三元制冷系统轻冷剂流道堵塞问题的分析与对策

Analysis and Solution of Blocking of Light Tertiary Refrigerant Flow Passages in Tertiary Refrigeration System

针对乙烯装置的三元制冷系统在运行中轻冷剂过冷和致冷流道出现堵塞的问题进行分析,提出相应的改进措施。杂物淤积和杂质冻堵是造成流道堵塞的主要原因。改进措施包括:认真清扫设备和管道,在杂质容易淤积的地方可设置备用过滤器;降低三元冷剂的杂质和丙烯物料中水的含量;设置备用冷箱;气体配液吹扫等。还可通过调整操作参数来改善三元制冷系统的运行以弥补流道堵塞造成的致冷效果下降,如降低压缩机吸入压力、加大轻冷剂的用量和增加轻组分配比等。改进措施实施后,三元制冷系统的运行参数基本恢复正常,脱甲烷塔塔顶的乙烯损失降低至0.02%(x)以下。

The freezing and blocking encountered in the flow passages of light tertiary refrigerant（LTR） in the tertiary refrigeration system of an ethylene plant were analyzed,and corresponding solutions were proposed. Solid dirt and some impurities in the mixed refrigerant were the leading causes of the blocking and freezing. The solutions include strictly purging equipments and pipelines,setting spare filters at the position that the dirt easily fill up,reducing impurity content in the tertiary refrigerant（such as H2 O in propylene stream）,adding spare cold-boxes,and sweeping with nitrogen or the mixture of methane and methanol. The refrigeration effect could also be improved by adjusting operating parameters,namely reducing the pressure at compressor inlet,and increasing the flow rate of LTR and lighter component contents in the tertiary refrigerant. The tertiary refrigeration system could run normally by using the measures,and ethylene loss in the overhead stream of demethanizer could be decreased to less than 0.02%（x）.