松木屑催化热解及热解油分析

以松木屑为原料,选取无水Na2CO3、无水Al2O3、凹凸棒土、ZSM-5共4类催化剂,利用管式炉实验及色质联用(GC-MS)分析仪进行热解特性研究,探索了热解产物产率和组分特性的变化规律.实验结果表明,松木屑在热解温度为550,℃时,产油率达到最大值51.47%(质量分数);无催化剂条件下松木屑热解油主要成分为酸类化合物,加催化剂条件下松木屑热解油主要成分为酸类和酮类化合物,催化剂的加入主要影响了呋喃类、醇类、糖类和含氮类化合物的质量分数.ZSM-5催化剂的催化性能最佳,其能够提高热解油产率,其对应的热解油中酯类、呋喃类和芳香族类等能够提高热解油品质的化合物质量分数均较高,而糖类、含氮类等化合物质量分数较低,能够提高热解油的稳定性.     

氢氧化钾催化木屑热解特性影响研究

为了考察钾盐催化剂对生物质热解特性的影响,实验以木屑为原料,采用浸渍方法加入不同质量KOH,干燥和粉碎后进行热重和热解实验。实验中使用热重分析仪对样品进行热重实验,采用Starink法进行动力学分析,使用自行搭建的固定床热解炉研究热解温度和KOH添加量对木屑热解的影响。热重结果表明,加入KOH后热解温度降低,改变了木屑热解路径,降低了热解失重速率。动力学分析结果表明,加入KOH后使木屑主要热解区间表观活化能降低。热解实验结果表明,加入KOH后,木屑热解产物中热解油产率降低,热解合成气和半焦产率增加。热解产物经分析发现,加入KOH后,热解合成气中氢气含量显著增加,热解油品质有所改善,低KOH添加量对半焦孔隙结构影响较小,高KOH添加量使半焦的孔隙更加发达。     

杨木屑热解过程及动力学研究

运用热重分析法研究了氮气下杨木屑的热解过程.在不同的升温速度(5、15、30℃/min)下,对热解TG、DTG、DSC曲线分析,得出杨木屑热解分干燥、预热解、热解和煅烧4个阶段,并且热解随着升温速度的提高出现了热滞后现象.最后通过比较1、1.5、2、3级反应动力学模型,确定1级反应为杨木屑热解的动力学模型,并求出了热解反应的活化能和频率因子.     

污泥与木屑共热解特性研究

文章采用污泥、木屑为原料,在氮气气氛下进行热重实验,研究了升温速率和木屑添加量对污泥与木屑共热解特性的影响规律,并进行动力学分析。研究结果表明:随着升温速率的增加,样品挥发分析出阶段向高温方向移动,最大失重速率增加;随着木屑添加量的增加,样品总失重量及最大失重速率均显著增加。动力学分析认为:污泥热解的反应机理为三维扩散,机理函数为Z-L-T函数;污泥与木屑共热解的反应机理为成核和生长,机理函数为Avrami-Erofeev函数。污泥热解活化能为287.29～390.57 kJ/mol,污泥与木屑共热解活化能为170.16～277.05 kJ/mol,木屑的加入降低了污泥的热解活化能。     

生物质与云南褐煤共热解特性研究

选取一种典型的生物质样品(木屑),将木屑与褐煤分别以15∶85、30∶70、50∶50的质量比例混合.采用热重分析法,在某一特定升温速率下,对各种混合物样品进行热解实验,探讨了单独木屑与褐煤热解特性的差异以及它们共热解时对褐煤热解过程的影响.实验研究表明,木屑与褐煤的热解特性差异较大,木屑的热解温度低,热解反应速度较快,褐煤的热解温度高,热解速度相对较慢.木屑与褐煤共热解特性并不是单独褐煤和单独木屑的简单叠加,而且木屑与褐煤混合热解过程的放热量和木屑的混合比例关系较大.     

木屑水蒸气气化热重分析及合成气释放特性

试验研究了木屑在水蒸气气氛下的热失重行为及气化过程中合成气释放特性。首先采用TG-DTA对木屑样品进行了水蒸气气氛下的热重行为分析,结果表明,木屑气化过程可以分为挥发分释放和半焦气化两个阶段,分别可由二级反应动力学和三维扩散Ginstling-Broushtein方程描述,对应的表观活化能分别为87.014kJ/mol和103.35 kJ/mol。此外,在自制的固定床气化反应装置上,研究了生物质气化过程中挥发分释放和半焦气化阶段合成气释放特性。另外,半焦水蒸气气化阶段对气体中合成气含量和H2/CO起到决定性作用,通过合理调控半焦气化阶段反应条件,可以得到合适化学当量比的生物质合成气。     

松木屑乙二醇/甲醇复合溶剂液化及液化产物分析

以松木屑为原料,氢氧化钠为催化剂,乙二醇/甲醇复合溶剂为液化剂,考察了溶剂体积比(乙二醇/甲醇)、催化剂用量、液化温度、液化时间对液化转化率的影响,得到了较佳的液化条件:溶剂比(乙二醇/甲醇)50/150,NaOH用量为2 g、反应温度为320℃、液化时间为10 min,该条件下液化转化率为94.5%。利用GC-MS对液化油进行分析,结果显示,液化油组成非常复杂,主要含有烃、醇、醛、酮、酸、酯、酚类等物质。利用红外光谱对松木屑及其液化残渣和液化油进行了分析,分析表明,液化残渣中含有较多的木质素及其降解产物的缩合物,液化油中羟基含量较多。     

印染污泥与木屑混燃特性及动力学

采用综合热重分析法,在不同升温速率及印染污泥与木屑不同比例混合条件下,对印染污泥、木屑及其混合物的燃烧特性进行了研究.结果表明,印染污泥的热重曲线存在4个明显的失重峰,分别与水分的析出、两个挥发分的析出以及固定碳的燃烧阶段相对应.混合试样燃烧过程中,污泥和木屑基本保持各自的挥发分析出特性,其燃烧曲线位于污泥和木屑燃烧曲线之间,且混合试样微熵热重曲线的变化趋势与组成比例较大的成分DTG曲线变化趋势较为接近.污泥与木屑混合后其综合燃烧特性指数SN有所增大,说明挥发分含量越高对应的燃烧特性越好;采用积分法(Coats-Redfern方程)计算得到各阶段燃烧反应的机理方程及相应的活化能参数,分析表明单一印染污泥燃烧的活化能较低,活化能的大小与试样的燃烧阶段是相对应的.     

升温速率和水分含量对木屑热解过程和特性的影响

以木屑为研究对象进行热重分析试验,利用TG/DTG曲线分析了木屑热解的基本特性,包括热解区间、最大热解速率对应的温度、不同加热速率和水分含量对热解过程的影响.试验结果表明:木屑的失重过程主要由干燥、预热、挥发分析出和炭化4个阶段组成;随着升温速率的增大,TG和DTG曲线移向高温区,半焦产率降低;水分含量的增大在一定程度上促进了木屑热解反应的进行,使半焦产率升高.     

升温速率对煤热解特性影响的TG/DTG分析

利用热重法对我国四种典型动力用煤在不同升温速率(20℃/min、35℃/min、50℃/min、75℃/min、100℃/min)下的热解过程进行了研究.由各工况热重曲线得到热解特征参数,利用微分法与积分法相结合的方法求得了各煤样的动力学参数以及机理函数.分析比较了不同煤种、不同升温速率下的热解特性.结果表明,中温段热解反应最剧烈,活化能也最大;随着升温速率的提高,各煤样平均活化能增加.     

Experimental study on the key factors affecting the gasification performance between different biomass: Compare citrus peel with pine sawdust

This work aims to reveal the advantages of citrus peel gasification and investigate the key factors affecting gasification performance. The gasification performance of citrus peel and pine sawdust are compared in a fixed bed reactor, and the reactivity and properties of biochar were investigated. The results showed that the H₂ yield and carbon conversion efficiency of citrus peel gasification were 34.35 mol/kg_biomass and 66.30%, respectively, which were higher than those of pine sawdust. Due to the high reactivity of citrus peel char, it only takes 100 min for the citrus peel to complete the gasification reaction, which is significantly faster than pine sawdust. Although the specific surface area of citrus peel char is lower than that of pine sawdust char, both the low degree of graphitization and the high catalytic index (2426.96) are favorable for the conversion of char, which ultimately lead to the high reactivity of citrus peel char.     

松木锯屑在N2和CO2气氛下的热解特性研究

对松木锯屑在N2和CO2气氛下的热解反应进行了分析,分别运用Ozawa法和Coats-Redfern法求得松木锯屑在N2气氛下的反应活化能与适合的机理函数。试验结果表明:在CO2和N2气氛下,松木锯屑热解过程分为干燥、热解预热、热解和高温煅烧4个阶段。随着升温速率的提高,热解曲线向高温一侧移动;较之在N2气氛下的热解过程,松木锯屑在CO2气氛下热解完成后的残余质量更少,由此可推断:CO2气氛有利于热解产生更多的气体产物。     

Effect of fractional condensers on characteristics,compounds distribution and phenols selection of bio-oil from pine sawdust fast pyrolysis

Bio-oil is a multicomponent mixture of more than 400 types of organic compounds, with high water content. Fractionation of bio-oil may be a more efficient approach for primary separation of bio-oil. In this work, to better understand the effect of fractional condensers on bio-oil yield, physicochemical characteristics, compounds distribution and phenols selection during biomass fast pyrolysis process, a semi-automatic controlled fluidized bed reactor biomass fast pyrolysis system with four-stage condensers was developed. Average temperatures of Condensers 1, 2, 3, 4 were 32.39 °C, 26.74 °C, 24.06 °C and 23.68 °C, respectively. And the bio-oil yields of Condenser 1, 2, 3, and 4 were 26.82%, 7.31%, 1.48% and 9.69%, respectively. Bio-oil collected from Condenser 4 had the lowest water content (9.68 wt%), the lowest acidity (pH = 3.67), and the highest HHV (29.2 MJ/kg). The highest relative contents of compounds collected from Condenser 1, 2, 3 and 4 were 1-(4-hydroxy-3-methoxyphenyl)-2-Propanone (6.95%), trans-Isoeugenol (6.63%), Creosol (5.28%), and trans-Isoeugenol (6.69%), respectively. Fractional condensers affected the compounds distribution, but it has a stronger effect on relative heavy compounds (molar mass > 250) and a weaker effect on relative light compounds (molar mass < 200). Fractional condensers were more conducive to the selection of phenols with relative yield of more than 30%. Phenols, acids and furfurans tended to distribute at higher temperature, while alcohols, ethers and hydrocarbons tended to distribute at relative lower temperature, but the difference was small. The research has provided a reference for the production of bio-oil.     

Study on catalytic properties of potassium carbonate during the process of sawdust pyrolysis

In order to investigate the effect of potassium carbonate on biomass pyrolysis properties, sawdust was used as raw material and different amounts of K₂CO₃ were added by impregnation method to carry out thermogravimetric and pyrolysis experiments. The effects of pyrolysis temperature and the amount of K₂CO₃ addition on the pyrolysis of sawdust were studied using a self-made fixed-bed pyrolysis furnace. Calculation of pyrolysis kinetics shows that the existence of K₂CO₃ catalyst changes the pyrolysis path of sawdust, so that the activation energy of pyrolysis sawdust decreases at low temperature and increases at high temperature. The pyrolysis experiments shows that the addition of K₂CO₃ and the increase of pyrolysis temperature both reduce the yield of the pyrolysis oil of sawdust and increase the yield of the pyrolysis syngas. However, K₂CO₃ catalyst promotes the yield of char, the increase of pyrolysis temperature decreases the yield of char. Analysis of the pyrolysis products finds that the addition of K₂CO₃ and the increase of pyrolysis temperature both improve quality of the pyrolysis oil, form more microporous surface of char, and increase the hydrogen content in the pyrolysis syngas. It is considered that the optimal process for producing pyrolysis syngas is 900 °C of pyrolysis temperature and 10% of K₂CO₃ addition.     

Co-gasification of coal gangue and pine sawdust on a self-made two-stage fixed bed: Effect of mixing ratio

In this paper, the synergistic effect of co-gasification for coal gangue and pine sawdust was studied on a self-made two-stage gasification fixed bed experimental device. The results indicated that there was synergistic effect between coal gangue and pine sawdust. With the gasification temperature was 850 °C, the catalytic reforming temperature was 900 °C, the steam flow was 2 ml/min and the mixing ratio of coal gangue and pine sawdust was 1:1. The co-gasification synergistic effect yields the best results, the H₂ volume fraction reached its highest value of 37.2%, with a synergistic coefficient of 0.22. Under this condition, the number of mesopores in co-gasification char was the largest and the absorbance of the hydroxyl (-OH) functional group was the smallest. The alkali metal (K, Ca) content reached a maximum of 22.18%, which was conducive to the formation of hydrogen.     

Effect of pine sawdust on the behavior of arsenic and sulfur during slow heating pyrolysis of Shanxi Tuanbo-2 coal

Effect of pine sawdust on the removal of arsenic and sulfur during Shanxi Tuanbo-2 coal pyrolysis was investigated. Results showed that adding pine sawdust could increase the removals of arsenic and sulfur during Shanxi Tuanbo-2 coal pyrolysis, and when the ratio of the pine sawdust was 50%, the arsenic removal was the highest; at this ratio, the total sulfur removal also was the highest. Adding pine sawdust also increased pyritic sulfur and organic sulfur removal. Furthermore, results also indicated that adding pine sawdust made arsenic associated with sulfates and monosulfides and arsenic in stable forms escape more easily.     

Effects of Fe2O3 on pyrolysis characteristics of soybean protein and release of NOx precursors

The effects of ferric oxide (Fe₂O₃) on the pyrolysis characteristics of soybean protein and the release of precursors to nitrogen oxides (NOx) were studied using thermogravimetry and mass spectrometry. The results show that, as the content of Fe₂O₃ increases, there is no major difference between initial and peak temperatures of protein pyrolysis samples. Moreover, between the temperature range of 204 and 550°C where weight loss mainly occurs, total weight-loss rate decreases before increasing, with obvious weight loss occurring around the temperature of 650°C. Fe₂O₃ displays both inhibiting and promoting effects on the precipitation of nitrogen-containing gases such as ammonia (NH₃), hydrogen cyanide (HCN), isocyanic acid (HNCO), and acetonitrile (CH₃CN), with the inhibition effect prevailing over promotion effect on the whole.     

玉米秸秆催化热解试验研究

利用自行设计的固定床快速热裂解试验系统,研究了玉米秸秆催化热解(催化剂为CaO)规律及催化剂对热裂解产物分布的影响,探讨了CaO的催化机理.结果表明,750℃时,CaO在促进焦油裂解的同时,也促进了焦炭和气体产物的生成;CaO对气体产物中的CO2具有吸附作用,降低了CO2的含量,它对大分子脱氢具有明显的催化选择性,增加了产气中H2的含量.在试验中采用了2种催化剂添加方式,添加比为1:1(质量比);分析了不同催化剂添加方式对催化热解的影响;采用悬挂方式时产气率达到57.68%;采用混合方式时,燃气中H2含量高达33.33%,燃气热值达到了12.389 MJ/m3.     

花生壳和松木屑固定床低温热解特性的实验研究

分别以花生壳和松木屑为原料在固定床上进行低温热解实验,探究热解温度对热解产物产率的影响。利用气相色谱-质谱联用仪(GC-MS)对热解所得生物油组分进行定性分析,并对生物油中的愈创木酚进行定量分析。结果表明:花生壳和松木屑热解过程中半焦的产率都随热解温度的升高而降低;生物油的产率都随热解温度的升高先升高后降低,且都在500℃达到最大值,最大产率分别为13.14%和20.41%;热解气体的产率都随热解温度的升高而升高。两种生物质热解生物油中各类组分的含量随热解温度的升高发生不同的变化,其中愈创木酚的含量都随热解温度的升高先升高后降低,并在400℃达到最大值。     

锯末制备生物质成型燃料的试验研究

分别采用冷压成型和炭化成型工艺以锯末制备生物质成型燃料。冷压成型工艺主要考察原料水分、成型压力对燃料的成型性能影响。试验结果表明:原料水分为12%~16%,成型压力为60 MPa的条件下能够制得成型性能较好的生物质成型燃料,其密度与抗跌强度分别能够达到0.94 g/cm3和99%;炭化成型工艺主要考察混合料水分、无烟煤配比、J型粘结剂添加量、成型压力对燃料的成型性能影响。试验结果表明:无烟煤配比为50%、混合料水分为30%、J型粘结剂添加量为8%、成型压力为45 MPa的条件下能够制得成型性能较好的优质生物质成型燃料,其密度与抗跌强度分别为0.93 g/cm3和99.3%。