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OAR Box 1784 

Prepped by Ollie Stewart 

Document Number: 

52) ll-B-11 

Docket Number: 

A--84-44 

Printed 10/31/2008 8:05:40 AM Sheet 52 of 143 
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

Office of Air Quality Planning and Standards 

Research Triangle Park, North Carolina 27711 

6 MAY 1986 

MEMORANDUM 

SUBJECT: Hydrogen Sulfide Continuous Emission Monitors at Refineries 

(86CEM02) 

FROM: Foston Curtis, Test Support Section _£ 

Emission Measurement Branch, ESED (MD-19) 

TO: Roger Shigehara, Chief, Test Support Section 

Emission Measurement Branch, ESED (MD-19) 

The available data on hydrogen sulfide (H£S) continuous emission 

monitoring systems (CEMS) has been obtained and reviewed. The Bay Area Air 

Quality Management District (BAAQMD) submitted test results of eight CEMS's 

under its jurisdiction. The tests consisted of cylinder gas audits 

administered on a quarterly basis. The data covered periods ranging from 1 

to 5 years and information detailing instrument down time was included. 

Testing to determine instrument calibration drift was not performed. 

Another report discussing the certification of an H2S CEMS at a Tacoma 

refinery was obtained through the Industrial Studies Branch. The CEMS was 

certified following the procedures of Performance Specifications (PS's) 2 

and 5; Method 11 served as the reference method. 

A summary of the data is shown in Tables 1 and 2. In Table 1, the 

BAAQMD results show a wide range of accuracies for the two CEMS types 

tested. Accuracy was calculated as percent difference between the CEMS 

results and the audit gas value. Differences greater than 20 percent 

constituted a failure. Accuracies determined in this manner are less 

stringent on the CEMS than accuracy determinations made as prescribed in 

the PS's. Even so, the average failure rate of seven companies using a 

Tracor Atlas CEMS was 24 percent for 38 tests. The one company using a 

General Monitors CEMS averaged a 57 percent failure rate for 23 tests. The 

instrument down time percentages over the data-gathering periods were 3.1 

for the Tracor Atlas and 0 for the General Monitors CEMS's. 

The certification test at the Tacoma refinery evaluated a Tracor Atlas 

CEMS following PS's 2 and five guidelines. The relative accuracy (RA) was 

9.8 percent (Table 2) and the 7-day calibration drift (CD) averaged 

1.4 percent. Individual drift data for each of the 7 days was not 

reported, but the CD was calculated by the procedure in a former version of 

PS 2 wherein the average daily drift plus the confidence interval were 

divided by the instrument span value. 
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These data sets are too limited to set practical PS's; but they 

show that, at least in some cases, acceptable performance can be obtained 

from some CEMS's in the field. According to the source review lead 

engineer, BAAQMD contacts, and other personnel in the refinery industry, 

very little data on CEMS calibration drift and RA testing against standard 

methods is available. A meeting was held to discuss the status and future 

activity for this project. Since available data is \ery limited and 

contractor resources are unavailable, it was decided that no future work 

should be planned, and the project should be terminated. 

2 Attachments 

c: Larry Elmore (MD-13) 
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Table 1. Field Data Summary 

Analyzer 

TracorAtlas 

* 

Aver. 

General 

Monitors 

Company 

Tosco 

Shell 

Pacific 

Huntway 

Exxon 

Union 

Chevron 

ige 

Chevron 

Total 

CGA's 

7 

7 

6 

4 

7 

4 

3 

5.4 

23 

Failed 

CGA's 

U 

1 

1 

1 

2 

2 

2 

1.3 

13 

% 

•Failed 

U 

14 

17 

25 

29 

50 

67 

29 

57 

% 

Downtime 

11 

3.2 

1.1 

0.2 

1.1 

1.9 

-_-__-

3.1 

0 

Yrs of downtime 

data 

5 

2 

3 

2 

4 

4 

0 

3.3 

b 

•Percent difference > 2U% 
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a _ 

Table 2. Tacoma CEMS RA Data 

Run 

1 

2 

3 

4 

5 

6 

7 

8 

9 

Mean 

sd 

Method 11 Results 

bb.3 

bl.3 

60.5 

18.U 

19.6 

lb.7 

i.2.5 

21.8 

19.1 

31.5 

CEMS Results 

63. b 

bl.U 

61. U 

2U.0 

2U.0 

22. U 

22. b 

22.0 

22.5 

33.8 

Difference 

8.2 

'-U.3 

0.5 

2.0 

- U.4 

6.3 

U 

0.2 

3.4 

2.4 

2.9 

CC = (2.3U6) (2.9) = 0.743 

9 

R A = (2.4) + (U.743) = 9#8 % 

31. b