【摘要】：循環(huán)泵是火電廠煙氣脫硫系統(tǒng)中的關(guān)鍵設(shè)備,循環(huán)泵在運(yùn)行中存在氣蝕、腐蝕和磨損等問題,特別是氣蝕形成的瞬時(shí)高壓對(duì)循環(huán)泵的沖擊非常大,是循環(huán)泵的主要破壞形式。本文通過對(duì)壁面附近的單空泡潰滅動(dòng)力學(xué)過程的數(shù)值模擬,探討循環(huán)泵氣蝕問題的防治措施。由于漿液成份的復(fù)雜性,本文用水代替漿液進(jìn)行模擬,并考慮水蒸氣粘度隨溫度和壓力變化(簡稱為非定常粘度)對(duì)計(jì)算模型進(jìn)行了優(yōu)化,得到了不同流場背景壓力下空泡潰滅過程各特征參數(shù)的變化情況,并分析微射流及潰滅最大壓力的相關(guān)影響因素。本文還模擬了水蒸氣-空氣混合空泡的近壁面潰滅過程,得到了不同含氣量下混合空泡潰滅過程的相關(guān)特征參數(shù)。模擬結(jié)果表明:非定常粘度的水蒸氣空泡潰滅過程與定常(μ=constant)粘度的空泡潰滅過程大致相同,在流場背景壓力為0.1~0.6MPa的情況下,非定常粘度的水蒸氣空泡潰滅過程均比粘度為常數(shù)的水蒸氣空泡潰滅過程的對(duì)稱性好,潰滅過程形態(tài)變化較為接近;非定常粘度的水蒸氣空泡潰滅過程產(chǎn)生的射流速度均低于定常粘度的水蒸氣空泡,而潰滅最大壓力則相反;射流產(chǎn)生的水擊壓力對(duì)壁面的影響小于空泡潰滅最大壓力;混合空泡射流速度與空氣含量關(guān)系不明顯;混合空泡的潰滅最大壓力隨空氣含量的變化曲線近似為拋物線,在空氣含量為0.5時(shí)達(dá)到最高,在2100MPa左右。通過模擬分析,提出了循環(huán)泵氣蝕問題的防治措施:控制再氧化空氣的通入量、增加漿液的空氣溶解能力和調(diào)整漿液層的壓力。吸收塔底部再氧化空氣的通入量,應(yīng)綜合考慮循環(huán)泵的最大流量及運(yùn)行負(fù)荷情況。增加漿液對(duì)空氣的溶解度可以降低空氣總量和空泡中空氣含量,且改善漿液的抗空化的能力。
[Abstract]:Circulating pump is the key equipment in flue gas desulfurization system in thermal power plant. There are some problems such as cavitation, corrosion and wear in operation of circulating pump, especially the impact of instantaneous high pressure formed by cavitation on circulating pump is very big, which is the main failure form of circulating pump. Based on the numerical simulation of the dynamic process of single cavitation collapse near the wall, this paper discusses the prevention and cure measures of the cavitation problem of the circulating pump. Because of the complexity of the composition of the slurry, the model is optimized by using water instead of the slurry, and considering the variation of the water vapor viscosity with temperature and pressure (referred to as unsteady viscosity). The variation of characteristic parameters of cavitation collapse process under different background pressure of flow field is obtained, and the influence factors of micro-jet and maximum collapse pressure are analyzed. In this paper, the near wall collapse process of water vapor air mixed cavitation is simulated, and the relevant characteristic parameters of the mixed cavitation collapse process with different gas content are obtained. The simulation results show that the process of vapor bubble collapse with unsteady viscosity is approximately the same as that with constant viscosity, and the flow field background pressure is 0.1~0.6MPa. The process of vapor bubble collapse with unsteady viscosity is more symmetrical than that with constant viscosity, and the morphological changes of the collapse process are close to each other. The velocity of water vapor bubble collapsing with unsteady viscosity is lower than that of water vapor bubble with constant viscosity, but the maximum pressure of collapse is opposite, the influence of water hammer pressure generated by jet on the wall is less than the maximum pressure of bubble collapse. The relationship between the velocity of mixed cavitation jet and air content is not obvious, and the curve of maximum collapse pressure with air content is approximately parabola, reaching the highest at 0.5 air content, about 2100MPa. Through simulation and analysis, the measures to prevent cavitation erosion of circulating pump are put forward: controlling the flux of reoxidized air, increasing the air dissolution capacity of slurry and adjusting the pressure of slurry layer. The maximum flow rate and operating load of the circulating pump should be taken into account when reoxidizing the air at the bottom of the absorber. Increasing the solubility of slurry to air can reduce the total air content and the air content in cavitation and improve the anti-cavitation ability of the slurry.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：X773

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相關(guān)期刊論文 前2條

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本文編號(hào)：2158898