The lime slurry nozzle is a key equipment component in the flue gas drying desulfurization system. The atomizing performance of lime slurry nozzles with different structure parameters under low pressure conditions was experimentally studied by using the laser diffraction/scattering particle size distribution analyzer (Win212-2), and the optimized structure of nozzle was obtained. Experimental results indicate that there is a relation between the average granularity and the fluid pressure and that the spray angle increases with increasing pressure. As the solid percentage of lime slurry increases, the Sauter Mean Diameter (SMD) of droplets also increases, the atomizing performance of the nozzle slightly decreases, and the spray angle of nozzle also decreases. The flux of lime slurry is uniformly distributed along the radial direction of the nozzle, and then the flux characteristic of the spray nozzle is obtained. In order to meet the size of droplets for the semidry desulphurization process, the performance of an optimum nozzle was experimentally tested. The proper nozzle type and optimal parameters for low pressure swirl nozzles are suggested. 1. Introduction To date, secondary pollution is still a serious problem for our environment caused by some industries, such as power stations and waste incineration plants. Therefore, flue gas is necessarily purified before being discharged into the atmosphere. In the semidry flue gas desulfurization process, the lime slurry spray nozzle is an important component for the spray-drying flue gas desulfurization device. The atomizing performance of the spray nozzle, which has significant effects on the flue gas desulphurization as well as the security and economy of the semidry flue gas desulphurization system, mainly depends on the Sauter Mean Diameter (SMD) of droplets, spray angle, atomization uniformity, and so on. The effects of water-coal-slurry spray nozzle structure on the distribution of atomizing particles, SMD of droplets, and spray angle were thoroughly analyzed by Yu et al. [1]. It was found that the atomization quality can be enhanced by using a new method of multistage atomization as discussed by Huang et al. [2]. In order to take full advantage of the atomizing gas momentum, the atomizing gas is brought into the nozzle by multiple stages and the next stage atomizing air is guided into the nozzle until the atomizing air at previous stage is completely consumed. Zeng et al. [3] studied the behaviour of collared jets under different expansion ratios and the use of indeterminate-origin collars comprising
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