97/03725 Utility applications for coal water slurry cofiring

Abstract

In order for the electric utilities to continue to use coal and still meet environmental requirements, deeper cleaning of coal will be required. The downside to that cleaning is the increased generation of coal fines. These fines are produced from coal cleaning processes and are generally disposed of in settling ponds. If the coal pond fines can be economically recovered and used, the material is no longer a liability but represents a significant stockpile of fuel. Recovery of the fines for use as a low solids coal water slurry (CWS) is one means of utilizing this resource and is attractive from both an economic and an environmental standpoint. CWS from freshly produced coal fines have been successfully co-fired with pulverized coal in boilers at Penn State University and Penelec. Penelec has recently completed formulation and combustion testing of this concept at a total boiler combustion rate of 20% on a 32 MWe boiler utilizing a slurry produced at the coal preparation facility at Homer City, PA. The objectives of the project were: (1) to determine the technical feasibility of co-firing; (2) to develop the design criteria for formulating low solids CWS without the need for costly additives; and (3) tomore » utilize the fuel without the need for major boiler modifications. An additional benefit of this process is the reduction in NOx formation compared to firing with pulverized coal alone. This paper presents the success to date of the co-firing of low solids CWS with pulverized coal in a utility scale boiler using {open_quotes}Fresh{close_quotes} fines directly from coal cleaning circuits. The paper also outlines continuation work in progress and the future outlook on the effects of the implementation of the technology. The use of coal fines as a CWS feedstock has the potential to generate a new market for a material that is currently discarded as waste by coal producers and to provide possible savings in fuel costs to coal users.« less