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

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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

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      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

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