【作者】 范军；

【导师】 别如山；

【作者基本信息】 哈尔滨工业大学 ， 热能工程， 2015， 硕士

【摘要】 当今世界因过度使用化石燃料造成环境日益恶化和资源短缺,我国对煤的消费较大,同样面临这样的问题。生物质是清洁可持续能源,近年来它受到了能源界的广泛关注,同时也被视为化石燃料最为理想的替代能源之一。我国生物质品种丰富、资源量大,可以用生物质代替相当一部分化石燃料。造纸黑液属于类生物质,它具有生物质的一般特征,但也有其自身的特点,如COD高、碱度大、有机物含量多,未经处理直接排放会造成严重的环境污染。通常使用传统碱回收炉对木浆黑液进行处理,但处理草浆黑液的效果不理想,这是由草浆黑液粘度大、硅含量高、热值低的特点造成的。因此需要开发一种新的回收技术处理草浆黑液,本文提出使用流化床热解碱回收技术处理草浆黑液,选用芦苇浆黑液作为原料,计算了其热解反应动力学参数,研究了其反应动力学机理,并在小型流化床实验台上进行了芦苇浆黑液热解试验,得到了其热解机理,为流化床热解碱回收技术的应用提供了理论基础。首先,根据芦苇浆黑液热解的3个温度区间以及已知的芦苇浆黑液TG和DTG曲线,选用了Coats-Redfern、Flynn-Wall-Ozawa、Friedman以及Kissinger法这四种常用的热解反应动力学模型进行了热解反应动力学参数的求解,计算表明Coats-Redfern法确定的芦苇浆黑液热解反应机理是随机成核和随后生长,Flynn-Wall-Ozawa法和Friedman法回避了反应机理的选择带来的误差,其结果的准确性更高一些,Kissinger法只分析峰值点处的数据点,有些结果偏差较大。其次,以钙基沸石为床料、以氮气为流化介质,选择了530、580、630、680、730、780℃为试验热解温度,对芦苇浆黑液在小型流化床上的热解过程进行了相关试验,得到了气相、液相和固相产物,通过相应的检测手段获得了这些产物的试验结果。研究表明,较高的热解温度有利于热解过程的进行,具体表现为可获得较多的热解气且其中的可燃气占的比例较大,有利于抑制焦油的形成,降低了残留在黑液半焦中的挥发分含量,增大了碳、氢转化率,减少了碳、氢元素的损失。热解温度对各相产物的组分变化规律有明显的影响,对于气相产物热解气,随着热解温度的升高,H2和CO的体积浓度逐渐增大,CH4的体积浓度逐渐减小,CO2的体积浓度一直下降;对于液相产物焦油,其产率基本随热解温度的升高而降低,高温时多环芳烃的相对含量较多;对于固相产物半焦,其高位热值随热解温度的升高呈一直下降的趋势,其微观形貌受热解温度影响较大。综合分析,780℃是热解试验效果最理想的热解温度。更多还原

【Abstract】 In the present world, the environment is deteriorating and the shortage of resources is due to the overuse of fossil fuel. China consumes a large amount of coal and also faces this problem. Biomass is a clean and sustainable energy, in recent years it has been concern widely in the energy community and it is also considered as one of the most ideal alternatives for fossil fuel fuels. China has a rich variety of biomass and the amount of biomass is large, biomass can be used in place of a considerable portion of fossil fuels.Papermaking black liquor belongs to approximate biomass, it has the general characteristics of biomass and but has its own characteristics, for example, high COD concentration, high alkalinity and high organic content. Untreated direct emissions can cause serious environmental pollution. Generally, the conventional alkali recovery boiler is used for treatment of wood pulp black liquor, but the effect is not ideal for treating straw pulp black liquor, this is caused by black liquor’s characteristics of high viscosity,high silicon content and low calorific value. Therefore a new recycling technology is needed to develop for treating straw pulp black liquor, a fluidized bed pyrolysis treatment technology of straw pulp black liquor for alkali recovery is proposed in this paper. The reed pulp black liquor is selected as raw material, The kinetic parameters of pyrolysis reaction of the reed pulp black liquor are calculated, its mechanism of reaction kinetics are studied. The pyrolysis experiment of reed pulping black liquor was carried out in a small fluidized bed and the mechanism of its pyrolysis was obtained. It provides the theoretical basis for the application of the technology of the recovery of the pyrolysis of the fluidized bed.First, according to the 3 temperature interval of reed pulp black liquor pyrolysis and the known TG and DTG curves of reed pulp black liquor, The kinetic parameters of pyrolysis reaction were solved by using Coats-Redfern, Flynn-Wall-Ozawa, Friedman,and Kissinger method which were in common use in reaction kinetics calculation. The results showed that the reaction mechanism of reed pulping black liquor by Coats-Redfern method was random nucleation and subsequent growth. The error caused by the choice of the reaction mechanism was avoided by Flynn-Wall-Ozawa and Friedman method and the accuracy of the results was higher. The Kissinger method could only analyze the data points of the peak points, and there were large deviations in some results for Kissinger method.Secondly, the calcium based zeolite was selected as the bed material and the nitrogen was selected as the fluidization medium, the temperatures of the experiment were selected by 530, 580, 630, 680, 730 and 780℃, the pyrolysis process of reed pulpblack liquor in a small fluidized bed was carried out, and the gas phase, liquid phase and solid phase products were obtained. The test results of these products were obtained by means of the corresponding detection method. These researches showed that the higher pyrolysis temperatures were suitable for the pyrolysis process, the specific performances were that the pyrolysis gases were obtained, and the combustible gases could account for a large proportion of the pyrolysis gases, the formation of tar was suppressed, the volatile content of the residual in the semi coke of the black liquor could be reduced, the conversions of carbon and hydrogen were increased, and the losses of carbon and hydrogen were reduced. The pyrolysis temperature had a significant impact on the variation of the components of each phase of product. For gas products pyrolysis, with increase of the pyrolysis temperature, the volume concentration of H2 and CO gradually increased the volume concentration of CH4 gradually reduced, the volume concentration of CO2 were declining. For tar which was liquid phase product, the yield was decreased with the increase of pyrolysis temperature, the relative contents of polycyclic aromatic hydrocarbons were more at high temperature. For solid phase product, the high calorific value of the semi coke decreased with the increase of the pyrolysis temperature. The micro morphology of the semi coke was greatly influenced by the pyrolysis temperature.Analysed comprehensively, the most ideal pyrolysis temperature was 780℃.更多还原