大型多反应室煤矿乏风预热催化氧化器的工作过程仿真

发布时间：2018-03-02 18:08

  本文选题：预热催化氧化器　切入点：甲烷　出处：《山东理工大学》2013年硕士论文　论文类型：学位论文

【摘要】：中国是煤炭能源大国,每年通过煤矿乏风排入大气的甲烷既造成了清洁能源的巨大浪费,又污染了大气环境。由于乏风瓦斯中甲烷含量低、浓度波动范围广且排风量大等特点,风排瓦斯的治理利用一直是个大难题。预热催化氧化反应器是山东理工大学自主研发的一种处理乏风瓦斯的催化氧化装置,它不仅具有结构紧凑、占地面积小、机械强度高等优点,而且利用反应后的废气预热新鲜进气进行能量回收,减少了能耗,提高了热利用率和催化氧化床进气温度、省去加热装置,具有节能和环保的双重意义。 本文研究了扩张段的导流分配方案,对装置运行参数、氧化床结构参数和陶瓷参数的变化对流场的影响规律进行了试验研究和数值模拟计算,主要研究内容包括： (1)建造处理量为1000m3/h的预热催化氧化反应器试验台及数值计算模型,研究冷态流场下反应室入口截面处气流速度分布的均匀性。模拟结果显示出与实验结果一致的速度分布规律,都表现为中间速度高,周围速度偏低的一种态势,且氧化床顶部及底部很大一部分处于低速度区,速度分布极不均匀。 (2)对预热催化氧化反应器反应室入口的导流分配系统进行数值模拟计算,确定了扩张段的最佳导流分配方案。未加导流板时的原模型反应室氧化床入口截面的速度分布不均匀性系数为0.8左右；布置水平导流板之后纵向速度分布有一定改善,不均匀性系数降低到0.5左右；增加垂直导流板后速度分布的均匀性明显提高,不均匀性系数降低到0.2左右。 (3)分析冷态流场下氧化床参数的变化对速度分布均匀性的影响,催化床层前端布置均温均流床层可以显著改善催化床入口截面的速度分布均匀性；均温均流床层与催化床层间距为10mm左右时,对速度分布均匀性改善最佳；氧化床长度和孔隙率的变化对其影响不是很大；在装置结构尺寸一定的条件下,氧化床横截面边长在550mm和600mm之间时速度均匀性较好。 (4)运行参数、陶瓷参数及催化剂参数对流场的影响：气流速度增大将会缩短甲烷分子在壁面的驻留时间,导致温升缓慢,降低甲烷转化率；适当提高入口温度和甲烷浓度有利于反应初期吸附基元反应的发生,对壁面催化反应具有促进作用；在其它条件不变的情况下,增大陶瓷床的比表面积可以增加甲烷分子与活性微粒触碰的频率,加快某些关键基元反应的速率；适当增加催化剂涂覆量可以增加活性位数目,有利于催化反应的进行。 (5)导流板对热态流场的影响：在反应室扩张段安装导流板后,氧化床入口截面的速度分布不均匀系数从0.5降低到0.18左右；氧化床中部横截面上的温度场不均匀系数几乎为零,温度梯度非常小,陶瓷氧化床运行的安全性大大提高；同一横截面的甲烷浓度不均匀系数降低,床体底部甲烷浓度波动比较大的现象明显改善,整体气流完全反应的时间和距离缩短,这样可以根据风量处理要求适当缩减床体长度,节约装置成本。
[Abstract]:Chinese coal energy power, each year through the coal mine ventilation air methane into the atmosphere has caused a huge waste of clean energy, and pollution of the atmospheric environment. The methane content of VAM in low concentration fluctuation range and characteristics of large volume discharge, exhaust gas treatment and preheating has been a big problem. Catalytic oxidation catalytic oxidation reactor is a device for processing developed by Shandong University of Technology, VAM, it not only has the advantages of compact structure, small occupied area, high mechanical strength and so on, and the reaction of the waste gas preheating intake of fresh energy recovery, reduce energy consumption, improve the rate of catalytic oxidation bed and inlet temperature heat utilization. Save the heating device, which has dual significance of energy saving and environmental protection.
In this paper, the diversion diversion plan of expansion section is studied. The influence of operation parameters of the plant, the structural parameters of the oxidation bed and the change of ceramic parameters on the flow field is studied by numerical simulation and experiment.
(1) the construction of the processing capacity of preheating 1000m3/h catalytic oxidation reactor test and numerical calculation model of cold state flow field under the reaction chamber entrance section of air velocity distribution. The simulation results show good agreement with experimental results showed the velocity distribution in high speed, a situation around the speed the low, and the oxidation bed top and bottom of a large part in the low speed region, the velocity distribution is very uneven.
(2) the distribution system of diversion entrance reaction preheating catalytic oxidation reactor chamber by numerical simulation, the optimum flow distribution scheme expansion section. The original model of the reaction chamber entrance section of the oxidation bed without deflectors of the velocity distribution uniformity coefficient was about 0.8; after the layout of horizontal guide plate longitudinal velocity distribution there is some improvement, the non-uniformity coefficient is reduced to about 0.5; increase the speed distribution of the vertical guide plate after uniformity was obviously improved, the non-uniformity coefficient is reduced to about 0.2.
(3)鍒嗘瀽鍐锋，

本文编号：1557603