螺杆水蒸气压缩机的MVR系统在碱回收中的应用

Research of MVR system with twin-screw vapor compressor in lye recovery

印染企业采用热泵系统回收碱液能有效降低环境污染,节省能耗。本文针对碱回收热泵系统中水蒸汽压缩机温升小而造成效数不够的问题,提出采用螺杆水蒸汽压缩机替代罗茨式、离心式压缩机构成机械压缩式(MVR)系统。建立了系统各部件的数学模型,首先对系统工况的可行性进行核算,随后在合适的工况条件下计算了不同效数的MVR系统和蒸汽动力压缩式(TVR)系统的热力性能,并比较了各系统回收碱液的经济性。结果表明,在压缩机入口为一个大气压的条件下将质量分数4%的废碱液浓缩到30%不宜采用TVR系统;同时MVR系统的理论COP均高于20,且理论COP及换热器面积随处理效数增加而增加。采用螺杆水蒸汽压缩机构成的三效系统的经济性较其他系统要高,与罗茨机构成的双效系统相比,企业一年即可收回增加的固定成本。在综合考虑压缩机耗功以及设备成本的情况下,印染企业采用螺杆压缩机进行三效处理即可达到较好的节能效果。

Lye recovery using heat pump is beneficial in pollution control and energy saving in the industry of printing and dyeing. This paper investigated mechanical vapor recompression （MVR） system with twin-screw vapor compressor instead of Roots or centrifugal compressor to solve the problem of insufficient number of effects caused by small temperature rise in the lye recovery heat pump system. The mathematical model of every component of the system was built,the feasibility of the system’s operation conditions were evaluated,and the thermal performances of different effects of MVR systems and thermal vapor recompression （TVR） systems were simulated and calculated under the suitable operation conditions,and the economic effects of the two systems were compared. The results showed that the TVR system was not favorable when the waste lye was concentrated from 4%to 30% at 1 atm. In addition,the theoretical COP of each MVR system was over 20, and the theoretical COP and the heat exchange area increased with the increase of number of effects. The economical efficiency of the heat pump system with twin-screw vapor compressor was better than other systems in the waste lye recovery process. Applying three-effect system with twin-screw vapor compressor to lye recovery can achieve better energy saving.