| Under the background of atmospheric pollution is seriously,emission standard of air pollutants is more and more strict,the long bag pulse-jet bag filters has the ability to adapted to the new standards. We need to give furer research on the cleaning progress and filtration progress when the bag house is becoming more and more large. It is hard to test the complicated solid two phase flow but numerical simulation method can get the process of pulse-jet and airflow of cleaning process and they can proved some rule to improve the equipment.Cleaning effect is one of the important factors affecting the equipment work properly and the airflow distribution in the middle house play a key role in affecting the service life of bag house. Geometry model and structured grids are built by ICEM software using a 1:1 scale. The pressure distribution in the cleaning progress and the airflow distribution in the filtration progress are simulated and analysed by using FLUENT software.The cleaning process has been testified through comparing the simulation results and the experimental date. That the venturis, injection pressure and the length of filter bag how to effect the maximum peak pressure on the surface of filter bag is simulated. The result show that venturis had a greater influence on the peak pressure of filter bag,the maximum peak pressure reduce from 16.9kPa to 15.7kPa by 7%,and the position of maximum pressure is receded by 0.5m,the middle and bottom pressure of filter bag drop from 7.5 kPa to 5.4kPa by 28%. The injection pressure also has a big influence on the maximum peak pressure of the filter bag surface,the maximum pressure is 18.5kPa and the downstream is 8kPa when the injection pressure is 0.35 MPa while the maximum pressure is 13.7kPa and the downstream is 3.8kPa when the injection pressure is 0.2MPa without venturis. The maximum pressure and downstream pressue reduced by 26% and 53%. Different length of filter bag have the same pressure distribution within the scope of 1 m. The different is seriously in the middle and bottom of filter bag. When the length of filter bag increase from 6m to 9m,the peak pressure of filter bag bottom reduce from 8kPa to 2 kPa.The airflow filed of bag house is simulated after extended the YTALS-03-60 filter bag form 6 m to 8 m. The simulation result show that the airflow field distribution is nonuniform and the flow distribution before and after cleaning of A and B row is 1.42、1.14 and 1.21、1.62, maximum flow uneven amplitude is 0.61、0.75. Velocity around near wall is lager than the center,and near the inlet is larger than the zone away from the inlet,the airflow from the intake has a directly effect on the bottom of filter bag. The simulation was executed again after added the baffle plate in the bag house, the result show that the airflow distribution is better than the original model when the height of baffle plate is 1m or 2m,and the maximum flow uneven amplitude is 0.47、0.57 and 0.52、0.78. The effect from the intake airflow on the bottom of filter bag is disappeared,but the eddy down of air intake go against the dust falling. Changing the horizontal size of baffle plate,when the height is 3m,flow uneven amplitude is 0.37、0.35,and reach the minimum. All of the filter bag can meet the requirements except the A row before cleaning and P row after cleaning;the eddy down of the air intake is disappeared when the connection of ash bucket and middle house;the size of baffle plane has great effect on the airflow field which has considerable improvement. |
PDF Full Text Request