Service Communautaire d'Information sur la Recherche et le Développement - CORDIS

Improved hot gas cleaning for gasification technologies

Combined cycle turbines can increase the efficiency of power generation by 10% or more compared with conventional power stations, whilst significantly reducing emissions of acid and greenhouse gases. However, advanced power generation technologies based on coal gasification with combined cycles need extensive gas cleaning and efficient particulate removal in order to protect the gas turbine. To maximize thermal efficiency, this cleaning needs to be carried out at elevated temperatures. In order to achieve integrated hot gas cleaning for particulates and acid gas precursor species such as sulphur, nitrogen, or halogen components in fuel gas, the cleaning system must operate at 400-600 C. This is termed the intermediate temperature application. Ceramic candle filter elements may be a promising method for gas cleaning. The main problems associated with these filters in a gasification environment at intermediate temperatures were identified and resolved here.

In combined cycle gasification processes, the fuel gas must be cleaned at high temperatures before being burnt in the gas turbine. Ceramic candle filters can provide effective particulate removal. Here, it was shown that these filters could perform satisfactorily under a gasification environment. The results are already benefiting developments in gasification technology for integrated gasification combined cycle plants fired by coal or biomass.

The collaborators in this project combined expertise from an equipment supplier, a potential end user and university support. Their overall aim was to compile process and engineering information for the application of filtration at intermediate temperature fuel gas conditions at operational scale. The focus was on identifying and resolving the main problems encountered when ceramic filters were used in a gasification environment at intermediate temperatures. This was done by firstly developing an understanding of the mechanisms involved in filtering gasifier dust and the subsequent cyclic cleaning of the filter elements. Next, the filters were assessed to identify their durability and critical mechanical components. Operational and control strategies were agreed upon, and then mathematical models developed to assist in the design and scale up of filters. Finally, the researchers carried out test programmes on hot gas filters operating under conditions representative of high pressure and intermediate temperature gas cleaning.

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.


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