蒸汽喷射泵穿孔事故分析.pdf

蒸汽喷射泵穿孔事故分析 收稿日期:2004-08-27作者简介:王培红(1972-),男,1995年郑州工学院毕业,工程师,主要从事化工生产和管理。王培红,李开胜(河南濮阳市中原大化集团合成氨厂,河南 濮阳 457000)摘 要:介绍蒸汽喷射泵的腐蚀机理及修复。关键词:蒸汽喷射泵;腐蚀;材质中图分类号:TQ113126+413 文献标识码:A 文章编号:1003-6490(2005)02-0015-020 引 言中原大化合成氨装置脱碳系统采用低热苯菲尔德脱碳流程,其脱碳溶液的再生由加热蒸汽汽提后送到闪蒸槽,再经4台蒸汽喷射泵05A001/2/3/4和蒸汽压缩机(或备用喷射泵05A005)闪蒸完成。4台蒸汽喷射泵05A001/2/3/4和蒸汽压缩机(或备用喷射泵05A005)的运行好坏直接影响到脱碳溶液的再生,制约着生产。1 结构与性能蒸汽喷射泵是利用蒸汽高速流动时静压能与动能相互转换的原理来吸入和输送流体的,即由于动力蒸汽的喷射作用,在壳体内形成一个负压区,将闪蒸汽从闪蒸槽中汽提出来,其流量受可调喷嘴的面积控制,泵体的主要部件材质为C2218,St3518,HII。动力蒸汽是由脱碳系统的气体冷却器提供的0137MPa,150的饱和蒸汽,经由蒸汽接管进入喷射泵的蒸汽腔,在喷针的调节下,从喷嘴喷出,汽提出来的闪蒸汽从下部接管吸入,与动力蒸汽混合后从喷嘴喷出,闪蒸汽中主要成分是H2O,K2CO3,KHCO3,CO2,V5+,活化剂,溶解氧等杂质。05A001的设计性能指标如表1所示。表105A001的设计性能指标项目动力蒸汽闪蒸汽排出混合物成分H2OH2OK2CO3H2OK2CO3流量/kgh-11 1002 2003 300压力/MPa0137010540107温度/1501161272 问题的发现在喷射泵投运1a后,发现05A001入口闪蒸汽压力逐渐升高,开始怀疑蒸汽腔穿孔,停机后将05A001解体检查,发现蒸汽腔外侧正对闪蒸汽入口处,出现严重腐蚀,表面呈山谷状,且05A001穿孔,接着将其余喷射泵解体,也观察到不同程度的腐蚀。3 腐蚀原因探讨311 介质冲刷根据05A001的设计值可计算出闪蒸汽的入口流第31卷第2期2005年6月化工设计通讯Chemical Engineering Design CommunicationsVol131 No12Jun12005 1994-2007 China Academic Journal Electronic Publishing House.All rights reserved.http:/速是19127m/s,该高速介质对蒸汽腔外侧的金属表面形成直接冲刷,必然对金属表面形成极大的危害。312 闪蒸汽的腐蚀K2CO3溶液对碳钢设备具有较强的腐蚀性,为阻止其腐蚀在溶液中加入缓蚀剂V2O5,称之为钒化,但喷射泵系统却得不到这种钒化,尽管闪蒸汽中含有V5+,但由于气流对碳钢表面的强烈冲刷,并不能在金属表面形成稳定的保护膜,同时由于闪蒸汽中携带少量K2CO3,CO2,溶解氧等杂质。在它们的共同作用下,对蒸汽腔外侧正对闪蒸汽入口部位便形成强烈的冲刷腐蚀。溶液对碳钢设备的腐蚀是电化学腐蚀,当设备表面由于碳钢的成分不均匀或存在应力集中以及金属晶粒间存在着微小的缺陷时,都使这种部位间的电子逸出电位不同,此时若设备与电解质溶液接触,在这些部位之间便形成一个个微电池,这样一来就造成了电化学腐蚀,尤其是当溶液中含有CO2时,对碳钢设备的腐蚀就更为严重。因此,当带有较大腐蚀性的闪蒸汽与喷射泵的碳钢表面接触后便形成无数腐蚀微电池,阳极过程可由下式表示:FeFe2+2e(1)在阳极过程中,碳钢表面不断产生活性溶解,腐蚀速度处于阴极控制之下,阴极过程则可由下述两式共同控制:2H+2eH+HH2(2)O2+4H+4e2H2O(3)下面对影响式(2)(3)的因素作一探讨:式(2):表示的氢去极化腐蚀,决定于氢过电位数值的大小,该值的大小与腐蚀速度成反比,05A001蒸汽腔外侧较粗糙的金属表面和较高的溶液温度都导致氢过电位减小,从而提高了腐蚀速度。式(3):为了氧化苯菲尔溶液中的V4+,以利于在碳钢表面形成钝化膜,采用了向溶液中加入微量氧的方法,由于这种方法溶解氧的浓度很小,并且采取了一定的措施,所以对碳钢设备的腐蚀很小,但在闪蒸汽中,溶解氧的浓度却成倍提高,对金属形成了所谓的氧去极化腐蚀,影响这种腐蚀的因素有以下几种:a1 介质流速。闪蒸汽的流速很大,使得氧很容易到达阴极表面。b1K2CO3。由于闪蒸汽中存在这种电解质,提高了溶液的导电率。c1 介质温度。闪蒸汽的温度比较高。这三种因素都提高了腐蚀速度。从05A001至05A005,闪蒸汽的流量和流速依次递减,杂质含量也逐步减少。所以05A001的腐蚀最强烈,并导致穿孔。4 修复措施根据蒸汽喷射泵的工艺条件,其壳体和蒸汽腔均设计为碳钢材质并非理想的选择。由于05A001的蒸汽腔已穿孔,因此采用厚度为5mm的1Cr18Ni9Ti不锈钢板,将蒸汽腔圆柱形外侧整体包覆,满焊,采用A132焊条。其余的喷射泵均采用相同的措施修复。在此后的大修检查中,确认设备的使用状况良好,说明了此修复措施可行。存刊有供信息本刊有自1975年创刊以来的少量过刊及合订本,欢迎有需要者联系订购。联系电话:0731-56039606663458E-mail:hgsjtx 联系人:李金阳化工设计通讯 编辑部61化工设计通讯第31卷 1994-2007 China Academic Journal Electronic Publishing House.All rights reserved.http:/AbstractSummary of Alcohol2copper Base CatalystHyperthermic Reduction ProcessG UO Xin2fa(Nanyang Derun Chemical Co.,Ltd,Neixiang,Henan474350,China)Abstract:This article introduces the hyperthermic reduction pro2cess of alcohol2copper hase catalyst,besides,it points out theitems for attention during hyperthermic reduction1Key words:Copper2base catalyst;hyperthermic reduction;itemsfor attentionModification on G as ProducerTian Jian2an(Henan Yanshi Fertilizer Factory,Yanshi,Henan471900,China)Abstract:This article introduces the technical modification on gasproducer and puts forwards some measures.K ey words:gas producer;diameter expansion;modificationMeasures for Preventing CentrifugalCompressor Rotor from Fouling andAxle Vibration V alue ZncreasingQi Ai2qin(Heihua Group Co.,Ltd,Qiqihaer,Heilongjiang,161041China)Abstract:This article introduces several measures for preventingcentrifugal compressor from fouling.It also describes the runningeffect.Key words:centrifugal compressor;rotor fouling;axle vibrationValue increasing;measureThe analysis of the cause for block2up in thedesulfuration toner and raises some counte measuresQUAN Shi2kuang,JIA Ran2yang(Shandong Hualuhengsheng Chemical Co1,Ltd,Dezhou,shandong253024,China)Abstract:this paper introduces application of tannin desulfurationused in fertilizer plant and analyzes the cause for block2up in thedesulfuration tower and raises some counter measures.Key words:tannin desulfuration;block2up;measuresApplication of Anti2blocking Agent in High2nitrogenCompound Fertilizer(N:25%28%)JI Bao2de(Linquan Chemical Co.,Ltd,Linquan,Anhui236400,China)Abstract:This article introduces the mechanism,application andeffect of anti2block agent in high2nitrogen compound fertilizer(N:25%28%).Key words:anti2block agent;high2nitrogen compoundfertilizer;testPerforation Analysis of Steam Injection PumpWANG Pei2hong,LI Kai2sheng(Henan Puyang Zhongyuan Chemical Group,Puyang,Henan457000,China)Abstract:This article introduces the corrosion mechanism andcountermeasures for steam injection pump.Key words:steam injection pump;corrosion;materialThe Catalyst Steam of a Section ofStoves Burns the Carbon Brief SummaryLI Kai2sheng,WANG Pei2hong(Synthetic ammonia of Dahua Group of Central Plains,Puyang of Henan factory,457000,China)Abstract:Narrate a section of stoves and analyse the carbon rea2son Measure and burning the carbon course after the catalyst analy2ses carbons.Key words:Analyse carbons;Burn carbons;MeasurePrinciple and Application of Wet Electric FilterG UO Qiang(Henan Shenma Group,Pingdingshan467013,China)Abstract:This article introduces the basic principle of wet elec2tric filter on the basisof actual application of DC-8.8 Wet electricfilter,This provides a reference for correct application of wet eletricfilter.Key words:electric filter;charge;displacement;adhension;washingCalculation on H alf2w ater G as Scrubberand Turbogrid Angle2bar TrayLIN Chang2qin,HUANGJie,ZHANG Zhen2ou,ZHANG Xue(Tiangjin Bolong T ower New T echnology Co1,Ltd,Tianjin300193,China)Abstract:This article makes an overall calculation,analysis andcomparison for water feed and theoretical tray number of half2watergas scrubber.It also puts forward new suggestions on angle2bar traystructure and design.K ey words:half2water gas;scrubber;calculation;trayDesign Summary and Expansion Plan for 1.5104t/aExtraction Phosphoric Acid PlantCHEN Min(Hunan Chmical&Pharmaceutical Design Institute,Changsha,Hunan410007,China)Abstract:This article mainly describes the design idea and com2missioning result of two extraction phosphoric acid plants designed byour institute.It also makes a comparison with general2purpose pro2cess flow and raises some suggestions for future development.K ey words:extraction;phosphoric acid;compoundfertilizer;de2signDesign a Product for Renewing orObtaining ASME CredentialsW ANG Jiao2qin(Ningbo Engineering CO.,Ltd.of SINOPEC,Ningbo Zhejiang315207,China)Abstract:This article has introduced how to design a pressure ves2sel in detail according to ASME standard.Introduced design methodsstep by step,such as customer specification,calculation vessel for 1994-2007 China Academic Journal Electronic Publishing House.All rights reserved.http:/