電站鍋爐省煤器磨損分析與數(shù)值模擬
發(fā)布時間：2018-10-20 09:56
【摘要】：煤粉在爐膛內(nèi)燃燒后,產(chǎn)生的煙氣沖刷尾部受熱面管道,煙氣中夾帶的飛灰顆粒撞擊到管子壁面上,對管子造成磨損。磨損會導(dǎo)致管子強度降低,引發(fā)省煤器爆管。和其他受熱面相比,省煤器布置在爐膛的尾部煙道下部,煙氣溫度較低,夾帶的飛灰顆粒硬度較大,由于重力的作用,速度也比較快,由此造成省煤器的磨損量比過熱器等要大很多。 造成省煤器磨損的因素眾多,如顆粒的物理性質(zhì)(成分、粒徑、形狀、硬度)、煙氣速度等,省煤器的布置方式也會對磨損有影響。 本課題借用Fluent模擬軟件,考慮到煙氣和飛灰顆粒屬于氣固兩相流,并結(jié)合模型適用范圍,最終選擇離散相模型來模擬,湍流模型則選擇RNG k-ε模型,對省煤器部分管排進(jìn)行數(shù)值模擬。重點研究省煤器彎管與爐墻之間煙氣走廊的形成,以及順列和錯列管排不同的布置方式對于煙氣、飛灰顆粒流場的影響,以此判斷磨損的大小。 通過模擬,得到煙氣走廊的形成及流場特點。煙氣進(jìn)入省煤器管排區(qū)域,因為彎管與爐墻之間縫隙的阻力系數(shù)比管子的阻力系數(shù)小,在縫隙處產(chǎn)生低壓區(qū),部分煙氣流向發(fā)生改變,向縫隙處靠攏,因此形成“煙氣走廊”。通過模擬發(fā)現(xiàn),煙氣走廊處的煙氣、飛灰顆粒的速度一直增加,到了流場出口邊界時,速度幾乎是入口速度的2倍,同時,可以觀察到走廊處的煙氣平均速度大于直管段的煙氣速度,在彎管處的煙氣、飛灰顆粒速度較大,磨損速率增加,再加上彎管本身的結(jié)構(gòu)特點,使得彎管成為需要重點防磨的區(qū)域。 在順列管排和錯列管排的流場分析中,：我們發(fā)現(xiàn),順列管排的最大磨損一般發(fā)生在第一排的位置,而錯列管排則發(fā)生在中間管排,二者結(jié)構(gòu)的不同造成易磨損部位發(fā)生改變。錯列管排的磨損比順列管排的磨損大。 本課題模擬內(nèi)容基本符合事實,對于理論研究有所幫助,對電廠的實際運行可以提供指導(dǎo)性意見。
[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.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM621.2
本文編號：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.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM621.2
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