Experimental Study on the Characteristics of Rotating Spray Evaporation of Desulfurization Wastewater

doi:10.11930/j.issn.1004-9649.202005143

Abstract

Abstract: As a type of zero-discharge technologies, the rotary spray drying technology utilizes hot flue gas to evaporate desulfurization wastewater. In this paper, the evaporation test is carried out for both the raw wastewater with different suspended solid (SS) content and the concentrated high salinity wastewater. Specifically, the evaporation characteristics of the desulfurization wastewater in the drying tower are examined with the aid of visualization techniques. Moreover, the impacts of residence time duration, inlet flue gas temperature and gas-liquid ratio on the evaporation characteristics are also investigated during the spray evaporation process of the desulfurization wastewater. The results show that the rotary spray evaporation process has better adaptability to complex desulphurization wastewater components such as high salinity and high SS content. After sprayed from the rotary atomizer, the desulfurization wastewater evaporates rapidly mainly into the zone of 0.75~1.00 m below the atomization tray, and then the precipitated salt and the incompletely evaporated wastewater droplets are further evaporated until the moisture content is less than 2%. The residence time of the flue gas needs to last at least 20 seconds in the spray drying tower so as to ensure the moisture content of ash particles to be less than 2% at the outlet of the tower. The higher the temperature of the inlet flue gas, the lower the particle moisture content at both the bottom and the outlet of the tower. As for the wastewater with the gas-liquid ratio at 12 000 m³/m³ (standard state), the expected outcome of evaporation of wastewater droplets could hardly be guaranteed with the inlet smoke temperature at 280 ℃. However, if the inlet flue gas temperature is maintained at 340 ℃ and the gas-liquid ratio is greater than 10 000 m³/m³(standard state), the bottom ash moisture content is dropped down below 2%, which shows good evaporation effect.

Key words: desulfurization wastewater, evaporation characteristics, residence time, suspended solid concentration, visualization experiment

LI Fei, CHEN Haijie, LIU Fengjun, GU Xiaobing, CHE Guangmin, BAI Yuyong, YANG Linjun. Experimental Study on the Characteristics of Rotating Spray Evaporation of Desulfurization Wastewater[J]. Electric Power, 2021, 54(1): 188-195.

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URL: https://www.electricpower.com.cn/EN/10.11930/j.issn.1004-9649.202005143

https://www.electricpower.com.cn/EN/Y2021/V54/I1/188

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