PFTIR Test&of&Steam/Assisted

Elevated&Flares&– Port&Arthur

Final!Report

June!17,!2011

Flint!Hills!Resources!Port!Arthur,!LLC

Port!Arthur!Chemicals

4241!Savannah!Avenue

Port!Arthur,!Texas!77640

Testing!Conducted

October!21!– November!8,!2010

Prepared!by

Clean!Air!Engineering,!Inc.

Project!No:!11085
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Table&of&Contents

1.0 Overview..............................................................................................................................4

1.1 Introduction .....................................................................................................................4

Figure!1.1R1:!AU!Flare!(left)!and!LOU!Flare!(right) ...........................................................4

1.2 Test!Program!Overview ...................................................................................................5

1.2.1 Objectives.................................................................................................................5

1.2.2 Flare!Components ....................................................................................................5

1.2.2.1 AU!Flare!Description..........................................................................................5

1.2.2.2 LOU!Flare!Description........................................................................................5

1.2.3 Test!Conditions.........................................................................................................6

1.2.3.1 AU!Test!Conditions............................................................................................6

1.2.3.2 LOU!Test!Conditions..........................................................................................7

1.2.3.3 Run!Lengths!and!Replicates...............................................................................7

1.3 PFTIR!Testing!Description ................................................................................................8

1.3.1 PFTIR!Locations.........................................................................................................8

Figure!1.3R1:!Map!of!PFTIR!Locations!in!Relation!to!AU!and!LOU!Flares.........................9

1.3.2 Video!Recordings....................................................................................................10

1.3.3 Preliminary!Results!and!QA/QC..............................................................................10

1.3.4 Vertical!Traverse.....................................................................................................10

Figure!1.3R2:!Vertical!Traverse!Results...........................................................................11

2.0 Results...............................................................................................................................12

2.1 Visual!Rating ..................................................................................................................12

Table!2.1R1:!Flare!Visual!Rating!Scale.............................................................................13

Figure!2.1R1:!CE!vs.!Visual!Rating!for!AU!Flare!Tests......................................................13

Figure!2.1R2:!CE!vs.!Visual!Rating!for!LOU!Flare!Tests....................................................14

2.2 Steam!to!Vent!Gas!Ratio ................................................................................................15

Figure!2.2R1:!Combustion!Efficiency!vs.!S/VG!(lb/lb):!AURA,B,C,D .................................16

Figure!2.2R2:!Combustion!Efficiency!vs.!S/VG!(lb/lb):!LOURA,B,C...................................16

Figure!2.2R3:!Combustion!Efficiency!vs.!S/VG!(scf/scf):!AURA,B,C,D ..............................17

Figure!2.2R4:!Combustion!Efficiency!vs.!S/VG!(scf/scf):!LOURA,B,C................................17

2.3 Net!Heating!Value!of!the!Combustion!Zone ..................................................................18

Figure!2.3R1:!Combustion!Efficiency!vs.!Adjusted!NHVcz:!AURA,B,C,D............................19

Figure!2.3R2:!Combustion!Efficiency!vs.!Adjusted!NHVcz:!LOURA,B,C.............................19
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Figure!2.3R3:!Adjusted/Unadjusted!NHVcz Comparison:!AURB,C,D ................................20

Figure!2.3R4:!Adjusted/Unadjusted!NHVcz Comparison:!LOURA,B,C...............................20

3.0 Conclusions........................................................................................................................21

Appendix&List

Appendix A.1 – EPA 114 Request

Appendix A.2 – Flare Specifications and Equipment

Appendix A.3 – Calculations

Appendix A.4 – PFTIR Description

Appendix A.5 – PFTIR Theory and Operation

Appendix A.6 – Video Camera Descriptions

Appendix A.7 – Individual Test Series Results and Charts

Appendix A.8 – Individual Test Series Process Conditions

Appendix A.9 – Individual Run Results Data Tables

Appendix A.10 – Individual Run Vent Gas Composition Charts

Appendix A.11 – Wind Data Tables

Appendix A.12 – PFTIR QA/QC

Appendix A.13 – Electronic Minute Data

Appendix A.14 – Electronic PFTIR Raw Spectral Data

Appendix A.15 – Video of Runs

Appendix A.16 – Flare Visual Rating Data Sheets

Appendix A.17 – Independent Source Test Calibration Data

Appendix A.18 – Independent Source Test Gas Certifications

Appendix A.19 – Laboratory Records for AU Sample Bags

Appendix A.20 – Clock Synchronization Forms

Appendix A.21 – Hydrogen Net Heating Value Adjustment
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1.0 Overview

1.1 Introduction

As required by a Clean Air Act Section 114 request in Appendix A.1, Flint Hills Resources Port 

Arthur, LLC (FHR) conducted PFTIR testing of the Aromatics Unit (AU) and Light Olefins Unit 

(LOU) flares at their facility in Port Arthur, TX, in October and November of 2010. The main 

objective of the tests was to better understand the impacts of steam on the overall performance of 

each flare in terms of combustion efficiency (CE). Two additional operating parameters were 

also examined during this test program. The effect of hydrogen on combustion efficiency was 

studied on the AU flare. The effect of vent gas flow rate on combustion efficiency was studied 

on the LOU flare. The PFTIR tests were conducted using a Passive Fourier Transform Infrared 

Spectroscopy (PFTIR) instrument developed and operated by Industrial Monitor and Control 

Corporation (IMACC). This report contains the AU and LOU flare test results.

Figure&1.1/1:&AU&Flare&(left)&and&LOU&Flare&(right)

The test was conducted with the assistance of both Clean Air Engineering, Inc. (CAE) and 

Industrial Monitoring and Controls Corporation (IMACC).

Clean Air Engineering, Inc. IMACC

500 W Wood St. 800 Paloma, Suite 100

Palatine, IL 60067 Round Rock, TX 78645
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1.2 Test&Program&Overview

1.2.1 Objectives

The overall objectives of the test program were as follows:

1. Evaluate the impacts of combustion efficiency over a range of operating scenarios by 

changing both flare vent gas composition and steam rates.

2. Evaluate key operating parameters such as steam to vent gas ratio (S/VG) and Net 

Heating Value of the Combustion Zone (NHVcz) as indicators that may assist in 

maintaining flare operation at high efficiency conditions during day-to-day operation.

1.2.2 Flare-Components

FHR Port Arthur has two flares: the Aromatics Unit (AU) flare and Light Olefins Unit (LOU) 

flare. Each flare has automatic steam control logic and equipment that is used during normal 

operation. This control system was used to set each flare at the required test conditions described 

in Section 1.2.3. Details of control and measurement equipment used for each flare are contained 

in Appendix A.2.

1.2.2.1 AU Flare Description

The AU flare is an elevated (120 ft.) steam-assisted flare. The current tip has a diameter of 20 

inches and was installed in 1996. This tip was manufactured by Callidus and has two points of 

steam addition: center steam and ring steam. The center steam is injected in the vent gas stack 

prior to reaching the flare tip, and the ring steam is injected with nozzles around the flare tip rim. 

Appendix A.2 contains design specifications for the AU flare.

The AU flare serves as relief for the Aromatics Unit. The typical AU flare vent gas flow rate 

during normal operation is approximately 800 lb/hr, or less than 0.4% of the hydraulic capacity 

(approximately a 250:1 turndown factor). Base load includes flare header gas from the Aromatics 

Unit, seal purges from rotating equipment, sample station vents, and various process vents from 

process equipment. The flare was operated with a constant center steam of approximately 500 

lb/hr and variable ring steam for the AU flare PFTIR test.

1.2.2.2 LOU Flare Description

The LOU flare is an elevated (370 ft.) steam-assisted flare. The current tip has a diameter of 78 

inches (equivalent diameter of 54 inches – see Appendix A.2 for calculation) and was installed in 

June 2010. This tip was manufactured by Callidus and has two points of steam addition: center 

steam and lower steam. The center steam is injected in the vent gas stack prior to reaching the 

flare tip, and the lower steam is injected through internal tubes interspersed throughout the flare 

tip. Appendix A.2 contains design specifications for the LOU flare.
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The LOU flare serves as relief for the Light Olefins Unit. The typical LOU flare vent gas flow 

rate during normal operation is approximately 3,000 lb/hr, or less than 0.3% of the hydraulic 

capacity (approximately a 333:1 turndown factor). Base load includes flare header gas from the 

Light Olefins Unit, seal purges from rotating equipment, sample station vents, and various 

process vents from process equipment. The flare was operated with a constant center steam of 

approximately 2,890 lb/hr and variable lower steam for the LOU flare PFTIR test.

1.2.3 Test-Conditions

PFTIR test series were performed on both AU and LOU flares at their base loads. For the AU 

flare, additional test series were performed to study the effects of hydrogen on steam operating 

envelopes. For the LOU flare, additional test series were performed to study the effects of 

increased vent gas flow on steam operating envelopes. Each test series is described in the below 

sections.

1.2.3.1 AU Test Conditions

Four test series (A, B, C, and D) were conducted by setting a vent gas composition and vent gas 

flow rate. Within the test series, the steam flow was varied to achieve a range of steam to vent 

gas ratios on a mass basis (S/VG). The rationale for each test series is as follows:

AU-A To simulate normal base load with typical flow conditions for the flare. This test 

represented day-to-day operation. Vent gas flow was between 600 lb/hr and 1,100 

lb/hr, with a best effort to maintain the flow between 700 lb/hr and 1,000 lb/hr.

AU-B To simulate a vent gas composition with low hydrogen content. This test added 

additional natural gas to the base load to bring the total flow up to between 1,750 

lb/hr and 2,250 lb/hr. Hydrogen content in the vent gas was below 15% by volume.

AU-C To simulate a vent gas composition with medium hydrogen content. This test added

additional natural gas and hydrogen to the base load to bring the total flow up to 

match the volumetric flow rate of AU-B. Hydrogen content in the vent gas was 

between 25% and 35% by volume.

AU-D To simulate a vent gas composition with high hydrogen content. This test added

additional natural gas and hydrogen to the base load to bring the total flow up to 

match the volumetric flow rate of AU-B. Hydrogen content in the vent gas was 

between 40% and 50% by volume.

Because the AU flare vent gas header did not have a gas chromatograph installed, vent gas 

sample bags were collected twice for each run and analyzed by the on-site FHR laboratory for 

vent gas composition. The sample bag analysis was corrected to 0% oxygen for the final vent gas 

composition results.
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1.2.3.2 LOU Test Conditions

Three test series (A, B, and C) were conducted by setting a vent gas flow rate. Within the test 

series, the steam flow was varied to achieve a range of steam to vent gas ratios (S/VG). The 

rationale for each test series is as follows:

LOU-A To simulate normal base load with typical flow conditions for the flare. This test 

represented day-to-day operation. Vent gas flow was between 2,500 lb/hr and 3,500 

lb/hr.

LOU-B To simulate an increase in vent gas flow. This test added an additional 5,000 lb/hr of 

fuel gas to the base load. A best effort was made to maintain the hydrogen content of 

the vent gas so that it did not vary by more than 5% by volume (absolute) from LOUA.

LOU-C To simulate a further increase in vent gas flow. This test added an additional 10,000 

lb/hr of fuel gas to the base load. A best effort was made to maintain the hydrogen 

content of the vent gas so that it did not vary by more than 5% by volume (absolute) 

from LOU-A.

1.2.3.3 Run Lengths and Replicates

Each test series had several runs that were performed at set steam to vent gas ratios on a mass 

basis (S/VG). Each run was repeated at least once. If the absolute difference in on-site 

preliminary combustion efficiency results for the two replicates was more than 5% and the 

average combustion efficiency was greater than 85%, a third replicate run would be performed. 

Additionally, at least 15 valid data points (as determined by CleanAir and IMACC site personnel 

from on-site preliminary data) were required to constitute a valid run.

The length for all initial replicate runs at a given condition was 30 minutes. At the conclusion of 

the initial run, the data was divided into 10-minute segments and analyzed. If none of the 

segment average combustion efficiencies varied from the 30 minute average by more than 0.5% 

absolute, the run length for the second replicate could be shortened to 20 minutes.

The S/VG set point for each set of replicate runs was incremented from the minimum or API 521 

recommended steam rate using whole number S/VG steps to the incipient snuff point. If the 

S/VG set point resulted in visible emissions, the run would be discontinued after three minutes of 

Method 22 visible emissions.
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1.3 PFTIR&Testing&Description

The IMACC instrument used to determine gas composition of the flare plume for each test 

condition listed in Section 1.2.3 is the Passive Fourier Transform Infrared (PFTIR) analyzer. 

PFTIR analysis operates on the principle of spectral analysis of thermal radiation emitted by hot 

gases. Passive means that no “active” infrared light source is used. Instead, the hot gases of the 

flare are the infrared source. The spectrometer is a receiver only. This approach is possible 

because the infrared emission spectra of hot gases have the same patterns or “fingerprints” as 

their absorption spectra do. Consequently, observing a flare with an infrared instrument allows 

for identification and quantification of species through emission spectroscopy just as with 

absorption spectroscopy. A detailed description of the instrument and testing procedure are 

found in Appendix A.4.

1.3.1 PFTIR-Locations

Two PFTIR instruments were used for this test program. They were placed at approximately 90° 

from one another in order to ensure a good view of the flare plume regardless of wind direction.

For the AU flare tests, one PFTIR location was inside a portable SeaCan container by the 

fenceline monitoring building (“SeaCan location”), and the second location was in a trailer on 

Miller Farm road (“Trailer location 1”). The Trailer location equipment was controlled from the 

SeaCan location via fiber optic and Ethernet cables. This allowed both PFTIRs to collect data 

during a run for simultaneous readings. However, only some runs had simultaneous readings due 

to wind and calibration restrictions.

For the LOU flare tests, the PFTIR at the SeaCan location was used, and the Trailer location was 

moved to the opposite end of Miller Farm road (“Trailer location 2”). The two locations were not 

connected by cable, so only one location could be controlled at a time. Thus, simultaneous 

readings were not performed for the LOU flare test.

Figure 1.3-1 shows a map of the PFTIR locations in relation to the flare. The PFTIR at the trailer 

locations (serial number “H”) was mounted inside the rear of the trailer. The PFTIR at the 

SeaCan location (serial number “A”) was mounted on a tripod and placed at the road location. 

Appendix A.4 contains more detailed information about each location.
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Figure&1.3/1:&Map&of&PFTIR&Locations&in&Relation&to&AU&and&LOU&Flares
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1.3.2 Video-Recordings

During the test program, video cameras recorded flare activity from the SeaCan and Trailer 

locations. At each location, one stationary visible light camera and one stationary infrared light 

camera were recording the flare tip. Additionally, one infrared camera was mounted on each 

PFTIR and recorded the aiming position of each PFTIR. For the Trailer location during the LOU 

test (“Trailer location 2”), the stationary visible and infrared cameras were located on the roof of 

the LOU control room. The types of cameras used during the test program are listed in Appendix 

A.6.

1.3.3 Preliminary-Results-and-QA/QC

On-site preliminary combustion efficiency results were computed. On-site replicate and run 

length decisions were made with the preliminary combustion efficiency results. By design, these 

preliminary results did not take into account the sky backgrounds, compound lists, and 

interferents that are incorporated after the test program is complete (see Appendix A.4). Thus, 

the final combustion efficiency results may change when all fraction are included in the analysis. 

To ensure useable combustion efficiency results from the PFTIR, several QA/QC tests were 

performed during the test program. These tests included an independent source test, simultaneous 

measurements, and vertical traverses. Appendix A.12 contains data from these QA/QC tests.

1.3.4 Vertical-Traverse

In selecting an aiming point for the PFTIR near the center of the flare plume, an assumption is 

made that the combustion efficiency at this location is representative of the overall combustion 

efficiency of the flare. In order to test this assumption, a separate vertical traverse of the plume 

was conducted along with the LOU A 4.0 test series. Measurements were made at the top, the 

middle, and the bottom of the plume. This traverse was conducted under high wind conditions 

that would maximize the possibility of combustion efficiency stratification in the plume (i.e., 

higher combustion efficiency at the edges of the plume and lower combustion efficiency in the 

center.)

Details of the traverse are found in Appendix Section A.12.3. Figure 1.3-2 shows the results of 

the traverse. Note that regardless of whether the PFTIR measures at the top, the middle, or the 

bottom of the plume, the combustion efficiency is essentially constant. 
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Figure&1.3/2:&Vertical&Traverse&Results
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2.0 Results

For results presented in this section, relationships between combustion efficiency and three 

operating parameters were analyzed:

• Visual Rating – Flare flame visual emission readings (1-10 scale)

• S/VG – Actual steam to vent gas ratio (lb steam/lb vent gas)

• NHVcz – Net heating value of the combustion zone (BTU/scf)

These parameters were selected because they can potentially be used during normal flare 

operation to maintain high combustion efficiency. Analysis of the combustion efficiency results 

from the PFTIR during this test established a relationship between combustion efficiency and 

these parameters. Descriptions of calculations for these parameters are contained in Appendix 

A.3. Appendix A.7 contains tables and charts of completed runs based on the requirements of 

the 114 Request. Appendices A.7 through A.11 also contain detailed condition and run 

information for each test.

2.1 Visual&Rating

Visual ratings can be performed quickly and easily by flare operators without specialized 

equipment or instruments. Visual observations are an effective tool to be used in conjunction 

with the other operating parameters S/VG and NHVcz. A relationship between combustion 

efficiency and visual rating may help an operator identify desirable flare operating conditions. 

However, this parameter is limited in that flare combustion efficiency is not easily determined 

when the flare flame is transparent.

Flare visual readings were collected during the test program using the scale established for the 

PFTIR test. Table 2.1-1 describes the flare visual rating scale.

The incipient smoke point is designated as the number 5 (the center of the scale), and represents 

the point at which the flare displays a “marbled” texture, indicative of small carbon soot particles 

forming in the combustion zone but quickly dissipating. No visible soot particles are present 

outside of the flame boundary at the incipient smoke point.

Flame ratings above 5 indicate increasing visible emissions extending beyond the flame 

boundary observed by an increasingly distinct trailing smoke plume. Flame ratings less than 5 

indicate a visible flame decreasing in intensity until it becomes transparent. Ratings of 2 to 4 

indicate a visible flame and a rating of 1 indicates a transparent flame. A flame rating of 0 

indicates that the flare may be extinguished with steam visually present.
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Table&2.1/1:&Flare&Visual&Rating&Scale

Flame Rating Flame Characteristic

0 Steam plume

1 Transparent

2 Mostly transparent, with occasional yellow flame.

3 Mostly yellow flame, with occasional transparency.

4 Yellow to orange flame.

5 Orange flame with some dark areas in the flame. (Incipient smoke point)

6 Orange flame with light smoke trail.

7 Clear steam at the flare tip, with an orange flame and a light smoke trail.

8 Orange flame with dark smoke trail leaving the flame.

9 Orange flame with heavy dark smoke trail leaving the flame.

10 Billowing black smoke

For the AU and LOU test programs, a FHR Port Arthur contractor recorded visual readings 

during each run using the flame rating scale. When the flare flame began consistently smoking (a 

rating of 6.0), the visual reader would alert the flare test control room and the run would be 

halted after 3 minutes of continuous visual emissions.

Figure 2.1-1 shows the relationship between combustion efficiency and visual rating for all runs 

in the AU flare tests. Most of the runs performed in the AU flare tests had transparent flames and 

low visual ratings.

Figure 2.1-2 shows the relationship between combustion efficiency and visual rating for all runs 

in the LOU flare tests. Like the AU flare tests, most of the runs performed in the LOU flare tests 

had transparent flames and low visual ratings. 

Figure&2.1/1:&CE&vs.&Visual&Rating&for&AU&Flare&Tests
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Figure&2.1/2:&CE&vs.&Visual&Rating&for&LOU&Flare&Tests
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2.2 Steam&to&Vent&Gas&Ratio

S/VG can be used in control logic for maintaining smokeless combustion. Establishing a 

relationship between S/VG and combustion efficiency enables flare operators to better program 

steam control logic to improve combustion efficiency. However, S/VG alone may have 

limitations in its relationship to combustion efficiency. For example, a vent gas stream with high 

concentrations of inerts in the vent gas will not follow the same S/VG vs. combustion efficiency 

relationship as a vent gas stream with low concentrations of inerts.

PFTIR test runs for the AU and LOU flares were conducted at set steam to vent gas ratios 

(S/VG) on a mass basis (lb/lb). The S/VG set points for each run were established prior to the 

test by the 114 Request found in Appendix A.1. Figures showing S/VG ratios on a volumetric 

basis (scf/scf) are also included for comparison

For the AU flare base load (AU-A), low hydrogen (AU-B), mid hydrogen (AU-C), and high 

hydrogen (AU-D) test series, steam flow was increased from the point of incipient smoke to a 

point just before snuffing the flare (incipient snuff). For these test series, combustion efficiency

remained relatively constant at a high level until the S/VG reached a point after which, 

combustion efficiency declined with increasing steam.

A mixture of hydrogen balanced with natural gas was added to the base load to achieve the 

desired hydrogen content (by volume) for the variable hydrogen tests. All of the variable 

hydrogen tests were performed at approximately the same volumetric flow rate. The vent gas for 

AU-B was less than 15% hydrogen content. The vent gas for AU-C had a hydrogen content 

between 25% and 35%. The vent gas for AU-D had hydrogen content between 40% and 50%.

The increased hydrogen content appears to reduce the rate of combustion efficiency decline. 

Figure 2.2-1 shows this trend on a mass basis. Figure 2.2-3 shows this trend on a volumetric 

basis (scf/scf) for comparison. 

For the LOU flare base load (LOU-A), mid flow (LOU-B), and high flow (LOU-C) series, steam 

flow was increased from the point of incipient smoke to a point just before snuffing the flare 

(incipient snuff). Like the AU flare results, combustion efficiency for the LOU flare remained 

relatively constant at a high level until the S/VG reached a point after which, combustion 

efficiency declined with increasing steam.

The LOU-B test series added an additional 5,000 lb/hr of fuel gas to the base load rate (3,000 

lb/hr). Fuel gas was used because its hydrogen and methane content are similar to the LOU vent 

gas. The LOU-C test series added an additional 10,000 lb/hr of fuel gas to the base load rate. The 

rate of combustion efficiency decline seemed to increase slightly with increased vent gas flow. 

Figure 2.2-2 shows this trend on a mass basis. Figure 2.2-4 shows this trend on a volumetric 

basis (scf/scf) for comparison. 
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Figure&2.2/1:&Combustion&Efficiency&vs.&S/VG&(lb/lb):&AU/A,B,C,D

Figure&2.2/2:&Combustion&Efficiency&vs.&S/VG&(lb/lb):&LOU/A,B,C
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Figure&2.2/3:&Combustion&Efficiency&vs.&S/VG&(scf/scf):&AU/A,B,C,D

Figure&2.2/4:&Combustion&Efficiency&vs.&S/VG&(scf/scf):&LOU/A,B,C
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2.3 Net&Heating&Value&of&the&Combustion&Zone

NHVcz is another parameter that could be used to assist control of normal flare operation. The 

relationship between NHVcz and combustion efficiency has a wider scope and can take into 

account more process variables. For example, inerts in the vent gas are taken into account for the 

NHVcz calculation so the relationship to combustion efficiency remains valid when inerts are 

variable in the vent gas. However, NHVcz requires the flare operator to measure vent gas 

composition, which may require new equipment be installed on the vent header. Because the 

vent gas composition may only be measured in 10+ minute increments it also may be difficult to 

use NHVcz alone for control. 

The Net Heating Value of the Combustion Zone (NHVcz) , which includes total steam to the flare 

tip, is a calculated term representing the net heating value of all components in the combustion 

zone. The combustion zone is directly above the flare tip and is the point at which all materials 

combine for combustion. The NHVcz is therefore the resultant heat content from the mixture of 

the vent gas from the flare header, the pilot gas, and the total steam. To compensate for the 

observed effects of hydrogen, an adjusted NHVcz was calculated assuming hydrogen to have a 

net heating value of 1,212 BTU/scf instead of the unadjusted net heating value of 275 BTU/scf. 

For a more detailed discussion regarding the hydrogen adjusted NHVcz, calculation and value,

see Appendix A.21. 

Figure 2.3-1 shows the relationship between combustion efficiency and adjusted NHVcz for the 

AU flare tests.

Figure 2.3-2 shows the relationship between combustion efficiency and NHVcz for the LOU flare 

tests. 

The adjusted NHVcz appears to compensate well for the effects of hydrogen on combustion 

efficiency decline. When a hydrogen net heating value of 1,212 BTU/scf is used, the adjusted 

NHVcz trends for the AU hydrogen test series (AU-B,C,D) shift into closer alignment. Figure 

2.3-3 shows this shift from unadjusted NHVcz to adjusted NHVcz for the AU hydrogen tests.

The adjusted NHVcz does not compensate for the effects of vent gas flow rate on combustion 

efficiency decline. Figure 2.3-4 shows this shift from unadjusted NHVcz to adjusted NHVcz for 

the LOU tests.
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Figure&2.3/1:&Combustion&Efficiency&vs.&Adjusted&NHVcz:&AU/A,B,C,D

Figure&2.3/2:&Combustion&Efficiency&vs.&Adjusted&NHVcz:&LOU/A,B,C
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Figure&2.3/3:&Adjusted/Unadjusted&NHVcz Comparison:&AU/B,C,D

Figure&2.3/4:&Adjusted/Unadjusted&NHVcz Comparison:&LOU/A,B,C
PFTIR!Test!of!SteamRAssisted!Elevated!Flares

Flint!Hills!Resources!Port!Arthur,!LLC!R AU!and!LOU!Flares

Page 21 of 21

3.0 Conclusions

The PFTIR test of the AU and LOU flares at the FHR Port Arthur chemical plant provided data 

to support the following conclusions.

Overall Observations

General

! The data shows that both the AU and LOU flares exhibit a fairly broad high efficiency 

operating range that is consistent with current and past flare operating practices.

! Each of the three approaches to manage combustion efficiency (visibility, S/VG, and 

NHVcz) have advantages and disadvantages. Using a combination of these approaches 

will likely result in the most effective overall flare control strategy.

Visiblity

• Combustion efficiency generally begins to decline once the flame transitions from a 

smokeless, visible flame to one that is transparent. However, depending on the vent gas 

composition, not all transparent flames have poor combustion efficiency. This is most 

evident on the LOU flare results which contain a high hydrogen, high methane 

composition vent gas.

• A visible orange flame generally indicates good combustion efficiency.

S/VG

• Once adequate steam is supplied to prevent smoking, combustion efficiency generally 

declines with increased S/VG during normal and higher flow operations.

• Combustion efficiency will decline more rapidly with increased steam to vent gas ratios 

on a mass basis when the vent gas flow rate increases.

NHVcz

• The characteristics of hydrogen combustion are different than those of hydrocarbon 

combustion.

• Adjusting the net heating value of hydrogen from 275 BTU/scf to 1,212 BTU/scf more 

closely reflects the true combustion characteristics of hydrogen.

• Adjusting the net heating value of hydrogen brings the combustion efficiency trend lines 

into closer alignment when calculating the net heating value of the combustion zone.