Demonstration of Hydrogen Air-Assisted Fla

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Alexis McKittrick, Ph.D.Combustion R&DPraxair, Inc.

June 9, 2009

Demonstration ofHydrogen Use in Steam-and Air-Assisted Flares

www.praxair.com



Hydrogen as a Fuel

for Flaring

• Current EPA flare complianceoptions

– Non-assisted Flares:

• 200 Btu/scf minimum OR

• 8 volume % hydrogen minimum

– Assisted flares

• 300 Btu/scf minimum

• Natural gas added to “sweeten”low-Btu streams and comply withregulations

• Much less hydrogen than naturalgas is needed to comply with EPArequirements for low-Btu flarestreams

2

• Praxair pursuing modification of 40CFR 60.18 and 40 CFR 63.11 toextend the current specification toinclude steam- and air-assisted flares

• Potential benefits:

– Lower operating cost - 50% to 70%

reduction

– Lower environmental emissions –

CO2, CO, NOx

– Lower net natural gas consumption



Low-Btu Flaring for

Assisted Flares

WASTE30 Btu

(1000

NATURALGAS

(420 scf)

+

Currently, many flareoperators add natural gas to

the waste stream to complywith 300 Btu/scf regulation

3

GAS scf

cf)

HYDROGEN(130 scf)

+

Using Praxair’s proposedregulation, flare operators

could add Hydrogen to 11.5vol% to comply



Benefits ExampleAssisted Flare – 100k scfh st

Fuel gas required for compliance (scfh)

Annual fuel costs (24/7 operation, 340 d/y) $4/MMBtu Natural Gas

NOx emissions (ton/yr)

CO emissions (ton/yr)

CO2 emissions (ton/yr)

~$1MM/year in pot4

eam @ 30 Btu/scf

Natural Gas

300 Btu/scf

Hydrogen

11.5 vol.%

Reduction

(%)

42,000 13,000 69

$1,400,000 $425,000 70

11.8 1.9 84

60.2 9.9 84

19,363 2,605 87

ntial annual savings



Stream assumptions: waste gas volume = 100,000 scfh; waste gas heating

NOx & CO Calculations: Based on Standard Emissions Index from TCEQ’Flares and Vapor Oxidizers, October 2000, RG 109 (Draft) pg 18-19

Thermal NOX – 0.068 lb/MMBTU for steam assisted

CO - 0.3465 lb/MMBTU for steam assisted

CO2 Calculations: Based on 9.5lbs of CO2 for 1lb H2 produced from SMR; 11

Steam-Assisted Flare

Emissions Reduction

0

10

20

30

40

50

60

70

NOx CO

Emiss

ions(ton/ yr)

Natural gas fuel

Hydrogen fuel

5

alue = 30 BTU / scf; H2 volume % required = 11.5%

s Air Permit Technical Guidance for Chemical Sources:

3lbs CO2 for 1000scf of Natural Gas

–

ith Hydrogen

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

20,000

CO2

Natural gas fuel

Hydrogen fuel



Testing Hydrogen A

to Assisted Flares

• Flare testing facility built in Tonawand

NY – 1H 2008 – Variety of fuels

– Assist / non-assist operation

• Goal: Add hydrogen compliance optio

for assisted flares to EPA regulations

• Critical parameters:

– >98% destruction efficiency of

hydrocarbons

– Flame stability

– No visible emissions / smoke

6

dition

,



7



8



Assisted Flare Diagr

AirOutlet

SteamOutlet

Pilot GasInlet

SteamInlet

WasteGasInlet

AirInlet

Pi

Top View9

ms

ilot GasInlet Pilot

ConduitConnection

AirInlet

WasteGas

Inlet

SteamInlet

5’

Side View



Additional Conside

• Mirrored previous flare studies where

– Flame Stability and Destruction Effici

– Flare diameter – 3 inches

– Ethylene used as surrogate HAP

– Use of emissions capture hood

– CO2 used as a tracer to determine a• Simplification of assist – test “worst c

– Steam assist is simple 5 nozzle ring d

– Air assist will not use advanced mixin

• Baseline measurements – Test 300 Btu/scf waste stream for ea

– Replicate non-assisted hydrogen-fuelequivalency of Praxair’s testing

10

rations

er possible

ncy tests

ount of captured flare emissions se scenario”

esign

aides

h assist setting (mimics current operation)

d flare flame stability tests to demonstrate



Test Variables for

Assisted Flares

Variable

H2 volume %

Hydrocarbon heating value

Velocity

Steam Assist

Air Assist

11

Range / Value Tested

5 - 25%

30, 100, & 200 Btu/scf

20 - 150 ft/s

0.4 lb steam / lb ethylene

20% of stoichiometric airrequirement



Flame Stability Imag

Flare Pipe

Pilot

FlareTip

(A)

Flare Pipe

Pilot

FlareTip

(A)

Not

Lifted

12

s

Flare Pipe

Pilot

FlareTip

NoFlame

(B)

Flare Pipe

Pilot

FlareTip

NoFlame

(B)

LiftedFlame



Flame Stability Resu

Air-Assisted Flare

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

20%

0 50

Exit V

H y d

r o g e n V o l u m

e P e r c e n t ( %

)

13

ts –

100 150 200

locity (ft/s)




Steam-Assisted Flar

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

20%

0 50

Exit V

H y d r o g e n V o l u m e P e r c e n t ( % )

14

ts –

100 150 200

locity (ft/s)




• Fitting linear equations to t

results in the following:

• These equations can be usamount of hydrogen requirat a given exit velocity

Air-assisted flare: 04.0(%)2 = X H

Steam-assisted flare: 05.0(%)2 = X H

Where:

=(%)2 H X Hydrogen volume percent i

=) / ( s ft v Exit velocity of the flare (ex

15

ts

e flame stability data

ed to determine thed to ensure a stable flame

3.10) / (*9 +s ft v

83.9) / (*5 +s ft v

the waste gas exiting the flare

luding assist gas), not to exceed 150 ft/s



Destruction Efficien

Results Using Hydro

eating Value Assist

of Waste Gas Used Runs

(Btu/scf) n Average

30 Steam 3 99.77

100 Steam 4 99.94

200 Steam 3 99.99

30 Air 4 99.26

100 Air 4 99.90

200 Air 3 99.92

Destruc

16

y

en

Exit Flame

Velocity Stability

95% Confidence (ft/s) Ratio

99.61 151 1.03

99.92 150 1.04

99.98 151 1.03

99.02 150 1.02

99.88 150 1.02

99.90 150 1.02

ion Efficiency

(%)



Assisted Flare Testi

How Much Hydrogen

• Slightly morehydrogen requiredfor assisted flaresthan non-assisted

• These numbers

must be approvedby the EPA

• Assuming any newregulation will beequation-based(similar to currentcompliance options)

25

50

75

100

125

150

Exit Velocity

(ft/s)

17

g Results

?

No Assist Air-Assist Steam-Assist

8.0 11.5 11.3

10.2 12.7 12.7

12.4 14.0 14.1

14.5 15.2 15.6

- 16.4 17.0

- 17.6 18.5

Hydrogen Requirement (vol%)



Praxair Study Conclu

• Hydrogen use in assisted fl

flare testing as closely as p

• Results established a flameassisted flares over a range

• Destruction efficiencies aboall hydrogen-fueled conditio

• Requesting that 40CFR 60.include hydrogen as a comair-assisted flares based on

18

sions

res study mirrored previous

ssible

stability envelope forof velocities

e 99% were observed fors tested

8 & 63.11 be amended toliance option for steam- andthese findings

Demonstration of Hydrogen Air-Assisted Fla

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