How to solve the heat exchange problem of disperse dye coupling reaction
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In the production of disperse dyes, the coupling reaction generally uses ice to control the reaction temperature. However, the problem is that the amount of wastewater is large, and the energy consumption of evaporative desalination during wastewater pretreatment is too high. Using the external circulation heat exchange method, the tube heat exchanger is easy to block and needs to be cleaned frequently, which affects the efficiency of the device. If the coil in the kettle is used for heat exchange, multi-layer coils need to be installed due to the large heat exchange area, which will also affect the mixing effect. Does anyone have any good plans?
Using the external circulation heat exchange method, the tube heat exchanger is prone to blockage. Analyze why it is blocked and see how to solve it appropriately. The method of directly throwing ice cubes into the material to cool down has basically been eliminated.
This is diazotization, and more optimization measures can definitely be made in the process. However, safety risks must also be considered in the process. Although adding ice is rough, there is a lot of water. However, too much water with high specific heat will help the reaction heat to be uniform and stable.
Is it possible to consider using vertical heat exchange plates to transfer heat in the reactor? Of course, the form of the mixer must also be adjusted accordingly.
The new project was changed to external circulation heat exchange, and there are two main reasons for the blockage.: 1. There is sodium sulfate in the system. At low temperature, the solubility of sodium sulfate is only 6g, and it will crystallize (with crystal water) and precipitate out. ； 2. The dye is insoluble in water. The solid content and viscosity of the slurry are relatively large during the middle and late stages of the reaction, and the tubes will be blocked together with sodium sulfate.
It is equivalent to reacting and producing products at the same time. At the same time, sodium sulfate is also precipitated. If the external circulation is used without a pump, it will definitely be easily blocked. Even if a pump is added, the location of the liquid must be considered to avoid a large amount of crystallization entering the heat exchanger. The internal coil method is a good solution. You can consider using a fluoroplastic heat exchanger, which does not require hard connections, and adding a vibrating hammer to vibrate the material on the tube wall.
This heat exchange area is large, but does it affect mass transfer?