石油焦高溫氣化反應性

第33卷第6期燃料化學(xué)學(xué)報ol. 33 No 62005年12月Journal of Fuel Chemistry and TechnologyDec.2005文章編號:0253-240200506-0687405石油焦高溫氣化反應性唐黎華,陳冬霞,朱學(xué)棟,吳勇強,倪燕慧,朱子彬華東理工大學(xué)化學(xué)工藝研究所,上海200237)摘要常壓μ200℃~1500℃在自制管式反應器中以二氧化碳為氣化介質(zhì)研究了石油焦以及石油焦與后布連煤焦摻混后形成的混合焦的氣化反應性借助于ⅪRD分析了高溫處理后石油焦與煤焦在碳結構有序化方面的區別。研究結果表明當碳轉化率高于0.7氕氣化超過(guò)1300℃石油焦的反應速率岀現急驟下降氕氣化溫度越高相應石油焦速率下降越快?；旌辖箽饣磻约炔煌诩兪徒挂膊煌诩兠航?。隨石油焦摻入比變化而改變的拐點(diǎn)主要源于石油焦與煤焦的反應性之間差異。較高轉化率下出現的拐點(diǎn)主要源于石油焦本身隨氣化溫度提高導致氣化速率下降。RD測定顯示高溫處理后石油焦中碳有序化程度要明顯高于煤焦。高氣化溫度下石油焦碳結構發(fā)生明顯有序化是導致其反應活性急劇下降的重要原因關(guān)鍵詞:石油焦;高溫氣化;XRD;碳結構中圖分類(lèi)號:TO051.13T038.2文獻標識碼:A中國進(jìn)口的中東原油中硫質(zhì)量分數較高其副表2后布連原煤性質(zhì)產(chǎn)品石油焦含有較高的硫,一般作為動(dòng)力燃料燃燒Table 2 Properties of Houbulian coal sample時(shí)產(chǎn)生的硫氧化物通過(guò)添加石灰石解決。但是隨著(zhù)ate analysis wan /Ultimate analysis wdn /%環(huán)保對大氣污染排放物要求的提高,加之燃燒后產(chǎn)生的大量廢渣難以處理所以尋找更為有效的石油27.4319.1553.4281.003.981.250.3313.44焦處理技術(shù)一直是研究者追求的目標。借助高溫氣化爐將石油焦轉化成高價(jià)值氬、動(dòng)力和蒸汽同時(shí)將原料中98%以上的硫轉化成單質(zhì)硫可實(shí)現石油焦1.2煤焦制備將后布連煤放在干餾爐內加熱干的資源化利用。石油焦作為燃料的研究已有許多報餾用高純氮氣充分置換將氮氣流量調至20mL導31對石油焦氣化反應也進(jìn)行了一定的研min以5℃/min的速率升溫至900℃并在該溫度究461但涉及石油焦以及石油焦與煤焦混合焦在下保持2h在氮氣保護下降至室溫再將制得的焦高氣化溫度下的反應性研究很少。本文以上海煉油樣過(guò)篩得到粒徑200μm-280m的焦樣分析數廠(chǎng)石油焦和后布連( Houbulian)煤焦為對象在據見(jiàn)表3200℃~1500℃下對石油焦以及石油焦與煤焦混表3后布連煤焦性質(zhì)合焦的氣化特性進(jìn)行了研究。Table 3 Properties of Houbulian char samples1實(shí)驗部分Proximate analysis wan / Ultimate analysis war /91.1原料實(shí)驗選用上海煉油廠(chǎng)石油焦和后布連煤作為試樣試樣粒徑200μm~280μm。石油焦以3.4321.1575.4293.322.581.100.162.84及煤樣的組成分析分別見(jiàn)表1和表2。表1石油焦性質(zhì)1.3焦氣化反應性測定實(shí)驗用CO,作氣化劑Table 1 Properties of petroleum coke sam流量控制在0.50L/min~0.60L/min實(shí)驗證實(shí)該Proximate analysis war, / Ultimate analysis war /%條件下已消除內、外擴散的影響。試樣量約0.2FCC8.780.1891.0491.683.261.722.770.57236hH中國煤化工器是一個(gè)長(cháng)CNMH叵溫區中心有鉑銠熱by difference電偶測溫加熱爐內的加熱元件為硅碳棒。作者簡(jiǎn)方雋貨搖0),男,上海人,博士,化學(xué)工藝專(zhuān)業(yè),從事煤氣優(yōu)和固體廢棄物資源化工作。Em1:hang(@ecust.edu.cn688燃料化學(xué)學(xué)報33卷6即得到反應速率與碳轉化率的關(guān)系。2結果與討論2.1石油焦的反應性圖2是石油焦氣化反應的789101113145比較。由圖2(a)可見(jiàn)隨氣化溫度上升石油焦的圖1氣化速率測定裝置示意圖高溫氣化反應性也隨之提高;但當氣化溫度高于Figure 1 Diagram of testing apparatus of gasification rate1300℃石油焦的轉化率與反應時(shí)間曲線(xiàn)在高轉化-CO, cylinder 2-flowmeter : 3-buffer bottle: 4-suIfi率明顯岀現拐點(diǎn)氣化溫度越高拐點(diǎn)岀現的位置越acid washing bottle;5- -dry bottle:6- temperature con-提前。從圖2(b)也可以發(fā)現在碳轉化率低于0.7troller:7- porcelain boat:8- lace r9rtoe:10時(shí)石油焦的反應速率隨氣化溫度提高而上升沮當碳轉化率高于0.7隨著(zhù)氣化溫度的提高石油焦的反filter; 14--triple valve 15--chromatographic instrument應速率出現了急驟下降溫度越高相應石油焦反應1.4數據處理在反應器出囗處每間隔一定時(shí)間速率下降越快,下降的位置也越提前。由圖2xc)可取樣通過(guò)色譜儀分析其中的CO的體積分數同時(shí)見(jiàn)碳轉化率分別為0.2和0.5時(shí)石油焦反應速率由濕式流量計計量碳轉化率與對應氣化反應時(shí)間與溫度的關(guān)系與煤焦基本相似即反應速率隨溫度的關(guān)系由下式可求得。提高而上升擔碳轉化率0.9時(shí)反應溫度從1200℃碳轉化率x的計算式提高至1300℃反應速率單調上升繼續提高溫度,yc0△1270反應速率則開(kāi)始呈現單調下降趨勢。表4是石油焦2mu GD在1200℃~150℃C不同碳轉化率下的活化能比較。通過(guò)對碳轉化率x與氣化時(shí)間t的曲線(xiàn)進(jìn)行微由表4可見(jiàn)碳轉化率為0.20.5時(shí)活化能基本相商處理求取不同碳轉化率下的反應速率(dx/dt)同說(shuō)明溫度的改變對反應速率的影響非常相似。0150.010002040.60.81.0Time !/minConversion xT(10k)圖2石油焦的反應性Figure 2 Reactivity of petroleum cokeate with(c)relation of reaction rate with temperature(a)■1200℃;o1250℃;▲1300℃;V1350℃;★1400℃;☆1450℃;◆1500℃(b)■120℃;1250℃;▲1300℃;V1350℃;◆1400℃;◇1450℃;★1500℃(c)口x=0.2:ox。=0.5:△x。=0.9表4不同碳轉化率下石油焦的活化能變化既不同于純石油焦也不同于純煤焦,1200℃Table 4 Activation energy of petroleum coke at時(shí)碳轉化率和時(shí)間曲線(xiàn)在碳轉化率分別為0.7和different carbon conversions0.9中國煤化工拐點(diǎn)。隨著(zhù)氣化溫度Cony. x從1CNMHG點(diǎn)的明顯程度雖有所E/kF mol150.3151.8減弱世在飯轉化率為0.7位置出現的拐點(diǎn)基本保2.2混合焦的反應性后布連煤焦與不同比例石持而另一拐點(diǎn)出現的位置則隨氣化溫度的提高呈油焦形成的混合焦氣化反應性隨溫度的變化見(jiàn)現下移的趨勢。綜合圖3可以發(fā)現隨著(zhù)石油焦摻圖3。由圖數期可見(jiàn)混合焦氣化反應性隨溫度的入比從30%遞增到50%和70%原來(lái)在圖3(a)中唐黎華等:石油焦高溫氣化反應性碳轉化率0.7位置岀現的拐點(diǎn)也相應遞減至0.5和較高轉化率下岀現的拐點(diǎn)依據其隨氣化溫度提高0.4而另一拐點(diǎn)則隨石油焦摻入比的增加并未發(fā)生出現位置下降的特征,可以認為這一拐點(diǎn)的出現主明顯的改變。由此可以初步判斷拐點(diǎn)隨石油焦摻要源于石油焦本身隨氣化溫度提高導致氣化速率下入比變化而改變的主要原因是石油焦與煤焦的反應降。從圖3也可以看出不同焦摻混可能會(huì )造成完性之間存在明顯的差異。由于后布連煤焦的反應性全氣化所需的時(shí)間延長(cháng)所摻混合焦的氣化反應特明顯高于石油焦可以推斷拐點(diǎn)之前發(fā)生的主要是性相差懸殊時(shí)這種現象表現得更加突出。煤焦氣化反應拐點(diǎn)之后主要為石油焦的氣化反應0.20010TimeTime f/min圖3后布連煤焦與石油焦摻混所形成混合焦的反應性Figure 3 Reactivity of petroleum coke blending with Houbulian charC a)Houbulian +30% petroleum coke b) Houbulian +50% petroleum coke c)Houbulian +70% petroleum coke■120℃;○1300℃;▲1400℃;V1500℃2.3石油焦與后布連煤焦XRD比較在相同的焦和后布連煤焦來(lái)源不同決定了它們在結構方面氣化溫度下石油焦反應速率隨轉化過(guò)程而發(fā)生變存在差異。圖4和圖5是石油焦和后布連煤焦在化主要源于石油焦本身碳結構改變以及石油焦中1500℃不同時(shí)間熱處理的XRD變化。23.5°(C礦物質(zhì)變化而氣化溫度以及所用石油焦樣來(lái)源是(002))和43.5(((10))相對應峰強度的高低可以決定上述兩種變化最為重要的二個(gè)因素。由于石油用于衡量試樣中碳的有序化程度7是焦晶格化程600006000050000petroleum coke400002000020000100001000026°)20°)6000050000Smin400004000020000中國煤化工10000CNMHG26°圖41500℃下不同熱處理時(shí)間所得石油焦的XRD比較萬(wàn)方數掘e4 XRD comparison of petroleum coke with coke of different heat treatment times at1500℃燃料化學(xué)學(xué)報33卷8000Houbulian coalI min500030003000100020°)20f°)圖51500℃下不同熱處理時(shí)間所得后布連煤焦的XRD比較Figure 5 XRD comparison of Houbulian coal with char of different heat treatment times at 1 500C度的重要標志對焦反應性有重要的影響]。而譜素形態(tài)。高溫氣化反應時(shí)后期反應的石油焦伴隨圖中一些細小的尖峰代表煤焦中所含有的各種礦物氣化反應的進(jìn)行經(jīng)歷一個(gè)高溫熱處理過(guò)程。而從質(zhì)]。由ⅹRD圖譜可以發(fā)現,石油焦主要出現C上述的XRD分析可知石油焦經(jīng)過(guò)短時(shí)間的高溫熱〔α02朧峰經(jīng)過(guò)1500℃高溫處理后α(002)峰強度處理后其碳結構已發(fā)生明顯的改變有序化程度得明顯增強但熱處理達到3mi后峰的強度不再增以顯著(zhù)加強相應石油焦旳反應性明顯減弱而這種加熱處理后新增了一個(gè)∝10)峰和2θ約為53.5°弱化作用直接與熱處理溫度和時(shí)間相關(guān)。熱處理溫的峰但強度相對較低基本上不隨熱處理時(shí)間發(fā)生度越高熱處理時(shí)間越長(cháng)碳的有序化程度越深反改變。后布連原煤也只岀現了一個(gè)α002牖峰但峰應性下降越明顯。這是導致石油焦在高氣化溫度和的面積較大峰的強度明顯低于石油焦。高溫熱處高轉化率下反應速率岀現急劇下降的重要原因。后后布連煤焦XRD衍射圖譜上也出現了明顯的符號說(shuō)明α(10產(chǎn)峰蜂面積和峰強度與石油焦相當。綜合石x.—碳轉化率%油焦和后布連煤焦在α002)和α(10)峰強度上的yo-CO平均體積分數%強弱可以發(fā)現由于石油焦在((002)峰上的強度Vn一反應器出口氣體體積L比后布連煤焦高6倍~10倍而兩種焦的α(10)峰m一試樣的質(zhì)量強度相當由此可以認為石油焦中碳的有序化程度試樣中碳的質(zhì)量分數%明顯高于后布連煤焦導致石油焦的反應性也明顯T-273.15K低于后布連煤焦?；焓搅髁坑嫵隹跍囟菿。石油焦屬生焦本質(zhì)上是一種部分石墨化的炭中國煤化工CNMHG參考文獻[Ⅰ]楊亞平,蔡崧.煙煤與石油焦摻混燃燒特性硏究J]熱能動(dòng)力工程,2001,16(6):612631YANG Ya-ping, CAI Song. Study of combustion characteristic of bituminous coal mixing with petroleum coke j ] Power ErEngineering ofHeat Energy,2001,16(6):612631.)[2]熊源駟瀲椐,鄭守忠.油焦漿、水焦漿燃燒特性的試驗研究J]熱能動(dòng)力工程,2001,165):494496唐黎華等:石油焦高溫氣化反應性691XIONG Yuan-quan, SHEN Xiang-lin, ZHENG Shou-zhong. Experimental study of combustion characteristic of oil-coke slurry and wateroke slurry[ J ] Power Engineering of Heat Energy 2001, 16(5): 494-496.)[3]黎永,呂俊復,張建勝,仼維,王盺,劉青,岳光溪.石油焦燃燒反應活性及循環(huán)流化床燃燒實(shí)駘J]燃燒科學(xué)與技術(shù),2001,7(1)81-84LI Yong, LU Jun-fu, ZHANG Jian-sheng. REN Wei, WANG Xin, LIU Qing, YUE Guang-xi. Reactivity measurements and combustion experiments on CFB rig for petroleum coke J ] Journal of Combustion Science and Technology 2001, 7(1): 81-84.)4] LEE S H, CHOI C S. Chemical activation of high sulfur petroleum coke by alkali metal compound J ] Fuel Process Technol 2000, 6413):141-153[6]李慶峰,房倚天,張建民,王洋,時(shí)銘顯,孫國剛石油焦水蒸氣氣化反應特性J]燃料化學(xué)學(xué)報,2003,33)2[5] TYLER R J, SMITH I W, Reactivity of petroleum coke to carbon dioxide between 1030 and 1180KT J ] Fuel, 1975, 54 2): 99LI Qing-feng, FANG Yi-tian, ZHANG Jian-min, WANG Yang, SHI Ming-xian, SUN Guo-gan. Steam gasification characteristics of petum cok j ] Journal of Fuel Chemistry and Technology 2003 31(3): 204-208[7] RADOVIC L R, WALKER Jr P L JENKINS R G. Importance of carbon active sites in the gasification of coal chars[ J ] Fuel, 1983, 629-856[8]路霽鸰,黎永,楊小勇,岳光溪,李欽義.煤焦的晶格結構、本征反應活性和密度初探J]燃料化學(xué)學(xué)報,1998,266):492496(LU Ji-ling, LI Yong YANG Xiao-yong, YUE Guang-xi, Yam Y. lee. Crystallinity true density and in trinsic reactivity of intermediate tem-perature coal chat J ] Journal of Fuel Chemistry and Technology 1998, 26(6):492-496.)[9] SENNECA O SALATINO S, MASI S. Microstructural changes and loss of gasification reactivity of chars upon heat treatment[ J ]. Fuel1998,77(13):1483-1493Gasification reactivity of petroleum coke at high temperatureTANG Li-hua, CHEN Dong-xia ZHU Xue-dong, wU Yong-qiang, NI Yan-hui, ZHU Zi-binResearch Institute of Chemical Technology ECUST, Shanghai 200237, ChinaAbstract: Using CO, as the gasification agent, the gasification reactivity of the petroleum coke and the mixtureswith Houbulian coal chars was studied in a self-made tubular reactor under normal pressure and at temperatureranging from 1 200 C to 1 500 C. The difference of carbon structure ordering between petroleum coke and coalchar processed at high temperature was analyzed by using XRD. The results show that the gasification rate of pe-troleum coke decreases rapidly when the carbon conversion rate is higher than 70% and the gasification temperature is over 1 300 C. The higher the gasification temperature is the faster the gasification rate of petroleum cokedeclines. The gasification reactivity of the mixture of petroleum and coal char is different from that of pure petro-eum coke or pure coal char. With the variation of the ratio of petroleum coke to coal char the inflexion variebecause of the different reactivity between petroleum coke and coal char. With the increase of gasification tem-perature the decrease of gasification rate of the petroleum coke results in the appearing of inflexion at higher carbon conversion. The XRD test indicates that after being handled at high temperature the degree of carbon structure ordering in petroleum coke is greater than that in coal char. The carbon structure ordering obviously at hightemperature is an important reason to lead to the sharp reduction of petroleum coke gasification rateKey words: petroleum coke high temperature reactivity XRD carbon structureAuthor introduction: TANG Li-hua( 1965-), male, Ph. D, majoring in chemical technology and engaged in the coal gasification and solid waste utilization. E-mail: lhtang ecust edu中國煤化工CNMHG