STUDIES ON FLUID CATALYTIC CRACKING OF HYDROPROCESSED FEEDSTOCKS

Worldwide public concern about environment and increased demand for better quality fuels by automobile industries has necessiated developed countries like USA, UK and Japan to stipulate stringent specifications for petroleum fuel products. Fluid catalytic cracking (FCC) is a major secondary process for fuel products and quality of products coming from FCC unit depends largely on the feedstock used. FCC naphtha makes up for 30-40% gasoline in a typical refinery pool. This FCC naphtha contributes to around 90% of the gasoline pool sulphur. Hence, sulfur and nitrogen reduction have become essential for meeting the quality requirements of fuel products resulting in the growing importance for pretreatment of FCC feedstock. In the present work, studies were carried out in pilot plant on hydrotreatment of feedstock for FCC unit. The results indicate better quality products for treated feedstock vis-a-vis untreated heavy vacuum gas oils from Persian Gulf (PG) crudes. Hydroprocessing of FCC feed has helped refiners in meeting the fuel products quality especially with feedstocks, which are characterized as heavy and refractory in nature.     

高氮原料催化裂化转化研究

采用氧化铝色谱柱及索氏抽提的方式对高氮原料分离富集,利用傅里叶变换离子回旋共振质谱仪及CG-MS对分离所得到的碱性氮化物、非碱性氮化物及稠环芳烃结构进行了分析,结果表明：高氮原料中的碱性氮化物一般包括吖啶、环烷基吖啶、氮杂芘;非碱性氮化物主要为苯并咔唑;稠环芳烃以含有3个环的短侧链芳烃为主。对高氮原料的催化裂化生焦机理进行了分析,提出高氮原料催化裂化转化可以通过预处理-FCC组合工艺（物理改质）及分区转化工艺（化学改质）来实现,通过分区转化工艺可以使高氮原料转化率提高5.84百分点,并可改善产品分布,汽油收率提高6.49百分点。     

流化催化裂化再生器构型的讨论

利用裂化催化剂上的烧碳动力学和化学反应工程学原理,讨论了催化剂再生的影响因素,并通过再生器的烧焦计算,重点讨论了再生温度、过程热效应、催化剂循环和再生器构型的影响。可供催化裂化装置再生器的设计和实际操作参考。     

精细催化裂化工艺研究

开发了以富含多环环烷烃的馏分油为原料,通过精准反应途径控制,多产异丁烷、异戊烷等异构烷烃和二甲苯等轻质芳烃,从而实现原料油组成单一化、反应过程精准化和目标产品定制化的精细催化裂化新工艺（Fine FCC,简称FFCC）。对不同含量的多环环烷烃原料进行催化裂化反应试验研究,结果表明：当原料油中的多环环烷烃质量分数超过55%时,所得异丁烷、异戊烷、二甲苯的产率分别为8.37%、9.87%、6.97%。催化馏分油的单程加氢深度越大,异丁烷等目标产物收率和氢有效利用率越高,氢消耗反而越少,装置能耗也越低。     

改变剂油比对催化裂化工艺的影响

本文叙述了剂油比在催化裂化装置操作中的重要地位，着重论述了改变剂油比对催化裂化反应、反应－再生两器热平衡化及催化剂性能的影响。在实际生产中，适时调整剂油比使装置适应不同性质的原料、生产不同的产品、提高装置的适应弹性，最大程度地发挥装置的作用，提高经济效益具有重大意义。     

催化裂化装置生产异戊烯的模拟计算研究

应用HYSIM模拟软件,对催化裂化(FCC)装置获取碳五馏分的各种方案进行了研究,并对各方案的优缺点进行了评述。仅有一套FCC装置的炼油厂或者同时拥有几套FCC装置但各装置稳定汽油辛烷值接近的炼油厂,推荐采用塔底方案。炼油化工型企业可考虑塔顶方案或侧线方案。     

管式沉降器催化裂化装置的设想

对于分子筛催化裂化工艺而言,沉降器已失去早期作为反应器的作用,蜕变为一个包容旋风分离器和待生催化剂沉降的压力、保温空间.基于催化裂化装置发展历程以及沉降器功能的转变,提出将目前应用的沉降器改造成管式沉降器的设想.该设想将管式沉降器仅作为油气流动的管道,以消除油气滞留的大空间,实现油气和催化剂的快速分离以及油气的快速引出,避免因沉降器大空间存在而产生的问题.     

催化裂化对炼油厂产品结构和产品质量的影响

催化裂化装置是炼油厂最重要的二次加工装置之一。催化裂化装置对炼油厂的产品产率、柴／汽比、汽油和柴油产品质量有重要影响。催化裂化装置还生产大量可以用于生产优质汽油组分的气体原料。     

灵活多效催化裂化工艺汽油提升管反应热的探讨

对灵活多效催化裂化工艺汽油提升管的反应热进行了分析研究，并通过催化碳法和分子膨胀法计算得出，在低温下以降低汽油烯烃为目标时，反应热为20～30kJ／kg；在高温下以多产丙烯和降低汽油烯烃为目标时，反应热为180～200kJ／kg。     

灵活多效催化裂化工艺技术的工业试验

介绍了洛阳石油化工工程公司开发的灵活多效促化裂化工艺的技术特点，该技术在治江石油化工有限责任公司120kt／a双提升管重油催化裂化装置进行的工业试验结果表明，灵活多效催化裂化工艺技术可使重油催化裂化装置的汽油烯烃体积分数降低到20％以下，硫含量也可降低15％—25％，辛烷值可提高l—2个单位，重油催化裂化装置柴汽比提高0．2—0．7，丙烯产率提高3—6个百分点。     

RAX-3000型对二甲苯吸附剂的工业应用

介绍了RAX-3000型吸附剂的物化性能及在某企业的工业应用情况。该企业600 kt/a芳烃联合装置平稳运行5年以上，并在设计负荷的110%原料流量下进行标定，对二甲苯平均纯度为99.8%，平均收率为98.3%，超过了技术合同保证值。生产过程中，水平衡（装置排出的水量与注水量之比）控制在0.8~1.0之间，有利于提高吸附选择性。与参比剂的数据比对表明，RAX-3000型吸附剂在原料适应性、极端工况、吸附容量和压降等方面性能更好。     

INFLUENCE OF FEEDSTOCK COMPOSITION ON THE YIELD OF TOTAL CYCLE OIL IN FLUID CATALYTIC CRACKING

With a view to gaining an insight into the understanding of the factors responsible for the maximization of the total cycle oil (TCO) in the fluid catalytic cracking of the vacuum gas oils (VGOs) including the one from Bombay High (BH), necessitated by a greater demand for the diesel fuel compared to gasoline, in India, studies have been carried out on three different VGOs in a Xytel Auto Mat II unit over two REY based FCC catalysts differing in their zeolite content using a fixed bed reactor. The fact that the yield of CLO (370^°C+) from BH VGO was much higher than would be expected for a predominantly paraffinic feedstock has led to studying the cracking to compositionally different concentrates isolated from BH VGO and the results are discussed.     

INFLUENCE OF FEEDSTOCK COMPOSITION ON THE YIELD OF TOTAL CYCLE OIL IN FLUID CATALYTIC CRACKING

ABSTRACT

With a view to gaining an insight into the understanding of the factors responsible for the maximization of the total cycle oil (TCO) in the fluid catalytic cracking of the vacuum gas oils (VGOs) including the one from Bombay High (BH), necessitated by a greater demand for the diesel fuel compared to gasoline, in India, studies have been carried out on three different VGOs in a Xytel Auto Mat II unit over two REY based FCC catalysts differing in their zeolite content using a fixed bed reactor. The fact that the yield of CLO (370^°C+) from BH VGO was much higher than would be expected for a predominantly paraffinic feedstock has led to studying the cracking to compositionally different concentrates isolated from BH VGO and the results are discussed.     

减少渣油催化裂化装置的结焦

介绍了清江石化有限公司渣油催化裂化装置反应分馏系统提升管进料喷射区、沉降器顶部、大油气管线、分馏塔底等主要结焦部位的结焦情况，分析了结焦的原因，阐述了为防结焦所采取的一些措施及其效果。     

强化直馏石脑油催化裂解过程中链烷烃选择性催化裂解反应研究

在直馏石脑油催化裂解(SNCC)技术开发过程中,发现原料中链烷烃转化率始终难以大幅提高,仅保持在52.58%~77.07%,对低碳烯烃产率存在较明显的限制。本研究采用基于密度泛函理论的分子模拟计算方法,构建了正辛烷、2-甲基庚烷和2,5-二甲基己烷3种直馏石脑油馏分链烷烃模型化合物的催化裂解反应网络,并分别提出了正构烷烃和异构烷烃理想的链反应引发途径和反应方向,发现反应体系中存在的高供氢活性的环烷烃等烃类会通过负氢离子转移反应抑制链烷烃转化,从而导致链烷烃转化率较低。通过引入新型有特定孔道结构的IM-5分子筛催化剂,可有效强化SNCC过程中链烷烃的选择性催化裂解。     

两器两段再生催化裂化装置的改造技术

Stone & Webster公司两器两段再生技术在生产实践中存在着对原料的适应性差,第二再生器温度过高等问题.由洛阳石油化工工程公司开发的成套技术在镇海炼油化工股份有限公司炼油厂1.4 Mt/a重油催化裂化装置的改造中获得了巨大成功.装置加工能力扩大到1.8 Mt/a,催化剂循环量由约1 050 t/h提高到1 400 t/h以上,再生催化剂碳质量含量由0.2%降到约0.02%,大于C3轻产品收率提高1.69个百分点,干气产率下降明显,沉降器仅有少量结焦.装置操作自如,改造后首次开工平稳运行达2年半.该成套技术包括再生系统、反应系统、管路系统优化等,特别适宜在三器并列及沉降器与第一再生器同轴布置的重油催化裂化装置上推广.     

RECENT ADVANCES IN FLUID CATALYTIC CRACKING PROCESS

Fluid Catalytic Cracking (FCC) is one of the processes applied world-wide for upgrading of heavy petroleum cuts by converting them into lighter products in the gasoline, light, and heavy cycle oil ranges. Catalytic cracking process was developed in the early stages of petroleum refining. It started by utilizing chemically treated natural clays as catalysts. In the early 1960s the introduction of zeolite containing catalysts, mainly the wide pore faujasite family (X-and Y-type) has significantly contributed to the yield as well as FCC process design consideration. The overall process performance is strongly dependent the catalyst characteristics. Therefore, FCC catalyst manufacturers and researchers are continuously searching for modified catalyst characteristics (improved thermal and hydrothermal stability, higher Activity and better selectivity for high barrel-octane gasoline production). This research activity resulted in this introduction of several FCC catalyses with enhanced performance to suit the steadily increasing emand for high quality refined FCC products.

The present review is aimed at throwing a light on the FCC process with special emphasis on the recent advances made in the field of catalysts design and its impact on the whole FCC process performance as related to the production of high octane gasoline.     

无沉降器催化裂化装置的设想

对于分子筛催化裂化工艺而言,催化裂化装置沉降器的作用仅是包容旋风分离器和用于待生催化剂的沉降和保温。但沉降器存在的大空间却形成了油气的滞留空间,油气流速低,停留时间长,结果导致反应油气的二次裂化反应,油气中的液滴和催化剂颗粒易于沉积在沉降器器壁上结焦形成焦块。因此,提出了取消沉降器,采用无沉降器催化裂化工艺装置的设想。该设想包括两个方案,第一个方案为：封闭式旋流快分器作为第一级分离器,多个并联PV型旋风分离器作为第二级分离器,旋风分离器的料腿出口阀采用气动V型阀;第二个方案为：带汽提器的旋风分离器作为第一级分离器,多个并联PV型旋风分离器作为第二级分离器,旋风分离器的料腿出口阀采用翼阀。     

催化裂化工艺技术的发展近况

从多掺渣油,生产低碳烯烃,增加产品结构灵活性和新装置构型等方面系统地评述了国内外催化工艺技术近年来的最新进展,指出了增加掺渣比同时生产清洁资料,以及炼油与石油化工一体化的新工艺将是催化裂化近期发展的重点。     

下行床反应器用于催化裂化多种目标产品的优化工艺研究

本研究在一套内径13mm、长1500mm、处理量为1．8kg／h的催化剂连续再生循环下行床反应器中进行。以大庆VGO为原料,使用工业FCC分子筛催化剂,较为系统地研究了顺重力场下的催化裂化过程。通过对较宽范围的剂油比(7—30)和反应温度(490—600℃)等重要操作参数的考察,初步得到了其对下行床催化裂化过程产品分布影响的基本规律,分别得出了适合于生产汽油、柴油和液化气各种目的产品的最优生产方案。