第41卷第10期化學(xué)工程Vol. 41 No. 102013年10月CHEMICAL ENGINEERING( CHINA)Oct. 2013鼓泡流化床內(nèi)粉煤氣化的數(shù)值模擬王海艷"”，郝振華'，房倚天'，黃戒介'，董立波'，張磊', 陸慧林(1.中國科學(xué)院山西煤炭化學(xué)研究所煤轉(zhuǎn)化國家重點實驗室，山西本原030001; 2.中國科學(xué)院大學(xué)，北京100039; 3.哈爾濱工業(yè)大學(xué) 能源科學(xué)與工程學(xué)院，黑龍江哈爾濱150001)摘要:將應(yīng)用歐拉雙流體模型對鼓泡氣化爐內(nèi)的氣化過程進(jìn)行研究。摒棄傳統(tǒng)顆粒動理學(xué)理論中顆粒光滑無旋轉(zhuǎn)的假設(shè),引人顆粒的旋轉(zhuǎn)運(yùn)動,構(gòu)建粗糙顆粒動理學(xué)理論來封閉雙流體模型?；谌紵碚摻⒎勖簾峤鈿饣Ｐ鸵约肮呐荽矁?nèi)氣固之間以及氣體和氣體之間的傳熱、傳質(zhì)模型。采用該模型進(jìn)行數(shù)值模擬計算,分析床內(nèi)的氣固反應(yīng)過程,對比實驗結(jié)果表明粗糙顆粒動理學(xué)理論適用于模擬鼓泡床氣化爐內(nèi)的反應(yīng)。關(guān)鍵詞:粗糙顆粒動理學(xué);粉煤氣化;鼓泡流化床中圖分類號:TQ 545文獻(xiàn)標(biāo)識碼:A文章編號:005-9954( 2013) 10-0045-05DOI:10. 3969/j isn.100S-9954. 2013.10.011Numerical simulation of coal gasification in bubbling fluidized bedWANG Hai-yan'.2 ,HAO Zhen-hua' ,FANG Yi-tian'，HUANG Jie-jie' ,DONG Li-bo' ，ZHANG Lei' ,LU Hui-lin'(1. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry ,Chinese Academy of Sciences，Taiyuan 030001 ,Shanxi Province ,China ;2. University of Chinese Academy of Sciences , Bejing100039, ,China ;3. School of Energy Science and Engineering, Harbin Institute ofTechnology , Harbin 150001 , Heilongjiang Province, China)Abstract: The gasifcation behavior of gas and solids in a bubbling fluidized bed gasifer was simulated by Euleriantwo-fuid model. Different from the present kinetic theory of granular flow based on the assumption of smooth andelatic during the cllision of particles, the rolation of particles was taken into account and the kinetic theory ofrough spheres( KTRS )was proposed for the two-luid model closure. Meanwhile the coal pyrolysgsification modelbased on the combustion theory and the heat and mass transfer model between gas and solid as well as gas and gasin a bubbling fluidized bed were established. By this means, the reaction behavior of gas solid in the fluidized bedwas analyzed. The simulated resuls agree well with the experimental data, which shows that the kinetic theory ofrough spheres can reasonably describe the reaction in a bbling fluidized bed gasifer.Key words:kinetic theory of rough spheres ;coal gasification ;bubbling fluidized bed .流化床碎煤氣化技術(shù)由于具有反應(yīng)條件溫和，人顆粒旋轉(zhuǎn)對流化床 進(jìn)行了模擬計算,結(jié)果表明顆可以氣化高灰、高灰熔點煤,設(shè)備造價低等諸多優(yōu)粒旋轉(zhuǎn)對床內(nèi)顆粒的速度和濃度均有影響。但是，點,顯示出強(qiáng)大的發(fā)展前景。將顆粒旋轉(zhuǎn)引人煤粉氣化反應(yīng)的數(shù)值模擬研究還未假定顆粒表面光滑無旋轉(zhuǎn)運(yùn)動,前人對鼓泡床見報道。氣化爐數(shù)值模擬做了許多工作(3。然而,許多研究綜上,作者考慮粗糙顆粒瞬時碰撞過程中的旋表明'48] ,顆粒旋轉(zhuǎn)會對氣固流動結(jié)構(gòu)產(chǎn)生- -定的影轉(zhuǎn)摩擦效應(yīng),采用粗糙顆粒動理學(xué)理論[12]對固相方響,在數(shù)值模擬過程中,應(yīng)予以考慮。Sun'°! , Wang程進(jìn)行封閉,對高2 m直徑為0.2 m的鼓泡床氣化Shuyan' 10] , Wang Shuil1] 等分別采用不同的方法引爐內(nèi)氣化反應(yīng)過程進(jìn)行數(shù)值模擬,為今后的研究工收稿日期::2012-12-11中國煤化工基金項目:中國科學(xué)院山西煤炭化學(xué)研究所青年創(chuàng)新基金(2011SQNRC02).MYHCN M H G通信聯(lián)系人,Emal:作者簡介:王海艷(1986- -), 女,碩士研究生,研究方向為流態(tài)化.數(shù)值模擬，E-mailhzh203@ 163. com。●46●化學(xué)工程2013 年第41卷第10期作拓寬思路。數(shù);p為密度;u為速度。1.2動量方程.1氣化爐內(nèi)氣固二相流動-反 應(yīng)數(shù)學(xué)模型1.1連續(xù)性方程Q(φ,Pou,) +V●(qP2u.ug)=中e V.τ +φpP,8 -(φP。)+V.(φp。u,)= Es。.4。Vp-Bg(u,-u,)+S?！駏g (2)(1)(pρ,u,) +V●(qp,u.u,) =φ, V●T, +φρ,8 -8ti(φp.)+V.(φ.ρ.u.)= 2S.φ。Vp+β。(u。-u.) +Sg●u. (3)式中:下標(biāo)s,g分別表示氣體和固體;N為組分個式中:τ 和β。分別為氣體和固體的應(yīng)力及氣固曳數(shù);S。和S分別為組分i的生成速率;p為體積分力,ρ為顆粒相總應(yīng)力,本構(gòu)關(guān)系參照表1。表1本構(gòu)關(guān)系式"Table 1 Constitutive relation氣相應(yīng)力:r。=p,[Vu, +(Vu。)"]-號u。(V.u,)8 .(T-I)固相應(yīng)力:r，= p,8 +μ,[Vu, + (Vu,)"] +5(V.u,)δ +ξ.δxVxu.(T-2)固相壓力:p, =二a.p.p.e。 + p,p.g.(1 +e)e。T-2a)顆粒相體積黏度:6 = +.O.,(1+e) 1唇{o.v(T-2b)顆粒相旋轉(zhuǎn)黏度:ξ. 19uw. K(1+)(T-2c)顆粒相剪切黏度:μ。=p.um +μ.cu(T-2d顆粒相動力黏度:H.kin =μu[1 +1.6[n:(3n. -2) +0.5n2(6m. -1 -2n2 - 2n.a,/( Ka,))]o.B.1+ 號(2n +3n)4.| (T.2d1)g。[(2-η -n)(η + n) + na,/(6Ka,)]顆粒相碰撞黏度:μo= qp.g.dp. ,/*(4n, +3m2){o.a古層πa,π[an +2p.g.(1 +e)aa](T-2d2)η =(1 +e)2,n2 =0.5K(1 +β)/(1 +K),K=」-rdm(T-e)K, ={421[a(I], +1.) +a,(I, +I,)]+號4.8。0(小+號2)(.,I2 +a,I,)+| 4gJI顆粒脈動動能擴(kuò)散系數(shù):(T-3) .3 V3ae°a,(η + n2)4,p.g.d +2m_λ_-4.g.(a,I +a,I,) +-43.p.g.da,J4πK g,= -(3a3a; - 25a,a,);I]2 =(6asag + 10aqa.p.g.);l3 =卡(Sa,a, + 3a2agp.g.)II。= 5(5asa。+asay4.B.);Is = 25(agas + 5ara69.g.)a = n/K;az =4a,(2η -1);a; =41(η +n2) -33(力+m2) +50ηηz - 7aa,/a;as = 3/2 + a24.g./K;as =5/2 +[4(6n2 一站) -2m(9η +4m2) +8a,m(2K +a,/a)]o.g.;a6 =a[3中國煤化工”-16a,n.+ar +8a。7;ag = (η +n2) +a,/3n2(7-4n,) -a,(2 + 1/K)YHCNMHG王海艷等鼓泡流 化床內(nèi)粉煤氣化的數(shù)值模擬●47●續(xù)表1顆粒碰撞能量耗散:x =- 3q,.p.g.Oa,海、1gr1-2+(三2)(+ 9)] 300951C,a, +2aq.1+.)1v..(T4)2dVπc,=aud, c;=aA+尋(1-e)+(二其) Koa.tga,(1 +e)顆粒相單位體積能量耗散率:D。=_25(T-5)(3a).5 me.g.“dp.'*a,與a,為量綱- -平動和轉(zhuǎn)動系數(shù),a, +a, =號;g.為顆粒徑向分布函數(shù);刀; ,加為與顆粒彈性恢復(fù)系數(shù)e和切向恢復(fù)系數(shù)β有關(guān)的系數(shù);akx與a..分別為懸浮能和碰撞與總能量的比值。M. 0.81.3擬總溫方程中+、告m)(12)類比顆粒動理學(xué)理論,引人顆粒擬總溫e。:/8(1 +me。==<+c +(4)λ.= ZwAwA.=u.(Cu+4M.)(13)式中:C為顆粒平動脈動速度;w為顆粒旋轉(zhuǎn)脈動速度;1為轉(zhuǎn)動慣量。中g(shù) =中。6入p。中.Nu,(14)d2 j(qp.eo) +V .(4p.e。u.)]=V.(K, ve.)+Nu, =(7-10a +5a2)(1 +0.7Re,2 Pr'3}) +p:Vu. -x. -D。-3βge。(5)(1. 33 -2.4a。+1. 2q})Re;,'Pr/3 (15)式中:K,X.,D。物理意義及具體的本構(gòu)關(guān)系式見1.6 熱解反應(yīng)采用如下雙方程熱解模型:表11.4 組分方程[煤-“+(1-a)w(炭) +a,(揮發(fā)分)(16)(pwe.) +V(ρou.u,)=-V.Ju. +S。(6)煤氣+(1-a2)w2(炭) +a2(揮發(fā)分)(17)反應(yīng)速率:ro=(a,h + azk)c.(18)式中: w。,為組分i的局部質(zhì)量分?jǐn)?shù)。式中:C為固體碳顆粒未反應(yīng)的濃度。擴(kuò)散通量J。.=-(p,D;+二)V ●w。.(7)速率系數(shù)h; = A,exp[- E/(RT)]i=1,2(19)式中:σγ為Schmidt數(shù)。1.7 異相反應(yīng)1.5 能量方程煤氣化過程中的非均相反應(yīng)為j(apgcT) +V. (ap,CT,u,)=V(λg VT)+2K +2K+氣C(s) +O2(g)→H2C0(g) +φ。(T。-T,)+ ESuCgT(8)2一一CO2(g)(20)O(ap,c,T.) +V. (ap,c.T.u,)=V(Aλ。VT,) +C(s) +H2O(g)-→C0(g) +H2(g) (21)C(s) + CO2(g)-→2CO(g)(22)φ&(T,-T)+ ES.cgT.(9)按縮核模型計算式(20)- -(22)反應(yīng)系數(shù)k..式中:T,c,λ ,中。分別表示溫度、比熱容、導(dǎo)熱系數(shù)和(Pa-'●s")為相間換熱系數(shù);ScT為反應(yīng)引入的源項。具體表達(dá)k.3 = 17. 9x'exp(- 13 750/T)(23 )式為k, =5.95x 10 Yexp(- 13 650/T,) (24)cq= Zw,Cg c。= Sw.c。(10)中國煤化工T,) (25)x;hgi，5RCNM H G_λ.=ZxJYH2 ixXiPy;5g=4He(Cy+4M) (11) 式中:x= (ww，，0在山v。與w0,10。分w"w。●48●化學(xué)工程2013 年第41卷第10期別為初始時刻與反應(yīng)中殘?zhí)款w粒內(nèi)灰分和固定碳的1.8 均相反應(yīng)質(zhì)量分?jǐn)?shù)。主要均相反應(yīng)及化學(xué)反應(yīng)速率見表2。表2均相化學(xué)反應(yīng)速率Table 2 Homogeneous reaction rates used in simulations反應(yīng)反應(yīng)速率/(kg.m-3.s-I)動力常數(shù)_動力常數(shù)單位CH, +202- +2H2OR。=kJT-' w( CH:)w(O2)p2k。=1 x10l*exp(- 15 700/T)kmol-' .m' .K.s-'H2 +02-→+2H2OR, = khT"*w's(H2)w(O2)p2'h, =5.159x 10'exp( - 3430/T，) kmol :2C0+02-→2CO2Rg = kgw( CO)w^s(O2)p;'hg = 1.0x 10'*exp(- 16 00/T7) kmol-0.75 .m2.5. K!'5.s-'_u(CQ)u(H) 1的=2. 78 x 10'exp(- 1510/T,)∞+H0一-cCO2 +Hh R=k [ w(CO)w(H2O)kmol-' .m' .s'hg. = 0. 0265exp(3 968/T])2數(shù)值計算條件3計算結(jié)果分析計算模型按照Chejne等[13]的實驗數(shù)據(jù),結(jié)構(gòu)3.1模擬結(jié)果與實驗結(jié)果對比示意如圖1所示。計算采用速度人口邊界條件,頂圖2為數(shù)值模擬結(jié)果與實驗結(jié)果的對比，由圖部為壓力出口,出口壓力為100 kPa。燃料反應(yīng)器兩可見計算值中CO2和H2的值偏大, CO的值偏小。側(cè)為絕熱壁面。初始床料高度為1.0 m,體積分?jǐn)?shù)分析原因可能是:①CaCO3 ,SO2和O2的反應(yīng)發(fā)生量為0.58。固體煤顆粒中水分、固定碳、揮發(fā)分和灰較小,計算時忽略;②煤熱解模型的局限性。分分別為2.6% ,54. 1% ,41. 8%和1.5%。其余模60照實驗擬參數(shù)見表3。習(xí)模擬↑↑↑↑↑q.-21.9kgh寂40- q(H2O)=4.6kghT。-693K至30-20_D10t: CO: CH， CON:圖2 模擬結(jié)果與實驗對比Fig.2 Comparisons between predictions and experimental data3.2顆粒擬總溫 .圈1流化床氣化床結(jié)構(gòu)圖3為顆粒擬總溫隨體積分?jǐn)?shù)的變化。顆粒擬Fig.1 Structure scheme of 2D fuel reactor總溫反映了顆粒平動和轉(zhuǎn)動脈動的強(qiáng)弱。由圖可見,隨著體積分?jǐn)?shù)的升高,顆粒之間的平均自由程減表3 Chejne 等[3)實驗參數(shù)及數(shù)值模擬參數(shù)小,致使顆粒脈動減弱。Table 3 Parameters used for Chejne et al'!. and simulationsd 0.62 mmh.=1.0m符號物理意義文獻(xiàn)模擬q.≈21.9kg/sp./(kg. m-3)顆粒密度1 250p.=1250kgm'd./mm顆粒直徑0.62T。693Kq./(kg.h"')進(jìn)口空氣流量21.921.9q(H.O)-4.6kg/sq(H20)/(kg.h~")進(jìn)口水蒸氣流量4.64.6To/K進(jìn)口氣體溫度69393初始?xì)庀噘|(zhì)N2 =80.0,wo量分?jǐn)?shù)/%02 =20.0N.xN,網(wǎng)格數(shù)22x118中國煤化工04 0sAt時間步長/s5.0x10-*-.MYHCN M H G變化規(guī)律2.0x 10 -Fig.3 Total energy variation as a function of particle volume fraction