3

Fuel Gas

British Gas Lurgi

British Gas Lurgi

FIGURE 7-6. Schematic diagram of the Kentucky Pioneer Energy IGCC demonstration project (with MCFC slipstream shown). (From DOE, Clean Coal Technology Demonstration Program: Program Update 2001 Including Power Plant Improvement Initiative Projects, Office of Fossil Energy, U.S. Department of Energy, Washington, D.C., July 2002.)

FIGURE 7-6. Schematic diagram of the Kentucky Pioneer Energy IGCC demonstration project (with MCFC slipstream shown). (From DOE, Clean Coal Technology Demonstration Program: Program Update 2001 Including Power Plant Improvement Initiative Projects, Office of Fossil Energy, U.S. Department of Energy, Washington, D.C., July 2002.)

converted into 99.99% pure sulfur, NOZ emissions were 0.15 lb/MM Btu (thus meeting 2003 target emission limits for ozone non-attainment areas), particulate emissions were below detectable limits, CO emissions averaged 0.05 lb/MM Btu, and coal ash was converted to a low-carbon vitreous slag valued as an aggregate in construction or as grit for abrasives and roofing metals [4]. The plant is currently in commercial operation.

Kentucky Pioneer Energy, LLC, was awarded a CCT Program project to demonstrate and assess the reliability, availability, and maintainability of a utility-scale IGCC system using a high-sulfur bituminous coal and refuse-derived fuel blend in oxygen-blown, fixed-bed, BGL slagging gasifiers, and the operability of an MCFC fueled by coal gas [4]. The IGCC system, shown in Figure 7-6, is located at the East Kentucky Power Cooperative Smith site (Trapp, Kentucky), and its capacity is 580 MW. The MCFC portion of the project, which is a slipstream of fuel gas fed to the gas turbine (and rated at 2.0 MW), has been moved to the Wabash River site [9]. The IGCC system to be demonstrated in this project is suitable for both repowering applications and new power plants. Permitting for the IGCC system is still under way. The fuel cell portion of the project broke ground in August 2003 [9].

Advanced Combustion/Heat Engines Two projects are demonstrating advanced combustion/heat engine technology. One project has been completed, and the other is delayed. Alaska Industrial Development and Export

Authority demonstrated TRW's clean coal combustion system integrated with B&W's spray dryer absorber (SDA) with sorbent recycle [41]. The demonstration was performed adjacent to Healy Unit No. 1. The objective was to demonstrate an innovative new power plant design featuring integration of an advanced combustor coupled with both high- and low-temperature emissions control processes. Emissions were controlled using TRW's advanced entrained/slagging combustors through staged fuel and air injection for NOz control and limestone injection for SO2 control. Additional SO2 control was accomplished using B&W's activated recycle SDA. Carbon burnout goals of greater than 99% were achieved and emissions were successfully controlled: NOz emissions averaged 0.245 lb/MM Btu, SO2 removal efficiencies in excess of 90% were achieved with typical emissions of 0.038 lb/MM Btu, particulate matter emissions were 0.0047 lb/MM Btu, and CO emissions were less than 130 ppm at 3.0% O2 [4].

TIAX (formerly Arthur D. Little, Inc.) is demonstrating a coal-fired diesel engine operation with the objective to prove the design, operability, and durability of the coal diesel engine during 4000 hours of operation and to test a coal slurry in the diesel [4]. A Fairbanks Morse 18-cyclinder, heavy-duty engine (6.4 MW) modified to operate on Alaskan subbituminous coal made into a low-rank coal-water fuel is expected to have very low NOx and SO2 emission levels (50-70% below current NSPSs). In addition, the demonstration plant, located at the University of Alaska (Fairbanks), is expected to achieve 41% efficiency, with future plant designs expected to reach 48% efficiency, which will result in a 25% reduction in CO2 emissions compared with conventional coal-fired plants. Testing has been delayed due to TIAX's reorganization [9].

Coal Processing for Clean Fuels Technology

The CCT Program also addresses approaches to converting raw run-of-mine coals to high-energy density, low-sulfur products. Four projects completed in the category of coal processing for clean fuels represent a diversified portfolio and include two projects that produced high-energy density solid fuels (see discussion in Chapter 5, Technologies for Coal Utilization), one of which also produced a liquid product equivalent to No. 6 fuel oil; one project that demonstrated a new methanol production process; and one project that complemented the process demonstrations by providing an expert computer model that enables a utility to assess the environmental, operational, and cost impact of utilizing coals not previously burned at a facility, including upgraded coal and coal blends [4].

ENCOAL Corporation demonstrated SGI International's Liquids-From-Coal (LFC®) process at Triton Coal Company's Buckskin Mine (located near Gillette, Wyoming) [42]. The project objective was to demonstrate the integrated operation of a number of novel processing steps to produce two higher heating value fuel forms with lower sulfur contents from mild gasification of low-sulfur subbituminous coal and to provide sufficient products for potential end users to conduct burn tests. The process, described in Chapter 5, produces a Process-Derived Fuel (PDF®) and Coal-Derived Liquid (CDL®). The LFC® process consistently produced 250 short tons/day of PDF® and 250 barrels/day of CDL® fro m 500 short tons of run-of-mine coal per day. The PDF® contains 0.26% sulfur with a heat content of 11,100 Btu/lb (compared with 0.45% sulfur and 8300 Btu/lb for the feed coal) [4]. The CDL® contains 0.6% sulfur and has a heating value of 140,000 Btu/gallon (compared with 0.8% sulfur and 150,000 Btu/gallon for No. 6 fuel oil) [4].

Western SynCoal LLC (formerly Rosebud SynCoal Partnership, a subsidiary of Montana Power Company's Energy Supply Division) demonstrated their advanced coal conversion process (ACCP) of upgrading low-rank sub-bituminous coal and lignite [43]. The process, described in Chapter 5, was performed to demonstrate the potential of ACCP to produce a stable coal product having a moisture content as low as 1%, sulfur content as low as 0.3%, and heating value up to 12,000 Btu/lb [4]. The ACCP project processed over 2.8 million short tons of raw coal at Colstrip, Montana, to produce nearly 1.9 million short tons of SynCoal® products that were shipped to utility and industrial users. Lower emissions of SO2 and NOx were reported in addition to increased power plant output due to the higher grade of fuel burned.

Air Products Liquid Phase Conversion Company, LP (a limited partnership between Air Products and Chemicals, Inc., the general partner, and Eastman Chemical Company), demonstrated Air Products and Chemicals' liquid-phase methanol process [44]. The objective was to demonstrate, on a commercial scale, the production of methanol from coal-derived synthesis gas using the LPMEOHTM process; to determine the suitability of methanol produced during this demonstration for use as a chemical feedstock or as a low SO2- and NO x-emitting alternative fuel in stationary and transportation applications; and to demonstrate, if practical, the production of dimethyl ether (DME) as a mixed co-product with methanol [4]. The LPMEOH™ process, illustrated in Figure 7-7, was successfully operated for 69 months, and the demonstration ended in December 2002 [45]. Over the entire operating period, the demonstration facility (located at Kingsport, Tennessee) operated at an on-stream availability of 97.5% and produced nearly 104 million gallons of methanol, all of which was accepted by Eastman Chemical Company for use in downstream chemical processes. The facility is currently being operated in a commercial mode by Eastman Chemical Company [45]. The process was developed to enhance IGCC power generation by producing a clean-burning, storable liquid fuel from clean coal-derived gas. Methanol contains no sulfur and has exceptionally low NOx characteristics when burned.

The final project in this category was the development of CQ, Inc.'s (Homer City, Pennsylvania) EPRI Coal Quality Expert™ (CQETM) computer software [47]. The objective of the project was to provide the utility industry with a PC software program it could use to confidently and inexpensively

H2 Feed gas

Recycle Syngas

Purge Gas

To Fuel

H2 Feed gas

Recycle Syngas

Purge Gas

To Fuel

FIGURE 7-7. LPMEOH™ demonstration unit process flow diagram. (From DOE, Clean Coal Technology: Commercial-Scale Demonstration of the Liquid Phase Methanol (LPMEOHtm) Process, Technical Report No. 11, Office of Fossil Energy, U.S. Department of Energy, Washington, D.C., April 1999.)

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evaluate the potential for coal cleaning, blending, and switching options to reduce emissions while producing the lowest cost electricity [4]. Specifically, the project was intended to (1) enhance the existing Coal Quality Information Systems (CQISTM) database and Coal Quality Impact Model (CQIMtm) to allow assessment of the effects of coal cleaning on specific boiler costs and performance; and (2) develop and validate CQETM, a model that allows accurate and detailed prediction of coal quality impacts on total power plant operating cost and performance. The model that was developed evaluates the impacts of coal quality, capital improvements, operational changes, and environmental compliance alternatives on power plant emissions, performance, and production costs [4].

Industrial Applications Technology

Projects were also undertaken to address pollution problems associated with using coal in the industrial sector. Five projects encompass substitution of coal for 40% of the coke in iron making (completed), integration of a direct iron-making process with the production of electricity (ongoing), reduction of cement kiln emissions and solid-waste generation (completed), demonstration of an industrial-scale slagging combustor (completed), and demonstration of a pulse combustor system (completed). Although electricity can be produced at the industrial scale, these projects are not discussed in this chapter as they have limited or no applicability in power generation and, except for the Blast Furnace Granular-Coal Injection System Demonstration Project [48] and Passamaquoddy Technology Recovery Scrubber™, have not been considered commercial successes in that no domestic or international sales have been made of the demonstrated technologies nor are they in continued operation at the demonstration site [49].

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