常减压装置工艺防腐运行效果分析.pdf

工程应用石油化工设计Petrochemical Design2023,40(4)14 17常减压装置工艺防腐运行效果分析金洲，苑方伟（中国石油化工股份有限公司镇海炼化分公司，浙江宁波3152 0 7）摘要：阐述了常减压装置的主要腐蚀类型和机理，以及镇海炼化常减压装置“一脱四注”等工艺防腐措施的设计初和操作要求。从装置运行初期原料主要性质，实际操作情况和腐蚀监测结果分析看，各项工艺防腐措施运行平稳有效，腐蚀指标总体正常，满足生产要求。关键词：常减压工艺防腐运行效果doi:10.3969/j.issn.1005-8168.2023.04.004常减压装置作为炼厂的“龙头”装置，是原油加工的第一道工序。原油劣质带来的问题首先反映在常减压装置上，使装置的生产、安全、设备受到严重威胁，对下游装置也会产生不良影响。为解决这一问题,要加强对常减压装置腐蚀与防护措施的管理，从而有效缓解常减压装置的腐蚀，避免出现严重的生产安全事故，确保装置安全、平稳、长周期运行。1常减压装置主要腐蚀类型及机理原油中除存在碳、氢元素外，还存在硫、氮、氧、氯、金属和杂质等，这些元素在原油加工过程中形成了复杂多变的腐蚀环境,对于常减压装置来说,主要包括原油中的盐类、含硫化合物及酸性物质。主要腐蚀类型及机理如下。1.11低温硫化氢腐蚀1-2 原油在加热过程中，硫化物和氯化盐分解出H,S、H C l,随油气到塔顶,经塔顶冷凝器冷却后,遇冷凝水形成强酸性介质,即 H,S-HCI-H,O 的腐蚀体系。该类腐蚀需要水的参与，一般发生在塔顶管道和设备等运行温度12 0 以下的部位，尤其是气液相变的露点部位，酸性最强，腐蚀最为严重。反应如下：Fe+2HClFeCl,+H2Fe+H,SFeS+H2FeS+2HClFeCl,+H,S首先H,S与Fe反应生产FeS,并在设备内表面形成一层硫化亚铁保护膜，但由于HCI的存在形成盐酸，盐酸与硫化亚铁反应还原出H,S和FeCl2,并破坏了保护膜,其中FeCl 溶于水,很容易被冲洗掉，加剧了设备腐蚀。1.2高温硫腐蚀在高温条件下,单质硫、硫化氢、硫醇、硫醚等活性硫与金属直接发生反应生产FeS,或分解出单质硫与金属发生反应。反应如下：H,S+FeFeS+H2S+FeFeSRCH,CH,SH+FeFeS+RCH=CH,+H,尤其当温度高于2 40 时,会促进活性硫与金属发生反应。同时还会促进非活性硫分解为活性硫,导致会腐蚀加剧；当温度达到430 时，腐蚀基本达到顶峰,温度达到48 0 时腐蚀速率开始下降；开始时腐蚀速率较快，但形成硫化亚铁保护膜后,腐蚀反应会随之下降；当腐蚀速率与保护膜脱落速度相同后，便达到平衡状态，腐蚀速率基本保持不变。1.3高温环烷酸腐蚀原油中的酸约9 0%为环烷酸,其在高温下与金属铁或铁锈发生反应，生成环烷酸铁，生成的环收稿日期：2 0 2 3-0 8-2 9。作者简介：金洲，男，2 0 0 8 年毕业于浙江工业大学化学工程与工艺专业，高级工程师，目前主要从事石油加工工艺技术与管理。联系电话：[phone]；E-mail:jinzhou.zhlh 2023年第4期（第40 卷）烷酸铁溶于油中,生成的H,S又继续与金属发生腐蚀反应。反应如下：2RCOOH+FeFe(RCO0)2+H2FeS+2RCOOHFe(RCOO)2+H,S温度在2 2 0 以下时,环烷酸基本不腐蚀。随着温度的升高,腐蚀性逐渐增强,升至2 7 0 280时腐蚀性最强。若温度再升高,环烷酸部分发生气化但未冷凝而液相中环烷酸浓度降低,故腐蚀性又开始下降。当温度达350 左右时,环烷酸气化速度加快，气相浓度增加，腐蚀又加剧，直至40 0 左右时，原油中环烷酸已基本全部气化,对设备的高温部位不再产生腐蚀作用。2装置运行基本情况镇海炼化4号常减压装置设计加工规模为1000万t/a,年操作时间为8 40 0 h，操作弹性70%120%。装置的选材按原油酸值2 mg（K O H)/g,硫含量（w)3.0%设计。装置主要由常压蒸馏单元、减压蒸馏单元、轻烃回收单元、脱硫再生单元组成，于2 0 2 1年9 月2 7 日投料开车一次成功。截止到2 0 2 3年6 月，装置累计加工39 种原油,主要油种有阿曼、冷湖、杰诺等,原油主要性质见表1。表14号常减压装置原油主要性质原油盐含量原油硫含项目(mgL-)最大值198.0最小值2.9平均值27.83工艺防腐措施考虑到装置处理原油的适应性（按高硫高酸考虑），对装置有可能发生低温硫腐蚀和高温硫腐蚀、高温环烷酸腐蚀的设备和管道,采用不同的防腐设计。除设备选材等措施外，装置还设计有电脱盐、注碱、注水、注缓蚀剂和注中和等工艺防腐措施。3.1原油电脱盐原油脱盐是控制腐蚀的关键步骤,通过水洗、破乳和电场脱水后,将原油中的盐类脱除,从根本上降低腐蚀物质含量，降低低温部位的腐蚀，脱后盐含量控制指标为3mg/L。4号常减压装置采金洲等.常减压装置工艺防腐运行效果分析一定的破乳作用。3)操作温度为132 140，弱化环烷酸的乳化性能,乳化膜就越容易被破坏。截止2 0 2 3年6月原油脱后盐含量数据见表2。表2 4号常减压装置原油电脱盐后盐含量数据项目盐含量/（mgL-l）最大值13.10最小值2.00平均值2.10合格率，%99.43由表2 可知：4号常减压装置原油电脱盐合格率达9 9.43%，基本满足生产要求。其中，不合格部分主要是受原料性质影响，破乳剂与原油不匹配，脱盐效果差，经适当调整破乳剂注人量、注水量、混合压差等参数效果有所缓解，如仍有不合格,经调整原油加工比例后盐含量也能达标。3.2原原油注碱常减压装置注碱可有效缓解设备腐蚀情况，注碱的位置设置在电脱盐原油出口处，注碱目的原油酸值/量（w）,%mg(KOH)g-)2.991.350.350.141.680.5515用二级交流高速+一级低速交直流智能响应电脱盐技术，具有以下特点：1)即利用了高速电脱盐投资少、占地面积小的特点，又保持了交直流电脱盐的脱盐、脱水率高，操作弹性大，不同原油适应性强的优势。2)在电场设计上,选择较强的电场设计,具有是将脱后原油中残留的MgCl,、C a C lz 变为不易水解的 NaCl,从而进一步减少 HCl 的生产,以便降低腐蚀。由于原油中含有无机氯和有机氯，而注碱只能处理无机氯,故塔顶含硫污水的Cl-含量无法完全表征注碱效果,注碱量一般根据原油性质确定。4号常减压装置采用4%浓度的NaOH碱液，注人量通常在30 50 mg/L,剩余 Cl-则根据塔顶含硫污水的pH值注中和剂进行调节。3.3注中和剂3为防止塔顶高浓度的酸性液体腐蚀，设计上采取塔顶油气线注中和剂的方式，控制塔顶冷凝液的pH值,减少腐蚀。中和剂类型一般为油溶或水溶性有机胺类,其用量是由塔顶冷凝水的pH值来确定。当pH值 8 时,H,S 的腐蚀作用增强,pH值与腐蚀速率关系如图1所示。.16(e.ww)/率率到石油化工设计应用缓蚀剂可以处理更高酸值的原油。4号常减HCI腐蚀H,S腐蚀2023年第4期（第40 卷）压装置高温缓蚀剂注入点分别为闪底泵入口、常底泵人口、常二中泵入口、减二线泵人口和减三线泵人口等五个部位,注人量分别为1 3mg/L。4防腐效果日常生产中,除采用“一脱四注”的工艺防腐pH值措施控制好各项防腐指标外，腐蚀速率检测也是图1pH值与腐蚀速率关系实际生产作过程中，4号常减压装置采用在线仪表进行检测,2 h分析1次数据，由于加注泵为手动调节和标定，考虑到实际操作,pH值控制在5.5 8.5。操作上根据污水pH值及时调整中和剂注人量，确保塔顶含硫污水pH值在合理范围,减少腐蚀。塔顶含硫污水pH值详细数据见表3。表3塔顶含硫污水pH值统计数据项目最大值最小值平均值合格率，%常顶一级含硫污水pH值7.92常顶二级含硫污水pH值8.88减顶含硫污水pH值9.283.4塔顶注水注水的作用有2 个，一是溶解塔顶管道中生成的氯化铵，以防止其沉积在管道和冷凝器管壁上，从而导致垢下腐蚀、阻力增加和传热速率下降；二是注人适量水后，将介质冷凝点前移,并稀释最初冷凝下来的腐蚀性较强的冷凝液,可减少设备的腐蚀。根据计算,塔顶水蒸汽分压下的饱和温度远低于塔顶温度，故塔顶水蒸气仍处于过热状态，不会冷凝，注水位置选择在塔顶换热器入口。注人量一般为塔顶油气馏出量的5%10%。4号常减压装置采用常压塔顶含硫污水进行回注，常顶注人量为2 0 t/h，减顶注人量为1.5t/h。3.5注缓蚀剂4缓蚀剂的作用是在设备内表面形成一层保护膜,以抑止腐蚀介质对设备的侵蚀。其中低温缓蚀剂分为水溶性和油溶性，注人点为塔顶油气管道注氨点之后，以保护塔顶冷凝冷却系统。4号常减压装置采用油溶性缓蚀剂，常压塔顶注人量为1 3 mg/L,减压塔顶注人量为1 5 mg/L。高温缓蚀剂主要是对抗高温部位的环烷酸腐蚀,可以根据腐蚀部位，灵活注入，合适的选择和重要的监控手段,便于及时发现腐蚀问题。4号常减压装置主要采取2 个主要的监控手段。一是对关键管道的关键部位进行定点测厚,3个月进行1次测量,并进行详细记录和分析。二是分析塔顶含硫污水铁离子含量，它直观地反映了金属被腐蚀情况，一般要求总铁离子含量3mg/L。4.1定点测厚数据选取了常压塔顶油气线、减压塔顶油气线、常底泵出人口管道和减三线泵出入口管道等部位5.936.943.756.574.607.14100.096.7697.52022年3月至2 0 2 3年6 月的测厚数据，计算得出腐蚀速率见表4。表4关键部位管道腐蚀速率序号常顶10.3820.0430.3040.1150.2460.0970.1480.2090.58100.28110.56120.19130.34140.50150.10160.32平均值0.27从表4可看出：所有测量点腐蚀速率全部满足1 mm/a 的指标要求,腐蚀速率最大处在常压塔顶管道上，腐蚀速率为0.58 mm/a。4.2塔顶含硫污水铁离子含量统计了4号常减压装置投产以来的常顶一级含硫污水、常顶二级含硫污水和减顶含硫污水的pH值分析数据,详见表5。mm/a减顶常底油泵0.150.140.050.270.010.160.080.070.050.060.070.090.100.390.060.110.090.220.040.220.02一0.010.010.350.020.080.07减三线泵0.160.260.180.010.000.200.220.13一0.170.112023年第4期（第40 卷）项目常顶一级含硫污水常顶二级含硫污水减顶含硫污水5结语镇海炼化4号常减压装置加工的原油总体性质为高硫、含酸原油，在原始设计选材的基础上，通过做好“一脱四注”等工艺防腐措施，各项防腐指标基本满足生产需求,在降低腐蚀的同时,努力降低各化工原材料消耗。由于当前为投产后的第一个生产周期，设备内部的具体腐蚀情况暂不详，需待大修时进行详细确认和检测。搞好“一脱四注”的工艺防腐是控制常减压装置腐蚀的关键操作,是一项深人细致的工作,除了要有先进的工艺防腐措施和检测技术外，生产管理十分重要。由于加工原油性质的频繁变化,要(上接第 13 页)热后进人下行式固定床一反,新增反应产物与循环氢换热器1台(DFU1300-3.0)。4)氢气回收系统。新增高压循环氢膜分离系统与膜分离提纯气单级压缩机。排放氢经膜分离系统提纯升压后与新氢混合进入上行式反应器，并使其与油混合达到为反应器提供所需氢油比。5)其它设备。泵、容器、塔器、加热炉等其它设备可利旧。若原装置因占地紧张、布置紧凑等原因无法增加膜分离及膜分离压缩机，也可通过提高装置新氢进量达到工艺要求，新增上行式反应器氢油比全部由新氢压缩机提供，废氢直接排至全厂PSA系统。该方案改动量较小，适用于原装置新氢压缩机及全厂PSA装置设计余量较大的情况。3投资估算与经济效益分析装置投资估算如表1所示，总计约16 40 0 万元。改造后的固定床渣油加氢装置操作周期预计可延长56 个月达2 2 2 4个月。因本装置在1个检修周期（4年内）可减少换剂1次，节省催化剂约6 0 0 m。同时，装置处理量可提高至220万t/a,能耗降低3kg标油/t原料油,有利于炼厂经济效益的最大化。金洲等.常减压装置工艺防腐运行效果分析表5常压塔顶和减压塔顶含硫污水pH值统计数据分析项目最大值总铁/（mgL-）)8.9总铁/(mg L-)7.2总铁/(mgL-）6.117，最小值平均值0.21.90.21.40.41.4及时分析、精细调整,甚至要根据原油的变化,实时对各项注剂进行筛选、攻关。只要操作合理，效果将十分显著。参考文献：1寿建祥,陈伟军.常减压蒸馏装置技术手册M.北京：中国石化出版社,2 0 16：2 11-2 18.2李瑞泽.常减压装置腐蚀探究与建议措施C.常减压及延迟焦化技术论文集.北京：中国石化出版社，2 0 17：2 47-2 51.3杨骁，刘全新.加工高酸原油常减压蒸馏装置腐蚀及原因J.石油化工腐蚀与防护,2 0 0 9.2 6:9 0-9 3.4吴起越.加工劣质原油南蒸馏装置的腐蚀分析与防护C常减压及延迟焦化技术论文集.北京：中国石化出版社，2017.6:221-232.表1投资估算项目价格/万元反应器（含内件）12000高压换热器500膜分离600膜分离压缩机1300高压调节阀，管线等其它2000总计164004结语1)前置上行式反应器固定床渣油加氢长周期运行成套技术可实现新建装置的大型化与最大程度的节能。在现有反应器制造能力要求最大内径不超过58 0 0 mm及循环氢压缩机压差不超过4.6MPa的前提下：单系列渣油加氢装置的年处理能力提高至2 8 0 30 0 万t，能耗指标控制在15kg标油/t原料油以内,并能显著延长装置的操作周期，使装置的操作周期达到2 年。2)利用现有渣油加氢装置进行前置上行式反应器固定床渣油加氢长周期运行成套技术改造是可行的，装置改动量较小，改造后装置处理量增大,运行周期延长,经济效益显著。3)本装置虽以2 2 0 万t/a为基础做改造分析，但一般来说,在装置现有反应器不改造、主体设备离心式压缩机不改造的情况下，装置的处理量可高于2 2 0 万t/a。各装置可根据实际运行情况优化确认改造规模。合格率，%96.7597.9498.81ABSTRACTSHEAT TRANSFER EQUATION FITTING AND STRUC-TURAL DESIGN OF NANO AEROGEL THERMAL INSU-LATION MATERIALS1Gao Jiansong,Li Jiuchong,Zhou Tianyu,Zhang Jing-fan,SuYaolun(SINOPEC Engineering（G RO U P)C o.,Ltd.,Luoyang,Henan,471003)Abstract:Nano aerogel thermal insulation material is a newtype of solid material with nano porous structure and thelowest thermal conductivity.The lack of basic heat transferparameters results in large deviation in final thickness,restricting the promotion and application of this material.This paper uses the pipe insulation test device to simulatethe working conditions,and uses nano aerogel thermalinsulation material as the insulation layer.The surface heatflow is measured by the steady-state method,and thethermal conductivity of nano aerogel thermal insulationmaterial at the temperature of tm is calculated by theFourier law,so as to fit the heat transfer equation of nanoaerogel thermal insulation material.And the thickness ofeach layer of the nano aerogel composite insulation structureis calculated by using Excel software combined with thetrial and error method.The composite insulation structureformed by nano aerogel thermal insulation materials andtraditional insulation materials is an optimal way.Amongthem,the“nano aerogel felt plus aluminum silicate needlefelt and the“nano aerogel felt plus calcium silicate hasthe lowest comprehensive cost,and may be used as thepreferred insulation structure for equipment and pipelines.Key words:nano aerogel;thermal insulating material;heattransfer equation;composite insulation structure;preferredREALTIMEIMPROVEMENTALGORITHMNUMERICAL OPTIMIZATION OF CHEMICAL PLANTS5Zhu Qiang(SINOPEC Engineering Incorporation,Bei-jing,100101)Abstract:In this paper,a real time improvement algorithmbased on sensitivity information for numerical optimizationof chemical plants is developed based on the originalreceding horizon optimization algorithm to solve theproblems in the large-scale and nonlinear operationoptimization of chemical plants such as high complexity,difficult convergence and poor real-time performance.Whileovercoming the uncertainty of optimization,this algorithmuses the sensitivity information of nonlinear programmingoptimization result to predict on line the approximateoptimal solution of operation optimization problem in thePETROCHEMICAL DESIGNStarted Publication in 1984.Quarterly.25 Nov.2023 Vol.40 No.4 I:next optimization cycle.Meanwhile,the accuracy of theapproximate optimal solution is further improved bybackground computation and off-line correction,so as toensure that the optimal solution of operation optimizationproblem can be obtained quickly and accurately.Finally,atypical chemical plant is selected as the simulation case andthe optimization computation time is reduced by 64.3%compared with that of the traditional method,whichverifies the validity of the real time improvement algorithm.Key words:chemical plant;numerical optimization;recedinghorizon;real time;sensitivityFIXED-BEDRESIDUE HYDROTREATING TECHNOLOGYFORIMPROVINGRESIDUEPROCESSINGCAPACITYOFREFINERIESL12Li Mingdong,Liu Kairiang,Song Zhibo（SI NO PECEngineeringIncorporation，Be i j i n g,10 0 10 1)Abstract:The fixed-bed residue hydrotreating technologydeveloped by SINOPEC Engineering Incorporation(SEI)isintroduced,and its process flow and characteristics areanalyzed.Taking the modification of the existing 2.o Mt/aconventional fixed-bed residue hydrotreating unit as anexample,the technical scheme,investment estimation andeconomic benefits are introduced.This technology isconducive to the large-scale production of single-trainresidue hydrotreating unit and can significantly prolong theoperation cycle of the unit,achieving significant economicbenefits.Key words:fixed-bed residue hydrotreating;upflow reactor;complete set of technologyOPERATIONAL EFFECT OF PROCESS ANTI-CORRO-FORSION OF ATMOSPHERIC AND VACUUM DISTILLATIONUNITS14Jin Zhou,Yuan Fangwei(SINOPEC Zhenhai Refining&Chemical Company,Ningbo,Zhejiang,315207)Abstract:This article introduces the main types andmechanisms of corrosion in atmospheric and vacuumdistillation units as well as the design intention andoperation requirements of anti-corrosion measures such as*one removal and four injections in the No.4 atmosphericand vacuum distillation unit in Zhenhai Refinery.Theanalysis of the main properties of raw materials during theinitial operation of unit,the actual operating conditions andthe corrosion monitoring results show that various processanti-corrosion measures are implemented smoothly andeffectively,and the corrosion indicators are normal ingeneral,meeting the production requirements.ABSTRACTSKey words:atmospheric and vacuum distillation;processanti-corrosion;operational effectAPPLICATION OF RECUTTING TECHNOLOGY FORSTABILIZEDHEAVY GASOLINE18Wang Hui,Ma Zhiyuan,Yu Aijun,Zhang Peng(CNOOC Zhongjie Petrochemicals Co.,Ltd.,Cangzhou,Hebei,061101)Abstract:Due to the influence of purchased naphtha,thearomatization unit of a company has been operated at a lowload.In order to ensure the safe and efficient operation ofthe unit and improve the economic benefit of the company,a cutting system is to be installed downstream the stabilizerof gasoline hydrodesulfurization unit to cut the intermediatecomponents of heavy gasoline at the bottom of stabilizer andsent them to the aromatization unit.This article focuses onthe calibration data analysis and operation summary of thenew fractionation column after it is put into use.Key words:stabilized heavy gasoline;cutting medium gaso-line;data calibrationDISCUSSION ON LOCAL ANTI FLOATING TREATMENTOFLONGANDNARROWWATERTANKS22Zhang Yuanqi,Du Lei?(1.China Petroleum Jilin Chemi-cal Engineering Co.，Lt d.，Jilin，Jilin，132 0 0 2;2.Changchun Jing yue Programming Construction DesignResearch Institute,Changchun,Jilin,130000)Abstract:For some underground water tanks that adopt theoverall anti floating design by covering the soil weight onthe cantilever plate,the central partition wall is difficult tomeet the local anti floating requirements from time to time.At this time,if the plane size of the water tank is narrowand long and the in-plane stiffness of the centrallongitudinal partition wall is weak,the adverse impactcaused by the insufficient local anti floating will beamplified.This paper discusses such problems based onengineering examples,analyzes their adverse effects indetail，g i v e s r e f e r e n c e t r e a t m e n t m e t h o d s，a n ddemonstrates them through theoretical derivation.Key words:local anti floating;underground water tank;in-plane stiffnessAPPLICATION OF CONDITION MONITORING ANDREMOTE DIAGNOSIS TECHNOLOGY IN COMPRESSORUNITS OF LARGE CHEMICAL FERTILIZER PLANTS26Zhang Xide,Hu Yu,Yang Geng,Lou Weidong,ChaiBoyang（(Pe t r o C h i n a T a r i m Pe t r o c h e mi c a l C o mp a n y,PETROCHEMICAL DESIGNStarted Publication in 1984.Quarterly.25 25 Nov.2023 Vol.40 No.4 II:Korla,Xinjiang,841000)Abstract:The five compressor units of large chemicalfertilizer plant are the core rotating equipment of chemicalfertilizer production.It is important to carry out all weathermonitoring of large compressor units to predict in advancethe potential anomalies and hidden dangers of thecompressor units.BH5oo0 condition monitoring and remotediagnosis system collects the vibration,shaft displacement,rotor key phase,bearing temperature and compressor unitspeed in Bentley 3500.In the server,the spectrum analysisof the compressor unit state parameters is carried outthrough the condition monitoring and diagnosis software,the fault type,fault damage degree and fault location arejudged,the unit faults are compared with database cases,the unit anomalies and hidden dangers are warned inadvance,and remote precision diagnosis is realized byexpert team using Internet technology,so as to changefrom breakdown maintenance to maintenance beforehandand from planned maintenance to predictive maintenance.The vibration of air compressor with water and thevibration caused by rotor imbalance of raw gas compressorturbine are found out quickly by using the spectrum analysisof condition monitoring.Eliminating the hidden dangers inthe bud can fundamentally ensure the safe and long-termoperation of compressor units.Key words:large chemical fertilizer plant;compressor unit;condition monitoring;remote diagnosis;technology;applica-tionOPTIMIZATION OF BUTENE REFINING SCHEME FORPOLYOLEFINPLANTS32Huang Rui(SINOPEC Engineering Incorporation,Bei-jing,100101)Abstract:The impurities in industrial butene such as H,O,CO and O,have great influence on the activity of catalystsin polyolefin plants.Therefore,the butene raw materialmust be refined to remove the excessive H,O,CO,Oz andother impurities before participating in polymerizationreaction.In this paper,the butane refining unit of apolyolefin plant is simulated by Aspen Plus,the refiningprocess is discussed based on the stripper model establishedand the simulation results,and the characteristics andadvantages of two butene refining schemes are introducedand discussed.Appropriate refining sch