COMBINED FIRING SYSTEMS FOR
SPECIFIC METROPOLITAN AREAS
A Final Report to the
ENVIRONMENTAL PROTECTION AGENCY
Report No. F-0303
November 1971
-------
COMBINED FIRING SYSTEMS FOR
SPECIFIC METROPOLITAN AREAS
A Report to
-ENVIRONMENTAL PROTECTION AGENCY
CONTRACT NO. EHSD 71-9
By
R. M. Roberts and R. C. Hanson
NOVEMBER 1971
ENVIROGENICS COMPANY
A DIVISION OF
AEROJET -GENERAL CORPORATION
EL MONTE, CALIFORNIA
-------
ABSTRACT
The purpose of the present study was to develop for two major
cities design recommendations and procedures for the disposal of
refuse', a low sulfur fuel, with heat recovery in utility grade boilers.
The guidelines observed were those generated on a previous Enviro-
genies I program performed on EPA Contract CPA 22-69-22. In that
work, optimal system design configurations were identified and the
benefits to the environment and the economy quantified. Thus the
present program has been one of applying that knowledge to specific
case study areas.
.....
Arrangements with two cities having high S02 burdens and
growing solid waste burdens were made; these were Philadelphia,
Pennsylvania, and Cleveland, Ohio. Information required for the
study was collected and analyzed. Specific design packages were
then developed for each city. Contained therein are projections des-
cribing the future nature of the city refuse-fuel inventories, specific
recommendations as to plant types, sizes, and sites, cost analyses
of operations involving the utilization of such systems, and estimated
reduction in S02 and particulate emissions. From these data, the
conclusion can readily be drawn that the systems recommended would
be more cost-effective than the methods that are now in use.
ii
-------
TABLE OF CONTENTS
Page
ABSTRACT. . . . . . . . . . . . . . .
~4.
~
. . . . . . . .
11
. . . . . . . .
1.
INTRODUCTION AND SUMMAR Y
. . . . .
A.
B.
C.
D.
. . . . .
. I-I
. . . . .
Background. . . . . . . . . . . . . . . . . . . . . . . . I-I
Summary of the Preceding Program. . . . . . . . . . . I-I
Scope of the Present Study. ., . . . . . . . . . . . . . . 1-2
B.
C.
D.
E.
Program Summary. . . . . . .
. . . . . .
. . 1- 3
l.
2.
3.
4.
5.
6.
. . . . .
Selection of Metropolitan Sites. . . . . . . . . . . 1- 3
Data Acquisition and Analysis. . . . . . . . . . . 1-3
Design Recommendations. . . . . . . . . . . . . . 1- 5
Cost Analysis. . . . . . . . . . . . . . . . . . . 1-7
Cost Analysis Results. . . . . . . . . . . . . . . . 1-8
Potential Reduction of Air Pollutants. . . . . . . 1- 9
II.
THE PHILADELPHIA STUDY. . . . .
. . . . .. .. ..
A.
.. .. .. .. ..
. II-I
Waste Management Operations
.. .. .. ..
. . II-I
.. .. .. .. .. .. .. ..
Refuse Inventory and Composition Projections. . . . . . II- 3
l.
2.
Refuse Quantities. . . . . . . . . . . . . . . . . . II-3
Refuse Composition. . . . . . . . . . . . . . . . . II- 8
Fuel Characteristics of Philadelphia Refuse. . . . . . . II-II
l.
2.
Heating Value. . . . . .
Combustion Calculations
. . . . . . . . . . . . . . 11- II
. . . . . . . . . . . . . . 11- II
Utility Steam Generation Operations
.. .. .. .. .. .. ..
II- 13
.. .. .. ..
l.
2.
3.
Steam Generator Inventory. . . . . . . . . . . . . II-I3
Effect of Firing Refuse on Pollution Burden. . . . II-20
Suggested Study Guidelines . . . . . . . . . . . . . II-2I
Preliminary Planning Recommendations.
.. .. .. .. ..
. . . II- 22
l.
2.
3.
Overview . . . . . . . . . . . . . . . . . . . II-22
District Steam Plant. . . . . . . . . . . . . . . . II-23
Power Plant. . . . . . . . . . . . . . . . . . . II- 34
111
-------
TABLE OF CONTENTS (Continued)
III.
THE CLEVELAND STUDY. . . . . . . . .
. . . . "
A.
B.
C.
D.
E.
" " " "
Waste Management Operations.
" " " " " " " "
" " " "
1.
2.
3.
Municipal Background Information. . . . . . .
Present Waste Management Program. . . . . .
Future Waste Management Plans. . . . . . . .
Refuse Inventory and Composition Projections
" " " "
1.
2.
Refuse Quantities. . . . . . . . . . .
Refuse Composition. . . . . . . . . .
" " " " "
" " " " "
Fuel Characteristics of Cleveland Refuse
" " " " " " "
1.
2.
Heating Value. . . . .
Combustion Calculations. .
" " " "
" " " " " " "
" " " " "
" " " " " "
Utility Steam Generation Operations. . . .
" " " " " "
l.
2.
Municipally-Owned Boilers. . . . . . . . . . .
Cleveland Electric Illuminating Co.
(CEl) - Owned Boilers. . . . . . . . . . . . . .
Effect of Firing Refuse on Pollution Burden
3.
Preliminary Planning Recommendations
" " " " " " "
l.
2.
3.
4.
5.
Ove rview ....................
Refuse-Fired District Heating Plant. . . . . .
Refuse-Fired Turbo-Electric Plant. . . . . .
Transportation Costs. . . . . . . . . . . . . . .
Conclusions Regarding the Cleveland Study. . .
ACKNOWLEDGEMENTS
REFERENCES
'" " " " " " " " " " " " " " " " " " " " " "
" " " "
" " " " " " " " " " " " " " " " " " " " " " "
lV
Page
III - 1
IIl- 1
III - 1
III - 5
III- 5
III - 6
III-6
lII- 7
III- lO
III-I 0
IIl-lO
IlI- 16
III- 16
III - 1 6
III-l 7
III-18
Ill- 1 8
III-19
1II-28
III - 35
lII-40
III - 42
1II-44
-------
Table No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
\ 17.
18.
19.
20.
21.
LIS T OF TABLES
SMSA's Ranked by Severity of S02 Problem. . . . . . . . . . .
Characteristics of Proposed Steam Generators. . . . . . . . .
Philadelphia Refuse Collection/ Disposal Statistics by Districts
Philadelphia Refuse Densities by Districts. . . . . . . . . . .
Combustion Gas Requirements Based on Projected 1980
Philadelphia Mixed Refuse Composition. . '. . . . . . . . . . .
Products of Refuse Combustion Based on Projected 1980
Philadelphia Mixed Refuse Composition. . . . . . . . . . . . .
Efficiency of Steam Generator Firing Philadelphia Mixed
Refuse of Composition Projected for 1980 . . . . . . . . . . . .
Utility Power Boiler Inventory Within the City of Philadelphia
Utility Steam Plant Inventory Within the City of Philadelphia. .
Costs for the 1400 TPD Philadelphia District Heating Plant. .
Characteristics of 300 MW, Case 3 Power System. . . . . . .
Estimated Costs for a 300 MW Combined-Fired Turboelectric
Plant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion Gas Requirements for Cleveland Refuse Composition
Projected for 1980 . . . . . . . . . . . . . . . . . . . . . . . .
Products of Combustion of the Refuse Projected for Cleveland
in 1980 . . . . . . . . . . . . . . . . . . . . . . . . . . .
Efficiency of Steam Generator Firing Cleveland Refuse of
Composition Projected for 1980 . . . . . . . . . . . . . . . . .
System Characteristics of Canal Road Steam Plant (Refuse Fired)
Estimated Costs for the Over-the-Fence, Refuse-Fired Steam
Bo ile r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Estimated Costs for Refuse-Fired Boiler Installed On-Site at
Canal Ro ad Plant. . . . . . . . . . . . . . . . . . . . . . . . .
Characteristics of 200 MW, Combination-Fired System for the
Lake Sho re Plant. . . . . . . . . . . . . . . . . . . . . . . . .
Estimated Costs for Refuse-Fired, Turbo-Electric System
Installed at the Lake Shore Plant. . . . . . . . . . . . . . . .
Refuse Input Areas Assumed for Transportation Cost Analysis.
v
Page
1-4
1-6
II-4
Il-5
Il-14
II- 15
U-16
II-I8
Il- 1 9
II-29
II- 35
II- 40
I11-12
III - 1 3
III-14
III - 22
1II-24
1II-29
I11-32
III-34
IIl- 3 7
-------
Table No.
22.
23.
LIS T OF TABLES (Continued)
Refuse Transportation Cost Factors for Existing Cleveland
D i 5 po s al S it e s . . . . . . . . . . . . . . . . . . . . . . . . . . .
Refuse Transportation Cost Factors for Proposed Steam
Gene r ate r s . . . . . . . . . . . . . . . . . . . . . . . . .
. . . .
vi
Page
III- 3 8
III-39
-------
Figure No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
ll.
12.
13.
14.
15.
16.
17.
18.
19.
20.
LIST OF FIGURES
Page
Philadelphia Sanitation Areas and Incinerator System. . . . . . II-2
Refuse Collection Rates in Philadelphia - Recorded and
Proj ected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1I- 6
Projected Philadelphia Boiler Refuse-Fuel Inventories. . . . . II-9
Projected Compositional Changes in Philadelt>hia Mixed Refuse. II-lO
Projected Increase i~ Heating Value of Mixed Philadelphia Refuse II-12
Locations of Utility Power and Steam Plants in Philadelphia. . . II-17
Lay-out of Steam Plant. . . . . . . . . . . . . . . . . . . . . . II...26
District Heating Plant - Refuse Disposal Costs as a Function of
Creditable Steam Value. . . . . . . . . . . . . . . . . . . . . . 11- 3 0
Steam Distribution System of the Philadelphia Electric Company
Refuse-Fired Economizer of the Case 3 Type ..........
Disposal Costs for 300 MW Plant as a Function of Fuel Cost. .
Ward Map of the City of Cleveland. . . . . . . . . . . . . . . .
Refuse Collection Districts in City of Cleveland. . . . . .
Projected Compositional Changes in Cleveland Refuse. . . . . .
Projected Change in Heating Value of Cleveland Refuse. . . . .
Efficiencies at Various Flue Gas Exit Temperatures of a Steam
Generator Firing Projected 1980 Cleveland Refuse. . . . . . . .
Cleveland's District Heating System. . . . . . . . . . . . . . .
Canal Road Steam Plant. . . . . . . . . . . . . . . . . . . . . .
Proposed Modification of Canal Road Plant. . . . . . . . . . . .
Lake Shore Plant Layout. . . . . . . . . . . . . . . . . . . . .
II-32
II- 3 7
II-4l
I11-2
III-4
llI-'9
Ill-II
Ill- 1 5
ill-20
Ill- 26
IIl~ 2 7
III - 3 1
Vll
-------
1.
II.
APPENDIX A
TITLE: COSTS OF OPERATING PLANTS
OF OVERSIZED REFUSE CAPACITY
INTRODUCTION
. . . . .
. . . . . . . . . . . . . . . . .
COST ANALYSIS
A.
B.
Figure No.
A-I
. . . . . . . .
. . . . . .
. . . . . . . .
Sys tern Options
. . . . . . . . .
. . . . . . .
. . ,. .
Cost Analysis Results.
. . . . .
. . . . .
. . . . . .
FIGURES
Disposal Costs for Plants Operating at Less Than
Full Refuse Input Rating. . . . . . . . . . . . . . . .
Vlll
Page
A-I
A-I
A-I
A-2
A-3
-------
1.
INTRODUCTION AND SUMMARY
A.
BACKGROUND
The work documented in the present report represents a logical
sequel to a larger program effort recently completed for the EPA. The
conclusions and recommendations developed therein concerning the economic,
technological, and environmental aspects of disposing of refuse in utility
class steam generators, have now been applied to specific metropolitan'
case areas.
The initial study, entitled "Systems Evaluation of Refuse as a
Low Sulfur Fuel, " was accomplished on EPA Contract CPA 22-69-22. It
was carried out by the Envirogenics Co. in conjunction with the Foster
Wheeler Corp. and Cottrell Environmental Systems, Inc. The final report
has recently been released (Ref. 1) and should be consulted if the background
information on which the p'resent work is based is to be fully appreciated.
A brief summary of the CPA 22-69-22 program is given in the following
paragraphs.
B.
SUMMARY OF THE PRECEDING PROGRAM
The ground-laying work done on EPA Contract 22-69-22 was
addressed to the assessment and systematic optimization of the mechanics
and combustion methodology associated with the utilization of refuse as a
fuel for generating steam. While benefiting waste management interests,
it was noted that refuse firing could also displace conventional fuels that
cause high sulfur oxide emissions. The extent of S02 - abatement possible
was projected to the year 2000, by estimating the quantities and composition
of refuse that would likely be available.
Determining the useful energy from refuse involved the associated
task of establishing for this fuel its behavior in and compatability with furnace
structures. This required the definition of the various energy utilization
opportunities for which refuse might be suited. With emphasis logically
aligned to power plant applications, the relevant technology and state-of-the-
art (particularly in Europe) of power generation with refuse were documented.
In this connection, processes and hardware used in the handling and condition-
ing of refuse were also reviewed. Criteria were then established for
firing refuse in utility-class boilers.
A catalog of ten different combined-fuel (coal + refuse) fired
boiler configurations were conceived and then analyzed in terms of process
variables (plant power capacity, fuel-ratio, etc.); performance/cost
characteristics were also predicted. Similarly treated were five plans for
1-1
-------
modifying existing plants to refuse-burning systems. At least one of these
fifteen systems was identified as being a more cost-effective approach to
refuse disposal than is landfill at the present time.
A cost model wfis developed to consider all the major elements
involved in the erection and operation of these refuse-burning systems.
From this systematic analysis, two new-plant configurations were extracted
and subjected to detailed engineering analysis. Cost estimates were iter-
atively computed for the resulting preliminary designs.
The two favored steam generator configurations, the end product
of the system analysis, represented considerably different levels of cost-
effectiveness. However, the system predicted to have the higher disposal
cost required more conservative treatment because of performance uncer-
tainties associated with its more advanced design.
In line with the latter problem and extending to all aspects of the
study where technical knowledge-gaps were recognized, research and develop-
ment requirements were iteznized. These were analyzed and integrated into
discrete task packages. Final organization of these R&D elements took the
form of two 5-year plans, each structured to accommodate a specific level
of effort.
C.
SCOPE OF THE PRESENT STUDY
The technical and economic analysis of a wide range of refuse
or combined firing possibilities performed on the initial program showed
that the cost effectiveness of a preferred system is dependent on a great
many factors and constraints operating within any specific metropolitan
area under consideration. The purpose of the present study was to apply
these generalized results to two specific and representative metropolitan
areas where sulfur oxides and particulate pollution and refuse disposal
are problems, and evaluate the influence of the specific local conditions
and constraints on the system choice and feasibility. Municipalities
interested in a cooperative effort were to be selected, and specific cost-
benefit advantage to the municipality.deterznined. Beneficial uses of energy
recovery from refuse incineration other than power generation were also
to be considered. It was. expected that favorable results from these studies
would not only suggest implementation in the specific localities studied, but
would serve to arouse interest in other metropolitan areas with similar problems.
Attainment of these objectives would)nvolve the acquisition and
analysis of information within the case areas pertaining to refuse management
and inventory characteristics, steam generation requirements, and urban
layout. Specific steam generator systems and sites were then to be proposed
1-2
-------
and design packages submitted for review by the principals within the two'
selected municipalities. The responses elicited would then help guide the
preparation of the present document, which offers the recommendations
deemed potentially most beneficial to the municipalities concerned.
D.
PROGRAM SUMMAR Y
1.
Selection of Metropolitan Sites
The selection of the two metropolitan case study areas
was limited to those among the first twenty-five cities ranked in terms of
S02 problem severity shown in Table 1. This tabulation was extracted
from Reference 2. Most of the cities listed also suffer from the associated
problem of particulate air pollution. Six of the cities were identified as
being faced with moderate to acute waste management problems. Local
authorities were contacted in these six areas and working arrangements
established with two. These were the cities of Philadelphia, Pennsylvania,
and Cleveland, Ohio. The respective utilities involved were the Philadelphia
Electric Co. and the Cleveland Electric Illuminating Co. The key personnel
of these organizations who furnished inputs to this study are named in the
Acknowledgement Section of this report.
2.
Data Acquisition and Analysis
As a resUlt of the liaison established in the two cities,
information was provided on the following factors.
.
.
.
Demographic trends
Waste collection rates by districts
Waste composition and characteristics
Waste management practices and policies
Utility-grade steam generator inventories,
including design specifications and station
site s
Future energy and waste disposal requirements
and related planning.
.
.
.
This information was systematically analyzed and projections developed by
Electronic Data Processing (EDP) techniques on solid waste trends pertaining
to collection rates, composition and fuel value, and combustion characteristics.
Opportunities for establishing refuse-firing steam generators within reasonable
reach of the refuse collection systems were then explored. This was condi-
tioned by the decision to locate power plants at shore sites of water bodies
within or adjacent to the cities to satisfy cooling water requirements. Both
city utilities, however, operate district heating networks, the steam plants
of which are not only centrally located but require only modest quantities of
1-3
-------
TABLE 1
SMSA's RANKED ~Y SEVERITY OF S02 PROBLEM
(AS OF 1968)
SMSA
New York
Chicago
Philadelphia, Pa-NJ
Newark
St. Louis,. Mo - III
Paterson -Clifton -Pas saic
Washington, Md- Va
Jersey City
Providence -Pawtucket, Ri-Mass
Reading
Allentown - Bethlehem - Eas ton,
Bo s ton
Lancaster
Cleveland
York
Pa-NJ
Wilmington,
Baltimore
Bridgeport
Cincinnati,
Akron
Del-NJ
Ohio-Ky
Canton
New Haven
Worcester
Gary-Hammond-E.
Pittsburgh
Chicago
1-4
S02
Rank
1
2
3
4
5
6
6
8
9
10
11
12
13
14
14
16
17
18
- 19
20
20
20
20
24
25
-------
cooling water. Recommendation of refuse-fired steam plants for both cities
was thus indicated, although it was recognized that steam demand would per-
mit only the firing of a fraction of the total refuse collected in either city.
The solution to this has been to propose a combination of steam and turbo-
electric plants, setting the refuse rate of the former as high as possible.
3.
Design Recommendations
Specific plant design and performance recommendations
were prepared for each of the cities. The guidelines established on the basic
program (Ref. l) were initially followed (except as noted below), then
modified after the design packages had been reviewed by the city and utility
principals to accommodate local factors. For each city, the design re-
commendation consisted of one district heating plant (100% refuse fired)
and one turbo-electric plant of the Case 3 type. * Key information on these
systems is shown in Table 2.
In neither city was an opportunity for the retrofit approach
recognized. In Cleveland, this was due to the prevalent use of slag- tap
boilers, which are poor retrofit candidates because of structural lay-out
and the potential for slag solidification when mixed refuse/ coal fuels are
fired. In Philadelphia, the utility company suggested that the retrofit
approach would not be compatible with their operations.
In preparing the design packages, one notable deviation
from the design guidelines established on the initial program was considered
advisable. Thi s concerned the manner in which refuse is stored and charged
to the furnace. In Reference I, it is recommended that charging be done by
conveyor-belt systems, utilizing live-bottom, high-profile storage structures.
Because such a technique has not yet been actually tried on refuse, it was
decided that the more conservative, and costly, storage pit and crane method
be employed. This required that current cost data on components of such
systems be collected and inserted into the existing cost model.
Conversion of boilers to fire low sulfur oil is the present
trend, particularly in Philadelphia. This can be done at much lower capital
costs than in providing SOZ-removal equipment for f:oal-fired furnaces. As
a result, fuel costs have sIgnificantly increased, posing long term economic
penalties for power consumers. On the present study, coal has therefore been
the fuel of choice. Appropriate gas cleaning equipment for both 502 and par-
ticulate control (90% and 99% efficiencies, respectively) has been specified
and cos ted.
* As described in detail in Reference 1, a design wherein refuse is
fired on agitating grates in a feedwater heater or "economizer" that
serves a separately situated steam generator fired with fossil fuel.
1-5
-------
TABLE 2
CHARACTERISTICS OF PROPOSED STEAM GENERATORS
Philadel phia
Cleveland
District Heating Plant
Refuse Rate, tpd
Plant Factor, o/c
1,400 400
315,000 90,000
270,000 75,000
225 170
450 425
80 80
Steam Production, Ib/hr
Send Out, lb/hr
Steam Pressure, psig
o
Steam Temperature, F
Turbo:- electric Plant
Nameplate Rating, MW
300
200
Refuse Rate, tpd
Steam Conditions, pSig/oF/oF*
1,500
936
2400/1000/1000
1800/1000/1000
Energy Input from Refuse, o/c
19.4
80
17.4
Plant Factor, o/c
80
. *Turbine throttle pressure, psig/Superheat temperature, of/Reheat
temperature, of
1-6
-------
4.
Cost Analysis
With certain notable exceptions, the development of system
ca-pital, operating and maintenance, and refuse disposal costs basically
followed the approach outlined in Reference 1. The cost model provided
in that document was updated to compensate for cost escalations. A
number of cost model functions were modified to better represent cost
situations operating in the cities studied. Several new functions were
added. to accommodate system components that were not previously provided.
Capital costs derived include land and land rights, structures
and improvements, boiler plant equipment (boiler, water treatment equip-
ment, pumps, piping, coal handling equipment, residue handling equipment,
and stacks), turbine-generator equipment (if any). accessory electrical
equipment, miscellaneous plant equipment (including turbine room cranes
and fire fighting equipment), air pollution control (APC) equipment, and
refuse handling equipment and facilities.
Capital costs were annualized on the basis of utility
rather than municipal ownership. This was done because of the less
favorable rate of the former and not to suggest where proper proprietorship
belongs. Operating and maintenance costs (including costs of water and
residue disposal) were calculated and added to annualized capital costs
to furnish total annual costs. Product credit was then determined, using
different approaches fo! district heating and turbo- electric systems, and
subtracted from total annual costs. The difference was then distributed over
the quantity of refuse fired per year (80% plant factor) to arrive at unit
disposal cost. The culmination of this analysis was the derivation of costs
for transporting refuse to the sites selected for the refuse-fired steam
generators. This cost was added to disposal cost, the combined trans-
poration-disposal costs thus serving as the primary reference point for
comparing the recommended system with methodology now in use.
Assignment of product credit must take into account the
nature of the product demand that is to be satisfied by a new installation
when it is added to an already operating complex of steam generators.
In the case of the refuse-fired turbo-electric system, it was reasonable
to assume that it would be built to satisfy a load in excess of the capacity
of the existing system, since power demand is increasing rapidly. In this
situation the proper product credit would be the cost of generating the same
amount of electricity by a conventionally-fired power station of identical
capacity and plant factor and one that was built under the same cost con-
ditions as the refuse-fired system. This required of course that complete
costs be developed for both the conventional and the refuse-fired power
plants.
1-7
-------
In the case of district heating plants, a different method of
product credit assignment was necessary. This resulted from the fact
that in both cit ies increased steam demand is not expected. Firing a new
steam plant would therefore necessitate that the older ones be operated at
reduced plant factors. Thus product credit would consist only of the fuel
saved and the operating and maintenance (O&M) costs displaced in the
older units wl).en operating the refuse-fired systems.
5.
Cost Analysis Results
Most of the refuse collected in the City of Philadelphia is
disposed of in a system of strategically well-located incinerators. In July
1969, it was estimated that this operation cost $7. 35/ton. On the present
study, it was estimated that the transportation cost associated with incin-
eration amounts to $1. 81 /ton. This suggests that current combined trans-
portation and disposal cost are something higher than the'sum ($9. 16 /ton)
of these two costs.
The disposal cost for the district heating plant (see Table 2)
recommended was calculated and found to range between $3.20 and $5. 36/ton,
depending on the steam generating costs ($l. 00 to $0.55/10 Ib steam) of the
existing station that it would displace. The cost for transporting refuse to
this new plant was calculated to be $1. 93/ton, bringing overall costs to
between $5. 13 and $7. 29/ton.
In the case of the recommended turbo-electric plant,
disposal costs were estimated to range between zero and $1. 75/ton as the
cost of the fossil fu~l (low sulfur oil) displaced by refuse ranged between
$0.44 and $0.40/10 Btu's. Refuse transportation cost for this plant was
estimated to be $3. 30/ton, bringing the overall charge between $3.30 and
$5. 05 /ton.
In Cleveland, landfill disposal is the favored tool of solid
waste management. The city currently seeks new landfill sites and aims
to reach these through the use of transfer stations. It has been estimated
that the combined cost for transportation and disposal by this new arrangement
will come to about $7. OO/ton. The equivalent costs for hauling to and dis-
posing of refuse at the district heating plant recommended were estimated
to be $10.80 /ton, including $2. 80/ton for transportation. For the turbo-
electric system this cost was found to be only $4. 53/ton including $2. 62/ton
for transportation. The relatively high refuse handling cost associated with
the district heating installation resulted not only from the unfavorable method
of product credit assignment discussed above, but a well-below optimum
refuse charging rate. This was unavoidable because of the steam demand
situation in Cleveland.
1-8
-------
An analysis conducted on the present study that was not
treated on the previous program involved the effect on costs of oversizing
a plant so as to accommodate future increases in refuse production. Two
approaches were analyzed and are discussed in Appendix A. It can be
seen from this analysis that if a plant is built intentionally oversized, the
refuse deficit should be made up by firing supplemental fos sil fuel rather
than by turning down the plant.
On the basis of the foregoing considerations, design
packages were prepared for each of the municipalities and presented to the
principals for review and comments. Conferences were then held in each
city; a number of changes were suggested by both city and utility officials.
These largely dealt with local costing practices, although site changes and
modification of plant capacities were also requested. The design recommen-
dation contained in the present report reflect essentially all of the resolutions
reached in these reviews.
6.
Potential Reduction of Air Pollutants
The possible significance to air pollution burdens of
using refuse as a partial substitute for fossil fuels was also explored.
Based on best estimates as to the type of fossil fuel that would be dis-
placed and the pollutant generation rates that would probably be en-
countered, calculations were performed. The results, which indicate
that only modest air purification benefits are available in substituting
refuse for fossil fuels that, themselves, have been specified in order to
reduce pollutant emis sions, can be tabulated as follows:
ESTIMATED AIR POLLUTION REDUCTIONS
FROM SUBSTITUTING REFUSE FOR FOSSIL FUELS
City
Fuel Displaced
by Refus e
Refuse Fired,
6
10 tpy
Reduction in Emissions, tpy
Particulates (1)
Oil (0.5% S)
Coal (1. 0% S,
10% Ash)
. (1 )Air pollution control (APC)
text.
Philadelphia
Cleveland
0.875
0.393
S02
1000
590
W /0 APC
With APC
4,125
420
41
equipment efficiency set at 99%; also see following
In this analysis, it was assumed for the Philadelphia case
that, because of its low ash content, oil would be fired without the use of
APC equipment while refuse would only be fired if such equipment were
installed. In the Cleveland case, the comparison was arbitrarily made
on the basis of zero and 99% dust control for both coals and refuse.
1-9
-------
II.
THE PHILADELPHIA STUDY
A.
WASTE MANAGEMENT OPERATIONS
The Sanitation Division of the City of Philadelphia I s Department
of Streets has cognizance of that City's waste management operations.
According to its charter, _the Sanitation Division is charged with six
responsibilities, two of which are:
.
"Collection of ashes, rubbish and garbage from
households and retail establishments II
.
"Disposal of all refuse removed by city forces
by operation of incinerators and sanitary land-
fills. Also the disposal of combustible refuse
collected by private contractors and industrial
establishments and delivered to incinerators. II
Fulfillment of these mandates is being accomplished by a
collection system which functions within six sanitation areas, each of
which is divided into two sanitation districts. Disposal is effected largely
through the operation of six incinerators. The districting and incinerator
locations are shown in Figure 1.
During the one year period from 1 July 1969 to 30 June 1970,
the incinerator system fired 683, 711 tons of refuse. Of this quantity,
12.4% was combustible refuse delivered by private operators and a small
amount of special collection garbage brought in by city trucks. Another
200,245 tons of refuse was disposed of in landfill sites. It was estimated
that about 20% of the landfill material was refuse of the oversized type.
Disposal costs, as of 30 June 1969, were estimated to be
$7. 35 /ton by incineration and $1. 74/ton by landfill. By definition, these
costs do not of course include transportation, which in the case of landfill
operations is substantial.
, .
A third method of disposal used in Philadelphia is the outhaul
of garbage to swine raisers. The demand, however, is not sufficient to
absorb the entire production of garbage in Philadelphia. The districts in
which separate garbage collections are now made include: West Philadelphia
"A", West Philadelphia "B" (excluding Eastwick), South Philadelphia,
Manayunk, Germantown, Logan, Frankford, and Lower Tacony. The slop
market has steadily declined with time due to the displacement of pig
farming by rural urbanization. In the last decade, garbage deliveries to
II-I
-------
\
tot
\
INCINERATOR DESIGNATIONS
~
1 ... BART:RAM
2 ... SOUTHEAST
3 ... EAST' CENTRAL
4 ... NOR1:HWEST
5 ... HARROW GA TE
6 - NORTHEAST
DELAWARE
RIVER Miles
o 1 2 3
t:::=::f:::::::
PHILADELPHIA SANITATION AREAS
AND INGINERATOR SYSTEM
II-2
Figure 1
-------
farmers dropped an estimated 420/0. At the present rate of decline, the market
could become nonexistent in another 12 years. Another factor which may
make this operation even more short lived is that it requires subsidization
by the City of Philadelphia. Elimination of the slop program has been fre-
quently considered by city officials in recent years. It was therefore considered
appropriate for present purposes to assume that all garbage now being
collected separately would eventually be mixed with other refuse and be
put into the 1;"egular disposal sys tern.
B.
REFUSE INVENTORY AND COMPOSITION PROJECTIONS
1.
Refuse Quantities
Collection and disposal statistics for Philadelphia are
shown in Table 3 for the period 1 July 1969 to 30 June 1970. Included are
all municipal operations involving either the collection or the disposal of
solid wastes. Thus, data on solid wastes transported by private haulers
for disposal in privately owned facilities is not included. This category
is essentially of the commercial/industrial type. It will be noted, how-
ever, that some 8.2% of the total solid waste handled by the city is
commercial/industrial. Ninety percent of this material is fired in two
of the city's six incinerators; these are the -Bartram and the Southeastern
Incinerators. The small amount of garbage brought in from special col-
lections (in response to complaints, etc.) is also fired in the incinerators.
The amounts of refuse collected per unit area vary widely
in Philadelphia. This can be seen from Table 4, which shows refuse den-
sities by districts. Homogenous distributions of the amounts of refuse
collected within each district have been as sumed. It is recognized of
course that large non-residential tracts exist, particularly in West
Philadelphia B, South Philadelphia, and the Fairmont Park areas of West
Philadelphia A and the Columbia District. The zone of greatest refuse
output density is still obviously the block of five districts comprised of
West Philadelphia A, Columbia, Fairhill, Germantown and Logan.
The quantities of refuse handled by municipal forces
over the past decade and projected for the next decade are shown in
Figure 2. This graph was prepared by the Sanitation Division of the
Department of Streets and incorporated in an internal report of the City
of Philadelphia. The data show the decrease of garbage collections for
the slop market discussed earlier, and a decline in the amounts of commercial/
industrial solid wastes being hauled to city incinerators. The latter effect
does not mean that les s industrial/commercial solid waste is being collected,
but merely that private haulers are taking more of their collections to privately
owned disposal sites. Similarly, the drop in garbage collection rates does
not mean that the amount of garbage put out has decreased to that extent.
It merely reflects the shrinking of the slop market and that separate garbage
collections are giving way to mixed collections, the latter being disposed of
in incinerators or landfills.
[,
I
TI-3
-------
TABLE 3
PHILADELPHIA REFUSE COLLECTION/DISPOSAL
STATISTICS BY DISTRICTS
(1 July 1969 to 30 June 1970)
Disposal Method, tpy
City Animal
Owned Contracted
District/ Source Incinerators Landfills Landfills F d 1,2 Totals
ee ,
West Phila. A 45,926 12,274 45,613 16,270 120,083
West Phila. B 51,169 0 0 7,040 58,209
Central City 27, 756 6,424 0 0 34,180
South Phila. 78, 983 22,025 5,122 0 106,130
Columbia 76,316 84 3,071 0 79,471
Fairhill 64,611 2,493 2,937 0 70,041
Logan 50,242 304 529 14,1 30 65.205
Germantown 56,396 1,939 1 J 239 16,310 75,884
Manayunk 42,754 1, 755 942 12,440 57,891
Frankford 55,578 84 6,572 15,560 77, 794
Upper Tacony 33,740 0 86,534 0 120,274
Lower Tacony 15,213 0 304 4,250 19, 767
Spec. Garb. CollIns. 5,160 0 0 0 5,160
Comm'I/Ind.2 79,867 0 0 0 74,867
Totals 683, 711 47, 382 152,863 86,000 969,956
o/c of overall total 70.5 4.9 15. 7 8.9 100
1 District garbage data are proportioned estimates. In West Phila. B, allowance
was made for Eastwick Section, where separate garbage collections are not
made.
2Collected by private haulers.
II-4
-------
TABLE 4
PHILADELPHIA REFUSE DENSITIES
BY DISTRICTSI
Total Solid District Refuse
District Waste Collected, tpy Area, sq. mi. Density, tpd/sq. ml.
West Phila. A 120,083 9.5 34.6
West Phila. B 58,209 15.4 10.4
Central City 34,180 4.4 21. 3
South Phila. 106,130 13.1 22.2 \
Columbia 79,471 7.1 30.7
Fairhill 70,041 5. 7 33.7
Lo gan 65,205 6.9 25.9
Germantown 75,884 7.1 29.3
Manayunk 57,891 15.6 10.2
Frankford 77,794 10.3 20.7
Upper Tacony 120,274 33.2 9.9
Lower Tacony 19, 767 7.6 7.1
Entire City 884,929 135.9 17.8
1 Based on collections for the period 1 July 1969 to 30 June 1970 and
excluding commercia1/ industrial and special garbage collections.
1I-5
-------
1,200 RECORDED PROJECTED
I 'f.C.
~ p..S rt ~'
I 501.-1))
ort~1.-
I ~
900 I
H I
;Ij I
Q
~I
H I
~
~
'-:: 600 I
~
0 I
H
..., I
0
.-.
I
300 I
COMM'L/IND. SQLID WASTES
I TO CITY INCINERATORS
I GARBAGE COLLEC TED FOR SLOP
I
0
-
1960 1965 1970 1975 1980
Year
REFUSE COLLEC TION RATES IN PHILADELPHIA -
RECORDED AND PROJECTED
Figure 2
II-6
-------
Figure 2 also shows an erratic trend in total was te dis-
posal, which actually reflects a slight net drop over the ten year period.
This is because the rate of decline in commercial/industrial receipts
at the incinerators has been so much greater than the rate of increase
in other urban collections (by far the larger fraction) as to create a small
decline in the overall disposal rate. If the industrial/ commercial frac-
tion is extracted from these data, an average increase of 1. 39%/year
for other urban refuse collections is found.
This is considerably lower than the 3. O%/year predicted
for the nation on the initial Envirogenics I program. It will be recalled,
however, that this rate involves two factors: (1) a per capita refuse
production increase of 1. 5%/year, and (2) a 1. 5% increase in the national
population. The population in Philadelphia decreased during the period
1960-1970 from 2,002,512 to l, 948, 609 according to Bureau of Census
figures. This represents an annual population drop of 0.27%. If this
negative rate is combined with the expected rate of increase in the refuse
collected per capita (1. 5%/year), the resultant estimated increase in
domestic refuse collections for 1970 would be 1. 23%. This compares rea-
sonably well with the 1. 39% actually observed.
It will be noted in Figure 2, that the changes in collection
rates projected by Philadelphia I s Sanitation Division for the present decade
do not appear to be consistent with those of the.previous decade:
PROJECTED AND ACTUAL PHILADELPHIA
REFUSE HANDLING RATE CHANGES
Decade of the Sixtie s
(Recorded)
Decade of the Seventie s
(Projected)
Change in Urban 1
Refuse Collections,
%/year
1. 39
2.06
Change in Commer-
cial/Industrial Solid
Waste Receipts at City
Incinerators, %/year
-9.56
-0.69
Change in Garbage
Collections for Farm
Consumers, %/year
-5.09
-2.00
Chang e in Total Quan-
tities of Solid Waste
Handled by City Forces
and/or Facilities and
City Contracts, %/year
-0.30
2.00
lIncluding garbage for farm use but excluding commercial/industrial.
11-7
-------
What is actually involved is quite plausible. During the
previous decade a sharp decline in commercial/industrial solid waste
. receipts cancelled the normal increase in other urban refuse collections
so that the total waste handled remained about even. In the present decade,
however, the Sanitation Division policies regarding incinerator access by
private haulers are expected to level out the receipt rates of commercial/
industrial waste material. This will then result in an upward trend in the
curve of total solid waste collected, which now will reflect the increase in
other urban collections. It is questionable, however, whether the urban
collection rate would increase from 1. 39% to Z. 06%/year.
In the preceding discus sion, the rate of change in the
quantity of garbage collected for farm use was not considered. This is
because this operation has no influence on the other rates. The total
solid waste collection rate and the rate at which urban refuse is collected
involve all the garbage that is hauled. These rates are therefore insen-
sitive to the manner in which the garbage is ultimately disposed of or
recycled. In terms of firing refuse in steam generators, however, this
factor must be taken into account. Obviously, any garbage taken to farm
users must be excluded in considering the quantities of refuse that will be
available for firing in boilers.
A twenty-year projection of the quantities of refuse fuel
that will be available in Philadelphia from city managed sources is shown
in Figure 3. The projections for commercial/industrial solid waste receipts
and garbage hauled to farms made by the Sanitation Division have been
observed. The rate of increase in urban collections has, however, been
based on that (1. 39%/year) recorded for the previous decade. It should be
mentioned that the amount of slop garbage collected by 1980 will have
dropped to about 50,000 tpy. This is probably approaching the level where
the practice could well be discontinued as economically unattractive.
2.
Refuse Composition
Establishment of the composition of Philadelphia fuel-
refuse is complicated by the fact that two types exist in the various districts.
That is, urban refuse with and without garbage is being collected. Because
the duration of this situation is uncertain and because the two types would
be difficult to isolate in disposal operations, the use of composite data
appeared to be most practical. Figure 4, showing compositional projections
for the period 1970 - 1990, has been prepared on that basis. The data were
obtained using the compositional change derivations developed on the orig-
inal Envirogenics program and the Philadelphia disposal trends previously
dis cus sed.
11-8
-------
1200
1000
~
~ 800
C'i
0
....
'"d
v
~
~ 600
ell
:r:
(/)
(!)
~
(/)
ell
~
'"d 400
....
0
U')
200
Commercial/Industrial Solid Wastes
o
1970
1975
1980
Year
1985
1990
PROJECTED PHILADELPHIA BOILER
REFUSE -FUEL INVENTORIES
Figure 3
Il- 9
-------
.40
b~
.
..
.~
g 10
....
t 9
CIS
t: 8
..
!::
Q)
!::
o
At
S
o
U
50
PAPER
30
2.0
GARDEN WASTES
GLASS
7
6
RESIDUAL
5
4
3
z
1
1970
1985
1990
,1 9.75
1980
Year
PROJECTED COMPOSITla>NAL CHANGES IN
PHILADELPHIA MIXEP REFUSE
1I- 10
F igu,:re 4
-------
C.
FUEL CHARACTERISTICS OF PHILADELPHIA REFUSE
1.
Heating Value
Using the compositional values discussed in the previous
section and the component calorific values adopted on the previous Envir-
ogenics program, higher heating values (HHV) were calculated for mixed
Philadelphia refuse. These are shown in Figure 5 for the period 1970-1990.
An increase in the projected HHV for refuse results because the predicted
compositional changes (Figure 4) involve increases in the levels of high
I-ll-IV constituents, paper and plastics, and decreases in low HHV components,
such as glass, metals, and garbage.
Work is being done at the Drexel Institute to determine the
calorific value of refuse fired at certain of the City's incinerators. In a
private communication, Dr. R. Schoenberger of that institute advised that
a current typical value would be about 5500 Btu/lb. The material tested
was, however, garbage-free.
2.
Combustion Calculations
In developing preliminary designs of combination-fired
systems, some specific refuse composition must be assumed. It is
recognized that the design fuel would not be valid except for a compara-
tively short period of time. It would, however, furnish a reference point
for making adjustments in firing rates, etc., when fuel characteristics
are significantly different. For the purposes of the present .study, the
refuse composition projected for 1980 was used. It is tabulated below for
easy reference.
PROJECTED 1980 COMPOSITION (WT-%)
OF MIXED PHILADELPHIA REFUSE
Garden
Garbage Plastic Wastes Glass Metals
Paper Residual
Commercial/
Indus trial
5. 9
3. 7
12.0
11. 2
9.2
44.8
6.0
7.2
The heating value, as shown in the last figure, will be about 4700 Btu/lb.
Using the same guidelines as observed on the previous program, the
following ultimate analysis was computed.
ll- 11
-------
5500
5000
,.c
-c
-
::S
....
~
..
-
?-
::r:
::r:
-
C1)
::S
Cd
?- 4500
Of)
~
....
....
lIS
C1)
::r;
4000
1970
1975
1980
1985
1990
Year
PROJECTED INCREASE IN HEATING VALUE OF MIXED
PHILADELPHIA REFUSE (AS RECEIVED BASIS)
Fi.gure 5
li- 12
-------
PROJ;ECTED 1980 ULTIMATE ANALYSIS
OF MIXED PHILADELPHIA REFUSE,
Component Wt- %
H20 17.2
C 26.8
H 3. 5
o 22.9
N 0.4
S 0.2
,4 Inert 29.0
100.0
Combustion air, flue gas, and steam generator efficiency
were then calculated. The results are shown in Tables 5, 6, and 7. It
will be noted in Table 7 that steam generator efficiencies have been cal-
culated on the basis of three different flue gas exit-temperatures. These
values match the flue gas temperatures of the various boiler designs
described in the report of the previous program (Reference 1).
D.
UTILITY STEAM GENERATION OPERATIONS
1.
Steam Generator Inventory
The Philadelphia Electric Co. (P. E. ) provides electrical
power and some heating steam for the City., The P. E. inventory of power
stations is widely distributed. Within the city limits, however, there are
four power stations and two steam plants. Their locations are shown in
Figure 6. One of the units at the Schuylkill Plant is equipped with a topping
turbine. It is therefore linked with the two downtqwn steam plants in the
Center City heating steam loop. This circuitry is discussed in a later section.
The effective electrical capacity of the power stations located
within the city limits is about a third that of the entire P. E. system, which
includes nine other stations, all well outside the city limits. The Peach
Bottom atomic station, for example, is almost 60 miles from downtown
Philadelphia. The basic characteristics of the four power stations located
within the city limits are summarized in Table 8. The characteristics of
the two steam plants, Willow and Edison, are shown in Table 9. Units 23
and 24 of the Schuylkill Station appear in both tables. This is because they
are coupled to a topping turbine and thus produce both electricity and heating
II-13
-------
TABLE 5
COMBUSTION GAS REQUIREMENTS BASED
ON PROJECTED 1980 PHILADELPHIA
MIXED REFUSE COMPOSITION
Combustion Gas Requirement,
lb/lb Refuse
Constituent
Oxygen Dry Air
O. 714 3.077
0.280 1.207
0.002 0.009
0.013 0.056
1.009 4.349
-.229 -0. 987
O. 780 3.362
1 . 1 70 5.042
0.390 1 . 681
C
H
S
Metal
Oxygen
Total Required, Stoichiometric
Total Required, 500/c Excess Gas
Excess Gas
1I- 14
-------
TABLE 6
PRODUCTS OF REFUSE COMBUSTION
BASED ON PROJECTED 1980 PHILADELPHIA MIXED REFUSE
COMPOSITION
- Refuse HZ
- Refuse H20
- Combustion Airl
Gas formed per Ib Refuse Vol-o/e
Lb Mol Lb Dry Basis
0.02Z 0.983 lZ.8
(0.030) (0.544
0.018 0.315
0.010 O. 1 72
0.003 0.057
0.001 0.004 0.03
0.012 0.390 7.0
Constituent
COZ
H20
SOZ
0z (excess)
NZ
Total Air N
O. 138 3.876
80.23
0.001 0.004
0.202 5.801
0.17Z 5.Z57
Refuse N
Total Flue Gas (wet)
Total Flue Gas (dry)
1.
Based on standard (60% RH @ 900 F) of American
Boilers Manufacturers Association.
1I- 15
-------
TABLE 7
EFFICIENCY OF STEAM GENERATOR FIRING PHILADELPHIA
MIXED REFUSE OF COMPOSITION
P ROJEC TED FOR 1980
Fuel Value Heat Losses at Various
Flue Gas Exit Temperatures,
450uF Btu/lb of Fuel (o/c of HHV)
Item 500uF 575uF
1. Dry Gas 467(9.79) 530(11.11) 625 (13.10)
2. H20 in Refuse 209 (4.38) 213 (4.46) 219 (4.59)
3. From H2 Combustion 383(8.03) 390 (8.18) 402 (8.43)
4. H20 in Air 12 (0.25) 1 3 (0. 27) 16 (0.34)
5. Unburned Gas 4 (0.08) 4 (0.08) 4 (0.08)
6. Unburned Residue 107 (2.24) 107 (2.24) 107 (2.24)
7. Sensible Heat, Residue 47 (0.98) 47 (0.98) 47 (0.98)
8. Unburned Fly Ash 40 (0.84) 40 (0.84) 40 (0.84)
9. Sensible Heat in Fly Ash 5 (0.10) 5 (0.10) 6 (0.13)
Subtotal 1274 (26.69) 1349 (28.26) 1466 (30.73)
10. Radiation (0.20) (0.20) (0.20)
11. Unmeasured (0.50) (0.50) (0. 50)
12. Manufacturer's Margin (1.00) (1.00) (1. 00)
Total o/c Heat Loss 28.39 29.96 32.43
Stearn Gen. Efficiency 71. 61 70.04 67.57
NOTE: Fuel Value (HHV) = 4770 Btu/lb; Combustion Air Inlet
Temperature = 800F (600/c R. H.).
II- 16
-------
1',
, ,
I '
. ,
I ". '/'.'....
/ ' .I "
/ ',1 ",
. ,
I '....,
, ,
I '
,
/ "
& '
0<$.>
?"
v,
'<
~
<
-1,/' >
'"
., ,/..
..,~
,..,
/'
)
I
I
/
'-
,;
"
)
/
..... /
'./'
PHILADELPHIA
./
,./
./
,,/
/
/'
,/
/'
./
('
,.
..... .
" ""',
('
I
~
..."
"I
/
J
I
I
I
r
.I
I
/ ,. '""\,
r' '
\..-.-'
'')
;/
,.. /'
<'
"
)
~.
r'
\
\
(, .
, )
"".-'
/",
,,.' """,?
I ....
/ '\
/ "'-'~
/ ;
./
/ \
( \
\
I
I
I
/
/
/
PLANT IDENTIFICATIONS
1. SOGTI1"WARK POWER
STA.
2. SCHUYLKILL POWER "-
STEAM PLAI'JT
3. EDIS01'1 STEAM PLANT
L~. WILLOW S'_-'EAM PLANT
S. DELAWARE POWER S':'A.
6. RICHMOND POW EB. S'..'A.
LOCATIONS OF UTILITY POW:i:R AI:D S7,EAM PLA:~:'S
IN PHILADELPHIA
II- 1 ?
Figure 6
-------
TAB~E 8
UTILITY POWER BOILER INVENTORY WITHIN THE
CITY OF PHILADELPHIA
Station Boiler Pressure, Terngerature,
(Effective Capacityl, MW) No. psig F Fuel
Southwark (462) 11,12 925 900 Pulv. coal/
oil
21,22 925 900 Pul v. coal/
oil
Schuylkill (335) 1 2475 1050 oil
2,3 225 545 oil2
11-20 225 503 oil2
23,24 1350 910 Pulv. coal/
oil
Delaware (422) 13-24 267 637 "12
01
71 -81 1875 1000 Pulv. coal/
oil
Richmond (464) 49-52 400 703 '12
01
57-60 400 703 '12
01
63-64 1335 950 Pulv. coal/
oil
65,66 425 850 Pulv. coal/
oil
1 Effective capacity for 75o/c of the year.
2Converted from coal firing.
11-18
-------
~ ~A 3:"E ~
UTILITY STEAM PLANT INVENTORY WITffiN THE
CITY OF PffiLADELPHIA
Boiler Rated Steam Prod. , Pressure, Tem~erature,
Station No. 103 1b/hr psig F Fuel
Edison 1,2 216 ea. 205 435 oil
Willow 1-3 125 ea. 200 438 °11
01
4 170 180 434 011
01
5 170 190 430 oil 1
6 170 180 434 011
01
H
H
I 2
...... Schuylkill 23,24 600 ea. 225 450 Pu1 v. coal/
~ oil
1 Converted from coal firing.
20utput of topping turbine.
"-
-------
steam. The quantity of steam sent out from these units can be controlled
by using a low pressure 20 MW turbine (throttle condition - 200 psig, 4400 F)
in tandem with the topping turbine. Thus, any steam not required for the
city heating system can be diverted into this second turbine to produce
electricity. Over the past five years, the Schuylkill has accounted for an
average of 64.4% of the district heating steam sent out. All three plants
divert about 15% of their production to heat feed water and drive auxiliary
plant machinery.
It will be noted in Tables 8 and 9 that all of the units are,
or have a capability of, firing oil. This results from an effort on the part of
P. E. to shift completely over to (low sulfur) oil, an objective that is now
nearly fulfilled. The reason for this of course is to comply with air pollu-
tion abatement regulations. A problem this on-going strategy presented to
the present study was the current instability of fuel costs. This matter
is considered in greater detail in a later section.
2.
Effect of Firing Refuse on Pollution Burden
Because of its present predominant use in utility-class
boilers in Philadelphia, low sulfur (-0.5% S) oil would likely be the fuel
that would in~-ffect be substituted for if refuse were also fired in boilers.
The particulates and SO? pollutants emitted by refuse would be about a
fifth and a half, respechvely, that emitted by low sulfur oil, on an
equivalent energy basis. * This estimate is based on the air pollution
data presented in Reference 1. It also as sumes that no flue gas cleaning
would be practiced when oil is fired but that a refuse-fired steam generator
would incorporate an electrostatic precipitator having an efficiency of
99%.
A ton of fired refuse will produce, on the average, 2. 3
lb S02, while a quarter ton of oil (0.5% S) -- the equivalent in available
energy-- will produce about 4. 9 lb of S02' Thus, if all the refuse pre-
sently collected by city forces (875,000 tpy) were substituted for low
sulfur oil, the annual output of S02 would be reduced by slightly over
1000 tons.
*Assuming,for refuse and oil, fuel values of 4770 and 15,000 Btu/lb
and boiler efficiencies of 70% and 88%, respectively, this represents
an available energy ratio of about one to four.
II- 20
-------
In terms of particulates, refuse fired on agitating grates
loads the flue gas with about 1. 3 gr /SCFD of fly ash, while oil produces a
loading of only about O. 1 gr /SCFD. Differences in exces s air requirements
considered, oil produces al?out 2 1/2 times as much flue gas as does refuse.
This, taken together with a refuse - oil available energy ratio of 1: 4, suggests
that refuse will produce 20 times as much fly ash as does oil in 4eveloping the
same amount of steam enthalpy. Typically, however, a refuse-fired system
will be equipped with gas cleaning equipment while an oil fircid boiler would
not. In the former case, an electrostatic precipitator having an efficiency
of 99% would be reasonable to expect. In this situation, the refuse-fired
system would produce about 20% the particulates that an uncontrolled oil-
fired boiler would that produced the same amount of steam energy. This
would represent a reduction of o. 96 lb of particulates for every ton of refuse
fired in replacement of oil, an air pollution burden relief of about 420 tons
per year, based on present refuse collection rates (875,000 tpy).
It should be pointed out that, in the foregoing discussion,
no account has been taken of the fact that considerable refuse is presently
being fired in conventional incinerators in Philadelphia. Although the overall
dust control efficiency of this system of incinerators is not known, it is said
to be considerably less than 99%. An obvious additional benefit would thus
result from firing the same refuse in steam generators equipped with high
efficiency gas cleaners.
It will be noted that the pollutant reduction estimates
shown here are considerably lower than those developed in Referenc'e 1.
In the latter, older analysis, the data were derived on the basis of high
sulfur (3% S) coal displacement and the use of refuse from the entire
Philadelphia Standard Metropolitan Statistical Area (SMSA). In either case,
however, the air pollution benefits estimated are not great.
3.
Suggested Study Guidelines
During the course of the program a number of very
helpful recommendations and observations were offered by officials of
the P. E. and the City of Philadelphia. These ranged in content from
matters dealing with costing details to the general philosophy of utilizing
refuse-fuel energy in utility operated systems. Because these Philadelphia
organizations will be the ultimate beneficiaries of the present study, their
inputs were incorporated wherever possible. This resulted in changes
being made in the original Envirogenics' cost model to accommodate local
economic factors and in the modification of specific system design features.
It also led to the generation of preliminary design and cost data on refuse-
fired, district steam plants. This was done because of P. E. IS expressed
greater interest in this type of plant over combined-fired turbo-electric
systems.
ll- 21
-------
It will be recalled that the initial Envirogenics study
was essentially addressed to the latter type of boiler, thus the consideration
of district steam plants on the present program could not be approached from
the systematically developed basis that was available in recommending tu-rbo-
electric systems. Of the two types, however, the district steam plant is
much less complex a structure, particularly in terms of configurational
options and the constraints controlling the use of refuse as a fuel. Thus,
the basic design described herein involved a fairly straightforward selection
process, to which the pertinent criteria developed on the earlier program
were applied.
E.
PRELIMINAR Y PLANNING RE COMMENDA TIONS
1.
Overview
In developing the following systems recommendations, it
was necessary to adopt and follow certain general guidelines. These are
itemized below.
a.
Lead Time
The typical period of time elapsed between con-
struction go-ahead and initial service of a conventional power plant is about
seven years. Because of the less conventional nature of refuse-firing
sys terns, 1980 was set as a convenient target date. The refuse characteristics
and quantities projected for that time have been discussed earlier.
b.
System Input
The overall system recommended should be
capable of handling all of the refuse for which the city will be responsible
in 1980 and preferably allow for expanded throughput beyond that date.
The system should, however, comprise more than one plant so that initial
capital cost burdens can be spaced out and so that logistics are manageable.
In order that collection forces will have a reliable disposal operation to
accept their deliveries, a high plant factor will be necessary. This has
been set at 80%, as on the previous Envirogenics. program. During outages,
elements of the existing incinerator /landfill disposal system would be
substituted.
c.
Plant Management
In terms of P. E. and City participation, many
management options can be considered. Attempting to influence the
decisions involving such alternatives is clearly not an objective of the
present program. For costing purposes, however, the capital cost
II- 22
-------
annualization rate selected was that associated with 'utility ownership.
This was done merely in the interest of conservatism. The average
utility annualization rate is usually considerably higher than would be
obtained under municipal ownership.
2.
District Steam Plant
a.
Design Characteristics
The plants Edison, Willow, and Schuylkill pump
steam into an essentially common distribution loop, the highest steam
condition input being from Schuylkill at 225 psig and 4500 F (enthalpy
~ 1235 BtU/lb). The lowest steam demand is of course during the summer
months when the steam send-out is below 400,000 lb/hr, little if any
of which goes into space heating systems.
The Philadelphia Electric Co. has demonstrated
that it is more economical to operate at 100% feedwater make-up than to
attempt recycle of the condensate, which becomes heavily contaminated
by the district heating circuitry. Because the boilers operate at low
steam temperatures, feedwater treatment can be limited to a softening
process rather than deionization, although the boiler must then be blown
down fairly frequently. A final factor influencing design is that Philadelphia I s
district heating requirement will probably not increase significantly with
time, because the central city served will not be involved in much further
growth. Thus, a refuse-firing, district-heating plant can be designed on
the basis of today's needs. If sized to summer demand, such a plant can
be operated at base-load condition all year around, assuming that, of
the three existing plants, only the Willow plant would be fired during the
summer months to fill the northern segment of the stea~ loop and thus
reduce the frictional line losses that would result from single plant input.
A send-out of 130,000 lb/hour would be sufficient to accomplish this.
It was suggested by the P. E. that the refuse-fired
plant have a steam production of no more than 350,000 lb/hour. This is
equivalent to a send-out of about 300,000 lb/hour. This size, however,
involves a refuse input that would probably require the use of three boilers.
By dropping the capacity to about 315,000 1b/hour, two boilers would be
sufficient. Production costs would thus be significantly reduced. In order
to generate steam at a rate of 315,000 lb/hour (send-out ~ 270, 000 lb/hour),
a refuse rate of 1400 tpd would be required. Fuel characteristics would,
as stated earlier, be based on those projected for 1980.
1I-23
-------
The plant would consist of a completely indoor
structure, housing two units in a side-by-side arrangement. Both units
would face upon a common storage pit, which would be separated from
the boilers by a 50-ft fire wall running the full length of the pit.
Overhead cranes would transfer refuse from the
pit to a water-cooled charging chute on each of the units. Stoking would
be promoted by means of a ram or vibratory feeder. In each furnace the
grate would be a three- stage, reciprocating device, the ash from which
would be quenched within the ash pit by water sprays. Combustion air,
50% in excess of stoichiometric, would be drawn from the refuse pit area
so that odor leakage would be minimized. From 60 to 75% of the total
air introduced into each unit would be directed to the underfire and sidefire
jets. This air would first be heated by a tubular air heater to about 3250 F.
Overfire air would be introduced so that the hot combustion gases would
flow back over the bed and tend to dehydrate the material on the first grate
stage. Natural gas burners would be provided, but for start-up and trim-
ming purposes only.
Because of the heterogeneity of the fuel, steam
conditions would be more variable than those experienced in firing fossil
fuel. In the case of turbo-electric plants, such fluctuations are unaccept-
able so that other design arrangements are necessary. However, based
upon European and domestic experience, this variability is regarded as
acceptable for district heating steam and no provisions are needed for
fuel augmentation.
In the radiative section of each boiler, standard
water wall construction would be employed. This would extend below the
grate and partially under it. Because of steam use and radiative super-
heating, the boilers would have, respectively, no pendant reheat or super-
heat surfaces. Most of the convective section would be occupied by the
economizer and the tube banks communicating with the mud drum. The
terngerature of the flue gas exiting from the air heater would be about
500 F. Thus the furnace efficiency (see Table 7) would be about 70.0%.
The flue gas from each unit would be cleaned in a separate electrostatic
precipitator having a dust removal efficiency of 99% and each sized to
handle an expected flue gas flow of 135, 000 ACFM. After cleaning, the
two flows would be blended and released from a common stack. General
plant lay-out is shown in Figure 7.
Because of the low sulfur content of the refuse fuel
(""" 0.1 % S) and the fact that fossil fuel would not ordinarily be fired in the
furnaces, provision for an S02 control system was considered unnecessary.
The plant could be expected to emit about 2800 lb/day of S02 and about
350 lb/day of particulates. This would correspond to a stack gas composition
II- 24
-------
of O. 012 gr /SCF and 0.008 vol-% with respect to particulates and S02.
These estimates are based on emission factors discussed in Reference 1.
On this basis, it is assumed that refuse would generate 24 lb of furnace
fly ash per ton of refuse fired and that the sulfur content of refuse would
be O. 1 % S, only half of which would be converted to S02. In view of
past experience (Reference 1), the expectation of achieving a 99% col-
lection efficiency appears to be reasonable. However, considerable
tolerance is available if one compares the expected dust output of O. 24
lb/ton of refuse with the projected national particulate emis sion standard
of 1. 9 lb/ton of refuse fired.
Feedwater would be introduced at 2200 F. This
would be heated in open-type, deaerating feedwater heaters equipped with
vent condensers. Steam from the boilers would be used as the heat source.
To effect pressure reduction, the steam would first be used to drive the
turbines on the boiler feed pumps. It is assumed that 100% feedwater
make -up would be practiced and that the water would be softened (through
synthetic zeolite) rather than deionized. Salt accumulations within each
boiler would be controlled by frequent blow-downs of the oversized mud
drum.
The tipping pit would be sized to permit continuous
7-day-a-week firing. Assuming that all packer-truck deliveries are
accomplished between 10 A. M. Monday and 12 Noon Friday, and allowing
an additional margin of four hours firing time, the pit should be able to
accommodate 4300 tons or 6.60 x 105 cu ft of refuse. This would require
a pit dimension of 200 (1) x 55 (w) x 60 (d) ft.
Three 1 OO-it bridge cranes would be installed over
the pit, one of which would be us ed to arrange and mix the pit contents
during the receiving hours (day shifts, Monday through Friday). During
other shifts, it would be held in stand-by without an operator. Assuming
a charging cycle of four minutes, grapples having a capacity of 5 cu. yd.
would be sufficient. The lift speed of the cranes should be at least 300
ft/min and provide a horizontal travel speed of at least 350 ft/min.
The storage pit would be able to accommodate 13
tipping stations. Assuming, conservatively, an average load of 4 tons
(15 cu yds) per truck and a discharge cycle time of four minutes, an
off-load rate of 780 tph would be reasonable to expect. The maximum
receiving rate should, however, not exceed 520 tph. This is bas ed on the
assumption that all the refuse fired would be delivered according to a 5 -day
collection schedule (1900 tpd) and that 80% of the daily receipts would be
delivered during two 1.5 hour peak periods. Thus, no truck queueing is
likely. Weigh-in would be handled by a single automated scale; weigh-out,
which is required by the City of Philadelphia, would be accomplished on a
second identical scale.
II- 25
-------
Outs ide
Building
Wails
Truck
Traffic
..
I
I
I
I
I
I
..
.
I
(
.
r--J
I
I
I
I
I
I
I
I
I
I
.
I
I
Electrostatic Precipitators
Stack
r-.a--
--~------
Boiler No.1
Charging
Chutes
Storage Pit
-------------
---,
I
I
I
I
I
I
Boiler No.2:
I
.
.
I
I
L. - ..::..:1
I
I
I
I
I
I
I
I
I
I
I
-.
---....------
Tipping Platform
LAY-OUT OF STEAM PLANT
1I- 26
Overhead
Crane
Tracks
Figure 7
-------
Disposal of bulky refuse should probably also be
handled at this plant. This is because it will probably have a centralized
location due to its association with the mid-city steam loop. The smallest
shredder capable of accepting typical bulky refuse items would have a rat-
ing of about 700 h. p. Such a machine could coarsely (7-10 in. top size)
reduce bulky items at a rate of at least 30 tph. Thus a single shredder
would probably handle the entire city's output of such refuse, which will
likely amount to some 250 tpd by 1980. .
b.
District Steam Plant Costs
The cost model developed on the initial Envirogenics I
program was modified extensively. This was done to accommodate cost in-
creases that have occurred since the development of the model and economic
factors characteristics of the Philadelphia area. It was also necessary to
introduce or substitute new cost elements. These involved design features
common to many steam plants (e. g., feed water treatment and heating equip-
ment) that are different from those found in turbo..eledric systems. Another
costing change arose from the fact that refuse-charging equipment was based
on the use of cranes rather than live-bottom storage structures and conveyors,
as was done on the original program. The highlights of these changes, as
recommended by City and P. E. officials, are as follows:
(1) Land Cost - This was increased from
$10,000 to $40, 000 per acre, based on the sites considered.
(2) Federal Power Commission (FPC) Boiler
Component Codes 311-316 Costs - These and certain other specified capital
costs were increased at a rate of 10%/year based on the cost model
development date, June 1969. The new base date has therefore been
shifted to June 1971.
(3 )
Annualization Rate - This was reduced
to 13. 75%.
(4)
based on steam send-out.
Water Cost - This was set at 4. 5~/l03 lb,
3 (5) Maintenance Costs - The present P. E. cost
is 12~/10 lb of steam produced. To this was added another 25% in con-
sideration of maintenance problems unique to refuse-firing and the separate
costs for maintaining shredders and APC equipment.
(6) Refuse Storage Pit Costs - These were
developed on the basis that the pit should be structurally stable if com-
pletely flooded with water.
ll- 27
-------
(7) Residue Disposal Costs - This was based
on the Philadelphia practice of using truck outhaul. In the present plant
this would involve four drivers and six trucks (two standing under hoppers).
(8) Fuel Costs - Because the price of fuel oil
is unstable at the present time, refuse disposal costs have be~n presented
as a function of this cost over the range $0.30 to $0.60 per 10 Btu's.
Costs for the district heating plant are shown in
Table 10. Total refuse disposal costs is the difference between total annual
costs and the annual credit for steam generated Unit refuse disposal
cost is this differenlfe divided by the quantity of refuse handled each year,
which is 0.409 x 10 tons, assuming an 80% plant factor. This cost will
vary considerably, depending on how the annual credit for steam is derived.
If the new refuse-firing, steam plant is added to an existing inventory that
is already capable of handling the demand, then the steam credit assignable
to the new boiler can only reflect the cost of fossil fuel saved and the O&M
costs transferred from the now less active, conventional boilers. If, on
the other hand, the refuse-fired plant is added to the system to supply needed
additional capacity or to permit the retirement of old equipment, the steam
credit should reflect annualized capital costs as well. It was the judgment
of the P. E. that the former situation prevails and that the steam production
costs of existing plants, preferably the Schuylkill plant, be used to calculate
refuse disposal cost.
As can be seen in Figure 8, the steam production
cost at Schuylkill was set at $0.55/103 lb. This would result in a refuse
disposal cost of $5. 36/ton, excluding transportation. As stated earlier,
the steam sent out from Schuylkill issues from a topping turbine. Because
of this arrangement, all plant labor costs are applied to power production.
Thus the Schuylkill steam production cost includes only a fuel cost equiv-
alent to the energy content of the output ste'am, some supervision, and a
small amount of maintenance. As can be seen from Figure 8, if production
costs (first ten month of 1970) of P. E. 's straight steam plants are used,
considerably lower refuse disposal cost result. Also shown, for compara-
tive purposes, is the tariff steam rate or the official rate of charge approved
by the PUC. The rate selected (excluding state tax) is that for large Rate
lIS" steam users during the minimum demand period, June through September.
c.
Site Selection
Because of the built-up nature of Philadelphia, it
will be difficult to find suitable tracts of land that are reasonably close
to the areas where the production of refuse is the greatest. An obvious
solution to this problem would be to locate the steam generator plants at the
11-28
-------
I
FPC Codes
310
311
312
315
316
TABLE 10
COS TS FOR THE 1400 TPD PHILADELPHIA
DISTRICT HEATING PLANT
CAPITAL COSTS
Description
Land and Land Rights
Structures and Improvements
Boiler Plant Equipment
Acces sory Electrical Equipment
Misc. Power Plant Equipment
Air Pollution Control Equipment (980/c efficiency)
Waste Handling Equipment
Engineering and Inspection
Total Capital Cost
ANNUAL COSTS
Annual Capital Cost, 106 $
(Effective Annualization Rate =
6
Water Cost, 10 $
Operating Labor, 106 $
Maintenance, 106 $
Residue Disposal, 106 $
Total Annual Costs, 106 $
13. 750/c}
II-29
6
Cost, 10 $
1. 696
1. 090
6.656
0.531
0.131
0.486
2.105
1. 1 74
13.869
1. 907
0.085
O. 578
0.351
O. 300
3.221
-------
6.00
5.00
Q
0
+>
--
~ 4.00
..
+>
(fj
0
U
~
ro 3.00
(fj
o
p..
(fj
....
~
Q)
(fj 2.00
::I
'+-I
Q)
ex:
1.00
---
Cost Point
Costing Bas is
1
2
3
4
Schuylkill Station
Edison Plant
Willow Plant
Tariff Steam Rate
~
o
0.40
0.60
1.20
1. 40
1. 60
0.8{)
1.00
I
Creditable Value of Steam, $/103 lb
DISTRICT HEATING PLANT - REFUSE DISPOSAL COSTS
AS A FUNCTION OF CREDITABLE STEAM VALUE
Figure 8
II- 3.0
-------
1--
sites where refuse incinerators are now located. With the commissioning
of the refuse-'firing steam generators, some of the incinerators would have
little function except, perhaps, during outages of refuse-fired boilers.
Thus the razing of one or two of the incinerators should be acceptable,
even if interim refuse disposal by landfilling is required during the con-
struction period. Another possibility is the use of the tract of land now
occupied by the Schuylkill Arsenal. This facility is adjacent to the southern
property line of the Schuylkill Station and its purchase is now being actively
pursued by the P. E.
In the case of the district heating plant, the site
selected should obviously be located close to the existing steam lines now
used by the Philadelphia Electric Co. The scope of that system, exclud-
ing the feeder lines, can be seen in Figure 9. Considering first the in-
cinerator sites, it will be ,noted that the East Central incinerator is
somewhat closer to the loop (i. e., The Willow Steam Station) than the
Bartram incinerator is to the loop on the east side of the Schuylkill River.
The East Central plant is separated from the loop, however, by a heavily
built-up section of center city. Leading a steam line from it to the Willow
Steam Station would be a major undertaking. The Bartram plant site
provides a more practical easement to the loop. The third potential site,
being continguous with the Schuylkill Station, is not snown. It is obviously,
however, the preferred site in terms of steam loop access. Its principal
drawbacks are that: (1) unlike the city incinerator sites, the land would
have to be purchased; and (2) other uses for this plot are being considered
by the P. E. It was their advice, however, that the arsenal grounds be
given primary attention on the present program.
d.
Transportation Costs
As shown in Figure 1, each sanitation area in the
city is divided into two districts, many of which are designated by the name
of a well-known section of town located within them. The amount of refuse
hauled out of each of the districts to both landfill and the incinerators was
tabulated in an earlier section. From these data, it was possible to esti-
mate comparative transportation costs for hauling refuse, once the trucks
are filled on their collection routes, to the existing incinerators and land-
fill sites, and to the Schuylkill site discussed in the preceding section. The
assumptions adopted were that the refuse production densities within each
of the districts were uniformly distributed therein and that landfill hauls
averaged 10 miles per round "trip. The latter value is a rough approximation.
, Each of the Philadelphia incinerators fires refuse
from several districts. None, for example, receives from fewer than
seven of the twelve districts, while the Northeast Incinerator receives from
nine. Each district was therefore roughly divided into zones, the area and
11- 31
-------
SOUTH PHILADELPHIA
COLUMBIA
~
f-<
,....
I
W
N
r-- --
r-~- i ~~:L
\. cc: - -- - - - -, ......
1 II :
r - ~ n r - - - _1 - - _J .
DASHED LI N ES SHOW I I
MAIN STEAM LOOP -......: I
, I
, I
~' I
)
, .
. I...
Ct:i.
MARKET ST.
-
WEST PHILADE LPH I A
o
I
SCALE
I MILE
I
FAIRHILL
r---1D WILLOW
J~ I STATION
- I I
I I
I I
I I
, I
.... , . i-'
I I'
. I I I
--l. - --iOJ
EDISON
STATION
E. CENTRAL
INCINERATOR .....
o
~
~
(It
a
oct
o
a::
to
STEAM DISTRIBUTION SYSTEM OF THE
PHILADELPHIA ELEC TRIC COMPANY
4'igure 9
-------
1---
location of which were selected to correspond with the logical direction of
travel to and the proportion of refuse sent out to the various incinerators.
The approximate center points of these zones thus served as loci for der-
iving weight-distance vectors for each district. The travel distance on a
grid makeup of surface streets would typically be the sum of the two
orthogonal sides of a right triangle. This sum can be anywhere from 0
to 41 % larger than the direct or diagonal distance. As a first approxima-
tion, the diagonal distance was increased by 25%. Distance travelled
included return trip mileage. Thus in multiplying distances by tonnage
handled, the resultant "ton miles" is actually about twice the real work
performed on the refuse.
From these calculations it was estimated that for
the period 1 July 1969 to 30 tune 1970 the refuse transportation performed
in Philadelphia was 5.8 x 10 ton-miles. Assuming a cost of $0. 2S/ton-
mile, the transportation cost was found to be $1. 81 /ton.
A similar analysis was performed for the proposed
district heating plant. This was done on the basis of the same haul cost
($0. 25/ton-mile) used above so as to permit direct comparison to be made.
The selection of the sanitation districts to be served by the steam plant
was based on refuse collection rates projected for 1980 and the proposition
that no refuse produced in these districts would be disposed of by landfill.
The plant would be adjacent to the Schuylkill Station. Fortuitously, it was
found that the six districts in the central and southern portions of the city
would provide just slightly more than the 1400 tpd required to operate the
plant. The refuse transportation data derived for these six districts is
tabulated below.
STEAM PLANT REFUSE TRANSPORTATION DATA
District
Refuse Hauled, ton-miles /yr
West Philadelphia rJA"
West Philadelphia "B"
South Philadelphia
Central
Columbia
Fairhill
1,275,200
394,000
670,100
171,700
844,000
814,100
Total
4,169,100
II- 33
-------
The projected total tonnage would be 537,400 tons/yr. The transportation
cost would thus be $1.93 /ton, which compares favorably with the $1.81 /ton
estimated for the present incineration system.
3.
Power Plant
a.
Design Characteristics
The steam plant described in the previous sections
would be capable of handling about one-half of the refuse that will probably
be collected in Philadelphia in 1980. It has been estimated that the refuse
available for boiler fuel (see Figure 2) at that time will be about 1. 02 x 106
tpy, which is equivalent to slightly over 2800 tpd. It would therefore be
appropriate to consider a combined-fired power plant that would have a
refuse capacity either the same as or perhaps greater than the steam plant.
If oversized, fossil fuel could be substituted for the refuse that would be
lacking until such time as the growing collection rates could satisfy design
input.
Using the designations developed on the original
program, a Case 3 system equipped with two refuse-fired economizers
would require about 1500 tpd of refuse. This is based on the heating value
and boiler efficiency for the fuel (at an exit temperature of 5750 F) pro-
jected for 1980. It will be recalled that the Case 3 system consists of a
conventionally fired steam generator having little economizer surface and
one or more externally situated "boilers. II The latter are fired with refuse
to deliver high enthalpy feedwater to the drum of the steam generator.
This design was found on the previous program to be optimum in terms
of cost effectiveness for the range of refuse rates in which the present one
falls. A summary of the boiler characteristics is shown in Table 11.
Except for a slightly larger refuse pit, the
refuse handling and charging arrangement for the two economizers in the
present system would be identical to that described for the district heat-
ing plant.
The two identical economizers would be operated
in parallel and thus perform the same function. In each, refuse would be
fed through a vertical, water- cooled chute and burn on a thick fuel bed.
The three-level grates incorporated should furnish both agitation and
tumbling to the fuel mass to insure good burnout. High velocity, secondary
air nozzles would be provided in the front and rear walls to promote com-
plete combustion of volatile gases and particles rising from the fuel bed.
All walls and the roof would be of welded tube-and-fin construction.
II- 34
-------
TABLE 11
CHARACTERISTICS OF 300 MW,
CASE 3 POWER SYSTEM
Item
Refuse Rate (fractional heat input), o/c
19.4
Steam Pressure, psig
2400
Number of Turbines
Total Turbine. Heat Input, 109 Btu/hr
1
2.52
Steam Generator Efficiency Due to Refuse, o/c
67.6
Steam Generator Efficiency Due to Fossil Fuel, o/c
87.0
Net Steam Generator Efficiency, o/c
83.2
9
Heat Input Total, 10 Btu/hr
9
Heat Input from Refuse, 10 Btu/hr
Heat Input from Fossil Fuel, 109 Btu/hr
3.036
0.596
2.440
Refuse Rate (firing 2 economizers), tpd
1500
Fossil Fuel Rate (as coal), tpd
Net Plant Heat Rate, Btu/kw-hr
2440
10,120
II-35
-------
Tube banks, especially in areas of relatively high gas temperatures, would
be arrayed vertically. Horizontal tube banks would be of bare tube design
in all cases. A tubular air heater, in which the flue gas would be directed
downward inside the tubes, would be used because of its ease of cleaning.
Ash hoppers would be appropriately located to remove ash where tube
banks might act as ash deflectors.
Feedwater at 4700 F would be flowed in a single
continuous (once through) path. Flue gas would be directed in a two-pass
arrangement and be dis charged into a dust collector located at grade level.
Air, preheated to 3160 F, would be delivered as underfire air. This tem-
perature was selected as being compatible with the cast iron grate. Approxi-
mately 25 percent of the preheated air would be sent through a booster fan
and delivered as high velocity secondary air. A 50% excess of air would be
employed and the exit flue gas temperature would be 5750 F.
The water wall panels would consist of 3-in. OD
tubes spaced on 3-3/4 in. centers with fins continuously welded between
tubes. Because of the all-metal construction, slag adhesion should be
minimal. Gas-borne, molten slag-particles would be cooled upon con-
tacting the tube or fin and thus tend to shed from the surface. The solid
walls would be impervious to gas penetration, so that a costly refractory
setting would be unnecessary. In the design of the rear wall of the furnace,
a "nose" would be incorporated at the furnace exit to insure good gas dis-
tribution. This wall would also form a three-row deep slag screen. The
screen would be arrayed with a longitudinal spacing of 5-in. and a trans-
verse spacing of 11-1 /4-in. The boiler bank design would consist of 2-1 /2-in.
OD tubes, three rows deep on 7-l/2-in. spacing, and thirty-one elements
acros s on II-in. spacing, arrayed in an in-line configuration. The horizon-
tal tubes would be 3-1/2-in. OD tubes, which would also be in-line on 5 x 5-in.
centers. The loops would be supported from the front and rear panel-walls
of the second pass. Ample space would be provided in the design for the
installation' of sootblowers, if needed. The air heater would consist of
1200-12 ft-long, 2-l/2-in. OD tubes arranged in a 4-l/2-in. spaced in-line
pattern. On the air-side, the gas flow would follow a three-pass, cross-
£low path.
Feedwater from the refuse-fired economizers would
be blegded and sent over to the coal~fired steam generator at a temperature
of 66.0. F, the drum pressure of which would be about 2580 psig. Steam
condihons would be 2400 psig at 10000 F with a 10000 F re~eat cycle. Exces 5'
air would be set at 18% and a steam £low of about 2. 10 x 10 lb/hr produced.
A drawing of the economizer is shown in Figure 10.
II- 36
-------
r' r. ~r.-.r"~'""'f;:.~~''''- "P'¥',,,,-,'
~::~.,.:...:::. ;r;i
. J~7-:-.;JN::; :!,i:.
:-:.. ."".~ I'
I .-- ,I'll .
1 'I'
: II'~ I!: -;:.-~
\ "\' \'
. ~ : : I
: .1 /il :'"
I I,., t... -
I . I-:~ il .
! I-::~ ~~":; :1
t.'.:~\>o-t I
~- I
, ..:~+ l...= 1-
.. ",,'p~"'"
/J:JJ1"~'~-#ut'w r,....Jtr.........~~.UI ..;...,
SECTION "A.A"
.....-...e.a.a.........--........-----
I
~I
I
tf': i
'., 'I
,I I,,:, J I:: i
OVERFIRE ~I.j ,., : IJ:-L..t F 0 FANS
r--",. /,.'1 I" " ;'!;,[ - . .
F.O. FANS .'J~;-. 1./ "[''i : 11'.1 f"\
I . I~'!=L;' ...h--- ~~, ,
I I
f
R E1?USE-FIPED ECONOMIZER OF TEE CASE 3 TYFE
Il-37
Figure 10
-------
The steam generator fed by the two externally
located economizers would be coal-rather than oil-fired, even though the
latter is the prevalent mode of operation in the Philadelphia area. This
is considered acceptable in that the system would inc orporate gas clean-
ing equipment that would result in lower S02 emissions when firing high
sulfur coal (- 3.0% S) than would be achievable by firing low sulfur oil
(.......-0.5% S) in existing, Wlcontrolled installations.
In most respects, the design of the coal-fired
unit would be conventional. The main differences would be in the design
layout of the heating surface. The heat absorbed in this unit would be
largely accomplished by the superheater and reheater because of the use of
the ref,\!se-fired economizers. Some economizer surface would be included
in the steam generator, however. This would be situated under the con-
vection superheater. In conventional Wlits a small section of the total.
economizer surface is usually located in this area, while the remainder
is located to follow the parallel pas s.
The furnace would have panel walls consisting of
3-in.OD tubes on 3-3/4-in. centers with continuous fins welded between
the tubes. In the upper furnace, "wing" division walls would comprise a
radiant superheater incorporating 2 -in. OD tangent tubes. A parallel
pass arrangement would be used in the second pass. Superheat tempera-
ture woul.d be controlled by the firing rate and by spraying. Reheat
temperature would be controlled by regulating the gas-flow with dampers.
The air pollution control equipment on the steam
generator would consist of a wet scrubber system capable of handling the
745,000 ACFM of flue gas calculated for this boiler. Exit flue gas tem-
perature would be 3000 F. The wet scrubber would remove both fly ash
and SO at expected efficiencies of 99% and 90%, respectively. Sulfur
oxide femoval would be accomplished by liming the scrubber liquor in
accordance with the Mitsubishi process. Gypsum recovery would not be
attempted, however. The separated calcium sulfate would instead be
discarded. A .gas reheater would be included in the system to prevent
the formation of stack plume.
The flue gas from the steam generator and the two
economizers would not be intermixed at any point in the systems. Each
would have its own air cleaning equipment; the economizers would, how-
ever, share a common stack. Each would deliver about 160,000 ACFM
of flue gas to its individual electrostatic precipitator, each of which would
be rated at an efficiency of 99%. The estimated emis sion characteristics
of the overall system can be tabulated as follows:
II- 38
-------
ESTIMATED STACK EMISSION OF 300 MW,
CASE 3 POWER SYSTEM
Fly Ash S02
Stack lb / da y gr /SCF lb/day Vol.-%
Steam Generator 4392 0.042 26,352 0.021
Economizers 360 0.010 3,000 O. 008
Total 4752 ----- 29,352 -----
Composite 0.034 0.018
The above estimates are based on several assumptions
concerning fuel characteristics. It is assumed that the coal would have a
sulfur and ash content of 3.0% Sand 10.0%, respectively, and that 90% of
each of these constituents would be entrained in the flue gas as S02 and fly
ash, respectively. Refuse is assumed to contain O. 1 % S, half of which would
be converted to S02; it is also assumed that 24 lb of fly ash would be formed
for each ton of refuse fired.
A subject related to the above discus sion is thermal
pollution control. In the present analysis, cooling towers for restoring the
original temperature of the riverine water discharged from the condenser
system were not included. Such devices are not now used by Philadelphia
power stations, nor is it expected that they will become a requirement for
future thermal plants. This situation apparently results from a number of
factors, incl uding good flow and mixing rates within each of the two major
rivers there.
b.
Power Plant Costs
Capital and annual costs for the 300 MW power plant are
shown in Table 12. Those cost model modifications, which were discussed
in connection with the steam plant and which are relevant here, have been
applied. A fixed annual credit for power generated has not been used because
of the current instability in fuel costs. In the Fuel Adjustment Clause of
P. E. IS tariff steam rates, fuel costs were increased 38% effective for the
quarter starting February 1971. It is safe to estimate that fuel costs are
now in excess of $0.40/106 Btu and will probably increase considerably
in the very near future. On this basis, it can be said that refuse disposal
costs for the proposed 300 MW plant-would be something less than $1. 75/ton
and would probably shift to the asset side if fuel costs exceed $0.44/106 Btu.
The relationship of disposal costs to energy costs for the proposed plant
are shown in Figure 11.
ll- 39
-------
FPC Codes
310
311
312
314
315
316
TABLE 12
ESTIMATED COSTS FOR A 300 MW
COMBINED-FIRED TURBO:-ELECTRIC PLANT
CAPITAL COSTS
Land and Land Rights
Structures and Improvements
Boiler Plant Equipment
Turbine -Gene rator Equipment
Accessory Electrical Equipment
Misc. Power Plant Equipment
Air Pollution Control Equipment
Waste Handling Equipment
Engineering and Inspection
Total Capital Cost
ANNUAL COSTS
Annual Capital Cost, 106 $
(Effective Annualization Rate =
Water Cost, 106 $
Operating Labor, 106 $
Maintenance, 106 $
6
Coal Cost, 10 $
13. 75o/c)
Residue Disposal, 106 $
Total Annual Costs, 106 $
II-40
6
Cost, 10 $
2.380
5.326
33.077
13.431
2. 783
0.398
3.853
2.316
2.812
66.376
9.126
0.006
O. 723
1.411
5. 301
0.468
17.035
-------
25.00
s:: 20.00
o
.......
~
-
s::
o
.~
..
<
a>
-
..
tI)
o
U
5. 00
ro
:n
o
a..
tI)
.....
~
o
C)
t1J
;j
......
'!)
-5.00
-10. 00
----------------------
NOTE: In addition to variable fuel costs,
includes all fixed capital and operating costs.
o
0.10
0.20 0.30 0.40
Fossil Fuel Energy Cost, $/106 Btu
0.50
0.60
---------
DISPOSAL COSTS FOR 300 MW PLANT AS A FUNCTION OF FUEL COST
Figure 11
II-41
-------
c.
Power Plant Site Selection and Refuse
Transportation Costs
The logical location of the 300 MW plant would be
on the Schuylkill or Delaware Rivers at some point northwesterly or north-
easterly, respectively, of the northern boundaries of the Columbia and
Fairhill Districts. As can be seen in Figure 1, two city incinerator sites
can be considered. Because few other sites are now known, these were studied
to determine which would be optimum in terms of refuse transportation costs.
The results of the vector analysis are summarized in the following table:
POWER PLANT REFUSE TRANSPORTATION DATA
Refuse Hauled, Ton-Miles /Yr
Dis trict
N. W. Incinerator Site
N. E. Incinerator Site
Logan
Frankford
971,300
.'
833,100
27.0,900
1,685,800
492,700
4,049,100
8,302,900
1,380,700
1,383,000
746,700
317,000
147,500
2,350,800
6,325,700
Mana yunk
Germantown
Lower Tacony
Upper Tacony
Based on the total amount of refuse handled and a haul cost of $0. 25/ton-
mile, the transportation cost would be $4.34 and $3. 3D/ton to the Northwest
and Northeast Incinerators, respectively. Although the latter site is
obviously to be preferred, the transportation cost is still unacceptably
high, particularly in comparison with those of the existing incinerator
system ($1. 81 /ton) and the proposed steam plant ($1. 93/ton). The difference
can largely be explained on the basis of the lower refuse production density
that exists in the northern districts of Philadelphia, particularly Manayunk
and the Taconys. An obvious solution would be to employ transfer stations
in these particular districts, and possibly in Germantown as well. This
should bring the costs down by about a fourth.
11- 42
-------
III.
THE CLEVELAND STUDY
A.
WASTE MANAGEMENT OPERATIONS
1.
Municipal Background Information
Two documents obtained from the City of Cleveland
(References 3 and 4) provided important information on refuse collection
rates and population distributions. The first furnishes population statistics,
by ward, for 1967, when it was estimated that the city population was
814,156. The 1960 and 1970 census figures are 87'6,050 and 750,903,
respectively, a decrease rate of 1. 550/0/yr.
The ward structure of Cleveland is shown in Figure 12.
The nine major ward-groupings demarcated represent a new waste manage-
ment zoning now being considered there. Proposed sites for future transfer
stations are also shown on the map. The populations and population densities
of these ward groups are shown in the following table.
POPU LA TION DENSITY IN VARIOUS
SECTIONS OF CLEVELAND (1967)
Ward Group* Area, sq. mi Population
A 9.4 136,132
B 6.8 59,075
C 6. 5 127,407
D 5. 5 71,398
E 5.6 73,043
F 9.7 87,948
G 7.7 75,462
H 14.5 90,336
I 7.6 93,305
*Letter designations are arbitrary.
Pop. Density,
Persons / sq. mi
14,480
8,688
19,600
12,981
13,043
9,067
9,800
6,230
12,277
It can be seen that regions of highest population densities
are those surrounding downtown Cleveland and those along the Eastern end
of the city.
III - 1
-------
H
I=:
I
N
33
LAKE ERIE
DOWNTOWN
CLEVELAND,
,
LAKEWOOD
4
22
BROOK PARK
PARMA
EAST CLEVELAND
N
GARFIELD
HEI GHTS
. = PROPOSED REFUSE TRANSFER STATIONS
WARD MAP OF THE CITY OF CLEVELAND
Figure 12
-------
Figure 13 shows the five (arbitrarily numbered) collection
districts operating within Cleveland's Division of Naste Collection and
Disposal. It will be noted that all five district yards (and offices) have been
proposed as transfer stations. It will also be noted that two of the yards
are not located in the districts they serve; in fact, the Harvard station
is not even within the city limits. This of course results from land
availability problems. The refuse collection rates for the five districts,
based on 1969 data, can be tabulated as follows:
REFUSE COLLECTION RATES FOR
CLEVELAND'S FIVE COLLECTION DISTRICTS
Refuse Collected Estimated No.
District Area, Sq. Mi Tpd* Tpd/Sq. Mi of Homes Served
1. West Side 25.7 380 14.8 80,000
2. 24th & Rockwell 13. 1 140 10.7 60,000
3. West 3rd Street 8.8 200 22.7 15,000
4. Harvard 7.7 248 32.2 20,000
5. Glenville 10.0 224 22.4 65,000
* .
Based on fIve-day work week.
Although the collection districts are not organized on the
basis of ward boundaries, a geographic correlation can still be seen in that
the heaviest concentrations of refuse production and ward population densities
lie on the east end of town. This is fortuitous, in that the power plants
located within Cleveland are in or reasonably close to these areas of high
population and refuse production. The two lakeside power generator sites
shown in Figures 12 and 13 are, from west to east, owned by the City of
Cleveland and by the Cleveland Electric Illuminating Co.
The collection rates shown in the preceding table are
regarded as being low by the author of Reference 4. More accurate informa-
tion was also received for the year 1970, but this included totals only; these
have not yet been broken down by districts.
1lI-3
-------
Collection Districts
1- West Side
2- 24th a Rockwell
3- West Third
4- Harvard
5- Glenville
LeQend
. Proposed Transfer Station Sites "
o District Yards
.. Power Plants
1,1111 Unserved Areas
H I
H I
H
I
*'- I
I
.
. ,
,
\
,
I
.
,
. ,
,
I
I
5
lI)
N
\
"'(8 , .. - - - - --
",' , \ ~.' ,
. I
,,"
" ,
\ ,
\ -; .
\ ,
,.. /
, l
I I
,
I
I
2
4
REFUSE COLLECTION DISTRICTS IN CITY OF CLEVELAND
I
1-
Figure 13
-------
2.
Present Waste Management Program
The 1970 budget of Cleveland I s Division of Waste Coll-
ection and Disposal (DWC&D) is approximately $12,500,000, second only
to the budget of the Safety forces. S~rved on a weekly basis are 240, 000
residential units, the cost of which is approximately $1. OO/unit-wk. An
estimated 395,000 tons of refuse was collected during 1970. The estima-
ted per ton cost of disposing of Cleveland I s refuse in 1970 was about
$32. 50, which included all services from pulling the containers to the
curb to final disposal. Because this cost did not include such factors as
capital improvements, amortization, interest, etc., the DWC&D regards
$35. OO/ton to be a realistic value. The payroll of the division in 1970
exceeded 1400 persons, although a reduction in forces through attrition
is now in progres s to correct for certain archaic manning practices. The
rolling stock of the division comprised 189 packer trucks, 28 flat-bed trucks,
48 pas senger cars, and 21 specialized vehicles, including bulldozers,
animal-carcass trucks, front-end loaders, etc. In general, the vehicle
inventory is obsolescent, but new equipment is being actively sought.
Refuse handling wi thin the five districts had been more
or les s standardized in recent years except as to method of dispo sal. Crews
were first dispatched to move refuse containers to the curbs. Packer
trucks next.toured their routes and when filled proceeded individually,
without intermediate transfer, either to the landfill site operated by the
Rockside Hideaway Landfill, Inc., of Garfield Heights, Ohio, or to the
Ridge Avenue incinerator. The latter fires material collected only in the
West Side and 24th and Rockwell districts, although both of these districts
send more than 600/0 of their collections to the Rockside landfill. Formerly,
there were two incinerators in operation in Cleveland. The older of these
was phased out a few years ago as being too costly to rehabilitate. It is
also planned that the 10 year old Ridge Avenue incinerator be eventually
shut down and operations shifted to 100% landfill disposal.
Additional services provided by the DWC&D included the
removal of furniture and large appliances from the regular routes, pickup
of putrescibles from commercial and semi-commercial establishments,
and clean-up of dock areas and city streets. Special vehicles are used for
these tasks.
3.
Future Waste Management Plans
At the present time the DWC&D is moving forward in the
modernization of its operations. This is vitally needed in view of the present
high cost of disposal and the fact that the Rockside landfill will soon be
exhausted. In anticipation of this problem, bids are being sought for new
III- 5
-------
landfill contracts wherein the operator would remove the refuse in trailers
from close-in station(s). This will be done by one of two options, as deter-
mined by cost analyses of the submitted bids. The first plan would involve
the construction by the contractor of a receiving and storage plant similar
in function to that recommended in Section III, B, 7 of Reference 1. It
would not, however, involve any refuse grinding and the output from the
storage bin would be compacted into trailers for outhaul to landfill rather
than being conveyed to a furnace. The second plan would be based on the
construction, by the city, of transfer stations at a minimum of two of the
sites shown in Figures 12 and 13. There, the packer trucks would tip di-
rectly into the contractor I s trailers.
When the selected plan goes into effect, the contractor will
be expected to outhaul a guaranteed 300,000 tpy. The Ridge Avenue incin-
erator will continue to operate, although it is uncertain that the old refuse
rate of 80,000 to 90, 000 tpy will be maintained. Commissioner R. Beasley
of the DWC&D has assured Envirogenics that the landfill commitment would
not result in the denial of an adequate refuse fuel supply for any envisioned
steam generating scheme. It had originally been hoped that the plan selected
.would be implemented by 1 April 1971. Problems have arisen, however, and
a new bidding round will have to be undertaken.
Another economic pressure recently felt by the DWC&D
was a significant cut in the budget. This has necessitated an extensive re-
organization of operations, which are still under evaluation at the present
time. An outgrowth of this economy move has been a reduction in packer
truck crews to three men and the abandonment of backyard trash pick-up. .
B.
REFUSE INVENTORY AND COMPOSITION PROJECTIONS
1.
Refuse Quantities
Data received from the City of Cleveland on the quantities
of refuse disposed of during 1970 are as follows:
QUANTITY OF WASTE DISPOSED OF
IN CLEVELAND DURING 1970
Refuse Type
Cu Yds /Yr
Tons /Yr
Tons /Day
Packer Truck
to Landfill
to Incinerator
Bulky
Total
219,330
301,614
73,690
17, 766 (a)
393,070'
826
202
49(a)
1077
(a)Derived from a published specific volume value, wherein 1 cu yd of
bulky refuse = 162 lb. (Reference 5).
III - 6
-------
Included in this refuse estimate was a predominating quan-
tity of domestic material, together with street litter, dockside trash, and
waste from institutional sources, hotels, and markets. The bulky was te
constituted 4. 50/0 of the total, which is in good agreement with the 50/0 figure
suggested in Reference 1. Solid wastes from commercial and industrial
sources, other than those mentioned, are handled by private companies.
The values shown above are regarded by the author of
Reference 4 as being the most accurate yet obtained. The collection data
examined for previous years, in fact, do appear to be on the low side, con-
sidering the high rates of annual increase they suggest. The earliest estimate
on Cleveland I s refuse collections was reported for 1966 (Ref. 6). The quan-
tity estimated was 215,000 tpy, which would imply an increase of 14. 80/0/yr
to arrive at the 1970 figures. The quantity estimated for 1969 was 309, 922
tpy, which is 21. 70/0 less than the 1970 output (Ref. 4). The last reference
also predicts a future growth of 50/0/yr due to expansion in the southeast and
southwest portions of the city.
The 1. 550/0/yr decrease in population should have slightly
more than offset the expected 1. 50/0/yr per capita increase in refuse production.
Thus a more or less even collection rate should have been seen in Cleveland
over the past decade. Because of the inaccuracies associated with older
collection data and the prediction that Cleveland I s population is soon expected
to stabilize (remain constant), it was decided to as sume that the 1970 data
are accurate and project a growth rate of 1. 50/0/yr over the next decade. On
this basis, refuse rates were predicted to increase to 1250 tpy by 1980.
Allowing an additional 10% for commercial/industrial solid waste, the figure
was set at 1375 tpd.
2.
Refuse Composition
The Martin-Marietta Co. has been conducting a study
for EPA's Solid Waste Office. This has involved the compositional analyses
of refuse collected at Orlando, Florida; Wichita Falls, Texas; and Cleveland,
Ohio. The Project Manager, Mr. William Warren, kindly provided Enviro-
genics Co. the data which had been acquired in Cleveland. These analyses
were made on refuse collected in selected areas serviced by trucks from
the Ridge Avenue Station, the 24th and Rockwell Station, and the suburb of
Olmstead. The specific routes involved in the three areas were characterized,
respectively, as consisting of: (l) public housing, (2) large, older single-
family residences, many occupied by several families; and (3) single-
family, middle-class residences. The averages obtained for these three
samplings are shown below; data reported in Reference 1 are also given for
comparison.
111- 7
-------
A VERAGED COMPOSITIONAL DATA FOR
CLEVELAND REFUSE
W eight- Percent
Martin- Marietta, Nationwide
Cons ti tuent Cleveland (Ref. 1)
Garbage 18. 3 20
Paper 32.3 38
Ga rden 11. 9 12
Plastics 4.0 2
Metal 11. 2 10
Glass 15. 7 12
Residual 6. 6 6
100.0 100.0
The above composition was then adjusted to reflect the
presence of 100/0 commercial/industrial waste. Projections were then made,
per Reference 1, for future compositions. . The results are shown in Figure 14.
From Figure 14 the composition of refuse in 1980 can
be tabulated, for easier reference, as follows:
PROJECTED 1980 COMPOSITION OF
CLEVELAND REFUSE
Constituent
Garbage
Wt-%
11. 0
34.6
1 O. 7
6.7
8.5
12.6
5.9
10. 0
Paper
Ga rden
Plastics
Metal
Glass
Residual
Commercial/
Industrial
100.0
III_8
-------
~
o
I
.... 20
x
(!)
W
.3
,
40
30
10
GARDEN
COMML61NDL
o
1970
1980
1990
2000
YEA R
PROJEC TED COMPOSITIONAL CHANGES IN CLEVELAND REFUSE
ill - 9
Figure 14
-------
An ultimate analysis was then calculated for the above com-
position, the results of which are shown in the next table:
PROJECTED 1980 ULTIMATE ANALYSIS OF
CLEVELAND REFUSE
Cons ti tuent Wt-%
H20 19.8
C 26.3
H 3.5
o 21. 0
N O. 5
S O. 1
Ine rt 28.8
C.
100.0
FUEL CHARACTERISTICS OF CLEVELAND REFUSE
1.
Heating Value
Projections, based on the compositions discussed above
and the constituent calorific values for refus e des cribed in Reference 1, were
also made for the heating values of Cleveland refuse. These are shown in
Figure 15, where it can be seen that, by 1980, Cleveland's refuse will have
a higher heating value (HHV) of about 4750 Btu's/lb.
2.
Combustion Calculations
Combustion gas requirements, flue gas production rates,
and steam generator efficiencies at exit flue gas temperatures of 4500, 5000,
and 5750 F were then determined. These data are shown in Tables 13, 14,
and 15. The three different temperatures correspond, respectively, to the
flue gas exit temperatures of (1) the various Reference 1 refuse boiler designs,
excluding Case 3, (2) the straight-refuse-fired district heat plant, and (3) .
the Case 3 refuse fired economizer. The efficiency data shown in Table 15
are graphed in Figure 16 to permit the extraction of values at other flue gas
exit temperatures
III-I0
-------
rt)o
10
9
8
7
6
...J
.....
5
..
>
J:
J:
4
3
2
1970
1980
1990
2000
YEAR
PROJECTED CHANGE IN HEATING VALUE OF. CLEVELAND REFUSE
Figure 15'~
Ill- 11
-------
TABLE 13
COMBUSTION GAS REQUIREMENTS FOR CLEVELAND
REFUSE COMPOSITION PROJEC TED FOR 1980
Constituent
C
H
S
Metal
Oxygen
Total Required, stoichiometric
Total Required, 50o/c excess gas
Excess Gas
III - 1 2
Combustion Gas Requirement,
1b/1b Refuse
Oxygen
Dry Air
O. 701
0.280
0.001
0.007
0.989
0.251
O. 738
1. 107
0.369
3.021
1.207
0.004
0.030
4.262
1. 082
3.180
4.770
1.590
-------
TABLE 14
PRODUC TS OF COMBUSTION OF THE REFUSE
PROJECTED FOR CLEVELAND IN 1980
Gas Formed per 1b Refuse Vo1-o/c
Constituent Lb Mol Lb Dry Bas is
C02 0.022 0.964 13.3
H20 (0.032) (0.567)
- Refuse H2 0.018 0.315
- Refuse H20 0.011 0.198
- Combustion Air 0.003 0.054
S02 < 0.001 0.002 0.02
02 (excess) 0.012 0.369 7. 3
N2
Total Air N 0.131 3.666 } 79.4
Refuse N <0.001 0.004
Total Flue Gas (wet) 0.197 5.572
Total Flue Gas (dry) 0.165 5.005
III-I 3
-------
, TABLE 15
EFFICIENCY OF STEAM GENERATOR FIRING
CLEVELAND REFUSE OF COMPOSITION
PROJEC TED FOR 1980
Fuel Value Heat Losses at Various
Flue Gas Exit Temperatures,
Btu/lb of Fuel (% of HHV)
Item 4500F 5000F 5750F
1. Dry Gas 444 (9. 35) 505 (10.63) 595 (12.53)
2~ H20 in Refuse 241 (5.07) 245 ( 5.16) 252 ( 5.31)
3. From H2 Combustion 383 (8.06) 390 ( 8.21) 40 1 ( 8. 44)
4. H20 in Air 11 (0.23) 1 3 ( O. 27) 15 ( O. 32)
5. Unburned Gas 4 (0.08) 4 ( 0.08) 4 ( 0.08)
6. Unburned Residue 110 (2.32) 110 ( 2.32) 110 ( 2.32)
7. Sensible Heat, Residue 46 (0.97) 46 ( o. 97) 46 ( o. 97)
8. Unburned Fly Ash 41 (0.86) 41 (0.86) 41 (0.86)
9. Sensible Heat in Fly Ash 5 (0.09) 5 ( 0.11) 6 ( 0.13)
Subtotal 1285 (27.03) 1359 (28.61) 1470 (30.96)
10. Radiation ( O. 20) ( 0.20) ( 0.20)
11. Unmeasured ( O. 50) ( 0.50) ( 0.50)
12. Manufacturer's Margin ( 1. 00) ( 1. 00) ( 1. 00)
Total o/c Heat Los s 28.73 30. 31 32.66
Steam Gen. Efficiency 71. 27 69.69 67. 34
NOTE:
Fuel Value (HHV) = 4750 Btu/lb; Combustion Air Inlet
Temperature = 800F (600;c R. H. ).
III~ 1 4
-------
80
'*
-
~
u
Z
~
~
u
~
~
~
~
a:
o
~
<
~
~
Z
!it
Q
~
<
~
~
U)
70
60
300
00
o
Temperature, F
EFFICIENCIES AT VARIOUS FLUE GAS EXIT TEMPERATURES OF A
STEAM GENERATOR FIRING PROJECTED 1980 CLEVELAND REFUSE
Ill-IS
Figure 16
-------
D.
UTILITY STEAM GENERATION OPERATIONS
1.
Municipally-Owned Boilers
The facilities owned by the City of Cleveland consist of six
units, five of which are wet bottom or slagging furnaces. The sixth and new-
est unit was installed within the past few years. It has a pressurized furnace
and is of 75 MW capacity.
The other five units are Foster Wheeler boilers, three of
which were placed in service in the early 40's. The other two were com-
mis sioned in 1956. All five fire pulverized coal of low ash fusion temperature
from horizontally aligned burners. The three old boilers are identical, each
being designe~ to generate 300,000 Ib/hr of steam at a heat release rate of
26,100 Btu/ft. They are of course refractory-walled furnaces, the mono-
wall construction being of more recent invention. Retrofit of slag-tap boilers
to refuse or combined (refuse plus fossil fuel) firing is impractical because
of the costly modifications that would be necessary. Pressurized-furnace
boilers are also poor candidate'S for retrofit because of the difficulty of
providing a workable gas - seal on the charging chute.
2.
Cleveland Electric Illuminating Co. (CEI) - Owned Boilers
Three plants are operated by the CEI which are within
reasonable distance of the municipal refuse collection system. These are
the Lakeshore power station on East 70th Street and the Cleveland Memorial
Shoreway, the Canal Road steam plant beneath Eagle Avenue bridge, and the
East 20th Street steam plant between Hamilton and Lakeside Avenues. Five
units are operated at the Lakeshore Station, four of wh ich are of the contin-
uous slag-tap type and thus incompatible with refuse firing. The fifth unit
is a 250 MW dry-bottom boiler which is fueled with tangentially-fired,
pulverized coal. It is of recent enough vintage (1959) that it would not be
considered for retrofit treatment.
The steam plant at East 20th Street comprises six units,
all of which were commis sioned before 1930. The location of the plant is
in a highly congested area such that it would not be suitable for refuse
processing.
The Canal Road plant contains five boilers,all of which were
installed between 1948 and 1950. Each is equipped with forced draft chain
grate stokers and is capable of generating up to 150,000 Ib/hr of steam.
Because of their small sizes, it is doubtful that retrofit would be practical.
III- 16
-------
3.
Effect of Firing Refuse on Pollution Burden
The benefits of firing tie refuse as a substitute for fossil
fuel would have on the Cleveland air pollution situation is difficult to as ses s
because of the rather transitory nature of present utility fuel-use practices.
It was decided, somewhat arbitrarily, that benefit estimates would best be
derived based on the assumption that a coal containing about 1 % sulfur and
10% ash would be the fuel that would be partially replaced by the use of
refuse. Because gas cleaning equipment is not yet generally used through-
out Cleveland's coal-burning utility stations, particulate emis sion changes
were calculated on the basis of both zero and 99% control. As in most of
the nation, no APC equipment for sulfur oxide emission abatement is in
use in the Cleveland area, although plans for one such system are now being
considered. For the present analysis, however, zero S02 control was
as sumed.
From these bases, the comparative emissions of refuse
and an equivalent (energy-wise) amount of coal were calculated. It was
found that coal would produce about twice as much particulate loading and
4 1/2 times as much S02 in stack gas than would refuse.
The values assigned to the system variables are tabulated
below. They are based on data presented in the foregoing text and typical
air pollution data provided in Reference 1.
FACTORS ASSUMED FOR AIR POLLUTION
CALCULATIONS
Fuel
HHV, Btu/lb
Boiler
Efficiency, %
Flue Gas Loading,
lb/ton Fuel Fired
Particulates S02
Refus e
Coal
4, 100
12,000
70
85
24
160
2.3
19.0
On the basis of the above factors, it was estimated that
3. 55 lb of refuse would be required to produce the same working fluid
enthalpy as 1 lb of coal. Thus for every ton of refuse fired in substitution
for coal, the flue gas exiting the air heater would contain 21 lbs less par-
ticulate matter and 3 lbs les s S02. If an electrostatic precipitator of 99%
efficiency were us ed, the particulate reduction in the stack gas would only
amount to 0.21 lb per ton of refuse fired in substitution for coal. The
precipitator would of course have no significant effect on S02 levels.
Ill-I?
-------
If all the refuse now collected in the City of Cleveland
(393, 000 tpy) were fired in substitution for coal (1 % Sand 10% ash), the
S02 atmospheric burden would be reduced by about 590 tpy. Air-borne
dust would be reduced by about 4, 125 tpy if no APC systems were involved,
but only by one hundredth that amount if gas cleaning equipment of 99%
efficiency were in use by the hypothetical coal/refuse-fired plants. As found
in the Philadelphia analysis, the air pollution abatement benefits available
from firing refuse in lieu of fossil fuel are not great.
E.
PRELIMINARY PLANNING RECOMMENDATIONS
Overview
1.
Undertaking the construction of one or more refuse-firing
stearn generators in a large metropolitan area (LMA) such as Cleveland is
constrained by a number of factors. Obviously, the systems selected must
be located near the refuse collection network to minimize transportation
costs. Similarly, the operation of a single installation, capable of handling
all of the City's refuse, should be avoided. A single disposal plant would
necessarily be non-optimum in terms of city-wide accessibility and, too,
such an operation would doubtless promote severe traffic problems in the
immediate vicinity of the plant. Another key factor which must be considered
is that such plants must be situated near their service interfaces. A turbo-
electric facility should be within easy reach of the electrical grid system
and of copious quantities of cooling water. A process stearn or district
heating plant must be as close as possible to the stearn service lines because
easements of any distance are often difficult to arrange. Finally, and per-
haps most importantly, the planning interests of the utility companies, the
city managers, and potential large users of the product (e. g., proces s
stearn) must be served.
In the study of the Cleveland resource system, three aspects
of the local energy demand situation were considered. First, as in any LMA,
electrical power demand is increasing at a vigorous rate. For a city of
Cleveland's size, as much as 700 MW additional capacity per decade may
be required. Secondly, heating steam demand, though much more static
than the demand for electrical energy, will be difficult to satisfy with the
aging inventory of boilers now in service. Thirdly, the East Ohio Gas Co.
has an interest in the concept of firing refuse to generate process steam
(2 to 3 x l05 lb /hr) for the Republic Steel Plant in Cleveland. Unfortunately,
the last item became known only late on the program and a working arrange-
ment between Envirogenics and the Cleveland principals that would be con-
sistent with scheduled commitments could not be arranged.
III - 1 8
-------
Thus in the preliminary design work, the decision was
made to consider a refuse reduction arrangement which would include a
district heating boiler and a turbo-electric unit. The combination of these
two "strategically separated" facilities would offer the capability of con-
suming all of the refuse generated in Cleveland by the year 1980.
2.
Refuse-Fired District Heating Plant
a.
Site Selection
The district heating system operated by CEl is shown
in Figure 17. The only sites recognized for possible construction of a
refuse-fired facility were that of the existing steam plant at Canal Road,
the grounds of the now-defunct 3rd Avenue municipal incinerator, and the
yard of Sohio's asphalt and steam plant between Broadway and East 34th
Street.
The Canal Road plant is obviously the best choice
because it is already an element of the existing steam system. The plant
lay-out does not offer adequate room for waste handling, but some land is
available across the road from the plant. The 3rd Avenue municipal
incinerator is only O. 7 miles from the Canal Road steam plant and the
existing steam network. However, the construction of a pipe-line does
not appear economically attractive. Any steam flowing between the two
plants would have to cross the Cuyahoga River, the Inner Belt Freeway,
and a number of railroad lines. The Sohio proces s plant is a little farther
(1. 2 miles) from the Canal Road plant and is also separated by freeway and
railroad systems. It is, however, on the right side of the Cuyahoga and can
be considered the second best choice. Purchase of the Sobio steam plant
by the CEl is a pos sibility.
In examining the Canal Road plant lay-out (see
Figure 18), a possible accommodation for a refuse-firing unit has been
recognized. The existing 5-unit plant was designed with provision for the
installation of a 6th unit, the position of which is the closest to the coal
storage facility. The latter consists of a concrete walled, 30-ft deep pit
having a floor area of about 1/3 acre. Coal feeding, however, is normally
done directly from hopper bottom railroad cars over the track hoppers.
When this process is interrupted, then charging is done from the pit, but
usually only fr om that portion of the pit under the trestle into which coal
cars can discharge. A front end loader moves the coal from this area to
a loading hopper which communicates with a conveyor system. The latter
carries the feed to coal-crushers and thence to storage hoppers which feed
the chain stokers.
lll- 1 9
-------
LEGEND
I. NORTH SHORE POWER PLANT
2. E. 20 TH ST. STEAM PLANT
3. MAIN STEAM LI NES
4. CANAL ROAD STEAM PLANT
5. 3RD AVE. INCINERATOR
6. SOHIO STEAM PLANT
~
N
'1
~,- UJ
~ Z
:J: ~
~
en
:I:
.....
10
10
UJ
o I MI.
~
SCALE
CLEVELAND'S DISTRICT HEATING SYSTEM
lll- 20
Figure 17
-------
A major por tion of the coal-pit contents is held
in reserve for emergencies and has so been held for many decades.
If this coal could be stockpiled elsewhere, then the pit could be partitioned
and a bulk of its volume used for refuse storage without interfering with
. normal coaling operations.
Another pos sibility is that the plant might be con-
verted to fire oil. At the present time, CEI is converting its 20th Street
plant to oil-firing. If this were also done at the Canal Road plant, the coal
facilities described above could be more easily modified for refuse handling.
The new, refuse-fired boiler could of course be installed on the available,
6th foundation site or be located I'over-the-fence" on the property across
the road. As discussed later, both possibilities have been costed to deter-
mine which approach would be the more cost-effective.
The steam from the existing CEI steam plants is sent
out at 170 psig, equivalent to an enthalpy of about 1230 Btu/lb. The minimum
summer load requires steam production ranging between 90,000 and 120,000
lb/hr of steam. The former value was selected as the rating for the refuse
firing unit. This would permit the unit to dispose of refuse collected in
designated Cleveland districts at a more or less steady rate all year around.
It would also permit the East 20th Street plant to feed some steam into the
loop during minimum demand periods and thus minimize frictional line-
losses. The duty of the new unit would be 0.105 x 109 Btu/hr. Using the
fuel value projected for Cleveland refuse in 1980 (4750 Btu/1b) and an effic-
iency calculated to be 69. 7%, a refuse rate of about 400 tpd would be required.
b.
Over-the-Fence Arrangement
The over-the-fence installation would be essentially
a self- sufficient system. It would consist of a single boiler, the enclosure
of which would include a tipping-pit. The overall system design and opera-
tion would be basically the same as that described in Section II, E, 2, a,
except of course smaller in scale. The characteristics of the proposed Canal
Road steam plant are summarized in Table 16.
As seen, the storage pit would be sized to provide
SIX tipping stations. Based on an average packer truck load of four tons
(15 cu yds) and a discharge cycle time of four minutes, an average dump-
ing rate of 360 tph would be expected. The maximum receiving rate during
peak traffic hours should not, however, exceed 150 tph. Thus, truck queue-
ing is not probable. Weigh-in would be handled by a single, automated scale.
The access streets serving the site are rather narrow and require improvement.
I11-21
-------
TABLE 16
SYS TEM CHARAC TERIS TICS OF
CANAL ROAD STEAM PLANT
(REFUSE FIRED)
Steam Specifications
Production, Ib/hr
Sendout, Ib/hr
Pressure, psig
o
Temperature, F
Boiler Specifications
Refuse Rate, tpd
Efficiency, o/c
Duty, 109 Btu/hr
Flue Gas Exit Temperature, of
Exit Flue Gas Volume, ACFM
Feed Water Temperature, of
Plant Factor, o/c
Refuse Handling Facilities Specifications
Tipping Pit Dimensions, ft
Number of Bridge Cranes
Grapple Capacity, cu yd
Number of Tipping Stations
III-22
90,000
75,000
170
425
400
69.7
0.105
500
76,600
220
80
100 (l) x 40 (w) x 50 (d)
2 (60 ft long)
3
6
-------
Because of this, it was felt that oversized refuse should not be handled at
this plant.
Costs for the overall system have been derived util-
izing the methodology outlined in Reference 1. In these calculations, the
present system was considered to be equivalent to a 10 MW turbo-electric
system in solving certain of the cost functions. Because the base date of
the various cost formulae is June 1969, capital costs have been increased
by 10%/yr for a period of two years, bringing the base date to June 1971.
The results of this costing are shown in Table 17.
Disposal costs have been derived in two ways. In
Method A, it is assumed that the new, refuse-firing steam generator would
be added to the system inventory to provide needed capacity. That is, it
would replace a unit that had to be retired or would provide a needed in-
crease in the total production of the existing system. In either of these
situations, it would then be acceptable to apply the value of the steam gener-
ated (based on conventional plant operation) against the annualized capital'
and O&M costs of the new plant. If, on the other hand, the addition of this
base load plant were made to an existing steam plant arrangement that
was already capable of handling the demand, a service displacement would
occur. Some or all of the conventional units would have to be operated
at reduced plant factors in order to permit the refuse-fired installation to
operate at full load. In this case, annual credits (Method B) should include
only the costs of fossil fuel, labor, and maintenance for the conventional
plants partly or totally displaced by the new plant.
The credit used ~or the Column A costing was
derived using a steam value of $1. 05/10 lb, based on present operating
costs. For Column B, a coal-fired steam generator efficiency of 83% and
energy cost of $0.31/106 were used in determining the coal credit. Labor
and maintenance savings were assumed to be the same as the corresponding
costs for operating the refuse-fired plant, except that those cost items
dealing with refuse handling were deleted. This adjustment, incidentally,
showed that the labor costs of the refuse-fired plant would be 67% higher
than those of its fossil fuel equivalent.
A drawback to the plant layout just described is the
condition of the land adjacent to the Canal Road Plant. It is poorly shaped
and contoured, offers a marginal amount of area, and has a transformer
building located on the most important section of the plot. A detailed civil
engineering analysis of the property would be required to verify the feasi-
bility of utilizing this real estate.
III - 2 3
-------
FPC Codes
310
311
312
315
316
TABLE 17
ESTIMATED COSTS FOR THE OVER-THE-FENCE.
REFUSE-FIRED STEAM BOILER
CAPITAL COSTS
Description
Land and Land Rights (10 ac re s)
Structures and Improvements
Boiler Plant Equipment
Accessory Electrical Equipment
Misc. Power Plant Equipment
Air Pollution Control Equipment
Waste Handling Equipment
Engineering and Inspection
Total Capital Cost
ANNUAL COS TS
Annual Capital Cost, 106 $
(Effective Annualization Rate = 14.6Ofc)
- - 6
Water Cost, 10 $
Operating Labor, 106 $
Maintenance, 106 $
Residue Disposal, 106 $
Total Annual Costs, 106 $
A
Annual Credit, 106 $
o. 552
117
8. 16
3
Quantity of Waste Burned, 10 ton/yr
Disposal Cost, $/ton
A.
B.
Based on revenues for steam generated.
Based on coal, labor, and maintenance costs
for operating existing steam generator of .
equivalent capacity.
IlI- 24
6
Cost, 10 $
0.860
0.348
2.360
0.202
0.097
0.189
0.914
O. 705
5.675
0.828
0.038
0.455
0.096
0.090
1,507
B
O. 519
117
8.45
-------
c.
On-Site Arrangement
An alternate approach would be to utilize the
vacant foundation in the Canal Road Plant for the installation of a refuse-
fired boiler (see Figure 18). This would require that at least a portion
of the coal pit would be available for refuse storage.
The floor area of the pit is 14, 100 sq ft and the walls
are 30 it high except around the trestle. This represents a storage capacity
of over 15,000 cu yds, which is well in excess of the maximum refuse storage
volume requirement of 7000 cu yds. If the plant were converted to oil firing,
the existing coal conveyor system, including the loading hopper on the floor
of the pit, would be of no value for refuse charging. The existing components
are too narrow and conversion to the 10-It felt width needed would be exces-
sively costly. A new chargng arrangement would have to be installed.
Direct tipping into the pit also will not be practical.
The two ramped-roadways are too narrow and the pit wall extends from four
to nine feet above them at the highest and lowest elevations of the ramps,
respectively. The most economical solution to this problem is to install a
four-station tipping pit on the property opposite the plant on Canal Road. An
enclosed conveyor system would then be used to bring the material from the
tipping pit, over Canal Road, and into the storage structure. The overall
arrangement is shown conceptually in Figure 19.
An expensive pit modification will be the installation
of a covering structure. Except for a flat portion under the trestle, it would
be an arched configuration, supported by columns standing within the pit;
the roof would extend just to the walls at. the edge of the pit. In the interest
of odor control, the structure would be fitted with duct work so that the
combustion air for the refuse-fired furnace could be drawn from the pit.
Because of its lower volumetric heat-release rate,
the boiler itself would be much larger than the units now fired at Canal Road,
such that the existing foundation site would not be adequate. As shown in
Figure 19 the boiler would therefore be laid out so as to project out toward
the refuse pit. This would require the removal of a portion of the boiler
house wall, and the erection of a new ell on the building to house the new
boiler. The charging hopper of the boiler would be sealed off from the rest
of the building so that refuse odors would not permeate into the plant. The
boiler design features would be essentially the same as those described for
the over-the-fence plant, except that stoking would be by conveyor and ram
inj ecto r.
III - 2 5
-------
BOILERS r:::l
L .0
STACKS 0
I ~
H
H
H
I
N
0'
l TRACK
HOPPER
DO
00
,
......
""'.....
,
,'''''''''''' ~
.... '
.... '
'..... '.....
..... ....
""','~ . C4AI
, , I IV4{
7'
I
I
I
I
I
I
I
I
;;>0-40 ~
LOADING
HOPPER
\
COAL STORAGE
TRACKS
;u
o
»
o
~
~
CANAL ROAD STEAM PLANT
Figure 18
-------
TRANSFORMER
STATION
/
~
Can a I Road
-------
-------
H
H
H
I
N
-J
ODD
000
DO
~
~ED
\ BOILER
/
CONVEYOR
BRIDeE
....
,
....
...
...
'..
Q)
... 0
.....,~
~,
m "'...
CD
=-
C
CD
>
-------
Preliminary costs for this system were derived
and are presented in Table 18. It can be seen that both capital and annual
costs are lower than for the over-the-fence plant. This is because the
operating labor costs will be. somewhat lower by having the plant on site
and because less land will have to be purchased. In this costing, bulldozer
equipment sufficient to support two operators per shift have been included
even though such equipment is now being operated.
d.
Air Pollution Control (APC) Equipment
In either of the possible plant layouts, the APC
system would be the same. A single electrostatic precipitator having
a dust removal efficiency of 99% would be used. The system would be
sized to handle a gas throughput of 76,600 ACFM based on an inlet tempera-
ture of SOOo F. Because only refuse (sulfur content ""0. l%S) would normally
be fired in the furnace, provision for S02- removal is not considered necessary.
U sing the same emis sion factors as sumed for the Philadelphia study (Section
il, E, 2), it can be estimated that the present unit would emit about 96 lb/day
. fly ash. This corresponds to a stack gas loading of 0.011 gr/SCF. The
S02 output would be about 800 lb/day; this corresponds to a stack gas con-
centration of O. 008 Vol. -%.
3.
Refuse-Fired Turbo-electric Plant
a.
Size Specification
Whichever version of the steam plant discussed in the
previous sections were built, it would be capable of handling only slightly
more than 1/4 of the total refuse projected to be collected in Cleveland in
1980. Disposal of an additional 975 tpd will probably be necessary. This
quantity is about right for a 200 MW Case (936 tpd) system, deriving 16.6%
of its heat input from refuse. Adding this much power capacity to the existing
CEl inventory does not appear to pose any problem, considering the growing
power demand in Cleveland. The Case 3 design, as discussed in Reference 1,
is considered to be optimum for this power rating among the many conventional
and advanced (e. g., suspension firing) designs analyzed for cost effectiveness.
A question concerning plant sizing was whether to pro-
vide additional capacity to accommodate refuse production growth beyond 1980.
This was not done in the present case, because the possibility also exists in
Cleveland forS the erection of a third refuse-fired plant sized for the production
of 2 to 3 x 10 lb/hr of process (steel mill) stearn.
llI- 28
-------
FPC Codes
310
311
312
315
316
TABLE 18
ESTIMATED COSTS FOR REFUSE-FIRED STEAM BOILER
INSTALLED. ON-SITE AT CANAL ROAD PLANT
CAPITAL COSTS
Description
Land and Land Rights (5.5 acres)
Structures and Improvements
Boiler Plant Equipment
Accessory Electrical Equipment
Misc. Power Plant Equipment
Air Pollution Control Equipment
Waste Handling Equipment
Engineering and Inspection
Total Capital Cost
ANNUAL COSTS
Annual Capital Cost, 106 $
(Effective Annualization Rate = 14. 6O/c)
Water Cost, 106 $
Operating Labor, 106 $
Maintenance, 106 $
Residue Disposal, 106 $
Total Annual Costs. 106 $
A
Annual Credit, 106 $
0.552
117
7.72
3
Quantity of Waste Burned. 10 ton/yr
Disposal Cost. $/ton
A.
Based on revenues for steam generated.
Based on coal, labor. and maintenance costs
for operating existing steam generator of
equivalent capacity.
B.
III;;'29
6
Cost, 10 $
0.471
0.400
2.311
0.202
0.050
0.189
1.022
0.660
5.331
o. 778
0.038
0.416
0.133
0.090
1. 455
B
0.519
117
8.00
-------
b.
Site Selection
. Studies of possible sites for the plant revealed that the
p:Jant would probably have to be located on the shores of Lake Erie. The
Cuyahoga River is too contaminated to be considered even as a source cool-
ing water. Along the lake front, however, relatively few sites, which are
within reasonable reach of the waste collection system, appear to be avail-
able. The best approach would therefore be to install the new boiler at the
existing Lake Shore Plant. This already accommodates five units,. but has
provisions, including an empty turbine room, for expanded capacity. In-
stallation of a Case 3 system could be accomplished by locating the fossil
fuel steam generator on the "future-site" provided and locating the refuse-
fired economizer on adjacent property. The general plant lay-out is shown
in Figure 20.
c.
System Characteristics
A 200 MW version would be comprised of one coal-
fired steam generator and one refuse-fired economizer. The tipping pit
would be 150 ft long, 40 ft wide, and 60 ft deep. Two cranes mounted on
60 ft bridges 'and equipped with 5 cu yd grapples would be provided. One
crane would be used for standby service except during the day shift on week
days, when it would be manned and used to mix and arrange the pit contents.
The general design and operational characteristics of
the system would be very similar to those described in Section II E, 3, a.
Specific des cripti ve information on the present system is itemized in
Table 19.
Because of its more acces sible location, the Lake
Shore system would be assigned the task of shredding and firing oversized
refuse. A single 700 h. p. hammermill could reduce such items at a rate
of at least 30 tph. The city's entire output of such refuse is only about
50 tpd at the present time and would probably increase to only 75 tpd by
1980. Thus the mill would only be used a few days each week.
A special design requirement for this proposed plant
would be low stack height. The present Lake Shore site is situated in an
aircraft lane and CEl has already been requested to shorten the boiler stacks
already erected on the property. There is, in fact, a possibility that the site
may be condemned for the above reason.
III- 30
-------
LAKE ERIE
..J
I&J
Z
Z
C
:r
()
I&J
:III:
C
...
z
~;/
/
East Memorial Shoreway
SCREEN I
HOUSE DISCHARGE CHANNEL
/ .. Jt
~ I&J
II z
J '..J
"""\- >-
' I I ...
I I g:
I I&J
I I UNOCCUPIED Q.
I I I TURBINE ROOM 0
II:
I I I Q.
t... - - - - -.J. - - - - L.. - - - - - - -
I LOGI CAL
14 US I 18 17 18
I AVAILABLE REFUSE
o 0:0 - BOILER HANDLIN
o SITE AREA
I -- --
:
.
G
EXISTING BOILERS
o
/ END OF
~ E,70TH ST.
LAKE SHORE PLANT LAYOUT
Figure 20
III - 31
-------
TABLE 19
CHARAC TERIS TICS OF 200 MW ~ COMBINATION-FIRED
SYSTEM FOR THE LAKE SHORE PLANT
Item
Fuel Rate, tpd
Excess Air, o/c
Flue Gas Exit Temperature, of
Flue Gas Volume, ACFM
Unit Efficiency, o/c
Design Fuel Value, Btu/lb
Duty, 109 Btu/hr
o
Feedwater Temperature, F
Steam Conditions, psig/oF/oF
Steam Flow, 106 lb/hr
Number of Turbines
Plant Factor, o/c
Economizer
Steam Generator
936 (Refuse)
50
575
195,000
67.3
1, 752 (Coal)
18
300
570,000
87.0
12,022
1. 527
620 (1960 psi€
1800/1000/1000
1. 430
1
80
4,750
0.249
440
80
111- 32
-------
The addition of a combination-fired system would not,
however, complicate the stack hazard problem. Being equipped with high
efficiency gas cleaning systems, there would be no need to rely on high stacks
to disperse pollutants. The wet scrubber system on the coal-fired steam
generator would be sized to handle the 570,000 ACFM of flue gas calculated
for this boiler based on an exit flue gas temperature of 3000 F. The wet
scrubber would remove both fly ash and SOx' The latter removal would be
accomplished by liming the scrubber liquor in accordance with the Mitsubishi
process. Gypsum recovery would not be attempted, however. The separated
calcium sulfate would instead be discarded. Because of the inclusion of this
system, use of a low sulfur coal would be unnecessary.
The refuse-fired economizer would be equipped with
an electrostatic precipitator having a dust-removal efficiency of 99%. It
would be sized to handle a gas throughput of 195,000 ACFM based on an inlet
gas temperature of 5750 F. Following the gas cleaning stages, the exit
gases from the two furnaces would be blended and discharged through a
common stack. Because of the comparatively high temperature of the
economizer flue gas, it would be unneces sary to reheat the flue gas exiting
the wet scrubber of the steam generator.
Using the same emission factors observed for
the Philadelphia analysis (Section II, E, 3), the following emis sion estimates
can be tabulated:
ESTIMATED STACK EMISSIONS OF 200 MW
CASE 3 POWER SYSTEM
Combined Stack
Fly Ash
lb/day gr /SCF
3154 0.039
224 0.012
3378 0.033
S02
lb / day
18,922
1,872
20,794
Vol-%
0.020
0.008
0.017
Source
Steam Generator
Economizer
Costs for this system have been derived as shown
in Table 20 and in accordance with the procedures described earlier in this
report. In computing the annual credit for power generated, a parallel
costing was performed for a conventionally-fired, 200 MW unit to determine
annual costs and, thus, production costs for electricity, based on today's
capital and operating expenses. Unlike Philadelphia, considerable amounts
of coal are being fired in Cleveland such that fuel costs are more stable.
Because of this, a fixed fuel cost of $0. 31/106 Btu could be used in the
calculations. It can be seen from the cost data that the disposal cost for
refuse, exclusive o£ transportation, is considerably more attractive than
those derived for the district heating plant.
III - 33
-------
FPC Codes
310
311
312
314
315
316
TABLE 20
ES TIMA TED COS TS FOR REFUSE -FIRED.
TURBO-ELECTRIG.SYSTEM INSTALLED
A T THE LAKESHORE S TA TION
CAPITAL COS TS
Description
Land and Land Rights
Structures and Improvements
Boiler Plant Equipment
Turbine-Generator Equipment
Accessory Electrical Equipment
Misc. Power Plant Equipment
Air Pollution Control Equipment
Waste Handling Equipment
Engineering and Inspection
Total Capital Cost
ANNUAL COSTS
Annual Capital Cost, 106 $
(Effecti ve Annualization Rate = 14. 6o/c)
Operating Labor, 106 $
Maintenance, 106 $
Coal Cost, 106 $
Residue Disposal, 106 $
Total Annual Costs, 106 $
Annual Credit for Power Generated, 106 $
3
Quantity of Waste Burned, 10 ton/yr
Disposal Cost, $/ton
III - 34
.6
Cost, 10 $
1 . 040
3.343
23.663
10.582
1. 682
0.384
2.550
1. 362
2.268
46.874
6.844
0.551
1. 107
3.813
0.249
12.564
11. 849
273
2.62
-------
4.
Trans portation Cos ts
a.
Overview
An important cost element in disposing of refus e is
that associated with the movement of packer trucks, once they are loaded,
from their collection routes to the disposal site. If this cost increases in
shifting from present disposal methods to the steam generator approach,
appropriate operating adjustments will be required. Either the rolling
stock and the number of collection routes must be increased or transfer
stations will have to be incorporated within the system.
In performing the cost analysis, a number of
as sumptions were neces sarily made. These are discus sed in the following
s ec tions.
b.
Tonnage Hauled
It was as sumed that the amount of collected refuse
generated daily would be that projected for 1980 (13 75 tpd). It was furOther
assumed that the relative distribution of this production among the five
collection districts would be the same as that recorded for the year 1969.
The values thus derived are shown in the following table.
Collection District
CLEVELAND REFUSE PRODUCTION
PROJECTED FOR 1980 BY DISTRICTS
Collected Refuse
Generation Rate, tpd
:Percentage
of Total
1. West Side 439
2. 24th and Rockwell 161
3. West 3rd 231
4. Harvard 286
5. Glenville 258
Total 1375
31. 9
11. 7
16.8
20.8
18.8
100.0
It was also assumed that the refuse production densitites within each district
would be uniform.
Ill- 3 5
-------
c.
Disposal Sites
In attempting to compare transportation costs of the
present methods of disposal with those associated with steam plant opera-
tion, the disposal sites must be identified. This is difficult to do in that the
landfill areas now in use will doubtless be exhausted before the end of the
decade and other sites, probably more distant from the collection system, will
have been put into operation. Because the location of future landfill sites
is unknown at the present time, it was necessary to assume that the Rockside
landfill would still be in use in 1980. Thus the transportation costs derived
for landfill disposal are probably low.
The other disposal sites were as sumed to be the
Ridge Road Incinerator, and refuse-firing boilers at the Canal Road steam
plant and the Lakeshore pOwer station. The areas assumed to be served
by these facilities are itemized in Table 21.
d.
Travel Distance Derivations
Weight-distance vectors were derived as explained
in Section II, E, 2, d.
e.
Results
Using a base cost of $0. 20/ton-mile, it was found that
haulage to the existing disposal sites would average out at $2. S8/ton. The
information used to derive this value is shown in Table 22. The cost would
be somewhat lower if current refuse production quantities were used, since
then the fraction of the total refuse handled at the more centralized Ridge
R 0 a d incinerator would arithmetically increase. Regardless of which
base year is observed, however, the cost would be high enough to warrant
serious consideration of the use of transfer stations, as is now being done.
Costs were similarly deriv.ed for transporting refuse
to the proposed steam generators. The data are summarized in Table 23.
The cost of $2. 17 /ton is significantly lower than that associated with haulage
to the existing system ($2. S8/ton) and would become even more favorable
as new, more distant landfill sites are brought into operation.
By way of breakdown, transportation cost to the
proposed Canal Road plant would be $2. 80/ton, while that to the Lakeshore
Station would be only $1. 91 /ton. This would suggest that transfer stations
also be considered in connection with the operation of the refuse- fired boiler
at Canal Road. Referring to Figure 12, the most westerly plus one of the two
other transfer station sites proposed for District 1 would appear to be suitable.
III - 3 6
-------
TABLE 21
REFUSE INPUT AREAS ASSUMED FOR
TRANSPOR TA TION COS T ANALYSIS
Refuse Input,
tpd
Disposal Site
Present Disposal Methods:
Area Se rved
Ridge Road. Incinerator
District 1 east of West
117th Street
350
Rocks ide Landfill
District 1 west of West
11 7th Street, plus all
other districts
1025
Disposal in Steam Generators:
Canal Road Plant
District 1 and District 2
south of Denison Avenue
400
Lakeshore Plant
District 2 north of Denison
Avenue plus Districts 3, 4
and 5
9 75~::
~:' This is slightly higher than the actual capacity (936 tpd) of the plant. This
was done to permit direct transportation cost comparisons of the two dis-
posa1 methods. This adjustment does not bias the results.
I11-37
-------
TABLE 22
REFUSE TRANSPORTATION COST FACTORS
FOR EXISTING CLEVELAND DISPOSAL SITES
Avg. Direct Refuse Average
Haul Distance, Transported, Round tri~
Site Mi. tpd mileage Ton-miles
Ridge Avenue Incinerator:
District 1, east of 1.3 350 3.3 1,138
West 117th Street
Rocks ide Landfill:
District 1, . west of 9.0 89 22.5 2,003
West 117th Street
District 2 5.8 161 14.5 2,335
District 3 5. 1 231 12.8 2,957
District 4 4.8 286 12.0 3,432
District 5 9.1 258 22.8 5,882
Total 1,375 17,747
T to $0.20 x 17,747 = $2. 58/ton
ransporta lOn cost = 1,375
""Includes 250/c increase for indirect travel patterns.
1lI-38
-------
TABLE 23
REFUSE TRANSPORTATION COST FACTORS
FOR PROPOSED STEAM GENERATORS
Avg. Direct Refuse Average
Haul Distance, Transported, Round trip
Site Mi. tpd m ileage"( Ton-miles
Canal Road Plant:
District 1 and
District 2 south 5.6 400 14.0 5,600
of Deriison A venue
T "1.keshore Plant:
District 2, north of 4.5 200 11. 3 2,260
Denison A venue
District 3 4.2 231 10.5 2,426
District 4 5.2 286 13.0 3, 718
District 5, SW of 1.2 173 3.0 519
140th Street
District 5, NE of 1.9 85 4.8 408
140th Street
Total 1,375 1~, 931
T t t t - $0.20 x 14,931 = $2.17/ton
ranspor a ion cos - 1,375
::(Inc1udes 25% increase for indirect travel patterns.
IIl- 39
-------
5.
Conclusions Regarding the Cleveland Study
At the present time, the City of Cleveland is considering
proposals for the operation of new landfill sites under arrangements with
private contractors. The new approach will include the use of transfer
stations to reduce transportation costs. Including an estimated cost of
$0. 50/ton for hauling to the transfer stations, it appears likely from
recent bidding that net disposal costs will increase to about $7. OO/ton.
In comparison, the below summarized costs for disposal
with energy recovery in refuse-fired boilers can be considered.
ESTIMATED COSTS FOR CLEVELAND'S WASTE-FIRED
STEAM GENERATING SYSTEMS
District Heating Plant
(On-Site Version)
Turbo-electric
Facility
Total Capital Cos t, 106 $
Total Annual Cost, 106 $
5.331
1. 455
46.874
12.564
Total Net Disposal Cost,
$ / ton
A B
-
0.552 O. 519 11. 849
7.72 8.00 2.62
2.80 2.80 1. 88
10 . 52 10. 80 4.50
Annual Credit, 106 $
Refuse Disposal Cost,
$ / ton
Transportation Cost,
$ / ton
A
Based on revenues for steam generated.
B
Based on displaced coal, labor, and maintenance costs for operating
existing, conventional steam generator of equivalent capacity.
It is clear that operation of the combustion-fired power
plant would provide considerable cost savings to the City of Cleveland. This
is not immediately true in the case of the district heating plant. Assuming
that the proposed steam plant were operated in connection with transfer
stations, total net disposal costs would still be higher (about $9.75 and $.10.00
per ton by costing methods A and B, respectively) than for landfilling. This
comparison, however, is based on today' s fossil fuel and disposal costs.
III-40
-------
As both of these increase, the cost-effectiveness of the proposed heating
plant will rapidly change. In terms of fuel cost variations, for example,
this sensitivity was demonstrated in Figure 11. Another factor that
would serve to reduce disposal costs would be an increase in steam sales.
This would put the plant on a more attractive (Method A) costing basis and
the required increase in the refuse rate would result in a more cost-
effective system design.
An alternate plan that can be considered is to con-
struct two smaller turbo-electric stations. From the cost model developed
on the earlier program, this arrangement can be shown to be non-optimunl
and to result in very high disposal costs. It has been concluded, there-
fore, that the system recommended is the proper approach. To trade
off nicely the factors that influence an area case study of this type, it is
virtually impossible to realize a perfect balance of system cost benefits
in the face of local constraints.
III-41
-------
ACKNOW LEDGEMENTS
The present program was conducted under the technical guidance of
EPA' s Robert C. Lorentz, who also served as project officer on the pre-
vious program. The insight and understanding he provided on both programs
have been much appreciated. The authors also wish to acknowledge the
inputs and guidance supplied by their department head, Mr. E. M. Wilson.
Accomplishment of the work described in the present report obviously
required a considerable amount of assistance and cooperation by city and
utility officials in the two municipalities studied. What is noteworthy is
that this support was given in such a friendly and open manner.
The authors particularly extend their thanks to Mr. Elwood A. Clymer
of Philadelphia Electric Co. and Mr. Howard Mayerhofer of Cleveland
Electric Illuminating Co. These men not only provided much of the needed
working data and their review talents, but generally smoothed the way.
Acknowledgement should also be made of the following other officials who
lent their support, in one form or another, to the present study.
Individual
City of Philadelphia
Title
David Darniano*
Chief Sanitation Engineer
Department of Streets -Sanitation
Leo Goldstein
Commissioner
Department of Streets
Glenn Smith
Chief Sanitation Engineer
Department of Streets -Sanitation
Philadelphia Electric Co.
Vincent S. Boyer
Vice President
Engineering and Research
John S. Kemper
Manager
Engineering and Research Division
Edward C. Kistner
Chief Mechanical Engineer
*Now with New York City.
III-42
-------
Indi vidual
Title
Charles W. McQuiston
Sales Engineer,
Government Sales Division
Frederick A. Pyecroft
Manager
Government Sales Division
City of Cleveland
Robert Beasley
Commissioner
Division of Waste Collection and Disposal
o. N. Bergman, Jr.
Commissioner
Division of Light and Power
Cleveland Electric Illuminating Co.
R. G. Schuerger
Manager
Ci viI and Mechanical Engineering
John A. Bostic
General Supervising Engineer
IIl- 4 3
-------
REFERENCES
1.
Roberts, R. M., et aI, "Systems Evaluation of Refuse as a Low
Sulfur Fuel, " Envirogenics Co. Final Report No. F -1295 for
EPA Contract CPA 22-69-22, November 1971.
2.
Federal Power Commis sion Staff Report, Air Pollution and the
Regulated Electric Power and Natural Gas Industries, September
1968.
3.
Solid Waste Management, Department of Public Service Report
to City Council of Cleveland, 10 June 1968.
4.
Beasley" R., Functions and Activities, Department of Public
Service, Division of Waste Collection and Disposal, City of
Cleveland Internal Report, December l, 1968.
5.
Kaiser, E. R., liThe Incineration of Bulky Refuse, II Froc. 1966
Nat. Incin. Con£., New York, 1-4 May 1966, pp 39-48.
6.
Governmental Facts, No. 125, Governmental Research Institute
Cleveland, Ohio, 8 August 1967.
III-44
-------
APPENDIX A
COSTS OF OPERATING PLANTS
OF OVERSIZED REFUSE CAPACITY
1.
INTRODUCTION
The sizing of refuse-fired steam generators should logically conform
to the collection rates of the area served. During the life expectancy of the
boiler, which should be at least 20 years, both the quantity and fuel value
of refuse will increase. An enhancement in heating value would likely
necessitate a cut-back in the refuse firing rate of waste fueled plants.
The net effect would be that alternate methods of disposal would have to be
sought for the refuse in excess of plant capacity. A possible solution to
this problem would be to co nstruct plants that are of greater capacities than
the refuse available. As the design refuse rate approached fulfillment,
lead time would thus be provided for planning new starts on additional units.
An obvious drawback to operating oversized plants would be the higher initial
capital outlay and, in all probability, a substantial increase in disposal
costs over those that would be realized when firing at rated capacity. The
purpose of the analysis des cribed in this appendix was to examine the effect
of oversizing on disposal costs and to compare two different approaches for
operating oversized plants.
II.
COST ANALYSIS
A.
SYSTEM OPTIONS
The cost analysis was performed for system conditions that
were initially expected to have applicability for the Philadelphia case study.
This did not prove to be the case. Thus the systems subjected to the cost
modeling described here are somewhat different from those detailed in the
main part of the report. The general conclusions reached, however, are
qualitati vely valid regardles s of which system Gonditions are actually observed.
For the purpose of the present analysis, a 500 MW Case 3 plant
firing 5500 Btu refuse was analyzed. Two modalities of under-capacity
operation were considered. These are referred to here as the expandable
plant and the fixed design plant.
A-I
-------
The expandable plant would be a full- sized, Case 3 system in all
respects except that it would be equipped with only three of the four waste-
fueled economizers specified on the initial program. It would thus operate
at something less than the 75% refuse rate. The shortage of energy input
would be compensated for by reducing the fossil fuel input to the steam
generator. The turndown of the steam generator would not necessarily have
to be directly proportional to the shortage of refuse energy input. There
would be very definite limits, however, as to the flow of extra steam that
could be achieved by firing higher than proportional quantities of fossil fuel
in the steam generator. For the present analysis, therefore, it was assumed
that the fuel rates would be at a fixed ratio regardles s of the plant duty. This
would mean that when the three economizers achieve full refuse input rates
the plant capacity would be at 75% of nameplate rating, or 375 MW. Beyond
this point a fourth economizer could then be installed when convenient and
the steam generator turn-down slowly decreased until the design refuse rate
and full plant capacity of 500 MW is attained.
The alternative approach is the fixed design plant. This would
be essentially identical to the design described on the initial program and,
thus, to the system discussed above, after it had been expanded. The notable
difference in the operation of the two plants would be in the fueling of the
economizers. In the fixed design plant, the fossil fuel burners normally
used in the economizers for trimming and start-up purposes would be
continuously fired. Their function of course would be to make up for the
refuse energy shortage. Thus the plant would operate at full nameplate
rating regardless of the quantities of refuse that are available for the plant.
B.
COST ANALYSIS RESULTS
The two systems described were analyzed using the previously
developed cost model. The range of the analysis was from 75% to 100% of
refuse rate (WR). The results are shown in Figure A-I. Because of the
comparatively poor cost effectiveness of the expandable plant approach,
only a single data point was derived. The connecting dashed line is therefore
only illustrative, as is the cost jump shown (at an arbitrary point) when the
plant is expanded by adding a fourth economizer.
It is obvious from Figure A-I that the use of make-up fossil fuel
is the preferred approach to take if a plant is to be operated at les s than
full refuse rate. It is also interesting to note that, in this mode of operation,
disposal costs are not increased to unacceptable levels under conditions of
substantial fossil fuel substitutions. It should be borne in mind, however,
that system conditions used for the modeling were6 those stipulated on the
original program. Thus the fuel cost of $0. 31 /l 0 Btu observed may be
seriously inappropriate in terms of the more recent fuel cost trends. At
higher fuel costs, the analytical results would have proved less favorable
toward the fixed design plant.
A-2
-------
5.00
4.00
3.00
~
o
....
-
-(:A-
..
....
tI)
o
U
-t
------- |