Development of a Direct Coal-Fired Combined Cycle for Commercial Application

Abstract

A program has been underway since 1986 by Westinghouse Electric Corporation, Textron, Inc., and the sponsoring agency, the Morgantown Energy Technology Center (METC) of the U.S. Department of Energy (DOE), as participants, to establish the technology base for coal-fired combustion turbines targeted for power generation (50 to 150 MW size units). The developed system must be able to burn unbeneficiated, low-cost, utility-grade coal and meet the EPA New Source Performance Standards (NSPS) for coal-fired steam generators (Thoman et al., 1987). Development of a high pressure (12 to 16 atms) slagging combustor is the key to making a direct coal-fired combustion turbine a commercial reality. In testing to date, a 6 atm slagging combustor, rated at 12 MMBtu/hr (12.7 MHkJ/hr) has demonstrated its ability to handle high- and low-sulfur bituminous coals, and low-sulfur subbituminous coal. The program objectives relative to combustion efficiency, combustor exit temperature and pattern factor, NOx emissions, carbon burnout, and slag rejection have been met. Today, Northern States Power, working with Westinghouse with assistance from Textron is developing a plan to commercialize a direct coal-fired advanced combined cycle (DCFACC). Included in this plan is a pilot plant (which does not include a combustion turbine) and a demonstration plant that would utilize a 50 MW combustion turbine. The first commercial DCFACC, which would Include a 100 MW combustion turbine, is scheduled to be operational by the year 2001. The cooperative effort among Northern States Power, Westinghouse, and Textron is financially independent of the work now sponsored by DOE/METC. This paper presents the status of the pressurized slagging combustor development program including recent work to reduce alkali, particulates and SOx levels leaving the combustor and gives an overview of our commercialization process and plan.

A Direct Coal-Fired Combustion Turbine Power System Based on Slagging Gasification With In-Situ Gas Cleaning

“…and plant availability has not been engineering studies were conducted as well as slagging gasifier significantly reduced by turbine maintenance needs. testing using NSF feedstocks (Bannister et al, 1992). The DC?!'…”

Westinghouse Status of Coal and Biomass Fueled Combustion Turbine Systems for Power Generation

“…Westinghouse has evaluated design modifications required for our 251 and 501D5 combustion turbines to be used in PFBC applications. (Bannister et al, 1993. 3000 0 to 3600°F (1650° to 1985°C) range (Bannister, Newby, and Diehl, 1992). As illustrated in Figure 5, air for combustion is taken from the outlet of the combustion turbine compressor.…”

“…Westinghouse has tested cross flow and candle filter elements on field test facilities for entrained coal gasifiers and fluidized bed coal gasifiers. A Texaco entrained coal gasifier test facility (Lippert et al, 1993), a KRW fluid bed coal gasifier test facility (Haldipur et al, 1989), and a Foster Wheeler fluid bed coal carbonizer test facility (Newby et al, 1992) have logged more than 2000 hours of hot fuel gas exposure over a wide range of conditions Figure 6. Pinon Pine Hot Gas Filter from 805° to 1800°F (430°-980°C) with low-and medium-Btu fuel gases.…”

“…The small alkali sorbent particles remove alkali vapors while they reside in the gas phase and during their longer residence time within the filter cake. Reaction kinetics have been measured in laboratory rigs, and larger scale testing has been completed in a nominal 170 m 3 /hr (100 acfm) filter test facility (Newby et al, 1992).…”

Advanced Turbine Systems Program

“…The coal-fired system is an integrated system bleeding air from the compressor and returning a low heating value fuel to the gas turbine (Bannister, Newby and Diehl, 1992). The increase in volume flow to the turbine, compared to a natural gas-fired (dry) system, can usually be accommodated without turbine modifications.…”