第30卷第23期農(nóng)業(yè)工程學(xué)報(bào)VoL, 30 No. 2014年12月Transactions of the Chinese Society of Agricultural EngineeringDec.2014生物質(zhì)氣化尾氣CO2聯(lián)合微波重整甲苯制備合成氣李龍之1,宋占龍2,馬春元2,王孚懋1,田原宇3(1.山東科技大學(xué)機(jī)械電子工程學(xué)院,青島266590;2.山東大學(xué)燃煤污染物減排國(guó)家工程實(shí)驗(yàn)室,濟(jì)南2500613.山東科技大學(xué)化學(xué)與環(huán)境工程學(xué)院,青島266590)摘要:該文以甲苯為焦油模型化合物,利用生物質(zhì)焦炭誘導(dǎo)其轉(zhuǎn)化合成氣,探討加熱方式和通入CO2對(duì)甲苯轉(zhuǎn)化的影響。結(jié)果表明:同等工況下,微波加熱( microwave heating,MH)下甲苯轉(zhuǎn)化率高于常規(guī)加熱( electricalheating,EH),甲苯轉(zhuǎn)化率最大差值為15.58%。通入CO2可促進(jìn)甲苯轉(zhuǎn)化,MH和EH下分別在CO2流量為80和40mL/min達(dá)到最高轉(zhuǎn)化率93.73%和82.13%。引入CO2可調(diào)控甲苯定向制備合成氣,且對(duì)生物質(zhì)焦炭造成碳損耗。損耗碳可轉(zhuǎn)化合成氣,且CO2通入量越高,其貢獻(xiàn)越大。MH下合成氣最大產(chǎn)率為173.66 mL/min,為裂解反應(yīng)的5.68倍。甲苯裂解率持續(xù)降至49,0%,之后趨于穩(wěn)定。甲苯重整轉(zhuǎn)化率維持較高水平,140min后開(kāi)始減弱,同時(shí)合成氣收率平緩降低。該文研究結(jié)果對(duì)高效利用焦油和減排CO2有借鑒意義。關(guān)鍵詞:微波;重整反應(yīng);焦油;合成氣;生物質(zhì)焦炭doi:10.3969jisn.1002-6819201423.034中圖分類(lèi)號(hào):TK91文獻(xiàn)標(biāo)識(shí)碼:文章編號(hào):1002-6819(2014)-23-0268-07李龍之,宋占龍,馬春元,等.生物質(zhì)氣化尾氣CO2聯(lián)合微波重整甲苯制備合成氣[J]農(nóng)業(yè)工程學(xué)報(bào),2014Li Longzhi, Song Zhanlong, Ma Chunyuan, et al. Toluene reforming by carbon dioxide recycled from biomassgasification into syngas production under microwave irradiation[J]. Transactions of the Chinese Society of AgriculturalEngineering(Transactions of the CSAE), 2014, 30(23): 268--274(in Chinese with English abstract)0引言研究人員將微波技術(shù)運(yùn)用到焦油轉(zhuǎn)化過(guò)程67。結(jié)果表明,微波加熱可以提高焦油轉(zhuǎn)化率,對(duì)改善產(chǎn)物焦油作為生物質(zhì)氣化的伴生產(chǎn)物,會(huì)惡化產(chǎn)氣選擇性和脫除積碳也有良好效果品質(zhì)。所以,如何脫除焦油并利用其能量是生物質(zhì)生物質(zhì)氣相產(chǎn)物中通常含有體積分?jǐn)?shù)為研究領(lǐng)域的熱點(diǎn)。眾多技術(shù)中,催化裂解和重整是10%~30%的CO2,會(huì)加大氣化產(chǎn)氣后續(xù)利用的脫最有潛力的方式之一5。目前,焦油催化裂解的氣碳成本。因此,部分研究者利用CO2對(duì)焦油進(jìn)行轉(zhuǎn)相產(chǎn)物主要為H2,并且由于積碳問(wèn)題使得制氫收率化利用。彭軍霞等研究發(fā)現(xiàn),CO2氣氛下甲苯轉(zhuǎn)化不穩(wěn)定。焦油重整多為蒸汽重整,所制合成氣率比N2氣氛下提高了1.2%,但該研究未對(duì)重整(H2+CO)中HCO比值較高。催化焦油轉(zhuǎn)化通常產(chǎn)物特性和催化劑碳損耗進(jìn)行深入分析?？酌偷壤褂锰烊坏V石、堿金屬、過(guò)渡金屬及金屬負(fù)載催化用 Ni/MnO-MgO催化CO2重整甲苯31,570℃下劑等1。但是上述催化劑均存在不同程度的問(wèn)題甲苯轉(zhuǎn)化率為90%,但所用催化劑為金屬催化劑,成為制約焦油催化轉(zhuǎn)化的瓶頸。基于此,研究者利制備成本較高而且使用的加熱方式為常規(guī)加熱,并用炭材料如焦炭、木炭、活性炭和生物質(zhì)焦炭等催未涉及微波加熱下甲苯轉(zhuǎn)化特性的相關(guān)研究。化焦油轉(zhuǎn)化612。研究表明炭材料具有多孔結(jié)構(gòu)以基于上述分析,本文選擇焦油中芳香環(huán)結(jié)構(gòu)并及灰分中包含具備催化焦油轉(zhuǎn)化的K、Mg和Na等且含量極高的甲苯為焦油模型化合物,以生物質(zhì)微金屬物質(zhì),使得炭材料具備了催化焦油轉(zhuǎn)化的有利波熱解的固相產(chǎn)物-生物質(zhì)焦炭為催化劑和吸波介條件。同時(shí),基于炭材料對(duì)微波的良好吸收特性質(zhì),利用氣化氣中富含的CO2對(duì)甲苯催化重整定向收稿日期:201406-28修訂日期:2014-11-01制備合成氣,實(shí)現(xiàn)CO2減排利用和焦油綜合處置的基金頊目:山東省優(yōu)秀中青年科學(xué)家科研獎(jiǎng)勵(lì)基金(BS20INJo0):雙重目的,并且更容易調(diào)控所制合成氣的氫碳比山東科技大學(xué)人才引進(jìn)科研啟動(dòng)基金(2013RCJ018)作者簡(jiǎn)介:李龍之,男,山東壽光人,講師,博士,主要從事新能源利本文利用生物質(zhì)焦炭誘導(dǎo)甲苯轉(zhuǎn)化,降低了催化劑用及燃煤污染物減排方面的研究。青島山東科技大學(xué)機(jī)械電子工程學(xué)制備成本,實(shí)現(xiàn)了生物質(zhì)熱解產(chǎn)物的高值利用,并院熱能系,266590。Email;lilongzhie30@163.com.且將微波技術(shù)用轉(zhuǎn)化可降低甲苯轉(zhuǎn)化難度,※通信作者:宋占龍,男,山東壽光人,副教授,博士,主要從事固體膠棄物微波處置等方面的研究。濟(jì)雨山東大學(xué)燃煤污染物減排國(guó)家工提高甲苯轉(zhuǎn)化中國(guó)煤化工整甲苯過(guò)程程實(shí)驗(yàn)室,250061。 Email: zIsong(asdu. edu.cr甲苯轉(zhuǎn)化程度CNMHG耗特性,以李龍之等:生物質(zhì)氣化尾氣CO2聯(lián)合微波重整甲苯制備合成氣期為生物質(zhì)氣化焦油的綜合利用及減排CO2提供了有限公司)加熱床料,床層溫度通過(guò)熱電偶檢測(cè),思路溫控由可編程智能系統(tǒng)執(zhí)行。微波加熱試驗(yàn)裝置同試驗(yàn)部分樣使用wL-3S型微波源,通過(guò)調(diào)節(jié)微波輸出功率1.1生物質(zhì)焦炭制備和表征大小來(lái)控制床層溫度,遠(yuǎn)紅外測(cè)溫儀用熱電偶校正選擇玉米秸稈作為制炭材料,材料經(jīng)過(guò)沖洗后用來(lái)測(cè)量床層溫度。重整試驗(yàn)使用的立式石英管干燥、粉碎及過(guò)篩等前期處理后,每次稱(chēng)取20g狀反應(yīng)器幾何尺寸為Φ40mm×200mm,生物質(zhì)焦裝入水平管式石英容器,然后在自主研發(fā)的微波熱炭均勻分布在距離底部40mm的布風(fēng)板上試驗(yàn)系解裝置上進(jìn)行炭化處理。該裝置的微波源為統(tǒng)的附屬部分還包括反應(yīng)物流量精確控制裝置wL-3S型微波源(南京三樂(lè)微波技術(shù)有限公司(D07-19B流量控制器)、氣體產(chǎn)物的后續(xù)冷凝干功率0~3kW連續(xù)可調(diào)。利用微波加熱裝置附帶燥裝置和氣體產(chǎn)物終端分析儀器( Clarus500GC)的溫控功能,在800℃的熱解終溫下對(duì)原料進(jìn)行充此外,甲苯蒸汽輸送管路均采取外包加熱帶的保溫分熱解(時(shí)間設(shè)定為30min),同時(shí)為改善所制措施,保證甲苯始終為蒸汽相態(tài)。焦炭的表面結(jié)構(gòu)特性,熱解過(guò)程中持續(xù)通入體積分結(jié)合試驗(yàn)系統(tǒng)示意圖(圖1),試驗(yàn)流程簡(jiǎn)述數(shù)為20%的水蒸汽,實(shí)現(xiàn)熱解炭制備與活化一體如下:稱(chēng)取6g生物質(zhì)焦炭密置于反應(yīng)器中,預(yù)先化。熱解結(jié)束后,取出固化成塊的熱解炭,通過(guò)洗通入流量為30mL/min高純N2,20min后開(kāi)啟微波滌干燥、機(jī)械破碎和粒度篩選等處理方式,選用平發(fā)生器,待床層溫度穩(wěn)定后將載氣和甲苯蒸汽通入均粒度為0.35m的焦炭作為焦油轉(zhuǎn)化催化劑并反應(yīng)器進(jìn)行試驗(yàn),通過(guò)集氣袋收集冷凝干燥后的氣密封儲(chǔ)存。利用美國(guó)麥克儀器公司生產(chǎn)的全自動(dòng)比體產(chǎn)物,在 Clarus500GC氣相色譜上對(duì)所收集的氣表面及孔隙度分析儀(型號(hào)為ASAP2020)獲得焦體產(chǎn)物進(jìn)行成分定量分析,色譜工作條件:載氣為炭比表面特性的相關(guān)數(shù)據(jù),灰分中元素的定量檢測(cè)N2和He,熱導(dǎo)檢測(cè)器( thermal conductivity detector在美國(guó)鉑金埃爾默公司生產(chǎn)的電感耦合等離子體DCT)和氫火焰離子化檢測(cè)器( flame ionization原子發(fā)射光譜儀(型號(hào)為 Optima7300V)上進(jìn)行, detector,FID)分別設(shè)定溫度為200和250℃。反樣品用HNO3與HF混合酸溶解體積比為2:1,靜應(yīng)出口的甲苯通過(guò)島津GC2010色譜儀對(duì)甲苯進(jìn)止過(guò)夜,消煮2h后用 ICP-AES測(cè)定元素含量。行檢測(cè),檢測(cè)柱為 Rtx-wax毛細(xì)柱,柱長(zhǎng)為300m,測(cè)試結(jié)果示于表1內(nèi)徑為0.25mm,固定液厚度為0.25/m。對(duì)取樣時(shí)表1生物質(zhì)焦炭特性間內(nèi)的產(chǎn)物作整體分析,而且試驗(yàn)采取了多次取樣Table 1 Characteristics of biomass char的方法,并且取標(biāo)準(zhǔn)偏差在±0.5%以?xún)?nèi)的3次結(jié)果物理待性pm數(shù)值lhe的均值作為最終結(jié)果布魯諾爾-艾米特泰勒比表面積為一·氣體樣品Brunauer-Emmett-Teller specific surface 39.00 Si/%0.008微孔比表面積 Microporous specific總孔容 Total pore volume/(cm3g2)微孔孔容 Micropore volume(mg)0.021平均孔徑 Average pore size/nm氣體樣品1322Mg%3.107Gas sampleAl%0.2440.0161.2試驗(yàn)材料、裝置及流程本文以體積分?jǐn)?shù)為99.5%的甲苯為焦油模型物并輸入蒸發(fā)瓶中,產(chǎn)生的甲苯蒸汽由載氣攜帶進(jìn)入1.氣瓶2.氣表3.開(kāi)關(guān)閥門(mén)4.蒸發(fā)器5.注射泵6.微波反應(yīng)反應(yīng)器,甲苯蒸發(fā)量的標(biāo)定后面單獨(dú)介紹。甲苯裂器7.石英反應(yīng)器8.濾盤(pán)9波導(dǎo)管10.過(guò)濾器11.冷凝器解試驗(yàn)載氣為N2,甲苯重整試驗(yàn)CO2不僅作為重1. Gas bottle2. Gas meter3 On-off wave4. Evaporator整介質(zhì),而且與N2作為聯(lián)合載氣使用。裂解和重Pump6 Icrowave reactor. Quartz reactor,s. leve plateguide 10. Filter 11. Water condenser 12. Microwave整試驗(yàn)中載氣總流量均為200 mL/min,甲苯在床料13. Infrared pyrometer層中的滯留時(shí)間控制在1.5s。甲苯轉(zhuǎn)化試驗(yàn)分別在常規(guī)加熱和微波加熱重整裝置上進(jìn)行。常規(guī)加熱裝Fig 1 Schemat中國(guó)煤化工 ed reformin置使用管式電爐(型號(hào)SK-G06143,天津中環(huán)電爐CNMHG270農(nóng)業(yè)工程學(xué)報(bào)2014年1.3甲苯蒸發(fā)量測(cè)試2.2CO2流量和加熱方式對(duì)甲苯轉(zhuǎn)化的影響準(zhǔn)確量取一定質(zhì)量的甲苯液體裝入蒸發(fā)器并2.2.1CO2流量和加熱方式對(duì)甲苯轉(zhuǎn)化的影響置于數(shù)顯加熱器,對(duì)其恒溫蒸發(fā)。通過(guò)減壓閥和流CO2通入流量和加熱方式對(duì)甲苯轉(zhuǎn)化率的影響量控制器調(diào)節(jié)載氣N2(或N2+CO2)的流通壓力與示于圖2。如圖2所示,MH作用下,當(dāng)CO2流量流量。蒸發(fā)測(cè)試分2階段:第Ⅰ階段,蒸發(fā)溫度從低于80mL/min,XcH;隨著CO2通入量的提高而遞室溫至設(shè)定溫度,停止加熱并測(cè)量甲苯剩余質(zhì)量增,CO2流量為80mL/min時(shí),X達(dá)到最高值(記為耵1);第Ⅱ階段,重新加熱并在蒸發(fā)溫度達(dá)93.73%,比甲苯裂解轉(zhuǎn)化率高出12.08%,此后繼續(xù)到設(shè)定值后繼續(xù)恒溫蒸發(fā),一段時(shí)間(T)后停止加大CO2通入量反而導(dǎo)致XCH降低,CO2流量為加熱,稱(chēng)取甲苯剩余質(zhì)量(記為W2)。120mL/min,Xc降至89.24%。由此說(shuō)明,通入1.4評(píng)價(jià)指標(biāo)合適流量的CO2能夠起到促進(jìn)甲苯轉(zhuǎn)化的作用。其本文利用轉(zhuǎn)化率(XCH,%)和合成氣產(chǎn)率(Ys,原因有2方面:一是CO2的通入使得甲苯同時(shí)參與mL/min)2個(gè)指標(biāo)評(píng)價(jià)甲苯轉(zhuǎn)化程度和合成氣生成裂解(式(4))和重整反應(yīng)(式(5)),且CO規(guī)律。上述指標(biāo)的計(jì)算依據(jù)與推導(dǎo)如下所示通入量的增加使得甲苯重整反應(yīng)加強(qiáng),促進(jìn)了XCHs轉(zhuǎn)化率:甲苯轉(zhuǎn)化率κμ按式(1)進(jìn)行計(jì)算。升高。二是CO2的引入能夠脫除部分積碳,可以減X。=-o×100%(1)弱積碳對(duì)焦炭表面特性的惡化,有利于甲苯轉(zhuǎn)化。CO2通入量超出80mL/min,Yc隨CO2流量增加式中:mm為初始甲苯的量,g:mot為剩余甲苯的而降低是因?yàn)樘紖⑴c氣化反應(yīng),且反應(yīng)程度隨CO2量,g通入量的增加而加強(qiáng),使得生物質(zhì)焦炭損耗加大,成氣產(chǎn)率:相比于金屬催化劑,焦炭誘導(dǎo)甲從而降低了焦炭對(duì)甲苯轉(zhuǎn)化的作用性能。所以,微苯重整過(guò)程中,除甲苯直接轉(zhuǎn)化合成氣,碳的氣化波輻照焦炭誘導(dǎo)甲苯重整過(guò)程中,焦炭損耗問(wèn)題不反應(yīng)也會(huì)生成部分CO,從而提高了合成氣產(chǎn)量可避免。同時(shí),碳通過(guò)氣化反應(yīng)產(chǎn)生一定數(shù)量的本文用合成氣產(chǎn)率Ys表征反應(yīng)體系的合成氣生成CO,對(duì)合成氣產(chǎn)率有直接貢獻(xiàn)。特性,具體計(jì)算參見(jiàn)式(2)。甲苯裂解反應(yīng)中合C7Hg→7C+4H成氣的組分主要是H2,而且不存在氣化反應(yīng),式(2)CnHg+7CO2→14CO+4H2(5)同樣適用Ys=Fo×(1,+qo)式中:Fou為氣態(tài)產(chǎn)物總生成量, mL/min:om:和gco分別為產(chǎn)物中H2和CO的體積比例,%。2結(jié)果與分析微波加熱 Microwave heating2.1甲苯蒸發(fā)量測(cè)試結(jié)果電加熱 Electrical heating利用式(3)得到單位時(shí)間內(nèi)甲苯平均蒸發(fā)量020406080100120W,測(cè)試參數(shù)和結(jié)果列于表2。需要指出的是,為CO2流量CO2 flow rate( mL min2)注:測(cè)試參數(shù)如下:溫度T為700℃:加熱時(shí)間t為20min。減小誤差同一蒸發(fā)試驗(yàn)重復(fù)進(jìn)行三次,所以測(cè)試結(jié)Note: Test parameters were as follows: Temperature is 700C; Heating time果為三次試驗(yàn)結(jié)果的平均值。后續(xù)甲苯轉(zhuǎn)化試驗(yàn)is20min.中,其蒸發(fā)值選定為0.0434gmin,折算流量為圖2CO2流量和加熱方式對(duì)甲苯轉(zhuǎn)化的影響Fig 2 Effect of CO2 flow rate and heating method on toluene10.57mL/min。W=(W1-W2)T(3)式中:T為恒溫蒸發(fā)時(shí)間,min。從圖2可發(fā)現(xiàn),相同工況MH作用下XCH明表2甲苯蒸發(fā)量測(cè)試結(jié)果顯高于EH,在CO2通入量為80mL/min時(shí)達(dá)到最Table 2 Results of toluene evaporatio大差值15.58%(P<0.001)。對(duì)此可從3方面分析N2壓力蒸發(fā)量1)微波輻照下,焦炭的表面弱鍵及缺陷位與微波Temperature/C N2 flow rateMPa(mL' min)發(fā)生的區(qū)域共振耦合傳能,導(dǎo)致床層能量分布不0.10.0308均,局部出現(xiàn)超熱區(qū)(即“執(zhí)點(diǎn)效應(yīng)”),“熱點(diǎn)效應(yīng)”也是中國(guó)煤化工測(cè)溫發(fā)現(xiàn)床0.0434層某些測(cè)點(diǎn)的CNMHG度,直接證李龍之等:生物質(zhì)氣化尾氣CO2聯(lián)合微波重整甲苯制備合成氣271實(shí)了“熱點(diǎn)效應(yīng)”的存在。2)微波誘導(dǎo)甲苯轉(zhuǎn)化碳物料守恒分析,結(jié)果列于表4。結(jié)合反應(yīng)前后碳過(guò)程中,存在著與溫度無(wú)關(guān)的“非熱效應(yīng)”,可以的質(zhì)量變化(式(7))量化氣化反應(yīng)對(duì)合成氣產(chǎn)導(dǎo)致反應(yīng)氣體化學(xué)鍵的減弱,從而降低反應(yīng)活化率的貢獻(xiàn),計(jì)算依據(jù)為重整積碳導(dǎo)致碳質(zhì)量增加能。3)微波加熱和焦炭催化可能存在協(xié)同效應(yīng),氣化消碳使得碳質(zhì)量減少,積碳/消碳過(guò)程盡管存在利于甲苯的轉(zhuǎn)化。作者初步分析認(rèn)為,“熱點(diǎn)效應(yīng)”“碳置換”,但兩者的綜合效果體現(xiàn)了碳質(zhì)量的變是MH能夠顯著增強(qiáng)甲苯的主導(dǎo)原因,今后需設(shè)計(jì)化程度,進(jìn)而根據(jù)氣化反應(yīng)的化學(xué)計(jì)量比可以得到試驗(yàn)對(duì)“熱點(diǎn)效應(yīng)”的作用機(jī)制進(jìn)行量化研究。彭碳?xì)饣磻?yīng)的CO產(chǎn)量。軍霞等和馮曉寧也認(rèn)為微波加熱下的“熱點(diǎn)效×1000應(yīng)”使得甲苯轉(zhuǎn)化率提高式中:mca表示反應(yīng)前后碳質(zhì)量變化的計(jì)算值,mg從圖2還可發(fā)現(xiàn),EH方式下隨著CO2流量的mcm為反應(yīng)入口甲苯和CO2中碳的總質(zhì)量,g;mcom提高,XC的增加幅度不如MH,這說(shuō)明EH下甲反應(yīng)出口甲苯、CO、CH4、C6H6和CO2等物質(zhì)中苯重整反應(yīng)程度不高。因此,CO2更多是參與氣化碳的總質(zhì)量,g反應(yīng),導(dǎo)致焦炭損耗更嚴(yán)重,從而使得EH下XCHc, measure=mn1n×Cim-mlut×Co×1000(7)在CO2流量為40mL/min時(shí)達(dá)到最大值82.13%,式中: c meas為反應(yīng)前后碳質(zhì)量變化的測(cè)試值,此后XCH開(kāi)始降低。mg;mn和mom分別為反應(yīng)前后焦炭質(zhì)量,g;C表3的數(shù)據(jù)表明,引入CO2對(duì)提升合成氣產(chǎn)率和Co分別是反應(yīng)前后焦炭中碳的質(zhì)量分?jǐn)?shù),%有積極作用,其原因是甲苯裂解的氣態(tài)產(chǎn)物主要是表4碳物料守恒分析結(jié)果H2,而CO2重整甲苯的產(chǎn)物以H2和CO為主,并Table 4 Carbon mass balance analysis results且等量甲苯通過(guò)重整反應(yīng)制得的合成氣產(chǎn)量明顯CO2流量O2 flow rate/(mL min)高于裂解反應(yīng)。表3顯示,CO2流量為80mL/min56923時(shí),Ys達(dá)到最高值173.66mL/min,此產(chǎn)率為裂解38.797,24反應(yīng)Fs的568倍。此后繼續(xù)提高CO2流量,XH4050.269.15反而有所降低,但其降低幅度很小。這是因?yàn)樘紖⑴c氣化反應(yīng)生成部分CO,緩解了XCH的降低對(duì)合成氣收率的不利影響。隨著CO2流量的加大,合成114.38氣氫碳比(Rco)持續(xù)降低。根據(jù)反應(yīng)(4)和(5)141.70141.5426.42的化學(xué)計(jì)量比,可求得RH2Co理論最小值為0.29注:Ksco為碳損耗對(duì)合成氣產(chǎn)率的貢獻(xiàn),綜合氣化反應(yīng)式(C+CO2=2CO和 c measure計(jì)算。mcsa為反應(yīng)前后碳質(zhì)量變化的計(jì)算值,mg; Ie measur表3顯示在CO2流量為100和120mL/min時(shí),R12Co反應(yīng)前后碳質(zhì)量變化的測(cè)試值,mg。測(cè)試參數(shù)如下:溫度T為700℃僅為0.28和0.2,這說(shuō)明部分CO為氣化反應(yīng)所制,加熱時(shí)間:為2mNote: Ys. co is contribution of syngas yield from carbon loss, which can be證實(shí)了氣化反應(yīng)對(duì)合成氣的貢獻(xiàn)。obtained by me, measure combined with gasification reaction(C+CO2=2CO表3微波加熱下CO2流量對(duì)合成氣的影響cal represents calculated changes of carbon mass before and after thereaction, with a unit of mg. me measure stands for measured changes of carbonTable 3 Effect of COz flow rate on syngas production under mass before and after the reaction, with a unit of mg. Test parameters weremicrowave heatingas follows: Temperature is 700C; Heating time is 20minCO2流量合成氣產(chǎn)率合成氣氫碳比對(duì)照表4的數(shù)據(jù)可發(fā)現(xiàn),甲苯裂解產(chǎn)生的碳不Syngas yield/ Ratio of H2 and CO in syngas(mL min(mL min)能消除,使得反應(yīng)后碳質(zhì)量的增幅為9.49%。CO2的導(dǎo)入使得氣化反應(yīng)程度強(qiáng)于積碳反應(yīng),表現(xiàn)為碳質(zhì)量的降低。而且,碳損耗隨著CO2通入量的增加而加大,CO2通入量為120mL/min時(shí),碳損耗率達(dá)到2.36%。對(duì)比mca和 mc measur可發(fā)現(xiàn),前者略高于后者,說(shuō)明前者計(jì)算過(guò)程忽略了一些低分子碳烴等,可能與儀器量程或測(cè)試誤差有關(guān)。甲苯重整體171.570.22測(cè)試參數(shù)如下:溫度T為700℃:加熱時(shí)間t為20min。系中,碳損耗直接貢獻(xiàn)了CO的生成,隨著CO2通Note: Test parameters were as follows: Temperature is 700 C: Heating time入量的提高,貢獻(xiàn)越大。CO2流量為120mL/min20時(shí),碳損耗貢獻(xiàn)的合成氣占總產(chǎn)率的15.4%。甲苯2.2.2甲苯轉(zhuǎn)化反應(yīng)體系碳物料守恒分析化工、CO、CH4進(jìn)一步通過(guò)式(6)對(duì)甲苯轉(zhuǎn)化反應(yīng)和YHMHG物還包括一272農(nóng)業(yè)工程學(xué)報(bào)2014年些未檢測(cè)到的低碳烴等。段(140~180min),Ys有所降低,這與甲苯轉(zhuǎn)化2.3微波加熱下甲苯裂解與重整特性比較率的降低有直接關(guān)系。此外,相比于XcH的降低趨本文對(duì)裂解和重整過(guò)程中κc灬的變化規(guī)律進(jìn)勢(shì),此階段Ys的降低趨勢(shì)更平緩,這是由于測(cè)試后行測(cè)試,結(jié)果反映于圖3。如圖3所示,裂解反應(yīng)期氣化反應(yīng)的發(fā)生緩解了XCH的降低對(duì)Ys的負(fù)面初期H在80%以上,此后隨反應(yīng)的進(jìn)行,XH,影響。圖4表明,裂解測(cè)試過(guò)程中Ys的降低趨勢(shì)顯的降低趨勢(shì)延續(xù)到150min,表明甲苯裂解反應(yīng)的著,這是因?yàn)樯镔|(zhì)焦炭失活嚴(yán)重制約了甲苯的催程度隨時(shí)間的推移逐漸減弱,原因是裂解反應(yīng)產(chǎn)生化裂解,130min后Ys趨于穩(wěn)定,此時(shí)甲苯主要進(jìn)的大量積碳,惡化了生物質(zhì)焦炭的比表面特性,甚行熱裂解,焦炭失活對(duì)其影響不大。至?xí)苯诱紦?jù)表面活性位,嚴(yán)重制約了甲苯裂解反一裂解反應(yīng) Cracking reaction應(yīng)的進(jìn)行。反應(yīng)后期XCH降至49.0%,此后變化不一重整反應(yīng) Reforming reac大,表明此時(shí)甲苯以熱裂解為主?？傊?甲苯裂解反應(yīng)中焦炭積碳失活嚴(yán)重,如何加強(qiáng)積碳的脫除是解決上述問(wèn)題的技術(shù)關(guān)鍵。瓣禮了如裂解反應(yīng) Cracking reaction★重整反應(yīng) Reforming reaction衛(wèi)品130020406080100120140160180200間 Time/min506050圖4微波加熱下合成氣產(chǎn)率隨時(shí)間的變化Fig 4 Variation of syngas yield with time under microwave3結(jié)論020406080100120140160180200本文通過(guò)微波輻射生物質(zhì)焦炭促進(jìn)甲苯轉(zhuǎn)化時(shí)間 Time/min研究了裂解和重整氣氛下甲苯轉(zhuǎn)化特性與產(chǎn)物析注:測(cè)試參數(shù)如下:溫度T為700℃:加熱時(shí)間t為90mm:CO2流量出規(guī)律,主要結(jié)論為:Fco2為80 mL/min。下Note: Test parameters were as follows: Temperature is 700 C; Heating time1)通入CO2可促進(jìn)甲苯轉(zhuǎn)化。MH下CO2流is 90 min; Flow rate of CO2 was 80 mL/min, Same as below.量為80 mL/min時(shí),甲苯轉(zhuǎn)化率最高,相比裂解轉(zhuǎn)圖3微波加熱下甲苯轉(zhuǎn)化率隨時(shí)間的變化化率高出12.08%;EH下CO2流量40mL/min時(shí),Fig 3 Variation of toluene conversion with time under達(dá)到最高轉(zhuǎn)化率82.13%。相同工況下,MH作用下甲苯轉(zhuǎn)化深度強(qiáng)于EH,轉(zhuǎn)化率最大差值為15.58%圖3顯示,重整反應(yīng)初期XCH在90%以上,2)CO2的通入可調(diào)控甲苯定向轉(zhuǎn)化合成氣這是甲苯裂解和重整耦合進(jìn)行的結(jié)果。此后, XCHB Mh作用下,CO2流量為80 mL/min時(shí),合成氣產(chǎn)出現(xiàn)一定的降低并很快達(dá)到較穩(wěn)定的狀態(tài)。由此表率達(dá)到最高值17366mL/min,遠(yuǎn)高于裂解反應(yīng)的明,此階段焦炭對(duì)甲苯重整反應(yīng)的作用效果比較穩(wěn)306 mL/min。同時(shí),通入CO2會(huì)降低合成氣的定,這說(shuō)明CO2的通入使得焦炭活性得到較好保持。H2CO值。但是,140min后X再次降低并持續(xù)到測(cè)試結(jié)束3)通入CO2使得生物質(zhì)焦炭出現(xiàn)碳損耗,損這是惰性積碳和碳損耗綜合所致。綜上分析,碳損失的碳通過(guò)氣化反應(yīng)生成CO,且加大CO2通入量耗會(huì)削弱焦炭對(duì)甲苯的重整效果,反應(yīng)進(jìn)行140min可提高氣化反應(yīng)對(duì)合成氣產(chǎn)率的貢獻(xiàn),CO2流量為時(shí)需補(bǔ)充新鮮的生物質(zhì)焦炭。120 mL/min時(shí),其貢獻(xiàn)的合成氣占合成氣總產(chǎn)率的利用式(3)得到甲苯裂解和重整的Ys,結(jié)果154示于圖4。如圖4所示,同一測(cè)試節(jié)點(diǎn),重整反應(yīng)4)隨著CO2通入量的升高,甲苯裂解轉(zhuǎn)化率的ys遠(yuǎn)高于裂解反應(yīng),表明甲苯重整更利于合成氣持續(xù)降低,140min后裂解率降為490%,之后波動(dòng)的定向制備。重整反應(yīng)中Ys隨時(shí)間的變化過(guò)程可以很小。重整反應(yīng)能夠?qū)崿F(xiàn)甲苯的高效穩(wěn)定轉(zhuǎn)化,僅分成2階段:第1階段(0~140min),Ys處于一在測(cè)試后期甲苯轉(zhuǎn)化率有所降低。氣化反應(yīng)可推遲個(gè)平臺(tái)期,此階段可以實(shí)現(xiàn)合成氣連續(xù)且穩(wěn)定的生甲苯重整轉(zhuǎn)化中國(guó)煤化工利影響,前成,合成氣產(chǎn)率保持在153mL/min以上;第2階140min內(nèi)合HCNMH Gin以上第23期李龍之等:生物質(zhì)氣化尾氣CO2聯(lián)合微波重整甲苯制備合成氣273[參考文獻(xiàn)]Peng Junxia, Zhao Zengli, Li Haibin, et al. 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Journal of Fuel Chemistry andstudy of Ni/MgO catalyst in carbon dioxide reforming ofTechnology, 2010, 38(4):409-414.(in Chinese withtoluene, a model compound of tar from biomassEnglish abstract)gasification[J]. International Journal of Hydrogen Energy,]祃曉寧.微波輔助木炭催化裂解甲苯的研究[D].大2012,37(18):13355-13364連:大連理工大學(xué),2012[15]李龍之.微波輻照下生物質(zhì)熱解氣定向轉(zhuǎn)化合成氣研eng Xiaoning. Decomposition of Toluene with Charcoal究[D.濟(jì)南:山東大學(xué),2012as Catalyst under Microwave Irradiation D]. DalianLi Longzhi. Research on Directional Conversion ofDalian University of Technology, 2012. (in Chinese withGaseous Products from Biomass Pyrolysis into SyngasEnglish abstract)Production under Microwave Irradiation[D]. Jinan[8]彭軍霞,趙增立,李海濱,等.生物質(zhì)焦制備條件對(duì)甲Shandong University, 2012.(in Chinese with English苯裂解特性的影響J.農(nóng)業(yè)工程學(xué)報(bào),2010,26(6):251—256中國(guó)煤化工CNMHG農(nóng)業(yè)工程學(xué)報(bào)2014年Toluene reforming by carbon dioxide recycled from biomassgasification into syngas production under microwave irradiationLi Longzhi, Song Zhanlong, Ma Chunyuan, Wang Fumao, Tian Yuanyu(1. College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao 266590, China2. National Engineering Laboratory for Coal Combustion Pollutants Reduction, Shandong University, Jinan 250061, China3. College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China)Abstract: The quality of gaseous products can be deteriorated by tar, CO2 and other impurities during the processof biomass gasification. Based on the those impurities analysis, tar conversion by CO2 is performed in this paperToluene was chosen as a model compound in this study, and it was used for converting into syngas productionover a biomass-derived char Biomass char is obtained from the pyrolysis of corn straw at a microwave-assistedexperimental system. The influences of heating method includes microwave heating(MH) and electrical heatingEH) as well as CO2 flow rate on toluene conversion, syngas yield and carbon loss. The results show that tolueneconversion from microwave heating is significantly higher than that from electrical heating under the samecircumstances. And it is revealed that a maximum difference of toluene conversion between microwave heatingand electrical heating is reached up to 15.58% at CO2 flow rate of 80 mL/min When a certain amount of CO2 isimported, toluene conversion can be improved effectively. The highest toluene conversion of 93. 73% is achievedunder microwave heating at CO2 flow rate of 80 mL/min, while toluene conversion under electrical heating isreached a peak of 82. 13%, corresponding to CO2 flow rate of 40 mL/min. Moreover, the introduction of CO2 canregulate the conversion of toluene into syngas production with a suitable ratio of H2 and CO. At the same time, anexcess of CO, can result in a loss of carbon contained in biomass-derived char. The carbon consumed through thgasification of CO2 can be converted into part of syngas production, which can impose a direct contribution tototal syngas yield. With the increase of CO2 flow rate, a higher syngas yield from carbon consumption is achievedThe maximum contribution of carbon consumption to syngas yield is 15.40% under microwave heating at CO2flow rate of 120 mL/min. According to the results, it is found that the highest yield of syngas derived from toluenereforming by CO2 under microwave heating is 173.66 mL/min when CO2 flow rate is 80 mL/min. And the yieldmentioned above is 5.68 times that of syngas obtained from toluene cracking in the absence of CO2. a decrease inthe conversion of toluene cracking is revealed, with the advancement of cracking experiment. And continuousdecrease in toluene conversion occurred in cracking experiment until the conversion of toluene cracking dropsbelow 49.0%. Afterwards, a stable phase of toluene conversion is seen in toluene cracking. It is fond that theconversion obtained from toluene reforming is maintained at a higher level, compared to that from toluenecracking. After toluene reforming conducted for 140 min, a decrease in toluene conversion is emerged. At thesame time, a gentle decrease in the yield of syngas produced from toluene reforming is observed after 140 minThe conclusions of this study have a significant effect on efficient disposal and utilization of tar from biomassgasification. This research can also provide beneficial reference to the emission of coKey words: microwaves; reforming reactions; tar; syngas; biomass char中國(guó)煤化工CNMHG