自然通風(fēng)高位收水冷卻塔三維熱力特性的數(shù)值模擬與收水裝置的優(yōu)化研究
發(fā)布時(shí)間：2018-11-19 08:34
【摘要】：電廠中自然通風(fēng)逆流濕式冷卻塔的冷卻性能直接對(duì)整個(gè)電站熱力系統(tǒng)的性能有重要影響,而其性能由于進(jìn)風(fēng)情況不理想而造成出塔水溫偏高,高位收水冷卻塔較于常規(guī)冷卻塔取消了雨區(qū),設(shè)立高位收水裝置將填料下方的冷卻水收集起來,降低了進(jìn)風(fēng)阻力,提高進(jìn)風(fēng)量進(jìn)而改善冷卻塔冷卻性能。文獻(xiàn)[1]指出高位收水可有效利用冷卻水的位能,降低循環(huán)水泵揚(yáng)程15m以上,僅此一項(xiàng),對(duì)于AP1000核電廠,兩臺(tái)機(jī)組全年可節(jié)省廠用電約1.2億KW.h,符合國家節(jié)能減排的戰(zhàn)略方針。本文首先建立了自然通風(fēng)高位收水冷卻塔的計(jì)算模型,并通過實(shí)驗(yàn)驗(yàn)證了高位收水裝置模型的正確性,利用實(shí)型高位塔驗(yàn)證了整塔計(jì)算模型的準(zhǔn)確性。并通過此計(jì)算模型對(duì)高位塔有無環(huán)境自然側(cè)風(fēng)時(shí)進(jìn)行了具體計(jì)算分析,給出了塔內(nèi)外的空氣動(dòng)力場、溫度場、壓力場和進(jìn)風(fēng)量、各區(qū)冷卻貢獻(xiàn)、出塔溫度等重要參數(shù)以及其隨風(fēng)速改變的變化規(guī)律。通過性能保證工況和冬季工況下的計(jì)算分析可知,高位塔配水區(qū)和填料區(qū)的冷卻貢獻(xiàn)占整塔主要份額,在風(fēng)速處于0m/s～10m/s時(shí),隨著風(fēng)速增大,冷卻塔出塔水溫不斷升高,在風(fēng)速處于10m/s-40m/s時(shí),隨著風(fēng)速增大,冷卻塔出塔水溫不斷降低。建立常規(guī)冷卻塔計(jì)算模型,與自然通風(fēng)高位收水冷卻塔進(jìn)行對(duì)比,給出兩者在塔內(nèi)外空氣動(dòng)力場、溫度場以及進(jìn)風(fēng)量、出塔水溫等參數(shù)的不同進(jìn)而比較兩塔的冷卻性能,對(duì)其中差異的影響因素進(jìn)行深入分析。由結(jié)果可知,由于高位塔收水板間流道的導(dǎo)向作用,高位塔收水塔上部主要傳熱傳質(zhì)區(qū),特別是填料上方,空氣流速基本以塔心最高,而塔壁附近區(qū)域空氣流速則相對(duì)較小。而常規(guī)塔最高速度出現(xiàn)在半徑的三分之二左右。高位塔內(nèi)進(jìn)風(fēng)徑向相對(duì)比較均勻。高位塔取消大雨區(qū),可明顯降低通風(fēng)阻力,增大通風(fēng)量,從而通過填料區(qū)和配水區(qū)傳熱傳質(zhì)的加強(qiáng)來彌補(bǔ)雨區(qū)取消所帶來的不利影響,使得低風(fēng)速環(huán)境自然風(fēng)下高位塔冷卻性能優(yōu)于常規(guī)塔。高速環(huán)境風(fēng)下,大穿透能力側(cè)風(fēng)也在高位塔迎風(fēng)側(cè)進(jìn)風(fēng)口上緣收水裝置下方引起較大的縱向漩渦,大幅弱化了迎風(fēng)側(cè)填料的冷卻能力,高位塔熱力性能急劇惡化。通過對(duì)收水裝置高度為9m時(shí)收水板角度為40度、45度、50度和收水板角度為45度時(shí)收水裝置高度為8m、9m、10m時(shí)整塔的計(jì)算分析,對(duì)比其冷卻性能,得出最佳的收水裝置高度和收水板角度。并討論了十字隔墻、導(dǎo)風(fēng)板對(duì)于高位收水冷卻塔的冷卻效果的影響。
[Abstract]:The cooling performance of natural ventilation counterflow wet cooling tower in power plant has a direct impact on the performance of the whole thermal system of the power plant, and its performance is caused by the high water temperature of the tower due to the unsatisfactory inlet air condition. Compared with the conventional cooling tower, the high intake cooling tower cancels the rain area, sets up the high water collection device to collect the cooling water under the packing, reduces the inlet air resistance, increases the intake air volume, and then improves the cooling performance of the cooling tower. It is pointed out in literature [1] that high water intake can effectively utilize the potential energy of cooling water and reduce the lift of circulating water pump more than 15m. For AP1000 nuclear power plant, two units can save about 120 million KW.h, in the whole year. In line with the national energy conservation and emission reduction strategy. In this paper, the calculation model of the natural ventilation high water intake cooling tower is established, and the correctness of the model is verified by experiments, and the accuracy of the whole tower calculation model is verified by using the real high tower. Based on the model, the paper makes a concrete calculation and analysis on whether there is natural cross wind in the high tower, and gives the aerodynamic field, temperature field, pressure field, inlet air volume and the cooling contribution of each district. The important parameters such as tower exit temperature and its variation with wind speed are discussed. Through the calculation and analysis of the performance assurance and winter conditions, it can be seen that the cooling contribution of the high tower water distribution area and the packing area accounts for the main share of the whole tower. When the wind speed is at 0m/s~10m/s, the cooling contribution increases with the increase of the wind speed. When the wind speed is in 10m/s-40m/s, the water temperature of cooling tower is decreasing with the increase of wind speed. The calculation model of conventional cooling tower is established and compared with that of natural ventilation high water intake cooling tower. The differences of aerodynamic field, temperature field, inlet air volume and water temperature of the two towers are given, and then the cooling performance of the two towers is compared. The influence factors of the difference are analyzed in depth. From the results, it can be seen that due to the guiding effect of the passage between the water intake plates of the high tower, the main heat and mass transfer zone in the upper part of the tower, especially above the packing, the air velocity is basically the highest in the tower center, while the air velocity near the tower wall is relatively small. The maximum velocity of the conventional tower appears at about 2/3 of the radius. The air inlet radial is relatively uniform in the high tower. If the high tower cancels the heavy rain area, it can obviously reduce the ventilation resistance and increase the ventilation volume, thus making up for the adverse effect caused by the cancellation of the rain area through the enhancement of heat and mass transfer in the packing area and the water distribution area. The cooling performance of high tower under natural wind in low wind speed is better than that of conventional tower. Under the high speed wind, the large penetration side wind also causes a large longitudinal vortex under the upper edge of the inlet of the upwind tower, which greatly weakens the cooling ability of the upwind side packing, and the thermal performance of the high tower deteriorates sharply. Through the calculation and analysis of the whole tower when the height of the water collector is 9 m, the water collecting plate angle is 40 degrees, 45 degrees, 50 degrees and 45 degrees, the cooling performance of the tower is compared. The optimum height of the water collector and the angle of the water collecting plate are obtained. The influence of cross-wall and air-guide plate on cooling efficiency of high-rise water-collecting cooling tower is discussed.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TM621
本文編號(hào)：2341723
[Abstract]:The cooling performance of natural ventilation counterflow wet cooling tower in power plant has a direct impact on the performance of the whole thermal system of the power plant, and its performance is caused by the high water temperature of the tower due to the unsatisfactory inlet air condition. Compared with the conventional cooling tower, the high intake cooling tower cancels the rain area, sets up the high water collection device to collect the cooling water under the packing, reduces the inlet air resistance, increases the intake air volume, and then improves the cooling performance of the cooling tower. It is pointed out in literature [1] that high water intake can effectively utilize the potential energy of cooling water and reduce the lift of circulating water pump more than 15m. For AP1000 nuclear power plant, two units can save about 120 million KW.h, in the whole year. In line with the national energy conservation and emission reduction strategy. In this paper, the calculation model of the natural ventilation high water intake cooling tower is established, and the correctness of the model is verified by experiments, and the accuracy of the whole tower calculation model is verified by using the real high tower. Based on the model, the paper makes a concrete calculation and analysis on whether there is natural cross wind in the high tower, and gives the aerodynamic field, temperature field, pressure field, inlet air volume and the cooling contribution of each district. The important parameters such as tower exit temperature and its variation with wind speed are discussed. Through the calculation and analysis of the performance assurance and winter conditions, it can be seen that the cooling contribution of the high tower water distribution area and the packing area accounts for the main share of the whole tower. When the wind speed is at 0m/s~10m/s, the cooling contribution increases with the increase of the wind speed. When the wind speed is in 10m/s-40m/s, the water temperature of cooling tower is decreasing with the increase of wind speed. The calculation model of conventional cooling tower is established and compared with that of natural ventilation high water intake cooling tower. The differences of aerodynamic field, temperature field, inlet air volume and water temperature of the two towers are given, and then the cooling performance of the two towers is compared. The influence factors of the difference are analyzed in depth. From the results, it can be seen that due to the guiding effect of the passage between the water intake plates of the high tower, the main heat and mass transfer zone in the upper part of the tower, especially above the packing, the air velocity is basically the highest in the tower center, while the air velocity near the tower wall is relatively small. The maximum velocity of the conventional tower appears at about 2/3 of the radius. The air inlet radial is relatively uniform in the high tower. If the high tower cancels the heavy rain area, it can obviously reduce the ventilation resistance and increase the ventilation volume, thus making up for the adverse effect caused by the cancellation of the rain area through the enhancement of heat and mass transfer in the packing area and the water distribution area. The cooling performance of high tower under natural wind in low wind speed is better than that of conventional tower. Under the high speed wind, the large penetration side wind also causes a large longitudinal vortex under the upper edge of the inlet of the upwind tower, which greatly weakens the cooling ability of the upwind side packing, and the thermal performance of the high tower deteriorates sharply. Through the calculation and analysis of the whole tower when the height of the water collector is 9 m, the water collecting plate angle is 40 degrees, 45 degrees, 50 degrees and 45 degrees, the cooling performance of the tower is compared. The optimum height of the water collector and the angle of the water collecting plate are obtained. The influence of cross-wall and air-guide plate on cooling efficiency of high-rise water-collecting cooling tower is discussed.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TM621
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