改性造纸白泥循环捕集二氧化碳的性能研究
发布时间：2018-09-15 07:19
【摘要】：过度排放二氧化碳(CO2)是全球变暖的主要原因,氧化钙(CaO)价廉易得,是最易工业化应用的二氧化碳吸附剂。由于工厂尾气的温度较高,高温吸附分离可以提高热能利用率,因此本课题选用高温钙基吸附剂—CaO循环吸附分离的方法捕集尾气中的CO2。我国产纸量占世界总量的一半(年均超过50万吨),造纸工业碱回收过程中得到的造纸白泥是一种有毒的工业废弃物,每生产1吨纸浆就会得到0.5吨造纸白泥,因此亟需一种处理方法来减少造纸白泥给环境带来的负担。造纸白泥的主要成分为CaC03,本研究则结合白泥的自身性质制备钙基C02吸附剂,并将研究分为以下四个部分：将造纸白泥与铝土矿尾矿(或九水合硝酸铝)直接掺杂,通过转化率考察掺杂剂的含量、预煅烧温度和预煅烧时间对吸附剂循环性能的影响,得出最佳循环性能吸附剂的制备条件。由于造纸白泥中的杂质会影响循环吸附量和稳定性,因此,使用蔗糖法提纯改性造纸白泥。通过单因素法筛选出蔗糖溶液的最佳提取条件,并对最佳提取条件下得到的改性白泥进行掺杂,考察预煅烧温度、预煅烧时间和掺杂剂对改性白泥循环性能的影响,得出最佳循环性能吸附剂的制备条件。从上述实验中筛选出循环性能及经济效益兼优的改性吸附剂GLM-BTs-10-4-800,考察在不同碳酸化温度和CO2浓度下对循环性能的影响。由于工业生产的连续性,本研究考察了吸附剂的长周期循环。运用常见的动力学模型(机理模型、颗粒模型)对GLM-BTs一10-4-800动力学进行分段考察,并根据模拟结果确定吸附过程的反应机理。根据研究可知,LM-BTs-5-4-800循环15次后的碳酸化率为25.4%,较白泥原样高出了19.1%；LM-A1N-15-5-800循环15次后转化率为43.5%,较白泥原样高出了37.2%；GLM-BTs-10-4-800循环15次后的转化率为38.8%,较白泥原样高出了32.5%。通过对不同CO2浓度的考察可知,在热重分析仪中切换气氛会使转化率突增,加重吸附剂的烧结,而当CO2浓度较低时该现象减弱。GLM-BTs-1O-4-800表现出较好的稳定性与最低的失活率(30个循环仅降低了14.3%)。最后,根据碳酸化模拟结果可知,GLM-BTs-10-4-800的吸附动力学分为三个阶段进行：纯化学反应阶段、化学反应与扩散共同作用阶段和纯扩散阶段。
[Abstract]:Excessive emission of carbon dioxide (CO2) is the main cause of global warming. Calcium oxide (CaO) is the most easily applied carbon dioxide adsorbent. Due to the high temperature of plant tail gas, high temperature adsorption and separation can improve the utilization of heat energy. Therefore, the high temperature calcium based adsorbent -CaO cycle adsorption separation method is used to capture CO2. in tail gas. The volume of paper produced in China accounts for half of the world's total (more than 500000 tons a year). The white mud obtained from the alkali recovery process in the papermaking industry is a toxic industrial waste, and 0.5 tons of white mud is obtained for every ton of pulp produced. Therefore, there is an urgent need for a treatment method to reduce the burden of white mud on the environment. The main component of white mud in paper making is CaC03,. In this study, calcium based C02 adsorbent was prepared by combining the properties of white mud, and the study was divided into four parts: direct doping of white mud and bauxite tailings (or aluminum nitrate nine-hydrate). The effects of the content of dopant, the pre-calcination temperature and the pre-calcination time on the cyclic properties of the adsorbent were investigated, and the optimum conditions for the preparation of the adsorbent were obtained. Because the impurity in the white mud of papermaking will affect the amount and stability of circulating adsorption, the modified white mud is purified by sucrose method. The optimum extraction conditions of sucrose solution were screened by single factor method, and the modified white mud was doped under the optimum extraction conditions. The effects of pre-calcination temperature, pre-calcination time and dopant on the cyclic properties of modified white mud were investigated. The optimum conditions for the preparation of the adsorbent were obtained. The effects of the modified adsorbent GLM-BTs-10-4-800, at different carbonation temperature and CO2 concentration on the cycling performance were selected from the above experiments. Due to the continuity of industrial production, the long-period cycle of adsorbent was investigated. The kinetics of GLM-BTs -10-4-800 was investigated by using common kinetic models (mechanism model, particle model), and the reaction mechanism of adsorption process was determined according to the simulation results. According to the study, the carbonation rate of LM-BTs-5-4-800 was 25.4 after 15 cycles, which was higher than that of white mud. The conversion rate was 43.5 after 15 cycles of LM-A1N-15-5-800 and 38.2% of GLM-BTs-10-4-800 than that of white mud, 32.5% higher than that of white mud. Through the investigation of different CO2 concentration, it can be seen that switching atmosphere in thermogravimetric analyzer will increase the conversion rate and increase the sintering of adsorbent. When the concentration of CO2 was low, the phenomenon was weakened. GLM-BTs-1O-4-800 showed better stability and lowest inactivation rate (30 cycles decreased only 14.3%). Finally, according to the carbonation simulation results, the adsorption kinetics of GLM-BTs-10-4-800 can be divided into three stages: pure chemical reaction stage, chemical reaction and diffusion phase and pure diffusion stage.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X701;TQ424
[Abstract]:Excessive emission of carbon dioxide (CO2) is the main cause of global warming. Calcium oxide (CaO) is the most easily applied carbon dioxide adsorbent. Due to the high temperature of plant tail gas, high temperature adsorption and separation can improve the utilization of heat energy. Therefore, the high temperature calcium based adsorbent -CaO cycle adsorption separation method is used to capture CO2. in tail gas. The volume of paper produced in China accounts for half of the world's total (more than 500000 tons a year). The white mud obtained from the alkali recovery process in the papermaking industry is a toxic industrial waste, and 0.5 tons of white mud is obtained for every ton of pulp produced. Therefore, there is an urgent need for a treatment method to reduce the burden of white mud on the environment. The main component of white mud in paper making is CaC03,. In this study, calcium based C02 adsorbent was prepared by combining the properties of white mud, and the study was divided into four parts: direct doping of white mud and bauxite tailings (or aluminum nitrate nine-hydrate). The effects of the content of dopant, the pre-calcination temperature and the pre-calcination time on the cyclic properties of the adsorbent were investigated, and the optimum conditions for the preparation of the adsorbent were obtained. Because the impurity in the white mud of papermaking will affect the amount and stability of circulating adsorption, the modified white mud is purified by sucrose method. The optimum extraction conditions of sucrose solution were screened by single factor method, and the modified white mud was doped under the optimum extraction conditions. The effects of pre-calcination temperature, pre-calcination time and dopant on the cyclic properties of modified white mud were investigated. The optimum conditions for the preparation of the adsorbent were obtained. The effects of the modified adsorbent GLM-BTs-10-4-800, at different carbonation temperature and CO2 concentration on the cycling performance were selected from the above experiments. Due to the continuity of industrial production, the long-period cycle of adsorbent was investigated. The kinetics of GLM-BTs -10-4-800 was investigated by using common kinetic models (mechanism model, particle model), and the reaction mechanism of adsorption process was determined according to the simulation results. According to the study, the carbonation rate of LM-BTs-5-4-800 was 25.4 after 15 cycles, which was higher than that of white mud. The conversion rate was 43.5 after 15 cycles of LM-A1N-15-5-800 and 38.2% of GLM-BTs-10-4-800 than that of white mud, 32.5% higher than that of white mud. Through the investigation of different CO2 concentration, it can be seen that switching atmosphere in thermogravimetric analyzer will increase the conversion rate and increase the sintering of adsorbent. When the concentration of CO2 was low, the phenomenon was weakened. GLM-BTs-1O-4-800 showed better stability and lowest inactivation rate (30 cycles decreased only 14.3%). Finally, according to the carbonation simulation results, the adsorption kinetics of GLM-BTs-10-4-800 can be divided into three stages: pure chemical reaction stage, chemical reaction and diffusion phase and pure diffusion stage.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X701;TQ424
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