Pre-treatment by MVR
The pretreatment stage is the softening of industrial wastewater, usually by the mannite-lime flue gas method, which removes a large number of cations from the wastewater, thus reducing the amount of fouling in the industrial wastewater.
In the pre-treatment softening system, lime milk and mannitol are added and the industrial wastewater is centrifuged in a centrifuge, after which the dissolved solution is treated by an MVR system.
In this process, the pH value is adjusted according to the requirements of the MVR system and the way the wastewater is treated. The impurities contained in the wastewater are treated by flue gas, and these magazines are removed by precipitation and then filtered by ceramic membranes.
The suspended matter in the industrial wastewater is reduced significantly, usually by no more than 0.001%.
After pretreatment, the calcium ions and precipitates in the wastewater are reduced, and the MVR evaporation process is used to treat the various salts contained in the wastewater, such as sodium chloride, to avoid scaling problems in the entire system.
Evaporation and crystallization
This stage is the use of MVR system for crystallization. In the process, the wastewater is fed into the conditioning tank of the MVR and scale inhibitors are added to slow down the scaling in the heat exchange tubes.
A deaerator is used to separate the non-condensable gas to improve the efficiency of steam heat exchange and increase the conversion rate.
The MVR system can evaporate more than 80% of the water. In this process, a centrifugal compressor and a three-effect mixed-flow forced circulation evaporator can be used to achieve secondary steam.
The application of mixed-flow system can continuously improve the efficiency of evaporation, while reducing the cost of investment and other energy applications.
Centrifugal drying
Centrifugal drying is mainly accomplished by centrifugation, drying and packaging.
After centrifugation, the water content of the material is about 5%, and the water content is too high, so the material is heated by steam heat exchanger and then dried. The temperature of the dryer is controlled at 140°C.
After the wet material is dried, crystalline salt is formed.
The MVR system can not only complete the treatment of industrial wastewater, but also enable the extraction of crystalline salts contained in industrial wastewater, which greatly improves the efficiency of resource utilization.