Study On Separation Characteristics Of Corrugated Plate Dryer

Natural circulation steam generator absorb heat from nuclear reactor and produce saturated steam for turbine.To promote steam quality,a two stage steam-water separation system is set in steam generator,and corrugated plate dryer is the last stage of this system,which determines the steam quality.Scine the output power of nuclear reactor increases continually,the performance of dryer must be improved to ensure the steam under high steam load.Although some research has been carried out topic before,the separation mechanism and performance characteristics of corrugated plate dryer is still not completely understand at present.To optimize the performance of the dryer,the separation characteristics and mechanism should be fully understood,and that is reason we carry out this study.Combining experimental and theoretical analysis,this paper studies the separation characteristics and Mechanism of the corrugated plate dryer.The detailed work is as follows:Firstly,an experimental bench was established to simulated gas-water separation in corrugated plate dryer,and the experimental bench and method was optimized after testing.On this basis,the influence of inlet moisture parameters?particle size distribution,inlet humidity and inlet velocity?,corrugated plate structure parameters?plate spacing,hook spacing,hook form?and drain sink structure parameters on the separation performance were studied.In addition,experiment was carried to study the influence of drain sink structure parameters on the re-entranment and the critical conditions of the wall liquid film rupture in corrugated plate channel.Finally,the wall liquid film rupture model and droplet separation model are deduced to explain the above experimental phenomena.The following concludes were obtained through the above research:?1?The wedge-shaped mixing section can achieve higher moisture content at the inlet of the dryer.In the experiment,the number of working nozzles must be controlled to keep the inlet moisture content steady,otherwise the contribution to separation efficiency raising by inlet moisture content increase and inlet speed increase would mixed up.?2?When droplets size increases,dryer's separation efficiency increases,while pressure drop and the critical airflow speed remain;when moisture content increases,separation efficiency increases,pressure drop remains,and critical airflow speed decreases;when airflow speed increases,separation efficiency drops after increasing to a high stable stage,pressure drop increases exponentially;when plate spacing increases,separation efficiency and pressure drop decrease,and critical airflow speed increases.Theseparation efficiency is determined by the flow area in corrugated plate channel rather than spacing of drainage hook.Compared with the drain sink with clapboard,the non-separated drain sink reduces the separation efficiency and critical speed of the dryer due to the air flows out of the dryer through sink,causing"short-circuit"of the dryer.?3?The critical break-up theory of liquid film indicates that corrugated plate structure factor k₁,fluid property parameter factor k₂ and liquid film thickness h determine the critical condition of film break-up.A larger k₁ and a smaller h are better for re-entrainment relief.When the liquid film is thin,the present theoretical criterion of film break-up is bigger than the experimental value;when the liquid film thickness is large,the two are consist well.The fluctuation of the film surface and the vortex formed by the gas flow after the folded corner accelerate the film break-up.Considering the separation efficiency and re-entrainmnet of the dryer,the ideal structural parameters of corrugated plate were that the bend angle is about30.6°and the plate spacing is about 11.2 mm...