基于热冲击条件下纤维材料形变对滤料性能影响的研究

发布时间：2018-05-11 04:41

本文选题：袋式除尘 + “尘”类热冲击　；参考：《东华大学》2017年博士论文

【摘要】：本研究工作的背景为大多数工业废气处理过程中都存在烟气温度突然升高的短时高温运行工况,滤料在热冲击作用下发生形变并导致滤料性能改变。研究的目标是分析得到热冲击作用下滤料过滤阻力和过滤效率的变化规律和变化原因,找到判定热冲击作用对滤料性能影响的方法,进而指导袋式除尘器受到热冲击作用后的处理方式。研究过程从热冲击作用如何影响滤料性能的角度,深入分析了纤维材料形变影响滤料性能,主要包含4个方面。(1)从热冲击形成的角度分析了烟和尘对滤料产生的热冲击作用。研究过程采用热传递理论,根据污染源种类,分析不同热冲击过程中对滤料性能产生的影响,将热冲击作用分为“尘”、“尘+气”和“气”三大类;并分别研究这三类作用下,热冲击过程中烟气和烟尘热作用对滤料的影响。结果表明:袋式除尘系统中对滤料的影响最大为“尘”类热冲击作用。烟气热冲击作用表现为直接作用整体滤料,烟气温度变化直接作用并影响了滤料性能。烟尘热冲击作用主要表现为与滤料接触性作用,颗粒物粒径越大产生的热温差越大,对滤料的破坏性越强且持续时间也越长;同时,推导出降低“尘”类热冲击影响所需时间的工程计算方法。(2)从纤维特性的角度分析了纤维细度、热冲击温度、热冲击时间三个因子对纤维断裂强力的影响。研究过程首先对3种常用纤维进行热重分析,明确烟气温度对纤维本体性能产生的可逆和不可逆影响规律;其次,采用试验方法分析了热冲击作用下3类10种常用滤料用纤维断裂强力的变化,数据处理采用无因次法将不同纤维细度的断裂强力值统一在同一个水平上,再通过显著性因子分析方法初步分析滤料用纤维在热冲击下的影响方式。通过对试验结果分析,归纳得到了热冲击作用对滤料用纤维强力的影响模型。(3)从滤料材料特性的微观结构变化角度探讨了热冲击对滤料强力性能影响的方式。采用试验方法,模拟滤料在实际工况下的热冲击循环作用,研究了预加张力、热冲击循环以及预加张力下热冲击循环这3种条件对滤料材料力学性能的影响规律,并采用扫描电子显微镜(sem)、x射线衍射(xrd)和动态机械力学分析(dma)等表征手段深入分析了热冲击作用对滤料强力性能影响的机理。结果表明:热冲击作用对滤料拉伸断裂强力的影响为先增后降,这种规律产生的机理是热冲击作用导致了滤料纤维的微结构发生变化,即结晶度提高、玻璃化转变温度(tg)升高和储能模量(e’)增加。(4)从过滤性能的角度分析了热冲击作用后纤维参数改变对滤料性能的影响。采用数值模拟方法,首先分析了相同克重条件下纤维细度变化对过滤阻力和过滤效率的影响规律;再从纤维滤料的收缩的角度分析了热冲击作用对过滤性能的影响规律,并利用试验方法进行了验证。结果表明:相同克重的条件下,纤维细度的减小能明显提高对细颗粒物的捕集效率,但同时增加了过滤阻力,得到了单位阻力的捕集效率提升率随纤维细度的变化规律;同时,分析得到了热冲击作用下纤维收缩、垂直气流方向间距变化和平行气流方向间距变化对不同粒径颗粒物捕集的显著影响因子及其影响规律,表明纤维细度的减小有利于保持滤料在热冲击作用下过滤阻力和过滤效率的稳定性。
[Abstract]:The background of this study is that in the process of most industrial waste gas treatment, there is a short-time high temperature operating condition that the flue gas temperature rises suddenly. The filter material is deformed under the effect of thermal shock and causes the change of filter performance. The aim of the study is to analyze the change of filter resistance and filtration efficiency under the effect of thermal shock. The method of determining the effect of thermal shock on the performance of filter material is found, and then the treatment mode of the bag type dust collector after thermal shock is guided. From the angle of how the heat shock affects the performance of the filter material, the effect of the fiber material deformation on the filter material is analyzed in 4 aspects. (1) from the angle of thermal shock formation The effect of smoke and dust on the heat shock produced by the filter material is analyzed. The heat transfer theory is used to analyze the effect of the filter material on the performance of the filter material in different thermal shock processes. The thermal shock is divided into three categories, "dust", "dust + gas" and "gas". The effect of the smoke heat on the filter material shows that the maximum effect of the bag type dust removal system on the filter material is the "dust" type of thermal shock. The thermal shock effect of the flue gas is directly acting as a whole filter material, the change of the temperature of the flue gas is directly acting on the filter material and affects the performance of the filter material. The heat shock of the smoke and dust is mainly represented by the contact effect with the filter material. The greater the heat temperature difference produced by the larger particle size, the stronger the damage to the filter material and the longer the duration. At the same time, the engineering calculation method for reducing the time needed to reduce the impact of the "dust" heat shock is derived. (2) from the angle of fiber characteristics, the fiber fineness, thermal shock temperature, and heat shock time are analyzed by three factors to the fiber breaking strength. The process of thermogravimetric analysis of 3 kinds of common fibers was first made to clarify the reversible and irreversible law of the effect of flue gas temperature on the properties of fiber. Secondly, the change of fiber breaking strength of 3 kinds of 10 kinds of common filter materials under thermal shock was analyzed by the experimental method. The strength of fracture strength is unified at the same level, and then the influence mode of fiber under thermal shock is preliminarily analyzed by the method of significant factor analysis. Through the analysis of the test results, the effect of thermal shock on the fiber strength of the filter material is concluded. (3) the heat is discussed from the angle of microstructure change of the material properties of the filter material. The influence of impact on the strength of the filter material is used to simulate the effect of the heat shock cycle on the filter material under the actual working conditions, and the influence of the 3 conditions on the mechanical properties of the material, including the preloading tension, the thermal shock cycle and the heat shock cycle under the pretension, is studied, and the scanning electron microscope (SEM), X ray diffraction (XRD) is used. The mechanism of the influence of thermal shock to the strength of the filter material is analyzed by the means of dynamic mechanical mechanical analysis (DMA) and other characterization means. The result shows that the effect of thermal shock to the tensile strength of the filter is increased first and then descends, and the mechanism is that the thermal shock leads to the change of the microstructure of the filter fiber, that is, the crystallinity. The increase of glass transition temperature (TG) and energy storage modulus (E ') increase. (4) from the angle of filtration performance, the effect of fiber parameters on the performance of the filter material was analyzed. The influence of fiber fineness on the filtration resistance and filtration efficiency under the same weight condition was analyzed by numerical simulation. The effect of the thermal impact on the filtration performance is analyzed and the test method is used to verify the effect of the thermal impact on the filtration performance. The results show that the decrease of the fineness of the fiber can obviously improve the capture efficiency of the fine particles, but the filtration resistance is increased at the same time, and the capture efficiency of the unit resistance is improved. At the same time, the significant influence factors and influence laws of fiber shrinkage, vertical air flow direction distance and parallel airflow direction distance on the collection of particles with different particle sizes are obtained. The results show that the decrease of fiber fineness is beneficial to the filtration resistance of the filter material under the effect of thermal shock. Stability of force and filtration efficiency.

【学位授予单位】：东华大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ340.1;TS176.5

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