基于颗粒形态分析铬系聚乙烯气相聚合装置结片现象

Analysis of wall fouling in chromium-based polyethylene gas-phase reactor based on investigation of particle morphology

解析聚乙烯在气相聚合过程的颗粒生长和形态演变过程有助于理解气相流化床反应器静电波动和结片现象。已有研究报道了国内聚乙烯气相聚合装置的结片现象和成因,但对冷凝态操作条件下,铬系催化剂体系的聚乙烯颗粒形貌和结片的研究较少。本文通过粒径分析、SEM等表征方法研究了粉料颗粒形态与结片现象的相关性。结果显示,聚乙烯聚合过程随反应温度变化存在形貌劣化,粒径分布变窄的现象,导致反应器静电波动加剧,引发局部热点和结片现象。研究方法和试验结果可为同类装置结片研究提供借鉴意义。

Analyzing the morphology and growth process of polyethylene particle in the gas-phase reactor is crucial for understanding the electrostatic charging and sheeting in fluidized-bed.In fact,existing studies have explored the causes of wall fouling in linear low-density polyethylene,but lack of systematic studies for chromium-based polyethylene installations under condensing conditions.This study aimed to reveal the relationship between wall fouling and morphology of polyethylene particle by size analysis and SEM.The results show a general phenomenon morphology deterioration and particle size variation,triggering the electrostatic charging,local hotspots,and sheeting.The method and results in this paper provide important guides for long period operation of similar devices.