【摘要】：為緩解北方地區(qū)水資源缺乏的情況,直接空冷系統(tǒng)被世界各國普遍采用,尤其在富煤缺水地區(qū)更是得到廣泛應(yīng)用。然而直接空冷系統(tǒng)換熱器長期暴露在外,冷卻介質(zhì)是空氣,所以周圍空氣的溫度、風(fēng)速變化對其換熱能力以及正常運行有直接影響。直冷系統(tǒng)的換熱性能對機組運行的經(jīng)濟性至關(guān)重要,背壓的波動與機組運行安全性緊密相關(guān),因此研究直接空冷系統(tǒng)受環(huán)境因素影響的性能變化十分重要。本文通過對某廠的地形進行考察研究發(fā)現(xiàn),該廠直接空冷機組在常年風(fēng)沙及各種空氣中的雜質(zhì)影響下,形成了一定管外結(jié)垢,直接空冷換熱器性能逐年降低,該地環(huán)境溫度夏季常年較高,對機組的背壓有惡劣影響。而該廠廠址布置情況較為特殊,空冷島兩側(cè)山峰構(gòu)成了一條流道,而常年SSW風(fēng)向的氣流從流道的入口流入,直冷系統(tǒng)空冷島位于流道中間,兩側(cè)流道形成了“狹管效應(yīng)”,增大環(huán)境風(fēng)速,但具體影響數(shù)值并未有過類似研究。因此將該廠直接空冷島與兩側(cè)的山峰進行建模,通過數(shù)值模擬的方式分析風(fēng)速變化時直接空冷換熱能力改變與空冷島區(qū)域流場的變化。本文針對環(huán)境風(fēng)影響空冷島換熱性能的問題,結(jié)合間接空冷的抗自然因素變化影響能力以及噴射式凝汽器換熱端差小的特點,提出了一種新型抽汽冷卻方式,并將該種方式與傳統(tǒng)噴淋方式冷卻效果進行對比,發(fā)現(xiàn)這種冷卻方式效果更為理想,最后對全文結(jié)論進行總結(jié)與展望。
[Abstract]:In order to alleviate the shortage of water resources in the northern region, direct air cooling system is widely used in the world, especially in the areas rich in coal and water shortage. However, the heat exchanger of direct air-cooling system is exposed for a long time, and the cooling medium is air, so the temperature and wind speed of the surrounding air have a direct effect on the heat transfer capacity and normal operation of the heat exchanger. The heat transfer performance of direct cooling system is very important to the economy of unit operation, and the fluctuation of back pressure is closely related to the operation safety of the unit, so it is very important to study the performance change of direct air cooling system affected by environmental factors. Based on the investigation of the topography of a factory, it is found that the direct air-cooled unit in this plant has formed a certain scale outside the tube under the influence of the annual wind sand and various impurities in the air, and the performance of the direct air-cooled heat exchanger has been reduced year by year. The ambient temperature is high all year round in summer, which has a bad effect on the back pressure of the unit. The location of the plant is very special. The peaks on both sides of the air-cooled island form a channel, and the air flow from the SSW wind direction flows through the inlet of the channel. The air-cooled island of the direct-cooling system is located in the middle of the channel, and the "narrow pipe effect" is formed on both sides of the channel. Increasing the environmental wind speed, but the specific impact value has not been studied. Therefore, the direct air-cooled island and the peaks on both sides of the plant are modeled, and the change of the direct air-cooling heat transfer capacity and the flow field in the air-cooled island area are analyzed by numerical simulation. Aiming at the problem of the influence of ambient wind on the heat transfer performance of air-cooled island, combined with the influence ability of indirect air cooling against natural factors and the characteristics of small end difference of heat transfer of jet condenser, a new type of extraction cooling method is put forward in this paper. The cooling effect of this method is compared with that of the traditional spray method, and it is found that the cooling effect is more ideal. Finally, the conclusion of this paper is summarized and prospected.
【學(xué)位授予單位】：華北電力大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM621

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本文編號：2426011