生物质流态化气化技术研究

第24卷第2期林产化学与工业Vol 24 No. 22004年6月Chemistry and Industry of Forest ProductsJune 2004STUDY ON INDUSTRIAL TECHNOLOGY OFGASIFICATION OF BIOMASS WITHFLUIDIZED-BEDYING Hao, JIANG Jian-chun, DAI Wei-di, LIu Shi-cai, Gao Yi-weiInstitute of Chemical Industry of Forest Products CAF Nanjing 210042 ChinaYING HAbstract: Industrial technology of gasification and catalytic gasification of biomass with inner recycled conicalfluidized bed as gasifier was discussed. Experimental results indicated that calorific value of gas from wheat strawgasification is higher than those from rice straw and husk while calorific value of gas from sawdust gasification is thehighest. Calorific value of gas from non-catalytic gasification is about 40% higher than that from down-up gasifieratalytic gasification experiment showed Cao has the effect to markedly increase calorific value and reduce thecontent of CO in gas Na, CO, has the effect to enhance the content of H,. When reaction temperature reached 800Caddition of catalytic agent can obviously enhance the gas calorific valueKey words: biomass catalytic gasification fluidized-bed gasificationCLCr:TO351.2Document code AArticle ID0253-2417(200402-0001-05生物质流态化气化技术研究应浩,蒋剑春,戴伟娣,刘石彩,高一苇〔中国林业科学研究院林产化学工业研究所,江苏南京210042)摘要论述了在锥形流态化气化炉内对生物质原料进行气化和催化气化的工程化应用试验研究。研究结果表明淩草原料气化所产生的煤气热值比稻草和稻壳都高木屑气化所产生煤气热值最高非催化气化条件下流化床气化产生的煤气热值比下吸式气化炉产生的煤气热值提高40%左右催化气化试验发现CaO能明显提高煤气热值、降低CO组分№aC3催化气化能提高气体H2的含量。但是对气化产生的气体热值流态化空气气化中在710℃以下低温时无明显的影响当温度达到800℃时添加催化剂能明显提高气体的热值关键词泩物质滙化气化流化床汽气化Fluidized-bed gasifier of biomass is a recently developering operating processsince the 70's of last century. Compared with fixed gas中国煤化工ation has the advancedmerits of evener mixed contact for gas-solid reaction whichCNMHGeed larger gas-solidReceived date 2003-10-0sBiography痖溦1963-)男浙江永康人副研究员硕士生导师主要从事生物质能技术开发应用及林产品化学加工工艺和工程设备设计研究卫mailinjyingh@jlonline.com林产化学与工业contact area evener reaction temperature higher heat transfer coefficient higher reaction intensity of unit areaeasier operation controls shorter stay time of the reaction material in the reaction devices greater productioncity lower operation temperature and higher gasified calorific value than fixed bed gasifier -2] In recentyears researches have been paid attention to fluidized-bed technology deeplyRecycled fluidized-bed and pressure fluidized-bed have been developed respectively by researchers ofUSA, Britain Sweden Japan , India ,Germany Spain Belgium ,New Zealand Canada etc. Some of these tech-nologies have been applied in industry.The application technologies of biomass gasification have been developed in China since the 80s of lastcentury. Specially gasification system for civil cooking gas fuel have been spread in development area of ruralvillages. The gasifier that has been applied mainly is the fixed bed gasifier 51. Early in the 1990s,domesticresearches on gasification technology of recycled fluidized-bed had been carried out. However, gasificationtechnology of biomass in our country is still not advanced and the scale is small. Today reports on research ofcatalytic gasification and its industrial application are rare b.The purpose of this research is to investigate engineering adaptability of fluidized-bed gasifier designed byus using forestry residue and agriculture residue( such as sawdust straw ,rice husk etc. )as materials. Theresults of gasification experiment are discussed in this paperExperimental1.1 Raw materialsPulverizer was used to smash raw materials into granules smaller than 5 mm with the following indicescalorific values of wheat straw rice straw rice husk sawdust are 17 757, 16 317, 16 649 and 18784 kJ/krespetively the content of water( dry base )are 9.7%0 14 0% 11 5% and 13. 2% respectively1.2 Gasificationdesi technical process nner recycled fluidized bed and other equipment of biomass gasification system were1. 3 Analysis of gasGas was analyzed with a gas chromatography apparatus at testing place4 Choice of catalystsIn experiment choice of catalysts is very important. Based on laboratory test, CaO and Na, CO,werechosen as catalysts because of their good catalytic effect feasible nature and economy of industry application2 Results2.1 Gasification experimentGasification feature of sawdust rice straw heat straw and rice husk was respectively investigated. Duringthe trial processing of gasification temperature of gasification reaction was controlled by adjusting the amount ofair flow and the speed of adding raw material. Composition of gas flowing out from the gasification system wanalyzed. For different raw materials the selected feasible catalystdded into raw material before sendinto gasifier Sawdust or rice and wheat straw smashed into si中国煤化工5mm) were mixed withthe catalyst fully and evenly then they were constantly sentCNMHGgiven air flow amountwhen temperature of gasifier arrived at 600C. They were dried and decomposed quickly to carry out reactionto produce the gases such as CO, H, o,, Ha C, Hmetc2. 2 Influence of raw materialFig. I shows the influence of different kinds of raw material to gas composition at gasification reaction第2期应浩等生物质流态化气化技术研究temperature of 610C. Co conent is highest for sawdust H, is highest for rice straw but C, H is highest forwheat2 gas from sawdust followed by wheat straw has highest calorific value than rice straw and ricehusk. However calorific values of the later two are still higher than those obtained from down-up gasifier offixed bed usually 15 %o higher岁8710℃610℃materialsmaterials口 rice straw;■ sawdust; Im wheat straw;团 rice huskFig 1 Effects of raw material on the component Fig. 2 Effects of raw material on the calorific valueof gas from non-catalytic gasificationof gas from non-catalytic gasification2. 3 Relation of raw materials to catalytic gasificationThere are a lot of differences on gas composition produced from catalytic gasification of diverse rawmaterials. Fig. 3 shows gas composition at two different gasifying temperatures. In this situation no matter whatkind of raw materials both contents of CO and H, are the highest the content of C, Hm is the least. This phenomenon is identical with the principle of gas-solid reaction. The content of different gas constituents is inder for CO H, CHa and C, Hm. Catalytic effect on the change of gas composition is not very notablefor the same raw material. Particularly for CO , there are slight differences between catalytic and non-catalyticgasification Content of CHA under the condition of non-catalytic gasification is high. This proved that catalysishas the effect to reduce formation of CHa. Considering the kind of raw material no matter whether catalysis isadopted gasification of sawdust is superior to rice straw. This is similar to solid reaction mechanism. Takinas gasification agent the reactions chiefly occur as followsC+O2-+C02C+O2-+2C030610℃710℃15105Na, Co, non-catalytic Cuo Na, CO, non-catalyticCaO Ne, C0, non-catalyticrice strawsawdustrice strawsawdust口H2;■C0;四CH4;囡CHFig 3 Effects of catalyst on the component of gasThe reaction begins at 350C. When temperature reaches over 500C reaction becomes completely out ofcontrol and catalysis function is lost. Addition of Na, CO, favours the reaction between H,O and C ,thus Hcontent in gas produced with catalysis is obviously higher thTH中国煤化工2.4 Calorific value of gas from catalysis gasification ofCNMHGnows the influence of catalyst to gas calorific value , under the conditions of different gasificationtemperatures. At 710C calorific value of gas by non-catalytic gasification of sawdust is a little higher thancatalysis. However at 610C the gas calorific value produced using Cao as catalyst is higher than non-catalsis. We can infer from these trial results that catalyst plays a beneficial function for pyrolysis of biomass产化学与工业710℃6610℃grice straw口Ca0;■Na2CO3; I non-catalyticFig 4 Effects of catalyst on calorific value of gasFig 5 shows the relation between kinds of catalyst withtures. Content of CO, was increased at 750C by addition of Na, CO,. At 710 C content of CO, was decreasedby addition of CaO. In this test change of non-catalytic gasification is fairly small between 610-800C. Gasifi-talyzed by Cao below 710C had no obvious effect on CO content in gas. However at 800C CaOplayed a function to raise the content of CO in gas. Moreover after adding Na, CO, the content of CO would bereduced64086420710710800temp /Ctemp./℃CO content :O-Ca0H2 content:-Ca0;■Na2OO3;△CO2 content i x-Ca0;-口一Na2CO3;●- non-catalytic CH4 content:x-Ca0;-kNa2OO3;-●- non-catalyticFig 5 Relationship between temperature of catalytic gasification and its content of gas from sawdustCHA and C, H are the gas components of high calorific value. In order to get gas of high calorific value thecontent of CHa and C, Hm should be raised. In Fig. 5 content of CHa under non-catalysis gasification is higherthan catalysis gasification Na, CO, possesses clearly the function of restraining the production of CHa the effectof CaO is the second Content of H, varies remarkably Na, CO, can raise the content of H, greatly. Thus it is comparatively advantageous to add Na, CO, as catalyst for producing gas rich in H, under the conditions of takias a gasification agent and using the inner recycled conical fluidized bed as gasifier. Except the decomposition ofless organic gas under high temperature the increase of H, in gas is mainly due to the addition of catalyst byreducing activation energy to accelerate the reaction between steam and carbon Content of h, is reduced underthe condition taking CaO as the catalyst probably because of occurrence of more reactions. This occurs also intheIn gasification procession with fluidized bed ,aw mater中国煤化工 perature in a very shorttime similar to flash pyrolysis which is favourable to obtainCNMH Gse However the longerstaying time in gasifier generally 10 s results in thermal decomposition of the produced gas to increase C, Hcontent In Fig. 6 calorific value of gas with CaO catalyst is higher the maximum value reaches 9 kJ/NmBoth CaO and CaCO, catalysts increase the calorific value of gas at temperature above 710C. Calorific value isobviously raised taking Cao as catalyst and reduced taking Na, CO, as catalyst应浩等生物质流态化气化技术研究3 Conclusions8103. 1 Inner recycled conical fluidized bed developed by authors is an 95propriate gasifier for loose materials such as rice straw Wheat strawrice husk sawdust etc. Suitable operation temperature in central sec- 9 a0ion of gasifier is 600-820C. Adoption of the fluidized-bed can not a 6800teap./℃only resolve the difficulty for fixed gasifier to gasify materials of lowdensity and high ash content but also produce gas of higher calorificFig 6 Relationship between temperaturevalue than fixed bed gasifier for biomassof catalytic gasification and calo3.2 Calorific value of gas from wheat straw at 7716 kJ/Nm' is highrifie value of gas from sawduster than rice straw, Calorific value of gas from sawdust at 9 064 kJ/Nmis the highest3.3 Cao can obviously increase C, Hm and decrease CO in gas Na, CO, can increase H, content and decreaseCO content slightly in gas. Adoption of catalyst can effectively adjust the component of gas and reduce the content of CO. However addition of catalyst at reaction temperature below 710C has insignificant influence oncalorific value of gas. When reaction temperature is over 800C calorific value of gas is clearly increased3. 4 Inner recycled conical fluidized bed is a suitable and comparatively ideal gasifier for loose biomass.Under the condition of non-catalytic gasification ,gas of high calorific value about 40% higher than that ofdown-up gasifier of fixed bed can be obtained. Reaction temperature can be controlled convenientlyReferences1]黎强邱宽嶸等.流态化原理及其应瓶M]徐州中国矿业大学岀版社1994[2 JMILES TES TR ir. Overview of biomass gasification in the USA[ J ] Biomass 1989 18: 163-1[3]张进平蒋剑春金淳等.生物质流态化催化气化技术研究J]林产化学与工业200121(3)16[4 GERALD L, FRANCIS X J. Modern bioenergy-An overview of its prospects and potential[ J ] Renewable Energy forDevelopment 1999 124) 16-18[5正铁林等.农作物秸秆利用技术与设备M]北京中国农业出版社1996[6凎金淳应浩涨进平等.民用木煤气的研究J]林产化工通讯1995293)3-1旧◆旧◆◆旧◆◆旧◆◆旧旧◆旧◆阳◆◆◆◆旧◆◆◆◆◆◆◆◆◆◆◆旧◆◆◆旧◆◆◆◆旧◆林产业广交会”10月召开2004林业产业及技术应用广州博览会将于2004年10月26~29日在广州·花城(国际)展览中心举行。主办单位中国林学会承办单位疒州市今科展览服务有限公司。博览会设以下展会●木材、夹板、饰面板及设备专题展览会;●森林生态旅游专题展览会;纸品、纸板、纸浆及机械专题展览会;家具及木工机械专题展览会;林副产品、林化」林花木及木雕、根雕及机械专题展览会。中国煤化品专题展览会;●园CNMHG联系地址:510620广州市体育东路33号天盛大厦。口U154158;传真020)87577283;E-mailjk6@163.net;联系人杜齐华先生。