allothermal gasification and integrated syngas cleaning by ... · 1. deutsches...

www.evt.cbi.fau.de Department Chemie- und Bioingenieurwesen (CBI) Lehrstuhl für Energieverfahrenstechnik Prof. Dr.-Ing. Jürgen Karl

1. Deutsches Doktorandenkolloquium Bioenergie, DBFZ, September 20-21, 2018, Leipzig

Coal Steam Raw Syngas

Flue gas

Heat- Pipes

Reactor

Combustion- chamber

Dipl.-Ing. Peter Treiber

Allothermal gasification and integrated syngas cleaning by hot K2CO3 scrubbing for

decentralized SNG production



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 2

Conclusion

1. Motivation: CO2freeSNG2.0 – Coal-to-SNG with integrated syngas cleaning

2. Coal/Biomass-to-SNG Allothermal gasification and carbonate syngas scrubbing

3. EVT lab-scale test stands 5 kW gasifier and Benfield scrubber

Agenda

4. Results Gasification Gasification Syngas cleaning

5. Conclusion



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 3

Conclusion

Motivation - CO2freeSNG2.0

Project goals • Integrated process optimization and economic feasibility study of

medium-scale SNG plants based on process simulations • Extensive lab- and bench-scale testing of lignite gasification with integrated

CO2 removal and catalytic methanation (5 kW Process chain) • Demonstration of the complete process chain with integrated technologies:

• 100 kW EVT-Heatpipe Reformer • Scrubbing unit based on Benfield process • Methanation with conventional and new developed catalyst systems

The research project CO2freeSNG2.0 (RFCR-CT-2013-00008) is funded by the Research Fund for Coal and Steel of the European Commission.

Motivation



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 4

Conclusion

Coal Steam Raw Syngas

Flue gas

Heat- Pipes

Reactor

Combustion- chamber

EVT – Heatpipe Reformer • Allothermal steam gasification

• Dual fluidized bed reactor:

• Atmospheric combustion

• Pressurized gasification

• Heat transfer by Heatpipes

Gasification

Vapor flow Liquid flow Mesh structure

Condensation zone

Adiabatic zone

Evaporation zone

Heat source

Heat sink



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 5

Conclusion

EVT – Heatpipe Reformer

Gasification

Gasificationfuel

Combustionfuel

Steam

Secondaryair

Combustor

Primaryair

Heatpipe reformer

Heatpipes

Gasificationreactor

Raw syngas

Flue gas

Clean syngas

Ash,char

WaterRME

Water

Ash

RME, tar, condensate



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 6

Conclusion

Integrated Syngas Cleaning Motivation • Utilization of light hydrocarbons and tars (BTX) for methanation • Removal of heavy tars to prevent coke formation • Bulk sulfur removal necessary for catalyst life time • Adjustment of the C/H/O-ratio by partial CO2 removal

Approach • Scrubbing at elevated temperature based on Benfield process

• Condensation of heavier tars • Bulk removal of sulfur components • Removal of surplus CO2

Application • Bulk syngas cleaning for decentralized SNG production in small and mid scale plants

Syngas cleaning



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 7

Conclusion

Carbonate Scrubbing – Benfield Process

Basic data Carbonate scrubbing • Increased solvent temperature • No additional solvent cooling before absorber

inlet • Low reboiler duty (steam) necessary • Stabile and non-toxic solvent

Pump

Lean CarbonateSolution

Valve

CO2-free Gas

RawGas

120°C

Level Control

Reflux

CO2

Rich CarbonateSolution

115°C

Abso

rber

(10.

..20

bar)

Rege

nera

tor (

0,5 .

..1 b

ar)

Cond

ense

r

Steam

𝐾2𝐶𝐶3 + 𝐶𝐶2 + 𝐻2𝐶 ⇌ 2 𝐾𝐻𝐶𝐶3 𝐾2𝐶𝐶3 + 𝐻2𝑆 ⇌ 𝐾𝐻𝑆 + 𝐾𝐻𝐶𝐶3

Homer E. Benson Joseph H. Field

….



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 8

Conclusion

SNG-Production – process chain 5 kW

Air H2O

A

Gas control rig

Gasifier

Carbonate Scrubber

Hot gas cleaning

Raw Syngas

Humidifier

350 °C1-4 bar

–

– 0 – 350 °C

Fuel N2

Test stands

H2O

Absorber Desorber

Carbonate Scrubber

Hot gas cleaning

p

KHCO3

Clean SyngasRaw Syngas

350 °C1-4 bar

250 – 400 °C

–

100 – 120 °C0 – 350 °C

CO2

N2

Desorber

polytropicMethanation

3

Clean Syngas

Gasanalysis

SNG

+20 °C -20 °C

250 – 400 °C

230 – 250 °C

– 120 °C

CO2Condenser

µ-GC

Tar protocol

SPE

GA



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 9

Conclusion

SNG-Production – 5 kW Gasifier

Steam

Fuel

Raw Syngas

Technical Data

• Stationary fluidized bed

• Electrical reactor heating

• Allothermal steam gasification

• Pressure: up to 6 bara

• Gasification temperature: 800 – 900 °C

• Hot gas filter

• Inspection glas

Reactor heating

Fuel inlet Pressure lock

Steam generator

SPC

Lignite Biomass



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 10

Conclusion

SNG-Production – 5 kW Scrubber

Technical Data • P = 5 bara , TSolvent = 100°C, 30 wt.-% K2CO3

• Packings: Raschig Rings 6 mm VA

Test stands



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 11

Conclusion

Results – Gasification – Temperature

Biomass gasification p = 1.3 bara σ = 12

Results

0%

10%

20%

30%

40%

50%

60%

800 810 820 830 840

Syng

as c

ompo

sitio

n (d

ry, N

2-fr

ee)

Fluidized bed temperature [°C]

H2

CO2

CO

CH4

b)

a)

b)

c)

U/U0 = 1.5

U/U0= 3

U/U0= 6



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 12

Conclusion

1

10

100

1,000

10,000

Syng

as ta

r loa

ding

(dry

, N2-

free

) [m

g/N

m³]

814°C WS

820°C WS

829°C WS

835°C WS

Results – Gasification – Temperature

Biomass gasification p = 1.3 bara σ = 12

Results



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 13

Conclusion

0%

10%

20%

30%

40%

50%

60%

0 3 6 9 12 15

Syng

as c

ompo

sitio

n (d

ry, N

2)-fr

ee)

Stoichiometric steam ratio σ [-]

H2

CO2

CO

CH4

b)

Results – Gasification – Steam excess ratio

Results

Biomass gasification p = 1.3 bara 𝑇𝐹𝐹 = 830 °C



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 14

Conclusion

1

10

100

1,000

10,000Sy

ngas

tar l

oadi

ng (d

ry, N

2-fr

ee) [

mg/

Nm

³]Sigma 4Sigma 6Sigma 8Sigma 10Sigma 12

Results – Gasification – Steam excess ratio

Results

Biomass gasification p = 1.3 bara 𝑇𝐹𝐹 = 830 °C



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 15

Conclusion

0

4

8

12

16

20

0

400

800

1,200

1,600

2,000

820 825 830 835 840

Thiop

hene

[ppm

]

H 2S

[ppm]

Fluidized bed temperature[°C]

H2S

Thiophene

Results – Gasification p = 5,2 bara, σ = 3,26

Results

Light Hydrocarbons and Sulfur

• Overall tar reduction with rising gasification temperature

• At lower gasification temperatures shift towards aromates

• Ethene and Ethine decrease with rising gasification temperature

• Sulfur compounds barely affected by fluidized bed temperature

• H2S

• Thiophene

0.00

0.05

0.10

0.15

0.20

0.25

820 825 830 835 840

C xH y

conc

entra

tion [

Vol.-%

]

Fluidized bed temperature [°C]

Ethene

Ethine



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 16

Conclusion

0

10

20

30

40

50

60

70

80

90

100

CO2 H2S

Rem

oval

effi

cien

cy [%

]

Results – Scrubber

Results

L/G = 14

L/G = 10

Simulation vs. bench scale tests • Simulation of 90% CO2 removal efficiency @ L/G 19 proofed only up to 65% in bench scale

tests due to heat losses and edge effects → higher efficiency reached in pre-pilot scale

Removal efficiency

𝜂𝐶𝐶2 =(𝑥𝐶𝐶2,𝑟𝑟𝑟 − 𝑥𝐶𝐶2,𝑐𝑐𝑐𝑟𝑐)

(𝑥𝐶𝐶2,𝑟𝑟𝑟 × (1 − 𝑥𝐶𝐶2,𝑐𝑐𝑐𝑟𝑐)

𝜂𝐻2𝐻 =(𝑥𝐻2𝐻,𝑟𝑟𝑟 − 𝑥𝐻2𝐻,𝑐𝑐𝑐𝑟𝑐)

(𝑥𝐻2𝐻,𝑟𝑟𝑟 × (1 − 𝑥𝐻2𝐻,𝑐𝑐𝑐𝑟𝑐)

Liquid-to-Gas ratio

𝐿𝐺

= �̇�𝐻𝑆𝑐𝑆𝑐𝑐𝑆�̇�𝐻𝑆𝑐𝑆𝑟𝑆



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 17

Conclusion

Results – Scrubber – L/G-ratio

Results

0%

10%

20%

30%

40%

50%

60%

70%

0%

10%

20%

30%

40%

50%

60%

70%

RawSyngas

10 12 14 16 18 20

CO2

Rem

oval

effi

cien

cy

Syng

as c

ompo

sitio

n (d

ry, N

2-fr

ee)

Liquid-to-gas ratio L/G [-]

H2

CO2

CH4

CO

CO2 Removal efficiency



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 18

Conclusion

1

10

100

1,000

10,000

Syng

as ta

r loa

ding

[mg/

Nm

³]GasifierL/G 10L/G 12L/G 14L/G 16L/G 18L/G 20

Results – Scrubber – L/G-ratio

Results



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 19

Conclusion

Results – Scrubber – Solvent

Results

0%

10%

20%

30%

40%

50%

60%

70%

80%

8 10 12 14 16 18 20 22

CO2

Rem

oval

effi

cien

cy


10 wt.-% K2CO3

20 wt.-% K2CO3

30 wt.-% K2CO3 ** Biomass

gasification K2CO3

K2CO3

K2CO3

a)

0%

10%

20%

30%

40%

50%

60%

70%

80%

8 10 12 14 16 18 20 22CO

2Re

mov

al e

ffici

ency


Without PZ

2.5 wt.-% PZ

5.0 wt.-% PZ

b)



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 20

Conclusion

Results – Scrubber

Results

0

500

1000

1500

2000

2500

3000

3500

Gasifier Scrubber

Tar c

once

ntra

tion

[mg/

Nm

³] (S

PE-M

etho

d)

BTX

Aromates

Tar removal

• Reduced syngas vol.-flow due to CO2 removal

• Higher BTX concentration after scrubber but • Less aromates after scrubber

• Close to total removal of heavier hydrocarbons

(TB > 350 °C)



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 21

Conclusion

100 kW Process chain

Desorber Absorber

Condenser

Flash drum

Reboiler

Tar separator

HPR filter

EVT-Heatpipe Reformer Pre-pilot carbonate scrubber



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 22

Conclusion

100 kW Process chain – Demonstration

0

10

20

30

40

50

60

70

0 20 40 60 80 100

120

140

160

180

200

220

240

260

Syng

asco

mpo

sitio

n(d

ry, N

2-fr

ee) [

vol.-

%]

Time [min]

H2

CO

CO2

CH4

Fuelstop

H2

CH4

CO2

CO

Heatpipe ReformerScrubbernot recorded (methanation)

123

1 1 12 23 3

H2

COCO2

CH4

𝜂𝐶𝐶2= 60 %

Lignite gasification pgasifier = 4,0 bara pabsorber = 3,8 bara TSyngas, clean = 120 °C



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 23

Conclusion

100 kW Process chain – Demonstration

pre-pilot scrubber at FAU

0

10

20

30

40

50

60

70

H2 CO CO2 CH4

Conc

entr

atio

n (d

ry, N

2-fr

ee) [

vol.-

%] Lignite 1.3 bar

Lignite 4.0 bar

Biomass 1.5 bar

Biomass 4.0 bar



Motivation

Gasification

Syngas Cleaning

Test stands

Results

Folie 24

Conclusion

Conclusion CO2freeSNG2.0 • Decentralized SNG-Production from coal or biomass with

integrated syngas cleaning and CO2-removal • Bench scale testing: Gasifier, Scrubber, Methanation (5 kW) • Demonstration of the pre-pilot scale process chain

• Heatpipe Reformer(100 kW) + Scrubber

Allothermal steam gasification • Steam surplus variation to support methanation • Tar load and composition in focus of investigation Integrated Syngas Cleaning • Syngas scrubbing at elevated temperatures based on the

Benfield process as bulk cleaning process • Heavy tar components (Condensation) • Surplus CO2 und sulfur compounds removal

• Utilization of light hydrocarbons in Methanation

Conclusion

allothermal gasification and integrated syngas cleaning by ... · 1. deutsches...

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