&ER& United States Environmental Protection Agency Industrial Environmental Research Laboratory Research Triangle Park NC 27711 Research and Development EPA-600/S7-82-028 August 1982 Project Summary Pilot-Scale Assessment of Conventional Particulate Control Technology for Pressurized Fluidized-Bed Combustion Emissions W. 0. Lipscomb III, S. R. Malani, C. L. Stanley, and S. P. Schliesser This report presents the results of a performance evaluation of con- ventional particulate control tech- nology applied to the EPA/Exxon pressurized fluidized-bed combustion (PFBC) mini plant in Linden, NJ. The EPA mobile electrostatic precipitator (ESP) and fabric filter pilot facilities were slipstreamed downstream of the miniplant's tertiary cyclone to simulate the flue gas stream exiting a PFBC combined-cycle gas turbine. Results presented include control- device operating characteristics and performance based on mass and fractional efficiencies. ESP mass efficiency varied from 80 to 90 percent and appeared to be sensitive to miniplant operating conditions. The mobile baghouse efficiency was 99.3 percent. The EPA mathematical performance models for the ESP, fabric filter, and venturi scrubber were exercised to generate a basis for an economic analysis of conven- tional particulate control alternatives. Costs of control for a 350 MW PFBC ranged from 0.33 to 0.51 mills/kWh for fabric filters and from 0.30 to 0.57 mills/kWh for ESPs. Venturi scrubbing costs were considerably higher (0.66 mills/kWh). This Project Summary was developed by EPA's Industrial Environmental Research Laboratory, Research Triangle Park, NC. to announce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering information at back). Introduction and Objectives Fluidized-bed combustion (FBC) sys- tems being developed for steam and electrical power generation and process heating employ a number of concepts, including atmospheric and pressurized combustion, temperature control by fuel-to-air ratio, heat transfer surface, and particulate circulation. These FBC systems offer attractive advantages over conventional combustion in costs, resource utilization, and environmental impact. Current FBC development programs use calcium-based sorbents (limestones and dolomites) for in-situ control of sulfur oxides (SOx) in the combustor, while lower combustion temperatures limit to some degree the formation of thermal nitrogen oxides (NOX). Particu- late matter (PM) emissions from an atmospheric FBC system are controlled by conventional technology. In contrast, the pressurized fluidized-bed combustion (PFBC) process uses the hot, high- pressure flue gas exiting the combustor to drive a gas turbine to generate additional power, and conventional ------- technology for control of PM emissions is not applicable. There has been considerable discus- sion of the degree of PM removal required ahead of the gas turbine to prevent excessive corrosion and/or erosion of the turbine. High-pressure, high-temperature PM control technology (e.g., ceramic filters) has been investi- gated to provide a flue gas cleansed of PM to ensure acceptable turbine operating and maintenance costs and life expec- tancy. Recently, turbine designers have reduced the limitations on PM concen- tration and size distribution required so that a secondary or tertiary cyclone system can achieve the required level of PM control. The residual particulates, while acceptable for the gas turbine, must be further controlled to meet environmental standards. This study assessed a pilot-scale application of conventional PM control technology (i.e., an electrostatic precipi- tator (ESP) and a fabric filter (baghouse)) to a PFBC cyclone-cleaned exhaust. The program's objectives were accomplished using EPA's mobile ESP and baghouse slipstreamed from the 630 kW EPA/Exxon Research and Engineering Company miniplant in Linden, NJ. The mobile ESP pilot assessment was conducted during April and May 1979, and the mobile fabric filter program was accomplished in June 1979. Specific program objectives were to: • Test the applicability of conventional PM control technology to cyclone- cleaned PFBC emissions. • Evaluate respective control device operating characteristics and per- formance levels. • Exercise EPA/IERL-RTP's control device performance models to esta- blish a basis for cost analysis. • Generate cost-of-control estimates for an ESP, a baghouse, and a venturi scrubber. Results presented in this report are specific to the EPA Exxon miniplant and the slipstreamed mobile ESP and bag- house; extrapolation to other systems may be risky. Conclusions The study pointed to the following conclusions: • Conventional PM control technology appears applicable to cyclone- cleaned PFBC emissions. • ESP operating characteristics and performance were influenced by PFBC operating conditions and sorbent type. Cold-side ESP perfor- mance was better than hot-side performance on a normalized gas treatment basis. • Fabric filtration affords an appreci- ably higher degree of control at approximately the same costs as an ESP. • This PFBC process is apparently subject to peaking sulfur dioxide (SOzJ/sulfur trioxide (SOs) emission levels, which cause acid dew-point excursions and seriously impact control hardware specifications and operating conditions. • There were both similarities and differences in conventional control device operating characteristics for the PFBC process and for conventional coal-fired boilers. Recommendations Recommendations generated by the study include: • Conduct further pilot-scale control evaluations of the PFBC process to optimize control device design and operating conditions. • Address the extent of and resolution of the apparent SOz/SOa excursions associated with this and possibly other PFBC processes. W. 0. Lipscomb. Ill, S. R. Malani, C. L Stanley, and S. P. Schliesser are with Acurex Corporation, Morrisville, NC 27560. John O. Milliken is the EPA Project Officer (see below). The complete report, entitled "Pilot-Scale Assessment of Conventional Particu- late Control Technology for Pressurized Fluidized-Bed Combustion Emis- sions," (Order No. PB 82-230 921; Cost: $13.50, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Industrial Environmental Research Laboratory U.S. Environmental Protection Agency Research Triangle Park, NC 27711 » U.S. GOVERNMENT PRINTm0OfFICE:1«K-559-Ol7/0773 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Postage and Fees Paid Environmental Protection Agency EPA 335 Official Business Penalty for Private Use $300 PS ------- |