Liquefaction co-processing of coal shale oil at - Argonne National ...

cost of coal liquefaction, the high recycle oil requirements. In all direct
liquefaction processes coal is slurried with a process derived recycle oil at a
mica1 ratio of 2:l recycle oil to coal feed. Coprocessing of residuum and coal
reduces the high cost associated with recycle oil by eliminating or reducing the
requirements for recycle oil.
Coprocessing hydrocracking technology was originally developed for processing heavy
crude with coal additives as a means of inhibiting the formation of coke. The
CANMET hydrocracking process is based upon this comcept. This emerging technology
shows promise of I]iqh demetallization, residuum hydrocracking, and high conversion
of the pitch (975 F ) fraction. Coal additives include 1.0 - 2.0 wt.% of fine coal
and ferrous sulfate.
Integration of the CANMET type process initially to an existing refinery and/or idle
units is a first step toward utilization of coal and heavy oils (pitch and
asphaltenes). A once through process arrangement without the use of a recycle
stream may also be possible at lower coal concentrations.
Coprocessing technologies to be included in a staged approach are HRI, Lumnus, and
the Cherry-P processes which can process up to 50 wt.% of coal in heavy oil
fraction.
Implementation of coprocessing will likely require additional refinery hydrogen
generation. This will probably be based upon steam reforming of hydrocarbon gases
and light naphtha. Steam reforming is a well established and adopted method of
generating hydrogen. The expansion of reforming units can be accomplished more
easily than integrating gasification units into refineries.
Hydrostabilization of product distillates are incorporated into a refinery to
provide hydrotreatment and product stabilization prior to distribution outside the
refinery complex. Further pretreatments for heteroatom removal may be required in a
refinery utilizing coprocessing derived liquids.
The introduction of coal/residuum coprocessing will tend to reduce crude re-
quirements. The extent of reduction will be dictated by market demands as well as
product yields and qualities of the coprocessing distillate liquids. Other
positive factors are 1) the use of existing refinery and infrastructure, 2) better
economics than direct liquefaction, 3) compatability with the use of heavier crudes,
and 4) the capability of installing a coprocessing unit independently from existing
refinery operations.
Potential Coal Requirements
An estimate of the potential coal requirements for coal/oil coprocessing for the
general refinery types in the United States is presented in Table 2. These
capacities represent an upper limit for the application of coal/residua coprocessing
as fuel oil production was assumed to be zero. It was also assumed that COprocessing
is more economic than vacuum distillation (both cases are highly
unlikely). Based upon a 1985 production capacity of 890 million tons of coal in the
U.S.; coal producing capacity would have to increase by one-third if the upper
limits of coal/residua coprocessing were achieved.
The most likely near term application for coal/oil coprocessing appears to be for
residuum conversion capacity additions to low conversion refineries to improve
profitability and to high conversion refineries to provide the capability for
handling future feedstocks with increasingly higher residuum content. This premise
is based on the assumption that present trends toward a heavier crude feedstocks and
lighter reduced fuel oil requirements will continue. In terms of refinery capacity,
average size Hydroskimming or Topping and High Conversion Refineries
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