CLEAN COAL SYSTEM

 

            Copyright: Author - C. V. Hall & ecoTECH Waste Management Systems (1991) Inc.

 

 

 

 

 

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)
 

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

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