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SYNOPSIS
During the period of the “Energy Cost Crisis” of the mid 1980’s
considerable research effort was dedicated worldwide to development
of Coal/Water (CWS) and Coal/Oil/Water (COW) Slurries for use as
replacement of Heavy Fuel Oil for generating electrical power in
Thermal Generating Utility Stations. The Chemical Engineering
Laboratories of the National Research Council of Canada conducted
some of the most significant technological development.
Demonstration projects using the product of the research were
conducted in the Atlantic provinces of Canada cooperatively with
researchers at the Technical University of Nova Scotia (TUNS), the
Nova Scotia Power Corporation (NSPC) and the Cape Breton Development
Corporation (CBDC).
Slurries containing 70% coal together with water and special
chemicals to maintain the product in stable slurry forms for
long-term storage were successfully produced, shipped to
international customers and burned to produce power. All of the work
relied on using finely pulverized coal (-200 mesh), and in the
processing of this material methods were developed to reduce the ash
and the pyritic sulphur by significant amounts.
The research work also determined that the level of ash and sulphur
reduction achievable was very dependent of the specific properties
of the coal used in the process. In general high bituminous coals
provided the greatest opportunity for ash reduction, while coals
toward the lignite end of the coal range were capable of some ash
and sulphur decrease, but provided the lowest improvement. However
in all cases ash reductions were possible with the added advantage
of improving the Caloric Value of the end product significantly.
Besides enabling the production of a storable, pumpable coal product
added benefits observed in the demonstration work using the reduced
ash level product consistently improved conditions within the
combustion devices by:
• Improving the overall total gas flow
rates by reducing the carry through rates;
• Increasing the ash fusion temperature within the combustion zone
and;
• Hence reduced the fouling within the boiler heat exchange
surfaces;
• Reducing the boiler tube erosion associated with slagging and
fouling;
• Improved flame characteristics within the combustion zone;
and other significant improvements to enhance boiler performance and
efficiency.
ecoTECH uses a sono-chemical micronizer reactor to produce a
coal/water emulsion spray fuel that is compatible with its second
stage vortex combustion unit (post gasification cyclonic venturi
burner)
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HISTORY OF COAL BENEFICIATION
The National Research Council of Canada (NRC) began experimenting
with coal beneficiation in the mid-sixties. Their emphasis at that
time was to maximize the use of coal as an alternative fuel to
petroleum products (Heavy Fuel Oil) for utility power generation.
The meteoric rise of energy prices during the seventies focused the
world’s energy sector on beneficiation as a possible answer to oil
shortages by replacing some or all of the oil demand for these
applications with a coal/oil or coal/water emulsion containing
primarily powdered coal.
In 1979 the Energy Research Laboratory was installed at The
Technical University of Nova Scotia. This research centre was
financially supported by the National Research Council of Canada to
conduct cooperative coal related combustion research and fluid bed
combustion technology. By this time the National Research Council
had obtained patents on beneficiating coal. Senior Research
Scientists of the Council cooperated on applications and equipment
required to perfect the beneficiation process. These research
efforts used various Eastern Canadian coals and additives. In 1985,
the NRC and Sulzer Brothers Ltd., Winterthur, Switzerland conducted
cooperative research with Coal Water Slurries.
By that time the research had established that over ninety-five
percent of the inert substances in coal (pyretic sulphur and ash)
can be removed prior to burning, thereby allowing improved
hydrocarbon coal to be burned (varies depending on the quality of
the coal). The Technical University of Nova Scotia, the Nova Scotia
power Corporation, and the Cape Breton Development Corporation set
up Projects in Atlantic Canada and successfully demonstrated the
practical applications of the Research.
ecoTECH Sono Chemical Reactor |
