Theadvantagesofhydrogasificationwillbe

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ygen
(O2),
generally
at
a
high
 temperature
and
under
high
pressure.

 
 Climate
Change
Policy
Partnership
 4
 Synthetic
Natural
Gas
(SNG):
Technology,
Environmental
Implications,
and
Economics
 N2 Particulate,
 tar
removal
 
Coal 
 
 
 CO2 N2 Air 
 Air ASU 
 ASU O2 
 O2 Gasifier 
 Gasifier Steam Ash
 
Syngas Gas
 cleaning
 
 Compression
and
 sequestration
 (optional)
 CO2 Water‐ gas
 shift
 H2,
CO,
 CO2
 
 H2,
CO,
 CO2
 Gas
 cleaning
 
 
 Water‐ Gas
 Gas
 Steam Gas
 cleaning
 cleaning
 Shift
 Figure
1.
Steam‐oxygen
gasification
process
diagram
 
 Compression
and
 Sequestration
 CO,
 (Optional)
 Methanation SNG
 H2 
 
 
 SNG
 
 
 
 As
an
example,
the
GE/Texaco
gasifier
temperature
operates
at
42
bars
and
2,500°
F.
The
different
types
 of
gasifiers
are:
entrained
flow,
fluidized
bed,
moving
bed,
and
transport
reactor
(Stiegel
2007).
 Commercial
gasifier
vendors
include
ConocoPhillips,
GE
Energy
(Chevron‐Texaco),
Shell‐SCGP,
Siemens
 (GSP/Noell),
KBR
Transport,
and
Lurgi.
 
 Water‐Gas
Shift
Reactor
 The
concentration
of
H2
is
increased
by
the
water‐gas
shift
reaction.
In
the
water‐gas
shift
reaction,
CO
 and
H2O
are
converted
to
CO2
and
H2
in
a
fixed‐bed
catalytic
converter.
The
reaction
is
exothermic
and
 can
be
completed
either
before
or
after
the
acid
gas
removal.
The
catalyst
composition
varies
for
both
 types
of
shift
reactions
(NETL
2007).

 
 Syngas
Cleanup
 The
syngas
cleanup
is
done
in
two
steps.
First,
the
syngas
from
the
gasifier
is
quenched
and
cooled,
and
 the
dust
and
tar
carried
by
the
gas
are
removed.
After
passing
through
the
water‐gas
shift
reactor,
the
 syngas
is
cleaned
a
second
time
to
remove
the
acid
gases
H2S
and
CO2.
The
acid
gas
cleanup
system
can
 use
either
the
Selexol
or
Rectisol
process.
Both
processes
are
based
on
physical
absorption,
which
 makes
them
more
economical
than
the
amine
process
used
for
CO2
separation
in
power
plants,
which
is
 based
on
chemical
absorption.
The
processes
can
be
used
in
a
selective
manner
to
produce
separate
 streams
of
H2S
and
CO2.
The
H2S
can
be
further
utilized
in
a
Claus
plant
to
generate
sulfur.
 
 In
the
Selexol
process,
a
mixture
of
dimethyl
ethers
of
polyethylene
glycol
is
used
as
an
absorbent.
The
 Selexol
solvent
absorbs
the
acid
gases
from
the
syngas
at
relatively
high
pressure,
usually
...
View Full Document

This essay was uploaded on 03/18/2014 for the course ENG 316K taught by Professor Kruppa during the Spring '08 term at University of Texas at Austin.

Ask a homework question - tutors are online