Flare Gas Regulations and Monitoring TechnologiesLorenzo NirchiThursday, December 18, 2014
2
Overview
• Why we measure flare gas• Flare gas regulations• Technologies used to monitor flare gas• Dealing with carbon dioxide• Open forum for Q&A
3
Why measure flare gas flowACCOUNTABILITY
>Flare Base Load–Typically unknown
>Mass Balance–Complete balance–Drive flaring reduction
ENVIRONMENTAL>Mandatory Reporting>Avoidance of Penalties
–EPA, TCEQ, SCAQMD, EU, Kyoto,BOEM, 40CFR Part 98 (GHG),more
STEAM CONTROL–Steam Injection
•Complete burning•Smokeless operation
–Steam Consumption•Expensive•Flow rate controlled•Molecular weight
–proportion steamRECOVERY COMPRESSION
•Flare Gas as fuel
LEAK DETECTION–Molecular Weight
•Identification of source
–Leaky Valves•Potentially 1000’s in plant
FLARECRUDE
PRODUCT A
PRODUCT B
PRODUCT C
21
3 4
FurnaceProcess Unit
Waste Gas
4
What the Rule CoversNSPS Ja applies to flare systems as follows:• New Flares• Modification of existing flares (after
June 24th 2008)• Reconstructed flares (after June 24th
2008)
It is probably fair to say that the vast majority of flares in NA will be required to comply because they have been modified during the past few years
5
How many flares are affected?The EPA estimates that there are approximately 400 flares in the USA of which 70% will be subject to monitoring under these regulations.That’s 280 flares that will need attention…..Deadline to comply November 11th 2015
6
Flare Management PlanOperators are required to:• Establish baseline flare flow (not
including pilot and purge flows) based upon all inputs into the flare header system
• Implement Root Cause Analysis and Corrective Action Methods for unplanned flare events
• Establish maintenance procedures and routines
7
(i) Locate the monitor in a position that provides a representative measurement of the total gas flow rate.(ii) Use a flow sensor with a measurement sensitivity of no more than 5 percent of the flow rate or 10 cubic feet per minute, whichever is greater.(iii) Use a flow monitor that is maintainable online, is able to continuously correct for temperature and pressure and is able to record flow in standard conditions (as defined in § 60.2) over one-minute averages.(iv) At least quarterly, perform a visual inspection of all components of the monitor for physical and operational integrity and all electrical connections for oxidation and galvanic corrosion if the flow monitor is not equipped with a redundant flow sensor.(v) Recalibrate the flow monitor in accordance with the manufacturer’s procedures and specifications biennially (every two years) or at the frequency specified by the manufacturer.
§ 60.107a Monitoring of emissions and operations for fuel gas combustion devices and flares.
8
Flow Meter Performance Under JaWhat are the requirements for flow metering?60.107a(f)(1)(i) Locate the monitor in a position that provides a representative measurement of the total gas flow rate.
In other words:• Meter must be positioned in
the pipeline between all sources of gas and the flare itself
• Pilot Gas can be included as it is considered a constant flow and is part of the flare baseline flow – but this is not necessary
21
3 4
Meter goes hereGas
Sources
9
Flow Meter Performance Under JaWhat are the requirements for flow metering?60.107a(f)(1)(ii) Flare gas flow meters must have a measurement sensitivity of +/-5% of flow rate or 10cfm, whichever is greater.In other words:• Flow rates at or above 200cfm
must be sensitive to +/-5%• Flow rates below 200cfm must
be sensitive to +/-10cfm• On a 24” pipe size – 200cfm flow
rate~ 1ft/sec• On a 72” pipe size, 200 cfm flow
rates ~0.2ft/sec
Measurement of flare flow rate requires performance across a wide range of flow rates. A careful assessment of operating conditions should be carried out to estimate performance over the flow range of the meter
10
Flow Meter Performance Under JaWhat are the requirements for flow metering?60.107a(f)(1)(iii) Use a flow monitor that is maintainable online, is able to continuously correct for temperature and pressure and is able to record flow in standard conditions (as defined in § 60.2) over one-minute averages.In other words:• Electronic units must have the
ability to calculate volume flow at standard conditions and to either read line pressure and temperature directly or have input capability for values from external devices
11
Flare Gas: Why Measure Ultrasonically?FLARE GAS
> Variable Flow Rates– Low flow = normal flare– Moderate flow = inadvertent flare– High flow = emergency flare
> Variable Composition– Range of hydrocarbons– H2 to C6 + (typical)
> Corrosive Environment– H2S, HF etc.– Liquid dropout
> Low Pressure– Atmospheric (slightly negative to
slightly positive)> Wide Temperature Range
– From –150C to 280C overall
21
3 4
Conventional technologies allhave problems with one or moreof these characteristics of flare gas operation, resulting in inaccuracy,poor reliability and high cost of ownership. The required turn-down ratioand low-end sensitivityfar exceeds conventionalflow measurement technologies
12
Flare Gas Flowmeter: Hardware OverviewModel GF868 Flare Gas Ultrasonic Flowmeter:
13
The Flare Gas Flowmeter: Transducers
Configurations
14
• Solutions:• Full Diameter Path Length
• Longer paths with high power transducers capture a full cross section of the flow in the pipe.
• Apply Two Cross Paths• Look at flow in two directions -
cancel/reduce cross Flow
Installed system with a dual diagonal TD45 path arrangement.
Low Flow Method and Solution
New T17 high power transducer – 3 times more
signal energy than existing designs
15
FAN GENERATES
CROSS FLOW
Channel 1
Channel 2
Two channel GF for two crossed paths. Log flow for both channels with and without cross flow.
Flare Gas Flowmeter: Low Flow RateCross flow-demonstration test
Cross flow Verification Results
Each channel sees a different “slice” of the cross flow currents. When averaged together, net result is zero.
16
CFD Models used to define issue and recommend path configuration for best performanceT17 high power transducer allows long path length in big pipes – increased tolerance to non-perfect flow profile
Typical Convection Problem Simulation
2
2’ 1
1’
Low Flow / Cross Flow Field Performance
T17 Transducer
2 cross paths give best performance in low flow with cross flow regime
17
Accuracy
Single path system shows Max uncertainty of 8.0% at rates below 1ft/sec. Dual path averaging reduces this further to 5.7%.
18
Published ResultsProven performance from testing results in high confidence in operation.
GE has performed relevant and specific testing to ensure flare system products can meet EPA rules and performance is defendable against published white papers
19
The Problem with High Velocity Flow…
• Signal is “swept away” by the flow
• When high flow occurs, measurement is lost
Hey Freddie!
What did you say?
20
Methodology: Sending the signal “upstream” into the flow stops it being swept away and ensures that the signal reaches the upstream transducer
Extended Velocity Range Solution Recovery Angle
The transducer with recovery angle isthe downstream transducer orientatedto transmit into the oncoming flow
6º
45ºFlow Transducer
Transducer
Transducer with 6º recovery angle
Standard Transducer
Care needed for orientation at i t ll ti !
21
Performance is verified by calibration in a National Standards (NIST) traceable facility reference paper.
22
Diagonal 45° for pipes14-inch/350 mm
Flare Gas: Hardware Installation
23
The Flare Gas “Flow-cell”
Spool-piece
When ultrasonic transducers are arranged relative to each other to make a flow measurement, a “flow-cell” is created. There are two major types:
Hot-tap (or cold-tap)
Hole-saw
Pilot-drill
24
Bias 90 Mid-radius forpipes 16-inch/400 mm
Flare Gas: Hardware Installation
25
The Flare Gas Flowmeter: “Flow-cell”
Spool-piece
When ultrasonic transducers are arranged relative to each other to make a flow measurement, a “flow-cell” is created, There are two major types:
Hot-tap (or cold-tap)
Hole-sawPilot-drill
Coupon retaining finger
26
“Flow-cell” Types: Spool-piece
• Manufactured under safe, controlled conditions
• Precise• Suitable for new-build• Requires shutdown for
retro-fit• Allows full functional test • Can be “wet” calibrated by
accredited third-party facility• Allows full functional test
& “dry” calibration before delivery
Spool-piece
27
Barrel
Packing Gland
Isolation Valve
IMA Assembly
“Flow-cell” Types: Hot-Tap / Cold-Tap Nozzle & Insertion Hardware
Nozzles
Pre-Cut for Pipe ODPre-Cut for Installation Configuration
> Bias 90> Diagonal 45
Specified MaterialsFlange type and RatingNDE RequirementsInstallation Jig & Kit
28
Flowmeter Electronics
•Package Standard: Epoxy-coated aluminum weatherproof Type
4X/IP66 Class I, Div 2, Groups A,B,C&D FM and CSAOptional: 19-inch rack
Type 4/7 xproof for Class I, Div 1, Group B,C&D EExd IIC T6 flameproof
• 110/120 VAC, 230/240 VAC, • 12-28 VDC• 1 or 2 channel• Text/Graphics Display & Keypad • Two analogue inputs (T & P)• Six, isolated analogue outputs• Velocity range 0.03-120 m/s• Mw range 2–120 g/mole• Actual & Standard Volume, Mass
Specification
29
Flare Gas: Installation Requirements• Ultrasonic Flare Gas Flowmeters sample along one or two acoustic
paths at the diameter or off diameter (e.g. mid-radius) • Specifications assume a fully developed flow profile. This is installation
dependent and may require a straight pipe run of 20 diameters upstream and 10 diameters downstream
• Evaluation of the intended installation site at enquiry stage is recommended
• For hot-tap/cold-tap installations, a dimensional survey is recommended particularly for exotic/thin-wall materials e.g. Schedule 10S
If the disturbance source creates swirl, the straight run may need to be much higher!
“Swirl generator!!”
30
Extended Velocity Range•Higher Velocity Range is Standard
•328 f/s (100 m/s) max velocity (was 275 f/s)
•Transformer on Preamp•New Extended Range
• 394 f/s (120 m/s ) max velocity•Transformer on Preamp•Short Path•Recovery Angle
New Data sheet for the GF868 with revised specs for both systems. Bias 90 and Diagonal 45 configurations included
An ultrasonic flowmeter has beendeveloped and tested for high-velocity gasmeasurement up to 123.7 m/s in air. Theaccuracy of the new meter isdemonstrated to be better than 3-4% withreference meter uncertainty included, andthe relative standard deviation of the newmeter is within 1.2%.
31
Design of Transducer Dimensions, Separation, and Frequency
We have designed our transducers with a radius of 0.375” and a frequency of 100 kHz, and chosen a separation of the transducer pair of ~6.5 to 7.8”. LR
a
ultrasound propagation in a medium across both near field and far field, nominally separated by Rayleigh Distance, LR.
z
Extended Velocity Range Methodology:
Recovery AngleThe recovery angle is on thedownstream transducer by rotating it 60
into the flow.Upstream Beam Drift
-35
-30
-25
-20
-15
-10
-5
0
0 10 20 30 40 50 60 70 80 90
M = 0.1M = 0.2M = 0.3M = 0.4M = 0.5
Downstream Beam Drift
0
5
10
15
20
25
30
0 10 20 30 40 50 60 70 80 90
M = 0.1M = 0.2M = 0.3M = 0.4M = 0.5
(a)
(b)
Downstream ultrasonic beam drift angle as a function of ultrasonic path angle at different Mach numbers; (b) Upstream ultrasonic beam drift angle as a function of ultrasonic path angle at different Mach numbers.
Conceptual design of the flare gas ultrasonic flowmeter.
6º
45ºFlow
TransducerP~6.5 to 7.8” Transducer
32
Performance is verified by calibration in a National Standards (NIST) traceable facility-Reference Paper.
33
Calibration Example: 24”
34
Low Flow Methodology•Users and Regulators realizing continuous low flow adds up
> Stack allocation can be reached with low flow, not just relief flow > North America, Europe, Asia all requesting flow accuracy for 0.1 to 1 f/s velocity
•Accuracy Requirements at 0.1 to 1 f/s are currently at +/-20%> Trend is to better: 5%
•Problems• Better Accuracy/Resolution at Low Flow• Better Average of Asymmetric Flow • Convection flow-cross flow-circulation: may dominate at very low flow rates
35
History for Beaumont, TXOctober 21, 2009 through October 28, 2009
Refinery-Beaumont, TX24” flare line
~0.3 f/s
Convection flow & Stratification
36
History for Bay City(Sweeny), TX September 23, 2004 through September 30, 2004
Refinery-Sweeny,Texas66” Flare line
Convection flow
37
•Solutions:>Apply Two or more Paths
–One path for high flow–One (longer) path for low flow–Look at more area of flow
–Cross Paths–Cancel/Reduce Cross Flow
A combination of the two types of installation in a two-channel meter allows the low flows to be measured by the Diagonal 45 configuration, and the high flows by the Bias 90. Additional paths, paths of longer length, unconventional configurations and location of paths are all used.
Bias 90 on the top and a mid-radius Diagonal 45 below
Installed systems of two-path bias 90 (high flow) and a two-path Diagonal 45 (low flow). Note separation of the two-path systems to avoid potential acoustic crosstalk
Low Flow Methodology
38
Green House Gas: Dealing with CO2•New Green House Gas (GHG) Monitoring requirements> From EPA: 40CFR Mandatory Reporting of Greenhouse Gases; Final Rule
– “requires reporting of annual emissions of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), sulfur hexafluoride (SF6), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and other fluorinated gases (e.g., nitrogen trifluoride (NF3) and hydrofluorinated
ethers (HFEs)”
> Part 98: Stationary Sources– Subpart
• C. General Stationary Fuel Combustion Sources • P. Hydrogen Production • X. Petrochemical Production • Y. Petroleum Refineries • MM. Suppliers of Petroleum Products • NN. Suppliers of Natural Gas and Natural Gas Liquids
– Flare Gas• Subpart 98.254
– General Stacks• Fuel, Flue, Vent
> Meter Requirements– 5% accuracy (Range TBD)– Yearly Verification (Driving Service contracts)– Within 1 year installation-or sooner
39
HIGH CO2 CONTENT FLOW MEASUREMENT
The flow rate of Flare Gas with a high concentration of Carbon Dioxide is becoming an important measurement for the petrochemical industry. In fact very new legislation for monitoring of Green House Gases has been issued by the EPA in the USA under 40CFRMandatory Reporting of Greenhouse Gases; Final Rule. Flare gas monitoring for calculating CO2 emissions is mandated under Part 98 and covers petrochemical facilities. The EU has had directives for reporting of GHG for sometime now.
Green House Gas: Dealing with CO2
40
Data collected on flare gases by Exxon/Panametrics
HIGH CO2 CONTENT FLOW MEASUREMENT
Known to have an attenuating effect on ultrasound, well characterised since 1950s).(1951, Rev of Modern Physics, Vol 23, page 353)Classical attenuation:
Due to scattering viscosity etc.Relaxation Effect:
Energy absorption by CO2 molecules
CO2 Attenuation
41
HIGH CO2 CONTENT FLOW MEASUREMENTStudy of CO2 attenuation was conducted in 2005 to model the effects on ultrasound.
From the above equation, we can see that the signal strength is only associated with the density and attenuation factor of the gas mixture.
t r
iV oV
One transducer transmits acoustic waves into acoustic medium (a mixture of CO2 and N2) and one receiving transducer receives those waves.
c
Df
io eVV
/
The relationship of the signal strength to the fraction of CO2 in N2.
Meter accuracy is limited by signal to noise ratio, not by CO2 concentration
A variety of ultrasonic transducers, at different frequencies, are used in flare gas flow measurement.
Solutions are provided based on the available piping configuration, and the gas conditions
Transducer Offerings
42
application Press (barg) Press (atm) Temp. (degree C)
Pipe Size (Meter Size)
Pipe Schedule
Flow Rate(MMSCMD)
CO2 mole%
Mcycles/atm
XGM with 200 khz BWT 1.39 1.372 185 ? ? ? 78.5-90 0.146
XGM with T14 1.59 1.57 65 ? ? ? 78.5-90 0.063
Typical flare gas application
Power Plants Min Press (barg)
Max Press (barg)
Temp.(degree
C)
Pipe Size (Meter Size)
Pipe Schedule
Flow Rate(MMSCMD)
CO2mole%
Mcycles/atm(100 kHz)/
min P
Mcycles/atm(100 kHz)/
max P
I 15 20 22.28 DN450 Sch40 4.543 20%+ 0.0067 0.005II, III, IV 40 60 22.61 DN400 Sch40 3.936 20%+ 0.0025 0.00167
T N 15 20 30.01 DN250 Sch40 1.343 20%+ 0.0067 0.005
Typical flare gas application
Customer Example: Higher Pressure Customer Example: Lower Pressure
Evaluation of specific applications with CO2
43
Process Applications with CO2
ApplicationNatural Gas Transport Process (1%) Process process
Power Plant
H2 Blow by
Coke Oven Gas
(COG) COG COG Steel (LDG) Flue Stack
Process BFG (Flue)
Blast Furnace
Gas Flare
Flare-CO2 Recovery Injection Flare
Qty/Size 9 24" 1 x 14" 1 x 400mm 1 x 3" 1 1 x 40" 1 x 40" 1 x 1829 mm 6.34 meter 1 1 x 40" 1 x 24" 3 x 12-24" 1 x 36"location Kazakhstan Wyoming, USA California,USA East europe Japan Asia Japan Japan Japan Spain Asia Japan Texas, USA Texas, USA Wyoming, USAUser IHC/SBM Exxonmobil Exxon ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- Oil co. AmocoInstall date 2005 2004 2003 <2009 2008 2007 <2008 2008/2009 2009 2005 2007 2008 2008 ~1995 1994pressure 28 bar (600#) 2.04 bar 1.08 bar 3 bar 1.039 bar 1.045 bar 1.196 bar amb (1 bar) amb (1 bar) 1.078 bar 1.062 bar 1.55 bar 1-1.3 bar amb (1 bar)
Methane 51.076 1.5 26.6 29.2 1.4Nitrogen 0.562 3 48 2.3 3.4 18.1 71.8 54.1Ethane 10.785 2.3 0.82Propane 5.335 0.62Iso-butane 0.765N-butane 1.511Iso-Pentane 0.401N-pentane 0.394CO2 5.649 69 100 7 100 3.1 2 2.1 16.4 14.2 20.7 23 97.16 85-90 >95CO 22 8.4 6.1 64.6 22H2S 22.076Hydrogen 12 18 56.4 56.4 0.9 3.2HexaneC6+ 0.65H2O 0.796 5 10.88Other 14.5 2.9 98 0.5 77 15-Oct <5Oxygen 0.3 3.12
Composition
One major feature that differentiates the GE Sensing meter from other ultrasonic meters is the power of the transducer we designed and use.
This installation is on a 14 inch pipe, with a 19 inch path. In 100% pure CO2. Temperature is ambient and pressure approximately 30 PSIA. Plot of freq/pressure =0.05 with a 100 kHz transducer is shown.
44
Questions