production of drop-in transportation fuels via combined biomass gasification- fischer...

Production of Drop-in Transportation Fuels via Combined Biomass Gasification-

Fischer-Tropsch Synthesis

Amit Gujar, Jong Baik, Nathaniel Garceau, Nazim Muradov and Ali T-Raissi

Florida Solar Energy CenterUniversity of Central Florida

29 September 2010

FESC 2010 Summit, Orlando

Objectives & Approach

• Demonstrate, at pilot-scale, production of transporatation fuel from biomass feedstock

• Build a PDU-scale oxygen-blown gasifier capable of steady-state operation.

• Fabricate a multi-tube Fischer-Tropsch (FT) reactor capable of yielding 1L/8hr liquid hydrocarbon fuel

• Integrate, operate and optimize integrated combined biomass gasification and FT synthesis reactor.

Introduction

Pine wood

pellets

Pine charcoal

pellets

Citrus pulp

pelletsDuckweedRiver

algae

Ash

Wood pellets, algae, citrus waste, etc.

water

fuel refining

F-T reactor

conditioner

scrubber

gasifier

O2

raw bio-fuel

diesel

gasoline

Introduction

• Ideal biomass gasification reaction-

CH1.4O0.6 + 0.4 O2 0.7 CO + 0.3 CO2 + 0.6 H2 + 0.1 H2O

• Ideal Fischer-Tropsch (FT) synthesis reaction-

CO + 2 H2 -CH2- + H2O

Other reactions

CO+H2O------> CO2 + H2

C+CO2-----> 2CO

CO+3H2----->CH4 +H2O

Gasification Reactor

/

SUS304

200psig cylinder

Biomass

(charcoal, wood

pellet etc.)

Glass fiber

insulation

Insulating riser

sleeve

Hearth zone

Grate/flow

diffuser

Ash collector

Cyclone

• 3.25” Hearth dia.

• 9” Internal dia. of the riser sleeve.

• 41 lt of biomass volume capacity.

• 200psig pressure rating.

Results – Biomass Gasification (1)

Optimum [H2O]0/[O2]0 molar feed ratio appears to be in the range of 4-5.

Feed [H2O]

0/[O

2]0 ratio, -

0 1 2 3 4 5

H2/C

O &

CO

/CO

2 r

atios a

nd C

gasifie

d/C

com

buste

d,

-

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

H2/CO in syngas

Cgasified/Ccombusted

Linear fit to data

CO/CO2 in syngas

Small gasifier

Results – Biomass Gasification (2)

High O2 mass flow rate leads to higher concentration of H2 & CO in the syngas as well as higher gasification rates.

Useful data for sizing the gasifier

Specie

s c

oncentr

ation,

%

0

20

40

60

80

100

Input oxygen mass flow rate, g/min

0 1 2 3 4 5 6

Gasific

ation r

ate

& s

yngas p

roduction r

ate

, g/m

in

0

2

4

6

8

10

12

Gasification rate

Syngas mass flow rate

Linear fit to data

[H2O]/[O2]= 2.25

H2

CO

CO2

CH4

FT Reactor Design

• Twelve (12) 1” OD SS316 tubes

• 6 cartridge heaters

Cartridge heaters

Syngas from

gasifier

FT reactor

(1"OD SS316)

Copper spacers

Steam inlet

Steam outlet

Liquid fuel

to condenser

FT reactor / Heater

arrangement

Results – FT Synthesis (1)

• Co catalyst tested at 250°C, 200 psig, 3,106 mL/gcat.hr

Elapsed time, hrs

0 10 20 30 40 50

Specie

s c

onvers

ion/s

ele

ctivity,

%

0

20

40

60

80

100

CO conversion

CH4 selectivity

CO2 selectivity

Fit to data

33% CO & balance H2 over 20% Co-SiO2

Gasoline range (C5-C10) 48.98 wt%

Kerosene/jet fuel range (C11-C12)

15.08

Diesel range (C13-C16) 21.10

Lube oil and wax range (C17-C26)

14.84

Space-time yield = 0.24 g/gcat.hr

H2 conversion

Results – FT Synthesis (2)Scale up studies Temperature effect (H2:CO=2:1 & 450 mL/min

flow)

Temperature, oC

180 190 200 210 220

Specie

s c

onvers

ion/s

ele

ctivity,

%

0

20

40

60

80

100

H2 conversion

CO conversion

CH4 selectivity

CO2 selectivity

C2-C4 selectivity

Fit to data

Space-t

ime y

ield

, g/g

cat/

hr

0.00

0.02

0.04

0.06

0.08

0.10

0.12

STY

Nonlinear fit to STY data

• Increase in temperature leads to increase in conversions and space time yields of liquid product

CH4

CO2

Results – FT Synthesis (3)Effect of space velocity at 220°C

Syngas flow rate, mL/min

400 500 600 700 800 900

Specie

s c

onvers

ion/s

ele

ctivity,

%

0

20

40

60

80

100

H2 conversion

CO conversion

CH4 selectivity

CO2 selectivity

C2-C4 selectivity

Space-t

ime y

ield

, S

TY

, g/g

cat.

/hr

0.10

0.11

0.12

0.13

0.14

0.15

STY

• Increasing the syngas flow rate eventually leads to increase in

methane light gas selectivity due to exothermicity of the reaction thus

leading to decrease in liquid yields.

CO2

CH4


Increasing pressure helps but reaction does proceed at low pressures, as well (unlike Fe catalyst)

Total pressure, psig

40 60 80 100 120 140 160

Convers

ion/s

ele

ctivity,

%

0

20

40

60

80

100

H2 conversion

CO conversion

CH4 selectivity

CO2 selectivity

C2-C4 selectivity

40 60 80 100 120 140 160

Space-t

ime y

ield

, S

TY

, g/g

cat.

/hr

0.10

0.12

0.14

0.16

0.18

0.20

STY

CH4

CO2


Decrease in the CH4 selectivity as CO2

concentration in the feed increases

CO2 concentration in syngas, %

0 10 20 30 40 50

Convers

ion/s

ele

ctivity,

%

0

20

40

60

80

100

H2 conversion

CO conversion

CH4 selectivity

C2-C4 selectivity

Space-t

ime y

ield

, S

TY

, g/g

cat.

/hr

0.06

0.08

0.10

0.12

0.14

STY

Results – FT Synthesis (6)Effect of space velocity (230°C & H2:CO= 1:1)

Syngas flow rate, LPM

0.40 0.60 0.80 1.00 1.20

Convers

ion/s

ele

ctivity,

%

0

20

40

60

80

100

H2 conversion

CO conversion

CH4 selectivity

CO2 selectivity

C2-C4 selectivity

Space-t

ime y

ield

, S

TY

, g/g

cat.

/hr

0.05

0.10

0.15

0.20

0.25

STY

• Upto 50% more liquid yield per tube when H2:CO=1:1

H2

CO

Summary of FT Tests

• Using Syngas of H2:CO=1:1 is preferable if the aim is to get maximum liquids out in a single pass mode.

• The use of syngas of H2:CO=2:1 is preferable if the aim is to have maximum utilization of the inlet gas.

• Presence of CO2 is helpfully in controlling the exothermicity of the reaction thus reducing the methane and light gas selectivity.

Acknowledgement

production of drop-in transportation fuels via combined biomass gasification- fischer...

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