The core principle of industrial wastewater treatment using a low-temperature evaporator is to reduce the boiling point of water by creating a vacuum negative pressure environment, and to achieve water evaporation-condensation recovery through low-temperature heating, ultimately completing the combined process of solid-liquid separation and wastewater resource recovery. Its core advantage lies in achieving wastewater reduction with low energy consumption, while avoiding the damage of high temperatures to heat-sensitive substances. It is suitable for various challenging industrial wastewater treatment scenarios and is one of the key technologies for efficiently treating high-salt and high-COD wastewater in the current environmental protection field.

The construction of a vacuum negative pressure environment is the foundation of the entire process and the core prerequisite for achieving "low-temperature" evaporation. Under normal pressure, the boiling point of water is 100℃. However, a low-temperature evaporator continuously extracts air from a sealed processing chamber through a professional vacuum pump, creating a stable negative pressure environment (typically corresponding to an absolute pressure of 5-50kPa). According to the physical correlation between atmospheric pressure and boiling point, the lower the atmospheric pressure, the lower the boiling point of the liquid. Under this negative pressure condition, the boiling point of water can be significantly reduced from 100℃ to a range of 30-60℃. This core breakthrough allows for rapid evaporation of water without the need for high-temperature heating, thereby reducing energy consumption at its source.

The low-temperature heating and evaporation process operates in a negative pressure environment, completing the initial separation of water and impurities. The system provides the latent heat required for evaporation of wastewater through heat pumps, electric heating, or auxiliary heating with a small amount of steam. Since the boiling point of water has been reduced to the low-temperature range, only a small amount of energy is required to boil and vaporize the water in the wastewater, forming water vapor. However, non-volatile impurities such as salts, heavy metals, and high-concentration organic pollutants contained in the wastewater have boiling points much higher than that of water (most salts have boiling points exceeding 1000°C), and cannot evaporate with the water vapor. They are firmly trapped in the original liquid and gradually form a high-concentration concentrated liquid. If the equipment is equipped with a crystallization module, the concentrated liquid will further evaporate and crystallize, transforming into solid crystalline salts.

Steam condensation recovery is a crucial step in the resource recovery of water. The water vapor generated by evaporation enters the condenser (mainly shell-and-tube or plate heat exchangers) through a closed pipeline. The condenser cools the water vapor through a cooling water circulation or heat pump refrigeration system, causing it to rapidly release latent heat and condense back into liquid water, which meets the standards of distilled water. After testing, this distilled water has significantly lower indicators such as COD and salinity compared to the original wastewater, and can be directly reused in enterprise production cleaning, equipment cooling, green irrigation, and other aspects, achieving water resource recycling and reducing the procurement cost of tap water for enterprises.

The concentrated solution/crystallized salt discharge process completes the closed-loop of wastewater reduction. When the concentrated solution reaches the preset concentration threshold, the equipment initiates the slag discharge procedure through the PLC automatic control system, discharging the concentrated solution into a dedicated storage tank. If it is crystallized salt, the solid salt is discharged through a screw conveyor or scraper device, and subsequent treatment can be carried out according to the properties of the salt - non-hazardous waste salt can be recycled after meeting the standards through testing, while hazardous waste salt is handed over to qualified units for compliant disposal, significantly reducing the volume and cost of hazardous waste disposal for enterprises.

It should be added that the efficient implementation of this principle requires two prerequisites: first, the system vacuum degree must be stable. If there are issues such as aging seals or pipeline leaks, it will lead to a rise in boiling point and a surge in energy consumption; second, proper wastewater pretreatment is necessary. If the wastewater contains high concentrations of calcium, magnesium, sulfate, and other components prone to scaling, softening or scale inhibition treatment should be carried out in advance to avoid blocking the heating tubes and affecting evaporation efficiency. Based on this core principle, low-temperature evaporators reduce energy consumption by 30%-50% compared to traditional high-temperature evaporators, and can also reduce odor and VOCs volatilization, making them the preferred solution for wastewater treatment in small and medium-sized enterprises.