engleski

The recovery of water from flue gas in coal-fired power plants by using fluoroplastic heat exchanger

The coal-fired power plants have a common characteristic for high consumption of coal and water resource. It is significantly valuable that how to realize this technique of deep condensation of water vapor from flue gases after desulfurizer for power plants of water shortage areas. In this paper, the effect of different factors on the overall heat transfer coefficient for fluoroplastic heat exchanger (FHE) is investigated by using the theoretical and experimental method. Based on the lab-scale research, the pilot scale tests for FHE are performed in a 600MW lignite-fired power plant of Inner Mongolia. And then the engineering application of FHE has been realized in a 630 MW coal-fired power plant of Changzhou. The results show that the overall heat transfer coefficient for FHE is calculated using this method considering the convection, conduction and condensation heat transfer, which is agreed well with one obtained by experimental measurements. The heat transfer coefficient for heat exchangers is increased with the thermal conductivity of pipe materials less than 15W/(m·K). But when the pipe material with heat conductivity is greater than 15W/(m·K), enhancing the flue gas velocity is a better approach to increase the heat transfer coefficient. The fluoroplastics are selected as the materials for the heat exchangers, due to the high overall heat transfer coefficient of 190W/(m2·K), good corrosion resistance and abrasion resistance. For the pilot scale tests in a 600MW power plant, it is found that the recovery efficiency of water by installing FHE is gradually increased with an increase in cooling water velocity and a decrease in flue gas velocity. The optimized recovery water region where the flue gas velocity was less than 4.5m/s and the cooling water velocity was larger than 0.22m/s, the recovery efficiency of water was higher than 70%. The recovering yield of water from flue gases obtained by condensation was nearly equivalent for supplemental water from desulfuration system. The recovery water after treatment is well recommended as the supplemental water for desulfurizer, to realize the zero water consumption for desulfuration system in power plants. Based on the results for lab-and pilot-scale tests, the large FHE device has been put into operation in a 630MW coalfired power plant, the recovery efficiency of water is higher than 90% under different power loads.

coal-fired power plants; water recovery; fluoroplastic heat exchanger

nije evidentirano