United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-84-008 Mar. 1984
&EPA Project Summary
Retrofit Cost Relationships for
Hazardous Waste Incineration
K. Lim, R. DeRosier, R. Larkin and R. McCormick
This study reports a methodology
that can be used to estimate the costs of
major capital additions or subsystem
modifications for retrofitting/upgrad-
ing existing hazardous waste incinera-
tion facilities to comply with RCRA
performance requirements. The results
of the study are expressed in a series of
empirical relationships between the
costs for various capital modifications/
additions and factors that significantly
impact these costs, e.g., capacity,
materials of construction, etc. Costs
are developed for (1) aspects of combus-
tion system retrofit to improve destruc-
tion of toxic waste constituents, (2)
scrubbing system component addition,
replacement, or upgrading to improve
particulate and/or HCI removal, and
(3) addition or replacement of ancillary
equipment mandated by combustion or
scrubbing system retrofit. The costs are
based on a combination of in-house
engineering and vendor-supplied bud-
getary cost estimates.
This Project Summary was developed
by EPA's Industrial Environmental
Research Laboratory, Cincinnati. OH, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
EPA is currently performing a Regula-
tory Impact Analysis (RIA) of the RCRA
performance standards for hazardous
waste incineration facilities. One of the
key elements of the RIA is the development
of representative cost data for hazardous
waste incineration, including:
• Capital costs for new facilities
designed in accordance with RCRA
requirements.
• Operation and maintenance (O&M)
costs for these facilities, and
• Retrofit costs for existing facilities to
comply with RCRA standards.
The first two types of costs are addressed
in a larger, more in-depth companion
report entitled, "Capital and O&M Cost
Relationships for Hazardous Waste Incin-
eration."
The objective of the study summarized
herein was to develop a methodology and
an accompanying set of cost relationships
that could be used to estimate the costs of
retrofitting or upgrading components of
existing hazardous waste incineration
facilities to comply with RCRA performance
requirements. Both the methodology and
the retrofit cost relationships were
intended to focus on major capital
additions or subsystem modifications
that could be required for existing
facilities to: (1) increase destruction and
removal efficiency (ORE) of the principal
organic hazardous constituents (POHC's)
in the waste feed, (2) reduce particulate
loading in the stack gas to <0.08 gr/dscf,
and/or (3) increase HCI removal to >99
percent in facilities burning a waste mix
containing >0.5 percent organic chlorine.
This study provides engineering-cost
relationships and cost data that can be
used in an RIA to estimate the costs of
those regulatory alternatives which
require that existing incinerators be
retrofitted. However, because there was
insufficient design information available
on existing incinerators, no attempt was
made in this study to predict what the
total costs would be for the incinerator
industry to comply with a particular
regulatory alternative. Instead, sufficient
cost information was developed so that
those performing the RIA could address
the question: "If one or more capital
additions/modifications are required for
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Facility XYZ to achieve RCRA compliance,
and Facility XYZ has specified design/
operational characteristics, what will it
cost to make the necessary modifications?"
It was recognized that major capital
additions or modifications were not the
only types of retrofit costs that may be
encountered by facilities upgrading perfor-
mance. Other potential costs associated
with upgrading include minor finetuning
adjustments, downtown-related costs,
and increased O&M costs. However,
these costs could not be quantified
within the framework of this study.
Methodology
The results of this study are expressed
in a series of graphical relationships
between the costs for various capital
modifications or additions and factors
that significantly impact these costs, e.g.,
capacity and materials of construction.
Costs are developed for:
• Combustion system retrofit
- Burner replacement
- Refractory replacement
- Combustion chamber replacement
• Quench and/or waste heat boiler
addition
• Scrubber system addition, replace-
ment, or modification
• Flue gas handling system modification
- Fans, stack, etc.
In addition to the cost curves themselves,
guidelines are presented toaid the user in
determining when particular retrofit
activities need to be considered, what
types of input data are needed to use the
various cost curves, and how installation
and indirect construction costs can be
factored in.
The cost relationships and associated
information are designed to cover as
broad a range of incinerator facilities as
possible. A wide range of waste composi-
tions is also considered, including
hydrocarbon-based mixtures with variable
heating values, moisture contents, ash
contents and compositions (including
alkalis), and chlorine concentrations.
Liquid injection, rotary kiln, and hearth-
type incinerators are all addressed in
capacities ranging from 1-1000 M
Btu/hr. Quenches and steam-generating
waste heat boilers are considered for gas
temperature reduction; venturi scrubbers
are assumed for paniculate control; and
packed bed absorbers are assumed for
HCI removal.
Combustion
The primary driving force considered in
this study for combustion system retrofit
was to increase destruction efficiencies
(DE's) for POHC's contained in the waste.
At present, insufficient data are available
to relate DE's directly to incinerator
design and operational requirements.
Therefore, this study focused on major
capital additions or modifications that
might be needed to raise incinerator
temperature above original design
specifications and/or to increase effective
residence time, mixing efficiency, etc.
First, the costs of burner system
replacement for improved combustion
efficiency or increased fuel co-firing
capability to elevate temperature were
estimated. The major problem in estimat-
ing these costs was that high-efficiency
burners capable of handling multiple
liquid waste streams plus support fuel
are almost always custom designed and fab-
ricated, and the costs are therefore quite
case-specific. As an alternative, a base-
line costing approach was adopted where-
in a purchased cost vs. capacity curve was
developed for burner systems capable of
firing waste oils. Burner auxiliaries such
as blowers, dampers, flame safe-guards,
and combustion controls were included
in the cost estimates, as were installation
costs. It was assumed that the burner
system is physically compatible with the
combustion chamber configuration. If
this is not the case, more extensive
retrofitting is required.
If incinerator temperature is increased
substantially above the original design
specifications, it may be necessary to
replace the existing refractory lining
with a higher grade material. In this
study, approximate refractory replacement
costs are estimated by first calculating
the material requirements, then judging
the type of refractory required and its
cost, and finally, factoring in labor costs
for removal of the old lining and installa-
tion of the higher quality material.
The volume of refractory required for
a given application is estimated, in brick
equivalents (9 in. x4.5 in. x 3 in.), from the
thermal capacity of the system, typical
state-of-the-art heat release rates and
residence times for the three generic
incinerator designs considered, typical
dimensions for these generic designs
(length: diameter, surface: volume), and
simplified thickness vs. temperature
guidelines. Refractory "type" (brick vs.
castable, alumina content) and unit cost
are estimated based on temperature
application guidelines, plus the qualitative
presence or absence of alkalis and/or
chlorine in the combustion environment.
Total material costs are then determined
by combining the estimated volume
requirements in brick equivalents and the
dollar per brick equivalent cost for an
appropriate refractory. A range of installed
vs. material cost multipliers is provided to
estimate the final installed cost, which is
affected by local labor costs, ease of
access to the combustion chamber
interior, and other site specific factors.
In many cases, it may not be feasible to
replace only the burner system or only the
existing refractory. Complete combustion
system replacement may be required to
significantly improve performance. For
example, a substantial increase in
operating temperature may require a
thicker refractory lining to limit skin
temperature. This increased refractory
thickness reduces internal volume and
residence time. If the residence time
reduction is significant enough to impact
DE, a larger shell and, thus, a new
combustion chamber is required.
Equipment cost vs. capacity curves are
presented for liquid injection, rotary
kiln/afterburner, and fixed hearth/after-
burner combustion systems. The costs
include burner systems, as previously
described, refractory lined shell, auxiliaries,
and controls. A range of retrofit installa-
tion costs is also provided.
Quench
If air pollution control devices (APCD's)
such as venturi scrubbers or acid gas
absorbers need to be added to existing
incineration systems to comply with
RCRA emission standards, some means
of cooling the combustion gases prior to
APCD entry must also be provided. Two
alternatives are considered in the study:
(1) direct water-spray quenching to
200°F, and (2) waste heat boiler and
post-boiler quench application to achieve
the same temperature reduction.
Separate capital cost vs. gas flow rate
curves are providedforfullscalequenches
and for smaller, post-boiler quenches.
Costs for fullscale quench towers are
based on the assumption of 2000°-
2300°F inlet gas temperature and, thus,
interior refractory lining. Acid-resistant
design is also assumed. Inlet gas temper-
atures of 400°F-600°F and acid-resistant
alloy construction are assumed for the
smaller quenches. Installation cost
multipliers are given for both generic
designs.
Equipment costs vs. gas flow rate
curves are also provided for waste heat
boilers. These costs are for packaged
firetube and watertube boilers with
standard trim and controls. Installation
cost ranges are presented as a fund ion of
retrofit difficulty.
Scrubber
In order to meet RCRA standards for
particulate and HCI removal, existing
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hazardous waste incineration facility
retrofit requirements may range from
virtually nil to complete particulate and
acid gas scrubbing system addition. In
terms of major capital additions or
modifications, however, the following
four retrofit possibilities were selected for
this study: (1) venturi scrubber addition/
replacement for improved particulate
collection, (2) conversion from once-
through water absorption of acid gases to
a caustic recycle system, (3) acid gas
absorption column addition/replacement,
and (4) total scrubbing system addition—
venturi scrubber and caustic recycle acid
gas absorption system, plus fan and
stack.
Purchased costs for complete scrubbing
systems, including flue gas handling
equipment, are presented in Figure 1.
These costs are for typical 30"WC back
pressure systems and represent "baseline"
costs for this study. Adjustment multipliers
are provided to estimate the costs for (1)
higher pressure drop systems, (2) addition
of only a venturi scrubber and auxiliaries, (3)
addition of a complete acid gas absorption
system without particulate scrubbing
capability, and (4) addition of a caustic
recycle system for conversion from once-
through water absorption of HCI. Installa-
tion cost multipliers are also provided.
Flue Gas Handling
In certain situations, particulate collec-
tion efficiency in the venturi scrubber may
be limited because the fan capacity is
insufficient to handle the combustion gas
flow at the pressure drop necessary for
good venturi performance. If this is the
case, then particulate emissions can be
reduced (without reducing waste through-
put) by simply replacing the fan. Therefore,
FOB and installation cost estimates are
provided for carbon steel and corrosion-
resistant fans as a function of total
system back pressure and gas flowrate.
Cost versus height relationships are
also provided for FRP-lined stacks.
Although stack replacement will not
reduce emissions in itself, this retrofit
possibility was included at the request of
the Office of Solid Waste for use in their
dispersion model -based risk assessments.
Since increased stack height reduces the
maximum ground level concentration of
emitted species, the costs for adding
taller stacks are needed to perform
cost/benefit analyses.
Indirect Costs
In addition to the direct costs for
equipment and installation, (he indirect
costs associated with engineering,
construction, and startup must be considered.
1,000
500
200
100
50
20
10
Figure 1.
,8
I
on
$=145 [<7o,, .cfm]
D
I I I
I I I I I 1
5 10 20 50
Inlet Gas Flowrate. qo,, f 1,000 acfm)
100
200 300
Purchase costs for typical hazardous waste incinerator scrubbing system receiving
1.800° to 2,200°F gas (July 1982).
For this study, indirect costs are estimated
as percentages of the total direct cost as
follows:
Engineering 10%
Construction overhead 10%
Construction fee 8%
Startup 2%
Thus, the indirect costs are estimated to
total approximately 30% of the direct cost
for a given retrofit. This figure does not
include permitting and trial burn costs,
which are difficult to predict for a retrofit
operation. Permitting costs for new
facilities are estimated in "Capital and O&M
Cost Relationships for Hazardous Waste
Incineration."
Example
In order to illustrate how the informa-
tion presented above can be used to
estimate costs for major retrofit activities,
the following example is provided.
Basis
A small multiple chamber hearth
incinerator is being used to dispose of
liquid process wastes and plant trash.
The toxic components of the liquid waste
are not difficult to destroy, so the unit is
achieving 99.99% destruction efficiency.
However, because the system was
installed prior to implementation of air
emission standards, no pollution controls
are provided. Combustion gas is vented
directly to a refractory-lined stack. As a
result, the unit exceeds RCRA emission
standards both for particulates and HCI.
Retrofit Requirements
In order to achieve compliance, the
existing stack must be bypassed, and a
complete scrubbing system—venturi
scrubber, HCI absorber, fan, and stack—
must be added. The mean particle
diameter in the gas is approximately 2 jum,
so a 30" WC back pressure system is
adequate. In addition, quenching can be
accomplished in the venturi outlet.
Because space is available for the
scrubbing system, no special retrofit
difficulties are encountered.
Costs
The combustion gas flow from the
secondary chamber is 10,000 acfm at
1600°F. Therefore, from Figure 1, the
purchased cost for the scrubbing system
is approximately $100,000. Since instal-
lation runs about 50% of equipment cost,
the total direct cost is $150,000. Adding
30% for indirect costs, the total capital
expenditure is $195,000.
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Limitations
The study described in this summary is
a basic, first-cut effort to estimate
potential costs for hazardous waste
incineration facility retrofit. Because of
the many site specific factors that impact
retrofit costs, the accuracy of the
estimates may be no better than -50% to
+100% for some facilities. Large discrep-
ancies between projected costs and
actual costs are most likely in situations
where space is limited, service relocations
are required, interferences are encountered,
or structural relocation is required.
Where these problems are not encountered,
the estimating methods described in the
report may achieve conceptual design
accuracies of ±30-40%.
K. Urn. R. DeRosier, R. Larkin, and R. McCormick are with Acurex Corporation,
Mountain View, CA 94039.
Benjamin L, Blanoy is the EPA Project Officer (see below).
The complete report, entitled "Retrofit Cost Relationships for Hazardous Waste
Incineration, "fOrder No. PB 84-139 435; Cost: $ 10.00, subject to change) will
be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
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