United States
Environmental Protection
Agency
National Risk Management
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-96/003 May 1996
EPA Project Summary
The Carnol Process for
CO2 Mitigation from Power
Plants and the Transportation
Sector
Meyer Steinberg
An alternative carbon dioxide (CO2)
mitigation process has been conceived
and its feasibility investigated. The
Carnol process is directed to reduce
CO2 emission primarily from coal burn-
ing power plants and producing metha-
nol as an alternative automotive fuel.
By-product carbon produced is either
stored or sold as a materials commod-
ity. A process simulation computer
model is used to perform materials and
energy balances. Preliminary econom-
ics of the process is evaluated. Two
advanced unit process developments
are identified for improving the utiliza-
tion of this process.
This Project Summary was devel-
oped by EPA's National Risk Manage-
ment Research Laboratory's Air Pollu-
tion Prevention and Control Division,
Research Triangle Park, NC, to an-
nounce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
A CO2 greenhouse gas mitigation pro-
cess is introduced and developed. The
Carnol process takes CO2 recovered from
the stack gases of a coal-fired power plant
and reacts it with hydrogen produced by
the thermal decomposition of natural gas
(methane) to produce methanol as a liq-
uid alternative transportation fuel. The re-
duction to near-zero CO2 emission results
from the removal of CO2 from the coal
burning plant and the emission of an
equivalent amount of CO2 when the metha-
nol is burned as fuel. The carbon pro-
duced from the methane decomposition
step is not used as fuel but is either stored
or sold as a materials commodity.
Process Chemistry
The process chemistry depends on two
reactions:
Methane Decomposition:
2H
CH4 = C
Methanol Synthesis:
CO
3H2 = CH3OH
H2O
The overall stoichiometry of the pro-
cess is:
3CH4 + 2CO2= 2CH3OH
2H2O + 3C.
The net CO2 generation for the produc-
tion and utilization of methanol is zero,
since 1 mol is recovered from the power
plant and 1 mol is produced when metha-
nol is used as fuel.
Process Design
Based on the thermodynamics and ki-
netics of methane decomposition, the con-
ditions for a Methane Decomposition Re-
actor (MDR) require operating tempera-
tures of 800°C and above at 1 atm* pres-
sure. A circulating heated alumina fluid-
(*) For readers more familiar with metric units: 1 atm =
101 kPa; 1 bbl = 159 L; 1 ton = 0.9 metric ton; and
1 lb/106 Btu = 0.43 kg/GJ.
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ized-bed reactor supplies the energy re-
quired to decompose the methane. The
methanol synthesis reactor (MSR) is a
conventional catalytic system operating at
260°C and pressures of 30 to 50 atm. An
equilibrium based process simulation
model is used to produce mass and en-
ergy balances based on the process flow
diagram shown in Figure 1. It was found
that CO2 emission reduction of 90% and
above can be achieved by the Carnol
process compared to that produced by
the conventional methane steam reform-
ing process. The thermal efficiency for
methanol production is 41% and the co-
product carbon conversion efficiency
based on methane is 92%.
Preliminary Economics
A preliminary economic evaluation is
made feeding CO2 recovered from a 600
MW(e) coal-fired power plant, together
with natural gas to produce 61,100 bbl/
day of methanol and 5800 tons/day of
carbon. Depending on the cost of natural
gas, the cost of CO2 recovery, the market
price of methanol, and the possible mar-
ket value of carbon, the cost of CO2 emis-
sion reduction can vary from an income
of $103/ton to an expenditure of $55/ton
CO2 recovered from the power plant. The
latter is less than the highest cost esti-
mated for recovery of CO2 from a coal-
fired power plant located near a coast
and disposal of the CO2 in the ocean.
The application of CO2 mitigation tech-
nologies, such as the Carnol process,
depends to some extent on how seri-
ously the country and the world take the
global greenhouse gas warming problem
since such an approach would involve
massive capital investments and funda-
mental changes in the country's energy
use patterns.
Steam
V
'2.8 kmol* ^lllbus-lul |
y : Alumina or Hex.
MDR
*" 1 atm, 800°C
640°C /A
260°C|
0.2 kmol
1 2.86 kmol
188°C <
i '
1 1
59.5 kmol " 197°C
Y
MSR
50 atm, 260°C
200°C A
^ Carbon to Storage
**68.8 kg
CH4 Feedstock
100kg, 20"C
CC>2 Feedstock from
156.6kg, 20°C
y
Carbon Efficiency 50.3%
Thermal Efficiency 41.1%
CO2 Emission 22.7 lb/106Btu
Basis 100 kg CH4 Feed
Gas Stream ABC
Rate-
Temp
Comp
CO
CO2
©Cri4
H,n
"^^ 59.5 kmol A H2
138°C! ' ¥ Me°H
: CIRC ]<--'
Y L-r- l
2.6 kmol
-^- CON
^ '-*- 50 atm, 50°C
^J
kmol 12.0 70.4 64.0
-°C 800 260 50
mo I %
3.35 3.68
12.86 14.15
4.25 17.34 19.08
4.76 0.14
95.75 56.67 62.34
5.02 0.60
I I
Y Y
MeOH H2O
101kg 58.7kg
Figure 1. CO mitigation technology Carnol-lll + process.
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Process Improvements
Two important process improvements
for lowering the cost of the Carnol pro-
cess are identified for further research
and development: (1) the use of a mol-
ten metal bath reactor for thermally de-
composing methane and (2) the use of a
liquid phase slurry catalyst for synthesiz-
ing methanol by the reaction of hydrogen
with CO2 in a monoethanolamine (MEA)
solvent. The conceptual process dia-
gram including these developments is
shown in Figure 2.
Exhaust Gas
(90% CO2'
Recovery)
PP Flue Gas
CW
Coal
Fuel
Coal Fired
Power Plant
MeOH
H2O, H2, cw\Cond. Recycle
120°C C02
CO2, H2 1 ATM .
Flue Gas Pump
Preheater
Flue Gas
30 ATM
Nat. Gas
Feedstock
MEA Scrubber Liquid Phase MeOH-H2O PSA-H2/CH4Sep. Molten-Metal Tin
with MeOH Catalyst Slurry Methanol Fractionator Compressor Methane Decomp.
1ATM-40°C Converter 30 ATM From 1-10 ATM Reactor
30 ATM to 30 ATM 1-10 ATM
120°C 800°C-900°C
Feedstock
| r*- Product
Process Chemistry: 3/2 CH4 = 3/2 C + 3H2
3 H2 + CO2 = CH3OH + H2O
Nat. Gas, Decomp.
MeOH Synthesis
Flue Product
Gas
Figure 2. Carnol-VI process for CO2 mitigation technology—combining CO2 recovery from power plants with liquid metal
methane decomposition and liquid-phase methanol synthesis.
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Meyer Steinberg is with Brookhaven National Laboratory, Upton, NY 11973.
Robert H. Borgwardt is the EPA Project Officer (see below).
The complete report, entitled "The Carnol Process for CO2 Mitigation from Power
Plants and the Transportation Sector," (Order No. PB96-145 065; Cost: $19.50,
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air Pollution Prevention and Control Division
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
National Risk Management Research Laboratory (G-72)
Cincinnati, OH 45268
Official Business
Penalty for Private Use $300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-96/003
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