自吸式文丘里水洗器过滤性能研究

发布时间：2018-11-15 22:53

【摘要】：核电厂安全壳是防止放射性产物释放到环境的最后一道屏障,在发生类似堆芯熔穿压力容器的严重事故时,一回路高温高压的冷却剂释放到安全壳内,造成安全壳内压力持续升高,当压力超过安全限值时可能会威胁到安全壳的完整性。安全壳过滤排放系统采用主动卸压的方式确保安全壳的完整性,同时通过系统的过滤部件去除排放气体中的放射性物质。本文以过滤排放系统的湿式过滤环节为研究背景,对自吸式文丘里水洗器的引射机理和水洗器去除气溶胶、碘及甲基碘的性能进行了实验研究和理论分析,其中实验部分主要是在冷态条件下进行的,完成的主要研究工作如下:1、研究了自吸式文丘里水洗器喉管段(整体式)和喷嘴出口(分体式)截面上的静压分布规律,以及压力分布特性对引射量的影响。结果表明:整体式文丘里水洗器喉管径向上的静压梯度显著,并且在不同流速范围内,径向上的压力差异随流速表现出明显的区域效应,引射量与吸液口处静压的变化规律反向一致。分体式文丘里水洗器的喷嘴出口截面上,静压同样存在显著的径向分布梯度,而液体通道内的压力与喷嘴壁面处的压力分布密切相关,特别是在引射液体的情况下,由于气-液间的相互作用使得液体通道内的压力产生额外增量,从而造成引射液体的有效吸液压差受到限制。通过进一步的理论分析和实验研究,获取了操作参数和结构参数对引射性能的影响规律,并最终得到了改善引射量的有效方法。2、对自吸式文丘里水洗器的除尘和除气特性进行了实验研究和理论分析。结果发现,文丘里水洗器对气溶胶的过滤性能与气溶胶粒径、水洗器结构以及两相流动参数密切相关,过滤效率主要受限于对小粒径气溶胶的去除能力,为了改善水洗器的除尘效率,研究中对水洗器的结构和操作参数进行优化,得到了满足效率要求的设计方案。文丘里水洗器对碘单质具有出色的过滤性能,在引射量充足情况下对结构参数和操作参数的变化不敏感。相反,文丘里水洗器对甲基碘气体的过滤性能较差,并且改变结构参数和操作参数对效率的改善作用不大。3、基于亨利定律和质量守恒原理,通过实验测量了不同温度和压力下的甲基碘气体溶解度系数,拟合得到了溶解度系数在不同参数下的统一计算式。借助溶解度系数的测量结果,在溶解饱和的假设前提下,对文丘里水洗器和出口淹没段内溶液的甲基碘最大吸收能力进行计算,以此确定效率改进的主要方向。4、以文丘里水洗器出口淹没段内溶液的除气过程为研究背景,对鼓泡层内甲基碘气体的吸收规律进行了研究。实验中通过对气体吸收的非平衡态特征分析,研究了传质速率和化学反应速率对平衡态效率的影响,通过过程分析确定不同工况下限制吸收效率的主要因素,并验证了限制因素改进后对效率的影响。实验中还系统的研究了溶液温度、系统压力、气相流量、溶液液位以及入口甲基碘气体浓度等参数对稳态吸收效率的影响规律。
[Abstract]:The containment of the nuclear power plant is the last barrier to prevent the release of the radioactive product to the environment. In the event of a severe accident similar to the core penetration of the pressure vessel, a high temperature and high temperature of the coolant is released into the containment and the pressure in the containment continues to rise, The integrity of the containment may be compromised when the pressure exceeds the safety limit. The containment filtration and drainage system ensures the integrity of the containment by means of active pressure relief, while removing the radioactive material from the exhaust gas through the filter components of the system. In this paper, the performance of the self-suction venturi scrubber and the removal of aerosol, iodine and methyl iodide from the suction mechanism and the water scrubber of the self-suction venturi scrubber are studied and the theoretical analysis is carried out in this paper. The experimental part is mainly carried out under the condition of cold state. The main research work is as follows: 1. The static pressure distribution in the section of the throat section (integral) and the nozzle outlet (split) of the self-suction type Venturi water washer and the effect of the pressure distribution on the injection quantity are studied. The results show that the static pressure gradient in the radial direction of the integral venturi scrubber is significant, and the pressure difference in the radial direction shows a significant regional effect with the flow velocity in the range of different flow velocity. the static pressure also has a significant radial distribution gradient on the outlet cross-section of the nozzle of the split-type venturi water washer, and the pressure in the liquid channel is closely related to the pressure distribution at the wall of the nozzle, As a result of the interaction of the gas-liquid, the pressure in the liquid channel is increased in an additional increment, thereby limiting the effective suction pressure difference of the injection liquid. By means of further theoretical analysis and experimental study, the influence of operating parameters and structural parameters on the ejection performance is obtained, and an effective method to improve the injection quantity is finally obtained. The experimental and theoretical analysis of the dust removal and the degas characteristics of the self-suction type Venturi water washer are carried out. The results show that the filter performance of the Venturi scrubber is closely related to the aerosol particle size, the structure of the water scrubber and the two-phase flow parameters, and the filtration efficiency is mainly limited to the removal ability of the small particle size aerosol. In order to improve the dust removal efficiency of the water washer, The structure and operating parameters of the water scrubber were optimized in the study, and the design scheme to meet the efficiency requirement was obtained. The Venturi water washer has excellent filtering performance on the iodine simple substance, and is insensitive to the change of the structural parameters and the operating parameters in the case of sufficient injection quantity. in contrast, the filtering performance of the methyl iodide gas by the Venturi water washing device is poor, and the effect of changing the structural parameters and the operating parameters on the efficiency is not great; and 3, the solubility coefficient of the methyl iodide under different temperatures and pressures is measured by experiments based on the Henry's law and the mass conservation principle, and the uniform calculation formula of the solubility coefficient under different parameters is obtained. By means of the measurement of the solubility coefficient, the maximum absorption capacity of the methyl iodide in the solution in the venturi scrubber and the outlet inundated section is calculated on the assumption that the saturation is dissolved, thereby determining the main direction of the efficiency improvement. The absorption law of the methyl iodide gas in the bubble layer was studied in the background of the gas removal process of the solution in the outlet of the venturi scrubber. The influence of mass transfer rate and chemical reaction rate on the equilibrium efficiency is studied by the non-equilibrium characteristic analysis of gas absorption, and the main factors limiting the absorption efficiency under different working conditions are determined through the process analysis, and the effect of the limiting factor on the efficiency is also verified. The influence of the parameters of solution temperature, system pressure, gas phase flow, solution liquid level and inlet methyl iodide gas concentration on the steady-state absorption efficiency was also studied in the experiment.
【学位授予单位】：哈尔滨工程大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TL364.3

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