Increased efficiency of topping cycle PCFB power plants

Pressurized circulating fluidized bed (PCFB) power plants offer the power industry significantly increased efficiencies with reduced costs of electricity and lower emissions. When topping combustion is incorporated in the plant, these advantages are enhanced. In the plant, coal is fed to a pressurized carbonizer that produces a low-Btu fuel gas and char. After passing through a cyclone and ceramic barrier filter to remove gas-entrained particulates and a packed bed of emathelite pellets to remove alkali vapors. the fuel gas is burned in a topping combustor to produce the energy required to drive a gas turbine. The gas turbine drives a generator combustor, and a fluidized bed heat exchanger (FBHE). The carbonizer char is burned in the PCFB and the exhaust gas passes through its own cyclone, ceramic barrier filter, and alkali getter and supports combustion of the fuel gas in the topping combustor. Steam generated in a heat-recovery steam generator (HRSG) downstream of the gas turbine and in the FBHE associated with the PCFB drives the steam turbine generator that furnishes the balance of electric power delivered by the plant

Pressurized Fluidized Bed Combustion Second-Generation System Research and Development

Research is being conducted under United States Department of Energy (DOE) Contract DE-AC21-86MC21023 to develop a new type of coal-fired plant for electric power generation. This new type of plant--called a Second-Generation or Advanced Pressurized Circulating Fluidized Bed Combustion (APCFB) plant--offers the promise of efficiencies greater than 45% (HHV), with both emissions and a cost of electricity that are significantly lower than conventional pulverized-coal-fired plants with scrubbers. The APCFB plant incorporates the partial gasification of coal in a carbonizer, the combustion of carbonizer char in a pressurized circulating fluidized bed boiler (PCFB), and the combustion of carbonizer syngas in a topping combustor to achieve gas turbine inlet temperatures of 2300 F and higher. A conceptual design was previously prepared for this new type of plant and an economic analysis presented, all based on the use of a Siemens Westinghouse W501F gas turbine with projected carbonizer, PCFB, and topping combustor performance data. Having tested these components at the pilot plant stage, the referenced conceptual design is being updated to reflect more accurate performance predictions together with the use of the more advanced Siemens Westinghouse W501G gas turbine and a conventional 2400 psig/1050 F/1050 F/2-1/2 in. steam turbine. This report describes the updated plant which is projected to have an HHV efficiency of 48% and identifies work completed for the October 2001 through September 2002 time period

CONCEPTUAL DESIGN AND ECONOMICS OF A NOMINAL 500 MWe SECOND-GENERATION PFB COMBUSTION PLANT

Research has been conducted under United States Department of Energy Contract DE-AC21-86MC21023 to develop a new type of coal-fired plant for electric power generation. This new type of plant, called a Second Generation Pressurized Fluidized Bed Combustion Plant (2nd Gen PFB), offers the promise of efficiencies greater than 48 percent, with both emissions and a cost of electricity that are significantly lower than those of conventional pulverized coal-fired (PC) plants with wet flue gas desulfurization. The 2nd Gen PFB plant incorporates the partial gasification of coal in a carbonizer, the combustion of carbonizer char in a pressurized circulating fluidized bed boiler, and the combustion of carbonizer syngas in a gas turbine combustor to achieve gas turbine inlet temperatures of 2300 F and higher. A conceptual design and an economic analysis was previously prepared for this plant. When operating with a Siemens Westinghouse W501F gas turbine, a 2400psig/1000 F/1000 F/2-1/2 in. Hg. steam turbine, and projected carbonizer, PCFB, and topping combustor performance data, the plant generated 496 MWe of power with an efficiency of 44.9 percent (coal higher heating value basis) and a cost of electricity 22 percent less than a comparable PC plant. The key components of this new type of plant have been successfully tested at the pilot plant stage and their performance has been found to be better than previously assumed. As a result, the referenced conceptual design has been updated herein to reflect more accurate performance predictions together with the use of the more advanced Siemens Westinghouse W501G gas turbine. The use of this advanced gas turbine, together with a conventional 2400 psig/1050 F/1050 F/2-1/2 in. Hg. steam turbine increases the plant efficiency to 48.2 percent and yields a total plant cost of $1,079/KW (January 2002 dollars). The cost of electricity is 40.7 mills/kWh, a value 12 percent less than a comparable PC plant

Development of second-generation PFB combustion plants

Research is being conducted under United States Department of Energy (USDOE) Contract DE-AC21-86MC21023 to develop a new type of coal-fueled plant for electric power generation. This new type of plant--called an Advanced or Second-generation Pressurized Fluidized Bed Combustion (APFBC) plant--offers the promise of efficiencies greater than 45 percent (HHV), with both emissions and a cost of electricity that are significantly lower than conventional pulverized-coal-fired plants with scrubbers. This paper summarizes the pilot-plant R&D work being conducted to develop this new type of plant and discusses a proposed design that should reduce demonstration-plant risks and costs

Efficient gas stream cooling in Second-Generation PFBC plants

The coal-fueled Advanced or Second-Generation Pressurized Fluidized Bed Combustor concept (APFBC) is an efficient combined cycle in which coal is carbonized (partially gasified) to fuel a gas turbine, gas turbine exhaust heats feedwater for the steam cycle, and carbonizer char is used to generate steam for a steam turbine while heating combustion air for the gas turbine. The system can be described as an energy cascade in which chemical energy in solid coal is converted to gaseous form and flows to the gas turbine followed by the steam turbine, where it is converted to electrical power. Likewise, chemical energy in the char flows to both turbines generating electrical power in parallel. The fuel gas and vitiated air (PFBC exhaust) streams must be cleaned of entrained particulates by high-temperature equipment representing significant extensions of current technology. The energy recovery in the APFBC cycle allows these streams to be cooled to lower temperatures without significantly reducing the efficiency of the plant. Cooling these streams would allow the use of lower-temperature gas cleanup equipment that more closely approaches commercially available equipment, reducing cost and technological risk, and providing an earlier path to commercialization. This paper describes the performance effects of cooling the two hottest APFBC process gas streams: carbonizer fuel gas and vitiated air. Each cooling variation is described in terms of energy utilization, cycle efficiency, and cost implications

Second-Generation Pressurized Fluidized Bed Combustion: Small gas turbine induustrial plant study

Second-Generation Pressurized Fluidized Bed Combustion (PFBC) plants provide a coal-fired, high-efficiency, combined-cycle system for the generation of electricity and steam. The plants use lime-based sorbents in PFB combustors to meet environmental air standards without back-end gas desulfurization equipment. The second-generation system is an improvement over earlier PFBC concepts because it can achieve gas temperatures of 2100[degrees]F and higher for improved cycle efficiency while maintaining the fluidized beds at 1600[degrees]F for enhanced sulfur capture and minimum alkali release. Second-generation PFBC systems are capable of supplying the electric and steam process needs of industrial plants. The basic second-generation system can be applied in different ways to meet a variety of process steam and electrical requirements. To evaluate the potential of these systems in the industrial market, conceptual designs have been developed for six second-generation PFBC plants. These plants cover a range of electrical outputs from 6.3 to 41.5 MWe and steam flows from 46,067 to 442,337 lb/h. Capital and operating costs have been estimated for these six plants and for equivalent (in size) conventional, coal-fired atmospheric fluidized bed combustion cogeneration plants. Economic analyses were conducted to compare the cost of steam for both the second-generation plants and the conventional plants

Pressurized fluidized bed combustion second-generation system research and development. Technical progress for Phase 2 and Phase 3, October 1, 1997--September 30, 1998

When DOE funds were exhausted in March 1995, all Phase 2 activities were placed on hold. In February 1996 a detailed cost estimate was submitted to the DOE for completing the two remaining Phase 2 Multi Annular Swirl Burner (MASB) topping combustor test burns; in August 1996 release was received from METC to proceed with these tests. The first test (Test Campaign No.3) will be conducted to: (1) test the MASB at proposed demonstration plant full to minimum loading operating conditions; (2) identify the lower oxygen limit of the MASB; and (3) demonstrate natural gas to carbonizer fuel gas switching. The Livingston Phase 3 Pilot Plant was last operated under contract DE-AC21-86MC21023 in September 1995 for seven days in an integrated carbonizer-CPFBC configuration. In May, 1996, the pilot plant was transferred to Contract DE-AC22-95PC95143 to allow testing in support of the High Performance Power Systems (HIPPS) Program. The HIPPS Program required modifications to the pilot plant and the following changes were incorporated: (1) installation of a dense phase transport system for loading pulverized coal into the feed system lock hopper directly from a pneumatic transport truck; (2) removal of the char transfer pipe between the char collecting hopper and the CPFBC to allow carbonizer only operation; (3) installation of a lock hopper directly under the char collecting hopper to facilitate char removal from the process, the hopper vent gases exhaust to the carbonizer baghouse filter and the depressured char is transferred via nitrogen to the CPFBC baghouse for dumping into drums; (4) removal of the carbonizer cyclone and top of bed overflow drain line; all material elutriated from the carbonizer bed will thus be removed by the 22-element Westinghouse ceramic candle filter; (5) replacement of the carbonizer continuous bottom bed drain (screw feeder) with a batch-type drain removal system; and (6) installation of a mass spectrometer that draws sample gas via a steam jacketed line from the refractory lined piping downstream of the candle filter