United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-91/007 Feb. 1992
i§rEPA Project Summary
A Feasibility Study for the
Coprocessing of Fossil Fuels
With Biomass by the Hydrocarb
Process
Meyer Steinberg, Edward W. Grohse, and Yuanki Tung
A new process concept for the pro-
duction of carbon and methanol from
fossil fuels is described and assessed.
The Hydrocarb Process consists of the
hydrogasification of carbonaceous ma-
terial to produce methane, which is sub-
sequently thermally decomposed to
carbon black and hydrogen, part of
which is recycled to the hydrogasifier.
With an oxygen-containing feedstock,
the carbon monoxide (CO) is converted
with hydrogen to methanol in an inter-
mediate step. Background process
chemistry data are available for each
step of the process. A process simula-
tion model has been developed to per-
form complete mass and energy bal-
ances based on approaching thermo-
dynamic equilibrium compositions. Pre-
liminary process design and analysis
indicates economic potential. By
coprocessing fossil fuels with biomass
to produce hydrogen-rich fuels, it is
shown that the carbon dioxide (CO2)
emissions can be substantially reduced
compared to direct combustion of fos-
sil fuel. Additional experimental data
on the kinetics of hydrogasification of
wood and methane decomposition are
required before a process demonstra-
tion unit can be constructed.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Tri-
angle Park, NC, to announce key find-
ings of the research project tht is fully
documented in a separate report of the
same title (sea Project Report ordering
information at back).
Introduction
A feasibility study was undertaken at
Brookhaven National Laboratory (BNL) to
determine the potential of coprocessing
biomass with fossil fuel to produce a clean
carbon fuel and coproduct methanol by
the Hydrocarb Process. The process may
be useful for mitigating the global warm-
ing problem by reducing CO? emissions.
The Hydrocarb Process consists of three
basic process steps: (1) the exothermic
hydrogasification of a carbonaceous feed-
stock to a methane-rich process gas
stream, (2) the endothermic thermal de-
composition of methane to carbon and
hydrogen, part of which is recycled to
step (1), and (3) the conversion of CO
and hydrogen to methanol. Any carbon-
aceous material can be used as feed-
stock. The coproducts are clean particu-
late carbon black, liquid methanol, and
gaseous hydrogen or methane. There are
distinctive benefits of clean carbon and
methanol as environmentally acceptable
utility and transportation fuels. Carbon can
be used separately or combined in slurry
form with methanol which significantly im-
proves the volumetric energy density of
methanol while methanol improves the ig-
nition characteristics of the carbon in the
slurry.
Basic Hydrocarb Process
The basic Hydrocarb Process can be
operated with any carbonaceous feedstock
or with combinations of feedstocks. Fur-
thermore other coproducts can be formed.
Feedstock which contains some oxygen
material, which includes coal and wood,
Printed on Recycled Paper
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when hydropyrolyzed forms some amounts
of CO. The CO then can be catalytically
combined with hydrogen to form metha-
nol. Table 1, a generalized schematic of
the Hydrocarb Process, indicates possible
alternate feedstocks and coproducts. Fig-
ure 1 shows one version of several
flowsheets in which methanol is produced
between the methane pyrolyzer and the
hydrogasHier without an alumina heat
transport system between the reactors. A
further step in the Hyrdrocarb Process
converts the methanol to gasoline by the
MTG (methanol to gasoline) process. Al-
ternate reactors, including moving and f lu-
idized beds can be used.
Analysis of Proposed Blomass/
Fossil Fuel Hydrocarb
Coprocess
The Hydrocarb processing of fossil fuel
atone, sequestering the carbon and using
only the hydrogen generated, can extract
56% of the energy from natural gas, 25 to
37% from crude oil, and 19% from coal.
With this energy penalty, a hydrogen
economy can be based on utilizing fossil
fuel with no generation or emission of
ca.
Coprocessing fossil fuel with biomass,
employing the Hydrocarb system to pro-
duce carbon and methanol while seques-
tering the carbon and only using methanol
Table 1. Clean Coal Technology: Production of a Clean Carbon Fuel and Coproducts
All coal ranks
C (impure)
Optional additions
Carbon black
main product
H2 -
exothermic
CH4
methane
C (pure)
endothermic
H20
C02
CH4
limestone
water
carbon dioxide
methane
Alternate feedstocks
peat
Co-products
-»• H2 - hydrogen
*• CH4 - methane, SNG
.*• CH3OH - methanol
Waste streams
- water
wood
rubber
paper
MSW
— * C02
». CaSO4 or S
> N2
>• ash
- carbon
dioxide
- sulfur
- nitrogen
Notes: 1) Three methods of heat transfer - gas, solid, or steam
2) Three reactor types - fiuidized bed, moving bed, entrained bed
Alternate
feedstocks
Feedstock
Preparation
cod
oN
o.as
wood
MSW
char
additives
limestone
Water
CO,
CH4
500° C
AIr-b!own
combustion
Hot flue gas
for carbon
reheater
Cond. water
-800° C
HGR
Hydrogasifier
CCFB or
COMB
-50 ATM
MPR
Methane
Decomposer
CCFB or CCMB
50 ATM
-800° C
_£
Inert ash and CaSO4
for Disposal
Methanol
coproduct
Purge and
fuel gas
Recycle and
lift C pellets
Gas
Lift
Clean pe let carbon Pur9» 3^
fuel product
Flgun 1. Csfbex version of the Hydrocarb Process: Clean carbon and coproduct fuels from carbonaceous feedstocks
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as fuel, not only can reduce CO2 emis-
sions to zero, but also can actually show
a removal of CO2 from the atmosphere.
Table 2 gives the stoichiometry of the
photosynthesis process for producing bio-
mass (wood) and the coprocessing of bio-
mass with natural gas, oil, and coal. For
various methods of methanol synthesis,
including conventional and Hydrocarb,
Table 3 summarizes the carbon and en-
ergy utilization efficiencies, and the CO
generated when using only the methanol
and when using both the methanol and
carbon.
Conventional steam reforming and air
oxidation processes generate more than
50% greater amounts of CO/IO6 Btu of
methanol energy than if the fossil fuel
were burned directly. Using Hydrocarb with
bituminous coal alone reduces CO2 emis-
sions by about 60%; however, the energy
utilization efficiency is reduced by 38%
because the carbon is not used. The
coprocessing of biomass with natural gas
and oil can actually remove as much as
78 Ib of CCyi O6 Btu from the atmosphere
while generating 166 and 115% more en-
ergy, respectively, than the energy con-
tent of gas and oil. These results occur
because solar energy utilized in growing
biomass is assumed to be free.
Coprocessing with coal shows a zero emis-
sion of CO2 and a 50% utilization of the
energy in coal. Utilizing both the methanol
and carbon more than doubles the utiliza-
tion of coal and reduces the CO2 genera-
tion by 50% compared to conventional
production of methanol from coal.
Background Process Data
Supporting the Hydrocarb
Process
There is an abundance of coal
hydrogasification data. Work at BNL on
flash hydropyrolysis indicates that 90%
conversion of carbon in lignite to methane
can be obtained at 2500 psi* and 900° C
at residence times of 5-10 sec. The
Rheinbraun Co. in West Germany oper-
ated a 240 ton/day (T/D) brown coal fluid-
ized bed hydrogasifier, and obtained over
80% carbon conversion of which 90% was
converted to methane, the remainder be-
ing CO and CO2
At BNL, experiments on the hydrogas-
ification of wood in and entrained flow
tubular dilute phase reactor indicated that
over 90% of the carbon in the wood can
be converted to methane and CO at resi-
dence times of up to 2 sec, temperatures
of 800 - 1000° C, pressures of 200 - 500
psi, and concentrations of less than 10%.
The reactivity of wood towards
hydrogasification is greater than that of
coal. However additional data are needed
* Readers more familiar with the metric system
may use the factors at the end of this sum-
mary to convert to that system.
Table 2. Reduction of Atmospheric COS by Photosynthesis and Thermochemistry
I. Photosynthesis - Driven by solar energy - biomass formation
C02 + 0.72 H20 = CH1440066 -f 1.03O2
hemi-cellulose
biomass
II. Thermochemica! Cracking - Thermal energy driven - high efficiency Hydrocarb Process
1 . Biomass alone
CHi.44°o.ee
0.66 H2O + 0.06 H2
Sequester C in the earth
O emission/MMBtu of H2 energy
Fraction of biomass energy used = 6%
2. Biomass + natural gas
CHi.«°o.ee
0.34 CH4 = 0.64 + 0.66 CH3OH
Sequester C - utilize methanol for energy
CO2 removed from atmosphere = 78 Ib CO2/MMBtu
Energy Enhancement of Natural Gas = 163%
3. Biomass + oil
CH1440068
0.7 CH17 = C
0.66 CH.OH
Sequester C - utilize methanol for energy
CO2 removed from atmosphere = 78 Ib CO^MMBtu
Energy enhancement of oil = 115%
4. Biomass + bituminous coal
0.32CH144Ooee + CH08O01 = C + 0.32 CH3OH
Sequester C - utilize methanol for energy
CO2 balance - O emission of CO2
Fraction of coal energy used = 50%
to obtain higher concentrations of meth-
ane much closer to equilibrium values,
necessary for the Hydrocarb Process to
work efficiently.
Methane decomposition has been prac-
ticed for a long time by industry in making
thermal black from natural gas by pyroly-
sis. Literature data also indicate that the
reaction is catalyzed by substrates of iron
oxide, aluminum oxide, and (to some ex-
tent) by carbon itself. A process called
Hypro was actually operated by an oil
company to produce hydrogen for a refin-
ery from methane by thermal decomposi-
tion. Additional work is required to deter-
mine the kinetics of methane cracking at
elevated pressures.
Methanol formation is basically conven-
tional by the well-known low pressure ICI
copper catalysts. The main difference is
that Hydrocarb operates on the synthesis
gas stream once through, without recy-
cling.
Value of Carbon and Methanol
as Fuel
Clean carbon and methanol can be used
in heat engines (turbines and diesels) while
coal because of its ash and sulfur content
cannot be readily used because of corro-
sion and erosion of turbine blades and
cylinder walls. Carbon with a density of 2
g/cm3 can be slurried with water, oil, and
methanol to energy densify the liquid fu-
els. Experimental characteristics of a num-
ber of carbon slurries have been prepared
and measured.
Process Design and Analysis
Extensive process design and analysis
of the Hydrocarb Process has been made
for several of its configurations. Mass and
energy balances have been made based
on approaching thermodynamic equilibrium
among the five gaseous components CH4,
CO, CO , H ,and HO. A Hydrocarb Pro-
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Tab/a 3. COS Generated or Removed From the Atmosphere by Various Methanol Synthesis and Coprocessing Systems Using Fossil Fuel and
Biomass Feedstocks
Energy utilization CO2 generated(+)
Carbon utilization Energy utilization CO2 generated {+) efficiency using both CO2 removed (-)
methanol only efficiency methanol CO2 removed (-) methanol and carbon Ib CCyMMBtu of
based on fossil only based on fossil Ib CO2/MMBtu based on fossil fuel both mehtanol and
fuel feedstock only fuel feedstock only of methanol feedstock only carbon generated
Feedstock Methanol process % % generated energy % energy
Conventional-
Produces-COj
natural gas
on
coal-bit
Hydrocarb-
store carbon
bit coal
(added H2O)
lignite
Hydrocaxb
co-processing
with biomass store
carbon
steam reforming 82
partial oxidation 50
steam-oxygen reforming 42
68
64
64
+170
+280
+330
Hydro carb
Hydrocarb
27
18
40
30
+130
+130
92
92
+250
+270
II biomass
+ natural gas
III biomass
IV biomass
+ bit coal
Photosynthesis
+ Hydrocarb
Photosynthesis
+ Hydrocarb
Photosynthesis
+ Hydrocarb
200
85
30
166
115
50
-78
-78
280
215
130
+41
+76
+162
Note: 1) combustion of natural gas generates 110 Ib CO,/MMBtu, oil 160 Ibs/MMBtu, bit. coal 215 Ibs CCyMMBtu, Lignite 225 Ibs CO./MMBTU
2) Assumes 90% conversion of feedstock to mehtanol in Hydrocarb Process.
cess Simulation model has been devel-
oped to obtain full mass, energy, and com-
positional data for each feedstock and pro-
cess configuration.
Sulfur removal is a special problem.
One approach is to feed dolomite or lime
in conjunction with coal to the
hydropyrotosis reactor. The bulk of the
gasified sulfur Is removed as CaS, which
then must be properly disposed of with
the ash. A zinc oxide guard filter is used
to protect the catalytic converter from be-
coming poisoned by the sulfur. Reactor
design can be of the moving bed or the
fluidized bed type, with the former giving
a higher thermal efficiency but more diffi-
cult operation.
Preliminary economic analysis indicates
that for a 10,000 T/D fast rotational poplar
tree crop supplying wood from an energy
farm, at $38/ton, to a Hydrocarb plant
together with natural gas at $2.50/1000
scf would require a capital investment of
$577 million and, taking credit for carbon
at $2.50/108 Btu, could yield a selling price
for methanol of $0.37/gal., which is eco-
nomically competitive with conventional
production of methanol from natural gas
at $0.45/gal.
Conclusions
It is concluded that the Hydrocarb
coprocessing of fossil fuel with biomass is
technically feasible. Methanol and carbon
as clean fuel would be suitable for use in
heat engines (turbines and diesels) at com-
petitive prices with oil and gas. By se-
questering the carbon and using only the
hydrogen-rich methanol as fuel, the emis-
sion of CO2 can be significantly reduced
compared to the direct combustion of fos-
sil fuel. Additional kinetic data for the
hydrogasification of biomass under meth-
ane-rich conditions, as well as experimen-
tal data on the thermal decomposition of
methane under pressure and temperature
conditions designed for the Hydrocarb Pro-
cess, are required before proceeding with
a process demonstration unit.
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Conversion Factors
Readers more familiar with the metric
system may use the following factors to
convert to that system.
Nonmetric Multiplied by Yields metric
atm 101.3 kPa
Btu 1.06 kJ
gal. 3.785 liter
psi 6.89 kPa
scf 0.028 sm3
ton 907.2 kg
•&U.S.GOVERNMENT PRINTING OFFICE: 1992 - 648-080/40 KO
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M. Steinberg is with Brookhaven National Laboratory, Upton, NY 11973; and
£ Grohse and Y. Tung are with Hydrocarb Corp., Upton, NY 11776
Robert H. Borgwardt is the EPA Project Officer (see below).
The complete report, entitled "A Feasibility Study for the Coprocessing of Fossil Fuels
With Bhmass by the Hydrocarb Process," (Order No. DE91- 011971'/AS; Cost:
$26.00, 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 and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/600/S7-91/007
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