多組分合成氣強化換熱器殼程傳熱的數值模擬

第42卷第10期熱力發(fā)電Vol 42 No 102013年10月THERMAL POWER GENERATIONOct.2013多組分合成氣強化換熱器殼程傳熱的教值模擬李彥1,2,姜秀民3,任建興12,吳江11.上海電力學(xué)院能源與機械工程學(xué)院,上海2000902.上海發(fā)電環(huán)保工程技術(shù)研究中心,上海2000903.上海交通大學(xué)燃煤污染物減排國家工程實(shí)驗室,上海200240[摘要]采用多孔介質(zhì)模型對 ASPEN軟件設計的高壓多組分合成氣換熱器進(jìn)行了三維數值模擬,分析了不同的幾何結構對殼程流體的傳熱和壓降的影響規律。分析結果表明,采用 ASPEN軟件設計的換熱器具有較妤的流動(dòng)和換熱特性;多孔介質(zhì)模型可用于模擬凈燃氣過(guò)熱器殼程流體的流動(dòng)和換熱;在其它參數不變情況下?lián)Q熱器折流板的圓缺度由20%減至15%對殼程流體的換熱影響不大,但增加了殼程流體的壓降[關(guān)鍵詞]管殼式換熱器;多組分合成氣;多孔介質(zhì);殼程;流速;強化傳熱; ASPEN軟件中圖分類(lèi)號]TK124[文獻標識碼]A[文章編號]10023364(2013)10-0021-05[DOⅠ編號]10.3969/.isn.1002-3364.2013.10.021Numerical simulation on heat transfer enhancement in shellside of multi-component synthetic gas heat exchangerLI Yan. 2, JIANG Xiumin, REN Jianxing, 2, WU Jiang, 21. College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai 200090, Chir2. Shanghai Engineering Research Center of Power Generation Environment Protection, Shanghai 200090, ChinaNational Engineering Laboratory of Coal-fired Pollutants Emission Reduction, School of Mechanical EngineeringShanghai Jiao Tong University, Shanghai 200240, ChinaAbstract: The porous media model was employed to conduct three-dimensional numerical simulation on a high pressure multi-component syngas heat exchanger designed by AsPen software.The effect of different geometric structures on heat transfer and pressure drop of shell side fluidwas investigated. The results showed that, the heat exchanger designed by the asPen softwarehad good flow and heat transfer performance; the temperature distribution of the high pressuremulti-component syngas at shell side obtained by the porous medium model agreed well with thatdesigned by the aspen software; keeping the other parameters as constants and decreasing thesegmental orifice degree of the baffle plate in heat exchanger from 20% to 15% had little effect onheat transfer behavior of the shell side fluid, but the pressure drop was increasedKey words shell and tube heat exchanger; multi-component syngas; porous medium; shell side;flow rate; heat transfer; enhancement; ASPEN收稿日期:2012-10-31基金項目:國家863高技術(shù)基金項目(2007AA05Z247);上海高校青年教師培養資助計劃(sd1008);上海市教委重點(diǎn)學(xué)科(第五期)(J51304);上海發(fā)電環(huán)保工程技術(shù)研究中心項目(1ldz2281700)。作者簡(jiǎn)介:李彥(1978-),女,副教授遼寧丹東人,從事lGCC系統內換熱器強化傳熱及E-mail:yli@shiep.edu.cnTHS中國煤化工CNMHG熱力發(fā)電2013年管殼式換熱器是目前整體煤氣化燃氣蒸汽聯(lián)合1模型建立循環(huán)(IGCC)系統中主要的換熱器形式。近年來(lái),許多學(xué)者研究了換熱器結構與換熱器性能之間的關(guān)高壓多組分合成氣換熱器的結構如圖1所示,系口12。古新等研究了斜向流管殼式換熱器殼程凈燃氣走管程,水走殼程,中間布置有隔板,考慮到的折流柵等結構參數對流體的換熱和流阻的影響規固定板結構的溫差應力過(guò)大,選用管程可拆式U型律,分析了其溫度和速度梯度的協(xié)同程度。Peng管式結構。換熱器屬于雙殼程雙管程結構。Z軸為等設計出一種防短路的折流板結構新型防短路合成氣和水的流動(dòng)方向,Y軸為合成氣和水的進(jìn)出螺旋折流板在原扇形折流板的基礎上將兩側直邊同口方向,該布置方式是根據 ASPEN設計計算結果時(shí)加寬1排或2排管距寬度,相鄰2塊扇形板的直得出的最優(yōu)布置方式。邊以交叉重疊方式連接。該結構有助于正向流動(dòng),防止上游螺旋通道內的流體通過(guò)三角區向下游通道逆向泄漏。趙本華等5研究對比了旋向自交叉轉子、同向轉子的換熱器和光管的傳熱性能,發(fā)現在同等條件下,旋向子交叉轉子的換熱器具有較好的換熱性能。何雅玲等6研究了壓力場(chǎng)和速度場(chǎng)的場(chǎng)協(xié)同效應,得出速度矢量與壓力梯度之間的夾角越大,壓力場(chǎng)與流場(chǎng)的協(xié)同性越好,流動(dòng)產(chǎn)生的壓降越小,流動(dòng)損失越小。董其伍等把周期性和對稱(chēng)性簡(jiǎn)化手段應用于管殼式換熱器數值模擬中,提出了圖1高壓多組分合成氣換熱器結構幾何原型周期段模型和單元流道模型簡(jiǎn)化方法,并Fig 1 Schematic diagram of the high pressure基于整體的對稱(chēng)性,僅取簡(jiǎn)化模型的一半進(jìn)行計算,multicomponent synthetic gas heat exchanger大大降低了計算量。 Hilbert r等通過(guò)改變結構布置來(lái)優(yōu)化傳熱、降低阻力。劉偉等0設計了一種殼側采用多孔介質(zhì)模型的控制方程組 RNG k-e新型的折流桿-擾流葉片組合式換熱器,建立了相應模型進(jìn)行計算。其中經(jīng)驗常數為:C=0.0845,的物理和數學(xué)模型,并對其傳熱與流動(dòng)特性進(jìn)行了=1.42,Ca=1.68,B=0.012,7=4.38,ak=計算模擬,認為該新型換熱器殼程的對流換熱系數=1.39。與折流桿換熱器相當,但流動(dòng)阻力遠小于折流桿換首先給出管側流體溫度的初值,并設其為線(xiàn)性熱器,綜合性能優(yōu)于折流桿換熱器。夏翔鳴等從分布,通過(guò)多孔介質(zhì)模型得到殼程流體的溫度分布,場(chǎng)協(xié)同原理出發(fā),提出了基于場(chǎng)協(xié)同理論的無(wú)因次根據殼程流體的吸熱量等于管程流體的放熱量迭代性能因子來(lái)綜合評價(jià)換熱表面的強化傳熱效果。本計算管側流體溫度直至滿(mǎn)足收斂要求。管程流體文采用多孔介質(zhì)模型對IGCC系統中的凈燃氣過(guò)熱的物性通過(guò) ASPEN PLUS進(jìn)行計算,對于具體的器進(jìn)行模擬,探討了其采用的高壓多組分合成氣換工況其值為常數。熱器的換熱機理,對比分析了不同折流板圓缺度對模擬用簡(jiǎn)化凈燃氣過(guò)熱器的主要幾何和運行參數見(jiàn)表1、表2。合成氣換熱器換熱的影響規律。表1模擬用簡(jiǎn)化凈燃氣過(guò)熱器主要幾何參數Table 1 Main geometric parameters of the simplified clean synthetic gas superheater項目數值項目數值殼體內1300折流板間距/mm30殼體長(cháng)度/mm折流板數殼體進(jìn)出口內徑/mm折流板圓缺度/%管子外徑/mm第1塊折流板距離管板/m管子內徑/mm管子根數2172管間距/mm管子排列方式中國煤化工CNMHGhttp:/www.rlfd.comcnhttp:/rlfd.periodicals.net.cn第10期李彥等多組分合成氣強化換熱器殼程傳熱的數值模擬表2模擬用簡(jiǎn)化凈燃氣過(guò)熱器主要運行參數Table 2 Main operation parameters of the simplifiedclean synthetic gas superheater殼側管側內容項目?jì)热葸M(jìn)口介質(zhì)水進(jìn)口介質(zhì)合成氣進(jìn)口介質(zhì)溫度/℃240進(jìn)口介質(zhì)溫度/C144.1流量/kghi9020流量/kg·h150140工作壓力/MPa10‖出口介質(zhì)溫度/℃160入2計算方法和邊界條件采用 gambit進(jìn)行網(wǎng)格劃分,采用 Fluent6.1進(jìn)圖3換熱器殼程流體速度分布Fig 3 Velocity profile of the shell-side fluid行模擬,多孔度、分布阻力和分布熱源采用用戶(hù)自定義函數耦合進(jìn) Fluent中進(jìn)行計算。采用 SIMPLEC方法求解方程。動(dòng)量、能量方程采用二級差分,壓力方程采用 Standard邊界條件為:給定換熱器進(jìn)口壓力、流量和溫度,其出口速度由質(zhì)量守恒確定,出口壓力和溫度根據局部單向化確定;換熱器外殼采用不可滲透、無(wú)滑移和絕熱條件圖2為換熱器的網(wǎng)格布置。采用782228網(wǎng)格劃分方式對換熱器進(jìn)行計算,其計算誤差約為2%。圖4換熱器殼程流體流線(xiàn)Fig 4 Streamlines of the shell-side fluid圖5為殼程流體在x=0平面的壓力分布(單位:Pa,下同)。由圖5可見(jiàn),換熱器入口處的壓力較高,流體沿流動(dòng)方向壓力逐漸降低,出口處壓力最低。流體進(jìn)、出口大約有26Pa的壓降。沿流體流動(dòng)方向,折流板正向的壓力較大,背側壓力較小圖2網(wǎng)格布置Fig 2 Mesh generation of the clean synthetic gas superheater3結果與討論3.1基準工況計算結果圖3、圖4分別為換熱器殼程流體的速度分布和流線(xiàn)。由圖3可見(jiàn),流體沿著(zhù)換熱器殼體從入口流向出口,折流板處流速較小,相應地增加了流體的停留時(shí)間。由圖4可見(jiàn),換熱器殼程流體的流線(xiàn)較為順暢,基本無(wú)流動(dòng)漩渦。面的壓力外和Fig 5中國煤化CNMHGhttp:www.rlfd.com.cnhttp:/rlfd.periodicalsnet.cn熱力發(fā)電2013年圖6為殼程流體在x=0平面的溫度分布(單位:K,下同)。由圖6可見(jiàn),殼程流體的入口溫度為513K,出口溫度為419K,這與 ASPEN設計計算的出口溫度(417.44K)接近。流體入口處溫度降低較多,換熱較強。圖8折流板圓缺度為15%時(shí)殼程流體速度分布ig. 8 Velocity distribution of the shell-side fluid in heatexchanger with baffle segmental degree of 15%圖6x=0平面的溫度分布入口Fig 6 Temperature distribution of the shell-side fluidin cross section where x=0圖9折流板圓缺度為15%時(shí)殼程流體流線(xiàn)3.2換熱器結構對換熱性能的影響Fig9 Streamlines of the shell-side fluid in heat exchanger圖7為折流板圓缺度為15%時(shí)換熱器的結構。ith baffle segmental degree of 15%圖8、圖9分別為該結構換熱器的殼程流體速度分圖10為折流板圓缺度為15%的換熱器殼程流布和流線(xiàn)。由圖8圖9可見(jiàn),折流板附近的流體流體在x=0平面的壓力分布速較小,出、人口的流體流速較大。由于折流板圓缺度的減小,在增加了流體擾動(dòng)性的同時(shí),折流板之間也產(chǎn)生了大量的漩渦,漩渦處流體的流速較小。流動(dòng)漩渦的存在導致流體在該位置下形成流動(dòng)死區,影響了殼程流體與管程流體之間的換熱。圖10折流板圓缺度為15%時(shí)殼程流體在x=0平面的壓力分布圖7折流板圓缺度為15%時(shí)換熱器結構Fig 10distribution of the shelk-side fluid inFig 7 Structure of the heat exchanger with baffle中國煤化he bafflesegmental degree of 15%CNMHGhttp:/www.rlfd.comcnhttp:/rlfd.periodicals.net.cn第10期李彥等多組分合成氣強化換熱器殼程傳熱的數值模擬比較圖5、圖10發(fā)現,折流板的圓缺度從20%減至板的圓缺度,相應增加了殼程流體的壓降,但對殼程15%后,殼程流體的入口壓力從2.66Pa增至流體的換熱影響不大。26Pa,殼程流體的壓降從26Pa增至38Pa,符合減少折流板圓缺度流體的壓降增加的規律。流體流向[參考文獻]折流板側壓力較高,背流側壓力較低[1]江澤民.對中國能源問(wèn)題的思考[J].上海交通大學(xué)學(xué)圖11為折流板圓缺度為15%的換熱器殼程流報,2008,42(3):345-359體在x=0平面的溫度分布。比較圖6、圖11發(fā)現JIANG Zemin. Reflections on energy issues in折流板的圓缺度從20%減至15%后,殼程流體的出[J]. Journal of Shanghai Jiaotong University42(3):345-359.口溫度基本不變?？梢?jiàn),減少折流板的圓缺度對殼[2]焦樹(shù)建整體煤氣化燃氣蒸汽聯(lián)合循環(huán)[M].北京:中程流體的換熱影響不大,但可增加殼程流體的壓降國電力出版社,1996JIAO Shujian. Integrated gasification combined cycle[M]. Beijing China Electric Power Press. 1996(in Chi[3]古新,董其伍,劉敏珊等導向型折流柵強化換熱器殼程傳熱的數值模擬[冂].核動(dòng)力工程,2010,31(2):113117GU Xin, DONG Qiwu, LIU Minshan, et al. Numericalsimulation on heat transfer enhancement in shell side ofer with lebaffles[J]. Nuclear Power Engineering, 2010, 31(2):113-117[4] Zhang C, Xie G N, Luo L Q, et al. Astudy of shell- and-tube heat exchanges with continu-ous helical baffles [J]. Technical Briefs. 2007, 1291426-1431圖11折流板圓缺度為15%時(shí)殼程流體在x=0平面的[5]趙本華,何雪濤,閻華等換熱管內旋向自交又轉子強溫度分布化傳熱性能研究[].熱能動(dòng)力工程,2012,27(3):307Fig. 11 Temperature distribution of the shellside fluidin cross section where x=0 with the baffleZHAO Benhua, HE Xuetao, YAN Hua, et al. Study ofsegmental degree of 15%the intensified heat transfer performance of a heat exhanger tube inner rotation direction self-cross rotor4結論[J]. Journal of Engineering for Thermal Energy and采用多孔介質(zhì)模型以及分布阻力、分布熱源關(guān)Power,2012,27(3):307-311系式,對高壓多組分合成氣換熱器殼程流體的流動(dòng)6]何雅玲,雷勇剛,田麗享等高效低阻強化換熱技術(shù)的和傳熱進(jìn)行了三維數值模擬,并分析了折流板的圓三場(chǎng)協(xié)同性探討[J.工程熱物理學(xué)報,2009,30(11)1904-1906缺度對換熱器換熱性能的影響結果表明HE Yaling, LEI Yonggang, TIAN Liting, et al. An a-(1)采用 ASPEN軟件設計的換熱器具有較好alysis of three-field synergy on heat transfer augmen的流動(dòng)和換熱特性。tation with low penalty of pressure drop[J]. Journal of(2)采用多孔介質(zhì)模型模擬得到的凈燃氣過(guò)熱2009,30(11):1904-1906器殼程流體的溫度分布與采用 ASPEN軟件的設計[7 Dong Q W, Liu m s, Zhao XD. Research on the char-結果相近,說(shuō)明多孔介質(zhì)模型可用于模擬凈燃氣過(guò)acteristic of shellside support structures of heat ex熱器殼程流體的流動(dòng)和換熱。changer with longitudinal flow of shellside fluid[J](3)對于本文給定的運行條件和參數,減少折流IASME Transactions, 2005,8(2): 1491-1498中國煤化工轉第31頁(yè))CNMHGhttp://www.rlfd.comcnhttp:/rlfd.periodicalsnet.cns 10 #y LI Yan et al Numerical simulation on heat transfer enhancement in shell side of multi-component synthetic gas heat exchangerteristicschanger tube inner rotation direction self-cross rotor(2)Temperature distribution of the shell-side[J]. Journal of Engineering for Thermal Energy andfluid in clean synthetic gas superheater which wasPower,2012,27(3):307-311simulated by the porous medium model was similar[6] HE Yaling, LEI Yonggang, TIAN Liting, et al. An analysis of three-field synergy on heat transfer augerto that designed by the ASPEN software, demontation with low penalty of pressure drop[]. Journal ofstrating that the porous medium model can be usedEngineering Thermophysics, 2009, 30(11): 1904-to simulate the flow and heat transfer of the shell-1906side fluid in clean synthetic gas superheat[7] Dong Q W, Liu M S, Zhao X D. Research on the char-(3)For the given operation conditions and paacteristic of shellside support structures of heat ex-rameters in this study, the pressure drop of thchanger with longitudinal flow of shellside fluid[J].shell-side fluid increased when decreasing the baf-IASME Transactions, 2005,8(2): 1491-1498tal degree[8] WU Jinxing, DONG Qiwu, LIU Minshan, et al. Numer-ical simulation on the turbulent flow and heat transferReferencesin the shell side of the rod baffle heat exchanger[J][1] JIANG Zemin. Reflections on energy issues in ChinaJournal of Chemical Engineering of Chinese Universi[T. Journal of Shanghai Jiaotong University, 2008, 42ties,2006,20(2):213-216(3):345-359[9] Hilbert R, Janiga G, Baron R, et al. Multi-objective[2] JIAO Shujian Integrated gasification combined cycleshape optimization of a heat exchanger using parallel[MI. Beijing: China Electric Power Press, 1996(ingenetic algorithms [J]. International Journal of Heatand Mass Transfer, 2006, 49: 2567-25773] GU Xin, DONG Qiwu, LIU Minshan, et al. Numerical [10] LIU Wei, LIU Zhichun, WANG Shuangying, et alulation on heat transfer enhancement in shell sideStrengthening heat transfer research and spoiler mech-of shell-and-tube heat exchanger with leading typeanism in longitudinal bundles of tube-and-shell heatshutter baffles[ J]. Nuclear Power Engineering, 2010exchanger[J]. Science in China(Series E: Technologi31(2):113-117al sciences),2009,39(11):1850-1856[4] Zhang C, Xie G N, Luo L Q, et al. An experimental [11] XIA Xiangming, ZHAO Liwei, XU Hong, et al. Overallstudy of shell- and- tube heat exchanges with continu-performance factor for evaluating intensified heat conous helical baffles [J]. Technical Briefs, 2007, 129duction based on the fieldheory[J]. Jou1426-1431of Engineering for Thermal Energy and Power, 2011[5 ZHAO Benhua, HE Xuetao, YAN Hua, et al. Study of26(2):197-201the intensified heat transfer performance of a heat ex-上接第25頁(yè)[8]吳金星,董其伍,劉敏珊,等.折流桿換熱器殼程湍流和學(xué),2009,39(11):1850-1856傳熱的數值模擬[].高?；瘜W(xué)工程學(xué)報,2006,20(2)LIU Wei, LIU Zhichun, WANG Shuangying, et al.213-216Strengthening heat transfer research and spoiler mechWU Jinxing, DONG Qiwu, LIU Minshan, et al. Numer-anism in longitudinal bundles of tube-and-shell heat ex-ical simulation on the turbulent flow and heat transferhanger[J]. Science in China( Series E: Technologicalin the shell side of the rod baffle heat exchanger[J]Sciences),2009,39(11):1850-1856Journal of Chemical- ngineering of Chinese Universi-[11]夏翔鳴,趙力偉,徐宏,等.基于場(chǎng)協(xié)同理論的強化傳熱ties,2006,20(2)213-216綜合性能評價(jià)因子[J].熱能動(dòng)力工程,2011,26(2)[9] Hilbert R, Janiga G, Baron R, et al. Multi-objective197-201shape optimization of a heat exchanger using parallXIA Xiangming, ZHAO Liwei, XU Hong, et al. Overallgenetic algorithms [J]. International Journal of Heatrformance factor for evaluating intensified heat con-and Mass Transfer, 2006, 49: 2567-2577duction based on the field synergy theory [J]. Journal[10]劉偉,劉志春,王英雙,等.管殼式換熱器縱流管束內的of Engineering for Thermal Energy and Power, 2011擾流機制與傳熱強化研究[J].中國科學(xué)E輯:技術(shù)科26(2):1中國煤化工CNMHGhttp∥www.rfdcom. cnhttp:l/rlfd.periodicalsnet.cn第42卷第10熱力發(fā)電vo.42No.102013年10月THERMAL POWER GENERATIONOct.2013Numerical simulation on heat transfer enhancement in shellside of multi-component synthetic gas heat exchangerLI YanZ, JIANG Xiumin, REN Jianxing, 2, WU Jiang, 21. College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai 200090, china2. Shanghai Engineering Research Center of Power Generation Environment Protection, Shanghai 200090, China3. National Engineering Laboratory of Coal-fired Pollutants Emission Reduction, School of Mechanical engineeringShanghai Jiao Tong University, Shanghai 200240, ChinaAbstract: The porous media model was employed to conduct three-dimensional numerical simulation on ahigh pressure multi-component syngas heat exchanger designed by asPen software. The effect of differentgeometric structures on heat transfer and pressure drop of shell side fluid was investigated. The resultsshowed that, the heat exchanger designed by the aspen software had good flow and heat transfer performance; the temperature distribution of the high pressure multi-component syngas at shell side obtainedy the porous medium model agreed well with that designed by the aspen software keeping the other pa-rameters as constants and decreasing the segmental orifice degree of the baffle plate in heat exchanger from20% to 15% had little effect on heat transfer behavior of the shell side fluid, but the pressure drop was in-creasedKey words: shell and tube heat exchanger; multi-component syngas; porous medium; shell side; flow rateheat transfer; enhancement; ASPENAs the major heat exchanger type in the inte- verlapped and connected This structure helped tograted gasification combined cycle(IGCC) system, flow forwardly and prevented the upstream fluid inshell and tube heat exchanger has drawn much at- a spiral channel from reversely leaking to thetention in recent years, especially the relationship downstream channel through the triangle area.between the heat exchanger structure and the heat Zhao Benhua et all5] investigated and compared thetransfer performance has been widely investigated heat transfer performance of heat exchangers withby many researchers-23. Gu Xin et all3 studied the rotary self-cross rotor, co-rotating rotor andeffect of baffle structure parameters on heat trans- smooth pipe. They found that the rotary self-crossfer and flow resistance of the fluid in oblique flow rotor heat exchanger had better heat transfer pershell and tube heat exchanger, and analyzed the formance under the same conditions. He yaling etsynergy degree of the temperature and the velocity all studied the synergy effect of the pressure fieldgradient. Peng et al designed a short-circuit pre- and velocity field. They found that with an increaseventing baffles On the basis of the original sectorangle between the velocity vector and the presbaffles, the two straight edges were widened for sure gradient, the cooperativitythe pressuretube spacing width of one or two rows. The two field and the flow field got better, and the pressurestraight edges of the adjacent fan-shaped plates o- drop and flow loss decreased. Dong Qiwu and WuSupported by: National High Technology Research and Development Program of China(863 Program)(2007AA05Z247): Funding Scheme for Training Young Teachers in Shanghai Colleges(sdl11008); Key disciplines of Shanghai Education Commission(The Fifth Period)(J51304): Shanghai Engineering Research Center(11dz2281700)Correspondingauthor.E-mail:yli@shiep.edu.cnTH中國煤化工 onment ProtectionCNMHGsB 10 M LI Yan et al Numerical simulation on heat transfer enhancement in shell side of multi-component synthetic gas heat exchangerJinxing et al[7-8]applied the periodicity and symme- plate structure, the dismountable U-type tubulartry reduction methods to conduct numerical simu- structure was applied. The heat exchanger adoptedlation on a shell and tube heat exchanger Moreo- double-shell and double-tube structure. The synver, they proposed a geometric prototype of period- thetic gas and water flows along the Z axis, whilemodel and a simplified method of unit duct mohe y axis is their inflow and outflow directionel. On the basis of the overall symmetry, the com- This arrangement is the optimal configuration ac-putation amount was reduced significantly by tak- cording to the ASPEN calculation results.ing half of the simplified model to calculate. Hil-bertR et al] optimized the heat transfer and reduced the resistance by changing the structure ar-rangement. Liu Wei et allo] designed a new type ofrod baffle-spoiler blade combined heat exchangerand established the corresponding physical andmathematical model. Besides, the characteristics ofheat transfer and flow were simulated. They reported that the convective heat transfer coefficient inshell-side of this new heat exchanger was equivant to thebaffle heat exchanger, but the flowFig. 1 Schematic diagram of the high pressuremulticomponent synthetic gas heat exchangerfar less. Therefore, the comprehenive performance of the new heat exchanger wasFor calculation in the shell side, control equabetter than that of the rod baffle heat exchanger. tions of the porous medium model and the rNG k-eXia Xiangming et ali put forward a field synergy model were used. The empirical constants in theprinciple based dimensionless performance factor torng k-E model were as follows. C.=0.084 5,evaluate the effect of heat transfer enhancement Cle=l 42, Cze=1.68,P=0.012,o=4. 38,akcomprehensively In this paper, a porous medium=1.39model was applied to simulate the flow and heatAn initial temperature value of the tube-sidetransfer characteristics of the shell-side fluid in a fluid was given and its distribution was supposedclean synthetic gas superheater of the IGCC sys- to be linear. Temperature distribution of the shell-tem. The heat transfer mechanism of high pressure side fluid was obtained through the porous mediummulticomponent synthetic gas heat exchanger wasmodel Because the heat transfer of the shell-sidediscussed. Furthermore, the effect of baffle seg- fluid was equal to the heat release of the tube-sidemental degree on heat transfer of the synthesis gas fluid, the tube--side fluid temperature was iterative-heat exchanger was comparedly calculated till the convergence requirements1 Model establishmentwere satisfied. The physical properties of the tubeside fluid were calculated by the ASPEN PLUSThe structure of the high pressure multicom-software and in specific operation conditions theyponent synthetic gas heat exchanger is shown inwere considered as constantsFig. 1. The clean synthetic gas flows in the pipeThe main geometric parameters of the simpliand the water flows in the shell equipped withfied clean synthetic gas superheater are shown insome baffles in the middle. Considering the overTable 1 and table 2large temperaturess in the fixedH中國煤化工CNMHGhttp:www.rlfd.comcnhttp:/rlfd.periodicals.net.cn熱力發(fā)電2013年Table 1 Main geometric parameters of the simplified clean synthetic gas superheaterItemvalueItemInner diameter of the shell side/mm1 300 Baffle spacing/mn2 360 Baffle number6Inner diameter of the shell-side fluid at inletand outlet/mn200 Baffle segmental degree/The tube outer diameter/mmDistance between the first baffle and the tubeplate/mmThe tube inner diameter/mm14‖ Tube number2172ch/mm25 Tube arrangementTriangularTable 2 Main operation parameters of the simplified clean synthetic gas superheaterShell sideTube sideItemValueItemInlet mediumWater‖ Inlet mediumSynthetic gaInlet medium temperature/CInlet medium temperature/C144.Flux/kg·h-19020Fux/kg·h-1150140Operation pressure/MPaOutlet medium temperature /C2 Calculation method and the boundaryseen that, the water flows from the entrance to theconditionsexit along the shell. The flow rate around the baf-The gambit software was employed to generfles is low. Correspondingly, the residence time ofate the meshes, and the Fluent 6. 1 was adopted tothe fluid is prolonged. Seen in Fig. 4, the shell-sidefluid has smooth streamlines with almost no flconduct the simulation. The porosity, the resistancevortexdistribution and the heat source distribution werecoupled into the Fluent by applying thee user-de-fined function By SIMPLEC method, the equationswere solved. The second difference was used forthe momentum and energy equations and theStandard was employed for the pressure equation.The boundary conditions were: the pressureflux and temperature at the heat exchanger inletwere given; the outlet velocity was determined according to the mass conservation; the outlet pressure and temperature were determined according to Fig. 2 Mesh generation of the clean synthetic gas superheaterthe local unidirectional the outer shell of the heatexchanger adopted impermeable, no slip and adia-batic conditionsFig 2 shows mesh generation of the heat exchanger. The 782 228 mesh division method was a-dopted to conduct the calculation The grid computing error of this method was about 2%let3 Results and discussion3.1 Calculation results in the reference conditions IFig. 3 and Fig 4 show the velocity distributionand streamlines of the shell-side fluid. It can beYH中國煤化工elk-side fluidCNMHGhttp:www.rlfd.comcnhttp:/rlfd.periodicalsnetcn9 10 LI Yan et al Numerical simulation on heat transfer enhancement in shell side of multi-component synthetic gas heat exchangerThe temperature drop of the fluid at inlet is largeindicating severe heat transfer occursin letFig 4 Streamlines of the shelF-side fluidFig. 5 in which the unit is Pa, shows the pressure distribution of the shell-side fluid in cross secDtion where x=0. It can be seen that, the highestoutletfluid pressure appears at the heat exchanger en-trance. Then the pressure decreases gradually a-long the flow direction and reaches the lowest atFig 6 Temperature distribution of the shell-side fluidin cross section where x=0the outlet. The pressure drop between the inlet andoutlet is about 26 Pa. Along the fluid flow direc-3. 2 Effect of heat exchanger structure on heation, the pressure at the baffle plate forward direc-transfer per formancetion is higher than that at the dorsal side of theFig 7 shows structure of the heat exchangerbaffleswith baffle segmental degree of 15%. Fig 8andFig 9 are the velocity distribution and streamlinesof the shell-side fluid in heat exchanger with thisnew structure. Seen in Fig. 8 and Fig 9, the fluidvelocity around the baffle plates is low, while thatat the entrance and the exit is high. This is becausethe decrease in baffle segmental degree increasethe fluid disturbance, meanwhile, a large number ofvortexes also formed between and among the baffleplates, causing the flow dead zone appears, whichaffects the heat transfer between the shell-side flu-id and the tube-side fluidFig. 5 Pressure distribution of the sheell-side fluidin cross section where x=0Fig. 6 in which the unit is K shows the shell-side fluid temperature distribution in cross sectionwhere x=o As shown in Fig. 6, the entrance tem-perature of the shell-side fluid is 513 K and theoutlet temperature is 419 K, which is close to theFig. 7oh中國煤化工-ith bafflecalculated temperature (417. 44 K)by ASPENCNMHGhttp:/www.rlfd.comcnhttp://rlfd.perionet cn熱力發(fā)電2013年Fig 8 Velocity distribution of the shell-side fluid in heatexchanger with baffle segmental degree of 15%outletFig 10 Pressure distribution of the shell-side fluid incross section where x=0 with the bafflesegmental degree of 15%nletoutletFig. 9 Streamlines of the shell-side fluid in heat exchangerwith baffle segmental degree of 15%Fig. 10 shows pressure distribution of theshell-side fluid in cross section where x=0, withbaffle segmental degree of 15%. Comparison be-tween Fig. 5 and Fig 10 indicates that, with an de-crease in baffle segmental degree from 20% to15%, the inlet pressure of the shell-side fluid increases from 2. 66 Pa to 26 Pa, and the fluids pressure drop increases from 26 Pa to 38 Pa, whichaccordance with the general law that the fluid'spressure drop increases with the decrease of theFig. 11 Temperature distribution of the shell-side fluidbaffle segmental degree. The pressure at the bafflein cross section where x= with the bafflesegmental degree of 15%plate forward direction is higher than that at thedorsal side of the baffles4 ConclusionsFig 11 shows temperature distribution of theThe 3D numerical simulation on flow and heatshell-side fluid in cross section where x=0 with transfer oof the shell-side fluid in high pressurethe baffle segmental degree of 15%. Comparison multicomponent synthetic gas heat exchanger wasbetween Fig. 6 and Fig. 11 indicates that, with the conducted by adopting the porous medium modelbaffle segmental degree decreases from 20%distributed resistance and distributed heat source15%, the outlet temperature of the shell-side fluid relationships. The influence of the baffle segmentalchanges little. Decrease in baffle segmental degree degree on heat transfer performance was also in-has nearly no effect on heat transfer of the shell- vestigated. It could be concluded thatside fluid, but it can increase pressure drop of the(1)1中國煤化工 ned by aspenshell-side fluidsoftwareCNMHGransfer charachttp:/www.rlfd.comcnhttp:/rlfd.periodicalsnet.cns 10 #y LI Yan et al Numerical simulation on heat transfer enhancement in shell side of multi-component synthetic gas heat exchangerteristicschanger tube inner rotation direction self-cross rotor(2)Temperature distribution of the shell-side[J]. Journal of Engineering for Thermal Energy andfluid in clean synthetic gas superheater which wasPower,2012,27(3):307-311simulated by the porous medium model was similar[6] HE Yaling, LEI Yonggang, TIAN Liting, et al. An analysis of three-field synergy on heat transfer augerto that designed by the ASPEN software, demontation with low penalty of pressure drop[]. Journal ofstrating that the porous medium model can be usedEngineering Thermophysics, 2009, 30(11): 1904-to simulate the flow and heat transfer of the shell-1906side fluid in clean synthetic gas superheat[7] Dong Q W, Liu M S, Zhao X D. Research on the char-(3)For the given operation conditions and paacteristic of shellside support structures of heat ex-rameters in this study, the pressure drop of thchanger with longitudinal flow of shellside fluid[J].shell-side fluid increased when decreasing the baf-IASME Transactions, 2005,8(2): 1491-1498tal degree[8] WU Jinxing, DONG Qiwu, LIU Minshan, et al. Numer-ical simulation on the turbulent flow and heat transferReferencesin the shell side of the rod baffle heat exchanger[J][1] JIANG Zemin. Reflections on energy issues in ChinaJournal of Chemical Engineering of Chinese Universi[T. Journal of Shanghai Jiaotong University, 2008, 42ties,2006,20(2):213-216(3):345-359[9] Hilbert R, Janiga G, Baron R, et al. Multi-objective[2] JIAO Shujian Integrated gasification combined cycleshape optimization of a heat exchanger using parallel[MI. Beijing: China Electric Power Press, 1996(ingenetic algorithms [J]. International Journal of Heatand Mass Transfer, 2006, 49: 2567-25773] GU Xin, DONG Qiwu, LIU Minshan, et al. Numerical [10] LIU Wei, LIU Zhichun, WANG Shuangying, et alulation on heat transfer enhancement in shell sideStrengthening heat transfer research and spoiler mech-of shell-and-tube heat exchanger with leading typeanism in longitudinal bundles of tube-and-shell heatshutter baffles[ J]. Nuclear Power Engineering, 2010exchanger[J]. Science in China(Series E: Technologi31(2):113-117al sciences),2009,39(11):1850-1856[4] Zhang C, Xie G N, Luo L Q, et al. An experimental [11] XIA Xiangming, ZHAO Liwei, XU Hong, et al. Overallstudy of shell- and- tube heat exchanges with continu-performance factor for evaluating intensified heat conous helical baffles [J]. Technical Briefs, 2007, 129duction based on the fieldheory[J]. Jou1426-1431of Engineering for Thermal Energy and Power, 2011[5 ZHAO Benhua, HE Xuetao, YAN Hua, et al. Study of26(2):197-201the intensified heat transfer performance of a heat ex-上接第25頁(yè)[8]吳金星,董其伍,劉敏珊,等.折流桿換熱器殼程湍流和學(xué),2009,39(11):1850-1856傳熱的數值模擬[].高?；瘜W(xué)工程學(xué)報,2006,20(2)LIU Wei, LIU Zhichun, WANG Shuangying, et al.213-216Strengthening heat transfer research and spoiler mechWU Jinxing, DONG Qiwu, LIU Minshan, et al. Numer-anism in longitudinal bundles of tube-and-shell heat ex-ical simulation on the turbulent flow and heat transferhanger[J]. Science in China( Series E: Technologicalin the shell side of the rod baffle heat exchanger[J]Sciences),2009,39(11):1850-1856Journal of Chemical- ngineering of Chinese Universi-[11]夏翔鳴,趙力偉,徐宏,等.基于場(chǎng)協(xié)同理論的強化傳熱ties,2006,20(2)213-216綜合性能評價(jià)因子[J].熱能動(dòng)力工程,2011,26(2)[9] Hilbert R, Janiga G, Baron R, et al. Multi-objective197-201shape optimization of a heat exchanger using parallXIA Xiangming, ZHAO Liwei, XU Hong, et al. Overallgenetic algorithms [J]. International Journal of Heatrformance factor for evaluating intensified heat con-and Mass Transfer, 2006, 49: 2567-2577duction based on the field synergy theory [J]. Journal[10]劉偉,劉志春,王英雙,等.管殼式換熱器縱流管束內的of Engineering for Thermal Energy and Power, 2011擾流機制與傳熱強化研究[J].中國科學(xué)E輯:技術(shù)科26(2):1中國煤化工CNMHGhttp∥www.rfdcom. cnhttp:l/rlfd.periodicalsnet.cn