scholarly journals Simulation Study on Centrifugal Spray Evaporation Characteristics and Process Optimization of Desulfurization Wastewater

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 837
Author(s):  
Ning Zhao ◽  
Yongxin Feng ◽  
Debo Li ◽  
Zongkun Li
Keyword(s):  
Flue Gas ◽  
Gas Flow ◽  
Droplet Evaporation ◽  
Advanced Treatment ◽  
Axial Distance ◽  
Liquid Ratio ◽  
Evaporation Time ◽  
Liquid Discharge ◽  
Drying Technology ◽  
Desulfurization Wastewater

As an advanced treatment of desulfurization wastewater, centrifugal spray drying technology, which can achieve a zero liquid discharge target, has attracted wide attention and great interest in recent years. However, the results of previous studies were based on the laboratory-scale centrifugal spray dryer. In order to study the evaporation characteristics of desulfurization wastewater and the parameter optimization of the dryer, the evaporation model of wastewater droplets was established. The effects of parameters such as the angle of the deflectors, gas–liquid ratio and atomizer speed on droplet evaporation were studied by numerical simulation. The results show that with the increase in the angle of the deflectors, the swirl effect of flue gas flow field is more obvious and the time and axial distance required for the complete evaporation of the droplets are shorter. Reducing the gas–liquid ratio will make the average evaporation time longer. Moreover, a higher atomizer speed is helpful for the evaporation of the droplets. The optimum gas–liquid ratio and rotational speed are found to be 9300 m3/Nm3 and 16,000 rpm, respectively.

scholarly journals Application and performance evaluation of desulfurization wastewater spray drying technology

2020 ◽  
Vol 143 ◽  
pp. 02029
Author(s):  
Zhang Shanshan ◽  
Wang Renlei ◽  
Tang Guorui ◽  
Dai YU
Keyword(s):  
Spray Drying ◽  
Flue Gas ◽  
Unit Load ◽  
Air Preheater ◽  
Mass Fractions ◽  
Denitrification Reactor ◽  
And Performance ◽  
Drying Technology ◽  
Gas Volume ◽  
Desulfurization Wastewater

In order to realize zero discharge of desulfurization wastewater, spray drying technology of desulfurization wastewater was used in 2x330MW unit of a power plant. Its principle was to use a rotary atomizer for atomization,and a part of hot flue gas was drawn from the SCR denitrification reactor and air preheater into the drying tower, the heat was used to evaporate the desulfurization wastewater in a spray drying tower. The salt in the waste water was mixed with the dust, which was collected and removed by the electric dust remover. Then the water vapor was mixed with the flue gas and finally enters the desulfurization tower.The field test was carried out under the condition that the unit load was 100% and the amount of desulfurization wastewater treated was 5.1m3/h.The results showed that the hot smoke gas volume of drying tower was about 64896m3/h, The smoke temperature at the inlet and outlet of the drying tower were 335℃ and 205℃ respectively,the moisture content of drying products was only 0.05%. The content of HCl in the flue gas at the inlet and outlet of the drying tower were 55mg/L and 195mg/L respectively, the mass fractions of Cl removal and Cl volatilization in desulfurization wastewater were 87.7% and 12.3% respectively. The increase of Cl content in the dried products had little effect on the utilization of fly ash.

scholarly journals Analysis of Main Influencing Factors of the Wastewater Evaporation in Flue Duct

2020 ◽  
Vol 143 ◽  
pp. 02025
Author(s):  
Haowei Pan ◽  
Liang Zhang ◽  
Wei Li ◽  
Ning Gao ◽  
Yin Liu
Keyword(s):  
Flue Gas ◽  
Gas Flow ◽  
Droplet Diameter ◽  
Operating Cost ◽  
Simulation Method ◽  
Inlet Temperature ◽  
Factors Affecting ◽  
Two Factors ◽  
High Pollution ◽  
Desulfurization Wastewater

Desulfurization wastewater has the characteristics of small discharge and high pollution, and must be strictly treated. To obtain the main factors affecting the evaporation characteristics of desulfurization wastewater in boiler flue, a 600MW unit of a coal-fired power plant in China was taken as an example. According to the theory of fluid mechanics and heat transfer, the numerical simulation method was used. The results show that the way the nozzle is installed on the upper wall of the flue inlet can enhance the evaporation effect of the desulfurization wastewater. It is also revealed that the influence of the flue gas flow rate on the droplet evaporation effect is relatively small. The smaller droplet diameter and the higher flue gas inlet temperature will obviously enhance the evaporation effect of the droplets in the flue. However these two factors will increase the operating cost and reduce the boiler thermal efficiency. Therefore, the values of the droplet diameter and the flue gas inlet temperature need to be further determined by technical and economic comparison.

scholarly journals Numerical Investigation on the Evaporation Performance of Desulfurization Wastewater in a Spray Drying Tower without Deflectors

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1022
Author(s):  
Debo Li ◽  
Ning Zhao ◽  
Yongxin Feng ◽  
Zhiwen Xie
Keyword(s):  
Spray Drying ◽  
Droplet Size ◽  
Flow Rate ◽  
Flue Gas ◽  
Gas Flow ◽  
Initial Temperature ◽  
Gas Temperature ◽  
Gas Flow Rate ◽  
Complete Evaporation ◽  
Desulfurization Wastewater

The desulfurization wastewater evaporation technology with flue gas has been widely applied to dispose of desulfurization wastewater. This paper investigates the effect of flue gas flow rate and temperature, wastewater flow rate and initial temperature, and droplet size on the evaporation performance of the desulfurization wastewater in a spray drying tower without deflectors. The results show that the flue gas flow rate and temperature affect the evaporation performance of desulfurization wastewater. The larger flow rate and higher temperature of flue gas correspond to the faster evaporation speed and the shorter complete evaporation distance of the wastewater droplet. Decreasing the flow rate and increasing the initial temperature of the desulfurization wastewater is advantageous to enhance the evaporation speed and shorten the complete evaporation distance of the wastewater droplet. Reducing the droplet size is beneficial to improve the evaporation performance of the desulfurization wastewater. The orthogonal test results show that the factors affecting droplet evaporation performance are ranked as follows: flue gas flow rate > wastewater flow rate > flue gas temperature > wastewater initial temperature > droplet size. Considering the evaporation ratio and the complete evaporation distance, the optimal setting is 14.470 kg/s for flue gas flow rate, 385 °C for flue gas temperature, 0.582 kg/s for wastewater flow rate, 25 °C for wastewater initial temperature, and 60 μm for droplet size. These studied results can provide valuable information to improve the operational performance of the desulfurization wastewater evaporation technology with flue gas.

WATER DROPLET EVAPORATION IN A CHAMBER ISOLATED FROM THE EXTERNAL ENVIRONMENT

2020 ◽  
Vol 6 (3) ◽  
pp. 8-22
Author(s):  
KSENIA A. Batishcheva ◽  
ATLANT E. Nurpeiis
Keyword(s):  
Water Vapor ◽  
Evaporation Rate ◽  
External Environment ◽  
Heat Removal ◽  
Droplet Evaporation ◽  
Droplet Volume ◽  
Evaporation Time ◽  
Aluminum Alloy Amg6 ◽  
Evaporation Of Droplets ◽  
Contact Diameter

With an increase in the productivity of power equipment and the miniaturization of its components, the use of traditional thermal management systems becomes insufficient. There is a need to develop drip heat removal systems, based on phase transition effects. Cooling with small volumes of liquids is a promising technology for microfluidic devices or evaporation chambers, which are self-regulating systems isolated from the external environment. However, the heat removal during evaporation of droplets into a limited volume is a difficult task due to the temperature difference in the cooling device and the concentration of water vapor that is unsteady in time depending on the mass of the evaporated liquid. This paper presents the results of an experimental study of the distilled water microdrops’ (5-25 μl) evaporation on an aluminum alloy AMg6 with the temperatures of 298-353 K in an isolated chamber (70 × 70 × 30 mm3) in the presence of heat supply to its lower part. Based on the analysis of shadow images, the changes in the geometric dimensions of evaporating drops were established. They included the increase in the contact diameter, engagement of the contact line due to nano roughening and chemical composition inhomogeneous on the surface (90-95% of the total evaporation time) of the alloy and a decrease in the contact diameter. The surface temperature and droplet volume did not affect the sequence of changes in the geometric dimensions of the droplets. It was found that the droplet volume has a significant effect on the evaporation time at relatively low substrate temperatures. The results of the analysis of droplet evaporation rates and hygrometer readings have shown that reservoirs with salt solutions can be used in isolated chambers to control the concentration of water vapor. The water droplets evaporation time was determined. The analysis of the time dependences of the evaporation rate has revealed that upon the evaporation of droplets in an isolated chamber under the conditions of the present experiment, the air was not saturated with water vapor. The latter did not affect the evaporation rate.

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