Title: Pressurised pulverised coal combustion – a coal-based combined-cycle state of the cooperative project: cleaned flue gas matches specifications for use with gas turbines

Authors: Malte E.C. Forster

Addresses: Institute of Heat and Mass Transfer (WSA), RWTH-Aachen, Eilfschornsteinstr. 18, D-52056 Aachen, Germany

Abstract: 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/m³ s.t.p., particle diameters d <<1 µm and the progress in alkali-reduction to a content <0.01 mg/m³ s.t.p. thus meeting gas turbine specifications. Perspectives and possible spin-offs of the technology are deduced.

Keywords: alkali reduction; combined cycle; power generation efficiency; gas turbines; high temperature flue gas cleaning; pressurised coal combustion; pulverised coal combustion; liquid ash particles.

DOI: 10.1504/IJETP.2007.014743

International Journal of Energy Technology and Policy, 2007 Vol.5 No.3, pp.383 - 390

Published online: 06 Aug 2007 *

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