Abstract:

MGGH system cycle water temperature at inlet and outlet determines the logarithm mean temperature difference of the heat exchangers, which affects the heat transfer area of cooling and reheat heat exchanger. At the same time, the materials of cooling heat exchanger and reheat heat exchanger are quite different because of the low temperature corrosion. The difference of materials makes the unit cost of these two heat exchangers varying widely. Therefore, the MGGH system was optimized by considering heat transfer area and material cost factor integrally. The MGGH system was built with the software Aspen plus and simulated numerically. Using the sensitivity analysis of the software, two variables which are the inlet and outlet temperature of cooling heat exchanger circulating water temperature in a power plant are set, to find out the optimal operating parameters. After optimization, the originally designed circulating temperature at outlet increases from 95℃ to 105℃, the required yield of circulating water drops from 619.677t/h to 437.428t/h, the total price of cooling heat exchanger and reheating equipment, reduced by 5.02% , and the total heat transfer area is increased by 1.55%.

Key words:

coalfired power plant, MGGH system, low temperature corrosion, Aspen plus software, simulation optimization