焊接烟气水浴净化系统关键技术研究

发布时间：2018-06-23 11:02

本文选题：水浴法 + 气液两相流　；参考：《哈尔滨理工大学》2017年硕士论文

【摘要】：焊接烟气是造成焊接从业者健康损伤和周围环境污染的最主要原因,越来越得到人们的重视。在焊接烟气净化除尘领域,水浴法净化是全新的技术,具有效率高、无耗材、低能耗等优点。在水浴净化过程中,焊接烟气和水形成气液两相流。本文对焊接烟气在水中形成的气液两相流进行瞬时体分分析,并以此指导设计了合理的烟气气泡破碎器,将含有烟尘颗粒的大气团逐层破碎,消耗了烟气动能,增加了烟尘颗粒与水接触面积和时间,加以喷淋装置,最大限度提高烟尘粒子被水捕获的效率。首先,对比了现有烟气净化方法应用于焊接烟气除尘的局限性,论证水浴法除尘的可行性,分析了水浴系统的工作原理和组成。其次,由单相流理论入手,将单相流流动情形下的控制方程推广到气液两相流的流动情形,确立了水浴净化过程流动特性,对有限元分析焊接烟气水浴净化提供基础。在ICEM中进行二维网格划分并导入FLUENT软件,采用VOF模型进行瞬时体分分析。仿真结果表明,采用双层气泡破碎和喷淋除尘过程的水浴净化设计可以显著提高气液分界面面积和接触时间;烟气入射速度越小,液池液面越高,气液分界面和接触时间越大。再次,研究了焊接烟气产生机理,分析了符合焊接烟气扩散的湍流模型,利用DPM模型对焊接烟气扩散进行仿真。根据水浴净化和烟气扩散仿真结论,设计了新型的水浴净化系统,并利用此实验装置进行了焊接比对试验,为气体保护焊和手工电弧焊焊接水浴净化系统提供了理论支持和实验验证。最后,采用烟气测量仪进行焊接烟气水浴净化效率研究。对比焊接烟气水浴净化过程中气泡破碎器和喷淋除尘装置的有无对焊接烟尘除尘效率的影响;采用单因素分析法,对不同烟气入射速度和液池液面高度的烟气除尘效率进行实验研究。结果表明,含有气泡破碎器和喷淋除尘装置的水浴净化系统除尘效率高且烟气入射速度越低、液池液面越高除尘效率也越高。
[Abstract]:Welding smoke is the main cause of health damage and environmental pollution of welding workers, and has been paid more and more attention. In the field of welding flue gas purification and dust removal, water bath purification is a new technology with the advantages of high efficiency, no consumables and low energy consumption. In the process of water bath purification, gas-liquid two-phase flow is formed by welding flue gas and water. In this paper, the instantaneous volumetric analysis of gas-liquid two-phase flow formed by welding flue gas in water is carried out, and a reasonable flue gas bubble crusher is designed to break the atmospheric mass containing smoke particles layer by layer, thus consuming the kinetic energy of the flue gas. The contact area and time between soot particles and water were increased, and the spraying device was used to improve the efficiency of soot particles being captured by water to the maximum extent. Firstly, the limitations of the existing flue gas purification methods used in welding flue gas dust removal are compared, the feasibility of water bath dust removal is demonstrated, and the working principle and composition of the water bath system are analyzed. Secondly, starting with the single-phase flow theory, the governing equation in single-phase flow is extended to the gas-liquid two-phase flow, and the flow characteristics of water bath purification process are established, which provides the basis for finite element analysis of welding flue gas water bath purification. In ICEM, two-dimensional mesh division is carried out and fluent software is imported, and VOF model is used for instantaneous volumetric analysis. The simulation results show that the design of water bath purification with double-layer bubble breakage and spray dust removal process can significantly increase the interface area and contact time of gas-liquid fraction, and the lower the incident velocity of flue gas, the higher the liquid level of the liquid pool and the longer the gas-liquid separation interface and contact time. Thirdly, the mechanism of welding flue gas generation is studied, and the turbulent model of welding flue gas diffusion is analyzed, and the simulation of welding flue gas diffusion is carried out by using DPM model. According to the simulation results of water bath purification and flue gas diffusion, a new water bath purification system was designed, and the welding comparison test was carried out with this experimental device. It provides theoretical support and experimental verification for gas shielded welding and manual arc welding water bath purification system. Finally, the efficiency of welding flue gas water bath purification is studied by means of flue gas measuring instrument. Comparing the influence of bubble crusher and spray dust collector on the efficiency of welding dust removal in the process of welding flue gas water bath purification, the single factor analysis method is used. The dedusting efficiency of flue gas with different incidence velocity and liquid level was studied experimentally. The results show that the dust removal efficiency of water bath purification system with bubble crusher and spray dust removal device is high and the lower the incident velocity of flue gas is, the higher the dust removal efficiency of liquid level in liquid tank is.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X76

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