SMALL MODULAR INCINERATOR SYSTEMS WITH HEAT RECOVERY:

 A TECHNICAL, ENVIRONMENTAL, AND ECONOMIC EVALUATION

                  Executive Summary
          This report (SW-797)  was prepared
    under contract for the Office of Solid Waste
               by Richard Frounfelker.
        U.S.  ENVIRONMENTAL  PROTECTION AGENCY

                        1979

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     An environmental protection publication (SW-797) in the solid waste
management series.  Mention of commercial products does not constitute
endorsement by the U.S. Government.  Editing and technical content of this
report were the responsibilities of the Resource Recovery Division of the
Office of Solid Waste.

     Single copies of this publication are available from Solid Waste
Information, U.S. Environmental Protection Agency, Cincinnati, OH  45268.
                                     11

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                                   FOREWORD
     This report is a summary of a technical, environmental, and economic
evaluation of two small modular incineration-heat recovery facilities:  one
in the plant of the Truck Axle Division of Rockwell International Corporation
in Marysville, Ohio, and the other in the Municipal North Shore Energy Plant
in North Little Rock, Arkansas.  The evaluation program was sponsored and
directed by the Environmental Protection Agency (EPA) and the California
State Solid Waste Management Board and was conducted under EPA Contract
No. 68-01-3889 by Systems Technology Corporation (SYSTECH), Xenia, Ohio.
The report was prepared by Richard Frounfelker, Staff Engineer of SYSTECH,
for submittal to EPA.

     The report explains the controlled air concept of the modern two-
chamber incinerator, chronicles its development and application, and sum-
marizes currently available systems for small-scale usage.  Then the report
details each of two facilities selected for the evaluation and presents the
technical, environmental, and economic evaluation for each facility.  In
addition, the report projects the operating costs for the two facilities under
optimum operating conditions and for municipal and industrial facilities in
general.

     Since the two evaluated facilities operate under different conditions
with one burning municipal waste and the other industrial waste, they were
not compared.  Moreover, the reader is cautioned not to draw comparative
conclusions.

     The full report, intended for design engineers and other specialists
requiring in-depth data, will be made available for purchase from the
National Technical Information Service, Springfield, VA  22161.
                                     iii

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                                   ABSTRACT

     This program involved a technical, environmental, and economic assess-
ment of the feasibility of utilizing small modular incinerator systems for
solid waste disposal in municipal and industrial applications.  The assess-
ment was implemented by (1) overviewing the state-of-the-art, (2) selecting
two operational sites (one municipal and one industrial) representative of
the state-of-the-art, and (3) subjecting these two sites to a rigorous field
evaluation.  The two facilities selected for this study were a municipal
incinerator plant with a Consumat system in North Little Rock, Arkansas, and
an industrial incinerator facility with a Kelley system in the plant of the
Truck Axle Division of the Rockwell International Corporation in Marysville,
Ohio.  This selection was the result of a nationwide survey to find those
two facilities which best satisfied several criteria.  The principal selec-
tion requirements were a solid waste processing module with heat recovery
and a capacity of 50 tons or less per day and its being representative of
current technology, designs, and operational procedures.

     Preparatory to the detailed description and evaluation of the two
facilities, the report explains the controlled air concept of the two-
chamber incinerator and briefly discribes its development and application.
In addition, as a technical guide for the review and selection of currently
available systems, the report details, according to available information,
the 17 sources whose modular incinerators represent state-of-the-art
technologies.

     The technical evaluation presents the results of three weekly field
tests at each site.  The data was used to calculate the following for each
system:  the mass balance, the incinerator efficiency, the energy balance,
the heat recovery efficiency, and the overall effectiveness of the system as
a solid waste disposal facility.

     The environmental evaluation presents the effects of the incinerator-
heat recovery operation on the environment, specifically the atmosphere, the
discharged process water, the landfills for refuse disposal, and the plant
areas.  An EPA Level One assessment presents a detailed analysis of the
emissions.

     The economic evaluation presents a detailed accounting of facility
(1) capital costs, (2) operating and maintenance costs, (3) revenues, and
(4) net operating costs.

     Since the two systems differ in many respects and operate on dissimilar
waste streams, they are not compared.

     This report was submitted in fulfillment' of Contract Number 68-01-3889
by Systems Technology Corporation under the sponsorship of the U.S. Environ-
mental Protection Agency.  This report covers the period October 1977 to
March 1979.
                                      iv

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                                   CONTENTS

Foreword	   ±±±
Abstract	    iv
Figures	   vii
Tables  	     x
Acknowledgment	   xli

     1.   Introduction and Summary  	    1
               Program objective, background, and scope 	    1
               Current modular incinerator technology ... 	    2
                    Concept 	    2
                    Current systems 	    2
               Summary of selected systems  	 .    3
                    Technical capabilities  	    3
                    Environmental acceptability .....  	 •   4
                    Economic effectiveness  	    4
     2.   The Small Modular Incinerator 	    6
               Controlled air incineration  ....  	    6
                    Introduction  	    6
                    Feeding mechanism 	    7
                    Primary chamber 	    8
                    Secondary chamber 	    8
                    Temperature control 	    8
                    Residue removal 	 .    9
                    Energy recovery 	    9
                    Waste consumption 	    9
                    Stack emissions	    9
               History of controlled air incineration ... 	   10
                    Introduction  	  .....   10
                    Design evolution  	   10
               Currently available modular incinerators 	   11
     3.   Overview of Facilities and Their Evaluations  	   19
               Evaluation Overview  	   19
               North Little Rock facility	   19
                    Description	   19
                    Operation	   21
                    Introduction to test program	   24
                    Technical evaluation  	   25
                    Environmental evaluation  	   31
                    Economic evaluation .  .  .	   38

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                        CONTENTS (concluded)

          Marysville facility  	    42
               Description	    42
               Operation	    47
               Introduction to test program	    47
               Technical evaluation  .  .
               Environmental Evaluation
               Economic evaluation .  .  .
4.   Operating Cost Projections  . .  .  .
          Evaluated facilities 	
          Facilities in general  . .  .  .
47
53
56
60
60
60
                                     vx

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                                 FIGURES
Number
   1   Operational ranges (stoichiometric air percentage and
       temperature) for controlled air incinerators  	   7

   2   Configuration of two horizontal cylindrical
       chambers with one above the other	14

   3   Configuration of two horizontal rectangular chambers
       with one above the other	-	14

   4   Configuration of Burn-Zol's two vertical cylindrical
       chambers with one above the other	15

   5   Configuration of Lamb-Cargate's two vertical cylindrical
       chambers with one above the other	16

   6   Configuration of Scientific Energy Engineering's
       incinerator with an auger in the primary chamber	17

   7   Configuration of Giery's incinerator with a rotary
       grate in the primary chamber	/.....  17

   8   Configuration of C. E. Bartlett's incinerator with a
       rotary primary chamber	  18

   9   Configuration of Clear Air's incinerator-heat recovery
       system with two horizontal rectangular chambers aligned
       one after the other	18

  10   Vicinity map of North Little Rock facility	20

  11   Plant layout of North Little Rock facility  	  21

  12   Three-dimensional drawing of incineration-heat recovery
       module in North Little Rock facility	  22

  13   Cross section of incinerator module in North Little
       Rock facility	«  23

  14   Flow diagram of incineration-heat recovery processes in
       North Little Rock facility	24
                                    VII

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                           FIGURES (continued)
Number
Page
  15   Mass balance for incineration-heat recovery processes in
       North Little Rock facility during the 118.5-hour October
       field test	27

  16   Energy balance for incineration-heat recovery processes in
       North Little Rock facility during the 118.5-hour October
       field test	28

  17   System temperature versus loading sizes and events in North
       Little Rock facility	29

  18   Stack emission during heavy and light loading periods in
       North Little Rock facility	30

  19   In-plant noise-level plot for North Little Rock facility.  .   35

  20   Outside-plant noise-level plot for North Little Rock
       facility	36

  21   Vicinity map of Marysville (Rockwell International)
       facility	42

  22   Functional schematic of incineration-heat recovery
       processes in Marysville facility  	   43

  23   Three-dimensional,  cutaway drawing of incinerator
       module in Marysville facility 	   44

  24   Plant layout of Marysville facility 	   45

  25   Flow diagram of incineration-heat recovery processes in
       Marysville facility 	   46

  26   Mass balance for incineration-heat recovery processes
       in Marysville facility during the 120-hour (75.5-hour heat
       recovery) July field test	49

  27   Energy balance for incineration-heat recovery processes in
       Marysville facility during the 120-hour (75.5-hour heat
       recovery) July field test	50

  28   System temperatures during peak loading periods in
       Marysville facility 	   51
                                  viii

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                           FIGURES (concluded)
Number
  29
  30
  31
  32
Stack emissions during peak loading periods in
Marysville facility 	
In-plant noise-level plot for Marysville facility 	

Estimated operating cost as a function of refuse feed rate,
shifts per week, and operating percentage of rated capacity
for municipal small modular incinerators  .........

Estimated operating cost as a function of refuse feed
rate, shifts per week, and operating percentage of rated
capacity for industrial small modular incinerators  . .  .  .
Page


 52

 56



 64



 65
                                    IX

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                                 TABLES
Number                                                             Page

   1   Manufacturers of Modular Incinerators 	   12

   2   Addresses and Telephone Numbers of Modular
       Incinerator Manufacturers 	   13
   3   North Little Rock Weekly Refuse Composition for
       March, May,  and October Tests  	
  11

  12

  13
                                                             26
       North Little Rock Pollutant Emission Rates  for
       October Test	31
       North Little Rock Summary of  Stack Emissions  for
       March, May,  and October Tests 	
                                                             32
   6   North Little Rock Residue  Leachate  Parameter  and
       Component Values	34

   7   North Little Rock Summary  of  Elements Detected in
       Stack Emission Filters   	  37

   8   North Little Rock Actual Capital  Costs   	  38

   9   North Little Rock Unit  Cost Data	39
  10    North Little Rock Projected Annual Operating and
       Maintenance Costs   	
                                                             40
North Little Rock Projected Annual Revenues 	   41

North Little Rock Projected Annual Net Operating Costs  .  .   41
Marysville Weekly Refuse Composition for April,
July, and August Tests  	
                                                                   48
  14   Marysville Pollutant Emission Rates for July Test	53

  15   Marysville Summary of Stack Emissions for April, July,
      and August Tests	54
 16   Marysville Residue Leachate Parameter and Component
      Values   	
                                                             55
                                    x

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                           TABLES (concluded)
Number
                                                            Page
  17   Marysville Summary of Elements Detected in Stack
       Emission Filters  	   57
  18

  19

  20
Marysville Capital Costs

Marysville Unit Cost Data
Marysville Projected Annual Operating and Maintenance
Costs per Cost Center	
  21   Marysville Net Operating Cost by System Function

  22
57

58


59

59
North Little Rock Projected Optimum Operating and
Maintenance Costs 	   61
  23   North Little Rock Projected Optimum Annual Revenues .  .

  24   Marysville Projected Optimum Operating and Maintenance
       Costs 	
  25   Marysville Projected Optimum Net Operation Cost
                                                             61


                                                             62

                                                             62
                                    xi

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                                 ACKNOWLEDGMENT
      This evaluation program was performed under EPA Contract No.  68-01-3889,
 "Technical and Economic Evaluation of Small Modular Incinerator Systems  with
 Heat Recovery."

      The EPA project officer was David B.  Sussman of the Office of Solid
 Waste,  Washington,  D.C.   The coordinator for the California State  Solid
 Waste Management Board was Robert Harper,  Waste Management  Engineer.

      On behalf of Systems Technology Corporation,  the author is pleased  to
 acknowledge the guidance and support of David B.  Sussman and Robert Harper
 and the cooperation of the plant engineers and staff members and the manu-
 facturer representatives who generously assisted with the testing  at the
 Rockwell International Corporation facility in Marysville,  Ohio, and at  the
 North Shore Energy  Plant in North Little Rock,  Arkansas.

      The author is  also  grateful to Arthur Young &  Company  for its collabo-
 ration  in the economic evaluation and to all his company colleagues who
 contributed to the  collection of the test  data and  the development of  this
'report.   Of the latter,  the author is particularly  thankful to Gerald  Degler,
 Ned Kleinhenz,  and  Rick  Haverland.
                                    xii

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                                   SECTION 1

                           INTRODUCTION AND SUMMARY
PROGRAM OBJECTIVE, BACKGROUND, AND SCOPE

     This study consisted of a technical, environmental, and economic evalua-
tion of small modular incinerator systems with the overall objective being to
determine the feasibility of their usage for solid waste disposal and -heat
recovery in municipal and industrial environments.  The evaluation aspects of
this report include (1) sufficient data and procedures to assess all technical,
environmental, and economic aspects of small, modular incineration-heat recovery
systems; (2) a technical guide for the review and selection of currently
available systems; (3) sufficient manufacturer and field test data to apply
and/or adapt} the current systems to particular needs; and (4) a data base for
the future analysis and appraisal of advanced systems.

     Recent technological advances and economic and environmental develop-
ments prompted the Office of Solid Waste Management of the Environmental
Protection Agency to initiate this study.  Some of the more significant
advances are as follows:  First, the incinerator manufacturers have success-
fully developed the two-chamber, controlled air incinerator for optimum
efficiency and significantly reduced particulate emissions.  Second, they
have designed incinerators with integrated control systems to ensure their
economic feasibility and efficient operation.  Third, the small modular
incinerator features simple and reliable operation, low maintenance costs,
and payback frequently within 3 to 4 years (primarily in an industrial
application).

     Several economic and environmental factors have given added impetus to
the attractiveness of the small modular incinerator with heat recovery.  For
example, municipalities are finding that such incinerators can address the
problems (1) of rising landfill costs or rapidly diminishing landfill sites,
(2) of complying with environmental pollution control regulations, and (3) of
offsetting capital costs for waste disposal equipment through the revenues of
recovered energy products and the savings of eliminated landfill expenses.
Similarly, industries are seeing the advantages of burning waste rather than
oil or gas  (1) to recover the waste energy,  (2) to save the expenditures for
landfill disposal, (3) to meet the threats of fuel curtailments and rising
costs,  (4) to gain tax credits, and (5) to comply more readily with environmen-
tal control regulations.  Furthermore, public opinion and government enactments
lend strong encouragement and support to the widespread usage of the small
modular incinerator with heat recovery because of its resource recovery and
environmental control potential.

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      This report explains the controlled air concept of the modern two-
 chamber incinerator, chronicles its development and application,  and summarizes
 currently available systems designed for small-scale usage.  Then the report
 details each of two selected small-scale facilities and presents  the technical,
 environmental, and economic evaluation of each, but in no way attempts to com-
 pare the two different systems.  Finally, the 1978 economic data  of the two
 evaluated facilities were adapted to estimate the operating costs at municipal
 and industrial facilities in general.

      The two small incinerator facilities selected for intensive  evaluation
 were a municipal incinerator plant in North Little Rock,  Arkansas,  and an
 industrial incinerator in the plant of the Truck Axle Division of the Rockwell
 International Corporation in Marysville,  Ohio.   In the selection  of the two
 facilities,  each had to meet three criteria:   (1)  a capacity designed for
 50 tons or less of solid waste per day;  (2)  its integration with  heat recovery
 equipment;  and (3)  its incorporation of  the principles,  designs,  and operational
 procedures of current technology.
CURRENT MODULAR INCINERATOR TECHNOLOGY
Concept

     The modular  incinerators,
ary combustion chamber,  employ
of air required for  combustion
of their particulate emissions,
1960fs, and their technologies
generally consisting of a primary and a second-
controlled air techniques to reduce the amount
in the primary chamber and to lower the level
  These incinerators originated in the late
and applications expanded in the 1970's.
     The name "modular" was derived  from the  following:   (1) each unit is
identical,  (2) each unit operates independently, and  (3)  one or more units
can be readily integrated in an existing system as  the waste demand increases.
The terms "starved air," "substoichiometric," and "pyrolitic" denote the
different combustion processes in the primary chamber.  Sometimes these terms
are used to denote the entire incinerator system.

Current Systems

     A survey identified 16 manufacturers that produce incinerators capable of
processing 454 to 1816 kg/hr (1000 to 4000 Ib/hr) of  industrial and/or munici-
pal solid waste and of recovering the heat for energy production.  The primary
chambers in these incinerators operate under starved  air  (substoichiometric)
or excess air combustion conditions.  The incinerator systems can be grouped in
five basic physical configurations.  The larger systems have (1) automatic feeds
consisting of loading hoppers, conveyors, and screws; (2) loading rams, moving
grates, augers, and rotating chambers for continuous  refuse flow through the
primary chamber; and (3) heat recovery systems with fire  or water tube boilers
and other heat exchangers.

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SUMMARY OF SELECTED SYSTEMS

Technical Capabilities

Performance —
     At the North Little Rock municipal facility, where a Consumat incineration-
heat recovery system is operative, the Consumat module proved capable of ^
recovering about 55 percent of the energy burned and of reducing the municipal
solid waste 55 percent by weight and 94 percent by volume.  Over the past
3 years, 13 Consumat incinerators have been burning municipal waste.  Four of
these incinerators are integrated with heat recovery equipment.

     At the Marysville industrial facility, where a Kelley incineration-heat
recovery system is operative, the Kelley module proved capable of recovering
about 55 percent of the energy burned and of reducing industrial refuse
95 percent by volume.  Over the past four years, seven similar systems have
been burning industrial waste.  In addition, four units are burning municipal
waste but without heat recovery.

     The designs of both  systems  are still evolving.  Each new facility
introduces technological  advances based on the experience gained from the
previous installations.   These technological improvements have advanced to
'the stage where  the systems can burn waste and produce energy with  satisfactory
reliability.

Maintenance  and  Reliability —
     The routine maintenance  of both the  Consumat  and the Kelley  systems
consists principally  of  small refractory  repairs and replacement  of thermo-
couples and  other  switches, door  seals, and motors.  The maintenance require-
ments  specific to  each system are the weekly removal of  soot  from the boiler
tubes  in  the Consumat system  and  the weekly  cleaning of  the  induced draft  fan
blades  and  at least  the  semiannual cleaning  of  the boiler  tubes  in the  Kelley
system. The major maintenance requirement  of both systems  is  the refractory
replacement  in 3 to  8 years,  depending  on the operational mode.   In addition,
because of  its more  extensive control  system,  the  Consumat  module requires
more  maintenance on  the automatic control,  hydraulic,  and residue removal
 systems.   In general, modules burning municipal waste  require more maintenance
 than those  burning industrial refuse.   In addition, more operational interrup-
 tions must  be anticipated when burning  municipal waste because of the  jams
 caused by large metal objects in the waste and  the greater frequency of the
 above-mentioned routine maintenance.   Moreover,  the slag formed from the
 fusion of glass and metals frequently plugs air injection ports and degrades
 the refractory.
                   system with its 100-TPD capacity at the North Little Rock
 facility required nine personnel:  one supervisor, one clerk, one truck
 driver/and two operators for each of three shifts.  The Kelley system at the
 Marysville facility with its capacity of 12 TPD and limited operational usage
 of two shifts, 5 days per week, required 9nly one full-time operator per
 shift   As additional part-time assistance was required, it was usually supplied
 by the plant maintenance staff.  Neither facility required waste preprocessing,

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 although operators at both facilities removed such materials as pipe and wire
 before refuse loading and hand-loaded some materials,into the incinerator
 hopper to prevent jamming.

      The Consumat system includes (1) a remotely controlled display panel to
 instruct the loading operator on how large a load to collect and when to
 deposit it into the incinerator hopper, (2) an automatically modulated air
 control to maintain a desired temperature in each of the two combustion
 chambers, and (3) an automatic ash removal system.   The Kelley system allows
 the operator to judge the size and frequency of each refuse loading.   With
 the airflow preset to handle a specific waste stream,  only a high temperature
 lockout on the Kelley system prevents extreme refuse overloading.   In both
 systems,  overfeeding causes high temperatures in the secondary chamber,
 excessive gaseous emissions,  and wasted energy.   On the other hand,  under-
 feeding reduces the system throughput rate, and the resultant low chamber
 temperatures may require burning auxiliary fuel.  Therefore,  proper  feeding
 of the incinerators to ensure proper combustion is  essential for optimum
 incinerator performance.

 Environmental Acceptability

 Emissions Compliance—
      Neither facility had a high enough daily refuse consumption,  i.e.,  over
 50 tons per day per module or 250 tons  per day per  facility,  to  be considered
 under the Federal standard of performance  for new stationary  sources  or  the
 prevention of significant deterioration regulations.  Therefore, a new source
 review was not required  during the preconstruction  planning.   Both plants
 complied  with their respective state-imposed  emissions  standards and  building
 permits.   If either facility  had more than a  daily  250-ton  throughput, it
 would have been  subject  to  a  new source  review and  would have  required the
 best  available emissions control such as an electrostatic precipitator or a
 fabric filter.

      At both facilities,  the  gaseous emissions related  directly to the size
 of the load  fed  into  the incinerator.  The sulfur and nitrogen oxide  levels
 in the stack emissions were negligible.  At the North Little Rock  facility,
 the chloride  emissions varied from 100 to  600 mg/m3.  No direct relationship
was evidenced between the loading  or sizing of the  particulate emissions and
 the modulating air  supply.

EPA Level 1 Analysis—
     At both  facilities, 90 percent of the stack particulates were less than
 7 micrometers in diameter; the stack emissions had  a wide range of metals and
 halogens in minute amounts; and the residue had a high pH and contained
traces of many metals such as zinc, tin, lead, and  cadmium.

Economic Effectiveness

Capital Cost—
     For an incinerator with heat recovery, the capital cost of refuse
processed daily was computed at $15,000 per ton (based on 1977 dollars).

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The relationship between the capital cost per ton and the incinerator capacity
was found to be nearly linear up to a 200-TPD capacity.  A 12-TPD industrial
system would cost $220,000 to $300,000, while a 100-TPD municipal system with
a 300-meter steam condensate return line would cost about $1,500,000 (based
on 1977 dollars).

Operational Cost—
     On the basis of the test data, the optimum annual operating cost (based
on 1978 dollars) of a 100-TPD municipal facility would be $370,000.  With
optimum steam revenues and tipping fees of $305,000, the net annual operating
cost of this facility would be $65,000 or $3.01/Mg  ($2.72/ton) of refuse
processed.  For a 12-TPD industrial facility, the optimum annual operating
cost (based on 1978 dollars) would be $117,944.  Applying credits for disposal
savings and energy savings of $82,620 and $139,594, respectively, results in a
net savings of $104,270 or $31.94/Mg ($28.96/ton) of refuse processed.   The
facility finances are highly sensitive to the refuse processing rate, the
operating time, and the steam sales price.

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                                   SECTION 2

                         THE SMALL MODULAR INCINERATOR
CONTROLLED AIR INCINERATION

Introduction

     During the 1960?s virtually all operational incinerators were still
uncontrolled air units.  To ensure a high degree of combustion in these
incinerators, air was supplied in fixed amounts with a volume considerably
more than that required for stoichiometric combustion.  Consequently, large
quantities of both combustible and inert particulates were discharged to
the atmosphere with the exiting flue gases.

     In the late 1960*s the industry introduced the controlled air inciner-
ator, that is, an incinerator with an afterburner or an incinerator with a
primary and a secondary combustion chamber.  The term "controlled air"
denotes that the air flowing into the two combustion chambers is regulated
at a minimum rate.  The lower airflow requires less motor horsepower on the
fans and reduces the amount of the particulates entrained in the exiting
flue gases.

     The first, or primary, chamber is also called the lower chamber, the
combustion chamber, or the gasifier.  Similarly, the second, or secondary,
chamber is also called the upper chamber, the ignition chamber, the after-
burner, or the thermal reactor.

     The term "modular" as a descriptor for the controlled air incinerator
developed as follows:  The controlled air incinerators designed for burning
commercial and industrial waste have been constructed of integral components,
one for the primary chamber, one for the secondary chamber, and so on.
Each component has been assembled and packaged in the factory for immediate
on-site installation.  Only electrical, fuel, water, and gas duct connections
are required at the installation site.  When the waste volume has exceeded
the capacity of the installed units, additional incinerators have been
incorporated to meet the increased demand.  Since the additional incinerators
are constructed and function as modules, the integrated units became known as
modular incinerators.  While the capacity of the modular incinerators has
increased from 1 to 4 tons of waste per hour, most of the components are
still completely assembled and packaged in the factory for immediate on-site
installation.

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     Controlled  air incinerators are grouped under two main categories
according to  the degree of combustion,  complete or partial, in the primary
chamber.  Since  the complete combustion requires excess air and the partial
combustion needs substoichiometric conditions,  the categories are excess  air
incinerators  and substoichiometric, or  starved  air, incinerators (see Figure 1)
             4000
             3000
          LU
          tr
          Z)
tr
LU

LU
             2000
             1000
                                EXCESS AIR —percent

                            0          100         200
                                                              300
                          STARVED AIR RANGE

                          PRIMARY COMBUSTION CHAMBER
                          SECONDARY COMBUSTON CHAMBER

                          EXCESS AIR RANGE

                          PRIMARY AND SECONDARY
                            COMBUSTION CHAMBERS
                                                                2000
                                                                1500
                                                                1000
LU
tr

I
ir
LU
a.
LU
                                                                500
                            100
                                       200
                                                   300
                                                              400
       Figure 1.
                  STOICHIOMETRIC AIR — percent

        Operational  ranges (stoichiometr.ic  air  percentage and
        temperature)  for controlled air incinerators.
     In  addition to the airflow regulation,  the combustion process  is also
controlled  by varying the waste feed  rate and, in some incinerators,  by
spraying water into the primary chamber.

Feeding  Mechanism

     The waste to be burned is fed  into  the  primary chamber  in  controlled
batches  and at prescribed intervals.   The feed rate is usually  dictated by
the temperature in the secondary chamber.  Except for the removal of  white
goods and large metals, the waste stream usually need not be preprocessed
before it enters the primary chamber.

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Primary Chamber

     During start-up of the substoichiometric, or starved air, incinerator,
one or two auxiliary burners in the primary chamber progressively dry,
volatize, and ignite the waste.  When the combustion rate is sufficient to
sustain partial oxidation reactions, the auxiliary burners are shut off.  The
partial oxidation is maintained by supplying the primary chamber with less
air than that needed for the complete combustion of the gases and chars.  The
combustible gases and particulates generated in the primary chamber flow into
the secondary chamber where combustion is completed.  Any unburned carbon in
the primary chamber is removed with the ash and other inert materials.

     During start-up of the excess air incinerator, an auxiliary burner in
the primary chamber dries, volatizes, and ignites the waste.  With 75 to
150 percent excess air introduced under, over, and beside the waste, the
combustion is sustained sufficiently to turn off the burner and to burn both
the gas by-products and the combustible solids of the initial and subsequent
waste batches.  As the gases flow into and through the secondary chamber, any
remaining combustibles are burned to completion.

Secondary Chamber

     In the substoichiometric, or starved air, incinerator, the secondary
chamber is initially heated by an auxiliary burner.  This burner ignites the
partially oxidized combustibles flowing from the primary chamber into the
secondary chamber.  Then as the burning gases mix with additional air,
complete combustion is achieved and the flue gas temperatures increase to
760° and 888°C (1400° and 1600°F).  As the combustion generating this heat is
self-sustaining, the burner is automatically shut off by a temperature control
device and remains off while the unit is maintained at the designed operating
level.

     In the excess air incinerator, no auxiliary burner is needed in the
secondary chamber since the high temperature of the entering gases and the
addition of more air is sufficient to sustain combustion.  The excess air
introduced into the chamber ranges from 75 to 150 percent of the air needed
for combustion.  Excess air, turbulence, and retention time collectively
provide the conditions for the nearly complete burning of all the combustible
gases and particulates.

Temperature Control

     The temperature in the primary chamber is sensed by thermocouples.
Temperature control is maintained at a set point with a 37.7°C (100°F)
control band by varying the waste feed rate and the amount of air injected
and by spraying the chamber with a water mist.  While the set points vary
with the incinerator manufacturer and the waste to be burned, they generally
range from 649° to 982°C (1200° to 1800°F).

     The temperature in the secondary chamber is also sensed by thermocouples
with set points.  When the chamber temperature reaches the set points, the

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 thermocouples activate controllers which modulate airflow dampers and turn
 the burner on and off.

 Residue Removal

      Ash and other noncombustible residue which settle on the hearth of the
 primary chamber after the combustion process are periodically removed by
 manually or automatically operated systems.  In the manual system the operator
 scoops out the ash (by shovel or front-end loader) after the unit has been
 shut off and cooled down.  In the automatic system the ash is pushed or
 forced ahead of the burning waste until it exits the chamber, generally
 through a drop chute into a water-sealed pit or an air-lock chamber.

 Energy Recovery

      Several incinerator systems incorporate water of fire tube boilers to
 recover the thermal energy from the flue gases exiting the secondary chamber.
 Either an induced draft fan in the gas stream or an aspirator fan outside the
 gas stream draws the flue gas through the boiler.

 Waste Consumption

      The waste consumption capacity of the controlled air incinerators
 varies greatly with the waste characteristics.   The energy content is the
 most important factor in determining the capacity.   The modular units are
 designed to burn a specific amount of energy per hour;  therefore,  the higher
 the energy content per unit mass,  the slower the feed rate.   The incinerator
 capacities in  industrial plants  and those in municipal plants are  convention-
 ally expressed in waste feed rates of kilograms  (pounds)  per  hour  and mega-
 grams  (tons) per day,  respectively.

     The capacities  of the substoichiometric, or starved  air,  incinerators
 range  from 10.9  to 45.4 Mg/day (12 to 50 TPD) while  those of  the excess air
 incinerators range from 10.9 to  272.1 Mg/day (12 to  300 TPD).

 Stack  Emissions

     Since  the controlled  air  combustion in  the  two  chambers  burns most, but
not  all, of the  combustible  gases  and particulates,  the stack emissions without
any  additional air pollution equipment will  contain  some  unburned carbon, as
well as  inert particles and  vapors.

     Industrial incinerators that burn a consistent waste have been  designed
and operated so that their stacks would  not  require additional emission
control equipment.  In contrast, municipal incinerators that burn a highly
heterogeneous and changing waste may  require additional air emission  control
equipment to meet the applicable state standard  since it is difficult to
maintain combustion at steady-state conditions,  and, consequently, to keep
emissions at prescribed levels.

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HISTORY OF CONTROLLED AIR INCINERATION

Introduction

     During the period from 1960 to 1970, incineration was a recognized
economical method of solid waste disposal.  A reported 265 to 299 incineration
plants were in operation across the United States.

     The enactment of the Clean Air Act in 1970 began the closure of the
incineration facilities because of a reluctance on the part of the facility
owners to add air pollution control equipment to meet the more stringent air
emissions standards.  Closure due to the excessive cost of installing air
emission control devices has prompted most cities to seek a more economical
method of solid waste disposal.

     As the incineration facilities closed, many of the incinerator companies
also folded.  As the uncontrolled (excess) air incinerator industry dimin-
ished, the controlled air incinerator business correspondingly increased.
Many of the smaller modular incinerators were first developed by manufac-
turers of the larger uncontrolled air incinerators.

Design Evolution

     The first-generation models of the controlled air modular incinerator
were small refractory-brick-lined primary chambers with a vertical after-
burner chamber and stack combination.  These incinerators had capacities in
the range of 45.4 to 318 kg/hr  (100 to 700 Ib/hr) when burning commercial or
industrial waste.  The controls on these incinerators were minimal, i.e.,
on/off switches for the burner and preset air blowers.  The primary uses for
the incinerators were to burn waste generated from hospitals, stores, and
restaurants.

     Subsequently, the afterburner stack was replaced by a larger secondary
chamber, and the capacity of the units was increased to 1135 kg/hr  (2,500 Ib/hr)
The control of the temperature and airflow in the secondary chamber permitted
modulating the burner or even shutting it off after a temperature high enough
for self-sustaining combustion of the gases was reached.  This control mini-
mized the consumption of auxiliary fuel since continuously operating units do
not require afterburner fuel once they have reached operating temperature and
are maintained at designed operating levels.

     The earlier units were loaded through a door before the unit was ignited.
Because of the positive pressure in the chamber and the presence of pyrolysis
gases, opening the door while the waste was burning resulted in flames leaping
out.  Double doors and temperature lockouts were developed to prevent the
operator from being injured by  these flames.  Later, a slight negative
pressure was induced in some models to prevent flame escape as the  doors were
opened.  On the larger units, the loading system advanced from the  door
loaders to an enclosed hopper and ram module.  The latter equipment allowed
                                      10

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more waste  to be quickly and  safely  loaded  into  the primary  chamber.   Pneumatic
feeds for small-particle waste  and pump  feeds  for  liquid waste were  also
developed.

     Ash in the primary chamber was  originally removed manually  after  the
chamber had cooled sufficiently.  While  automatic, continuously  operating
residue removal systems have  been developed for  the larger incinerators, most
of the smaller incinerators (those with  capacities less than 317.8 kg/hr
[700 lb/hr]) still have the ash removed  manually.

     Although the larger modular incinerators  were integrated with heat
recovery systems, their high  cost initially made their sale  difficult.
However, with oil and gas prices increasing and  curtailments brought on by
the recent  energy crisis, the waste  incinerator with heat recovery became an
economical  alternative to landfills  and  conventional fuels.  Incorporating
the heat recovery system with the incinerator  necessitated the addition of
expanded control systems.

CURRENTLY AVAILABLE MODULAR INCINERATORS

     In a survey to determine the currently available modular incinerators
that would  represent state-of-the-art technologies and designs and various
configurations, the manufacturers' brochures were reviewed,  and  conversations
were held with manufacturer representatives  to supplement the information in
the sales literature.  Most of  the manufacturers have several incinerator and
heat recovery models with capacities ranging from 15.4 to 90.7 Mg (17 to
100 tons) per day.   Table 1 presents pertinent information about the differ-
ent systems, and Table 2 lists  the manufacturers' addresses and  telephone
numbers.

     After  analyzing the survey results, the incinerator systems were grouped
under five  categories:

     (1)  Two horizontal cylindrical chambers with one above the other,
          as manufactured by Environmental  Control Products,  Comtro, Morse
          Boulger,  Econo-therm, Kelley, Consumat, and Smokatrol  (see Figure 2).

     (2)  Two horizontal rectangular chambers with one above the other, as
          manufactured by Washburn & Granger, Basic,  and Simonds (see
          Figure 3).

     (3)  Two vertical cylindrical chambers with one above the other, as
          manufactured by Burn-Zol and Lamb—Cargate (see Figures 4 and 5).

     (4)  A rotary primary chamber or a fixed primary chamber with a rotary
          grate -or auger and a fixed secondary chamber,  as manufactured by
          Scientific Energy Engineering, Giery, and C.  E.  Bartlett (see
          Figures 6,  7,  and 8).

     (5)  Two horizontal rectangular chambers with one after the other, as
          manufactured by Clear Air  (see Figure 9).
                                     11

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                           TABLE 1.  MANUFACTURERS OF MODULAR INCINERATORS
Incinerator type
municipal
no.

Manufacturer
Basic
Burn-Zol
.C.E. Bartlett
Clear Air
Comtro
Consumat
Econo therm
ECP
Giery
Kelley
Lamb-Cargate
Morse-Boulger
SEE
Simonds
Smokatrol
Washburn
with
heat
recovery
0
0
0
0
0
4
0
1
1
0
0
0
0
0
0
1
without
heat
recovery
0
0
0
3
3
13
0
0
0
6
0
4
1
0
0
1
industrial
no. Air emissions
with
heat
recovery
6
1
0
0
3
4
4
14
0
49
2
1
0
7
1
0
Capacity
without control equipment Combustion range
heat normally employed process Mg/day (TPD)
recovery
6
0
19
0
N
N
N
N
0
N
0
0
0
N
N
0


X
X
X

X


X
X
X


X

//
t
#
#
t
t
t
t
t
t
t
#
t
#
t
t

33 (36)
up
UP'
44 (48)
up
up
up
up
22 (24)
up
up
up
up
up
up
up

to
to
to
to
to
to
to
to
to
to
to
to
to
to
to
to

136
22
35
272
22
45
29
43
65
22
181
227
136
27
37
22

(150)
(24)
(38)
(300)
(24)
(50)
(32)
(48)
(72)
(24)
(200)
(250)
(150)
(30)
(30)
(24)
#  Excess air incineration.




t  Starved air incineration.




N  Numerous.

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   TABLE 2.   ADDRESSES AND  TELEPHONE  NUMBERS OF MODULAR
                INCINERATOR MANUFACTURERS
Basic Environmental  Engineering, Inc.
21W161 Hill
Glen Ellyn, Illinois  60137
(312) 469-5340
Burn-Zol
P.O. Box 109
Dover, New Jersey
(201) 361-5900.
07801
C. E. Bartlett-Snow
200 West Monroe
Chicago, Illinois   60606
(312) 236-4044

Clear Air,  Inc.
P.O. Box 111
Ogden, Utah  84402
(801) 399-9828

Comtro Division
180 Mercer Street
Meadville,  Pennsylvania  16335
(814) 724-1456
Consumat
P.O. Box 9574
Richmond, Virginia
(804) 746-4120
 23228
Econo-Therm
1132 K-Tel Drive
Minnetonka, Minnesota
(612) 938-3100
    55343
Environmental Control Products
P.O. Box 15753
Charlotte, North Carolina  28210
(704) 588-1620

Environmental Services Corporation
P.O. Box 765
Crossville, Tennessee  38555
(615) 484-7673
                        Giery Company, Inc.
                        P.O. Box 17335
                        Milwaukee, Wisconsin
                        (414) 351-0740
                      53217
Kelley Company,  Inc.
6720 N. Teutonia Avenue
Milwaukee, Wisconsin   53209
(414) 352-1000

Lamb-Cargate
P.O. Box 440
1135 Queens Avenue
New Westminster, British  Columbia
V3L 4Y7  (604) 521-8821
                        Morse-Boulger
                        53-09 97th Place
                        Corona, New York
                        (212) 699-5000
                  11368
Scientific Energy Engineering,  Inc.
1103 Blackstone Building
Jacksonville, Florida  32202
(904) 632-2102

Simonds Company
P.O. Drawer 32
Winter Haven, Florida  33880
(813) 293-2171

U.S. Smelting Furnace Company
(Smokatrol)
P.O. Box 217
Belleville, Illinois  62222
(618) 233-0129

Washburn and Granger
85 5th Avenue
Patterson, New Jersey
(201) 274-2522
                                     13

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                                        SPARK ARRESTOR
                                         -BLOWER
                 RRE DOOR-
                LOADING HOPPER
                                  SECONDARY CHAMBER   LP-—BURNER
                                    PRIMARY CHAMBER
                                BURNER
                                                       -ACCESS DOOR
                                                       - RESIDUE CHUTE
                               BLOWER
          Figure  2.   Configuration of two horizontal cylindrical
                      chambers with one above the other.
                         - SPARK ARRESTOR
BURNER
ACCESS DOOR -
                      BLOWER
                             SECONDARY CHAMBER
                               PRIMARY CHAMBER
                              ^BURNERS'
                                       BLOWER
                                                     'FIRE DOOR
                                                       LOADER
Figure 3.
                Configuration of  two horizontal rectangular chambers
                with one  above the other.
                                      14

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          BLOWER—-((
          BURNER -—-
          BLOWER-
TE
a
SEC
C
F
C
ERTIARY
1AMBER
1


3ONDARY
HAMBER
I


RIMARY
HAMBER
0
1
	 1 —

pi
r

LOADER
1 " !
                       ACCESS DOOR
Figure 4.   Configuration of  Burn-Zol's two vertical cylindrical
            chambers with one above the other.
                                15

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Figure 5.  Configuration of Lamb-Cargate's two vertical cylindrical
           chambers with one above the other.
                                16

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SHREDDER/AIR CLASSIFIER
                                STEAM GENERATING SYSTEM/S.E.E. INCINERATOR
                                                                     AIR POLLUTION CONTROL
     Figure 6.   Configuration  of Scientific  Energy  Engineering's
                  incinerator with an  auger in the primary  chamber.
                      HOPPER
                       GATES
                    REFUSE CHUTE
                      GATES
                   IGNITION BURNER
                                                       FLUE GAS OUTLET
                                                       TO SCRUBBER
ROTARY BASKET
GRATE
                                               RESIDUE
      Figure 7.  Configuration of  Giery's incinerator  with a  rotary
                  grate in  the primary chamber.
                                        17

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                   ROTARY PRIMARY
                     CHAMBER     I—I '
              \ i—^_M^ ^-T-V •§   I   .'
      LOADING   L
      RAM
 Figure 8.
                                RESIDUE PIT
 Configuration  of C. E.  Bartlett's  incinerator  with a
 rotary primary chamber.
Figure 9.
                                                                ELECTROSTATIC
                                                                PRECIPITATOR
                     PRIMARY CHAMBER
                     WITH MOVING GRATE
                                               WATER TUBE BOILER
Configuration of  Clear Air's  incinerator-heat recovery
system with two horizontal  rectangular  chambers  aligned
one after the other.
                                    18

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                                   SECTION 3

                 OVERVIEW OF FACILITIES AND THEIR EVALUATIONS
EVALUATION OVERVIEW

     The current program was designed to evaluate small modular Incinerators
in terms of operational data that would reflect the state-of-the-art of their
technologies.  Since incinerators burning, municipal solid waste have different
operating conditions than those burning industrial waste, a unit of each type
was separately evaluated.  Although the two evaluations are documented
together, they are not compared since each typifies a discrete set of condi-
tions.  Consequently, the reader is cautioned against drawing any comparative
conclusions.

     The two selected facilities were each tested over three 1-week periods
to gather data for technical, environmental, and economic evaluations.  The
technical evaluation consisted of (1) refuse and residue analyses, (2) effi-
ciency analyses of the incinerator and the heat recovery boiler, (3) an
operational data summary, and (4) a maintenance data summary.  For each
facility, a mass balance was prepared for the weekly field test with the most
continuous and stable operating conditions to verify the accuracy of the data
used in the energy efficiency and balance calculations.  In the mass balance,
the mass inputs to the system were calculated and compared with the measured
mass outputs from the system.  In the energy balance, the measured input
energies were compared with the measured output energies.  While the input
and output values in each of these balances should be equal, values close to
equality, i.e., less than a 5 percent difference"between them, are normally
considered the best achievable.

     The environmental evaluation consisted of analyses of the stack flue
gases, the residue, the process water, and the general plant environment.  In
addition, an EPA Level 1 type of anlysis was designed to identify the organic
and inorganic elements in the system emissions.  The EPA-recommended analysis
methods and sampling techniques were applied to investigate the emissions that
had a high potential for adversely affecting the environment.  The economic
evaluation consisted of capital cost, actual operational cost, and projected
operational cost summaries.

NORTH LITTLE ROCK FACILITY

Description

     The North Little Rock  facility  (referred to as  the North  Shore Energy
Plant) is located in an  industrial area of North Little Rock,  Arkansas  (see

                                      19

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Figure 10).  During the time of this evaluation, the City was collecting, on
the average, 63.4 Mg (70 tons) of solid waste per  day.  The estimated 1978
waste throughput of the North Shore Plant was 13,721 Mg (15,125 tons).  Four
Consumat Modular Model CS-1200 incinerators integrated with heat recovery
equipment burn the waste and produce steam which is delivered under contract
to the nearby Koppers Corporation, a manufacturer of creosote-treated wood
products.  The contract calls for an average 6804 kg (15,000 Ib) per hour of
steam at 150 psi to be delivered 24 hours per day, 5 days per week.
                             NORTH LITTLE
                                  ROCK
          Figure 10.  Vicinity map of North Little Rock facility.
     The plant lies on a relatively flat, 8092-m2 (2-acre) site adjacent to
the Koppers plant.  There are two structures on the site:  a main building
with a wing on each side, one facing east and the other west, and an adminis-
tration building southwest of the main building and nearer to the plant
access (see Figure 11).

     The central part of the main building is the tipping floor,  and each of
the two wings contains an identical waste-to-heat energy module.   Each
module consists of (1) a dual loading ram; (2)  a display panel for refuse
loading instructions; (3) two control systems;  (4)  two identical  incinerator
systems each including a primary chamber with an automatic residue removal
                                      20

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           Figure 11.  Plant layout of North Little Rock facility.
system and a secondary chamber;  (5) a  tee section with a  dump stack  common  to
the two incinerator systems; and  (6) a heat recovery system  that  is  .common  to
both systems including a water tube boiler, a soot blower, a water treatment
system, an aspirator section, and an exhaust stack (see Figure 12).  Figure 13
shows  the cross section of the system.  The flow diagram  of  the process is
shown  in Figure 14.

Operation

Refuse Loading—
     The operator of the skid-steer tractor on the tipping floor has the
twofold task of pushing the truck-deposited refuse into each of the  four
floor corners for temporary storage and of pushing the piled waste along the
loading platform to the hopper in both the east and the west waste-to-energy
modules.

     The load-size indicators on the loading display panel are automatically
lighted according to the correlation of the primary chamber temperature with
preset lower and upper limits.   The three load sizes,  namely, LOAD HEAVY,
LOAD MEDIUM,  and LOAD LIGHT,  refer only to the quantity,  that is,  cubic

                                      21

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NJ
N>
              Figure 12.  Three-dimensional drawing of incineration-heat recovery module
                          in North Little Rock facility.

-------
TO
HEAT
RECOVEI
BOILER
3

\ 1 SECONDARY CHAMBER
	 = 	 i^!_zi^ 	 : 	 ij_i_ri 	 21; 	 ; — "- - _^J 	 i; 	 • ' -'.'..^
Figure 13.  Cross section of incinerator module in North Little Rock facility.
yards  of  the  refuse.   Therefore,  there  is  no  need  to  vary the  quality  of
the  refuse  gathered  for  any  one of  the  three  load  sizes  indicated.   When  the
chamber temperature  is above the  high set  point, the  LOAD HEAVY  frame, which
represents  the  largest load,  illuminates so that the  next load will  lower
the  temperature below  the maximum level.   When  the chamber temperature is
at the desired  operating level, the LOAD MEDIUM frame, which represents the
intermediate  load, illuminates so that  the next load  will maintain the
current temperature.   When the chamber  temperature is below the  low  set point,
the  LOAD  LIGHT  frame,  which  represents  the smallest load,  illuminates so
that the  next load will  raise the temperature above the  minimum  level.

Steam  Production—
     The  gases  are slowly drawn through the heat exchanger by  a  negative
pressure  generated at  the inlet side by the aspirator fan.

     During steam production  the  cap at the base of the  dump stack is
pneumatically closed.  Since  the  cap is normally held open by  a  counterweight
as a fail-safe  design, the flue gases are  automatically  discharged through
the  dump  stack  whenever  the power fails, the  flue  gas control  system malfunc-
tions, the water in the  steam drum  or deaerator tank  drops  too low, or the
steam  generation rate  exceeds the steam demand  rate.
                                      23

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Aspirator
~:
i
i
Soot Blower
                                    Flue Gas To
                                    Atmosphere

                                      1
                                    Condensate
                                    • Return
                       Air
       From Water
       Softener
   To
 Deaerator"*
       1    f
 Solids To   Water To
 Landfill    Drainage
            Ditch
Air
   J     V
Water To   Solids To
Drainage   Landfill
 Ditch
                                    Solid Waste.
     Figure 14.   Flow diagram of  incineration-heat recovery processes  in
                  North Little Rock  facility.
Residue  Transfer and Removal—
     The two rams on the hearth of  the primary chamber are cycled  to push
the residue forward and to break up clinker formations.

     The residue removal ram is automatically cycled after several loading
cycles.   As the residue falls into  the wet sump, it is sprayed with water.
After a  delay period the drag chain lifts the residue from the sump and
deposits it into the residue removal container.

Introduction to Test Program

     The purpose of the testing was to provide detailed data on  the facility
performance.   Since both wings of the plant are identical and operate under
the same conditions, only one set of incinerators and the common steam
module were tested.  The system in  the west wing was chosen.

     The facility was tested for 1-week periods  during the months  of March,
May, and October 1978.   Of the three tests, the October test had the most
                                       24

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 continuous and stable operating conditions.  The data for this test, there-
 fore, were used in the technical evaluation of the facility.

      The October test began at normal start-up Sunday night and lasted for
 118.5 hours to late Friday night when burndown began.  During that period,
 204,300 kg (450,000 lb)  of refuse were burned at an average weekly rate of
 1725 kg/hr (3800 Ib/hr)  and at a daily rate ranging from 1634 to 1770 kg/hr
 (3600 to 3900 Ib/hr)  in the two incinerators being monitored.

 Technical Evaluation

      As indicated by Table 3,  which summarizes the refuse weights and sorts
 in 11 categories,  the incinerator handled a wide variety of refuse sizes and
 components.   However,  the operator manually removed large,  bulky,  explosive,
 metallic,  and wire objects before the refuse was dumped  into the  loading
 hopper.

      During  the  three  field tests,  the refuse had a moisture content  varying
 from 22  to 35 percent  and an average bulk density of 97.7 kg/m3  (165  lb/yd3).
 The  residue  had  an average bulk density of 896  kg/m3 (1510  lb/yd3)  with
 69 percent of the  residue particles being smaller than 1 inch.  The refuse
 reduction  through  combustion was  55 percent by  weight and 95 percent  by
 volume based  on  the ratio of wet  residue to as-received  refuse.  On a dry
 residue  basis, the refuse weight  reduction was  70 percent.

      The weekly  system mass  balance for  the October  field test compares the
 mass  flows entering and leaving the incinerator-heat recovery system.   While
 the  system inputs  measured were the refuse,  the  combustion air, the auxiliary
 gas,  the residue cooling  water, and the  aspirator fan air, the system outputs
 measured were  the  residue and  the boiler exhaust  stack flue  gas.  Figure 15
 presents the mass  balance on a per  ton input basis.  Over the 118.5-hour test,
 the total mass input was  4127  Mg  (4550 tons) and  the mass output was  4199  Mg
 (4629 tons).   The  difference,  namely  71.7 Mg  (79  tons) or 2  percent of  the
 output, was not accounted for.

     The energy balance in Figure 16  compares the measured energy inputs and
 outputs  on a per ton input basis.   For this balance, the  inputs were  refuse,
 electricity, and auxiliary fuel while the outputs were steam, sensible heat
 and remaining energy in the residue, heat lost by radiation  and convection,
 and sensible heat  in the  flue  gases.  The energy  inputs and  outputs on  the
 118.5-hour test totaled 2298 and 2350 GJ  (2178 and 2228 MBTU), respectively.
 The lesser energy output  of  52 GJ (50 MBtu) or 2 percent  of  the energy input,
was well within the expected ±5 percent  closure.

     Each of the two Gonsumat heat  recovery modules was designed to produce
 4,540 kg (10,000 lb) of steam  per hour.  The total plant  steam demand, as
measured by a Honeywell steam  flow  integrator, averaged 4,994 kg (11,000 lb)
 per hour with a maximum and minimum of 6,356 and 2,724 kg (14,000 and
 6,000 lb) per hour.  On the average, the plant steam demand was 79 percent of
 the original anticipated  demand of  6,81,0 kg  (15,000 lb)  per hour.   The west-
 end waste-to-energy module (the module tested) had steam ouputs that averaged
 3,746 kg (8,250 lb) per hour and reached levels between 4,994 and 5,357 kg
 (11,000 and 11,800 lb) per hour during peak demand periods that lasted from

                                     25

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    Table 3.  NORTH LITTLE ROCK WEEKLY REFUSE  COMPOSITION FOR MARCH,  MAY,
              AND OCTOBER TESTS
Test Period
Category
Food waste
Garden
Paper
Plastic
Textiles
Wood
Ferrous
Aluminum
Glass
Inert
Fines
Tocall

Weekly %
by weight
8.8
7.2
48.1
6.1
3.4
1.4
8.3
1.1
10.9
1.6
3.2
100.1
March
Category weight
kg(lb)
13, 104 ( 28,890)
10,722( 23,638)
71,692(157,914)
9,084( 20,027)
5,063( 11,162)
2,085( 4,596)
12,360( 27,249)
1,638( 3,611)
16,232( 35,785)
2,383( 5,253)
4,765( 10,506)
149,198(328,631)

Weekly %
by weight
6.7
4.2
49.6
7.4
1.5
1.1
9.8
1.8
11.8
0.4
5.7
100.0
May
Category weight
kg(lb) 	
10,332( 22,779)
6,477( 14,279)
76,489(168,630)
11,412( 25,159)
2,313( 5,100)
1,696( 3,740)
15, 113 ( 33,318)
2,776( 6,120)
18,197( 40,118)
617( 1,360)
8,791( 19,380)
154,350(339,980)

Weekly „%
by weight
6.8
3.0
54.1
8.7
2.2
1.0
8.8
3.2
7.6
0.3
4.1
99.8
October
Category weight
kg(lb)
13,880( 30,600)
6,123( 13,500)
110,019(242,550)
17,758( 39,150)
4,491( 9,900)
2,041( 4,500)
17,962( 39,600)
6,532( 14,400)
15,513( 34,200)
612( 1,350)
8,369( 18,450)
203,483(448,200)
 I Totals do not equal weighed refuse total due to rounding and averaging.


30 to 60 minutes.  The pressure in the  steam  drum varied  from 120  psi at  peak
demands, to 130 psi at the average steam demand,  and  to a high of  140 psi at
the low steam demand.  The efficiency of the  refuse combustion was 94 percent,
or 6 percent of the combustibles were unburned and removed with the residue.

     The system energy efficiencies,  as calculated by the input-output,  and the
heat loss methods were 56 and 54 percent,  respectively.   Because of the  high
moisture and hydrogen content of the  refuse,  the  net  efficiency of the system
was calculated with a net heating  value to eliminate  the  heat lost by evapo-
rating the moisture.  The resultant 65  percent efficiency was 9 to 11 percent
higher than the efficiency computed with the  total or as-received heating
value.

     The operation of the facility required a total of nine personnel, i.e.,
one supervisor, one office manager, one truck driver, and two operators  per
shift for each of the three  shifts.   The supervisor position was critical to
the successful operation of  the plant.  The office manager maintained all
plant records such as those  for utilities, refuse delivery, and steam con-
sumption.  The truck driver  transported the residue to the disposal site.
                                       26

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                              Mass balance 118.5-hour test*
                          Input
                                                       Output
                  Mg per Mg refuse
          Source         or
                  Ton per ton refuse
                                    of Total
           Mg per Mg refuse    '/•> of Total
                or
           Ton per ton refuse
        Refuse          1.0
        Natural gas      0.002
        Residue,
          cooling water   0.157
        Aspirator air   10.26
        Blower air       8.88
        Residue, wet
        Flue gases      	
        Total
                      20.299
 4.92
 0.01

 0.77
50.54
43.76
                                  100.00
                 0.45
                20.13
                                                   20.58
 2.19
97.81
                                                                100.00
        * Total refuse input 204 Mg (225 tons).
                                                  |         BOILER  STACK
                                             DUMP STACK      FLUE.  GAS
                                             FLUE GAS
                               GAS-
                BLOWER-
                REFUSE-
  *[    A.B,
  _j  czr
                                                      BOILER
                                                                    -ASPIRATOR
                                PRIMARY
                                  WATER-
                                              PIT
                                                           .—RESIDUE-
Figure 15.   Mass  balance for  incineration-heat  recovery processes  in
               North Little Rock facility during the  118.5-hour  October
               field test.
                                          27

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                                      Energy balance 118.5-hour cast*
                            Input
                                                                 Output
  Source
  GJ per
Mg of refuse
   MBtu per  j
Ton of refuseJ
                                          of total
                                                       GJ per
                                                     Mg of refuse
                        MBtu per
                      Ton of refuse
                                                                             % of total
  Refuse
  Electricity
  Natural gas
  Unburned
   combustibles
  Stean
  Flue gases
  Radiation and
   Convection

  Total
   11.12
     .09
     .052
   (9.56 )
   ( .08 )
   ( .044)
98.71
 0.83
 0.46
   11.262
               (9.684)
                          100.00
                                         .661
                                        5.99
                                        4.30

                                        0.56

                                       11.51
                                        ( .569)
                                        (5.15 )
                                        (3.70 )

                                        (0.48 )

                                        (9.909)
                                     5.74
                                    52.05
                                    37.36

                                   	4_.85

                                   100.00
  *Total refuse input 204 Mg (225 ton)
                                                       BOILER STACK
                                                        FLUE  GAS
                                          DUMP STACK
                                           FLUE GAS
                                     t
                                R/C LOSSES
                                                   BOILER
                            GAS-
                        A.B.
                                                                 - STEAM'-
        ELECTRICITY-
           REFUSE -
                             PRIMARY
                                              UNBURNED
                                             COMBUSTIBLES
    Figure 16.   Energy  balance  for incineration-heat recovery processes  in
                  North Little Rock facility during the 118.5-hour  October
                  field test.
The  two operators shared routine maintenance  and incinerator  loading  opera-
tions.   The  steady-state, efficient operation of the  system requires  that the
operators closely follow the  start-up  procedures, the automatic loading
instructions,  and the burndown procedures.  The effects on the  system temper-
atures  and gaseous emissions  when the  hopper  loads varied from  light  to
heavy are shown in Figures 17 and 18.
                                          28

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                          LEGEND
                             Temperature in
                         @L  Temperature in
                         ©.  Temperature in
                         ©I  Temperature in
                         ©•  Temoerature at
                          EVENTS
                          1.  Load,  light No.
                          2.  Load,  light No.
                          3.  Load,  medium No
                          4.  Residue, dump No
                          5.  Load,  light No.
Primary Chamber No. 3.
Secondary Chamber No. 3.
Primary Chamber No. 4.
Secondary Chamber No. 4.
Boiler Entrance.

 4        6.  Load, medium No.
 3        7.  Load, light No.
  4        8.  Load, medium No.
  4        9.  Load, medium No.
 3       10.  Load, medium No.
Figure  17.   System temperature versus  loading  sizes  and  events  in North
               Little Rock  facility.
                                          29

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               1.  CO     X10 = ppm
              ,2.  NOX    X 5 = ppm
              "3.  Opacity    « percent
               4.  CO j      ORSAT      /•
               5.  0=,
    Figure 18.   Stack  emission during heavy and light loading periods in
                 North  Little  Rock facility.
     The routine maintenance  of  the facility required a working knowledge
of the hydraulic, electronic,  and mechanical systems.   A supply of small
spare parts, such as switches, thermocouples,  hydraulic parts,  and motors,
was essential for continuous  24-hour operation.   While major maintenance
during the week required shutting down the  incinerator, much maintenance
could be performed during an  hour or two with the incinerator still operating
but at reduced capacity.  Normally,  the major maintenance (if required) and
removal of soot deposits in the  boiler were performed during the weekend.
                                      30

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Environmental Evaluation

     For the October  test,  Table 4 presents the flue gas emissions in terms
of grains per standard  cubic  foot (gr/SCF)  and grams per standard cubic meter
 (g/SCM) and pounds per  ton  of refuse processed.  Table 5 summarizes the
emissions for each of the three  test periods.   The size distribution analysis
of the particulates during  the October test revealed that 95 percent by
weight of the particulates  were  smaller than 7 pm and 50 percent by weight
were 0.3 um or less.  In five October tests for total particulates, including
the wet-catch particulates, the  total particulates, corrected to 12 percent
C02 averaged 0.397 g/SCM (0.174  gr/DSCF)  with a maximum of 0.500 g/SCM
(0.219 gr/DSCF) and with a  minimum of .271  g/SCM (0.119 gr/DSCF).  While the
concentrations of chloride  ranged from 19 to 610 mg/m3 (13 to 420 ppm) and
averaged 187 mg/m3 (130 ppm),  those of fluoride ranged from 0.5 to 4.3 mg/m3
(0.6 to 5.5 ppm) and  averaged 1.6 mg/m3 (2.0 ppm) over the three test periods.
          TABLE 4.  NORTH LITTLE ROCK POLLUTANT EMISSION RATES
                    FOR  OCTOBER TEST
Pollutant
Particulate
sox
NOX
CO
HC
Pb
Emission rate

Ib/ton refuse
Maximum Average Minimum chargedt
.231* gr/SCF .130* gr/SCF .067* gr/SCF
<10 ppm
99 ppm 82 ppm 69 ppm
36 ppm 29 ppm 16 ppm
40 ppm 28 ppm 20 ppm
4.49 mg/m3
3.03
<0.78
3.68
1.00
0.55
0.14
     *  Corrected to 12 percent C02.
     t  Based on an average flow of 15,198 DSCFM including aspirator air and a
        feed rate of 1.9 TPH.
                                       31

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               TABLE  5.   NORTH LITTLE ROCK SUMMARY OF STACK EMISSION FOR
                            MARCH, MAY,  AND  OCTOBER  TESTS
Field test
Emissions (units)
Particulate (gr/SCF)*
Particulate (g/a3)*
Chlorides (mg/m3)
Fluorides (mg/m3)
Stack 02 (percent)
Stack CO 2 (per cent )t
Stack C02 (percent)tt
Stack CO (mg/m3)
Stack NOX (mg/m3)
Stack SOX (mg/m3)
Stack H20 (percent by volume)
Boiler 02 (percent)
Boiler C02 (percent)tt
Boiler CO (mg/m3)
Boiler NOX (mg/m3)
Boiler SOX (mg/m3)
Particulate size (ym)#
Hydrocarbons (mg/m3)i}>
Test
Max
.1847
.4227
609.9
4.3
18.3
3.5


112.8
13.3
6.7
—


334.3
133.3
34.0
0.19
1: March 3-20,
, 1978
Avg Min Std Dev
.1430 .0998
.3458 .2284
344.7 217.0
2.3 1.6
17.2 16.5
3.1 2.8
No Data
No Data
102.3 95.6
13.3 13.3
6.0 4.5
11.6
No Data
No Data
272.2 181.5
56.5 13.3
3.0 <0.3
0.16 0.15
.0282
.0682
126.8
1.0
.8
.3
Test
Max
.2779
.6359
34.9
1.7
19.0
4.5
2: May 5-22,
Avg
.1906
.4609
26.0
1.3
17.1
2.6
Min
.0747
.1709
19.4
.6
15.1
1.9
1978
Std Dev
.0545
.1318
6.0
.5
.9
.7
No Data

7.2
0
—
—
61.4
175.0
33.3
9.7
14.5
35.2
94.8
10.3
7.9
11.5
16.6
<10.0
<13.0
6.8
9.2
9.4
39.8
9.4
—
1.'7
No Data

56.3
49.2
	
—
61.7
510.0
88.0
28.0
0.19
44.6
284.4
22.5
0.3
0.12
25.8
76.6
<13.0
<0.3
0.06
10.4
114.4
19.4
__
—
Test 3;
Max
.2312
.5291
193.3
1.2
18.0
4.7
6.8
46.4
213.9
<13.0
7.5
12.6
11.6
91.6
450.8
26.6
28.0
25.3
: October 9-13
Avg
.1297
.3136
154.8
.9
16.9
4.1
4.4
21.6
129.7
<13.0
6.1
10.7
9.5
37.4
386.9
3.3
0.3
1.78
Min
.0669
.1531
127.4
.5
13.8
3.5
2.6
<11.0
57.3
<13.0
4.2
8.8
7.5
<11.0
192.9
<13.0
<0.3
1.26
, 1978
Std Dev
.0549
.1327
24.2
.5
.8
.4
.9
15.8
38.1
0

.5
.6
22.9
58.4
6.2

—
Opacity  (percent)

Flue gas temperature  (°F)
Flue gas flow (SCFM)
Flue gas flow (CFM)
         No Data

   259    249    234
19,313  15,671 13,975
26,166  21,085 18,436
          No Data

   260    242    217
18,883  15,822 12,260    —
26,084  22,893 17,518
                                                                42
                                                                       24
                                                                              12
   289     285    274
18,658  16,185 15,192
26,207  22,823 21,484
tt
    Corrected to 12  percent C02
    Data from Orsat  analyser
    Average is mass  mean diameter
    Average of CHi,-C<,Hio
    Continuous NDIR  monitor

-------
     The mechanical functions and the operational procedures were investigated
to determine their effect on the particulate emission level.  Within the scope
of the available data, the emission level increased whenever the temperature
in the primary chamber, the size of the charging load, or the amount of under-
fired air increased.  The individual effects of these parameters could not be
determined because of their interrelationships in the system.  The particulate
emission level could not be correlated with the following:  excess air amounts,
secondary chamber temperature, residue ram action, aspirator fan flow rate,
and the waste characteristics.

     The plant was designed to meet a state-imposed particulate standard
of 0.2 gr/DSCF corrected to 12 percent C02.  The present federal standard
for municipal incinerators with capacities greater than 50 TPD is 0.08 gr/DSCF
corrected to 12 percent C02.  However, this standard does not apply to
the North Little Rock facility because each pair of incinerator units is
rated at less than 50 TPD.  Since the facility complied with the emissions
limitation prescribed in its permit, the reader is cautioned against
assuming that the North Little Rock facility did not comply with the
federal standard.

     A similar unit in Salem, Virginia, was designed to meet a state-
imposed standard of 0.08 gr/DSCF corrected to 12 percent C02.  As of the
date of this publication (September 1979), this small modular system
(with automatic feed and ash removal) has not demonstrated its capability
of meeting the state air emission standards.

     The daily discharge of process water varied from 37.85 to 113.5 m3
(10,000 to 30,000 gallons).   Of the significant discharge water character-
istics, the tipping floor water had a BOD of 1780 mg/&, a COD of 2710 mg/&,
and an arsenic level of 9 mg/Jl; and the residue removal sump water had a
pH of 12 and a temperature of 39° C.  The tipping .floor water is treated by a
municipal treatment plant.  Concentrations of the pollutants are not high
enough to affect the treatment plant's operation.

     The residue contained unburned hydrocarbons and traces of a wide range
of heavy metals.  The tests on the laboratory-produced leachate, as sum-
marized in Table 6, revealed insignificant amounts of pollutants.  This
finding was due primarily to high pH levels that restricted the solubility of
the heavy metals in the leachate.  Although the laboratory-tested residue and
leachate had insignificant amounts of pollutants, the residue could be a
source of pollution if its pH level dropped enough to allow the solubility
of the residue heavy metals during the surface drainage at the local site
and/or the leachate formation at the disposal site.

     Within the facility building, the levels and the viable microorganism
content of the fugitive dust were low, and the noise levels never exceeded
the OSHA limits (see Figure 19).

     Outside the building no significant amounts of pollutants were found at
the upwind or downwind ambient air sample sites; both sites were at a
91.4-meter (300-foot) distance from the-boiler exhaust stack.  The noise
levels were within standard limits (see Figure 20).
                                     33

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    TABLE 6.  NORTH LITTLE ROCK RESIDUE LEACHATE PARAMETER
              AND COMPONENT  VALUES

PH
Conductivity
Alkalinity
TKN
Hardness
TOC
Ortho-Phosphate
Total Phosphate
Sulfide
Chloride
Acidity
Total Dissolved
Solids
Ammonia as N
COD
Sulfate
Bromide
Fluoride
Boron
Mercury
Cadmium
Antimony
Lead
Chromium
Arsenic
Cyanide
Phenols
MBAS
Sulfur


umhos
mg/1
mg/1
rag/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1

mg/1
mg/1

mg/1
mg/1
mg/1
mg/1
Pg/1
Pg/1
Mg/1
Pg/1
PS/1
Pg/1
mg/1
mg/1
mg/1
mg/1
Water Blank
5.52
2.78
1.10
6.95
2.00
3.10
0.005
0.01
O.002
ND
5

<1
0.216
ND
<1.00
<0.100
0.058
<0.1
<0.1
<1
<1.0
<1
<1
ND
-
-
-

Test 1
8.65
185.00
43.50
5.25
70.00
5.70
0.025
0.044
0.002
0.71
ND

80
0.183
ND
34.30
<0.100
0.099
<0.1
<0.1
<1
5.4
<1
<1
ND
-
-
—

Phosphate Buffer
Test 2
6.05
2800
144
11.6
ND
2.2
1400
1975
ND
12
1841

5770
0.23
ND
16.6
1.0
.07
.127
-
-
-
-
-
-
< .002
.005
0.12

ND " None detected
                                 34

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                                                      AIR COMPRESSOR
             CONTROL
             PANEL
                                                               Band "A" dB Imp
                                      Near Compressor on(off)
                                      Soot Blower on(off)
                                      Boiler
                                      Hydraulic Loader on(off)
                                      Storage Area
                                      Near Electrical Panel
                                      Loading Area
                                        W/Skid-Steer Lpader
                                      Near Residue Conveyor
88(84)  105
88(87)  100
82
88(81)
84
83
82
88
79
                                                               RESIDUE
                                                              CONTAINER
94
        93
Figure 19.   In-plant  noise-level plot for  North Little Rock facility.
                                        35

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Figure 20.  Outside-plant noise-level plot for North Little Rock facility.
                                    36

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     The major elements detected in the EPA Level 1 analysis are  shown in
Table  7.   Other metals and elements were  found occasionally in smaller
amounts.
           TABLE 7.  NORTH LITTLE ROCK'SUMMARY OF ELEMENTS
                      DETECTED IN STACK EMISSION  FILTERS
            Element
                                       Emission rate
Concentration in gas
      (yg/m3)*
Emission factor
g/Mg of refuser
Silicon
Iron
Aluminum
Sodium
Calcium
Potassium
Magnesium
Lead
Zinc
Cadmium
Beryllium
Titanium
Chromium
Copper
Nickel
Manganese
Lithium
Antimony
Boron
Tin
Vanadium
3.22
261.
331.
9,363.
894.
381.
331.
4,280.
9,071.
123.
0.114
.333
1.105
62.57
1.97
8.02
2.48
13.26
105.0
3.81
2.26
.0505
4.10
5.20
147.0
14.0
5.98
5.20
67.2
142.
1.93
.0018
.0052
.0173
.982
.031
.126
.039
.208
1.640
.0598
.0354
         *  Concentrations based on a composite of six filters from
            October test period.
         t  g/Mg * 500 = Ib/ton
                                     37

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Economic Evaluation

     The total cost of the plant in  1977  was $1,529,404.  Table  8  presents
the total  capital cost breakdown by  EPA cost categories, and Table 9  presents
the unit operational cost.  These costs are based on averages of the  actual
unit costs over the evaluation period.  Table 10 presents the projected
annual operating and maintenance costs  based on the as-operating parameters;
i.e., feed rate and steam capacity equal  to 2.72 Mg (3 tons) and 7274 kg
(16,000 Ib)  per hour, respectively.

     Table 11 presents the estimated annual revenues.  The as-operated
economic and production conditions yield  a total revenue and a revenue
per Mg of  refuse processed that are  respectively $177,335 and $10.94.
               TABLE 8.  NORTH  LITTLE ROCK ACTUAL CAPITAL COSTS*
                Land

                Site preparation

                Design

                Construction

                Real equipment

                Other equipment

                Other costs
$  10,000

  101,093

   37,583

  311,383

  968,929

   62,886

   37,530
                Total capital investment
                                                          $1,529,404
                *Based on actual costs in 1977.
                                        38

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    TABLE 9.   NORTH  LITTLE ROCK UNIT COST DATA"
Annual salary rates:
   Director of sanitation
   Plant superintendent
   Maintenance superintendent
   Operator
   Truck driver
   Secretary
   Overtime

Employee benefits:
   Health insurance (each employee)
   Retirement
   PICA

Fuel rates:
   Natural gas
   Number 2 diesel  oil
   Gasoline

Electricity:

Water and sewer:
       $19,000
        13,290
        10,800
         9,442
         8,086
         7,956
         5,000
  $29.70/month
         5.00%
         6.05%
 $0.056/1000 I
      $0.122/£
      $0.140/£

    $0.034/kwh

$0.0918/1000 L
*Based on cost  projections from costs incurred during
September 1978.
                              39

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TABLE  10.  NORTH LITTLE ROCK PROJECTED  ANNUAL
            OPERATING AND MAINTENANCE COSTS*
Item
Salaries
Employee benefits
fuel - no. 2 diesel
Natural gas
Gasoline
Electricity
Water and sewer
Maintenance
Replacement equipment
Residue removal
Chemicals
Interest
Depreciation
Other overhead
Total operating and
maintenance costs
Cost
($/yr)
$111,284
15,750
3,456
16,704
2,916
19,237
6,402
65,656
—
t
3,400
39,179
78,070
3,209
$365,263

($/Mg)
$ 6.87
0.97
0.21
1.03
0.18
1.19
0.40
4.05
—
t
0.21
2.42
4.82
0.20
$22.55
 *  Based on costs  incurred during September 1978.

 f  Cost included in salaries and employee benefit categories.
                          40

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                     TABLE  11.   NORTH LITTLE ROCK PROJECTED
                                 ANNUAL REVENUES*
                       Sources
                                                       Revenue
                 Steam production

                 Commercial dumping fees


                 Total


                 Per Mg of refuse processed (per ton)
      $152,999

        24,336


      $177,335


    $10.94 (9.92)
                 *  Based on 1978 dollars.
     With $365,263 as  the projected  annual operating  and maintenance  cost
and $177,335 as the estimated annual revenue, the net annual operating cost
will  be $187,928.  Table 12 presents the costs,  revenues, and  net costs per
unit  of refuse processed.

      In summary, with the facility requiring an  initial capital investment of
$1,529,404 in 1977,  its anticipated annual operation  in 1978 dollars will cost
$187,928 or $11.67 per Mg ($10.53  per ton) of refuse  processed.
                 TABLE 12.   NORTH LITTLE ROCK PROJECTED ANNUAL
                             NET OPERATING COSTS*
                                                      Cost
                                                 ($/Mg)
          ($/ton)
                 Operating and maintenance costs

                 Revenue

                 Net cost of operation
                     (tipping fee)
22.55      20.45

10.94       9.92

11.67      10.53
                 *  Based on costs incurred during September 1978.
                                        41

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MARYSVILLE FACILITY

Description

     This facility is located at the Truck Axle Division of the Rockwell
International Corporation in Marysville, Ohio  (see Figure 21).  The system
was intended for the twofold purpose of burning the division s solid waste,
mostly packing and shipping scraps, and of providing energy for both heating
and cooling the main building by recovering the combustion gas heat in the
form of hot water.
                                                              71
    Figure  21.   Vicinity map  of Marysville  (Rockwell  International) vacility.
                                       42

-------
       The waste-to-heat system includes a Kelley Model 1280 incinerator with a
  Kelley Model 72 feeder and a York-Shipley  Series  565  firetube boiler
  Figures 22 and 23 show a functional schematic  of  the  entire system and a
  three-dimensional, cutaway drawing of the  incinerator module, respectively
  Both the primary and secondary chambers of the incinerator are outside the
  facility housing so that the main building is  remote  from excessive heat
  radiating from the incinerator (see Figure 24).

       While the refuse is burned 16 hours a day 5  days per week throughout the
  year,  the hot water is generated only as needed to maintain the prescribed
  temperatures.
                            EXHAUST STACK
                                                                  HOT WATER TO
                                                                  HEATING SYSTEM
   ASH
REMOVAL DOOR
    \
   Figure 22.   Functional schematic of incineration-heat  recovery  processes
               in Marysville facility.
                                      43

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                                                    Main eh«mb«r burn«r
                                                   Y  —      '^""*


                                                  Air manifold
Figure  23.   Three-dimensional, cutaway drawing of  incinerator module

             in Marysville facility.
                                     44

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    WAREHOUSE
                                         ASSEMBLY PLANT
      GUARD HOUSE
         .. I
VISITOR PARKING
                           OFFICE
 B
CT
 S
 A
 L
 C
PC
TR
BOILER
COOLING TOWER
STACK
ASH CONTAINER
LOADER
CHILLING UNIT
PRIMARY CHAMBER
THERMAL REACTOR
                                                                  MARYSVILLE
        Figure 24.   Plant  layout of Marysville facility.
                                     45

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     The  incinerator system  includes a loading hopper  and ram module, a
pyrolytic primary chamber with  an automatic residue  removal system, a
secondary chamber, a hot water  boiler system, and  an exhaust gas stack.
process flow diagram is shown in Figure 25.
                                        The
                                     Flue Gas
                                   To Atmosphere
                         Henting/Cooling
                            System
                                      Stack
              Air
Thermal
Reactor
                                     Primary
                                     Chamber
                                     Loading
                                     Hopper
                                       T
                           Municipal
                            Water
                                   Solid Waste
    Figure 25.  Flow diagram of incineration-heat recovery processes in
                Marysville facility.
                                       46

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 Operation

 Refuse Loading—
      A fork lift vehicle transports the packing and shipping scraps and other
 solid waste in small containers to the refuse hopper.  When the hopper door is
 opened,  the vehicle operator lifts the containers and  dumps the refuse into
 the hopper.   Then the operator depresses the START button on the control
 panel to activate an automatic loading sequence.

 Chamber Operations—
      Manufacturer performance specifications indicate  that the primary,  or
 pyrolysis,  chamber operates, at 30  percent of the  air required for stoichio-
 metric combustion.   The  secondary  chamber,  or thermal  reactor,  operates  at a
 maximum of  150  percent of  stoichiometric air.

 Introduction to Test Program

      The facility was tested for 1-week periods during the months of  April,
 July,  and August 1978.   The  system was  tested during the  heat  recovery period
 of  the daily operation.  Since the unit was  used  for heating  and  cooling'of
 the plant,  there was frequent  cycling  from energy to non-energy recovery
 during mild  weather  periods.   Of these  three  tests,  the July  test had the
 most  continuous  and  stable operating conditions.   The  data for this test,
 therefore, were  used in  the  technical evaluation  of  the facility.  The July
 test  lasted  for  120  hours.   Energy was  recovered  during 75.5 hours of  the
 80  hours  of  operation, and the  five daily burndown cycles  totaled 40  hours.
 During the July  test  the incinerator operated at  63  percent of capacity.  A
 total  of  25,652  kg  (56,552 Ib)  of wood  and paper waste was burned at  an
 hourly average of 340 kg (750  Ib).

 Technical Evaluation

     During  the  three field  tests,  the  refuse had a moisture content  that
 ranged from  7 to  11 percent with an average of 9.3 percent.  Of the 51,722 kg
 (114,027  Ib) of  refuse burned,  as  shown  in Table 13, 65.7 percent was wood;
 33.8 percent was  paper; and  the remaining 0.5 percent was plastics, paint,
 inerts,  textiles, and rubber.   On the average, the measured energy values of
 the wood and paper were 18.04 and 17.89 MJ/kg  (7758 and 7693 Btu/lb), respec-
 tively.  The residue had an  average bulk density of 428 kg/m3  (726 lb/yd3)
with 97 percent being inerts and the remaining 3 percent being combustibles.
The refuse reduction through combustion was 95 percent by weight.

     The weekly system mass balance for the July field test compares the mass
 flow entering and leaving'the incinerator-heat recovery system.  The system
 inputs were the refuse, the  combustion fan air, the auxiliary gas, the quench
water, and the afterburner air.  The system outputs were the residue, hot
water, and the boiler exhaust flue gas.  The mass balance shown in Figure 26
 covers two time periods:   one for 75.35 hours while the system was in full
heat recovery operation and  the other for 44.62 hours while the system was in
burndown cycles.  Excluding the combustion air, the measured inputs totaled
42.6 Mg  (47 tons).  The air  input could not .be measured and had to be com-
puted by the difference method.
                                     47

-------
        TABLE 13.  MARYSVILLE WEEKLY REFUSE COMPOSITION FOR APRIL,  JULY,
                  AND AUGUST TESTS

Category April
kg (Ib)
Total 13,151 (28,994)
Wood 7,324 (16,147
Paper 5,768 (12,717)
Plastics
Paine 59 (130)
Crease
llHTt
Textiles
Rubber
Test Period
July At
kg (Ib) kg
25,652 (56,552) 12,919
18,684 (41,191) 7,985
6,940 (15,300) 4,782
17 (38) 14

12 (26) 20
82
13
22

igust
(Ib)
(28,481)
(17,605)
(10,543)
(31)

(45)
(181)
(28)
(48)

1
kg
51,722
33,993
17,490
31
59
32
83
13
22

total ]
(Ib) o:
(114,027)
(74,943)
(38,557)
(69)
(130)
(71)
(181)
(28)
(48)

Percent
E Total

65.7
33.8
<.l

<.l
.1
<.l
<.i
     In the computation of the system mass balance on a per ton input basis,
shown in Figure 26, the amounts of the combustion air and the afterburner
section air had to be computed by subtracting the mass of the other inputs
from the total mass output.  This was done because the air masses could not
be directly measured.

     During the second field test, the energy recovered was 150 GJ (142 MBtu)
as measured by the BTU meter and 180 GJ (174 MBtu) as computed by the heat
loss method.  The effectiveness and the thermal efficiency of the boiler were
90 and 82 percent, respectively.
                                     48

-------
                                 Mass balance 120-hour test*
                              Input
                                                     Output
                      Mg per Mg refuse
                Source       or
                      Ton per ton refuse
            of Total   Mg per Mg refuse
                        or
                    Ton per ton refuse
                                                              of Total
              Refuse
              Cooling spray.
                water
              Natural gas
              Combustion air
              Flue gases
              Residue, dry

              Total
 1.00

 0.65
 0.02
18.39
                         20.06
 4.99

 3.24
 0.10
91.67
                                     100.00
                         20.01
                        	.04

                         20.05
                         99.80
                         0.20
                                                              100.00
              * Total refuse input 25.6-Mg (28.3 tons)
                    GAS
            WATER
           REFUSE
   Figure 26.  Mass balance  for incineration-heat recovery processes in
                Marysville faciltiy during  the 120-hour  (75.5-hour  heat
                recovery) July  field test.
      The energy balance in Figure 27 compares the measured energy  inputs and
outputs on a per  ton input basis.  For this  balance,  the inputs were refuse,
quench water, auxiliary fuel,  and electricity.   The outputs were the hot
water generated,  sensible heat and remaining energy in  the residue,  heat lost
by radiation and  convection, and sensible heat  in the flue gases.  The energy
inputs and outputs  for the 120-hour test totaled 436 GJ and 409 GJ (413 and
388 MBtu), respectively.  The  difference of  27  GJ (25 MBtu) or 6 percent
of the energy input was not accounted for.

      As shown in  Figure 27 for the energy balance, 19 percent of the heat
was lost by radiation and convection, and 14 percent was lost during the
burndown cycles.
                                         49

-------
                                   Energy balance 120—hour test*
Input
GJ per 1 HBCu per J % of total
Source Mg of refuse VTon of refused
Refuse 16.36 (14.07) 96.4
Electricity 0.12 ( 0.10) 0.7
Natural gas
Heat recovery 0.29 ( 0.25) 1.7
Burndown 0.21 ( 0.18) 1.2
Residue
Radiation and
Convection
Ifeat recovery
Bumdoun
Flue gases
Heat recovery
Burndown
tllot vater
(aeasured)
16.98 (14.60) 100.0
Output
GJ per I MBtu per
Mg of refuse \ Ton of refuse


0.


2.
0.

4.
2.

6.
15.


03


.26
.82

,19
.27

,09
,66


( .


(1,
(0,

(3,
(1.

(5.
(13.


.03)


.94)
.71)

.60)
.95)

.24)
.47)
j % of


0


14
5

26
14

38
100
total


.2


.4
.3

.7
.5

.9
.0
     *Total refuse input 25.6 Mg (28.3 ton)
     tllot water output by difference 7.41 GJ/Mg refuse (6.37 MBtu/ton)
                                           FLUE GAS
               CAS
                                                                 HOT WATER
  Figure 27.
Energy balance for incineration-heat recovery processes  in
Marysville  facility during the  120-hour (75.5-hour heat
recovery) July field test.
     The system energy efficiency  during the heat recovery  periods as
calculated by  the heat loss method was  54 percent.  The system energy
efficiency for a week-long test, including heat recovery and  burndown
periods was  42 percent.  The net efficiencies were 54 and 43  percent,
respectively.

     While the facility was capable  of  handling all incoming  refuse and of
meeting the  plant's heating and cooling demands, it operated  at only 63 per-
cent of capacity during the two 8-hour  shifts.

     The delivery of waste varied  widely in amounts and times.   The unit was
underfed most  of the time, but occasionally it was overfed.   This is evidenced
                                       50

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by Figure 28 which  shows an overload period when the boiler entrance tempera-
ture was higher  than the secondary -chamber temperature.   Figure 29 shows gas
emission peaks caused by overfeeding during the same period.

     One man could  readily operate the facility.  Corrective maintenance
required (1) once or twice a week removal of residue,  (2)  the weekly removal
of particulate accumulations from the blades on the induced draft fan that
made the fan vibrate excessively toward the end of the week,  and (3) the
semiannual removal  of slag accumulations from the boiler  tubes.
                 J

'. ini

i '
in
..
1 • • 19
.
'
;
in
':q
' .
, , .
1/j
_ —
in
                                                              2200
                                        1. Primary Chamber Temperature
                                        2. Secondary Chamber Temperature'-
                                        3. Boiler Entrance Temperature
                                         > i i • •  • i ••• : I - ' •!    i  •:  i
                                         > • '• i ;  1800 .  i .  2000'    .2200  , !
                                              ---4-     -~"-"
        Figure 28.   System temperatures during peak  loading periods in
                     Marysville facility.
                                      51

-------
                                                                         x  5 = ppm
                                                                         x 10 = ppm
                                                           L 3. NOX       x  5 = ppm
                                                           ; 4. Opacity        = percent
                                                       ""i	r 5. 02        *  4 = percent —
 " "T" ~ ~ "" ">*T~ ~~ "••" ~— — — "T"
                                                            _J	L	L_ i
                                                             - --
Figure 29.   Stack emissions during peak loading periods in  Marysville facility.
                                          52

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Environmental Evaluation

     For the July test, Table 14 presents the  flue  gas  emissions  in  terms
of grains or ppm and of pounds per hour per ton of  refuse processed.  Table  15
summarizes the emissions for each of the three test periods.  The size  distri-
bution analysis of the particulates during the July test revealed that
85 percent by weight of the particulates were smaller than  7 urn.   The concen-
trations of chloride ranged from 4 to 136 mg/m3 (3  to 94 ppm) and averaged
38 mg/m3 (26 ppm) while those of fluoride ranged from 0.2 to 2.0  mg/m3
(0.3 to 2.6 ppm) and averaged 0.9 mg/m3 (1.1 ppm) over  the  three  test periods.
The light (Ci to C6) hydrocarbons varied widely in  the  range from 1.8 to
1423 mg/m3 (1.2 to 936 ppm).

     No significant amounts of pollutants were found in the residue or  its
laboratory-produced leachate (see Table 16).  Within the facility building,
the fugitive dust levels were low, and no noise levels exceeded the OSHA
limits (see Figure 30).   No significant amounts of  pollutants were 'found at
the upwind or downwind ambient air sample sites which were both at a 91.4-m
(300-ft) distance from the boiler exhaust stack.
TABLE 14.- MARYSVILLE POLLUTANT EMISSION RATES FOR JULY TEST
Emission rate
Pollutant
Particulate
SOX
NOX
CO
HC-
Lead
Maximum
0.111 gr/SCF*
31 ppm
125 ppm
<1000 ppm
2285 ppm

Average
.049 gr/SCF*
8 ppm
30 ppm
240 ppm
765 ppm
624 yg/m^
Minimum
.033 gr/SCF*
<5 ppm
6 ppm
17 ppm
21 ppm

Ib/ton refuse
charged
2.01
.44
1.19
5.81
10.4
0.02
     * Corrected to 12 percent C02.
                                     53

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                                TABLE  15.  MARYSVILLE SUMMARY OF  STACK EMISSIONS FOR APRIL,
                                            JULY, AND AUGUST TESTS
Ul
Emissions (units)
Particulate (gr/SCF)*
Particulate (g/m3)*
Chlorides (mg/m3)
Fluorides (mg/m3)
02 (percent)
C02 (percent)
CO (mg/m3)
NOX (mg/m3)
S0x (mg/m3)
Particulate size (um)#
Hydrocarbons (mg/m3)<|>
Opacity (percent).
H20 (percent by volume)
Flue gas temperature (°F)
Flue gas flow (SCFM)
Flue gas flow (ACFM)

Test
Max

1: April

24-28, 1978
Avg Min Std Dev
Not Isokinetic

23.0
0.7
17.8

>1000
191
37

105

14.4
150
1790
3765


13.9
0.5
14.0
No Data
148
64
16
No Data
17.9
No Data
8.4
195
2195
2773


5.8 7.1
0.2 0.2
10.7 1.7

26 27
<10 38
<13 7.0

1.8
—
1.8
227
3155
2205

Test
Max
0.111
0.253
136
2.0
18.5
10.5
>1000
239
82
29
1400

16.4
237
6830
9350
Field
2: July
test
7-17.

1978
Avg Min Std Dev
0.049 0
0.111 0
78.6
0.9
14.3
9.7
279
59
15
0.3
475
No Data
14.5
280
2870
4075
.033
.075
9.3
0.3
5.4
7.2
20
11
<13
<0.3
13.7

13.3
291
2210
3100
0.024
0.054
49.7
0.6
2.8
1.01
129
47
21
—
—
—
—
—
~

Test 3:
Max
0.133
0.303
31.7
1.7
19. 4t
9.0
363
143
56
27
204
42
14.4
217
2490
3920

August
Avg
0.088
0.201
11.4
1.0
15.9
5.6
108
33
9.0
0.7
70
—
9.6
326
2250
3445

21-25
Min
0.060
0.137
4.2
0.7
12.4
3.4
8
<10
<13
<0.7
9.1
15
1.8
459
1700
2235

, 1978
Std Dev
0.027
0.061
8.6
0.3
1.9
1.8
93
34
10
—
~
—
—
	

               *  Corrected to 12 percent C02
               t  During charging hours only
               #  Average is mass mean diameter
                 Average CHi.-Ci.Hio

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     TABLE 16.   MARYSVILLE RESIDUE LEACHATE  PARAMETER AND
                COMPONENT VALUES

PH
Conductivity
Alkalinity
TKN
Hardness
TOG
Ortho-Phosphate
Total Phosphate
Sulfide
Chloride
Acidity
Total Dissolved
Solids
Ammonia as N
COD
Sulfate
Bromide
Fluoride
Boron
Mercury
Cadmium
Antimony
Lead
Chromium
Arsenic
MBAS
Phenols
Cyanide


umhos
mg/X
mg/X
mg/X.
mg/X.
mg/X,
mg/X,
mg/X
mg/X.
mg/2.

mg/X.
mg/X,
mg/L
mg/X.
mg/X,
mg/X
mg/X
yg/x.
yg/x.
yg/x
yg/x.
yg/x.

mg/X,
mg/X
mg/Jl
Water Blank
5.52
2.78
1.10
6.95
2.00
3.10
0.005
0.01
<0.002
ND
5

<1
0.216
ND
<1.00
<0.100
0.058
<0.1
<0.1
<1
<1.0
<1
<1
ND
-
-
—
Test 1
10.24
379.00
78.10
2.59
112.30
5.00
0.002
0.063
<0.002
1.51
ND

236
0.170
ND
68.00
<0.100
0.662
2.6
<0.1
<1
18.7
1.3
3280
ND
-
-
—
Phosphate Buffer
Test 2
6.2
3700
232
7.05
<0.1
<1
1230
1360
< .003
43
1938

6012
' 0.076
52.5
0.19
0.64
0.363
65.6

„
_
_
-
_
.121
.080
.002
ND = None detected
                               55

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                           PRIMARY CHAMBER
                              LOADER
                                                BUILDING
                                                         STACK
                                                         BOILER
                                                           ID FAN
             LOCATION


             1 LOADER

             2 LOADER
             3 WORK FLOOR

             4 BOILER FRONT

             5 BOILER REAR
SOUND LEVEL, dB


77
78
78

83
83
             6 ELECTRICAL PANELS 80
         Figure 30.   In-plant noise-level plot for Marysville facility.
     Of  the pollutants detected in  the  EPA Level 1 analysis, antimony,
arsenic, mercury,  and heavy organic compounds were found consistently in
small amounts.   Other metals such as lead,  cadmium, chromium, and  barium
were found  occasionally in small amounts  (see Table 17).  The contaminants
ware found  in the stack emissions and the residue.
Economic Evaluation

     The total cost of- the facility was $509,949 in 1977.  Table  18  presents
the total cost breakdown by EPA cost  categories, and Table 19 presents the
unit operational costs which were  obtained from records maintained by the
plant engineer.  Table 20 presents a  comprehensive economic evaluation for
each cost center based on actual operating conditions during July.
                                       56

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   TABLE 17.   MARYSVILLE SUMMARY OF ELEMENTS
               DETECTED  IN STACK EMISSION FILTERS
                             Emission rate
Element
Concentration in gas
       (Ug/m3)*
Emission factor
g/Mg  of refuset
Silicon
Iron
Aluminum
Sodium
Calcium
Potassium
Magnesium
Lead
Zinc
Cadmium
Beryllium
Titanium
Chromium
Copper
Nickel
Manganese
Lithium
Antimony
Boron
Tin
Vanadium
* Concentrations based
July test' period.
t g/Mg * 500 = Ib/ton
2.95
520.
2,202.
13,839.
1,749.
450.
640.
624.
2,724.
428.
0.09
0.419
1.66
19.3
1.78
11.4
2.10
1.69
98.1
3.33
2.30
on a composite of


.042
7.45
31.5
198.0
25.0
6.44
9.17
8.93
39.0
6.14
.0014
.0060
.0237
.277
.0255
.164
.030
.0243
1.41
.0477
.033
five filters from


       TABLE  18.  MARYSVILLE CAPITAL COSTS*
                                Incineration  Heat Recovery
Land
Site preparation
Design
Cons truction
Real equipment
Total capital investment
$ 1,000
t

7,000
69,302
77,302
$ 2,000
t
12,500
82,166
335,081
432,647
*  Based on 1977  dollars.

t  Site preparation costs were not identified in Rockwell
   International  Corporation accounting  records.
                          57

-------
                  TABLE 19.  MARYSVILLE UNIT COST DATA*
             Salary rates (annual, .FY 78):

                General helper

                Employee benefits rate

             Natural gas

             Electricity rate

             Water rate

             Sewer

             Chemical (NC-1) costs
   $14,500

    $5,800

  $0.091/k£

$0.0282/kwh

$0.24/1000£

        t

   $2.30/£
             *Based on costs incurred in 1978.
             tOn-site disposal (septic system).
     Although  the incinerator-heat recovery  facility was installed  to
provide an assured energy supply for the plant's heating and air conditioning
systems, and not  to produce revenue by  itself;  it indirectly produces  a
revenue by eliminating the costs previously  expended for the propane used
during the winter, for the electricity  used  during the summer, and  for the
compactor and  container used to dispose of the  solid waste.

     During the three test periods, the average heat recovery rate  was
23,025 MJ  (21.8 MBtu) per day.  With estimated  heating and cooling  seasons
of 128 and 122 days, respectively, and  with  the previous propane and
electricity costs of $0.00404 and $0.00769 per  MJ ($3-83 and $7.29  per
MBtu), respectively, the facility yielded  an annual savings, or annual
revenue equivalent, of $23,557.  The costs of  the solid waste disposal
method that were replaced amounted to $27,500  per year or $24.21 per Mg
($22.95 per ton).  The net operating costs by  system function are shown in
Table 21.
                                       58

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       TABLE  20.   MARYSVILLE PROJECTED ANNUAL OPERATING  AND MAINTENANCE
                   COSTS PER COST  CENTER*

                                                    Cost Center
Cost classification
Salaries
Employee benefits
Fuel
Water and sewer
Electricity
Maintenance
Chemicals
Interest
Depreciation
Sub total
General plant allocation:
Total
Total
cost
$ 14,500
5,800
9,914
163
" 829
15,004
65
24,480
34,815
$105,570

$105,570
Receiving
$ 7,250
2,900


45
828

687
1,255
$12,965
3,045
$16,010
Incineration
$ 5,800
2,320
9,914
163
235
3,498

2,918
5,300 •
$30,148
4,084
$34,232
Heat
recovery
$ 1,450
580


549
5,818
65
16,592
24,499
$49,553
5,775
$55,328
General
plant





$ 4,860

4,283
3,671
$12,904


  *Based on 1978 dollars.
       TABLE 21.   MARYSVILLE NET OPERATING COST BY  SYSTEM FUNCTION*
       Net savings (cost)
         of operation
                                  Incineration
                         Incineration and
                          Heat recovery

Operating and
maintenance
Disposal savings
Energy savings
($/yr)
(34,232)
27,500

($/Mg) ($/ton) ($/yr)
(28.53) (105,570)
22.95 27,500
23,557
($/Mg) ($/ton)
(87.98)
22.95
19.63
( 6,732) (5.92) ( 5.61) ( 54,513) (47.93) (45.43)
       *  Based on 1978 dollars, 1200 tons annually.
          Operating cost includes interest and depreciation.


     In summary, the facility required an initial capital investment of
$509,949  in  1977.   Of this amount, $77,302 was spent on  the incineration
system to dispose  of the solid waste  and $432,647 was  spent to recover and
utilize the  energy.  The anticipated  net annual operational cost of the
facility  in  1978 dollars would be  $105,570 or $47.93 per Mg ($45.40 per ton).
The as-operated economics would produce an after tax positive cash flow of
$85,400 the  first  year and $7,600  for each year thereafter.  The first year
value includes  all of the 10 percent  investment tax credit and the additional
10 percent energy  credit effective in 1978.
                                       59

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                                   SECTION 4

                          OPERATING COST PROJECTIONS
EVALUATED FACILITIES

     Since the two evaluated facilities at North Little Rock, Arkansas, and
Marysville, Ohio, were not operating at optimum conditions when they were
monitored, the cost and revenue for the as-operated conditions at each
facility were extrapolated to the optimum conditions.  If the North Little
Rock facility had operated under optimum conditions, that is, with the feed
rate and steam production equal to the design capacities of 3.6 Mg (4 tons)
and 9090 kg (20,000 Ib) per hour, respectively, it would have had a total
revenue and a revenue per Mg (per ton) of refuse processed that would have
been $127,773 and $3.08 per Mg  ($2.79 per ton), respectively, more than the
revenue for the as-operated conditions.  The optimum operating costs are
given in Table 22, and the revenues are shown in Table 23.  If the Marysville
facility had operated under optimum conditions, that is, with a daily feed
rate and energy recovery equal  to the design capacities of 545 kg  (1200 Ib)
and 6.17 GJ (5.85 MBtu), respectively, it would have yielded a savings of
$104,270 or $31.94 per Mg ($28.96 per ton) of refuse processed.  The optimum
operating costs are shown in Table 24, and the revenues are shown in Table 25.
These revenues will give a payback within 5 years.

FACILITIES IN GENERAL

     To estimate the operating  costs at municipal and industrial facilities
in general, the 1978 economic data for the various operating parameters at
the two evaluated facilities were adapted in an empirical method to develop
equations expressing the relationship between the net loss or profit and
three independent parameters, namely refuse feed rate, shifts per week, and
operating percentage of rated capacity.

     To determine the net operating costs of the municipal facilities, the
following assumptions were made:   (1) the average employee salary is $20,800
per year including benefits, (2) the auxiliary fuel used is natural gas at
a unit cost of $0.088/kJl  ($2.50 MCF) ,  (3) the electric power unit cost is
$0.035/kwh, (4) the unit cost of water is $0.24/k£ ($0.90/1000 gal), (5) the
ratio of the wet residue to the as-received refuse is 0.40,  (6) the cost of
residue disposal is $4/Mg,  (7)  the interest rate is 7 percent,  (8) the
estimated life of the facility  is 15 years, (9) the heat content of the
refuse is 10.4 MJ/kg (4500 Btu/lb), and  (10) the recovered energy value is
$0.00245/MJ ($2.60/MBtu).
                                       60

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TABLE  22.  NORTH LITTLE ROCK PROJECTED OPTIMUM OPERATING
            AND MAINTENANCE COSTS*
Item
Salaries
Employee benefits
Fuel - no. 2 diesel
Natural gas
Gasoline
Electricity
Water and sewer
Maintenance
Replacement equipment
Residue removal
Chemicals
Interest
Depreciation
Other overhead
Total operating and
maintenance costs
Cost
($/yr)
$111,284
15,750
4,608
16,704
3,888
19,237
8,121
65,656
—
t
5,033
39,179
78,070
3,209
$370,739

($/Mg)
$ 5.11
0.72
0.21
0.77
0.18
0.88
0.37
3.02
—
t
0.23
1.80
3.59
0..15
$17.03
  *  Based on 1978 dollars.

  +  Cost  Included  in salaries and employee benefit categories.
     TABLE  23.   NORTH LITTLE ROCK PROJECTED  OPTIMUM
                 ANNUAL REVENUES*
     Revenues
                                              Cost
      Steam production

      Tipping fees
$280,772

  24,336
     Total
$305,108
     Per Mg of  refuse processed (per ton)    $14.02 (12.72)
      *  Based on 1978 dollars.
                               61

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TABLE  24.   MARYSVILLE PROJECTED  OPTIMUM OPERATING
            AND MAINTENANCE COSTS*
Item
Salaries
Employee benefits
Fuel
Electricity
Water and sewer
Maintenance
Chemicals
Interest
Depreciation
Total
Cost
($/yr)
21,750
5,438
14,871
1,244
244
15,004
98
24,480
34,815
117,944

($/Mg)
6.66
1.66
4.55
0.38
0.07
4.59
0.03
7.49
10.66
36.12
*  Based on 1978 dollars.
   TABLE 25.   MARYSVILLE PROJECTED OPTIMUM NET
               OPERATION COSTS*

Item
Operating and maintenance
Disposal savings
Energy savings
Net savings

($/yr)
117,944
82,620
139,594
104,270
Cost
($/Mg)
36.12
42.75
25.30
31.94

($/ton)
32.76
38.77
22.95
28.96
 *  Based on 1978 dollars.
                          62

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     To determine the net operating cost of the industrial facilities, the
following assumptions were made:  (1) the average employee salary is $20,800
per year including benefits, (2) the auxiliary fuel used is natural gas at
a unit cost of $0.088/k& ($2.50 kCF), (3) the electric power unit cost is
$0.035/kwh, (4) the unit cost of water is $0.24/k& ($0.91/1000 gal), (5) the
ratio of the wet residue to the as-received refuse is 0.10, (6) the cost of
residue disposal is $4/Mg,  (7) the interest rate is 12 percent, (8) the
depreciation period is 7 years, (9) the heat content of the refuse is
7.91 MJ/kg (7500 Btu/lb), and.(10) the recovered energy value is $0.00311/MJ
($3.28/MBtu).   The higher energy value can be used because the industry is
the energy user and does not have to sell energy at a derated price.

     The resultant data for the municipal and industrial facilities are
summarized in Figures 31 and 32, respectively, where the curves A through F
represent possible operational modes.  In the development of these figures,
it was assumed that the refuse would be generated only 5 days per week.
The 7-day operational mode is burning a 5-day per week refuse generation
over a 7-day per week refuse processing.  At 100 percent of rated capacity,
the net operating costs for 15 and 21 shifts per week in municipal systems
are nearly the same.  As seen in Figure 31, the net operating cost per unit
of refuse feed rate is $10/Mg ($9/ton) or less for the capacity range
between 45 and 90 Mg/5 days (50 and 100 tons/5 days).

     With refuse feed rates in the range of 27.5 Mg/5 days (25 tons/5 days)
and above, industrial facilities will yield a positive balance, or revenue,
in the net operating cost computation when they operate at 100 percent of
rated capacity but an actual cost in the net operating cost computation
when they operate at 50 percent of rated capacity.  This cost must be
compared with the cost of alternative waste disposal methods and fuel
sources to determine the economic feasibility of a proposed system.
                                     63

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    30 (27.0)
                                                              A-OFF GRAPH
    25 (22.5)
 5  20 (18.0)
 SB
 §  15 (13.5)
    10  (9.0)

     5   (4.5)   -
Figure 31.
                                                            180
                                                           (200)
                  REFUSE GENERATION RATE IN MgPD5 (TPD-O
Estimated operating  cost  as a function of refuse feed  rate,
shifts per week,  and operating percentage of rated  capacity
for municipal small  modular incinerators.
                                    64

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                                                      NET OPERATING BALANCE  IN $/Mg  ($/TON)
                                   SAVINGS
COST
         H
         CD
ON
Ln
0 H
PJ P)
T3 rt
PI ro
O "
H-
rt cn
•
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                          EPA  REGIONS
U.S. EPA, Region 1
Solid Waste Program
John F. Kennedy Bldg.
Boston, MA 02203
617-223-5775

U.S. EPA, Region 2
Solid Waste Section
26 Federal Plaza
New York, NY 10007
212-264-0503

U.S. EPA, Region 3
Solid Waste Program
6th and Walnut Sts.   ,
Philadelphia, PA 19106
215-597-9377

U.S. EPA, Region 4
Solid Waste Program
345 Courtland St., N.E.
Altanta, GA 30308
404-881-3016
U.S. EPA, Region 5
Solid Waste Program
230 South Dearborn St.
Chicago, IL 60604
312-353-2197

U.S. EPA, Region 6
Solid Waste Section
1201 Elm St.
Dallas, TX 75270
214-767-2734

U.S. EPA, Region 7
Solid Waste Section
1735 Baltimore Ave.
Kansas City, MO 64108
816-374-3307
U.S. EPA, Region 8
Solid Waste Section
1860 Lincoln St.
Denver, CO 80295
303-837-2221

U.S. EPA, Region 9  *
Solid Waste Program
215 Fremont St.
San Francisco, CA 94105
415-556-4606

U.S. EPA, Region 10
Solid Waste Program
1200 6th Ave.
Seattle, WA 98101
206-442-1260
                                                             U01833
                                                             SW-797

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•

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