焦炉荒煤气显热深度回收热力计算分析

摘要

针对焦炉荒煤气显热回收中受热面布置空间小及受热表面结焦致使热回收难以持续等问题,提出下降管多层膜式壁换热结构,且在热回收低温段采取镍涂层、喷氨等除焦措施,对荒煤气显热进行深度回收.热力计算结果表明:入口流量400 Nm3/h、温度750℃的荒煤气在经过上升管换热器回收部分显热后,再通过下降管热回收装置最终出口平均温度可达301.3℃,突破了由于焦油凝析结焦带来的荒煤气出口温度的限制,下降管换热器可产生1.9 NPa饱和蒸汽174 kg/h,系统总热回收效率高达65％,可实现显热深度回收利用.%In order to solve the problems that there are small space for heating surface and the unsustainable heat recovery because of heating surface coking,existing in the process of coke-oven raw gas of sensible heat recovery,the paper proposes a multi-layer membrane wall heat exchanging structure in downcomer,and it takes some decoking measure in low temperature heat recovery section as well,such as spraying ammonia,nickel coating.The result obtained by thermodynamic calculation shows:the raw gas with inlet flow rate 400 Nm3/h and the temperature 750℃,flowing through the heat exchanger in riser,are recovered partial sensible heat and then passes through the heat recovery device in downcomer,its average temperature at the downcomer outlet reaches 301.3℃,breaking through the limit of the temperature brought by the coal tar of condensation and coking,during the running process,the heat exchanger in downcomer can produce 174 kg/h of 1.9 MPa saturated vapor,the overall efticiency of heat recovery system reaches up to 65％,which can realize the full recovery and utilization for the sensible heat of coke-oven raw gas.