production of drop-in transportation fuels via combined biomass gasification- fischer...
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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
Results – FT Synthesis (4)
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
Results – FT Synthesis (5)
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
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