第24卷第2期煤炭轉(zhuǎn)化Vol.24 No. 22001年4月COAL CONVERSIONApr.2001煤快速熱解過(guò)程中氧化鈣對(duì)焦油裂解的影響”賈永斌)黃戒介2) 程中虎3王洋4>商要為降低煤在熱解、氣化過(guò)程中的焦油產(chǎn)量,在一快速熱解固定床反應(yīng)器中考察了氧化鈣催化劑的加入對(duì)焦油裂解反應(yīng)的影響,研究結(jié)果表明:在相同反應(yīng)條件下，所選三種氧化鈣催化劑中以CaO-3的焦油裂解活性為最大,它們的焦油裂解活性順序?yàn)?CaO-3>CaO-2>CaO-1.并進(jìn)-步考察了CaO-3在不同反應(yīng)溫度下對(duì)焦油裂解反應(yīng)的影響.關(guān)鍵詞焦油裂解,氧化鈣,快速熱解，固定床中圖分類號(hào)TQ530. 2些低沸點(diǎn)純組分的裂解研究表明:氧化鈣對(duì)芳香烴0引言裂解的影響較大，而對(duì)脂肪烴的影響較小:甲基物均發(fā)生脫甲基反應(yīng),氧化鈣促進(jìn)了脫甲基析碳和環(huán)狀煤在我國(guó)能源結(jié)構(gòu)中占有絕對(duì)優(yōu)勢(shì),其中低階結(jié)構(gòu)的破裂.有的學(xué)者認(rèn)為堿土金屬的氧化物能激煤占煤總儲(chǔ)量的42%以上.低階煤通常含有30%~發(fā)活化位的產(chǎn)生.[6.7]本研究將在固定床快速熱解條40%的揮發(fā)分,適宜于通過(guò)熱解氣化制取較高熱值件下考察三種不同來(lái)源的氧化鈣對(duì)焦油的裂解活的氣體,但在熱解氣化過(guò)程中會(huì)有少量的焦油產(chǎn)生，性,并對(duì)較優(yōu)的催化劑作進(jìn)-步較詳細(xì)的考察.焦油的產(chǎn)生一方面會(huì)引起管道堵塞,影響操作系統(tǒng)的正常運(yùn)行;另一方面在許多的工業(yè)應(yīng)用中要求得1實(shí)驗(yàn)部分到潔凈的煤氣,例如在IGCC中要求得到熱的和潔凈的煤氣,而焦油的產(chǎn)生增加了粗煤氣的凈化難度,1.1實(shí)驗(yàn)物料歐盟正致力于這一方面的研究.所以,如何能使焦油在熱解氣化過(guò)程中盡可能得到完全的裂解，使產(chǎn)生以彬縣煤為原料,煤樣粒徑為0.180 mm~的氣體不含焦油，對(duì)于潔凈高效利用低階煤具有重.0.700mm,-次反應(yīng)煤樣及所加催化劑分別為5g要的意義.和1 g,催化劑與煤樣機(jī)械混合,原煤煤質(zhì)分析見表關(guān)于氧化鈣對(duì)于焦油裂解的活性,人們作了較1,所選催化劑組成見第54頁(yè)表2.其中CaO-1是化多的研究,Frankin等口發(fā)現(xiàn)含鈣的礦物質(zhì)可以降低表1原煤工業(yè)分析和元素分析Table 1 The Proximate and ultimate analysis焦油的產(chǎn)量.Yoon等0]的實(shí)驗(yàn)表明石灰石可以增強(qiáng)of coal used焦油的裂解程度和速度,提高煤氣中的氫氣、甲烷以Proximate analysis/% " .adUltimate analysis/%* ,ad及二碳烴的含量. ChiuKin-53的研究表明氧化鈣可MAvCHN以通過(guò)催化酮-烯醇異構(gòu)化反應(yīng)而促進(jìn)酚類的裂解.5.7110.58 23. 5!67.48 3.97 10.86 1.04 0.36Khan[41的研究也表明:氧化鈣的添加有利于焦油Percent of weight.(尤其是酚類化合物)的裂解.Eling[']在對(duì)焦油中某54煤炭轉(zhuǎn)化2001年學(xué)分析純氧化鈣,CaO-2是由碳酸鈣在900 C下煅加入無(wú)水硫酸鈉,輕輕搖動(dòng)至不結(jié)塊為止,加蓋,放燒得到的,CaO- 3是由氫氧化鈣在700 C下煅燒得置約30min后,用預(yù)先以石油醚洗滌過(guò)的濾紙過(guò)到的.濾,收集濾液經(jīng)65 C烘干,置于恒重的200mL燒表2所選催化劑的組成杯中，用石油醚洗滌錐形瓶、硫酸鈉和濾紙,洗液并Table 2The composition of catalysts used”入燒杯中,將燒杯置于65 C水浴上蒸發(fā)至近干,然Ca(OH)2>99. 0%Ca0>99. 0%CaCO3>98. 0%后將燒杯外壁水珠擦干,置于烘箱中,在65 C下烘HCI- nonsoluble Ammonia precipitate HCI nonsoluble干1h,放入干燥器內(nèi)冷卻30min后稱重.materials 0.01%0.2%materials 0. 05%1.3.2 氣體分析Sulfate 0. 01%Alkaline metal and實(shí)驗(yàn)采用2305色譜儀分析二氧化碳,用2307Mg 0. 5%色譜儀分析其它常規(guī)氣體.Na 0.2% .Sulfate 0.1%Sulfate 0.2%Acetic acidAmmonium hydroxideMg 0.05%; Nonsoluble materialsprecipitate 0. 25%2結(jié)果與討論0. 05%K 0.01%Chloride 0. 5%￥Percen of weigh.2.1不同氧化鈣催化劑對(duì)焦油裂解影響的考察1.2實(shí)驗(yàn)裝置為了對(duì)不同來(lái)源的氧化鈣催化劑的催化性能進(jìn)實(shí)驗(yàn)在一固定床快速熱解反應(yīng)器中進(jìn)行,系統(tǒng)行比較,分別在700 C和800 C反應(yīng)條件下考察了壓力為常壓,實(shí)驗(yàn)裝置見圖1.它們對(duì)焦油裂解情況的影響.實(shí)驗(yàn)結(jié)果分別見表3和表4.|4表3700C時(shí)催化劑對(duì)焦油和氣體產(chǎn)量的影響Table 3 Effects of catalysts on tar and gas yields (700 C)NKindsof Tar yield/Gas yields/10- 3/molcatalystcoH2CH49No catalyst2.7412.013.449. 457. 79AM 2], 8CaO-1 .2.345.364.4612.60 9.01CaO-21.964.01 5.7713.69 8. 31CaO-31.683.674.0414. 609.24，圖1實(shí)驗(yàn)裝置表4800C時(shí)催化劑對(duì)焦油和氣體產(chǎn)量的影響Fig. 1 Experimental apparatusTable 4 Effects of catalysts on tar and gas yields (800 C )Reactor: 2Electric furnace; SPush rod;Kinds of Tar yield/Gas yields/10- /molHeating control apparatus; 5, 6. 7Tar trap;CO2H: Gas collector; 9-- Pressure meterNo catalyst 2. 2112.707.4520.2010.36首先設(shè)定反應(yīng)溫度,然后開始升溫,同時(shí)通入氮1.9911.36 :11.89 24. 81.13. 771.61 .10.3411.26 27. 6713.24氣,氮?dú)饬髁繛?90mL/min;當(dāng)?shù)獨(dú)馔ㄈ霑r(shí)間超過(guò)1.419. 6910.06 30. 1813.1330 min且達(dá)到設(shè)定溫度后,快速推入樣品到反應(yīng)區(qū)，同時(shí)開始排水取氣,熱解煤氣經(jīng)石油醚吸收后進(jìn)由表3和表4也可看出,在三種氧化鈣催化劑入集氣瓶中;當(dāng)反應(yīng)約8 min~10 min后,停止實(shí)中，催化活性的大小順序?yàn)?CaO- 1CaO 2≈Al2O:>CaO-1≈Fe2O,其中氧化鈣催化劑的物理性質(zhì)極大地影響著它們的催化作用.2 6-(2)700C時(shí)在原煤中加入CaO催化劑后,從CaO-1到CaO-3,氣體中的CO2含量逐漸減少,而H2含量逐漸增加,800C時(shí)這種現(xiàn)象不很明顯.(3)相對(duì)原煤熱解而言，加入CaO-3后,焦油產(chǎn)0550600650700750800率下降35%~40%,且焦油產(chǎn)率最大值所處的溫度由650C下降到600C.圖5不同溫度下 CaO-3對(duì)CO產(chǎn)率的影響(4)相對(duì)原煤而言,加入CaO-3后，氣體中的Fig.5 Effect of CaO-3 on CO yield at differentCO2含量明顯降低,而CO,H2和CH。的含量則明顯增加.第2期賈永斌等煤快速熱解過(guò)程中氧化鈣對(duì)焦油裂解的影響參考文獻(xiàn)[1] FranklinH D, Peters W A. Howard J B. Mineral Matter Effects on the Rapid Pyrolysis and Hydropyrolysis of a BituminousCoal 1. Effects on Yields of Char. Tar and Light Gaseous Volatiles. Fuel, 1982.61:155-160[2] YoonK J, Walker P L Jr. Mulay L N et al. Benzene Hydrogenation over Iron; 1, Specific Activities and Kinetic Behaviorover Unsupported Iron and Iron Dispersed on SiO2. AlOs，Carbon and Doped Carbon. Ind Eng Chem Process Des Dev,1983.22:519[3] Chiu- KinSL. Chen P. Longwell J P et al. Thermal Reactions of m Cresol over Calcium Oxide Between 350 and 600 C. Fu-el. 1987.66 ;525-531[4] Khan M R, Seshadri K. Compositional Changes in the Mild Gasification Liquids Produced in the Presence of Caleium Com-pounds. Fuel Processing Technology. 1991. 27:83-94[5]呂俊復(fù).岳光溪.氧化鈣條件下焦油主要組分的催化裂解.清華大學(xué)學(xué)報(bào)(自然科學(xué)版).1997.37(2):6-10.[6] Simell P A. son Bredenberg J B. Catalytic Purification of Tarry Fuel Gas. Fuel, 1990.69;1219- 1225[7] SimelIP A, Hepola J O, Krause A O. Effects of Gasification Gas Components on Tar and Ammonia Decomposition over HotGas Cleanup Catalysts. Fuel, 1997.761117-1127[8] Tamhankar ss. Tsuchiya K, Riggs J B. Catalytic Cracking of Benzene on lron Oxide Silica: Catalyst Activity and ReactionMechanism. Applied Catalysts, 1985.16:103-121[9] Wornat, Nelson. Effect of Iron Exchanged Calcium on Brown Coal Tar. Energy and Fuels, 1992 ,6:136- 142[10] Tyler R J. Flash Pyrolysis of Coals 1. Devolatilization of a Victorian Brown Coal in a Small Fluidized. Bed Reactor. Fuel,1979.58:680-686[11] Tyler R J. Flash Pyrolysis of Coals: Devolatilization of Bituminous Coals in a Small Fluidized- Bed Reactor. Fuel, 1980.59;218- 226[12] Solomon P R，Hamblen D G，Carangelo R M et al. General Model of Coal Devolatilization. Energy and Fuels, 1988,2:405EFFECT OF CaO ON TAR CRACKING IN A RAPID-PYROLYSISFIXED BED REACTOR .Jia Yongbin Huang Jiejie Cheng Zhonghu and Wang Yang(Institute of Coal Chemistry, Chinese Academy of Sciences, 030001 Taiyuan)ABSTRACT The effect of CaO catalysts on tar cracking in a rapid- pyrolysis fixed bed reac-tor was studied in order to cut down the yield of tar in pyrolysis or gasification process. The re-sults show that minimum yield of tar was gained in the presence of CaO-3. The sequence ofcatalytic activities is:CaO- 3>CaO- 2>CaO-1. In the meantime, the effect of CaO-3 on tar crack- .ing reaction at different temperatures is also discussed.KEY WORDS tar cracking. CaO, rapid-pyrolysis, fixed bed reactor