EPA-650/2-74-032
April 1974
Environmental Protection Technology Series
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DESIGN TRENDS
AND OPERATING PROBLEMS
IN COMBUSTION MODIFICATION
OF INDUSTRIAL BOILERS
by
D.W. Locklin, H.H. Krause, A.A. Putnam,
E.L. Kropp, W.T. Reid, and M.A. Duffy
Battelle - Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
EPA Grant No. R-802402
ROAP No. 21ADG-83
Program Element No. 1AB014
Project Officer: David G . Lachapelle
Control Systems Laboratory
National Environmental Research Center
Research Triangle Park, N. C. 27711
Prepared for
OFFICE OF RESEARCH AND DEVELOPMENT
ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D. C. 20460
April 1974
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This report has been reviewed by the Environmental Protection Agency
and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the" Agency,
nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
11
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TABLE OF CONTENTS
Page
ABSTRACT V
ACKNOWLEDGMENT Vi
EXECUTIVE SUMMARY 1
PART A INDUSTRIAL BOILER POPULATION AND DESIGN TRENDS *
OBJECTIVES OF TASK A-l
BACKGROUND AND SCOPE A-l
OVERALL CONCLUSIONS A-8
SURVEY OF FIELD POPULATION OF INDUSTRIAL BOILERS A-17
RECENT SALES OF FIRETUBE BOILERS A-72
APPLICABILITY OF COMBUSTION MODIFICATION TO INDUSTRIAL
BOILERS A-79
REFERENCES FOR PART A A-81
PART B FIRESIDE CORROSION AND DEPOSITS AS
AFFECTED BY COMBUSTION MODIFICATION *
TASK OBJECTIVES B-l
EFFECTS OF LOW-EXCESS AIR B-l
EFFECTS OF TWO-STAGE COMBUSTION B-7
EFFECTS OF FLUE-GAS RECIRCULATION B-10
(*) Each Part has its own separate detailed Table of Contents.
iii
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TABLE OF CONTENTS (Continued)
Page
METHODS OF MINIMIZING CORROSION B-ll
RESEARCH NEEDS B-16
REFERENCES FOR PART B B-20
PART C FLAME STABILITY AS AFFECTED BY
COMBUSTION MODIFICATIONS *
INTRODUCTION AND OVERVIEW C-1
FLAME STABILITY C-5
COMBUSTION NOISE C-29
REFERENCES FOR PART C C-67
(*) Each Part has its own separate detailed Table of Contents.
IV
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ABSTRACT
As a basis for R&D planning directed to the control
of air-pollutant emissions, an EPA grant study was undertaken
by Battelle-Columbus Laboratories (1) to characterize the cur-
rent field population of industrial boilers, (2) to identify
trends in boiler design, and (3) to assess operating problems
associated with combustion modification.
Statistics supplied by the American Boiler Manufac-
turers Association were analyzed by Battelle to describe the
field population and recent sales trends for firetube and
watertube industrial boilers in the range from 10 million to
500 million Btu/hr. Aspects considered were boiler capacity,
design type, mode of erection, primary and secondary fuels,
firing method for coal, plus the industrial classification and
geographic region of the boiler installation.
When combustion modifications are employed to control
nitrogen oxide emissions from industrial boilers, practical
operating problems may arise, namely: (1) fireside corrosion
and deposits on boiler tubes and (2) flame instability--in-
cluding blow-off, flashback, combustion-driven oscillations,
and combustion noise or roar. These problems were assessed,
and research needs were identified in relation to such com-
bustion modifications as low-excess-air operation, staged com-
bustion modification, and flue-gas recirculation.
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ACKNOWLEDGMENT
The authors acknowledge the helpful comments
of D. G. Lachapelle, EPA Project Officer, on various
aspects of this study.
A special acknowledgement and thanks are due
to the American Boiler Manufacturers Association for
their cooperation in making available their extensive
statistics on boiler sales, to the ABMA committee per-
sonnel that contributed significant information and
comments, and to ABMA Assistant Executive Director,
W. H. Axtman, for his in-depth suggestions during the
course of the study on boiler population and trends.
The authors also acknowledge comments of others repre-
senting boiler manufacturers, utilities, and research
organizations that were contacted as part of the study.
Additional Battelle staff made significant
contributions to the study. T. J. Thomas handled the
computer programming to analyze boiler statistics, and
the following staff provided valuable insight based
on their experience: D. A. Ball, R. E. Barrett, R. B.
Engdahl, H. R. Hazard, R. D. Giammar, and A. E. Weller.
Vi
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DESIGN TRENDS AND OPERATING PROBLEMS IN
COMBUSTION MODIFICATIONS OF INDUSTRIAL BOILERS
by
D. W. Locklin, H. H. Krause, A. A. Putnam,
W. T. Reid, E. L. Kropp, and M. A. Duffy
March, 1974
Final Report
to the
U. S. ENVIRONMENTAL PROTECTION AGENCY
on
Grant No. 802402
EXECUTIVE SUMMARY
Fossil-fuel utilization in industrial boiler plants for steam
generation is almost as great as in utility boiler plants for electrical
generation. Thus, reduction of nitrogen oxide emissions from industrial
boilers represents a significant need for air-pollution control among
stationary sources.
Industrial boilers were defined for this study as steam or hot-
water boilers encompassing the range of capacity from 10 to 500 million
Btu/hr output (corresponding to the range from 10,000 to 500,000 Ibs of
steam per hour). Boilers in this size range serve a number of functions
for industry: generation of steam or hot water for space heating, process
steam, on-site power, or combinations of these.
Efforts to control emissions of nitrogen oxides from industrial
boilers by combustion modification may result in operating problems arising
from the steps taken to modify the combustion process. The principal
problems anticipated are (1) fireside corrosion and deposits on boiler tubes
and (2) flame instability.
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OBJECTIVES AND SCOPE
The overall objectives of this grant are to assemble background
information and to make recommendations in support of research planning
on problems associated with combustion modification of industrial boilers,
Three separate tasks cover the following areas:
Task A. Information on design features and design
trends in industrial boilers, including the
composition of the current field population
and an assessment of the applicability of com-
bustion modification techniques to various
boiler types. Trends in boiler design were
assessed by analysis of recent boiler sales in
the industrial size range.
Task B. Fireside corrosion and deposits in boilers
as affected by combustion modification.
Task C. Flame stability as affected by combustion
modifications, including considerations of
flame blow-off and combustion-driven
oscillations.
A. INDUSTRIAL BOILER POPULATION AND DESIGN TRENDS "
Published statistics on industrial boiler installations do not
include the detailed breakdown needed to characterize the boiler popula-
tion, boiler design types, fuel capability, or firing method by capacity
range.
To provide this type of information on the current field popula-
tion for purposes of another EPA contract on commercial boilers, a special
survey was made in 1972 by Battelle in cooperation with the American Boiler
Manufacturers Association (ABMA). Those data also cover the industrial
boiler range and are included in this report as the basis for characterizing
the current field population; however, new forecasts of future fuel trends
are offered on the basis of more recent developments in the fuel outlook.
Trends in boiler design were assessed by analysis of recent boiler sales in
the industrial size range.
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Recent Sales. Statistics on sales of watertube and firetube
boilers were analyzed from ABMA data covering recent years. For water-
tube boilers, the basic type of boiler design in the larger industrial
sizes, ABMA made available computer input data for individual boiler
sales recorded during the 8-year period, 1965-1973. Computer summaries
were then recorded, considering the following aspects:
• boiler output capacity
• boiler design type
• erection mode, field or shop erected
• fuel capability
• firing method (for coal)
• year of sale
• industrial classification of customer
• region of customer.
Table 1 lists the approximate distribution of recent boiler
installations by capacity ranges. Four size classes are identified,
covering industrial boiler capacities in the range from 10 to 500 mil-
lion Btu/hr.
C
D
TABLE 1. .DISTRIBUTION OF RECENT SALES OF
INDUSTRIAL SIZE BOILERS BY SIZE
RANGE
Size
Class
Capacity
Range ,
10b Btu/hr
Percent of
Industrial
Boiler
Units
Percent of
Total
Industrial
Capacity
Comment on
Predominant Types
10-16
17-100
101-250
251-500
35
53
11
10
45
36
9
Nearly all are firetube
boilers of various types.
About 75% are watertube
boilers, mostly packaged.
All are watertubc boilers,
about 70% field erected.
All are watertube boilers,
over 807o field erected.
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Detailed tables are included in the report, and general con-
clusions are summarized for each of these aspects.
Combustion Modifications. An assessment was made of the over-
all applicability of various boiler designs for combustion modification.
Modifications included in the appraisal were the following:
• burner design
• low-excess-air firing
• steam or water injection
• biased firing
• staged combustion
• flue-gas recirculation.
No attempt was made in this study to assess the effectiveness of the modi-
fications in reducing NO emissions, as this aspect is being covered in
A
other investigations.
B. FIRESIDE CORROSION AND DEPOSITS
AS AFFECTED BY COMBUSTION MODIFICATION
The effects of combustion modifications on boiler corrosion
and deposits have been assessed in Task B. Consideration has been
given to combustion with low-excess air, two-stage firing, and flue-gas
recirculation.
Low-Excess Air. Firing with low-excess air requires that
stoichiometric combustion conditions be approached as closely as possible.
In the best practice, this has meant that the excess air is maintained
at 1 percent (0.2 percent oxygen). With the presently available techno-
logy, this condition can only be achieved in oil and gas firing. Low-
excess-air combustion essentially eliminates the formation of sulfur
trioxide (SO ) and produces substantial reductions in corrosion. The
formation of pyrosulfates and trisulfates in high-temperature zones is
minimized, and sulfuric acid corrosion in low-temperature zones is pre-
vented. The formation of low-melting vanadium compounds in residual-oil
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firing also is inhibited. The benefits of firing with low-excess air are
not yet available to coal-fired systems, and new research needs to be con-
ducted in this area.
Staged Combustion. Both the fuel-rich zone and the transi-
tion zone in two-stage combustion can be a source of corrosion and
deposit problems. Sulfide corrosion is likely to occur in areas that
are subject to reducing conditions, because the sulfur in the fuel will
not be oxidized to SO . This condition is particularly serious in coal-
firing, where the pyrites (FeS ) may not be completely oxidized.
The reducing atmosphere of staged combustion also can lead
to potential problems with incompletely oxidized carbon, particularly
in the transition zone, where alternating oxidizing and reducing con-
ditions can occur. Formation of carbon monoxide in this zone can result
in removal of protective iron oxide layers on boiler tubes. New tube
metal will then be oxidized when the conditions reverse, thus accelerating
corrosion.
The problems that may result from partially oxidized sulfur
and carbon possibly can be overcome by air-management practices. Proper
blanketing of vulnerable areas with air would be required to insure
that oxidation to CO and SO will occur, without formation of SO . The
use of special alloy steels with high chromium content that will resist
sulfide corrosion and oxidation also offers a potential solution to the
problems of staged combustion. Investigation of the use of chrome ore
for tube protection also is recommended.
Flue-Gas Recirculation^ Flue-gas recirculation can provide
the benefits of lowered SO , but it can also introduce the problems of
partially oxidized sulfur and carbon. Careful design of equipment is
required to minimize these potential problems.
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R&D Recommendations. Research is needed on several problem
areas in burning pulverized coal with low-excess air. To make this
approach feasible, it will be necessary to investigate several variables
with respect to low-excess-air operation: coal particle size, coal
rank, burner design, air-fuel ratio, and type of firing.
Methods for preventing corrosion in (1) sulfide attack
under fuel-rich conditions, and (2) metal wastage by alternate oxidizing
and reducing conditions should be investigated. An improved corrosion
probe concept needs design and development.
C. FLAME STABILITY
AS AFFECTED BY COMBUSTION MODIFICATION
Utilizing various combustion modification techniques to con-
trol NO^ emissions from industrial boilers can lead to severe flame
stability problems. Because flame stability is directly related to the
basic fuel parameters of burning velocity and critical velocity gradient,
either a change in fuel composition in critical regions in the combustion
system or a change in the burner can alter these parameters and affect
the stability of a burner-furnace system. The flame stability criteria
of a burner-furnace system must not only be considered in relation to
traditional terms of flash-back, blow-off, and quenching potential, but
also in relation to criteria associated with combustion-induced noise.
In Task C, basic data on flame instability that were available
in the literature were applied to industrial-boiler systems to predict
the potential of flame instability from combustion modification. A
general correlation for predicting the effects of recirculated products
at arbitrary temperatures on burning velocity and critical velocity
gradient was developed and utilized to predict relative effects of
various design changes on the stability limits of a combustion system.
It was shown that recirculation without excessive cooling of the recir-
culated gases could actually increase the maximum firing rate (excluding
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the effect of increased pressure drop through the heat exchanger).
Additional cooling will decrease the limits. The effect of two-stage
combustion depends on the details of the furnace-burner system, and
may either increase or decrease the operating range. Steam or water
injection will decrease the stability limits.
Combustion Noise. Four different types of combustion noise
were considered: (1) combustion-driven oscillations, (2) combustion
roar, (3) unstable combustion noise generated by the precursor of the
blow-off conditions of a flame, and (4) amplified noise of periodic
flow phenomena. On the basis of present technology, it was not possible
to make specific predictions as to the effects on noise of various
combustion modifications; however, several positive conclusions can
be drawn.
First, problems of combustion-driven oscillations are common
in the development of any new burner-furnace system. The conversion
of combustion systems to use of two-stage combustion, recirculation,
or other modifications, can be expected to produce some incidence of
such problems. However, because of the urgency for trials to investi-
gate combustion modification as a means of NO control and the large
X
number of potential conversions of existing units, the problem will be
amplified. Second, changes in design that lower the stability limits
will increase the incidence of combustion-driven oscillations and the
intensity of combustion roar. Third, the use of cooled recirculated
products and/or steam will decrease the noise output. Fourth, two-stage
combustion will increase combustion roar and the propensity for
combustion-driven oscillations.
R&D Recommendations. Although flame-stability and combustion-
noise problems can be anticipated when combustion systems for industrial
boilers are modified for NO control, an awareness of potential problems
X
during engineering design can help to minimize the extent of problems.
New R&D directed to these areas can provide a broader design oasis for
solutions to problems related to stability and noise under conditions ot
combustion modifications.
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Specific research that should be carried out concerns (1)
the determination of stability limits data and corresponding predictive
rules on industrial-type burners (as contrasted to laboratory burners)
using both present fuels and contemplated fuels, (2) experimental deter-
mination of acoustic impedance characteristics of furnace and ducting
components, (3) experimental determination of basic acoustic spectra of
industrial burners using present and contemplated fuels.
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PART A
INDUSTRIAL BOILER POPULATION AND DESIGN TRENDS
by
D. W. Locklrn and E. L. Kropp
Battelle-Columbus Laboratories
March, 1974
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A-ii
PART A
INDUSTRIAL BOILER POPULATION AND DESIGN TRENDS
TABLE OF CONTENTS
Page
OBJECTIVES OF TASK A_j_
BACKGROUND AND SCOPE A-1
Significance of Industrial Steam Generation A-3
Available Statistical Information A-5
OVERALL CONCLUSIONS A_8
Current Field Population of Boiler Trends A-8
Recent Sales of Watertube Boilers A-11
Recent Sales of Firetube Boilers A-14
Inventory of Installed Capacity A-15
Applicability of Combustion Modification A-16
SURVEY OF FIELD POPULATION OF INDUSTRIAL BOILERS A-17
Tables Summarizing Survey Results A-17
Revisions From Previous Survey A-25
Information Analyzed A-27
Explanation of Summary Tables From Analysis A-29
Summary Tables for Recent Sales of Watertube Boilers. . A-30
RECENT SALES OF FIRETUBE BOILERS A_72
Recent Boiler Sales in Terms of Total Capacity A-75
Inventory of Installed Capacity of Current Boiler
Population A-75
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A-iii
TABLE OF CONTENTS (Continued)
Page
APPLICABILITY OF COMBUSTION MODIFICATION TO INDUSTRIAL
BOILERS A_ 79
REFERENCES FOR PART A A_81
LIST OF TABLES
TABLE A-l. CAPACITY RANGE FOR INDUSTRIAL BOILERS IN
APPROXIMATELY EQUIVALENT UNITS A-2
TABLE A-2. INDUSTRIAL AND UTILITY USE OF FOSSIL FUELS A-3
TABLE A-3. POPULATION BREAKDOWN BY BOILER TYPES (PERCENTAGE
BASIS) FOR ALL COMMERCIAL-INDUSTRIAL BOILERS NOW
IN SERVICE IN U.S A-19
TABLE, A-4. POPULATION BREAKDOWN BY FUEL CAPABILITY (PERCENTAGE
BASIS) FOR ALL COMMERCIAL-INDUSTRIAL BOILERS
NOW IN SERVICE A-20
TABLE A-5. POPULATION BREAKDOWN BY BURNER TYPE (PERCENTAGE
BASIS) FOR ALL COMMERCIAL-INDUSTRIAL BOILERS
NOW IN SERVICE IN U.S A-21
TABLE A-6. ESTIMATED TRENDS OF BOILER TYPES (PERCENTAGE
BASIS) FOR ALL COMMERCIAL-INDUSTRIAL BOILERS
INSTALLED IN YEARS NOTED A-22
TABLE A-7. ESTIMATED TRENDS BY FUEL CAPABILITY (PERCENTAGE
BASIS) FOR ALL COMMERCIAL-INDUSTRIAL BOILERS
IN YEARS NOTED, INCLUDING CONVERSIONS A-23
TABLE A-8. ESTIMATED TRENDS BY BURNER TYPE (PERCENTAGE
BASIS) FOR ALL COMMERCIAL-INDUSTRIAL BOILERS
INSTALLED IN YEARS NOTED (INCLUDING CONVERSIONS). . . A-24
TABLE A-9. BOILER CAPACITY CATEGORY BY YEAR FOR WATERTUBE
BOILERS A_31
TABLE A-10.
TABLE A-10.
TABLE A-10.
BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH
PRIMARY OR ALTERNATE FUEL -- BITUMINOUS COAL .... A-32
BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH
PRIMARY OR ALTERNATE FUEL (Continued) — OIL .... A-33
BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH
PRIMARY OR ALTERNATE FUEL (Continued) -- NATURAL GAS. A-34
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A-iv
LIST OF TABLES (Continued)
Page
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH
PRIMARY OR ALTERNATE FUEL (Continued) -- WOOD WASTE . A-35
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH
PRIMARY OR ALTERNATE FUEL (Continued) -- BAGASSE. . . A-36
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH
PRIMARY OR ALTERNATE FUEL (Continued) — BLACK
LIQUOR A-37
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH
PRIMARY OR ALTERNATE FUEL (continued) — OTHER FUELS. A-38
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH
PRIMARY OR ALTERNATE FUEL (Continued) — WASTE HEAT . A-39
TABLE A-ll. ERECTION METHOD BY CAPACITY CATEGORY FOR WATERTUBE
BOILERS A-40
TABLE A-12. FIRING METHOD BY CAPACITY CATEGORY FOR SOLID
FUELD — BITUMINOUS COAL A-41
TABLE A-12. FIRING METHOD BY CAPACITY CATEGORY FOR SOLID
FUELS (Continued -- WOOD WASTE A-42
TABLE A-12. FIRING METHOD BY CAPACITY CATEGORY FOR SOLID
FUELS (Continued) -- BAGASSE A-43
TABLE A-13. PRIMARY FUEL BY BOILER CAPACITY CATEGORY FOR
WATERTUBE BOILERS A-44
TABLE A-14. ALTERNATE FUEL BY CAPACITY CATEGORY FOR WATERTUBE
BOILERS A-46
TABLE A-15. PRIMARY FUEL BY CAPACITY CATEGORY FOR EXPORTED
WATERTUBE BOILERS A-48
TABLE A-16. PRIMARY FUEL BY YEAR SOLD FOR WATERTUBE BOILERS . . . A-49
TABLE A-17. PRIMARY FUEY BY ALTERNATE FUEL FOR WATERTUBE
BOILERS A-53
TABLE A-18. ERECTION METHOD BY PRIMARY FUEL FOR WATERTUBE
BOILERS '. A-55
TABLE A-19. ERECTION METHOD BY YEAR FOR WATERTUBE BOILERS .... A-56
TABLE A-20. FIRING METHOD FOR COAL BY YEAR FOR EACH WATERTUBE
CAPACITY CATEGORY -- 10-16 KPH A-57
TABLE A-20. FIRING METHOD FOR COAL BY YEAR FOR EACH WATERTUBE
CAPACITY CATEGORY (Continued) -- 17-100 KPH A-58
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A-v
LIST OF TABLES (Continued)
Paee
TABLE A-20. FIRING METHOD FOR COAL BY YEAR FOR EACH WATERTUBE
CAPACITY CATEGORY (Continued) -- 101-250 KPH A-59
TABLE A-20. FIRING METHOD FOR COAL BY YEAR FOR EACH WATERTUBE
. CAPACITY CATEGORY (Continued) -- 251-500 KPH A-60
TABLE A-20. FIRING METHOD FOR COAL BY YEAR FOR EACH WATERTUBE
CAPACITY CATEGORY (Continued) -- 500 KPH A-61
TABLE A-21. PRIMARY FUEL BY STANDARD INDUSTRIAL CODE FOR
WATERTUBE BOILERS A-62
TABLE A-22. PRIMARY FUEL BY GEOGRAPHIC REGION FOR WATERTUBE
BOILERS A-70
TABLE A-23. RECENT SALES OF PACKAGED SCOTCH FIRETUBE BOILERS
BY CAPACITY (1965-1972) A-73
TABLE A-24. SALES OF PACKAGED SCOTCH WATERTUBE BOILERS BY
YEAR AND FUEL - (1965-1972) A-74.
TABLE A-25. SUMMARY OF SALES OF PACKAGED SCOTCH FIRETUBE
BOILERS -- NUMBER OF UNITS AND TOTAL CAPACITY
BY SIZE CATEGORIES (1965-1972) A-76
TABLE A-26. SALES OF WATERTUBE BOILERS — NUMBER OF UNITS
AND TOTAL INSTALLED CAPACITY (1965-October 1973). . . A-76
TABLE A-27. INVENTORY ESTIMATE OF TOTAL INSTALLED CAPACITY
FOR INDUSTRIAL BOILERS A-77
TABLE A-28. APPLICABILITY OF COMBUSTION MODIFICATION TO
VARIOUS TYPES OF BOILERS A-80
FIGURE
FIGURE A-l. TOTAL ANNUAL INSTALLED CAPACITY OF INDUSTRIAL
BOILERS -- DISTRIBUTION BY BOILER SIZE FOR
WATERTUBE AND PACKAGED SCOTCH FIRETUBE BOILERS
Page
A-78
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PART A
INDUSTRIAL BOILER POPULATION AND DESIGN TRENDS
by
D. W. Locklin and E. L. Kropp
BATTELLE
Columbus Laboratories
OBJECTIVES OF TASK
Boilers for industrial steam raising are significant users of
fossil fuels and, thus, are important in considerations of air-pollution
control from stationary sources.
To provide a broader basis for R&D planning directed to the con-
trol of air-pollutant emissions from industrial boilers, this task had the
following objectives:
1. To characterize the current field population of
industrial boilers
2. To identify trends in boiler design
3. To assess the overall applicability of various boiler
designs for combustion modifications to control
nitrogen oxides.
BACKGROUND AND SCOPE
Definition of Capacity Range for Industrial Boilers
The capacity range typically designated for industrial boilers is
from 10 million to 500 million Btu/hr output. This range is large : than
"commercial boilers" and smaller than "utility boilers", even though industrial-
type boilers are sometimes used for electrical generation by utilities (including
municipal utilities and rural cooperatives).
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A-2
Table A-l shows this capacity range in other approximately equiva-
lent units of output and fuel input.
TABLE A-L. CAPACITY RANGE FOR INDUSTRIAL BOILERS
IN APPROXIMATELY EQUIVALENT UNITS
Capacity Rating
Minimum
Capacity
Maximum
Capacity
Boiler Output Units
Btu/hr output
(a)
Pounds steam/hr output, PPH
Boiler horsepower
10,000,000
10,000
300
500,000,000
500,000
Fuel Input Units ^
Oil input gallons/hr
barrels/day
Gas input, cubic feet/hr
Coal input, Ib/hr
tons/day
83
48
12,000
1,000
12
4,200
2,400
620,000
50,000
600
a. Based on equivalent output of saturated steam.
b. One boiler horsepower is equivalent to approximately 33,500 Btu/hr
output. Boiler horsepower ratings are commonly used for firetube boilers,
which are generally available only in sizes up to about 900 boiler
horsepower.
c. Assuming full-load operation at 80 percent boiler efficiency and
fuel heating value 150,000 Btu/gal for residual oil, 1,000 Btu/cubic
foot for natural gas, and 12,500 Btu/lb for coal.
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A-3
Significance of Industrial Steam Generation
Table A-2 shows the usage of fossil fuels for major industrial
applications in comparison to the total usage of all sectors and to the
utility sector. Steam generation is the predominant industrial use and
is almost as large in fuel consumption as the utility sector.
TABLE A-2. INDUSTRIAL AND UTILITY USE OF FOSSIL FUELS
(1)
Trillions of Btu's
for base year 1968
All
Fossil
Fuels
Coal
Oil
Gas
TOTAL - ALL SECTORS
UTILITY SECTOR TOTAL
INDUSTRIAL SECTOR TOTAL
Fuel-Fired in Boilers for
Steam Generation
59,639 13,326 26,749 19,564
11,556 7,130 1,181 3,245
19,348 5,616 4,474 9,258
Process & Space Heating
Electricity Generated On- site
Fuel Used for Direct-Heat
Applications (not including
purchased electrical energy)
Fuel Used as Feedstocks
10,132
410
6,604
2,202
2,349
95
3,025
147
1,986
80
808
1,600
5,797
235
2,771
455
Boiler firing accounts for 54 percent of industrial-fuel usage;
nearly all of this energy input is for steam or hot water used in process or
space heating applications, and only a small fraction represents steam for
generation of on-site electrical power. In the base year, gas provided
approximately 57 percent of the fuel input to boilers for industrial steam
generation, with coal and oil contributing 23 and 20 percent, respectively.
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A-4
Fuel Trends
The coal share of the industrial market has declined steadily in
the past few decades, with increasing use of natural gas and oil. The
growth of gas usage reflects the recent low cost of gas in many areas and
the low capital cost and low operating cost of gas-fired-packaged boilers.
The decline in the share of coal reflects, similarly, the high capital and
operating cost of coal-fired steam plants which must include coal storage
and handling, air-pollution control, and ash disposal. In many new plants
these problems are minimized by installing low-cost-packaged boilers to burn
gas or oil.
Interest in air-pollution abatement in recent years has also tended
to increase,conversions of coal-fired plans to gas or to low-sulfur oil,
adding to the demand for these clean fuels. However, as clean fuels become
less available, it appears probable that the industrial sector will be forced
to rely increasingly upon coal and residual oil.
Types of Industrial Boilers
Industrial boilers can be categorizedv ' into the following basic
types:
• Watertube construction
- Packaged or shop erected
- Field erected
• Firetube Construction
- Packaged Scotch
- Firebox
- Horizontal return tubular
- Miscellaneous types
Design features typical of these types of boilers are discussed and illustrated
in references 3 through 7 and will not be described here.
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A-5
Available Statistical Information
The following discussion provides comments on the availability,
use, and limitations of statistical information on industrial boilers from
various sources.
Field Population Distribution. Previously published statistics
on industrial-boiler installations do not include the level of detailed
breakdown as desired to characterize the boiler population on boiler design
types, fuel capability, and boiler capacity.
To provide this type of information on the boiler field population
for purposes of another EPA investigation on emissions from commercial boilers,
a special survey was made in 1972 by Battelle in cooperation with the American
Boiler Manufacturers Association (ABMA). That survey covered the entire
commercial-industrial-boiler range, and data are included in this report as the
basis for characterizing the current field population. The survey also
indicated past trends since 1930 and a forecast to 1990. However, new fore-
casts of future fuel trends are offered in this report to reflect an appraisal
of more recent developments in the outlook of fuels availability.
Recent Sales. To identify recent trends, statistics on sales of
watertube and firetube boilers were analyzed from ABMA data covering recent
years^ . For watertube boilers, the basic type of boiler design in the
larger industrial sizes, ABMA has made available their data on boiler sales
recorded during the period 1965 through October, 1973. Computer summaries
were then made considering the following aspects:
• boiler output capacity
• boiler design type
• erection mode, field or shop erected
• fuel capability
• firing method (for coal)
-------
A-6
• year of sale
• industrial classification of customer
• region of customer.
(9)
For firetube boilers, sales of packaged-Scotch boilers were
analyzed, based on ABMA statistics for the years 1965 to 1972. Packaged-
Scotch boilers are the predominant type of firetube boilers in the industrial-
size range; however, limited ABMA data provided an estimate of firebox-firetube
boilers in this size range.
Inventory of Boiler Installations. Unfortunately, there is no
fully satisfactory source of statistics on the actual number or the installed
capacity of boilers now in field service. Sales records, even if available
for many years, would not be adequate because a field conversion from one
fuel to another is not reflected in sales records. Boiler inspectors are
the only group that continues to monitor boilers after installation, but
they are concerned primarily with the safety of the pressure vessel and
do not record details of fuel use or burner fuel in a consistent reporting
procedure.
The most comprehensive inventory estimate of boilers from residential
to utility size was from an EPA study conducted by Walden^10^ which made use
of data and estimates from a variety of sources but did not provide breakdowns
to characterize the boiler population on a detailed basis. The Walden estimate
of total-installed capacity of industrial boilers in 1967 have been updated
in this report on the basis of ABMA data. The detailed information charac-
terizing the field population on a percentage basis can be applied to the
total inventory estimates to provide an insight as to the total capacity of
boilers with features of particular interest.
Power Magazine provides an annual statistical overview of industrial
boilers , but this is only a partial sampling and is not adequate to pro-
vide inventory information. This annual overview offers an opportunity to
judge boiler types and installation features, but it was not used in this
analysis.
-------
A-7
The National Environmental Data System (NEDS) is a new source of
information that may prove to be effective in estimating the total inventory
of large boilers as the coverage and reporting are improved. This EPA data
bank contains limited information on major boiler installations that have
been identified as "point sources" in the emission inventories compiled under
The Clean Air Act . Most states are represented, but several significant
industrial states are not yet included.
This system provides information for major installations on the
boiler capacity, fuel type, and estimated annual fuel consumption, but no
other details are available to characterize the boiler as to design or burner
type.
Another limitation is that the lower cut-off point of boiler capacity
for reporting may be variable with the practices of the reporting companies,
with the inventory-survey teams compiling data for various states, and for
different fuels according to an appraisal of annual emissions. These latter
criteria could also eliminate boilers which operate as standby or with very
low load factor. The inventory is probably more reliable for the largest
boilers with high-load factor and with coal-fired boilers where emission
factors would be highest.
In view of the foregoing limitations, the NEDS data were not used
in this study, except to compare the overall distribution of capacities in
coal-fired boilers in the largest sizes(13). However, the NEDS system appears
to offer a potential opportunity in the future to provide useful information
on an inventory of boilers in the largest sizes and, possibly, to be viewed
in conjunction with ABMA data.
-------
A-8
OVERALL CONCLUSIONS
An overview of conclusions resulting from the study is presented
in this section, covering separately the following aspects:
1. Survey of the current field population and
trends
2. Analysis of recent watertube boiler sales
installations
3. Analysis of recent firetube boiler sales
installations
4. Inventory of installed capacity
5. Applicability of combustion modification to various
types of industrial boilers.
The designations in the right-hand margin refer to tables or figures
that support the conclusions.
1. Current Field Population of Boiler Trends
The survey conducted for the API/EPA field measurement pro-
gram included a range of capacity comprising both commercial and in-
/Q\
dustrial boilers ; the following observations apply to industrial
boilers in the capacity range from 10,000 to 500,000 pounds steam
per hour (PPH).
Boiler Type
• In the industrial boiler size range, firetube boilers A-3
are the dominant construction type in the smaller sizes,
accounting for 78 percent of the boilers below 16,000
PPH; many of these are of package design. Watertube
boilers are dominant in the size range from 17,000 to
100,000 PPH, accounting for 79 percent of the boilers,
mostly package type. Essentially, all boilers above
30,000 PPH in capacity are of watertube construction,
with field erection for the larger sizes.
-------
A-9
• In the capacity range where firetube and watertube boilers A-6
overlap, little trend in sales is apparent in recent years,
so the relationship of the two types is expected to hold
relatively constant.
Package vs Field-Erected Boilers
• In firetube boilers below 30,000 PPH, packaged Scotch A-3
boilers and firebox boilers are most common. Cast-iron
boilers are generally not available in the industrial
size range.
• The trend in firetube boiler construction is to packaged A-6
Scotch boilers. Firebox boilers are expected to hold
their present position in smaller size ranges. In water-
tube construction, the trend is toward packaged boilers
and away from field-erected boilers, except in the
largest sizes.
Fuels
• Oil and gas firing are dominant over the full range of A-4
industrial boilers, with gas firing most prevalent as a
prime fuel for the smaller capacity and oil most prevalent
at larger capacities. Few boilers in the smaller sizes
have coal-firing capability, but the percentage increases
to nearly 30 percent in sizes about 250,000 PPH.
• Until the recent situation of fuel shortages, the trend A-7
in fuels has been toward oil and gas, with coal projected
in the previous survey to decrease even in larger sizes.
Revised projections show an increase in coal firing for
new installations in all sizes, but especially in capa-
cities above about 100,000 PPH.
-------
A-10
• Of the oil-fired installations, residual oil is predoroi- A-4
nate, mainly heavy No. 5 and No. 6 oil. Distillate oil
firing is significant only below about 16,000 PPH,
representing only 10 percent of oil firing in this range.
(In dual oil/gas burners, distillate oil firing is
more common.)
• A trend to distillate oil firing, away from residual oil A-7
and coal, has become apparent due to air-pollution con-
siderations. (However, this is likely to reverse for
large industrial boilers if fuels become allocated
according to priority uses.)
• For larger boilers, a return to coal firing in the near A-7
future is likely if supplies of oil and gas continue to
be limited.
Oil Burner Types
• Among oil, burners, air atomization and rotary atomization A-5
are the dominant types in the lowest capacities. Steam
atomization is dominant in larger capacities. Pressure
atomization is sometimes used in the low capacities.
• Present and forecast trends are away from rotary oil A-8
burners and toward air atomizing burners in smaller sizes
or steam atomizing in larger sizes.
Coal-Firing Method
• The underfeed stoker is by far the most common coal-firing A-5
method in boiler sizes up to about 100,000 PPH. The
spreader stoker is popular from 100,000 to 250,000 PPH.
Pulverized coal firing is dominant in larger sizes.
-------
A-11
• For coal firing of boiler capacities up to 100,000 PPH, A-8
the use of spreader stokers is forecast to increase.
Pulverized coal firing is expected to become more preva-
lent in sizes between 100,000 and 250,000 PPH.
Load Factor
• Annual load factor is a measure of boiler service usage
reflecting part-load operation; it is the ratio of fuel
quantity burned to the quantity that would be burned in
full-load operation. Annual load factor varies from about
25 percent for boilers used for space heating to as high
as 90 percent for boilers supplying steam for relatively
constant-process loads.
2. Recent Sales of Watertube Boilers
The following observations are made from the analysis of ABMA
records on watertube sales for the period, 1965 through October 1973.
Capacities
• Most watertube boilers sold were in the lower end of A-9
the capacity range. The range up to 100,000 PPH accounts
for 76 percent of the watertube boiler units. About 21
percent of the units were in the range 100,000 to 250,000
PPH, and only 21 percent were in the range 250,000 to
500,000 PPH. About 90 percent were in the range up to
250,000 PPH.
-------
A-12
• The total capacity of the non-utility watertube boiler A-25
was more evenly distributed between ranges. About 44
percent of the watertube capacity was in the range up to
100,000 PPH, about 41 percent was in the range 100,000
to 250,000 PPH, and only 10 percent in the range 250,000
to 500,000 PPH.
• There was a recent increase in the percentage of boiler A-9
units in the size category from 250,000 to 500,000 PPH.
Fuels
• Oil and gas were the dominant fuels in boiler sizes up A-10
to 500,000 PPH for sales during the past 8 years. A-13
Boilers identified with gas or oil firing capability A-17
account for 78 percent of all boilers (mostly as dual-
fuel units). Boilers with gas listed as primary fuel
accounted for 58 percent of the boilers, whereas oil
as-a primary fuel accounted for only 30 percent.
• Coal firing has declined during the period, from 14 A-10
percent of the boilers in 1965 to 4 percent in 1972
and 1973. Few new boiler installations have coal-firing
capability, except in sizes about 500,000 PPH, where
about 50 percent of boilers sold in the 8-year period
were coal fired. (In 1973, 92 percent of the boilers
ordered in this range were for coal firing.)
• Among other primary fuels (other than oil, gas, or coal), A-ll
wood waste was the most prevalent of those specifically A-13
identified. A substantial number of waste-heat boilers
were sold in the range below 100,000 PPH0
-------
A-13
Packaged vs Field-Erected Boilers
• Packaged boilers dominated the number of field-erected
boilers in the smaller size range, 9:1 up to 100,000
PPH and 3:1 between 100,000 and 250,000 PPH. The ratio
reversed to 1:5 between 250,000 and 500,000 PPH. In
larger boilers, nearly all were field erected.
• 80 percent of oil-fired boilers and 90 percent of gas-
fired boilers were package type. Field-erected boilers
account for 94 percent of coal-fired boilers.
Firing Method for Coal
• For coal firing, underfeed stokers were the principal
firing method for boiler capacities below 16,000 PPH.
Spreader stokers dominated the next range to 250,000
PPH, with pulverized coal dominating the larger sizes.
• Exports accounted for only about 2 percent of the
boilers during the period, mostly oil fired.
Geographic Distribution of Boilers and Primary Fuels
• The principal concentrations of industrial boiler sales
were in the Mid-Atlantic States and the East-North-Central
States. Each of these regions accounted for about 23
percent of the boiler sales. The next highest percentage
was 17 percent in the South-Atlantic States.
• Gas was the dominant fuel in all regions except the New
England States and the Mid-Altantic States; these latter
regions had 36 percent gas-fired boilers, compared to 59
percent on a national basis. Gas firing accounted for 72
percent of the boilers in the states west of the Mississippi
River and 68 percent in the East-North-Central States.
-------
A-14
• Oil was the dominant fuel in the Northeast, where much of A-22
industry is relatively accessible by water transportation.
Oil firing accounted for 64 percent of the boilers in New
England and 50 percent in the Mid-Atlantic States. (This
compares to 27 percent on a national basis.)
• Coal firing was strongest in the East-North-Central States, A-22
accounting for 42 percent of the coal-fired boilers in the
United States and 12 percent of boilers in those states.
The Mid-Atlantic States accounted for 18 percent of the coal-
fired boilers in the United States. (On a national basis,
7 percent of the boilers were coal fired.)
• Wood waste firing was the only significant nonfossil A-22
fuel, representing about 5 percent of the boilers in the
two Western regions.
3. Recent Sales of Firetube Boilers
Most of the recent firetube boilers in the industrial size
range (about 300 boile'r horsepower or 10,000 PPH) are packaged Scotch
type. The following observations are based on ABMA records on fire-
tube boiler sales in the commercial-industrial size range for the 8-year
period, 1965-1972.
• Boilers of the packaged Scotch type ranged in capacity A-24
from 10 to 900 boiler horsepower. The most popular size A-25
range was 100 to 300 boiler horsepower. About 14 percent
of the Scotch units were in the industrial size range, and
about 38 percent of the Scotch capacity was in this size
range.
• As for fuel firing capability, 30 percent of the Scotch A-23
boilers were equipped as dual-fuel boilers for oil or gas,
38 percent were equipped for oil only, and 32 percent for
gas only. (Scotch firetube boilers are generally not
equipped for coal firing.)
-------
A-15
• Over the 8-year period, there has been a trend to dual- A-23
fuel combination boilers from 24 percent in 1965 to
37 percent in 1972. In 1971 and 1972, units equipped
for oil only displaced gas-only units. (In 1972, 41
percent were oil only and 21 percent gas only, and 38
percent combination.)
4. Inventory of Installed Capacity
The following observations were made from an estimate of total
capacity of boilers in service within the industrial size range.
• It is estimated that the total installed capacity of A-26
industrial watertube and firetube boilers in service
at the end of 1972 was nearly 2.5 billion PPH. Of
this capacity, 90 percent was watertube construction.
• Of the industrial firetube capacity installed in the past A-24
8 years, 68 percent was in the range 301 to 500 boiler
horsepower, and 32 percent in the range above 500 horse-
power .
• Of the watertube capacity installed in the past 8 years, A-25
44 percent was in the size range 100,000 PPH and below,
41 percent was in the range 100,000 to 250,000 PPH, and
10 percent was in the range 150,000 PPH to 500,000 PPH.
Only 5 percent of the non-utility boilers were above
500,000 PPH.
-------
A-16
5. Applicability of Combustion Modification
The following generalizations result from considerations of A-16
the applicability of various combustion modifications for NO control
j£
to different types of industrial boilers, without regard to the
relative effectiveness of the modification.
• Water injection can be applied to any type of industrial
boiler.
• Except for coal firing, the combustion modifications which
are most readily applied to industrial boilers for NO
v
control are burner design, low-excess-air firing, and
water injection.
• Flue-gas recirculation and staged combustion are feasible
in many cases, but with considerable difficulty, for all
types of boilers. For stokers, staged combustion can be
considered only for new installations.
-------
A-17
SURVEY OF FIELD POPULATION OF INDUSTRIAL BOILERS
The most complete information available to characterize the
field population of industrial boilers was that developed in connection
with planning for the joint API/EPA field measurement program for
(Q\
emissions from commercial boilers. Because industry statistics did
not provide the desired detail on boiler and burner features, a special
survey of boiler manufacturers was conducted jointly by Battelle and ABMA.
Estimates of percentage distributions were requested to enable broad judge-
ments by respondents and provide an overall profile of the present field
population.
Tables Summarizing Survey Results
The composite results of that survey are reproduced in the
following tables (with revisions by Battelle as identified in the foot-
notes and as discussed in subsequent text).
Field Population
Breakdowns by capacity ranges of all commercial-industrial
boilers now in service in the United States (percentage basis).
Table A-3. By Boiler Types
Table A-4. By Fuel Capability
Table A-5. By Burner Type*
* Includes revisions on firing method for coal.
-------
A-18
Trends
Estimated distribution of features by capacity ranges describing
commercial-industrial boilers in service in the United States in years
1930, 1950, 1970, and the forecast for 1990.
Table A-6. By Boiler Types
Table A-7. By Fuel Capability (Revised **)
Table A-8. By Burner Type (Revised ***)
Principal observations from these data were presented in the previous
section on "General Conclusions".
** Includes revised projections of fuel use.
*** Includes revisions on firing method for coal.
-------
TABLE A-3. POPULATION BREAKDOWN BY BOILER TYPES (PERCENTAGE BASIS) FOR ALL
COMMERCIAL-INDUSTRIAL BOILERS NOW IN SERVICE IN U.S.
Commercial •
Industrial
RATED
CAPACITY.
SIZE RANGE
106 Btu/hr or
103 Ib rtm/hr
Boiler Horsepower
10-50
51-100
10-16
101-300
301-500
17-100
101-250
251-500
WATER TUBE
Industrial Type> 104 # Steam/hr
Packaged
Field erected
Commercial Type < 104 # Steam/hr
Coil
Firebox
Other
FIRE TUBE
Packaged Scotch
Firebox
Vertical
Horizontal Return Tubular (HRT)
Misc. (Locomotive type, etc.)
CAST IRON
MISC. (Tubalest. etc.)
TOTAL
COMMERCIAL-INDUSTRIAL
BOILERS
15
25
1
5
2
45
1
100%
20
25
0.5
10
3
33
0.5
100%
30
30
nil
15
5
15
nil
100%
100%
100%
100%
-------
TABLE A-4. POPULATION BREAKDOWN BY FUEL CAPABILITY (PERCENTAGE BASIS) FOR
ALL COMMERCIAL-INDUSTRIAL BOILERS NOW IN SERVICE
RATED
CAPACITY,
SIZE RANGE
FUELS
Oil Only
Gas Only
Coal Only
106 Btu/hr or
103 Ib stm/hr
Boiler Horsepower
Oil & Gas and Gas & Oil
Oil & Coal and Coal & Oil
Gas & Coal and Coal & Gas
Misc. Fuels
(alone or with alternate fuels)
OIL
Total
Distillate, No. 2
Resid
No. 4 and
Light No. 5 (No preheat)
Heavy No. 6 and No. 6 (Preheated)
Total Oil
10-50
42
50
2
5
1
100%
95
(5)
4.5
0.5
100%
51-100
42
-50
1
6
1
100%
85
(15)
14
1
100%
101-300
40
50
1
8
1
100%
50
(50)
30
20
100%
10-16
301-500
35
45
3
16
ymzmm%%'
'mmmm.
i
100%
10
(90)
20
70
100%
17-100
35
35
10
18
4ffiMMMMWM6fM4>
2
100%
2
(98)
2
96
100%
101-250
30
22
18
26
0.5
0.5
3
100%
2
(98)
nil
98
100%
251-500
22
22
22
23
3
3
5
100%
2
(98)
nil
98
100%
I
NJ
o
-------
TABLE A-5. POPULATION BREAKDOWN BY BURNER TYPE (PERCENTAGE BASIS) FOR ALL
COMMERCIAL-INDUSTRIAL BOILERS NOW IN SERVICE IN U. S.
106 Btu/hr or
RATED 1fl3 ib jtm/hr
SIZE RANGE Boj|er Horttpower
OIL BURNERS (approx. gph)
Air Atomizing
Steam Atomizing
Pressure or Mechanical Atomizing
Rotary
Total Oil
COAL BURNERS (aoDrox. Ib/hr)
Spreader
Underfeed
OvBrfeed
Pulverized
Other (Hand- fir Ing, Miscellaneous,
and Unreported)
Total Coal
- Commercial •
10-50
3-15
15
mmmm
70
15
100% •
33-160
nil
90
'%^^m>,
5
100%
51-100
15-30
35
25
40
100%
160-330
. 5
80
10
5
100%
101-300
30-90
40
20
40
100%
330-1000
10
75
5
100%
10-16
301-500
90-150
40
20
10
30
100%
1000-1600
15
70
10
V^MMt,
5
100%
17-100
150-900
15
70
10
5
100%
1600-10,000
20
60
5
100%
101-250
900-2250
5
85
10
100%
10.000-25.000 .
50
20
10
15
5
100%
251-500
2250-4500
1
94
5
100%
25.000-50.000
30
15
10
40
5
100%
>
-------
TABLE A-6. ESTIMATED TRENDS OF BOILER TYPES (PERCENTAGE BASIS) FOR
ALL COMMERCIAL-INDUSTRIAL BOILERS INSTALLED IN YEARS NOTED
- Commercial -
Industrial-
RATED
CAPACITY,
SIZE RANGE
106Btu/hr or
103 Ib stm/hr
Boiler Horsepower
10-50
51-100
101-300
10-16
301 -500
17-100
101-250
251-500
30 '50 '70 '90
30 '50 '70 '90
30 '50 '70 '90
WATER TUBE
Industrial Type > 104 # Steam/Hr
Packaged
Field erected
Commercial Type < 104 # Steam/Hr
Coil
Firebox
Other
FIRE-TUBE
Packaged Scotch
Firebox
Vertical
Horizontal Return Tubular (HRT)
Misc. (Locomotive type, etc.)
CAST IRON
MISC (TUBELESS, ETC)
TOTAL
COMMERCIAL-INDUSTRIAL
BOILERS
(13^15) (16) (21)
nil 2 3 5
8531
. 5 8 10 15
30 '50 '70 '90
(25)(17)(19)(20)
0 2 18 20
25 15 1 0
'30 '50 '70 '90
(94) (97) (94) (90)
0 8 80 89
94 89 14 1
•30 '50 '70 '90
100) (100) (100X100)
0 0 80 90
100 100 20 10
'30 'SO '70 '90
CLOO UOO) (100)0.00
0 0 1 20
100 100 99 30
(5) (11) (10) (14)
nil 3 4 5
3345
2524
nil 10 1L 10
6 11 18 20
5666
5 1 nil nil
8 5 3 2
60 50 45 40
3211
100 100 100 100
1 14 22 26
20 15 17 23
3532
5 2 nil nil
5111
50 45 40 36
3 2 1 nil
100 100 100 100
2 21 41 40
20 30 35 30
5 2 nil nil
60 25 1 nil
8 5 2 nil
nil 5 10 15
nil 111
100 100 100 100
ro
N3
-------
TABLE A-7. ESTIMATED TRENDS BY FUEL CAPABILITY (PERCENTAGE BASIS) FOR ALL COMMERCIAL-INDUSTRIAL
BOILERS INSTALLED IN YEARS NOTED, INCLUDING CONVERSIONS
106Btu/hror
RATED ID3 Ib stm/hr
CAPACITY,
SIZE RANGE BOJI,,, Horsepower
FUEL CAPABILITY
Oil Only
Gas Only
Coal Only
Oil & Gas and Gas & Oil
Oil & Coal and Coal & Oil
Gas & Coal and Coal & Gas
Misc. fuels
(alone or with alternate fuels)
Total
OIL
Distillate. No. 2
Resid
No. 4 & Light No. 5 (No preheat)
Heavy No. 5 & No. 6 (Preheated)
Total Oil
•" - Commercial *
10-50
'30 '50 '70 '90
20 40 30 20
LO 30 45 25
65 20 5 10
nil 5 18 40
5525
100 100 100 100
%
40 50 70 100
60) (50) (30) (nil)
40 40 25 nil
20 10 5 nil
00 100 100 100
%
-
51-100
'30 '50 '70 '90
10 30 25 10
10 30 38 10
75 15 5 15
nil 10 30 60
5 525
100 100 100 100
%
20 30 40 70
80) (70) (60) (30)
50 50 50 30 '
30 20 10 nil
100 100 100 100
%
101-300
'30 '50 '70 '90
10 40 30 10
5 25 30 5
80 10 5 20
nil 20 30 60
55 55
100 100 100 100
%
10 10 20 40
(90) (90) (80) (60)
30 40 30 5
60 50 50 55
00 100 100 100
%
10-16
301-500
'30 '50 '70 '90
17 43 30 13
5 20 30 6
75 10 5 30
nil 25 30 45
32 56
100 100 100 100
%
5 2 10 30
(95) (98) (90) (70)
20 23 10 nil
75 75 80 70
00 100 100 100
%
17-100
'30 'SO '70 '90
13 30 30 10
10 30 30 4
75 30 5 40
nil 5 30 40
2556
100 100 100 100
%
11 nil 10 20
100)(100)(90)60
11 5 nil nil
00 95 90 80
00 100 100 100
%
101-250
'30 '50 '70 '90
5 20 24 nil
5 20 24 nil
90 38 15 50
nil 10 25 30
nil 5 5 10
nil 5 55
nil 2 25
100 100 100 iOO
%
nil nil 5 10
J 00) (100) (95) (90)
11 nil nil nil
00 100 95 90
00 100 100 100
%
251-500
'30 '50 '70 '90
5 15 20 nil
5 15 20 nil
90 60 20 60
nil 5 20 20
nil 3 10 10
nil 2 10 5
nil nil nil 5
100 100 100 100
%
nil nil 5 10
J00)(100)(95)(90)
nil nil nil nil
100 100 95 90
100 100 100 100
%
rO
LO
-------
TABLE A-8. ESTIMATED TRENDS BY BURNER TYPE (PERCENTAGE BASIS) FOR ALL COMMERCIAL-INDUS TRIAL
BOILERS INSTALLED IN YEARS NOTED (INCLUDING CONVERSIONS)
• Commercial
Industrial
RATED
CAPACITY.
SIZE RANGE
OIL BURNERS
106 Btu/hr or
103 Ib stm/hr
Boiler Horsepower
Air Atomizing
Steam Atomizing
Pressure or Mechanical Atomizing
Rotary
Total Oil
COAL BURNER
Spreader
Underfeed
Overfeed
Pulverized
Other (Including refuse, sawdust,
and wood)
Total Coal
10-50
30 'SO '70 '90
10 15 15 "15
70 75 85 85
20 10 nil nil
100 100 100 100
ill nil nil nil
50 95 95 95
nil nil nil nil
50 5 5 5
100 100 100 100
5MOO
'30 '50 '70 '90
15 20 30 30
55 60 65 70
30 20 5 nil
100 100 100 100
ill 5 10 20
50 60 75 70
40 30 10 5
10 5 5 5
100 100 100 100
101-300
•30 '50 '70 '90
20 30 55 60
50 40 40 40
30 30 5 nil
100 100 100 100
nil 10 20 25
55 65 70 70
35 20 10 5
10 5 55
100 100 100 100
10-16
301-500
•30 '50 '70 '90
10 20 35 40
30 30 35 40
25 20 20 20
35 30 10 nil
100 100 100 100
nil 10 25 35
60 60 70 50
35 25 nil 10
555 5
100 100 100 100
17-100
'30 '50 "70 '90
53 21
75 80 88 90
15 14 10 9
5 3 nil nil
100 100 100 100
nil 40 50 65
60 25 15 10
35 30 25 15
5 5 5 10
100 100 100 100
101-250
'30 '50 '70 "90
2 1 nil nil
93 94 95 95
5555
100 100 100-100
nil 50 60 35
50 20 nil nil
45 15 10 10
nil 10 20 40
55 10 15
100 100 100 100
251-500
'30 '50 '70 '90
2 1 nil nil
93 94 95 95
5555
100 100 100 100
nil 25 10 5
25 10 nil nil
60 10 nil nil
10 50 80 85
5 5 10 10
100 100 100 100
>
ro
-------
A-25
Revisions From Previous Survey
The following comments refer to the revisions made in the
(8)
summary of the previous survey of field population and sales trends.
Fuel Projections. In Table A-7, the projection of fuels for
the year 1990 were revised by Battelle to reflect changes in availability
of fuels which might be expected in light of the overall energy situation.
The projections were made on a judgmental basis, with the following
broad assumptions:
1. That oil and gas supplies will be limited
2. That oil and gas will be utilized in smaller
equipment and for high-priority uses (but not by
100-percent mandatory allocation)
3. That coal will dominate new installations in the
larger sizes
4. That clean liquid and gaseous fuels from coal
conversion processes will not be available in
large quantities by 1990
5. That firing of any available supply of SNG or low-
Btu gas will be included in the estimate for gas
firing, and any available supplies of liquid fuels
from coal will be included in the estimates for oil
firing. (Pulverized firing of chemically refined
solid fuels will be included under coal firing)
6. Refuse firing as a supplementary fuel will increase,
but will not become significant in terms of
percentages.
Firing Method. The information on firing method for coal
and other solid fuels was revised for Tables A-5 and A-8. These esti-
mates were made judgmentally, based on the analysis of recent sales
data for watertube boilers (reported in a subsequent section of this
report), plus overall judgment of Battelle and ABMA staff familiar with
solid fuel firing.
-------
A-26
Load Factors. Most industrial boilers do not operate contin-
uously at full load. Load factor (or usage factor) is of interest to
allow estimates of fuel use where this is necessary. Load factor is
defined as the ratio of actual fuel used per year to the calculated usage
per year at constant full-load operation. The following provides infor-
mation on typical load factors for boilers serving different functions:
Typical Range for
Range Factor,
Type of Load percent
Space heating 20-30
General commercial uses 30-60
General industrial uses 50-80
Industrial processing 75-90
Power generation 10-90
An analysis of large coal-fired industrial boilers in the NEDS
data bank revealed an average load factor of about 55 percent.
-------
A-27
ABMA records of watertube boiler sales during the last 8 years
were analyzed. Through a special agreement for purposes of this EPA grant,
ABMA made available to Battelle their data file on watertube boiler sales
for the years 1965 through October, 1973. These records were in the form
of computer cards for each boiler sale, coded with detailed information
concerning boiler capacity, erection method, fuels, industrial classification
of customer, and other data as noted below.
Information Analyzed
• Capacity Per Unit:
Boiler capacity reported in thousands pounds of steam
per hour as the maximum capacity when fired with pri-
mary fuel.
To facilitate comparison with the field population
survey, Battelle aggregated individual boiler capa-
cities into five boiler capacity categories as
follows:
A. 10 to 16 KPH*
B. 17 to 100 KPH
C. 101 to 250 KPH
D. 250 to 500 KPH
E. Over 500 KPH
(generally utility boilers)
• Primary Fuel:
- Bituminous Coal - Wasteheat
- Oil - Wasteheat, auxiliary firing
- Natural Gas - Lignite
- Wood, Bark, or Solid Wood - Raw Municipal, unsorted
- Bagasse - Raw Municipal, non-
- Black Liquor combustible removed
- Other Fuels - Raw Municipal, sorted &
sized
- Other Industrial Waste
* Boiler capacity categories in the statistical tables which follow are in
thousand pounds of steam per hour rated output (KPH).
-------
A-28
Alternate or Auxiliary Fuel:
Same as list above for primary fuel
- Gas turbine or engine exhaust
- Other non-combustible waste gas
- Combustible waste gas
- Non-solid fuel firing
• Firing Method:
- Pulverized coal
- Spreader stoker
- Underfeed stoker
- Overfeed stoker
- Other solid fuel firing
• Packaged or Field Assembled:*
- Pressure vessel completely shop assembled
- Pressure vessel shop assembled and shipped as two, three,
four, five, or six major modules
- Packaged design shipped knocked-down
- Field assembled, bottom supported
- Field assembled, top supported
• Standard Industrial Classification Number
• Domestic or Export
• Geographic Region (by number code as follows:)
1. New England States
Connecticut, Maine, Massachusetts, New
Hampshire, Rhode Island, Vermont
2. Mid-Atlantic States
Delaware, Maryland, New Jersey, New York,
Pennsylvania, Virginia, West Virginia
3. East-North-Central States
Illinois, Indiana, Kentucky, Michigan,
Ohio, Wisconsin
4. South-Atlantic States
Alabama, Florida, Georgia, Mississippi,
North Carolina, South Carolina, Tennessee
5. West-North-Central States
Iowa, Kansas, Minnesota, Missouri,
Nebraska, North Dakota, South Dakota
6. West-South-Central States
Arkansas, Louisiana, Oklahoma, Texas
7. Rocky Mountain States
Colorado, New Mexico, Utah, Wyoming
* For purposes of the analysis for method of erection, all boilers were
considered "packaged boilers", except those identified as "field
assembled".
-------
A-29
8. Northwestern States
Idaho, Montana, Oregon, Washington
9, Southwestern States
Arizona, California, Nevada
Explanation of Summary Tables From Analysis
The computer program used to summarize the information on recent
sales of watertube boilers was the SPSS statistical package*. SPSS contains
subprograms which allow the examination of relationships between variables
in a table-type format. They permit display of frequency distributions
with varying levels of control variables. The following explanation applies
to Tables A-9 through A-22.
Table Format. The body of each table contains blocks with
numerical information. The upper left corner of the table describes what
the numbers represent; e.g., COUNT is the number of boilers in the block;
ROW PCT is the row percentage of a given block of the total number in the
row; COL PCT is the column percentage of a given block of the total number
in the column; and TOT PCT is the percentage of a given block of the total
number in the table.
The phrase "Number of missing observations = n" may appear at
the bottom of the table. This means that of the total cases examined for
a table, there were some cases for which either a row variable or a
column variable was missing, so that the case could not be classified.
SPSS is a set of commercial computer programs available from Vegelback
Computing Center, Northwestern University. (13)
-------
Tables A-9 through A-22 are in the format described above and present statistical
analyses for the following cases:
Table Pages
A-9 31
A-10 32-39
A-ll
A-12
A-13
A-14
A-15
A-16
A-17
A-18
A-19
A-20
A-21
A-22
40
41-43
44-45
46-47
48
49-52
53-54
55
56
57-61
62-69
70-71
Description of Tables
Capacity Category
Capacity Category
Erection Method
Firing Method
Primary Fuel
Alternate Fuel
Primary Fuel
Primary Fuel
Primary Fuel
Erection Method
Erection Method
Firing Method
Primary Fuel
Primary Fuel
By
By
By
By
By
By
By
By
By
By
By
By
By
By
Year
Year
Capa
Capa
Capa
Capa
Capa
Year
Alte:
Prim
Year
Year
SIC i
Geog:
Capacity Category
Capacity Category
Capacity Category
Capacity Category
Capacity Category
Year
Alternate Fuel
Primary Fuel
Year
Year
SIC Code
Geographic Region
For All WT Boilers
For Each Primary or Alternate
Fuel
For WT Boilers
For Solid Fuels
For WT Boilers
For WT Boilers
For Exported WT Boilers
For WT Boilers
For WT Boilers
For WT Boilers
For WT Boilers
For Each WT Capacity Category
For WT Boilers
For WT Boilers
>
o
-------
TABLE A-9. BOILER CAPACITY CATEGORY BY YEAR FOR WATERTUBE BOILERS
Y E fl * SOLD
COUNT T
Rnji POT j
.. cm PCT i
BOILER CAP. TOT PCT T
1 I
10-16KPH I
I
T
-I-
2 I
16-100KPH I
T
T
-I -
3 I
1CO-250KPH T
I
I
-T-
:» T
250-5COKPH T
T
T
-I-
M J.
5GO+KPH I
1
I
-1-
COLMHN
TOTAL
65
1 0£
20.9
9.3
1 .1
300
13.0
6B .9
£.3
138
8.6
11.0
1. 1»
54
10.5
5.P
O.C-
657
10.7
70. 3
7.3
1^0
8.7
is. q
1.5
2U
6.1
?.6
0.3
b9
1 1.1
7.U
C.8
91«»
1C.£*
T
- T-
l
T
T
j,
T
- 1-
T
1
T
T
-T-
1
T
1
I
-I-
T
I
T
I
-I-
"T~
T
T
T
- I-
61
i;«j
10.9
6.2
C .6
69P>
11. 3
7ft. a
7.B
151
10. i»
17.0
1 .7
0
o.o
0.0
0.0
rr~
o.n
n.o
0.0
906
10.1
i
-T-
I,
T
T
T
-1-
T
1
I
I
-T-
I
T
I
T
-1-
I
J
I
1
-I-
~T~
I
1
I
- 1 -
69
65
12.6
5. °,
0.7
753
12.2
67. k
%.t4
i07
13.9
IB. 5
2.1
3?
11.7
3.1
a.i*
T7
11.7
b'.l
0.6
1117
1Z.S
1
-T-
1
I
1
I
-1-
. I
I
T
1
-T-
1
I
1
I
-1-
I
I
r
i
-i-
—[-
i
i
i
-i-
70
35
6. S
."i!.^
O.U
6&1
10. S
66.?
7. 4
193
13.0
19.3
2.2
T(*
11. ^
3.tf
0.4
7V~
15.7
0.3
1002
11.2
1
-T-
1
I
1
I
- L -
I
I
I
1
-T-
~I"
I
1
I
-1-
I
I
I
1
-I-
~T~
I
L
T.
-I -
71
UO
7.8
3.3
o.«»
70U
ll.i*
66.5
7.9
226
15.2
21 .<«
2.5
25
S.«»
2.t»
0 .3
5T-
12.9
b . U
0.7
105*
11.8
I
-T-
1
I
1
T
- 1-
I
I
T
I
-T-
I
I
J
I
-1-
T
I
T
~T"
-T-
~~r~
T
~T~
I
-
72
<*
NUMBER OF MISSTVG OgStRVftTTOKS =
-------
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH PRIMARY OR ALTERNATE FUEL BITUMINOUS COAL
YtAH SOLD
COUNT I
ROW KCT 1
COL PCT I
BOILER CAPACITY |OT PCT I
1 1
lO-16KPrl 1
I
I—
-I-
? 1
16-100KPH I
I
1
-1-
3 1
1
I
-I-
4 I
250-500*^ 1
1
I
-1-
5 1
500+KPM 1
I
1
-I-
COLUHN
TOTAL
BITUMINOUS COAL
HUM
TOUL
65
3
l.tt
"* c
76
J3-6
I/?. 4
23.6
15.1
4.1
15
9.0
2.5
A9.7
is. 3
7.7
166
27.1
I
J
T
I
-1-
1
1
1
1
1
1
I
-1-
T
1
1
1
-1-
I
1
1
I
-1-
66
e:
1 .5
0-3
61
27.0
45.9
10-0
2V
25. b
2l'.i
b
19. H
4.5
1.0
15.5
27. ^
21.'
I
I
I
1
I
-I-
T
I
I
1
1
I
I
1
-1-
I
I
I
1
-T-
1
I
1
1
-1-
67
4
4u.O
5.0
0.7
32
14.2
4--J.O
b.2
10
12.5
1.6
1
J.2
1.3
0'.2
J3
13.8
41.3
5.4
60
13.1
I
I
I
1
T
I
I
I
I
-I-
1
I
1
1
-1-
1
1
I
I
1
I
I
1
bb
1
10.0
2.5
0.2
25
1 1.1
62.5
4.1
13.2
2.3
0
0*0
o.u
o.u
u
0*0
o.u
o.o
4U
6.5
1
1
I
1
1
-1-
1
1
I
1
-1-
1
I
1
1
-i-
I
i
I
1
1
1
1
I
69
0
0.0
0.0
0.0
17
7.5
32.1
2.6
4
3.8
y.s
0.7
2
b.b
3.8
0.3
12.6
56.6
4.9
53
tJ.7
1
1
1
1
T
1
1
I
1
-I-
1
1
1
I
-
1
1
I
1
-I-
l
1
I
70
0
u.o
0.0
0.0
9
4.0
23,7
1.5
5~
4.7
13.2
3
y. t
u:*~
ZT~
u.u
3.4
3B
6.2
I
1
I
1
I
I
1
1
1
-I.
T"
I
1
1
1
r~
i
i
-i-
i
i
"T"
I
71
0
o.o
0.0
0.0
2
0.9
6.1
0.3
U
7.5
24.2
1.3
1
3.0
0.2
2~2~~
66.7
3.6
33
5 .4
I
-I-'
1
1
1
I
X
1
1
1
.1-
T~
X
1
I
X
X
1
-X-
X
X
72
0
0.0
o.o
0.0
1
0.4
2.7
0.2
d
7.5
21.6
1.3
2
6.5
5.4
0.3
26
10.9
0.3
4.2
37
6.0
I
-T-
I
I
1
I
I
I
I
I
-I-
I
I
I
I
I
I
1
-I-
I
I
1
I
73
0
0.0
0.0
0.0
3
1.3
0.5
5
4.7
15.6
0.8
1
jT2~~
3.1
0.2
23
9.6
f 1 .9
3.8
32
5.2
1
-1
1
I
1
I
I
I
X
1
-I
I
1
1
I
—
I
1
1
-1
I
I
— i —
10
1.6
226
36.9
X06
17.3
31
5TI
239
39.1
612
ToOV'fl
NUMBER OF MISSING
-------
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH PRIMARY OR ALTERNATE FUEL (Continued) OIL
SOLD
CUJNT 1
HOvJ PCT I
COL PrT I
BOILER CAPACITY TOT PCT I
1 I
10-16KPH I
1
I
-1-
? I
16-100KKM 1
i
1
- I -
3 1
1
1
-.1-
4 1
1
1
— I -
5 I
bOO*KPH I
1
1
-I-
COLLlMN
TOTAL
t-5
By
20.7
11.5
563
n.o
73.0
6.1
fe7
6.5
I'D
?j
14.2
3.M
0.3
1^3
!'•• 4
771
11.0
I
-T-
1
1
1
I
-1-
I
I
T
1
1
I
1
I
-1-
I
i
I
1
1
1
1
I
-1-
66
8J
19.3
?J2
655
12- d
75.0
9«>
8?0
10.3
1.3
ia
ll.i
2.1
Oi-3
H.9
2r*
e?b
12. »
I
I
I
1
I
-I-
I
1
I
I
I
I
I
I
-1-
I
1
I
1
1
I
1
I
-1-
67
44
10.2
fa. 6
0.6
509
75.9
7.3
74
7.2
11.0
1.1
15
y . j
0.2
29
12.3
4.3
0.4
671
^S.6
-1-
I
I
I
I
1
I
1
I
-1-
I
1
I
1
I
I
I
I
-1-
(
6b
43
10.0
6.2
0.6
~559
10.9
80.3
8.u
94
9.1
13.5
1 .3
0
0*0
0.0
0*0
0
0.0
c-«o
o.o
696
10-0
3IL
1
-1-
1
I
1
I
-1-
1
1
I
1
1
1
1
I
-1-
1
1
1
1
i
1
1
1
-1-
69
11.9
b.2
0.7
590
11.7
72.2
8.6
135
13.1
lb.3
1.9
20
ieL* J
2.4
0.3
10.2
2.9
U.3
828
Tl .9
I
-r-
i
i
i
i
-i-
i
i
i
i
1
i
i
i
-i-
i
r
1
1
1
1
1
1
-1-
70
32
7.4
0.5
b63
11.0
&.1
15.1
l^;2
17
2.1
U.2
4B
2U.3
u*7
816
11.7
1
-I-
1
I
1
1
-1-
I
I
I
1
1
I
1
I
-1-
I
I
I
1
1
I
i
i
-i-
71
32
7.4
3.6
0.5
621
12.1
70.4
8.9
T77
17.2
20.1
2.5
17
10*5
1.9
0'.?"
J5
14.8
4*0
0.5
882
12.6
1
-I-
1
1
1
I
-1-
1
1
1
1
i
1
1
1
1
I
1
1
1
I
1
I
-1-
72
35
6.1
4.0
0.5
629
12.3
72.7
9.0
1 J t
13.3
15.8
2.0
30
3*5
0.4
34
14.4
3.9
0.5
865
12.4
I
•T-
I
I
I
I
-I-
I
I
I
I
I
I
I
I
-1-
I
1
I
1
I
I
I
I
-1-
73
21
3.6
0.3
425
8.3
72.6
6.1
TOT
9.B
1 1.3
1.4
22
1 J. b
3.8
0.3
10
6.8
2.7
0.2
585
8.4
I
1
I
1
1
-i
I
I
I
1
1
I
1
1
-1
I
1
I
1
I
1
I
1
RUW
TOTAL
430
6.2
5122
73.4
14,8
lt>2
• j
236
3.4
6960
100.0
OF MISSING OBsKHVATiONb =
-------
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH PRIMARY OR ALTERNATE FUEL (Continued) NATURAL GAS
YE*H SOLD
COUNT I
HOW HCT i
COL HTT 1
BOILER CAPACITY TOT HCT 1
CATEGORY T_,
1 1
10-16KPH I
I
1
-1-
?. 1
I
I
-I -
3 1
i
I
-1-
4 I
250-500*™ 1
1
1
-I-
5 1
500*KPH I
1
1
-I-
COLUMN
TOTAL
NATURAL
o5
75
1 .?
514
11.3
71.6
rt.3
8.6
11.1
1 .3
" ~?a
IH.l
3.9
!)-5
13.3
0«3
" 71H
11 .6
I
I
1
1
-1-
1
1
I
I
-T -
1
I
I.
1
-I-
T
I
I
1
-1 -
1
T
1
I
-1-
06
71
d .6
1.2
Sdb
71 .J
9.b
13.3
15.1
2-0
21
13. S
2.o
o.!-4
12«f
0'^
821
13.3
1
I
T
I
-I-
I
1
I
1
I
1
I
i
-I-
r
i
i
i
-T-
I
T
1
1
-I-
67
37
5.7
0.6
*b2
10.6
74.3
7.8
8.9
12.8
1.3
12
1.8
0.2
35
22-2
0*6
b49
10.5
I
I
I
-I
T
I
I
I
I
1
I
I
I
-1-
I
1
I
I
— I-
l
I
I
I
— l-
68
30
8.0
4.6
O.b
537
11. b
fll .7
8.7
vo
9.7
13.7
l.b
0
0«0
0*0
0
0.0
0*0
657
10.7
I
I
1
1
I
I
1
I
1
1
I
1
1
-1-
1
1
1
1
-1-
1
I
1
1
CAS
69
12.0
b.5
0.7
598
13.1
73.0
9.7
13?
14.7
lb.7
21
13. b
2.6
0.3
18
11.4
t.Z
0*3
619
13.3
1
-I-
1
I
1
1
-1-
1
1
I
1
1
1
I
1
I
1
1
1
-1-
1
I
1
I
70
32
0.5
4.4
0.5
520
11.4
71.3
8.4
14.2
16.1
14
9.0
U.2
31
19.6
0.5
729
11.8
I
-I-
1
I
1
I
-1-
I
I
1
1
-I-
1
I
1
1
I
1
I
1
-I-
1
I
1
I
-1-
71
29
7.7
4*4
O.b
490
10.8
74.6
7.9
111
11.9
16.9
1.8
10
6.5
1.5
0.2
17
10.8
2.6
0«3
6b7
10.7
1
-I-
1
1
1
1
i
1
I
1
-1-
1
1
1
I
i
1
-I-
I
1
1
72
40
10.7
6.1
0.6
507
11.1
76.8
8.2
9.5
13.3
18
11>6
277
0.3
7
4.4
1.1
0.1
66Q
10.7
I
-I-
I
I
I
T
-1-.
I
I
I
I
-I-
1
I
I
I
I
i
i
i
-i-
i
i
i
i
•i-
73
16
4.3
3.5
0.3
31H
7.0
69.3
5.2
85
9,1
18. 5
1.4
31
6.H
O.h
9
5.7
2.u
0.1
459
7.4
I
-I
1
I
1
I
I
1
I
I
-I
T
I
1
I
I
I
I
-I
I
I
1
I
TOTAL
375
6.1
4551
73.8
930 '
lb.1 £
155
iba
2.6
6169
iOO.O
OF MISSING
KV AT iOf-jS =
=>2
-------
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH PRIMARY OR ALTERNATE FUEL (Continued) - - WOOD WASTE
SOLD
COUNiT T
HO* PCT i
COL PrT i
BOILER CAPACITY TOT Pt'T 1
1 I
10-16Kh>rl I
I
-
? I
16-10CKPM I
I
I
-1-
3 1
1
I
- 1 -
4 !.
2bO-5oO*Hh T"
1
I
-1-
5 1
bOO*KHn I
1
1
- 1 -
COLUMN
TUTAL
WOODWASTF
65
1
J3.3
5.6
0. A
13
1 C • 7
7?. 2
7.9
7.1
11 .1
1 .2
1
5.6
i) .6
I
14.3
0-6
18
1 0 . 9
I
•-T-
J
T
1
T
I
1
1
1
•-T-
I
I
1
• 1
T
1
I
1
-l-
1
I
1
I
6O 1
1-
1 I
33.3 I
12. b J
'.l«6 I
I-
/ I
5-' I
87. :> I
4.c I
* 1
0-0 I
o.o i
0-v 1
0 1
o» o i
0«l! I
0 * v I
— - — i-
C 1
6 1
4.b
67
0
0.0
o • U
0.0
«,
3 '.3
2.4
1
3.6
12.5
0.6
a
25.0
1.2
1
14.3
0.6
6
NUMU£ft Op MISSING
-------
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH PRIMARY OR ALTERNATE FUEL (Continued) BAGASSE
SOLD
CUJNT I
HOW HCT i
COL PrT 1
BOILER CAPACITY TOf PCT I
CATEGORY 1-
2 I
16-100KPM 1
1
l
- 1-
3 I
100-250KHH I
1
1
• T
* i
250-500KHH ' I
1
1
-1-
5 1
I
1
_ T
~ 1 •
COLUMN
TOIAL
6b
2
O • f
100.0
o
o.o
O.'J
17
o.o
0*0
o
0. J
O.fJ
4.5
I
-1-
1
I
I
*
1
I
I
I
-T-
t
I
1
I
I
I
I
1
fatj
U
().U
(. .0
2
lO'b
*T&
0
{J.(j
0.0
0*0
0
fl.o
IJ.f
0..0
c
4.5
T
I
I
I
1
-I-
I
I
I
I
-1-
1
I
I
1
6H
3
1 0 0 . 0
6.M
0
o.o
0.0
0.0
0
0.0
0.0
0.0
0
0*0
0.0
0.0
3
6.6
1
-T-
1
I
I
I
I
I
I
I
-T-
1
I
I
I
-
I
1
I
1
B4
0V
1
4.3
16.7
2.3
4
21.1
66.7
y.i
0
c.o
0*0
0*0
1
16.7
2.3
6
13.6
.GAS
1
-T-
1
1
1
I
1
1
1
I
-I-
1
1
1
1
-1-
I
1
I
1
SE
70
2
8.7
66.7
4.5
1
b.3
33.3
2.3
0
0.0
0.0
0.0
0
0.0
0.0
0.0
3
6.S
1
- 1 -
1
1
I
1
1
1
1
1
-1-
i
I
1
1
-1-
I
i
1
1
71
b
21.7
bo.O
11.4
5
£6.3
50.0
11.4
0
o.o
0.0
0.0
0
0.0
0.0
10
22.7
1
-T-
1
I
I
I
I
1
1
1
-1-
1
I
1
I
-1-
I
1
I
1
72
6
26.1
66.7
13.6
3
15.8
33.3
6.8
0
0..0
0.0
0.0
0
0*0
o.o
0.0
9
20.5
1
-1-
1
1
1
1
1
I
1
1
1
1
1
1
-1-
1
1
I
1
4
17.4
44.4
9.1
4
21.1
44.4
9.1
1
100.0
11.1
2.3
0
0.0
o.o
o.o
9
20.5
I
I
I
I
T
I
I
I
I
-T
I
I
I
I
-I
I
I
I
1
HOW
TOTAL
23
52.3
19
43.2
1
2.3
1
£.S
44
100.0
-------
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH PRIMARY OR ALTERNATE FUEL (Continued) BLACK LIQUOR
YEAR SOLD
COUNT 1
HO* PcT 1
COL HfT 1
BOILER CAPACITY TOT KCT 1
2 1
16-100KPH 1
I
1
-1 —
3 1
100-250*^H I
I
1
- T -•
4 I
250-500KHM I
I
1
-1--
5 I
bOO**PH i
1
I
-!-•
COLUMN
TOTAL
05
2
15.^
iO-5
1-fl
7
19.4
3ft. H
6. 1
10
19.6
5?. 6
3.rt
C
o-o
Cue
o.o
19
16.7
I
1
1
I
_L_
-I-
i
i
i
i
i
i
i
T
-1-
1
1
I
1
66
1
l.f
6.7
0-9
5
13'1*-
33 «J
4.4
?—
13.7
46. /
h.i
2
14. J
13. J
!•«
Ib
13.2
I
I
T
I
_L_
-I-
1
1
T
I
1
T
1
T
-1-
I
1
1
1
-I-
fa7
1
7.7-
ifb.O
0-9
2
5.6
5J.O
1.8
1
2.0
2^*0
0.9
0
o.o
0.0
0.0
4
3.5
I
I
I
1
T
I
1
I
1
1
I
\
I
-1-
I
I
I
1
bb
4
30«tl
66«7
3.5
2
5.6
33.3
l.B
U
n.o
0-0
0*0
0
c.u
0*0
o.o
6
5.3
BLACK LICUOR
I
1
I
1
1
1
1
I
1
1
1
I
I
-1-
I
1
I
1
69
1
7.7
a. 3
0.9
2
S.6
16,7
1.8
8~
lb,7
66.7
7.0
1
/.I
b.3
0.9
T2~
10.5
1
1
I
I
I
I
I
I
1
1
I
1
1
-1-
I
1
I
1
70
0
0.0
o.o
C.U
2
b.6
22.2
Kb
J~
6.9
33.3
2.6
4
£!B.6
44.4
.i.b
9~
7.9
1
I
I
1
I
-1-
I
1
1
1
-I-
I
1
1
I
-I-
1
~T"
I
1
-I-
71
0
0.0
0«0
o.u
6
16.7
37.5
5.3
9
17.6
56.3
7.9
1
TTT
6.3
0.9
T6~
14.Q
1
.1-
i
1
1
I
I
1
I
1
-I-
— r
i
~T~
I
—
1
T"
I
1
— 1-
72
2
15.4
11.1
l.B
5
13.9
27.3
4.4
6
11.8
33.3
5.3
5
35. r
27.8
4.4
18
15.8
I
•I-
I
I
I
I
I
1
I
I
-I-
I
I
1
I
I
I
1
-I-
73
2
15.4
13.3
l.B
5
13.9
33.3
4.4
7
13.7
46. 7
6.1
1
Til
6.7
0.9
15
13.2
I
-I
I
I
1
I
1
1
I
1
-I
i
i
i
i
v~t~
I
I
1
-I
ROW
TOTAL
13
11.4
36
31 «6
bl
44.7
14
e.3
114
100.0
>
-------
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH PRIMARY OR ALTERNATE FUEL (Continued) OTHER FUELS
YE AW SOLD
COUNT I
no* HCT i
COL PCT i
flOILER CAPACITY TOT PcT I
CATEGORY . I_
1 I
10-16KPH I
I
I
-I-
? I
16-100KPrt 1
I
I
-I-
3 1
100-250KPH 1
I
I
-I-
4 1
2bO-500NrH 1
1
I
-I-
5 1
500**PH i
1
I
-I-
COLUMN
TOTAL
OTHER FUELS
t>5
J
16.7
3.tt
0.7
H3
24.6
5?.o
10.3
20
12.8
25.3
4.6
7
lo.tJ
9.9
1 .6
t
25-0
5. 1
0.9
Y9
18.0
I
I
I
I
T
-I-
I
1
1
I
I
1
.1
1
-1-
I
"I
I
1
I
1
I
I
-I-
bb
J
1 ft . V
2.8
0.7
48
26. e:
44« *
11.0
*t>
2b.b
37.4
9.1
15
23.1
14. a
3.4
i
6.3
c-9
.>•*
107
2*;1*
I
I
I
I
T
-I-
I
1
I
I
-I-
I
I
1
I
-1-
T
I
I
1
-T-
I
I
1
I
-I-
67
2
11.1
3.3-
U.5
29
Ib.H
40.3
b.6
19
12.2
31.7
4.3
7
lo.ti
11.7
1.6
3
Id. 7
b.O
0.7
60
1 J.7
I
1
I
I
1
I
1
I
1
-I-
1
I
I
I
-1-
I
1
I
1
I
I
i
I
-1-
68
b
44.4
17. b
1.8
25
13. V
5S.6
S.7
12
7.7
26. /
2.7
0
(i.O
0.0
0*0
0
o.o
0-0
0.0
45
10.3
1
i
1
1
I
I
I
1
1
i
I
1
1
1
1
I
1
1
1
1
I
-
69
1
5.6
1.9
U.2
18
9.ti
34.6
4.1
21
13.5
40.4
4.8
9
U.B
17.3
2.1
r~
lb.7
b.8
0.7
52
11.9
1
1
i
1
I
I
1
1
1
-1-
1
I
1
I
I
r
i
i
i
i
i
i
70
0
o.o
0.0
o.u
6
3.3
33.3
1.4
«
S.I
44.4
l.H
4
b.2
22.2
0.9^
D~
o.O
u*0
0.0
IB
4.1
1
-I-
1
I
i
I
I
1
I
1
-1-
1
I
1
I
I
~T~
I
1
-I-
1
I
~T~
I
71
1
5.6
5.6
0.2
S
2.7
27. t)
1.1
8
5.1
44.4
1.8
3
4.6^
16.7
0.7
r
6.3
5.6
0.2
18
4.1
i
-I-
1
1
1
1
1
~T~
1
1
-1-
T~
1
1
I
—
I
i
I
~r~
-i-
i
i
~T~
I
72
0
0.0
0.0
0.0
4
2.2
18.2
0.9
T2~
7.7
b4.b
2.7
2
J.I
9.1
0.5
4
25.0
18.2
0.9
22
5.0
I
-T-
I
I
I
I
I
~T~
I
I
-I-
I
I
I
I
—
I
T~
I
1
-I-
1
I
1
I
73
0
0.0
0.0
0.0
3
1 .6
8.1
0.7
Tb~
10.3
43.2
3.7
18
1 1 . /
48.6
4.1
0~
0.0
0.0
0.0
37
d.4
1
-I
1
I
1
I
— ? —
I
1
1
1
-1
T
1
1
I
I—
1
~T~
I
1
-I
1
I
1
I
uu*
TOTAL
18
4.1
io3
41 »B
ib6
35.6
65
— 16
3.7
438
100.0
00
OF MISSING OHSEKVM
-------
TABLE A-10. BOILER CAPACITY CATEGORY BY YEAR SOLD FOR EACH PRIMARY OR ALTERNATE FUEL (Continued) WASTE HEAT
SOLD
COUNT 1
now P(:T i
COL r>n i
BOILER CAPACITY ] QT PC T I
CATEGORY j.
?. I
16-lQOKPH I
1
J
-1-
.1 1
1
I
-1-
4 I
i
1
-I-
COLUMN
TOTAL
WASTEHEAT
fc*
•J
0 • U
o.o
6.0
„
1 LO.O
4.8
0
C'O
(i . U
4.6
i
1
1
1
I
1
1
T
1
1
1
J
I
•-JL-
71 1
1_
3 1. I
57. t I
.Iti.l I
___ j_
o I
2ulu S
9»b I
!_
<; i
15.4 I
2»'» I
1-
40
4H.t
7?
14
5e>.'j
16 .9
0
U • U
U.U
0.0
11
4<+ . 0
13.3
25
Ju.l
I
-T-
I
T
T
-1-
I
I
T
I
-T-
I
I
1
I
-1-
1S
5V
q
33
4?
7
r-
c
i;
it.
73
a
.1
.fS
ft
.3
•^
U
* 0
.0
.0
14
• V
1
-1
I
I
1
I
-1
I
1
T
1
-I
1
I
1
I
-i
KOW
TOTAL
62.7
18
21.7
13
15.7
83
iOli.U
OF MISSliMG OHSfc H V« I 1
-------
TABLE A-11. ERECTION METHOD BY CAPACITY CATEGORY FOR WATERTUBE BOILERS
CATEO
ERECTION
METHOD
PACKAGED
FIELD ASSEMBLED
COUNT I
ROW fCT H
COL PcT I
TOT HCT I
— 1.
1 1
I
1
I
-I.
? 1.
r
i
i
-i-
COLUNN
TOTAL
e-16KHrl 16-lOOKK 100-R50K 250-500K 500+KPH
M PH PH
1
469
H').?
S.I
S7
?.8
10. B
0.6
5.7"
I
-T —
1-
I
I
T
-]-•
I
I
T
I
-56-?!
70.0
8M.fr
709
35.4
11.2
7.T
6rt. t
I
•T-
I
I
I
T
-l-
I
I
I
I
-T-
3
1066
68.9
11.*,
481
24.Q
31.1
5.2
16.8
1
-I-
I
1
I
T
-l-
I
1
I
I
-T-
4
53
17.5
0.6
250
12.5
82.5
2.7
303
3.3
1
-I-
1
I
I
I
-1-
I
1
I
I
-I-
8
1
0.0
0.2
0.0
505
25.2
99.8
5.5
506
5.5
1
-I
1
I
1
I
I
1
I
1
-I
ROW
TOTAL
7220
78.3
2002
21.7
9222
100.0
.JS
o
OF MISSING OBSPRVATIONS =
-------
TABLE A-12. FIRING METHOD BY CAPACTIY CATEGORY FOR SOLID FUELS -- BITUMINOUS COAL
LUUHI i
HUW HCT 1
COL PrT I
1 0.00
-0. 1 3
UNSPECIFIED i 44
1.
PULVErtlZtU COAl I
SPHEADE* STO-^ER
3.
UNQEBFg£P STOKER 1
4.
OVEWFEED STOKER
OTHER 50LIO
V.
NON-SOLID FUtL
75.0
0
J . U
O'O
0
a. a
0*0
1
25.0
0
D.O
0.0
0
0«0
0
D.O
O'O
COLUMN 4
TOTAL t!-7
10-
I
I
1
I -2
1
I
I
I
1
I 2
I
J 1
I 6
I
I
I
I
1
-i
1
1
I
1
• ' ' H_
t^OOl -2*00
'e. i 36
?.y r 52.9
U
0.0
O'O
2
J-'1*
6
Q.U
0
0 .1)
o.o
0
0*0
16.7
10
PH
I
I
1
I
I
1 I
0.4 I
O'S
be
5V. 5
26
7H.H
12.0
43
feSI. 6
19.9
|._..^._.
I *2
I 3V. 3
I 10«2
U 1 0
ii . 0 I 0.0
0 • 0 I 0 • 0
U 216
1.7 36.2
I
1
1
I
I
1
T
1
T--
1
I
I
1 —
1
I
I
I--
I
I
1
•T-'
r»-2SOK 250-500* 500*KPH
' ' PH
3.001
15
iV
16
6.7.
15.7
56
3?..8_
54. SI
0
o.o
0.0
5
10.4
4.9
10
JJ.y
9. a
0
0.0
O'O
102
1
I
1
-I—
1
I
1
•r—
1
I
I
-I —
I
I
1
-I —
I
I
I
-I--
I
I
I
-I —
I
I
1
4.001
— j.
2 1
2.9 1
6.9 1
1-
21 1
t. *i r
72'4 1
1-
2 I
1...4 1-
6.9 I
1-
0 1
0.0 I
0.0 I
— : 1.
0 1
0.0 1
0.0 I
1.
3 1
5.4 1
1U.3 i
1
1 1
33.3 I
3.4 I
29
4,9
10
14.7
4J3
202
b4.2
86.Q
0
,0.6.
- 1'*
0
0.6
O.D
0
0.0
0.0
21
37.5
d.V
2
66.7
-------
TABLE A-12. FIRING METHOD BY CAPACITY CATEGORY FOR SOLID FUELS (Continued) — WOOD WASTE
BOILER CAPACITY CATEGORY
COUNT
RO* PCT
COL HrT
-0.
UNSPECIFIED 6
100
-I..-.
1. J
PULVERIZtD COAL 1
2.
3.
UNDERFEED STOKER
4.
OVERFEED STOKER
b.
. „. . OTHEP .SOUIU
9.
NON-SOLID FUEL
, 0
0
0
0
0
6
• _-_
0
0
c
u
c
10-16
0.001 1
1
.7
• 0
0
.0
•6
0
. u
•0
-. — ).
H Ph
•00
1
33;
U.
1.
33.
____-
0 I
.0 I 0.
•o 1 or
0
.0
•0
u
.0
•0
.0
0*0
COLUMN
TUIAL (,
0.
0»
_ 3.
33i
0.
Oj
1
.7 2.
3
0
0
1
5
3
6
0
0
0
0
1
6
,1
U
6
j
;
2.001 3.001
8 1
53.3
7.2
_--_____
0
o.u
o.o
42
64.6
37. H
_--_:. — -
2
100.0
1*8
_-.
fib. 7
23.4
»*.3
22.5
8
loo.o
2
13.3
8.0
U
0.0
0-0
IV
29.2
76^0
0
0.0
O'O
4
13.3
16.0
0
0.0
Q.O
0
[ 0.0
l;i I 0-0
3 111 15
0 74.5 16.8
1
I
I
-|
1
i
1
• j
I
\
I
-I
I
I
I
•I
I
I
i
-\
i
I
I
-1
1
I
1
-f
250-500K
PH
4.001
3
20.0
100.0
0
0.0
0*0
0
0.0
0*0
0
0.0
0.0
0
0.0
o.o
0
_9.0
0*0
0
0.0
0>0
3
-2.J) .
I
\
i
f
1
L
1
|
I
1
1
1
I
I
1
I
I
1
1
1
1
I
1
1
1
J
1
1
5UO*KPH HOW
TOTAL
0 I IS
0.6 I 10.1
9*9 l
i
is;?
3
4.6
5o>0
0
0.6
0-0
0
0.6
u.o
7.1
33^3
o
0.6
u.o
1
0.7
65
43.6
1.3
30
20.1
28
18.8
8
5.4
[
6 H9
J>
t-0
-------
TABLE A-12. FIRING METHOD BY CAPACITY CATEGORY FOR SOLID FUELS (Continued) -- BAGASSE
BOILER CAPACITY CATEGORY
ro JUT
COL nr?
FIRING METHOD
-0.
UNSPECIFIED
2.
5KR t AO.e«_SlClKf,fl._
3.
UNDEHFEEO STCtKFR
4.
OvE_RF£eo STOntH
5,
OTHER SUL1U
V.
NtfN-SOLlO HJtL
COLUMN
TUIAL
1
.1
1
1
I
I
-r
i
. L
I
-I
I
I
1
-I
1
i
1
-1
I
1
I
-J
1
J
I
•T
16-lo
H
*
7S.
13.
...1.5«
13.
.16(3.
4.
Ifco.
4 >
J
«2.
6C«
.._J?'J.
5?.
0^
3
I)
U
3
B
0
1
C
3
1
(>
3
i*
4
9
1
1)
J
3
Hri
L
I
(i
78
78
0
0
0
17
15
_50
5
!-..._
^50*
J.OU
U
.0
• V
.9
0
,0
• J
0
,9
j
.0
•e
i
.0
. J
19
I
I
T
I
1
I
J
1
1
I
I
1
1
1
1
I
I
I
I
t
PH
4
u .
u .
£l •
100.
0 .
o?
0«
0.
U;
u.
V-
?
00*
• ou
0
0
u
1
3
0
u
o
0
...
0
f)
0 J
u
t; i
u
—
u
o J
"--J
1
T
50o**P
1 U.
1
?5.0
loo.u
0
y . o
~o.d
0
0. 0
o«u
0
u.o
I 0*0
u
0.0
0«0
— __1-
0
0.0
(/• 0
1
2.3
M
oci
I
1
I
--I
I
T
--I
I
I
I
•-1
1
f
I
--I
I
1
1
I
I
1
KGH
TOTAL
9.1
19
1
2.3
1
2.3
17
2
4.5
44
100.0
I
.p-
10
-------
TABLE A-13. PRIMARY FUEL BY BOILER CAPACITY CATEGORY FOR WATERTUBE BOILERS
COUMT
PCT IIO-IP-KPH 1^-190KP 100-250K
T H PH PH TOTAL
TOT PCT
PRIMARY FUEL
1
BITUMINOUS COAL
OIL
3
NATURAL GAS
^
W0003APK
5
PAHASSF
5
BLACK LIQUOR
7
OTHER FUELS
COLUMN
TOTAL
I
T
T
I
T
-I-
T
T
T
I
-T-
T
T
I
T
-T-
T
1
T
1
-I-
I
T
J
T
T
1
T
T
-I-
I
I
I
T
-I-
1
10
1.7
1.9
C.I
1UO
7.6
27.1
l.F.
. 6.7
6&.9
3.9
^
O.ft
C.O
p
c.o
(5.0
0.0
0
e.o
c.o
G* 0
18
5.6
3.5
516
5 « ft
1
I
T
T
T
-I-
T
I
T
T
T
T
T
T
-T-
T
1
T
T
1
T
t
T
T
I
T
1 T
-I-
1
T
I
T
'
2
215
3.5
i ft a. <3
t>7.7
Z7.5
16-9
J911
75.9
63.6
99
72. *
1.1
^
D.<*
0. 3
12
11.0
0.2
U.I
uu. ?
Z..1
1.6
61f7
68 . 9
1
T
T
I
T
T
I
T
I
-T-
1
T
T
T
_[-
T
.1
T
I
•-T-
T
I
t
I
•- 1-
T
T
I
T
I
I
I
1
•>
97
lfi.9
1.1
L.7?
19-9
31.8
= .3
J!c
1*8.7
8.1
25
1.7
0^
»Q\«
1.1
0.2
1?
2.2
O.t.
97
30.2
F>.5
\ .1
1UIJ5
16.6
1
I
T
1
T
•1-
T
I
T
I
-T-
1
T
1
T
-1-
T
I
I
1
-I-
I
I
1
T
- J -
I
1
T
I
1
I
T
T
"rT:
t.
u^9
9.(f
0.3
7 <*
3. 0
21*. 9
0. 0
72
'irJ
i
? • 2
1.0
0. 3
1
07J~
0.0
51
17.2
U.t>
16.5
17.8
0.6
297
3.3
I
-T--
I
I
J
I
- I -•
I
1
J
I
-!-•
I
I
1
T
-1-
I
1
I
i
-I-
I
T
T~
I
•- 1-
I
T~
I
i
J
I
I
-
8
22^
39.0
2. "5
119
2^'.!
1.3
152
£.0
21.3
1.1
6
1.3
0.1
1
. 2
0.0
!<*
12 .«
2.9
L' . d
11
2.3
0.1
UBO
I
-I
T.
I
1
I
- 1
T
T
I
1
-T
I
I
1
T
-1
I
1
T
I
-I
I
I
I
T
T~
I
I
T~
I
l\l
?«}*
27.9
5153
•57.7
136
.5
0.5
109
T2
2 1
3 0 . D
(CONTTNUEO)
-------
TABLE A-13. PRIMARY FUEL BY BOILER CAPACITY CATEGORY FOR WATERTUBE BOILERS (Continued)
COUNT
COL °GT
TOT PCT
8
WASTEHEAT
9
WITH AUV. FIRING
10
LIGNITE
COLUMM
.OiftL
T
U
T
1
I
r
T
I
i
I
I
I
T
T
T
J
0-16KP
i
D
c.o
0.0
c.o
0
e.o
c.c
c.o
0
0.0
c.o
516
b'.tt
H 16-lC-OKP J.OO-'iSO!
u FH
T -
T
J
T
T
I
T
1
I
I
r
T
-
2
51 '"
65. «
\\l
5
33.3
0.1
0.1
0
C . 0
e.o
o.o
61^7
63.9
I
I
T
i
1
T
- J -
T
1
I
T
-T-
1
T
T
I
-.1 -
1.7
I
$3
C
U
0
0
n
1U
Ih
.9
'J
8.
. .<
.^
.1
'j
.0
.0
.0
*?5
.fi
< ?50-b
PH
I
I
T
1
T
- T -
I
T
T
J
-T-
1
T
I
T
1
<4.
0.
1 J.
0.
G.
Q.
0.
0.
10k 5GO+KVtf
**
3
t
•>
7
0
IT
n
U
0
?97
.1.
1
1
I
J
T
•
I
1
I
1
-I-
~r
i
T
•
H
!J
0.0
0.0
0
n.o
0.0
0.0
r
100. 0
G.O
^80
,.u
1
I
I
r~
i
•-T
I
I
1
r
T
r~
i
Sow
TOTftL
0.9
15
0.2
3
0.0
8925
1C 0 . U
NUMBER OF MISSING o^S1!1?'' CT TONS = , 93
I
-p-
U1
-------
TABLE A-14. ALTERNATE FUEL BY CAPACITY CATEGORY FOR WATERTUBE BOILERS
CATEG
rOUNT T
ROW PCT n
rni Prt T
TOT PCT I
ALTFUEL — — f-
* I
NONE I
I
T
0 T
I
I
T
-T-
. 1 I
BITUMINOUS COAL I
I
I
-I-
2 T
OIL I
i
I
• i-
3 I
NAfURAL GAS T
I
i
4 I
WOOD BARK I
i
T
-T-
6 I
BLACK LIQUOP I
I
i
-I-
5-16KPH 16-lOOKP 100-250K 256-500K 500*KPH
H PH PH
1 .001
211
5.9
48.9
2.4
n
n.n
n.n
O.n
. 3
o.n
O.n
?B?
6.6
54.7
3.2
?2
7.6
4.3
n
0.8
O.Q
o.c
a
O.Q
O.Q
n.n
I
T
I
T
— I-
T
-T
T
I
— T-
I
I
I
I
-I-
I
T
I
I
T
I
i
j
i
i
T
I
I
I
i
-i-
2.001
22*7
62.7
36.5
. .^_.
70.3
6.3
10
45.5-
0.2
n.l
"~3?83~
76.7
51.3
36.7
61\B
R.6
5.9
11
68'. 8
n.2
0.1
1
loo.o
n.o
n.o
I
T
I
T
•I-
T
I
T
1
•T-
I
I
I
I
•I-
T
I
I
I
I
I
I
I
•I-
I
I
I
T
•T-
I
I
I
I
•I-
3.001
715
19.9
48.1
8.C
3
8.1
0.2
0.0
4
18.2
0.3
o.o
523
12.2
15.?
5.8
175
?0.4
11.8
2.0
r
18.7
0.2
O.o
0
o.n
0.0
0.6
I
I
I
I
-I-
T
I
T
I
-T-
I
I
I
I
-I-
I
I
I
I
-I-
I
I
I
I
-T-
I
I
I
I
-I-
4,001 8.001
104
2.9
14.9
1.2
5
13.5
1.7
0.1
3
T3.6
1-9
n.o
83
1.9
P7.9
80
9.3
ft. 9
1
6.3
0.3
n.o
0
n.6
6.6
308
8.6
63.0
3.4
3
8.1
0.6
0.0
5
22.7,
1.0
0.1
112
2.6
22.9
1.3
5.9
10.4
0.6
1
6.3
0.?
0,0
0
o.n
O.Q
0.6
I
I
I
T
•I
I
I
T
I
-T
I
I
I
I
•I
I
I
I
I
I
I
I
I
I
I
I
I
-T
I
I
t
I
ROW
TOTAL
3585
40.1
37
0.4
22
0.2
4283
«7.9
853
9.6
16
0.2
I
o.o
COLUMN
6
148ft
?98
(CONTINUED)
TOTAL
5.8
68.8
16.6
3.3
489
8948
5.5
100.0
I
•p-
cr>
-------
TABLE A-14. ALTERNATE FUEL BY CAPACITY CATEGORY FOR WATERTUBE BOILERS (Continued)
COUNT
POW PCT
COL PCT
TOT PCT
OTHER FUELS
CATEG
i
IV5-16KPH 16-1 OOKP 100-250K 250-500K 500*KPH
T H PH PH
I
I
T
I
i_
-I —
8 T
WASTEHEAT
9
WltH AUX. FIRING
COLUMN
TOTAL
I
t
I
I
I
i
-I-.
1.001
1
0.2
0.0
5
n.Q
. 6.0
0.0
. 5
0.0
a-e
c.o
516
5.8
I
I
I
T
T
I
I
I
-T-
I
T
1
T
2.001
35.9
' 0*8
0
Q.O
o«o
0*0
5~
o.o
n.o
o.o
6159
68. H
I
T
I
I
-I-
T
I
T
I
I
T
I
T
-I-
3.001
42.3
4.0
0.7
2
lno.0
0.1
O.o
T~
50.0
0.1
0.0
1486
16.6
I
I
I
T
-I-
T
1
T
1
-I-
I
I
1
T
4.001
1 —
?4.8
7.0
n.2
0
g.Q
o.o
0.0
- 1
50.0
p. 3
a. 6
298
3-3
I
I
I
I
-I —
I
I
I
-I—
I
I
I
—
HUW
TOTAL
B.OOI
1
9
6.3
l.R
0.1
6
o.o
0.0
0.0
0
o.o
0*0
o.o
489
I
1
I
I
I
1
— I
I
I
I
I~~
142
1.6
2
0*0
't
0.0
8948
Oh MISSlTIG
-------
TABLE A-15. PRIMARY FUEL BY CAPACITY CATEGORY FOR EXPORTED WATERTUBE BOILERS
COUNT I
ROW PCT n
COL HCT I
TOT PCT I
1 I
BITUMINOUS COAL I
I
I
-I-
? I
OIL I
I
I
-I-
3 I
NATURAL GAS I
I
I
• T -
4 I
WOODRARK I
I
I
-I.
6 I
BLACK LIQUOR I
I
1
-I-
7 I
OTHER FUELS I
I
I
Q
WITH AUX. FINING
-I
COLUMN
TOTAL
6-16KPH 16-100KH 1
1
0
o.o
o.o
o.o
2
1 .6
100.0
6.9
0
P.O
o.o
0.0
0
0.0
o.o
o.o
0
oo
o.o
o.o
0
0*0
0.0
0.0
0
0.0
p.O
o.o
6«9
H
I
-I —
T
I
I
I
1
T
I
I
-I-
I
T
I
I
I
I
T
-I-
I
I
T
I
— T-
1
2
0
o.o
p.O
67
54.5
74.4
30-0
27.6
17.B
7.2
0
6.0
Q.O
o»o
1
ioo*o
1.1
°;T
to
16*7
6.7
2.7
0
o.o
0*0
o .0
90
00-250!:
PH
1 3
•I-
T
I
I
I
T
I
I
•I-
T
-T-
I
-T-
1
I
I
I
T
I
I
I
0
0.0
0*0
0.0
37
30.1
47.4
16.6
10
17.2
12.8
4.5
1
100.0
1.3
0.4
0
o.o
0.0
0.0
29
80.6
37.2
13.0
1
50.0
1.3
0.4
78
35.0
L_2!
p»
I
T
I
1
I
-T-
I
T
1
I
•1-
I
I
I
I
-I-
I
I
I
I
-1-
I
I
I
I
-I-
I
I
I
T
I
I
I
I
-I-
JO-500K
H
4
0
c.o
o.o
o.o
9
7.3
24.3
4.0
27
46.6
73.0
12.1
0
0.0
0*0
0.0
0
0*0
0.0
0.0
0
0*0
o.o
0.0
1
50.0
2*7
0.4
37
i'6-6
500*KPH
I
T
I
I
I
I-
I
I
1
I
I
I
I
I
I
1
JL
-I-
I
I
i
I
i
"T
I
I
-I
e
2
100.0
12.5
0.9
8
6.5
50.0
3.6
5
8.6
31.3
2.2
0
0.0
0.0
0.0
0
o.o
0.0
0.0
1
2.8
6.3
0.4
0
0.0
0.0
0.0
16
7.2
I
I
1
I
I
I
I
1
I
I
1
I
1
-I
I
I
1
I
I
1
I
1
-I
I
ROW
TOTAL
2
0.9
123
55.2
58
26.0
1
1
0.4
36
16.1
2
79
223
100*0
*-
oo
-------
TABLE A-16. PRIMARY FUEL BY YEAR SOLD FOR WATERTUBE BOILERS
PRIMARY FUEL
COUNT T
flOW PCT I
rni CCT T
TOT PCT I
ITEAR SOLD 1-
65. I
T
T
I
_
66. I
I
T
I
— T —
67. I
T
I
T
_T _
6B. I
I
I
I
— T —
69. I
I
T
I
~ I ~
70. I
I
T
T
_ T _
~-l ~
71. T
T
T
I
-I-
COLUHN
TOTAL
6ITUMINO OIL
-0.
6
0.5
26.1
0.1
l*
-0.3
17. t*
0.0
c
0.0
0.0
0.1
1
0.1
G'.'o'""
0
0. P
0 .2
0.3
2
0.?
8.7
C.O
7
0.7
30. (4
0.1
23
0.?
I
T
T
T
I
T
I
I
T
T
1
I
T
T
T
I
I
T
T
I
1
I
f
T
T
I
T
T
I
T
1
1
161
13.7
27. f
1.7
130
10.2
21.8
1.4
78
8.2
13.1
0.8
3ft
4. 1
"~ 07 4"
4.3
8.2
0.5
38
0.4
33
3.1
5.5
596
6 . 4
.1
-T-
T
T
T
I
T
I
I
I
I
I
I
I
T
I
T
I
T
1
I
T
I
I
I
T
I
T
-1-
2.
316
12-.C
346
27.2
3.7
22.6
8.1
2. .3
?04
7.5
™"2T2~
230
20.3
a.a
2.5
311
30.9
3.3
386
36.2
2*28
28.3
NATURAL
I
T
T
_A_
I
I
I
T
I
T
I
I
I
I
y
I
I
T
T
1
I
I
I
T
1
I
T
I
•1
3
594
50.7
11.2
7C7
55.6
13. 3
7.6
598
6J. 2
11.2
619
67.. 6
11.6
7F.7
67.6
8.2
618
61. 4
6.6
535
50.2
5. 8
5322
57.2
WOODBARK HARASS?
.1
-I
T
T
I
T
I
I
T
I
I
I
I
I
I
I
_I
I
I
I
I
I
T
I
I
I
I
-I —
4.
13
1.1
3.7
0.1
u
0.3
2.7
0.0
6
0.6
0.1
11
1.2
TTi —
20
1.8
0.2
7
0 .7
4.7
0.1
17
1.6
0.2
149
1.6
I
T-
I
T
I
I
I
I
I
T
1
I
I
T
T
T
I
T~
I
T
I
I
T
I
I
T
I
I
1-
0.
0.
0.
0.
0.
c.
0.
0.
6.
0 •
0.
13.
0.
0.
6.
0.
1
0.
22.
0.
4
0.
5.
2
?
0
2
2
0
3
0
0
0
•5
3
8
6
5
fe
1
3
3
8
0
0
9
7
1
4
5
BLACK LI
OUOP
I
T-
I
T
I
I
I
I
T
T
I
I
I
I
I
I
T
-\~
I
T
I
I
I
T
I
I
I
I
I
•1-
6.
19
1.6
16.8
0.2
15
1.2
13.3
0.2
0.4
3.5
0.0
5
0.5
071—
12
1.1
10 .6
0.1
9
0.9
8.0
C.I
16
14.2
0.2
113
1.2
OTHFR FU
Ft s
I
•f
T
T
I
T
V
I
T
I
I
I
I
I
I
T
I
I
T
I
I
1
I
I
I
T
I
1
I
T
I
7.
j_ "
C.6
64
5.0
19.8
0.7
4.9
14.?
0.'5
35
3.8
1C. 8
074~~
4.0
13.9
0.5
13
1.3
n.i
16
t* • 9
0.2
324
3.5
I
T
I
T
I
I
I
I
I
I
I
I
I
I
T
I
T
'1
I
T
I
T
I
I
I
I
I
I
I
•1
WASTEHES WITH AIJX
ft
0
C.O
C.O
0.0
0
0.0
0.0
0.0
0
O.C
0.0
0.0
0
C.O
C.O
' d'.c
0.2
2.4
C.O
0
0.0
O.P
0.0
48.8
82
0.9
>. T
,_T.
T
T
I
T
T
I
T
I
I
I
I
I
T
I
I
~r
T
I
I.
I
I
I
T
I
I
I
T
T
1
9.
0
c.c
0.0
0.0
D
O.C
0. C
0.0
G
0.0
O.C
0.0
0
0. 0
p._o _
3
0. 3
0. 0
c
0.5
31.3
0. 1
5
0. 5
.31.3
Q.I
16
0.2
I
• T
I
J
I
I
•T
I
T
T
I
•I
I
I
Y
T
I
I
I
r
i
T
I
I
T
I
I
T
I
I
T
ROW
TOTiL
1171
1E72
11.7
. 1C. 2
9>16
9.8>
1134
12. 2
1006
10.8
1065
11.4
93P2
100.0
tCONTTMJEO)
-------
TABLE A-16. PRIMARY FUEL BY YEAR SOLD FOR WATERTUBE BOILERS (Continued)
PRIMARY FUEL
COUNT
ROW PCT TLTC
nni. pr.T i
TOT PCT T
Y^/SP SOLD 1
65. t
T
I
I
.-T
fbfb. T
I
T
1 '
-T
67. I
T
I
T
_T
63. I
I
T
. j
~ L • ~
59. I
I
I
I
-I"
70. I
T
T
1
-T — ~
71. J
T
. a
I
-I--
COL'JMN
TOTAL
NTT'
1<5.
0
0.0
1 .0
0.0
0
:.o
n.o
c . a
a
e.o
:TO
rj .0
a
n.O
0 .Q
".•• .c
0
c.6
0.0
G .0
G
P . G
C .0
0 . n
u
C . 0
I' . G
C'.C
««
0.0
NON
OS
T
T
'I
T
T
T
T
T
T
T
T
-I
T
I
I
I
-T
T
T
T
T
T
I
T
I
I
I
T
1
T
I
f
T
-I--
-crxB
RE"OV
12.
•) —
0.0
0.0
0. 0
c
G . 0
0.0
0.0
0
0. 0
0. C
0.0
c
C. 0
G.O
0. G
0
G.O
0. 0
C.O
C
0. 0
0.0
0 . U
Q
0 .0
U . 0
0.0
1
o.c
I
T
t"
T
I
T
T
T
I
1
T
T
I
T
T
I
r
T
i
i
T
T
•1
T
1
T
"T
I
T
T
T
ry
ROW
TOTflL
1171
12.6
127? .
13.7
9^6
10.2
916
9TR
113£»
1?.2
10C6
10.8
1 C rr;
11. U
9.10?
100. C
01
o
(CONTINUED)
-------
TABLE A-16. PRIMARY FUEL BY YEAR SOLD FOR WATERTUBE BOILERS (Continued)
COIIUT T
ROW »CT I
POL PCT I
TOT PCT I
YEAR SOU) r.
72. I
I
I
T
73. I
I
.T
I
-T-
COLUMN
TOTflL
(CONTINUED)
PRIMARY FUEL
BITUMIMO OTL
US COAL
-0
3
C.3
13.0
0.0
0
0.0
o.c
0.0
2?
0.2
.T
-T--
T
I
I
T
T
I
T
T
-T--
I.I
37
3.6
6.2
O.fc
32
s'.l
0.3
596
I
I
I
T
•-1-
T
I
T
I
•-T-
2,
3-53
13. t
3.8
. Z.6B
35.5
10.2
2.9
262?
2ft. 3
NATURAL
f.AS
.1
I
T
T
I
-1-
T
I
I
I
•I-
3
52. H
10^.3
336
6.3
3.6
5322
57.2
WOCORARK BAGASSE
.1
I
I
I
I
-I —
I
I
I
I
-T--
*
27
2.6
18.1
0.3
<*!,
5.8
29.5
0.5
1.6
.1
T
I
I
T
I
I
I
I
-T-
0.
20.
n.
1 .
20.
0.
It
0.
b
9
9
5
1
q
2
5
1
<+
5
BLACK LI OTHrP F
QUO? ^IS
• i
T
I
I
T
T
I
T
I
-T-
6
18
1.7
15.9
0 .2
1.5
2.0
13.3
C .2
113
1.2
.1
T
T
I
T
T
I
T
I
-T--
7
15
0.2
30
u.e
9.3
0.3
«;
U WASTFHEA W
T
T
I
T
I
T
-I-
T
T
T
T
8
25
30.5
0.3
15
2.0
C.2
0.9
. I
I
T
I
T
T
I
T
I
ITH AUX
F I ° T N r.
9.1
0. 2
12. C
0.0
0. 1
0.6
16
0. Z
I
T
I
T
-I
T
T
T
T
T 0 T fl L
1D37
11.1
75:5
8.1
930? p
18
-------
TABLE A-16. PRIMARY FUEL BY YEAR SOLD FOR WATERTUBE BOILERS (Continued)
COUNT
'J
PRIMARY FUEL
ROW PCT ILIG"'
COL PCT I
TOT PCT I
7? .
7.1.
COLUMN
TOTAL
1
-I
1
I
-1 •
T
I
I
I
0
0
D
lOfl
0
0
lit
1C
IJ
.0
'.0
•4
. b
.0
. U
.0
IVON-COMB
US REWOV
.1
T
T
I
I
-!-•
T
I
I '.
\
0.
0 .
0.
u .
0.
0.
12
a
0
u
3
1
1
0
U
1
0
. T
1
I
1
T
1
-.1
T
1
I
T
TOTAL
lu
11
37
.1
755
8
100
.1
.«•
. *-"
N)
-------
TABLE A-17. PRIMARY FUEL BY ALTERNATE FUEL FOR WATERTUBE BOILERS
COUNT I
ALTERNATE FUEL
HOW PCT 1NCNE
COI PCT 1
ror yci i
0. i
1
1
i
i . i
Bl fUMINOUS COAL 1
1
1
2* l
OIL 1
i
i
-1-
3. 1
NATURAL OAS i
i
i
4. 1
WOODBARK i
1
1
-1-
5. 1
i
i
_ i _
6. 1
BLACK LKJUOR 1
1
i
-i-
COL UMlv
TOTAL
X
b
all
454
12. to
5.0
69.6
19.5
102b
19.0
28.5
11.4
73
53.3
ol0
16
JO. L
0.4
&.<:
2J
21.1
0*6
U.3
3607
•+G.U
1
-1-
1
i
i
1
1
i
i
1
1
1
1
1
1
i
1
I
1
1
1
1
1
I
i
i
1
i
1
-1-
u
-------
TABLE A-17. PRIMARY FUEL BY ALTERNATE FUEL FOR WATERTUBE BOILERS (Continued)
COUNT
ALTERNATE FUEL
ROW PCT it
COL P£T 1
10T PCT T
7. i
OTHER FUELS i
i
8. 1
1
-I-
T* — r
WI1H AUX. KTfilNti 1
1
i
)0« i
LlljNITt i
1
-1-
LUI UMI\
TOTAL
iW*£.
~~3?
52.3
4. 7
i.y
.7
0. t)
^6.7
0.1
0. J
3
1 C0«0
0. i
u.-3
4 0 • u
1
-I-
1
1
1
1
1
I
1
1
1
1
1
1
1
1
1
-!-•
0
o.o
o.c
«?.o
&
o.c
G. 0
o.o
O.U
0-0
0
0.6
0*1}
— 37—
~~B
0
1
1
1
1
I
I
1
I
1
-i-
1
1
I
1
1
1
1
-1-
iTuniw
S COAL
1
1.2
la. 2
0.0
. 0
o«o
n.o
u.u
o.o
O.U
o.o
0
o.o
6>o
0.2
0 OIL
I
I
I
I
T
I
1
I
1
1
I
T
I
1
I
1
-I-
2
63
19. f>
l.ts
-0.7
U
0*0
0.0
o.O
5~
33.3
0.1
0.1
0
0*0
0.0
0.0
47.9
NATURAL
GAS
I
1
I
1
I
I
1
I
I
I
I
I
I
1
I
I
3
bb
17.1
0.6
&
o.o
0.1
40.0
0.7
0.1
0
0.0
0.0
u.u
9^6
WOOU bA
K
1
i
1
i
i
-!-•
1
1
}
1
1
I
I
1
1
*
0
O.u
O.u
0.0
U
0.0
o.o
0
0«U
O.U
0*0
0
0«G
o.o
0.6-
10
0.2
R BLACK LI o
UUOH t
i
l
i
I
-i —
i
i
i
i
-i —
i
I
I
i
I
1
i
i
6
0
0.0
o.c
0.0
0
0*0
0.0
0.0
0
0.0
0.0
0.0
0
o.o
0.0
OeO
1
0.0
1
1
I
i
I
-1-
1
1
I
i
-I-
I
I
1
-1-
I
1
I
1
THt!H f-
LS
7
31
9.7
2i.7
0.3
0
0*0
0 .0
o.o
u
0.0
O.u
0.0
0
0 »0
o.o
O.o
1.6
J w,
T
1
i
I
1
I
-!-•
1
1
1
1
- f _.
I
1
i
-i —
1
1
I
—[—
b
U
0.0
O.u
0.0
0
0.0
0.0
u.u
0.0
0.0
0.0
0
0«0
0.0
GVO
£.
0,0
A
I
I
I
I
I
~T
I
1
-I1
1
I
I
I
-I-
I
1
1
1
with
• t- IK
0.
0.
0.
ov
0.
o.
0.
0.
0.
o.
u.
0.
0.
AOX
INd
0
0
b
0
0
0
0
0
u
0
0
0
0
0
0
0
z
0
I
1
i
I
I
I
1
1
1
1
I
1
i
1
1
1
TOTAL
321
3.6
79
•••-0.9
o.?5
3
0*0
-900"
100. 0
NOMBtiH OK MISSlNli OOStHiVMTIUNS =
-------
TABLE A-18. ERECTION METHOD BY PRIMARY FUEL FOR WATERTUBE BOILERS
PRIMARY FUEL
COUNT I
HOW PCT
COL PCT
TOT HcT
ERECTION METHOD ._
1
PACKAGED
2
FIELD ASSEMBLED
.
COLUMN
TOTAL
r5TTui*T»n
IUS COftL
1 I
36
9.5
6:0
0.4
560
27.9
^4.0
6-0
. .
5*6
6.4
r
i
-i
i
i
T
I
1
I
I
I
OIL
'
?g.7
79.4
??.5
ii42
?7.0
?0'&
5. a
?S«3
NATUHAL
GAS
I 3 I
-I 1
I 67.4 I
I 92.2 I
I 52.9 I
1 416 I
I 20.7 1
I 7.8 I
I 4.S I
-I 1
!>3Z1
57.4
WOOUBAHK BAGASSE
4 I 5
1
32 I 0
0.4 I Q.O
21.5 I 0.0
0.3 I 0.0
117 I 44
5.B 1 2.2
7ft.5 1 100.0
1.3 1 0.5
1
149 44
1*6 0>5
BLACK Li
QUUrl
I 6
1 4
I 0.1
I 3.5
I 0.0
I 109
I i.4
1 96.5
I .1.2
.1
1-2
OTHER F
ELS
I 7
I.. ._
J 148
I 2.0
I 45.7
I 1.6
I— -----
I 176
I 8.8
I 54.3
t 1.9'
I
324
3.5
U-ff]
T
1
-T-.
I
I
I
I
-1 —
I
I
I
T-
ETCHES"!
8 I
" "53 I"
0.7 I
0.6 T
29 r
1.4 I
35.4 I
OTS I
0.9
7ITH AJX LIGNITE '
FIRING
. 91 10 I
~~9 I 0 "I
0.1 I 0.0 I
56.3 I 0.0 1
0.1 I 0.0 I
1 4
71 41
0.3 I 0.2 i
43. 3 I 100.C I
0.1 I 0.0 'I
1 1
16 4
0.2 0.0
NO^-corvj ROW
us ntMUrf TOTAL
12 J
0 I 7273
0.0 I 7A.4
o.o
a. a
1 2ft05
O» 0 ? ] . 6
100. 0
6.C I
1 9?76
0.0 100. ft
OF MISSING
-------
TABLE A-19. ERECTION METHOD BY YEAR FOR WATERTUBE BOILERS
CQMT I
HOW PCT i
COL PrT I
OT PCT i
ERECTION METHOD j
1 I
PACKAGED I
I
I
_ T
1 "
2 !
1
FIELD ASSEMBLED i
I
-I-
COLUMN
TOTAL
65
794
1 A Q
4 p • r
07. H
8.5
377
18.7
32.2
4.1
11 1\
1
i
I
1
I
T
I
I
-I-
tib
13.0
74.4
10>2
326
2s. 6
3.5
13.7
1
I
1
I
I
I
I
I
I
67
7iH
9.9
75.9
7.7
228
11.3
24.1
2.5
946
10.2
I
I
I
I
I
I
1
I
I
6B
787
85.9
8.5
"TzT
6.4
14.1
1.4
<»16
9.6
I
~r
i
i
i
i
i
i
i
69
932
12.8
82.2
10. 0
202
10.0
17. 8
2.2
1 134
12.2
I
I
I
I
I
I
1
T
I
/O I
806 I
11.1 I
60.1 I
8.7 I
200 I
9.9 1
19.9 I
272 T~
1006
10.8
71
866
11.9
81.4
9.3
1V8
9.8
18*6
2.1
1064
11.4
~T
I
1
I
I
1
f
.1
72
~8~3l -
11.4
80.2
8.9
205
10.2
19 .A
2.2"
" Id36
11.1
I
I
T
T
-I-
T
I
T
73
605
8.3
60.1
6.5
774 -
1 O . Q
* 7 » 7
1.6
8.1
T
-1
T
1
T
-1
T
I
-
ROW
7265-
7b.3
20 IS
~2T. 7
1
~9TCO'
1 00 . 0
Of Ml S'SlNG
-------
TABLE A-20. FIRING METHOD FOR COAL BY YEAR FOR EACH WATERTUBE CAPACITY CATEGORY — 10-16 KPH
YEfl"
ROM OCT
roi PCT
TOT PCT
FIRING
-C.
?.
SP*E*OE* STOKER
T.
UMD£PFfEO STOKER
COLIIMM
TOT«L
C.
e.
o.
e.
0.
0.
56.
100.
16.
30.
S5.
0
n
0
0
n
0
0
1
T
0
0
0
3
0
r
t
t 0
r o
t 0
100
100
eo
0
0
0
zo
66.
0
.n
.c
• o_
2
.0
.0
.u
'0
.0
.3
.0
2
.0
I
I
T
T
I_
I-
T
T
I
T
I
T
T
T
T-
67.
?
105. D
60.0
30..0
o
o.c
0.0
0.0
2
33.3
50.0
20. C
<•
1*0.0
I
T
T
I
T
I
T
I
I
I
T
I
T
I
n
0
0
0
0
0
If.
100
1 0
10
M.
0
• n
.0
.0
o
.0
.0
.0
1
.7
.0
.1
1
.0
I
I
I
T
I
I
I
I
t
T
I
T
I
T
T
?nu
TOTAL
?
20. n
z
20.0
6
60.0 •
10
100.0
Ui
-------
TABLE A-20. FIRING METHOD FOR COAL BY YEAR FOR EACH WATERTUBE CAPACITY CATEGORY (Continued) -- 17-100 KPH
caiwr T
ROW r-CT T
COL PCT i
TOT "CT I
-0. 'I
I
I
I
1. T
I
r
-i
7. T
?PR£flOER STOKER I
T
I
.1. I
I
t
-I
ir. — r
. . • -J
r
5.
OTH.iJ SOLIO
_
COLUMN
THT4L
vnu —
65.
17" '
1.0.5
7.5
0
C-.O
t.o
6. 0
35.6
'U?.l '
I*.?
28.6
3.5
n —
1.1 .9
1
1 .1
...!l!..
7<> --
33.6
1
T-
I
T
T
I
T
I
I
1
T -
T
T
T "
I
I
T
I
t
I
T
I
T
f
I
1
I-
6b . I
T
11
76.3
10.0
U.9
1
100.0
1.6
o.u
"26
20.9
11. *5
13
1.3.9
19.7
5.3
16.3
11.5
T.I
1.
tfl.?
b.6
l.B
" 61
?7.0
"T
T
I
T
- -I
T
T
T
1
- -I
'T
r
~ T
T
- - I
I
T
r
T
— r
T
T
T
T
f
I
1
--T
67. I
1-
u.C
0
" 0.0
o.r
O.n
15.6
6.2
1
1.6
3.1
•••'fl.lt
r
i!i
_ O.i.
7
31. R
31.9
.'•1
3?
I
I
1
--T-
I
I
I
I
T
T
" r
i
i
T
I
I
— r~
T
~ T
T
1
I
T
I
--T-
f>
«,.!
o.o
0.9
0
"0.0
0.0
D.O
" 5
5.6
"20.3
3
10.7
13.0
1.3
11.6
20.0
3.Z
10
1.5.5
1.0.0
U.U
11.1
«. 1
T
I
T
I
I
"I
T
I
I
I"
I
I
T
I
"I
--T-
— r~
_!..
I
I
I
1
1
— T-
69. T
"T I
7.1 I
17.6 I
1.3 I
1
0 t
"0.0 'I
0.0 T
0.0 I
7 - i
7.8 I
3.1 I
I
1 I
'3.6 I
5.9 I
~ O.k "I
1
6 — r
11.. e i
"3573~ I
7.7 I
0 I
4.6 t
0.0 I
O.U I
1
17
7.5
n
0
o.o
o.o
o.o
0
0. 0
0.0
U.It
1. 8
VI
I
T
T
I
-I
I
T
1
I
T
T
1
0 I
— 0.0 T
0.3 I
OYO~I
1
5~
_11.5_
3.2
0
' 0.0
0.0
U • U
-q
~T
I
— r
i
i
~T
I
1
r
c
0.0
n. C
0.0
0
~ -• o . o
0. 0
0.0
U
0.0
Tl.D
0.0
2
7.1
100.0
0.9
ff
0.0
— o.o
0.0
0
O.ff
u . u
a. 9
TTI
I
T
I
r
--i
T
""I
T
— r
r
I
T
I
--T
r
i
i
~T
--T
— r
_r
T
r
— r
T
I
rv.
0
o.c
o.o
0.0
c
D'.G"
a .c
U.O
i
i .1
' rao.o
O.U
0
-•-o.o •
o.o
o.o
D —
o.o
0. 0
0.0
0
fl.o
0.0
u . u
1
o.u
T —
I
T
I
I
T
r"
T
I
I
T
I
I
I
1
T
I"
I
I
I
I
1
r
o.o
o.o
o.c
c
"C -. 0
o.c
— GTtr
- r
1. 1
13.3
O.U
1
3.6
1
?. 3
33.1
0
6.G
0.0
0.0
3
1.3
RHU
TOT4L
f. 1
I 19. fc
T
I
T 1
I
1
T ~*?0
i 39.a
i •
T
I 2P
I 13. U - -
I
I
I I.1! '
"T
T
-- I
T 22
T 9.7
I
I
100. 0
Ul
oo
-------
TABLE A-20. FIRING METHOD FOR COAL BY YEAR FOR EACH WATERTUBE CAPACITY CATEGORY (Continued) -- 101-250 KPH
cflom
COL °CT
TOT PCT
FTflJWG
-C.
1.
PULVERIZED CO«L
SefttaOF» STORES
u.
OvEffrCEJ) STOKER.
5.
81|ffiR..SOL19. ._
COL'IMN
I
I
I
T
-T--
I
I
I
T
I .
I
I
I
-T--
" T
I
I
T
I
I"
I
I
T
I
. I .
65
ll.n
1 .9
8
32.0
7.5
15
60.0
0
070 "
0.0
0.0
B~
0.0
e.i
6.0
?5
^3.6
.1
-T
T
T
I
T
I
T
t
I
-T
I
T
I
-I
T
T
T
"I
-T
T
I
T
I
f,
8
U7.1
£9.6
3
17.6
1 1.1
Z.9
" 11
19.3
(•0.7
Z
7.1,
1 .9
30.0
11.1
27
^.T
--T-
I
I
I
T
I.
I
I
I
•-T-
I
I
J
•-!-
T
I
~T~
•-T-
I
I
I
67.
3
17. f.
30.0
ii.R
zo.o
1.9
It
7.0
(.0.0
0
— o;o -
o.c
576
1 —
10.0
10.0
0.9
10
9.1*
I
T
I
I
t
I
I
I
I
I
T
r
i
i
i
T
T
I
T
I
I
I
I
I
69
1
7.1
P..2-.
1
5.9
7.1
0.9
6
10.5
0
"P.B
0.0
.1
-T —
I
T
I
-1-7
T
I
I
I
I
69
0
0.0
0.0
0.0
0
o.o
3.0
d.j
7.0
T 100.0
-I —
I
T —
I
0.0 ' I
1"
E~
60.0
5.7
11.
1 13.2
I"
I
I
0
-07TT
0.0
0.0
•-•fl
0.0
"0.0
0.0
k
J. fl
.1
-T-
I
I
I
-1-
T
I
I
I
I
1
-I-
I
I
1
-T-
T
I
I
70.
0
0.0
0.0
0.0
0
0. 0
0.0
0.0
- i,
7.0
80.0
1
~7o i'o™'
?o.o
0.9
0
0.0
0.0
0.0
5
fc.7
I
I
T
i
T
t
I
T
I
I
T
T
I
I
I
1
T
I
I
I
T
71.
0
0.0
0.0
0.0
li.i
1.9
t"
7.0
soTF~
3.8
?
~5070 —
25.0
1.9
0
0.0
0.0'
0.0
R
7.5
r
I
T
I
I
1
T
T
I
I
I
r
T
T
T
7
I
I
T
r
i
T
72
3
17. f,
37.5
1
5.9
0.4
7.0
50.0
3.8
0
Q.O"
0.0
0 .0
0
0.0
P.O
0.0
8
7.5
.1
I
I
I
T
I
I
I
T
-T
• I
~T
I
I
-T
I
I
I
I
-1
73.
0
G.O
0.2
0.0
0
C. 0
0.0
0.0
6.3
To o" . 6
•..7
0
~ fl-. 0 —
0.0
0.0
0
0.0
c.o
0.0
q
I.. 7
T
T
I
T
I
I
I
T
T
T
I
T
1
T
r
i
r
i
i
T
r
i
r
T
f
fUW
TOT&l
17
16. P
17
16. C
57
53.8
5
10
9. it
10*
100. 0
Ui
-------
TABLE A-20. FIRING METHOD FOR COAL BY YEAR FOR EACH WATERTUBE CAPACITY CATEGORY (Continued) — 251-500 KPH
CO'iriT i
pOW oCT T
COL PCT I
TOT PC* I
-C. I
I
I
I
1. T
PULVERIZED COflL I
I
I
-!-•
?. I
SPR640E7 STClKCfl. I
T
5. T
I
I
9. I
MOM- SOL ID FUTl I
T
I
— ( » .
(>'.
1
25.0
f>.7
3.2
12
57.1
so. o
31.7
1
50.0
"|2
1
31.3
6.7
3.2
0
0.0
0.0
o.o
>7T
i
i
T
T
T
I
I
•-T-
T
T
I
I
T
T
I
T
y
T
T
I
£*.!
50.0
33. J
6.5
3
53.1
9. 7
' 0"
0.0
• o.o"
0.0
1
33.3
3.2"
0
o. g
0.0
o.o
t
I
1
T
T
I
I
I
-T
I
I
T
r
T
T
I
1
I
I
T
T
t7. T
0
0.0
O.C
0.0
0
" "0.0
O.C
0.0
0
O.G
"" 0.0'
0.0
1
33.3
100.0
3.?
0
0.0
- o.o
0.0
I
I
1
T
I
I
I
1
— T
I
I
" T
I
T
I
I
1
t
I
I
I
69. I
0
0.0
0.0
0.0
2
"9.5
100.0
6.5
n
o.o
0.0
0.0
0
"0.0
0.0
0.0
0
0.0
-o.o
0.0
I
1
T
I
f
I
1
--T-
I
I
"T
I
I
— r
I
1
I
I
I
70
0
0.0
0.0
0.0
1
-------
TABLE A-20. FIRING METHOD FOR COAL BY YEAR FOR EACH WATERTUBE CAPACITY CATEGORY (Continued) -- >500 KPH
COUNT T
ftnn PCT T
COL PCT i
ror PCT i
-0. 1
I
I
-I-
I. -I
PULVEH,I7ET> COAL I
T
I
• T •
5. I
orneg SOLID i
i
T
-i-
9. T
NOH-SOLTO FUfcl I
T
I
-T-
COLUrtN
TOTSL
&5
3
10.0
1 .3
. 19 _
19.0
63.0
1ft. 3
5
23. 0
10. ft
2.1
0
C.O
e.i
e.o
1.7
19.7
I
I
T
I
I
-T--
I
I
T
I
I
T
I
T
-I-
I
I
T
t
-T-
6<
i.n.n
10.8
1. 7
1377
75.7
11.7
5
Z3.8
t3.5
?.l
0
0.0
0.0
0.0
77
15.5
T
I
._T-.
_!._
I
I
"I
T
T
T
--T-
T
I
I
--I-
67,
3
11.0
9-1
1.3
17. ._
13.2
81.X
11.3
1«..3
9.1
1.3
0
C.O
0.0
•o;o""
33
13. P.
T
I
T
I
1-
I_
I
I
T
I
I
T
I-
T
I
I
I
I-
*.«».
0
9.n
Lo
0.0
9ft!7
12.1
1
it.1
3.3
O.U
0
0.0
0.0
0.0
3Q—
12.
-------
TABLE A-21. PRIMARY FUEL BY STANDARD INDUSTRIAL CODE FOR WATERTUBE BOILERS.
COUNT I
ROW PCT I
COI PCT T
SIC CODE T
0 . T
NON-MANU I
I
I
1. I
I
I
I
-T-
9. I
I
I
I
15. I
OFFfCF.S I
T
-T-
20. T
FOODS T
T
T
21. I
TOBflCCO I
T
I
-I-
?2. I
TEXTILES I
I
T
COLUMN
TOTAL
(CONTINUE1!)
PRIMARY FUEL
US COAL
0.?
oil
0
G .0
0.0
C .0
c
0 . 0
n.n
G
r. o
O.C
0.0
0.?
e. 7
0. 0
0
0.0
0. 0
"3 . 0
1
C.2
4. 3
0.3
?3
0.2
T
T
T
T
•-T-
T
T
T
I
•-T-
I
T
T
I
~I~
1
T
I
-T-
{
I
T
I
I
I
I
I
I
I
T
**!
11.3 I
52.3 T
3.4 I
T
0 I
0.0 T
0.0 I
0.0 T
T
0 T
0.0 I
0.0 I
0.0 I
0 I
0.0 I
0.0 I
o.o r
4.9 i
2 I
9.5 T
0.3 I
0.0 I
1
16 T
2.9 I
2.7 I
0.2 I
----- — I-
596
6.4
DTL
C
2°.l
3G.5
0
0.0
O.C
0
0.0
0.0
1
2 5 . C .
0.0
0.0
?\*l
7.1
•>
9-5
0.1
0.0
" 1«5
70.3
6.3
1.8
2628
28.3
MflTUPftL
r,AS
''*
T
T
T
•- 1-
T
I
T
I
— I-
I
I
I
I
T
T
I
J
i1
i
T
I
I
I
I
T
~T~
T
-
3
57.6
29.8
17.1
t
100.0
0. 0
0.0
1
100.0
0.0
0.0
1
75. 0
0.1
0.0
576
66.3
1C. 8
17
ftl.O
0.3
0 . 2
360
66.2
6.3
3.9
5322
57.2
WOODBARK RAGASSf^
•T
T
I
T
-1-
I
I
T
T
1
T
I
I
I
I
1~
I
I
-1--
I
I
T
1
1
I
I
T
-•
k
0.1
1.3
0.0
0
0.0
0.0
3.0
C
0.0
0.0
o
0.0
0.0
"OVO
0.1
0.7
a
0.0
0 .G
3 .0
0
0.0
-1
T
T
I
-I--
I
I
I
I
T~
I
I
I
I
1
I
r
f
r
-T--
r
I
T
I
I
I
"" O'.O T
0.0 I
149
1.6
-I —
b
0. 0
3. 0
0.0
„
0.0
0.0
0.0
0.0
0.0
c.o
o
0. 0
_0 . 0_
0*0
4.6
^o'.t
0
0.0
0. 0
0.0
0
0.0
0. 0
o. a
44
0.5
RL/SCK L
QHOR
-1
T
I
T
-I-
I
I
I
~I
I
I
-I--
I
r
~1—
-T --
I
-I.--
I
I
I
i
I
I
I
I
6
0
0.0
3.C
0 .C
c
0.0
0.0
3.0
0.0
0.0
0.0
0
0.0
0.0
TT. 0 "
0 .0
0~YC~~
0.0
0
0.0
0.0
0 .0
1
0.2
079"
n.o
113
1.2
I n
T
T
I
-1-
T
I
T
I
I
I
T
T
-T-
T
1
T
I
1
I
T
-T--
T
T
I
1
T
I
~r~
i
• i —
TH'o FU NASTEHF4 HTTH »!!jy ROW
LS T . FT3Tf.T. TOTffl
7
1 .5
12.3
0.4
C
0.0
G.C
O.C
0
0.0
0 • 0
0.0
„•
C .0
0.0
" ~ 0 V 0
3"
1C. 2
0.4
c
G.O
fl.O
G.O
1
0.2
C .3
0.0
3?4
3.5
•I
T
T
L
I
-i-
T
T
1
T
I
•J
I
T
I
r
:
T
-i-
T
I
I
1
I
I
I
8.
0.3
fl.5
0
0.0
Q.G
C.C
0
0.0
C.O
c.o
••-
c.o
n.o
" "O.'O""
0.0°
O.G
0.0
G
0.0
0.0
G.G
0
0. 0
„_..„.. ..
0.0
?-2
0.9
I
T
T
I
I-
T
T
L
T
T
I
}•
I
T
T
I
T
T
r
T
I
I
T
I
T
I--
O.C
0.0
o
O.G
G.G
0.0
0 . C
0.0
0.0
— -
0. C
0.0
CYC
1
6. 3
0. C
f!
0. 0
0. C
C.C
0
0. C
0. C
0. C
16
0.2
9.1
T 2Q. A
I
--I
I 1
T 0.0
T
I
I 1
T O.C
I
T
T 4
T 0/..C
T
T
T l^
T 9.1
I
T
•-I
I 21
I 6.2
I
I
T 5n<»
I 5". 6
f
T
-I
9302
10C.O
-------
TABLE A-21. PRIMARY FUEL BY STANDARD INDUSTRIAL CODE FOR WATERTUBE BOILERS (Continued)
PRIMARY-FUEtT
COUNT
ROM PCT ILIGNTT? NfON-C(U*Q PPW
COL PCT I US REMOV TOTflL
SIC CODE
NON-MflNU
Ot-l- Ultb!
FOOTS
TOBACCO
TEXTILES
OT PCT T
C. 1
I
I
I
-I-
1. I
I
I
T
9. T
I
T
T
-T-
1
T
I
-I-
-------
TABLE A-21. PRIMARY FUEL BY STANDARD INDUSTRIAL CODE FOR WATERTUBE BOILERS (Continued)
PRIMARY FUELS
COUNT T
POW OCT T
COL «>CT T
TOT °CT I
SIC CODE T
23. I
T
T
I
Zk. I
LUMBER I
I
I
?5. T
T
T
I
-I-
26. I
PflPEK I
T
I
-I -
26. T
CHEMICALS I
I
T
-T-
?.9. I
PETROLEUMS T
I
I
30. I
RuggER T
I
I
-T-
13 ITU MIN-
US COAL
-C.
0
C .0
0. 0
0.0
0
C. D
C.O
C.O
0
13. 0
Q.C
C.C
1
0 . ?.
C.3
"iJ'.O"
3
0.3
17.0
0.0
n
C.O
o.o
0.0
3
0.0
G.O
P.O
I
T-.
T
T
T
I
T
I
T
I
I
I
I
T
1
I
I
I
I
1
I
1 -•
I
T
I
I
1
T
T
I
1--
4
C
o.c
0. 0
0.0
9
3.5
0.1
1
13.3
0.2
0.0
25
<4. B
t».2
OT?
37
3.5
fj. Z
O.l»
6
1.1
l.C
0.1
3
l.<*
0.5
G.O
0 OIL
.1
-I-
T
I
I
I
I
;
i
i
T
I
I
-1-
T
I
I
1
I
I
T
-1-
I
T
I
I
1
I
I
I
-1-
2.
0
C.O
0.0
0.0
3k
13.2
o.«*
0
o.c
0.0
C.O
1M?
28. D
5.6
" I.". '
2*
5 . 0
17,-!-•
ft.
0
O.C
0.0
C.O
3
1.2
3.7
0 .0
0
o.c •
C.C ~
0.0
15
? . 9
i B . 3
CV2
12
1 .1
1<* . n
0.1
' 13
2. 3
15. T
0.1
1
C.5
1..2"
C. 0
VIITH AUX
. PIPING
I
T--
I
I
I
I
T
I
I
I
I
1
T
• 1--
T
I
I
1
i
T
I
T
• 1--
I
T
I
I
i
I
I
I
•1--
9.
0
0. C
C.O
C.C
C
C.O
0. 0
0. C
Q
Q.O
'C.O "
0. 0
0
C . •„•
C.O
"0.0 '
3
0.3
16.7
0.1
6
1 . 1
37.5
Q.I
C
0.0
0.0
C.O
OQW
TOTiL
I
I
I 1
i o.:
i
i
i
I 25?
I ?..*
T
I
I
I 3
T 0.0
I
T
•I
T 5??
I 5.0
T
I ""
•T
I 10^7
I 11.'
I
'I
I 5f.=
T '-. . 1
I
T
•I
1 ?17
I 2.3
T
T
•I
(CONTINUED)
COLUMN
TOTAL
596
_
0 ."2
6. <*
U.5
J32
0". 9~
If)
910?
"iCO.O
-------
TABLE A-21. PRIMARY FUEL BY STANDARD INDUSTRIAL CODE FOR WATERTUBE BOILERS (Continued)
PSIMFIJEL
COUNT
ROW PCT ILIGNIT?
COL PCT T
SIC CODE T°T PCT E
Z3. T
I
T
T
2<*. I
LUMBER I
T
I
Zi>« I
I
I
I
— J — •
26. I
I
I
2«. I
CHEMICALS I
I
I
-I-1
29. I
PETROLEUMS I
I
I
L
JU • i
I
I
10
0
o.n
0 .0
0.0
0
0 .0
0.0
c.o
0
0.0
3.0
r.o
0
u . u
0.0
D . 0
0
3.0
r.o
0.0
0
a . a
c.o
0 . C
u
C.o
t.o
6.0
NON-COMB 90M .
US RFt-'OV TOTAL
.1
I
T
I
I
I
I
I
T
I
T
T
T
I
1
I
I
T
I
I
I
I
I
I
T
I
I
I
I
1Z
0
0.0
a . o
o.c
0
o.c
0.0
0. 0
0
0.0
3.3
0. 0
0
U • U
0.0
0. 0~
0
0.0
0.0
0. 0
0
u. u
0.0
0 . D
u
0.0
0. 0
0.0
L
T
T
I
-1
T
T
I
1
T.
I
I
I
T
I
T
~r~
T
i
i
i
-i
i
i
i
i
T
T
T
1
0.0
257
Z.B
3
0.0
522
t> .b
10*»7
11.3
565
h.l
2.3
I
ON
Ol
COLUMN
9702
TOT flL
B .D
(CONTINUED)
-------
TABLE A-21. PRIMARY FUEL BY STANDARD INDUSTRIAL CODE FOR WATERTUBE BOILERS (Continued)
PRIMARY FUEL
COUNT T
ROW PCT I
COL PCT T
TOT PCT I
SIC CODE T
31. I
I
T
T
T* • I
METAL I
T
I
PAB. MTTALS i
i
i
-T —
35. I
NON-E. MACH. I
T
I
37. I
TRANSPORTATION I
I
39. I
MISC-MANU T
i
i
-T--
<»9. T
ELEC UTILITIES I
I
I
Ci" LUMN
TOTAL
0ITUNINO OIL
us eoAi
-0
0
0/0
0.0
0.0
0
c . a
c.o
0 . C
c
C.G
C. G
c.o
0
0 . 0
c.o
0 . 0
0
0.0
1 . 0
c.o
1.
0 . 2
0. 0
9
2.0
39. 1
3.1
23
j .?
.T
-T-
I
T
I
T
-1-
T
1
I
I
-T-
I
T
I
I
-L-
T
1
I
I
-T-
T
T
L
T
I
I
I
T
-T-
nr
T
T
1
1
50. 0
0.2
0.0
11
3.9
1. 9
0.1
0
Q.O
O.C
0. G
0
0. 0
0.0
C. C
19
f>.7
0.2
16
2.6
2.7
0.2
93
20 .9
15.6
596
6.i»
.1
-T-
I
I
T
T
T
I
T
I
-T-
I
I
1
I
-I-
I
I
I
1
I
I
1
I
-1-
T
I
I
I
-T-
1
T
L
-I-
2.
0
0.0
0.0
C.C
flf-
27.2
2.5
0.7
n
0.0
0.1
0.0
1
1 1 . 3
0.0
0.0
105
t».C
1.1
191
30.5
7.3
,.1
51.7
2.5
'628
28.3
GfiS
T
T-
T
T
T
I
1-
T
I
I
I
T-
I
T
1
I
1-
I
I
T
1
I-
I
r
i
T
1-
T
T
I
I
T-
T
I
I-
3
1
50.S
0.0
0.0
139
2.6
1.5
100.0
0.1
0.0
6
85. 7
0.1
0.1
155
51*. 1
2.9
1. 7
«»1 1
7.7
A. if
95
21.3
1. 3
5322
57.2
WOOOTARK BAf.ASSE BLACK
ODOR
.1
-T-
I
I
T
I
I
I
T
-T-
I
I
I
I
T
1
I
I
-T-
I
I
I
T
-1-
I
I
T
I
-T-
1
I
I
I
-1-
«,
0
0.0
0.0
C.C
0
0.0
0.0
0.0
0.
0.0
0.0
0.0
0
(1.0
Q.O
n.o
G
0.0
0.0
0.0
1
0.2
0.7
0.0
c
O.G
0.0
Q.O
1«,9
1.6
f.T
I
I
T
•-I-
I
I
I
I
.-!_.
I
I
T
I
.-I--
T
I
I
1
-T--
1
T
I
T
T
I
T
I
T
I
1
0
0.0
0. 0
0. 0
0
c.o
0.0
0. 0
o
0. 0
0.0
0. 0
n
G . Q
G. 0
~~0.0
0
0.0
0. 0
0 . 0
0
0.0
0.0
0. 0
0
0. 0
0.0
0. 0
<»<*
0 .5
b.l
1
T
I
T
T
I
I
I
I
T
I
T
"I-
T
T
I
— r
--T-
I
T
1
T
T
I
I
1
--T-
L
I
I
T
— I-
0
0.0
0.0
0 . 0
n
•J
0 .0
C .0
0 .0
0
0 .0
0 .0
0.0
0
0.0
0.0
0 .G
0
0.0
0.0
0.0
0
0.0
0 .0
0.0
0
C .G
0 .0
0 .0
113
1,2
LI OTH£R FU HASTEN
ELS T
6.1
I
T
I
T
— I —
T
I
T
T
t
T
I
T
I
I
T
T
T
I
T
T
I
I
T
I
T
T
I
I
1
7.
0
0.0
0.0
0.0
51
18.0
15.7
0.5
0
0.0
•QTO
C .0
Q
0.0
o.o___
1.1
P. 9
n.o
2
0 .3
0.6
0 .0
1
S.2
C.3
0.0
3^
3.5"
T
I
I
I
T
T
T
I
i
T
T
I
I-
T
I
T
I
T-
I
T
I
T
I-
T
T
T
I
I
I
I
T
I-
0
0. 0
C. 0
C . 0
1 3
15.9
0.1
0
0.0
G.O
C.O
G
C.C
0.0
O.C
Eft WTTH fi'jx flaw
. FIRIMf, TOTti
«. T
I
I
T
I
I
I
I
I
I
I
I
I
I
T
I
--T--
0 I
0.0 T
0.0
C.C
5
0. 8
0. 1
12
2.7
C. 1
82
0.9
r
T
I
I
I
r
I
I
T
I
1
0
0. C
0. 0
0. 0
u
1. (*
25. 0
C. 0
C
0. 0
O.C
o.c
0
0.0
c. c
0.0
O.i.
6.3
C. 0
0
c.o
C. 0
0.0
1
C. 2
ft . "?
0. 0
16
0.2
9.1
f 2
I 0 .0
T
I
T '«:>
I 3.1
I
I 3
I 0.0 3
; ~ i
I 7
I J.I
T
T "" "
--T
T 2SJ
I 3.C
I
I
T ^27
I 6.7
I
I
I I*.",
T
I
--T
930?
1CC.O
-------
TABLE A-21. PRIMARY FUEL BY STANDARD INDUSTRIAL CODE FOR WATERTUBE BOILERS (Continued)
COUNT
ROW
COL
PCT
PCT
PKTHARY
I
TLIGNITE
I
FUEL
NnM-COMB
US 3EMOV
TOTflL
TOT PCT
SIC CODE
31.
33.
Mb 1 AL
FAR. METALS
35,
NtHI-t. MflCH.
37.
TRANSPORTATION
39.
~ HTSC-MANU
ELEC UTILITIES
COLUMN
TOTflL
I
-T-
I
T
I
I
-1-
I
I
T
I
I
I
I
I
-1-
I
I
I
I
I
t
I
-I-
I
i
I
I
-I-
T
I
I
T
-1 •
in
o
0.0
0.0
0
C .0
0.0
c.o
0
0.0
'C'.'O™
0.0
0
u. u
0.0
o ."
0
0.0
1! .U
0.0
0
0. C
o.n
0.0
IT
0.9
100.0
c.o
«,
0.0
.1
I
t
I
- 1 -
T
1
T
T
1
I
1
I
- 1-
I
1
I
I
1
I
I!
I
I
1
T
1
— r
I
T
T
1
12
2.0
0.0
0.0
0
0 . C
0.0
0.0
0
0.0
~~0 . C
0.0
0
u. u
0.0
0. 0
0
0.1}
u. u
0.0
0
0 . 0
0.0
0.0
- •• a
0.0
0.0
0.0
1
0.0
.T
-T
T
I
I
- L
T
1
T
I
I
I
T
I
-T
I
1
I
I
1
T
r~
T
I
T
I
1
• -I
— r~
I
I
I
--1
0.0
2*U
J.I
0.0
7
OTI
383
3.0
637
6.7
<».9
930?
100.0
<^
•vj
(COMTTMUEO)
-------
TABLE A-21. PRIMARY FUEL BY STANDARD INDUSTRIAL CODE FOR WATERTUBE BOILERS (Continued)
PRIMARY FUEfc-
COUNT
POW PCT
COL PCT
SIC CODE T°T PCT
65.
APARTMENTS
8C.
HOSPITALS
32.
SCHOOLS
ILIGNITE
T
I
T
J
I
T
I
I
T
I
I
I
I
-T--
C
10.
c
.n
0.0
C.O
I!
0
p
0
(J
0
0
. 0
.0
.0
0
. G
. G
.0
NON-COMB
US REMOV
T
1
I
r
r
I —
T
1
T
I
I
I
l
T
n
G
0
U
0
0
0
0
12
0
.0
.C
.0
0
. U
.0
.0
0
.0
.0
. 1
T
T
I
I
T
T
T
T
T
T
~r
i
-i
flow
TOTAL
2
0.3
537
5.8
302
3.?
COLUMN
TOTAL
9302.
ON
00
C .C
-------
TABLE A-21. PRIMARY FUEL BY STANDARD INDUSTRIAL CODE FOR WATERTUBE BOILERS (Continued)
PRIMARY FUEL
COUNT T
ROM PCT T
COL PCT T
TOT PCT T
SIC CODE x
65. I
APARTMENTS i
T
i
10. I
HOSPITALS I
I
T
SCHOOLS T
I
I
COLUMN
OTfiL
BITUMINO OTL
US COAL
-0
0
o-. o
0.0
0.0
0
c.o
0.0
0.0
0
G . 0
C .0
1 .0
23
D . 7T
. 1
-T--
I
I
I
T
-T--
I
T
I
I
I
I
T
I
1
0
0.0
0.0
0.0
4
0.7
0.7
0.3
12
4.0
2.0
0.1
596
b.4
.1
-T-
I
I
I
I
- 1 -
T
I
T
I
-I-
T
I
I
I
-1-
2
0
O.P
0.0
0.0
139
25.9
5.3
1.5
fil
3.1
P. 9
2*29
VH..J
NftTURAL
GAS
.1
- T-
I
T
T
T
-1-
T
I
I
I
-T-
I
T
I
I
-1-
3
2
100.0
0.0
0.0
394
7.4
4.2
207
68.5
3.9
2.2
5322
t> 1 . Z
WOOOSAP.K OAGASSE
.1
I
T
I
T
I
I
I
I
I
I
I
-1--
0
0.0
0.0
0.0
0
0.0
0.0
0.0
c
O.C
0.0
0.0
149
'1.6
4.1
— I ..
I
T
T
I
T
I
T
I
I
I
I
I
— I —
n
0
0
u
0
u
0
0
0
0
5
0
.n
.0
. n
0
. 0
. 0
. 0
0
. 0
. 0
.0
44
.5
BLACK LT OTHE
OUOP -LS
.T
-I -•
I
T
I
T
-I —
I
I
I
1
I
I
I
I
6
0
0.0
0.0
0.0
0
0 .0
0.0
0.0
0
0 .0
0.0
0.0
113
1.2
. I
T
T
T
T
T
I
I
T
I
T
T
f
-I —
n
0
n
0
0
0
0
0
0
R FU WASTEHEA WITH A'JX
T . FIRINf-
7
0
.n
.0
.n
0
.u
.0
.0
1
.3
.3
.0
.1
I
T
I
T
T
1
I
I
I
T
I
T
324
.<
.b
*
0
0.0
0.0
0.0
0
0.0
0. Q
c.c
1
0.3
1.2
O.C
92
u.y
.1
i
T
I
T
T
I
I
I
T
I
T
1
n.
0.
n.
0.
0.
0.
0.
0.
n.
1
—07
9
C
n
0
n
n
0
0
c
0
0
c
0
f,
2"
.1
I
T
I
T
-r
T
T
T
T
-I
T
I
T
I
-I
POW
TOTAL
2
0.3
537
5.8
I°l
930?
100. 0
-------
TABLE A-22. PRIMARY FUEL BY GEOGRAPHIC REGIONS
(See Page A-28 for state/region definitions)
COUNT I
ROW PCT 1
COL FCT I
not
TOT PCT Icoded °
PRIHFUEL 1
I . I
I
I
I
-I-
1. I
BITUMINOUS COAL I
I
I
-I-
2. I
OIL I
I
I
-I-
3. I
NATURAL GiS I
I
I
-I-
i.. I
MOOOBAR< I
1
I
-I-
5. I
BAGASSE I
I
I
-I-
6. I
BLACK LIQUOR I
I
I
-I-
0
b.O
J. J
Ci. 1
1
0.2
o.a
2. *
61.1
C. B
-7
I.E.
2«. 3
U.",
J
ti.o
*J • J
G.'J
G
1. J
G.O
i.. J
1
C.9
u.9
U.O
N.
.1
-I -•
I
I
I
I
-T--
1
I
I
-!-•
I
1
I
1
-T--
1
I
I
I
I
I
I
-!-•
Eng.
C
G
I
j
1
0
i
12
3
1
2
•'•1
I
2
(j
a
u
3
a
5
1
a
i
0
. 0
. c
. 0
5
.9
. 1
. 1
J i
. 2
. 2
.3
4F,
. a
. 3
.b
. 8
. a
;
.0
.0
. u
b
.5
. 3
.1
M-Atl.
.1
-T-
I
I
I
I
-1-
I
I
I
I
-T -
1
I
I
I
-i-
I
1
I
1
-T-
1
I
I
I
-1 -
I
I
I
I
-I-
1
I
I
I
-1-
2
0
0.0
O.'J
a. a
106
18.3
5.2
1.2
t 1.8
50.2
11.4
717
15. j
8.6
16
11.1
0. 8
0.2
0
0.0
0.0
o.a
e
7.3
0.1
E-N-C
. I
- T-
I
I
I
1
-1-
1
I
I
I
-T-
1
I
I
I
-J-
I
I
I
1
-T-
I
I
I
I
-1-
I
1
I
I
-T-
3
2
25.0
0 .1
o.e
244
<«2.1
12-. 1
2.7
327
13 .4
1W2
3.7
1371
26.1
67.8
15 .3
S.3
U .4
0 .1
9
25.7
U ."•
7.3
0 .4
3.1
.1
I
T
I
I
I
I
I
I
-T
I
I
I
I
I
a.
i
i
i
|
i
i
i
i
S-Atl.
i*
0
0.0
0.0
3. J
89
15.4
5.8
1. 0
15.7
25.0
l«. 3
912
17.4
~ 59.5
10.2
49
3<«. 0
3. 2
j.5
,,
11. 4
0. 3
40
36.7
2.6
W-N-C
.1
I
T
I
I
-1-
I
I
I
I
-T-
I
I
I
I
-1-
I
I
I
1
-T-
1
I
I
I
-1-
I
I
I
-T-
1
I
I
I
-I-
w-s-c
5.1
2
0.3
c.o
58
It.Q
P. 9
t.6
97
fc.O
1.1
tfld
9.1
73.4
•_.4
0
C.O
1.0
c.o
1
2.9
C.2
3.7
C.6
0.0
I
T
I
I
-1-
I
I
I
I
-T-
I
I
I
I
-I-
I
1
I
I
-T-
1
I
I
I
-l-
I
I
I
I
-T-
1
I
I
I
-1-
6
50.0
0 . 4
0 .0
18
3.1
1.7
0.2
86
3.5
S.3
1.0
764
73.7
8.5
16.7
2.3
0.3
18
51.4
1.7
a .2
17
15.6
1.6
0.2
fl
.1
I
T
I
T
-1-
I
I
I
-I-
I
i
i
i
-T-
1
I
I
I
-1-
I
I
I
1
-T-
1
I
I
I
-1-
.Mtn.
7
0
0. 0
0. J
0. 0
32
5.5
13.8
3.4
21
0.9
9. 1
0.2
169
3.2
72.8
1.9
1
0.7
0. 4
0.0
D
0.0
0.0
0. 0
0
. 0. 0
0.0
J.O
.1
I
T
I
I
-1-
I
I
I
I
-T-
I
I
I
I
-I-
I
1
I
-T-
I
I
I
I
-1-
I
I
I
1
-T-
I
I
I
I
-1-
NW
a. i
0
0.0
0.0
0.0
" 14
4)4
0.2
39
1.6
12.2
209
4.0
65.5
2.3
20
13.9
6.3
0.2
0
0.0
0.0
O.u
2$
22.9
7.8
0.3
I
T
I
T
•1-
I
I
I
I
•T-
I
I
I
I
-I-
I
I
I
I
-T -
I
I
I
I
•1-
I
I
I
I
•T-
I
I
I
I
-1-
SW
9.1
1
0
0.0
0. J
o. a
12
2.1
2.2
0.1
4. 1
18. 5
1.1
380
69.5
4.2
21
3. 3
0.2
3
8.6
0.5
0.3
a
o.a
0.0
o.a
i
T
i
i
•i
i
i
i
i
-T
I
I
I
-1
I
I
I
I
-T
I
I
I
I
•1
I
I
1
-T
1
I
I
I
-1
ROW
TOTAL
8
0.1
579
6.5
27.3
5350
58.6
1.6
35
0.4
109
1.2
I
•^J
o
COLUMN
113
2031
2021
153«t
65<»
1037
232
319
5
-------
TABLE A-22. PRIMARY FUEL BY GEOGRAPHIC REGIONS (Continued)
(See Page A-28 for state/region definition)
COUNT I
ROH PCT I
COL PCT I
not
TOT PCT I coded 3
PRIHFUEL 1
7. I
OTHER FJiLS I
I
I
-I —
8. I
WASTEHE4T I
I
I
-I--
9. I
WITH AUK . FIrUNG I
I
I
.-!-•
10 . I
LIGNITE I
I
I
-I —
12. I
NON-COM3US REMOV I
I
I
-!-•
COLUMN
TOTAL
13
3.5
6.8
0. 1
3
s!"
u. 0
0. J
0. 0
.,.0
J
0.0
C. J
U. J
0
0.3
u . 3
L. 0
113
1.3
N
.1
1
I
I
I
I
I
I
I
I
I
1
I
I
I
I
I
1
I
1
I
1
Eng.
1
i. a
1. 1
0. 1
i
1.2
3 . 2
0 . 0
3
0 . C
o. a
D . )
3
J. 0
u. 3
0 . 3
0
0. 3
o. :
0 . 0
I»o6
D. 2
M-At 1 .
.1
-T-
1
I
I
I
-1-
I
I
I
I
-T-
I
I
I
I
-1-
I
i
I
I
-I-
1
I
t
I
-1-
2
72
25.
NUMBER OF HISSING OBSERVATIONS =
(priniary fuel data missing from input card)
-------
A-72
RECENT SALES OF FIRETUBE BOILERS
Firetube boilers are available in the industrial size range in
sizes up to about 900 BMP (or 30,000 PPH). They are most common in sizes
below 500 BHP. ABMA records on sales of firetube boilers do not contain
as much detail as for watertube boilers regarding combinations of features.
However, in recent years, most firetube boilers in the industrial size
range have been of the packaged Scotch design. ABMA data on sales of
packaged Scotch boilers during the period 1965-1972 are summarized in
Tables A-23 and A-24.
Table A-23 shows recent sales of packaged Scotch firetube boilers
tabulated by capacity in boiler horsepower. Most of these sales are in
the commercial size range; only 14 percent fall in the industrial size
range. The most popular sizes in the commercial range are 100 and 150 BHP
and 600 BHP in the industrial range.
Table A-24 shows the sales of Scotch boilers by years, with the
percentage distribution by fuels. Over the period 1965 through 1972, 38
percent were oil fired, 32 percent gas fired, and 30 percent equipped for
dual-fuel or combination oil/gas firing. A gradual decrease in oil-fired
units during the period was accompanied by a shift to combination units,
except in the last few years oil-fired units gained as gas-fired units
were displaced by both oil and combination units.
-------
A-73
TABLE A-23. RECENT SALES OF PACKAGED SCOTCH FIRETUBE
BOILERS BY CAPACITY (1965-1972)
Capacity,
boiler horsepower
Commercial Range
<15
20
25
30
40
50
60
70
80
100
125
150
200
225
250
Industrial Range
300
350
400
500
600
>700
Total
Number of
Units
728
898
425
2,060
1,976
2,263
2,928
1,189
2,630
4,971
3,757
4,305
4,548
205
2,454
2,572
1,385
1,319
1,392
1,670
212
43,887
Percent
of Total
1.7
2.0
1.0
4.7
4.5
5.1
6.7
2.7
6.0
11.2
8.6
9.8
10.3
0.5
5.6
5.9
3.2
3.0
3.2
3.8
0.5
100.07.
-------
A-74
TABLE A- 24. SALES OF PACKAGED SCOTCH WATERTUBE BOILERS BY YEAR
AND FUEL - (1965-1972)
Distribution by Fuel,
Total Number . , percent
Year
'65
'66
'67
'68
'69
'70
'71
'72
of Boiler Units
6,520
6,611
5,515
5,292
6,580
4,732
4,422
4.215
Oil
43.0
42.8
38.7
35.9
35.2
32.7
34. 8
41.3
Gas
33.5
33.0
33.0
35.3
36.9
33.5
26.4
21.3
Combination
23.5
24.2
28.3
28.8
27.9
33.8
38.8
37.4
8-year
Total 43,887 Average 38.3 32.2 29.5
-------
A-75
Recent Boiler Sales in Terms of Total Capacity
Firetube Boilers. Table A-25 summarizes recent sales of pack-
aged Scotch boilers in the commercial-industrial range, both in number of
units and in total capacity (PPH). While the Scotch boilers in the indus-
trial size range represent only 14 percent of the total Scotch boiler units,
they account for 38 percent of the total capacity of Scotch boilers.
Watertube Boilers. Table A-26 summarizes recent sales of non-
utility watertube boilers by size range, showing the number of units and
the total installed capacity. Boilers of 250,000 PPH and below represent
about 98 percent of the total watertube boiler units, but they account
for only 85 percent of the total capacity.
Figure A-l shows graphically the accumulative distribution of
non-utility boilers (firetube and watertube boiler capacity added per
year) . This illustrates the contribution of the large numbers of smaller
units in making up the total installed capacity.
Inventory of Installed Capacity of
Current Boiler Population
To examine the total installed capacity of the current field
population of industrial boilers, the estimates by Walden for 1967 were
(10)
updated to 1972 using ABMA data for the period.
Table 27 summarizes the distribution of total installed capacity
by boiler type and size category, showing the Walden estimate for 1967
and the 1972 update. The total installed capacity of industrial boilers
9
was estimated to be 2.45 x 10 PPH for 1972.* Of this capacity, 90
percent is contributed by boilers of watertube construction and 10 percent
by those of firetube construction.
* It is interesting to note that the total installed capacity of boilers
used in industry is nearly as great as the capacity of boilers serving
electrical utilities. The total installed capacity of industrial boilers
in 1967 was estimated in the Walden study to be about 85 percent of the
utility capacity.
-------
A-76
TABLE A-25. SUMMARY OF SALES OF PACKAGED SCOTCH FIRETUBE BOILERS-
NUMBER OF UNITS AND TOTAL CAPACITY BY
SIZE CATEGORIES (1965-1972)
Boiler Size
Range, horsepower
Commercial Range
10-50 BHP
51-100 BHP
101-300 BHP
Industrial Ran^e
301-500 BHP
>501 BHP
Total
Number
Units
8,351
11,718
17,877
4,096
1.882
43,889
of Units
Percent
19.0
26.6
40.7
9.4
A. 3
100.0
Total
10° PPH
9.9
32.3
115.4
57.0
38.3
252.9
Capacity
Percent
3.9
12.8
45.6
22.5
15.2
100.0
TABLE A-26. SALES OF WATERTUBE BOILERS -- NUMBER OF UNITS AND
TOTAL INSTALLED CAPACITY (1965-October 1973)
(Not Including Boilers For)
Utility Electrical Generation)
Boiler Capacity Range
100,000 and less
100,001 to 250,000
250,001 to 500,000
over 500,000
Boiler Units T2tal Capacity,
Number Percent 10° PPH Percen
6,000 76.5 237.7 43.5
1,643 21.0 225.1 41.2
177 2.2 56.4 10.3
27 0.3 27.2 5.0
Total 7,820 100.0 546.4 100.0
-------
A-77
TABLE A-27.. INVENTORY ESTIMATE OF TOTAL INSTALLED CAPACITY
FOR INDUSTRIAL BOILERS
(Flretube and Watertube Boilers
Operating in the United States
at the End of 1972)
Total Installed Capacity,'
106 PPH
Boiler Type and
Size Range
1967
Inventory
(a)
1972
Update
(b)
Firetube
>10,000 PPH (>300 HP)
192
(c)
250v
Watertube
10,000-100,000 PPH '
100,001-250,000 PPH
250,001-500,000 PPH
Total
921
658
259
2,030
1,090
800
310
2,450
a. Walden estimate of capacity operating in 1967 (Reference 10).
b. Update through 1972, using Walden estimate of capacity for 1967,
plus ABMA sales data on non-utility watertube boilers and Scotch
firetwbe boilers.
c. Derived from Walden estimate for commercial-industrial boilers
by deducting watertube capacity.
d. Including firebox firetube boilers in this range as 5 percent of
the Scotch boiler capacity.
-------
Boiler Horsepower
100 200 300
600 900
Packaged Scotch
firetube boilers
>
00
5000
10,000 50,000 100,000
Rated Capacity of Individual Boilers, PPH
200,000
500,000 1,000,000
FIGURE A-l. TOTAL ANNUAL INSTALLED CAPACITY OF INDUSTRIAL BOILERS - DISTRIBUTION
BY BOILER SIZE FOR WATERTUBE AND PACKAGED SCOTCH FIRETUBE BOILERS
-------
A-79
APPLICABILITY OF COMBUSTION MODIFICATION
TO INDUSTRIAL BOILERS
The feasibility of applying combustion modification techniques
to industrial boilers varies with boiler design and particular circum-
stances of the installation. The effectiveness, practical difficulty, and
cost of the modification are also subject to much variation with condi-
tions. However, a general assessment was made of the practical feasibility
of applying various modification techniques to various boilers, without
considering the effectiveness of each. Other investigations have considered
effects of combustion modifications on emissions. "
Table A-28 provides an overview of the relative applicability
of the following combustion techniques to firetube and watertube boilers
in the industrial size range:
• Burner design changes
• Low-excess air firing
•. Steam or water injection
t
• Biased firing
,(for multiple-burner units)
• Staged combustion
(no ports)
• Flue-gas recirculation
Current studies will provide additional insight and experience as to the
applicability of these modifications to industrial boilers.
*****
Parts B and C of this report cover potential problems associated with
combustion modification:
Part B. Corrosion and Deposits
Part C. Flame Stability
-------
TABLE A-28.
APPLICABILITY OF COMBUSTION MODIFICATION TO
VARIOUS TYPES OF BOILERS
(Does not imply relative effectiveness for NO
reduction)
Combustion, .
Modification*'3''
FIRETUBE BOILERS
Packaged Scotch
Firebox
WATERTUBE BOILERS
Burner Low-Excess
Fuel Design Air Firing
gas/oil ••• •••
gas/oil ••• •••
stoker ' N/A N/A
gas/oil ••• •••
stoker N/A N/A
PC •• ••
Steam or Biased Staged
Water Firing Combustion
Injection (b) (c)
••• N/A ••
••• N/A ••
••• N/A •
••• N/A •
Flue-gas
Recirculation
••
"
**
oo
o
Notes: (a) Applicability of combustion modification
••• Modification is feasible for new boilers and for retrofit (consistent with other criteria)
•• Modification is feasible for new boilers and for retrofit, but with considerable
difficulty (re cutting boiler tubes or overall cost)
• Modification is feasible only for entirely new designs
(b) Only applicable for multiple burners.
(c) Staged combustion includes use of NO-ports downstream of rich burning zone.
-------
A-81
REFERENCES FOR PART A
(1) Office of Science and Technology, "Patterns of Energy Comsumption in
the United States", U. S. Government Printing Office, Stock Number
4106-0034 (January, 1972).
(2) "Lexicon of Steam Generating Equipment", American Boiler Manufacturers
Association, Third Edition (1974), Available from the American Boiler
Manufacturers Association.
(3) Guide to Good Practice for Federal Facility Oil-Burning Units, prepared
by the American Boiler Manufacturers Association for National Air
Pollution Control Administration, Contract CPA 22-69-133 (August 15,
1970).
(4) Shields, Carl D., "Boilers: Types, Characteristics, and Functions".
F. W. Dodge Corporation (1961) 559 pages.
(5) Steam, The Babcock & Wilcox Company (1972).
(6) Combustion Engineering, Edited by Glenn R. Fryling, M.E., Revised
Edition, Combustion Engineering, Inc., New York (1966).
(7) Smith, M. L., and Stinson, K. W., Fuels and Combustion, McGraw-Hill
Book Co., Inc. (1952) Chapter 7. Coal Burning Equipment.
(8) Barrett, R. E., Miller, S. E., and Locklin, D. W., "Field Investigation
of Emissions from Combustion Equipment for Space Heating", Report for
American Petroleum Institute and Environmental Protection Agency
EPA-R2-73-084a (API Publication 4180) (June, 1973).
(9) "Stationary Watertube Steam and Hot Water Generator Sales", prepared
by American Boiler Manufacturers Association (1973).
(10) Ehrenfield, J. R., e± al, "Systematic Study of Air Pollution from
Intermediate-Size Fossil-Fuel Combustion Equipment", report by
Walden Research Corporation to the Environmental Protection Adminis-
tration, Contract No. CPA 22-69-85 (July, 1971).
(11) "Industrial Steam Generation: Annual Plant Design Report", Power,
117 (11), S-20-24 (November, 1973).
(12) "Guide for Compiling a Comprehensive Emission Inventory", U. S. Environ-
mental Protection Agency, Applied Technology Division, Publication
Number APTD-1135 (June 1972).
(13) Foley, G. J., Rochelle, G. T., Schofield, W. R., and Smith, J. 0.,
"Control of SOX Emissions From Industrial Combustion", AIChE
Southwestern Conference on Energy and Environment (1973) .
-------
A-82
(14) Nie, N., Bent, D. H., and Hull, C. H., "SPSS: Statistical Package
for Social Scientists", McGraw-Hill (1970) (Library of Congress
No. 75-119826).
(15) Jain, L. K., _et al. "State of the Art for Controlling NOX Emissions
Part 1. Utility Boilers", Catalytic, Inc., to Environmental Protection
Agency, NTIS No. PB-213297 (September, 1972).
(16) Berkau, E. E., and Lachapelle, D. E., "Status of EPA's Combustion
Program for Control of Nitrogen Oxide Emissions from Stationary
Sources.- September, 1972", presented at Southeastern APCA Meeting,
Raleigh, North Carolina (September 19, 1972).
(17) Proceedings; EPA Coal Combustion Seminar, sponsored by the U. S.
Environmental Protection Agency, held June 19-20, 1973, at Research
Triangle Park, North Carolina.
(18) Siegmund, C. W., and Turner, D. W., "NOX Emissions from Industrial
Boilers: Potential Control Methods", Combustion, 24-30 (October, 1973).
(19) Brashears, D. F., "Industrial Boiler Design for Nitric Oxide Emissions
Control", presented to Western Gas Processors and Oil Refiners
.Association, Bellinghara, Washington (March 8, 1973).
-------
PART B
FIRESIDE CORROSION AND DEPOSITS
AS AFFECTED BY COMBUSTION MODIFICATIONS
by
H. H. Krause and W. T. Reid
Battelle-Columbus Laboratories
March, 1974
-------
B-ii
PART B
FIRESIDE CORROSION AND DEPOSITS
AS AFFECTED BY COMBUSTION MODIFICATIONS
TABLE OF CONTENTS
TASK OBJECTIVES B-l
EFFECTS OF LOW-EXCESS AIR -1
Reduction of SO Concentration -2
Reduction of Vanadium Corrosion -3
Problems in Burning Pulverized
Coal with Low-Excess Air -4
EFFECTS OF TWO-STAGE COMBUSTION -7
Sulfide Corrosion -7
Effects of Carbon Monoxide -9
EFFECTS OF FLUE-GAS RECIRCULATION -10
METHODS OF MINIMIZING CORROSION -11
Air Management -12
Corrosion-Resistant Alloys -12
RESEARCH NEEDS -16
TVA Program -16
Low-Excess Air in Pulverized-Coal Firing -17
Corrosion Mechanisms -17
Corrosion Probe Design -18
Chrome-ore Packing „ -19
References -20
TABLE
TABLE B-l. COMPARATIVE RESISTANCE OF VARIOUS ALLOYS
COATED AND UNCOATED, TO SULFUR ATTACK ... o .... B-15
-------
PARTS
FIRESIDE CORROSION AND DEPOSITS
AS AFFECTED BY COMBUSTION MODIFICATIONS
by
H. H. Krause and W. T. Reid*
BATTELLE
Columbus Laboratories
In the history of boiler furnace operation, increased corrosion
and deposit problems have been associated with changes in fuels, fuel-
firing techniques, surface temperatures, and other combustion variables.
The current emphasis on environmental quality has brought about the need
for generating power and steam with less emission of air pollutants.
Combustion modification offers a solution to at least part of the problem,
but the changes in furnace conditions resulting from modifications such
as low-excess air or two-stage firing have a potential for introducing
new corrosion.and deposit problems.
TASK OBJECTIVES
The specific aims of this task are to:
(1) Assess the corrosion and deposit problems that
are likely to result from combustion modification.
(2) Determine whether or not solutions to the potential
problems are known.
(3) Recommend specific research directed toward pro-
viding solutions where none are known.
EFFECTS OF LOW-EXCESS AIR
From the viewpoint of air-pollution control, operation of boilers
with low-excess air is designed to reduce the formation of nitrogen oxides,
* W. T. Reid is a retired staff member of Battelle Columbus Laboratories ar,H
is currently serving as a consultant.
-------
B-2
but it will have other effects on the chemistry of the combustion system
as well. Reduction of the amount of combustion air can affect substantial
lowering of the S0_ concentration in the boiler, and it will also minimize
the conversion of the vanadium in residual oil to low-melting-corrosive
compounds. However, present technology has limited the use of low-excess
air to oil-burning systems.,
Reduction of SO- Concentration
In terms of corrosion by SCL and the various compounds formed
from it, the effects of operating boiler furnaces with low-excess air
are beneficial. Experience with oil-fired systems, where low-excess-
air operation is most practical at the present time, has demonstrated
that this mode of operation minimizes auperheater deposits, essentially
prevents high-temperature-metal wastage, stops air-preheater corrosion,
and eliminates emission of acid smuts. This subject has been thoroughly
discussed by W, T0 Reid in his book on Corrosion and Deposits. Suc-
cessful operation with low-excess air requires that the oxygen in the
flue gas be maintained less than about 0.2 percent. This requires pre-
cise control of the fuel-air ratio in all parts of the combustion system
to prevent fuel-rich zones with subsequent thermal cracking of hydrocar-
bons and the emission of smoke. Consequently low-excess-air operation
has in the past been limited to oil-fired systems, because the technology
for burning pulverized coal with such little oxygen has not yet been
developed. Normal operation with 12 to 20 percent excess air results in
the formation of 25 to 30 ppm SO., in the flame with fuels containing 2-3
percent sulfur. The excess air must be less than 2 percent to decrease
the SO- by about half. Further lowering of the excess air results in a
rapid drop of the S0_ level, and at about 0.1 percent oxygen in the flue
gas the SO- concentration will be reduced essentially to zero.
A typical example of the reduction in corrosion that can be
obtained by low-excess-air-operation was reported by Attig and Sedor for
-------
B-3
(2)
a furnace operating with residual oil containing 4 percent sulfur.
Corrosion rates for carbon steel were reduced from about 90 mils per
year to about 8 mils per year in a 200 F temperature zone, by decreas-
ing the excess air from 9.5 percent to 1.5 percent. In the 350 F zone
the corrosion rate was well under 5 mils per year. An even more sig-
nificant reduction in corrosion was obtained by Glaubitz, who operated
(3 4)
oil-fired boilers at 0.3 percent excess air. ' By reducing the
excess air to this level from the previous level of 7 percent, a 16-
fold decrease in corrosion was achieved when burning an oil containing
3.3 percent sulfur. According to a report of Russian experience with
oil containing 205 to 3.0 percent sulfur, corrosion rates were reduced
at least 4-fold by decreasing the excess air from the usual 10 percent
to 2 to 3 percent. Boiler furnace operation with low-excess air has
been pioneered in Germany and England, but this technique has not been
widely practiced in the United States. However, new boiler installa-
tions are incorporating this capability.
Corrosion of wall tubes in boilers, particularly those fired
with coal, has been found to be caused by low-melting pyrosulfates and
trisulfates. * ' These compounds all depend on the presence of SO-
for their formation, and the corrosion mechanisms involving these com-
pounds require the availability of high concentrations of S0~» In the
superheaters, the tube temperature is too high for pyrosulfates to exist,
but corrosion by the trisulfates has been serious enough to limit steam
temperatures to the range 1000-1050 F. Consequently, minimizing the
amount of SO- in the flue gases by using low-excess-air combustion will
reduce the corrosion from these complex sulfates, on both wall tubes and
superheaters„
Reduction of Vanadium Corrosion
Another beneficial effect of low-excess-air operation is the
reduction of high-temperature corrosion which results from the vanadium
-------
B-4
content of residual oils. When the vanadium is oxidized to the penta-
valent state, low-melting compounds such as vanadium pentoxide (^Oc) an(i
various sodium vanadates are formed. Operation with low-excess air,
however, limits the oxidation of vanadium to compounds such as ^O- or
V 0. which are high-melting compounds and do not cause corrosion as do
the easily fusible salts.
This effect has been demonstrated by Chaikivsky and Siegmund,
who burned residual oil containing 350 ppm vanadium and 2.57 percent
sulfur in a laboratory combustor. With 15 percent excess air almost
all of the vanadium appeared in the tube deposits as the very corrosive
sodium vanadyl vanadatec At 5 percent excess air, significant amounts
of the lower-vanadium oxides were formed, and below 4 percent excess air
there was an abrupt decrease in both corrosion and deposits, as the
lower oxides predominated.
From these considerations it must be concluded that as long as
strongly reducing conditions are not created in localized areas, opera-
tion of boiler furnaces with low-excess air will reduce corrosion,, The
benefits of low-excess air will be reflected in longer life of all of
the elements of the boiler, from wall tubes to superheater elements
and convection surfaces, through the low-temperature end, including
economizer and sir preheater. However, as mentioned previously, at the
present time low-excess-air operation has only been adapted to oil-firing
systems.
Problems in Burning Pulverized
Coal With Low-Excess Air
Central-station boiler plants burning pulverized coal usually
operate with excess air ranging between about 12 and 20 percent. At
higher levels, excessive sensible heat is lost in the stack gas, and at
-------
B-5
lower levels too much unburned carbon leaves the furnace with the flyash0
This unburned carbon represents a serious heat loss and it can be a
grave source of trouble if it becomes ignited and burns in ash hoppers
later in the boiler circuit.
The reactivity of the coal probably plays a part in establish-
ing the amount of unburned carbon leaving the furnace, but the main
problem undoubtedly is the combustion mode of particles of pulverized
coal, where devolatilization occurs first with immediate burning of the
volatile matter followed by slower combustion of the remaining particle
of "char". Because that residual-carbonaceous particle is relatively
inert compared with a droplet of fuel oil, more excess air is required
to burn it in the few milliseconds available than suffices for complete
combustion of liquid droplets. Hence, the same few precautions taken
when burning fuel oil with low-excess air—of insuring fine droplet size
and carefully proportioning fuel and air for stoichiometric combustion—
will not be adequate when burning solid particles of coal.
Basically, then, to simulate the conditions leading to success-
ful burning of fuel oil with low-excess air, pulverized coal firstly must
be finely ground to produce particles with the highest possible surface
area to compensate for its lesser reactivity than fuel oil. The conven-
tional grind of 85 percent of the coal through a 200-mesh sieve—or 74
micrometers--must be changed to provide finer particles, but the actual
particle size necessary is in doubt.
Secondly, proportioning of air and coal at each burner will
need more consideration than is given at present. Great care will be
necessary to insure precisely the coal and air distribution to each flame
element to be certain that complete burning will take place,, Any fuel-
rich flame zones will lead to solid-carbonaceous particles probably too
inert to react with carbon dioxide and water vapor as the particles move
out of the flame zone into cooler parts of the boiler furnace.
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B-6
Thirdly, residence time at high temperature must be long. It appears
possible that corner firing leading to a flame vortex may result in longer
residence time in a high-temperature zone than would be expected in a wall-
fired furnace. In addition, the intermixing at different burner streams in
corner firing may minimize the importance of proportioning fuel and air to
each burner. More data are needed here to substantiate this theoretically
attractive possibility.
Fourthly, burners must be designed for gradual mixing of coal and
air at moderate temperatures to minimize conversion of fuel nitrogen to NO ,
X
although this increases the difficulty of carbon burnout later in the flame.
In the later stages of combustion it appears necessary to maintain high
temperature and assure adequate turbulence for carbon burnout. A better
understanding of these techniques is being gained in research on fundamentals
of pulverized coal combustion, such as that at IJmuiden
Fifthly, basic differences in the nature of devolatilized char from
different coals need to be evaluated. Obvious problems in burning pulverized
anthracite have been recognized for many years, but less clear are the factors
involved between bituminous coals, subbituminous coals, and lignite. Recent
experience has shown that burning low-rank coals from Montana in cyclone
furnaces intended to burn bituminous coal from southern Illinois has led to
serious problems with unburned carbon leaving the furnace. It is not clear
presently whether this is mainly the result of differences in reactivity or
of other factors inherent in cyclone furnaces. It is evident, though, that
coal reactivity depends upon other factors than volatile matter content as
determined by a proximate analysis.
These arguments apply mainly to the burning of pulverized coal.
They apply with almost equal importance to spreader stokers or to fast-
fluidized beds where burning in suspension is significant. They do not
apply to fixed-fuel beds, such as with chain-grate or underfeed stokers.
In those cases, combustion occurs in two distinct stages either within
the fuel bed for thin beds, or within the bed and above it for thick
-------
B-7
fuel beds which act like gas producers. Usual practice in stoker-fired
installations is to supply an excess of overfire air, frequently through
high-velocity jets, to burn the carbon monoxide and hydrogen plus any
volatile matter leaving the fuel bed. A highly sophisticated secondary
air system with overfire jets can minimize the amount of excess air
needed, but probably never to the level achievable with the best pulver-
ized-coal systems.
EFFECTS OF TWO-STAGE COMBUSTION
The use of two-stage combustion to reduce air pollution requires
that the first stage be a fuel-rich zone. Under these conditions the com-
bustion is not complete and a reducing atmosphere predominates in this
region. As a result, the oxidation of the sulfur and the carbon will not
be complete, and corrosion might occur quite differently than in an oxidizing
atmosphere.
Sulfide Corrosion
In an oxygen-deficient atmosphere the sulfur from the decomposi-
tion of pyrites, FeS , will not all be oxidized to sulfur dioxide. The
first step in the combustion of FeS is a dissociation in which an atom
of sulfur is released. An experimental study of the reaction under con-
ditions that would exist in a furnace showed that this sulfur was released
(12)
in 0.5 sec at a temperature of 2000 F. ' The pressure of the sulfur
vapor thus formed reaches one atmosphere at 1435 F. The experiments dem-
onstrated that with the short residence time in the flame, sulfur and
metal sulfides could be deposited on furnace-wall tubes.
The presence of FeS in the deposits found on badly corroded boiler
tubes has been reported by W. T. Reid and his associates. In 7 of the
furnaces that they examined in the early 1940"s, sulfide deposits were
found in some areas. Up to 5 percent carbon also was noted in some
-------
B-8
of these deposits, indicating that the normal oxidation process had not
occurred. Later Corey, et al, demonstrated by laboratory experiments
that iron is corroded rapidly in the presence of FeS0 in the temperature
(9) L
range 700-1000 F. Under these conditions corrosion by FeS was negli-
gible, indicating that the sulfur released in the decomposition of FeS
was responsible for the attack. Considering these experiments in the
light of the conditions that prevailed in the furnace, it was concluded
that poor distribution of the coal stream leaving the burners, coupled
with coarse pulverization, resulted in deposition of incompletely burned
coal on the furnace walls. The FeS« carried with this coal oxidized
slowly, evolving sulfur, which then could react with the tube metal to
give the deposit of FeS, some of which subsequently oxidized to Fe-O .
Both of these compounds were identified in the deposit by X-ray diffrac-
tion analysis.
Additional evidence for this mechanism was obtained when cor-
rective measures were applied in two of the furnaces having severe
corrosion in areas with FeS deposits. Both the rapid corrosion and the
FeS were eliminated when mill adjustments were made and coal-distributor
pipes were repaired, thus insuring that the carbon and the sulfur would
be completely oxidized before reaching the wall tubes.
No data are available on the extent or duration of reducing
conditions required to convert the alkali-iron trisulfates into sulfides.
It is probable that the ratio of H to HO and of CO to CO- must be
fairly high for that conversion to occur. Probably more important here
is that the trisulfates will not form except in the presence of SO-,
some 250 ppm being necessary to 1000 F to produce these compounds. Since,
as has been shown conclusively in studies of combustion with low-excess
air, S0_ is not formed when the oxygen level in the flue gas is less
than about 0.2 percent, it is highly probable that there will be no tri-
sulfates formed under such conditions. However, the oxygen-deficient
-------
B-9
conditions may lead to deposition of sulfur or pyrites, with the con-
sequent corrosion of the boiler tubes,
Sulfide corrosion is particularly serious when the tube metal
being attacked contains nickel and the corrosion propagates along the
grain boundaries. The resulting nickel sulfides are low-melting com-
pounds, and being liquids of more than one valence state can freely
transport sulfur from the mouth of a grain boundary deeper into the
grain boundary. In the case of chromium, the sulfides which form do
not melt as readily and therefore do not migrate as freely. Accord-
ingly, chromium-base alloys are more resistant to sulfide corrosion
than are nickel-base alloys,, ' Unfortunately, the chromium-base
alloys have inferior high-temperature strength.
Effects of Carbon Monoxide
Incomplete combustion of carbon in a fuel-rich zone will result
in an increase in CO concentration. There is no direct action of CO on
boiler steels to cause metal wastage when the concentration is low.
However, there can be an indirect effect of the CO in reducing the
thickness of the oxide scale, thereby exposing fresh tube metal to
oxidative attack when conditions change from reducing to oxidizing,
Rasch has shown that the reduction sequence Fe_0, -• Fe~0, -* FeO can occur
when the ratio of CO to C0_ is 1 to 1 and will take place at lower temper-
(15)
atures as the amount of CO predominates over C0», Furthermore, the
CO can reduce FeO to Fe via an intermediate of Fe_C, thus removing all
of the protective oxide layer from the tube., Subsequent oxidation of
the unprotected metal will then occur if alternating oxidizing and re-
ducing conditions are present.
Excessive loss of tube metal in large steam-generating incin-
erators in Europe has been attributed to this action. The poor
combustion conditions in fuel beds burning raw garbage results in flames
-------
B-10
reaching wall tubes one moment and air the next, so that the atmosphere
over the wall tubes is alternately highly reducing and highly oxidizing.
Corrosion at the Stuttgart incinerator in Germany was attri-
buted to these causes. The CO concentration was about 082 percent,
with unburned carbon in the form of glowing particles impinging on the
wall tubes. Although the wall tubes were only at a temperature of
570 F, their failure frequency was 10 times as great as that of the con-
vection tubes. Some of the superheater tubes failed in just one year,
and others after 4 years. This catastrophic corrosion was alleviated
by redesigning the combustion chamber and by putting studs on the tubes
in vulnerable areas and packing the studded area with silicon carbide.
At the Munich incinerator, wall tubes subject to a reducing
atmosphere decreased in thickness from 3.2 mm to 1.8 mm in 3500 hours.
Flame impingement and alternate oxidizing and reducing atmospheres were
blamed for corrosion that required replacement of 100 boiler tubes. In
this case also, the silicon-carbide packing was used as a remedy. In
addition the superheater tubes were shielded with Sicromal alloy to re-
duce corrosion. No definite proof exists as yet that tube wastage is always
accelerated by such alternating conditions, but this is a point worthy
of consideration since two-stage combustion very likely will lead to a
zone intermediate between the two combustion zones where the furnace
atmosphere may shift rapidly and unpredictably between reducing and
oxidizing conditions.
EFFECTS OF FLUE-GAS RECIRCULATION
Recirculation of flue gas probably will tend to minimize the
formation of the alkali-iron trisulfates because not enough oxygen may
then be present to form the needed SO . If enough CO , water vapor, and
N are brought back into the combustion zone to lower furnace temperatures
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B-ll
appreciably, the SO- levels in the flue gas will drop, and not enough
oxygen will be available beneath slag deposits to convert S02 to S03 in
the .required amounts. Similarly, not enough SO- will be present to form
the alkali pyrosulfates even at low-metal temperatures.
The main problem with flue-gas recirculation is that it may
affect combustion conditions unfavorably so that unburned particles of
pulverized coal and unoxidized particles of pyrites might reach the wall
tubes. As shown earlier, this could cause serious wastage by the sulfide
routeo
A major effort must be made, then, in planning tests of flue-
gas recirculation, to assure that no unburned particles of coal and
pyrites impinge on wall tubes. Care must be taken in designing burners
to assure a blanket of secondary air along the walls and to prevent any
flame impingement,, Good pulverization must be obtained, and coal
splitters between the pulverizers and the burners must be carefully laid
out to assure minimum segregation of coarse coal particles to any one
burner. If such preventive steps are taken, flue-gas recirculation should
have a minimum impact on corrosion and deposits on wall tubes.
METHODS OF MINIMIZING CORROSION
Two approaches are available in current technology for keeping
corrosion to a minimum when combustion modification is used to reduce
air pollution. One technique is to improve air-management practices so
that the vulnerable areas are not subject to reducing conditions. The
other approach is to utilize alloys that are more resistant to attack
by the corrosive agents.
-------
B-12
Air Management
In the 1940's, when serious wall-tube, wastage was first ob-
served, the troubles were blamed on flame impingement; the corrosion
patterns closely matched the flame patterns on the wall. As a correc-
tional measure, the operators admitted a part of the secondary air to
the casing around the lower section of the furnace so that air infil-
trated between the closely spaced tubes to dilute the products of
combustion. In other cases, burners were modified to direct a blanket
of secondary air along the walls and to minimize flame impingement.
These practical solutions essentially eliminated wall-tube wastage by
lowering the S03 level beneath deposits to the point where the trisul-
fates could not form.
Air management will be critical in two-stage combustion,, The
problems of burning pulverized coal with less than the stoichiometric
amount of air in the first stage will yield devolatilized "char" to be
burned in the second stage, a job that will call for the utmost in air
management. And since the problems of sulfide corrosion will be serious
if unburned coal particles and unoxidized pyrites reach the furnace walls,
great care must be taken to be sure that burner direction, secondary air
dampers, and tertiary-air admittance be closely controlled to keep par-
ticles away from furnace walls until the second-stage combustion is
completed. This is almost certain to call for new concepts in burner
design and in furnace geometry.
Industrial boilers, having a relatively high surface-volume
ratio, will probably pose greater problems in air management than will
large utility-boiler furnaces.
Corrosion-Resistant Alloys
Past experience both with industrial and with utility-boiler
furnaces has shown that the selection of alloys for wall tubes and for
-------
B-13
superheater and reheater elements is based on the oxidation resistance of
the alloy and the ability of the alloy to withstand high stress levels.
Increased resistance to corrosion beyond normal oxidation has not been
justifiable economically. Hence the design philosophy has been to choose
the lowest cost alloy that will survive under high stress for 20 to 30
years in an oxidizing environment such as exists in a boiler furnace.
For wall tubes this has generally meant a low-carbon steel, and for super-
heaters and reheaters a low-alloy steel typically containing a small
amount of chromium and a little molybdenum,, More exotic alloys are
either too costly or have undesirable physical characteristics. With
the usual levels of excess air in boiler furnaces burning pulverized
coal, variations in flue-gas composition have an insignificant effect on
the rate of oxidation compared with air»
Decreasing excess air nearly to stoichiometric levels, as is
possible with oil firing, has had no essential effect on oxidation since
carbon dioxide, water vapor, and nominal amounts of sulfur dioxide are
about equivalent to air in forming scale on low-carbon steels at usual
working temperatures. Slightly reducing conditions where small amounts
of carbon monoxide are present also have little effect on the rate of
(18)
oxidation, at least when the carbon monoxide level is below 0.1 percent.
At higher levels, carbon monoxide can be expected to be troublesome.
But since boiler furnaces have not been operated under reducing conditions
because this would result in a costly loss of fuel, no data are available
on metal wastage problems with boiler furnaces at appreciable levels of
carbon monoxide.
High-alloy steels provide greater corrosion resistance than
either the carbon or low-alloy steels commonly used. However, as pointed
out previously, steels containing substantial amounts of nickel have been
subject to sulfide corrosion, which is of particular concern here.
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B-14
Improvement in the high-temperature corrosion resistance of
(19)
nickel-base alloys has been reported by Bergman, et al, as a result
of addition of rare earth elements to the alloys. Cerium additions in
particular were said to provide remarkable benefits when added to nickel-
base Udimet 500 alloy in quantities up to 0.5 percent. A possible ex-
planation for this effect is the high melting points of rare earth
sulfides and their very high free energies of formation, which would
render them good sulfide getters.
Llewelyn has demonstrated that aluminum coatings confer im-
proved sulfide corrosion resistance to nickel-base alloys. Table 1
reproduced from Llewelyn's paper compares corrosion resistance of several
alloys with and without aluminum coatings. The table also compares the
effects of reducing and nonreducing environments on the corrosion
resistance. The data summarized in the table denote the temperature at
which attack was first observed on the specimens. Sulfide corrosion be-
gan in some of the alloys at temperatures as low as 770 C, while others
resisted corrosion up to 980 C. The pack-aluminizing treatment which
consisted of hot-soaking a specimen with a mixture of metallic aluminum,
aluminum oxide, and ammonium bromide provided a significant increase in
the threshold temperature at which corrosive attack began,, Increases as
high as 170 degrees C were noted for some of the alloys. As recorded in
the table, if the material was in contact with carbon its corrosion re-
sistance was somewhat reduced. The aluminizing process also gave
significant increases in corrosion resistance in this case as well.
Studies made at the International Nickel Company Laboratories
showed that metals of the type discussed by Bergman and Llewelyn, 60
chromium-40 nickel and 50 chromium-50 nickel, may cost three to four
times as much as austenitic stainless steels presently used in high-
temperature applications but their resistance to corrosion is 4 to 15
times as great.
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B-L5
TABLE B-l. COMPARATIVE RESISTANCE OF VARIOUS ALLOYS
COATED AND UNCOATED, TO SULFUR ATTACK
6 HOUR CYCLE, INTERMITTENT" SOj AND AIR AT 45 MINUTE INTERVALS
MATERIAL IN CAS STREAM
M 71 VC
N ios N 100 EPK34 (IN. 100 )
G 64 (HT DENUDED LAYER REMOVED)
INCO 711
G 64
MAP M 3OO
MAR M 10}
N SO N IIS
C64 (PA.NIJ AI COATING) joo HOURS soo'c
MAR M 333 MAR M 5O9
M 21 VC PA
WIJ2 G64 PA X 40
INCO '13 PA N IDS PA X4OPA ERK24 (IN IOO ) PA
Wl S3 PA
N «O PA
MAR M 30} PA MAR M JOO PA
MAR M 2OO PA
THRESHOLD
TEMP
•c
77O
7 IO
7QO
90O
OIO
8 jo
630.
84O
eso
06O
870
09O
eeo
90O
510
eso
«30
ltd
9 SO
96O
97O
ieo
1 10
IOOO
IOIO
IO7O
1010
IO4O
IO5O
IO6O
MATERIAL IM CONTACT WITH CARBON
M 31 VC
N IOS N IOO EPK X (iN IOO )
INCO 71} Gt.4
MAR M 30O
MAR M 3O2
N IIS
G 64 (PA Ni,Ai COATING) soo HOURS «oo"c
N 9O X 4O
MAR M SO9 MAR M 33}
Wl 5? M Jl VC PA
O 64 PA
MAR M 323 PA
X 4O PA Wl 53 PA
MAR M 3O3 PA
N 105 PA EPK 24 PA N «O PA
MAR M SO9 PA
MAR M 3OO PA
PA . PACK ALUMINISCO 6V BRISTOL SIDOCLEY PROCESS
These recent developments in corrosion-resistant alloys and
surface treatments to increase resistance to sulfide attack indicate
that materials are available to meet the problems that would be antici-
pated from combustion modification. However, these are very expensive
materials to use on a large scale, and research is needed to provide
solutions that would be less costly. Further since field assembly of
boilers calls for considerable welding, any treatment such as aluminizinp
would have to be applicable in the field after all welding was completed.
Shop assembled panels of wall tube would minimize this problem during
construction, but maintenance of wall tubes which occasionally calls for
replacing individual wall tubes will call for field welding. Hence any
protective coating, or indeed any superalloy, would have to be such as
to permit servicing in the field.
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B-16
RESEARCH NEEDS
The corrosion and deposits problems that may arise from combus-
tion modification cannot be solved without some additional research. The
application of air-management principles to protect vulnerable areas in
the boiler will require individual attention to each situation in exist-
ing boilers. In addition, the design of future boilers should take into
account the need for application of these principles.
Research to determine the seriousness of corrosion that can re-
sult from staged combustion is particularly important. Some of this work
can be done in existing furnaces by the use of corrosion probes. However,
laboratory-scale research also is needed to determine whether or not the
mechanisms that have been hypothesized for such cases as alternate oxida-
tion and reduction are valid. Applied research to make possible wide-
spread use of low-excess air in pulverized-coal firing is needed especially.
TVA Program
The Tennessee Valley Authority presently is planning large-scale
tests of staged combustion in a 125-MW-pulverized-coal unit. To anticipate
any possible problems with wall tubes, TVA plans to use a corrosion probe
that can be removed periodically to check on metal wastage or the accumulation
of potentially damaging deposits in the furnace. ' To insure that the
corrosion probe specimens will have the same radiative and convective heat
transfer, gas velocity and direction, and impingement of solid particles
that will occur on furnace-wall tubes, TVA is planning to use a probe designed
to lie flush with furnace-wall tubes, thus nearly duplicating the conditions
on the original furnace wall.
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B-17
Low-Excess Air in Pulverized-Coal Firing
In order to make the benefits of low-excess air available to
pulverized-coal firing, a large-scale research program would be required.
An adequate program should investigate the following aspects of the problem
especially with respect to low-excess-air conditions:
1. The optimum coal-particle size to provide the necessary
surface area for complete combustion
2. Means of proportioning of coal and air at the burner to
insure good combustion
3. The possible advantage of corner-firing in providing
optimum combustion
4. The design of burners to provide optimum turbulence and rate
of mixing in the flame zone
5. The nature of the devolatized char formed in burning different
ranks of coal under low-excess-air conditions.
Corrosion Mechanisms
An investigation of the mechanism by which a reducing atmosphere
may cause corrosion under boiler furnace conditions is warranted,, The
questions raised by the European steam-generating incinerator experience
have not been answered definitively, although logical mechanisms have
been deduced,, The effects of alternate oxidizing and reducing conditions
with and without flame impingement need to be studied, to ascertain
whether chemical attack is involved, or only physical affects such as
spelling of deposits to expose fresh surfaces,,
Some further study of the extent of sulfide attack under fuel-
rich conditions also should be made. The previous data were obtained
mostly under oxidizing conditions where poor fuel handling was responsible
for the unburned fuel, rather than a truly oxygen-deficient atmosphere.
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B-18
Corrosion Probe Design
A major problem in the past in controlling corrosion in large
boiler furnaces has been the operator's inability to determine loss of
metal except from measurements made during major outages. A further
difficulty arises in that samples taken from corrosion areas are com-
posites of chemical reactions that have taken place over long periods
under varying operating conditions. It is not possible, for instance,
in examining badly corroded tubes to attribute the wastage to a single
short-lived episode or to continuous low-rate corrosion over a long time,,
Also, momentary overheating occurring at any time between inspections at
outages can radically modify the nature of the overlying deposit, there-
by negating its usefulness in explaining the mechanism of corrosion. In
short, relying on infrequent inspections of wastage areas is an unsatis-
factory way of understanding and explaining corrosion and deposition
processes.
Probes have been devised in the past for measuring rates of
corrosion and of accumulation of deposits, but serious shortcomings have
greatly limited their usefulness. Two major requirements must be met:
(1) temperature, rate of heat transfer, and gas velocity and composition
over the probe must be identical with conditions on furnace elements; and
(2) the probe must be readily removable from the furnace for inspection
and as easily replaced for further exposure. No probe used as yet in
boiler furnaces has met all these requirements, which can be met only by
designing a probe that lies flush with wall tubes or parallel to superheater
elements without disturbing existing gas-flow patterns. A probe of this
type, proposed by the Battelle Columbus Laboratories, is being considered
by TVA for use in their program.
Considerable importance is attached to designing a probe since
only with such a device can bad conditions within a boiler furnace be
detected before they have caused serious damage to the installation. Also,
such a probe will allow evaluation of protective measures without the long
delays inherent in field inspection of furnace-wall tubes and superheaters.
-------
B-19
Chrome-ore Packing
An investigation should be made of the possibility of utilizing
a chrome-ore packing as a method of combating sulfide corrosion under re-
ducing conditions. This approach would entail studding of the boiler
tubes and packing chrome ore in the studded area.
This method of preventing corrosion was attempted years ago in
oxidizing furnace atmospheres, but was not successful. The chrome-ore
oxidized and crumbled away in about a six-month period. However, a
recent reference to experience in chemical recovery furnaces used in the
Kraft paper industry indicates that under reducing conditions the chrome-
ore packing does not deteriorate and protects against sulfide corrosion.
In these furnaces the black liquor from the Kraft process is burned and
the inorganic chemicals are recovered for recycling in the process. The
bottom of the furnace is subjected to a molten mixture of Na2C03 and
Na S in a reducing atmosphere. In this environment the chrome-ore pack-
ing is reported to persist and protect against corrosion. The possibility
of using this technique to counteract sulfide corrosion that might occur
with two-stage combustion warrants investigation.
-------
B-20
REFERENCES FOR PART B
(1) Reid, William T., External Corrosion and Deposits, Boilers and Gas
Turbines. American Elsevier Publishing Co., New York, 1971, pp 178-
188.
(2) Attig, R. C. and Sedor, P., "A Pilot-Plant Investigation of Factors
Affecting Low-Temperature Corrosion in Oil-Fired Boilers", ASME
Trans., J. Engineering for Power, 87., 197-202 (April 1965).
(3) Glaubitz, F., "The Most Economic and Safest Method for the Prevention
of High and Low Temperature Corrosion in Oil-Fired Boilers", Energie,
16., 507-511 (1964).
(4) Glaubitz, F., "The Prevention of Corrosion in Oil-Fired Boilers by
Combustion of Oil with Extremely Low Excess Air", Werkstoffe und
Korrosion, 1£(12): 1033-1039 (1965).
(5) Petrosyan, R. A., and Sergeeva, N. D., "A Study of Low-Temperature
Corrosion When Burning High Sulphur Content Oil", Teploenerogetika,
U, (2) 55-59 (1965).
(6) Childs, G. D., "Countermeasures Against Flue Gas Corrosion and
Deposits", Technical Association of the Pulp and Paper Industry,
50, 122A-125A (June 1967).
(7) Reid, W. T., Corey, R. C., and Cross, B. J., "External Corrosion of
Furnace-Wall Tubes-I. History and Occurrence". Transactions of
ASME, 6_7(4): 279-288 (1945).
(8) Corey, R. C., Cross, B. J., and Reid, W0 T., "External Corrosion of
Furnace-Wall Tubes-II. Significance of Sulphate Deposits and Sulfur
Trioxide in Corrosion Mechanism". Transactions of ASME, 67(4);
289-302 (1945).
(9) Corey, R. C., Grabowski, H0 A., and Cross, B0 J., "External Corrosion
of Furnace-Wall Tubes-Ill. Further Data on Sulphate Deposits and the
Significance of Iron Sulphide Deposits". Transactions of ASME, 71(8):
951-963 (1949).
(10) Chaikivsky, M. and Siegmund, C. W., "Low-Excess-Air Combustion of
Heavy Fuel-High Temperature Deposits and Corrosion". Transactions
of ASME, Jr. Engineering Power, 87., Series A, 379 (1965).
(11) Heap, M. P., Lowes, T. M., Walmsley, R. and Bartelds, H0, "Burner
Design Principles for Minimum NO Emissions". International Flame
Research Foundation, IJmuiden, Holland. Presented at Coal Combustion
Seminar, Research Triangle Park, N. Carolina, June, 1973.
-------
B-21
(12) Halstead, W0 D0 and Raask, Ec, "The Behavior of Sulphur and Chlorine
Compounds in Pulverized-Coal-Fired Boilers", J0 Institute of Fuel,
42., 344-349 (Sept» 1969),
(13) Narita, T and Nishida, K., "On the High-Temperature Corrosion of Fe-Cr
Alloys in Sulfur Vapor", Oxidation of Metals, £(3): 157-180 (1973).
(14) Narita, T. and Nishida, K0, "High Temperature Corrosion of Low Cr-Fe
Alloys in Sulfur Vapor", Oxidation of Metals, 6.(3): 181-196 (1973).
(15) Rasch, R., "Thermodynamics of High Temperature Corrosion", Inter-
national Symposium on Corrosion in Refuse Incineration Plants ,
Dusseldorf, West Germany, April 1970.
(16) Nowak, F., "Corrosion Phenomena in Refuse-Firing Boilers and Pre-
ventive Measures", International Symposium on Corrosion in Refuse
Incineration Plants, Dusseldorf, West Germany, April 1970.
(17) Maikranz, F., "Corrosion in Three Different Firing Installations",
International Symposium on Corrosion in Refuse Incineration Plants,
Dusseldorf, West Germany, April 1970.
(18) Slunder, C. J., Hall, A. M., and Jackson, J. H., "Laboratory
Investigations of Superheater-Tubing Materials in Contact with
Synthetic Combustion Atmospheres at 1350 F", ASME, Paper 52-A-36,
1952.
(19) Bergman, P» A., Sims, C. L., and Beltran, A. N., "Development of
Hot-Corrosion-Resistant Alloys for Marine Gas Turbine Service",
Hot Corrosion Problems Associated with Gas Turbines, ASTM Special
Technical Publication No0 421, 1967, pp 38-59.
(20) Llewelyn, G0, "Protection of Nickel-Base Alloys Against Sulfur Corro-
sion by Pack Aluminizing", Hot-Corrosion Problems Associated with Gas
Turbines^ ASTM Special Technical Publication, No. 421, 1967, pp 3-20.
(21) International Nickel Company, Elevated Temperature Symposium,
National Association of Corrosion Engineers, Miami, Fla., April,
1966.
(22) Hollinden, G. A. and Ray, S. S., "Control of Nox Formation in Wall,
Coal-fired Utility Boilers: TVA-EPA Interagency Agreement", Pulverize.
Coal Combustion Seminar, Research Triangle Park, North Carolina,
June, 1973.
(23) Ylasaari, S., "Investigations on the Fireside Sulfide Corrosion in
Soda Recovery Units", International Symposium on Corrosion in Refuse
Incineration Plants, Dusseldorf, West Germany, April, 1970.
-------
PART C
FLAME STABILITY AS AFFECTED BY
COMBUSTION MODIFICATIONS
by
A. A. Putnam and M. A. Duffy
Battelle-Columbus Laboratories
March, 1974
-------
C-ii
PARTC
FLAME STABILITY AS AFFECTED BY
COMBUSTION MODIFICATIONS
TABLE OF CONTENTS
Page
INTRODUCTION AND OVERVIEW C-l
Significance of Basic Phenomena Relative
to Combustion Modification. . ; c"2
Suggested Future Work c"^
FLAME STABILITY c'5
General Description C-5
Laminar Flame Stability C-5
Stability of Turbulent Premix Flame C-8
Stability of Turbulent Diffusion Flame . C-8
Basic Stability Parameters C-9
Burning Velocity C-ll
Derivation of Basic Relation C-ll
Discussion of Data C-13
Chemically Controlled Reaction Rate Per Unit Volume .... C-20
Derivation of Basic Relations C-20
Discussion of Data C-21
Effect of Design Changes on Stability C-25
Recirculation C-25
Two-Stage Combustion C-26
COMBUSTION NOISE C-29
Basic Phenomena C-29
Combustion-Driven Oscillations C-30
Suppression of Combustion-Driven Oscillations .... C-35
Enclosure Effects C-35
-------
C-iii
Page
Combustion Roar C-36
General Observations , „ C-36
Theory of Combustion Roar . . „ . „ C-38
General Conclusion from Combustion Roar Theory .... C-39
Effect of Environment C-44
. Application of Combustion Roar Theory C-44
Suppression of Combustion Roar C-47
Unstable Combustion Noise C-47
Observations of Smith and Kilham C-49
Observations of Westberg C-50
Observations of Fricker C-50
Other Observations C-53
Combustion Amplification of Periodic Flow Phenomena .... C-53
External Noise Source C-54
Strouhal Related Phenomena C-55
Swirl-Burner Precession Noise C-56
REFERENCES FOR PART C ; c_67
LIST OF TABLES
TABLE C-l. EFFECT OF TWO-STAGE COMBUSTION C-28
TABLE C-2. SWIRL BURNER DIMENSIONS C-58
LIST OF FIGURES
FIGURE C-l. FLASH-BACK, EXTINCTION, AND BLOW-OFF CURVES
WITH AND WITHOUT 3000-v FIELD C-6
FIGURE C-2. EFFECT OF NATURE OF SURROUNDING ATMOSPHERE
ON BLOWOFF OF NATURAL GAS-AIR FLAMES; TUBE
DIAMETER, 0.577 cm C-7
FIGURE C-3.
BURNING VELOCITIES OF ETHANE, PROPYLENE,
PROPANE, n-BUTYLENE-1 AND n-BUTANE WITH AIR
.012
-------
C-iv
FIGURE C-4. SCHEMATICS OF FLOW AND TEMPERATURE IN VARIOUS
RECIRCULATION SITUATIONS . . . . ; C-14
i
FIGURE C-5. REDUCED BURNING VELOCITY RATIO AS A FUNCTION
OF TEMPERATURE DEPRESSION RESULTING FROM HEAT
LOSS C-15
FIGURE C-6. MEASURED BURNING VELOCITIES OF METHANE/
CARBON DIOXIDE/AIR MIXTURES C-17
FIGURE C-7. MEASURED BURNING VELOCITIES OF METHANE/
NITROGEN/AIR MIXTURES C-18
FIGURE C-8. MEASURED BURNING VELOCITIES OF METHANE/AIR
MIXTURES SATURATED WITH WATER VAPOR AT 20 C. . . .C-19
FIGURE C-9. REDUCED CRITICAL VELOCITY GRADIENT AS A
FUNCTION OF TEMPERATURE DEPRESSION RESULTING
FROM HEAT LOSS = . . . .C-22
FIGURE C-10. REDUCED CRITICAL VELOCITY GRADIENT AS A
FUNCTION OF TEMPERATURE INCREASE C-24
FIGURE C-ll. EFFECT OF RECIRCULATION ON MASS FLOW RATE OF
FRESH MIXTURE (FIRING RATE) AT STABILITY LIMIT . .C-27
FIGURE C-12. TWO-PULSE COMBUSTORS OF MULLER DESIGN, 4-IN. APART
CONNECTED AT COMBUSTION CHAMBERS BY 24-IN. LONG
TUBE, AND FIRING AT 200,000 BTU/HR EACH C-31
FIGURE C-13. NOISE SPECTRA FOR TWO FIRING RATES OF LARGE
AIR HEATER C-32
FIGURE C-14. COMBUSTION-ROAR AMPLITUDE-FREQUENCY SPECTRUM
AT 40,000 BTU/HR, USING TWO IMPINGING NATURAL
GAS JETS C-37
FIGURE C-15. OVERALL DECIBEL LEVEL (SPL REF. 20 MICRO-
NEWTONS/M2) AT 3 FEET FROM PREMIX BURNERS(S)
AS A PRODUCT OF PRESSURE DROP ACROSS BURNER
AND BTU/HR BASED ON AVAILABLE AIR C-41
FIGURE C-16. DECIBEL LEVEL AT PEAK FREQUENCY OF A NOZZLE-
MIX BURNER, WITH DATA AT CONSTANT NATURAL
GAS FLOW RATE (0), AND CONSTANT AIR FLOW
RATE (0), CORRECTED TO CONSTANT TOTAL FLOW
RATE C-43
FIGURE C-17. EFFECT OF OTHER NOISE SOURCES ON TYPICAL
COMBUSTION-ROAR SPECTRUM FOR A NOZZLE-MIX
BURNER . . C-45
-------
C-v
FIGURE C-18. THE RATIO OF EFFICIENCY OF CONVERSION OF
CHEMICAL TO ACOUSTIC ENERGY AS A FUNCTION
OF DIMENSIONED PRESSURE DROP C-46
FIGURE C-19. TYPICAL INSTALLATION OF AN INLET MUFFLER ON
A GAS BURNER FOR USE IN AN OIL REFINERY C-48
FIGURE C-20. FLOW PATTERNS AND FLAME FORMS OF GAS
FLAME WITH SWIRLING AIR FLOW C-5I
FIGURE C-21. THE DEPENDENCE OF FLAME TYPE AND FLAME NOISE
ON BURNER QUARL ANGLE FOR FLAME WITH SWIRLING
AIR FLOW AND AXIAL FUEL INJECTION C-52
FIGURE C-22. SCHEMATIC DIAGRAM OF SWIRL BURNER C-57
FIGURE C-23. THE ISOTHERMAL FLOW STATE WITH A PRECESSING
VORTEX CORE oC-58
FIGURE C-24. SPATIAL DISTRIBUTION OF STREAM FUNCTION Y/¥ . . . .C-59
o
FIGURE C-25. DIMENSIONLESS FREQUENCY AS A FUNCTION OF
REYNOLDS NUMBER FOR SWIRL BURNERS, WHERE f =
FREQUENCY, D = DIAMETER, Q = VOLUME FLOW RATE,
-^ = INLET ANGULAR MOMENTUM. NOTE THAT - LD/.i 2
IS 2/,T TIMES THE CONVENTIONAL SWIRL NUMBER
2G^/DGx C_60
FIGURE Cr26. THE EFFECT OF REYNOLDS NUMBER ON THE FREQUENCY
PARAMETER FOR PREMIXED COMBUSTION AND ISO-
THERMAL STATES .c-62
FIGURE C-21. AMPLITUDE-FREQUENCY SPECTRUM FOR MAXIMUM
NOISE OUTPUT AT 1.65 x 10"3 m3/s AIR c-64
FIGURE C-28. ACOUSTIC POWER OUTPUT OF A SWIRL BURNER
AS A FUNCTION OF FLOW RATE c_65
-------
PARTC
FLAME STABILITY AS AFFECTED BY
COMBUSTION MODIFICATIONS
by
A. A. Putnam and M. A. Duffy
BATTELLE
Columbus Laboratories
OVERVIEW
Utilizing various combustion modification techniques to control
NO emissions from industrial boilers can lead to severe flame stability
X
problems. Because flame stability is directly related to the basic fuel
parameters of burning velocity and critical velocity gradient, a change
in fuel composition at some point in the combustion system or a change
in the burner can alter these parameters and affect the stability of a
burner-furnace system. The flame stability criteria of a burner-furnace
system must not only be considered in traditional terms of flash-back,
blow-off, and quenching potential, but also in terms of the potential
for the system to generate combust ion-induced noise.
The control of NO through combustion modification is a relatively
X
new development and can impose some requirements seemingly opposed to those
necessary to satisfy operational demands of a boiler-furnace system .
These modifications include, low excess air, steam/water injection, flue-
gas recirculation, two-stage combustion, biased firing, flame type changes
induced by burner swirl, and mixing rate changes produced by burner de-
(2)
sign changes . Because flame stability is related to basic fuel para-
meters of burning velocity and critical velocity gradient, the degree of
applicability of each of these methods will depend on the type of fuel
being fired. In addition, it has been shown that the minimization pro-
cedures for thermal NO are not the same as for the fuel NO . The
x x
combustion engineer must consider all these factors in the designing
of systems to meet acceptable NO levels while not causing significant:
A
deterioration of boiler performance.
-------
C-2
This part of the report is intended to provide not only speci-
fic techniques for suppressing flame instability and combustion-induced
noise in an industrial boiler system, but also background material des-
cribing basic flame instability and noise generating phenomena. Even if
the phenomena of flame instability in a modified boiler system were fully
understood, which is not the case, that understanding would not be suffi-
*
cient for the designer. The designer must blend the basic principles
presented in this report with his own ingenuity in achieving the best
boiler system design for a particular application.
Because the discussion of flame stability and combustion-
induced noise is necessarily complex, a summary of the conclusions is
given first, followed by suggestions of future work. Next flame stability
is considered in a very broad sense. Not only are the changes in blow-
off, flash-back, and quenching potential of a design considered, but also
the change in potential for producing combust ion-induced noise and
combustion-driven oscillations.
Significance of Basic Phenomena
Relative to Combustion Modification
From the discussion of flame stability and combustion noise
that will follow, several general conclusions can be drawn as to the effect
combustion modification has on stability and noise. Because there are
voids in present technology and because these basic phenomena are often
unique only to specific systems, only general statements can be made.
These include
1. Recirculation without excessive cooling of the
recirculated gases can actually increase the
maximum firing rate (excluding the effect of
increased pressure drop through heat exchangers)
through increases in the critical velocity gradients.
Excess cooling will decrease the maximum firing rate.
Design changes for pollution control will probably
fall in the "excess cooling" category.
In general, design application of combustion fundamentals is still
an art. Current mathematical models of combustion systems are still
not sufficiently flexible to permit detailed "computer design".
-------
C-3
2. Two-stage combustion can either increase or decrease
burner operating range because the effect depends on
the details of the burner-furnace system. As a retro-
fit, decreases result.
3. Steam or water injection will decrease the stability limits
4. Conversion of combustion systems to use of two-stage
combustion, recirculation, and other features for pollutant
reduction can be expected to produce the normal incidence
of combustion-driven oscillations, because it is common
in the development of any new burner-furnace system to
encounter these problems. Because of the short time
factor involved, and the large number of conversions
of existing units and changes to new designs, this
problem will be amplified.
5. Changes in design which lower the stability limits
will tend to produce an increased incidence of
combustion-driven oscillations, and, near the rated
firing condition, an increased intensity of combustion
roar unless the unit is derated.
6. Recirculation (with cooled products) and steam addition
will decrease the mass burning velocity and the expansion
ratio between burned and unburned mixture. Provided that
the operating range is well withir. the stability limits
(cf items 3 and 5), both of these effects will tend
to decrease the noise output, perhaps by a significant
amount,' but experimental confirmation is not presently
available.
7. Two-stage combustion can be expected to increase the
combustion roar and the propensity for combustion-
driven oscillations. As a retrofit there will also
be a tendency for unstable fluid dynamic phenomena to
occur. In the case of biased combustion, careful ex-
amination of the details of the system might permit a
statement to be made relative to combustion roar but
not combustion-driven oscillations,on the basis of
present technology.
* Assuming 25 percent addition of recirculated products which have cooled
halfway to ambient temperature, the temperature of the mixture may be
about 480 K as compared to 660 K without loss of heat. Using Figure C-4
to determine the burning velocity ratio, correcting the velocity of
sound (note that this factor has not been examined experimentally or
theoretically), and correcting for the higher intensity of turbulence
from the higher flow rate, the efficiency of noise conversion drops
to 0.254 of the original value and the sound-power level drops by
6 dB.
-------
C-4
Research Needs
This study points to the following research needs relative to
flame stability and combustion noise in industrial boilers as affected
by combustion modifications:
1. The excellent correlation of burning velocity data and flash-back
data on stoichiometric mixtures of three fuels over a wide range of
simulated recirculation ratios and temperatures,using the product
temperature control theory, suggests that this concept is worthy of
(a) deeper examination from a theoretical standpoint, (b) application
to a wide range of mixture ratios and fuels using pertinent
data in the literature, and (c) experimental confirmation with fuel-
recirculated product mixtures in industrial burners, using industrially
pertinent fuels.
2. The most common type of excessive noise from a furnace, after the
combustion-driven oscillation problems have been handled, is that
resulting from approach to flame blow-off. Thus, there is a need
for studying the stability limits of industrial-type burners, as con-
trasted to simple laboratory burners, from both the burner capacity
standpoint and the noise standpoint. An understanding of the stability
limits of typical industrial burners would aid considerably in pre-
dicting problems and designing around problems associated with com-
bustion modification.
3. The following discussion shows that the details of noise production
by a turbulent flame are not fully understood. The semiqualitative
arguments used to derive correlating relations contain several terms
not supported by experimental data or rigorous theory. In particular,
the relation used to predict the effects of recirculated products is
open to some question. A combined experimental and theoretical
study would appear to be indicated.
-------
C-5
FLAME STABILITY
General Description
Generally speaking, there are three aspects of flame stability
to be considered; blow-off, flash-back, and extinction or quenching.
Figure C-l shows how these are related for a Bunsen-type burner on
a dimensionless plot of the ratio of flow velocity to burning velocity
(V/F) as a function of the Peclet number based on burning velocity and
V*
burner diameter (FD/D ). This may be compared with the more usual
(4)
dimensional stability plot of Figure C-2 which requires one plot for
each burner size, fuel, and pressure.
Laminar Flame Stability
Considering a point on Figure C-l (at about 60, 1.0), it is
seen that an increase in flow velocity or decrease in burning velocity
will cause the flame to blow off. A modification of the flow conditions,
such as by an electric field, can delay this blow-off. A decrease in
flow velocity will cause the flame to flash back upstream. As shown in
this figure, an increase in thermal diffusivity, D , say, by a decrease in
pressure, will result in extinction of the flame from thermal losses.
A constant Reynolds number curve of about 2000 has been added
to Figure c-1. The curve has a 45° slope moving downward to the right.
Up to this critical Reynolds number, the slopes of the blow-off and flash-
back velocity gradient are constant (except near extinctions). On passing
through the transition Reynolds number, the flame becomes turbulent. The
blow-off and flash-back curves jog and change slope, but the overall pic-
ture remains the same. For other types of burners, such as ducts with
axially symmetric central bodies (see below), or two-dimensional systems,
the same general characteristics hold. Finally, if the flame is a diffusion
flame rather than a premixed flame, these relations can be used if the com-
position is defined in the flame-holding region.
V - critical velocity, F = laminar burning velocity,
D = diameter, Dfc = thermal diffusivity.
-------
C-6
5.0
2.0
1.0
0.5
0.2
Blow-off
Re =
2000
Band for all
extinction data
of reference
Tube Diam, Electrode
Potential
in.
v 19/64
+ 19/64
o 7/16
x 7/16
A 7/16
0
+ 3000
0
+ 3000
Arc-over at +3000
50 percent
scatterband
from reference
10
20 50
FD/Dt
100 200
500
FIGURE C-l. FLASH-BACK, EXTINCTION, AND BLOW-
OFF CURVES WITH AND WITHOUT 3000-v
FIELD
-------
C-7
4 6 8 10 12
Gas Concentration, percent
14
16
FIGURE C-2.
EFFECT OF NATURE OF SURROUNDING
ATMOSPHERE ON BLOWOFF OF NATURAL
GAS-AIR FLAMES; TUBE DIAMETER, 0.577 cm.
-------
C-8
Stability of Turbulent Premix Flame
For turbulent premix flames, Spalding and Tall showed
that the blow-off limits of simple axially symmetric flame holders in a
premixed stream gave a relation of the form V/F w DF/D for Reynolds
numbers above about 15,000. This can be presented in the alternative
2
form, V/D ~ F /D . For Reynolds number below 15,000, the relation was
0 41"
V/F ~ (DF/D ) ' , This relation can be, and was explained, on the basis
that the size of the recirculation region downstream of the flame holder
relative to the flame-holder diameter decreased with increasing Reynolds
numbers up to a certain point; it was this size of recirculation region
rather than the flame-holder diameter that was the important dimension
to stability. Using the critical flow dimension, L, related to the
size of the recirculation regions rather than diameter, a velocity gra-
dient term, V/L, becomes the significant aerodynamic variable, proportional
2
to the fuel-air property (F /D ) at blow-off.
Stability of Turbulent Diffusion Flame
In the case of turbulent diffusion flames, the stability phenom-
enon is more complex than for turbulent premix flames. Generally speaking,
the flame will be stabilized near the region where a stoichiometric con-
dition exists, that is, near a maximum burning velocity and minimum flame
thickness condition. When the stabilized region is relatively fixed, the
interaction of the (mass, momentum, and thermal) diffusion relations is such
that the velocity gradient criterion is still highly successful for predicting
blow-off in the nonturbulent region. For turbulent conditions, and
free floating flames, the results are more complex, but the combustion
characteristics of burning velocity and flash-back velocity gradient should
still be adequate for comparison purposes.
-------
C-9
In the case of liquid fuels, there are two situations that
arise. First, when obstacles are present as flame holders, the liquid
droplets follow trajectories that tend to cause impingement. Thus the
obstacles become wet. Depending on its temperature, the fuel may shear
off either as droplets or as vapor. In any case, in the recirculation
zone, behind the obstacle, the composition is not necessarily that of the
oncoming stream. Thus the stability of the flame in the recirculation
zone must be interpreted on the basis of the vapor-air mixture in the re-
circulating zone and immediate vicinity, and not on an average basis. A
similar argument has to be used in the case of the flame spreading from
the piloting recirculation zone.
If there is no obstacle-induced recirculation zone for piloting
the flame, then the fine drop vaporization and mixing of the fuel with air
has to be considered. It might be noted that at atmospheric temperature,
droplets of the order of 5 micron or less result in flames generally
similar to that of a vapor. On this basis, the observed stability phenomena
can be related to those observed with a premixed gaseous fuel.
Basic Stability Parameters
Only a small number of fundamental properties of combustible
mixtures are required to correlate experimental data when dimensionless
relations are used. In fact, for considering the physical properties
(rather than chemical properties) of flames, two parameters appear to
be sufficient, the laminar burning velocity and the laminar flame thick-
ness. The laminar burning velocity has been identified as significant
in Figure C-l. However, in the horizontal coordinate, the dimensionless
parameter should have been D/6, rather than FD/D , where 6 is a suitably
* t
defined laminar flame thickness. The substitution stems from the lack
* There are several ways to define flame thickness. The various
thicknesses are related by (hopefully) constant factors.
-------
C-10
of data on laminar flame thickness; because of this, the approximate
relation that F6/D is a constant is used to eliminate 6. It might
be noted that some investigators prefer to use D , a mean.molecular
diffusivity, rather than D , the thermal diffusivity. But while this is
important in considering the kinetic details of combustion, the difference
is not significant to this discussion.
A third parameter, more convenient to obtain than §}
is the ratio, F/6 . This ratio can be considered a chemically con-
trolled reaction rate per unit volume. It is also proportional to
the velocity gradient at flash-back for a Bunsen-type burner and, in
premixed turbulent flames from flameholders, to blow-off velocity
gradient. Extensive tabulations of these values for various fuel
* (4)
gases are available in Bureau of Mines RI 5225.
It follows that the predictions of the effect of various
changes in burners and burner systems made to control pollution can be
based on the changes that occur in these basic flame properties, plus
a knowledge of the accompanying dimensional and velocity changes. There-
fore, the effects of recirculated products on burning velocity and flash-
back velocity gradient will be considered before proceeding to some examples
of the effects expected in burner performance from changes made to suppress
pollution.
(4 )
It should be noted that Grumer, et al., presented extensive sets
of data on the stability limits of various hydrocarbons, hydrogen,
and carbon monoxide with air. These cover a wide range of mixture
ratios for each fuel. Furthermore, rules are formulated for com-
puting the limits for mixed fuels, and notice is given of combina-
tions that do not follow these rules. However, using data on stra-
tegically chosen mixtures as the starting point rather than pure
fuels, the simple rule can be extended to the problem cases with
some degree of success.
-------
Oil
Burning Velocity
To evaluate the various types of changes that might
be made in a combustion system to reduce pollution, changes in burning
velocity as a result of (a) changes in mixture ratio, (b) changes in
temperature, (c) addition of recirculated products, and (d) addition of
steam or water must be considered. Since the performance of most hydro-
carbon fuels are similar (except for stability of a laminar flame front
in certain special cases wherein the relative molecular diffusivities of
fuel and oxygen became important), general conclusions can be based in
most instances on consideration of data on any of the hydrocarbon fuels.
( a \
Figure C-3 shows the burning velocity of several hydro-
carbon-air flames, obtained using the angle of the inner cone of the
flame above an accelerating nozzle, as detected by a modified Schlieren
method. It is noted that the curves are all much the same shape, with
peaks that are slightly on the fuel-rich side of stoichiometric (90
percent to 95 percent stoichiometric air). Not shown in this figure are
ethylene, peaking at about 0.70 meter/sec, and hydrogen, at 2.80 meter/sec.
Mixtures of hydrocarbon fuels are essentially linear in respect to burning
velocity. However, hydrogen additions do not have a linear effect, and
( 9 )
CO addition is even more confusing in its effect. Nevertheless, the
general burning velocity curves are the same shape, and conclusions may
be drawn on the basis of any of the fuels.
(10)
Derivation of Basic Relation. Karr and Putnam, from a study
of available data, suggested that the addition of recirculated products
without loss of heat to a premix burner does not change the flame shape.
In other words, the addition of the products can be ignored in this
special case. A theoretical argument based on the Brokaw-Gerstein
formulation of the SZFK equation for burning velocity led to the same
conclusion.
-------
C-12
0.50
E 0.40
o
o
c
c
t_
00
0.30
0.20
6 8
Volume Percent Fuel
10
12
FIGURE C-3. BURNING VELOCITIES OF ETHANE, PROPYLENE, PROPANE,
n-BUTYLENE-1 and n-BUTANE WITH AIR
-------
C-13
Following this line of reasoning, the effect of the addition of
cooled products of combustion can be determined on the basis of the effect
of the addition on the peak flame temperature, and the effect of peak flame
temperature on burning velocity for undiluted mixtures. Furthermore, if
products from the burning of one mixture are added to a mixture of another
composition, the effect can be determined by considering the final tempera-
ture and composition. This follows because the theoretical arguments that
appear to give predictions compatible with the data are based on the
assumption of a controlling influence of the final temperature and com-
position on the reaction rate. Again, using the Brokaw-Gerstein formu-
lation, but allowing for the loss of heat from the recirculated produc-
tion, and assuming a small drop in maximum flame temperature,
£n.[(F'/Fu) (TQu/T^ ) (M/M)] = -(T-To') (E/2RT*) (1)
where, using Figure C-4a and c as a basis, T is the temperature that
the mixture (of recirculated products plus unvitiated fuel-air mixture,
with total mass rate M) would have had without loss of heat from the
recirculated products, T^ is the actual temperature of the mixture, T
is the temperature of the unvitiated fuel-air mixture of mass rate M
and T is the flame temperature of the incooled products. F is the
u
reference burning velocity at temperature T , and F' is the burning
velocity of the vitiated, cooled mixture.
Discussion of Data. Figure C-5 shows the data obtained by
Karr and Putnam on the rig of Figure C-4c, plotted in the indicated
manner. E was found to be about 40 kcal/mole for the solid curve, which
is based on the assumption of a theoretical adiabatic flame temperature
plus a temperature invarient specific heat.
(12)
Reed, et al., studied the effect of vitiation on burning
•velocity by the use of nitrogen and carbon dioxide, at the ambient tem-
perature. This type of experiment is similar in concept to that of
Figure C-4b . For convenience, these diluents were mixed first with
the methane, before mixing with the air, so the data are given in the
ou
o:
-------
C-14
MO
T00
Fresh
Mixture
MO
Recirculated products, V
Tf
Mixing
Chamber
a. Recirculation With
No heat loss
M= M0+ Mr
0
No Heat Loss
I
r
Reaction
Zone
MO
T,
__ Recirculated t>roducts> Mr
MO
TOU
Fresh
Mixture
MO
TOU
T
ou
Mixing
Chamber
^'XLimit h'iat lOJ
TOU
>S
Reaction
Zone
MO
Tf£
b. Recirculated Products at Ambien
Recirculated products*
M0
.TOU
ft
TOU
Fresh
Mixture
Mr
MO
TOU
Inner
Reactor
c.
Mixing
Chamber
^^Heat loss
M = Mo+Mr
V
r
Reaction
Zone
MO
T,'
*
General Case
^ Mr
V H*nt ln«
Fresh
Mixture
M0
Tou
Mixing
Chamber
M=M0i+Mr
Reaction
Zone
M
Tf'
d. Experimental Rig
FIGURE C-4. SCHEMATICS OF FLOW AND TEMPERATURE IN
VARIOUS RECIRCULATION SITUAT30NS.
-------
C-15
Karr-Putnam (propane)
Dugger
Jost (H2)
Reed, et al (methane)
-400
-200
200
400
600
K
FIGURE C-5. REDUCED BURNING VELOCITY RATIO AS A FUNCTION OF
TEMPERATURE DEPRESSION RESULTING FROM HEAT LOSS
-------
C-16
form of volume ratio of diluent in the fuel-diluent mixture. The burning
velocities for each fuel-diluent mixture are plotted against the fuel
concentration as a fraction of stoichiometric concentrations, as shown
in Figures C-6 and C-7 . Their data replotted on Figure c-5 by use
-f
of the relation T -T ' = (1890 K) (1 - 4^) show close agreement,
o o M
especially when considering that the fuel is methane rather than the
propane of Figure C-5 , the diluent is nitrogen rather than products of
combustion, and the diluent is at ambient temperature rather than near
the flame temperature.
Bugger reported data on the effect of initial mixture tem-
peratures on the burning velocity of methane, propane, and ethylene with
air. These data can be interpreted in the framework of the recirculated
products effect uncovered by Karr and Putnam. Thus, Dugger's data for
stoichiometric mixtures of propane and air are added to Figure C-5.
Considering the wide variation of flame temperature over the range of data,
as compared to the narrow range assumed is the derivative of Equation (1)
that leads to a straight line prediction, the slight curvature of the line
through the two sets of data is not unexpected.
It can be concluded that the above method of plotting experi-
mental data on a given fuel-air mixture with various amounts of recircu-
lated products added is acceptable for use in predicting the effects of
recirculation on burning velocity in practical combustion systems.
Steam or water injection reduces NO formation by lowering
flame temperature (water vapor in the atmosphere has a similar effect).
However, this reduction in flame temperature also reduces the burning
f-i o \
velocity as shown in Figure C-8 for a saturated mixture of methane
and air at 20 C. It might be noted that if Figures C-6, C-7, and
C-8 are normalized as far as diluent is concerned on the basis of molar
specific heats of the diluents, the effects on burning velocity become
essentially the same for all three.
-------
C-17
0.5
0.4
(S)
V.
E
5^
O
CD
O>
c
m
0.3
0.2
O.I
0
Symbol
•
A
°'o
100.0
87.6
75.0
67.9
I
% C02
0.0
12.4
25.0
32.1
I
I
0.8 1.0 1.2 1.4
Fraction of Stoichiometnc Fuel Concentration
FIGURE C-6.
MEASURED BURNING VELOCITIES OF
METHANE/CARBON DIOXIDE/AIR MIXTURES
-------
C-18
0.5
0.4
0.3
o
o
c
'c
1_
CD
0.2
O.I
O.Q
CM,
100.0
77.2
50.0
41 .5
L
0.0
22.8
50.0
58.5
J.
_L
' 0.8 1.0 1.2 1.4
Fraction of Stoichiometric Fuel Concentration
FIGURE C-7. MEASURED BURNING VELOCITIES OF
METHANE/NITROGEN/AIR MIXTURES
-------
C-19
0.5
0.4
E 0.3
o
o
o>
CP
c.
m
0.2
O.I
Symbol
A
D
A
O
%CH4
100.0
79.0
81.00
82.35
83.84
85.14
i
I
% H20
0.0
20.95
19.00
17.65
16.16
14.86
i
0.8 1.0 1.2 1.4
Fraction of Stoichiometnc Fuel Concentration
FIGURE C-8. MEASURED BURNING VELOCITIES OF
METHANE/AIR MIXTURES SATURATED
WITH WATER VAPOR AT 20 C . NOTE
THAT PERCENT OF H20 in CH4/H20
MIXTURE VARIES AS THE STOICHIO-
METRIC RATIO VARIES
-------
C-20
Chemically Controlled Reaction Rate
Per Unit Volume
It is noted that the chemically controlled reaction rate
per unit volume has the dimensions of reciprocal seconds. Thus, one
might suspect that any measured flame phenomena that has a time dimension
could be related to the term. Indeed, Giammar and Putnam have
suggested that this factor is related to the peak frequency of the tur-
bulent flame noise spectrum. A variety of ignition delay measurements
are also in this class. But for the present discussion the flash-back
velocity gradient discussed above will be used as the indicating para-
meter for the chemically controlled reaction rate.
Derivation of Basic Relations. -In order to determine a form
for predicting the data on chemically controlled reaction rate per unit
volume, the assumption is made that the controlling feature of a flame
j^s the region jLn which combustion j.s nearly complete. On this basis, it
*
is assumed that Ff &/Dff is a constant. On the basis of the mixture
supply temperature, this became (F6/D ) (T/Tf) where n is between 1
and 1.5. The volume reaction rate per unit volume, R , on the basis of
the supply conditions then becomes R = F/6 = K (F /D )(T/T )n , and
« -i
the mass reaction rate per unit volume, R = K (F p/D ) (T/T,.)n . The
m t f
mass reaction rate of the unvitiated material per unit volume is given by
* • .
R = R (M /M). This last rate is quite meaningful since it permits
m m u
direct comparison at a constant firing rate of fresh mixture before
vitiation.
* We note that the assumption that F6/Dt is a constant, where all
terms are defined at the fresh mixture temperature, is quite common.
This assumption was made in Reference (10) , and led to a slightly
different equation than deduced herein.
-------
C-21
Making the assumptions consistent with those in Reference (10),
R M 2 T „
. £n (_v } (_° ) (^) = E_ (T^ _ T^- } ^ (2)
vu o RT_
R M 2
in (^) (^) =--4 (T0-To), (3)
mo M RTf
and j.
mo M f
Discussion of Data. Unfortunately there are few data to use
in confirming these relations. Reed and Wakefield present some blow-
off data on Bunsen-type burners using methane, with a diluent composition
simulating the concentration of a burned stoichiometric methane-air mix-
ture. For our purposes, the only easily interpreted data are therefore
for the stoichiometric mixture. The mixtures studies were at room tem-
perature, simulating the situation of Figure C-4b. . These data were put
in the form comparable to Equation (2) by multiplying the stability ratio
by (MQ/M)2 and determining T -T ' from 1900/ Q— -\,where Qr/Q was
U - 'I
determined from the percent (>2. We note that TQU /T^ = 1 for these data.
Figure C-9 shows the resulting curve, which turns out to be
a straight line with the same slope as that of Figure C-5 . This indi-
cates a similar activation energy. While the effect of the temperature
term T /T / is not confirmed because of the lack of the proper data,
' ou o
it does seem that the agreement with the theoretical prediction as far
as pattern of data, and agreement with Figure C-5 are concerned, does
give confidence to the proposed equation for prediction changes in cri-
tical velocity gradient.
-------
C-22
1.0 O
0.8 -
> >
o:
Reed 8 Wakefield (CH4)
Grumer, et al (H~)
O.I
0.08 -
0.06
200
400 600
2(T0-To). °K
800
1000
FIGURE C-9. REDUCED CRITICAL VELOCITY GRADIENT AS A FUNCTION OF
TEMPERATURE DEPRESSION RESULTING FROM HEAT LOSS
-------
C-23
Grumer, et al., obtained data on the flash-back and blow-off
/ 4 \
methane-air mixtures over a range of temperatures. ' The flash-back
data can be considered in the same light as the burning velocity data of
Dugger, in extending the stability curve. The more numerous Bunsen
burner type blow-off data on the effect of temperature changes (others
have investigated this) is not within the framework of this study because
the ambient air (in the reported studies, which enters into the blow-off
stability) is not at the experimental temperatures but is at ambient
temperature. Thus, the blow-off stability limit at higher temperatures
is depressed.
Figure C-10 shows these flash-back data. The curve through
the data is from Figure C-5 , obtained from flame speed considerations,
Grumer, et al., suggested that mixtures of fuels may be handled
by a linear summation on a volume basis of the flash-back or blow-off
gradients assigned to each component. Except, as the authors point out,
for large additions of H2 or CO, this seems to be a satisfactory approach.
However, they also suggest assigning to inerts a value of zero in the
additive relation. This Bureau of Mines suggestion does not agree with
the relation suggested by this study except for one specific mixture of
methane and ethane with small amounts of diluent. Therefore, the subject
was examined for confirming data. There was one set of stability data for
methane with about 10 percent nitrogen but the flash-back showed an anomaly
in that the addition of nitrogen increased the flash-back velocity. This
is contrary to the prediction of both approaches. The second set of data
were for hydrogen-nitrogen mixtures. These data are shown in Figure C-9
with the temperature diffusion normalized by the square of the ratio of
flame temperatures,, No normalizing change was made relative to the value
of E. The agreement is excellent. To inspect the results further, data
on burning velocity of nitrogen-diluted air mixed with hydrogen were reaJ
from Jost (Figure 90). The reduced burning velocities are plotted in
Figure C-5 against the equivalent temperature difference used, normalized
to correct for the difference in flame temperatures. Again the agreement is
excellent, with the possible exception of the last point.
-------
C-24
3.0
H°
2.0
1.0
0.8
0.6
Curve from Figure c-4-
J —I 1 L
-600 -400 -200
2(T0-T0),°K
200
Figure C-10. REDUCED CRITICAL VELOCITY GRADIENT AS A
FUNCTION OF TEMPERATURE INCREASE
(Grumer, Harris, and Rowe)
-------
C-25
Effect of Design Changes on Stability
In general, the details of a design change to decrease the
NO production have to be considered before a prediction can be made as
to the concurrent effect on burner stability. To illustrate the pro-
cedure, two cases are considered herein. In the first, the effect of re-
circulation of the products of combustion on the maximum firing rate is
considered. In the second, the effect of two-stage combustion at a
constant firing rate on the proximity of the stability limit is considered.
In both instances, the initial configuration is used as a standard.
Recirculation. A discussion on the effect on stability of
recirculating the products of combustion into the air supply of an in-
dustrial gas-fired burner in a furnace will include the range of cases
from recirculation of products of combustion without loss of heat to pro-
ducts with complete cooling to the incoming air temperature. The primary
air-fuel ratios will be assumed to remain constant. To carry out the com-
putations, Figure C-9 will be used. The criterion of merit will be the
fraction of the undiluted firing rate that is attained at the flame
stability limit. Since the size of the burner is assumed constant, the
item of interest is given by Equation (4) .
R* M
To determine T - T , we assume as an example a temperature difference,
° ou
T,. - T , of 1800 K. As a result
f ou
Mo
1800 (i - — ; = T -T .
M o ou
For no loss of heat from the recirculated products,
w
M
R*
K
* M M
mo M0 M0
-------
C-26
For a loss of heat sufficient to reduce the temperature of recirculated
products to the ambient temperature,
; M
- - - (1800) jl -^- .
RT£ I M
Figure C-ll shows the effect of recirculation on the firing rate
at the stability limit. It is seen that a small reduction in temperature
of the recirculated products can be tolerated with no reduction in firing
rate at the stability limit. For moderate reduction in temperatures of
the recirculated products, a minimum reduction in firing rate is attained,
and further increase in recirculation increases the stability. For larger
reductions in temperature, the reduction in stability becomes excessive,
Any specific situation has to be measured also in terms of the
concomitant reduction in NO and the possible change is pressure drop and
X
performance of the heat exchanger components of a furnace system. • The
t / o ^
concensus of several discussions ^ is that the retrofitting to use re-
circulated products will 'reduce the capacity of present installation,
and probably of new designs.
Two-Stage Combustion. One approach to the reduction of NO has
X
been the use of two-stage combustion. For furnaces with multiple burners,
this may be done in many instances by diverting the fuel from the last set
of burners to the previous sets, with a resultant increase in the fuel-air
ratio in the initial sets of burners. If there are n sets of burners, the
air/fuel ratio relative to stoichiometric, or.., would then be reduced to
., 1. *
«2 =*l (1 --).
(43)
* Dykama points out that, because of the back pressure of the flame,
this relation over-estimates the primary combustion air. Because the
flame pressure drop varies with flame stabilizing position and thus mixture
ratio, fluid dynamic instabilities of an undesirable amplitude can
result. Robinson and Cavers ^3) list the fuel sensitivity to this
problem as P.C. - none, oil - small, and gas - large.
-------
C-27
Temp of recirculated
products above ambient
1 . 2 3
Regulated Mass Flow Rote
Mass Flow Rate of Fresh Mixture
FIGURE Oil.
EFFECT OF RECIRCULATION ON MASS FLOW RATE
OF FRESH MIXTURE (FIRING RATE) AT STABILITY
LIMIT
-------
028
The effect of this change on the stability limits will be examined as a
sample case, for a set of natural gas/air burners, with 120 percent and
110 percent theoretical air before modification. For the illustration,
the data of Figure 20 of Reference (4) will be used; the data are for
methane with a mass ratio of air to methane at stoichiometric of 17.2.
For the original system, the critical velocity gradient at flash-
back at 120 percent air (.833 fuel) is 240/sec and at 110 percent air
(.909 fuel) is 350/sec. (Note the argument presented previously against
using blow-off limit as a measure of chemically controlled reaction rate
per unit volume, or stability in closed system). For several different
numbers of burner banks, the following table may be produced.
TABLE C-l. EFFECT OF TWO-STAGE COMBUSTION
Number of
Burner
Banks
3
4
5
6
7
4
5
6
7
Air /Fuel
Air /Fuel
Stoich.
0.80
0.90
0.96
1.00
1.03
0.825
0.880
0.917
0.943
Flash-Back
Gradient, Mass Flow
sec" Rate
(a) 120%
140
330
390
390
380
(b) 110%
180
300
350
380
Stoichiometric
1.023
1.015
1.012
1.009
1.008
Stoichiometric
1.015
1.012
1.009
1.008
Fractional
Increase in
Stability Limit
- 0.43
+ 0.35
+ 0.61
+ 0.61
+ 0.57
- 0.49
- 0.15
- 0.01
+ 0.08
It is clear from a study of these results that the stability of the combus-
tion system as related to its rated firing rate may increase or decrease,
depending on the number of burners involved in the system and the overall
air/fuel ratio before modification. For the smaller numbers of burner
banks, however, the changes cause a deterioration in performance.
-------
C-29
For this reason, retrofits based on this principle decrease the
furnace capacity, but, in new designs, this need not be the case .
COMBUSTION NOISE
Historically, the combust ion-system noise of interest was in the
high frequency screech and lower frequency pulsations that occasionally
emanated from such systems because such noise could be of intolerable
level, detrimental to combustor performance, or cause physical deteriora-
tion of the equipment. However, both because of the increased realization
of the detrimental effects of noise on work output, and the increased
attention of various legislative bodies to the problems of industrial
noise, the combustion community is now adding to its concern for combustion-
driven oscillations the industrial counterpart of the comforting "roaring"
fireplace. In addition to (1) combustion-driven oscillations, and (2)
combustion roar, at least two other classes of combustion noise must now
be considered. These are (3) the unstable combustion noise generated by
the precursor of the blow-off conditions of a flame (discussed previously),
and (4) the amplified noise of periodic flow phenomena. Each of these
classes will be discussed in sufficient detail to transmit a general under-
standing of the specific class. This will be followed by discussion of
the significance of each class relative to design changes that might be
made to improve the pollution performance of the existing combustion sys-
tems or new systems.
Basic Phenomena
As pointed out above,, combustion-driven oscillations are the
most widely investigated phenomenon, of the classes combustion-generated
noise. Combustion-driven oscillations are characterized by the presence
of some sort of feed-back cycle. This is in contrast to the other three
types of phenomena that do not have such a feed-back cycle present. How-
ever, when combust ion-driven oscillations are not strongly generated, thn /
can be confused with the acoustic amplification of specific frequence ^.? ir
the broad band spectrum produced by combustion roar. Furthermore, when
-------
C-30
specific frequency generated mechanisms such as vortex shedding are present,
these specific aerodynamic frequencies can produce noise that is ampli-
fied by the combustion process; this phenomena can also be confused with
low amplitude combustion-driven oscillations. Finally, it must be noted
that the noise produced by the vortex shedding phenomena (commonly con-
sidered to be related to a Strouhal number) is often of about the same
intensity and in the same noise spectrum as one obtains from combustion
roar; therefore these two sources of noise can be confused.
Combustion-Driven Oscillations
Combustion-driven oscillations, often termed pulsating combus-
tion, in larger pieces of equipment with lower natural frequencies, in-
volve a feed-back cycle that converts chemical energy to oscillatory
energy in the gas flow. The noise spectrum ordinarily involves one
specific frequency and its harmonics. Figure C-12 shows the noise spec-
* r
trum obtained for an extreme case of combustion-driven oscillations, a
situation in which the oscillations were purposely generated in a pair of
pulse combustors. Figure c-13 f.hows another example of combustion-
driven oscillations, in a large air heater. '
Typical efficiencies of conversion of chemical energy to noise
— A-
are about 10 , although purposely produced pulsations in pulse combustor
/i g\
can have efficiencies considerably higher. ' As a result of the high
conversion efficiency relative to the other types of combustion generated
noise, not only can the noise produced be unbearable, but large changes
in combustion efficiency and physical destruction of the equipment can
occur. Thus, combustion-driven oscillations have always received atten-
tion, both by industry in respect to residential and industrial combustors,
*
The sharpness of the peaks as recorded involves not only the physical
characteristics of a pulsation but the characteristics of a recording
system.
-------
100 -
0)
>
O)
O
cu
Q
n
i
100
FIGURE C-12,
200
300 400
Frequency, Hz
600
800 1000
TWO-PULSE COMBUSTORS OF MULLER DESIGN, 4-IN. APART
CONNECTED AT COMBUSTION CHAMBERS .BY 24-IN. LONG TUBE,
AND FIRING AT 200,000 BTU/HR EACH.
-------
C-32
1301—
120
m
•o
o>
4> 110
0)
D
CL. 100
O
O
90
80.
High fire
Moderate fire
10
15 20 25
Frequency, Hz
30
50
FIGURE C-13. NOISE SPECTRA FOR TWO FIRING RATES OF LARGE AIR HEATER
-------
C-33
and by governmental agencies in respect to rockets, ramjets, afterburners,
and similar combustion systems.
Reference 19 is used as a basic reference for following dis-
cussion of combustion-driven oscillations, since it covers the work
reported in the literature that is related to residential and industrial
combustion systems. A review of this work shows that the probability
that a specific change in boiler design (including burners) to reduce
pollution will promote combustion-driven oscillations is a function of the
driving mechanisms that may be present and the specific details of design.
Since more than one type of driving mechanism is possible in most com-
bustion systems, and since many of the acoustic and flow details of a
combustion system cannot be computed on the basis of present knowledge,
the prediction of the effects of the specific design change would appear
to be best handled on a probability basis. In fact, it has been shown
for certain combustion systems that, while some design change (for other
purposes than pollution control) have a high probability of eliminating
combustion-driven oscillations, there is also a finite probability that
they can worsen the situation.
However, in respect to some of the changes in design that might
be expected to eliminate pollution, some comment can be made relative to
the information in Reference 19 without looking at the details of design.
For instance, if staged-combustion is to be used, then one would expect
that the first stage of combustion will take place with a richer than
stoichiometric mixture. Thus, there is a high probability that the burn-
ing velocity will be greater than would be the case if staged combustion
were not used. An increase in burning velocity generally will tend to
produce a higher probability of occurrence of combustion-driven oscilla-
tions. Thus staging can be expected to increase the incidence of this
Pulse combustors appear to perform better with fuel-rich mixtures.
-------
34
type of problem. The use of low excess air falls in the same category as
that of staged combustion.
On the other hand, when the use of recirculated products of com-
bustion is considered, the recirculated product will have been cooled from
the maximum gas temperature. This will result in a reduction of the burn-
ing velocity and the basic chemically controlled reaction rate per unit
volume (see previous discussion on flash-back gradient). Both of these
changes are expected to reduce the probability of occurrence of combustion-
driven oscillations. The use of water injection falls into this same
category.
The situation relative to biased combustion is not clear cut.
Since some of the burners will be operating closer to stoichiometric or
possibly even on the fuel-rich side, the general tendency would be for
these burners to be a source of driving and to produce an increased
probability of combustion-driven oscillations. On the other hand, some of
the burners will be operating farther from stoichiometric on the excess
air side; these would tend to decrease the probability of generation
of combustion-driven oscillations. In addition, there is the possi-
bility that the two basic time lags of the two types of burner loadings
could be made such that under no circumstance could driving occur at the
lower frequencies of a combustion system.
One factor should not be overlooked. In the history of develop-
ment of burner-combustion systems one finds many problems of combustion-
driven oscillations. In the slow development of these systems in the past,
such problems were handled in a routine way, without receiving a great
deal of notoriety. However, with pressure for major changes across the
board of burner-furnace designs, the problems associated with combustion-
driven oscillations, although no more severe on a system basis than in the
past, will be more severe on the basis of the availability of time and
engineers to solve the problems. This effect is already showing up as
new low-pollution installations are made.
* Dykama*1 reported an interesting case in which secondary air was
introduced by cutting off the fuel from the lowest bank of burners.
The timing of the periodic component of the heat release rate in this
case, resulting from a first mode standing wave in the furnace, i;
such as to supply energy to maintain the oscillation. On the other
hand, the timing was incorrect for driving with the secondary air
supplied above the burner.
-------
C-35
Suppression of Combustion-Driven Oscillations. There are
several approaches to the suppression of combustion-driven oscillations. )20'
If the feedback system is known, suppression of the amplifying effect of
any or all the steps in the feedback cycle would help. That is, the
ratio of output amplitude to input amplitude in each step should be
reduced. For instance, if a flashing flame as a result of a periodicity
in velocity is involved, the flame might be stabilized. An alternative
approach is to shift the response time between output and input.
A second approach is to relieve the pressure in the region of
maximum pressure amplitude by an orifice or port to the surroundings.
However, this is not always a practical solution. An alternative is to
return part of a pressure signal out of phase with the acoustic pressure
oscillation in the combustion system. This can be done by the use of
quarter-wave tubes or Helmholtz resonator.
Damping and sound-absorbing materials may also be used, alone
or in combination with other approaches. In the case of frequencies
below about 200-400 Hz, this is not usually a practical approach, however.
In cases where feedback into the combustible mixture line, the fuel line,
or the air line is involved, and sufficient pressure is available, an
impedance matching device at the exit of the pertinent line can often be
used successfully.
Baffles at the entrance, exit, and in the interior of the com-
bustion system have been used successfully on various occasions, but the
reason for the success has not always been clear. Two specific examples
are porous duct sections and restrictive orifices at the exit of tunnc.l
burners.
Enclosure Effects. A brief comment should be made about the
consequences of various comparative values of the natural frequencies of
if
We note that the propensity for this type of driving is directly
related to the stability consideration discussion above.
-------
C-36
furnace and enclosure (or room). There will be little tendency of a room
to oscillate in response to the furnace frequency if no natural frequency
of the room or enclosure is close to the furnace frequency. But if a
room frequency and the furnace frequency are close together, and the
furnace is near a pressure antinode in the enclosure, the installation
will probably produce an intolerably noisy environment.
Combustion Roar
General Observations. The basic noise spectrum for combustion
roar has no specific frequency but a broad band of noise with a basic
form similar to that of noise from a jet. As mentioned above, the peaking
frequency appears to be related to the chemically controlled reaction
rate per unit volume. Figure C-14 shows a noise spectrum obtained
from a natural gas diffusion flame in an anechoic chamber. Typical
efficiencies of conversion to roar from chemical energy input of a burner
are of the range 10~8 to 10~6.(21) It is seen that this is at least two
orders of magnitudes lower than the efficiency of conversion expected
for combustion-driven oscillations. Little attention was given to this
form of combust ion-produced noise until recently, when it was realized
that it could be a significant contributor to environmental pollution.
Currently, however, a considerable amount of attention is being devoted
to this aspect of combustion noise and progress is being made rather
rapidly in understanding this phenomenon. * Results have already
emerged that are pertinent to boiler design changes to reduce noise
levels; any change that lowers the turbulence level of the combustion
region or intensity of combustion should result in a lower combustior roar.
Therefore, the use of recirculation or water injection would probably tend
to reduce the combustion roar output, while the use of staging or biased
combustion or low excess air would tend to increase the combustion roar.
In general, however, the effects available in one boiler while maintaining
satisfactory operation would be far less than the effects which one would
expect from changing the basic design to lower the intensity of combustion
or the turbulence level.
-------
80
_ 70
o>
O)
O
-L
100
_L
250
500 1000
Frequency, Hz
2500
5000
FIGURE C-14.
COMBUSTION-ROAR AMPLITUDE-FREQUENCY SPECTRUM AT 40,000
BTU/HR, USING TOO IMPINGING NATURAL GAS JETS
-------
C-38
The basic source of noise in the case of combustion roar is
well understood. The source is the movement of the flame front in the
turbulent flame, as the volume of gas increases on passing through flame
front. However, the specific details which would allow a prediction of
the noise output from a turbulent flame are not understood. This situa-
tion is understandable since the specific details of the propagation of a
turbulent flame are not completely understood as yet and the production
of noise adds one more level of complication to the problem. However,
it is valuable to consider this noise production in a simplified way, to
determine how various outside factors may affect the amplitude of noise
produced by a combustion system. The following comments are based on a
consideration of the literature on combustion noise and the various mathe-
matical models of combustion roar presented therein. The comments pre-
sented are not in agreement with many of those commonly cited in the
literature. However, it is believed that the presentation presented
herein is both technically and intuitively acceptable, and does form a
basis for organizing available information.
Theory of Combustion Roar. The basis for the following dis-
cussion is the assumption that, from an acoustic point of view, a turbu-
lent flame of commercially significant size is composed of an array of
monopole sources. ^ ' The sound power, G, produced by N monopole
sources is given by
/_..-. I ,
(5 )
where E is the volume expansion ratio of the burned to the unburned gas,
and q is the volume rate of consumption of the combustible gas in each ele-
ment. We assume that the time of consumption of an element is propor-
tional to df/u', where d, is the element thickness and u1 is the intensity
of turbulence. Thus we can replace d/dt by u /df. We also assume that
qN = Q, where Q is the volume firing rate of the flame. Making these
substitutions
A monopole source can be pictured as a sphere, periodically expand-
ing and contracting radially.
-------
C-39
^2(Vf
if } ^ c ) '
ST} -«s. £ S I ». 2
G -(-p^UTr1
VArrc / V d
With some further manipulation and the assumption that the burning
2
velocity, F, equals q/d , the efficiency of conversion of chemical energy
to acoustic energy, Tj, is given by
/*& ^ /•.. i s.2
(7)
We note that the efficiency is a function of the product of a term
depending on the fuel and mixture ratio, and a term depending on the
turbulence level in the combustion region.
Further considerations of this model, discussed in Reference 24 ,
justify a proportionality of the peak frequency of the roar spectrum
(see Figure C-14) to the chemically limited reaction rate per unit volume
of the combustible mixture.
General Conclusion from Combustion Roar Theory. Several con-
clusions may be drawn from the above theory. These will be applied to
thrust controlled flames. For buoyancy-controlled flame, the intensity
of turbulence assumption that is made in this discussion would have to be
modified. This would result in slightly altered conclusions.
Change in Firing Rate of Single Burner. For a single burner with
a fixed fuel and fuel/air ratio, we can assume that u'?s U « Q where U
is a typical flow velocity and Q is the heat release rate. If W is the
* 3
noise power output, then W « Q and PWL (decibels) « 30 log Q.
Effect of Change in Burner Size. If a homologous series of
burners is considered, each firing at its rated capacity and pressure drop,
"* ~~ ~~~
SPL (dB) = PWL (db) - 20 log R(feet) - 0.5 where SPL is the sound
pressure level at a point R feet from the source, assuming spherical
expansion of the sound from the source.
-------
C-40
then (neglecting Reynolds number effects) u'/c is a constant. It follows
that the efficiency of conversion is a constant. Thus, W « Q and
PWL w 10 log Q.
It also follows that a change in the number of burners for a
given application, if from the same series and all fired at rated capacity,
will not change the combustion roar output. Figure C-15 shows a corre-
lation of three sizes of premix burners, singly and in pairs, on this
basis.
Effect of Intensity of Combustion. The intensity of combustion,
I, is proportional to U/L where L is the modular size associated with a
particular combustor. With some manipulation, one can determine that
W « Q5'3 I , or PWL « 16.7 log Q + 13.3 log I. Thus, if the intensity
of combustion is maintained throughout a series of designs, say, by
increasing the number of modules and maintaining the characteristic
velocity, the noise output will increase with somewhat less than the
square of the combustion energy input. It might be noted some series of
burner designs are constructed on this basis. This could explain the
/• 2 c\ / 26^
results reported by Bitterlich and Seebold
Effect of Flame Size. The effect of flame size is not well
understood and may involve more than one phenomena. First of all, there is
an overall effect from the change in intensity, if the firing rate is
held constant. But second, there is a change in roar spectrum shape; as
the flame gets larger a gradual cut-off on the high frequencies moves to
(22)
longer wavelength or lower frequencies. Because of the response of
the human ear, the effect can become quite pronounced for large flames.
This could make the use of a single large burner preferable to two smaller
burners.
-------
C-41
110
o>
JO
O
0)
Q
B
i_
OJ
O
90
Slope = 0.83:1
4 6 8 10
(AP/P)xoir(Btu/hr)xlO~2
20
40
FIGURE C-15.
OVERALL DECIBEL LEVEL (SPL REF. 20 MICRONEWTONS/METER )
AT 3 FEET FROM PREMIX BURNER(S) AS A PRODUCT OF PRESSURE
DROP ACRuSS BURNER AND BTU/HR BASED ON AVAILABLE AIR.
DIFFERENT SYMBOLS INDICATE DIFFERENT BURNER SIZES.
BURNERS OPERATING IN PAIRS ARE INDICATED BY TWO
SYMBOLS AT SAME POINT.
-------
C-42
Effect of Fuel Composition. In a case of a preraixed flame or a
nozzle mix burner in which all combustion takes place within the burner,
the expansion ratio and the burning velocity are known. One therefore
expects that if the overall flow rate is held constant, the efficiency
of noise output will peak near stoichiometric and fall off on both sides.
Since the heat release rate is limited on the fuel-rich side by the amount
of air present, and on the excess air side by the amount of fuel present,
a further peaking will be found in plotting dB output against air/fuel
ratio. Figure C-16 shows the total effect.
For1 nozzle mix and diffusion flames, as compared to premixed
flames, one expects the burning to take place over a wide range of mixture
ratios and to involve more local re.circulation of hot products, thus.
decreasing the effective value of E. As a result of this effect and of
change in the effective value of burning velocity, the noise output should
be reduced and the noise spectrum flattened and shifted to lower fre-
quencies .
Effect of Fuel Type. Most hydrocarbon fuels do not vary greatly
in burning velocity at stoichiometric, or in expansion ratio. However,
for high percentages of, ethylene, hydrogen, and some other fuels with
high burning velocity, the efficiency of noise output is seen from
Equation (7 ) to be increased accordingly.
Effect of Recirculated Products or Steam. Since recirculated
products have ordinarily lost at least some, and usually much of their
thermal energy above ambient, before they are used to dilute the fresh
mixture, the burning velocity and the value of the expansion ratio
will both be reduced. As a result, from Equation (7 ), the efficiency of
noise output will be reduced.
-------
C-43
100
o
0)
Q_
O
0)
* o
«g
-O 3
90
QU_
80
8 10
Air/ Fuel Ratio
30
FIGURE C-16.
DECIBEL LEVEL AT PEAK FREQUENCY OF A NOZZLE-
MIX BURNER, WITH DATA AT CONSTANT NATURAL
GAS FLOW RATE (<>) , AND CONSTANT AIR FLOW
RATE (0), CORRECTED TO CONSTANT TOTAL FLOW
RATE
-------
C-44
Effect of Environment. While the basic noise spectrum is shaped
much like a jet noise spectrum, components of the spectrum are amplified
at the natural frequencies of the surrounding environment. For instance,
a burner tile around the flame can amplify the combustion roar at the
natural axial modes of the tile, as in Figure C-17 . The same holds true
for the acoustic modes of the furnace.
Another environmental effect is that of noise from valves or
orifices in the fuel or air supply lines. These noises are amplified by
the flame, although at the same time the combustion roar spectrum may
decrease somewhat.
Application of Combustion Roar Theory. It is not convenient or
even possible in most instances to specify the intensity of turbulence
in a burner. However, for a series of similar burners one might assume
2 2
that (u'/c) pa (U/c) pa Ap/p, where AP is the pressure drop across the air
inlet into the burner (or fuel and air if premixed), and P is the absolute
pressure. In case the air is inspirated by fuel jets, the pressure drop
across the fuel jets divided by the square of the air to fuel ratio can be
used. The data for the efficiency of noise output of a series of similar
burners are expected to vary with (AP/P) where a is close to unity.
Figure c-18 shows data presented on this basis. It is seen
that the correlation is quite acceptable for specifying noise output.
Often, the sound power level (SPL) in decibels is preferred.
ry
In this case, the SPL can be plotted against log (Ap/p) Q. Within the
accuracy of the data, log (AP/P)Q is often equally acceptable even if not
absolutely correct when ot is other than unity. Figure C-15 shows data
presented on this basis.
-------
100
Burner-tile respons
Typicol combustion-roar
spectrum
o
I
60
50
100
250
500
Frequency, Hz
1000
2500
50OO
FIGURE C-17.
EFFECT OF OTHER NOISE SOURCES ON TYPICAL COMBUSTION-
ROAR SPECTRUM FOR A NOZZLE-MIX BURNER
-------
C-46
20
^ 10
O
1 8
o
c
0)
o 6
+ 1.5
8 10
(AP/P)xl03
20
40
60
FIGURE 018.
THE RATIO OF EFFICIENCY OF CONVERSION OF
CHEMICAL TO ACOUSTIC ENERGY AS A FUNCTION
OF DIMENSIONED PRESSURE DROP
-------
C-47
Suppression of Combustion Roar. There are several different
possibilities for suppressing combustion roar. One of the most obvious,
and often very effective, is the installation of mufflers in the inlet
and/or exhaust lines, depending on where the prominent noise emanates.
Figure C-19 is a sketch of the installation of an inlet muffler on a gas
burner for use in banks in oil refineries. Such mufflers quite commonly
reduce the dB level by 25. Multiple Helmholtz resonators, quarter-wave
tubes, and similar devices can also be used to suppress the combustion
roar, especially in cases where there has been amplification of the roar
at the natural frequencies of the burner tile or the furnace.
High frequencies imposed on the flame are known to decrease the
combustion roar amplitude. Thus Briffa and Fursey^7^ have suggested
using ultrasonic frequencies to decrease the combustion roar.
Since the combustion roar is known to increase about with the
square of the intensity of turbulence, the turbulence level should be
reduced as far as possible while still maintaining a satisfactory flame
from other points of .view.
Unstable Combustion Noise
As noted above there are several types of combustion generated
noise that do not fall conveniently into the first two classes discussed.
In many instances, these types have not been studied carefully from the
noise standpoint or alternatively, it has not been realized that they fall
into a separate class. One of these types of combustion-generated noise
is that which is related to unstable combustion.
Oftimes flames are unstable and tend to blow off or flash back,
as has been discussed previously. However, the flame may not be sufficiently
unstable that it is an undesirable flame under normal operating conditions;
in fact, visual inspection of the flame may show it satisfactory.
-------
C-48
Preferred Design:
Volume: > 15 cu ft
Acoustic material density: 6lb/cuft
thickness: > 4 in.
Retainer: expanded metal screen
Heavy plate: >O.I34 in. sound-deadening undercoat
•';•;
•V
i
ID DO!
inr
Til
xl
V
/
>
/
/
/
s
'..';•'
FIGURE C-19. TYPICAL INSTALLATION OF AN INLET
MUFFLER ON A GAS BURNER FOR USE IN
AN OIL REFINERY
-------
C-49
Alternatively, as the flame changes toward, say, blow-off there will be a
change in flow pattern and a tendency to reestablish the flame, or a local
region thereof, at the expense of some other region. Without a feedback
mechanism present in either of these instances, the frequency of such a
phenomena is highly erratic. However, the large gross movements of the
turbulent flame can produce noise from the moving front of ignition of
local combustion cells. Increases of 10 dB or more are hot at all
unusual when the mixture ratio or flow rate is changed sufficiently to
put a flame into a metastable or unstable regime.
Observations of Smith and Kilham. Smith and Kilham
reported data on this particular phenomena in 1963. They studied a
burner consisting of'a long tube with a small pilot flame around the exit.
The combustible mixture was 4 percent propane. The flow rate was varied
by a factor of about 5 to, 1. At each flow rate of the combustible mixture,
the supply of hydrogen to the annular hydrogen pilot was varied. As the
input to the piloting annulus was decreased the flame suddenly became
unstable and the noise level started to increase. With further reduction
in the hydrogen flow rate the noise level reached a peak, and then started
to decrease as the flame became very tenuous and combustion became in-
complete. In these experiments the sound power output increased with
about the 5/3 power of the firing rate over a range of 5 to 1. Through-
out this range the maximum increase in sound pressure level observed when
the hydrogen flow was dropped was about 3 dB. That is, the efficiency of
chemical energy conversion to noise increased by a factor of 2 when the
flame went into this unstable region, before the flame became too tenuous
to be considered as a satisfactorily burning combustion system. It might
be noted that this 5/3 power was observed by Giammar and Putnam^ ' i-
small burners.when buoyancy effects were important.
in
-------
C-50
(29)
Observations of Westberg. Westbergv reported the noise out-
put of several industrial burners in industrial and laboratory surround-
ings. In a set of data on a premixed, continuous-flame, line-type burner,
an observed jump in the sound pressure level with increase in firing rate
near the rated firing rate can be interpreted as resulting from a flame
moving into a partially unstable situation. This jump was about 8 dB.
Assuming that this is the correct interpretation of these data, a considera-
tion of the spectrum data before and after the jump shows little change in
shape. This would indicate that the overall sound generating phenomena
were the same, but the change of the flame into an unstable operating
condition resulted in an effective increase in the turbulence level in
the combustion region.
Observations of Fricker. Fricker * ' discusses the noise
produced by a swirl burner with natural gas injected axially at 200 m /h.
Figure C-20 shows the two types of flames that result. In Type II flame,
the central fuel jet is stopped by the recirculation zone and spreads out-
ward to give an intense blue flame. In Type I flame, the gas jet pene-
trates the recirculation zone with subsequent burning, but leaves enough
behind in the reverse flow region to burn and stabilize the flame.
Because the Type II flame was noisy and the Type I was quiet, Fricker
hypothesized that
(fuel + heat) + combustion air — quiet mixing controlled ignition
(fuel + combustion air) + heat - noisy "explosion" ignition.
Figure C-2l shows the results of a more detailed study of the
effect of the ratio of gas velocity to air velocity, and the quarl angle.
Two regions are delineated, where Type I and Type II flames exist. When
the gas velocity is near the critical value for penetration, the flame is
unstable and the noise level is up to 5 dB above that with a stable flame.
Changing the fuel injection from a single axial jet to a multihole divergent
set of jets was found to quiet the flame when in this unstable region.
For Type II stable flames, the noise level was found to increase linearly
from 106 to 114 dB as the swirl number increased from zero to 1.7.
* Dykama indicates this instability between these two types possibly
was the cause of unsatisfactory combustion in one furnace installation,
but burner modification solved the problem.
-------
Flame Forms
TYPE I
Flow Patterns
n
i
TYPE
FIGURE C-20. FLOW PATTERNS AND FLAME FORMS OF GAS FLAME WITH SWIRLING AIR FLOW
-------
C-52
o
c>
>
(/)
o
O
Air velocity =50 m/s
S = l-7
quarl L/D = 1
_ (a = 0°:Gc
G > Gc! Type I flames
M4dB \ IKdB
\\\\\
= GC! Fuctuating flames
Typell flames
Burner Quarl Angle (a)
FIGURE C-21. THE DEPENDENCE OF FLAME TYPE AND FLAME NOISE ON
BURNER QUARL ANGLE FOR FLAME WITH SWIRLING AIR
FLOW AND AXIAL FUEL INJECTION
!07dB
-------
C-53
This latter value corresponds to the swirl of the burner studied by
Beer, et al.
(32)
Other Observations. Nesbittv ' indicated that the largest
source of combustion noise in industrial combustors is related to the
incipient flame instability problem in combustion systems. Unpublished
data obtained by the authors on a 4,000,000 Btu/hr nozzle-mix burner
indicated about a 10 dB increase in noise level when the unstable
region of combustion was entered. It should be noted that from an
appearance standpoint, and from a performance standpoint relative to
heat output, the burner was still operating satisfactorily.
Data are not yet available to permit a prediction of the increase
in decibel level that can be expected when a burner goes into the zone of
metastable or unstable operation. The data available indicate anything
from a three to a ten decibel increase can be expected. In the case of
the observed 3 decibel increase, a larger increase would possibly have
occurred if the flame had continued to burn satisfactorily. On the other
hand, the little data that are available indicate that the basic phenomena
are still one of combustion roar. The change comes about from an
increase in the effective level of turbulence at the point of burning.
Thus, one would expect that the basic criterion in reducing the noise in
cases where the partially unstable burning has to be accepted would be the
same criterion of noise reduction one would use for reducing combustion
roar
Combustion Amplification of
Periodic Flow Phenomena
There are several variations on the process of noise amplifi-
cation of periodic flow phenomena by the flame. Because of the lack of
understanding of the details of this amplification process, these several
different classes have been grouped together. However, the differences
will become apparent as various examples are discussed. At present it
seems possible to group these examples into the following three subclasses
-------
C-54
(a) periodic flow phenomena resulting from an input of a high frequency
noise to the combustion system, (b) input of a periodic phenomena by a
Strouhal-type vortex shedding in the flow system, upstream of or at the
location of the combustion process, and (c) periodic flow phenomena
resulting from the swirl flow in swirl type combustors.
(33)
External Noise Source. Briffa and Fursey examined the
possibility of subjecting a flame to an ultrasonic noise source. He
observed that while the ultrasonic noise was amplified by the flame, this
amplified noise was outside of the range of hearing. At the same time
the combustion roar of the flame decreased in amplitude the order of 2 or
3 dB. It was not clear from the data whether or not the overall noise
level produced by the flame was constant or decreased.
'(22)
Giammar and Putnam observed that the imposition of jet
noise in the flow system by insertion of a length of restrictive pipe in
the supply line produced a decrease in the amplitude of the combustion
roar spectrum of the same order of magnitude as Briffa and Fursey had
observed, while at the same time the jet noise itself was amplified by
the flame by as much as 25 dB at its characteristic frequency. In this
case the jet noise was within the audible range, and this made the burner
much more noisy in the audible range. Examination of data on diffusion
flames wherein the fuel was supplied by a multiple set of spuds showed the
same type of phenomena to be present. ' That is, the jet noise was
amplified above what it would have been without combustion, by a factor of
up to 25 dB.
It would appear that the superposition of a high frequency note
on the turbulent flame results in a change in the burning phenomena suffi-
cient to decrease the low frequency noise spectrum amplitude while ampli-
06)
fying the noise of the superimposed tone.
-------
C-55
Strouhal Related Phenomena. In small turbulent flames, it is
quite common for a periodic structure to occur in the flame with a fre-
quency spectra having a Strouhal-like characteristic. That is, the peak
frequency will have a linear functional relation with the flow velocity.
Because the combustion roar may also be present at about the same level
of intensity, and in the same frequency range, a clear-cut indication of
a vortex shedding (Strouhal-like) phenomena is not always observed.
(28)
The best known work in this area is that of Smith and Kilhan.
It is commonly assumed that they observed combustion roar, but there are
strong indications that they actually observed at the same time a
significant contribution of noise amplification of jet noise from the small
jets. While the variation of peak frequency with mixture flow velocity
that they observed was less rapid than one would expect for a simple cold
(22)
flow jet, Putnam and Giammar observed this slow variation in peak
frequency with small air jets. The frequencies observed by Smith and
Kilham give Strouhal numbers of the order of about .2, which is in the
region of the expected value. It is also important to note that, while
the authors indicated that they observed a noise power output varying
with the square of the product of flow velocity, duct diameter, and burn-
ing velocity, this conclusion is not correct.
A replot of their data of their Figure 2 in terms of sound power
level, which should be independent of microphone position for sufficiently
large distances, show that the sound power level for three different
diameters of burner, for one mixture ratio, varied with the square of the
flow rate, rather than the Reynolds number as they indicated. Their other
data were all taken at one constant position for the acoustic probe and
one constant burner diameter. Thus the data of their Figure 2 were the
only ones that could be used to show up the effect of burner diameter.
(22 )
The interesting fact is that Giammar and Putnam also observed this
sound power variation with the fourth power of the diameter for cold jets.
-------
C-56
Swirl-Burner Precession Noise. One possible source of noise in
a swirl burner is from the precessing of the vortex cores.
(37 38)
Syred and Beer ' present data from both air flow studies and
combustion studies on two swirl burners of the design shown in Figure C-22 ,
Table 2 presents the cr-itical dimensions; it is noted that there is
approximately a scale factor of five between the two. For premixed
flames, the mixture of. fuel and air entered through the swirl vanes.
For diffusion flames, fuel was added (1) axially, (2) radially, or (3)
tangentially. The first two are obvious. In the third case, the fuel
was added through a tube on the axis of the tangential air inlet, termi-
nating at the outer shell wall with the air inlet termination.
Figure c-23 shows the flow pattern obtained from air flow experi-
ments when conditions were such that precession of the vortex occurred.
The precessing vortex core appears to lie in the boundary of the reverse
flow zone between the zero velocity and zero streamline (cf Figure C-24).
At the same time the annular eddy which forms stably at the exit at low
flow rates starts shedding and peeling off behind the passing precessing
cores. Figure C-25 shows the dimensionless frequency curves obtained in
the air flow tests on the two sizes of units.
Since the curves for the two sizes are not identical, it is
2
apparent that the parameter QD/pQ does not completely characterize the
data. Syred (private correspondence) points out two possible reasons.
First, he notes that the exact flow pattern of the fluid into the chamber
3
has considerable effect on the value of fd /Q. Second, he notes that the
correction factor he uses to bring the two curves together is equal to
n where n is the scale factor. In any case, it is clear that studies
2
are needed for other values of QD/pQ , as well as other scale sizes, and
other designs of entrance.
-------
SCHEMATIC DIAGRAM OF SWIRL BURNER
TANGENTIAL
FUEL
AXIAL
FUEL
CHANGEABLE BURNER
EXIT NOZZLE UNIT
RADIAL FUEL
TANGENTIAL
AIR
o
i
Ui
-J
FIGURE C-22. SCHEMATIC DIAGRAM OF SWIRL BURNER
-------
C-58
TABLE C-2. SWIRL BURNER DIMENSIONS
Diameter, mm
Length, mm
Number of tangential inlets
Size of tangential inlets, mm
Size of axial inlet, mm
======
Large
176
560
8
352 x 4.8
12.5
======
Small
34
100 -
8
70 x 1.02
2.0
Rodiol Section
(Exit)
FIGURE C-23. THE ISOTHERMAL FLOW STATE WITH A PRECESSING VORTEX CORE
-------
C-59
-1.0
Zero axial velocity line
I//////////J
FIGURE C-24. SPATIAL DISTRIBUTION OF STREAM FUNCTION Y
-------
O
\
to
0
Small l-5-Scole Burner
Tangential fuel entry
Axial fuel entry
Isothermal
Uncorrected for size
Small Burner - Corrected for size to large burner
• Tangential fuel entry
A Axial fuel entry
Large, Burner *^R = 1.182
Isothermal
Premixed = 2.0
Premixed <£ = 4.0
Isothermal
Axial fuel entry 4> - 75
Axial fuel entry <£= 150
Modified by
valve change
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Re x ICT5
o
i
c^
o
2.2
FIGURE C-25
DIMENSIONLESS FREQUENCY AS A FUNCTION OF REYNOLDS NUMBER FOR SWIRL
BURNERS, WHERE f = FREQUENCY, D = DIAMETER, Q = VOLUME FLOW RATE,
•ft- = INLET ANGULAR MOMENTUM. NOTE THAT Ao/p2 is 2 /n TIMES THE
CONVENTIONAL SWIRL NUMBER, 2G
-------
C-61
Syred and Beer also studied the noise produced by combustion
of premixed natural gas and air in the system, for Reynolds numbers from
45 *
4 x 10 up to about 10 , and air/fuel ratios up to 6 times stoichiometric.
A short, intense, noisy flame was produced. As shown by Figure C-26, the
frequency increased by a factor of 2 to 3; the exact value depends on the
mixture ratio, with the value increasing as the mixture ratio approaches
stoichiometric. The noise intensity was up to 20 times the level without
combustion. With town gas (50% H2) at Reynolds number of 1.4 x 10 ,
the frequency was approximately doubled but the noise amplitude appeared
to decrease somewhat.
In studies of natural gas diffusion flames with tangential fuel
injection and with axial fuel injection for stoichiometric to about
200% excess air, a 1/5 scale burner was used. The frequency with combus-
tion was about the same as for isothermal flow, but showed less variation
with Reynolds number. In a later study, for an axial fuel injection, the
frequency decreased about 307» in changing from an infinite air/fuel ratio
to 50:1. At less than 50:1, vortex breakdown occurs, while the
amplitude was decreased by about 100; this indicates a damping effect of
the diffusion flame as the source of noise. Similar suppression effects
were obtained with axial injection of town gas but not tangential;
apparently the high molecular diffusion rate of the hydrogen in the town
(37)
gas made this condition similar to the premix case. In another
paper these investigators point out that "premixed fuel and air appear
to be the only method by which the precessing vortex core may be excited;
any other mode of fuel entry damps the precessing vortex core considerably".
*
Apparently the vortex action also results in partial separation of the
premixed fuel and air, so as to produce a mixture within the combustible
range even at the high excess air values.
-------
ro
Q
4
A
O
D
O
v
1.47
2.0
2.5
3.0
4.0
6.0
Isotherm
Q2
= 1.182
Blow-off region
O
I
°0.0
0.2
0.4
0.6
R
10
0.8
-5
1.0
1.2
1.4
FIGURE C-26.
THE EFFECT OF REYNOLDS NUMBER ON THE FREQUENCY
PARAMETER FOR PREMIXED COMBUSTION AND ISO-
THERMAL STATES
-------
C-63
(43)
Gupta, Syred, and Beer reported data on the sound pressure
level and amplitude-frequency spectra using the smaller natural gas
version of the burner shown in Figure C-22.
The sound spectra, such as in Figure C-27, showed no sharp peaks
below the approximately 5000 Hz of the jet noise, but a high value in
(22 )
about 200-500 Hz range reported by Giammar and Putnam. The precess-
ing frequency noise observed with isothermal flow was either masked or
suppressed by the near-stoichiometric combustion of this diffusion flame
as contrasted to the suppression observed with weaker mixtures.
The sound pressure level measurements as a function of excess air
from stoichiometric to 20 percent excess air showed little effect up to 1/4
fuel injected radially, and then decreasing amplitude with increased
excess air up to about 85 percent radial injection, where stability diffi-
culties entered. For stoichiometric, the 100 percent axial injection was
somewhat less noisy than the 85 percent radial, while for 10 percent
excess air, the opposite was true. Most interestingly, at about 55 percent
radial injection, a dip in the noise output of 1 to 3 dB occurred.
Figure C-28shows that the use of a convergent-divergent nozzle
increases the noise level over the minimum by up to 4 dB. At the higher
flow rates, the noise levels off and, according to the investigators, is
principally jet noise. It is probable that the combustion region has moved
outward to a region of lower turbulence intensity, leading to a lower
relative noise level.
The fractional efficiency of noise production, as indicated by
- 8
the straight diagonals, is of the order of 10 . This is of the order of
efficiencies found for low firing rates. The parabolic curve indicates
the change of efficiency with firing rate expected on the basis of simple
theory, which assumes that the turbulence level in the combustion region
is a constant fraction of the flow velocity. If the pressure drop across
-------
C-64
80
CM
'0
OJ
**—
or
S
a.
c/j
70
60
30
10
Combustion (axial; radial
fuel = 45/55)
100 1000
Frequency, Hz
10,000
FIGURE C-27. AMPLITUDE-FREQUENCY SPECTRUM FOR MAXIMUM
NOISE OUTPUT AT 1.65 x 10'3 m^/s AIR
-------
C-65
Axial fuel
(convergent divergent
fuel)
Axial fuel
(straight exit)
Axial and radial
fuel (ratio 45 = 55)
All stoichiometric
mixture ratio
77 =0.5 x 10
100
200
Air Flow, liters/minute
FIGURE C-28. ACOUSTIC POWER OUTPUT OF A SWIRL
BURNER AS A FUNCTION OF FLOW RATE
-------
C-66
the burner is assumed to scale from the larger swirl burner discussed
above, this parabolic is about 1/4 the mean value obtained by Giammar
( *) / \
and Putnam for premix natural gas flame retention burners (data extra-
polated to lower firing rates). A similar comparison based on data from
two impinging fuel jets at an optimum spacing for mixing shows good agree-
ment.
(41)
Syred, Hanby, and Gupta added a resonance tube of ^0 mm
diameter to the larger natural gas swirl burner. The fuel was injected
either axially or tangentially. Because of the blockage, the resonance
tube acted as a quarter-wave tube. It was found that there was amplifi-
cation of the precessing frequency when the resonant frequency and precess-
ing frequency coincided. However, there were several complicating factors
in the study. The precessing frequency, for the axial fuel entry, varied
from 140 Hz at the mixture ratio relative to stoichiometric of 1.0, to
peaks'of 200 Hz at 1.6 and 2.6, and a valley of 170 Hz at 1.8. For
tangential fuel entry, the frequency varies from 120 Hz at 1.0 to 160 Hz
at 2.3, with fluctuations up to + 20 Hz, with peaks at 1.0, 1.6, and 2.0.
The resonant frequency of the system falls off with increasing tube length,
but not at a uniform rate, and is affected by both mixture ratio and
mode of fuel injection. Finally, the "Q" of the system is affected by
mixture ratio and mode of fuel injection. As a result, there is a major
amplified peak at a resonance tube length of 1000 mm and a minor peak at
1400 mm for axial injection, and peaks at 900, 1300, and 1600 (one case)
mm for tangential fuel injection, with the major peak at 1300 and 1600 mm.
The intensity at a specific measuring point within the combustion system
reached twice the amplitude in the case of axial fuel entry as in the case
of the tangential fuel entry, but data were not sufficient to obtain a
value of efficiency of noise production. It should also be noted that,
because of poor blow-off limits of flames with tangential fuel entry, the
axial system is preferred.
There does not seem to be any feedback in the system, whereby
the resonance amplitude tends to shift the precessing frequency or sharpen
it. Rather, the amplification phenomenon appears similar to that dis-
(22)
cussed by Giammar and Putnam for con, istion rear from a burner in a
tile.
-------
C-67
REFERENCES FOR PART C
(1) "State of the Art for Controlling NOX Emissions, Part I, Utility
Boiler", Catalytic, Inc., September, 1972.
(2) "Lowes, T. M., Bartelds, H., Heap, M. P., Walmsley, R., "Burner
Design Optimization for the Control of NOx Emissions from Boilers
and Furnaces", IFRF, Doc. Nr. K20/a-68, September, 1973.
(3) Putnam, A. A., and Smith, L. R., "On the Extinction Limit of Laminar
Flame", 4th Symp. (International) on Combustion, 1953, pp 708-714,
Figure 8.
(4) Grumer, J., Harris, M. E., Rowe, V. R., "Fundamental Flash-Back,
'Blow-Off, and Yellow-Tip Limits of Fuel Gas-Air Mixtures", Bureau
of Mines, RI 5225, 1956.
(5)' Spalding, D. B., and Tall, B. S., "Flame Stabilization in High
Velocity Gas Streams and the Effect of Heat Losses at Low Pressure",
The Aeronatucial Quarterly, J5, 1954, pp 195-217.
(6) Fristrora, M. M., and Westenberg, A. A., Flame Structure, McGraw-Hill,
1965.
(7) Beer, J. M., and Chigier, N. A., Combustion Aerodynamics, Applied
Science Publishers, Ltd., London, 1972.
(8) Scholte, T. G., and Vaags, P. B., "The Burning Velocity of Hydrogen-
Air Mixtures and Mixtures of Some Hydrocarbons With Air", Combustion
and Flame, 3, 1959, pp 495-501.
(9) Scholte, T. G., and Vaags, P. B., "Burning Velocity of Mixtures of
Hydrogen, Carbon Monoxide, and Methane With Air", Combustion and
Flame, 3, 1959, pp 511-524.
(10) Karr, C., and Putnam, A. A., "Influence of Recirculated Combustion
Products on Burning Velocity", Trans. ASHRAE, 69. 1963, pp 72-78,
(also ASHRAE J., Sept, 1962, pp 43-48, 70)„
(11) Brokaw, R. S., and Gerstein, M., "Correlation of Burning Velocity,
Quenching Distance, and Minimum Ignition Energies for Hydrocarbon-
Oxygen-Nitrogen Systems", 6th Symposium (International) on Combustion
Reinhold, 1957, pp 66-74.
(12) Reed, S. B., Mineur, J., McNaughton, J. P., "The Effect on Burning
Velocity of Methane of Vitiation of Combustion Air", J. Institute
Fuel, 43, 1971, pp 149-155.
-------
C-68
(13) Dugger, Gordon L., "Effect of Initial Mixture Temperature on Flame
Speed of Methane-Air, Propane-Air, and Ethylene-Air Mixtures",
NACA Report 1061, 1952.
(14) Giammar, R. D., and Putnam, A. A., "Combustion Roar of Turbulent
Diffusion Flames", J. Eng. Power, Transactions ASME, 92, Series A,
1970, pp 159-165.
(15) Reed, S. B., and Wakefield, R. P., "Vitiation of .Combu.stion Air",
Inst. Gas Engineers Journal, 10, .1970, pp 77-96.
(16) Jost, Wo, Explosion and Combustion Processes in Gases, McGraw-Hill,
1946.
(17) Putnam, A. A., Hyatt, R. S., Rodman, C. W., "Elimination of Combus-
tion-Driven Oscillations in a Large Air Heater", ASME 67-WA/FU-2,
November, 1967.
(18) Brown, D. J., "Noise Emission and Acoustic Efficiency in .Pulsating
Combustion", Combustion Science and Technology, _3_i 197.1, pp 51-52.
(19) Putnam, A. A., Combust ion-Driven Oscillation in Industry, American
Elsevier, 1971.
(20) Markstein, G. H. (Editor), Non-Steady Flame Propagation, AGARDograph 75,
Pergamon, 1964, Chapter F, G, H.
(21) Putnam, A. A., "Combustion Noise in Industry and Its Control", Fuels
Utilization Conference Proceedings, The Cleveland State University,
October, 1972. • .
(22) Giammar, R. D., and Putnam, A. A., "Noise Generation by Turbulent
Flames", American Gas Association,. Catalog No. M00080, 1971.
(23) Bragg, S. L., "Combustion Noise", J. Inst. Fuel, .36, 1963, pp 12-16.
(24) Giammar, R. D., and Putnam, A. A., "Combustion Roar of Premix Burners,
Singly and in Pairs", Combustion and Flame, 18, 1972, pp 435-438.
(25) Bitterlich, G. M., "Some Findings on Burner Noise and Its Suppression",
presented at Symposium on Burners and Noise, 35th Mid-Year Meeting
of API Division of Refining, Houston, Texas, May 13,. 1970.
(26) Seebold, J. G., "How to Control Combustion Noise in Process Plant
Furnaces", Oil and Gas Journal, Jan. 3, 1972, pp 48-51.
(27) Briffa, F.E.J., and Fursey, R.A.E., "Reduction of Audible Flame Noise
by the Application of Ultrasonics", Nature, 214, 5083, April 1, 1967,
pp 75-76.
-------
C-69
(28) Smith, T.J.B., and Kilham, J. K., "Noise Generation by Open Turbu-
lent Flames", J. Acoustical Soc. America, ^5, 1963, pp 715-724.
(29) Westberg, F. W., "Combustion Noise Evaluation of Selected Field
and Laboratory Industrial Burners and Environments", American Gas
Laboratory Research Report No. 1358A, May, 1964.
(30) Fricker, N., "Flow and Combustion Phenomena in Swirl Stabilized Gas
and Oil Diffusion Flames", Members Conference IFRF, IJmuiden, May,
-L 17 / _L »
(31) Beer, J. M., "Recent Advances in the Technology of Furnace Flames"
J. Inst. Fuel, 45, 1972, pp 370-382. '
(32) Nesbitt, J. D., private communication.
(33) Briffa, F.E.J., and Fursey, R.A.E., "Some Aspects of the Effect of
Transverse Acoustic Fields on Flame Noise", 10th International Gas
Conference, Hamburg, West Germany, 1967.
(34) Putnam, A. A., "Flame Noise at High Firing Rates", American Gas
Association Catalog No. M30000-27, 1968.
(35) Putnam, A. A., "Flame Noise from the Combustion Zone Formed by Two
Axially Impinging Fuel Gas Jets", U. of Sheffield Fuel Society
Journal, 19, 1968, pp 8-21.
(36) Giammar, R. D., and Putnam, A. A., "Combustion Roar of Premix
Burners, Singly and In Pairs", Combustion and Flame, 18, 1972
pp 435-438. — *
(37) Syred, N., and Beer, J. M., "The Damping of Precessing Vortex Cores
by Combustion in Swirl Generators", Astronautica Acta, 17
pp 783-801, 1972. —'
(38) Syred N., and Beer, J. M., "Vortex Core Precession in High Swirl
Flows , Proceedings, 2nd J.S.M.E. Conference on Fluid Machinery
and Fluidics, Tokyo, Sept, 1972, pp 111-120.
(39) Syred, N., and Bee'r, J. M., "The Effect of Combustion Upon Pre-
cessing Vortex Cores Generated by Swirl Combustion", 14th Symposium
on Combustion, 1972, pp 537-550.
(40) Syred, N., and Bee'r, J. M., "Vortex Breakdown and Flow Stabilization
in Swirl Combustions", European Combustion Symposium, Sheffield
University, 19730
-------
C-70
(41) Syred, N., Hanby, V. I., and Gupta, A. K., "Resonant Instabilities
Generated by Swirl Burners", J. Institute Fuel, ^6, Dec., 1973,
pp 402-407.
(42) Gupta, A. K., Syred, N. , Beer, J. M. , "A Low-Noise Burner for Swirl-
Stabilized Natural Gas Flames", J. Institute Fuel, .46, March, 1973,
pp 119-123.
(43) Private communication with: B. C. Krippene, Babcock & Wilcox,
Barberton, Ohio; A. Wier, Southern California Edison, Los Angeles,
California; 0. Dykama, Aerospace Corporation, El Segundo, Calif;
R. Robinson, Combustion Engineering, Windsor, Conn; D. Cavers,
Combustion Enginnering, Windsor, Conn.
-------
C-71
TECHNICAL REPORT DATA
(Please read /iiwiiciions on //;<• reverse before completing)
I HbPOHTNO.
EPA-650/2-74-032
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Design Trends and Operating Problems in Combustion
Modification of Industrial Boilers
5. REPORT DATE
April 1674
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S) .
D. W. Locklin, H. H. Krause , A. A. Putnam,
E.L.Kropp, W.T.Reid, and M.A.Duffy
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Battelle--Columbus Laboratories
505 King Avenue
Columbus , Ohio 432^1
10. PROGRAM ELEMENT NO.
1ABOH; ROAP 21ADG-6.5
11. CONTRACT/GRANT NO.
R-802402
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
NERC-RTP, Control Systems Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The ^p^ gives results of an air pollution emissions control study to:
characterize the current field population of industrial boilers; identify trends in
boiler design; and assess operating problems associated with combustion modification.
Statistics supplied by the American Boiler Manufacturers Association were analyzed
to describe the field population and recent sales trends for firetube and watertube
industrial boilers in the range from 10 million to 500 million Btu/hr. Boiler capacity,
design type, mode of direction, primary and secondary fuels, firing method (for coal)
industrial classification, and geographic region of the boiler installation were all
considered. When combustion modifications are used to control nitrogen oxide
emissions from industrial boilers, practical operating problems may arise, namely:
fireside corrosion and deposits on boiler tubes; and flame instability, including blow-
off, flashback, combustion -driven oscillations, and combustion noise or roar. These
problems were assessed and research needs were identified in relation to such
combustion modifications as low-excess-air operation, staged combustion, and
fluegas recirculation.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Air Pollution Pulverized Fuels
'ombustion Water Tube Boilers
Boilers Fire Tube Boilers
Nitrogen Oxides Combustion Stability
""oal Distillates
Fuel Oil Residual Oils
Stoichiometry
b.lDENTIFIERS/OPEN ENDED TERMS
Air Pollution Control
Combustion Modification
Stationary Sources
Industrial Boilers
Boiler Capacity
Stoker Firing
Combustion Noise
c. COSATI Held/Group
13B,
21B,
13A
07B
21D
11H
07D
14A
2uM
JISTRIBUTION STATEMEN
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
200
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
Form 2220-1 (9-73)
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