Study On Combined Electrostatic Purification Device For Cooking Oil Fume Treatment

Vigorous development of catering industry makes people’s life more convenient in China.In addition,the problem of cooking fume pollution has become increasingly serious.This will increase the concentration of O₃,PM_2.5,etc.,and also cause air pollution problems such as smog.The national and local governments have successively released the emission limits of cooking fume.Various types of oil fume purification technologies have been developed for different components in cooking fume,among which the combined cooking fume purification technology containing static electricity is a hot spot at present.Therefore,the research on the combined electrostatic cooking fume purification technology can lay a foundation for the popularization of this technology.In this paper,aiming at the core module in the combined electrostatic purification technology,simulation and experiment are completed,whose results are used to adjust the parameters of the process,and the core module and main devices are designed.In this paper,COMSOL software was used to simulate the movement of catering oil droplets in the electrostatic region.In the two-dimensional model,the effects of voltage,speed and particle size on the deformation of single oil droplet and the coalescence of two oil droplets under the single electric field,flow field and coupling field were studied by using the flow field motion control equation and electric field control equation,and evaluated by deformation degree D and start coalescence time respectively.Under the effect of a single electric field or flow field,a single oil droplet presented unidirectional deformation.Under the action of coupling field,multi-directional deformation occurred,which was teardrop-shaped.Voltage,speed and particle size were all positively correlated with the deformation degree of oil droplets.As the voltage increased from 40 kV to 50 kV,the deformation degree of oil droplets rose from 0.8 to 1 under the electric field.Under the effect of the flow field,when the speed was 0.05 m/s,the deformation degree of oil droplets was 0.33.As the speed accelerated to0.15 m/s,the deformation degree went up to 0.83.The oil droplets increased from 1.2 mm to 2 mm,and the deformation degree of oil droplets increased from 0.5 to 0.75.The two oil droplets showed multi-directional deformation under a single electric field,and the coalescence probability was higher than that under a single flow field.Under the coupling field,properly increasing the voltage,speed and particle size was beneficial to accelerate the start coalescence time of oil droplets.When the speed exceeded 0.5 m/s,the residence time of oil droplets in the electrostatic region was less than 0.005 s,and effective coalescence cannot be realized.When the particle size of oil droplets was larger than 1.5 mm,the applied force of electric field was too scattered,and the coalescence time of oil droplets was stable at 0.015 s,with little change.Response surface method was applied in the paper to adjust the parameters of two oil droplets coalescence.The best result was as follows:when the particle size was 1.56 mm,the voltage was 12 kV,and the speed was 180 mm/ms,the shortest coalescence time was 16.8253 ms.Through matrix analysis,it was concluded that the importance of influencing factors was speed>voltage>particle size.In this paper,the influence of voltage,flow rate and electric field on cooking fume purification efficiency was studied on the self-designed electrostatic purification device.Under a single electric field,when the voltage increased from 0 kV to 15 kV,the purification efficiency increased from 8.7%to 76.3%.The purification efficiency then was basically stable,and brown smoke appeared on the plate.The purification effect of two electric fields was better than that of a single electric field.When the two voltages increased to 17 kV at the same time,the purification efficiency reached 89.2%and tended to be stable.When one voltage was constant at 5 kV and the other voltage was adjusted to 20 kV,the purification efficiency was stable at 84.1%.Increasing the flow rate would reduce the residence time of air flow in the electric field.When the flow rate increased from 1.5 L/min to 3.5 L/min,the purification efficiency decreased from 85.6%to 56.6%.A combined oil fume purification process of filtration+static electricity+adsorption was designed in the paper,and the filtration device and static electricity device were integrated.Baffle filter device was adopted,with baffle blade spacing of 15 mm and the number of folded plates was 6.Based on the simulation and experimental results,a combination of DC and AC electrostatic devices was selected in the electrostatic module.The single board area of polar plates in the electric field was 0.078 m².The material was stainless steel plates,which requires a total of 23 plates.86 dust collecting plates were needed.The adsorption module used an annular adsorption device.The required amount of molecular sieve adsorbent was 105.47 kg.The bottom area of the annular adsorption area was 0.434 m² and the height was 0.516 m.The inner diameter of adsorption tower was 0.97 m and the total height was 1.5 m.The simulation and experimental test results obtained in this paper,as well as the designed process device,provide a basis for developing a new type of combined electrostatic fume purification technology.