Abstract:

The increase of reactor pressure drop is an important factor affecting the long-term operation of industrial residue hydrotreating unit. Three sets of industrial residue hydrotreating units processing different typical raw materials were selected to analyze the impurity deposition and pore structure changes at different locations of the catalysts after operation. The SEM-EDS Mapping method was used to in situ characterize the impurity deposition distribution of agglomerated catalysts, and the impurity deposition rules were obtained. The rise mechanism of reactor pressure drop was analyzed based on the properties of the raw materials and the operating conditions. The results showed that a large number of metal impurities and carbon deposits were deposited on the catalysts in the front of the reactor during the long period operation, and the pore structure of the catalysts changed significantly. At the same time, a large amount of coke or iron containing scale was deposited in the gap between catalyst particles, causing bed plugging. Ni and V were mainly deposited within the catalyst particles, while Fe and Ca were deposited between catalyst particles or attached to the external surface of the catalysts, and a large amount of coke was filled in the gap of caked catalyst particles. The increase of reactor pressure drop followed two different mechanisms. When the content of Fe and Ca in the raw materials was low, the demetallization catalyst at the lower part of the reactor would be deactivated due to the deposition of metal Ni and V, and thus formed a large amount of coke between catalyst particles, resulting in bed hardening and pressure drop increase. When the content of Fe and Ca in the raw materials was high, a large amount of Fe and Ca would deposit among the guard catalyst particles at the upper part of the bed, which led to reactor blockage and high pressure drop. Therefore, controlling the content of Fe and Ca in the feed should be strictly controlled, and the design and grading of the catalysts should also be optimized to extend the operating time.

Key words: residue hydrotreating, fixed bed, reactor pressure drop, catalyst, deactivation

摘要：

反应器压降升高是影响固定床渣油加氢装置长周期运行的重要因素。选取三套加工不同典型原料的工业渣油加氢装置，分析不同位置不同种类运转后催化剂的杂质沉积和孔结构变化情况，采用扫描电子显微镜-二维元素分析方法对结块催化剂杂质沉积分布进行原位表征，获得渣油加氢装置杂质沉积规律。结合装置原料性质和运行工况，对反应器压降升高机理进行分析。结果表明，长周期运行过程中，前部反应器催化剂大量沉积金属杂质，积炭严重，催化剂孔结构发生显著变化；同时，在催化剂颗粒间隙沉积大量焦炭或含铁垢物，造成床层堵塞。Ni、V主要沉积在催化剂颗粒内部，Fe、Ca则沉积在催化剂颗粒之间或附着在催化剂外表面，结块催化剂颗粒间隙填堵大量焦炭。反应器压降升高遵循两种不同的机理或路径。原料Fe、Ca含量较低时，反应器下部脱金属催化剂因沉积金属Ni、V而失活，进而在催化剂颗粒之间形成大量积炭，导致床层板结、压降上升；原料Fe、Ca含量高时，Fe、Ca在床层上部保护剂颗粒间大量沉积，导致反应器堵塞，压降升高。在严格控制进料Fe、Ca含量的同时，还应针对性优化催化剂及其级配设计，延长运转周期。

关键词: 渣油加氢, 固定床, 反应器压降, 催化剂, 失活