Experimental Study On Temperature And Humidity Field During The Process Of Flue Gas Humidification In CFB-FGD

In the process of circulating fluidized bed for flue gas desulfurization, the ion reaction between gas and fluid is the crucial factor to determine the desulfurization efficiency. The distribution feature of temperature and humidity in the desulfurizer is studied by means of two measurement methods in this paper. This settles the foundation for further understanding of desulfurization mechanism and optimization of structure and operating parameters of CFB.Based on the traditional measurement methods, a double-loop extraction temperature and humidity measurement device is designed for measuring the temperature and humidity in the multistage spouted desulfurizer under the condition of three phase's coexistence. The distributions of temperature and humidity in the desulfurizer were measured in a thermal state facility by the new measurement device. The results show that in the atomization region, two peaks of temperature appeared in the radial direction, and the curve of humidity is of W type. It also indicates that evaporation intensity is elevated at first then depressed, and reaches the maximum value at the position which is 200mm away from the nozzle. Under the condition of the inlet flue gas temperature of 180℃, the flow rate of slurry of 0.8 kg/h, and air/liquid mass ratio of 0.2, the droplets are completely evaporated at the position which is 800mm away from the nozzle.For further understanding of the distribution feature of the temperature and humidity, the temperatures and humidity with different atomization degrees, inlet conditions and structures were measured on each radial section by the reticular measurement device which can move along the axial direction and by the data-acquisition system which is developed on the basis of MGCS. During the measurement, slurry is replaced by pure water.Due to the influence of evaporation environments and characteristics of droplets, it takes much more time for the pure water drying than the slurry with same mass. The increase of water leads to the prolonging of duration of droplets and the reducing of fluid temperature. And the reducing of fluid temperature decreases mass transfer resistance. It will be beneficial for desulfurization. With the increase of air/liquid mass ratio, the distribution of droplets in the desulfurizer becomes more even. But it shortens the existence region of droplets, and decreases the contact duration between gas and fluid. With the decrease of the flow velocity of flue gas, the reaction zone and the existence region of droplets in the desulfurizer are slightly shortened. But the contact duration between SO2 and water increases greatly.The blunt body can rectify the deflection of flow field in effect. It can also prevent the collision between droplets and wall and improve the fluidized state to make the distribution feature of temperature and humidity become more even.