EPA
         Decision
Jnited States
•nvironmental
'rotection Agency
Office of
Research and
Development
Energy,
Minerals and
Industry
EPA-600/9-77-013

June 1977
          Advanced
          Fossil Fuels
          and the
          Environment

-------
      ADVANCED
     FOSSIL FUEL
        AND THE
   ENVIRONMENT:
An Executive Report

-------
CONTENTS
Introduction                                                   1



Chemical Coal Cleaning                                           3



Synthetic Fuels                                                 7



Chemically Active Fluid Bed                                       13



Oil Shale                                                    16



Liquid Fuels Cleaning                                           19



Prospect                                                    22



Further Reading                                               23


-------
 CHEMICAL
 COAL
 CLEANING
 Process
 Chemical coal cleaning is used to remove sulfur and other
 pollutants from coal before it is burned. Sulfur is found in
 coal in two general forms: organic and pyritic. Organic
 sulfur is part of the molecular structure of coal, while
 pyritic sulfur, or iron sulfide, is part of the mineral portion
 of coal. The sulfur content of coal, both organic and
 pyritic, ranges from less than 1% to over 8%, depending
 on the coal type. Pyritic sulfur accounts for about half of
 the total sulfur in a given type of coal. When coal is
 burned, the pyritic sulfur, along with some of the organic
 sulfur, is transformed to sulfur dioxide and becomes a
 major source of air pollution. Chemical cleaning, which
 involves leaching to wash out pyritic sulfur and heating to
 break the bonds that bind the organic sulfur to coal, is
 potentially more effective in ridding coal of its pollutants
 than conventional physical cleaning methods.

 Four chemical coal cleaning methods are currently being
 evaluated by EPA. These are:
     Meyers process
     Hydrothermal process
     Flash desulfurization process
     Microwave process.

 Meyers Process — In the Meyers process, a heated
 liquid iron sulfate leaching solution is reacted with ground
 coal. This leaching action releases pyritic sulfur as well as
 iron, alkaline ash, and other impurities. Following the
 leaching, the coal is washed to remove these
 contaminants and the leaching solution is then processed
 for reuse. No organically bound sulfur is removed
 because the leaching solution does not penetrate the
 carbon-coal matrix. The Meyers process is 95% effective
 in removing pyritic sulfur in pilot plant tests (7 metric tons
 per day).
 Hydrothermal Process — The hydrothermal process
 adds a leaching solution of sodium hydroxide, calcium
 hydroxide, or their combination, to a mixture of crushed
coal and water at moderate temperatures. This heating/
 leaching transforms the solid sulfur compounds and ash
to a solution, which can then be separated from the coal.
This process removes up to 95% of the pyritic sulfur
 and 40% of the organic sulfur in pilot plant tests (1A ton
 per day).
Flash Desulfurization Process — This process exposes
coal to hydrogen at low pressure and high temperature. In
this reaction, the sulfur in the coal is released into the gas
stream where it is purified. Flash desulfurization removes
over 90% of the total sulfur content of coal in laboratory
tests.
Microwave Process — The microwave process heats
coal to high temperatures so that the volatile parts of the
pyritic sulfur are vaporized for separate recovery. This
process is being evaluated to determine how much of the
sulfur can be removed.
Rationale
The successful development of chemical coal cleaning
and its adoption by the public and private sectors could
potentially:

Assure removal of pyritic and organic sulfur
from coal, while at the same time maintain a high
level of energy content in the cleaned coal.
Physical coal cleaning methods in industrial use
today remove some of the pyritic sulfur but do not
remove organic sulfur. The amount of pyritic sulfur
removed by physical methods ranges from 50% to
70%. In removing this pyritic sulfur, however,
physical cleaning methods also significantly reduce
the energy content of coal.

Offer a viable alternative to smaller users of coal
for control of air pollution from combustion.
Some industrial users of coal may not be able to use
flue gas desulfurization equipment because its size
may be incompatible with installed combustion
equipment, or the cost of adding stack gas
scrubbers may preclude economical operation of
the industrial plant.

Provide an economic advantage to coal users.
Initial cost/benefit analyses of cleaning  coal using
both chemical and physical methods plus flue gas
desulfurization indicate a net cost saving to coal
users compared with the use of flue gas scrubbers
alone. Although some of the coal is inevitably lost in
the cleaning process, thereby reducing the total

-------
coal cleaned and its pyritic sulfur content. If the Meyers
process proves to be efficient and economical, this could
be an advantage to small industrial users of coal who may
not be able to afford stack-gas contaminant removal
technologies.
Program
The four chemical cleaning methods being sponsored by
the EPA Interagency Program are currently undergoing
careful evaluation:

   Meyers Process — Development is at the pilot-
   plant stage and is receiving the major portion of
   current Interagency Program funds allocated to
   chemical coal cleaning because it appears to be the
   most promising of the four technologies under study.
   EPA is funding $4 million for a one-year demon-
   stration of the process, scheduled to begin in the
   spring of 1977. The reactor test unit was designed by
   Procon, Inc., Los Angeles. Construction of the unit
   began in November 1976, at a site near Capistrano,
   California. TRW, Inc., Redondo Beach, California,
   will operate the pilot plant. The unit, which will treat
   about 7 metric tons of coal per day, performs only
   leaching and regeneration operations. Dewatering,
   drying, and sulfur removal will be done in the
   laboratory using coal samples from the test unit.
   Bench-scale support and applicability studies will be
   carried out concurrent with the test of the pilot plant.

   The actual operation of this pilot plant is expected to
   demonstrate more effective coal cleaning process-
   ing and lower costs than previously indicated in
   laboratory and  bench-scale tests. If these
  expectations are realized, EPA may
   recommend completion  of the pilot plant
  to  add dewatering, drying, and sulfur
  removal equipment. Further
  testing will then define process
       applicability, design, and cost data. Industrial and utility
       support will be sought during the test to help identify
       practical operating problems.

       Flash desulfurization — Experiments are under
       way at the Institute of Gas Technology (IGT) in
       Chicago to establish the potential of this process.
       EPA is funding $370,000 for this 20-month project.
       Chemical reactions to remove nitrogen as well as
       sulfur are being evaluated as a part of this
       EPA-sponsored program.

       Hydrothermal coal cleaning — This process was
       investigated by Battelle Laboratories in Columbus,
       Ohio. Although the process is technologically
       feasible, it does not appear to be cost competitive
       with other chemical coal cleaning methods.

       Microwave treatment — Research performed at
       General Electric Company,  Valley Forge,
       Pennsylvania, is currently being reviewed  by EPA to
       determine the potential of microwave treatment to
       release both the pyritic and the organic sulfur in
       coal.

    EPA also has a large ongoing program of environmental
    assessment of chemical coal cleaning processes.
    Process streams, compounds,  and discharges that have
    adverse health and ecological effects are being analyzed.
    Results are used to establish permissible concentrations
    of potentially hazardous substances. Environmental
    guidelines for developers of coal cleaning processes will
    be based on the permissible concentrations determined in
    these studies.

    As an adjunct to this chemical cleaning research, EPA and
    the U.S. Bureau of Mines plan to use computer modeling
HYDROTHERMAL
                             MEYERS  PROCESS

-------
 SYNTHETIC
 FUELS
 Process
 The federal government is giving priority to the develop-
 ment of coal gasification and liquefaction processes. Such
 processes, it is hoped, will produce an adequate supply of
 synthetic gaseous and liquid fuels as sources of domestic
 petroleum are exhausted and petroleum imports become
 more expensive. The prime responsibility for the actual
 development of these coal conversion processes belongs
 to ERDA. The EPA responsibility is to ensure that these
 processes do not create adverse health and ecological
 effects. Major EPA concerns are the nature of pollutant
 by-products, the locations in the process stream where
 environmental control technologies should be integrated,
 and the development of effective environmental control
 techniques.

 Synthetic fuel development research is concentrated on
 producing substitute natural gas (SNG) and liquid fuels,
 primarily for use as refinery feedstock and in electric
 power generation.  However, gasification units are already
being used by industry and more are scheduled to be
installed. Thus, it is logical to assume that industry, rather
than the electric utilities, will be the first to adopt advanced
gasification techniques as they become ready for
commercial use.

Coal gasification can produce iow-, medium-, and
high-Btu gas. The low-Btu gas has a heating value of 100
to 200 Btu per cubic foot and is used as a fuel feedstock
or to generate power in combined gas-steam turbine
power cycles. The medium-Btu gas has a heating value of
300 to 650 Btu per cubic foot and is usually used as a
feedstock in the production of high-Btu gas. This high-Btu
gas, with a heating value of 950 to 1,000 Btu per cubic
foot, can be substituted for natural gas in industrial and
residential consumption.

Coal liquefaction is used to produce an entire range of
liquid products from coal. These products  include fuel oil,
gasoline, jet fuel, and diesel oil. Processes are being
developed and  improved to increase the supply of
nonpolluting liquid fuels as well as to facilitate their
transport and use. Current emphasis is being placed on
the development of lower grade synthetic fuels suitable
for firing industrial and electric utility boilers and gas
turbines.
 Coal Gasification Process
 Coal is gasified by applying heat and pressure or a
 catalyst to break down the components of coal to form a
 synthesis gas containing mainly carbon monoxide, hydro-
 gen, and some methane. The gas formed in this way may
 also contain carbon dioxide, nitrogen, water vapor, and
 contaminants such as hydrogen sulfide and ash.

 In simple gasification, a synthetic gas is produced  by
 reacting coal with steam or hydrogen and air or oxygen. If
 air is used, a low-Btu, nitrogen-rich gas is produced. The
 nitrogen limits the heating value of the synthesis gas and
 could cause release of environmentally hazardous
 nitrogen oxides (NOx) if the gas were burned as fuel. The
 gas also will contain sulfur oxides and other pollutants
 that have to be removed.

 Alternatively, if oxygen is used, medium-Btu gas is
 produced. This product gas contains some sulfur oxides
 but no nitrogen. It is usually intermediate to the production
 of high-Btu gas.

 Other gasification reactions use hydrogen instead of
 steam. This produces more methane directly in the
 synthesis gas than is produced in simple gasification.
 Consequently, the medium-Btu gas produced by hydro-
 gasification requires less additional processing to be trans-
 formed to a high-Btu gas. Moreover, higher overall con-
 version efficiencies can be realized with hydrogasification
 than with simple gasification.

 High-Btu gas is made from low- and medium-Btu gases
 by adjusting the ratio of hydrogen to carbon monoxide  in
 these gases. This ratio adjustment is called the water-gas
 shift reaction. The gas is also purified  by removing  the
 acid gases produced in the reaction, chiefly hydrogen
 sulfide and carbon dioxide. The remaining hydrogen and
 carbon monoxide are then combined to form methane
 and water — a methanation reaction. The water is then
 removed leaving a methane-rich product with the
 essential characteristics of natural high-Btu gas.

Gasification is carried out in either a fixed bed reactor,
fluidized bed reactor, or entrained bed reactor.

 In the fixed bed reactor crushed coal is fed to the reactor to
form a bed. Air or oxygen and steam are blown  upward
through the bed at a relatively low velocity to gasify the
coal. The raw synthetic gas exits from the top of the  reactor
and is quenched to remove tars, oils, and particulates. The
gas is then cooled for further processing.

-------
                                            DIRECT CATALYTIC
                                            HYDROGENATION
 processing.
 The data developed on the
 types and quantities of
 pollutants and the levels at
 which they become toxic are used to
 develop criteria for controlling such pollution.

 A synthetic fuel industry will grow rapidly when
 production processes are proven technically and
 economically viable. Environmental control technologies
 developed concurrent with the processes themselves will
 avoid costly delays which would be necessitated by
 attempts to add environmental controls after processes
 are perfected. Environmental controls integrated into
 processing systems are also likely to be more efficient
than add-on methods.
lack of information on individual devices hinders their
environmental control evaluation. Moreover, the United
States has only a few advanced processing pilot plants on
which to test control technologies. Some information is
being collected on gasification processes in foreign
countries. However, the results obtained from monitoring
the operation of foreign plants may not be applicable to
U.S. plants because of the differences in foreign and U.S.
coal and the consequent variations in effluents.

Other technical problems involve the removal of individual
pollutants, such as solid waste in the form of particulates,
at the high temperatures and high pressures in some of
the gasification processes. Large particulates, over  a few
microns in size, can cause erosion of power plant turbine
blades, while the smaller particulates are environmentally
undesirable. It is not clear at what stage in the fuel
conversion stream these particulates can be most
effectively and economically removed. Their effective
removal, in any event, will be a benefit both to process
technology and to environmental control technology. The
current alternatives for removal are during or after
gasification. The tradeoffs between these alternatives
Factors
Technological — Most process technology developed for
gasification/liquefaction
is proprietary. The
consequent
                            PURIFICATION
                                                SOLVENT
                                                EXTRACTION

-------
 will produce 90,000 cubic meters per hour {cu M/H) of raw
 generated gas and 60,000 cu M/H of clean gas. It also
 produces appreciable amounts of tar; heavy, medium-
 heavy, and light oil; raw phenol; and ammonia water. The
 Kosovo plant is equipped with only minimal environmental
 controls. It does not have a sulfur recovery unit or an
 operational waste water treatment facility.

 The Lurgi process is to be used in three industry-
 sponsored commercial U.S. coal gasification plants. The
 three are sponsored by the Western Gasification
 Company (WESCO), the El Paso Natural  Gas Company,
 and the Michigan-Wisconsin Pipeline Company. The
 results of research at the Kosovo plant will  provide a basis
 for establishing environmental control technologies to be
 incorporated into the design of U.S. plants, an
 economically and operationally superior alternative to
 retrofit controls. Recommendations for municipal
 regulations on disposal of solid waste from coal
 gasification  plants also will be made on the basis
 of the study.

 The Kosovo project was approved by the U.S. and
 Yugoslavian governments in June 1976. EPA has
 allocated $290,000 for the three-year program.
 Yugoslavia is providing matching funding.

 Gas and water treatment — A gas treatment test facility
 is being constructed at North Carolina State University to
 treat raw gas that contains large amounts of acids. The
 facility is being designed and installed by the Aerotherm
 Division of Acurex Corporation, Mountain View, California.
 Research on treating waste water is being  performed by
 the University of North Carolina under a grant from EPA.

 High temperature/high pressure particulate re-
 moval — To develop the technology necessary to remove
 solid waste particles from fluidized bed reactors used in
 gasification, HTP particulate removal programs, mainly at
 the bench-scale level, have been funded. Additionally,
 some demonstration tests of electrostatic precipitators
 have also received agency support. An HTP electrostatic
 precipitator (1700°F) is being developed by Research-
 Cottrell, Inc., Bound Brook, New Jersey, under a
$130,000 contract from EPA. Standard electrostatic
 precipitators operate at 600° to 800°R

 Filter concepts for HTP control are under study by several
contractors. A contract for assessment of granular bed
filtering is currently being negotiated. Westinghouse is
 evaluating the use of ceramics and other materials as
 filters. Aerotherm is comparing the collection perfor-
 mance of metallic, ceramic, and fabric filters against the
 performance of electrostatic precipitators.

 Air Pollution Technology Corporation, San Diego, has a
 contract to develop a bench-scale dry scrubber for HTP
 particulate removal.

 Economically viable techniques to remove large and small
 particulate matter at gasifier exit temperatures are being
 sought. The cost tradeoffs between high-temperature and
 low-temperature particuiate removal are also being studied.

 Pollutant sampling and emission standards —
 Additional research on identifying pollutants from synthetic
 fuels processing is expected to begin by early 1977.

 EPA is reviewing preliminary new source performance
 standards for atmospheric emission of sulfur and
 hydrocarbons from coal gasification plants. These
 standards will be published in 1977. But no new standards
 on water pollution are planned because the demands of
 environmental control technologies on plant water use are
 not yet known.

Agency Interaction
EPA, under the auspices of the Interagency Program, is
working closely with ERDA to collect data on environ-
mental effects of coal gasification/liquefaction in a
number of projects.

     EPA is evaluating data on process effluents from
     ERDA gasification and liquefaction pilot plants —
     HYGAS in Chicago,  Solvent Refined Coal (SRC) in
     Tacoma, Washington. Joint agency environmental
     testing is planned. SRC is the liquefaction process
     that is closest to commercialization. In addition, EPA
     has entered into an agreement with ERDA to
     characterize effluents and to provide guidance for
     ERDA's comprehensive industrial gasification
     program including the startup and operation of pilot
     plant gasifiers at Morgantown, West Virginia, and
     Grand Forks, North Dakota.
                                  EPA and ERDA are
                                  coordinating work on
                                  particulate  removal
                                  concepts. The most
                                  effective devices will
                                  be recommended
                                  for future analysis.
                               LIQUID HYDROCARBON SYNTHESIS
                                                                                                          11

-------
 CHEMICALLY
 ACTIVE
 FLUID  BED
 Process
 The chemically active fluid bed (CAFB) process is
 designed to convert heavy, high-sulfur residual oil to
 clean, low-sulfur gas. The process also may be applicable
 to making clean gas from high-sulfur coal.

 In applying  the process to residual oil, the oil is first heated
 and then fed to a reactor that contains a fluidized bed of
 fine particles of limestone. The oil is vaporized in  the
 reactor through a series of catalytic cracking and  oxida-
 tion reactions. Hydrogen sulfide and some organic
 sulfur are released from the vaporized oil to be absorbed
 by the lime  in the "boiling" limestone. The remaining hot,
 low-sulfur fuel gas produced in the process can be piped
 directly to steam boilers or gas turbines for combustion.

 The CAFB reactor contains two sections, one for
 gasification  of the oil and one for regeneration of the
 sulfur-absorbing lime.  In the regeneration step, air reacts
 with the limestone, freeing it from the sulfur, which is
 released into the air stream as sulfur dioxide. The sulfur
 dioxide is removed from the regeneration gas and  may be
 converted to a nonpolluting solid. The cleansed limestone
 is then recycled through the reactor continuously  until it
 loses its efficiency as an absorbent.
Rationale
Many utilities are required to burn only low-sulfur fuel in
order to meet federal and state emissions regulations.
This means that large supplies of heavy residual oils
remain untapped as sources of fuel for power plants. In
the face of the growing shortage of domestic oil supplies,
it is important that maximum use be made of all grades of
petroleum. By efficiently converting high-sulfur residual oil
to clean gaseous fuel, the CAFB process offers an
environmentally sound means of freeing this resource for
the production of energy.

The process has particular importance as a retrofit
mechanism for the numerous gas-fired power plant
 boilers in the southwest. These boilers cannot be readily
 converted to the use of high-sulfur heavy oil or coal. Most
 of the existing gas-fired boilers in Texas, for instance,
 have a remaining life of 20 to 30 years, but the sources of
 natural gas to fuel them are expected to be unavailable in
 just a few years. These boilers are in power plants that
 currently produce approximately 120,000 megawatts of
 power. Use of the CAFB process could permit this level of
 energy production to be maintained throughout the useful
 life of these boilers.

 In addition, the CAFB process offers a technological
 advantage over other methods of contaminant removal by
 avoiding the necessity of cooling and scrubbing the gas.
 These methods lower the heating value of the product gas
 and the efficiency of the gasification process.
 Factors
 Technological — Individual power plants may present
 engineering problems in retrofitting the CAFB process.
 The age and condition of boilers and the size of burners
 will have to be considered in designing retrofit equipment.
 The adequacy of existing pipelines to handle liquid fuels
 will be another design consideration. But these problems
 are expected to be readily solved on a case-by-case basis
 using good engineering practice.

 Environmental — The release of large amounts of sulfur
 in the gasification step of the CAFB process is a basic
 environmental concern. The efficiency of the fluidized bed
 of limestone will determine how much of this sulfur, in the
 form of highly toxic hydrogen sulfide gas, reaches the
 atmosphere. Efficient removal of the sulfur dioxide gas
 released from the limestone in the regeneration step is
 also necessary to maintain air quality.

 Another environmental concern  is the release of con-
taminant metals such as vanadium, nickel, sodium, and
some alkali metals during gasification. These  metals pose
a health hazard because of their high toxicity. There is
concern that these toxic metallic substances, which may
have been present only in trace  amounts in the original
fuel, will be concentrated as a result of the fuel conversion
process in amounts that intensify their pollution potential.
                                                                                                   13

-------
 Approximately $1.3 million is allocated for studies of the
 process in FY77.
 Outlook
 Preliminary calculations indicate that the CAFB process
 can be as much as three times more efficient in pollutant
 removal than initial estimates suggested. However,
 demonstration tests under a range of operating conditions
 and grades of fuel are necessary to confirm these
 indications. The full capability of the process also has
 yet to be determined. To confidently predict the efficiency
 of the process over years of operation, it will be important
 to determine early in the demonstration tests how
 effectively contaminants are removed.
 With the capabilities of the process determined, standards
 of practice and recommendations for control technologies
 can be formulated to meet environmental requirements.
 For these purposes, long-term monitoring of emissions
 and waste streams will be necessary.

 The economics of the process in terms of retrofit,
 operation, maintenance, and costs added to the fuel
 product will have to be determined. How well the process
 competes with the cost of alternative technologies such
 as flue gas desulfurization also will require analysis.

 Work on the CAFB concept to date suggests that it has
 significant potential as a means of producing clean fuel.
 The next step in the development of the process is the
 demonstration at La Palma Station to determine the
 technical, environmental, and economic realities of plant
 operation.
      Chemically Active  Fluid  Bed  Facts
Process: Heating high-sulfur coal or residual oil in the
         presence of a fluidized bed of limestone to
         convert the coal or oil to gas and transfer sulfur
         and other contaminants to the limestone.

Purpose: Make high-sulfur oil and coal available as a
         boiler fuel.
Problems: Retrofit of boilers to use the CAFB process.
          Transport of liquid fuels to the boilers.
          Hydrogen sulfide and sulfur dioxide emissions.
          Heavy metals release from spent limestone.
          Inadequate information on installation and
          operating costs.

Potential:  CAFB may be more efficient than
          expected. Fuels produced by CAFB
          will be clean and air pollution will be
          reduced. Techniques to handle
          CAFB solid wastes already exist.
                                                                                                 15
                                                        yet on tne TeasiDiiuy
                                                                                                     19

                                                                                                     23

-------

-------