Rev. 5 Document: 9136991-GP0-P07-0001 1

TEST PROTOCOL FOR THE DETERMINATION

OF DESTRUCTION EFFICIENCY OF PRESSUREASSISTED AND STEAM-ASSISTED FLARE BURNERS

This test activity is undertaken by The Dow Chemical Company in 

support of an application to the TCEQ for an Alternate Means of 

Control.

Oct 1, 2013

PREPARED BY

Document: 9136991-GP0-P07-0001
Rev. 5 Document: 9136991-GP0-P07-0001 2

Contents

INTRODUCTION ......................................................................................................3

PURPOSE ................................................................................................................4

FUEL COMPOSITION FOR PRESSURE-ASSISTED BURNER TESTS..................5

FUEL COMPOSITION FOR STEAM-ASSISTED BURNER TESTS .........................6

TESTING METHODOLOGY .....................................................................................7

1.1 Division of Labor ..........................................................................................7

1.2 Fuel Gas and Steam Flow Measurement.....................................................7

1.3 Description of Sample Gas Extraction Method.............................................8

1.4 Passive Fourier Transform Infrared Spectroscopy (PFTIR) Measurement ..8

1.5 Testing Duration and Replicates..................................................................9

1.6 Flue Gas Sampling and Analysis .................................................................9

1.6.1 CO Emissions Analyzer.......................................................................10

1.6.2 CO2 Emissions Analyzer .....................................................................10

1.6.3 Total Unburned Hydrocarbon Emissions Analyzer..............................10

1.6.4 Oxygen Analyzer.................................................................................10

1.6.5 NOx Emissions Analyzer.....................................................................10

1.6.6 Propylene Emissions Analyzer............................................................11

1.7 Fuel Gas Sampling and Analysis ...............................................................11

1.8 Data Acquisition Systems ..........................................................................11

A) John Zink Data Acquisition System ........................................................11

B) CleanAir Engineering and TRC Data Acquisition System.......................12

1.9 General Conduct of Test............................................................................12

QUALITY ASSURANCE AND QUALITY CONTROL ACTIVITIES..........................14

CALCULATIONS OF DESTRUCTION REMOVAL EFFICIENCY AND 

COMBUSTION EFFICIENCY .................................................................................15

FINAL REPORT CONTENTS .................................................................................16

APPENDIX A – PFTIR OPERATION AND CALIBRATION.....................................17

APPENDIX B – TEST ARRANGEMENT FOR PRESSURE ASSISTED BURNER.25

APPENDIX C – PROPOSED FUEL COMPOSITION..............................................26
Rev. 5 Document: 9136991-GP0-P07-0001 3

INTRODUCTION

High destruction efficiency of flared gases is very desirable. This level of flare performance requires 

good mixing of gas and ambient air. The traditional means of drawing air into the gas and 

promoting mixing is a steam-assisted flare burner. Air from a blower or fan is also used as a source 

of air for combustion and the energy for mixing. There are, however, flare systems that have 

significant static energy in the gases. By converting this static energy (gas pressure) into kinetic 

energy (velocity) it is possible to educt air into the gas achieving a high level of mixing. These flares 

are often referred to as high-pressure flares or pressure-assisted flares. Pressure-assisted flare 

burners described above have been in use in Texas for more than 30 years.
Rev. 5 Document: 9136991-GP0-P07-0001 4

PURPOSE

The purpose of these tests is to determine the destruction removal efficiencies of pressure assisted

and steam-assisted flare burners that will be used for the disposal of hydrocarbon emissions from a

DOW Chemical facility located in Texas. The tests will be conducted under conditions 

representative of the expected normal operating conditions. The data will be used to define the air 

quality impact of such flaring operations.

Using equipment, gases and procedures agreed by all parties involved, emission measurements will 

be made to determine concentrations of carbon dioxide (CO2), carbon monoxide (CO), oxygen (O2), 

total hydrocarbons (THC), propylene, and NOx. Additional data that will be logged includes: 

process conditions (fuel flows, fuel pressure, etc.) and meteorological measurements.

Previous studies conducted in the 1980’s, and more recently, indicate that pressure assisted flare 

designs are capable of achieving high destruction efficiencies with very high exit velocities for 

various hydrocarbons. The ultimate purpose of the study is to provide TCEQ with sufficient data to 

demonstrate that pressure assisted flare tips can achieve a minimum destruction efficiency that 

meets or exceeds the minimum destruction efficiency for steam assisted or air assisted flares 

operating within the velocity restrictions contained in 40 CFR 60.18 & 40 CFR 63.11.

A small portion of the burners associated with this system will be steam-assisted burners. This 

burner type will also be investigated to determine the operating envelope for good destruction 

efficiency.
Rev. 5 Document: 9136991-GP0-P07-0001 5

FUEL COMPOSITION FOR PRESSURE-ASSISTED BURNER 

TESTS

A total of seven tests will be performed with four fuel compositions. The fuel composition for each 

test will consist of the following:

Test #P1H: 100% Propylene. Burner fuel pressure to be maximum operating pressure.

Test #P1L: 100% Propylene. Burner fuel pressure to be minimum operating pressure.

Test #P2H: Mixture of propylene and nitrogen. Burner fuel pressure to be maximum

operating pressure. Initial run of this test will vary the proportion of nitrogen 

to propylene to determine minimum heating value for stability. Once the 

minimum heating value for stability is determined, the first emissions test 

run will commence. Replicate runs of test P2H and all runs of test P2L will 

use the same heating value.

Test #P2L: Mixture of propylene and nitrogen. Proportion of nitrogen to propylene 

determined from test P2H. Burner fuel pressure to be minimum operating 

pressure.

Test #P3H: Mixture of 50% propylene / 50% natural gas by volume diluted with nitrogen. 

Burner fuel pressure to be maximum operating pressure. Initial run of this 

test will vary the proportion of nitrogen to hydrocarbon to determine 

minimum heating value for stability. Once the minimum heating value for 

stability is determined, the first emissions test run will commence. Replicate 

runs of test P3H and all runs of test P3L will use the same heating value.

Test #P3L: Mixture of 50% propylene / 50% natural gas by volume diluted with nitrogen. 

Proportion of nitrogen to hydrocarbon determined from test P3H. Burner 

fuel pressure to be minimum operating pressure.

Test #P4: Mixture of 90% hydrogen / 10% natural gas by volume. Burner fuel pressure 

to be maximum operating pressure. This test is to prove flame stability. No 

emissions data will be taken and no replicates conducted for this test. 

Expected run time for this test is less than 5 minutes.

Note that standard conditions are defined as 68°F and 14.696 psia pressure.
Rev. 5 Document: 9136991-GP0-P07-0001 6

FUEL COMPOSITION FOR STEAM-ASSISTED BURNER TESTS

A total of six tests will be performed. The fuel composition for each test will consist of the 

following:

Test #S1: Mixture of propylene/nitrogen at or slightly above critical pressure to 

produce sonic exit velocity. Steam to be at design flow rate. Proportion of 

propylene to nitrogen will be adjusted to the minimum heating value which 

produces a stable flame. This test would allow operation of the SKEC burners 

at maximum pressure as long as the heat content of the relief gases was 

above the determined minimum.

Test #S2: Same fuel composition and flow rate determined in test S1. Steam to be shut 

off. This test will show that steam is not needed for high destruction 

efficiency or smokeless operation when the exit velocity is sufficiently high.

Note: Tests S1 & S2 are designed to show that this type of burner can operate as a 

pressure assisted burner with or without steam and meet emissions 

requirements.

Test #S3: Steam flow rate set to the cooling rate (minimum steam rate). Fuel to be 

propylene / nitrogen mixture of 300 btu/scf LHV. Fuel flow to initially be at a 

low rate. The fuel flow rate will be slowly increased until the flame becomes 

unstable, at which point the flow rate will be slightly reduced.

Test #S4: Steam flow rate set to the cooling rate (minimum steam rate). Fuel to be 

propylene / nitrogen mixture of 700 btu/scf LHV. Fuel flow to initially be at a 

low rate. The fuel flow rate will be slowly increased until the flame becomes 

unstable, at which point the flow rate will be slightly reduced.

Test #S5: Steam flow rate set to produce 10 psig steam pressure at the burner. Fuel to 

be propylene / nitrogen mixture of 300 btu/scf LHV. Fuel flow to initially be 

at a low rate. The fuel flow rate will be slowly increased until the flame 

becomes unstable, at which point the flow rate will be slightly reduced. If 

300 btu/scf LHV cannot be made stable with this steam rate, a higher LHV 

composition will be used.

Test #S6: Steam flow rate set to produce 10 psig steam pressure at the burner. Fuel to 

be propylene / nitrogen mixture with an LHV of test S5 + 400. Fuel flow to 

initially be at a low rate. The fuel flow rate will be slowly increased until the

flame becomes unstable, at which point the flow rate will be slightly reduced. 

Note that standard conditions are defined as 68°F and 14.696 psia pressure.
Rev. 5 Document: 9136991-GP0-P07-0001 7

TESTING METHODOLOGY

1.1 Division of Labor

The John Zink Company will be responsible for overall conduct of the testing. JZ will be 

directly responsible for supply and metering of fuel gases, logging of process conditions (fuel 

flow, fuel pressure, etc.), logging of meteorological data, supply of test burners, generation of 

final report, video recording, and sub-contracting to third parties.

TRC (a gas analysis company) will be responsible for supply, calibration, and operation of all 

gas sampling and analysis equipment as well as supply of all calibration gases. TRC will 

calculate the flare destruction efficiency and combustion efficiency at the conclusion of each 

test point and will supply JZ a written formal test report that documents the findings of the 

testing program.

CleanAir Engineering will be responsible for supply, calibration, and operation of the PFTIR 

emissions measurement device. CleanAir Engineering will calculate the flare combustion 

efficiency at the conclusion of each test point and will supply JZ a written formal test report 

that documents the results of their measurements.

Other contractors that will be employed include; crane rental services, liquid nitrogen storage 

and vaporization services, and hydrogen delivery services.

1.2 Fuel Gas and Steam Flow Measurement

All testing will be performed at the John Zink R&D Test Facility located in Tulsa, Oklahoma. 

The John Zink R&D Test Facility has liquid, commercial grade, propylene, nitrogen and Tulsa 

natural gas (TNG) available on site. The Test Facility is equipped with a water bath vaporizer 

capable of vaporizing approximately 20,000 lb/hr of propylene. 

The John Zink R&D Test Facility has nitrogen available at low flow rates. In order to meet the 

nitrogen supply demand required for testing, supplemental liquid nitrogen storage and 

vaporization capability will be brought on site.

The John Zink R&D Test Facility has hydrogen available at low flow rates. In order to meet 

the hydrogen supply demand required for testing, supplemental hydrogen will be brought on 

site via transport. The meter run used for nitrogen will be re-tasked for hydrogen for test P4.

The flow rate of each fuel component will be measured separately using an orifice metering 

system designed in accordance to ANSI standards. The orifice plate and orifice flanges will be 

certified to meet all applicable procedures and specifications. All fuel measurements are fully 

compensated for pressure and temperature. The propylene meter run uses differential 

pressure, static pressure, and temperature transmitters to provide the data acquisition 

system with sufficient information to calculate flow rate. The nitrogen/hydrogen and natural 

gas meter runs employ fully compensated mass flow meters which internally calculate the 

flow rate and outputs the mass flow.
Rev. 5 Document: 9136991-GP0-P07-0001 8

Samples of the fuel mixture flowing to the flare will be collected from a point near the burner

in order to confirm the composition and heating value of the waste gas stream. A minimum 

of two samples during each test run will be analyzed per EPA Method 18. A sample will be 

collected at the start and end of each test point. Additional samples will be taken if time 

allows.

The temperature and pressure of the fuel gas will also be measured at a location just 

upstream of the test burner. These measurements will be used as a check to insure that the 

flow rate through the metering system properly corresponds to these readings.

Steam flow will be measured via an ultrasonic flow meter fully compensated for pressure and 

temperature. Steam pressure and temperature will be measured at a location very near the 

burner.

1.3 Description of Sample Gas Extraction Method

The sample gas extraction apparatus designed and employed for the TCEQ 2010 Flare Study 

will be used for this test campaign. (See Figure 1) The apparatus consists of an inlet cone, a 

sample preparation section, a sample extraction section, and eductor. The inlet face of the 

cone is 20” diameter tapered to a 12” outlet. Around the perimeter of the cone, 120° apart, 

are three exposed junction thermocouples for sensing the temperature of the plume. The 

12” cone outlet is connected to a 90 degree elbow in which mixing tabs have been installed. 

The mixing tabs ensure the plume sample that is pulled through the extraction apparatus is 

well mixed and homogeneous. The outlet of the elbow is connected to the inlet of the 

sample preparation section. The sample preparation section is a 9.5’ long 12” pipe with a 

Vortab flow conditioner located in the first 3 feet. The Vortab flow conditioner will also assist 

in mixing the gases as well as conditioning the flow profile. At the exit of the sample 

preparation section is the extraction section. The sampling section is 1.5 feet long and 

consists of a pitot tube for measurement of the flue gas velocity in the apparatus, an exposed 

junction temperature element, and a flue gas extraction probe. The flare flue gas sample that 

will be analyzed for emissions composition will be obtained from this location. Downstream 

of the sampling section 7.5 feet is the end of the sample gas extraction apparatus where the 

eductor is attached. The eductor uses compressed air to induce flow through the apparatus. 

The sample gas extraction apparatus is designed with lifting lugs to allow it to be positioned 

with a crane; it is also designed with guide chains that will allow it to be positioned from 

grade in order to prevent the apparatus from swinging.

1.4 Passive Fourier Transform Infrared Spectroscopy (PFTIR) 

Measurement

A single PFTIR instrument will be used during all tests. PFTIR data will be collected 

simultaneously with the extractive data. Appendix A details the PFTIR methodology.
Rev. 5 Document: 9136991-GP0-P07-0001 9

Figure 1 Sample Gas Extraction Apparatus

1.5 Testing Duration and Replicates

Tests P1-P3 H/L will be run for 20 minutes with three replicates. Consequently, the total run 

time for each of these tests is 1 hour. Replicates will be separated by the other 5 tests in this 

matrix. Test P4 is unique in that only a small percentage of the fuel gas is a hydrocarbon; 

consequently determination of DRE is problematic. Test P4 is to demonstrate stability and it 

is expected that this test run will take less than 5 minutes. No replicates will be run for test 

P4.

Tests S1 to S6 will be run for 20 minutes once process conditions have been determined and 

stabilized. No replicates will be run for tests S1 to S6. 

1.6 Flue Gas Sampling and Analysis

A representative exhaust sample of the flare emissions will be collected through the sample 

gas extraction apparatus that will be positioned over the exhaust plume of the flare. The 

sampling apparatus cone will be positioned outside the visible flame. The position of the 

inlet will be adjusted so that the average temperature readings of the three inlet

thermocouples are between 700° and 300°F. Effort will be made to ensure the temperature 

of the gases entering the extraction apparatus does not exceed 800°F. 800°F is chosen 

because it is below the auto-ignition temperature of Methane (1076°F), Propylene (856°F), 

and Carbon Monoxide (1128°F). Ensuring that the gases entering the gas extraction 

apparatus do not exceed 800°F gives confidence that the combustion process has ceased 

prior to the sample being extracted.

The extracted sample will be pulled through a heated sample line and into a mobile 

laboratory for analysis. A portion of the sample gas will be analyzed on a wet basis (total 

hydrocarbons and GC analysis of propylene) to avoid condensation of the hydrocarbons prior 

to measurement. The remainder of the sample will be dried and sent to the CO, O2, CO2 and 

NOx analytical instruments.

The moisture content of the plume will be calculated using a combination of Equations 19-13 

and 19-34 of EPA Method 19. The total hydrocarbon concentration will then be converted 
Rev. 5 Document: 9136991-GP0-P07-0001 10

from a wet basis to a dry basis, and then the concentration on a dry basis will be used in the 

remainder of the emission calculations.

The sampling and analysis procedures to be used during these tests will conform in principle 

with those outlined in the Code of Federal Regulations, Title 40, Part 60, Appendix 1, 

Methods 3A, 10, 25A, 7E, and 18. Mass emissions rates will be determined by the 

stoichiometric calculation techniques of EPA Method 19; see section titled “Calculation of 

Destruction Removal Efficiency” of this document for details. A discussion of the continuous 

analyzers used for this type of testing is presented below.

1.6.1 CO Emissions Analyzer

CO concentrations will be determined in accordance with procedures set forth in 

EPA Method 10. A continuous non-dispersive infrared (NDIR) analyzer will be used. 

The NDIR analyzer is equipped with a gas correlation filter that removes any 

interference from CO2 or other combustion products; this eliminates the need for 

ascarite traps and the associated correction factors.

1.6.2 CO2 Emissions Analyzer

The CO2 concentration measurements will be made in accordance with the 

procedures of EPA Method 3A. An infrared absorption CO2 analyzer will be utilized 

for these tests.

1.6.3 Total Unburned Hydrocarbon Emissions Analyzer

EPA Method 25A will be utilized to determine concentrations of total 

hydrocarbons. Calibrated on a methane basis, the analyzer will utilize a flame 

ionization detector to determine THC. The analyzer is equipped with an adjustable 

heated oven, containing a heated pump and a burner. A small flame, inside the 

oven, is elevated and sustained by regulated flows of air and hydrogen. The burner 

jet acts as an electrode and is connected to the negative side of a precision power 

supply. An additional electrode, known as the “collector,” is connected to a high 

impedance, low noise electronic amplifier. The two electrodes establish an 

electrostatic field. When a gaseous sample is introduced to the burner, it is ionized 

in the flame. The charged particles (ions) migrate to their respective electrodes 

creating a small current between the electrodes. A precision electrometer 

amplifier is used to measure this current. The current is directly proportional to the 

hydrocarbon content of the sample.

1.6.4 Oxygen Analyzer

The O2 concentration measurements will be made in accordance with the 

procedures of EPA Method 3A. A paramagnetic cell O2 analyzer will be utilized for 

these tests.

1.6.5 NOx Emissions Analyzer
Rev. 5 Document: 9136991-GP0-P07-0001 11

EPA Method 7E will be used to determine concentrations of NOx (via 

chemiluminescence). Within the chemiluminescence analyzer, the gaseous sample 

is routed through an NO2 to NO converter. In the presence of ozone, the 

chemiluminescence reaction yields excited NO2, oxygen, and a photon (NO + O3 →

NO2 + O2 + photon). The transition to this state produces light intensity 

proportional to the mass flow rate of NO2 into the reaction chamber. The light is 

measured by means of a photomultiplier tube and associated amplification 

electronics. NOx mass emission rates will be calculated as if all the NOx was in the 

form of NO2. This approach corresponds to EPA’s convention; however, it tends to 

overestimate the actual NOx mass emission rates since the majority of NOx is in the 

form of NO which has less mass per unit volume than NO2.

1.6.6 Propylene Emissions Analyzer

The concentrations of propylene, methane, ethane, propane, and butane will be 

measured in accordance with the procedures of EPA Method 18. A gas 

chromatograph will be used for these measurements.

1.7 Fuel Gas Sampling and Analysis

The fuel gas will be analyzed via a gas chromatograph to validate the measured fuel 

flows. The analysis will be made in accordance with the procedures of EPA Method 

18. 

1.8 Data Acquisition Systems

All acquisition systems will be synchronized at the beginning of each test day to a master 

clock which auto-synchronizes to the government generated time signals every evening.

A) John Zink Data Acquisition System

The John Zink data acquisition system logs data once per second. It is stored in a 

CSV format file which can be read by spreadsheet programs. All of the data logged 

will be visible real time in the flare test facility control room. The following 

information will be logged to this file:

 Date – Month/Day/Year

 Time – Hour:Minute:Second AM/PM

 Comment – Comment entered by operator to help sort data.

 Nitrogen or Hydrogen Flow Rate – lb/hr

 Natural Gas Flow Rate – lb/hr

 Propylene Differential Pressure Across Orifice – “H2O

 Propylene Static Pressure – psig

 Propylene Temperature – °F

 Propylene Flow Rate – lb/hr
Rev. 5 Document: 9136991-GP0-P07-0001 12

 Calculated Total Fuel Flow to Flare – lb/hr

 Calculated Lower Heating Value of Fuel to Flare – BTU/SCF

 Fuel Pressure at Burner – psig

 Mixed Fuel Temperature - °F

 Steam Flow Rate – lb/hr

 Steam Pressure Near Burner – psig

 Steam Temperature Near Burner – °F

 Temperature of Gases Entering Sample Collector (qty 3) - °F

 Calculated Average Temperature of Gases - °F

 Temperature of Gases at Sample Extraction Point - °F

 Differential Pressure Across Sample Collector Pitot – “H2O

 Static Pressure at Sample Collector Pitot – “H2O

 Calculated Flow Through Sample Collector - SCFH

 Ambient Temperature - °F

 Barometric Pressure – psia

 Wind Speed – mph

 Wind Direction – 0 = North, 90 = East, 180 = South, 270 = West

 Relative Humidity - %

B) CleanAir Engineering and TRC Data Acquisition System

One minute averages will be logged for the continuous monitors (O2, CO, CO2, 

NOx, and THC). The results of GC analysis will be logged internally to the GC. 

Barometric pressure, dry bulb temperature, and wet bulb temperature will be hand 

logged at the beginning of each test. PFTIR data will be logged in 1 minute 

averages.

1.9 General Conduct of Test

Two sets of tests will be conducted, tests of a pressure assisted burner and tests of a steam 

assisted burner. A single burner will be used for each pressure assisted emissions test. A 

single burner will be used for each steam assisted emissions test. The test burners will either 

be project burners or burners that are geometrically identical to project burners (same basic 

burner casting with the same size/number of ports). During testing, once the main flame is 

established on a burner, the pilot will be turned off for the emissions sampling portion of the 

test.

When all fuel flow conditions are stable, the sample gas collection apparatus will be 

positioned, by a crane, at a location above the visible flare flame. Prior to positioning the 

sample collector, all initial calibrations and other quality assurance activities will be complete. 

Samples of flare exhaust gas will be extracted from the sample collector and delivered 

through heat traced lines into the mobile laboratory. The sample gas will be conditioned, if 
Rev. 5 Document: 9136991-GP0-P07-0001 13

necessary, (dried for the CO, O2, NOx and CO2 analyzers) and delivered to each analyzer at the 

appropriate flow rate. When the analyzers respond to the exhaust gas and stabilize, a test 

run will be started. The data logger will record the concentrations from each analyzer over 

the test run period in one minute averages. At the beginning and end of each test run, a GC 

analysis of the incoming fuel will be performed. During the test period, GC analysis of the 

flue gas will occur periodically. Also, during the course of the 20 minute run time, an average 

bag sample of the flue gas will be extracted into two bags with one bag as primary and the 

second bag as a back-up. The primary bag sample will be analyzed at the conclusion of the 

test run via GC.

An additional, non-emissions, test will also be conducted. This additional test will consist of 

nine or more burners spaced the same distance as the project burners. This test will be 

conducted with 100% propylene. This test will demonstrate the cross-lighting of the burners 

as well as provide the length of the flame.
Rev. 5 Document: 9136991-GP0-P07-0001 14

QUALITY ASSURANCE AND QUALITY CONTROL ACTIVITIES

All instruments supplied and utilized by JZ will undergo calibration and span checks prior to testing. 

These calibration and span checks will validate the accuracy of the instruments as well as the 

proper logging of the data. All analytical instruments will be calibrated per their respective 

methods during the course of the test

After the testing has been completed, the collection hood will be positioned in clean air (air not 

effected by flare emissions) and a sample of ambient air will be analyzed to determine the ambient 

contribution to results collected during the testing.
Rev. 5 Document: 9136991-GP0-P07-0001 15

CALCULATIONS OF DESTRUCTION REMOVAL EFFICIENCY

AND COMBUSTION EFFICIENCY

The calculation of flare destruction removal efficiency (DRE) will be determined using the 

calculation techniques from 40 CFR 60, Appendix A, EPA Reference Method 19. Knowing the 

composition of the fuel, a fuel specific “F factor” (scf of combustion products / MMBtu of fuel 

burned) can be determined by the equations shown in Section 12.3.2.1 of EPA Reference Method 

19. The “F factor” is used to calculate the mass emission rate of the exhaust hydrocarbons as 

sampled from the gas collection apparatus. Both O2 and CO2 concentrations will be used to 

calculate dilution ratios resulting in the calculation of two DREs. Using the total hydrocarbon 

measurement, equations 19-4 and 19-8 of Method 19 can be used to calculate the mass of 

unburned hydrocarbons on a pounds per million BTU fired basis. Multiplying these numbers by the 

heat release of the hydrocarbon flowing to the flare will yield the pounds per hour of unburned 

hydrocarbons exiting the flare flame. Knowing the mass flow rate of hydrocarbon sent to the flare 

and the mass of unburned hydrocarbon exiting the flame, the destruction efficiency can be 

determined as follows:

 [

 

 ] 

The advantage of using this method is that all of the flare exhaust does not have to be captured. If 

the exhaust plume is diluted by ambient air (hydrocarbon concentrations biased low), the increased 

O2 or decreased CO2 in the exhaust sample will correct this bias by means of the dilution ratio 

component of the respective equations.

These same calculations will be repeated but instead of using the total hydrocarbon measurement, 

the propylene, propane, and butane measurements from the GC will be added and the sum used to 

determine destruction efficiency.

 [

 

 ] 

The combustion efficiency of the flare will also be calculated using the following equation:

 [

 

 

] 

Where CO2, CO, and THCd are the volume fractions of the components on a dry basis.
Rev. 5 Document: 9136991-GP0-P07-0001 16

FINAL REPORT CONTENTS

After the testing program is complete, all operational data is organized and labeled, all the testing 

results are reviewed and corrected for QA/QC activities, a formal test report will be prepared that 

documents the findings of the testing program. The test report will include the following items:

A) Introduction: A discussion of what was tested, why it was tested, and the goal of this

project.

B) Summary of Results:

1) Discussion of results

2) Discrepancies or problems that arose during tests

3) Tabular summaries containing the following:

a. Date, Test ID

b. Ambient Conditions

c. Process Data (fuel flows, burner pressure, etc.)

d. Calculated Process Values (fuel LHV, fuel exit velocity, etc.)

e. Propylene DRE (using THC & GC data and O2 as tracer)

f. Propylene DRE (using THC & GC data and CO2 as tracer)

g. Propylene DRE (using GC data and O2 as tracer)

h. Propylene DRE (using GC data and CO2 as tracer)

i. Combustion Efficiency

C) Test Protocol: A copy of this document.

D) Appendices:

1) CleanAir Engineering and TRC reports which will include:

a. Calculations Used in the Analysis

b. Detailed Results

c. Analytical Techniques

d. Quality Assurance Activities

e. Supporting Data

2) JZ Data Log Index

3) Calculations used by JZ

4) JZ Quality Control Documents

a. Calibration Records

b. Gas Analysis Records

Electronic copies of the JZ data logs will be supplied with the report.

Note: The final report will be non-confidential and can be placed into the public domain.
Rev. 5 Document: 9136991-GP0-P07-0001 17

APPENDIX A – PFTIR OPERATION AND CALIBRATION

PFTIR Operation

Passive Fourier Transform Infrared (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 my 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.

To monitor flares, standard absorption infrared spectroscopy could be used. However it 

is difficult to pass an infrared light beam through an elevated flare plume and then

capture the transmission. Fortunately, a passive approach is possible. 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 radiation emitted by hot gases has the same patterns or fingerprints as their 

absorption spectrum does. Consequently, observing a flare with an infrared instrument 

allows for identification and quantification of species through emission spectroscopy 

just as absorption spectroscopy can. However, there is one main difference: the 

signature arising from a hot gas is proportional to the gases concentration AND to its 

temperature. To do emission or radiance measurements therefore, the temperature must 

be deduced in addition to the gas concentrations.

When a PFTIR is used as an emission monitor it is calibrated in absolute radiance units. 

This calibrates the output voltage of the instrument to the received power per unit area of 

source, per unit solid angle of observation, and per unit wavelength or wave number 

(watts/cm

2

/steradian/wavenumber). This calibration uses a black body source. A 

Blackbody is an object that is perfectly absorbing throughout the infrared. If a body is 

perfectly absorbing, the Planck radiation law gives the power emitted by this body, when 

hot. This law states that the emission of a blackbody at a given absolute temperature (T),

and wave number ( ̃), is given by:

 ( ̃ ) 

 

 ̃ 

 

 ̃ 

(1)

Here h is Planck’s constant, c the speed of light, and k Boltzmann’s constant. This 

function looks like that shown in Figure A-1 at a temperature of 200 °C. As the 

temperature rises, the peak of this function moves toward larger wave numbers (smaller
Rev. 5 Document: 9136991-GP0-P07-0001 18

u

w/cm2/str/cm-1

wavelength) and it increases in intensity. For this reason, hotter objects will emit more in 

the short wavelengths or visible while cooler bodies emit in the longer wavelengths or the 

infrared.

70

60

50

40

30

20

10

0

0 1000 2000 3000 4000 5000

Wavenumbers (cm-1)

Figure A-1. Planck Function Showing the Radiation Emitted by a Blackbody at

200 °C

If a body is not “black” or totally absorbing, the energy it emits is just the Planck function 

times the body’s absorption. For example, if the body is 50% absorbing it will emit 50% 

of the Planck function.

Gases have highly variable absorption with wavelength. It is in fact this variation that 

produces the absorption patterns that allow for their identification in the infrared. If the 

transmission of a gas is given by τ( ̃,T) then [1 - τ( ̃,T)] is the amount of absorption. 

The radiation the gas emits at temperature T is then given by:

N( ̃ ) = [1 - τ ̃,T)] * Nbb( ̃,T) (2) 

For flare measurements, it is this signal that is being detected from the hot gases above

the combustion zone.

However, there are also other contributions to the signal an analyzer “sees.” As shown in 

Figure A-2, the background (typically the sky) has some emission, also defined by 

equation (2) that when transmitted through the plume and the intervening atmosphere is 

seen by the analyzer. The plume emissions transmitted through this same atmospheric 

path provides the signal of interest. The intervening atmosphere itself has some emission, 

which is also seen by the analyzer. The total radiant signal received then consists of:
Rev. 5 Document: 9136991-GP0-P07-0001 19

Background

Radiance Flare

Radiance

Atmospheric

Transmission

& Radiance

Figure A-2 Contributions to the measured flare radiance that must be accounted for.

The total radiant signal received then consists of:

 (3)

In Equation (3) the arguments ̃,T have been dropped for clarity and the individual terms 

are:

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
Rev. 5 Document: 9136991-GP0-P07-0001 20

The actual measurements performed by the PFTIR consist of the following:

Mflr =The measured plume radiance given by equation (3)

Mb = The measured background radiance taken by moving the PFTIR off the flare 

to monitor the sky background. This is given by

 

Mn = A measurement made looking at the calibration source (see below) with a 

cold (liquid nitrogen) emitter in place of the normal (black body)

Mbb = A measurement made looking at the calibration source with a 

commercial black body emitter in the source

τatm = Measured atmospheric path transmission

,

Based on these measurements Equation (3) can be rearranged to give the plume 

transmission as:

 

 ( ) 

 

 

 ( ) 

 

 

(4)

In this equation, the superscript on the Planck function radiance (NBB) denotes that this is 

the Planck function computed at the temperature of the flare. C is a calibration 

measurement made with a black body calibration source. The calibration source is a 

telescope identical to that of the PFTIR but with the capability of using various radiation 

sources. For C the radiation source is a commercial black body emitter. C then becomes 

the Planck function for the temperature of the black body divided by the measured 

radiance from the calibration source. This factor converts the FTIR voltages to radiance 

units and it is given by:

 

 

 

( )

(5)

The measured black body radiance (Mbb) has the cold source measurement (Mn) 

subtracted to cancel emissions from the intervening air and/or the PFTIR instrument 

itself.

Atmospheric transmission τatm is also measured using the calibration source. In this case 

the black body is replaced by a standard infrared source and the measurement is made at a 

path length roughly equal to that of the slant-path from the PFTIR to the flare.

Atmospheric transmission is then given by:
Rev. 5 Document: 9136991-GP0-P07-0001 21

 

 

 

(6)

MIR is the measured signal from the calibration source using the IR source and Mn is the 

measured cold source as defined earlier. The only term not defined is I0. This is the socalled synthetic background. It is frequently used in open-path FTIR measurements to 

convert a measured spectrum to transmission. It represents the shape of the spectrum that 

the PFTIR would measure if no gases were present. It can be synthesized from the (MIR–

Mn) measurement by doing a mathematical fit to points in the spectrum known to be free 

of molecular absorptions. An example is given in Figure A-3. In this Figure, the bottom

plot is the measured spectrum (here a relatively clean spectrum done in the laboratory), 

the middle plot the points chosen for fitting, and the top plot the mathematical fit to the 

chosen points. The top plot is the Io spectrum.

Figure A-3, an example of synthetic Io generation from a measured spectrum.

With equations (5) and (6), equation (4) then contains only measured or computed terms. 

However, to compute the Planck function at the temperature of the flare ( 

 ) the flare 

gas temperature must be known. Fortunately, this can be measured using features in the 

PFTIR data itself. One convenient feature is the CO band near 2150 cm

-1

.
Rev. 5 Document: 9136991-GP0-P07-0001 22

Figure A-4 shows this band at two different temperatures. The upper plot is at ambient 

temperature (300 K) and the bottom plot is at 550 K. The effect of increasing

temperature is to expand the band shifting the peak position away from band center 

while increasing the strength of the weaker lines farther from band center. This is a 

sensitive function of temperature, so the shape of the band essentially measures 

temperature.

0.035

CO 50 ppm 300K 760 Torr 1meter path

0.030

0.025

Ab0.020 

s

0.015

0.010

0.005

-0.000

0.016

CO 50 ppm 550K 760 Torr 1meter path

0.014

0.012

0.010

Ab

s 0.008

0.006

0.004

0.002

0.000

Figure A-4. Structure of the Fundamental CO Band at 300K (top) and 550K (bottom) 

Showing Alteration of Band Shape with Temperature

The CO lines arise (in emission) from a transition of the molecule from a higher 

vibration/rotation state to a lower one. The transitions are dictated by quantum 

mechanics. However, the intensities of the individual lines are strongly influenced by the 

number of molecules in the initial state available to make the transition. This “population” 

of the initial states is dictated by the Boltzmann distribution which is given by:

 

 

 

 

 

 (7)
Rev. 5 Document: 9136991-GP0-P07-0001 23

lo

g(I

nte

n

sit

y)

Here NJ” is the number of molecules in the initial rotational state defined by the rotational 

quantum number J”. N0 is the total number of molecules available, E” the energy of the

initial state, k Boltzmann’s constant, T the absolute temperature, and Q a “partition sum.” 

The partition sum is just the sum of the exponential term over all possible energy levels. If

the log of the measured intensity of the CO lines is plotted against the initial state energy, 

the plot is linear and its slope is proportional to

 

 

Where h is Planck’s constant and c the speed of light. Temperature can therefore be 

determined by measuring the slope of the plot. An example of this process is shown in 

Figure A-5. In this case the temperature was 225C and the group of lines to the left in

Figure A-4 were used. These are defined as the R-branch lines of the CO band.

-36

0 50 100 150 200 250 300 350 400 450 500

-36.5

T = 223.5 C

y = -5.518909E-03x - 3.596906E+01

R

2

= 9.961816E-01

-37

-37.5

-38

-38.5

-39

E"

Figure A-5, a plot of the CO line intensities versus initial state energy for 

determination of gas temperature.

Given temperature, all terms in Equation (4) can be determined. Equation (4) represents 

the transmission spectrum, just as would be observed if an active FTIR were used and an 

IR beam propagated through the plume. As a result, the same algorithms used in normal 

spectroscopy can be used to analyze this transmission spectrum. As in normal absorption 

spectroscopy, the transmission is exponential in gas concentration. That is transmission is 

given by:

 

 ( ) 

(8)
Rev. 5 Document: 9136991-GP0-P07-0001 24

Where K(υ) is the absorption coefficient for the spectral line, c the gas concentration, and 

l the path length in the gas. Effectively K(υ) is the reference standard in the FTIR for the 

gas being monitored. Taking the negative log of this equation gives what is called 

Absorbance. That is:

 ( ) ( ) (9)

Absorbance is linear in concentration times path length and the absorbance spectrum is

analyzed using standard Classical Least Squares procedures to get the individual gas 

concentrations in the spectrum. To compute combustion efficiency, the concentrations

of CO, CO2, and Total Hydrocarbon (THC) are used to compute:

 

[ ]

[ ] [ ] [ ] [ ]

The remaining term, [soot], is the concentration of any soot present. If it is present at any 

significant concentration, it will be seen in the IR spectra as an attenuation of the signal 

with characteristic spectral shapes driven by particle size distribution. It is not believed 

that soot will be a significant issue in most well run flares but if it is present, procedures 

can be developed to treat it.
Rev. 5 Document: 9136991-GP0-P07-0001 25

APPENDIX B – TEST ARRANGEMENT FOR PRESSURE ASSISTED BURNER
Rev. 5 Document: 9136991-GP0-P07-0001 26

APPENDIX C – PROPOSED FUEL COMPOSITION

The purpose of this section is to discuss the selected test fuel compositions.

The predicted compositions that will be sent to PDH-1 flare are shown in Table 1 below:

Table 1, PDH-1 Multi-Point Ground Flare Steams (weight %)

Compound Normal Net Gas RXPRD N2 Purge Mix Maintenance

Nitrogen - - - 73.80 - -

Carbon Dioxide - - - 1.10 - -

Hydrogen 2.11 64.46 4.200 - 17.73 2.11

Methane 1.92 31.46 2.600 23.30 8.38 1.92

Ethane 10.27 2.94 2.900 1.20 2.28 10.27

Ethylene 0.39 0.35 0.200 - 0.10 0.39

Propylene 27.85 0.45 28.900 - 33.33 27.85

Propane 57.32 0.33 61.100 0.40 36.88 57.32

Butene 0.05 - 0.000 - 0.33 0.05

Butane 0.05 - 0.100 - 1.00 0.05

Pentane - - 0.000 0.14 0.00 0.00

Benzene 0.04 - 0.000 0.19 0.00 0.04

The proposed test gases for the flare efficiency tests are propylene and mixtures of propylene/nitrogen 

and propylene/nitrogen/natural gas. Although propane is a major component in some of the cases from 

Table 1, the John Zink Co. flare test facility is equipped with a single vaporizer and only one fuel 

requiring vaporization can be run at a time. Previous flare testing [1] has shown that propylene is more 

difficult to completely combust than propane thus propylene was selected.

A major component in the “Net Gas” case is hydrogen. Given the difficulty of flowing significant 

quantities of hydrogen at the JZ flare test facility for any length of time, a short term test is proposed to 

validate the stability of the pressure assisted flare burner with a fuel containing a large proportion of 

hydrogen. Tests conducted by CMA [2] the EPA and EER [3] and the EPA and DuPont [4] clearly 

demonstrate that the burning efficiency of a flare is directly related to flame stability. If a 

predominately hydrogen fuel is stable in a pressure assisted flare burner at sonic velocity, the research 

indicates the destruction efficiency will be high. 

REFERENCES

[1] Marathon Petroleum Company LP, “Performance Test of a Steam-Assisted Elevated Flare with 

Passive FTIR – Detroit, Final Report”, November 23, 2010.

[2] Engineering Science, “A Report on a Flare Efficiency Study,” Volume 1 for Chemical Manufacturers 

Association, March 1983.
Rev. 5 Document: 9136991-GP0-P07-0001 27

[3] Pohl, J. H., and Soelberg, N.R., “Evaluation of the Efficiency of Industrial Flares: H2S Gas Mixtures and 

Pilot Assisted Flares,” Energy and Environmental Research Corporation, EPA Contract No. 68-02-3661, 

September 1986.

[4] Energy and Environmental Research Corporation, “Hydrogen Flare Equivalency Demonstration – Final 

Report”, October 14, 1997