Study On Internal Structure Optimization Of Drying Chamber Of Sludge Drying Equipment

The low temperature drying of sludge adopts the principle of reverse Carnot cycle.Under the relatively low temperature condition(40℃～65℃),the core technology of humidity gradient and mass transfer is used to realize the continuous closed dehydration of sludge.Compared with the traditional heat drying,it is efficient and energy-saving,easy to operate and does not need additional waste gas and dust treatment.The heat and energy of drying process can be recycled,and the condensed water can be reused locally.At present,there is a problem of uneven distribution of velocity field in the drying room of sludge drying equipment.By changing the internal structure of the drying room,the uniformity of velocity field in the drying room can be improved to improve drying efficiency,reduce drying time and improve drying effect.Through the numerical simulation of the original oven,it is concluded that the middle and lower part of the oven has a higher velocity,while the upper part of the oven has a lower overall velocity due to the blocking effect of the conveyor belt.The outlet speed of the fan and return fan is larger,especially in the middle area of the upper part of the fan and the third layer of the net belt,the middle speed is larger,the speed on both sides is smaller,and the speed distribution is very uneven.The air outlet of the blower at the bottom of the drying room is blocked by the conveyor belt and the walls on both sides of the left and right sides,and the air flow gradually flows upward,converging to the return air outlet,presenting a region with a large speed.At the same time,eddy current region appears at the edge of the inner wall of the drying room.By comparing the velocity cloud before and after the position change of the blower,it was found that the mode of air flow through the condenser and out from the bottom side of the dryer was significantly better than the mode of air supply from the blower placed at the bottom of the dryer when the blower was placed in the heat pump part of the lowtemperature closed cycle sludge drying equipment with the air outlet facing down.When the spacing of the second and third layers of mesh belt increases from 210 mm to 250 mm,it is concluded that when the spacing of the second and third layers of mesh belt is 240 mm,the overall air distribution in the oven is the best.Through comparative analysis of 9combined working conditions of mesh belt aperture size,it is concluded that when the aperture size of the first and second layer mesh belt is 2mm*2mm,and the aperture size of the third layer mesh belt is 1.5mm*1.5mm,the air distribution in the oven reaches the best state.Through the analysis of three factors affecting the internal structure of the dryer,such as the position of the fan,the spacing of the mesh belt layer and the aperture size of the nylon mesh belt,it is concluded that the air distribution in the dryer has the greatest influence on the spacing of the mesh belt layer,followed by the aperture size of the nylon mesh belt,and the position of the fan has the least influence.After the calculation of 18 working conditions were set,the optimal combination parameters were obtained,namely,the spacing of mesh belt layer was 240 mm,the aperture size of the first and second layers of mesh belt was 3mm*3mm,and the aperture size of the third layer of mesh belt was1.5mm*1.5mm.After the adjustment of the fan position,the air distribution in the drying room was the best.