优化工艺操作延长双峰聚乙烯生产周期

Process Optimization to Extend Bimodal PE Production Cycle

双峰聚乙烯TUB121 N3000性能优良,具有良好的市场前景。高密度聚乙烯装置双峰生产过程中存在着齐聚物产物比较多、反应器易结皮结垢、溶剂回收系统产生的细粉比较多造成挂壁过滤器堵塞等问题,通过适当提高二反固相浓度至38.0%~38.5%之间,有效地降低了反应器内细粉含量;低压溶剂回收罐压力由680 k Pa提高至720 kPa,减少了闪蒸带粉,延长了滤袋使用周期;钛系双峰开工时优化氢气/乙烯比不超过0.16,减少了齐聚物的生成。停工转产时控制优化温度、CO注入压力、停催化剂后操作控制、异丁烷进料等措施解决了以上问题,提高了生产稳定性,延长了运行时间,减少过渡料产生70 t。

Bimodal Polyethylene TUB121 N3000 has excellent performance and market prospect. But some problems exist in bimodal polyethylene production in the HDPE plant, such as generating more oligomers, fouling in reactor, and clogging in wall filter caused by the fine powder generated in solvent recovery system. Increasing the solid concentration in the second reactor to 38 % - 38.5% can effectively reduce the fine powder in the reactor. Increasing the pressure of the low-pressure recovery tank from 680 kPa to 720 kPa can reduce the power entrainment from the flashing and prolong the service time of filter-bag. Optimizing startup of bimodal polyethylene plant with titanium catalysts and keeping the ratio of hydrogen/ethylene less than 0.16 can curb oligomers generation. Other measures include controlling the optimal temperature in product grade switch, the CO injecting pressure, the iso-butane feeding and etc. All of these measures have addressed the existing problems, improved operation stability and period, and reduced off-spec products by 70 tons.