Increase of unit efficiency by improved waste heat recovery

摘要

For coal-fired power plants with flue gas desulfurization by wet scrubbing and desulfurized exhaust gas discharge via cooling tower, a further improvement of new power plant efficiency is possible by exhanust gas heat recovery. The waste heat of exhaust gas is extracted in a flue gas cooler before the wet scrubber and recovered for combustion air and/or feedwater heating by either direct or indirect coupling of heat transfer. Different process configurations for heat recovery system are described and evaluated with regard to net unit improvement. For unite firing bituminous coal an increase of net unit efficiency of 0,25 to 0,7 percentage points and for lignite 0,7 to 1,6 percentage points can be realized depending on the process configurations of the heat recovery systems.