Experimental And Theoretical Study On Impinge Stream Scrubber Wet Flue Gas Desulfurization

With the development of economy, the environment we live in is badly polluted by SO₂ from coal-fired boilers. Limestone-gypsum wet flue gas desulfurization technology is being widely applied all over the world because of its advantages: high desulfurization efficiency, widespread and cheap absorbent, retrievable and available byproduct. But the capital cost and operation cost are too expensive to be accepted by our consumer in China. In the thesis, impinge stream scrubber are carried out in order to decrease its capital cost and operation cost.The resistance and desulfurization characteristic of impinge stream scrubber are studied. The effects of slurry flux density and flue gas velocity on the resistance in the scrubbers and the effects of slurry flux density, flue gas velocity, circulating tank pH, SO₂ inlet concentration, and flue gas inlet temperature on desulfurization in the scrubbers are studied. The effects of additives (formic acid, sodium formate and adipic acid) on desulfurization in the scrubbers are also studied. The characteristics of the scrubbers are found. Optimum operation parameters are obtained on the basis of experimental investigation results.The flow field characteristic in impinge stream scrubber such as the diameter and velocity distribution of atomized slurry droplets has great effect on SO₂ absorption. With PIV technology, the diameter distribution and motion state of droplets is investigated. The effects of slurry flux, flue gas velocity, the distance between damper and nozzles and damper type are studied. As can be seen from the experimental investigation results, the mean diameter of slurry droplets increase with a greater slurry flux when the flue gas velocity is indefinite; but when the slurry flux is infinite, it will decrease when the flue gas velocity increases. The atomization effect is better with a less distance between damper and nozzles. And the droplets diameter distribution is Rosin-Rammler.On the basis of multiphase fluid dynamics, chemical reaction kinetics, turbulent diffusion and mass transfer theory, the SO₂ absorption model in impinge stream scrubber is set up. The effect s of slurry flux density, flue gas velocity, droplets diameter change and distribution on flow field distribution and SO2 absorption are taken into consideration. The flow field and SO₂ absorption in 1 impinge stream scrubber has been simulated by CFD method. In order to improve the distribution of flow field, the geometry of tower entrance is optimized. The calculated results agreed well with the test results. The results may give some directions on the design and operation of impinge stream scrubber.The resistance and desulfurization characteristic of turbulent ball scrubber which is fit for medium and small sized station boiler is also studied on pilot-scale and industry application. The reason of flue gas carrying water is analyzed and solved by the optimum design of rotating dehumidification plate to improve dehumidification efficiency.