vxEPA
                                 United States
                                 Environmental Protection
                                 Agency
                                 Industrial Environmental Research
                                 Laboratory
                                 Research Triangle Park NC 27711
                                 Research and Development
                                 EPA-600/S7-81 -169  August 1982
Project Summary
                                 Emissions from  Refinery
                                 Process Heaters  Equipped with
                                 Low-NOx Burners
                                 R. J. Tidona, H. J. Buening, and J. R. Hart
                                   This report summarizes results of an
                                 investigation of the performance of
                                 commercial Iow-N0x burners in refin-
                                 ery process heaters.  Refineries in
                                 Southern and Central California were
                                 surveyed to determine the number of
                                 low-NOx burner installations existing
                                 or planned. Ten process heaters, equip-
                                 ped with low- N Ox burners, were tested
                                 to measure gaseous emissions, partic-
                                 ulates, and efficiences  over a normal
                                 range of operating conditions. The as-
                                 found NOX emission increased from
                                 58 to 245 ng/J as the fuel-bound
                                 nitrogen increased from 0 to 0.81
                                 percent. The NOX concentrations were
                                 strongly influenced by excess air levels
                                 in most cases. Reducing excess air to
                                 about 3-4 percent reduced NOxto 34-
                                 200 ng/J, depending on fuel nitrogen.
                                 Comparisons of present emissions
                                 data with past field test  data for
                                 refinery heaters equipped with stan-
                                 dard burners showed that for mechan-
                                 ical-draft gas-fired heaters, low-NOx
                                 burners may reduce the NOX emission
                                 factor by 32-77 percent below the
                                 mean emission factor for  standard
                                 burners. Three heaters (one firing gas,
                                 another firing distillate oil, and the
                                 third firing residual oil)  were selected
                                 as suitable candidates for 30-day
                                 continuous monitoring of gaseous
                                 emissions.
                                   This Project Summary was devel-
                                 oped by EPA's Industrial Environmen-
                                 tal Research Laboratory, Research
                                 Triangle Park, NC, to announce key
                                 findings of the research project that is
                                 fully documented in a separate report
                                 of the same title (see Project Report
                                 ordering information at back).

                                 Introduction
                                  Approximately 6000 refinery process
                                 heaters are in operation in the United
                                 States  (Ref. 1). Of these, about 5400
                                 have natural draft burners; the remain-
                                 der have forced or balanced draft
                                 burners. Both types emit a total of about
                                 121.5 Gg/y (134,000 tons/y) of NO,,
                                 making process heaters one of the
                                 largest industrial emitters of this pollu-
                                 tant.
                                  Several field test programs have been
                                 conducted  to characterize NO* emis-
                                 sions from process heaters over a wide
                                 range of operating conditions. However,
                                 all  the previous field  test work was
                                 conducted  on heaters equipped with
                                 conventional burners. Only  recently
                                 have refinery heater burner manufac-
                                 turers begun to market low-NOx burners
                                 for  the petroleum industry, and new
                                 commercial installations are somewhat
                                 sparse.
                                  It was the purpose of this program to
                                 (1)  locate refineries  in Southern Cali-
                                 fornia which have installed or ordered
                                 low-NOx burners, (2) test  nine gas- or
                                 oil-fired process heaters in which low-
                                 NOx burners have been installed (NO,
                                 and other gaseous emissions were to be
                                 measured over a normal range of oper-
                                 ating conditions), and (3) assess the
                                 potential for long term (30-day) tests of

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the heaters with the  goal of finding
three suitable sites—one firing gas, a
second firing distillate oil, and the third
firing residual oil.
  Southern California was selected for
the heater survey because of its strict
NOx emission regulations; hence, a high
likelihood of finding installations with
low-NOx burners. Results of the survey
are summarized in Table 1. At least 29
heaters were found with low-NOx
burners installed or planned for instal-
lation. Heaters which were tested in this
program were assigned the site num-
bers shown in Table  1.
  Results of the tests conducted at these
10 sites are reported here. (Site 10 was
added to the required  nine because it
was near Sites  6 through 9 and the
refinery was willing to allow it to be
tested.)
Summary of Program Results
and Comparison with Past
Results
  This program required that baseline
tests be  conducted for  nine  refinery
process heaters equipped with low-NOx
burners. Tests were completed on 10
process heaters, since one extra could
be tested for minimal additional cost.
  At each  test site, the gaseous emis-
sions and  stack gas temperature were
measured. Samples of fuel were taken
and submitted to an independent labora-
tory for analysis. Unit operational data
such as flow rate, pressure, and tem-
perature were recorded  periodically.
After testing the unit  in the as-found
condition, burner registers and/or stack
dampers were adjusted  to determine
the effect of excess oxygen  on unit
operation, gaseous  emissions, and
heater  efficiency.
  The  heaters tested included four
natural draft and six mechanical draft
units firing gas, distillate, and  residual
oils. Four of the mechanical draft units
had preheated combustion air.
Emission Test Methods and
Instrumentation
  All emission measurement instru-
mentation was carried in a 2.4 x 12.8 m
(8 x 42 ft) mobile laboratory trailer. Thi
trailer was used at all test sites. Gaseou
species were measured with analyzer
in the  trailer. The emission measure
ment instrumentation used  is listed ii
Table 2.

Results
  Figure 1  shows NOx emissions as i
function of stack oxygen for the  11
process heaters tested. These data shov
that for all heaters, lowering the oxygei
resulted in lower N0» emissions. Th<
gas-fired heaters had lower NO, emis
sions than did the distillate-oil-firei
heater, and the residual-oil-fired heater:
had the highest NOx emissions. Thi
gas-fired heaters with combustion  ai
preheat had higher NO, emissions thai
gas-fired heaters with ambient combus
tion air. The points at which significan
CO emissions or visible smoke occurrei
are marked in the figure as "CO limits.'
  Gas-fired heaters with ambient com
bustion air showed  NOx emissions a<
40-50  ng/J (80-100 ppm at 3 percent
 Table 1.    Heater Low NOK Burner Test Site Survey
Location
A
B
C
D
E

F
G/i

G/2
H
1
J/1
J/2
K
L/1
L/2
M
N
0/1
O/2
P
Site
No.
2
-
-
-
_

-
6, 7,
8,9
10
-
-
-
-
7
4
3
5
-
-
-
-
Air
Quality
Control
Region
31
31
24
24
24

31
30

30
24
31
24
24
24
31
31
31
24
30
30
31
No.
Heaters
1
1
-
-
1

11
4

1
1
1
1
1
1
1
1
1
-
1
1
-
Heat Input Rate
106
MW Btu/Hr
4.7
16.4
-
-
7.5

-
93.8°

8.8
7.7
10.3
-
-
6.1-6.7
6.7
11.7
11.7
-
21.4
6.4
-
~ 16
56
-
-
25.7

-
320

30
26.4
35
-
-
21-23
22.9
39.9
40
-
73
22
-
Burners
1
8
-
-
4

-
32

1
8
3
-
-
3
3
12
10
-
-
-
-
Operational
Yes
Yes
-
-
Dec. 8O-
Jan. 81
-
Sept. 80

Sept. 80
Jan. 81
March 81
Jan. 81
Jan. 81
Yes
Yes
Yes
Yes
-
Yes
Yes
-
Fuel
LO-S resid
6 Gas, 2 Oil
-
-
Gas

-
Gas

Gas
-
#6 Oil
Gas
Gas
Gas
#5 Oil, gas
#5 Oil, gas
#£+/?G
-
Gas
Gas
-
Comments
Natural Draft
Old heater; leaks above firebox


Natural Draft


Preheat, Balanced Draft

Ambient, Forced Draft

Natural Draft
Natural Draft
Natural Draft
Forced Draft
Natural Draft
Natural Draft
Natural Draft

Natural Draft
Natural Draft

 aTotal for four heaters.

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 02, dry*) in the as-found condition. By
 lowering the excess oxygen to a CO limit
 or to the minimum acceptable condition
 as determined by the plant, NO* emis-
 sions were reduced to about 25 ng/J
 (50 ppm). Heaters with preheated com-
 bustion air showed as-found NO* emis-
 sions as 58-76 ng/J (115-150 ppm).
   Lowering excess oxygen  resulted in
 NO, reduction to 25-43 ng/J (50-85
 ppm).
  As-found NO emissions from a natural-
 draft  distillate-oil-fired  process heater
 were 92-117 ng/J (168-212 ppm) and
 were reduced to approximately 58 ng/J
 (105 ppm) by lowering excess air to the
 single burner.
   Emissions in the as-found condition
 were considerably higher for the three
 units firing residual oil. All were natural
 draft  units, and two were found to be
 emitting 207-281 ng/J (370-500 ppm)
 of NO. The unit at Site 5 fired 15-20
 percent  refinery gas simultaneously
 with residual oil. This unit was found to be
 emitting 194-205 ng/J (350-370 ppm)
 of NO and was  the  only  unit firing
 residual oil which showed a significant
 tendency toward reduced  emissions
 when excess air levels were lowered. At
 reduced  excess air settings,  this  unit
 produced about 166 ng/J (300 ppm) of
 NO.
  Table 3  is  a  summary of  gaseous
emissions and efficiency for each  site
tested. Emissions at as-found conditions
and at optimum low-NO* conditions (i.e.,
lowest NOx emission without adverse
effects on flame stability or unit effi-
ciency) are compared in this table. At
most sites, significant reductions in NO*
emission below as-found levels could
be achieved along with small increases
or, at worst, no change, in efficiency.
With respect to flame stability, product
flows and temperatures, and emissions
of CO and unburned hydrocarbons, unit
operations at the optimum Iow-N0x
conditions  were  generally unchanged
from the as-found conditions.
  Figure 2 is a plot of the effect of fuel-
bound nitrogen  content on the NO,
emission factor. The three circles plotted
in this figure represent data from the
oil-fired units tested. Site 2 burned 100
percent No. 2 oil; Sites 3 and 4, No. 6 oil
(both units burned fuel having the same
composition);  Site 5,  a combination of
80 percent  No. 6 oil (by heat input rate)
and 20 percent refinery gas. The "zero
*AII emission concentrations given as ppm are
 corrected to 3 percent 02, dry basis.
Table 2.     Emission Measurement Instrumentation

Species            Manufacturer            Measurement Method Model No,
Hydrocarbon
Carbon Monoxide
Oxygen
Carbon Dioxide
Nitrogen Oxides
Particulates
Sulfur Dioxide
Beckman Instruments
Beckman Instruments
Teledyne
Beckman Instruments
Thermo Electron Co.
Joy Manufacturing Co.
DuPont Instruments
Flame lonization
IR Spectrometer
Polarographic
IR Spectrometer
Chemiluminescent
EPA Method 5 Train
UV Spectrometer
402
865
326A
864
10A
EPA
400
   500
   400
£300
I

d
^ 200
   100
                                                                I-Site 4
                                                            'Residual Oil
                                                            Natural Draft
                                      Site 3
                                      Residual Oil
                                      Natural Draft
                                            -Site 5
                             fS          Residual Oil/RG
                          xv/'               Natural Draft
      0


Figure 1.
                         468
                             Stack Oxygen, % Dry
 Site 2
 Distillate Oil
 Natural Draft

 Site 6-9
 Refinery Gas
 Balanced Draft

 Site 10
 Refinery Gas
 Forced Draft

 Site 1
 NG/RG
 Forced Draft
                                             RG = Refinery Gas
                                             NG = Natural Gas
                                             — = Denotes as-found cond.
10
12
                  14
            NOX emissions as a function of stack oxygen for Iow-N0x burners in
            process heaters.

                                       3

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Table 3.     Optimum Low-N0x and As-Found Gaseous Emissions and Efficiencies at 10 Heaters Equipped withLow-NOxBurners

                                             As-Found                         Optimum Low-N0x


Site
1
2
3
4
5
6
7
8
9
10

Heater' Test Nos.
Config. (A.F.:Low-NOx)
121 1-13; 1-24
211 2/1-1e;2/1-3a
311 3-1:3-3
311 4-1:4-4
411 5-3:5-6
132 6/5-3:6/5-1
132 7/1-1:7/2-2
132 8/1-1:8/1-3
132 9/1-1:9/1-3
121 10/1-1; 10/1-4
3Heater configuration designations







1st Digit
Fuel Burned
1 = gas
2 = dist. oil
3 = residual oil
4 = combined oil
&gas

NO
(ng/J)
39.0
92.4
222.0
268.0
194.0
57.9
65.8
74.9
60.2
51.6
are:








NO 02
(ppm) (%)
77 6.2
168 5. 1
396 5.2
477 8. 1
352 7.7
114 4.8
130 5.3
148 7.7
119 8.4
102 6.7

2nd Digit
Draft Type
1 = natural
2 = forced
3 = balanced



CO
(ppm)b
0
11
11
0
11
11
11
14
0
13

Htr.
Eff.
(%)
79.9
64.0
63.4
67.9
—
69.8
68.0
65.4
66.4
73.1


NO
(ng/J)
24.0
80.4
203.0
264.0
167.0
38.1
35.4
41.0
32.9
32.9


NO
(ppm)
48
145
361
471
303
75
70
81
65
65


02
(%)
3.0
4.0
4.3
7.1
4.4
3.5
2.3
3.8
3.3
2.8


CO
lppm)b
20
11
11
0
22
11
33
15
10
10

Htr.
Eff.
(%)
83.0
64.0
64.5
68.6
—
71.3
68.5
69.2
68.8
74.4


%NO
Reduction
38.5
13.0
8.5
1.5
13.9
34.2
46.2
45.3
45.3
36.2

3rd Digit
Air Temp.















1 =
2 =



ambient



preheater












 bDry, corrected to 3%02.
                      Fuel Bound Nitrogen, Percent by Weight


  Figure 2.    Fuel-bound nitrogen effect on NOX emission factor.
 level" or base HO* emission factor for
 gaseous fuel (containing no fuel-bound
 nitrogen) was computed by taking the
 average as-found NOX emission factor
for all  sites firing gas fuel only. This
value was 58 ng/J. The increase. A, in
emission factor for No. 2 oil was 34
ng/J (as found). For No. 6/gas fuel, the
increase over the gas fuel emission
factor was 136 ng/J (as found). For No.
6 oil, A was 187 ng/J (as found).
  Comparing these points to the curve
fit of previous laboratory data (Figure 2),
shows that in all cases the emissions
from low-NOx burners fall below that
curve. It is interesting to note that
operation at the optimum low-NOx mode
(represented by squares in Figure 2) did
not significantly alter the fuel-bound
nitrogen conversion to NO,. Also, except
for Site 2, in the as-found condition all
points plotted in Figure 2 fall within the
bounda ry curves for the laboratory data.
The effect of fuel  nitrogen  on NOx
emissions is  thus responsible for the
large differences in emissions between
gas- and oil-fired heaters  shown  in
Figure  1.
  Table 4 summarizes  NO  emissions
from the heater configurations studied
over the tested  range  of  operating
variables. The values reported in paren-
theses are ppm  corrected to 3 percent
Oz, dry. (NOz emissions were  not in-
cluded due to lack of data at some sites.
The data available  from Sites 6-10,
however, show that the NOz emissions
average only 3.6 percent of the total NO,
emissions.)

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Past Results - Comparison to
Present

  Reference 2 summarizes past NOx
emissions  data on refinery process
heaters firing oil and gas. These data are
presented in Table 5. Unfortunately, the
paucity of baseline data from oil-fired
process heaters with standard burners
makes it difficult to compare them with
present Iow-N0x burner data. Mechan-
ically drafted  heaters with  low-NOx
burners firing gas,  however, appear to
have significantly lower NO, emissions
relative to the standard burners. Tables
4 and 5  reveal that low-NO. burners
produced NO* emissions (neglecting
NOz) which were 32-77 percent less
than the average emission factor for all
standard  burners on mechanical-draft
gas-fired  heaters. The variations in NO*
                       emissions from low-NOx burners were
                       due to operating differences between
                       units (e.g., excess air level and air
                       register settings). It is important to note
                       that there is no NO, data available on
                       a ny of the units tested for operation with
                       standard burners. Thus, NO, emissions
                       with  and without low-NO, burners
                       cannot be compared  directly for any
                       heater. Because of a lack of availability,
                       no natural-draft gas-firing low-NOx
                       burners were tested; hence, they cannot
                       be compared with their standard counter-
                       parts.

                       Conclusions and
                       Recommendations for Future
                       Testing

                         The following conclusions may be
                       drawn from the study:
                                  1.  The effectiveness of low-NOx burn-
                                      ers depends on operating tech-
                                      niques, especially excess air level
                                      and air register settings.
                                  2.  By changing excess air and air
                                      register settings, NO,  emissions
                                      were reduced at every site with
                                      improved overall heater perform-
                                      ance.
                                  3.  Commercially available low-NOx
                                      burners may reduce the NO, emis-
                                      sion factor by 32-77 percent below
                                      the average emission  factor for
                                      standard burners on mechanical-
                                      draft gas-fired heaters,  depending
                                      on operating techniques.
                                  4.  Because of the lack of a good data
                                      base for oil-fired heaters with
                                      standard burners, a meaningful
                                      comparison of the performance of
                                      low-NOx oil-fired burners versus
Table 4.    NO Emissions from Process Heaters with Low-NOx Burners (1)

                                                           Fuel Type
   Unit  Type
   Gas (Ref. or NG)
Distillate Oil
Residual Oil + Gas
Residual Oil
Natural Draft
                                                                      ,"9*,
                      58_j 77 21(105-212 ppm)  167-202—.(303-366ppm)  207-284^(369-506ppm)
                              J                         J                       J
Forced Draft,       co^/c*  m? nnm>
AmbientAir    26-52-2(51-102 ppm)
Balanced Draft,  „_ -,.,n9 ,.-n , ,0    ,
AirPreheat      25-75^(50-148 ppm)
aRatio of heat input from oil to heat input from gas = 83/ J 7.
Table 5.    Mean NOX Emissions from Process Heaters with Standard Burners

              	Fuel  Type

  Unit Type        Gas (Ref. or NG)
                             Distillate Oil
                      Residual Oil + Gas
                            Residual Oil
Natural
 60.6   (25 tests)
Mechanical
 111  "J! (6tests)
      J
                       89.6 22 (5 tests)
                           138 ^-(3 tests)
                                \J
Not Reported
(Bay Area
A.P.C.D.)
70.022 (64 tests)
     \J
Not Reported
(AP-42)
  95    (8 tests)
    ng
198 — (4 tests) - oil - firing only; type unspecified
'Ratio of heat input from oil to heat input from gas — 60/40.

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     standard oit-fired burners cannot
     be made at this time.
 5.   It is  recommended  that  further
     testing include mechanical-draft
     oil-fired heaters with and without
     air preheat  and equipped  with
     low-No, burners as well as natural-
     draft gas-fired heaters  equipped
     with low-NO, burners.
 6.   Existing data  on heaters  with
     standard burners have a number
     of gaps (see Table  5); further
     testing is  required on  standard
     burners firing distillate oil  (both
     natural- and mechanical-draft)
     and standard burners firing resid-
     ual oil (natural-draft) for  a  more
     valid comparison with Iow-N0x
     burners.
 7.   Each test site in the program was
     evaluated as to its potential for a
     30-day test. Considerations  in-
     cluded:

     • Fuel type fired.
     • Ability to fire this fuel independ-
       ently of other fuels.
     • Availability of the  heater and
       the desired fuel for 30-40  days.

     Based  on  these considerations,
     the following sites are proposed
     as desirable for 30-day tests:

     • Site 1 - gas-fired, forced-draft
     • Site 2  -  distillate-oil-fired,
     natural-draft.
     • Site 4  -  residual-oil-fired,
     natural-draft.

  Although Sites  6 through  10 are all
gas-fired mechanical-draft heaters, they
are  not desirable sites for a 30-day test
because  they are still  experiencing
start-up problems; i.e., availability prob-
lems. Site 5, firing a combination of gas
and oil, does not satisfy the fuel specific-
ity requirement. Sites 3 and 4 are both
residual-oil-fired natural-draft heaters,
but Site 4 is a vertical cylindrical heater
similar to the other recommended sites.
Because of this similarity in design. Site
4 is the better choice.
  The influence of heater design on NO,
emission between the three candidate
sites will thus be minimal. Since none of
the residual oil  tests provided low NO*
levels, it may be desirable to try to find a
site which can achieve lowr NO, levels.

References
  1.  Hunter, S. C. et al., "Application of
      Advanced Combustion Modifica-
2.
tions to Industrial Process Equip-
ment:  Subscale Test  Results,"
USEPA, Industrial Environmental
Research Laboratory,  Research
Triangle Park, NC (Draft No. IERL-
RTP-1271).
Hunter, S. C. and  Cherry, S. S.,
NOjL Emission  from Petroleum
Industry Operations. API Publica-
tion No. 4311, American Petroleum
Institute, Washington, DC, October
1979.
  R. J. Tidona, H. J. Buening, andJ. R. Hart are with KVB, Inc., Irvine, CA 92714.
  Robert E. Hall is the EPA Project Officer (see below).
  The  complete report, entitled  "Emissions from Refinery Process Heaters
    Equipped with Low-NO* Burners,"(Order No. PB 82-231 838; Cost: $16.50,
    subject to change) will be available only from:
          National Technical Information Service
          5285 Port Royal Road
          Springfield, VA 22161
          Telephone: 703-487-4650
  The EPA Project Officer can be contacted at:
          Industrial Environmental Research Laboratory
          U.S. Environmental Protection Agency
          Research Triangle Park, NC 27711

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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
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