Hot Gas Filtration Meeting Turbine Requirements for Particulate Matter

The Power Systems Development Facility (PSDF) is an engineering scale demonstration of advanced coal-fired power systems and high-temperature, high-pressure gas filtration systems. The PSDF was designed at sufficient scale so that advanced power systems and components can be tested in an integrated fashion to provide data for commercial scale-up. The PSDF is funded by the U.S. Department of Energy, the Electric Power Research Institute, Southern Company Services, Kellogg Brown & Root, Inc. (KBR), Siemens-Westinghouse, and Peabody Energy. Gasification at the PSDF is based on KBR’s Transport Gasifier, which is an advanced circulating fluidized-bed gasifier. Hot gas filtration is a critical process in the gasification system to clean up the particulate matter before the synthesis gas (syngas) is fed to the turbine. A Siemens-Westinghouse particulate control device (PCD) is used for syngas cleanup. The PCD contains 91 candle-style filter elements. More than twenty types of filter elements, categorized as monolithic ceramic, composite ceramic, sintered-metal powder, and sintered-metal fiber, have been tested in the gasification environment at the PSDF. Up to January 2005, the longest exposure time for individual filters has been 5783 hours. The particulate loading in the clean syngas during most stable operating periods has been demonstrated to be consistently below 0.1 ppmw, which is the lower detection limit of Southern Research Institute’s sampling system. Safeguard devices (failsafes) have also been tested and developed at the PSDF. Failsafes are used to block the particulate leaking through the PCD in the case of filter element failure to eliminate damage to the turbine. Demonstration of reliable failsafes is a critical factor to the hot gas filtration technology. Several types of currently available failsafes and PSDF-developed failsafes have been tested in the PCD with gasification ash injection to simulate filter element leakage. A typical failsafe was also tested in a device equipped with a quick-open mechanism to simulate a complete filter failure during a test run operation. The testing showed promising results for certain types of failsafes. Further failsafe testing and better understanding of turbine requirements for particulate loading are needed to evaluate the PCD performance and increase readiness towards commercialization of the technology.