本文選題：墻式切圓燃燒 + 數(shù)值模擬��； 參考：《華中科技大學(xué)》2015年碩士論文

【摘要】：切圓燃燒方式具有許多優(yōu)點(diǎn),在我國得到廣泛的應(yīng)用。切圓燃燒方式主要特點(diǎn)是爐內(nèi)氣流旋轉(zhuǎn),引起爐內(nèi)旋轉(zhuǎn)中心低壓區(qū)卷吸高溫?zé)煔?讓氣流充分混合,形成良好的著火條件和穩(wěn)定的燃燒環(huán)境,并且顆粒在爐內(nèi)停留時(shí)間長,有利于燃盡。但由于爐膛高度有限,爐膛出口仍然存在氣流的殘余旋轉(zhuǎn),導(dǎo)致水平煙道處左右側(cè)出現(xiàn)煙速偏差與煙溫偏差的現(xiàn)象,使過熱器與再熱器的管屏左右側(cè)吸熱不均勻,出現(xiàn)熱偏差現(xiàn)象,情況嚴(yán)重時(shí),導(dǎo)致受熱面出現(xiàn)超溫爆管事故。因此,研究爐膛出口煙溫偏差對(duì)提高鍋爐運(yùn)行的安全性、可靠性及經(jīng)濟(jì)效益均具有重要意義。本文針對(duì)一臺(tái)660MW的墻式切圓燃燒超臨界鍋爐開展了煙溫偏差優(yōu)化的數(shù)值模擬,并對(duì)基準(zhǔn)工況爐膛出口參數(shù)的模擬結(jié)果與實(shí)驗(yàn)結(jié)果進(jìn)行了對(duì)比,模擬值與實(shí)驗(yàn)值相符合。結(jié)果表明:爐內(nèi)形成了良好的切圓燃燒,煤粉顆粒停留時(shí)間長,有利于燃盡,NOX排放量較低,在進(jìn)入分隔屏底前,爐內(nèi)氣流的溫度場和速度場分布比較對(duì)稱;但由于爐內(nèi)形成逆時(shí)針旋轉(zhuǎn)氣流,在爐膛出口存在著氣流的殘余旋轉(zhuǎn),爐膛出口截面出現(xiàn)比較明顯煙溫偏差,溫度高的區(qū)域集中在截面的右下角,爐膛出口截面的速度分布與溫度分布呈現(xiàn)左低又高的分布。在基準(zhǔn)工況的基礎(chǔ)上,依次進(jìn)行改變SOFA風(fēng)水平擺角、二次風(fēng)擋板開度、SOFA風(fēng)擋板開度的模擬實(shí)驗(yàn)和試驗(yàn)研究,分析了其三種變工況對(duì)爐膛出口煙氣速度與煙溫偏差的影響。結(jié)果表明:隨著SOFA風(fēng)水平擺角逆時(shí)針擺動(dòng),爐膛內(nèi)氣流旋轉(zhuǎn)強(qiáng)度減弱,出口截面水平分速度及切圓直徑減小,煙溫偏差隨之減小;隨二次風(fēng)擋板開度增加時(shí),爐膛內(nèi)氣流旋轉(zhuǎn)強(qiáng)度較強(qiáng),出口切圓直徑及水平分速度增大,煙溫偏差隨之增大;隨SOFA風(fēng)擋板開度增加,其結(jié)果與二次風(fēng)擋板開度增加相反。通過對(duì)三組變工況的調(diào)整,有效的降低了爐膛出口左右兩側(cè)的煙溫偏差。
[Abstract]:Tangential combustion has many advantages and has been widely used in China. The main feature of tangential combustion is that the air flow in the furnace rotates, which causes the high temperature flue gas to be absorbed in the low pressure region of the rotary center in the furnace, so that the air flow can be fully mixed to form a good ignition condition and a stable combustion environment, and the particle stays in the furnace for a long time. In favor of burnout. However, due to the limited height of the furnace, there is still a residual air flow rotation at the outlet of the furnace, which leads to the deviation of the smoke velocity and the smoke temperature at the left and right side of the horizontal flue, resulting in uneven heat absorption between the left and the right side of the tube screen of the superheater and the reheater. The phenomenon of thermal deviation, when the situation is serious, lead to the accident of overheated tube explosion on the heating surface. Therefore, it is of great significance to study the deviation of flue gas temperature at furnace outlet to improve the safety, reliability and economic benefit of boiler operation. In this paper, the numerical simulation of flue gas temperature deviation optimization for a 660MW wall tangent circle combustion supercritical boiler is carried out. The simulation results of furnace outlet parameters under the standard operating conditions are compared with the experimental results, and the simulation results are in good agreement with the experimental results. The results show that a good tangential combustion is formed in the furnace, and the residence time of pulverized coal particles is long, which is beneficial to the low emission of no _ x from burn-out. Before entering the bottom of the separator screen, the distribution of the temperature field and velocity field of the gas flow in the furnace is relatively symmetrical. However, due to the formation of counterclockwise rotating air flow in the furnace, there is a residual rotation of the gas flow at the furnace outlet, and the section of the furnace outlet has a relatively obvious deviation of smoke temperature, and the high temperature area is concentrated in the lower right corner of the section. The velocity distribution and temperature distribution of the outlet section of the furnace show the left low and high distribution. On the basis of the reference condition, the simulation experiment and experimental study of changing the horizontal swing angle of SOFA wind and the opening degree of secondary windshield board and the opening degree of sofa windshield board are carried out, and the influence of three different working conditions on flue gas velocity and flue gas temperature deviation at furnace outlet is analyzed. The results show that with the counterclockwise swing of the horizontal swing angle of the SOFA wind, the intensity of the air flow in the furnace decreases, the horizontal velocity of the exit section and the tangential diameter decrease, and the deviation of smoke temperature decreases with the increase of the opening degree of the secondary windshield. With the increase of the opening degree of the SOFA windshield, the result is contrary to the increase of the opening degree of the secondary windshield plate with the increase of the air flow rotation intensity in the furnace and the increase of the tangential diameter and horizontal velocity of the outlet. By adjusting the three sets of variable working conditions, the deviation of flue gas temperature on the left and right sides of the furnace outlet is reduced effectively.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TK229.2

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