Particulate deposition on candle filters

Abstract

Clean coal technologies employing a combined cycle, such as pressurised fluidised bed combustion and integral gasification combined cycle, offer the potential to generate power from coal at higher thermal efficiencies. However, many of these technologies require a barrier filtration system capable of removing particulate material from the coal-derived fuel- or flue-gas to protect the gas turbine from damage. Ceramic candle filters are generally accepted as the most suitable technology. Continued satisfactory operation of ceramic candle filter units is dependent on satisfactory removal, through periodic back pulsing, of the filter cake that builds up during operation. This study examines, through experimental and computational modelling, the deposition process and the factors that affect the build up of the filter cake of a single filter element in cross-flow and parallel flow. For both flow regimes the validation of the computational study was adequate and a method has been developed for predicting filter cake growth using CFD data.