GASIFICATION OF ISOOCTANE INTO HYDROGEN FOR FUEL CELL
APPLICATION USING SUPERCRITICAL WATER
1Supercritical
Ratna Frida Susanti1,2, Bambang Veriansyah1, Jaehoon Kim1, Jae-Duck Kim1,2* and Youn-Woo Lee3
Fluid Research Laboratory, Energy and Environment Research Division, Korea Institute of Science and Technology (KIST)
2Department of Green Process and System Engineering, University of Science and Technology (UST)
3School of Chemical and Biological Engineering, Seoul National University (SNU)
*Correspondence : [email protected]
Supercritical water
HYDROGEN as renewable energy
Compact reformer
Supercritical
No
catalyst
0.315 g/ml
Pressure
[bar]
221 73.8
S
U
P
E
R
C
R
I
T
I
C
A
L
Critical
Point
0.05 g/ml
Solid
0.315 g/ml
374oC, 221bar
Liquid
0.0006 g/ml
300oC,
0.006
Water
100oC, 1bar
0.71 g/ml
85bar
Short
residence
time
Short
residence
time
Compactness, portable,
continuous operation
1.0 g/ml
Gas
0
Wall
effect
Low CO
content
374
Advantages of SCW:
environmentally friendly fluid
as reaction medium it has fast heat and mass
transfer with adjustable density
As homogenizing reaction medium, it dissolves
hydrocarbon so minimize tar/char
Objective
to examine the performance of up-down and
down-up reactor configuration for gasification
of isooctane in supercritical water.
Experimental section
KIST Gasification Apparatus Scheme
Material:
isooctane (C8H18, 99% min), distilled and
deionized water (DDI water), hydrogen peroxide (35% w/v)
Analytical method : Gas product was analyzed
using two kinds of gas chromatography:
1. GC HP5890 Series II; Thermal Conductivity Detector
(TCD); HP-PLOT Q Column; helium as carrier gas
2. Young Lin ACME 6100 GC; Pulsed Discharge Helium
Ionization Detector (PDHID); Rt-MSievetm 5A Plot Column
TEMPERATURE EFFECT
Experiments variable:
Pressure
= 25 MPa
UP-DOWN type :
C8H18 concentration = 21wt%
Residence time
= 16 s
DOWN-UP type :
C8H18 concentration = 11.2 wt%
residence time
= 6.9 s
RESIDENCE TIME EFFECT
Experiments variable:
DOWN-UP type
Reactor inclination : 750 from vertical position
f
L
U
I
D
High P,
dense
fluid
Pressure
UP-DOWN type
Reactor position :vertical
COMPARISON
= 25 MPa
UP-DOWN type :
C8H18 concentration = 19.5wt%
Temperature
= 871 K
Tubular reactor
Material : Hastelloy C-276 (Ni, Mo, Cr, Fe)
Dimension: ID=10 mm; OD = 31 mm; effective length=380
mm
DOWN-UP type :
C8H18 concentration = 15.2 wt%
Temperature
= 905 K
OXIDANT EFFECT
In the similar condition :
Configuration
Gas
Yield,
L/g
H2
CO
CO2
CH4
C2-C4
Up-down
Experiment
condition
T, K τ, s
Feed
Conc.
937
16
21
Product gas (%mol)
Hydrogen yield, *CE,
mol/mol
%
isooctane
0.51
34.1
2.0
19.9
37.4
6.6
0.63
16.7
Down-up
913
1.87
46.6
1.7
17.2
26.5
4.2
2.61
45.8
Experiments variable:
Pressure
= 25 MPa
UP-DOWN type :
C8H18 concentration = 22 wt%
Residence time
= 15 s
Temperature
= 936 K
DOWN-UP type
18
20
C8H18Concentration = 10 wt%
Residence time
=8s
Temperature
= 910 K
* CE = carbon gasification efficiency, total moles of carbon in gas product per total mol carbon in feed
CONCLUSION
The supercritical water gasification has been proved to be an effective technique to produce hydrogen from isooctane even without addition of any
Higher
CATALYST
HYDROGEN YIELD was achieved by applying higher temperature, longer residence time and small amount of oxidant for both of the the gasifier types
The
DRAWBACKS owned by the UP-DOWN configuration made the hydrogen yield obtained was much lower than down-up type.
The
DOWN-UP gasifier offers a promising chance to develop compact onboard reformer for processing heavy oil