沸腾床渣油加氢裂化装置结焦情况分析与操作优化

Analysis of coking situation and operation optimization of ebullated-bed residue oil hydrocracking unit

分析了沸腾床渣油加氢裂化装置易结焦堵塞的原因,介绍了某炼化公司沸腾床渣油加氢裂化装置易结焦区域和结焦典型症状,从原料、催化剂、反应和分馏工况等方面进行了优化。通过将原料渣油引入脱固油浆减缓结焦,动态调整渣油转化率控制装置结焦:加工中东高硫低氮原油所产渣油时,转化率可控制在75%以上;加工低硫中东原油所产渣油时,转化率控制在不大于70%;加工低硫高氮原油所产渣油时,转化率控制在不大于65%。每吨渣油原料置换新鲜催化剂0.90~0.95 kg,低控减压塔塔底液位(25%~30%),提高塔底物料返混流量以减少沥青质在塔底器壁生焦。优化操作后,常压塔底油总沉积物质量分数稳定小于0.2%,确保了装置在渣油高转化率下的长周期稳定运行。

The article analyzes the reasons for easy coking and blocking in the ebullated-bed residue oil hydrocracking unit.The coking prone areas and typical symptoms of coking in an ebullated-bed residue oil hydrocracking unit of a refinery are introduced.In response to the problem,the optimization is carried out from feedstocks,catalysts,reaction and fractionation conditions and others.Through introducing the purified FCC slurry into the residue oil and dynamically adjusting the residue oil conversion rate to control coking:when processing the residue oil produced from Middle East high sulfur and low nitrogen crude oil,the conversion rate is controlled above 75%;when processing the residue oil produced from Middle East low sulfur crude oil,the conversion rate is controlled at no more than 70%;when processing the residue oil produced from low sulfur and high nitrogen crude oil,the conversion rate is controlled within 65%.The ratio of replacement is controlled at 0.90 to 0.95 kg of fresh catalyst per ton of residue;lower control liquid level(25%~30%)at the bottom of vacuum distillate tower,and increase the flow rate of distillate back to the bottom of the tower to reduce coking of asphalt on the bottom wall of the tower.And then,the sediment mass fraction of the bottom oil of the atmospheric tower is stable at less than 0.2%,ensuring the unit long-term stable operation under high residue oil conversion rate.