April 1, 2011 

Shell Deer Park Refining LP 

Deer Park Refinery 

East Property Flare 

Test Report 
April 1, 2011 

2 

Shell Deer Park Refining LP 

Deer Park Refinery 

East Property Flare 

Performance Test Report

by 

Shell Global Solutions (US) Inc.
April 1, 2011 

i 

Executive Summary 

Shell Deer Park Site (SDP) received a letter, dated March 19, 2010, from the United States 

Environmental Protection Agency (EPA) requesting SDP to conduct a series of tests on the East 

Property Flare (EPF) and report the results. This report provides the EPF test results. The 

primary objective of the EPF testing was to obtain a better understanding of how the ratio of 

steam to vent gas (S/VG) at the flare combustion zone and the hydrogen content of the vent gas 

affect the combustion efficiency (CE). 

The EPF, like many refinery flares, is a steam-assisted flare equipped with a steam injection 

system to inject high-pressure steam at the flare tip to aid combustion and reduce smoke 

formation. Steam injection reduces smoke formation by adding additional momentum to the lowpressure vent gas stream, educting additional air into the combustion zone, and participating in 

the combustion process. Too much steam can decrease CE. Accordingly, the Section 114 

Request testing was intended to determine how the S/VG ratio and vent gas composition affect 

the CE achieved at the EPF. 

To determine how the S/VG ratio and vent gas composition affect CE, the CE achieved during 

testing can be calculated from the composition of the flare plume. EPA directed SDP to utilize a 

Passive Fourier Transform Infrared (PFTIR) instrument to determine the composition of the flare 

gas plume. The PFTIR instrument analyzes the infrared signal from the hot gas plume from the 

flare. The infrared spectra emitted by individual gas species can be analyzed to identify the 

concentrations of the various gas species in the gas plume. The ratio of hot flare gas carbon 

dioxide to total flare gas carbon constituents was used to calculate CE. 

SDP tested the EPF on several days in March and April, 2010. The data gathered during the 

testing provided useful insight into the factors that affect CE achieved by the EPF. The 

composition of the vent gas during this period was consistent with normal operation of the EPF, 

with the vent gas major constituents being hydrogen, nitrogen, and methane, with minor 

contributions from other low-molecular weight paraffinic, olefinic, and aromatic hydrocarbons. 

The EPF exhibited high combustion efficiencies over a wide range of S/VG ratios. The EPF 

attained combustion efficiencies in excess of 98.0% up to S/VG ratios approaching 6 lb steam/lb 

vent gas. However, due to the large variation in vent gas composition observed at the EPF, 

poor combustion efficiencies were also seen at S/VG ratios as low as 1.2 lb steam/lb vent gas 

when the vent gas had high nitrogen contents and low heat content. While there was not a 

consistent relationship between CE and S/VG ratio due to significant changes in vent gas 

composition, a more consistent and predictable relationship was observed between CE and the 

net heating value of the combustion zone gas (NHVczg). NHVczg is calculated as the volumetric 

dilution of all process gases going to the flare tip (e.g. vent gas, steam, and pilot gas). SDP 

observed high combustion efficiencies when the NHVczg was above 200 BTU/SCF, as can be 

seen in Figure ES-1 which displays all observed NHVczg and CE values from all of the Section 

114 Request testing conducted on the SDP EPF. 
April 1, 2011 

ii 

A secondary objective of the EPF testing was to compare data gathered by the PTFIR 

instrument when using an Indium Antimonide (InSb) detector with data collected using a 

Mercury Cadmium Telluride (MCT) detector. Industrial Monitor and Control Corp. (IMACC) 

compared the InSb and MCT detectors and found that the CE data trends from each detector 

were indistinguishable. Since the MCT detector can analyze for the presence of CO2 in multiple 

regions of the IR spectra, additional data on flare plume temperature can be obtained from the 

MCT detector, using a proprietary fitting algorithm developed by the PFTIR vendor IMACC. Due 

to the InSb detector’s greater sensitivity in the 1-5.5 μm wavelength range, it remains the better 

detector to characterize unburned higher molecular weight hydrocarbons in the hot flare plume. 
April 1, 2011 

iii 

Table of Contents 

Executive Summary

1. Introduction ........................................................................................................ 1

1.1 Background ............................................................................................... 1

1.2 Objectives of program................................................................................ 1

1.3 Testing Team............................................................................................. 1

1.4 Flare System Components ........................................................................ 1

1.4.1 Flare Purpose ................................................................................. 1

1.4.2 Flare Tip.......................................................................................... 2

1.4.3 Flare Instrumentation and Control .................................................. 2

1.4.3.1 Vent Gas Flow.......................................................................... 2 

1.4.3.2 Steam Flow and Control ........................................................... 2 

1.4.3.3 Online Vent Gas Analyzer......................................................... 3 

1.5 Flare Test Equipment ................................................................................ 3

1.5.1 Passive FTIR System ..................................................................... 3

1.5.2 Online BTEX Gas Chromatograph (GC)......................................... 3

1.5.3 Video Cameras............................................................................... 3

1.5.4 PFTIR Aiming Camera.................................................................... 4

1.5.5 FLIR GasFindIR Video Camera...................................................... 4

1.6 Flare Test Program.................................................................................... 4

1.6.1 Series A.......................................................................................... 4

1.6.2 Series B.......................................................................................... 5

1.6.3 Series C.......................................................................................... 6

1.6.4 Series D (Mercury Cadmium Telluride (MCT) Detector 

Comparison Series) ....................................................................... 6

2. Summary of Results........................................................................................... 8

2.1 Summary and Key Data Trends by Test Series......................................... 8

2.1.1 Test Series A, Increasing Steam to Vent Gas (S/VG) Ratio at 

Low Hydrogen Content................................................................... 8

2.1.2 Test Series B, Limiting S/VG Ratio with Variable Hydrogen 

Content......................................................................................... 12

2.1.3 Test Series C, Increasing S/VG Ratio, Low Vent Gas Flow, 

Variable Hydrogen Content.......................................................... 16

2.1.4 Test Series D, Mercury Cadmium Telluride (MCT) Detector 

Comparison.................................................................................. 19

2.2 Summary and Key Data Trends of Whole Data Set ................................ 23

2.2.1 Visible Emissions.......................................................................... 23

2.2.2 CE vs. S/VG Ratio ........................................................................ 25

2.2.3 CE vs. NHVczg ............................................................................... 27

2.3 Factors Influencing Test Results ............................................................. 29

2.3.1 EPF Vent Gas Flow Measurements.............................................. 29

2.3.1.1 EPF GE Panametric Flow Issues............................................ 29 

2.3.1.2 Corrective Actions................................................................... 30 
April 1, 2011 

iv 

2.3.1.3 Flow Validation from New Configuration/ Adjustment of Prior 

Data from Old Configuration ................................................... 31 

2.3.1.4 Adjustment of EPF flows during High N2 Test Periods ............ 36 

2.3.2 Wind Effects and PFTIR Aiming Issues ........................................ 36

2.3.3 PFTIR Variability - Confidence Intervals for Observed 

Combustion Efficiency Mean Values............................................ 37

2.3.4 PFTIR Component Errors ............................................................. 43

2.3.5 PFTIR Hot Cell Calibration............................................................ 44

2.3.6 Validation of Online Gas Composition Analyzers.......................... 44

2.3.7 Potential Impacts of Integrated Sampling ..................................... 50

2.3.8 Accuracy of Combustion Efficiency Measurements at Unstable 

Combustion Conditions ................................................................ 50

2.4 Conclusions............................................................................................. 51

3. PFTIR Testing Methods and Procedures........................................................ 52

3.1 Description and Principles of Passive FTIR Measurements .................... 52

3.2 PFTIR Siting Configuration...................................................................... 52

3.3 PFTIR Operation ..................................................................................... 54

3.4 PFTIR Data Reduction............................................................................. 54

4. Data Tables and Files....................................................................................... 59

4.1 Data Tables ............................................................................................. 59

4.2 Visible Video Files ................................................................................... 59

4.3 GasFindIR Video Files............................................................................. 59

5. Appendices....................................................................................................... 60

5.1 PFTIR Test Protocol (IMACC) ................................................................. 60

5.2 Weather Data .......................................................................................... 60

5.3 Summa Canister Sample Results............................................................ 60

5.4 PFTIR Calibration Log ............................................................................. 60

5.5 Master Data Workbook............................................................................ 60

5.6 Flare Testing Video Files......................................................................... 60

5.7 Flare Testing GasFindIR Video Files....................................................... 60
April 1, 2011 

1 

1. Introduction 

1.1 Background 

Shell Deer Park Site (SDP) received a letter, dated March 19, 2010, from the United States 

Environmental Protection Agency (EPA) pursuant to Section 114 of the federal Clean Air Act 

(Section 114 Request) requesting SDP to conduct a series of tests and provide test results on 

the East Property Flare (EPF). This report provides the requested data and test results. 

1.2 Objectives of program 

The Section 114 Request defined the objectives of the EPF test program and required three test 

series. EPA subsequently added a fourth test series. The four test series are: 

 

A. Series A - Identify the relationship between Steam to Vent gas Ratio (S/VG) and 

combustion efficiency (CE) at the EPF when operating within a defined vent gas flow 

range and at a vent gas hydrogen composition below 30v%. 

B. Series B - Identify the relationship between hydrogen content of vent gas and CE at the 

EPF when operating within a defined vent gas flow range and at a S/VG ratio identified 

as resulting in a CE between 75% and 90% in Series A. 

C. Series C - During flare operating conditions that do not meet any of the test conditions 

specified for Series A or B, test at successive higher S/VG until the observed CE drops 

to below 75% in order to identify the relationship between S/VG ratio and CE. 

D. Series D (Mercury Cadmium Telluride Detector Comparison Series) - Compare the 

results from the Indium Antimonide (InSb) detector used in the other tests to a Mercury 

Cadmium Telluride (MCT) detector by obtaining CE data with the MCT detector under 

similar conditions used in testing with the InSb detector. 

1.3 Testing Team 

SDP conducted the tests responsive to the Section 114 Request in cooperation with Deer Park 

Operations, Maintenance, Engineering, and Environmental staff and with assistance from Shell 

Global Solutions (US) Inc. and Industrial Monitor and Control Corporation (IMACC) personnel 

(collectively, the “Testing Team”). 

Shell Global Solutions (US) Inc. IMACC 

3333 Hwy 6 South 800 Paloma, Suite 100 

Houston, Texas 77082 Round Rock, Texas 78645 

1.4 Flare System Components 

1.4.1 Flare Purpose 

The EPF provides emergency relief capacity and waste gas destruction capability for nineteen 

process units in the Deer Park Refinery. The EPF flows range from 2,000 to 5,000 lb/hr at 

normal operating conditions to a maximum relief capacity of nominally 500,000 lb/hr. The EPF 

waste gas typically has high hydrogen content with periodic, limited instances of high nitrogen 

content. 
April 1, 2011 

2 

The flare is operated within the maximum flare tip velocities and minimum net heating values as 

specified in 40 CFR 60.18. The Section 114 Request testing program specified test conditions 

at normal minimum flow conditions at the EPF. 

1.4.2 Flare Tip 

The Deer Park Site East Property Flare is a 36” diameter, elevated, steam-assisted flare. The 

36” diameter flare tip (model EEF-QA-36-C) was manufactured by the John Zink Company, 

Tulsa, OK, and was installed in May, 1990. The flare has provisions for steam addition from 21 

upper steam ring flame shaping tips and from a center steam injection port. 

Table 1.4.2-1. Shell Deer Park Site East Property Flare Description 

Parameter Value Units 

Pilot Gas 150 SCFH 

Minimum Center Cooling Steam 1,500 lb/hr 

Minimum Upper Cooling Steam 500 lb/hr 

Maximum Hydraulic Capacity1330,829-806,704 lb/hr 

Maximum Smokeless Capacity2105,000-140,000 lb/hr 

Height of Flare Tip 60 ft above grade 

 

Typical flows at the EPF are approximately 4% of the smokeless capacity of the flare and 1% of 

the maximum relief capacity. The EPF base load includes flare header sweep gas, seal purges 

from rotating equipment, flows from sample and analyzer stations, and process vents from the 

process units serviced by the EPF. 

1.4.3 Flare Instrumentation and Control 

1.4.3.1 Vent Gas Flow 

SDP meters the waste gas flow to the EPF with a GE Panametric GF868 correlation transient 

line ultrasonic meter. The transducers are placed in a top down standard Midradius Bias 90 

configuration with local temperature and pressure compensation installed as per manufacturer’s 

specifications. The sensors are installed in a straight run configuration. The meter ID is 

FI30418. It is positioned between the final knock out vessel (V5086) and the flare. Signals from 

this analyzer are tied into the Deer Park Refinery Distributed Control System (DCS). Calibration 

is performed annually. 

1.4.3.2 Steam Flow and Control 

The EPF steam control consists of a model 10” LVM-U Wyatt Venturi flow meter (FE-422), a 

model ED 1 1⁄2” Fisher control valve (FV-422A), and a model ED 4” Fisher control valve (FV422B). The control valves are operated in stages. An output between 0% and 50% operates 

the 1 1⁄2” control valve, and an output between 51% to 100% operates the 4” control valve. 

When the output is above 50% the 1 1⁄2” control valve is wide open while the 4” control valve 

begins to open. The flow meter is calibrated for a range of 0 to 100 inches of water column 

 

1

 The maximum hydraulic capacity of the EPF varies from 330,829-806,704 lb/hr as the molecular weight 

of the vent gas varies from 7.4-44. 

2

 The smokeless capacity of the EPF varies from 105,000-140,000 lb/hr as the molecular weight of the 

vent gas varies from 7.4-44. 
April 1, 2011 

3 

which corresponds to a steam flow of 0 to 44,000 lb/hr. The steam to the East Property Flare is 

limited by upstream hydraulics to about 34,000 lb/hr. The steam addition to the flare is manually 

controlled by an operator who monitors the flare camera. The operator increases or decreases 

the control valve output in accordance with flare smoke observation. 

1.4.3.3 Online Vent Gas Analyzer 

The online vent gas analyzer is a Siemens Maxum Edition II process analyzer with a full 

complement of modules to meet the TCEQ Chapter 115 HRVOC monitoring requirements. The 

analyzer cycle time is every 7 minutes. Quality Assurance and Quality Control programs meets 

all RATA and TCEQ HRVOC requirements including three point certified testing and R2 linearity 

requirements. The collected data is tied into the Deer Park Refinery LIMS system. 

1.5 Flare Test Equipment 

1.5.1 Passive FTIR System 

As directed, SDP used PFTIR spectroscopy to determine the gas composition of the hot flare 

gas plume. Chapter 3 and Appendix 5.1 describe the instrument and testing procedures. 

PFTIR spectroscopy uses spectral analysis to detect individual compounds in the hot flare 

plume. Rather than using an active infrared (IR) source and detecting the energy adsorbed by 

the individual species from the active source, PFTIR analyzes the IR signal from the hot flare 

gas plume. The IR emission spectra emitted by individual species from a hot source is the same 

spectra or “fingerprint” as the absorption spectra being analyzed in an active FTIR system. The 

advantage of a PFTIR is that no active source is needed and no additional optics 

(retroreflectors) is needed to collect the active beam after it passes through the source plume. 

By observing the IR radiation emitted from the flare with an appropriate IR collection telescope 

and spectrometer, individual species can be detected and quantified, just as in active FTIR 

spectroscopy. 

For this test program, the PFTIR operation and data analysis was overseen by Dr. Robert 

Spellicy and Dr. Curtis Laush of IMACC. The PFTIR instrumentation and software were 

developed by IMACC. 

1.5.2 Online BTEX Gas Chromatograph (GC) 

EPA required measurement of the aromatics present in the EPF vent gas but SDP’s vent gas 

GC does not speciate benzene, toluene, ethylbenzene, and xylenes (BTEX) because they 

historically make up less than one percent by volume of EPF waste gas. Therefore, these 

aromatic compounds have been grouped as a pseudo C5

+ compound by the existing GC. SDP 

installed a Photovac Voyager gas chromatograph with photo-ionization detection (PID) on the 

vent gas analyzer fast loop to measure BTEX components during the Section 114 Request 

testing. SDP used QA/QC programs in accordance with US EPA Method 18. Cycle time was at 

least as frequent as the process analyzer. SDP collected data from the BTEX device locally. 

1.5.3 Video Cameras 

Two video cameras recorded the flare plume during the testing. The cameras are pan/tilt/zoom 

Pelco cameras fed to a Pelco DX4500 digital video recorder. Both cameras were mast mounted 

about 5 yards above grade and 100 yards from the flare on a similar vector as the PFTIR 

instrument. 
April 1, 2011 

4 

1.5.4 PFTIR Aiming Camera 

The PFTIR Aiming Camera is an IR camera mounted on the PFTIR telescope. The PFTIR 

operator used the camera image to aim the PFTIR instrument. Images from this video stream 

give an indication of PFTIR aiming accuracy. An image from this camera is shown in Figure 

1.4.5-1-1. The red square (added for this report) shows the area analyzed by the PFTIR. This 

red area completely fills the field of view of the PFTIR telescope during testing and indicates the 

area of the plume being sampled. 

Figure 1.4.5-1. FTIR Aiming Camera 

1.5.5 FLIR GasFindIR Video Camera 

A FLIR GasFindIR Model 25147-200 video camera recorded the thermal images of the flare tip 

during the Section 114 Request testing. The camera was tripod mounted adjacent to the IMACC 

FTIR and signal output was fed to a DVR recorder. A 50mm lens was used to optimize the field 

of view and default image settings gave the most consistent image. Those image settings were: 

(auto, histogram, and black polarity as hydrocarbon). 

 

1.6 Flare Test Program 

The Section 114 Request prescribed three test series, and EPA added a fourth test series. The 

procedures and conditions for each test series are discussed below. 

1.6.1 Series A 

Series A was designed to identify the impact of the S/VG ratio on the CE of the EPF. As 

specified in the Section 114 Request, SDP was to conduct Series A testing at vent gas flows 

between 3,000 and 6,000 lb/hr, when the hydrogen content of the vent gas was less than 30v%. 

The Section 114 Request specified twelve S/VG values as listed in Table 1.6.1-1, below. SDP 

was to run each test for 30 minutes, except for those runs during which the preliminary CE was 

below 75%, in which case SDP could terminate the run after 10 minutes. 

Table 1.6.1-1. S/VG Ratios Requested for Series A

Test EPA Test ID S/VG (lb Steam/lb Vent Gas) 

[EP-A-10.0] 10.0 

[EP-A-9.0] 9.0 

[EP-A-8.0] 8.0 

[EP-A-7.0] 7.0 

[EP-A-6.0] 6.0 

[EP-A-5.0] 5.0 
April 1, 2011 

5 

[EP-A-4.0] 4.0 

[EP-A-3.0] 3.0 

[EP-A-2.0] 2.0 

[EP-A-1.0] 1.0 

[EP-A-Minimum Cooling Steam] 0.33-0.67 

[EP-A-API 521] 0.1-0.4 

SDP deviated from the prescribed testing procedures and conditions in two ways. First, 

because the minimum manufacturer’s recommended cooling steam is 2,000 lb/hr for the EPF 

(1,500 lb/hr to the center steam port and 500 lb/hr to the upper steam ring), SDP could not 

operate at the API 521 suggested S/VG ratio at the flow rates requested in this series of tests 

(i.e., 3,000 to 6,000 lb/hr). Second, EPA requested that SDP begin Series A testing at the 

highest S/VG ratio and work back to the lower S/VG values. Because the EPF receives vent 

gas streams that have the potential to contain hydrogen sulfide (H2S), SDP, with EPA’s 

concurrence, started at lower S/VG ratios and incrementally increased the /VG to minimize the 

potential to extinguish the flare flame and release H2S to the environment. 

1.6.2 Series B 

Series B was designed to identify the impact of increasing hydrogen concentration in the vent 

gas on the CE of the EPF at a constant S/VG ratio. The Section 114 request set the S/VG ratio 

for this series as the lowest S/VG ratio at which SDP observed a CE between 75-90% during 

Series A testing. Table 1.6.2-1 depicts the vent gas hydrogen concentrations prescribed in the 

Section 114 Request for Series B testing. 

Table 1.6.2-1 Hydrogen Concentrations Requested for Series B Testing 

EPA Test ID Vent Gas Hydrogen Concentration, v% 

[EP-B-31] 31-40 

[EP-B-41] 41-50 

[EP-B-51] 51-60 

[EP-B-61] >60 

Preliminary Series A test results indicated that CE deteriorated rapidly between an S/VG ratio of 

4.0 to 5.0 lb steam/lb vent gas. Therefore, SDP conducted B Series tests starting at an /VG 

ratio of 4.0. Subsequently, SDP learned that the vent gas flow values obtained from the GE 

Panametrics flow meter during the Series A testing significantly under represented actual flows 

under the high nitrogen conditions present in the Series A tests. SDP adjusted the nonrepresentative flows using other process instrumentation to better quantify actual flows during 

the Series A tests. The procedure to adjust the flows is explained in Section 2.3.1, but explains 

why the S/VG values presented in the Series B results section do not correspond to the S/VG 

values ultimately determined from the adjusted Series A test. 

The impact of conducting the Series B tests at an S/VG ratio between 4.0 and 5.0, versus the 

value determined from the corrected flow data in Series A (~0.8 lb Steam/lb Vent Gas), was 

negligible. In fact, if Series B had been conducted at an S/VG ratio of 1.4, as indicated by the 

corrected Series A flow data, all CE results for Series B would have been above 98.0%, an area 

where little discernible impact of hydrogen would have been noticeable. 
April 1, 2011 

6 

1.6.3 Series C 

The EPF receives vent gas from a large number of units with limited ability to adjust flows or 

hydrogen concentrations to achieve the series A and B test criteria so there were numerous 

periods during the testing when SDP could not conduct Series A or Series B tests per the 

specified conditions. EPA asked SDP to use the available test time when process conditions 

were not within the Series A or B test conditions to conduct Series C tests at a broader range of 

operating conditions and obtain as much data as possible that may indicate how CE varies as a 

function of S/VG ratio. Series C flow rate ranges were 100-6,000 lb/hr with hydrogen 

concentrations above 30v%. SDP was to conduct each individual run for 10 minutes and, if 

possible, for an additional 10 minutes following the first 10-minute period. The Section 114 

Request directed SDP to conduct the Series C testing from the highest achievable S/VG ratio to 

the lowest. However, as with the Series A tests, the Series C tests were run from lowest S/VG 

ratio to highest, to minimize the potential for H2S emissions. Table 1.6.3-1 describes the S/VG 

values EPA requested. 

Table 1.6.3-1. S/VG Ratios EPA Requested for Series C Testing 

EPA Test ID S/VG (lb Steam/lb Vent Gas) 

[EP-C-16.0] 16.0 

[EP-C-15.0] 15.0 

[EP-C-14.0] 14.0 

[EP-C-13.0] 13.0 

[EP-C-12.0] 12.0 

[EP-C-11.0] 11.0 

[EP-C-10.0] 10.0 

[EP-C-9.0] 9.0 

[EP-C-8.0] 8.0 

[EP-C-7.0] 7.0 

[EP-C-6.0] 6.0 

[EP-C-5.0] 5.0 

[EP-C-4.0] 4.0 

[EP-C-3.0] 3.0 

1.6.4 Series D (Mercury Cadmium Telluride (MCT) Detector Comparison 

Series) 

SDP conducted Series A, B, and C testing using an Indium Antimonide (InSb) detector. The 

Testing Team believed that this detector had the best range of sensitivities for the detection of a 

broad range of hydrocarbons, methane, and carbon monoxide (CO), although it is less sensitive 

with respect to carbon dioxide (CO2). This is because the InSb detector cannot detect signals 

below a wavenumber of 2000 cm-1, which is where the strongest CO2 absorption band falls. 

Although the Testing Team did not expect this lack of CO2 absorption sensitivity to be 

problematic for robust flames, the Testing Team was uncertain about the InSb detector’s ability 

to detect CO2 in unstable combustion situations where low CO2 concentrations might be 

encountered. 

The MCT detector is capable of detecting CO2 in three different wave number regions: 2080 

cm-1

, 1000 cm-1, and 765 cm-1. Therefore, the Testing Team hypothesized that the MCT detector 

might provide more accurate CO2 measurements at low CO2 concentrations. 

Because IMACC did not have a beam splitter during the test, it was not possible to utilize both 

the InSb and MCT detectors at the same time to detect the same flare IR signature. Therefore, 
April 1, 2011 

7 

for the last two test days (April 15th and 16th), IMACC replaced the InSb detector with the MCT 

detector and SDP conducted a series of tests at conditions similar to those encountered using 

the InSb detector on previous days. IMACC analyzed the CO2 data at both the 765 cm-1 and 

2080 cm-1 wavenumber with the MCT detector. IMACC used its proprietary iterative comparison 

technique to estimate the temperature of the hot flare plume. The temperature determined from 

this iterative process was then used to reduce the data obtained from other species detected in 

the hot gas plume. Although it was not possible to directly compare the data gathered by the 

InSb detector and the MCT detector, test conditions with the MCT detector were matched as 

closely as possible to the conditions at which the InSb detector was utilized. Table 1.6.4-1 

illustrates the test conditions selected for the MCT detector comparison testing. 

Table 1.6.4-1. S/VG Ratios Selected for MCT Detector Testing 

EPA Test ID S/VG (lb Steam/lb Vent Gas) 

EP-D-2.0(MCT2) 2.0 

EP-D-3.0(MCT2) 3.0 

EP-D-4.0(MCT2) 4.0 

EP-D-5.0(MCT1) 5.0 

EP-A-5.0(MCT3) 5.0 

EP-D-6.0(MCT'1) 6.0 

EP-D-2.0(MCT1) 2.0 

EP-D-3.0(MCT1) 3.0 

EP-D-4.0(MCT1) 4.0 

EP-D-6.0-1 MCT 6.0 

EP-D-4.5(MCT1) 4.5 
April 1, 2011 

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2. Summary of Results 

2.1 Summary and Key Data Trends by Test Series 

2.1.1 Test Series A, Increasing Steam to Vent Gas (S/VG) Ratio at Low 

Hydrogen Content 

EPA instructed SDP to conduct Series A testing when the hydrogen composition of the stream 

was less than 30v%. However, historic EPF composition data indicated that the vent gas 

hydrogen content is not normally below 30v% except during the nitrogen purge cycle of the 

Catalytic Reformer-3 (CR-3) regeneration. This purge cycle occurs every 30-36 hours, so SDP 

had a limited number of daylight opportunities to test with hydrogen below 30v% during the 

Section 114 Request test period. SDP conducted Series A tests on March 29 and April 13, 

2010. Figure 2.1.1-1 and Figure 2.1.1-1a illustrate the CE results from this series of tests. 

Tabulated data from this test series are presented in Table 2.1.1-1. 

During the Series A testing, the vent gas flow readings from the GE Panametric GF868 flow 

meter during the CR-3 nitrogen purge cycle were not representative of the anticipated flows 

based on process knowledge (i.e., extremely low measured vent gas flows, when based on 

other process data the flow was known to be much higher). The flare exhibited visually stable 

combustion and high measured CE with the PFTIR at S/VG ratios in excess of 30, as calculated 

using indicated flows from the GE flow meter. Further investigation of the flow meter response 

at high nitrogen concentrations led SDP, in consultation with EPA, to adjust the flow meter 

results, using other plant instrumentation, to provide representative flows during the high 

nitrogen flow conditions. Section 2.3.1 provides a detailed discussion of the procedures used to 

make the flow adjustments. 

SDP adjusted all vent gas flow data during the CR-3 nitrogen purge including data gathered 

during the Series A testing conducted on March 29. Accordingly, all but one of the Series A 

S/VG ratios reported and displayed in Figure 2.1.1-1 are based upon adjusted flow data, which 

varied considerably from the values computed from the vent gas flow numbers obtained during 

the test period. Data points calculated from adjusted flows are shown as open symbols in the 

graphs in this report, while data calculated from the unadjusted vent gas flow meter values are 

shown as closed symbols. Data calculated from adjusted vent gas flows in the tables in this 

report are printed in red, while data calculated from the existing EPF vent gas flow meter are 

printed in black. 

At constant vent gas composition, CE is relatively constant with increasing S/VG ratios until a 

critical S/VG value is reached, at which point there is a very rapid drop in the observed CE. For 

the Series A tests this breakpoint in CE occurred at a S/VG ratio of approximately 1.2 lb 

sSteam/lb vent gas. As will be seen in later results, the S/VG ratio at which this drop in CE 

occurs is a function of the vent gas composition and the combustion properties of the vent gas. 

 
April 1, 2011 

9 

* The expanded scale graphs in this report depict the high combustion efficiency data at a larger scale to facilitate visual 

data analysis. However, the expanded scale graph excludes any CE data below 90%. The expanded scale graph should 

be used in conjunction with the full scale graphs for a full representation of the subject data sets. 
April 1, 2011 

10 

Table 2.1.1-1 Series A Test Results Summary 

Test Number Start Time End Time Min 

# PFTIR 

scan 

avg. 

NHVczg 

(BTU/SCF) 

CE 

(%) 

H2 

(v%) 

THC 

(v%) 

N2 

(v%) 

S/VG 

(lb/lb) 

[EP-A-2.0(1)] * 3/29/2010 

13:30 

3/29/2010 

14:23 53 13 188 99.1 29.6 16.1 53.4 0.90 

[EP-A-3.0(1)] * 3/29/2010 

11:37 

3/29/2010 

12:20 43 10 144 97.4 27.3 15.3 56.7 1.21 

[EP-A-4.0(1)] * 3/29/2010 

12:21 

3/29/2010 

12:51 30 8 149 97.6 28.2 15.3 55.7 1.23 

[EP-A-5.0(1)] * 3/29/2010 

13:10 

3/29/2010 

13:15 05 1 129 0.0 27.5 14.0 57.6 1.34 

[EP-A-5.0(2)] * 3/29/2010 

13:16 

3/29/2010 

13:22 06 1 127 0.0 27.8 14.4 56.9 1.45 

[EP-A-6,000(1)] * 4/13/2010 

9:30 

4/13/2010 

10:04 34 16 251 98.9 25.9 24.4 48.4 0.44 

[EP-A-5,500(1)] * 4/13/2010 

10:07 

4/13/2010 

10:39 32 15 234 98.8 24.2 22.5 52.0 0.40 

[EP-A-10,000(1)] * 4/13/2010 

10:51 

4/13/2010 

11:22 31 16 208 98.6 20.5 30.1 48.1 0.76 

[EP-A-12,500(1)] * 4/13/2010 

11:32 

4/13/2010 

12:03 31 16 181 0.00 20.4 30.2 48.1 0.97 

[EP-A-10,000(1)] 

4/13/2010 

12:51 

4/13/2010 

13:11 20 10 159 96.9 48.4 34.0 14.1 3.42 

1EPA test number nomenclature identified Series A tests by the intended S/VG. This nomenclature was used 

for the March 29 testing. However, after determining that vent gas flow readings, and thus the S/VG, were not 

representative of process conditions, the April 13 test runs were named by the total steam (lb/hr) going to the flare. 

* Measured vent gas flow was adjusted for this test. Results presented are based on the adjusted vent gas flow 

values, not the incorrect measured values. See discussion in Section 2.3.1. 

Because the S/VG at which CE rapidly declines may vary drastically as a function of vent gas 

composition, EPA proposed an alternate parameter to account for the impacts of both the vent 

gas composition and S/VG ratio on CE: the net heating value in the combustion zone (NHVczg). 

The NHVczg is calculated as the volumetric dilution of the gas components entering the flame 

zone (e.g. vent gas, pilot gas, and steam). Figure 2.1.1-2 and Figure 2.1.1-2a illustrate the 

Series A CEs as a function of NHVczg. Based on the data displayed in Figure 2.1.1-2, SDP 

believes that the NHVczg may be a suitable control parameter to predict expected CEs at varying 

vent gas compositions and S/VG ratios. For the Series A tests the CE was always above 98.0% 

when the NHVczg was above 200 BTU/SCF. 
April 1, 2011 

11 

* The expanded scale graphs in this report depict the high combustion efficiency data at a larger scale to facilitate visual data 

analysis. However, the expanded scale graph excludes any CE data below 90%. The expanded scale graph should be used 

in conjunction with the full scale graphs for a full representation of the subject data sets. 
April 1, 2011 

12 

2.1.2 Test Series B, Limiting S/VG Ratio with Variable Hydrogen Content 

One objective of the Series A tests was to determine the S/VG ratio that yielded a CE between 

75-90%. Based upon the unadjusted March 29 test flow data this CE was observed at an S/VG 

between 4 and 5. Therefore, SDP attempted to conduct Series B tests at a S/VG ratio between 

4 and 5. SDP did not discover that the flow readings observed from the vent gas flow meter 

during periods of elevated nitrogen concentrations were not representative of actual flows until 

after Series B testing was completed. The impact of conducting the Series B tests at an S/VG 

ratio of between 4.0 and 5.0, versus the value determined from the corrected flow data in Series 

A (~1.2-1.4 lb Steam/lb Vent Gas), was negligible. In fact, if Series B had been conducted at a 

S/VG ratio of 1.2, as indicated by the corrected Series A flow data, all CE results for Series B 

would have been above 98.0%, an area where little discernible impact of hydrogen would have 

been noticeable. 

SDP conducted Series B testing on March 30, April 1, and April 6, 2010. Figures 2.1.2-1 and 

2.1.2-2a depict the results from the Series B tests, and Table 2.1.2-1 presents the tabulated data 

from this test series. Figure 2.1.2-1 shows that under typical gas compositions, outside the CR3 nitrogen purge window, high CEs were observed up to a S/VG ratio of near 5, with extinction 

of the flame observed at a S/VG ratio between 5 and 6. As observed during Series A testing, 

when the nitrogen concentration increases, such as during CR-3 nitrogen purges, the breakpoint 

in the CE curve versus S/VG will be pushed to lower S/VG ratios. Conversely, at constant 

nitrogen concentrations, as the ratio of hydrogen to total hydrocarbon increases, the breakpoint 

in the CE versus S/VG relationship will be pushed to higher S/VG ratios. This trend is somewhat 

obscured in the data, as SDP does not have the ability to independently manipulate the 

hydrogen concentration without impacting the resulting hydrocarbon and nitrogen 

concentrations. 

Figure 2.1.2-2 and Figure 2.1.2-2a display the CEs measured during Series B testing as a 

function of NHVczg. These Series B tests display high observed combustion efficiencies 

(>98.0%) when the NHVczg is above 150 BTU/SCF. This breakpoint in combustion efficiency 

versus NHVczg is about 50 BTU/SCF lower than that observed in the Series A testing, which is 

believed to be a result of the higher hydrogen content of the vent gas during the Series B tests. 

Consistent with Series A results, NHVczg appears to have a more consistent correlation with CE 

than S/VG ratio. 
April 1, 2011 

13 

* The expanded scale graphs in this report depict the high combustion efficiency data at a larger scale to facilitate visual 

data analysis. However, the expanded scale graph excludes any CE data below 90%. The expanded scale graph should 

be used in conjunction with the full scale graphs for a full representation of the subject data sets. 
April 1, 2011 

14 

Table 2.1.2-1. Series B Test Results Summary 

Test Number Start Time End Time Min 

# PFTIR 

scan 

avg.

NHVczg

(BTU/SCF) 

CE 

(%) 

H2 

(v%) 

THC 

(v%) 

N2 

(v%) 

S/VG 

(lb/lb) 

[EP-B-51(1)] 3/30/2010 

9:55 

3/30/2010 

10:38 43 18 145 97.3 57.1 27.1 13.4 4.13 

[EP-B-51(2)] 3/30/2010 

10:40 

3/30/2010 

11:30 50 18 126 97.5 57.0 27.4 13.3 4.95 

[EP-B-61(1)] * 4/1/2010 

8:48 

4/1/2010 

9:16 28 13 162 98.6 60.4 23.8 14.3 3.25 

[EP-B-61(2)] * 4/1/2010 

9:17 

4/1/2010 

9:46 29 15 261 99.0 61.9 23.7 12.9 1.53 

[EP-B-31(3)] * 4/1/2010 

10:17 

4/1/2010 

10:50 33 16 171 97.1 37.1 16.5 45.3 1.20 

[EP-B-31(2)] * 4/1/2010 

10:51 

4/1/2010 

11:28 37 19 176 98.6 35.7 16.0 47.0 1.12 

[EP-B51(HiFlo1)] *4/1/2010 

12:32 

4/1/2010 

13:16 44 22 160 98.8 50.8 15.4 32.7 1.91 

[EP-B51(HiFlo2)] *4/1/2010 

13:17 

4/1/2010 

13:53 36 18 159 98.8 51.0 15.0 32.9 1.90 

[EP-B-61-2i] 4/6/2010 

10:00 

4/6/2010 

10:16 16 8 132 97.3 61.2 21.4 14.6 4.09 

[EP-B-61-2ii] 4/6/2010 

10:17 

4/6/2010 

10:42 25 13 120 57.1 61.0 21.5 14.8 4.61 

[EP-B-61-2iii] 4/6/2010 

10:43 

4/6/2010 

10:53 10 6 111 79.8 61.1 21.6 14.4 5.15 

[EP-B-61-2iv] 4/6/2010 

10:54 

4/6/2010 

11:14 20 10 106 0.0 61.1 21.7 14.5 5.45 

[EP-B-61-3i] 4/6/2010 

11:16 

4/6/2010 

11:24 08 3 187 98.7 61.0 21.7 14.8 2.47 

[EP-B-61-3ii] 4/6/2010 

11:32 

4/6/2010 

11:49 17 1 119 98.9 60.6 21.7 14.9 4.66 

[EP-B-61-3iii] 4/6/2010 

11:50 

4/6/2010 

11:58 08 4 114 97.5 59.8 22.1 15.2 4.89 

[EP-B-61-3iv] 4/6/2010 

11:59 

4/6/2010 

12:09 10 5 130 0.0 59.9 21.8 15.5 6.01 

*

Vent gas flow was adjusted for these tests. See discussion in Section 2.3.1. 
April 1, 2011 

15 

 * The expanded scale graphs in this report depict the high combustion efficiency data at a larger scale to facilitate visual 

data analysis. However, the expanded scale graph excludes any CE data below 90%. The expanded scale graph should be

used in conjunction with the full scale graphs for a full representation of the subject data sets. 
April 1, 2011 

16 

2.1.3 Test Series C, Increasing S/VG Ratio, Low Vent Gas Flow, Variable 

Hydrogen Content 

SDP conducted Series C testing on March 22, 24, and 25, 2010. SDP started the C Series test 

at an S/VG ratio of approximately 2.5 and incrementally increased the S/VG ratio. The results 

for these tests are illustrated in Figure 2.1.3-1, and the numerical results are tabulated in Table 

2.1.3-1. As in the Series B tests, the CE started above 98.0%, but decreased as the S/VG ratio 

increased. However, depending upon the composition of the gas (hydrogen, nitrogen, and total 

hydrocarbon concentrations being the key parameters of interest), the breakpoint in CE 

performance occurred anywhere between a S/VG ratio of slightly less than 3 lb steam/lb vent 

gas to almost 6 lb steam/lb vent gas. This reinforces the previous observation that the CE 

breakpoint with respect to S/VG is strongly influenced by the concentrations of hydrogen, 

nitrogen, and total hydrocarbon in the vent gas. 

Displaying the combustion data versus the net heating value of the combustion zone gas 

(NHVczg) collapsed the data from the individual days and vent gas compositions to a reasonably 

consistent relationship. See Figure 2.1.3-2. There are still some minor differences in the shape 

of the combustion efficiency versus NHVczg relationship between the different test days that 

cannot be completely explained by the observed composition changes observed in the vent gas. 

The observed combustion efficiencies for the Series C tests also exhibit an increase in 

combustion efficiency as the NHVczg increases. While the data from the first day of testing, 

March 22nd, also exhibits this trend the observed combustion efficiencies were somewhat lower 

than would have been predicted by the trend presented by the rest of the data. Conditions 

during this test run were dissimilar from most of the other test conditions in that these runs were 

characterized by high hydrogen, relatively high nitrogen (approaching the 30% that was 

observed to cause issues with the vent gas flow meter previously), but low THC content in the 

vent gas (leading to lower CO2 concentrations in the hot flare plume). None of these 

observations necessarily invalidate the data, but they are believed to have contributed to the 

broader than expected scatter in the data. This scatter aside, combustion efficiencies of greater 

than 98% were still observed for test runs with combustion zone gas net heating values above 

200 BTU/SCF. 
April 1, 2011 

17 

Table 2.1.3-1. Series C Test Results Summary 

Test Number Start Time End Time Min 

# PFTIR 

scan 

avg.

NHVczg

(BTU/SCF) 

CE 

(%) 

H2 

(v%) 

THC 

(v%) 

N2 

(v%) 

S/VG 

(lb/lb) 

[EP-C-2.5(1)] 3/22/2010 

17:14 

3/22/2010 

17:38 24 9 205 97.3 53.2 27.5 17.1 2.60 

[EP-C-2.5(2)] 3/22/2010 

17:39 

3/22/2010 

19:16 37 28 198 94.3 54.0 26.6 17.0 2.69 

[EP-C-3.0(1)] 3/22/2010 

19:17 

3/22/2010 

20:08 51 18 154 92.5 47.1 23.9 26.9 3.05 

[EP-C-3.0(2)] 3/22/2010 

20:09 

3/22/2010 

20:39 30 9 143 93.6 45.1 26.1 26.7 3.17 

[EP-C-3.0(3)] 3/24/2010 

14:08 

3/24/2010 

14:18 10 2 178 99.7 44.4 41.8 11.4 3.33 

[EP-C-4.0(1)] 3/24/2010 

14:26 

3/24/2010 

14:35 09 2 154 99.3 43.2 43.2 11.3 4.06 

[EP-C-4.0(2)] 3/25/2010 

15:55 

3/25/2010 

16:16 21 5 127 99.2 36.9 36.0 25.4 3.90 

[EP-C-5.0(1)] 3/24/2010 

16:01 

3/24/2010 

16:11 10 5 128 99.2 44.1 42.4 11.0 5.09 

[EP-C-6.0(1)] 3/24/2010 

15:47 

3/24/2010 

15:58 11 5 109 96.8 44.8 41.7 10.8 6.19 

[EP-C-6.0(2)] 3/24/2010 

16:20 

3/24/2010 

16:31 11 4 114 94.1 44.5 42.0 10.7 5.87 

[EP-C-6.0(3)] 3/24/2010 

16:41 

3/24/2010 

16:52 11 5 112 90.9 44.6 42.2 10.3 6.09 

[EP-C-6.0(4)] 3/24/2010 

16:56 

3/24/2010 

17:07 11 3 108 99.3 44.5 42.6 10.3 6.34 

[EP-C-7.0(1)] 3/25/2010 

10:02 

3/25/2010 

10:16 14 3 74 87.9 46.9 26.4 25.0 6.92 

[EP-C-7.0(2)] 3/25/2010 

10:20 

3/25/2010 

10:32 12 4 81 95.9 48.0 28.4 22.0 6.72 

[EP-C-8.0(1)] 3/25/2010 

11:28 

3/25/2010 

11:37 9 3 85 95.9 51.7 33.1 13.7 7.81 
April 1, 2011 

18 
April 1, 2011 

19 

2.1.4 Test Series D, Mercury Cadmium Telluride (MCT) Detector 

Comparison 

Without a beam splitter IMACC could not use a MCT detector and an InSb detector at the same 

time. Since SDP has very limited means to control the composition of the EPF vent gas, it was 

also impractical to recreate test conditions identical to those that occurred when SDP collected 

data with the InSb detector. Given these constraints, the only way to compare the MCT detector 

to the InSb detector was to gather as many data points as practical with the MCT detector at 

similar, but not identical, conditions as occurred when data were gathered with the InSb 

detector, and then compare the two data sets. Figure 2.1.4-1 and Figure 2.1.4-1a depict the CE 

versus S/VG ratio data obtained during the detector comparison testing. These data are 

tabulated in Table 2.1.4-1. Figure 2.1.4-2 and Figure 2.1.4-2a depict the relationship between 

CE and NHVczg observed during Series D testing. Combustion efficiency data were calculated 

from the PFTIR data using the CO2 results from both the 765 cm-1 wave number and the 2080 

cm-1 wave number. Results at the 2080 wave number would be indicative of results achieved 

when the InSb detector was being used. Results at a wavenumber of 765 are indicative of the 

MCT detector. 

SDP conducted Series D testing on April 15 and 16, 2010. During the two MCT detector test 

days the range of measured vent gas compositions did not vary as much as during the longer 

InSb test campaigns (i.e., Series A, B, and C). However, the CE data obtained with the MCT 

detector exhibited a similar functional relationship versus both S/VG and NHVczg. The 

breakpoint where CE started to decline was at a S/VG ratio of approximately 4.0 and the flare 

was extinguished at a S/VG ratio of 5.0. The NHVczg required to achieve a CE greater than 

98.0% was approximately 150 BTU/SCF. These data are very consistent with data collected at 

high hydrogen and low nitrogen concentrations with the InSb detector. 
April 1, 2011 

20 

* The expanded scale graphs in this report depict the high combustion efficiency data at a larger scale to facilitate visual 

data analysis. However, the expanded scale graph excludes any CE data below 90%. The expanded scale graph

should be used in conjunction with the full scale graphs for a full representation of the subject data sets. 
April 1, 2011 

21 

Table 2.1.4-1. MCT Detector Comparison Series Test Result Summary 

Test 

Number 

Start 

Time 

End 

Time 

Mins 

# 

PFTIR 

scan 

avg.

NHVczg

(BTU/SCF) 

CE % 

@ 765 

(cm-1) 

CE % 

@2080 

(cm-1) 

H2 

(v%) 

THC 

(v%) 

N2 

(v%) 

S/V

G 

[EP-D2.0(MCT1)] 4/15 

12:44 

4/15 

13:15 31 14 207 99.3% 99.3% 62.30 21.20 12.77 2.21 

[EP-D3.0(MCT1)] 4/15 

10:28 

4/15 

10:59 31 14 111 98.6% 98.6% 61.68 20.97 13.29 3.65 

[EP-D4.0(MCT1)] 4/15 

11:09 

4/15 

11:39 30 14 131 97.6% 97.6% 63.05 21.11 12.34 4.32 

[EP-D5.0(MCT1)] 4/15 

11:46 

4/15 

12:17 31 14 113 97.0% 97.0% 63.06 21.15 12.05 5.21 

[EP-D4.0(MCT2)] 4/15 

13:34 

4/15 

14:05 31 15 137 97.1% 97.1% 55.30 22.71 18.90 3.64 

[EP-D5.0(MCT2)] 4/15 

12:22 

4/15 

12:32 10 0 124 0.00% 0.0% 63.39 21.05 11.78 5.06 

[EP-D2.0(MCT2)] 4/16 

10:28 

4/16 

11:01 33 16 199 98.9% 98.9% 52.95 19.38 24.37 2.13 

[EP-D3.0(MCT2)] 4/16 

11:09 

4/16 

11:46 37 18 160 98.0% 98.0% 54.92 19.56 22.52 2.85 

[EP-D4.0(MCT3)] 4/16 

11:58 

4/16 

12:29 31 15 132 95.2% 95.2% 55.70 19.28 22.13 4.01 

[EP-D5.0(MCT3)] 4/16 

12:58 

4/16 

13:07 9 0 119 0.0% 0.00% 55.21 20.07 21.77 4.88 

[EP-D4.5(MCT)] 4/16 

13:43 

4/16 

14:20 37 15 100 94.3% 94.0% 55.23 19.28 22.25 4.61 
April 1, 2011 

22 

* The expanded scale graphs in this report depict the high combustion efficiency data at a larger scale to facilitate 

visual data analysis. However, the expanded scale graph excludes any CE data below 90%. The expanded scale 

graph should be used in conjunction with the full scale graphs for a full representation of the subject data sets. 
April 1, 2011 

23 

2.2 Summary and Key Data Trends of Whole Data Set 

2.2.1 Visible Emissions 

The principal reason steam is added to the flare is to prevent visible emissions (e.g. smoking). 

The American Petroleum Institute (API) has developed suggested minimum values of steam to 

vent gas ratios needed to prevent smoking for various classes of vent gas compounds. These 

minimum suggested steam values have been published as part of API Standard 521, PressureRelieving and Depressuring Systems. Table 11 from API 521 has been reproduced as Table 

2.2.1-1 in this report. 

Table 2.2.1-1 Table 11 from API 521 – Suggested Steam Injection Rates 

The composition of the EPF vent gas is primarily low molecular weight paraffinic hydrocarbons 

and hydrogen. There are few olefinic compounds in the EPF vent gas and generally less than 

1v% of aromatic compounds. As such, this flare typically does not exhibit a high tendency to 

smoke. Since this flare has an online GC, as required by the Texas Commission on 

Environmental Quality (TCEQ) Highly Reactive Volatile Organic Compound (HRVOC) rule (30 

TAC 115, Subchapter H), API 521 suggested steam rates can be calculated directly from the 

online GC data, per Table 11 from API 521. The values for individual compounds in this table 

are listed as mass of steam per mass of hydrocarbon. API 521 ratios values for this study were 
April 1, 2011 

24 

computed by using Equation (1), which appropriately adjusts each ratio value for the total 

hydrocarbon content of the vent gas. 

 

 API 521 Suggest Steam Value = --------------------------------------------------- (Equation 1) 

 (hydrocarbon wgt. fraction of vent gas) 

Figure 2.2.1-1 illustrates the range of API 521 ratios values encountered at the EPF during the 

Section 114 Request testing. 

 

While there is some variability in the computed API 521 suggested steam ratio values, for the 

entire test period, the suggested API 521 steam ratios value ranged only from 0.1 -0.4 lb 

steam/lb vent gas. 

The lowest S/VG ratio achieved during the testing was a value of 0.33 lb steam/lb of vent gas, 

and the test S/VG ratios were always above the suggested API 521 ratio. As would be expected 

from Figure 2.2.1-1, at no point during the testing were visible emissions observed from the 

EPF. 
April 1, 2011 

25 

2.2.2 CE vs. S/VG Ratio 

Figure 2.2.2-1 and Figure 2.2.2-1a display the CE data as a function of S/VG ratio for all test 

points during the EPF Section 114 Request testing. While high CEs were observed at S/VG 

ratios of 1.0 lb steam/lb vent gas up to almost 6.0 lb/lb, significant deterioration of observed CE 

was also observed at S/VG ratios as low as 1.2-1.4 lb steam/lb vent gas. These data indicate 

that the composition of the vent gas (principally hydrogen, nitrogen, and total hydrocarbons 

concentrations) also significantly affect the S/VG ratio at which CE starts to decline. The 

following subsection addresses a parameter that accounts for both S/VG and vent gas 

composition, the combustion zone net heating value, and therefore, exhibits a more consistent 

correlation with CE than either S/VG ratio or vent gas composition alone. 

 
April 1, 2011 

26 

* The expanded scale graphs in this report depict the high combustion efficiency data at a larger scale to facilitate 

visual data analysis. However, the expanded scale graph excludes any CE data below 90%. The expanded scale 

graph should be used in conjunction with the full scale graphs for a full representation of the subject data sets. 
April 1, 2011 

27 

2.2.3 CE vs. NHVczg 

EPA suggested using the NHVczg parameter as a potential means to assess the impact of gas 

composition on the observed CE. Figure 2.2.3-1 and Figure 2.2.3-1a depict all calculated 

NHVczg values versus CE data from the EPF Section 114 Request testing in one graph. This 

figure illustrates that NHVczg exhibits a far more consistent relationship with CE than either the 

S/VG ratio or vent gas composition alone. 

These data indicate that a significant decline in CE occurs at a NHVczg between 100 and 150 

BTU/SCF at typical vent gas compositions (H2> 40v%). However, during the nitrogen purge 

portion of the CR-3 regeneration, when the nitrogen content of the vent gas can exceed 50v%, 

and the hydrogen content falls below 30v%, a significant decline in CE occurred at NHVczg

values between 150 and 200 BTU/SCF. Qualitatively, higher nitrogen concentrations will 

increase the NHVczg required to achieve a CE of greater than 98.0%, and higher hydrogen 

concentrations will tend to lower the NHVczg required to achieve a CE of 98.0%. However, within 

the relatively wide range of nitrogen and hydrogen concentrations encountered in these tests the 

NHVczg required to achieve a CE of 98.0% varied between 150-200 BTU/SCF. 
April 1, 2011 

28 

* The expanded scale graphs in this report depict the high combustion efficiency data at a larger scale to facilitate 

visual data analysis. However, the expanded scale graph excludes any CE data below 90%. The expanded scale 

graph should be used in conjunction with the full scale graphs for a full representation of the subject data sets. 
April 1, 2011 

29 

2.3 Factors Influencing Test Results 

2.3.1 EPF Vent Gas Flow Measurements 

2.3.1.1 EPF GE Panametric Flow Issues 

Prior to beginning the EPA 114 Request testing, a GE Field Service Technician made a site visit 

to Deer Park and verified that the GE Panametric GF 868 flow meter was responding correctly 

and that all flow meter parameters were within acceptable ranges. Further, SDP had 

discussions with senior GE technical support for these meters to discuss the impact of high 

nitrogen content on observed results from the meter. Although GE mentioned that the algorithm 

used to convert volumetric flow to mass flow is impacted by variable nitrogen conditions, GE 

asserted that the volumetric flows determined from the flow meter should be accurate and 

unaffected by high nitrogen contents. Since Deer Park uses the data from the online HRVOC 

GC to convert the volumetric flows into mass flows, the existing GE flow meter installation was 

deemed fit for purpose for the upcoming tests.

To achieve the hydrogen concentrations in the EPF vent gas specified for the Series A tests, 

SDP had to conduct EPF Series A testing during the nitrogen purge portion of the CR-3 

regeneration cycle. The high nitrogen flow from the CR-3 regen cycle dilutes the hydrogen in 

the EPF vent gas stream sufficiently to meet the hydrogen concentration requirements for the 

Series A tests. SDP conducted the first Series A test on March 29, 2010. The measured EPF 

mass flows during this test remained relatively constant during the nitrogen purge cycle, and did 

not exhibit the flow increase that was expected based on readings from CR-3 unit 

instrumentation. Standard operating procedure at the CR-3 unit is to establish a nitrogen purge 

flow of 3-4 MMSCFD (~9,000-12,000 lb/hr N2), which is routed to the EPF. 

The next Series A test did not occur until April 13, 2010. During the CR-3 nitrogen purge that 

day, the Panametrics flow meter indicated a very low flow to the EPF (100-500 lb/hr), yet CEs of 

greater than 98% were observed at apparent S/VG ratios in excess of 30:1. SDP concluded 

from these instrument readings that the GE Panametric flow readings must be in error when 

nitrogen concentrations in the EPF line were greater than 30v%. 

For the high nitrogen test cases encountered during CR-3 regenerations (N2 concentrations 

>30%v), vent gas flow estimates generated by using EPF baseline flow estimates and measured 

flows to the flare from the CR-3 unit were used in the resulting data analysis (S/VG and CZGNHV

calculations). These flow estimates yielded results that were 1) consistent with the amount of 

nitrogen used in the CR-3 regeneration process, 2) yielded S/VG ratio when the flare was 

extinguished that were consistent with theoretical calculation of the onset of an incombustible 

mixture, and 3) were also in line with flows measured with the subsequently installed 22” flow 

sensors. Based upon the agreement of this method with the newly installed longer flow sensor, 

the process instrumentation at CR-3, and the fact that S/VG ratios calculated from this method 

were consistent with when combustion theory would predict the flare to be extinguished, SDP 

believes that flows adjusted using the CR-3 Instrumentation Method are a reasonably accurate 

representation of the flow to the EPF when the nitrogen concentration in the vent gas exceeded 

30%v. Therefore, when the nitrogen concentration in the EPF vent gas was under 30% the 

flows from the existing EPF flow sensors were used. When the nitrogen concentration was 

above 30%, flows were adjusted by using estimates of the EPF baseline flow and adding 

measured flows from the CR-3 unit to the EPF header. Sections 2.3.1.2-4 describe the analysis 

methods used to arrive at this conclusion. As previously mentioned all data points calculated 

from adjusted flows are depicted as open symbols in this report. Data points calculated using 

the existing ultrasonic time of flight flow sensors are represented as solid symbols. Similarly, 
April 1, 2011 

30 

data generated from estimated flows are tabulated in red, while data calculated from the existing 

flow meters are tabulated in black. 

2.3.1.2 Corrective Actions 

Once SDP determined that the flow meter was not providing accurate flow rate data at vent gas 

nitrogen concentrations greater than 30v%, SDP investigated and implemented corrective 

actions. GE technical support personnel informed SDP that “stratification” of vent gas 

components had been observed in a limited number of prior applications where there were large 

differences in the molecular weight of component gases. 

The Deer Park GE Panametric Model GF868 installation is a standard “Bias 90” configuration. 

In this configuration the sensors are positioned in the top quadrant of the pipe flow (e.g. top 

insertion to a depth of 9” in a total pipe diameter of 36”). GE suggested building longer flow 

sensors and to installing them in the bottom quadrant of the EPF vent header (e.g. sensor 

inserted from the top to a depth of 22” out of total pipe diameter of 36”). SDP installed the 

longer sensors on June 10, 2010. 

Figure 2.3.1.2-1 depicts hourly average plant data from the process computers for a 12-day 

period from June 3rd to June 12th. Ten CR-3 regeneration cycles occurred over these 12 days. 

The flow response differences between the 9” sensor insertion and 22” sensor insertion 

configurations are apparent in the data. Prior to the June 10th sensor installation, observed flows 

during the N2 purge portion of the CR-3 regeneration cycle could be characterized by either 

constant flow or in some cases diminishing flows. After installating the longer flow sensor, SDP 

observed the expected increase in flow during CR-3 N2 purge cycles. The apparent spikes in 

S/VG ratio observed during vitrually every CR-3 regenaration cycle with the old sensor were also 

absent after installation of the new longer flow sensor. 
April 1, 2011 

31 

2.3.1.3 Flow Validation from New Configuration/ Adjustment of Prior Data from Old 

Configuration 

While Figure 2.3.1.2-1 illustrates the apparent differences in the responses observed from the 

two different flow sensors, it does not speak to the accuracy of one flow sensor configuration 

versus the other. To validate the flow response of the new longer sensor and develop a basis 

for adjusting flow measurements during the test to reflect flow conditions, SDP considered two 

alternate methods of determining flow to the EPF to estimate flows in the EPF vent gas line 

during high N2 periods. 

N2 Material Balance. Assuming the baseline flow to the EPF (all flow to the EPF header except 

that from the CR-3 unit) varies on a longer time scale than the typical CR-3 N2 purge cycle (3-4 

hours), then both the baseline flow to the flare and the N2 concentration of that baseline flow can 

be approximated by a linear interpolation of the values of each of these parameters at the 

beginning and end of the CR-3 N2 purge cycle. Since the gas from the CR-3 during the N2

purges is 100v% N2, and the N2 concentration of the combined flow to the EPF is measured by 

the online HRVOC GC, the volume of N2 coming from CR-3 to the EPF header, and therefore 

the total flow to the EPF header, can be calculated from a system of two equations with two 

unknowns (CR-3 N2 flow and Total EPF Flow) constructed from a material balance around this 

system. 

Figures 2.3.1.3-2, 2.3.1.3-3, and 2.3.1.3-4 compare the results from the N2 Material Balance to 

the flow rate measured by the longer sensor for first three successive CR-3 regenration cycles 

after the installation of the longer sensors. 

The shape of the curve of the EPF flow calculated from the N2 Material Balance over time very 

closely matches the shape of the curve of the flow measured by the longer 22” flow sensor over 

time. However, the amplitude of the N2 Material Balance flow rate curve is somewhat higher 

than the flow rate curve measured by the 22” probe. To quantify the magnitude of this variation, 

SDP performed a minute by minute integration of the area under the two curves. The integrated 

flow for the N2 Material Balance was 105.9%, 98.4% and 109.8% of the integrated flow 

measured by the 22” sensor, respectively, for each of the examples shown. 

CR-3 Process Instrumentation. Alternatively, SDP estimated EPF flows using the same EPF 

basline flow assumption -- that the base load flow remains constant or changes linerally during 

the N2 purge cycle. Adding the N2 flow add to the EPF, as measured from the CR-3 

instrumentation, to the EPF estimated base flow resulted in the total vent gas flow to the EPF. 

During the CR-3 regeneration cycle, flow from the CR-3 Caustic Water Wash Column (CWWC) 

is routed to the EPF header. This part of the regeneration cycle commences with a hydrogen 

purge and finishes with a nitrogen purge. The flow of H2 and N2 to the regenration loop is 

continuously monitored by CR-3 instrumentation. Because the regeneration loop is a closed 

system, the amount of H2 and N2 being added to the loop is equivalent to the amount of gas 

exiting the loop to the EPF header. These flows determined from CR-3 instrumentation were 

used to estimate the flow from CR-3 to the EPF header. 

After evaluating process data for flare flows outside the purge cycle, SDP assumed that the 

baseline flow to the EPF header from other units varied linearly during the CR-3 regeneration 

cylce. SDP estimated the baseline by taking the last Panametrics flow value prior to the CWWC 

being opened to the flare and the flow value point after flow from the CR-3 CWWC was 

stopped. SDP used a linear interpolation for all intermediate baseline flow values between these 

two points. The total flow to the EPF was then estimated as the baseline flow plus the 

measured flows from the CR-3 CWWC. The flows calculated from this procedure are also 

illustrated on Figures 2.3.1.3-2, 2.3.1.3-3, and 2.3.1.3-4. 
April 1, 2011 

32 

Figures 2.3.1.3-2, 2.3.1.3-3, and 2.3.1.3-4 illustrate that the EPF flows determined from the CR3 flow instrumentation estimation are consistent with the values measured by the longer GE 

Panametric flow sensors. The shape of the flow curve determined from the CR-3 

instrumentation is slightly more square than that observed at the sensor, and exhibits a slight 

time lag. This is to be expected because of the difference in measurement points. SDP also did 

a minute-by-minute integration for the CR-3 Instrumentation EPF flow validation method. The 

integrated flows were 100.2%, 101.2% and 105.6% of the flow measured by the newly installed 

22” GE Panametric flow sensors.

These data indicate that the flows measured by the new sensor positioned at 22” from the top of 

the 36” EPF header are consistent with the flows calculated using two independent methods of 

estimating the EPF vent gas flow when high N2 concentration are present. The EPF flow 

instrumentation configuration utilizing the longer sensors appears to provide representative flows 

in the EPF header, even under high nitrogen conditions, with acceptable accuracy (e.g. 

estimated to be better than +5%). 
April 1, 2011 

33 
April 1, 2011 

34 
April 1, 2011 

35 
April 1, 2011 

36 

2.3.1.4 Adjustment of EPF flows during High N2 Test Periods 

SDP calculated adjusted values for the test data when the nitrogen concentation in the vent gas 

exceeded 30v% using both the N2 Material Balance method and the CR-3 Process 

Instrumentation method, discussed above. The N2 Material Balance method gave results that 

were inconsistent with other measurements. During both the March 29 and April 13 tests, the 

average N2 flow determined from the material balance method was below the flow expected 

based on the rate of nitrogen addition to the CR-3 process. In addition, the dilution calculated 

from the flows adjusted via the N2 Material Balance method would have yielded incombustile 

mixtures, as calculated from standard mixing rules for combustible mixtures, yet the PFTIR 

instrumentation measured high CE values for these tests. While there is a modest level of 

uncertainty associated with the mixing constants used to calculate the combustion envelope for 

the mixure of a combustible gas with a incombustile diluent (steam), it is unlikely that the S/VG 

ratios and NHVCZG calculated from EPF flows calculated from the N2 Material Balance method 

are accurate for the high nitrogen concentration tests. 

For the high nitrogen cases encountered during CR-3 regenerations, using EPF flows estimated 

from the estimated EPF baseline flow and measured flows to the flare from the CR-3 unit yielded 

results that were 1) consistent with the amount of nitrogen used in the CR-3 regeneration 

process, 2) yielded steam to vent gas ratio when the flare was extinguished that were 

consistent with theoretical calculation of the onset of an incombustible mixture, and 3) were also 

in line with flows measured with the newly installed 22” flow sensors. SDP determined EPF 

flows for periods when the nitrogen concentration exceeded 30v% by adding the estimated EPF 

baseline flow to the flows from the CR-3 unit to the EPF, determined from CR-3 instrumentation, 

to determine the total flow to the EPF. Based upon the agreement of this method with the 

newly installed longer flow sensor, the process instrumentation at CR-3, and the fact that steam 

to vent gas ratios calculated from this method were consistent with when combustion theory 

would predict the flare to be extinguished, SDP believes that flows adjusted using the CR-3 

Instrumentation Method are a reasonably accurate representation of the flow to the EPF when 

the nitrogen concentration in the vent gas exceeded 30%v. When the nitrogen concentration 

was under 30% the flows from the existing EPF flow sensor were used. 

2.3.2 Wind Effects and PFTIR Aiming Issues 

SDP obtained 5-minute average weather data (temperature, pressure, dew point, wind direction, 

wind speed, relative humidity, and rainfall) from a local weather station. For each day the 

prevailing wind direction has been characterized by producing a wind rose for that day. These 

figures are presented in Appendix 5.2 along with the tabulated 5-minute average data. 

Recently, another refiner conducting similar PFTIR testing on another flare reported significant 

issues positioning the PFTIR telescope in the appropriate position to collect representative 

data.3 These aiming issues were in large part a function of prevailing wind conditions with 

respect to where the PFTIR telescope could be sited. While prevailing winds and siting criteria 

are important considerations in developing the PFTIR test plan for conducting CE 

measurements of a flare, SDP encountered few problems during the testing of the EPF in 

positioning the PFTIR telescope to collect representative data. SDP was able to regularly aim 

the PFTIR telescope at a point approximately one flame length from the flare flame. 

 

3

“Performance Test of a Steam-Assisted Elevated Flare with Passive FTIR,” Marathon 

Petroleum Company, LLC, Texas Refining Division, 502 10th Street South, Texas City, Texas 

77590, prepared by Clean Air Engineering, Inc. Project No. 10810. 
April 1, 2011 

37 

Problems were reported in other studies when strong winds were directly aligned with the 

relative positioning of the PFTIR telescope. During the EPF tests, winds aligned with the PFTIR 

telescope and the EPF on only a few occasions, and on each of these occasions, winds were 

very light. Therefore, IMACC did not report problems aiming the telescope at the desired 

location in the flare plume. 

2.3.3 PFTIR Variability - Confidence Intervals for Observed Combustion 

Efficiency Mean Values 

SDP calculated the 95th and 99th percentile confidence intervals for the mean CE of each test. 

See Figures 2.3.3-1, 2.3.3-2, 2.3.3-3, 2.3.3-4 and Table 2.3.3-1, 2.3.3-2, 2.3.3-3, 2.3.3-4. These 

data illustrate that the variability in the observed CEs tends to be less at stable combustion 

conditions and high CEs, but the variability increases as combustion conditions become more 

unstable. At high CEs the confidence interval is generally within + 0.5%, but as combustion 

conditions becomes more unstable the confidence interval increases up to + 50%. This high 

degree of variability is both a function of the high degree of variability in the combustion process 

at these conditions and the higher degree of uncertainty in the PFTIR technique under these 

conditions. 
April 1, 2011 

38 

94.00%

95.00%

96.00%

97.00%

98.00%

99.00%

100.00%

Combustion Efficiency

A-Series Test

 

Figure 2.3.3-1. Series A Test Data Variability 
April 1, 2011 

39 

10.00%

30.00%

50.00%

70.00%

90.00%

110.00%

130.00%

150.00%

170.00%

Combustion Efficiency

B-Series Test

Figure 2.3.3-2. Series B Test Data Variability 
April 1, 2011 

40 

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

110.00%

120.00%

130.00%

Combustion Efficiency

C-Series Test

Figure 2.3.3-3. Series C Test Data Variability 
April 1, 2011 

41 

93.00%

94.00%

95.00%

96.00%

97.00%

98.00%

99.00%

100.00%

Combustion Efficiency

MCTSeries Test

Figure 2.3.3-4. Series D Test Data Variability
April 1, 2011 

42 

Table 2.3.3-1. Series A Test Data Variability 

Test Date Test Run 

Average 

Combustion 

Efficiency 

95% 

Confidence 

Limit 

99% 

Confidence 

Limit 

Sample 

Size 

Standard 

Deviation 

3-29, 13:30-14:23 [EP-A-2.0(1)] * 99.06% ± 0.24% ± 0.34% 13 0.40%

3-29, 11:37-12:20 [EP-A-3.0(1)] *97.44% ± 0.41% ± 0.59% 10 0.58%

3-29, 12:21:12:51 [EP-A-4.0(1)] *97.57% ± 0.28% ± 0.41% 8 0.34%

3-29, 13:10-13:15 [EP-A-5.0(1)] *97.69% NA NA 1 NA 

3-29, 13:16-13:22 [EP-A-5.0(2)] *96.79% NA NA 1 NA 

4-13, 9:30-10:04 [EP-A-6,000(1)] *98.90% ± 0.3% ± 0.41% 16 0.57%

4-13, 10:07-10:39 [EP-A-5,500(1)] *98.77% ± 0.21% ± 0.29% 15 0.39%

4-13, 10:51-11:22 [EP-A-10,000(1)] *98.57% ± 0.11% ± 0.16% 16 0.22%

4-13, 11:32-12:03 [EP-A-12,500(1)] *97.48% ± 0.35% ± 0.48% 16 0.66%

4-13, 12:51-13:11 [EP-A-10,000(1)] 96.85% ± 1.24% ± 1.78% 10 1.73%

*

Vent gas flow was adjusted for this test. See discussion in Section 2.3.1. 

Table 2.3.3-2. Series B Test Data Variability 

Test Date Test Run 

Average 

Combustion 

Efficiency 

95% 

Confidence 

Limit 

99% 

Confidence 

Limit 

Sample 

Size 

Standard 

Deviation 

3-30, 9:55-10:38 [EP-B-51(1)] 97.30% ± 0.45% ± 0.61% 18 0.91%

3-30, 10:40-11:30 [EP-B-51(2)] 97.51% ± 0.62% ± 0.86% 18 1.26%

4/1 08:48- 09:16 [EP-B-61(1)] *98.63% ± 0.21% ± 0.3% 13 0.36%

4/1 09:17- 09:46 [EP-B-61(2)] *99.04% ± 0.16% ± 0.22% 15 0.30%

4/1 10:17- 10:50 [EP-B-31(3)] *97.11% ± 0.46% ± 0.64% 16 0.87%

4/1 10:51- 11:28 [EP-B-31(2)] *98.62% ± 0.46% ± 0.63% 19 0.96%

4/1 12:32- 13:16 [EP-B-51(HiFlo1)] *98.77% ± 0.09% ± 0.12% 22 0.21%

4/1 13:17- 13:53 [EP-B-51(HiFlo2)] *98.76% ± 0.08% ± 0.11% 18 0.16%

4-6, 10:00-10:16 [EP-B-61-2i] 97.35% ± 1.23% ± 1.82% 8 1.47%

4-6,10:17-10:42 [EP-B-61-2ii] 57.08% ± 28.94% ± 40.58% 13 47.90%

4-6, 10:43-10:53 [EP-B-61-2iii] 79.83% ± 41.05% ± 64.4% 6 39.12%

4-6, 10:54-11:14 [EP-B-61-2iv] 77.89% ± 29.37% ± 42.19% 10 41.06%

4-6, 11:16-11:24 [EP-B-61-3i] 98.71% ± 1.68% ± 3.88% 3 0.68%

4-6, 11:32-11:49 [EP-B-61-3ii] 98.92% NA NA 1 NA 

4-6, 11:50-11:58 [EP-B-61-3iii] 97.53% ± 1.15% ± 2.11% 4 0.72%

4-6, 11:59-12:09 [EP-B-61-3iv] 97.12% ± 1.01% ± 1.68% 5 0.82%

*

Vent gas flow was adjusted for this test. See discussion in Section 2.3.1. 
April 1, 2011 

43 

Table 2.3.3-3 Series C Test Data Variability 

Test Date Test Run 

Average 

Combustion 

Efficiency 

95% 

Confidence 

Limit 

99% 

Confidence 

Limit 

Sample 

Size 

Standard 

Deviation 

3-22, 17:14-17:38 [EP-C-2.5(1)] 97.29% ± 0.32% ± 0.47% 9 0.28%

3-22, 17:39-19:16 [EP-C-2.5(2)] 94.25% ± 1.87% ± 2.53% 28 0.77%

3-22, 19:17-20:08 [EP-C-3.0(1)] 92.49% ± 22.44% ± 30.83% 18 22.81%

3-22, 20:09-20:39 [EP-C-3.0(2)] 93.63% ± 2.86% ± 4.16% 9 1.01%

3-24, 14:08-14:18 [EP-C-3.0(3)] 99.67% ± 0.47% ± 2.38% 2 0.05%

3-24, 14:26-14:35 [EP-C-4.0(1)] 99.27% ± 2.31% ± 11.6% 2 0.26%

3-25, 15:55-16:16 [EP-C-4.0(2)] 99.21% ± 0.12% ± 0.2% 5 0.10%

3-24.16:01-16:11 [EP-C-5.0(1)] 99.19% ± 0.63% ± 1.05% 5 0.46%

3-24.15:47-15:58 [EP-C-6.0(1)] 96.78% ± 0.52% ± 0.86% 5 0.60%

3-24, 16:20-16:31 [EP-C-6.0(2)] 94.15% ± 3.02% ± 5.55% 4 1.90%

3-24, 16:41-16:52 [EP-C-6.0(3)] 90.88% ± 3.03% ± 5.03% 5 2.44%

3-24, 16:56-17:07 [EP-C-6.0(4)] 99.33% ± 0.29% ± 0.67% 3 0.12%

3-25, 10:02-10:16 [EP-C-7.0(1)] 87.86% ± 17.26% ± 39.83% 3 6.95%

3-25, 10:20-10:32 [EP-C-7.0(2)] 95.88% ± 2.73% ± 5.02% 4 1.72%

3-25, 11:28-11:37 [EP-C-8.0(1)] 95.90% ± 3.41% ± 7.86% 3 0.79%

Table 2.3.3-4 Series D Test Data Variability 

Test Date Test Run 

Average 

Combustion 

Efficiency 

95% 

Confidence 

Limit 

99% 

Confidence 

Limit 

Sample 

Size 

Standard 

Deviation 

4-15, 12:44 -13:15 [EP-D-2.0(MCT1)] 99.34% ± 0.1% ± 0.15% 14 0.19%

4-15, 10:28 -10;59 [EP-D-3.0(MCT1)] 98.59% ± 0.16% ± 0.22% 14 0.28%

4-15, 11:09-11:39 [EP-D-4.0(MCT1)] 97.60% ± 0.14% ± 0.2% 14 0.25%

4-15, 11:46-12:17 [EP-D-5.0(MCT1)] 97.03% ± 0.15% ± 0.2% 14 0.26%

4-15, 13:34-14:05 [EP-D-4.0(MCT2)] 97.07% ± 0.35% ± 0.48% 15 0.63%

4-16, 10:28-11:01 [EP-D-2.0(MCT2)] 98.60% ± 0.1% ± 0.14% 16 0.20%

4-16, 11:09-11:46 [EP-D-3.0(MCT2)] 98.02% ± 0.22% ± 0.3% 18 0.45%

4-16, 11:58-12:29 [EP-D-4.0(MCT3)] 95.22% ± 0.21% ± 0.29% 15 0.39%

4-16, 13:43-14:20 [EP-D-4.5(MCT)] 94.31% ± 0.48% ± 0.67% 15 0.88%

2.3.4 PFTIR Component Errors 

IMACC provided an error value for each species detected by the PFTIR. This error is the 

residual error calculated when the observed spectra obtained during the test is fit to the 

reference spectra using a Classical Least Squares (CLS) fitting routine. This error represents 

the “goodness of fit” of the observed data to the reference spectra. As such, it represents the 

minimum error in the measurement, not the actual error of the measurement. Other sources of 
April 1, 2011 

44 

error potentially exist in selecting the reference spectra, determining the sky radiance spectrum, 

plume transmittance, etc. These types of systematic error can produce additional bias and 

uncertainty in the observed values on top of the component error present in fitting the radiance 

spectrum. The potential bias introduced by the aforementioned background radiance 

measurements is difficult to quantify, but can be significantly reduced by using the hot cell 

calibration method employed in this study. Any bias introduced by the determination of the 

background radiance should be detected during the hot cell calibration and the appropriate 

adjustments made as a result. 

As the PFTIR data represent the mass of each component along the line of sight of the 

instrument, conversion to a concentration requires that a plume length be estimated. In strong 

winds, there can be considerable error in this value due to bending of the plume. While these 

effects generally will cancel out in CE calculations (e.g. same relative error in concentration 

determination exists in both the numerator and the denominator), the error in data expressed as 

a concentration can be significant due to poor path length assumptions. Consequently, the 

errors in data expressed as concentrations can be considerably larger than errors in data 

expressed as CE values. 

2.3.5 PFTIR Hot Cell Calibration 

After recent PFTIR flare testing studies, IMACC tested the PFTIR instrument in the laboratory by 

placing a hot cell of known path length and containing known gas composition in the PFTIR 

path. This method was used as a check on procedures utilized to develop the background 

radiance spectra. For the testing done at the Deer Park EPF, hot cell calibrations were done in 

the field each day as an additional check on the PFTIR data measurement protocols. In all 

cases, IMACC determined correction factors for each species detected from these hot cell 

calibrations. In most cases the results obtained from these hot cell calibrations were well within 

the normal EPA QA/QC acceptance protocols (e.g. 70% - 130% of the known value). However, 

these correction factors were applied to all spectra collected each day (e.g. applied to values 

within normal acceptance criteria as well as those outside the 70-130% window). This hot cell 

calibration step is an additional step utilized to minimize any bias and uncertainty associated 

with determining the background radiance parameters utilized to process the PFTIR data. A 

more detailed description of the hot cell calibration is available in Appendix 5.1. 

2.3.6 Validation of Online Gas Composition Analyzers 

Throughout all the test series, the online vent gas analyzers were checked by taking hourly 

composite vent gas samples into evacuated summa canisters. SDP had the canisters analyzed 

by an offsite laboratory. Analytical results for these canisters are presented in Appendix 5.3, 

along with the Chain of Custody documentation for these samples. 

In all, SDP collected 27 summa canisters samples during the test period. Table 2.3.6-1 

illustrates the agreement between the hourly composite samples analyzed at an outside 

laboratory and the hourly average data from the online analyzers for the same period. In all 

cases a small amount of air was drawn into the evacuated summa canisters, as evidenced by 

the bias in the oxygen and nitrogen values between the online analyzers to that of the summa 

canisters. In 20 of the 27 canisters, the amount of air leakage was calculated to be less than 5% 

of the sample. All the summa canister hydrocarbon concentration data in Table 2.3.6-1 were 

adjusted upward to account for the dilution of the small amount of air that was drawn into the 

canister. Conversely, the nitrogen and oxygen values were adjusted downward to account for 

the air that was drawn into the canister. For the major components (H2, N2, and CH4) the 

agreement of the data was well within standard EPA QA/QC acceptance protocols (e.g. relative 
April 1, 2011 

45 

difference less than + 20%) and, in fact, in most cases was much better than this. The relative 

difference for some of the minor components was at times somewhat greater, but these 

differences would have only minor impact on the combustion properties of the vent gas. Given 

the agreement between the online analyzers and the summa canister data, the vent gas 

composition data obtained from the online analyzers was used exclusively when vent gas 

composition data was needed. 
April 1, 2011 

46 

Table 2.3.6-1. Comparison of Online Vent Gas Composition Analyzers to Summa Canister Samples 

SPL SPL SPL SPL

EPF EQ2 HRVOC EPF 4163 SN HRVOC EPF 3862 HRVOC EPF 4166 HRVOC EPF 4345 HRVOC EPF 4165 HRVOC EPF 4315 HRVOC

Component Units

03/22/10 

@08:00-

09:00

03/22/10 

@08:00-

09:00

Relative 

accuracy

03/24/10 

@ 14:07-

15:07

03/24/10 

@ 14:07-

15:07

Relative 

accuracy

03/24/10 

@ 15:07-

16:07

03/24/10 

@ 15:07-

16:07

Relative 

precision

03/24/10 

@ 16:07-

17:07

03/24/10 

@ 16:07-

17:07

Relative 

accuracy

03/25/10 

@ 10:02-

11:02

03/25/10 

@ 10:02-

11:02

Relative 

accuracy

03/25/10 

@ 11:02-

12:02

03/25/10 

@ 11:02-

12:02

Relative 

accuracy

03/25/10 

@12:02-

13:02

03/25/10 

@12:02-

13:02

Relative 

accuracy

Hydrogen MOLE% 41.53 43.65 4.86 41.53 43.65 4.86 41.20 44.37 7.15 41.66 44.47 6.32 45.43 48.56 6.43 48.62 51.52 5.63 34.93 37.96 7.99

Oxygen MOLE% 0.04 0.04 -0.77 0.04 0.04 -0.77 0.04 0.04 -1.82 0.04 0.04 -2.13 0.02 0.02 -1.20 0.01 0.01 -0.97 0.02 0.01 -1.34

Nitogen MOLE% 12.25 11.27 -8.72 12.25 11.27 -8.72 12.89 11.22 -14.91 12.27 10.58 -16.02 22.13 20.92 -5.78 14.92 13.89 -7.36 41.33 38.58 -7.12

Methane MOLE% 31.99 30.34 -5.45 31.99 30.34 -5.45 33.03 30.54 -8.15 31.32 29.75 -5.30 19.55 17.84 -9.54 22.49 20.80 -8.17 12.98 12.24 -6.03

Ethylene MOLE% NIL 0.00 NIL 0.00 NIL 0.00 NIL 0.00 NIL 0.00 NIL 0.00 - NIL 0.00

Ethane MOLE% 3.10 2.98 -4.36 3.10 2.98 -4.36 3.14 3.07 -2.36 3.30 3.19 -3.35 3.68 3.45 -6.50 4.45 4.19 -6.08 3.73 3.62 -2.96

Acetylene MOLE% 0.00 0.00 0.00 0.00 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Propylene MOLE% 0.08 0.07 0.08 0.07 -13.72 0.05 0.05 -6.55 0.07 0.08 15.03 0.05 0.05 -0.21 0.05 0.05 10.70 0.02 0.03 43.38

Propane MOLE% 2.36 2.27 -3.99 2.36 2.27 -3.99 2.04 2.33 12.22 2.29 2.51 8.62 1.94 2.10 7.76 1.96 2.15 8.81 1.72 1.94 11.29

Butene1&Isobutane MOLE% 0.00 0.11 100.00 0.00 0.11 100.00 0.00 0.09 100.00 0.00 0.15 100.00 0.00 0.03 100.00 0.00 0.03 100.00 0.00 0.02 100.00

Trans2Butene MOLE% 0.00 0.05 0.00 0.05 100.00 0.00 0.05 100.00 0.00 0.08 100.00 0.00 0.00 0.00 0.00 0.00 0.00

Cis2Butene MOLE% 0.00 0.04 0.00 0.04 100.00 0.00 0.04 100.00 0.00 0.07 100.00 0.00 0.00 0.00 0.00 0.00 0.00

13BD MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

IsoButane MOLE% 1.22 1.10 -11.41 1.22 1.10 -11.41 1.04 1.11 5.77 1.22 1.26 3.24 1.00 1.02 2.28 1.00 1.02 2.04 0.77 0.82 6.15

Butane MOLE% 0.00 0.90 100.00 0.00 0.90 100.00 0.00 0.93 100.00 0.00 1.06 100.00 0.00 0.87 100.00 0.00 0.88 100.00 0.00 0.73 100.00

C5+ MOLE% 0.00 3.92 100.00 0.00 3.92 100.00 0.00 2.73 100.00 0.00 3.01 100.00 0.00 3.01 100.00 0.00 3.34 100.00 0.00 2.41 100.00

Hydrogen Sulfide MOLE% 2.41 1.71 -40.86 2.41 1.71 -40.86 2.37 1.74 -36.52 2.89 2.11 -37.16 2.50 1.58 -58.62 2.66 1.56 -70.76 1.61 1.20 -34.78

Water MOLE% 0.00 0.00 0.00 0.00 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Carbon Dioxide MOLE% 1.23 1.17 -5.35 1.23 1.17 -5.35 1.25 1.16 -7.06 1.17 1.08 -7.50 0.59 0.56 -5.87 0.59 0.56 -5.09 0.44 0.43 -3.49

Carbon Monoxide MOLE% 0.00 0.00 0.00 0.00 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Benzene MOLE% 0.53 0.35 0.53 0.35 -51.52 0.36 0.35 -2.06 0.45 0.35 -27.79 0.44 0.36 -22.44 0.45 0.35 -28.40 0.40 0.32 -26.36

Toluene MOLE% 0.11 0.14 0.11 0.14 19.30 0.07 0.14 49.12 0.10 0.15 31.27 0.09 0.12 29.44 0.10 0.15 32.54 0.07 0.12 41.63

Ethylbenzene MOLE% 0.01 0.01 0.01 0.01 54.36 0.00 0.01 73.67 0.00 0.01 67.99 0.00 0.01 64.00 0.00 0.01 67.79 0.00 0.01 66.93

Xylene's MOLE% 0.02 0.01 0.02 0.01 -52.18 0.01 0.01 10.17 0.02 0.02 -14.65 0.01 0.02 6.23 0.02 0.02 -12.00 0.01 0.01 8.09

Air Ingress v% 30.6% 0.8% 1.8% 2.1% 1.2% 1.0% 1.3%
April 1, 2011 

47 

Table 2.3.6-1. Comparison of Online Vent Gas Composition Analyzers to Summa Canister Samples (cont'd) 

SPL SPL SPL SPL SPL SPL SPL

EPF 4402 HRVOC EPF 3861 HRVOC EPF 1144 HRVOC EPF 3621 HRVOC EPF 1149 HRVOC EPF 1143 EPF 3622 HRVOC

HRVOC

Component Units

Hydrogen MOLE% 21.93 24.02 8.72 50.45 57.18 11.77 51.78 57.12 9.34 51.53 61.77 16.58 31.42 36.31 13.48 45.28 51.11 11.41 53.56 61.10 12.34

Oxygen MOLE% 0.01 0.01 -1.63 0.05 0.05 -4.72 0.07 0.07 -3.35 0.01 0.01 -13.99 0.02 0.02 -1.27 0.02 0.02 -2.45 0.04 0.04 -1.89

Nitogen MOLE% 53.00 50.30 -5.37 15.19 13.67 -11.11 15.09 13.28 -13.67 23.78 12.96 -83.56 49.59 46.33 -7.04 35.33 32.54 -8.58 16.35 14.70 -11.23

Methane MOLE% 17.87 17.57 -1.70 12.83 10.87 -18.04 11.81 10.90 -8.38 10.94 11.59 5.58 7.08 6.79 -4.39 6.22 5.48 -13.44 11.90 10.59 -12.45

Ethylene MOLE% NIL 0.00 - 0.08 0.00 -21441.66 0.07 0.00 -9384.82 0.09 0.00 -17420.07 0.81 0.00 -68927.29 1.13 0.00 -70995.90 0.98 0.00 -23971.33

Ethane MOLE% 1.82 1.89 3.81 4.02 3.94 -2.04 4.02 3.87 -3.84 4.14 4.15 0.23 2.32 2.29 -1.40 2.11 2.00 -5.52 3.20 3.10 -3.04

Acetylene MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Propylene MOLE% 0.02 0.03 28.78 0.06 0.04 -31.03 0.05 0.05 -19.00 0.04 0.04 -14.37 0.30 0.04 -597.62 0.42 0.05 -666.95 0.42 0.06 -646.71

Propane MOLE% 1.26 1.47 13.88 3.61 3.11 -16.13 3.48 3.12 -11.53 2.94 2.62 -12.02 2.11 1.94 -8.68 2.08 1.84 -12.78 2.42 2.24 -8.09

Butene1&Isobutane MOLE% 0.00 0.01 100.00 0.00 0.04 100.00 0.00 0.04 100.00 0.00 0.02 100.00 0.00 0.03 100.00 0.00 0.03 100.00 0.00 0.02 100.00

Trans2Butene MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 100.00 0.00 0.00 0.00 0.00 100.00 0.00 0.00 0.00 0.00

Cis2Butene MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

13BD MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

IsoButane MOLE% 0.53 0.59 9.82 1.77 1.49 -19.00 1.71 1.42 -20.30 0.80 0.75 -6.86 0.82 0.70 -16.21 0.87 0.72 -19.82 1.12 0.84 -32.91

Butane MOLE% 0.00 0.53 100.00 0.00 1.33 100.00 0.00 1.29 100.00 0.00 0.69 100.00 0.00 0.67 100.00 0.00 0.56 100.00 0.00 0.76 100.00

C5+ MOLE% 0.00 2.07 100.00 0.00 4.86 100.00 0.00 5.48 100.00 0.00 2.96 100.00 0.00 2.85 100.00 0.00 3.64 100.00 0.00 2.94 100.00

Hydrogen Sulfide MOLE% 0.97 0.93 -5.16 5.05 2.54 -98.69 5.34 2.49 -114.03 1.68 1.81 7.26 1.85 1.51 -22.58 2.61 1.53 -71.05 5.30 2.53 -109.98

Water MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 100.00 0.00 0.00 0.00 0.00 0.00 0.02 100.00

Carbon Dioxide MOLE% 0.57 0.56 -1.81 0.90 0.87 -3.48 0.93 0.87 -7.28 0.50 0.61 17.67 0.50 0.48 -3.45 0.46 0.44 -4.58 1.05 1.02 -3.10

Carbon Monoxide MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Benzene MOLE% 0.37 0.30 -23.62 0.78 0.73 -7.28 0.70 0.79 10.55 0.60 0.61 2.97 0.56 0.65 14.00 0.55 0.60 8.27 0.60 0.67 9.42

Toluene MOLE% 0.07 0.10 30.16 0.17 0.27 38.43 0.13 0.29 55.77 0.16 0.27 42.29 0.11 0.26 56.15 0.18 0.27 32.30 0.09 0.19 51.57

Ethylbenzene MOLE% 0.00 0.01 63.02 0.02 0.03 44.30 0.01 0.03 63.93 0.04 0.05 15.79 0.02 0.00 0.04 0.04 10.54 0.02 0.04 53.94

Xylene's MOLE% 0.01 0.01 -17.87 0.08 0.00 0.00 0.00 0.22 0.00 0.10 0.00 0.06 0.00 0.08 0.00

Air Ingress v% 1.6% 4.5% 0.03 12.3% 0.01 2.4% 0.02

03/25/10 

@ 13:50-

14:50

03/25/10 

@ 13:50-

14:50

Relative 

accuracy

03/30/10 

@ 09:29-

10:29

03/30/10 

@ 09:29-

10:29

Relative 

accuracy

03/30/10 

@ 10:42-

11:42

03/30/10 

@ 10:42-

11:42

04/06/10 

@09:45-

10:45

Relative 

precision

04/01/10 

@ 10:17-

11:27

Relative 

precision

04/01/10 

@ 12:42-

13:40

04/01/10 

@ 12:42-

Relative 

precision

04/06/10 

@09:45-

10:45

04/01/10 

@ 09:12-

09:45

04/01/10 

@ 09:12-

09:45

Relative 

precision

04/01/10 

@ 10:17-

11:27

Relative 

accuracy
April 1, 2011 

48 

Table 2.3.6-1. Comparison of Online Vent Gas Composition Analyzers to Summa Canister Samples (cont'd) 

SPL SPL SPL SPL SPL SPL SPL

EPF 3857 HRVOC EPF EQ-16 HRVOC EPF EQ-12HRVOC EPF EQ-22HRVOC EPF EQ-4 HRVOC EPF EQ 20 HRVOC EPF EQ9 HRVOC

Hydrogen MOLE% 54.37 60.97 10.83 7.16 25.03 71.41 24.99 28.33 11.80 27.27 28.33 3.76 9.53 39.81 76.06 33.94 36.33 6.58 22.08 25.06 11.91

Oxygen MOLE% 0.05 0.05 -4.56 0.02 0.02 -14.48 0.02 0.02 -3.45 0.02 0.02 -0.49 0.03 0.02 -47.85 0.01 0.01 -6.74 0.01 0.01 -1.40

Nitogen MOLE% 17.10 14.66 -16.64 64.35 32.28 -99.34 48.43 44.69 -8.38 44.56 44.69 0.30 53.94 36.54 -47.60 34.64 32.70 -5.91 54.40 50.17 -8.42

Methane MOLE% 11.30 10.58 -6.77 16.70 15.29 -9.22 18.75 18.85 0.53 18.46 18.85 2.07 15.94 14.36 -10.96 21.28 20.91 -1.77 17.29 17.62 1.87

Ethylene MOLE% 0.03 0.00 -695.60 0.00 0.00 0.00 0.00 0.06 0.00 0.00 0.00 100.00 NIL 0.01 NIL 0.00

Ethane MOLE% 3.27 3.09 -5.77 0.59 1.85 68.20 1.86 2.06 9.78 2.60 2.06 -26.07 3.34 2.55 -31.22 3.18 3.23 1.47 1.61 1.96 18.08

Acetylene MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Propylene MOLE% 0.05 0.06 11.49 0.03 0.02 -48.69 0.02 0.02 2.32 0.29 0.02 -1201.30 0.08 0.04 -115.68 0.02 0.02 7.98 0.02 0.03 17.97

Propane MOLE% 2.45 2.25 -8.65 1.38 1.27 -8.19 1.41 1.62 12.67 1.81 1.62 -11.67 2.49 1.96 -27.45 2.35 2.56 7.94 1.34 1.65 18.69

Butene1&Isobutane MOLE% 0.00 0.02 100.00 0.00 0.01 100.00 0.00 0.01 100.00 0.00 0.01 100.00 0.00 0.01 100.00 0.00 0.01 100.00 0.00 0.00 100.00

Trans2Butene MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Cis2Butene MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

13BD MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

IsoButane MOLE% 1.11 0.85 -31.40 0.53 0.46 -15.32 0.57 0.59 3.39 0.59 0.59 -0.47 0.89 0.66 -35.18 0.66 0.63 -3.64 0.46 0.47 2.59

Butane MOLE% 0.00 0.76 100.00 0.00 0.39 100.00 0.00 0.55 100.00 0.00 0.55 100.00 0.00 0.59 100.00 0.00 0.55 100.00 0.00 0.36 100.00

C5+ MOLE% 0.00 3.11 100.00 0.00 1.17 100.00 0.00 1.29 100.00 0.00 1.29 100.00 0.00 1.51 100.00 0.00 1.06 100.00 0.00 0.90 100.00

Hydrogen Sulfide MOLE% 5.41 2.48 -117.79 1.37 0.97 -41.34 1.27 1.10 -14.79 1.49 1.10 -34.81 1.53 1.28 -19.55 1.40 1.19 -17.32 0.78 1.01 22.36

Water MOLE% 0.00 0.02 100.00 0.00 0.12 100.00 0.00 0.21 100.00 0.00 0.21 100.00 0.00 0.13 100.00 0.00 0.11 100.00 0.00 0.14 100.00

Carbon Dioxide MOLE% 1.10 1.05 -5.35 6.49 0.50 -1187.95 0.64 0.63 -0.86 0.62 0.63 2.18 8.60 0.51 -1579.69 0.69 0.68 -2.17 0.61 0.61 0.39

Carbon Monoxide MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Benzene MOLE% 0.68 0.71 3.56 0.17 0.00 0.39 0.00 0.39 0.00 0.45 0.00 0.29 0.41 28.49 0.33 0.34 3.34

Toluene MOLE% 0.11 0.21 46.23 0.02 0.00 0.06 0.00 0.11 0.00 0.10 0.00 0.09 0.17 48.15 0.04 0.09 59.93

Ethylbenzene MOLE% 0.02 0.04 44.90 0.00 0.00 0.01 0.00 0.01 0.00 0.04 0.00 0.01 0.05 83.32 0.01 0.05 86.62

Xylene's MOLE% 0.11 0.00 0.03 0.00 0.04 0.00 0.09 0.00 0.23 0.00 0.05 0.00 0.03 0.00

Air Ingress v% 0.04 0.13 0.03 0.00 0.32 0.06 0.01

Component Units

04/13/10 

09:33-

10:33

04/13/10 

09:33-

10:33

Relative 

precision

04/13/10 

08:47-

09:32

Relative 

precision

04/07/10 

@13:31-

13:41

relative 

precision

04/07/10 

@13:43-

14:37

04/07/10 

@13:43-

14:37

Relative 

precision

04/13/10 

08:47-

09:32

04/07/10 

@ 12:19-

12:52

Relative 

precision

04/07/10 

@ 12:54-

13:30

04/07/10 

@12:54-

13:30

Relative 

precision

04/07/10 

@13:31-

13:41

04/06/10 

@ 10:46-

11:46

04/06/10 

@10:46-

11:46

Relative 

precision

04/07/10 

@12:19-

12:52
April 1, 2011 

49 

Table 2.3.6-1. Comparison of Online Vent Gas Composition Analyzers to Summa Canister Samples (cont'd) 

SPL SPL SPL SPL SPL SPL

EPF EQ 23 HRVOC EPF 2912 HRVOC DPEPF 3864 HRVOC DPEPF EQ12 HRVOC DPEPF 1143 HRVOC DPEPF 3861 HRVOC

Component Units

04/13/10 

10:37-

11:29

04/13/10 

10:37-

11:29

relative 

precision

04/13/10 

11:32-12:30

04/13/10 

11:32-

12:30

Relative 

precision

04/16/10 

@ 10:48-

11:46

04/16/10 

@ 10:48-

11:46

Relative 

precision

04/16/10 

©11:58-

12:58

04/16/10 

©11:58-

12:58

Relative 

precision

04/16/10 

@ 12:59-

13:36

04/16/10 

@ 12:59-

13:36

relative 

precision

04/16/10 

@ 13:40-

14:27

04/16/10 

@ 13:40-

14:27

Relative 

precision

Hydrogen MOLE% 18.77 21.24 11.60 19.35 24.87 22.18 49.41 54.50 9.34 48.61 55.52 12.44 49.38 54.56 9.50 49.02 55.15 11.11

Oxygen MOLE% 0.03 0.03 -10.31 0.01 0.01 -1.08 0.04 0.04 -3.33 0.03 0.03 -1.27 0.04 0.04 -11.87 0.03 0.03 -1.25

Nitogen MOLE% 50.01 49.18 -1.69 45.96 36.23 -26.87 23.83 23.01 -3.56 25.36 22.40 -13.21 26.40 22.73 -16.14 25.13 22.41 -12.14

Methane MOLE% 25.18 23.84 -5.62 26.04 32.15 19.01 9.61 8.78 -9.53 9.07 8.91 -1.88 9.15 8.90 -2.74 9.35 9.15 -2.21

Ethylene MOLE% 0.08 0.00 2.19 0.00 NIL 0.00 0.06 0.00 NIL 0.00 0.04 0.00

Ethane MOLE% 1.30 1.35 4.26 1.38 1.58 12.56 3.26 3.03 -7.51 3.07 3.18 3.62 3.10 3.19 2.75 3.28 3.25 -0.77

Acetylene MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Propylene MOLE% 0.39 0.01 -2822.03 0.81 0.01 -15914.81 NIL 0.10 0.12 0.01 -778.24 NIL 0.01 0.03 0.01 -154.70

Propane MOLE% 0.95 1.05 9.58 0.94 1.13 16.74 2.40 2.63 8.70 2.86 2.26 -26.64 3.40 3.02 -12.71 2.52 2.26 -11.57

Butene1&Isobutane MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Trans2Butene MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Cis2Butene MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

13BD MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

IsoButane MOLE% 0.41 0.41 -0.06 0.40 0.48 16.10 1.04 0.93 -11.77 1.08 0.93 -17.20 1.04 0.91 -14.18 1.06 0.91 -16.00

Butane MOLE% 0.00 0.29 100.00 0.00 0.33 100.00 0.00 0.65 100.00 0.00 0.65 100.00 0.00 0.63 100.00 0.00 0.63 100.00

C5+ MOLE% 0.00 0.89 100.00 0.00 1.05 100.00 0.00 2.38 100.00 0.00 2.28 100.00 0.00 2.09 100.00 0.00 2.13 100.00

Hydrogen Sulfide MOLE% 0.80 0.92 13.40 0.86 1.12 23.60 6.08 2.89 -110.09 5.10 2.79 -82.85 3.17 2.85 -11.19 5.19 3.03 -71.34

Water MOLE% 0.00 0.06 100.00 0.00 0.14 100.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Carbon Dioxide MOLE% 0.72 0.70 -1.86 0.73 0.92 20.33 1.04 1.06 2.23 1.07 1.04 -2.62 1.09 1.06 -2.44 1.07 1.04 -2.96

Carbon Monoxide MOLE% 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Benzene MOLE% 0.31 0.35 11.55 0.34 0.40 13.13 0.70 0.71 2.31 0.81 0.72 -13.29 0.79 0.70 -13.44 0.72 0.67 -6.70

Toluene MOLE% 0.04 0.07 50.13 0.04 0.09 60.09 0.09 0.17 45.39 0.10 0.18 44.48 0.08 0.18 53.79 0.09 0.17 47.55

Ethylbenzene MOLE% 0.01 0.02 75.79 0.01 0.02 68.35 0.02 0.04 48.55 0.02 0.04 53.85 0.01 0.04 60.59 0.02 0.04 53.91

Xylene's MOLE% 0.03 0.00 0.03 0.00 0.09 0.00 0.08 0.00 0.07 0.00 0.08 0.00

Air Ingress v% 0.09 0.01 0.03 0.01 0.11 0.01
April 1, 2011 

50 

2.3.7 Potential Impacts of Integrated Sampling 

Previous studies conducted to assess flare CEs have cited the need to sample the entire plume 

envelope, both radially and axially, in order to obtain representative CE values.4,5 The PFTIR 

instrumentation does not sample the entire flare plume, but instead analyzes only one small 

section of the plume at a time. However, because the flare flame is turbulent and subject to 

interactions with the wind, the PFTIR is randomly sampling different areas of the hot plume on a 

continuous basis. The inhomogeneous nature of the flare plume may be more apparent near 

the flame envelope and perhaps less apparent at greater distances from the flame (e.g. 

opportunity for burn out increases). However, at greater distances from the flame, lower 

temperatures can also increase the variability of the observed results due to the lower IR signal 

strength. A comprehensive treatment of this issue is beyond the scope of this investigation and 

might be addressed in the future in more controlled test environments to assess the optimal 

distance from the flame tip to aim the PFTIR telescope, such that the signal strength can be 

maximized but artifacts due to flame heterogeneity can be minimized. 

2.3.8 Accuracy of Combustion Efficiency Measurements at Unstable 

Combustion Conditions 

During several of the test runs at high S/VG ratio, when the EPF was approaching unstable 

operation (e.g. pulsating both visually and audibly), unexpectedly high CEs (90- 97%) were 

observed from the PFTIR instrumentation. The Testing Team hypothesized that the PFTIR data 

collection algorithm might be leading to unrepresentatively high CEs under these conditions. 

The PFTIR instrument collects a spectrum every second. If the instrument QA/QC parameters 

for that scan are acceptable (signal to noise ratio, signal strength, etc.), the spectrum is 

recorded. If an invalid spectrum is obtained, it is discarded. This continues until 82 valid spectra 

are recorded. When the flare starts to pulse, valid spectra can be recorded when combustible 

packets of vent gas are present, but no data is recorded when an incombustible packet is 

present. Data is not recorded under these conditions because no usable signal is received by 

the PFTIR instrument and the instrument QA/QC parameters are not met. 

This pulsing can be seen in the GasFindIR video recorded under these conditions. A 

combustible packet is characterized by a bright flash from the heat signature of the combusting 

gas. This flash disappears completely or almost completely when an incombustible packet of 

gas appears at the flare tip. Because IMACC does not collect data on the number of valid 

spectra recorded per the number of spectra attempted, there was no way to recover data on the 

frequency and duration of invalid spectra. 

There are reasons other than the presence of incombustible gas that could cause a spectrum to 

fail the QA/QC protocol. However, it is conceivable that if the frequency and duration of 

incombustible gas packets was consistent and persistent, the PFTIR instrument could have 

 

4 Pohl, J.H., R. Payne and J. Lee, “Evaluation of the Efficiency of Industrial Flares: Test Result,” 

United States Environmental Protection Agency, Office of Air Quality Planning and Standards, 

EPA-600/2-84-095, May 1984. 

5 M. McDaniel, US EPA/600-2-83-052, Flare Efficiency Study. Engineering-Science, Inc., 

July 1983. 
April 1, 2011 

51 

recorded a high CE based upon the limited data that passed the spectral QA/QC protocols, even 

if these data represented only a smaller percentage of all spectral scans attempted. It is 

possible that the greater degree of variability observed at high S/VG ratios is a function of the 

PFTIR being unable to adequately integrate these low combustion periods into the results. 

2.4 Conclusions 

The EPF vent gas typically contains large quantities of hydrogen, low molecular weight paraffinic 

hydrocarbons, nitrogen, and low concentrations of aromatic hydrocarbons. No visible emissions 

were detected during the testing. 

High CEs were observed over a wide range of S/VG ratios. CEs in excess of 98.0% were 

obtained up to S/VG ratios approaching 6 lb steam/lb vent gas. However, due to the large 

variation in vent gas composition observed at the EPF, CEs below 98.0% were occasionally 

observed at S/VG ratios of less than 1.0 lb steam/lb vent gas (i.e. test conditions with nitrogen 

concentrations in excess of 30 v%). NHVczg exhibited a more consistent relationship with CE 

than either S/VG ratio or vent gas composition alone. NHVczg is calculated as the volumetric 

dilution of all process gases going to the flare tip (e.g. vent gas, steam, and pilot gas). 

Based upon the detector comparison work during this study, the greater sensitivity of the InSb 

detector for hydrocarbons, and the ability of the MCT detector to estimate plume temperature via 

fitting CO2 concentrations in multiple spectral regions; it may be advantageous during future 

PFTIR flare work to have a beam splitter that would allow the simultaneous use of both the InSb 

and MCT detector. 
April 1, 2011 

52 

3. PFTIR Testing Methods and Procedures 

3.1 Description and Principles of Passive FTIR Measurements 

The gas composition data presented in this report was generated by measuring flare radiances 

with a PFTIR instrument. PFTIR analysis operates on the principle of spectral analysis of 

thermal radiation emitted by hot gases. 

In normal absorption spectroscopy, light is passed through a region containing gas to be 

analyzed, and the transmitted light is spread out into a spectrum using an interferometer (FTIR) 

or a spectrometer. In this spectrum, the presence of specific compounds can be determined 

from the patterns of light absorbed while the compound’s concentrations can be measured from 

the intensity of the patterns. The low energy of infrared light is absorbed by molecular species 

causing them to vibrate and rotate faster. Because each molecule consists of a unique structure 

of bound atoms, the patterns of infrared wavelengths (IR colors) absorbed by a molecule are 

also unique. These molecular “finger prints” are used in the infrared analysis of gases. 

In PFTIR analysis, there is no “active” infrared light source, as used in standard absorption 

infrared spectroscopy. Instead the hot gases of the flare are the infrared source. The 

spectrometer is a receiver only. This approach is possible because the infrared radiation 

emitted by hot gases has the same patterns or fingerprints as the absorption spectra for those 

gases. Consequently, like absorption spectroscopy, observing a flare with a passive infrared 

instrument allows for identification and quantification of species through emission spectroscopy. 

However, there is one main difference: the signature arising from a hot gas is proportional to the 

gas’ concentration and to its temperature. Therefore, to accurately take emission or radiance 

measurements, the temperature must be deduced in addition to the gas concentrations. A 

detailed explanation of the temperature determination method utilized for this testing is 

presented in Appendix 5.1. 

Consequently, unlike absorption spectroscopy, the PFTIR signal must be calibrated in absolute 

units of radiance. This requires that the instrument be calibrated utilizing an IR source of known 

spectral radiance. This calibration is accomplished with a commercial black body calibrator. This 

calibrator produces a known radiance IR distribution as predicted by the Planck function. Details 

of this calibration are provided in Appendix 5.1. 

Dr. Curtis Laush of IMACC conducted the PFTIR operation and data analysis for this test 

program. IMACC developed the PFTIR instrument and the analytical software used in this 

study. 

3.2 PFTIR Siting Configuration 

The PFTIR telescope was sited about 115 meters and 5-10 degrees above horizon for the flare 

and 115 meters at 0-3 degrees below horizon for the calibration cells. Figure 3.2-1 illustrates a 

plot plan of the site with the location of the PFTIR telescope, the flare, and the tent housing the 

black body source, cold source, and the hot cell calibration equipment. Also identified is the 

position of the video equipment used during the tests (e.g. visible video and GasFindIR video 

camera positions). 
April 1, 2011 

53 

IMACC

FLIR Camera Emergency

Response

Vehicle (video

cameras)

Analyzer House (SGS - GC)

Black Body/ Hot Cell

Calibration Tent

~375ft

~160ft

~375ft

* Drawing is not to scale

Generators

Figure 3.2-1. Plot Plan of East Property Flare and PFTIR Test Equipment 
April 1, 2011 

54 

3.3 PFTIR Operation 

The PFTIR instrument was located at about 115 meters from the flare. It was housed in and 

operated from a trailer. 

The equipment was calibrated twice a day. Calibration was completed in the morning prior to 

commencement of testing and again at the end of the day after testing was completed to 

validate the data collected that particular day. The calibrations were implemented in the 

quantitative analysis routines immediately prior to when field sample spectra were recorded. 

The calibration of this equipment required three different calibration sources: a cold source, IR 

source and a black body source. Calibration sources were located under a tent on the ground 

adjacent to the base of the flare. The location was chosen so the distance between the PFTIR 

and the calibration equipment was approximately the same as the ground distance between the 

PFTIR and the flare. 

After calibration was completed, the equipment was ready to start testing. A sky background 

was taken to be used in later analysis to subtract background radiance. A new sky background 

was taken as sky conditions changed during the testing. In PFTIR testing, it is important to 

adjust collected spectra with representative sky backgrounds. The calibration log for these tests 

is included in Appendix 5.4. 

For collection of spectral data from the hot gas plume of the flare, the field of view of the PFTIR 

telescope was aimed at a position approximately one flame length from the tip of the visible 

flame. This was deemed to be a point sufficiently away from the active flame for combustion 

reactions to have been completed and to avoid the high heat signature of the flare, which would 

complicate data reduction. 

 

3.4 PFTIR Data Reduction 

The raw PFTIR data must be processed to obtain the individual flare plume component 

concentrations. Dr. Curtis Laush from IMACC processed data and compiled it at approximately 

two minute intervals. IMACC took a spectral scan every second and recorded scans which met 

spectral QA/QC criteria. When 82 valid scans were recorded these scans were averaged. 

Constituents in the hot flare plume were determined by a Classical Least Squares curve fitting of 

the averaged spectral data. 

The total radiance measured by the PFTIR is comprised of four components as shown in Figure 

3.4-1. The four components are: (1) the background radiance altered by its transmission 

through the flare plume and the atmosphere, (2) the flare radiance altered by its transmission 

through the atmosphere, (3) the atmosphere radiance of the air, and (4) the radiance from the 

PFTIR instrument itself. 
April 1, 2011 

55 

Background

Radiance Flare 

Radiance 

Atmospheric

Transmission

& Radiance 

Figure 3.4-1 Contributions to the measured flare radiance 

The total radiant signal received can be represented by: 

Ntotal = Nbkg * τflr * τatm + Nflr * τatm + Natm +Nf Equation 1 

Where 

Ntotal = total radiance 

 Nbkg = background sky radiance 

 τflr = flare transmissivity 

 τatm= atmospheric transmissivity 

 Nflr = flare radiance 

 Natm= atmospheric radiance 

 Nf = radiance of the FTIR instrument itself 

The data analysis procedure is comprised of four steps. First, the raw interferogram is 

converted to a single-beam spectrum using a Fourier Transform process. Second, the flare 

transmissivity is isolated from the other interferences as listed above. Third, the isolated flare 

transmissivity spectrum is converted to an absorbance spectrum so it can be further analyzed 

with standard spectroscopic techniques. Finally, the concentrations of individual components of 

the flare plume are determined from the absorbance spectrum. 

Each of these steps are described briefly below: 

Step 1 – Convert the raw interferogram to a radiance spectrum 

The raw data from the PFTIR are in the form of an interferogram which is radiance as a function 

of FTIR scan position. The Fourier Transform (FT) process converts this data into a radiance 

spectrum, which is radiance as a function of wavelength or, in this case, wavenumber. The 

result is what is referred to as a “single beam” radiance spectrum. The FT process is a standard 

spectroscopic procedure and is not discussed in detail in this report. 
April 1, 2011 

56 

Step 2 – Isolate the flare transmission spectrum 

Once the radiance spectrum has been generated, the flare transmission must be isolated from 

all the interferants that the PFTIR also “sees.” In order to accomplish this, each term in Equation 

1 above must be determined. This is done as follows: 

Background radiance (Nbkg) – At least once each day, the PFTIR was aimed at an unobstructed 

part of the sky. Since the background radiance is affected by conditions such as sun position 

and cloud cover, this procedure was repeated whenever a significant change in background was 

observed. 

Flare transmissivity (τflr) – This is the value sought and is the result when all competing factors 

are removed. This value appears two places: 1) in transmitting the sky background through the 

flare to the PFTIR and 2) in the radiance term for the flare itself. Therefore, the flare 

transmission must be extracted from the complex mixture of signals received by the PFTIR. This 

task is accomplished by the IMACC software. 

Atmospheric transmissivity (τatm) – This value is determined by aiming the PFTIR at an IR 

source and taking the ratio of the value obtained (minus the atmospheric radiance) to a 

“synthetic background” spectrum. This synthetic background (referred to as I0) represents the 

shape of the radiance spectrum that would be generated by the PFTIR in the absence of all 

gases. For this project the IR source was a SiC source operated at a temperature of 1250 K. 

This is a standard source used in most active FTIR systems. This source has sufficient signal 

throughout the infrared to allow for a transmission spectrum to be determined over the range of 

wavenumbers needed. 

Flare plume radiance (Nflr) – Plume radiance is (1 – plume transmission) times the Planck 

function (evaluated at the temperature of the plume). The radiance is what is measured by the 

PFTIR, but it is mixed in with other signals and so must be corrected with respect to this 

interference. 

Atmospheric radiance (Natm) – This value is determined by aiming the PFTIR at a very cold 

source in the calibration telescope located at the same distance from the PFTIR as the flare. 

Any radiance observed will then be due to the intervening atmosphere plus any radiance from 

the PFTIR instrument itself. This measured value is referred to as Mn. For this project, the cold 

source was an aluminum bar immersed in liquid nitrogen. 

PFTIR radiance (Nf) – PFTIR radiance is the emissions of the instrument itself. It is measured 

together with atmospheric radiance and is part of the Mn measurement. 

Once these values are known, they are applied to the total radiance spectrum by IMACC 

proprietary software to isolate the flare transmission spectrum. 

Step 3 – Convert the transmission spectrum to an absorption spectrum 

Once the flare transmission spectrum has been isolated, it must be converted to an absorbance 

spectrum so that standard spectroscopic techniques can be used for further analysis. 

Transmission and absorbance are related by the Beer-Lambert law through the following 

equation. 

 Equation 2
April 1, 2011 

57 

Essentially, absorbance is the negative log of transmission, thus: 

 Equation 3 

This conversion is a standard spectroscopic procedure. 

Step 4 – Determine the concentrations of individual components in the flare plume 

Once the absorbance spectrum has been generated, there are several analytical techniques that 

may be used to estimate individual component concentrations. For this project, a modified 

Classical Least Squares (CLS) analysis was used. IMACC proprietary software was used for this 

step of the data analysis. The modifications to standard CLS include algorithms for linearizing 

the absorbance for each analyte with concentration, corrections for spectral baseline shifts, 

corrections for any spectral line shifts observed, and algorithms for dynamic reference spectra 

selection based upon observed concentrations of each compound. 

The CLS technique compares measured spectra to reference spectra of known concentration 

and interfering compounds and matches the absorbance of the data and the references to 

determine gas concentration. This process is performed for all components present to account 

for all spectral features present. 

After fitting, CLS also determines the difference or residual between the measured and scaled 

references. The fitting process minimizes the residuals in each analysis region. The software 

used for this project uses dynamic reference selection to select reference spectra based upon 

measured gas concentrations. In most cases, this means different reference spectra will be 

chosen for each analyte in the measured spectrum. This process will be repeated up to four 

times to optimize all spectra compared to the measured data. 

A flow chart of the PFTIR data analysis process is shown in Figure 3.4-2. 
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58 

Figure 3.4-2 PFTIR Data Analysis Progression 
April 1, 2011 

59 

4. Data Tables and Files 

4.1 Data Tables 

The test data are provided electronically in the Master Data Workbook. See Appendix 5.5. The 

test data consists of one minute plant data from the SDP Distributed Control System: vent and 

steam flow data, vent gas online GC data, and online BTEX data. SDP imported the IMACC 

PFTIR data from the flare hot gas plume into the plant data spreadsheet for analysis. Each test 

run is identified in the data file by the EPA test ID number and is color coded to facilitate location 

of individual test runs. 

4.2 Visible Video Files 

All of the tests were recorded with a video camera. These electronic data files are attached as 

Appendix 5.6. The video data files were not cataloged by Run ID, but rather were collected and 

labeled by date and time stamp. Therefore, the date, start, and stop times from the test data 

tables must be used to access the appropriate video file. 

4.3 GasFindIR Video Files 

All the tests were also recorded using a FLIR GasFindIR Model 25147-200 IR video camera. 

This camera captures both a thermal image of the flare and, further afield of the flame, a visible 

image of unburned hydrocarbon escaping the flame. These electronic data files are attached as 

Appendix 5.7. These files were also cataloged by date and time stamp in a similar fashion as 

the visible video files. 
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60 

5. Appendices 

5.1 PFTIR Test Protocol (IMACC) 

5.2 Weather Data 

5.3 Summa Canister Sample Results 

5.4 PFTIR Calibration Log 

5.5 Master Data Workbook 

5.6 Flare Testing Video Files 

5.7 Flare Testing GasFindIR Video Files