原料对煤基LLDPE DFDA-7042质量的影响分析与对策

Effect of feedstock on quality of coal-based LLDPE DFDA-7042 and solutions

研究了某煤基甲醇制烯烃公司300 kt/a气相法聚乙烯装置原料乙烯、1-丁烯和氢气对线型低密度聚乙烯(LLDPE)DFDA-7042质量的影响。研究发现,DFDA-7042密度从0.919 g/cm3提高至0.921 g/cm^3,断裂标称应变从712%降至443%。1-丁烯产量不足需要该装置从DFDA-7042切换至高密度聚乙烯产品,导致产品熔体流动速率、密度、色粒数量,以及蛇皮和拖尾粒数量不合格。2015—2018年,切换牌号产生的过渡料使产品合格品率降低了0.4%。甲醇合成塔弛放气所制氢气供应中断频繁,影响了产品熔体流动速率控制。提出了将聚乙烯装置最高设计产能提高至360 kt/a、采用异构化技术提高1-丁烯产量、增加氢气增压和储存单元等改善产品质量的措施。

The effects of ethylene,1-butene and hydrogen on the quality of linear low density polyethylene DFDA-7042 were observed,which was produced from 300,000 t/a gas-phase polyethylene plant at a coalbased methanol-to-olefin company.The results show that the tensile elongation at break of DFDA-7042 is decreased from 712%to 443%when the density of DFDA-7042 is increased from 0.919 g/cm^3 to 0.921 g/cm^3.The product of the plant was switched from DFDA-7042 to HDPE due to insufficient production of 1-butene,which results in unqualified melt flow rate,density,number of colored particles,snakeskin and trailing particles.The transition material produced from switches lowers the qualified rate by 0.4%from 2015 to 2018.The frequent interruption of hydrogen supply from methanol synthesis tower exhaust affects the MFR control of the product.Solutions are offered to improve product quality,which include increasing the maximum design capacity of polyethylene plant to 360000 t/a,enhancing yield of 1-butene by isomerization technology,adding hydrogen pressurization and storage units.