大型焦炉拦焦炉口烟尘扩散分析及集气罩结构优化

发布时间：2018-10-12 16:30

【摘要】：炉口烟尘是焦炉拦焦过程中的主要污染源,集气罩是炉口除尘系统的核心部件,目前焦炉炉口集气罩的设计研究主要是根据以往的工程经验,缺乏理论分析和模拟研究。为了减少焦炉烟尘污染,提高炉口除尘系统的集尘效率,本文以山东某焦化厂的捣固焦炉为例,对拦焦期间炉口烟尘扩散进行了理论分析和实验验证,并且对炉口除尘系统的前端集气罩结构参数进行了仿真分析和模拟研究。首先,对捣固焦炉拦焦工艺和拦焦过程中的除尘技术进行了分析,确定了炉口烟尘是目前拦焦过程中的主要污染源,然后对炉口除尘系统的主要设备部件:集气罩、矩形风管和引导风机进行了分析比较,并通过UG软件建立实体模型。通过对炉口烟尘颗粒物的采样分析,确定了烟气中主要元素和污染空气的化合物,并分析了烟气中所携带的颗粒粒径,确定了较小颗粒的扩散几乎完全随气流而运动。然后通过研究各种扩散理论,确定了以高斯扩散模型为基础进行研究,由于焦炉拦焦过程中炉口烟气的扩散属于近距离污染问题,而且污染源温度较高,因此将炉口烟气的扩散确定为高温浮射流。以点源浮力羽流为模型理论分析了烟气扩散中轴心线上的温度变化,并利用ThermaCAMS65红外热像仪对炉口烟气扩散过程进行了拍摄。根据扩散热像图轴心温度采样分析随着距离的变化情况,在采样的距离范围内,变化情况与理论分析基本拟合,从而验证了模型选用的正确,为下一步研究提供了理论支持。通过炉口烟气扩散的分析,在进入集气罩之前,热源是扩散的主要动力,而要使烟气进入集气罩内,罩内所形成的负压区域有着重要影响。利用fluent软件模拟集气罩内部流场,对模型进行了简化,选择了合适的湍流模型,对计算区域进行网格划分,并确定了合理的边界条件。分析了集气罩的结构参数,比较了矩形风管数量不同,开口面倾斜角度不同和矩形风管位置不同三种情况下,集气罩内部的负压区域变化,以及轴心线上各点的压力。分析结果表明,安置两个矩形风管,开口面倾斜角度在5°左右,或者将矩形风管安置在两侧时,集气罩内所形成的负压区域较好。由于环境空间有限,矩形风管安置在两侧不可取。通过对集气罩的气相流场分析,改进集气罩结构参数之后,利用fluent中的离散模型,对拦焦过程中炉口烟尘进行了气固两相模拟研究。并从现场地面除尘站和炉口附近的烟尘颗粒物进行了采样,分析了颗粒物的粒径大小和颗粒的表面形态,从而确定了模拟仿真颗粒物的参数设置。根据周围环境建立计算区域,按实际情况,以50μm、100μm、150μm和200μm为四种颗粒粒径代表炉口烟尘颗粒分布,进行了模拟仿真和比较分析。研究表明,较小颗粒随气相速度场运动性更好,在集气罩内运动时间较短,而较大颗粒更容易受重力影响而沉降,若进入集气罩内运动时间较长,容易堆积。
[Abstract]:Flue dust is the main source of pollution in coke oven coke arresting process, and the gas collecting hood is the core part of the flue dust removal system. At present, the design and research of gas collecting cover of coke oven mouth are mainly based on previous engineering experience, and lack of theoretical analysis and simulation research. In order to reduce the pollution of coke oven dust and improve the dust collection efficiency of the dust collection system at the mouth of the furnace, this paper takes the rammed coke oven of a coking plant in Shandong Province as an example, and carries out theoretical analysis and experimental verification of the smoke diffusion at the mouth during the coke arresting period. The structural parameters of the front-end collector hood of the flue dust removal system are simulated and analyzed. Firstly, this paper analyzes the coke arresting technology of ramming coke oven and the dust removal technology in the coke arresting process, and determines that the flue dust is the main pollution source in the coke arresting process at present. Then, the main equipment components of the dust removal system of the furnace mouth are the gas collecting hood. The rectangular duct and the guide fan are analyzed and compared, and the solid model is established by UG software. The main elements in flue gas and the compounds that pollute the air were determined by sampling and analyzing the particulate matter in the flue gas. The particle size of the smoke was analyzed and the diffusion of the smaller particles was almost completely moved with the air flow. Then, by studying various diffusion theories, it is determined that the study is based on Gao Si's diffusion model. Because the flue gas diffusion in coke oven is a problem of close range pollution, and the temperature of pollution source is high, Therefore, the flue gas diffusion at the furnace entrance is determined to be a high temperature floating jet. Based on the point source buoyancy plume theory, the temperature variation on the axis line in flue gas diffusion was analyzed, and the smoke diffusion process at the furnace entrance was photographed by using ThermaCAMS65 infrared thermal imaging system. According to the temperature sampling of the axial center of the diffusion thermal image, the variation is basically fitted to the theoretical analysis in the range of the sampling distance, which verifies the correct selection of the model and provides the theoretical support for the next research. Through the analysis of flue gas diffusion at the furnace entrance, the heat source is the main power of diffusion before entering the gas collecting hood, and the negative pressure region formed in the hood has an important influence to make the flue gas enter into the gas collecting hood. Using fluent software to simulate the inner flow field of the gas collecting hood, the model is simplified, the appropriate turbulence model is selected, the calculation area is meshed, and the reasonable boundary conditions are determined. The structural parameters of the collector hood are analyzed. The variation of the negative pressure region and the pressure at each point on the axis line are compared under three conditions: the number of the rectangular duct, the inclined angle of the opening surface and the position of the rectangular duct. The results show that when two rectangular air ducts are placed, the inclined angle of the opening surface is about 5 掳, or the rectangular duct is placed on both sides, the negative pressure region formed in the gas collecting hood is better. Due to the limited environmental space, rectangular duct placement on both sides is not desirable. By analyzing the gas phase flow field of the gas collecting hood and improving the structure parameters of the gas collecting hood, the gas-solid two-phase simulation of flue dust in the coke arresting process was carried out by using the discrete model in fluent. The particle size and surface morphology of the particles were analyzed by sampling the smoke particles near the ground dedusting station and the furnace mouth, and the parameters of the simulated particles were determined. According to the surrounding environment, the calculated area is established. According to the actual situation, four particle sizes of 50 渭 m ~ 100 渭 m ~ (100 渭 m) and 200 渭 m represent the distribution of smoke particles at the mouth of the furnace. The simulation and comparative analysis are carried out. The results show that the smaller particles have better mobility with the gas velocity field, and the movement time is shorter in the gas collecting hood, while the larger particles are more vulnerable to the influence of gravity, and if the moving time is longer, it is easy to pile up.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ520.5

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