1. Principle of special hollow blade dryer for sludge drying:
Drying is to remove the moisture in the sludge and increase the calorific value of the sludge. The removal of moisture has to go through two main processes. (1) Evaporation process: water vaporization on the surface of the material, because the water vapor pressure on the surface of the material is lower than the medium (gas) The water vapor is divided and the moisture enters the medium from the surface of the material.
(2) Diffusion process: It is a mass transfer process closely related to vaporization. When the surface moisture of the material is evaporated, the surface moisture of the material is lower than the internal humidity of the material. At this time, the driving force of heat is required to transfer the moisture from the inside to the surface.
The continuous alternating of the above two processes basically reflects the mechanism of drying.
The drying method of sludge drying can be divided into direct drying and indirect drying. Different heating forms determine different types of drying processes. Direct drying is to introduce high-temperature flue gas directly into the dryer. The heat is exchanged between the gas and the wet material, and the direct drying will increase the polluting gas. The representative equipment has a fluidized bed dryer; the indirect drying is to transfer the heat of the high temperature flue gas to the heat medium (heat transfer oil or steam) through the heat exchanger, and the heat medium circulates in a closed loop without contact with the sludge. Indirect drying has a certain heat loss, but the amount of smoke that needs to be treated is small and does not cause secondary pollution. The representative equipment has a paddle dryer.
2. Drying process of hollow blade dryer:
2.1 Equipment structure and working principle
The hollow blade dryer is a kind of heat conduction drying equipment, which is one of the core equipments for sludge drying. It is mainly composed of hot shaft, fuselage, end plate, upper cover and transmission system. The blade dryer uses heat transfer oil. Or water vapor as the heat medium, the hollow hot shaft and the hollow jacket of the paddle dryer are all connected to the heat medium during operation, and the wet material is heated and dried through the metal wall, and the wet material is stirred under the reverse rotation of the hollow hot shaft. Gradually move to the discharge port. After the drying requirement is reached, it is discharged from the tail of the blade dryer. The evaporated water is carried away by a carrier gas such as air and washed and condensed.
2.2 Dry gas system:
The drying gas generated by the drying process of the dryer is carried by the carrier gas to the scrubbing tower. In the scrubbing tower, the drying gas is brought into contact with a large amount of condensed water sprayed and rapidly cooled, and the water vapor in the drying gas is condensed while the particulate dust is removed and removed. The carrier gas of water vapor and particulate dust is discharged from the scrubber. Under the action of the exhaust fan, the non-condensable gas enters the incinerator for disposal, and the remaining carrier gas enters the dryer cycle. The washing tower effluent enters the raw water tank of the sewage treatment plant.
2.2 Technical Features of Hollow Blade Dryer (1) Stirring is uniform, the drying effect is good, and the agitation of the sludge by the paddle makes the sludge heat evenly, evenly dried, and has a high heat transfer coefficient.
(2) The hot shafts can be meshed with each other and have a self-cleaning effect, which can prevent the sludge from sticking to the wall (2), and the dust entrainment is small and the loss is small.
(4) Low energy consumption and low operating costs. The drying efficiency of the blade is up to 90%.
Sunflower Kernel From Inner Mongolia
Sunflower Kernel From Inner Mongolia,Dry Roasted Sunflower Kernels,Unsalted Sunflower Kernels,Salted Sunflower Kernels
Wuyuan county dafeng oil food co.,ltd , https://www.sundafengfoods.com