第31卷第3期燃料化學(xué)學(xué)報(bào)o1. 31 No. 32003年6月OURNAL OF FUEL CHEMISTRY AND TECHNOLOGY文章編號(hào):0253-240X200303-03004生物質(zhì)在超臨界水中熱解行為的初步研究曲先鋒,彭輝,畢繼誠(chéng),王錦風(fēng),孫東凱中國(guó)科學(xué)院山西煤炭化學(xué)研究所煤轉(zhuǎn)化國(guó)家重點(diǎn)實(shí)驗(yàn)室,山西太原03000摘要:在間歇式高壓反應(yīng)釜中考察了生物質(zhì)稻杄)在超臨界水中的熱解行為研究了熱解產(chǎn)物分布隨反應(yīng)溫度、壓力以及停留時(shí)間的變化規(guī)律。結(jié)果表明氣體收率隨溫度升高而增加油收率則先增加后減少380℃-410℃產(chǎn)油量較大可達(dá)28.57%氣體收率和油收率隨壓力升高而增加殘?jiān)章蕜t明顯減小但當(dāng)壓力高于31.5MPa后油收率基本不再隨壓力的升高而變化氕氣體收率隨停留時(shí)間的延長(zhǎng)而增加油收率則先增加后減少。關(guān)鍵詞:生物質(zhì);超臨界水;熱解中圖分類號(hào):TQ353.6文獻(xiàn)標(biāo)識(shí)碼:A生物質(zhì)作為一種化石燃料的替代能源由于其1,2實(shí)驗(yàn)裝置及實(shí)驗(yàn)過(guò)程實(shí)驗(yàn)所用反應(yīng)器為間具有二氧化碳零排放"效應(yīng)、低硫、資源廣泛和可歇式高壓反應(yīng)笠由不銹鋼材料制成體積為108mI再生性等特點(diǎn)越來(lái)越引起人們的重視。超臨界水裝料后密封反應(yīng)釜將反應(yīng)釜放入電爐中。升溫前〔簡(jiǎn)稱SCW湜一種溫度、壓力均高于其臨界溫度和用10MPa的N,進(jìn)行系統(tǒng)檢漏并置換反應(yīng)器中的空臨界壓水臨界溫度T。為374.3℃臨界壓力P為氣在常壓N,氣氛下加熱反應(yīng)釜。反應(yīng)釜用電爐加22.IMPa〕肭可壓縮性高密度流體具有良好的溶解熱反應(yīng)溫度和升溫速率由控溫儀來(lái)控制。反應(yīng)結(jié)特性和傳質(zhì)特性。在超臨界狀態(tài)下水的性質(zhì)更近束后打開(kāi)高壓閥,氣液產(chǎn)物在氣液分離器中分離,似于非極性有機(jī)溶劑可與大多數(shù)有機(jī)物和氣體互固體殘?jiān)粼诜磻?yīng)釜中。溶形成均相反應(yīng)環(huán)境1.3產(chǎn)物的分離和分析方法反應(yīng)產(chǎn)物經(jīng)氣液分超臨界水轉(zhuǎn)化生物質(zhì)是一個(gè)熱化學(xué)轉(zhuǎn)化過(guò)程,離后氣相產(chǎn)物中的H2、O2N2、CH、CO、CO2等永久目前國(guó)內(nèi)有關(guān)流化床中生物質(zhì)熱解氣化的報(bào)道較性氣體用SP-2305型氣相色譜儀熱導(dǎo)池檢測(cè)器)多3而在超臨界水中轉(zhuǎn)化的報(bào)道較少而國(guó)外檢測(cè);CH1及C2~C等烴類氣體采用sP-205有關(guān)生物質(zhì)在超臨界水中轉(zhuǎn)化的研究則主要集中在氣相色譜儀氫焰檢測(cè)器檢測(cè)。反應(yīng)器、管線和氣氣化及其模型化合物方面。本文主要考察生物液分離器中殘留產(chǎn)物經(jīng)四氫呋喃凊清洗與萃取質(zhì)在超臨界水中的熱解行為,方面為生物質(zhì)在超臨得到液相產(chǎn)物液相產(chǎn)物經(jīng)油水分離得到油品和水界水中氣化制氫提供參考信息一方面為探索生物相水相中留有的少量產(chǎn)物本文未做進(jìn)一步分析。質(zhì)在超臨界水中的轉(zhuǎn)化利用提供基礎(chǔ)數(shù)據(jù)。本文定義四氫呋喃可溶物為油品油品再經(jīng)正己烷實(shí)驗(yàn)部分萃取分為HX輕質(zhì)油品和H瀝青質(zhì))產(chǎn)物收11實(shí)驗(yàn)原料實(shí)驗(yàn)用生物質(zhì)為稻桿取自山西省率按下式計(jì)算太原市南郊稻桿的元素分析和工業(yè)分析見(jiàn)表1產(chǎn)物收率w%=產(chǎn)物g/稻桿gu×100%表1稻桿的元素分析和工業(yè)分析2結(jié)果與討論Table 1 Proximate and ultimate analyses of straw sample2.1溫度對(duì)產(chǎn)物分布的影響溫度對(duì)產(chǎn)物分布的Ultimate analyses Wa /%o影響見(jiàn)圖1,實(shí)驗(yàn)條件為6.6g稻桿3g水停留M ACH時(shí)間30min升溫速率10℃/mn~15℃/min。圖1表8.569.6682.7717.2349.825.470.410.9943.31明國(guó)煤化工的升高不斷增加油關(guān) by difference收率CNMHG減少380℃-410℃產(chǎn)收稿日期:2003-01-16;修回日期:2003-03-20基金項(xiàng)目:中國(guó)科學(xué)院百人計(jì)劃項(xiàng)目(01200020)作者簡(jiǎn)介萬(wàn)74)男山西五臺(tái)人碩士研究生從事生物質(zhì)在超臨界水中轉(zhuǎn)化的研究。Emil: xianren0im.m曲先鋒等:生物質(zhì)在超臨界水中熱解行為的初步研究油量較大可達(dá)28.57%。溫度對(duì)殘?jiān)章视绊懖淮?。a asphaltene生物質(zhì)的主成分為纖維素、半纖維素和木質(zhì)素纖維素、半纖維素是糖類高聚物木質(zhì)素是酚類高聚物其在亞臨界、超臨界水中主要發(fā)生水解反應(yīng)和熱315解反應(yīng)5-81生物質(zhì)通過(guò)水解反應(yīng)主要形成液相產(chǎn)縱主要為大分子物質(zhì))并且釋放出小分子氣體而水解產(chǎn)物大分子物質(zhì)可進(jìn)一步經(jīng)過(guò)熱解反應(yīng)形成油和一些小分子氣體。低溫時(shí)亞臨界區(qū)冰解反應(yīng)為主反應(yīng)熱解反應(yīng)緩慢因而油品中的瀝青質(zhì)(大420Temperature t/C分子物質(zhì)率高輕油收率低。隨著反應(yīng)溫度的升蠃亞臨界區(qū))水解反應(yīng)進(jìn)一步增強(qiáng),氣體收率增圖2溫度對(duì)油組成的影響加同時(shí)熱解反應(yīng)加劇導(dǎo)致瀝青質(zhì)收率下降而輕油Figure 2 Effect of temperature on composition of oil收率增加兩者共同作用的結(jié)果是亞臨界區(qū)內(nèi)氣體收率和油收率隨反應(yīng)溫度的升高而增加。當(dāng)溫度繼續(xù)升高至超臨界溫度區(qū)時(shí)隨著反應(yīng)溫度的升高熱解反應(yīng)急劇增強(qiáng)成為過(guò)程中的主反應(yīng)瀝青質(zhì)收率繼續(xù)下降,輕油收率繼續(xù)增加,體系中油品收率隨a8EE溫度升高而增加在380℃~400℃時(shí)油收率達(dá)到最大而熱解形成的一些小分子產(chǎn)物則以氣體形式0.5CO2、CO、HlCH和一些小分子烴類脫出導(dǎo)致氣體收率不斷增加。當(dāng)溫度高于380℃時(shí)水解反應(yīng)Temperature t/℃速率明顯大于近超臨界和超臨界溫度下的反應(yīng)速率9熱解反應(yīng)也十分劇烈可在相對(duì)較短的時(shí)間內(nèi)圖3溫度對(duì)氣體組分產(chǎn)量的影響完成生物質(zhì)的熱解,剩余時(shí)間內(nèi)熱解產(chǎn)物中的大分Figure 3 Effect of temperature on gas products子物質(zhì)瀝青質(zhì)和輕油發(fā)生分解導(dǎo)致瀝青質(zhì)收率隨溫度的變化較大為氣體的主要組成這是由于纖繼續(xù)下降而輕油收率也開(kāi)始下降油收率隨溫度的維素、半纖維素和木質(zhì)素等大分子物質(zhì)的結(jié)構(gòu)主要升高而下降氣體收率則繼續(xù)上升見(jiàn)圖1、圖2。瀝是以低能量的O-CH3及O—R鍵的形式相連0,青質(zhì)經(jīng)熱解能產(chǎn)生氣體以320℃產(chǎn)生的瀝青質(zhì)為實(shí)而這些鍵的水解是超臨界水中的主要反應(yīng)其后發(fā)驗(yàn)原料在450℃反應(yīng)得到氣油和渣。溫度對(duì)各種氣體組分產(chǎn)量的影響見(jiàn)圖3。CO2生脫—C00反應(yīng)所致。H、CH和C2~C的產(chǎn)量隨溫度升高增加較小,當(dāng)高于臨界溫度時(shí)隨溫度的變化較為明顯?！鰃as2.2壓力對(duì)產(chǎn)物分布的影響實(shí)驗(yàn)通過(guò)改變加水▲ residue量調(diào)節(jié)系統(tǒng)壓力壓力對(duì)產(chǎn)物分布的影響見(jiàn)圖4。實(shí)驗(yàn)條件為6.6g稻桿、反應(yīng)溫度430℃停留時(shí)間30min升溫速率10℃/min~15℃/min。圖4表明氣體收率隨壓力升高增加較快低壓段油收率增加緩R慢』V凵中國(guó)煤化工收率基本不隨壓力的升高CNMHG力升高明顯減少生物質(zhì)在超臨界水中熱解時(shí)水為反應(yīng)介質(zhì)壓力升高水密度增加有利于水解反應(yīng)的進(jìn)行因而瀝圖1溫度對(duì)產(chǎn)物分布的影響FE isotemperature on product distribution of str青質(zhì)大分子物質(zhì))的收率隨壓力的升高不斷增加而輕油的收率隨壓力的升高先增加后降低見(jiàn)圖5232燃料化學(xué)學(xué)報(bào)10Pressure P/MPa圖4壓力對(duì)產(chǎn)物分布的影響圖6壓力對(duì)氣體組分產(chǎn)量的影響Figure 4 Effect of pressure on product distribution of strawFigure 6 Effect of pressure on gas products2.3停留時(shí)間對(duì)產(chǎn)物分布的影響停留時(shí)間對(duì)反應(yīng)產(chǎn)物分布的影響見(jiàn)圖7。實(shí)驗(yàn)條件為為.6g稻桿、溫度430℃加水量53mL升溫速率10℃/min~15℃/mino圖7表明停留時(shí)間對(duì)氣體收率和油收率影響較大停留時(shí)間越長(zhǎng),氣體收率越高停留時(shí)間對(duì)油收率的影響有一最佳值殘?jiān)章孰S停留時(shí)間的增加而略Pressure p/MPa▲ residue圖5壓力對(duì)油組成的影響Figure 5 Effect of pressure on compositon of oil這可能是由于在超臨界狀態(tài)下水的H0鍵受壓縮,水分子間相互結(jié)合成籠”,將反應(yīng)中間體嵌在籠內(nèi),升高壓力使得水溶劑的籠效應(yīng)增強(qiáng),輕油的生成受阻同時(shí)輕油的分解加劇所致。瀝青質(zhì)和輕油的變化導(dǎo)致油收率隨壓力的升高而增加到圖7停留時(shí)間對(duì)產(chǎn)物分布的影響壓力高于31MPa后基本不再變化。此外水解反應(yīng)Fgre7 Effect of reaction time on product distribution of straw產(chǎn)生的液相產(chǎn)物經(jīng)超臨界水萃取能得到更好的分散進(jìn)而熱解產(chǎn)生油和小分子的氣體因而氣體收率asphaltene隨壓力升高而增加殘?jiān)章蕼p少殘?jiān)鼫p少的另原因是超臨界水對(duì)焦炭的形成有阻礙作用,該阻礙15作用可能是由于超臨界水能萃取并分散產(chǎn)生焦炭的前體中間體所致壓力對(duì)各種氣體組分產(chǎn)量的影響見(jiàn)圖6。CO中國(guó)煤化工仍然是氣體的主要組分其收率隨壓力升高而增加CNMHG主要是由于壓力升高有利于水解反應(yīng)的進(jìn)行。HReaction time (/min產(chǎn)量隨壓力升高線性增加,CO隨壓力的升高而降低表明增加水密度有利于超臨界水體系中水煤氣圖8停留時(shí)間對(duì)油組成的影響變換反應(yīng)的內(nèi)Figure 8 Effect of reaction time on composition of oil曲先鋒等∶生物質(zhì)在超臨界水中熱解行為的初步研究233有下降。這是由于在一定的溫度和壓力條件下,反輕油的分解反應(yīng)占主導(dǎo)優(yōu)勢(shì)產(chǎn)生小分子氣體等物質(zhì)應(yīng)時(shí)間越長(zhǎng)反應(yīng)越充分氣體收率和油收率隨停留導(dǎo)致氣體收率繼續(xù)增加而油收率下降見(jiàn)圖8氣相產(chǎn)時(shí)間的延長(zhǎng)而增加,但當(dāng)停留時(shí)間超過(guò)一定時(shí)間物中隨停留時(shí)間的延長(zhǎng),O,增加H略有增加。(約30min后生物質(zhì)的熱解反應(yīng)趨于結(jié)束瀝青質(zhì)及參考文獻(xiàn)[1]郭建維,宋曉銳,崔英德.流化床反應(yīng)器中生物質(zhì)的催化裂解氣化研究J]燃料化學(xué)學(xué)報(bào),2001,294)319-322.( GUO Jian-wei, SONG Xiao-rui, CUI Ying-de. Catalytic pyrogasification of biomass in a fluidized-bed reactor J ] Jounal of FuelChemistry and Technology 2001, 204)319-322.)[2]王智微,唐松濤,蘇學(xué)泳,等,流化床中生物質(zhì)熱解氣化的模型硏究J燃料化學(xué)學(xué)報(bào),200,30(4)342-346(WANG Zhi-wei, TANG Song-tao, SU Xue-yong et al. A study on model for biomass pyrolysis and gasification in fluidized bed[J]. Journal of Fuel Chemistry and Technology, 2002, 304)342-346.)[3]蘇學(xué)泳,王智微,程從明,等.生物質(zhì)在流化床中的熱解和氣化研究J]燃料化學(xué)學(xué)報(bào),2000,284)298-305.SU Xue-yong, WANG Zhi-wei, CHENG Cong-ming, et al. Study on biomass pyrolysis and gasification in fluidized bed J]Journal of Fuel Chemistry and Technology 2000, 28 4 )298-305.)[4] X H Hao, L J Guo, X M. Hydrogen production from glucose used as a model compound of biomass gasified in supercritical water[J]. Intemational Journal of hydrogen energy 2003, 28 1)55-64[5] Kabyemela B M, Adschiri T. Glucose and fructose decomposition in subcritical and supercritical water: Detailed reaction pathmechanisms and kinetic J ] Ind Eng Chem Res, 1999, 388)2888-2892[6] Kabyemela B M, Adschiri T, Malaluan R M. Kinetics of glucose epimerization and decomposition in subcritical and supercritical wa-tet J ] Ind Eng Chem Res, 1997, 35): 1552-1558[7] Kabyemela, Takigawa, Adschiri T. Mechanism and kinetics of cellobiose decomposition in sub-and supercritical watet J ]. Ind EngChem res,1998,372)357-36l[8] Tadafumi Adschiri, Satoru Hirose. Noncatalytic conversion of cellulose in supercritical and subcritical watet J ]. Jounal of ChemicalEngineering of Japan, 1993, 26)676-680[9] Holgate H R, Meyer J C, Teater J W. Glucose hydrolysis and oxidation in supercritical watet J ] AlChE J, 1995, 413)237-648[10]蔣挺大編著.木質(zhì)氪M]北京:化學(xué)工業(yè)出版社2001(JIANG Ting-da. Lignirt M ]. Beijing: Chemical Industry Press, 200111] Labrecque R S, Kaliaguine, Grandmason J L. Supercritical gas extraction of wood with methano[ J ] Ind Eng Chem prod Resx1)177-18012 Modell M. Gasification and Liquefaction of Forest Products in Supercritical Water, Foundamentals of Thermochemical Biomass Conversion M]. Elsevier, Amsterdam, 1985.95-96PYROLYSIS BEHAVIOUR OF BIOMASS IN SUPERCRITICAL WATERQU Xian-feng, PENG Hui, BI Ji-cheng WANG Jin-feng, SUN Dong-kaiState Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences Taiyuan 030001, ChinaAbstract Straw pyrolysis in supercritical water was studied using a high-pressure batch autoclave. The effects of temperature, pressure and reaction time on the distribution of pyrolysis products were examined. Results indicate that theyield of gas and oil increased with increasing temperature at first and then oil yield decreased. The highest oil yield28.57% was reached from 380C to 410C. The yield of gas and oil increased with increasing pressure while the yieldof residue decreased notably. When pressure is higher than 31. 5M中國(guó)煤化工 vary with pressure.Theyield of gas increased with reaction time and the yield of oil inciCNMH GreasedKey words: biomass i pyrolysis i supercritical waterFoundation item: Project of ACS Hundred Talents(0120002202)Author introduction: QU Xian-feng( 1974- ), male, Master Student engaged in biomass conversion in supercritical water