Keywords: alkali reduction, combined cycle, power generation efficiency, gas turbines, high temperature flue gas cleaning, pressurised coal combustion, pulverised coal combustion, liquid ash particles
Pressurised pulverised coal combustion ? a coal-based combined-cycle state of the cooperative project: cleaned flue gas matches specifications for use with gas turbines
A high efficiency of 60% in a combined-cycle power plant technology with fuels like gas or light oil is estimated to be achievable. On the other hand existing conventional coal-fired power plants based on steam generation have an efficiency of about 40?45%. A huge potential of improvement in efficiency could be achieved by the implementation of a simple and cost-effective technology: PPCC, a coal-based combined-cycle with combustion of coal at high pressure (up to 20 bar) and temperature (1500?C) with a subsequent efficient ash and alkali removal from the flue gas under pressure at process temperature to use it directly as input for a gas turbine. This process can be considered as the most suitable and straightforward design to utilise hard coal in a combined cycle with an efficiency of ~55% and above. The concept results in a straightforward and robust design at low installation and operating costs. We report the success in removing liquid ash particles to a content of <1 mg/m? s.t.p., particle diameters d <<1 ?m and the progress in alkali-reduction to a content <0.01 mg/m? s.t.p. thus meeting gas turbine specifications. Perspectives and possible spin-offs of the technology are deduced.