回收烟气余热的特种耐腐蚀塑料换热器的性能分析

Performance Analysis of Anti-corrosion Heat Exchangers Made of Special Plastics for Flue Gas Heat Recovery

运用特种塑料材料的换热器可以解决烟气余热回收中的低温腐蚀问题,扩大热回收的温度范围。结合1000MW机组烟气余热回收工况,分析了氟塑料管束式换热器和导热塑料翅片管换热器的性能,比较了两者在传热系数、换热面积、换热器体积、流动阻力等方面的差异。尽管氟塑料换热器在传热系数和材料消耗方面具有优势,但翅片管换热器整体体积更小,且管件数量远小于氟塑料换热器。在此基础分析了污垢热阻和材料热导率对翅片管换热器的影响,发现污垢热阻会造成换热器性能20%~30%的变化,材料热导率则需要达到15~20W/（m？K）的阈值,才能实现较好的换热性能。

Heat exchangers made of special plastics can solve the problem of low temperature corrosion in flue gas heat recovery, so that the lower limit of temperature restriction can be eliminated. In this paper, polytetrafluoroethylene （PTFE） tube bundle heat exchanger and fin-tube heat exchanger made of thermally conductive plastic were evaluated under the same work condition of a 1000MW power plant. Parameters including heat transfer coefficient, heat transfer area, heat exchanger volume, pressure drops were compared between the two types of heat exchangers. Although the PTFE tube bundle heat exchanger has higher heat transfer coefficient and consumes relatively less raw material for manufacturing, the fin-tube heat exchanger has smaller volume and much less number of tubes. Based on the comparison, further studies on fouling thermal resistance and material thermal conductivity were carried out for fin-tube heat exchanger. The results show fouling thermal resistance can lead to 20%~30% of performance variation. And the material thermal conductivity need to reach a threshold value of 15~20W/（m？K） to achieve satisfactory heat transfer performance.