already in operation, with experienced personnel and full support
equipment, and frequently are dependent on continued government
funds. Further, many are demonstration grant projects studying the
technology of size reduction and therefore already set up to perform
experiments and tests. (However, some of these units are very small
and may not be suitable for the test program.)
We are fully aware that the EPA cannot simply force these
existing facilities to participate in a test program. We are also
aware that legal and procedural difficulties may prevent some that
would desire to participate from doing so. However, the use of those
facilities is an economically acceptable procedure for developing the
technical and economic data needed. We therefore recommend that the EPA
determine what financial and legal arrangements will be required to
conduct the test program presented in this chapter at selected solid
waste size reduction facilities in the United States that are supported
by public funds. After a determination of the arrangements and costs
associated with this approach, it can be compared with the arrangements
and costs required for the use of private facilities as discussed
in the next section.
2. Private installations: Many of the larger manufacturers
of size reduction equipment maintain test facilities. They have
accumulated considerable data and operating experience in evaluating
their own equipment and also the equipment of competitors. Those
companies that do not maintain their own test facilities, often have a
"captive" (wholly owned) processing installation or a cooperating
private installation that they can use for testing and evaluation
purposes. Thus, a second solution to the problem of generating
technical and economic performance data would be to have the manufacturers
conduct the test program at their own facilities at government
expense with government supervision of testing procedures and data
collection. This proposed approach represents the least difficult
method of collecting data. However, manufacturers consider technical
and economic performance data for their machines as proprietary and
classified information and may, therefore, be unwilling to participate.
46
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A thorough study of the market would be required to determine which
manufacturers have test facilities and are willing to participate.
C. Summary of the Test Program
1. Program intent: The test program is designed to develop
accurate technical and economic performance factors for solid waste
.ize reduction equipment. The resultant technical data will also be
ised to verify the technical guidelines used as base-line data for
:he numerical rating procedure.
Technical performance is measured in terms of the capacity
>f the machine in tons per hour and net tons per day. Factors that
iffeet capacity are: unit energy (horsepower-hours per ton), category
if waste, particle size, feed rate, and moisture content. Size
eduction machines are normally designed to reduce a given tonnage
er hour of a given type of waste to a given particle size. The
lachine is then sized by determining the unit energy in horsepower-hours
er ton and multiplying by the desired tons per hour to obtain total
iorsepower required. Therefore, to be useful, technical data should
e presented as graphs showing unit energy vs particle size with
moisture content and type of waste held constant. Additional graphs
are needed to show the effects of variations in type of waste or
moisture content.
Economic performance is measured in terms of the cost,
in dollars per ton, of operating the size reduction facility. This
cost figure normally includes amortization of capital investment,
power costs, labor costs, and maintenance costs. The test procedure,
however, cannot accurately evaluate amortization or labor costs.
Both of these items depend more on the management policies of an
operation than upon the mechanics of the machine. Therefore, the
test procedure is only designed to measure power costs and maintenance
costs. The factors that affect these costs are unit energy (horsepower-hours
per ton), tons per scheduled repair and cost per scheduled repair. A
scheduled repair is defined as a repair that is predictable and
occurs at some repeatable interval, e.g., resurfacing or replacement
of major wear surfaces.
D. Technical and Economic Performance Tests
1. Test programs: Two test programs have been developed-the
recommended program and a minimum effort program. Either program can be
conducted at public sites or at private sites. The individual tests to
be conducted within each program are identical.
a. The recommended test program: The recommended test
program consists of conducting complete individual performance tests
and collecting data at five test facilities. The five types of facilities
recommended are:
(1) An Installation with .a horizontal shaft
hammermill and a large output particle size. Examples are San Diego,
California, and Tacoma, Washington.
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(2) An installation with a horizontal shaft
hantmermlll and a small particle size. An example Is St. Louis, Missouri.
(3) An installation with a large vertical shaft
hammerraill. Examples are Milford, Connecticut, and Vancouver, Washington.
(A) An installation with a small vertical shaft
hammermill, an example is Madison, Wisconsin.
(5) An installation with two-stage reduction.
Examples are New Castle County, Delaware, and Ecology, Inc., Brooklyn,
New York.
The recommended program is estimated to require a 20-month
performance period.
b. The minimum effort program: The minimum effort program
consists of conducting complete individual tests at two test facilities-a
large horizontal shaft hammermill installation and a large vertical
shaft installation. The minimum effort program is designed to develop
technical and economic performance data for solid waste size reduction
machines typical of machines that would be used in a large volume
municipal installation.
The minimum effort program is estimated to require an
8-1/2-month performance period.
2. Selection of test sites: Following are the desired criteria
for the test sites to be used for performance of the test program:
a. The site should be an existing public or private
solid waste reduction facility or an acceptable private test facility.
The installation shall have adequate conveying systems to feed the
shredder at desired feed rates.
b. The supply of solid waste shall be adequate to assure
normal operation at or near design levels at all times during the test
program.
c. The facility operator must give assurance of full
cooperation.
d. All operating and maintenance personnel should have
extensive experience with the equipment.
e. Suitable truck scales for measuring the weight of
solid waste delivered by each truck, should be available.
f. Suitable test facilities are required at the site
including a field office for storage of test equipment and data records,
and utilities, Including telephone, power, and sanitary facilities.
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g.. The site should be in a moderate climate location
or testing should be conducted in fair weather seasons.
h. The site should be geographically close to commercial
testing laboratories that can make moisture content and particle size
measurements.
3. Controlled test procedures; Following is a general
description of the proposed tests and the estimates of the time required
to conduct each test. The complete text of the test procedures is
presented in Appendix II. These estimates were prepared after careful
consideration of the data desired and the equipment to be tested.
However, there are several major variables that cannot be accurately
determined until the sites have been selected and evaluated. For example,
the support facilities and conveyor system must be sufficient to
adequately serve the shredder during the test. Also, availability of
suitable equipment and accessories is not positively known.
Test Procedure No. 1 - Technical Performance Tests
The technical performance test is designed to determine the
unit energy required for size reduction of solid waste. The test consists
of processing a measured quantity of waste under controlled conditions
and measuring the processing time in hours and unit power in
horsepower-hours per ton.. The data are then reduced to horsepower-hours
per ton for a type of waste, moisture content, and particle size. Tests
will be conducted at different feed rates to determine if feed rate
affects energy requirements or particle size. Three feed rates are
recommended-at design capacity and at plus or minus 25% of design
capacity (manufacturer's recommendations). The three tests should be
conducted once a day for 2 weeks (10 working days) to provide two
replications of the normal weekly variation in waste. It is estimated
that the tests at one facility can be completed in 4 weeks using one
test engineer and one test technician.
Test Procedure No. 2 - Economic Performance Tests
The economic performance test is designed to determine the
unit cost in dollars per ton for power and maintenance of normal wear
items. The test consists of accurately measuring and recording the weight
of solid waste material processed under controlled conditions, the
frequency of scheduled repairs, and the labor and materials required for
each repair. The tests should be conducted for sufficient time to cover-
three normal maintenance periods. The data are then reduced to determine
tons per required maintenance, labor and materials per repair and thus,
dollars per ton for maintenance. It is estimated that the test can be
completed at one facility in 4 weeks using one test technician.
E. Performance and Evaluation of Test Program
t. Contractor? An Independent contractor should be selected
to conduct the test program and evaluate the test data. The contractor
should be impartial, with no vested Interest or bias towards a particular
brand or type of size reduction equipment. The contractor should have
49
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an extensive background in the field of solid waste technology*
particularly in the areas of design, operations, and analysis of size
reduction of solid waste.
The specific background experience of the contractor should
include:
a. A working knowledge of the equipment and machinery
normally found in a solid waste size reduction facility;
b. Technical expertise in conducting field programs,
collecting and analyzing field data, and issuing written reports;
c. Working contacts with manufacturers of size
reduction equipment;
d. An experienced engineer to serve as program
director, and adequate technical and administrative support staff; and
e. A past history of satisfactory performance in
government contracts.
There are numerous consultants and technical institutions
that can respond to the above qualifications. The program can also be
conducted in-house by the United States Environmental Protection Agency,
Office of Solid Waste Management Programs. It is recommended that
equipment manufacturers be specifically excluded from conducting the
test program.
2. Test program staffing; The estimated staffing of the
test program is shown in Table 8. The estimates are shown for both the
recommended program and for the minimum effort program.
The program staff shall consist of a program director, test
engineer, and test technician. The program director should be a senior
staff engineer for the contractor. He should have a background in both
field and management phases of experimental programs. He should have a
thorough knowledge of solid waste processing and handling. The program
director should be supported by at least one test engineer whose
experience and background are similar to the program director.
The test engineer will be required to be at the test site full
time during the technical performance tests. If tests at different sites
are scheduled simultaneously, more than one test engineer will be
required.
The test technician will be required at the test site full
time to assist the test engineer during the technical performance tests.
The test technician will also be at the site full time to conduct the
economic performance test and report the data to the test engineer.
50
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TABLE 8
ESTIMATED PROGRAM STAFFING
Man-Months Effort
Program Planning
Project Director
Test Engineer
Technical Performance Test
Project Director
Test Engineer.
Test Technician
Economic Performance Test
Project Director
Test Engineer
Test Technician
Report Preparation
Project Director
Test Engineer
Totals
Project Director
Test Engineer
Test Technician
Recommended
Program
0.5
1.0
1.5
3.5
7.5
1.0
1.0
5.0
0.75
0.50
3.75
6.00
12.50
Minimum Effort
Program
0.3
0.5
0.6
1.4
3.0
0. A
0.4
2.0
0.50
0.25
1.80
2.55
5.00
3. Program schedule: The times required to complete the
recommended and minimum effort test programs are 20 months and 8.5
months, respectively. These estimates are based on the assumption that
tests at individual sites will be scheduled consecutively with a 1-month
delay between each test. The scheduling is as follows:
Time in Calendar Months
Project Planning
Conduct Tests at Individual Sites
Report Preparation and Submittal
Recommended
Program
3
15
2
Minimum Effort
Program
1.5
6
1
Total
20 months
8.5 months
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These total times can be shortened considerably by performing
simultaneous testing of two or more sites.
4. Program cost estimates: The estimated cost of conducting
the test program is presented in Table 9. The program costs are
developed based on the cost of an individual site test (five for the
recommended program, two for the minimum effort program) with the
project planning and report preparation time prorated.
TABLE 9
INDIVIDUAL TEST COST
Program Director 0.75 month at $1,600 m $1,200
Test Engineer 1.20 months at 1,400 ¦ 1,680
Test Technician 2.5 months at 700 = 1,750
Total $ 4,600
Overhead, Salary Related, and G&A at 270% 12,500
Travel, Five Round-Trips at $150/Trip 750
Subsistence - 60 Days at $30/Day 1,800
Test Equipment Rental 500
Testing Laboratory Services 500
Reproduction and Supplies 1 ,000
Total $ 21 ,150
TEST PROGRAM COSTS
Recommended Program five tests at $21,000 $105,000
Minimum Effort Program two tests at $21,000 42,000
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CHAPTER VI
CONCLUSIONS AND RECOMMENDATIONS
A. Conclusions
The following paragraphs present a summary of the major
conclusions of this program.
1. Size reduction of municipal solid waste is an emerging
technology. There is, as yet, no assembled body of knowledge on the
planning, design and fabrication of facilities and equipment, or on the
economics of purchasing and operating a facility.
2. Size reduction of municipal solid waste is a rapidly
growing technology. Most manufacturers firmly believe that sales of
size reduction equipment for application in solid waste systems will
significantly increase in the next 5 years.
3. The major application of size reduction in the near
future will be in landfill disposal systems. Size reduction is especially
suited to landfill operations because it increases landfill capacity,
reduces odors, blowing, and strewing, eliminates voids and reduces
vermin infestation, and eliminates the need for soil cover.
4. The long-term future of solid waste size reduction is in
resource recovery system. Size reduction produces a. uniform particle,
size, increases heterogeneity, and reduces the bulk of solid waste. All
of these factors can increase the efficiency of many of the currently
proposed resource recovery systems.
5. There are 10 basic types of size reduction machines and
many of them can theoretically be used for size reduction of solid
waste. However, only two types-the hammermill and the wet pulper-are
considered practical.
6. Hammermills are the principal type of solid waste size
reduction machines now being used or considered for future installations
in the United States.
7. The wet pulper is not usually considered a primary
machine for size reduction. Although one installation is in operation in
the United States, most wet pulper installations now being studied or
proposed also include a size reduction machine ahead of the pulper.
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8. Hammermills are either vertical shaft or horizontal shaft
type designs. There are distinct differences in their technical and
economic performances.
9. Most knowledgeable persons believe that there will be no
significant differences in the technical performance of similar machines
of the same type made by various manufacturers.
10. Reliable technical performance data for hammermills used
in solid waste size reduction are not available. Some equipment
manufacturers possess limited data on the performance of their
machines, but consider the data proprietary and confidential.
11. Economic performance data for hammermills used in solid
waste size reduction are available but unreliable. The data are usually
reported in dollars per ton of waste and do not identify the cost of
individual factors, such as capital investment, amortization, power,
operating costs, and maintenance cost. Variations in the data are often
due to bookkeeping practices, management practices, and Inaccuracies in
data collection techniques.
B. Recommendations
The following paragraphs present recommendations for future
EPA work related to size reduction of municipal solid waste.
1. An experimental test procedure should be conducted to
develop reliable technical and economic performance data for size
reduction of solid waste. Chapter V of this report presents a comprehensive
description of a recommended test program, including detailed test
procedures and cost estimates.
2. Public and private organizations planning solid waste
size reduction facilities should be encouraged to use the numerical
rating procedure presented in Chapter IV. Use of the procedure can
guide the organizations in the selection of a reputable dealer and
proper equipment.
3. There is a demonstrated need for a comprehensive
state-of-the-art report on planning, designing, building, and operation
of a solid waste size reduction facility. The report should include a
thorough systems analysis of the facility and all of the individual
components.
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APPENDIX I
PERSONS INTERVIEWED CONCERNING THE NUMERICAL
RATING PROCEDURE
R. W. Taylor
Joy Manufacturing
Denver, Colorado
Arsen Darnay
Resource Recovery Division
EPA
Washington, D.C.
Mr. Leonard Glascock
Prolerized Steel Corporation
Kansas City, Kansas
G. Wayne Sutterfield
Commissioner of Refuse
St. Louis, Missouri
H. J. Shelton and John Carnall
Gruendler Crusher and Pulverizer
St. Louis, Missouri
John Law and Don Johnson
Williams Patent Crusher and
Pulverizer
St. Louis, Missouri
John Dillon
French Oil Mill Company
Piqua, Ohio
Joe Baxter
Bill Eerbert
Black-Clawson
Franklin, Ohio
Calvin Hempling
Stedman Foundry
Aurora, Indiana
Kenneth Lee
American Pulverizer and Crustier
St. Louis, Missouri
Ralph Zawacky
General Metals
Denver, Colorado
Henry Munde
E1DAL, Inc.
Albuquerque, New Mexico
John Schreck
Hammermilis, Inc.
Cedar Rapids, Iowa
Ray Wender
Logemann Brothers Company
Milwaukee, Wisconsin
John Reinhardt and Gary Boley
Madison Landfill Product
Madison, Wisconsin
Terry Jones
Newell Manufacturing Company
San Antonio, Texas
Jim Barrett
San Diego Refuse Plant
San Diego, California
Dr. George Trezek, Consultant
University of California, Berkeley
Berkeley, California
Lorrle Leichner
Vancouver Sanitary Service
Vancouver, Washington
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Albert Gould
Enterprise Company
Santa Ana, California
Arthur Sternoff
Sternoff Metals
Seattle, Washington
Paul Chenard
Commissioner of Refuse
Milford, Connecticut
Dr. Stephen Varro
Ecology, Inc.
Brooklyn, New York
D.A. Savage and F. Stelwagon
Pennsylvania Crusher Company
Broomall, Pennsylvania
Paul Dion
State of Connecticut
EPA
Hartford, Connecticut
Uldis Kairins
County Engineer
Wilmington, Delaware
John Burkert
Delaware Design & Engineering
Dover, Delaware
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APPENDIX II
NUMERICAL RATING PROCEDURE FOR THE COMPARATIVE
EVALUATION OF SOLID WASTE SIZE REDUCTION EQUIPMENT
The following pages contain the text for the numerical
rating procedure discussed in Chapter IV. The procedure consists of
18 individual ratings grouped into three indexes-Manufacturer's
Index, Technical Index and Economic Index.
I. Manufacturer's Index
This index of the numerical rating procedure is designed to
provide a relative rating of the capability of the manufacturer to
build and service a reliable piece of equipment. The index is composed
of six individual ratings: Financial Strength, Shredder Experience,
Existing Installations, Equipment Endorsements, Service Endorsements,
and Industry Reputation.
Rating No. 1 — Financial Strength
The purchase cost of a size reduction machine of sufficient
capacity for processing municipal solid waste is in the range of
$50,000-$100,000. This figure is for the machine and motor only,
and does not include the other capital equipment needed to develop a
size reduction facility. For investments of this magnitude, it is
essential that the equipment manufacturer have sufficient financial
strength to promptly fill orders, meet delivery schedules, maintain a
spare parts inventory, and provide adequate field service. In addition,
most municipal waste processing machinery will be installed in large
plants that involve considerable capital investment and long
amortization periods. Thus, it is also essential that the manufacturer
have a foreseeable future equal in length to the projected life of
the machine. For these reasons, it is Important to consider the
financial strength and the credit position of a prospective source for
a machine.
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Rating scale: What is the Dun and Bradstreet capitalization
and credit rating of the manufacturer?
Rating Criteria
0 DD-1 ($35-50K cap., high credit)
1 DC"1 ($50-75K cap., high credit)
2 CC-1 ($75-125K cap., high credit)
3 CB-2 ($125-200K cap., good credit)
4 BB-2 ($200-300K cap., good credit)
5 BA-2 ($300-500K cap., good credit)
6 1A-3 ($500-750K cap., fair credit)
7 2A-3 ($750-1 mil. cap., fair credit)
8 3A-3 ($1-10 mil. cap., fair credit)
9 4A-3 ($10-50 mil. cap., fair credit)
10 5A-3 (Over $50 mil. cap., fair credit)
Rating No.2 - Shredder Experience
This section of the Manufacturer's Index is designed to
determine the manufacturer's past and present manufacturing experience
relevant to size reduction equipment and especially to size reduction
equipment for shredding municipal solid waste. This rating is one of two
related ratings-this rating for experience in manufacturing and selling
size reduction equipment and Rating No. 3 for the number of installations
actually shredding municipal solid waste with the manufacturer's equipment.
Both of these ratings have a direct bearing on the capability of the
company to select, recommend, design and fabricate a reliable piece of
equipment.
Advances in the state of the art of size reduction technology
have not been historically a scientific effort. Most of the extension
of the technology into new areas has been based on accumulated practical
experience. Even though the sales of size reduction equipment are
expected to increase due to the newly developed market in size
reduction of solid waste, the increase will not be sufficient to
support a comprehensive R&D program to develop a specific shredder
design for solid waste. For this reason, it is anticipated that
future advances in size reduction technology will continue to be of an
experimental nature. Therefore, the years of relative experience of the
manufacturer in the design, fabrication and sales of size reduction
machinery and the number of equipment installations completed was
considered an important factor in rating the machine.
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Rating scale: How many years has the manufacturer been
manufacturing and selling size reduction machinery?
Rating
Criteria
0
5 years or less
1
6 years
2
7 years
3
8 years
4
9 years
5
10 years
6
11 years
7
12 years
B
13 years
9
14 years
10
15 years or longer
Rating No. 3 - Existing Solid Waste Size Reduction Installations
As:discussed in Rating No. 2 above, size reduction of solid
waste is an emerging technology and experience is a major strength of
a manufacturer. The more direct to the subject the manufacturer's
experience is, the more advanced and reliable the equipment is apt to
be. The most accurate measure of the manufacturer's direct experience
in size reduction of solid waste is the number of existing installations
using his size reduction equipment.
Rating scale: How many Installations now In operation
processing municipal solid waste are using the manufacturer's size
reduction equipment?
Rating Criteria
0
1
3
5
7
9
10
0
1
2
3
4
5
6 or more
Rating No. 4 - Equipment Endorsements
Rating No. 5 - Service Endorsements
Rating No. 6 - Industry Reputation
These ratings are designed to develop a relative measure of
customer satisfaction with the manufacturer's products and service. It
is not sufficient that the manufacturers have adequate experience if
his customers are unhappy with his product.
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Customer satisfaction has been divided Into product endorsements
and service endorsements because of the generally Inadequate service
organizations of many manufacturers. In many cases, operators have
Indicated that they cannot get parts, those that they do receive do not
fit, and that technical assistance is often incompetent. This situation
is not unusual for an emerging technology, but should improve rapidly
as.sales increase.
Industry reputation is designed to measure nontechnical
aspects of customer satisfaction. Typical questions that this rating
tries to measure are: "Is the company reliable?" "Are they easy to
deal with?'' "Do they fulfill all contractual obligations?" "Even
if their machine is only adequate would you recommend them for other
reasons?", etc.
Ratine scales (Ratings Nos. 4 and 5): Are you satisfied
with the manufacturer's machine (service)? Would you recommend It
to others?
Rating Criteria
0 Recent customers are generally uuLiuppy
5 Normal mix of complaints and compliments
10 Customers enthusiastically endorse.the product
Rating scale (Rating No. 6): How would you describe the
business and technical reputation of the manufacturer?
Rating Criteria
0 Poor - Worse in the business
5 Adequate
10 Best - Generally acknowledged as Industry leader
II. Technical Index
This index of the numerical rating procedure is designed
to provide a relative rating of the engineering expertise demonstrated In
the design and fabrication of a size reduction machine. The rating
will provide a measure of the capability of the machine to meet the
required performance specifications of the customer. The index is
composed of nine individual ratings.
Rating No. 7 - Power Requirements
This rating is designed to measure the capacity of the
machine to meet required performance specifications of the customer.
The base line for evaluation is the guideline data presented in
Chapter III, Paragraph D. For example, If the customer's performance
specifications call for 40 tons/hr of combined waste with an output
particle size of 6 in., the guidelines indicate that 17.5 hp-hr/ton
are required and thus a 700-hp motor. If the.manufacturer recommends a
motor from 550 to 850 hp (plus or minus 25% of 700) then the
rating is 5.
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The rating criterion have been established on both the plus
or minus sides of recommended values because both too small a motor
and too large a motor are undesirable. Too small a motor means the
machine is undersized and will not give adequate performance at or
near design operating conditions. This factor is critical and should
be carefully evaluated. Too large a motor does provide excess capacity
for surge operation, but represents unused capital investment.
Individual users of this rating procedure, who are not strictly
limited on capital, may wish to modify the criteria to prevent
derating a machine that has excess power. This is accomplished by
ommitting the + in each of the rating criteria below.
Rating scale; How does the manufacturer's recommended
power requirements, in horsepower-hours per ton and total horsepower,
compare with the guideline data for the same performance requirements
(tons per hour of a given category of waste reduced to a given
particle size)?
Rating Criteria
0 Greater than plus or minus 50% of guidelines
1 Within plus or minus 45% of guidelines
2 Within plus or minus 40% of guidelines
3 Within plus or minus 35% of guidelines
4 Within plus or minus 30% of guidelines
5 Within plus or minus 25% of guidelines
6 Within plus or minus 20% of guidelines
7 Within plus or minus 15% of guidelines
8 Within plus or minus 10% of guidelines
9 Within plus or minus 5% of guidelines
10 Equal to guidelines recommendations
Rating No. 8 - Input Restrictions
Any given category of waste will occasionally contain an
item that is not a normal component of that category (for example,
a hardened transmission gear in medium solid waste) or an item that
cannot be efficiently processed in a hammermill (for example, fabrics).
The criteria for this rating are based on the potential damage that
these items can do to a machine and, consequently, the special
handling or presorting of the waste the manufacturer requires. If
the machine can be easily and severely damaged, then all input waste
must be thoroughly inspected and sorted. If the machine will reject
or pass through the occasional item with no damage, then no presorting
or special handling will be required. In most instances, the true
capabilities of the machine will be somewhere between the two
extremes.
Rating scale: What are the machine manufacturer's recommended
procedures for handling the occasional difficult item that can be
expected to be present in any specified class of input material?
6^
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Rating Criteria
0 continuous special handling or extensive presorting
required for difficult items
5 Can process almost all normal, items without special
handling
10 Can process all items without special handling
Rating No. 9 - Maintenance Intervals
The size reduction surfaces in any machine are subject to
severe impact, abrasion, and wear. Maintenance of these items, either
by resurfacing or by replacement, is a major factor in the operation of
the machine. All manufacturers have developed what they believe to be
the optimum combinations of hammer number, location, shape, weight, and
material and have optimized other items, such as cutter bars, breaker
bars, grates, housings, liners, etc. Some machines wear faster than
others and some machines are more sensitive to wear than others.
Each manufacturer will have a recommended procedure for replacement or
repair of major wear items on a normal maintenance interval. This
recommended interval will have an effect 6ft the use and avallablliLy
of the machines, and when converted to units of tons of waste per
repair, will provide a measure of machine efficiency.
Rating scale: What is the manufacturer's recommended interval,
in tons of waste, that his machine can process and still meet
specified performance, before repair of major wear items is required?
Rating Criteria
0 Less than 50% of average Interval from bids submitted
5 Average interval
10 Greater than 150% of average interval
Rating No. 10 - Machine Weight
Height Is a common yardstick that is used to evaluate many
machine tools. The total weight of a size reduction machine,
excluding motor and transmission, Is in general, a direct measure of
the durability of the machine-the heavier the machine, the more
durable it will be. Weight is especially important in large size
reduction machines. These machines are essentially very simple machines
that rely primarily on brute force to do their jobs. They need to be
heavy, sturdy, and possess sufficient mass to withstand the abuse they
must take.
Rating scalet How does the weight of the machine compare with
the average weight of all machines being considered?
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Rating
Criteria
0 Less than 75% of average
5 Average
10 More than 125% of average
Rating No. 11 - Rotor Inertia
Rotor inertia is a measure of the capability of a size
reduction machine to do its job effectively. These machines rely
primarily on the application of brute force, and it is the rotor that
applies the force. The higher the rotor inertia, the less susceptible
the machine is to jams, and the more effective it is in processing
large bulky items, resulting in less potential damage to the motor.
Rating scale: How does the rotor Inertia, in pounds-feet
squared of the machine compare with the average rotor inertia of all
machines being considered?
Rating Criteria
0 Less than 75% of average
5 Average
10 More than 125% of average
Rating No. 12 - Design Simplicity
Almost all size reduction machines are very simple devices.
They consist mainly of a rotor in a housing. This factor is designed
to est£felish a relative rating of the simplicity of design for the
machines being considered. No simple hard and fast rules are available.
The user must rely on his own analysis. However, he should at least
consider the following factors:
1. Access to major wear items for repair-access doors or
partial disassembly.
2. Hammer attachment to rotor and ease of replacement or
repair-individual hammer pins vs. common shaft.
3. Bearings and lubrication system-special design of
off-the-shelf components, access for repair or replacement.
4. Motor coupling-direct drive, belt drive, or transmission.
5. Special features, such as power assist devices.
Rating scale: How does the simplicity of design of the
machine compare to that of other machines being considered?
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Rating Criteria
0 Poor, complicated, many moving parts, poor access, etc.
5 Average
10 Exceptionally simple, best of the group
Rating No. 13 - Wear Adjustment
All size reduction machines are subject to severe wear during
operation. As the size reduction surfaces wear away, internal clearances
change and the output particle size may be affected. Most users of
size reduction equipment consider devices for adjustment for wear
as a desirable feature. Most of these devices currently available are
external, i.e., adjustment can be made without opening the machine
This rating is designed to measure the capabilities of the machine
for adjustment for wear.
Rating scale; Does the machine design provide for adjustment
of major wear surfaces to compensate for machine wear?
Rating Criteria
0 No wear take-up adjustment
5 Average
10 Fully adjustable up to sacrificial limits
Rating No. 14 - Power Assist Devices
Power assist devices constitute another special feature
that is considered desirable by most users of size reduction equipment.
Power assist devices include such items as hydraulic door openers,
hammer pin extractors, and hydraulic power units for wear adjustment
devices. This rating is designed to determine whether the basic
machine design can include these devices.
Rating scale? How well does the machine design provide for
the inclusion or addition of power assist devices without special
modification or alterations to the machine?
Rating Criteria
0 Such devices cannot be Included or added
5 Such devices can be included or added, but are optional
equipment
10 Such devices are included as standard equipment
Rating No. 15 - Rejection of Unprocessables
Any size reduction machine will eventually receive an item
that it cannot reduce or process in a normal manner. This rating is
designed to determine what will the machine do with this unprocessable
item. To prevent damage to the machine, it is essential that the item
be rejected in a safe manner or passed on through the machine. If
the item remains in the machine, then either the machine will jam or
will be damaged. Machines currently available on the market have a
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variety of systems including metal traps, ballistic rejection devices,
and discharge chutes. All of these devices have, in general, been
inadequate to guarantee machine safety.
Rating scale: What provisions or devices to prevent damage
does the machine have for handling unprocessable items that are
introduced into the machine?
Rating Criteria
0 None-machine must be stopped
5. Average-machine has a device that has potential of
preventing damage
10 Rejects or passes all items with no machine damage
Rating No. 16 - Installed Cost
This rating is designed to establish a relative rating of
the total costs for installation of the machine at the customer's
facility. Installed cost is the sum of FOB price, shipping charges,
delivery and setup charges, and any special installation charges.
The rating is intended to measure the net cost for the machine, in
dollars, that actually change hands; therefore, any special financing
or other agreements should also be included in determining installed
cost. The evaluator is cautioned to include like items in computing
the cost of each machine.
Rating scale: What is the net cost for the machine installed
at the customer's facility compared to the net cost of all machines
submitted?
Rating Criteria
0 Greater than 150% of average of all bids
5 Average costs
10 Less than 50% of average of all bids
Rating No. 17 - Operating Costs
This rating is designed to establish a relative measure of
the net cost, in dollars per ton, of operating the machine. Net cost
should include only power costs, costs for maintenance labor and
materials, and repair parts cost. The user should assume that the
operating labor and overhead costs will be equal for all machines,
unless the manufacturer specifically recommends personnel other than
those the customer' plans to use. Further, if amortization costs are
to be included, all machines should be depreciated on an equal basis.
Rating scale: What is the net cost, in dollars per ton,
for operating the machine compared to the average of all bids
submitted?
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Bating
Criteria
0 Greater than 150% of average
5 Average
10 Less than 50% of average
Rating No. 18 - Service Expectation
This rating is intended to measure the effects of the
manufacturer's service policies on the operation of the machine.
These machines are subject to severe abuse and require constant
service and maintenance. Many will be installed in facilities that
cannot tolerate long downtime duei to parts unavailability or poor
service' from the manufacturer, i;e., the solid waste input to the
facility must be disposed of.
Rating scale: What is the local service expectation from
the manufacturer?
Rating
0
5
10
Criteria
Poor, no local representative or parts
Average, no discernible difference among the bidders
Excellent, local service and parts, home office
within 100 miles
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APPENDIX III
TEST PROCEDURE NO. 1
TECHNICAL PERFORMANCE TEST
A. General
This test is designed to determine the unit power required
for the size reduction of solid waste. The test consists of processing
a measured sample of solid waste under controlled conditions and
measuring the processing time and total power used. The data are
then reduced to horsepower-hours per ton of waste.
The waste sample is selected and sorted to form a uniform
sample of one category of waste. Moisture content and output particle
size of the waste is determined from samples taken after size
reduction.
The test procedure requires a total of 30 tests with one
machine. Three tests per day shall be conducted for 2 weeks (five working
days per week). The test procedure is scheduled for 2 weeks to provide
two replications of the normal weekly variations in waste content.
The daily tests shall be made at designed processing rate (in tons
per hour), at 75% of design rate, and at 125% of design rate. The
different processing rates are to determine if there is any effect on
unit energy and output particle size. The content of all test waste
samples shall be adjusted to be the same category of waste.
B. Test Facilities
t. Test site;
a. Receiving area, approximately 50 ft by 50 ft for
collecting the test sample of solid waste. The area should be located
close to the shredder.
b. Bucket-equipped hi-loader or other suitable equipment
for placing the waste sample into the size reduction facility input
device.
2. Instruments and tools;
a. Suitable shredder drive motor power measuring
device. The device can be an amp-meter, a watt-meter, a watt-hour
meter, or other comparable instruments. It is recommended that the
instrument be equipped with an automatic recording paper graph or
chart.
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b. One stopwatch.
c. Handtools, such as rakes, hoes, yardsticks, etc.
d. Three each, 1 cu ft capacity plastic sample bags.
3. Personnel;
a. Test engineer; The test engineer shall plan the
test, determine the material processing rate, select the waste sample,
supervise the test, and record all test data.
b. Test technician; The test technician shall feed the
waste into the facility input device and maintain a continuous and
uniform flow rate of waste into the shredder. The test technicians
shall also collect the samples of shredded waste for subsequent
analysis.
c. Test operators: The operators shall work at the
direction of the test technician to operate the size reduction
facility during the test. The operators should be regular employees
of the size reduction facility.
C. Test Procedure
1. Preparation;
a. Collect a sample of solid waste sufficient to
supply the shredder for 1 hr at the test processing rate.
b. Sort the sample to remove any items not considered
normal for the category of waste being processed.
c. Thoroughly mix the waste with the hi-loader.
Bulky items or segregated items should be uniformly distributed in
the sample.
d. Inspect the shredder and major wear surfaces.
Replace or repair any missing, broken, or worn elements.
e. Verify proper operation of the drive motor power
measuring device.
f. All conveying equipment and the shredder shall be
operating properly.
g. All safety devices, including conveyor and shredder
motor Interlock shall be inspected for proper operation.
2. Test operation;
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a. Start all conveyors and feeders and the shredder,
and allow all units to come to normal operating conditions.
b. Begin placing the waste into the shredder Input
device with the hi-loader.
c. Verify that the depth of waste on the Input conveyor
is the proper depth to obtain the desired feed rate.
d. Distribute the waste evenly over the input
conveyor to assure uniform and continuous operation of the shredder.
Manual distribution using handtools may be required.
e. Start the stopwatch and the drive motor power
measuring device when the first waste from the sample enters the
shredder.
f. Continue to operate the shredder and waste,
feeding at a uniform rate, until all of the test sample has been
processed. Record the time and the power readings.
g. If any delays occur during the test, note the
time and power reading at shutdown and restart.
h. Obtain three 1 cu ft samples from the shredded
test waste. One sample should be taken from waste processed early in
the test, the second near the middle of the test, and the third
late in the test.
i. Have a commerical testing laboratory test the
samples for average particle size (by use of a sieve) and moisture
content (weight before and after heating). Measurements of the sample
should be made within 24 hr after test completion.
j. Record the following data on the test record
sheet:
t. Category of waste
2. Sample weight in tons
3. Processing time in hours
4. Total power in amps* watts, of watt-hours
E. Data Reductions
1. Convert the power data from amps, watts, or watt-hours
to horsepower.
2. Determine the processing rate in tons per hour by
dividing weight in tons by time in hours.
3. Determine the unit power in horsepower-hours per ton
by dividing the power in horsepower by the tons per hour.
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4. The test particle size Is determined as the numerical
average of the particle size of the three samples. The test moisture
content is determined as the numerical average of the moisture content
of the three samples.
5. Enter the following data for each Individual test on
the test summary sheet:
a. Waste category
b. Processing rate
c. Horsepower-hours per ton
d. Particle size
e. Moisture content
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TEST PROCEDURE NO. 2
ECONOMIC PERFORMANCE TEST
A. General
This test is designed to determine the net cost, in dollars
per ton, of power and machine wear for size reduction of municipal
solid waste. The test consists of monitoring the amount of waste
material processed through three normal repair intervals and accurately
determining the cost of labor and materials for each repair. A
normal repair is defined as a repair or replacement of a major
wear item in the shredder that has been worn beyond normal operating
limits. The data are then reduced to determine the tons per repair
interval, the cost per repair, and the dollars per ton of repair.
The test procedure requires no special samples of waste,
but is based on the usual waste processed at the site. If a private
test facility is used, then packer truck materials from the local
area shall be used. The waste shall be sorted and separated to conform
to one of the five basic categories. Test conditions and facility
operation shall, as closely as possible, duplicate the daily operations
of a solid waste size reduction facility.
This test procedure is not economically feasible for
application at facilities that have shredders with unusually long
repair intervals (i.e., longer than 8-10 days). In such instances,
the test procedure must be monitored by the facility operator with
a minimum supervision. Because of the operator's concern with day-to-day
problems, the accuracy and completeness of such data are questionable.
B. Test Procedure
This test procedure does not require any special facilities,
instruments, or tools. Also, no special test methods or procedures
are necessary. The test is performed by the test technician.
1. The test shall begin after the shredder has been
repaired or rebuilt to an as-new condition. All broken, missing
or worn major wear items-breaker bars, cutter bars, liners, etc.-shall
be replaced or repaired.
2. The test technician shall observe the incoming waste
and record the weight and type of all material processed by the shredder.
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3. When the machine Is shut down for maintenance, the
technician shall Inspect the machine and record the condition of
all major repair Items.
4. The test technician shall observe the maintenance
procedure and record the following data:
a. Number of personnel and their labor category-i.e.,
foreman, welder, laborer, etc.
b. The number of hours each member of the maintenance
crew actually participates in the maintenance work.
c. The type, and amount of materials used in the
maintenance work.
5. The above procedure (steps 1-4) shall be repeated
three times.
C, Data Reduction
1. The ton per repair shall be the arithmetic average
of the amount of material processed through the machine during each
of the three intervals.
2. The cost of the labor shall be computed by using
standard salary figures for the local geographic area.
3. The cost of materials shall be computed by using the
manufacturer's advertised retail price.
4. The cost of a repair is the sum of the labor and
materials cost.
5. The cost of maintenance in dollars per ton is
determined from the average tons per repair and the cost per repair.
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VOLUME II
INVENTORY OF SIZE-REDUCTION EQUIPMENT
CHAPTER I
INTRODUCTION
The purpose of this equipment Inventory is to assemble the avail-
able technical and cost data on size, reduction equipment in the processing of
municipal solid wastes. (Size reduction is defined as operations which reduce
the size of influent materials, through division into two or more sub-units.)
The data and narrative material included in this inventory are intended to be
used as an aid in the selection of size reduction equipment. Use of the cata-
log represents the first step in the selection process--screening of avail-
able sources of size reduction equipment to determine those sources that can
provide equipment of the proper type, capacity, and size for the intended
application. The second step for a prospective purchaser is to contact the
manufacturers and suppliers of size reduction equipment that are screened in
the first step to solicit specific technical data and cost estimates.
The information contained in this inventory presents the state
of the art in size reduction of municipal solid wastes. In many Instances
the technical data are very limited. This is an indication of the "newness"
of the application of size reduction to solid wastes. There are only a
few municipal solid waste processing installations in the United States that
include size reduction of the waste. Many of these are now, or have been,
partially funded by the EPA as demonstration projects. Almost all are pilot
operations, handling small volumes and small percentages of the total solid
wastes of the surrounding area.
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The following sections of this inventory present a general back-
ground of size reduction equipment, a discussion of the sources of informa-
tion for the inventory, selection guidelines based on the experience of
operators of municipal solid waste size reduction equipment, and data sheets
from each of the manufacturers and suppliers of size reduction equipment. A
list of existing municipal solid'waste size reduction installations is pre-
sented in Appendix I.
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CHAPTER II
SIZE-REDUCTION EQUIPMENT*:
Size reduction is the mechanical separation of bodies into smaller
pieces. Size reduction of municipal solid waste is becoming of more interest
because it facilitates handling, and permits more efficient separation and re-
covery processes. There are ten basic types of size reduction equipment gen-
erally available—crushers, cage disintegrators, shears, shredders, cutters and
chippers, rasp mills, drum pulverizers, disk mills, wet pulpers, and hammer-
mills. All except cage disintegrators, cutters, and disk mills have potential
application in either primary or secondary municipal waste size reduction.
However, only hammermills and wet pulpers are currently being used for muni-
cipal solid waste size reduction in the United States. The following para-
graphs present brief descriptions for each of the above types of machines.
Crushers; Crushers are normally relatively, slow-speed devices that
apply compression forces to reduce the size of friable materials such as
coal and rock. They are generally used in mines and quarries and their potential
application in municipal solid waste is limited to size reduction of bulky
items and construction rubble.
Four types of crushers are generally available: jaw, roll, gyrating,
and impact (see Figure 1, p. 5). Only the impact type seems to have application for
solid waste size reduction. Machine sizes range from 25 hp to over 2,000 hp
in mining installations.
* Condensed from Recovery and Utilization of Municipal Solid Waste, U.S.
Environmental Protection Agency, Solid Waste Office, SW-lOc.
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Cage disintegrators: Cage disintegrators (see Figure 2) use
single or multiple high speed contra-rotating cages to fragment input ma-
terial. Input is to the center cage and size reduction occurs as the
material moves radially. The machine is usually only effective with brittle
materials such as glass, and is used primarily in the chemical process in-
dustries where close control of output particle size is required. Cage dis-
integration does not appear to have any application to primary processing
o£ municipal solid wastes. However, they could be used for secondary size
reduction of separated friable materials in a resource recovery system.
Shears: Single-blade shears (see Figure 3) are a size reduction
device whose application is limited to bulky items such as automobile bodies,
lumber, and demolition wastes. They are most often found in scrap yards and
similar operations. For processing of municipal wastes, they would be used
for presizing of items too bulky to fit into the size reduction machine.
Cutters and chippers: Cutters and chippers are available in many
configurations. Two basic types—the pierce and tear type and the cutting
type (see Figure 4)--are of interest. The cutting type is the more widely
used of the two, although both types are generally only used for size reduction
of paper and cardboard. Both types are subject to excessive damage from un-
sorted refuse and do not appear suitable for municipal solid waste processing.
Larger chippers, such as those used for reduction of brush and yard waste,
would appear to have some application in solid waste, but they are generally
of small capacity.
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•I
Jaw
~
Roll
Figure 1 - Crushers
Input
Single or
multiple
controrotating
cages
Figure 2 - Cage Disintegrators
77
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0
Single alligator-type
Figure 3 - Shears
Cutting type
Figure 4 - Shredders, Cutters, and Chippers
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Rasp mills: Rasp mills are large, slow-speed cylindrical machines,
about 20 ft in diameter, used primarily in composting plants. The machine
has a bottom grate with holes and rasping pins (see Figure 5). A large heavy
rotor passes the waste over the pins and down through the holes. Bulky, non-
reducible solid waste is rejected. Rasp mills appear to be suitable for size
reduction of municipal solid waste and some are being used in Europe.
Drum pulverizers: A drum pulverizer is essentially a rasp mill with
a rotating grate and a stationary arm (see Figure 6). The drum, or perforated
grate, may be circular, octagonal, or hexagonal in shape. Some types of drum
pulverizers may have moving arms or baffels. These machines are slow SDeed
(up to 10 rpm) and may be a batch process operation and they can accept a wide
range of input materials.
Disk mills: Disk mills operate by tearing material placed between
two flat surfaces, one or both of which are rotating at high speed (see
Figure 7). They are precise-machines that .are normally suited for pulpable
materials and they are usually found in paper mills. Their major disadvantage
is that input particle size must be small—less than 2 in.--and therefore would
be suitable only for secondary reduction of municipal solid wastes.
Wet pulpers: A wet pulper is a type of vertical single disk mill
that operates under water (see Figure 8). It reduces the size of input material
by forming a water slurry (90% water, 10% solids), and forming a high-speed
water vortex. The input material is suspended in the vortex and subject to
repeated impact with stationary hardened impact bars of the pulper. Wet
pulpers are best suited for pulpable and fibrous material; however, they can
79
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Figure 5 - Rasp Mills
\o. Rejects
Perforated inner drum:
circular,octagon or hexagon
II rpm
Figure 6 - Drum Pulverizers
80
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Single or controrototing
Figure 7 - Disk Mills
Hard member
Rejects
Product
Figure 8 - Wet Pulper
81
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accept a wide range of materials, including metals. Application to municipal
solid waste processing is primarily in composting or fiber recovery operations.
Hammermills; Hammermills represent the largest percentage of muni-
cipal solid waste size reduction equipment. There are hammermills for all
types of input materials, and machine sizes range from small laboratory
models to huge machines capable of accepting entire automobile bodies. A
hammermill consists of a center rotor with radius arms (hammers) protruding
from the rotor circumference.. The. rotor is enclosed in a heavy duty housing.
Some hammermills have stationary breaker plates or cutter bars mounted inside
the housing. Input material is literally beat and torn to shreds by the
hammers.
There are three basic variations of the hammermills--the swing-
hammer type, the rigid-hammer type, and the grinder type. In the swing-hammer
type, the hammers are pivoted on the rotor. Hammer designs vary from sharp
choppers to rectangular blunt beaters'. The latter is most often used for
refuse size reduction. Ih grinder type hammermills, the hammers are replaced
by rotating elements, usually star wheels, which grind up the input refuse by
rolling it between the star wheels and the housing side walls.
tost hammermills have horizontal rotors with top feed and bottom
discharge. Output particle size is controlled by the size of openings in
a grate placed across the bottom. Material remains in the hammermill until
it is reduced sufficiently to fall through the grate. A unique variation
of the hammermill is the vertical rotor type. These machines may have a
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decreasing cross-sectional area between the rotor and stationary housing so
that progressive size reduction occurs as the material falls through the
machine.
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CHAPTER'III
SOURCES OF INFORMATION
The names and addresses of manufacturers, users, and consultants
for size reduction equipment were obtained from the following sources:
Thomas Register of American Manufacturers;
Environmental Protection Agency and Office of Solid Waste
Management Publications;
Advertisements in technical and trade publications;
In-house knowledge and experience; and
Trade shows.
Information obtained from the above sources was used to compile
the list of manufacturers of size reduction equipment presented in Appendix
II. This list was screened to eliminate companies producing only machines with
a capacity less than 4.tons/hr and the manufacturers of special purpose ma-
chines not intended for use with municipal solid waste. Requests for catalog
data, technical data, and advertising literature were made to the remaining
companies. Many of these companies were reluctant to submit any information
other than that contained in their advertising (some companies do only custom
design and have no specific catalog data; others were secretive about their
product). Those that did supply data are listed in Table I.
The original list contained the names of 76 sources of equipment.
Many of these companies were eliminated because their machines were too small,
were not suited for processing of solid waste, were designed to process only
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TABLE I
COMPANIES FURNISHING DATA FOR THE INVENTORY
American Pulverizer
Black-Clawson
Buffalo Hammer Mill
Denver Equipment
Eidal International
Enterprise
French Oil Mill
Gruendler Crusher
Hantmermills, Inc.
Hazemag
Hell
Jeffrey Manufacturing
Logemann Brothers
Newell
Pennsylvania Crusher
Proler Steel
Richards Shear
Stedman Foundry
Williams
Type of
Contact
P.V.
P.V.
P.L.
P.V.
P.V.
P.V.
P.V.
P.V.
P.V.
P.L.
P.V.
P.L.
P.V.
P.V.
P.L.
P.V.
P.V.
P.V.
P.V.
Included
in Catalog
Yes
Yes
Yes
No
Yes
Yes
No
Yes
Yes
No
Yes
Yes
No
No
Yes
No
No
Yes
Yes
Comments
Not for refuse
No future sales for refuse
Custom design only
Not for refuse
Custom design only
Custom design only
Custom design only
Notes: P.V. - Personal Visit.
P.L. - Phone and Letter.
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specific types of solid wastes (i.e., commercial scrap, building rubble,
etc.), or they did not intend to distribute their machines in the U.S. Of
the remaining companies, only about a dozen have machines in operation pro-
cessing municipal solid wastes; Because of this, very little technical data
supported by operational experience are available on size reduction equipment.
Manufacturers ratings are often established by intuition, by extrapolation of
limited test data, or from data for other materials. Capital cost and operat-
ing expense data are often unreliable because many of the size reduction ma-
chines processing municipal solid wastes are part of a project that is receiving
government funds or is operated by a government body which has captive main-
tenance and operating personnel. Funds for these personnel may not appear
in the net cost figures for the project. Thus, the potential user should be
aware that the. cost data available, in general, are subject to question.
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CHAPTER IV
SELECTION GUIDES
Development of size reduction technology to process solid waste has
been partially supported by the Office of Solid Waste Management of the Environ-
mental Protection Agency. In the past 10 years, this office has partially or
wholly supported many demonstration grants or pilot projects. These installa-
tions represent the principal source of practical experience in the operation
of size reduction equipment for the processing of municipal waste. Discussions
with personnel at these installations and review of government reports indi-
cate that there are, certain facets in the process of size reduction that are
common to all installations. Some of these are discussed in the following
paragraphs.
Materials handling: Size reduction of solid waste is apparently
within the capability of current state of the art of machines. Most experi-
enced personnel agree that the major system problem is refuse handling equip-
ment, not the size reduction machinery. Because of the size, weight, and
power requirements of size reduction equipment, it is usually necessary that
the machine be stationary and bring the solid waste material to the machine.
Municipal solid waste is not an easy material to handle. Some of the character-
istics that make it difficult to handle are:
Density: Prior to size reduction, municipal refuse has a low
density, and large process areas are required for large tonnage inputs. After
size reduction, the density may be increased and the shredded waste will com-
pact easier than unshredded waste. Because refuse is subject to compaction
-------
both before and after size reduction, it must be handled in special ways.
It cannot be "pushed" down a chute or tube or it will compact, bridge, and
jam the apparatus. Auger feeding is especially unsuitable.
Mixture: The waste material is a heterogeneous mixture of
particles of variable size, weight, and physical properties. There are no
distinct physical or mechanical properties that can be utilized to facili-
tate easy handling.
Abrasiveness; Municipal solid waste is a vesry abrasive ma-
terial and machine wear is a major problem. The abrasiveness is due to
many factors, including: (1) the waste contains large amounts of paper and
paper products that are abrasive in themselves; and (2) the waste is a mix-
ture of materials with widely different physical properties.
Flammability: The majority of municipal solid waste is organic
and is easily ignited. Because of the large amounts of energy being expended
to shred the waste, high temperatures and sparks cause frequent fires. Fire
control systems are a necessary requirement in most installations.
Presorting: Some degree of presorting of the input prior to size
reduction is required for almost all installations. No size reduction
machinery (except the very large hammermills capable of processing entire
cars) can accept and process all of the waste normally delivered by packer
trucks. For the smaller machines, the bulky wastes and all heavy gage metal
must be removed. For the larger machines, large heavy metal pieces must be
removed and bulky items must be distributed. Presorting the input is a manual
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operation normally performed by the operator controlling the input to the
size reduction machine.
Feed control: Efficient operation of the size reduction facility
requires that the machine be fed uniformly. Intermittent or variable feeding
of the machine can produce severe motor overloads, machine jams, and even
damage to the machine. However, 'Uniform feed is the single most difficult
operational factor to maintain. Due to ease of compaction, refuse cannot be
fed by screws. Due to bridging and agglomeration, it will not feed from hop-
pers or chutes. Pneumatic feeds are only partially successful. In most in-
stances the waste must be physically picked up and placed on an input conveyor
or similar device at the desired rate. Several of the demonstration projects
have used a procedure in which an operator transfers the waste from a re-
ceiving area to the input conveyor with a high loader, bulldozer, crane, or
other types of earth moving equipment. The operator thus controls the input by
the amount and kind of material he places on the input conveyor.
Type of machine: The hammermill is the most widely used machine
for the size reduction of municipal solid waste. The hammermill has been in
use in other industries for over 50 years and there are several reputable
manufacturers. Thus, the hammermill is readily available in a wide range of
sizes, and has an extensive background of use. The hammermill has many
advantages, including:
1. Reasonable control over output particle size: Specification
of grate sizes and hammer clearances allows a wide range of effluent particle
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size from under 1 in. (with double pass through two machines) to over 10 in.
Particle size is reproducible within acceptable limits.
2. Limited presort required: The hammermill can process most
bulky items (such as lumber, rubber tires, and small appliances) that are in
normal packer truck waste. Some presorting is required to remove heavy metal
pieces, rugs, large appliances, etc., except for the very large machines.
3. Simple machine design: The hammermill is a very simple
machine. It has few moving parts and can be serviced by operating personnel.
Horsepower: Total horsepower of a size reduction machine is an
indicator of the tonnage throughput capacity of the machine. For example,
a minimum horsepower, depending on the type of wastes to be processed, is
required to obtain minimum levels of performance without frequent jams or
damage to the machine. The minimum horsepower requirement for a given type
of waste will vary with machine type, degree of size reduction and other
variables. However, the following values are commonly used in the industry
as general guidelines for selecting a machine for a given application.
1. 250 hp - Light wastes—paper, cardboard, bottles, cans,
garbage and lawn trimmings.
2. 600 hp - Normal packer truck wastes — including small
appliances, some pieces of furniture, lumber and small commercial scrap,
bicycles, auto tires, and tree trimmings.
3. 1,000 hp - Bulky wastes—large appliances, bed springs,
mattresses and rugs, larger tires, tree brush, larger pieces of lumber.
90
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4. 2,000 hp - Heavy wastes—automobiles (without engines),
demolition rubble, tree trunks.
5. 3,000 hp - Entire automobiles (with engines), scrap metal.
In addition to the total horsepower of a given machine, the horse-
power-hour per ton is another indicator of machine performance.
A horsepower-hour per ton rating is obtained by dividing the total
horsepower of the main driver by the machine throughput capacity in tons per
hour. For example, a machine with 1,000 hp motor and a rated capacity of
50 ton/hr of municipal refuse has a horsepower-hour per ton rating of 20.
Discussions with operators of municipal refuse plants, EPA demonstration
grants, and private refuse processors have indicated that the horsepower-
hour per ton required to process municipal solid waste may be independent of
machine type or manufacturer. Fifteen horsepower-hour per ton is generally
considered the minimum rating and requires presorting to remove bulky items
and close control of feed rates to prevent jamming, especially for small
machines, i.e., less than 1,000 hp. Twenty-five horsepower-hour per ton is
an average figure for general municipal refuse and provides the operator with
the ability to handle moderately variable feed rates and occasional bulky
items (such as tree limbs and large appliances) without stopping or jamming
the machine. Thirty horsepower-hour per ton is a minimum value for continuous
processing of heavy items such as automobiles, building rubble and heavy
metal items.
Machine tool wear: Due to the abrasive nature of municipal solid
waste, wear in a size reduction machine is a major operating expense. All
91
-------
types of size reduction machines are subject to this wear. The major areas
of wear are the cutting surfaces that actually perform the size reduction
(for example, the hammers in a hammermill). Repair of worn areas is done
by resurfacing or by replacement, with resurfacing as the more common method.
Repair intervals vary with individual machines and with types of machines.
However, preliminary analysis of-existing plant procedures indicates that
tool repair will be required after 1,000 to 2,500 tons of waste processed
for the smaller machines (i.e., 500 to 1,000 hp), and after 2,000 to 5,000
tons for the larger machines (i.e., 1,500 to 3,000 hp).
Machine specifications: The size reducliuti machine is only one
component of a municipal solid waste processing system. The system will
include in most instances, the following components:
1. Receiving and holding - An area or device for accepting
refuse from the primary collection or transfer system.
2. Refuse feed - A manual or mechanical method of placing
the refuse on the size reduction unit input conveyor at a controlled rate.
3. Shredder input - A conveyor device to transfer the refuse
into the shredder.
4. Size reduction.
5. Refuse output - A conveyor device to transfer the refuse
away from the size reduction machine.
6. Discharge - An area or device that accepts the shredded
refuse for subsequent processing or disposals
92
-------
Because of the large number of possible installations and the
variation in the composition of solid wastes, manufacturers do not. produce
a "line" of off-the-shelf size reduction machines. Instead, they have a
series of basic machine designs which can be "tailored" to fit a specific
job. For this reason equipment specifications must be well defined in order
to receive competitive bids. As a minimum, the specification should include
the following information:
1. A description of the material to be processed, including
maximum input particle size and any allowable presorting to prevent potentially
damaging material from entering the shredder.
2. The minimum throughput rate desired in tons per hour and
tons per day or shift.
3. The particle size of output required.
4. The main drive motor size and type (i.e., electrical,
diesel, etc.), and peak power available for the motor.
5. The motor controls, if desired, including automatic and
manual shut-offs, recording power meters, and overload protection.
6. A fire control system, if desired.
7. The type of input, including size and location—i.e., top
loading conveyor or side loading feed chute.
8. Type of output, including size and location.
9. Machine installation requirement--i.e., indoors or outdoors,
foundation size and type, and vibration limitations.
93
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CHAPTER V
MANUFACTURERS' DATA SHEETS
This section contains brief descriptions of size reduction equip-
ment manufacturing companies and catalog data on their equipment. Inclusion
or exclusion of any manufacturer does not indicate endorsement or lack of
endorsement by the EPA, but rather a willingness of the manufacturer to supply
information to the project. Wherever possible, capacity in tons per hour has
been included. These ratings have been supplied by the manufacturer.
94
-------
American Pulverizer Company
1249 Macklind Avenue
St. Louis, Missouri
Machine type: Hammermill
American Pulverizer Company has been in business for over 60 years.
Their principal products are size reduction machinery and related equipment
such as conveyors, blow pipe, and cyclone separators. Their size reduction
machines are the hammermill type and are generally special purpose machines--
i.e., automobile, aluminum can, tin can, paperboard and corrugated cardboard,
scrap wood and glass shredders, and metal trimming crushers. The company
advertising literature describes two types of hammermills designed for refuse
and garbage shredding, although no model numbers, dimensions, or technical
data are presented. They do not report any' existing installations with
their machines processing municipal solid wastes. However, they have numerous
installations with machines processing paper and corrugated refuse and scrap.
Their hammermills are of horizontal rotor design with top input
opening and bottom discharge. The company prefers to do a "turn-key" job
providing all necessary components including the hammermill, conveyors,
separators, and air pollution control equipment. The technical data shown
on the attached data sheet were obtained from company literature and discussion
with company personnel.
95
-------
AMERICAN PULVERIZER COMPANY, ST. LOUIS, MISSOURI
FEED
MODEL NO. CAPACITY* SPEED OPENING
OR SIZE HORSEPOWER* (TPH) (rpm) (in.)
WS-16 21 x 18
WS-22 21 x 23
WS-28 (Horsepower, capacity, and 21 x 29
WS-34 speed determined upon 21 x 34
WS-40 application.) 21 x 40
2400 31 x 37
3800 31x49
4200 31 x 55
4800 31 x 61
48-50 50 x 54
48-60 50 x 64
48-80 50 x 84
48-90 50 x 94
60-50 48 x 52
60-60 48 x 62
60-80 48 x 82
60-90 48 x 92
72-60 68 x 65
72-72 68 x 76
72-84 68 x 88
72-96 68 xlOO
96-80 84 x 82
96-90 84 x 92
96-120 84 xl22
* Throughput material for horsepower and capacity listed
Automobile and scrap shredders.
DIMENSIONS (in.)
LENGTH WIDTH HEIGHT
WEIGHT
(lb)
FEED CAPITAL
METHOD COST
59
60
59
66
59
72
59
77
59
82
72
76
72
88
72
94
72
100
102
117
102
127
102
147
102
157
103
120
103
130
103
150
103
160
135
170
135
182
135
194
135
206
172
188
172
198
172
228
7,200 Top
8,000
8,800
9,800
11,000
14,000
17,000
19,000
22,000
40,000
46,000
69,000
83,000
63,000
70,000
90,000
105,000
170,000
190,000
210,000
235,000
260,000
295,000
350,000
38
38
38
38
38
49
49
49
49
73
73
73
73
90
90
90
90
123
123
123
123
146
146
146
-------
AMERICAN PULVERIZER COMPANY, ST. LOUIS, MISSOURI
FEED
MODEL NO.
CAPACITY*
SPEED
OPENING
OR SIZE
HORSEPOWER*
(TPH)
(rpm)
(in.)
CS 330
75
3-4
600
45 x 30
CS 350
100
6-8
600
45 x 50
CS 361
125
8-10
600
45 x 62
CS 370
150
10-12
600
45 x 72
CS 380
200
12-14
600
45 x 82
CS 390
250
14-16
600
45 x 92
* Throughput material for horsepower and capacity listed
Paper and corrugated material.
DIMENSIONS (in.)
LENGTH WIDTH HEIGHT
WEIGHT
(lb)
FEED CAPITAL
METHOD COST
12,000
17,000
20,000
22,000
25,000
28,000
Top
-------
Black-Clawson Company
Shartle-Pandia Division
Middletown, Ohio 45042
Machine type: Wet pulper
The Black-Clawson Company is a worldwide organization supplying
mechanical equipment for the wood, pulp and paper, paperboard, chemicals,
metal products, rubber, and plastics segment of the chemical processing indus-
try. The company manufactures machinery and equipment systems and provides
research and development services and technical guidance. The principal
products of their Shartle-Pandia Division include digesters, reactors, feeders,
conveyors, filtration equipment, mixers and blenders.
The Black-Clawson Company does not have a line of size reduction
equipment, as such. They are manufacturers of pulping equipment and custom
design installations for processing solid waste. Black-Clawson has developed
a solid waste disposal system called Hydrosposal and Fiberclaim. They are
total systems designed to recover fibers, glass and metals, and produce an
inert, nonputrescible residue. The company has a pilot plant operation at
Franklin, Ohio. This plant is an EPA Demonstration Project for recovery of
fibers and ferrous materials. The plant also separates glass and nonferrous
metals. All recovered fibers are sold to a local paper company. Combustible
residues are burned in a fluid bed reactor. All normal packer truck material
(except auto tires) can be handled by the system. The pilot plant has a
capacity of 6 ton/hr.
98
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Buffalo Hammer Mill Corporation
1245 McKinley Parkway
Buffalo, New York 14218
Machine type: Hanunermill
Buffalo Hammer Mill Company makes a series of small hammermills
with their largest unit having a <300-hp drive motor. These mills are gene-
rally intended for use in commercial applications where they are processing
specific types of materials. The units are top-fed bottom-discharge and are
welded one-piece construction. They make special mills (i.e.^ stainless
steel) and can provide a wide range of materials. They do not have any
machines in operation processing municipal- solid waste. The tonnage through
put values shown on the;data sheets are not for municipal refuse but were
demonstrated for much denser materials such as rock, etc. They do not recom-
mend processing metals, rubber tires, or tough plastics with their machines.
99
-------
BUFFALO HAMMER MILL COMPANY, BUFFALO, NEW YORK
FEED
o
o
MODEL NO.
CAPACITY*
SPEED
OPENING
DIMENSIONS (
OR SIZE
HORSEPOWER*
(TPH)
(rpm)
(in.)
LENGTH
WIDTH
W-4-L
1/2 - 2
1/2 - 2
8,000
4
12
20
W-6-L
1/2 - 3
1/2
8,000
6
14
20
W-8-L
5 - 20
1
3,600
8
27
30
W-12-L
15 - 50
5
3,600
12
30
30
W-16-L
20 - 60
8
3,600
16
40
38
W-20-L
25 - 75
15
3,000
20
43
38
W-25-L
25 - 100
20
2,900
25
48
38
W-30-L
50 - 150
30
1,800
30
50
54
W-36-L
60 - 150
40
1,8.00
36
66
54
W-40-L
75 - 200
60
1,200
40
72
60
W-50-L
75 - 300
80
1,000
50
98
72
W-60-L
100 - 300
100
900
60
108
80
HEIGHT
WEIGHT FEED
(lb) METHOD
CAPITAL
COST .
Top
* Throughput material for horsepower and capacity listed.
Material not specified--however, capacities are not for solid waste, but. much
heavier materials.
-------
Gidal International Corporation
(A Subsidiary of Southwest Factories, Inc.)
245 Woodward Road, S.E.
Albuquerque, New Mexico 87103
Machine type: Vertical shaft grinder-type hammermill
The Eidal Corporation has been associated with heavy equipment
design and manufacturing for many years. They introduced their line of
vertical shaft shredders in 1965. The company manufactures four basic ma-
chines ranging from a 100-hp "Mini-Mill" to a 2,000-hp "Brute." As shown
on the data sheet, they have several installations where their machines are
processing municipal solid refuse. The machines are top-loading, vertical-
feed with bottom horizontal discharge. Material entering the machine flows
through it by gravity and is progressively reduced in size until it reaches
the output. Because the size reduction process is progressive, bulky items
can be fed into the machine without presorting. The model 1000 is the
Eidal unit recommended for general municipal.refuse. User experience indi-
cates that these machines may have a very low hammer or grinder wear cost per
ton of waste.
101
-------
EIDAL INTERNATIONAL CORPORATION, ALBUQUERQUE, NEW MEXICO
MODEL NO.
OR SIZE
100
400
1000
2000
HORSEPOWER*
100
400^
1,000®/
2,000k/
CAPACITY*
(TFK)
5
15
40
100
SPEED
(rpm)
FEED
OPENING
(in.)
52 x 30
60 x 60
60 x 88
60 x 98
DIMENSIONS (In.) WEIGHT
LENGTH WIDTH HEIGHT (lb)
FEED CAPITAL
METHOD COST
Top
$23,800
72,400
139,000
318,000
* Throughput material for horsepower and capacity listed.
a/ Dual motor applications, i.e., 400 hp 05 2 each 200 hp motors, etc.
b/ Four motor application, i.e., 2,000 hp = 4 each 500 hp motors, etc.
Capacities for municipal solid waste.
-------
Enterprise Company
616 S. Santa Fe
Santa Ana, California 92705
Machine type: Hammermill
The Enterprise Cothpany. manufactures shredders, hoggers, and balers
for paper and cardboard. Their hammermills have a unique helix arrangement
of hammers so that only one hammer is striking the waste material at any
one time. Their machines are top-feed and can be obtained with either bottom
or side discharge. They have no units in operation processing municipal
refuse; however, the installations described on the data sheet have been con-
tracted for. The capacities shown are for corrugated cardboard and paper.
The company normally sells their machines direct, although they prefer to
offer a turn-key installation.
103
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ENTERPRISE COMPANY, SANTA ANA, CALIFORNIA
FEED
MODEL NO. CAPACITY* SPEED OPENING
OR SIZE HORSEPOWER* (TPH) (rpm) (in.)
3236EH
25 -
100
2
-
3
3236EC
25 -
125
2
-
3
3248EH
25 -
100
2
-
4
3248EC
25 -
125
2
-
4
3260EH
25 "
100
2
-
5
3260EC
25 -
125
2
-
5
4436EC
75 -
250
3
-
5
4448EC
75 -
250
3
-
6
4460EC
75 -
250
3
-
8
4472EC
75 -
250
3
-
10
4484EC
75 -
250
3
-
12
5236EC
100
- 400
6
-
15
5248EC
100
- 400
8
-
15
5260EC
100
400
8
-
18
5272EC
100
- 400
8
-
25
5284EC
100
- 400
8
-
30
* Throughput material for horsepower and capacity listed
Capacities for newspaper and corrugated material.
DIMENSIONS (in.)
LENGTH WIDTH HEIGHT
WEIGHT FEED CAPITAL
(lb) METHOD COST
60 80
60 100
72 82
72 100
84 80
84 100
64 126
76 126
88 126
100 126
112 1.26
70 150
84 150
96 150
108 150
120 150
12,000 Top
13,000
13,000
15,000
15,000
16,000
20,000
21,000
22,000
23,000
24,000
24,000
25,000
26,000
27,000
28,000
50
60
50
60
50
60
72
72
72
72
72
84
84
84
84
84
-------
Gruendler Crusher and Pulverizer Company
2915 North Market Street
St. Louis, Missouri 63106
Machine type: Hammermill
the Gruendler Company has been manufacturing hammermills, size
reduction equipment and material handling equipment since 1885. Their
machines for shredding municipal refuse are top-feed hammermills; discharge
is at the bottom. They have their machines in several installations where
refuse is being processed. The oldest installation is the St. Louis Munici-
pal Refuse Plant, where municipal refuse is being shredded and used as fuel
by the local electric company. They produce their hammermills in two
configurations: (1) for primary size reduction; and (2) for secondary size
reduction.
105
-------
GRUENDLER CRUSHER AND PULVERIZER COMPANY, ST. LOUIS, MISSOURI
c
a>
MODEL NO.
CAPACITY* SPEED
FEED
OPENING
DIMENSIONS (in.)
WEIGHT
OR SIZE
HORSEPOWER* (TPH) (rpm)
(in.)
LENGTH
WIDTH
HEIGHT
(lb)
48-5
36
X
46
74
100
48
18,000
60-5
36
X
58
74
116
48
-22,700
72-5
(Power and capacity to be
36
X
70
74
133
48
25,000
62-50
determined upon application)
44
X
62
96
119
72
43,500
72-50
44
X
72
96
129
72
50,000
84-50
44
X
84
96
141
72
56,300
96-50
44
X
96
96
153
73
62,800
60-60
50
X
60
122
130
96
79,500
84-60
50
X
84
122
154
96
99,300
96-60
50
X
96
122
166
96
106,800
108-60
50
X
108
122
178
96
113,500
84-7
66
X
84
150
152
120
109,000
108-7
66
X
108
160
176
120
131,000
120-7
78
X
120
184
188
144
175,000
FEED CAPITAL
METHOD COST
Top
* Throughput material for horsepower and capacity listed.
-------
Hammermills, Inc.
625 "C" Avenue, N.W.
Cedar Rapids, Iowa 52405
Machine type: Hammermill
Hammermills, Inc., has been manufacturing size reduction equipment
for over 60 years. They manufacture a full line of size reduction and
materials handling equipment, including shredders, conveyors, feeders, and
hoppers. The company produces numerous kinds of special purpose hammermills.
Their refuse shredders have alternating short and long hammers on the rotors,
and use a replaceable cutter bar. Input is side feed and they recommend a
compression feed roller device to eliminate feed problems, etc. Discharge
is through the bottom. They have several units in operation processing
refuse and have accumulated proprietary data on operational costs. The
company prefers to do a turn-key job including design fabrication and
installation of the shredding facility.
107
-------
HAMMERMILLS, INCORPORATED, CEDAR RAPIDS, IOWA
FEED
MODEL NO. CAPACITY* SPEED OPENING
OR SIZE HORSEPOWER* (TPH) (rpm) (in.)
4260 600 24
6060 800 32
6080 1,000 40
74104 2,000 80
96104 3,000 120
* Throughput material for horsepower and capacity listed
Capacities based on municipal solid waste.
DIMENSIONS (in.) WEIGHT FEED CAPITAL
LENGTH WIDTH HEIGHT (lb) METHOD COST
Side
-------
The Heil Company
3000 W. Montana Street
Milwaukee, Wisconsin 53201
Machine type: Vertical shaft hammermill
The Heil Company manufactures a series of three refuse pulverizers
based on a design similar to the English Tollemache machine, under license
to the Tollemache Company. The machine is a vertical shaft hammermill with
an upper conical section for primary size reduction and a lower grinding
section. A unique feature of the machine is the ballistic rejection of heavy
or resilient objects which are not reducible by the machine. Feed is at the
top and discharge is horizontal at the bottom. The Tollemache machine has
seen extensive application in Europe and Heil has several installations in
the U.S. processing municipal refuse. One of the units is located at the
refuse processing plant at Madison, Wisconsin. The Heil Company prefers to
sell a solid waste system, including all conveyors, etc. The larger model
is rated at 40 ton/hr, but no machines of this size have been built.
109
-------
HEIL COMPANY, MILWAUKEE, WISCONSIN
FEED
MODEL NO.
CAPACITY*
SPEED
OPENING
DIMENSIONS
(in.)
WEIGHT
FEED CAPITAL
OR SIZE
HORSEPOWER*
(TFH)
(rpm)
(in.)
LENGTH WIDTH
HEIGHT
(lb)
METHOD COST
4 2D
200
15
30 x 48
42F
250
20
42 x 60
92A
500
40
48 x 84
* Throughput material for horsepower and capacity listed.
Capacities based on municipal solid wastes
-------
Jeffrey Manufacturing Company
P. 0. Box 1879
Columbus, Ohio 43216
Machine type: Hammermill
The Jeffrey Manufacturing Company produces materials handling
equipment. They manufacture a series of seven sizes of hammermill-type
refuse pulverizers. A unique feature of their machine is the drive
system. The rotor is belt driven and has a heavy flywheel to maintain
speed. They do not list any installations in the U.S. for processing
municipal refuse. However, their advertising literature states that
throughput capacities are based on unsorted refuse.
Ill
-------
JEFFREY MANUFACTURING COMPANY, COLUMBUS, OHIO
FEED
MODEL NO. CAPACITY* SPEED OPENING DIMENSIONS (in.) WEIGHT FEED CAPITAL
OR SIZE HORSEPOWER* (TPH) (rpni) (in.) LENGTH WIDTH HEIGHT (lb) METHOD COST
432i/ 100 7
548£/ 250 15
748 400 25
766k/ 1,000 35
770SJ 500 35
990SJ 750 55
913—/ 2,000 75
48.
48
66
70
90
102
* Throughput material for horsepower and capacity listed,
a/ Presorting of large items required,
b/ For bulky items only.
cj Machine capacity can be increased 12-1/2% for bulky items.
Capacities based on municipal solid waste.
-------
Pennsylvania Crusher Corporation
Box 100 A
Broomall, Pennsylvania 19008
Machine type: tiammermill
The Pennsylvania Crusher Corporation has been manufa.cturine a
line of material reduction equipment for over 65 years. They manufacture
three lines of shredders—standard industrial, heavy duty, ana bulky wastes.
Their hammermill is a standard top-loading, bottom-discharge unit. The
advertising literature indicates that machine capacities are based on
processing refuse. The literature also indicates that they have several
installations processing municipal refuse.
113
-------
PENNSYLVANIA CRUSHER CORPORATION, BROOMALL, PENNSYLVANIA
MODEL NO.
OR SIZE
HORSEPOWER*
CAPACITY* SPEED
(TPH) (rpm)
FEED
OPENING
(in.)
DIMENSIONS (in.)
LENGTH WIDTH HEIGHT
WEIGHT
(lb)
FEED
METHOD
CAPITAL
COST
SI 20 24
25
1 - 25/
16 x 25
1,800
T
>P
$ 3,600
SI3030
60
2 - 52/
25 x 35
6,000
7,600
SI3640
125
5 - 10i/
29 x 44
8,000
9,600
SH3640
200
10 - 15k/
25 x 40
13,500
14,000
SH3666
300
15 - 20k/
25 x 60
12,500
16,000
SH4454
400
20 - 30k/
32 x 56
20,000
21,500
SH4478
600
30 - 40y
32 x 80
28,000
28,000
SH5484
800
40 - 50^/
42 x 84
48,000
42,000
SXH6060
800
25 - 30£/
67 x 61
83,000
65,000
SXH6080
1,200
30 - 50£/
67 x 81
100,000
74,000
SXH72104
2,000
50 - 75SJ
ITJ
o
H
o
00
150,000
130,000
SXH96104
3,000
75 - 100£/
105 x 164
250,000
*
195,000
* Throughput material for horsepower and capacity listed.
a/ Capacity based on selected waste—density of 10 - 15 lb/ft^.
b/ Capacity based on packer truck waste--density of 15 - 20 lb/ft-*.
c/ Capacity based on solid waste (except automobiles and demolition waste) at 15 - 70 lb/ft^.
-------
Stedman Foundry and Machine Company, Inc.
Aurora, Indiana 47001
Machine type: Hammermill
The Stedman Company has been manufacturing size reduction equip-
ment for over 50 years. They make several series of hammermills, two of
which are suitable for processing municipal wastes. They have several of
their machines in composting operations and being used for secondary size
reduction. Their machines are top-loading, bottom-discharge types. The
hammers are a reversible chisel point type.
115
-------
STEDMAN FOUNDRY AND MACHINE COMPANY, AURORA, ILLINOIS
FEED
MODEL NO. CAPACITY* SPEED OPENING
OR SIZE HORSEPOWER* (TPH) (rpm) (in.)
20-12 18 x 13
20-16 (Capacities and power to be 18 x 17
24-20 determined upon application) 21 x 21
24-24 21 x 25
24-30 21 x 31
30-16 26 x 17
30r20 26 x 21
30-24 26 x 25
30-32 26 x 33
36-24 32 x 25
36-30 32 x 31
36-36 32 x 38
36-42 32 x 44
42-54 38 x 56
42-60 38 x 62
42-84 38 x 86
* Throughput material for horsepower and capacity listed.
DIMENSIONS (in.)
LENGTH WIDTH HEIGHT
WEIGHT FEED CAPITAL
(lb) METHOD COST
55
53
34
3,800
55
58
34
4,150
62
65
40
6,700
62
71
40
7,200
62
77
40
8,000
74
67
48
9,500
74
71
48
10,300
74
80
48
11,000
74
89
48
12,700
88
87
56
19,000
88
95
56
17,000
88
102
56
19,500
88
110
56
21,000
118
99
64
32,400
124
99
64
33,300
148
99
64
35,000
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Williams Patent Crusher and Pulverizer Company
2701 North Broadway
St. Louis, Missouri 63102
Machine type: Hammermill
The Williams Company is a large manufacturer of hammermills.
They manufacture an extensive line of shredders, hamraermills, and related
equipment. Their line of refuse shredders are top-feeding, bottom-discharge
hammermilis. The company has numerous installations where their machines
are processing municipal solid wastes. The company prefers to do a turn-
key job, installing a complete size reduction system.
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WILLIAMS PATENT CRUSHER AND PULVERIZER COMPANY, ST. LOUIS, MISSOURI
FEED
MODEL NO. CAPACITY* SPEED OPENING DIMENSIONS (In.) WEIGHT FEED CAPITAL
OR SIZE HORSEPOWER* (TPH) (rpm) (in.) LENGTH WIDTH HEIGHT (lb) METHOD COST
(Williams manufacturers over 30 different size basic shredders. Horsepower,
capacity, feed opening, arid weight are determined upon application.)
* Throughput material for horsepower and capacity listed.
oo
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APPENDIX I
EXISTING MUNICIPAL SOLID WASTE SIZE REDUCTION INSTALLATIONS
The following table presents a listing of the known installations
(either operating or under construction) for size reduction of municipal
solid waste. Because many of these installations are privately owned, or
partially supported by federal, state, or local grants, their operational
status may change at any time. For further information, first contact
should be made with the machine manufacturer.
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EXISTING MUNICIPAL SOLID WASTE SIZE REDUCTION INSTALLATIONS
LOCATION
Alamosa, Colorado
Altoona, Pennsylvania
Atlanta, Georgia
Brooklyn, New York
Chicago, Illinois
Columbus, Bartholontew County,
Indiana
Dearborn, Michigan
DeKalb County, Georgia
Des Moines, Iowa
Edmonton, Alberta, Canada
Gainesville, Florida
High Point, North Carolina
Houston, Texas
Indianapolis, Indiana
MANUFACTURER
Heil
Stedman
American
Pennsylvania Crusher
Hammermills, Inc.
Heil
Williams
Eidal
and
Heil
Enterprise
Eidal
Williams
Eidal
Williams
Hazemag
SIZE
20 TPH
4 - 15 TPH
each
COMMENTS
Fairfield-Hardy compost plant.
Ecology, Inc., compost plant.
Goose Island Plant
Model 680
2 each,
Model 1000
3 each, 15 TPH
Digester Operation
Model 400
Model 475
Model 1000
Model 475
Lone Star Organics, compost plant
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EXISTING MUNICIPAL SOLID WASTE SIZE REDUCTION INSTALLATIONS (Continued)
LOCATION
Los Gatos, California
Louisville, Kentucky
Madison, Wisconsin
Menlo Park, California
Milford, Connecticut
New Castle County, Delaware
New York, New York
New York, New York
Pompano Beach, Florida
Providence, Rhode Island
San Diego, California
St. Louis, Missouri
Syracuse, New York
Tacoma, Washington
MANUFACTURER
SIZE
COMMENTS
Pennsylvania Crusher 3 - 30 TPH The Sira Corporation
Williams
Heil
Eidal
Eidal
Gruendler
Enterprise
Enterprise
Heil
Eidal
Williams
Gruendler
Eidal
Williams
Model 680
15 TPH
Model 1000 Combustion Power, Inc.
2 - Model 1000
4 - 50 TPH
15 TPH
Model 1000
Model 475
45 TPH
Model 1000
Model 680
New Castle County Public Works
Department
Ponte Brothers
Meadowlands Plant
Northeast Compost, Inc.
San Diego Public Works
Department
St. Louis Refuse Department
Tacoma Public Works
Department
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EXISTING MUNICIPAL SOLID WASTE SIZE REDUCTION INSTALLATIONS (Concluded)
LOCATION MANUFACTURER SIZE COMMENTS
Vancouver, Washington Eidal Model 1000 Vancouver Sanitary Service
Washington, D.C. Williams Model 780
Willoughby, Ohio Eidal Model 400
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APPENDIX II
MANUFACTURERS OF SIZE REDUCTION EQUIPMENT
Al-jon, Inc.
P.O. Box 592
Ottumwa, Iowa 42502
The American Baler Company
1000 Hickory Street
Bellevue, Ohio 44811
American Pulverizer & Crusher Company
1249 Macklind Avenue
St. Louis, Missouri 63110
Atomic Disposer Corporatiuii
605 East Banning Avenue
Compton, California
The Bauer Brothers Company
P.O. Box 968
Springfield, Ohio 45501
Benson Industries, Ltd.
1515 Pemberton Avenue
North Vancouver
British Columbia, Canada
The Black-Clawson Company
Middletown, Ohio 45042
Buffalo Hammer Mill Corporation
1245 McKinley Parkway
Buffalo (Lackawanna), New York 14218
Buhler Brothers
8923 Wayzetta Boulevard
Minneapolis, Minnesota
Centriblast Corporation
Subsidiary of the Joy Manufacturing
Company
P.O. Box 4488
Parkway West, Oliver Building
Pittsburgh, Pennsylvania 15222
Champion Line Machinery Company
229 Meadow Road
Rutherford, New Jersey
Conservomatic Corporation
113 Bala Avenue
Oreland, Pennsylvania
Consolidated Baling Machine Company
402 Third Avenue
Brooklyn, New York
Denver Equipment Company
606 Broadway
Denver, Colorado
Dorr-Oliver, Inc.
77 Havemeyer Lane
Stamford, Connecticut 06904
East Chicago Machine Tool Corporation
Balemaster Division
4801 Railroad Avenue
East Chicago, Indiana
Ecological Assistance Corporation
18-01 Pollitt Drive
Fairlawn, New Jersey 07401
Bus Boy Disposer, Inc. Environmental/One Corporation
13150 Saticoy Street 2773 Balltown Road
North Hollywood, California 91605 Schenectady, New York
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Eidal International Corporation
Subsidiary of Southwest Factories, Iric
250 Woodward Road, S.E.
P.O. Box 2087
Albuquerque, New Mexico 87103
The Engineer Company
Teeple Place, P. 0. Box 39
South Plainfield, New Jersey 07080
The Enterprise Company
616 South Santa Fe
Santa Ana, California
The Fitzpatrick Company
812 Industrial Drive
Elmhurst, Illinois
FMC Corporation
Hoopeston, Illinois 60942
French Oil Mill
Piqua, Ohio
Gondard
3000 West Montana Street
Milwaukee, Wisconsin 53201
Gruendler Crusher & Pulverizer Company
2915 North Market Street
St. Louis, Missouri 63106
Hammermills, Inc.
Division of Pettibone Mulliken
Corporation
625 "C" Avenue, N.W.
Cedar Rapids, Iowa 52405
Hazemag Shredders
Distributor: Hazemag U.S.A., Inc.
60 East 42nd Street
New York, New York 10017
The Heil Company
3000 West Montana Street
Milwaukee, Wisconsin 53201
Industrial Shredder & Cutter Company
711 South Ellsworth Avenue
Salem, Oh io
In-Sink-Erator Manufacturing Company
4700 21st Street
Racine, Wisconsin 53406
International Disposal Corporation
Shawnee, Oklahoma
Jacksonville Blow Pipe Company
2017 Thelma Avenue
Jacksonville, Florida 32206
The Jeffrey Manufacturing Company
274 East First Street
Columbus, Ohio 43216
David J. Joseph Company
2906 Vernon Place
Cincinnati, Ohio 45219
Kemp Manufacturing Company
1027 East 20th Street
Erie, Pennsylvania 16512
Koehring Company
1701 West Wisconsin Avenue
Milwaukee, "Wisconsin 53201
John S. Lane & Son, Inc.
East Mountain Road
Westfield, Massachusetts 01085
Logemann Brothers Company
3150 West Burleigh Street
Milwaukee, Wisconsin 53245
Luria Brothers & Company, Inc.
20521 Chagrin Boulevard
Cleveland, Ohio 44122
Master Disposers, Inc.
309 Ludlow Avenue
Cincinnati, Ohio
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Miller Franklin, Inc.
34 Meadow
East Orange, New Jersey
Mil-Pak Systems, Inc.
Unit of SFM (Seneca Falls
Machine) Corporation
2414 Morris Avenue
Union, New Jersey 07083
Mitts and Merrill, Inc.
Subsidiary of Waldo
American Corporation
109 McCoskry
Saginaw, Michigan 48601
Munro, H. F. & Sons, Inc.
2406 North Mascher and York Streets
Philadelphia, Pennsylvania
Newell Manufacturing Company
Box 9132
San Antonio, Texas 78204
Ogden Metals, Inc.
20521 Chagrin Boulevard
Cleveland, Ohio 44122
Oliver W. W. Manufacturing Company
8 Beard Avenue
Buffalo, New York
Pennsylvania Crusher Corporation
Subsidiary of Bath Industries, Inc.
600 Abbott Drive
Brooma11, Pennsylvania 19008
Perfection-Cobey Company
Cobey Refuse Handling Division
South East Street
Galion, Ohio
The Pettibone Companies
625 "C" Avenuei N.W.
Cedar Rapids, Iowa 52405
Piezo Manufacturing Corporation
P. 0. Box 120-T
Madiaon, New Jersey
The Proler Steel Corporation
7501 Wallisville Road
Houston, Texas
Qualheim, Inc.
1225-14th Street
P.O. Box 368
Racine, Wisconsin 53403
Richards Shear Company
7201 East Marginal Way
Renton, Washington
Ripsteel Corporation
Sales agent: Beltain-Drissen
570 Livernois Avenue
Ferndal, Michigan 48220
Salvajor Company
4530 East 75th Terrace
Kansas City, Missouri 64132
Sedberry J. B. Inc.
Dept. 83
Tyler, Texas
Somat Corporation
Box 831
Coatesville, Pennsylvania 19320
Sprout, Waldron & Company, Inc.
Muncy, Pennsylvania 17756.
Stedman Foundry & Machine Company, Inc.
Subsidiary of United Engineering and
Foundry Company
Indiana and Franklin Streets
Aurora, Indiana 47001
Sturtevant Mill Company
Park and Clayton Streets
Boston, Massachusetts 02122
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Swimquip, Inc.
3301 Gilman Road
El Monte, California 91732
The W-W Grinder Corporation
2957 North Market
Wichita, Kansas 67219
Tollemache
3000 West Montana Street
Milwaukee, Wisconsin 53201
Young Machinery Company, Inc
Robinson Division
Fainter Street
Muncy, Pennsylvania
Union Manufacturing & Gauge Company
511 North State
Syracuse, New York
Von Roll, Ltd.
P.Q. 2120 Sherbrooke Street East
Montreal, Quebec, Canada
Wascon Systems, Inc.
Subsidiary of Robins and Meyers, Inc.
21U Bona ir Avenue
Hatboro, Pennsylvania 19040
Waste Doctors, Inc.
Subsidiary of Cumberland Engineering Company, Inc.
P.O. Box 6065
Providence, Rhode Island 02904
Waste King Universal
3300 East 50th Street
Los Angeles, California 90058
Wastex, Solar Industries
Wayne Manufacturing Company
1201 East Lexington Street
Pomona, California 91766
Wiley Miner Associates, Inc.
Box 392
Cranbury, New Jersey
Williams Patent Crusher and Pulverizer Company
2701 North Broadway
St. Louis, Missouri 63102
935
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