汽水换热器管束泄漏原因分析及预防措施.pdf

工业技术乙烯工业2 0 2 4,3 6(1)2 4 2 7ETHYLENE INDUSTRY汽水换热器管束泄漏原因分析及预防措施张长松，黄超波，李文婷，杜志奇，雷（中国石油天然气股份有限公司独山子石化分公司，新疆独山子8 3 3 6 9 9）摘要：针对制氢装置出现的汽水波纹管换热器泄漏情况，结合具体操作工况，对换热器管束泄漏原因进行成因分析，根据波纹管在含氯介质环境下腐蚀机理，结合实际检验报告，得出可信的分析结果，且根据原因分析制定相应的具体预防措施。通过换热管改造彻底消除腐蚀隐患，延长换热器运行周期，确保换热器长周期运行。关键词：汽水换热器腐蚀泄漏改进1制氢装置汽水换热器制氢装置汽水换热器UD-0601B于2 0 0 7 年10月安装投用，主要作用是利用蒸汽加热采暖水，期间进行了3 次定期检验,3 次耐压实验，在2 0 1 9年第二次试压时发现换热管束存在泄漏情况，检维修单位对泄漏的管束进行了堵管处理，之后换热器继续处于备用状态，至2 0 2 1 年最近一次试压时发现有更多的换热管束泄漏。经试压检查，发生泄漏的换热管束1 0 4根,第二管程管束泄漏6 5根，单程堵管率达到1 4.3 8%，高于换热器“单程堵管率不大于1 0%”的完好指标。由于泄漏的管束较多,2 0 2 2 年2 月对换热器管束进行更换。为查明换热管束发生泄漏的具体原因，委托设备研究所对换热器管束泄漏进行失效分析。换热管堵管情况见图1.图1 换热器堵管情况示意UD-0601B为备用换热器，正常情况下不进行生产,仅当汽水换热器UD-0601A检维修或出现故障停工时才启用，该换热器于2 0 0 7 年1 0 月投用以来一直处于备用状态，但存在串汽串液现象，主要原因是管程进口的采暖水人口蝶阀及壳程蒸汽人口闸阀均存在泄漏。这2 台阀门自2 0 0 7年安装使用直到2 0 1 9 年才进行更换，更换前几次检维修均发现有串汽串液，管程及壳程均有残余的介质。UD-0601B管程残余介质为串液的采暖水，壳程残余介质为串汽的过热蒸汽，换热管材质0Cr18Ni9,形式为波纹管,规格 32 mm 0.8 mm 3010 mm,其主要参数见表1。表1 汽水换热器UD-0601B主要参数项目壳程换热面积/m195设计压力/MPa1.2设计温度/115工作压力/MPa1.1最高工作温度/95水压试验压力/MPa1.5工作介质采暖水流程数2壳体材料封头材料管板材料换热管材料换热管规格/mm换热管数量/根收稿日期：2 0 2 3-0 1-0 6；修改稿收到日期：2 0 2 4-0 2-1 8。作者简介：张长松，男，1 9 9 4年毕业于西安石油学院化工机械与设备专业，主要从事设备管理工作，高级工程师。管程Q235B16MnR16MnR0Cr18Ni9320.83010(波纹管)9040.42200.351900.56低压蒸汽1第3 6 卷2汽水换热器的检测与分析2.1设备外观检查渗漏部位主要集中在换热管束底部沟槽斜面与管壁结合的部位，该部位为不连续表面，泄漏进管束的介质易于在内壁凝聚。从管束外表面检查可发现腐蚀呈点状或孔状腐蚀，腐蚀部位有橙黄色的腐蚀产物集聚,其余部位表面均附着一层较薄的红褐色铁锈（见图2）。对管束采用渗透检测发现,有腐蚀穿孔和开裂的现象（见图3）。切开换热管束观察缺陷所对应的内表面，发现内表面凹槽凸起两侧有大量不同程度的点蚀坑和连成一片的孔蚀现象（见图4），腐蚀部位有橙黄色腐蚀产物聚集,其余部位表面均附着一层较薄的红褐色铁锈。(a)图2换热管外表面张长松等.汽水换热器管束泄漏原因分析及预防措施铁离子含量/(mg L-I)氯离子含量/(mg L-1）项目试样测试结果17.75 0.23OCr18Ni918.0020.00(GB/T 149762012)2.4金相试验根据GB/T132982015金属显微组织检验方法对检测对象取样并进行金相试验。经分析管束金相组织为奥氏体+栾晶组织（见图5），并伴有裂纹缺陷，裂纹自管束内壁扩展至外壁，裂纹性质为穿晶+极少数沿晶，见图6。(b)25149762012流体输送用不锈钢无缝钢管的要求，具体成分含量见表3。表2 UD-0601B管程出口/壳程出口介质取样对比项目管程出口采暖水壳程出口蒸汽凝液pH值8.10硫化物/(mgL-l)0.0100.873.99表3金属成分含量CrMn0.73 0.172.008.940.00611.001.09w,%Ni8.22 0.278.00 11.00刻孔状图5换热管束金相组织（2 0 0 倍）图3 换热管外表面渗透检测孔蚀点蚀点蚀点蚀点蚀点仙点蚀点蚀图6 换热管束边缘金相组织及裂纹（2 0 0 倍）2.5外观形貌及能谱分析图4换热管内表面2.2介质取样分析对UD-0601B管程及壳程介质进行取样分析,结果如表2 所示。2.3换热器材质分析对管束取样进行材质试验，符合CB/T对管束取样进行扫描电镜分析，从内表面观察发现有大量的点蚀、孔腐形貌（见图7）,并在孔蚀周边部位伴有裂纹缺陷（见图8）。对点蚀、孔蚀及裂纹部位进行多次能谱分析，发现有氯元素存在，氯元素质量百分比在0.0 3 0.0 9,具体元素及质量百分比见表4。26.图7 内表面孔蚀形貌（1 0 0 倍）图8 内表面孔蚀及裂纹缺陷形貌（7 0 倍）表4能谱分析结果项目W,%00.44 0.53Ca0.03 0.07Cr0.11 0.40Fe0.23 0.51C0.65 0.84Si0.050.07N0.00 0.12CI0.03 0.09S0.03 0.05Sh0.08 0.153汽水换热器的泄漏原因分析因管程入口、出口蝶阀泄漏导致采暖水介质不断的渗入，且换热器管束采用波纹管,故在管束表面形成大量的不连续表面，渗入的介质在内壁不连续部位产生集聚形成凝液，随着集聚凝液的不断增多和浓度的增大在局部形成腐蚀介质。取样分析发现管程出口的采暖水内含有氯离子，浓度达到3.9 9 mg/L,随着介质在管束内的凝聚、浓缩,管束内凝液中氯离子的浓度更高。换热器管束为增大介质的换热效率采用波纹管，增大了换热面积，同时产生了大量的不连续加工表面，这些形状不连续的部位相比正常管束存在应力集中，应力水平高于正常圆壁管束。材质为奥氏体不锈钢（0 Cr18Ni9），奥氏体不锈钢对氯离子很敏感，易发生氯离子引起的点蚀，在有应力的情况下易发乙烯工业生氯离子的应力腐蚀开裂。具体表现为管束宏观检查发现的大量点蚀坑及裂纹缺陷；宏观检查发现的裂纹在金相分析实验观察下裂纹缺陷为穿晶裂纹，符合奥氏体不锈钢氯离子应力腐蚀开裂的特征。能谱分析证明了腐蚀产物中大量氯元素的存在。综合以上分析，换热管束发生泄漏失效的原因是换热管束在氯离子腐蚀介质（局部凝液）中同时发生了点蚀及应力腐蚀开裂。具体腐蚀过程是因换热管束采用波纹管，渗人换热管束的采暖水介质在管束内壁产生聚集，形成局部凝液,随着浓度的增大，奥氏体不锈钢管束表面的钝化膜在氯离子的作用下遭到破坏露出基层，金属出现小蚀孔（孔径多在2 0 3 0 m），小蚀孔是亚稳态孔核,成为点腐蚀的活性中心,蚀核继续长大至一定临界尺寸时（一般孔径 3 0 m），金属表面出现宏观可见的蚀孔，此特定点成为孔蚀源。蚀孔一旦形成则加速生长，蚀孔内金属表面处于活态，电位较负，蚀孔外金属表面处于钝态，电位较正，孔内和孔外构成了一个活态一钝态微电偶腐蚀电池，电池具有大阴极小阳极的面积比结构，阳极电流密度很大，蚀孔加深很快：孔内主要发生阳极溶解反应：FeFe2+2e，CrCr3+3e,NiNi2+2e孔外在中性或弱碱性条件下发生的主要反应:1/2 0,+H,0+2e20H-孔内介质相对孔外介质呈滞流状态，溶解的金属阳离子不易向外扩散，溶解氧亦不易扩散进来。由于孔内金属阳离子浓度的增加,带负电的氯离子向孔内迁移以维持电中性，在孔内形成金属氯化物（如FeCl，等）的浓缩溶液，这种富集氯离子的溶液可使孔内金属表面继续维持活性。同时由于氯化物水解等原因，孔内介质酸度增加，使阳极溶解速度进一步加快，加上重力的作用，蚀孔加速向深度方向发展，由管束的内壁向外壁扩展。此时，管束应力较小的部位,孔蚀在深度方向上继续发展，直到管束外壁形成穿孔。而管束应力较大的部位，在应力的作用下，以蚀坑底部的敏感点为裂纹源，发生应力腐蚀开裂。换热管束发生应力腐蚀开裂的裂纹扩展随着点蚀的不断发展第3 6 卷第3 6 卷而扩大，氯离子不断在蚀坑敏感点的聚集，加速点蚀坑不断向纵深方向发展，在应力的作用下，众多点蚀坑的尖端就成为了裂纹扩展源且不断扩展，最终汇集到一起，造成管束在氯离子环境下的应力腐蚀开裂。最终确定汽水换热器UD-0601B管束泄漏失效原因为氯离子引起的点蚀穿孔及应力腐蚀开裂,失效的根原因是采暖水介质中存在氯离子,泄漏进人换热管束的采暖水在结构不连续部位聚集形成腐蚀凝液，换热管束在氯离子腐蚀介质（局部腐蚀凝液）中同时发生了点蚀及应力腐蚀开裂现象。4整改措施1)将原换热管32mm0.8mm3010mm（波纹管）更换为32mm2mm3010mm普通(上接第1 7 页)参考文献：1高云忠，袁琳.急冷水乳化原因分析与预防措施 J.乙烯工业,2 0 0 4,1 6(1):54-56.2吴家伟，林琪，朱俊桦.乙烯装置急冷水乳化的原因及对策 J.乙烯工业,2 0 1 6,2 8(4):5-8.3 于振清.工艺水油含量高的原因分析及处理措施J.乙烯工业,2 0 2 0,3 2(2):1 9-2 3.4卢亚昆，魏月娥.乙烯装置工艺水汽提塔系统换热器结垢原因分析及对策 J.乙烯工业，2 0 1 6,2 8（3）：34-38.5罗艺锋,王锋.工艺水系统堵塞问题研究和处理 J.张长松等.汽水换热器管束泄漏原因分析及预防措施整水质，保证水质合格。5结语针对换热器泄漏失效原因，通过对其管壳程进出口阀门定期检修更换，每年6 月采暖水系统停用后对换热器进出口阀门下线查漏检修，确保阀门能有效隔离。加强水质检测频次，根据分析结果及时调整水质，保证水质合格。经重新核算，将波纹管为普通换热管，确保换热器可长周期运行。0000000000000:0乙烯工业,2 0 1 0,2 2(1):2 3-2 7.6 吕鸿博.苯乙烯装置聚合物的产生与预防措施 J.化工管理,2 0 2 0(2)：1 8 3-1 8 4.7杜鹏,史军军,葱雷，等.抽提蒸馏过程中苯乙烯聚合机理的研究 J.石油炼制与化工,2 0 1 4,45（5）：1 1-15.8杨阳.抽提蒸馏过程中苯乙烯聚合机理研究 J.化工管理,2 0 1 9(2 0):1 9 3 -1 9 4.9谢芳宁，潘勤敏,孙建中，等.苯乙烯本体聚合机理及动力学模型 J.合成橡胶工业,1 9 9 7（1）：57-6 1.27.管。2)将原换热管材质由0 Cr18Ni9更换为2 0 号钢。3对换热器进出口阀门及时查漏检修或更换。4)加强水质检测频次，根据分析结果及时调乙烯在线茂名石化运用超高清旋转超声技术开展管线检测近日，茂名石化利用2.5代超高清旋转超声技术，完成公司石脑油长输管线内检测，初步分析综合数据完整有效，标志着国内长输管线首次实现5.0 mm5.0mm级别精度检测器应用。茂名石化长输管线穿江过河、横跨两市三地，如何实现高精度管内检测、精准 把脉 管道内腐蚀情况，一直以来困扰着运维人员。2.5代超高清旋转超声技术可识别管道内最小3.7 mm4.0mm的缺陷，管道坑蚀、针孔腐蚀等隐患判别能力更强，可实现长输管线风险看得见、摸得着、管得住,对实施针对性、预防性维修具有重要意义。摘自中国石化报2 0 2 4-0 3-0 5ABSTRACTSREVIEW OF SINOPECS ETHYLENE PRODUCTION IN20231Zeng Miaoyang,Zhang Xiaoming,Ma Guofeng,Zhang Wei.Chemical Department of SINOPEC,Beijing,P.C.100728Abstract:The achievement and performance of SINOPEC s ethyleneproduction in 2023 are introduced and analyzed briefly from theaspects of safety and environmental protection,feedstock andoperation optimization,energy saving and consumption reduction,technology research,long-term operation and maintenance,and theobjectives and focus of SINOPECs ethylene production in 2024 areput forward.Key words:SINOPEC;ethylene operation;reviewOVERVIEW OF PETROCHINAS ETHYLENE BUSINESS IN20237Shen Yang,Jiao Lifei,Liu Zhaohui,Liu Xiaozhou.PetroChinaRefining,Chemicals&New materials Company,Beijing,P.C.100007Abstract:This paper summarizes the development of PetroChinasethylene business in 2023,including the ethylene production,ethylene yield,yields of ethylene and propylene,processing lossratio and energy consumption _of its subordinate petrochemicalenterprises,as well as the feedstock optimization,long-termoperation,maintenance,technical modification and technicalmeasures.The_focus of work,concerning long-term optimumoperation of ethylene plants in 2024 is put forward.Key words:PetroChina;ethylene;overviewAPPLICATIONOFDEMULSIFIERAND SCALEINHIBITORINETHYLENEPLANT13Huang Zikun,Wang Zhicheng.SINOPEC-SK(Wuhan)Petrochemi-cal Company Limited,Wuhan,Hubei,P.C.430000Abstract:In recent years,affected by the diversification of rawmaterial to ethylene plant,the emulsification of quench wateroccurred.More and more benzene series remain in the system,leading to serious polymerization in process water system.Thepolymerization of process water not only leads to the blockage ofmultiple heat exchangers in the quench unit,but also may lead tothe shutdown of the quench unit in severe cases,which becomes one.of the main botlenecks for the long-term operation of ethylene plant.A new reagent is used in the quench water system to improve thewater quality and alleviate the emulsification and fouling problems ofthe water system,thus effectively prolonging the operation period ofthe ethylene plant.,Key words:quench water;emulsification;fouling;demulsifer andscale inhibitorCAUSE ANALYSIS AND OPTIMIZATION OF HIGH PRO-PYLENE CONTENTAT BOTTOM OFPROPYLENE RECTI-FICATIONTOWER18Lai Xijiang,Wang Junbin,Zhang Lei,Huang Chaobo,ZhangYanglong.PetroChina Dushanzi Petrochemical Company,Dushanzi,Xinjiang,P.C.833699Abstract:With the increase in the load of propylene rectificationtower in a 220 kt/a ethylene plant,the propylene loss in thecirculating propane at the bottom of tower reached 10%.In order toreduce the propylene loss at the bottom of propylene rectificationtower,Aspen Plus was used to establish a propylene rectificationtower model with the operation data of propylene rectification tower,and the current operation of the propylene rectification tower wasanalyzed and studied.By identifying the deviation points betweenthe simulation data and the actual operating parameters,theoperation of propylene rectification tower was adjusted andoptimized,so as to reduce propylene loss at the bottom of tower,increase propylene production and achieve the purpose of improvingquality and efficiency.Key words:propylene rectification tower;simulation;optimizationCAUSE ANALYSIS OF VIBRATION OF SILENCER ANDPIPELINEAT OUTLET OF RECYCLEGAS COMPRESSORINBUTADIENEUNITAND THE MODIFICATION21Zhang Xiaowei,Feng Min,Sheng Nan,Ju Tao,Jiang Feng.PetroChina Dushanzi Petrochemical Company,Dushanzi,Xinjiang,P.C.833699Abstract:To solve the vibration problem of the silencer and pipelineat the outlet of screw compressor in a chemical company,the gasETHYLENEINDUSTRYStarted Publication in 1989,Quarterly.Mar:2024 Vol.36 No.1 Total 137thpulsation and pipeline vibration of the existing exhaust pipe wasanalyzed,the main causes of the pipeline vibration were identifiedcombined with the measured data of pipeline vibration on site,andsome corresponding modification measures were put forward.Somereasonable vibration elimination measures were taken such asreplacing the silencer with three-chamber impedance compoundsilencer,revamping the exhaust pipe,installing pipe supports andreinforcing the thermocouple branches.After modification,thepressure unevenness at each point inside the exhaust pipe can meetthe requirements of API 619,and the gas pulsation decreased by72%on average.The first-order natural frequency of the exhaustpipe system increased from 4.572 Hz to 8.862 Hz,and the high-order natural frequency was 10%away from the compressorexcitation frequency.The maximum vibration of the silencerdecreased by 64%to 32 mm/s and the maximum vibration of theoutlet pipe decreased by 87.5%to 10 mm/s compared with thosebefore the modification,proving the effectiveness of the modificationmeasures.Key words:screw compressor;silencer;pipeline vibration;mea-sureCAUSE ANALYSIS AND PREVENTIVE MEASURES FORLEAKAGE OF TUBE BUNDLESOF STEAM-WATER HEATEXCHANGERS24Zhang Changsong,Huang Chaobo,Li Wenting,Du Zhiqi,LeiQian.PetroChina Dushanzi Petrochemical Company,Dushanzi,Xin-jiang,P.C.833699Abstract:To solve the leakage of steam-water corrugated-tube heatexchanger in hydrogen plant,the causes of the leakage of heatexchanger tube bundle were analyzed combined with the specificoperating conditions,the analysis results were obtained combinedwith the actual inspection report based on the corrosion mechanismof corrugated tubes in the environment of chlorine-containingmedium,and some specific preventive measures were developedcorrespondingly based on the cause analysis.The corrosion hazardswerecompletely eliminated throughheat exchange tubemodification,the operating cycle of the heat exchanger wasextended,and the long-term operation of the heat exchanger wasensured.Key words:steam-water heat exchanger;corrosion;leakage;improvementCAPACITY EXPANSION SCHEMES OF QUENCH SYSTEMINETHYLENEPLANT28Song Zhiqi,Ma Guomin,Ding Shaohui,Wu Liaosha,Xu Wenming.PetroChina Dushanzi Petrochemical Company,Dushanzi,Xinjiang,P.C.833699Abstract:In 2019,the capacity of a megaton ethylene plant wasexpanded in the overhaul window period,including the installationof an ethane cracking furnace,a viscosity reducing tower system anda toluene extraction system as well as the transformation of relatedsupporting equipment and facilities,so that the capacity reached1.15 million tons per year.This paper analyzes and summarizes theoperation of the ethylene plant after two overhauls in 2015 and 2019respectively,in order to find out the operation bottleneck of quenchsystem and formulate targeted optimization plans.Key words:ethylene plant;quench system;capacity expansion;long period operationAPPLICATION OF CFD TECHNOLOGY IN THE RE-SEARCH ON PIPING LAYOUT FOR RECYCLING DECOK-ING EFFLUENT TO FIREBOX OF LARGE-SCALE CRACK-INGFURNACE33Lin Jiangfeng,Xiao Jia.SINOPEC Engineering Incorporation,Bei-jing,P.C.100101Abstract:Recycling decoking effluent to firebox of cracking furnaceis one of the effective measures to reduce pollutant emissions fromthe cracking furnace,and the piping layout for recycling decokingeffluent to firebox has a significant impact on the decoking effect.This article uses CFD technology to numerically simulate the pipinglayout for recycling decoking effluent to firebox.RNG k-8turbulence model is used for the simulation,and the wall functionStandard Wall Fn is used to correct the near wall flow.Thecalculation results indicate that a reasonable piping layout canensure the even entry of decoking effluent into the firebox without