Gasification based combined cycle processes are being developed throughout Europe to meet energy requirements through environmentally acceptable use of fossil fuels. Typical combined cycles can increase the efficiency of power generation by 20% or more compared with conventional coal fired power stations, whilst reducing emissions of acid and greenhouse gases substantially.
To achieve simultaneously the environmental benefits, plant life and availability, whilst maximising the efficiency of power generation, it is generally necessary to clean the fuel gas at high temperatures. A prerequisite for a clean fuel gas of a quality acceptable for use in the current generation of high temperature gas turbines is the efficient removal of all particulates down to a size and concentration which does not damage the hot gas path components in the turbine. Furthermore, this level of particulate removal is often a prerequisite for other processes to remove gaseous contaminants from the fuel gas stream.
Reliable filtration with a low pressure drop operation was achieved at 400-600(C from air-blown coal and biomass gasification combined cycle technologies. The filtration process performed well during different aspects of plant control, including start-up, load change, and for process upsets such as high tar formation. The filter technology operated for a wide range of gasifier coal and sorbent feedstocks without formation of the dust cakes experienced at higher temperatures which are difficult to clean. The components of filter systems were developed with improvements made to filter elements, cleaning system design, and configurations. Experimental equipment and mathematical modelling tools were also developed and improved, and these can be used in future advances in filtration technology.
Hot gas filtration using ceramic candle filters has been used to remove particulates in high pressure combustion products gas with some success. However, the problems associated with this technology and the solutions applied are not directly applicable to the gasification environment.
The project focuses on identifying and resolving the major problems for these filters in the gasification environment at the temperatures stated above. This will be achieved through the following:
1. Developing a clear understanding of the mechanisms involved in filtering gasifier dust and the subsequent cyclic cleaning of the filter elements. 2. Determining the factors affecting the durability of ceramic candle elements and critical mechanical components.
3. Developing operational and control strategies for acceptable operational life.
4. Developing mathematical models to assist in the design and scale up of filters.
5. Carrying out test programmes on hot gas filters operating under conditions representative of high pressure and intermediate temperature fuel gas cleaning.
Funding SchemeCSC - Cost-sharing contracts