第32卷第4期燃料化學(xué)學(xué)報(bào)Vol 31 No 42003年8月JOURNAL OF FUEL CHEMISTRY AND TECHNOLOGY2003文章編號(hào):0253-24092003)40300-05吸熱型碳?xì)淙剂蠠崃呀饨沟男再|(zhì)研究郭永勝,何龍,方文軍,林瑞森浙江大學(xué)化學(xué)系,浙江杭州310027)摘要∶采用掛片測(cè)焦的方法測(cè)定了吸熱型碳?xì)迦剂蟂-1結(jié)焦速率隨裂解時(shí)間的變化結(jié)果顯示隨反應(yīng)時(shí)間的延長(zhǎng)燃料的結(jié)焦速率基本呈現(xiàn)増加趨勢(shì)。利用能量彌散ⅹ射線分析對(duì)金屬掛片滲碳現(xiàn)象旳考察結(jié)果顯示掛片焦中明顯有金屬原子的遷移。還利用儀器分析手段對(duì)吸熱型碳?xì)淙剂蟂-1在700℃時(shí)裂解所生成焦的性質(zhì)進(jìn)行了考察元素分析結(jié)果顯示隨反應(yīng)時(shí)間的延長(zhǎng)焦的氫碳比變低掃描電鏡對(duì)焦表面形態(tài)結(jié)構(gòu)的研究結(jié)果顯示熱處理溫度對(duì)焦的結(jié)構(gòu)有著很大的影響。對(duì)可溶焦的分析結(jié)果顯示δ-1裂解結(jié)焦并不是單一歷程結(jié)焦過(guò)程的中間產(chǎn)物基本分芳烴類與非芳烴類兩種關(guān)鍵詞:結(jié)焦;氬碳比;滲碳;吸熱型碳?xì)迦剂现袌D分類號(hào):V434.14文獻(xiàn)標(biāo)識(shí)碼:A吸熱型碳?xì)淙剂鲜且环N新型航空航天燃料,它1實(shí)驗(yàn)既可以通過(guò)自身的熱容、氣化潛熱吸熱還可以通過(guò)1.1實(shí)驗(yàn)原料選用自行配制的吸熱型碳?xì)淙剂匣瘜W(xué)裂解吸收并儲(chǔ)存飛行器高溫部位產(chǎn)生的熱量,s-1進(jìn)行裂解結(jié)焦實(shí)驗(yàn)s-1的基本物性見文獻(xiàn)在裂解的同時(shí)還可以得到燃燒性能良好的小分子產(chǎn)[1]該燃料具有相對(duì)較高的密度有利于提高燃料物這些產(chǎn)物進(jìn)入燃燒室后通過(guò)燃燒再把能量釋放的體積熱值從而減輕飛行器的負(fù)載同時(shí)S-1燃出來(lái)從而在提高能量利用率的同時(shí)6還有效的料還具有較高的吸熱能力即熱沉值較大當(dāng)裂解溫解決了飛行器的冷卻問(wèn)題。但是吸熱型碳?xì)迦剂隙葹?00℃時(shí)其熱沉值可以達(dá)到30MJkg在進(jìn)行裂解反應(yīng)時(shí)還會(huì)有小分子產(chǎn)物的聚合、縮合1.2試驗(yàn)裝置與方法為了研究吸熱型碳?xì)淙剂系榷畏磻?yīng)而導(dǎo)致結(jié)焦。結(jié)焦會(huì)帶來(lái)許多不利影熱裂解結(jié)焦性質(zhì),建立了一套連續(xù)流動(dòng)式測(cè)焦裝置響如堵塞閥門和過(guò)濾器油路變窄改變噴霧形狀,(圖1)影響霧化質(zhì)量嚴(yán)重時(shí)可導(dǎo)致發(fā)動(dòng)機(jī)熄火犛低熱交換效率結(jié)焦還會(huì)導(dǎo)致金屬管道中滲碳現(xiàn)象的發(fā)生從而降低其機(jī)械性能。吸熱型碳?xì)迦剂狭呀饨Y(jié)焦的研究一直是此類燃料開發(fā)的技術(shù)重點(diǎn)國(guó)內(nèi)外都進(jìn)行了大量的探索。但是這些研究大多是圍繞結(jié)焦扣制劑的開發(fā)以及結(jié)焦機(jī)理的推測(cè)展開的2而針對(duì)反應(yīng)生成的焦炭本身的性質(zhì)研究卻不多。焦炭的結(jié)構(gòu)性質(zhì)直接決定于燃料裂解過(guò)程中小分子產(chǎn)物的聚合路徑并與結(jié)焦機(jī)理密切相關(guān)"314。本文利用掃描電鏡圖1吸熱型碳?xì)迦剂辖Y(jié)焦測(cè)定裝置(S-570 SEM HITACHI Co, Japan)元素分析EA1l0, Figure 1 Coke determination system for endothermic hydrocarbon fuelIal以及能量彌散X射線分析 Finder-00DX等I-N2 i 2--surge damping valve i 3--manometer;4-rotor分析手段對(duì)吸熱型碳?xì)迦剂蟂-1熱裂解焦的性質(zhì)flowmeter ; 5-fuel pump ;7-valve i 8-temperature-con進(jìn)行了深入研究,為航空燃料的研究與開發(fā)提供了切實(shí)可靠的依據(jù)。YH中國(guó)煤化工-as-liquid separator; 15-gasCNMHG收稿日期:2002-08-28;修回日期:2003-06-02基金項(xiàng)目:國(guó)家高技術(shù)研究發(fā)展計(jì)戈863計(jì)劃夏863-2-1-1-7)作者簡(jiǎn)介5)男河南博愛人博士后從事吸熱型碳?xì)淙剂涎芯俊mil: sheng(@163.cm郭永勝等∵吸熱型碳?xì)淙剂蠠崃呀饨沟男再|(zhì)硏究301燃料由WPG-6型微量高壓平流泵輸送通過(guò)從圖2可以看出S-1裂解結(jié)焦速率隨時(shí)間的變指定流量的載氣攜帶進(jìn)入預(yù)熱系統(tǒng)汽化后在反應(yīng)化極不規(guī)律。反應(yīng)初期由于掛片中金屬原子的催管內(nèi)進(jìn)行裂解反應(yīng)。反應(yīng)生成的小分子產(chǎn)物在隨載化生焦作用結(jié)焦速率較快隨著結(jié)焦量的增加合金氣排岀的過(guò)程中不斷的發(fā)生縮合、聚合反應(yīng)而結(jié)焦,表面慢慢的被焦覆蓋金屬原子催化生焦的作用相隨著反應(yīng)時(shí)間的延續(xù)焦不斷的沉積在反應(yīng)管尾部應(yīng)減弱結(jié)焦速率也隨之下降。但隨著裂解反應(yīng)的的掛片上。當(dāng)裂解反應(yīng)結(jié)束后陬出掛片即可測(cè)定繼續(xù)很快NCr合金上岀現(xiàn)滲碳現(xiàn)象(焦的EDX譜結(jié)焦量并對(duì)焦的性質(zhì)進(jìn)行研究實(shí)驗(yàn)所選用的掛片圖對(duì)此是很好的證明見圖3)部分活性N、Cr金屬為NiCr合金。原子遷移到焦層表面重新恢復(fù)對(duì)結(jié)焦的催化作用。2結(jié)果與討論同時(shí)由于滲碳現(xiàn)象的出現(xiàn)以及焦在掛片表面的不斷21結(jié)焦速率隨反應(yīng)時(shí)間的變化在以前的研究沉積合金表面變得相對(duì)粗糙比表面積增大使得中H重點(diǎn)是測(cè)定結(jié)焦量,即利用脈沖進(jìn)樣法研究更多的烴可以粘附于焦的表面參與結(jié)焦反應(yīng)從而提添加不同結(jié)焦抑制劑后燃料裂解結(jié)焦量的減少?gòu)母吡私Y(jié)焦速率。而評(píng)價(jià)抑制劑的效果。但是,一次脈沖的結(jié)焦量只圖3是對(duì)焦的EDX分析譜圖圖中顯示從掛片能反映初始結(jié)焦速率而結(jié)焦是一個(gè)隨時(shí)間不斷變上剝離的焦中明顯含有NC金屬原子。這主要是化的過(guò)程結(jié)焦速率也隨反應(yīng)時(shí)間的延長(zhǎng)而不斷的碳現(xiàn)象導(dǎo)致金屬原子遷移的結(jié)果。變化。本文采用掛片測(cè)焦法對(duì)不同反應(yīng)時(shí)間掛片上2.2反應(yīng)時(shí)間對(duì)焦中氫碳比的影響反應(yīng)時(shí)間不焦的沉積速率進(jìn)行了測(cè)定結(jié)果見圖2。僅是影響結(jié)焦速率的關(guān)鍵因素同時(shí)它也直接影響焦的碳?xì)浣M成。一般說(shuō)來(lái)在溫度、壓力均保持恒定的條件下隨著反應(yīng)時(shí)間的增加,裂解深度逐漸加深,方面反應(yīng)初期生成的輕焦可以進(jìn)一步縮合焦的平均分子量隨之增大從而形成更小氬碳比的貧氫物質(zhì)另一方面小分子產(chǎn)物繼續(xù)聚合生成輕焦S1在不同反應(yīng)時(shí)間生成焦的氫碳比見圖4。從圖4可以看出S1裂解焦中氫碳比隨反應(yīng)時(shí)間的延長(zhǎng)而呈現(xiàn)下降趨勢(shì)說(shuō)明輕焦的進(jìn)一步聚合在結(jié)焦反應(yīng)中占據(jù)主導(dǎo)地位從而導(dǎo)致焦氫碳比的降低。0.00480.004圖2結(jié)焦速率隨反應(yīng)時(shí)間的變化igure 2 Changes of coking rate with reaction time0.0044000380.0036Reaction time t/min中國(guó)煤化工焦的氫碳比變化CNMHGcarbon ratio of cokeEnergy E/keVwith reaction time圖3焦的EDX分析譜圖2.3反應(yīng)溫度對(duì)焦性質(zhì)的影響反應(yīng)溫度對(duì)焦的Figure 3 EDX analysis for the coke性質(zhì)有著明顯的影響利用差熱分析方法對(duì)吸熱型碳?xì)淙剂蟂-1在700%℃時(shí)裂解沉積在Ni-Cr合金上的302燃料化學(xué)學(xué)報(bào)卷焦進(jìn)行程序升溫處理考察了不同溫度時(shí)焦性質(zhì)的過(guò)程基本是由以下步驟或其中的某些步驟組成的變化。試驗(yàn)過(guò)程中用氦氣保護(hù),程序升溫速率為烷烴→亠烯烴亠齊聚體亠環(huán)烷烴→芳烴。其中齊聚終溫1200℃體可以進(jìn)一步聚合當(dāng)分子量很大時(shí)就形成非芳烴烴類物質(zhì)的裂解結(jié)焦是小分子產(chǎn)物不斷聚合的焦。芳烴可以進(jìn)一步生成富碳缺氫的重焦隨著溫度的升高甚至生成石墨類物質(zhì)6549℃在對(duì)焦樣品進(jìn)行熱處理時(shí)發(fā)現(xiàn),當(dāng)溫度達(dá)到6549℃時(shí)焦樣品開始出現(xiàn)明顯的失重現(xiàn)象(見圖5)導(dǎo)致焦失重的原因可能是焦內(nèi)部的大分子DTG687.1℃烴類物質(zhì)在高溫條件下繼續(xù)進(jìn)行氬轉(zhuǎn)移反應(yīng)而造成的同時(shí)焦內(nèi)的有機(jī)物氣化以及一些雜質(zhì)的揮發(fā)也0060080010001200是引起焦失重的原因,說(shuō)明在該試驗(yàn)條件下焦中有Temperature t/℃機(jī)物進(jìn)一步生成了富碳貧氫的焦而原有裂解條件圖5S-1裂解焦的 DSC-TG分析譜圖下所生成的貧氫物質(zhì)聚合程度還不是特別大。當(dāng)熱Figure 5 DSC-TG analysis for coke of S-1處理溫度達(dá)到687.1℃時(shí)圖中出現(xiàn)熱效應(yīng)最大峰中國(guó)煤化工CNMH圖6熱處理前后S1焦的SEM照片F(xiàn)igure 6 SEM pictures for coke at different temperature( a)sEM picture of coke surface at 700C b)sEM picture of coke transect at 700 C(c) SEM picture of coke transect at 100c:d) SEM picture of coke surface at1200℃郭永勝等∵吸熱型碳?xì)淙剂蠠崃呀饨沟男再|(zhì)硏究值說(shuō)說(shuō)明此時(shí)焦內(nèi)的氫轉(zhuǎn)移反應(yīng)以及有杋物氣化最無(wú)論是焦的表面(d還是焦的橫斷面(c郿都呈現(xiàn)蜂窩為強(qiáng)烈。SEM對(duì)焦結(jié)構(gòu)分析的結(jié)果也顯示焦內(nèi)有機(jī)狀結(jié)構(gòu)這主要是由于焦中有機(jī)物和雜質(zhì)的揮發(fā)和物反應(yīng)的存在,圖6分別給岀了熱處理前后焦的氣化導(dǎo)致的這與差熱分析的結(jié)果相吻合。SEM照片直觀的顯示處理溫度對(duì)焦結(jié)構(gòu)的影響2.4焦中有機(jī)物的結(jié)構(gòu)分析焦中所含有機(jī)物質(zhì)圖中(a)(b)為700℃焦的SEM照片。從焦的基本可以分為可溶焦和不溶焦兩種其中可溶焦具表面形態(tài)分析照片(a)可以看出焦的表面比較粗有相對(duì)較高的氫碳比,它也可以被看作是結(jié)焦過(guò)程糙呈圓球型堆積在一起,可能是燃料在焦核金屬中的中間產(chǎn)物。對(duì)焦中可溶焦成分的鑒定對(duì)探索結(jié)原子、雜質(zhì))結(jié)焦并包裏焦核所致。另外對(duì)焦的橫焦的機(jī)理、確定S-1裂解結(jié)焦的反應(yīng)歷程具有重要斷面分杬b黠結(jié)果顯示焦內(nèi)部還有分層現(xiàn)象主要原意義。利用二氯甲烷作為溶劑對(duì)焦中的可溶焦進(jìn)因可能是結(jié)焦初期焦首先沉積并開始慢慢滲透到行抽提然后利用色質(zhì)聯(lián)用裝置進(jìn)行測(cè)定結(jié)果顯金屬里面造成金屬原子遷移此時(shí)主要是金屬催化示芳烴類焦占可溶焦總量的67%而非芳烴類焦生焦。隨著反應(yīng)的繼續(xù)和掛片上結(jié)焦量的增加直則占33%。接在焦表面的沉積結(jié)焦占據(jù)主導(dǎo)地位由于兩種結(jié)由此分析可以看出在S-1吸熱型碳?xì)淙剂蠠峤沟姆绞讲煌斐山沟慕Y(jié)構(gòu)也不同從而導(dǎo)致焦的裂解過(guò)程中小分子產(chǎn)物的聚合、縮合歷程非常復(fù)分層現(xiàn)象。對(duì)焦進(jìn)行熱處理至1200℃后焦的結(jié)構(gòu)雜這也為結(jié)焦機(jī)理的研究以及結(jié)焦抑制劑的開發(fā)發(fā)生了巨大變做Wc(d))從照片中可以看出,提供了重要的信息。參考文獻(xiàn)[1]郭永勝何龍蔣武籌.吸熱型碳?xì)迦剂狭呀獯呋瘎┙Y(jié)焦硏究J燃料化學(xué)學(xué)報(bào),2002,3(6)514-518GUO Yong-sheng, HE Long, JIANG Wu et al. 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Surface coking behavior on 25Cr35Ni heat-resistant alloy[ J ].Corro-sion Science and Protection Technol, 1999, 115)274-278)[I4]潘富敏何龍林瑞森.吸熱型碳?xì)迦剂系慕Y(jié)焦研究Ⅱ黠焦抑制劑的性能評(píng)J].推進(jìn)技術(shù),200,2x3)246-249(PAN Fu-min, HE Long, LIN Rui-sen. Coking property of endothermic fuel Il ) Evaluation on coking-inhibitors'functiort J]Joumal of Propulsion Technology, 2001, 2] 3 )246-249.)STUDY ON PYROLYSIS-CRACKING COKE OF ENDOTHERMICHYDROCARBON FUELSGUO Yong-sheng HE Long, FANG Wen-jun LIN RuiDepartment of Chemistry, Zhejiang University, Hangzhou 310027, ChinaAbstract: The coking characteristics of endothermic hydrocarbon fuel S-1 on Ni-Cr alloy was studied in a laboratoryscale continuous flow reactor system. The carburation on alloy was proved by EDX analysis. The composition of cokewas determined by element analysis( EA ), which showed that the ratio of hydrogen and carbon of the coke decreasessoon with the extending of reaction time. Surface morphology of coke was determined by means of scanning electronmicroscopy( Sem) after heat treatment at the temperature from 700C to 1 200 C with heating rate of 20 C/min byDifferential scanning calorimetry( DSC ) The results show that temperature has an important effect on the structure ofcokes. The analysis results of soluble coke show that intermediate coking product consists of aromatic compound andpaKey words coke i hydrogen-carbon ratio carburation endothermic hydrocarbon fuelFoundation item: The National High Technology Research and Development Program of China( 863 Program )(863-2-1-1-7)Author introduction: GUO Yong-sheng( 1975-), male, Postdoctor engaged in research of endothermic fuels中國(guó)煤化工CNMHG