以竹屑为原料,使用氧气-水蒸气作为混合气化剂,在固定床气化反应器中进行竹屑的氧气-水蒸气气化实验,考察了气化温度、水蒸气流量和氧气用量比对竹屑气化制备富氢燃气的影响.研究结果表明:气化温度和水蒸气流量均对竹屑燃气中氢气体积分数影响较大,氢气体积分数随着气化温度的升高呈稳步增长趋势,随水蒸气流量增加呈先增加后减少趋势,分别在气化温度900℃和水蒸气流量0.7 mL/min时达到最大值;而随着氧气用量比的增加,氢气体积分数变化不明显.竹屑氧气-水蒸气气化制备富氢燃气最佳的气化条件为气化温度900℃、水蒸气流量0.7 mL/min、氧气用量比0.30,此条件下气化制备的燃气中氢气体积分数32.04％,热值11.37 MJ/m3,产气率1.40 L/g,燃气中CH4体积分数8.82％,CO体积分数26.34％,CO2体积分数30.55％,C2Hm体积分数2.24％.

稻壳是稻谷加工的剩余物,稻壳炭是稻壳热解得到的副产物;稻壳炭中富含碳和二氧化硅,与水蒸气反应可以得到富氢气体,同时得到富含二氧化硅的稻壳灰副产物,具有与硅灰相媲美的高硅火山灰活性,可以作为高性能的无机材料、建筑材料、吸附材料及催化剂载体等高附加值的产品加以利用.为获得富氢气体及富硅材料,以热解副产物稻壳炭为原料,在固定床反应器中以水蒸气为气化剂气化制备富氢气体,探究稻壳炭的气化反应特性及气化产物分布与温度的关系,调控不同温度条件下的稻壳炭气化反应,通过生成气的组分分析及灰分生成率研究了气化温度对富氢气体产率、组分分布的影响;研究了稻壳炭气化固体剩余物稻壳灰的特性,对其进行SEM、XRD等表征,分析了其主要成分、表面结构等,研究反应温度对稻壳灰材料结构的影响.研究结果表明,反应温度的增加使气化产气率、产氢率及炭转化率均增加,950℃为最佳产气反应温度,产气率为2.1 L/g生物质,产氢率达到107.91 g/kg生物质,炭转化率为81.83％;气化固体剩余物稻壳灰的结构性质的变化趋势,则是反应温度越高,剩余物稻壳灰的灰分含量越高,SiO2含量也越高,但其片层结构破坏程度越严重,同时其中更多的无定形SiO2形成结晶,850℃以上则Si02更容易以晶体形式存在.

以木屑气化剩余炭粉为原料,通过添加活化助剂次氯酸钙和使用黏结剂羧甲基纤维素钠、沥青、酚醛树脂成型,经炭化、水蒸气活化,制得成型活性炭.考察了黏结剂种类和添加量、活化助剂添加量、水蒸气活化条件对制备活性炭性能的影响,结果发现:沥青、酚醛树脂作黏结剂时,单独和配合使用都可以制备性能较好的成型活性炭;活化助剂的添加有利于提高制备活性炭的吸附性能,但会影响活性炭强度和得率.当活化助剂添加0.3 g、水蒸气活化温度850℃、水蒸气活化时间45 min、水蒸气流量1.5 mL/min时,沥青(添加量25 g)为黏结剂制备的活性炭AC1、酚醛树脂(添加量6 g)为黏结剂制备的活性炭AC2、沥青(添加量10 g)和酚醛树脂(添加量3 g)共为黏结剂制备的活性炭AC3,3种样品的碘吸附值最高超过900 mg/g,亚甲基蓝吸附值最大达180 mg/g,强度最高为99％,得率最高为32.9％;活性炭的微孔率最高大于83％,比表面积和总孔容积最大达697.04 m2/g和0.38 cm3/g.

天然气因其清洁、高效、使用方便的特点而有着其他化石能源无法比拟的优势。随着天然气需求量的增加,天然气供需矛盾也逐渐凸显,生物质合成气催化制取合成天然气成为解决天然气供需矛盾的技术之一。针对生物质合成气甲烷化过程中存在的问题,从反应过程、催化剂、反应器等方面阐述了生物质合成气甲烷化研究现状;对比了不同催化剂的催化性能,分析得出Ni基催化剂是最适合工业化的甲烷化催化剂之一。列举了国外一些固定床和流化床甲烷化反应器工业化的案例,分析了其各自的生产工艺及优缺点,得出流化床是甲烷化反应器中较为有前景的反应器,并对生物质合成气催化制取合成天然气技术的发展方向进行了展望。

Biomass steam gasification is an efficient thermochemical process,and it can converts raw materials to hydrogen-rich syngas which can be applied widely.It has potential to substitute fossil fuels to produce hydrogen.Different biomasses greatly affect the gasification and hydrogen production capacity.The choice of feedstocks is crucial for gasification to produce hydrogen-rich syngas.In addition,the adjustment of operation parameters including reaction temperature,steam flow rate,catalyst and adsorbent can optimize the quality of syngas and enhance hydrogen concentration.In this paper,the effect of operation conditions on biomass steam gasification for hydrogen-rich syngas was reviewed.Meantime,the research status of bio-char gasification for hydrogen-rich syngas was discussed.High quality of hydrogen-rich syngas can be produced by char gasification,which is kinetically limitation,thus this process requires catalyst to improve char reaction rate.It was also introduced the catalytic mechanism of potassium salts.The prospect of hydrogen-rich syngas application was proposed,including high purity hydrogen for fuel cell and synthetic natural gas.

以木屑炭为原料,在上吸式固定床气化炉中进行水蒸气气化制备合成气,考察了温度和水蒸气流量对木屑炭水蒸气气化的产物分布、炭转化率、产气率、组成含量和H2/CO值的影响.结果表明:升高温度有助于木屑炭气化,炭转化率和产气率分别在950℃下达到最大值99.2％和4.16 L/g,但温度升高会导致H2从65.8％降至61.2％,同时H2/CO也呈下降趋势,从10.3降至3.35;水蒸气流量的增加可提升H2,从59.8％升至62％,但流量升至0.6 g/min时气化结果趋于稳定.水蒸气气化的最佳操作条件为900℃,水蒸气流量0.6 g/min,此条件下炭转化率、产气率和热值分别达到93.3％、4.06 L/g和9.04 MJ/m3,H2/CO值为4.11,适合于合成甲烷.

The steam gasification experiments of sawdust for production of hydrogen-rich gas were carried out in the high-temperature fixed bed reactor using steam as gasification agent and CaO as catalyst.The effects of the molar ratio of CaO and carbon element of sawdust (n(Ca)/n(C)), temperature and steam flow rate on gasification characteristics were investigated.The results showed that with the increament of n(Ca)/n(C) from 0 to 1.0, the volume fraction of hydrogen increased from 45.58% to 58.62%, and the dry gas yield increased from 1.04 m3/kg to 1.38 m3/kg;the hydrogen content and dry gas yield only showed a modest increase as the n(Ca)/n(C) increased to 1.5. With increasing the gasification temperature from 700 to 750 ℃, the volume fraction of hydrogen significantly increased from 51.78% to 58.62%, and that of carbon dioxide decreased from 19.89% to 12.60%;as the temperature kept rising, the hydrogen content and the low heating value decreased.By increasing the steam flow rate from 0.1 g/(min·g) to 0.34 g/(min·g), the volume fraction of hydrogen increased from 58.62% to 62.55%.However, the hydrogen content, the hydrogen yield and the low heating value decreased when the steam flow rate was higher than 0.34 g/(min·g).The optimized conditions with CaO as catalyst were n(Ca)/n(C)=1, the gasification temperature 750 ℃ and the steam flow rate 0.34 g/(min·g).Under these conditions, the volume fraction of hydrogen was 62.55%, the hydrogen yield was 85.08 g/kg, the low heating value was 11.41 MJ/m3.

在高温固定床反应器中,以木屑炭为原料,进行木屑炭CO2气化的特性研究.考察了气化温度和CO2流量对燃气各组分体积分数、热值、固体产率、产气率的影响.结果表明:随着气化温度从750℃升高到950℃,CO体积分数明显增加,CO2体积分数明显减少,燃气热值增加较明显,而从950℃升高到1 050℃时,燃气热值增加趋势减缓.CO2作为气化介质,随着其流量增加,固体产率减少,气体产率增加,燃气组分中CO2体积分数明显增加,CO体积分数先增加后减少,燃气热值先增大后减小.CO2流量为15 mL/(min·g)时,燃气热值最大.气化温度950℃、CO2流量15 mL/(min·g)为较佳的气化条件,此时气化制备的气体中CO体积分数为51.51％,CO2体积分数为37.99％,燃气热值为8.03 MJ/m3,产气率为0.78 L/g.

Steam catalytic gasification experiments of pine sawdust to produce hydrogen-rich gas were carried out in a high-temperature fixed bed reactor with Ni-CaO as the catalyst. The influence of catalyst dosage,gasification temperature and steam flow rate on hydrogen content were investigated. The results showed that by increasing the catalyst to sawdust ratio from 0 to 1.5(g/g),the hydrogen content was increased from 45.58% to 60.23%,and the hydrogen yield was increased from 38.80 g/kg to 93.75g/kg,whereas the hydrogen content and hydrogen yield only showed a modest increase when the ratio was changed into 2. Increasing the gasification temperature from 700℃ to 750℃ significantly increased the hydrogen content from 54.24% to 60.23%,and decreased the carbon dioxide content from 21.09% to 13.18%,but higher temperature gave rise to a decrease in the hydrogen content and the low heating value.When the best gasification temperature was taken as 750℃,and the catalyst to sawdust ratio and the steam flow rate were 1.5(g/g) and 0.34g/(min·g),the resulting hydrogen content,dry gas yield and low heating value were 60.23%,93.75g/kg,and 12.13MJ/m3,respectively.

Steam gasification of sawdust char for the production of hydrogen-rich gas was studied in a high-temperature fixed bed reactor.Experiments were carried out at 700-900 ℃ with steam flow rate of 0.11-0.32 g/(rmin·g) (based on the char,the same below).The effects of temperature and steam flow rate on the volume fraction of H2,gas yield,heat value and compositions were studied.The results showed that the excess steam led to a decrement of the gas heat value.Under the reaction conditions of temperature 900 ℃ and the steam flow rate was 0.32 g/(min·g),the volume fraction of H2 reached the maximum(62.53％),the heating value of the fuel gas was 8.99 MJ/Nm3 and the gas yield was 2.75 L/g.And the homogeneous volumetric model and shrinking core model were employed to obtain the corresponding kinetic parameters.The shrinking core model fitted the experimental data better than the homogeneous volumetric model.The acitivity energy and the pre-expenential factor obtained with homogeneous volumetric model were 88.67 kJ/(mol·K) and 2 976.55 min-1.The activity energy of the shrinking core model was 91.78 kJ/(mol·K) and the corresponding pre-exponential factor was 2 872.82 min-1.

利用热重分析仪对稻壳与褐煤单独及共热解过程进行研究.动力学分析选用Coats-Redfern模型和分布活化能模型(DAEM),发现Coats-Redfern模型无法在整个温度区间内对生物质的热解进行预测,只能将热解过程分为多段的单一反应;DAEM法计算得到的热解活化能随原料转化率的增大,大体呈现升高—平稳—升高的趋势;稻壳热解平均活化能约为182 k J/mol,褐煤为288 kJ/mol,共热解因混合比例的不同而有所差异,为180～190 kJ/mol,远小于褐煤,推测生物质的存在对煤炭热解具有一定的促进作用;对比Coats-Redfem模型和DAEM模型对于共热解过程动力学分析,发现DAEM模型更适于模拟稻壳与褐煤共热解过程中的活化能变化情况.

以木屑为原料,利用高温固定床反应器,通过高温水蒸气气化制取富氢燃气,考察了气化温度(750～1000℃)和水蒸气流量(0.290～1.409 g/min)对燃气中H2的体积分数、热值、产气率等指标的影响.实验结果表明:不同的气化温度和水蒸气流量对燃气各组分体积分数有很大的影响,较高的气化温度和适当的水蒸气引入量有利于氢气的产生,但是过高的温度和过量水蒸气的引入会造成燃气热值降低.综合考虑各方面影响,水蒸气气化的最适条件为气化温度900℃,水蒸气流量1.033 g/min,在该条件下,所制得的气化燃气中H2体积分数为45.74%,热值为11.69 MJ/m3,产气率为1.96 L/g.

采用TG-FTIR联用的分析方法对木屑与煤共热解产物进行分析,结果发现,木屑与煤共热解产物不是两者单独热解的简单叠加,而是木屑与煤协同反应相互促进或抑制的结果.煤化程度越高木屑与煤共热解过程中CO和CH4的产率越多,CO2的产率越少,液体和固体产物越多.木屑与煤掺混比例对于共热解产物的影响规律性不是非常明显,对于CO和CH4,掺混比例5∶5时产率最低;CO2在共热解温度＜500℃时,掺混比例5∶5时产率最高,而在共热解温度＞500℃时,随着煤的掺混比例的增加产率逐渐减小.木屑与褐煤的共热解固体产率随着掺混比例的增加逐渐增大,木屑与无烟煤的共热解固体产率正好相反.

在固定床反应器中,以水蒸气为气化介质,探讨不同CaO添加量和压力对松木屑气化结果的影响.结果表明CaO具有C02吸附和催化焦油裂解双重作用.在800℃、0.5 MPa下,添加一定量CaO,CO2浓度降幅达到50％以上,H2浓度增加到59.35％,气体热值达到12.97 MJ/m3;在900℃,Ca/C(CaO所含Ca与松木屑所含碳的物质的量之比)为1.0时焦油有最小值,为2.43 g/m3.此外,增加反应压力,H2和CO2的浓度出现缓慢增加趋势,CO浓度减少,CH4浓度无明显变化,同时气体中焦油含量出现降低趋势,该实验中最低值可达1.99 g/m3.

褐煤与木屑及在250℃/30 min的条件下烘焙后的木屑进行不同比例的掺混,分别通过热重分析仪和900℃高温热解研究其共热解特性.研究表明,木屑通过烘焙后,初始热解温度升高,热解剩余物增加,更接近褐煤;褐煤掺混的热重分析过程中,两种木屑的添加有利于提高反应物的转化率,但木屑的作用更强;与褐煤的高温共热解过程中,两种木屑的添加有利于提高气体和液体产物产量,烘焙木屑比木屑更有利于气体产生,而木屑更有利于液体产生;两种木屑的添加还有利于H2的产生,但木屑的作用更明显;烘焙木屑和褐煤共热解与两种物质单独热解焦油成分对比得出,共热解有利于使焦油成分变的简单,烘焙木屑与木屑单独热解焦油成分对比得出,烘焙过程可有效减少焦油中的物质.

Rice husk was torrefied at the condition of 250 ℃/30 min,then blended it with anthracite, bituminous coal and lignite at different ratios,which had different coalification degrees. The mixtures were analyzed by Thermal Gravimetric Analyzer (TGA) and co-pyrolysis experiments. The results showed that torrefied rice husk had the advantage of raising conversion of the anthracite and bituminous coal by analyzing the TG curves,the increased rates were no more than 5%,but the torrefied rice husk had a negative effect on the conversion of lignite. In the experiments of co-pyrolysis,with the increase of torrefied rice husk in anthracite and bituminous coal,the solid products of the mixtures were lowered and the the gaseous products were increased,but the torrefied rice husk had an inhibitive effect on lignite. The addition of torrefied rice husk in the blends had the effect of accruing the content of H2 and reducing the content of CO2. So changing the percentage of torrefied rice husk in the mixtures had the effect of regulating the component of syngas.

在常压固定床反应器中进行木屑高温水蒸气气化制取合成气研究.分别在750～1000℃温度和0.32～1.02g/min水蒸气流量下进行实验,反应时间为10 min.主要研究反应温度和水蒸气流量对碳转化率、合成气产率及合成气组分的影响.研究结果表明,木屑水蒸气气化具有很高的反应活性,合成气产率在0.81～1.74 L/g之间;反应温度和水蒸气流量对碳转化率和合成气热值及组分影响显著;在反应温度950℃,水蒸气流量0.67 g/min时,碳转化率达到最高值99.47％;合成气主要由H2、CO、CO2、CH4及少量CnHm组成,其中(H2+CO)比例达到63％～75％,合成气热值在10.5～11.5 MJ/m3之间,H2/CO比在1.0～2.3之间.

In order to solve the problems in biomass briquette combustion including low efficiency, exhausting gas and smoke, slagging easily and difficulty to remove, we designed a new type of combustion machine which adopt staged combustion mode. The steam boiler heating experiments were conducted and the results showed that the output of boiler was 5 300 MJ and combustion efficiency was 99. 36 %. The combustion gas contained CO with 0. 001 45% and the contents of SO2 and NOX were 0. 01 % and 0. 06 %, respectively. Slag could be automatically broken and slagging-off under the help of automatic slag broken& clean device.

The composition of tar distillations gained by simple distillation was analyzed with GC-MS analysis technology. The main component of all distillations is phenol and its homologue and heterocyclic compounds, in which guaiacol and its homologue are existed as azeotrope. Under nitrogen atmosphere, the tar pyrolysis behavior was investigated with different heating rates of 5, 10, 20, 30°C/min as same as its distillations with the heating rate of 10°C/min. The kinetic method of Coats-Redfern was used to analyze the TG data to identify reaction parameters which reflect reaction mechanism. And the results show that the reaction can be well described by first reaction order and two stages model.

Activated carbon was prepared from solid residue of sawdust liquefaction by phosphoric acid activation and steam activation,respectively.The yield and properties of the two activated carbons were investigated detailedly.The result showed that the two methods can prepare activated carbon with high yield.The yield of activated carbon from phosphoric acid method is 69.8%,whilefrom steam method is 37.3%.The activated carbon with phosphoric acid activation appears intensive pore width distribution on the microstructure.Through analysis of nitrogen adsorption and desorption isotherm,its average pore diameter is 1.99 nm,BET surface area is 1 255 m2/g.Pore width distribution of activated carbon with steam activation is scattered.The micropore and mesopore exhibit continuous distribution-with average pore diameter of 2.46 nm,BET surface area of 665 m2/g.Nitrogen adsorption and desorption isotherm appears lag circle in high relative pressure.