LDPE装置二次压缩机中间冷却器结垢原因及预防措施

Preventive Measures and Causes of Fouling on the Intercooler of Secondary Compressor in LDPE Plant

低密度聚乙烯装置的核心设备二次压缩机属于超高压压缩机,该压缩机分为两段压缩,随着运行时间的延长二次压缩机中间冷却器内壁结垢较为严重,影响了压缩机和反应器的正常运行。应用乙烯聚合热力学、动力学、乙烯-聚乙烯相平衡理论,分析了二次压缩机中间冷却器结垢原因。分析结果表明,一定条件下乙烯在压缩机系统发生明显的聚合反应以及高压循环系统分离效果差是中间冷却器结垢的主要原因。采取降低二次压缩机入口温度,添加阻聚剂、抗氧剂降低聚合速度以及提高高压循环系统分离效果等措施可以降低中间冷却器结垢速度。

The secondary compressor is the core equipment of low density polyethylene plant. The hypercompressor is a two stages compressor. As the extension of running, the wall of secondary compressor intercooler was fouled seriously, which affected the normal running of the compressor and reactor. Application of ethylene polymerization of thermodynamics, kinetics, ethylene/polyethylene phase equilibrium theory, the reasons of fouling in secondary compressor intercooler are analyzed. It was showed that the ethylene polymerized obviously in the compressor system and high pressure circulating system separated ineffciency were the main reasons for the fouling of the intercooler. Reducing the inlet temperature of secondary compressor, adding inhibitor and antioxidant, improving the separation effect of high pressure circulating system can lower fouling speed.