Coal-fired gas turbine and ash separation system

Abstract

Application of a coal-fired gas turbine for combined-cycle power generation is discussed. A cycle with staged coal treatment, a counterflow combustor and an aerodynamic ash separation cyclone is chosen and its principal components are investigated. Conditions for self-stabilizing char (solid product of coal gasification) combustion are found experimentally and by numerical simulation. It is shown that the obstacle of sticking ash can be obviated by staged combustion of the char and products of mild coal gasification. Experiments carried out with a coal-fired gas turbine at the Technion Combustion Laboratory are described. The main component making it feasible and reliable is an ash separation device, whose performance is analysed experimentally and computationally. Results indicate that the device suffices for the creation of a dynamically stable protective layer on the turbine blades. Efficiency studies indicate good performance of a metal multicyclone with swirl motion of the aerosol initiated by air jets. Simulation of the two-phase flow within the device, explaining its performance, is discussed.