97/01858 Development of hot gas filtration for air blown gasification plant

Abstract

This paper describes some of the development work carried out on hot gas filtration for the Air Blown Gasification Cycle (ABGC). The ABGC comprises partial gasification of coal at elevated pressure with combustion of the fuel gas produced in a gas turbine. The residual carbon from gasification is burned in an atmospheric pressure circulating fluidized bed combustor raising steam to drive a steam turbine. A critical requirement in the ABGC is to ensure that the fuel gas is free of dust, in order to avoid damage to the gas turbine. Ceramic filter elements are the preferred technology for this clean-up. The required operating temperature is 400--600 C, based on optimizing efficiency and to allow use of other hot gas clean-up systems, for instance for sulfur polishing. A development program on hot gas filtration has been carried out at CTDD in order to ensure that this component of the cycle can be used with minimum risk. To date, over 2,000 h of operation at up to 600 C has been achieved on two pilot scale hot gas filters, each taking full flow of gas from air blown gasifiers. The filters have operated with high availability and there have been no incidentsmore » of breakage of filter elements. Information has been generated for effect of filtration velocity and temperature, cleaning gas requirements, changing dust and gas composition, and for design of critical components such as fast opening valves, venturi ejectors and sealing mechanisms. The effect of different operating conditions on filter element strength has been evaluated for a range of filter elements.« less