United States
Environmental Protection
Agency
Industrial Environmental Researc
Laboratory
Research Triangle Park NC 2771
vvEPA
Research and Development
EPA-600/S7-82-045 September 1 982
Project Summary
Combustion of Oil Shale in
Fluidized-Bed Combustors-
An Overview
Douglas R. Roeck
Oil shale can be combusted (alone or
as a supplement to coal) and function
as an SO2 sorbent in atmospheric
fluidized-bed combustion (AFBC).
Spent shale from retorting processes
may also provide for SO2 sorption and
some residual fuel value in AFBC.
Commercial applications of direct
combustion of oil shale in AFBC are
limited, and known to exist only in
Estonia (Soviet Union), China, and
Southern Germany. Combustion of
shale and coal/shale mixtures in
AFBCs in the U.S. has been investi-
gated on a pilot and laboratory scale.
Technical concerns include calcination
heat loss, optimal shale sizing, and
combustion efficiency. Direct com-
bustion of Western U.S. shale in a pilot
AFBC resulted in NO* emissions as
high as 3 lb/1O6 Btu, although for
coal/shale mixtures NOX emissions
were below 0.6 lb/106 Btu. Because
of its calcium carbonate content,
shale can act as an effective SOa
sorbent in AFBC, and has resulted in
SOa reduction efficiencies of greater
than 85% in tests with coal/shale
mixtures. A preliminary economic
analysis indicates that substituting oil
shale for limestone in an AFBC may
have significant cost advantages
where shale (or spent shale) is available
at costs that are competitive with
conventional sorbents.
This Project Summary was devel-
oped by EPA's Industrial Environ-
mental Research Laboratory, Research
Triangle Park, NC. to announce 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
The U.S. has vast oil shale resources
that may be commercially developed
during the 1980s. Production estimates
for the emerging oil shale industry
range as high as 3 million bbl/day by the
year 2000, although 0.5 million bbl/day
may be a more realistic estimate. A
single full-scale commercial plant
producing 50,000 bbl/day would use
60,000 ton/day of high-grade shale
containing 35 gal./ton and would
produce 51,000 ton/day of spent shale.
AFB combusters could potentially be
used to burn virgin oil shale or oil shale
fines to produce steam or electricity.
Virgin or spent shale could be used in
coal/shale mixtures to provide heat and
capture potential SOa emissions. The
technoeconomic feasibility of using oil
shale to provide some heating value and
control SOa emissions from coal com-
bustion appears to be promising
In the U.S., research and pilot scale
experiments have been conducted by
the U.S. Department of Energy and
several private AFBC manufacturers.
DOE has conducted tests on oil shale
from Colorado, Israel, and Morocco at its
research facility in Morgantown, VW.
Private research has been conducted by
the Babcock and Wilcox (B&W) Re-
search and Development Division, by
Foster Wheeler Company, and by
numerous companies involved in the
-------
Table 2. Comparison of Direct Operating Costs for a 250,000 Ib/hr FBC Boiler Burning Coal with Limestone and Oil Shale Sorbents
Cost data /S/WOO Ib steam)
Test
description
Base case
Case No. J
(B&W Test
No. Til
Case No. 2*
(ANL Test
No. 171
Case No. 3"
(ANL Test
No 20)
Coal
Feed
Sulfur rate
% Ib/hr
35 34,012
3.6 26,377
3.0 21,632
2.0 28,950
HHV
Btu/lb
10,430
12,300
12,183
12,183
Sorbent Sorbent
SO, Snlirl rnal
Feed Ca/S reduc- waste at at at at at at
rote HHV molar tion rate $35/ S5/ $10/ S20/ $25/ $30/
Type Ib/hr Btu/lb ratio % Ib/hr ton ton ton ton ton ton
Limestone 12.256 — 3.0 85 13,484 2.38 — 0.2
049
0.61
0.74
Virgin 30.557 1.0OO 2.4 84 31,257 1 85 0.31
shale 061
1.22
— 1.83
Virgin 30.285 3,020 3.1 87.5 23,168 1.51 0.30
shale 0.61
1.21
— 1.82
Spent 5.790 400 1.2 95.9 8,546 203 0.06
shale 0. 12
0.23
— 0.35
Solid
waste
removal
at
S6/
ton
0 16
0.16
016
0.16
038
0.38
0.38
0.38
0.28
0.28
0.28
0.28
0 10
0.10
0.10
0.10
Total
direct
operating
cost*
3.92
4.16
4.28
4.41
3.67
3.97
4.58
5.19
3.22
3.53
4.13
4.74
3.32
3.38
3.49
3.61
'Not shown in this table are other components of the total direct operating cost: electricity, oil, and labor.
"Tests at ANL were by thermogravimetric analysis
on the costs of conventional sorbents as
well as other costs related to transporting
the raw or spent shale to an industrial
or utility-coal-burning facility. For a
retorting facility, generating its own
power in a fluidized-bed, coal-burning
power plant, the concept should be both
technically feasible and cost competi-
tive with limestone for achieving any
required SC"2 reduction.
Since oil shale combustion tests to
date have been conducted in fluidized
bed reactors 18 in. in diameter or less,
further testing in larger scale equipment
is warranted before firm conclusions
can be drawn concerning the prospects
of scaling up to commercial application.
The preliminary economic analysis
indicates that costs for operating an FBC
unit using oil shale as an SO2 sorbent
are competitive with similarly sized
FBCs using conventional limestone
sorbent. While direct operating costs
were -25 to +21% and total annualized
costs -15 to +13%, compared to the
coal/limestone base case, these costs
are highly dependent on the cost of the
shale. Given that the test data used for
this cost comparison were developed
from FBC units 18 in. in diameter or
less, such an assessment should be
repeated using test data resulting from
larger scale equipment if and when
such data become available.
Metric Conversion
Readers more familiar with metric units are asked to use the following factors to
convert certain non-metric units used in this summary.
Non-metric
Multiplied by
Yields metric
bbl
Btu
°F
ft
gal.
in.
Ib
ton
159
1055
5/9f°F-32)
0.3
3.79
2.54
0.45
8897
I
J
°C
m
I
cm
kg
Nt
-------
6.0
5.0
to
.1
§
t
0)
4.0
3.0
2.0
— — ,-
- Spent Shale
10 15 20
Sorbent Cost, $/ton
25
30
Figure 2.
Direct operating cost as a function of sorbent cost for various coal-
sorbent systems.
Douglas R. Roeck is with CCA/Technology Division, Bedford, MA 01730.
John O. Mill/ken is the EPA Project Officer (see below).
The complete report, entitled "Combustion of Oil Shale in Fluidized-Bed Com-
bustors—An Overview," (Order No. PB 82-249 889; Cost: $9.00. subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, MA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park. NC 27711
•&U. S. GOVERNMENT PRINTING OFFICE: I982/559-092/0502
-------
-------
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
PS 0000329
U S ENVIR PROTECTION AGENCY
REGION 5 LIBRARY
230 S DEARBORN STREET
CHICAGO IL 60604
------- |