重油催化裂化装置催化剂跑损原因分析及对策

An Analysis of Causes of Catalyst Loss in RFCCU and Countermeasures

长岭石化1号重油催化裂化装置进行FDFCC-Ⅲ工艺改造后,催化剂消耗量大,表现为催化剂自然跑损增大,故障跑损频繁,二次燃烧严重。从跑损机理入手,对催化剂跑损原因进行分析。装置平衡剂粒径小于20μm的占20.56%,催化剂粉碎动力学速度常数接近0.022,催化剂日周转次数为120次/d,是常规FCC工艺的1.6倍。同时,再生器主风分布管的引出平衡剂口以及两个偏流返回口,全部置于再生器内第Ⅰ、Ⅱ区间,导致分布不均衡;沉降器与再生器同轴布置,使沉降器局部器壁双面磨损,主风分布管受力不均,引起多次支管断裂。对此,实施如下措施:改善催化剂配方,补充重油提升管下料口周围的主风分布管,增加汽油提升管下料口周边分布管,其支管实行缩径增密措施,更新伸入再生器内的沉降器的所有构件,对催化剂总循环量予以控制,降低各路蒸汽用量等。措施实施后,催化剂跑损量由5.99t/d降到3.2t/d,故障引起的催化剂跑损现象基本消除。

Sinopec Changling Company's No.1 residue fluid catalytic cracking unit(RFCCU) had an excessively high consumption of catalyst after an upgrade using the FDFCC-Ⅲ technology.The amount of naturally lost catalyst increased and catalyst loss resulting from unit breakdowns was frequent,coupled with serious secondary combustion.This article analyzes the causes of catalyst loss in the unit.In the poising agent used in the unit,particles with diameters less than 20μm accounted for 20.56%.The catalyst crushing dynamics velocity constant was close to 0.022 and the catalyst turnover number was 120 per day,1.6 times that of conventional FCC technology.In addition,since the poising agent eliciting outlet of the main air distribution pipe of the regenerator and the two deviated flow return inlets were all located in sections Ⅰ and Ⅱ in the regenerator,resulting in an uneven distribution.The coaxial layout of the precipitator and the regenerator resulted in wearing of both sides of part of the regenerator wall,uneven stress on the main air distribution pipe and frequent breakage of branch pipes.To overcome these problems,technicians took measures as follows: improving catalyst formula,replenishing the main air distribution pipe around the feed opening of the residue riser,increasing the number of the air distribution pipes around the feed opening of the gasoline riser,reducing the diameter and increasing density for the branch pipes,replacing all components of the precipitator stretching into the regenerator,controlling the circulation of catalyst,and reducing steam consumption in each line.After these measures were taken,the catalyst loss dropped to 3.2t/d from 5.99t/d and catalyst loss caused by unit breakdowns was basically eliminated.