Device and method for enhancing heat and mass transfer of sludge superheated steam drying

Abstract

The invention relates to a heat and mass transfer enhancement device and method for sludge superheated steam drying. The device enhances heat and mass transfer in the sludge superheated steam drying process by improving the internal and external heat and mass transfer conditions of sludge, and is suitable for high water content sludge dry. Its characteristics are: the direction of the helix is ​​staggered by 45° on a single shaft, and the directions of the helical blades are clockwise and counterclockwise. The top edge of the counterclockwise helical blade is high. The device increases the gap between sludge during sludge movement, improves the two-phase flow of sludge and superheated steam, and then strengthens the contact efficiency between sludge and superheated steam, improves the external heat and mass transfer of sludge, and mixes sludge with different moisture content , form a higher temperature difference and humidity difference between the sludge, and enhance the internal heat and mass transfer of the sludge. The device strengthens internal and external heat and mass transfer during the drying process, speeds up the drying process, improves drying quality, and improves drying efficiency and energy utilization.

Description

Technical field [0001] The invention belongs to the field of sludge drying, and relates to a sludge drying heat and mass transfer enhancement device and method, in particular to a sludge drying heat and mass transfer enhancement device and method using superheated steam as a drying medium. Background technique [0002] With the increase of urban population, the amount of urban sewage treatment is also greatly increased, and the output of sludge is also increasing year by year. The sludge contains many kinds of harmful substances. If it cannot be effectively treated, it will cause great damage to the environment. Destruction. Moreover, untreated sludge emits odor, which directly affects human health and has carcinogenic effects. Therefore, the treatment of sludge faces severe forms. [0003] The sludge is a kind of high water content. The water content of the sludge produced by general sewage treatment plants is above 95%. After being concentrated, the water content is still above ...

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Problems solved by technology

However, this device only increases the heating area to enhance heat exchange, and improves the utilization rate of heat energy by setting an insulating layer between the inner and outer shells, without changing the movement state of the sludge and the internal mass and heat transfer of the sludge, and the drying rate of the sludge is low.

[0009] Chinese patent CN 205138138 U discloses a spiral propulsion type continuous drying device, which uses dispersing blades and helical blades to make the materials fully contact with the drying medium during the process of breaking up and raising, and the device strengthens the breaking up of sludge To achieve the purpose of enhancing heat exchange, but it does not improve the movement state of the drying medium and the mass and heat transfer of the sludge boundary layer, and the heat of the drying medium is not fully used

[0010] Chinese patent CN 103693838 A discloses a sludge drying device and method. The device is set through a sleeve connected to two cavities, and the sludge and the drying medium are respectively spirally moved in their respective cavities to increase the amount of sludge. The heat exchange efficiency with the drying medium, but this device only prolongs the movement time between the sludge and the drying medium, and does not change the movement effect of the sludge and the heat transfer inside the sludge, and the sludge is prone to uneven heating

[0011] For the drying of sludge with high moisture content, the current drying device does not have enough two-phase flow between sludge and superheated steam, and the sludge is easy to stick together, and the contact with superheated steam is not sufficient, which affects the mass and heat transfer of the boundary layer, and adjacent The temperature difference and concentration difference between the sludge are not high, which affects the mass and heat transfer inside the sludge, resulting in poor heat and mass transfer effect of the drying medium, which not only affects the drying rate, but also affects the drying effect, and the drying degree of the dried sludge uneven

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