电站锅炉省煤器磨损分析与数值模拟
发布时间：2018-10-20 09:56
【摘要】：煤粉在炉膛内燃烧后,产生的烟气冲刷尾部受热面管道,烟气中夹带的飞灰颗粒撞击到管子壁面上,对管子造成磨损。磨损会导致管子强度降低,引发省煤器爆管。和其他受热面相比,省煤器布置在炉膛的尾部烟道下部,烟气温度较低,夹带的飞灰颗粒硬度较大,由于重力的作用,速度也比较快,由此造成省煤器的磨损量比过热器等要大很多。 造成省煤器磨损的因素众多,如颗粒的物理性质(成分、粒径、形状、硬度)、烟气速度等,省煤器的布置方式也会对磨损有影响。 本课题借用Fluent模拟软件,考虑到烟气和飞灰颗粒属于气固两相流,并结合模型适用范围,最终选择离散相模型来模拟,湍流模型则选择RNG k-ε模型,对省煤器部分管排进行数值模拟。重点研究省煤器弯管与炉墙之间烟气走廊的形成,以及顺列和错列管排不同的布置方式对于烟气、飞灰颗粒流场的影响,以此判断磨损的大小。 通过模拟,得到烟气走廊的形成及流场特点。烟气进入省煤器管排区域,因为弯管与炉墙之间缝隙的阻力系数比管子的阻力系数小,在缝隙处产生低压区,部分烟气流向发生改变,向缝隙处靠拢,因此形成“烟气走廊”。通过模拟发现,烟气走廊处的烟气、飞灰颗粒的速度一直增加,到了流场出口边界时,速度几乎是入口速度的2倍,同时,可以观察到走廊处的烟气平均速度大于直管段的烟气速度,在弯管处的烟气、飞灰颗粒速度较大,磨损速率增加,再加上弯管本身的结构特点,使得弯管成为需要重点防磨的区域。 在顺列管排和错列管排的流场分析中,：我们发现,顺列管排的最大磨损一般发生在第一排的位置,而错列管排则发生在中间管排,二者结构的不同造成易磨损部位发生改变。错列管排的磨损比顺列管排的磨损大。 本课题模拟内容基本符合事实,对于理论研究有所帮助,对电厂的实际运行可以提供指导性意见。
[Abstract]:After the pulverized coal is burned in the furnace, the flue gas scour the tail heating surface pipe, and the fly ash particles in the flue gas impinge on the wall of the pipe, which causes wear and tear to the pipe. Wear can cause tube strength to decrease, cause economizer to burst tube. Compared with other heating surfaces, the economizer is arranged in the lower part of the tail flue of the furnace, the flue gas temperature is lower, the hardness of the fly ash particles in the entrainment is larger, and the speed is faster because of the effect of gravity. As a result, economizer wear is much larger than the superheater. There are many factors that cause the wear of economizer, such as the physical properties of particle (composition, particle size, shape, hardness), smoke velocity and so on. The layout of economizer will also affect the wear. By using Fluent software, considering that the flue gas and fly ash particles belong to gas-solid two-phase flow, and combining with the applicable range of the model, the discrete phase model is chosen to simulate the turbulent model, and the RNG k- 蔚 model is chosen for the turbulence model. The numerical simulation of partial tube row of economizer is carried out. The formation of flue gas corridor between the bends of economizer and the furnace wall and the influence of different arrangement of line and staggered tubes on the flow field of flue gas and fly ash particles are studied in order to judge the size of wear and tear. Through simulation, the formation and flow field characteristics of flue gas corridor are obtained. The flue gas enters the economizer pipe discharge area, because the resistance coefficient of the gap between the bend pipe and the furnace wall is smaller than that of the tube, there is a low pressure area in the gap, and some flue gas flow direction changes and draws closer to the gap, thus forming a "flue gas corridor". It is found by simulation that the velocity of fly ash particles in the flue gas corridor has been increasing, and at the exit boundary of the flow field, the velocity is almost twice that of the inlet velocity, and at the same time, It can be observed that the average flue gas velocity in the corridor is higher than that in the straight pipe section. In the flue gas at the bend, the fly ash particle velocity is larger, the wear rate is increased, and the structural characteristics of the bend pipe are added. So that the bend pipe needs to focus on the area of abrasion prevention. In the flow field analysis, we found that the maximum wear occurred in the first row, and the staggered tube line occurred in the middle line. The difference of the structure of the two lines caused the change of wear position. The wear of staggered tube row is greater than that of straight line tube row. The content of the simulation is basically in line with the facts, which is helpful to the theoretical research and can provide guidance for the actual operation of the power plant.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM621.2
本文编号：2282795
[Abstract]:After the pulverized coal is burned in the furnace, the flue gas scour the tail heating surface pipe, and the fly ash particles in the flue gas impinge on the wall of the pipe, which causes wear and tear to the pipe. Wear can cause tube strength to decrease, cause economizer to burst tube. Compared with other heating surfaces, the economizer is arranged in the lower part of the tail flue of the furnace, the flue gas temperature is lower, the hardness of the fly ash particles in the entrainment is larger, and the speed is faster because of the effect of gravity. As a result, economizer wear is much larger than the superheater. There are many factors that cause the wear of economizer, such as the physical properties of particle (composition, particle size, shape, hardness), smoke velocity and so on. The layout of economizer will also affect the wear. By using Fluent software, considering that the flue gas and fly ash particles belong to gas-solid two-phase flow, and combining with the applicable range of the model, the discrete phase model is chosen to simulate the turbulent model, and the RNG k- 蔚 model is chosen for the turbulence model. The numerical simulation of partial tube row of economizer is carried out. The formation of flue gas corridor between the bends of economizer and the furnace wall and the influence of different arrangement of line and staggered tubes on the flow field of flue gas and fly ash particles are studied in order to judge the size of wear and tear. Through simulation, the formation and flow field characteristics of flue gas corridor are obtained. The flue gas enters the economizer pipe discharge area, because the resistance coefficient of the gap between the bend pipe and the furnace wall is smaller than that of the tube, there is a low pressure area in the gap, and some flue gas flow direction changes and draws closer to the gap, thus forming a "flue gas corridor". It is found by simulation that the velocity of fly ash particles in the flue gas corridor has been increasing, and at the exit boundary of the flow field, the velocity is almost twice that of the inlet velocity, and at the same time, It can be observed that the average flue gas velocity in the corridor is higher than that in the straight pipe section. In the flue gas at the bend, the fly ash particle velocity is larger, the wear rate is increased, and the structural characteristics of the bend pipe are added. So that the bend pipe needs to focus on the area of abrasion prevention. In the flow field analysis, we found that the maximum wear occurred in the first row, and the staggered tube line occurred in the middle line. The difference of the structure of the two lines caused the change of wear position. The wear of staggered tube row is greater than that of straight line tube row. The content of the simulation is basically in line with the facts, which is helpful to the theoretical research and can provide guidance for the actual operation of the power plant.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM621.2
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