本文選題：數(shù)值模擬 + 溫度場(chǎng)　； 參考：《中國(guó)礦業(yè)大學(xué)》2015年碩士論文

【摘要】：超超臨界機(jī)組通過(guò)提高蒸汽參數(shù)來(lái)提高燃煤機(jī)組的發(fā)電效率,有效降低供電煤耗,實(shí)現(xiàn)節(jié)能與低污染排放,得到快速的發(fā)展。然而裝機(jī)機(jī)組逐年增大,管道運(yùn)行工況一再惡化,使得管道爆管事故時(shí)有發(fā)生,給電廠正常運(yùn)行帶來(lái)極大的經(jīng)濟(jì)損失。針對(duì)大型機(jī)組,僅用原有的熱偏差及壁溫計(jì)算方法已不適用。鑒于此,本文采用數(shù)值模擬和實(shí)驗(yàn)相結(jié)合的分析方法對(duì)超超臨界機(jī)組下?tīng)t膛燃燒情況及上爐膛受熱面溫度分布進(jìn)行研究。本文運(yùn)用層次分析法對(duì)超超臨界鍋爐的失效模式及導(dǎo)致失效的各因素進(jìn)行了分析。通過(guò)建立水冷壁、過(guò)熱器、再熱器的失效模型,對(duì)失效模型構(gòu)造相對(duì)應(yīng)的判斷矩陣進(jìn)而求出各失效因素的權(quán)重,得出了不同類(lèi)型受熱面的失效因素相對(duì)重要性,為后續(xù)有針對(duì)性的研究受熱面失效原因提供依據(jù)。對(duì)于爐膛燃燒模擬,通過(guò)對(duì)爐膛1:1實(shí)體建模計(jì)算與分析,詳細(xì)探討了進(jìn)煤量、過(guò)量空氣、煤粉細(xì)度、煤種及工況變化對(duì)燃燒的影響作用,結(jié)果表明:在二次風(fēng)一定的情況下,爐膛整體溫度隨著煤量的增加溫度呈先升高后降低的趨勢(shì),進(jìn)煤量的調(diào)整僅僅使各個(gè)部分的溫度改變,對(duì)切圓形態(tài)影響不大,11kg/s進(jìn)煤量燃燒效果最好。進(jìn)煤量一定的情況下,爐膛溫度和峰值溫度隨著過(guò)量空氣量的增加先升高而后降低,在過(guò)量空氣系數(shù)為1.15時(shí)煤粉燃燒較為充分。煤粉越細(xì)進(jìn)行燃燒的表面積越大,煤粉本身的熱阻越小,加熱煤粉至著火溫度所需要的時(shí)間越短,燃燒越完全,可以在爐膛較低位置開(kāi)始很劇烈的燃燒并形成較高的爐膛溫度。低位發(fā)熱量高與揮發(fā)分含量高的煤種形成的爐膛整體溫度較高。高負(fù)荷工況下的燃盡區(qū)發(fā)熱多,爐膛出口溫度較高,輻射強(qiáng)度較大。本文采用解析計(jì)算與數(shù)值模擬相結(jié)合的方法考察了不同高度下?tīng)t膛水冷壁的溫度分布、應(yīng)力分布,并且找出了水冷壁的危險(xiǎn)區(qū)域。結(jié)果表明:水冷壁的截面最高溫度在向火側(cè)鰭片端部位置,其溫度分布隨著爐膛高度的增加呈先升高后降低的趨勢(shì),在高度為38m處達(dá)到最高值。管壁截面最高溫度出現(xiàn)在向火側(cè)最高點(diǎn)處,最大應(yīng)力位置為背火側(cè)管壁與鰭片接觸面,水冷壁危險(xiǎn)區(qū)域?yàn)樯舷氯紵髦虚g部位。對(duì)于上爐膛受熱面模擬,本文基于燃燒模擬得到受熱面所處的管屏區(qū)進(jìn)口的煙氣溫度和速度邊界,將下?tīng)t膛煙氣組分通過(guò)運(yùn)輸方程傳遞上去,在此基礎(chǔ)上對(duì)管屏區(qū)進(jìn)行流固共軛傳熱分析,得到各工況下管道外壁溫度分布及波動(dòng)情況并且與電廠實(shí)測(cè)數(shù)據(jù)進(jìn)行了驗(yàn)證。結(jié)果表明:一級(jí)過(guò)熱器與三級(jí)過(guò)熱器類(lèi)似,高溫區(qū)出現(xiàn)爐膛中心處,變工況情況下管外壁溫度的波動(dòng)幅度由爐膛中心向爐膛兩側(cè)逐漸減小,爐膛中心處波動(dòng)最大。從二級(jí)再熱器以上開(kāi)始,高溫區(qū)由爐膛中心向爐膛兩側(cè)擴(kuò)展,并且工況越低擴(kuò)展越迅速,擴(kuò)展的距離越長(zhǎng)。溫度波動(dòng)大的區(qū)域也隨著爐膛高度的增加從爐膛中心向兩側(cè)擴(kuò)展,危險(xiǎn)區(qū)域從爐膛中心附近向爐膛兩側(cè)擴(kuò)展。通過(guò)對(duì)鍋爐已發(fā)生的過(guò)熱器失效管道及水冷壁焊縫裂紋進(jìn)行失效分析,找出了其相應(yīng)的失效原因,驗(yàn)證了失效模型建立和模擬結(jié)果的正確性,提出了改進(jìn)措施。
[Abstract]:The super supercritical unit improves the efficiency of the power generation by improving the steam parameters, effectively reducing the power supply coal consumption, realizing the energy saving and low pollution emission, and gets the rapid development. However, the installed unit is increasing year by year, the running condition of the pipeline is deteriorating again and again, which makes the pipe burst accident happen and brings great economy to the normal operation of the power plant. For large units, only the original thermal deviation and wall temperature calculation method is not applicable. In view of this, this paper uses numerical simulation and experimental analysis method to study the combustion of the lower furnace and the temperature distribution of the heating surface in the upper furnace. This paper uses the analytic hierarchy process to the failure mode of ultra supercritical boiler. Through the establishment of the failure model of water cooling wall, superheater and reheater, the corresponding judgement matrix of the failure model is constructed and the weight of each failure factor is obtained. The relative importance of the failure factors of different types of heat surface is obtained, which is the cause for the subsequent research on the failure of the heating surface. For the furnace combustion simulation, the effect of coal intake, excess air, pulverized coal fineness, coal and working conditions on combustion is discussed in detail through the calculation and analysis of 1:1 solid modeling in the furnace chamber. The results show that the overall temperature of the furnace increases first and then decreases with the increase of coal quantity in the case of two times of wind. The adjustment of coal intake is only the change of the temperature of each part, which has little influence on the tangential shape. The effect of 11kg/s coal intake is the best. Under the condition of certain amount of coal intake, the furnace temperature and peak temperature rise first and then decrease with the increase of excess air. The pulverized coal is finer when the excess air coefficient is 1.15, the finer the pulverized coal is. The larger the surface area of the row combustion, the smaller the thermal resistance of the pulverized coal, the shorter the time to heat the pulverized coal to the ignition temperature, the more complete the combustion, the higher the combustion and the higher furnace temperature in the lower chamber of the hearth, the higher the overall temperature of the hearth formed by the high calorific value and the high volatile content of the coal. The temperature of the furnace outlet is high and the furnace outlet temperature is high and the radiation intensity is high. In this paper, the temperature distribution and stress distribution of the water cold wall at the furnace chamber at different heights are investigated by the method of analytical calculation and numerical simulation, and the dangerous area of the water wall is found. The results show that the highest temperature of the section of the water wall is on the side fin of the fire side. With the increase of the furnace height, the temperature distribution at the height of the furnace increases first and then decreases, and reaches the highest value at the height of 38m. The highest temperature of the section of the tube wall appears at the highest point of the fire side, the maximum stress position is the contact surface of the back fire side tube wall and the fin, and the dangerous area of the water wall is the middle part of the upper and lower burner. On the basis of combustion simulation, the temperature and velocity boundary of the inlet of the tube screen area of the heated surface is obtained based on the combustion simulation, and the flue gas components in the lower furnace are passed through the transport equation. On this basis, the flow solid conjugate heat transfer analysis is carried out on the tube screen area, and the temperature distribution and fluctuation of the outer wall of the pipe are obtained and the power plant is obtained. The measured data are verified. The results show that the first class superheater is similar to the three stage superheater, and the high temperature zone appears at the hearth center. The fluctuation range of the outer wall temperature is gradually reduced from the furnace center to the hearth, and the center of the furnace fluctuates most. From the two reheater, the high temperature zone is from the furnace center to the furnace two. The larger the range of temperature fluctuates from the furnace center to both sides of the furnace center, and the danger zone extends from the furnace center to the hearth. The failure analysis of the superheater failure pipeline and the water wall weld crack has been carried out. The corresponding failure causes were found out, the correctness of the failure model establishment and the simulation results were verified, and the improvement measures were put forward.
【學(xué)位授予單位】：中國(guó)礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TM621.2

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本文編號(hào)：1907941