10/08/10
B&V E-15 

### PNM Response to EPA Question fr om Joe Kordzi, via email, dated September 29, 2010

Question : “PNM agreed to provide sulfuric acid mist st ack test data and any other data related to supporting the boiler outlet SO 3 emission rate of 0.011 lb/MMBtu.”

Response :

Item 1 – Sulfuric Acid Mist Stack Tests
Enclosed as Attachment 1 of this document are the results of sulfuric acid gas testing performed on San Juan Generating Station Units 1 and 3 in March 2009. These tests were conducted for informational purposes on ly and were not conducted for regulatory compliance. Additionally, Units 2 and 4 were not tested as they are considered similar to Units 1 and 3, respectively.

It should be noted that PNM is providing this information to be responsive to EPA’s questions from September 29, 2010. However, the results of this testing are invalid. As EPA reviews the enclosed testing in formation, please note the following:

 The results of testing on Unit 1 vary dram atically from Test Run No. 1 to Test
Run No. 3. Test R un No. 1 indicates H 2 SO 4 emissions of 25 lb/hr while Test Run
No. 3 indicates H 2 SO 4 emissions of 1.5 lb/hr. This is 1,500 percent difference
between the test runs.

 The testing results for Unit 3 show essentially no H 2 SO 4 emissions.

The test method used for the H 2 SO 4 testing is National Council of the Paper Industry for Air and Steam Improvement (NCASI) Method 8A (a EPA conditiona l test method 013), for ”Determination of Sulfuric Acid Vapor or Mist and Sulfur Dioxide Emissions from Kraft Recovery Furnaces”. This method (inclu ded as Attachment 2) was not specifically developed for coal fired power plants but is of ten used to measure coal fired power plants

H 2 SO 4 emissions. One key point to using this te st method is that the probe temperature is maintained above 350 °F by heating it so that none of the H 2 SO 4 in the flue gas condenses into the probe. Then the H 2 SO 4 is collected in a condenser, where the temperature (and therefor e the condensation of H 2 SO 4 ) can be controlled. The condenser
is then rinsed and the rinse water from the condenser is analyzed for H 2 SO 4 using titration. Because of this condenser, th is method is often called the “controlled condensation method”. If the probe temper ature is not maintain ed above 350 °F to revaporize the acid gas to allow the vapor to pass through the filter, H 2 SO 4 can collect on the probe and filter and not reach the condenser. This is an important point as coal fired power plants with wet scrubbers have stack gas temperatures well below 350 °F.

In Appendix 2 of the report, the field data shows that th e probe temperature was not
maintained above 350 °F for the duration of the tests. Table 1 summarizes the probe temperatures for the six test r uns conducted for Units 1 and 3.10/08/10
B&V E-15 Table 1 Emission Test Probe Temperatures

SJGS Unit 1

Test Run Probe Temperature Range

(°F)
1 350-351
2 346-348
3 349-350
SJGS Unit 3

Test Run Probe Temperature Range

(°F)
1 346-351
2 347-350
3 346-348

As can be seen by this summary, only one test run (out of six) had a temperature that met the requirements of the method. When the prob e temperature is allowed to go below the 350 °F temperature required by the method, H 2 SO 4 condenses in the probe instead of in condenser. The testing contract or indicates in the report that they rinsed the condenser but does not indicate they rins ed the probe. It a ppears unlikely that they analyzed the probe rinse solution. As a result , it is probable that all the H 2 SO 4 that condensed in the probe or was trapped on the filter was lost to the measurement results, leading to inaccurately low H 2 SO 4 emissions measurements. It is telling that only Unit 1, Test Run 1 of 3, where the probe temperature was maintained at 350 °F in accordance with the method, resulted in higher levels of H 2 SO 4 emissions than any of the other test runs
conducted.

Because of the probe temperature issues and in consistencies in the re sults, the tests were not properly performed and the resulting H 2 SO 4 emissions are not considered valid.

Item 2 – Boiler Outlet SO 3 Emissions In the Design Basis shown in Appendix A of the June 2007 BART submittal, B&V
assumed that the boiler woul d oxidize 1 percent of the SO 2 in the flue gas to SO 3 . This
forms the basis of the SO 3 emissions shown in the desi gn basis at the exit of the economizer. This assumption was used to assess the ammonium bisulfate condensation temperature entering the SCR catalyst. The ammonium bisulfate condensation temperature sets the minimum flue gas temper ature where ammonia can be injected into the flue gas for NOx control. Belo w this temperature, ammonia and SO 3 will combine to
form ammonium bisulfate and will foul the catalyst, making it unavailable for NOx reduction. This calculation is important b ecause it determines whether or not an economizer bypass will be required for low lo ad SCR operation. From this evaluation,10/08/10
B&V E-15 B&V determined that economizer bypass was not required at the San Juan Generating Station Units. Therefore, based on this asse ssment, no costs were included in the SCR estimate for an economizer bypass. The economizer outlet SO 3 emissions, based on the assumption of 1 percent oxidation rate of SO 2 to SO 3 by boiler shown in Appendix A, were not used for any other purpose in the BART analysis.

To determine the H 2 SO 4 emissions exiting the stack, B&V used the National Park Service particulate speciation method. The detail ed calculation, usi ng the NPS method, is presented in the June 2007 BART submittal in “Appendix E - Sectio n 4, NPS Speciation Spreadsheets”. A summary of these calculati ons can be found in Appendix D of the June
2007 BART submittal. The emission values in Appendix D were the values used in the visibility modeling performe d for the BART analysis.10/08/10
B&V E-15 Attachment 1

March 2009 Sulfuric Acid Mist Stack Testing Report for San Juan Generating Station10/08/10
B&V E-15 Attachment 2

NCASI Method 8A

### METHOD 8A - DETERMINATION OF SULFURIC ACID VAPOR

OR MIST AND SULFUR DIOXIDE EMISSIONS FROM

KRAFT RECOVERY FURNACES

NCASI Southern Regional Center
December 1996i

Acknowledgments

This method was prepared by Ashok K. Jain, Regional Manager at the NCASI Southern Regional
Center.

For more information about this method, contact:

Ashok K. Jain
NCASI
P. O. Box 141020 Gainesville, FL 32614-1020 (352) 377-4708, ext. 226 FAX (352) 371-6557

For information about NCASI publications, contact:

Publications Coordinator
NCASI
P. O. Box 13318 Research Triangle Park, NC 27709-3318 (919) 558-1987

National Council of the Paper Industry for Air and Stream Improvement, Inc. (NCASI). 1997. Methods Manual, Method 8 - Determination of Sulfuric Acid Vapor or Mist and Sulfur Dioxide Emissions from Kraft Recovery Furnaces , Research Triangle Park, N.C.: National Council of the Paper Industry for Air and Stream Improvement, Inc.

© 1997 by the National Council of the Paper Industry for Air and Stream Improvement, Inc.

NCASI ’s Mission To serve the forest products industry as a center of excellence for providing technical information and scientific research needed to achieve the industry ’ s environmental goals.ii

Disclaimer

The mention of trade names or commercial products does not constitute endorsement or
recommendation for use.1 December 1996



### METHOD 8 A - DETERMIN ATION OF SULFURIC ACID VAPOR
OR MIST AND SULFUR DIOXIDE EMISSIONS FROM

KRAFT RECOVERY FURNACES

1.0 Introduction

This method was developed as an alternative to E PA Method 8 for determining sulfuric acid emissions from kraft recovery furnaces. When testing recovery furnaces, E PA Method 8 is subject to significant interference from sulfates, which are present in the particulate matte r, and sulfur dioxide. The alternative method uses a quartz in-line filter to remove particulate matter from the gas stream prior to capturing sulfuric acid. The use of a controlled condensation technique eliminates the potential for interference from
sulfur dioxide.

EPA approved the use of Method 8 A in December 1996 for the determination of acid vapor or mist and sulfur dioxide emissions from kraft recovery furnaces.



### 2.0 Method Description

2.1 Principle and applicability

2.1.1 Principle
- A

gas sample is extracted from the sampling point in the recovery furnace stack. The sulfuric acid vapor or mist (including sulfur trioxide) and the sulfur dioxide are separated, and both fractions are measured separately by the
barium-thorin titration method.

2.1.2 Applicability - This method is applicable for the determination of sulfuric acid vapor or mist (including sulfur trioxide, and in the presence of other particulate matter) and sulfur dioxide emissions from kraft recovery furnaces. Tests have shown the minimum detectable limits of the method are 0.50 milligrams/cubic meter (3.1 x 10 -8 lb/ft 3 ) for sulfur trioxide. No upper limits have been established. Based on theoretical calculations, for 200 m L of 3% hydrogen peroxide solution, the upper concentration limit for sulfur dioxide in a 1.0 m 3 (35.3 ft 3 ) gas sample is about 12,500 mg/m 3 (7.7 x 10 -4 lb/ft 3 ). The upper limit can be extended by increasing the quantity of peroxide solution in the impingers.

Possible interfering agents of this method are fluorides, free ammonia, dimethyl aniline and recovery furnace salt cake.

2.2 Apparatus

2.2.1 Sampling
- A

schematic of the sampling train used in this method is shown in Figure 1. Component parts are discussed below. The schematic is similar to the EPA Method 6 (see Appendix A) train except that the impingers are not the midget type but larger as in the E PA Method 8 (see Appendix C) train. Also, theMethod 8A - Determination of Sulfuric Acid Vapor or Mist and Sulfur Dioxide Emissions

2 December 1996 impingers are preceded by a heated sampling probe, a heated quartz filter holder
and a heated H 2 SO 4 condense r

.

2.2.1.1 Probe - Quartz, straight tube approximately 12-mm inside diamete r,

with a heating element and a stainless steel jacket. A thermocouple taped on the quartz tube and insulated with glass wool allows for measurement of the probe temperature.

2.2.1.2 Sulfuric acid sampling box - Insulated box with heating elements for

filter holder and H 2 SO 4 condense r

.

(a) Filter holder - Quartz, as described in Figure 2. Filter medium
is T issuequartz filter paper with a 37-mm diameter (Pallflex Corporation). Filter holder is always maintained at temperatures >260°C (500°F) by a cylindrical heating mantle.

(b) H 2 SO 4 condenser - Modified Grahm condense r, with Type C glass frit and 200 cm of 5-mm ID glass tubing for condenser coil, as shown in Figure 3. Condenser filled with water and temperature maintained between 75 and 85°C (167 to 185°F) with a cylindrical heating mantle.

2.2.1.3 Thermocouples - Copper- constantan thermocouples to measure

temperatures at the probe end, after the filter holder and after the
H 2 SO 4 condenser (see Figure 1).

2.2.1.4 Impingers - Three, as shown in Figure 1. The first and third

impingers shall be of the Greenburg-Smith design with standard tips. The second shall be of the Greenburg-Smith design, modified by replacing the insert with an approximately 13 mm (0.5 in.) ID glass tube, having an unconstricted tip located 13 mm (0.5 in.) from the
bottom of the flask.
2.2.1.5 Metering system - Same as E PA Method 6, Sections 2.1.5 to 2.1.10,

except rotameter should be capable of measuring flow rate to within 2% of the selected flow rate of about 10,000 cc/min (and not 1,000 cc/min).

2.2.1.6 Barometer - Same as E PA Method 6, Section 2.1. 11.

2.2.1.7 Vacuum gauge and rotameter - Same as E PA Method 6, Section

2.1.12.

2.2.2 Sample Recovery - Same as E PA Method 8, Section 2.2.

2.2.3 Analysis - Same as E PA Method 8, Section 2.3.Method 8A - Determination of Sulfuric Acid Vapor or Mist and Sulfur Dioxide Emissions

3 December 1996 2.3 Reagents

2.3.1 Sampling

2.3.1.1 Filters
- T

issuequartz filter papers with a 37-mm diameter (Pallflex Corporation).

2.3.1.2 Silica Gel, Wate r , Hydrogen Peroxide, Crushed Ice - Same as
described in E PA Method 8, Section 3.1.3 to 3.1.6.

2.3.2 Sample Recovery - Water. Same as for E PA Method 8, Section 3.2.

2.3.3 Analysis

2.3.3.1 Wate r

, thorin indicato r

, barium perchlorate and sulfuric acid
standard - Same as for E PA Method 8, Section 3.3.

2.4 Procedure

2.4.1 Sampling

2.4.1.1 Preparation of collection train - Measure 100 m L of 3% hydrogen

peroxide into each of the first two impingers. Pour 100 m L of distilled deionized water into the third impinge r . Retain a portion of each reagent used as a blank solution. Assemble the train as shown in Figure 1. Adjust probe heater to maintain probe temperature above 177°C (350°F) to prevent condensation of H 2 SO 4 in the gas passing through the probe. Adjust heaters to the quartz filter and sulfuric acid condenser to the desired temperatures given in Sections 2.2.1.2 (a) and 2.2.1.2 (b). Place crushed ice around the impingers.

2.4.1.2 Leak-check procedure - Follow the procedure laid out in E PA

Method 8, Section 4.1.4.

2.4.1.3 Sample collection - Record the initial dry gas meter reading and

barometric pressure (see data sheet, Figure 4). To begin sampling, position the tip of the probe at the sampling point at right angles to direction of gas flow, connect the probe, filter and condenser assembly to the first impinge r, and start the pump. Adjust the sample flow to a constant rate of about 10.0 L/min as indicated by the rotamete r

. Maintain this constant rate ( + 10%) during the entire sampling run. Sample for a minimum of 30 minutes and take readings (dry gas mete r, temperatures at dry gas mete r, probe, filter and condenser) at least every five minutes (Figure 4). Add more ice during the run if needed. At the conclusion of each run, turn off the pump, remove probe from the stack, and record the final readings. Conduct a leak check asMethod 8A - Determination of Sulfuric Acid Vapor or Mist and Sulfur Dioxide Emissions

4 December 1996 described in Section 2.4.1.2. (This leak check is mandator y .) If the post-leakage rate exceeds the specified acceptable rate (see Section
4.1.4 of E PA Method 8), the tester shall either correct the sample volume, as specified in Section 6.3 of E PA Method 5 (see Appendix B), or shall void the run.

Drain the ice bath and, with the probe disconnected, purge the remaining part of the train by drawing clean ambient air through the system for 15 minutes at the average flow rate used for sampling (see
Section 4.1.5 of E PA Method 8 for details).

2.4.2 Sample recovery - Disconnect the impingers after purging. Rinse separately the probe, quartz filter holder and the H 2 SO 4 condenser with deionized water using multiple rinses for good washing. Collect the condenser wash solution in Container No. 1, and the No. 1 and No. 2 impinger solutions in Container No. 2. Note levels of liquids in each containe r

.

2.4.3 Sample analysis - Note the level of liquid in containers 1 and 2, and confirm whether or not any sample was lost during shipment; note this on the analytical data sheet. If a noticeable amount of leakage has occurred, either void the sample or use methods, subject to the approval of the administrato r, to correct the final
results.

2.4.3.1 Container no. 1 - Transfer the entire contents of Container no. 1 into a

250 m L Erlenmeyer flask, add enough isopropyl alcohol to give an 80% isopropyl alcohol solution. Pipette a 100-m L aliquot of this
solution into a 250-m L Erlenmeyer flask, add 2 to 4 drops of thorin
indicato r, and titrate to a pink end point using 0.0100 N barium perchlorate. Repeat the titration with a second aliquot of sample and average the titration values. Replicate titrations must agree within 1% or 0.2 mL, whichever is greate r . Caution: The H 2 SO 4 concentrations in kraft recovery furnace stacks are typically so low that at times almost the entire sample in Container no. 1 may have to be used during the
titration.

2.4.3.2 Container no. 2 - If concurrent SO 2 concentrations in the stack are

desired carry out the following. Thoroughly mix the solution in Container no. 2 which holds the contents of the 1st and 2nd impingers. Pipette a 10-m L aliquot of this solution into a 250-m L Erlenmeyer
flask. Add 40 m L isopropanol, 2 to 4 drops of thorin indicato r, and titrate to a pink end point using 0.0100 N barium perchlorate. Repeat the titration with a second aliquot of sample and average the titration values. Replicate titrations must agree within 1% or 0.2 mL, whichever is greate r

.Method 8A - Determination of Sulfuric Acid Vapor or Mist and Sulfur Dioxide Emissions

5 December 1996 2.4.3.3 Blanks - Prepare blanks by adding 2 to 4 drops of thorin indicator to

100 m L of 80% isopropanol. T itrate the blanks in the same manner as the samples.

2.5 Calibration - Same as Section 5 of E PA Method 8.

2.6 Calculations - Same as Section 6 of E PA Method 8, except that equation 8-1 should be replaced by equation 6-1 of E PA Method 6, and references to isokinetic sampling in this section should be omitted. Recovery furnace stack gas temperatures are expected to be higher than the estimated dewpoint of H 2 SO 4 in the stack gas, and H 2 SO 4 is expected to be present in vapor phase onl y . Consequentl y

, neither isokinetic sampling nor a stack traverse is required.

2.7 Alternative procedures - Not applicable to this method.

2.8 References

National Council of the Paper Industry for Air and Stream Improvement, Inc. (NCASI).
1980. A study of SO x measurement procedures and their use at kraft recovery furnaces. Atmospheric Quality Improvement Technical Bulletin No. 106. Research Triangle Park, NC: National Council of the Paper Industry for Air and Stream Improvement, Inc.Method 8A - Determination of Sulfuric Acid Vapor or Mist and Sulfur Dioxide Emissions

6 December 1996 2.9 Tables, diagrams, flowcharts, and validation data

Figure 1. SO Sampling Train

X Heated Probe with Quartz Tube Stack Wall Insulated Box
Quartz Filter Holder High Temperature

Heating Elements

H SO Condenser 2 4

Thermocouple Teflon Tube

Silica Gel Drying Tube

Water 3% Hydrogen
Peroxide

Rate Meter Thermometer Ice Bath Greenburg-Smith Impingers

Needle
Valve
Pump Dry Gas
MeterMethod 8A - Determination of Sulfuric Acid Vapor or Mist and Sulfur Dioxide Emissions

7 December 1996 28/15 Ball Spring Attachment
Hooks

Tissue Quartz
Filter Thermocouple Well

28/15 Socket

Extra Coarse Quartz Fit Standard Taper Quartz 40/50

Seal Extension to

Std. Taper Joint

Figure 2. Quartz Filter HolderMethod 8A - Determination of Sulfuric Acid Vapor or Mist and Sulfur Dioxide Emissions

8 December 1996 Glass Jacket Gas Sample In Sintered Glass Filter

Figure 3. H SO Condenser

2 4Method 8A - Determination of Sulfuric Acid Vapor or Mist and Sulfur Dioxide Emissions

9 December 1996 Source ____________ Date _________________

Run No. __________ Furnace Load ________________

Stack Gas Temp. _____________ Atmospheric Pressure _________

Final Dry Gas Meter Reading _________

Initial Dry Gas Meter Reading _________

V olume Sampled ____________________

Temperature, ° F Dry Gas Meter Time (min) Probe Filter Condenser In Out

0

5

10

15

20

25

30

Figure 4. SO 3 Measurement Field Data SheetMethod 8A - Determination of Sulfuric Acid Vapor or Mist and Sulfur Dioxide Emissions

10 December 1996 Figure 5. EPA Approval Letter