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36 万吨滑油 系统 头式 换热器 设计

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36万吨滑油系统浮头式换热器设计,36,万吨滑油,系统,头式,换热器,设计

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南华大学机械工程学院毕业设计（论文）1 概述11 换热设备在工业中的应用在炼油、化工生产中，绝大多数的工艺过程都有加热、冷却和冷凝的过程，这些过程总称为换热过程。传热过程的进行需要一定的设备来完成，这些使传热过程得以实现的设备就称之为换热设备。据统计，在炼油厂中换热设备的投资占全部工艺设备总投资的3540,因为绝大部分的化学反应或传质传热过程都与热量的变化密切相关，如反应过程中：有的要放热、有的要吸热、要维持反应的连续进行，就必须排除多余的热量或补充所需的热量。工艺过程中某些废热或余热也需要加以回收利用，以降低成本。综上所述，换热设备是炼油、化工生产中不可缺少的重要设备。换热设备在动力、原子能、冶金及食品等其他工业部门也有着广泛的应用。12 换热设备的分类1.2.1 按作用原理或传热方式可分为：（1）直接接触式（2）蓄热式（3）间壁式（4）中间载体式换热器1.2.1.1 直接接触式换热器，如下图所示热流体冷流体热流体冷流体图1.1其传热的效果好，但不能用于发生反应或有影响的流体之间。 蓄热式换热器，如下图所示 冷流体冷流体热流体热流体 图1.2其适用于温度较高的场合，但有交叉污染，温度被动大。1.2.1.3 间壁式换热器，又称表面式换热器利用间壁进行热交换。冷热两种流体隔开，互不接触，热量由热流体通过间壁传递给冷流体。1.2.2 按其工艺用途可分为：冷却器（cooler）、冷凝器（condenser）、加热器（一般不发生相变）（heater）、蒸发器（发生相变）（evaporator）、再沸器（reboiler） 、废热锅炉（waste heat boiler） 。1.2.3 按材料分类：分为金属材料和非金属材料换热器。13 国内外的研究现状上个世纪70年代初发生世界性能源危机，有力地促进了传热强化技术的发展。为了节能降耗，提高工业生产的经济效益，要求开发适用不同工业过程要求的高效能换热设备。因此，几十年来，高效换热器的开发与研究始终是人们关注的课题，国内外先后推出了一系列新型高效换热器。近年来，国内已经进行了大量的强化传热技术的研究，但在新型高效换热器的开发方面与国外差距仍然较大，并且新型高效换热器的实际推广和应用仍非常有限。尚需从事换热器专业的技术人员在制造工艺方面加大力度进行研究，使我国换热器技术从各个方面赶上国际水平，也需要各换热设备使用厂家勇于引进和推广新型高效换热器，为我国的节能事业做出贡献。14设计方案本设计为浮头式换热器，属于管壳式换热器的一种。管壳式换热器具有可靠性高、适用性广等优点，在各工业领域中的到最为广泛的应用。近年来受到其他新型换热器的挑战，但反过来也促进了其自身的发展。在换热器向高参数、大型化的今天，管壳式换热器仍占主要地位。该设计参考的前提是常减压装置中的工艺条件，根据装置工艺条件选择具体的流量、温度、压力等参数。浮头式换热器的主要特点是管束可以从壳体中抽出，便于清洗管间和管内。管束可以在其筒体内自由伸缩，不会产生热应力。但是结构复杂，造价高，制造安装要求高。浮头式换热器是由管箱、筒体、管板、封头、折流板、换热管等零部件组成，根据换热管材料、尺寸、管数、管程压力、管壁温度、管程数以及壳体材料、内径、厚度、壳程压力、温度等条件下确定管板的厚度、折流板的形状、尺寸与数量、折流板的布置情况和确定换热器的结构尺寸。根据已知的工作状况，选定换热器所在的化工工艺过程，从而根据工艺条件，以确定换热器内介质的物性参数；根据工艺结构尺寸结合已知条件，进一步计算换热器结构参数；最后进行换热器核算。2 浮头换热器工艺设计21 设计任务和工艺条件一、已知设计参数:滑油（己烷）流量50m3/h， 进口温度45,出口温度40,冷却水流量54m3/h,进口温度33，管程壳程操作压力为0.45MPa。二、换热器类型 浮头式 22 确定设计方案2.2.1 选择换热器 按要求使用浮头式换热器。2.2.2 流程安排 如下图所示，由于循环冷却水较易结垢，若流速太慢将会加快污垢增长速度，使换热器的流量下降，所以综合考虑，使水走管程，滑油走壳程，且选择逆流的形式。图2.123 确定物性参数2.3.1 计算冷却水出口温度热流量 =qv=8761.95550(45-40)=428145kJ/h其中，定压比热容 kJkg-1K-1 qm 质量流量 kgh-1 流体的密度 kgm3假设冷却水出口温度为35管程流体的定性温度为 t=（3335）/2=34循环冷却水在35的物性参数：密度 =994.3 kg/ 定压比热容 cp=4.174 kJ/(kgK)冷却水的温差 =/m=428145/(4.17454994.3)=2()故假设基本合理，由管式换热器设计中的总传热系数K的经验值取传热系数K=510W/(K)2.3.2 确定定性参数对于一般滑油和水等低粘度流体,其定性温度可取流体进出口温度的平均值，故壳程滑油的定性温度为 T=（4550）/2=42.5 管程流体的定性温度为（即冷却水的温度） t=（3340）/236.5 根据定性温度分别查取管程和壳程流体的有关物性数据，可知：滑油在42.5下的有关物性数据如下 密度 876kg/ 定压比热容 =1.955 kJ/(kgK) 热导率 =0.144W/(mK) 粘度 =0.21pas循环冷却水在34的物性数据： 密度 994.3kg/ 定压比热容 =4.174kJ/(kgK) 热导率 =0.624 W/(mK) 粘度 =0.742Pas24 估算换热面积2.4.1 热流量=8761.95550(50-45)=428145kJ/h=119kw 2.4.2 平均传热温差 先按纯流体计算，由于/t2=(45-35)/(40-33)=10/710000故假设成立，此时普兰特数 =4.96代入数值：=0.023 (25125=6013 W/()2.6.1.3 污垢热阻和管壁热阻 按管壳式热交换器设计手册GB151表F7.1，可取 管外侧污垢热阻 =0.000176K/W 管内侧污垢热阻 =0.0006K/W 管壁热阻按式= 式中 b传热管厚度，m； 管壁热导率，mK/W碳钢在该条件下的热导率为50W/(mK)，所以 0.00004K/W2.6.1.4 传热系数K依式K= ，则 K= =514w/m22.6.1.5 传热面积裕度 依式有 =27.45 改换热器的实际传热面积 3.140.0192.25260=34.9该还热器的面积裕度按式计算有H=27.14，因面积裕度大于1520，故传热面积裕度合适，该换热器能够完成生产任务。262 壁温的核算 因管壁很薄，且管壁热阻很小，故管壁温度可按式计算。由于该换热器用循环水冷却，冬季操作时，循环水的进口温度将会降低。为确保可靠，取循环冷却水进口温度为15，出口温度39计算传热管壁温。另外，由于传热管内侧污垢热阻较大，会使传热管壁温升高，降低了壳体和传热管的壁温之差。但在操作初期，污垢热阻较小，壳体和传热管间壁温差可能较大。计算中，应按最不利的操作条件考虑，因此，取两侧污垢热阻为零来计算传热管壁温。于是，按式式中 热流体的平均温度， 热流体侧的管壁温度， 冷流体的平均温度， 冷流体侧的管壁温度，热流体侧的表面传热系数，W/(K)冷流体侧的表面传热系数，W/(K)式中液体的平均温度分别按式中 热流体进口温度，热流体出口温度， 冷流体进口温度，冷流体出口温度，代入数据得： 34 =42.5=6013 W/(K)=83W/(K)传热管得平均壁温t=34.1壳体壁温，可近似取为壳程流体得平均温度即T=42.5壳体壁温和传热管壁温之差为t=42.5-34.1=8.4该温差较小，实际上可不用浮头式，按题目要求使用浮头式。263 换热器内流体流动阻力的核算2.6.3.1 管程流体阻力 依式 式中 管程总阻力； 单程直管阻力；局部阻力；壳程数；管程数管程结构校正系数，可近似取1.5。=1， =4由25125，传热管的相对粗糙度=0.013，查化工原理莫狄图，得：摩擦因素0.04，流体速度u=1.25m/s，994.3kg/ ，局部阻力系数=3.0，所以=0.04=4660=2330=(4660+2330) 141.5=41944此管程阻力在允许范围内。2.6.3.2 壳程阻力按式计算，由Ns=1，=1.15得：流体流经管束得阻力 由于管束采用正三角形，所以，有： F=0.5， Re=25125f0=0.5Re-0.228=0.233NTC=1.1NT0.5=1.12600.5=17.7=11 （即折流板数）, NT =260（即传热管的总根数） 0.54m/s Po=0.50.23317.7 (11+1) =7197 Pa流体流过折流板缺口得阻力 ， B=0.18m D=0.6m=11 (3.5-) =9279 Pa总阻力：9279719716475 Pa壳程流体的阻力比较适宜。小结换热器主要结构尺寸和计算结果，见如下表：参数管程壳程流率/（/h）5450进出口温度/33/3545/ 40压力/MPa0.50.5定性温度/3442.5密度/(kg/)994.3876定压比热容/kj/(kgk) 4.1741.955粘度/(pas)0.742* 0.21导热率/W/(mk)0.6240.144普兰特数4.963665形 式浮头式台数1壳体内径/mm600壳程数1管径/mm19管子排列/mm管长/mm2250折流板/个11管数目/根260折流板间距180传热面积/34.9材质碳钢管程数4管心距/mm25主要计算结果管程壳程流速/(m/s)1.30.54表面传热系数/W/(K)1546013污垢热阻/(K/W)0.00060.000176阻力/MPa0.0419440.007197热流量/KW119传热温差/K8.42传热系数/W/(K)73.7 裕度/82.63 浮头换热器机械设计31 结构设计3.1.1 椭圆形封头 由于此换热器的设计压力p1.6MPa，使用温度小于350，故封头材料可选用Q235-B， 封头的结构形式常采用椭圆形，查JB/T4737-95，椭圆形封头与圆筒厚度相等，且由GB150-1998 即下表，取其厚度为8mm，表3.1其结构形式如下图： 图3.1公称直径DN/mm曲面高度h1/mm直边高度h2/mm碳钢厚度/mm内表面积A/m2容积V/m36001502580.43740.0353表3.2凸形封头:公称直径DN/mm曲面高度h1/mm直边高度h2/mm碳钢厚度/mm内表面积A/m2容积V/m37001752580.5480.0442表3.33 2 管箱和圆筒由于筒体的直径D=600mm，即500mm=DN /2+(b-4)+c=219/2+(30-4)+50=185.5mm图3.3管箱接管的最小尺寸：（如下图） /2+c=108/2+105+50=209图3.4 其中，图中 DH 补强圈外径 dh 接管外径 C4S，且C30mm S 壁厚 b 管板厚度36 浮头管板及钩圈法兰的结构设计 3.6.1 浮头管板及钩圈法兰尺寸由于换热器内径已确定，故采用标准内径决定浮头管排列外径及结构尺寸。浮头管板外径 =-2b=600-23=594mm 由GB151表14、15知：浮头管板外径与壳体内径间隙，取=3mm，垫片宽度，取=12mm 浮头管板密封面宽度，取=+1.5=13.5mm 浮头法兰和钩圈外直径=+80=680mm浮头法兰和钩圈内直径= -2()600-2(3+12)=570mm外头盖内径, mm螺栓中心圆直径, =(594+680)/2=637mm3.6.2 浮头管板及钩圈法兰结构图3.51一 外头盖侧法兰，2 一 外头盖垫片，3一外头盖法兰 ，4-钩圈6一 排气口或放液口；7一 浮头法兰 , 8一 双头级柱9 - 螺母，10一封头11-球冠形封头 12一分程隔板;13-垫片。14一浮动管板。15-档管,16一换热管37 管法兰按标准GB/T9113.1-2000，则有如下图：表3.5滑油进出口自来水进出口管子直径/mm219108法兰内径/mm221110螺栓孔中心圆直径/mm280170公称直径/mm200100螺栓孔直径/mm2222螺栓孔数量n88法兰外径/mm340210法兰厚度/mm2418密封面d254144密封面f22螺纹规格M16M16其结构如下图：图3.638 布管限定圆3.8.1 尺寸表3.6换热器型式/mm/mm布管限定圆直径/mm固定管板式60085843.8.2 结构图3.7 39 拉杆的直径、数量和尺寸3.9.1 拉杆的结构由于换热管的直径为19mm，常采用拉杆定距管结构，如下：图3.83.9.2拉杆的尺寸 图3.9表3.7拉杆螺纹公称直径/mm数量基本尺寸拉杆直径d/mm/mm/mm/mm1241215502.03.9.3 拉杆孔图3.103.9.4 拉杆的布置 拉杆应尽量均匀布置在管束的外边缘。对于大直径的换热器，在布管区内或靠近折流板缺口处应布置适当数量的拉杆，任何折流板应不少于3个支承点。3.9.5 其他 拉杆数量与直径表查取，本换热器壳体内径为600mm，故其拉杆直径为12拉杆。310 折流板和支持板3.10.1 折流板 该换热器采用单弓形折流板，其流动方式和结构形式如下： 图3.11图3.12弓形折流板圆缺高度为壳体内径得25，则切去得圆缺高度为 H=0.25600=150mm折流板间距B，最小的距离为壳体直径的1/31/2，且不应小于50mm，取B=0.3D，则 B=0.3600=180mm折流板数： =传热管长/折流板间距-1=2250/180-1=11.511块由壳体的公称直径DN=600mm，选取换热管无支撑跨距300mm，查换热器设计手册表1-6-26知： 折流板或支撑板的最小厚度为4mm，取折流板的厚度为6mm。折流板名义外直径=DN4.5=595.5mm，折流板外直径允许偏差 由于此换热器的壳程为单相洁净流体，折流板缺口应水平上下布置，如下图所示：图3.13折流板圆缺面水平装配数量不得少于4个。3.10.2 支撑板一般换热管无支撑跨距小于最大跨距，所以无需设置支撑板，但由于浮头式换热器需设置支持板，此支持板可采用加厚的环板。3.10.3 折流板的布置一般因使管束两端的折流板尽可能靠近壳程进、出口接管，其余折流板等距离布置，靠近管板的折流板与管板间的距离如图所示：图3.14其尺寸按下式计算式中 =dH接管外径c=4S，S为壁厚所以，C=50mm，无防冲板时，可取防冲板长度 =可算出 +c=185.5mm所以 =(185.5+219/2)- (36-4)=263mm折流板切口尺寸 h=0.2600=120mm311 防冲板或导流筒因为水u=3.0m/s，滑油（己烷）： ，所以，管程和壳程都不设防冲板或导流筒。312 支座由鞍座材料Q235-B查JB/T 4712-92，选取B型鞍式支座，其结构及尺寸如下：图3.15图3.16表3.8公称直DN/mm允许载荷Q/KN鞍座高度h/mm底板/mm腹板2/mm600165200550150108筋板/mm垫板/mm螺栓间距弧长e3001208710200636400313 外头盖侧法兰 依工艺条件、壳侧压力、温度及公称直径DN=700mm，按JB4703-92长颈法兰标准选取，并确定各部分尺寸，并画出结构草图及尺寸如下：图3.17表3.9公称直径DN/mmD/mm7008408007657557525010525螺栓规格螺栓数量M2032171412221223314 管箱法兰和管箱侧壳体法兰 依工艺条件，管侧压力和壳侧压力的最大值，以及设计温度和公称直径DN=600mm，按JB4703-92长颈法兰标准选取，并确定各部分尺寸，并画出结构草图，如下图所示：表3.10公称直径DN/mmD/mm6007407006656556524410525螺栓规格螺栓数量M2028171412221223图3.18315 固定端管板 依据所用的管法兰管箱侧法兰的结构尺寸,确定固定端最大外径为D=638mm。316 排气和排液管排气口和排液口直径不小于15mm，设置的位置分别在壳体中的最高点和最低点。由于采用了四管程结构，所以设置应有一定的偏离。排气、排液接管的端部必须与壳体或接管内壁平齐。图3.19317 防短路结构3.17.1 旁路挡板 如下图：表3.11可知：旁路挡板应要2对，其厚度与折流板的厚度相同。其结构如下：图3.203.17.2 挡管挡管为两端堵死的换热管，设置于分程隔板槽背面两管板之间，挡管与换热管的规格相同，可与折流板点焊固定，也可用拉杆（带定距管或不带定距管）代替。挡管应每隔3-4排换热管设置一根，但不应设置在折流板缺口处。挡管伸出第一块及最后一块折流板或支持板的长度应不大于50mm,挡管应与任意一块折流板焊接固定。图3.21318 连接3.18.1 换热管与管板的连接 因无较大震动和间隙可采用强度焊接，且管板与换热管采用焊接连接时，管板的最小厚度应满足结构设计和制造的要求，且不小于12mm。如下图：图3.22表3.12换热管规格：外径壁厚/mm换热管最小伸出长度最小坡口深度l2/mml1/mm1921.523.18.2 管板与壳体、管箱的连接如下所示：图3.23 其中，=28mm 4 换热器的强度校核41 筒体壁厚校核 由工艺设计给定温度42.5，设计压力0.5MPa，选用低合金钢板Q235-B卷制，此材料42.5时的允许应力=113MPa，取焊缝系数=1.0，腐蚀裕度=1mm，则计算厚度 =1.33mm设计厚度 =1.33+1=2.33mm名义厚度 =2.33+1=3.33mm，圆整后，取=4mm有效厚度 =4-1-1=2mm水压试验应力 =1.250.51=0.5625MPa所选材料的屈服应力 =235 MPa水压试验校核=85.2 MPa因为0.9=0.93251=292.5 MPa，T=85.2 MPa292.5，则水压强度满足要求。由于介质非易燃和毒性程度为非极度，且允许由微量泄漏，所以不需进行气密性试验。42 外头盖短节和封头厚度校核 外头盖内径=700mm，其余条件，参数同筒体。短节计算壁厚 =1.55mm短节设计厚度 1.55+1=2.55mm短节名义厚度 =2.55+1=3.55，圆整后，取=6mm, =1.1 满足要求。有效厚度 =6-1-1 =4压力试验应力校核 =49.5MPa则T 0.9=0.93251=292.5 MPa 故，压力实验满足强度要求。由前述可知：外头盖封头选用标准椭圆封头，封头计算厚度S=1.55mm封头设计厚度 1.55+1=2.55mm封头名义厚度 =2.55+1=3.55，圆整后，取=8mm, =1mm，满足要求。有效厚度 =8-1-1=6mm压力试验应力校核 = =33.09 MPa则TA=271.32mm，故，该接管补强的强度足够,不需另设补强圈。 4. 6 固定管板的校核 固定管板厚度设计采用BS法。假设管板厚度 b=30mm总换热管数量 n=260一根管壁金属的截面积为0.785 =106.76 开孔强度消弱系数(4程) =0.5两管板之间换热管有效长度(去掉两管板厚度) L=2158 mm计算系数K= b管板厚度（不包括厚度附加量）D筒体内径则， =22.6 K=4.7按管板简支考虑，根据K值查图4-45、图4-46、图4-47可知，系数=3.3，0.68，=3.5筒体内径截面积 A= 0.7856002=282743mm2管板上管孔所占的总截面积 C=n/4=2601919/4=73680mm2系数 =系数 =260106.76/()=0.132壳程压力 =0.5MPa， 管程压力 0.5MPa当量压差 pa=pspt(1+)=0.50.5(1+0.132)= 0.66MPa管板最大应力 =13.09MPa管子的最大应力 =17.35MPa管板采用16Mn锻 =150MPa换热管采用20号碳素钢 130 MPa=13.09 MPa1.5 =1.5150=225 MPa=-17.35 MPa1.5 =1.5130=195 MPa管板计算厚度满足强度要求。考虑管板双面腐蚀取，分程隔板槽深取4mm，实际管板厚为38mm。 47 浮头管板及钩圈校核 换热管材料 20#，根据GB1501998表43，表F2，表F5可知：设计温度下许用应力 130MPa屈服点 219 MPa弹性模量 190800 MPa管板材料16Mn锻件，根据GB1501998 表F2，表F5可知：设计温度下的许用应力 149.7 MPa弹性模量 202700 MPa许用拉脱力按表1-9-5可知：KN 0.5130=65 MPa浮头式换热器浮头管板的厚度不是由强度决定的，由GB151-1999知：管板厚度 管板设计压力，由于不能保证和在任何情况下都同时作用，故MAX(,)=0.5MPa；=0.5所以， =0.009管板布管区的当量直径 =584mm根据 = 式中，L应为换热管的有效长度，但由于管板厚度尚未计算出，暂时用管子中长来代替进行计算，待管板厚度计算出，再用有效长度核算。L= (管端外伸出长度)4030MPa=0.039=1.078 查图可得到，系数C=0.325，管板计算厚度由得： =17.9mm又由于管板名义厚度不应小于下列三部分之和,即 =MAX(,)+壳程腐蚀裕量 =2mm管程腐蚀裕量 =2mm壳程侧隔板槽深 =0 mm管程侧隔板槽深 =4 mm所以，=17.9+4+2=23.9mm，圆整后，取=28mm钩圈采用B形，材料与浮头管板相同，设计厚度按浮头厚度加16mm，即 =38+16=44mm。48 无折边球封头计算 浮头盖上无折边球形封头的计算，按内压球壳计算, .选用16Mn锻, 在设计条件下其=150，查表GB151-98表46知，封头=500mm，按式计算得：= =3.26mm由于双面腐蚀，取=3 mm，设计厚度取8mm。49 浮头法兰计算 根据GB 151-1999， 计算方式符号如下图设计条件计算压力 设计温度t=42.5法兰材料16Mn 锻许用应力t =150MP设f=85mm, mm螺栓材料 40Cr许用应力t=685 MPa垫片及螺栓计算垫片材料碳钢-石棉缠绕密封b=10mmy=25.0mmM=2.5MPa螺栓直径 23螺栓数量 16Fp=6.28DGbmpc=6.28584102.50.5=45.84KNF=0.785DG2pc=0.78558420.5=133.86KNWa=3.14DGyb=3.145842510=458.44KNF+Fp=402.4KN=操作情况下法兰受力力臂 mm力矩Nmm33.58907.636.5KN=27.5=1003.75-41.67KN=30.5=-1257=266KN=20.66=5495操作状态下法兰总力矩=3131Nm操作状态操作状态的值不应小于两倍球封头厚度取值为58图4.14参考文献1郑津洋、董其伍、桑芝富 主编 过程设备设计2 GB150-1998.钢制压力容器3 GB151-1999.管壳式压力容器4 朱聘冠. 换热器原理及计算.清华大学出版社,19875 钱颂文.换热器设计手册.化学工业出版社,20026 石油和化学工业设备设计手册-标准零部件.全国化工设备设计技术中心站,20037 匡国柱 史启才主编.化工单元过程及设备课程设计.化学工业出版社,20028 秦叔经 叶文邦主编.化工设备设计全书-换热器.化学工业出版社,20039 贺匡国主编.化工容器及设备简明设计手册. 第二版,化学工业出版社, 200210 祁存谦、丁楠、吕树申 编 化工原理11 阮黎祥、曹文辉、林杰编纂.标准零部件.全国化工设备设计技术中心站，20035 翻译5.1 英文原文Shell-and-tube and plate heat exchanger water Comparative Analysis Abstract: Through the closed cycle cooling water system in thewater water heat interchanger shaping, in detail elaborated the shell type and the disc heat interchanger structure performance technology economy compares, provides the reference for the water and water heat interchanger shaping. Keyword: Heat interchanger performance comparison From the domestic power plants have been built, for closed-cycle cooling water system of water heat exchanger two categories. is a shell and tube type heat exchangers, and the other is the plate heat exchanger. Shell heat exchanger is used in the form of heat exchanger in the plant design has been widely used, In some domestic units of the plant imports, the gas-steam combined cycle power plants and nuclear power plants are more used plate heat exchanger. Plate heat exchanger as a compact, light weight, high heat transfer efficiency, and the people are interested in growing. This paper shell - and-tube heat exchanger plate and two kinds of styles, and make selection suggestions1. A plate and shell heat exchanger structure brief (1) Shell type heat interchangerShell-and-tube heat exchanger is the former Marine Room, probation, cylinder, the water room and so on. Control the use of pumped - Bundle, which consists of around tube sheet, Baffled, the stick, distance control, Tube components. Stick with the management board, demolition of the plates using screw connection tube and tube sheet adopted inflation accelerating sealed welding. In the shell side entrance to the control of water on board-equipped to prevent the cooling water washed Tube. In order to reduce the load or to take control of the cylinder friction, with the control on the slide. Room for cleaning up the rubbish, sediment and the blockage of the tubes in the water around the room on the Cover of an inspection hole. To monitor water heat exchanger performance, in the cooling water side (except salt water side) and the cooling water side (of seawater) for the import and export are equipped with a temperature and pressure measurement, There is also supposed to exhaust and interfaces. (2) Plate heat exchanger plate heat exchanger consists of a set of parallel corrugated sheet metal components, Plates in the four corner have access hole, Clamping plate was in connection with an aspect of the fixed plate compactor and activities in the framework of plate and clamping bolts used to be clamping. Connecting with the board of the channel pore right, and with two heat exchange liquid external piping connected Heat plate compactor and activities flag at the top plate bearing beams below it from the bottom of the beams at the position. Plate heat itself is a specific shape surrounded by solid-tight gasket seal to prevent external leakage. and the two heat exchange liquid form by alternating current to flow through another pair of plate heat transfer between the channel. Plates of corrugated not only improves the fluid turbulence, and creating many points of contact to withstand normal operating pressure. Fluid flow, physical properties, the pressure and temperature differential decision of the plate number and size.2 Heat interchangers design conditionsHeat exchanger design of the plant from the start to meet the greatest contribution to the various load operating conditions to take dollars, and leave enough margin to ensure heat exchanger in the maximum load and maximum inlet temperature and the largest Fouling, in the repair cycle, it was to be given the task of cooling. Domestic imported 300 MW coal-fired units as an example. Cooling equipment requirements of the cooling water inlet temperature is less than 37.5 C, from the cooling equipment was heating up over the cooling water temperature is about 42.8 3 Shells types and disc heat interchanger comparison 3.1 Flows the heat transfer design comparison Shell-and-tube heat exchanger tube heat exchanger is an essential component, It tube in a fluid flowing through the tube and another providing heat transfer fluid between the surface. According to both the fluid nature of pipe materials, will be corrosive, low-quality water on the water pipe flow In addition to better water quality brine on the shell side of the tubes, such tubes only used seawater corrosion-resistant titanium tube. Meanwhile more convenient cleaning dirt diameter from the point of view of heat transfer fluid dynamics, given the use of the shell of small diameter tubes can be greater density on the surface, but most fluid in the tubes on the surface dirt layer deposition, In particular, the cooling tube poor water, silt and dirt and sea organisms exist, are likely to be formed on the wall of sediments, will enable heat transfer deterioration regular cleansing becomes necessary, tube cleaning restrictions smallest diameter of about 20 mm, Titanium Tube general, 25 mm, the right to the fluid, formed mainly by dirt wall temperature and velocity impact to be reasonable maintenance cycle, the water inside the tube velocity in two 1961 (as to allow pressure drop requirements). As general use seawater cooling water, the river, prone to causing scaling the shell - and-tube heat exchanger, Water should be equipped concentration of plastic ball cleaning device for cleaning. Plate heat exchanger in the cooling water and cooling water on both sides of the corrugated plate convection, using corrugated chevron Bellows, These corrugated plate heat transfer bias, that is adjacent to the heat plate with the same angle of inclination and direction of the bellows. Cross sectional area along the direction of flow is constant, but due to the changing direction of flow resulting flow shape change, which leads to turbulence. Heat general corrugated plate depth of 3-5 mm, the turbulent flow is about 0.1 1.0 to 1.4 ms Bellows thin plate thickness 0.61 mm and the adjacent cubicle to have many points of contact to withstand normal operating pressure adjacent to the boards opposite direction of the chevron trench, two grooves on the intersection point of contact formation, this can also eliminate vibration, and the promotion of the exchange of heat and turbulence at the same time, eliminate fatigue cracks as a result of the internal leakage. Chevron corrugated plate turbulent higher, high turbulence can play a full role in cleaning, can be particularly effective deposition dirt minimized, but corrugated board more points of contact, when liquid water quality poor, containing suspended solid particles, debris and weeds, etc., because of the narrow gap plate. So to the extent possible, ensure that all particles above 2 mm into the heat exchanger in the past, must strip, If the filter can effectively play a role, it is easy to plug. 3.2 Heat transfer coefficients comparisonShell heat exchanger tube, a horizontal fluid passing through the tube wall and pipe flow of a heat transfer fluid, mutual vertical cross-flow heat transfer coefficient is generally 10003000 w/ (m2.k). Plate heat exchanger, the cooling water side with the side of the cooling water flow uniformity turbulence, the two reverse fluid flow As the ripple effect caused turbulence, resulting in higher heat transfer rate, high resistance to pressure and high shear stress field. This will lead to inhibit heat transfer surface of the dirt formed. Heat transfer coefficient is generally 35005500 w/ (m2.k), which can save heat exchanger heat transfer area. 3. Ends difference comparison Shell-and-tube heat exchanger temperature difference (that is, the cooling water inlet temperature and the cooling water outlet temperature difference) 5 . Plate heat exchanger due to its structural characteristics can be done to the economy as low as 1 C temperature difference. 3.4 Cooling water volume comparisonShell-and-tube heat exchanger general cooling and water cooling water than a 1.22.5:1. Plate heat exchanger, as two kinds of media flow with the same high heat transfer efficiency, Therefore plate heat exchanger can greatly reduce the cooling water, the general cooling water and cooling water than a 0.81.1 : 1, thus reducing pipe valves and pumps installed operating costs3.5 Installments overhauls comparisonPlate heat exchanger is small in size, light weight characteristics, maintenance convenience, without lifting based maintenance facilities, Therefore, the installation occupies less. Plate heat exchanger including the artificial maintenance unit packs will be opened, using water guns and brush cleaning plates and gaskets, check plate gasket and, if necessary, replace the plate and gasket. Plate heat exchanger generally a time to clean, and whether or not the actual needs to be done. When the application of the river, poor water quality, such as cooling water, silt and dirt because of the existence, and the rapid growth of microorganisms have caused pollution and the surface plug danger. Overseas, the application of water for cooling water, cleaning high frequency, the average annual 3.3. Shell-and-tube heat exchanger tube bundle is composed of its own weight is larger volume, maintenance of the pumping required to stay out of control as long distance, it occupies more needed with the necessary lifting overhaul facilities. Shell-and-tube heat exchanger design life-expectancy of 30 years, overhaul cycle four years, when heat exchanger leaked, (probably tubes and tube plate of tube leakage or rupture caused by the leakage) can be used to plug the pipe recovery in a short period of time Minute performance, shell - and-tube heat exchanger allows the blocking of 7% margin. For pipe cleaning may need plastic ball cleaning device for the mechanical cleaning regularly. 4 Heat interchangers in domestic power plant movement situationMy early commissioning of the 300 MW coal-fired units closed cooling water systems are chosen shell - and-tube heat exchanger water. running relatively well. In recent years, because of the continuous advancement of technology, design optimization, shell - and-tube exchangers covers water, Maintenance of large venues in the main shortcomings of the plant layout optimization more prominent, In some circulating water system for secondary cooling water circulation unit, taking into account the water cooling heat exchanger of the relatively good water quality, Impurities less pollution and the small screen structure of continuous improvement, closed cooling water systems also use plate heat exchanger. 5 Conclusion On shell - -tube and plate heat exchanger the comparison may come to the following conclusions : Plate heat exchanger for high heat transfer efficiency, small size, light in weight dismounting, when cooling water better, It is an ideal heat exchanger equipment. But for a large number of cooling water sediment and dirt, such as the presence of water, the filters can not effectively play its role it is easy to plug, resulting in frequent cleansing affect the safe operation of the unit. 译文：管壳式与板式水水换热器的比较分析摘要：通过闭式循环冷却水系统中水水换热器的选型，详细论述了管壳式与板式换热器的结构性能技术经济比较，为水水换热器的选型提供参考。 关键词：换热器 性能 比较 从国内已建发电厂来看，用于闭式循环冷却水系统的水水换热器有两类，一类是管壳热换器，另一类是板式换热器。管壳换热器是常用的换热器形式，在电厂设计中已得到了广泛的应用，而在国内一些进口机组的电厂、燃气蒸汽联合循环电厂和核电站多有采用板式换热器。由于板式换热器紧凑、重量轻、高传热效率，人们对它的兴趣日益增长。本文针对管壳式及板式换热器二种型式进行比较，并提出选型参考意见。1 管壳式及板式换热器结构简介 （1）管壳式换热器 管壳式换热器是由前水室、管束、筒体、后水室等组成。管束采用可抽式管束，它由前后管板、折流板、拉杆、定距管、换热管组成。拉杆与管板、拆流板采用丝扣连接，换热管与管板采用胀接加密封焊。在壳侧水入口处的管束上设置防冲板，以防止被冷却水直接冲刷换热管。为了减少管束装入或抽出筒体时的摩擦力，在管束上设有滑轨。为了检查清理室中垃圾、泥沙及管子的堵塞等，在前后水室端盖上设有检查孔。为了监视水水换热器的运行情况，在被冷却水侧（除盐水侧）及冷却水侧（海水侧）进出口都设置温度和压力测点，此外还设有排气和放水接口等。（2）板式换热器 板式换热器是由一组波纹形的平行金属板构成的，在板片的4个拐角处都有通道孔，板被夹紧在一个侧面附有连接管的固定板和活动压紧板的框架中，并用夹紧螺栓加以夹紧。这些连接管同板上的通道孔对中，并与热交换的两种液体的外部管路相连，传热板和活动压紧板悬挂在顶部承载梁的下面并由底部横梁使其对准定位。 传热板本身是有其有特定形状并被固紧的垫片密封，以防止外部泄漏，并把热交换的两种液体按逆流方式交替地流过另一对传热板之间的通道内。板片上的波纹不但提高流体的湍流程度，并且形成许多接触点，以承受正常的运行压力。流体的流量、物理性质，压降和温度差决定了板片的数目和尺寸。2 换热器设计条件 换热器设计应满足电厂从起动到最大出力时各种负荷下的运行需要，并留有一定的裕量，保证换热器在最大负荷、最高进水温度和最大污垢热阻时，在规定的检修周期内，仍能完成给定的冷却任务。 以国产引进型300 MW燃煤机组为例，各