| Media Gas-gas heat exchangers(MGGH)are the key components for achieving ultra-low emission in coal-fired power plants,and their performances have been attracted much attention from scholars.During actual operation,the erosion wear on the tubes of gas cooler is serious,which has an influence on safety and efficiency of power plants.Understanding characteristics of erosion wear in MGGH will help solve those wear problems on heat exchanger tubes in coal-fired power plants and improve the safety and operating efficiency.Firstly,this paper designed and established an erosion wear and heat transfer test device for heat exchangers in power plants based on the similarity theory and modular design theory,and conducted preliminary tests of erosion wear on the device which verified the effectiveness of the test device.The results show that the erosion wear mainly occurs on the windward surface of tubes.The average erosion wear rate of the first row is much greater than that of the other rows,and the average wear rate is constant in the short term.Secondly,combined with the existing data,Ansys Fluent was used to simulate the erosion wear of the tubes in heat exchangers.The wear rate of tubes under high-ash coal ash is 5~ 10 times that of tubes under ordinary coal ash.Finally,the relationships between erosion wear rate and flue gas flow rate,particle concentration and particle size were studied.Combining the existing research on erosion wear,and based on the heat exchanger design theory and engineering cost theory,the cost optimization model of MGGH and the dimensionless cost model of MGGH were built.An actual design of MGGH was optimized,and the cost of this MGGH is theoretically reduced by about 5% after optimization.The dimensionless relationship diagrams under different working conditions were obtained,which can be applied to MGGH engineering design. |
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