低温湿烟气溶液除湿技术试验研究

发布时间：2018-01-31 20:02

本文关键词： 湿烟气除湿降膜 CaCl_2溶液水回收　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：燃煤机组湿法脱硫后排放的湿烟气中含有大量水蒸气,烟气中水分携带量约为80g/kg干烟气,是电厂水资源消耗的重要组成部分,同时以潜热的形式排放大量低温余热,且引起烟囱腐蚀、"白烟"、烟囱雨等一系列问题。随着节水降耗工作的逐步深入,烟气除湿技术的研究得到了越来越多的关注。溶液除湿技术基于除湿溶液与湿烟气中水蒸气分压力之差,推动水蒸气在气相与液相间的迁移,在湿烟气除湿领域具有较大的应用潜力。除湿剂的选择是影响系统性能和经济性的关键,结合湿烟气除湿的应用环境、各种除湿剂的性能、经济性等因素分析表明,成本低廉的CaCl2溶液是一种良好的湿烟气除湿用除湿剂。本文首先通过数值模拟的方法,初步研究了 CaCl2溶液用于烟气除湿的性能特点。建立了绝热型逆流管式降膜除湿过程的控制方程,采用有限差分法,通过数值计算的方法,研究了管式降膜除湿器内的吸收热质过程,探究了溶液温度、浓度、雷诺数、传质面积及烟气温度对除湿性能的影响,并分析了液侧与气侧的变化规律。计算表明:基于CaCl2溶液的烟气除湿工艺可行,除湿效率超过50%,能够适应脱硫后烟气参数下的除湿需求。除湿过程中,溶液温度上升是除湿性能下降的主要因素,主要气液传质阻力在气侧,数值模拟为进一步的试验研究提供了参考。其次,设计、搭建了绝热型管式内降膜除湿试验台,试验研究了 CaCl2溶液的除湿特性,探究了溶液浓度、温度、传质面积、进口烟气温度等因素对除湿性能的影响,并与相同状态下的清水冷凝除湿进行了对比。试验结果表明:CaCl2溶液除湿效率能够满足湿烟气除湿需求,最大除湿效率可达70%;各因素对除湿性能的影响与模拟结果趋势一致;溶液浓度和溶液温度是影响除湿效率的关键因素,除湿溶液浓度不宜超过45%,在满足工程系统经济性且保证溶液不结晶的条件下,应尽量降低溶液温度,以提高除湿效率;相对于清水冷凝除湿效率为16.9%-33.9%的工况下,溶液除湿效率达到40%～55%,且烟气出口相对湿度约60%,在回收水分的同时为解决湿烟气凝结造成烟囱腐蚀提供了可能。数据分析得到,试验工况下传质系数介于0.009m/s～0.040m/s之间,除湿效率的实验关联式为η= 467.24Tain0.4805Xin0.841Tsolin-1.843ζlg0.071A0.432,上述结果为该工艺进一步中试研究和应用提供了参考。
[Abstract]:The wet flue gas emitted from coal-fired units after wet desulfurization contains a large amount of water vapor, and the moisture carrying capacity in the flue gas is about 80g / kg dry flue gas, which is an important part of water resources consumption in power plants. At the same time, a large amount of low temperature waste heat is discharged in the form of latent heat, which causes a series of problems such as chimney corrosion, "white smoke", chimney rain and so on. More and more attention has been paid to the research of flue gas dehumidification technology. Solution dehumidification technology is based on the difference of water vapor partial pressure between dehumidification solution and wet flue gas, which promotes the migration of water vapor between gas phase and liquid phase. The selection of dehumidifier is the key to affect the performance and economy of the system. Combined with the application environment of wet flue gas dehumidification, the performance of various dehumidifiers. Economic analysis shows that the low-cost CaCl2 solution is a good dehumidifier for wet flue gas dehumidification. The performance characteristics of CaCl2 solution used in flue gas dehumidification were studied preliminarily. The governing equation of adiabatic countercurrent tube falling film dehumidification process was established. The finite difference method was adopted and the numerical calculation method was used. The absorption process of heat and mass in the tube dehumidifier was studied. The effects of solution temperature, concentration, Reynolds number, mass transfer area and flue gas temperature on the dehumidification performance were investigated. The results show that the dehumidification process based on CaCl2 solution is feasible and the dehumidification efficiency is more than 50%. In the process of dehumidification, the increase of solution temperature is the main factor to decrease the dehumidification performance, and the main gas-liquid mass transfer resistance is on the gas side. Numerical simulation provides a reference for further experimental research. Secondly, the adiabatic tube internal falling film dehumidification test rig is designed and built. The dehumidification characteristics of CaCl2 solution are experimentally studied and the solution concentration is investigated. The influence of temperature, mass transfer area and inlet flue gas temperature on the dehumidification performance. The experimental results show that the dehumidification efficiency of the solution of 1% CaCl 2 can meet the demand of dehumidification of wet flue gas, and the maximum dehumidification efficiency can reach 70%. The influence of various factors on the dehumidification performance is consistent with the trend of simulation results. Solution concentration and solution temperature are the key factors affecting the dehumidification efficiency. The concentration of dehumidified solution should not exceed 455.The solution temperature should be reduced as far as possible under the condition of satisfying the economy of the engineering system and ensuring the solution not crystallizing. To improve dehumidification efficiency; Under the condition that the dehumidification efficiency of water is 16.9- 33.9%, the solution dehumidification efficiency reaches 40% and 55%, and the relative humidity of flue gas outlet is about 60%. It is possible to recover moisture and solve the corrosion of chimney caused by wet flue gas condensation. According to the data analysis, the mass transfer coefficient is between 0.009 m / s and 0.040 m / s under the test condition. The experimental correlation of dehumidification efficiency is 畏 = 467.24 Tain0.4805 Xin0.841 Tsolin-1.843 味 lg0.071A0.432. These results provide a reference for further pilot study and application of this process.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X773

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