Analysis Of Pulsed Jet Dust Removal Flow Field And Performance

With the continuous pursuit of high quality of life and the increasing awareness of environmental protection,air pollution,dust emissions have aroused widespread concern.The prevention and control of air pollution has been put on the agenda.High efficiency dust removal has become one of the main ways to respond to the call of emission reduction and environmental protection.It is an important part of the dust removal technology to clean the dust attached to the filter material regularly in the application of dust collector.The cleaning effect directly affects the dust removal efficiency,the stable operation of the system and the service life of the filter.It is an important research direction to explore the dynamic law of pulse injection flow field and analyze the influence of pulse flow field on soot cleaning performance,so as to optimize the injection structure and injection parameters.In this paper,firstly,the dynamic process of pulse jet cleaning in the folded filter was numerically simulated.The dynamic relationship between pulse flow field and sidewall pressure was established.The formation mechanism of sidewall peak pressure,the evaluation index of pulse cleaning effect,was analyzed.The results show that the compression effect of the pulse flow is prior to the flow velocity on the same section,so the sidewall pressure first increases and then decreases with the injection time.At the same time,the vortex characteristics appear above the upper section of the filter cartridge.With the action of continuous compression and eddy current,the pressure on the upper sidewall of the filter increases to the peak value,which increases from 322 Pa to 1147 Pa along the axial direction.The pressure on the sidewall of the middle and lower part of the filter reaches the peak value under the continuous compression of the airflow,and the pressure distribution along the axis is gentle.In the lower part of the filter cartridge,the sidewall pressure increases to a higher secondary peak value due to the direct effect of the air flow on the sidewall after the primary peak value of the sidewall pressure is formed by the continuous compression of the air flow.Secondly,the unsteady process of pulse jet soot cleaning under different injection pressure,injection distance and filter length were simulated.The influence of pulse flow field structure on soot cleaning performance was studied.The results show that with the increase of injection pressure,the effect of airflow compression and eddy current diversion is enhanced,and the intensity of pulse cleaning is improved,but the uniformity of pulse cleaning is reduced.With the increase of injection distance,the peak value of sidewall pressure increases in the upper part of the filter cartridge and decreases in the middle and lower part of the filter cartridge,which improves the uniformity of pulse cleaning.When the injection pressure is smaller,the injection distance can be appropriately reduced to enhance the direct effect of the air flow in the lower part of the filter cartridge.When the injection pressure is larger,the injection distance can be appropriately increased to avoid the backflow of airflow at the bottom of the filter cartridge.The results show that there is an optimal size for the filter length parameter,the pulse cleaning intensity under the condition of L = 1000 mm is better than that under the two conditions of L = 800 mm and 1200 mm.Then,in view of the problem that the cleaning effect of the upper part of the filter cartridge was not significantly improved by changing the injection distance or injection pressure under the traditional pulse injection cleaning mode,the conical diffuser with an upper opening was designed and installed under the nozzle.Compared with the simulation results of cartridge filter with or without diffuser,the results show that the diffuser has a good distributary effect on the jet flow.The part of the airflow can directly act on the upper part of the cartridge filter,which makes the cleaning intensity of the upper part of the filter cartridge increase by 53%,and the non-uniformity of cleaning along the axis decreases from0.52 to 0.33.Finally,three kinds of diffusers with different tapers were processed and the experiment of a pulse soot cleaning system based on diffuser was carried out.The soot cleaning intensity and uniformity under different injection distances,diffuser installation height,and diffuser taper were analyzed.The results show that when the injection distance of 150 mm,the installation distance of 200 mm,the diffuser taper of 59°,the pulse cleaning effect is the best.The peak intensity of sidewall pressure is 921 Pa and its uniformity of cleaning is 0.16 with this condition.