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Process principle of low-temperature evaporation concentrator
Date: 2025-04-23Read: 4
Low temperature evaporation concentrator is mainly used for industrial wastewater (such as cutting fluid, electroplating wastewater), high salt waste liquid, biopharmaceutical feed liquid and other concentration scenarios that require low-temperature treatment to avoid the decomposition of thermosensitive substances. Today, the editor will take you to understand the process principle of low-temperature evaporation concentrator.
1、 Core principle
1. Vacuum depressurization reduces boiling point
By using a vacuum pump to extract air inside the evaporator, the system pressure is reduced to 0.03-0.08 MPa, and the boiling point of the liquid significantly decreases with the decrease in pressure. For example, the boiling point of water can drop to 30-40 ℃ (standard atmospheric pressure is 100 ℃).
2. Low temperature evaporation and thermal energy cycle
In a low-pressure environment, the solution evaporates within the range of 35-50 ℃, combined with heat pumps or mechanical vapor recompression (MVR) technology to recover latent heat of steam, forming a closed thermal energy cycle system. For example, the MVR evaporator increases enthalpy by compressing secondary steam, which is repeatedly used to heat the original solution.
2、 Process flow
1. Preheating stage
After the original liquid reaches the set liquid level, the vacuum pump starts to create a negative pressure environment, and the evaporator automatically receives water.
The compressor/heat pump starts working, heating the wastewater to 30-35 ℃ to trigger initial evaporation.
2. Evaporation and concentration stage
The evaporation temperature is controlled at 35-40 ℃, and the refrigerant achieves synchronous heating and cooling through a compression expansion cycle
Heating side: compressing the refrigerant to release heat and maintain the boiling state of wastewater;
Refrigeration side: The expanding refrigerant absorbs the heat of steam, causing it to condense and liquefy.
The sensor monitors the evaporation status in real time and automatically injects defoamer to prevent foam interference.
3. Steam treatment and concentrated liquid discharge
The evaporated secondary steam is cooled into distilled water by the condenser and enters the water storage tank;
After the concentrated solution reaches the preset concentration, the pneumatic valve opens and is transported to the concentration tank for storage under pressure.
3、 Key technical features
1. Vacuum system
Using a vacuum pump to maintain a stable low-pressure environment, ensuring that the boiling point remains below the conventional value and reducing thermal energy consumption.
2. Thermal energy cycle design
Heat pump type: The refrigerant cycle achieves heat self-sufficiency without the need for external steam, and the energy efficiency is improved by more than 50% compared to traditional evaporation technology;
MVR type: After the secondary steam is pressurized and heated by the compressor, it is reused, and the water consumption per ton is only 1/4-1/5 of that of traditional evaporators.
3. Fully automatic control
By integrating liquid level, temperature, and pressure sensors through a PLC system, unmanned operation can be achieved, and the cycle time can be flexibly set.
