第26卷第3期化學(xué)反應(yīng)工程與工藝Vol 26. No 32010年6月Chemical Reaction Engineering and TechJune 2010文拿編號(hào):1001-7631(2010)03-0193-0漿態(tài)床合成氣制二甲醚反應(yīng)器數(shù)學(xué)模擬胡智力1劉殿華房鼎業(yè)1潘強(qiáng)2顏蜀雋2羅春桃(1.華東理工大學(xué)大型工業(yè)反應(yīng)器工程教育部工程研充中心,化學(xué)工程聯(lián)合國(guó)家重點(diǎn)實(shí)驗(yàn)室,上海2002372.神華寧煤集團(tuán)煤化工公司研發(fā)中心,寧夏銀川750411)搞要:建立了包括液相返混和催化劑顆教沉降的合成氣一步法制二甲醚漿態(tài)床反應(yīng)器的數(shù)學(xué)模型,模擬計(jì)算了空速、原料氣組成、反應(yīng)溫度、反應(yīng)壓力等反應(yīng)條件對(duì)反應(yīng)的影響,計(jì)算結(jié)果表明,CO轉(zhuǎn)化率和二甲醚的選擇性隨溫度增加、壓力增大而提高,在一定溫度、壓力條件下,CO轉(zhuǎn)化率隨空速增大而減小,合成氣含有一定量的CO2有利于CO轉(zhuǎn)化率增加關(guān)鵪詞:漿態(tài)床;食成氣;二甲:學(xué)橫型中圖分樊號(hào);TQ018文獻(xiàn)標(biāo)識(shí)碼:A合成氣二步法制二甲醚(DME)要經(jīng)過(guò)合成氣制甲醇和甲醇脫水兩個(gè)步驟,流程較長(zhǎng),設(shè)備投資大,產(chǎn)品成本較高,目前國(guó)內(nèi)外都在大力開展由合成氣一步法制二甲醚的研究。合成氣一步法制二甲醚是放熱反應(yīng),在固定床反應(yīng)器中進(jìn)行時(shí)反應(yīng)熱不易移出,存在溫度控制難等缺點(diǎn),若使用貧氫合成氣,則反應(yīng)溫度高,催化劑易結(jié)炭,因此固定床中氣相一步法反應(yīng)只能在轉(zhuǎn)化率較低情況下操作,大量的未反應(yīng)合成氣必須循環(huán),并使用富氫合成氣。漿態(tài)床中合成氣一步法制二甲醚是在三相體系中進(jìn)行的,CO、H2和DME等為氣相,惰性溶劑為液相,懸浮于溶劑中的催化劑為固相。氣相CO和H2穿過(guò)液相油層到達(dá)懸浮的固體催化劑表面進(jìn)行反應(yīng),由于液相的熱容大,液相一步法很易實(shí)現(xiàn)恒溫操作,而且催化劑顆粒表面為溶劑所包圍,結(jié)炭現(xiàn)象大為緩解,因而液相法可使用貧氫合成氣,適合我國(guó)以煤為原料制合成氣的現(xiàn)狀。鑒于三相漿態(tài)床在合成二甲醚中的熱力學(xué)、工藝條件及反應(yīng)器等方面的優(yōu)勢(shì),國(guó)內(nèi)外已將二甲醚的工業(yè)化研究集中于三相漿態(tài)床合成反應(yīng)器上,漿態(tài)床合成氣制二甲醚是未來(lái)工業(yè)化二甲醚生產(chǎn)的技術(shù)發(fā)展趨勢(shì)口-3。本工作建立了年產(chǎn)10萬(wàn)噸二甲醚漿態(tài)床反應(yīng)器模型,在合成氣H2和CO體積比為1~2,反應(yīng)壓力4~6MPa,溫度230~300℃條件下,模擬研究了反應(yīng)條件對(duì)反應(yīng)的影響,以期為工業(yè)反應(yīng)器的設(shè)計(jì)提供依據(jù)。漿態(tài)床反應(yīng)器數(shù)學(xué)模型合成氣一步法制二甲醚是一個(gè)復(fù)雜的反應(yīng)體系,主要反應(yīng)有:CO+2H,=CH3 OHCO2+3H2=CH,OH+H2O2CH,OH=CH, OCH,+H2O3C0+3H2=CH3 OCH,+CO22c0+4H,=CH, OCH,+H,OCO+H2 O=CO,+H2中國(guó)煤化工(6)收稿日期:2010-04-21;修訂日期:2010-05-23CNMHG作著簡(jiǎn)介:胡智力(1986),男,碩士研究生;劉殿華(1970-),男,副教授,通訊聯(lián)系人,Emal;delia@ecust.eud.cn薔金項(xiàng)目:國(guó)家科技支撐計(jì)劃資助(2007BAAo8B04)194化學(xué)反應(yīng)工程與工藝2010年6月根據(jù)相律計(jì)算得知該反應(yīng)體系的獨(dú)立反應(yīng)數(shù)為3,選取CO、CO2、 CH, OCH3為獨(dú)立組分,式(1)、(2)和(3)為獨(dú)立反應(yīng)1.1模型假設(shè)數(shù)學(xué)模型假設(shè):(1)氣相為平推流;(2)催化劑固體顆粒較小,液固之間的傳質(zhì)阻力忽略不計(jì);(3)反應(yīng)在高壓下進(jìn)行,反應(yīng)器內(nèi)總壓不變;(4)在高空速條件下,床層溫度均勻;(5)考慮催化劑的軸向分布,用固相沉降模型處理催化劑的床層分布。1.2數(shù)學(xué)模型考慮液相返混和催化劑顆粒沉降后的數(shù)學(xué)模型如下:klai(Ht-Cl. ), (j= H2, CO2, CO, CH,OH, H, O, DMED,rGi= H2, CO2, CO)-c-(,-c),0-c0,H0DNB邊界條件Cx=c,clxn-c,。z|2-013模型參數(shù)采用銅基催化劑和yAl2O甲醇脫水催化劑為雙功能催化劑所測(cè)定的動(dòng)力學(xué)方程:對(duì)()(-K/元)4舞)角(-xrrp Ag expR)(-m式中各個(gè)An為實(shí)驗(yàn)擬合的模型參數(shù),K為平衡常數(shù),f為各組分的逸度,采用 SHBWR狀態(tài)方程計(jì)算(。反應(yīng)器模型中其它參數(shù)-12如下:(4),(2-1)A-cb,頁(yè)=(-),=1,U了,U=Dp=P)U. Dg9.6()01+0.019R}1Re- U,DRpt, Re.=U.dee, D, =2. 7U'D2結(jié)果與討論已有文獻(xiàn)報(bào)道工業(yè)化或即將工業(yè)化的一步法漿態(tài)床中國(guó)煤化工斤要模擬的原料氣組成H2CO為1~2,故采用文獻(xiàn)的中試數(shù)據(jù)為模型CNMHG模型進(jìn)行模擬計(jì)算結(jié)果見表1。第26卷第3期胡智力等.漿態(tài)床合成氣制二甲醚反應(yīng)器數(shù)學(xué)模擬表1反應(yīng)器模擬計(jì)算數(shù)據(jù)與文獻(xiàn)值的比較Table. 1 The comparison of computational results with pllot plant dataH:/COT/CXoo,Err.%Computational results607.1表1結(jié)果表明,反應(yīng)器模擬計(jì)算數(shù)據(jù)與文獻(xiàn)中試數(shù)據(jù)比較的相對(duì)誤差為7.1%,表明建立模型與參數(shù)選擇合理,能較好地模擬反應(yīng)器實(shí)際狀況。2.1空速的影響在反應(yīng)壓力5MPa,反應(yīng)溫度250℃C條件下,模擬計(jì)算了空速對(duì)CO的轉(zhuǎn)化率的影響,結(jié)果見圖1?？梢钥吹?隨著空速的增大,CO的轉(zhuǎn)化率下降,這是因?yàn)殡S著空速的提高,反應(yīng)物在反應(yīng)器停留時(shí)間短,合成反應(yīng)不能充分進(jìn)行。雖然在低空速下,CO轉(zhuǎn)化率較大,但生產(chǎn)能力會(huì)降低,故要適當(dāng)控制空速圖1空速對(duì)CO轉(zhuǎn)化率的影響圖2CO2含量對(duì)CO轉(zhuǎn)化率的影響Fig. 1 Effect of space velocity on CO conversionFig. 2 Effect of CO, concentration on CO conversion2.2原料氣組成的影響圖2所示為反應(yīng)壓力5MPa,反應(yīng)溫度250℃,H2/CO為2的條件下原料氣中CO2含量變化對(duì)CO轉(zhuǎn)化率的影響。結(jié)果表明,含有適量的CO2有利于二甲醚的合成,但原料中CO2含量過(guò)高,會(huì)造成后續(xù)分離過(guò)程的困難,增加分離成本。因此在實(shí)際生產(chǎn)中應(yīng)綜合考慮CO2含量對(duì)生產(chǎn)的影響。2.3反應(yīng)溫度的影響圖3和圖4所示的是在反應(yīng)壓力5MPa,不同合成氣配比(H2/CO)條件下,溫度的變化對(duì)CO轉(zhuǎn)化率以及產(chǎn)物二甲醚選擇性的影響。由圖可知,隨著溫度的增加,CO轉(zhuǎn)化率提高,二甲醚選擇性提高。雖然反應(yīng)體系是放熱的,但在反應(yīng)條件下,反應(yīng)未達(dá)到平衡狀態(tài),反應(yīng)受動(dòng)力學(xué)控制,所以隨著溫度的升高,CO轉(zhuǎn)化率增大,DME的選擇性也增大。------“070中國(guó)煤化工CNMHG圖3反應(yīng)溫度對(duì)cO轉(zhuǎn)化率的影響度對(duì)UEM彈性的影響Fig 3 Effect of temperature on CO conversionFig. 4 Effect of temperature on DME selectivity196化學(xué)反應(yīng)工程與工藝2010年6月2.3反應(yīng)壓力的影響圖5與圖6表示的是在反應(yīng)溫度250℃,不同合成氣配比(H2/CO)條件下,壓力的變化對(duì)CO轉(zhuǎn)化率和二甲醚選擇性的影響?？梢钥吹?隨著壓力的增大,CO轉(zhuǎn)化率提高,二甲醚選擇性提高。因?yàn)楹铣蓺庵贫酌咽强傮w積減小的反應(yīng),增大壓力有利于反應(yīng)進(jìn)行。4.5505.5606P/ MPaP/ MPa圖5反應(yīng)壓力對(duì)CO轉(zhuǎn)化率的影響6反應(yīng)壓力對(duì)DEM選擇性的影響Fig 5 Effect of prCO conversionFig. 6 Effect of pressure on DME selectivity3結(jié)論建立了包括液相返混和催化劑顆粒沉降的合成氣一步法制二甲醚漿態(tài)床反應(yīng)器的數(shù)學(xué)模型,通過(guò)對(duì)不同反應(yīng)條件下漿態(tài)床合成氣制二甲醚的模擬計(jì)算,考察了反應(yīng)條件對(duì)反應(yīng)的影響,在工業(yè)反應(yīng)器的設(shè)計(jì)中,在不影響催化劑及設(shè)備條件下,應(yīng)適當(dāng)提高反應(yīng)溫度、壓力,原料氣中CO2的含量不易過(guò)大,宜控制在5%以內(nèi)符號(hào)說(shuō)明a—?dú)庖罕缺砻娣e,m2/m2反應(yīng)器進(jìn)口催化劑濃度,kg/m2反應(yīng)器內(nèi)沿床層高度催化劑濃度,kg/m3反應(yīng)器內(nèi)催化劑平均濃度,kg/m3氣相中j組分的濃度,kmol/m2液相中j組分的濃度,kmol/r催化劑顆粒粒徑,m液相軸向擴(kuò)散系數(shù),m2/sDR反應(yīng)器內(nèi)徑,m顆粒軸向擴(kuò)散系數(shù),m2/s重力加速度,m/s2氣體溶解度,kg/kg床層高度,m氣液傳質(zhì)系數(shù),m/s反應(yīng)的平衡常數(shù)CO加氫反應(yīng)速率,kmol/(kgm·b)CO2加氫反應(yīng)速率,kmol( kKat.h二甲醚生成速率,kmol/(kgah)氣相的 Reynold數(shù)顆粒的 Reynold數(shù)溫度表觀氣速,m/s顆粒受阻沉降速度,m/s顆粒閆由沉降速度催化劑密度,kg/m3液相密度,kg/m3H中國(guó)煤化工參考文獻(xiàn):NMHGI Moradi GR, Nazari M, Yaripour F. Statistical Analysis of the PerformLanyon unue. sperating Conditionsof LPDME Process. Chemical Engineering Journal, 2008, 140: 255-263第26卷第3期胡智力等.漿態(tài)床合成氣制二甲醚反應(yīng)器數(shù)學(xué)模擬1972 Prasad P SS, Bae J W, Kang S H, et al Single-Step Synthesis of DME from Syngas on Cu-Zno-Al O/Zeolite BifunctionalCatalysts: The Superiority of Ferrierite over the Other Zeolites, Fuel Processing Technology, 2008, 89: 1281-12863 Chena P, Guptab P, Dudukovica M P, et aL Hydrodynamics of Slurry Bubble Column during Dimethyl Ether(DME) SynthesisGas-Liquid Recirculation Model and Radioactive Tracer Studies, Chemical Engineering Science, 2006, 61: 6553--65704趙玉龍,張碧江,煤液化中氣液固反應(yīng)工程概況化學(xué)工程,1984,12(2):45~57Zhao Yulong, Zhang Bijiang. Gar Liquid-Solid Reaction Engineering in Liquefaction of Coal. Chemical Engineering, 1984, 12(2)45~575劉殿華,華鯡,房鼎業(yè).固定床合成氣制二甲醚的本征動(dòng)力學(xué)研究,天然氣化工,2007,32:18~22Liu Dianhua, Hua Xing, Fang Dingye. Intrinsic Kinetics of Dimethyl Ether Synthesis from Syngas in Fixed Bed Reactor. NaturalGas Chemical Industry, 2007. 321 18-226張海海,曹發(fā)海,劉殿華等.合成氣直接合成二甲嬖與甲醇的熱力學(xué)分析.華東理工大學(xué)學(xué)報(bào),2007,27(2):198~201Zhang Haitao, Cao Fahai, Liu Dianhua, et aL Thermodynamic Analysis for Synthesis of Dimethyl Ether and Methanol fromSynthesis Gas. Journal of East China University of Science and Technology, 2007, 27(2): 198-2017郭天民.多元?dú)庖浩胶夂途s,北京:石油工業(yè)出版社,2002mith D N, Ruether JAlid Dynamics in a Sully Bubble Column, Chemical Engineering Science, 1985, 40(5)1 741-754宋懷俊,張海濤,應(yīng)衛(wèi)勇.H2、N2、CO和CO2在液體石蠟中的溶解度和傳質(zhì)系數(shù)的研究.華東理T大學(xué)學(xué)報(bào),200430(5)498~518Song Huaijun, Zhang Haitao, Ying Weiyong. Investigation on Solubility and Volumetric Mass Transfer Coefficient of Hi, N2, cOand CO in Liquid Paraffin. Journal of East China University of Science and Technology, 2004, 30(5): 498-51810宋懷俊,張海濤,應(yīng)衛(wèi)男.二甲醚在液體石蠟中的溶解度和體積傳質(zhì)系數(shù)的研充,高校化學(xué)工程學(xué)報(bào),2005,19(2);253~257Song Huaijun, Zhang Haitao, Ying Weiyong. Study on Solubility and Volumetric Mass Transfer Coefficient of Dimethyl EtherinLiquid Paraffin. Journal of Chemical Engineering of Chinese Universities, 2005, 19(2): 253-25711宋懷俊,張海濤,應(yīng)衛(wèi)勇等.甲醇、水蒸氣在液體石蠟中的溶解度和體積傳質(zhì)系數(shù)的研究石油化工,2005,34(6);551~555Song Huaijun, Zhang Haitao, Ying Weiyong, et al. Solubilities and Volume Mass Transfer Coefficients of Methanol and Steam inLiquid Paraffin. Petrochemical Technology, 2005, 34(6) 551-5552秦惠芳,王世榮,丁百全等,醫(yī)用液體石蠟的物性數(shù)據(jù)測(cè)定及估算.天然氣化亡,199,24(3):56~58Qin Huifang, Wang Shirong, Ding Baiquan, et al. Determination and Estinmtion of Physical Property Data for Liquid Paraffin.Natural Gas Chemical Industry, 1999, 24 (3)1 56-513黎漢生,任飛,王金福.漿態(tài)床一步法二甲醚產(chǎn)業(yè)化技術(shù)開發(fā)研究進(jìn)展.化工進(jìn)展,2004,23(9):921~924Li Hansheng, Ren Fei, Wang Jinfu. Progress in Development of Direct Mass Production Technique of Dimethyl Ether fromSynthesis Gas in a Slurry Reactor. Chemical Industry And Engineering Progress, 2004, 23 (9)14 OKawa T, Inoue N, Shikada T, et al Direct Dimethyl Ether Synthesis. Joumal of Natural Gas Chemistry, 2003, 12(4): 219-227Mathematical Simulation for Synthesis of Dimethyl Ether from Syngasin a Slurry Bubble Column ReactorHu Zhili Liu Dianhua Fang Dingye Pan Qiang Yan Shujun Luo Chuntao(1. Engineering Research Center of Large Scale Reactor Engineering and Technology of Ministry of Educationate Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China2. Research and Development Center, Shenhua Ningxia Coal Industry Group Co Ltd, Yinchuan 750411, ChinaAbstract: A mathematical model for one step synthesis of dimethyl ether from syngas in a slurrybubble column reactor was developed, considering the influence of inert carrier backmixing and theinfluence of catalyst grain sedimentation. The effects of the space velocity, feed gas compositiontemperature and pressure were discussed. The results showed that CO conversion and DME selectivityincreased with the increase of temperature and pressure.rtain temperature and pressureconditions, the conversion of co decreased with the incre中國(guó)煤化工; th a certainamount of CO, was benefit to increasing of CO conversiCNMHGKey words: slurry reactor; syngas; dimethyl ether; mathematical model