institute of chemical kinetics & combustion, novosibirsk 630090 russia

Reducing of kinetic scheme for syngas oxidation at high pressure

and elevated temperature Bolshova T.A., Shmakov A.G., Yakimov S.A.,

Knyazkov D.A., Korobeinichev O.P.

Institute of Chemical Kinetics & Combustion, Novosibirsk 630090 Russia

7th International Seminar on Flame Structure, July 11 -15, 2011

Introduction• SYNGAS, components: H2 + CO • Production technology:

– Gasification of fossil fuels (mineral and brown coal)

– Processing of natural gas and natural hydrocarbons (catalytic and thermal methods)

– Gasification of combustible wastes• Spheres of application:

– Power engineering – Chemical engineering

• Problems: – Fire safety– Toxicity– Development of high-tech devices for

power chemical engineering (turbines, reactors, etc.)

The scheme of power station with the integrated cycle of gasification.

Introduction

The gas turbine

Introduction

P0 - up to 40 atm,

T0 - up to 700 оС

Research ObjectivesResearch Objectives

•Development of the reduced reaction mechanism for syngas oxidation at temperature Т0=300-700 K and pressure Р=10-30 bar

•Validation of the proposed reduced mechanism by comparing the simulated burning rate with experimental literature data

Characteristics of Unburnt Gases•The fraction of CO in the fuel :

а=[CO]/([CO]+[H2])=0.05 0.5 and 0.75

•The dilution ratio:D=[O2]/([O2]+[N2])=0.209

(for fuel/air mixtures).

•Equivalence ratio was :f=([CO]+[H2])/2[O2],

where [O2], [N2], [CO] and [H2] - are concentration of oxygen, nitrogen, carbon monoxide and hydrogen respectively.

BackgroundLiterature experimental data

Mechanism for modeling H2, CO oxidation.

Authors Reactions Т0, K P, atm Initial data Dixon-Lewis and Williams (1977)

19 298 1(N2) H2/CO/O2 0.01/66/33-2/66/33

Konnov (2000) 40 298 1(N2) CO/H2 (95/5)/ air 20% (CO+H2)/ air 14% (CO+H2) / air CO/H2/ air (=1)

Davis et al (2005) 30 298 1 (N2) 1, 15 (He)

H2/air (φ=1 и 3)

H2/O2/He (φ=1-2.25) H2/CO/air (φ=1-.89)

Saxena and Williams (2006)

30 298 1 (N2) 10-20 ((He)

H2/O2/( N2, Ar, He) D=0.214; H2/O2/He D= 0.08

Li et al. (2007) 31 298 1 (N2) CO/H2=95/5 (=0.5-6)

CO/H2=50/50 (=0.5-4.5) H2/CO/N2 (28/25/47) (=0.7-1.4)

Sun et al. (2007) 48 298 1-2 (N2) 5-40 (He)

H2/CO/air (=0.5-5) H2/CO/O2/He (=0.7-3.5)

Background

Model Sun H., Yang S.I., Jomaas G., Law C.K. (Proceedings of

the Combustion Institute 31, 2007)

H2 O2 H2OH O OH HO2 H2O2

CO CO2 HCOCH2O CH2OH

AR N2 HE

16 SPECIES and 48 REACTIONS

R1 H+O2=O+OH R2 O+H2=H+OH R3 O+H2=H+OH R4 H2+OH=H2O+H R9 H2+H2O=H+H+H2O R13 O+H+M=OH+M R14 H+OH+M=H2O+M R15 H+O2(+M)=HO2(+M) R19 H2+O2=HO2+H R21 HO2+H=OH+OH R22 HO2+O=O2+OH R23 HO2+OH=H2O+O2

R1 H+O2=O+OH R2 O+H2=H+OHR3 O+H2=H+OH R4 H2+OH=H2O+HR5 OH+OH=O+H2O R13 O+H+M=OH+MR14 H+OH+M=H2O+M R15 H+O2(+M)=HO2(+M)R19 H2+O2=HO2+H R21 HO2+H=OH+OHR23 HO2+OH=H2O+O2 R24 HO2+OH=H2O+O2R27 H2O2(+M)=OH+OH(+M) R36 CO+OH=CO2+HR37 CO+OH=CO2+H R38 CO+OH=CO2+H

-0,4 -0,2 0 0,2 0,4

R1

R2

R3

R4

R9

R13

R14

R15

R19

R21

R22

R23

30 atm

20 atm

10 atm

-0,4 -0,2 0 0,2 0,4

R1R2R3R4R5

R13R14R15R19R21R23R24R27R36R37R38

30 atm

20 atm

10 atm

The sensitivity coefficients of burning velocity to the reactions rate constants for H2/CO/air flame, р=10, 20, 30 bar

CO 5% CO 50%T0=300 K

f=1

R1 H+O2=O+OHR15 H+O2(+M)=HO2(+M)

R36+R37+R38 CO+OH=CO2+H

The sensitivity coefficients of burning velocity to the reactions rate constants for H2/CO/air flame, р= 20 bar

=0.5, T0=300 and 700 K, =0.75

R1 H+O2=O+OHR3 O+H2=H+OHR4 H2+OH=H2O+HR14 H+OH+M=H2O+MR15 H+O2(+M)=HO2(+M)R19 H2+O2=HO2+H R21 HO2+H=OH+OHR36 CO+OH=CO2+HR37 CO+OH=CO2+HR38 CO+OH=CO2+H

A rise of initial temperature does not influence on key reactions set

The sensitivity coefficients of burning velocity to the reactions rate constants for H2/CO/air flame, р= 20 bar

=0.5, T0=300 and 700 K, =3.5

The most appreciable changes of sensitivity coefficients as T0 rises from 300 to 700

K are observed in the rich flame for reactions R4 (in 8 times) and R15 (in 2 times).

R4 H2+OH=H2O+H

R15 H+O2(+M)=HO2(+M)

The sensitivity coefficients of burning velocity to the reactions rate constants for H2/CO/air flame, T0=300K, =0.5, р= 20 bar

-0,3 -0,1 0,1 0,3 0,5 0,7 0,9

R1

R2

R3

R4

R5

R6

R7

R13

R14

R15

R19

R21

R22

R23

R24

R27

R33

R36

R37

R38

R39

R40

f=3,5

f=1

f=0,75

R39 HCO+M=H+CO+MR40 HCO+H=CO+H2

R1 H+O2=O+OH

R19 H2+O2=HO2+H R21 HO2+H=OH+OH

The value of sensitivity coefficient to rate constants of the reactions depends on equivalence ratio .

-0,06

-0,04

-0,02

0,00

0,02

0,04

0,06

700 1200

temperature, K

rate

of

pro

du

cti

on

of

H,m

ole

/cm

3-s

ec

R1 H+O2=O+OH

R3 O+H2=H+OH

R4 H2+OH=H2O+H

R15 H+O2(+M)=HO2(+M)

R21 HO2+H=OH+OH

R37 CO+OH=CO2+H

R38 CO+OH=CO2+H

-0,80

-0,40

0,00

0,40

0,80

1,20

1,60

2,00

2,40

700 900 1100 1300 1500 1700

temperature, K

rate

of

pro

du

ctio

n o

f H

,mo

le/c

m3-

se

c

R1 H+O2=O+OH

R3 O+H2=H+OH

R4 H2+OH=H2O+H

R15 H+O2(+M)=HO2(+M)

R21 HO2+H=OH+OH

The rate of production of H in H2/CO/air flame, T0=700K, =0.5, р= 20 atm.

=0.3 =4.5

R4 H2+OH=H2O+HR3 H2O+H2=H+OHR37+R38 CO+OH=CO2+H

R1 H+O2=O+OHR15 H+O2(+M)=HO2(+M)

R4 H2+OH=H2O+HR3 H2O+H2=H+OH

R1 H+O2=O+OHR15 H+O2(+M)=HO2(+M)R21 HO2+H=OH+OH

-0,023

-0,020

-0,017

-0,014

-0,011

-0,008

-0,005

-0,002

700 1000 1300 1600

temperature, K

rate

of

pro

du

ctio

n o

f C

O,m

ole

/cm

3-se

c

R33 CO+O+M=CO2+M

R36 CO+OH=CO2+H

R37 CO+OH=CO2+H

R38 CO+OH=CO2+H

-0,0015

-0,0012

-0,0009

-0,0006

-0,0003

0,0000

0,0003

0,0006

0,0009

700 1000 1300

temperature, K

rate

of

pro

du

ctio

n o

f C

O,m

ole

/cm

3-se

c

R33 CO+O+M=CO2+M

R35 CO+HO2=CO2+OH

R37 CO+OH=CO2+H

R38 CO+OH=CO2+H

R39 HCO+M=H+CO+M

R40 HCO+H=CO+H2

R47 HCO+O2=CO+HO2

R48 HCO+O2=CO+HO2

The rate of production of CO in H2/CO/air flame, T0=700K, =0.5, р= 20 atm.

=0.3 =12

R36+R37+R38 CO+OH=CO2+H

R39 HCO+M=H+CO+MR35 CO+HO2=CO2+OH

R47 HCO+O2=CO+HO2

Н2

Н+OH

H2O+H

+O

+OH

74% 25%

CO

CO2 CO2+H

+O

+OH

94% 5%

Н2

Н+OH

H2O+H

+O

+OH

77% 23%

CO

CO2

CO2+H

+O

+OH

85%

6% +H

HCO

9%

Н2

Н+OH

H2O+H

+O

+OH

83% 17%

CO

CO2

CO2+H

+O

+OH

56%

5% +H

HCO

39%

=0.75

=2.0

=4.0

The main pathways for H2 and CO consumption in H2/CO/air flame, р= 20 atm, T0=300K, =0.5

A reduced reaction mechanism for oxidation of H2/CO/O2

№ Reartion A* n Ea*

S1. H+O2=O+OH 6.73e+15 -0.5 16670

S2. O+H2=H+OH 5.06E+4 2.67 6290

S3. H2+OH=H2O+H 1.168E+08 1.52 3457.4

S4. OH+OH=O+H2O 3.348e+04 2.42 -1927

S5. H+H+M=H2+M 7.00E+17 -1.0 0.0

S6. H+OH+M=H2O+M 2.212E+22 -2.0 0.0

S7. H+O2(+M)=HO2(+M) 4.65E+12 0.44 0.0

S8. H2+O2=HO2+H 7.395E+05 2.433 53502

S9. HO2+H=OH+OH 6.0E+13 0.0 295

S10. HO2+OH=H2O+O2 5E+13 0.0 1105.8

S11. CO+O+M=CO2+M 3.0E+14 0.0 3000

S12. CO+OH=CO2+H 1.8E+5 1.9 -1160

S13. HCO+M=H+CO+M 4.0E+13 0.0 15540

S14. HCO+H=CO+H2 1.11E+14 0.0 0.0* – In: cm3, mole, s, cal; rate constant expressed as k=A Tn exp (-Ea/RT)

13 species (H2, O2, H2O, H, O, OH, HO2, CO, CO2, HCO, Ar, He and N2) and 14 reactions

Flame speed of CO/H2/Air mixtures as function of equivalence ratio at P=10-30 atm,

=0.05, 0.5, 0.75.

5% CO+ 95% H2

Equivalence ratio

0 1 2 3 4 5 6 7

Bur

n ve

loci

ty, c

m/s

0

50

100

150

200

250

10 atm, full mech20 atm, full mech30 atm, full mech10 atm, short mech (var 9)20 atm, short mech (var 9)30 atm, short mech (var 9)

50% CO+ 50% H2

Equivalence ratio

0 1 2 3 4 5 6 7

Bur

n ve

loci

ty, c

m/s

0

20

40

60

80

100

120

140

75% CO+ 25% H2

Equivalence ratio

0 1 2 3 4 5 6 7

Bur

n ve

loci

ty, c

m/s

0

20

40

60

80

100

T0=300 K



5%CO+95%H2

Equivalence ratio

0 2 4 6 8 10 12

Fla

me

spee

d, c

m/s

0

100

200

300

400

500

600

50%CO+50%H2

Equivalence ratio

0 2 4 6 8 10 12

Fla

me

spee

d, c

m/s

0

50

100

150

200

250

300

350

75%CO+25%H2

Equivalence ratio0 2 4 6 8 10 12

Fla

me

spee

d, c

m/s

0

50

100

150

200

250

T0=500 K




5%CO+95%H2

Equivalence ratio

0 2 4 6 8 10 12 14 16 18

Flam

e sp

eed,

cm

/s

0

200

400

600

800

1000

1200

T0=700 K

50%CO+50%H2

Equivalence ratio

0 5 10 15 20

Flam

e sp

eed,

cm

/s

0

100

200

300

400

500

600

700

75%CO+25%H2

Equivalence ratio

0 2 4 6 8 10 12 14 16 18

Flam

e sp

eed,

cm

/s

0

100

200

300

400

500




Thin lines: model of Sun H. et al., lines with symbols: reduced mechanism

Testing of the reduced mechanism

Flame speed of CO/H2/O2/He mixtures as function of equivalence ratio

0 1 2 3 4 5 6

Fla

me

sp

ee

d,

cm/s

0

50

100

150

200

Full mech, (Sun H. et al, 2007)Exp. data (Sun H. et al, 2007)Short mech., Var 9

CO/H2/O2/He

CO/H2=50/50 T0=300 K, P=10 atm, D=0.125CO/H2/O2/He

CO/H2=75/25 T0=300 K, P=20 atm, D=0.125

0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5

Flam

e sp

eed,

cm

/s0

20

40

60

80

100

120

Exp. data (Sun H. et al, 2007)Short mech., Var 9


Triangles: experimental data of Sun et al., dashed line: mechanism of Sun et al., circles: reduced mechanism

P=20 barP=10 bar

CO/H2/O2/HeCO/H2=95/5 T0=300 K, P=40 atm, D=0.125

1,0 1,5 2,0 2,5 3,0

Fla

me

spee

d, c

m/s

0

10

20

30

40

50

Experimental data (Sun H. et al, 2007)Short mech, var 9


Flame speed of CO/H2/O2/He mixtures as function of equivalence ratio

P=40 bar

Triangles: experimental data of Sun et al., circles: reduced mechanism

Diamonds and triangles : experimental data of Natarajan et al, circles: reduced mechanism

0,0 0,2 0,4 0,6 0,8 1,0

Fla

me s

pee

d, c

m/s

10

25

40

55

70

Short mech, 14 reactions

Experimental data

P=15 bar, T0=300 K, =0.8, O2:He=1:9

0,0 0,2 0,4 0,6 0,8 1,0F

lam

e sp

eed

, cm

/s25

50

75

100

125

150

Short mech, var 9

Experimental data

P=15 bar, T0=600 K, =0.6, O2:He=1:9

Testing of the reduced mechanismFlame speed of CO/H2/O2/He mixtures as function as function of

at P=15 atm, T0=300K. ( =[CO]/([CO]+[H2])

=0.6=0.8

Lines: mechanism of Sun et al., symbols: reduced mechanism

mm

0,50 0,55 0,60 0,65 0,70 0,75

Mol

e fr

actio

n

0,00

0,05

0,10

0,15

0,20

Tem

pera

ture

, K0

500

1000

1500

2000

2500

H2COO2TÍ 2ÎCO2H2 short mechO2 short mechH2O short mechCO short mechCO2 short mechT short mech

CO+H2/AirP=20 atm, f=1, a=0.5, T0=300K

T

H2CO2

H2O

CO

O2

mm

0,50 0,55 0,60 0,65 0,70 0,75M

ole

frac

tion

0,000

0,002

0,004

0,006

0,008

0,010

HOHOHCO (x100)HO2Î Í short mechÍ short mechÎ short mechHO2 short mechHCO (x100) short mech

OH

H

O

Testing of the reduced mechanismTemperature and concentration profiles in CO/H2/Air flame (=0.5,

Р=20 atm, T0=300K, =1)

Summary1.1.Developed reduced reaction mechanism Developed reduced reaction mechanism

for syngas oxidation (14 steps, 13 species) for syngas oxidation (14 steps, 13 species) satisfactorily predicts burning velocity at satisfactorily predicts burning velocity at P=10-P=10-330 0 atm,atm, T T00=300-=300-7700K, 00K, and and =0.05 0.05 0.0.775.5.

2.2.In HIn H22//CO CO mixtures with mixtures with с с =0.05 =0.05 the the reaction from Hreaction from H22 oxidation were shown to be oxidation were shown to be key reactions; at key reactions; at =0.5 and higher the role of =0.5 and higher the role of reaction CO+OH=CO2+H appreciably reaction CO+OH=CO2+H appreciably increases.increases.

3.3.Pressure rise from 10 to 30 atm was not Pressure rise from 10 to 30 atm was not shown to influence the set of key reactionsshown to influence the set of key reactions..

4.4.HCO-involving reactions were shown to HCO-involving reactions were shown to play a noticeable role in sybgas oxidation only play a noticeable role in sybgas oxidation only in rich mixtures or at high CO content in in rich mixtures or at high CO content in syngas.syngas.

The research was performed under financial support of Siemens Ltd.Siemens Ltd. under

agreement #035-СT/2008

Thank you!

Flammability concentration limits for CO/H2/Air mixtures as functions of initial temperature (=0.5, p=1 bar) calculated using mechanism [1] - circles, reduced mechanism (var. #9) - triangles and literature data [Wierzba I., 2005] - squares.

Temperature, K

300 400 500 600 700 800

lim

0,0

0,1

0,2

0,3

0,4

6,0

8,0

10,0

12,0

14,0


O2+3H2= 2H2O+2H (I)*2H+MH2+M (II)*CO+H2O=CO2+H2 (III)*

* Wang W., Rogg, B., and Williams F.A. in Reduced Kinetic Mechanism for Application in Combustion Systems (Peters, N., Rogg, B., Eds.), Springer-Verlag, Berlin, p.48, 1993, pp.44-57

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

300 500 700 900 1100 1300 1500 1700 1900 2100 2300

T, K

Rea

ctio

n r

ate,

mo

le/(

cm3*

s) W II

W I

W III

Проверка механизма горения сингаза на основе брутто-реакций

Зависимость скорости реакций от температуры трех эффективных стадий для пламени СО/H2/Air (a=0.5, f=1.0, P=20 atm, T0=300K, D=0.209).

Аррениусовские параметры констант скоростей реакций для трех эффективных стадий в пламени СО/H2/Air (a=0.5, P=20 atm, T0=300K, D=0.209)

f

I II III

A Ea, cal/mol A Ea, cal/mol A Ea, cal/mol

Set#1 1 1.01030 56500 9.31013 -21280 2.01014 36560

Set#2 2 1.201026 41830 3.71013 -18900 1.941015 31900

Set#3 3 1.551025 40370 3.221012 -26600 1.871013 34600

Set#4 3.5 1.61025 42723 8.791010 -36500 4.331013 39000

50% CO+ 50% H2

0 1 2 3 4 5

Fla

me

sp

ee

d, cm

/s

0

20

40

60

80

100

120

140

20 atm, full mech20 atm, short mech (var 9)

set #4set #1set #2set #3

T0

=300 K, P=20 bar

Проверка механизма горения сингаза на основе брутто-реакций

Скорость распространения пламени СО/H2/Air (a=0.5, P=20 atm, T0=300K, D=0.209) от f, рассчитанная с использованием детального механизма реакций Sun H et al,

сокращенного механизма и трехстадийного механизма реакций на основе эфективных стадий с различными наборами кинетических параметров констант скоростей

Механизм реакций окисления H2/CO/O2

* размерность констант скоростей см3, моль, сек, кал, К , k = ATnexp(-Ea/RT).

No Реакция A* n Ea*

1 H + O2 = O + OH 6.731015 -0.50 16670

2 O + H2 = H + OH 3.821012 0 7948

3 O + H2 = H + OH 8.791014 0 19170

4 H2 + OH = H2O + H 2.17E + 08 1.52 3457.4

5 OH + OH = O + H2O 3.35E + 04 2.42 -1927

6 H2 + M = H + H + M 2.23E + 14 0 96070

7 H2 + H2 = H + H + H2 9.031014 0 96070

8 H2 + N2 = H + H + N2 4.581019 -1.4 104400

9 H2 + H2O = H + H + H2O 8.431019 -1.1 104400

10 O + O + M = O2 + M 6.161015 -0.5 0

11 O + O + AR = O2 + AR 1.891013 0 -1788

12 O + O + HE = O2 + HE 1.891013 0 -1788

13 O + H + M = OH + M 4.711018 -1.0 0

14 H + OH + M = H2O + M 2.211022 -2.0 0

15 H + O2(+M) = HO2(+M) k∞ 4.651012 0.4 0

16 H + O2(+Ar) = HO2(+Ar) k∞ 4.651012 0.4 0

17 H + O2(+He) = HO2(+He) k∞ 4.651012 0.4 0

18 H + O2(+H2O) = HO2(+H2O) k∞ 4.651012 0.4 0

19 H2 + O2 = HO2 + H 7.40105 2.43 53502

20 HO2 + H = H2O + O 1.441012 0 0

21 HO2 + H = OH + OH 6.001013 0 295

22 HO2 + O = O2 + OH 1.631013 0 -445.1

23 HO2 + OH = H2O + O2 l.00 1013 0 0

24 HO2 + OH = H2O + O2 5.801013 0 3974

No Реакция A* n Ea*

25 HO2 + HO2 = H2O2 + O2 4.201014 0 11982

26 HO2 + HO2 = H2O2 + O2 1.301011 0 -1629.3

27 H2O2(+M) = OH + OH(+M) k∞ 3.001014 0 48480

28 H2O2 + H = HO2 + H2 1.691012 0 3755.4

29 H2O2 + H = H2O + OH 1.021013 0 3576.6

30 H2O2 + O = OH + HO2 8.431011 0 3970

31 H2O2 + OH = HO2 + H2O 1.701018 0 29410

32 H2O2 + OH = HO2 + H2O 2.001012 0 427.2

33 CO + O(+M) = CO2(+M) 3.001014 0 3000

34 CO + O2 = CO2 + O 2.531012 0 47700

35 CO + HO2 = CO2 + OH 1.15105 2.278 17545

36 CO + OH = CO2 + H l.00 1013 0 15995.4

37 CO + OH = CO2 + H 9.001011 0 4570.1

38 CO + OH = CO2 + H 1.011011 0 59.6

39 HCO + M = H + CO + M 4.001013 0 15540

40 HCO + H = CO + H2 1.111014 0 0

41 HCO + O = CO + OH 3.001013 0 0

42 HCO + O = CO2 + H 3.001013 0 0

43 HCO + OH = CO + H2O 1.021014 0 0

44 HCO + HO2 = CO2 + OH + H 3.001013 0 0

45 HCO + HCO = H2 + CO + CO 3.011012 0 0

46 HCO + HCO = CH2O + CO 2.701013 0 0

47 HCO + O2 = CO + HO2 5.90E109 0.932 737

48 HCO + O2 = CO + HO2 1.55104 2.38 -1526Sun H., Yang S.I., Jomaas G., Law C.K., High-pressure laminar flame speeds and kinetic modeling of carbon monoxide/hydrogen combustion Proceedings of the Combustion Institute 31 (2007) 439–446

institute of chemical kinetics & combustion, novosibirsk 630090 russia

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