第43卷第4期熱力發(fā)電Vol 43 No 42014年4月THERMAL POWER GENERATIONApr.2014執(zhí)管式生物質(zhì)氣化爐間接氣化模擬砑究馮亮,張紅,王中賢,沈妍,于萍(南京工業(yè)大學(xué)能源學(xué)院,江蘇南京211816)[摘要]建立了熱管式生物質(zhì)氣化爐間接氣化的動力學(xué)模型,研究氣化溫度和水蒸氣與生物質(zhì)添加量之比(簡稱為S/B)對氣體組分、熱值和氣體總產(chǎn)率的影響。結(jié)果表明:H2和CO的體積分?jǐn)?shù)隨著氣化溫度的升高而增加,CO2的體積分?jǐn)?shù)隨著溫度的升高而減少;增加S/B有利于H2和CO2的產(chǎn)生,不利于CO的生成;生物質(zhì)氣化氣體產(chǎn)物中H2的體積分?jǐn)?shù)在50%~60%之間時(shí),氣體熱值可高達(dá)10MJ/m3。[關(guān)鍵詞]熱管;生物質(zhì);氣化爐;動力學(xué)模型;體積分?jǐn)?shù);熱值[中圖分類號]TK6[文獻(xiàn)標(biāo)識碼]A[文章編號]10023364(2014)04-0059-04[DOI編號]10.3969/j.issn.10023364.2014.04.059Simulation of indirect gasification in heat pipe biomass gasifierFENG Liang, ZHANG Hong, WANG Zhongxian, SHEN Yan, YU PingCollege of Energy, Nanjing University of Technology, Nanjing 211816, ChinaAbstract: Dynamical model of indirect gasification in heat pipe biomass gasifier was set up to studythe effect of temperature and steam/ biomass mass ratio on gas composition, heat value and gasyield. The results show that, with an increase in gasification temperature, the volume fraction ofH2 and CO monoxide increased greatly, while that of CO2 decreased. An increase in steam/biomassmass ratio was beneficial to production of H2 and cO2, but not to co. the heat value of the prod-uct gas could reach 10 MJ/m when the percentage of H2 in it ranged from 50% to 60%Key words: heat pipe; biomass; gasifier; dynamical model; volume percentage; heat value生物質(zhì)氣化是通過熱化學(xué)反應(yīng)將可再生生物質(zhì)能轉(zhuǎn)換為清潔氣體燃料的過程,是可再生能源開發(fā)1幾何模型利用的重要方向。目前,生物質(zhì)氣化一般采用空試驗(yàn)裝置如圖1所示。生物質(zhì)從側(cè)面進(jìn)入氣化氣或者空氣水蒸氣作為氣化劑,由于空氣中的氮?dú)鉅t,過熱水蒸氣作為氣化介質(zhì)通過分布板進(jìn)入氣化降低了氣化產(chǎn)物的熱值2,而以水蒸氣作為氣化劑爐,高溫?zé)峁茉谌紵覂?nèi)的一端為吸熱段,在氣化爐的間接供熱氣化技術(shù)(是獲得高熱值氣的有效途內(nèi)的一端為放熱段,將燃燒室的熱量傳入氣化爐,為徑。間接供熱氣化爐包括載體供熱式潛熱沙囊式、生物質(zhì)和水蒸氣的間接氣化提供反應(yīng)熱,氣化產(chǎn)物壓力熱管式等4。熱管作為一種高效的傳熱方式,通過燃?xì)獬隹谂懦觥饣癄t模型直徑100mm,以其優(yōu)良的傳熱性能在工業(yè)生產(chǎn)的不同領(lǐng)域中得到高1000mm,徑向共布置5排,每排4根直徑了廣泛應(yīng)用。本文建立了熱管式生物質(zhì)氣化爐25mm,長37mm,傾角45°的高溫?zé)峁?。間接氣化的動力學(xué)模型,分析了氣化溫度和S/B對采用Tet/ Hybrid劃分網(wǎng)格(圖2),總網(wǎng)格數(shù)量出口氣體組分、熱值和氣體總產(chǎn)率的影響。約為1.2×105。生物質(zhì)選稻草,物料特性見表1。收稿日期:2013-0401作者簡介:馮亮(1988-)男,江蘇徐州人,碩士研究生,研讀方向?yàn)闊峁芗夹g(shù)的研究與利中國煤化工Er-mail:hotfengliang@126.comCNMHG熱力發(fā)電2014年燃燒室高溫?zé)峁軋D2模型網(wǎng)格劃分Fig 2 Mesh generation生物質(zhì)圖1熱管式生物質(zhì)氣化爐結(jié)構(gòu)示意表1稻草的工業(yè)和元素分析Table 1 Proximate and ultimate analysis of the straw工業(yè)分析/元素分析/%低位熱值水分灰分揮發(fā)分固定碳C8.7516.426113.1832.3174.62336.9910.8892數(shù)學(xué)模型CO2、CH4和H2O。假設(shè)模擬過程是一個(gè)單相化學(xué)模型假設(shè)生物質(zhì)在高溫環(huán)境下迅速熱解,僅考反應(yīng),將固定碳的反應(yīng)轉(zhuǎn)化成氣體均相反應(yīng)模型進(jìn)慮氣體和焦炭的產(chǎn)生;把焦炭作為氣相考慮;氣化過行研究。程主要考慮CO、H2、CO2、CH4、C和H2O6種氣相由于氣化爐內(nèi)湍流運(yùn)動十分強(qiáng)烈,本文不考慮成分;無滑移等溫壁面條件反應(yīng)時(shí)氣體間的傳熱和混合問題,認(rèn)為氣相間的反應(yīng)完全由反應(yīng)動力學(xué)因素控制,所有反應(yīng)作為二級1控制方程反應(yīng)處理。氣體均相反應(yīng)模型采用組分輸運(yùn)?；瘜W(xué)反應(yīng)的存在增加了連續(xù)性方程動量方程、型;湍流采用標(biāo)準(zhǔn)湍流模型;化學(xué)反應(yīng)為容積反應(yīng)組分輸運(yùn)方程的源項(xiàng)和能量方程的反應(yīng)熱項(xiàng),因此速率采用有限速率/渦耗散模型;采用P1模型描述質(zhì)量、動量、組分及能量方程應(yīng)為7輻射傳熱過程。主要化學(xué)反應(yīng)為.u=(1)C+H2O→CO+H2(5)atC+CO2→→2COo2+v(auu)=-Vp+V(uVu)t Sm(2)C+2H2→CH4(7)aV(Y)+SY,=+(pD,V(Y))(3)CO+H2O→CO2+H2(8)9(H)CH4+H2O→CO+3H2at t V(auh)= v(vT)+s, (4)各化學(xué)反應(yīng)的動力學(xué)參數(shù)見表2910式中,Y1、D、a1分別為組分的質(zhì)量分?jǐn)?shù)、擴(kuò)散系數(shù)、生成速率,Sb、Sn、Sn分別為質(zhì)量源項(xiàng)、動量源項(xiàng)、能表2化學(xué)反應(yīng)動力學(xué)參數(shù)量源項(xiàng)。Table 2 Kinetic parameters of the chemical reaction化學(xué)反應(yīng)頻率因子K/s-1活化能E/(kJ·mol-1)2.2化學(xué)反應(yīng)模型式(5)1.214×105生物質(zhì)氣化化學(xué)反應(yīng)包括揮發(fā)分析出、氣體均式(6)5.55×1033.061×10相反應(yīng)、氣固異相反應(yīng)3個(gè)過程。由于流化床傳熱式(7)0.2082.33×105速率高,生物質(zhì)揮發(fā)分析出的時(shí)間比氣化反應(yīng)短很式(8)2.978×10123.695×105多,故假設(shè)生物質(zhì)進(jìn)入流化床后立刻揮發(fā),熱解剩余H式(9)中國煤化工1.68×102物僅含有固定碳,熱解氣體產(chǎn)物主要考慮CO、H2、CNMHGhttp:/www.rlfd.comcnhttp://rlfd.periodicalsnet.cn4期馮亮等熱管式生物質(zhì)氣化爐間接氣化模擬研究3計(jì)算結(jié)果及分析是因?yàn)榇矊訙囟妊貧饣癄t軸向逐漸升高,反應(yīng)式(5)、式(6)式(9)向消耗CO2、CH4生成H2、CO的3.1床溫和氣體分布方向進(jìn)行,使得H2的質(zhì)量分?jǐn)?shù)不斷增加,而CO2和選取生物質(zhì)流量為0.4kg/h,蒸汽量為CH4的質(zhì)量分?jǐn)?shù)不斷減小。擴(kuò)散對沿氣化爐徑向0.8kg/h,不同氣化溫度下的1組工況進(jìn)行計(jì)算,研究床層溫度對生物質(zhì)氣化的影響。工況參數(shù)見表氣體組分含量的影響較小。3,工況4的床層溫度和主要?dú)怏w在床內(nèi)的分布情況表3溫度變化工況如圖3所示。由圖3可見,床層溫度沿軸向快速升Table 3 The temperature conditions高到1070K左右,基本滿足所需要的氣化溫度,徑項(xiàng)目工況1工況2工況3工況4工況5工況6工況7向溫差隨著床層高度的增加趨于平均;氣化爐內(nèi)反應(yīng)溫度65070075080085090095、CO含量沿軸向逐漸增大,CO2、CH4含量沿軸向逐漸減小,沿徑向氣體組分含量的變化很小。這1.09e+031.05c+03!溫h!體!自1.04e+033.03e-021.65e-027.61e01.03e+07.22e-023.02e-021.56e.01.02e+033.02e-021.0le+03.01e-021.36e-026.43e-029.98e+0126e.026.04e.03.00e-021.16e-025.65e-09.75e+01.06e-029.64e+09.6le-09.53c+04.47e-094le+04.08e-027.63e-036.64e039.19e+023.29e-022.96e-0265e-033.29e-028.96e+028.85e+022.12e-022.68e-08.74e+021.73e-022.94e-021.73e.0263e+02133e-022.94e021.33e02(a)床層溫度T/K(b)Co/%(c)CO2/%(d)CH4/%(e)H2/%圖3工況4床層溫度和氣體組分分布Fig 3 Distribution of the(a)bed temperature and concentration of(b)co(c)co2(d )CH(e)H, under condition 43.2床溫對氣化結(jié)果的影響在50%~60%之間,成增長趨勢,CO2體積分?jǐn)?shù)不圖4為工況1-7氣體產(chǎn)物體積分?jǐn)?shù)隨床層溫?cái)鄿p小,CO體積分?jǐn)?shù)不斷增大,CH4體積分?jǐn)?shù)較度的變化情況。低,隨溫度變化不明顯。H CH圖5為床層溫度對氣體熱值和總產(chǎn)率的影響。12.011.5氣體熱值一氣體總產(chǎn)率爾勺票3=11.00.6650700750800850900950度℃650700750800850900950溫度/C圖4床層溫度對氣體組分的影響Fig 4 Effect of bed temperature on gas compositions圖5床層溫度對氣體熱值和氣體總產(chǎn)率的影響中國煤化工reon由圖4可見,隨著床溫的升高,H2的體積分?jǐn)?shù)CNMHGe gashttp:lwww.rlfd.comcnhttp://rlfd.periodicals.net.cn熱力發(fā)電2014年由圖5可見,氣體熱值和總產(chǎn)率隨床層溫度升高逐漸增大,其中床層溫度低于800℃時(shí)氣體總產(chǎn)10.4率上升快,高于800℃時(shí)較平緩?？梢?床溫在800氣體總產(chǎn)率℃時(shí),氣化效果較好。10.23.3S/B對氣化結(jié)果的影響反應(yīng)溫度為800℃C,生物質(zhì)量流量0.4kg/h10.0旦柵禮址改變S/B的1組工況見表4表4不同S/B計(jì)算工況Table 4 Calculation conditions withdifferent steam/biomass mass ratios項(xiàng)目工況8工況9工況10工況11工況12圖7S/B對氣體熱值和總產(chǎn)率的影響S/BFig. 7 Effect of steam/ biomass mass ratio on蒸汽流量、0.40.81.2heat value and total yield of the ga/(kg·h-l)1.64結(jié)論圖6為氣體產(chǎn)物體積分?jǐn)?shù)隨S/B的變化情況。由圖6可見,隨S/B的增加,H2體積分?jǐn)?shù)緩慢增大(1)在熱管式生物質(zhì)氣化爐的氣化工程中H(約55%),CO體積分?jǐn)?shù)快速下降,而CO2體積分CO的體積分?jǐn)?shù)、氣體熱值和氣體總產(chǎn)率隨著氣化數(shù)快速上升。這主要是因?yàn)殡S著S/B的增加參與溫度的升高而升高,CO2的體積分?jǐn)?shù)隨著氣化溫度反應(yīng)的水蒸氣量增大,水蒸氣分壓力增大水蒸氣重的升高而下降,CH4基本上不隨溫度的變化而變整變換反應(yīng)和CH4蒸汽重反應(yīng)向正方向移動,所以化。從氣體熱值氣體總產(chǎn)率氣化組成綜合考慮,CO和CH,的體積分?jǐn)?shù)減少,而CO2和H2的體積氣化溫度為800C時(shí)氣化效果較好分?jǐn)?shù)增加。(2)H2、CO2的體積分?jǐn)?shù)、氣體總產(chǎn)率隨著S/B的增加而增加,CO體積分?jǐn)?shù)、氣體熱值隨著S/B的增加而降低,從氣體熱值、氣體總產(chǎn)率、氣體組成綜合考慮,S/B在2~3時(shí),氣化效果較好[參考文獻(xiàn)][1]吳創(chuàng)之,馬隆龍.生物質(zhì)能現(xiàn)代化利用技術(shù)[M].北京化學(xué)工業(yè)出版社,2003WU Chuangzhi, Ma Longlong. 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