Characterization Study Of Atomizing Nozzle For Semi-dry Flue Gas Desulfurization

Nozzle used for lime slurry atomization has an important impact on the flue gas desulfurization as a critical component in the system of semi-dry flue gas desulfurization. Currently in the semi-dry desulfurization process, air-blast atomizer is widely used. The atomization system of air-blast is complicated and another compressor system is needed. It costs more and encounters the problems of poor economy. So the research for pressure nozzle which is suited to semi-dry desulfurization process is significant. In this paper, the research of swirl pressure nozzles is conducted in the two-spouted circulating semi-dry desulfurization process. Using the method of computational fluid dynamics, the spray characteristics required by internally circulating two-stage spouted desulfurization tower are simulated by means of large-scale commercial software FLUENT. A swirl pressure nozzle is designed, in addition, a variety of factors are analyzed and the structure is optimized. Two-film theory model is established, with Euler-Lagrange model, evaporationmodel coupling. A program written in C is invoked by the UDF interface and SO2removal process of internally circulating two-stage spouted desulfurization tower is simulated. Simulation results showed that, SO2removal efficiency related to lime slurry droplet size and atomization angle. When lime slurry droplet size is distributed in75~140μm, desulfurization efficiency can reach more than80%. When lime slurry spray angle is50°, the highest desulfurization efficiency is reached. Empirical coefficient method is used to design a swirl pressure atomizer.Atomization characteristics under different structures and sizes are simulated, the relationship between the nozzle structure size and atomization characteristics is discovered. With the increasing size of the number of swirl tank, the radius of the swirl chamber, the nozzle diameter, the angle of the swirl chamber contraction section, atomization angle increases. Atomization angle decreases with increasing length of the spout length. The best nozzle structure parameters are determined according to the relationship between size and atomization characteristics. Finally, the determined nozzle structure parameters follow, the number of swirl tank is6, nozzle diameter is1mm, spout length is2.5mm, swirl chamber radius is5.5mm. Mixture model and Erosion Model are used to simulate the internal flow field of designed pressure nozzle, the solid phase flow characteristics and wear characteristics of the nozzle are discovered, the particle phase concentration is high in pressure nozzle swirl chamber and nozzle orifice. With a higher particle speed, nozzle clogging is not easy to happen, but lead to nozzle wear easily. Through the optimization of the design of the nozzle, the pressure swirl atomizer can meet the required atomization characteristics of internally circulating two-stage spouted desulfurization tower.