1、 Equipment preparation and startup
1. Raw liquid injection and system pre inspection
Check if key components such as evaporator, vacuum pump, condenser are in normal condition.
After the original liquid is injected to the set liquid level, start the inlet pump and trigger the automatic inlet program.
2、 Establishment of vacuum environment
1. Activate the vacuum system
Turn on the vacuum pump to reduce the internal pressure of the evaporator to 0.03-0.08 MPa (corresponding to a vacuum degree of about 33-80 mbar), and lower the boiling point of the solution to 30-40 ℃.
Continuously monitor the vacuum level to ensure stable system pressure and avoid the accumulation of non condensable gases that may affect evaporation efficiency.
3、 Preheating and evaporation process
1. Heating and temperature control
Start the compressor or heat pump system, release heat through refrigerant compression, and heat the wastewater to 30-35 ℃ to trigger initial evaporation.
The evaporation temperature is controlled at 35-40 ℃, and the refrigerant circulation (compression heating expansion refrigeration) is adjusted in real time through sensors to maintain a stable boiling state.
2. Defoaming treatment
If foam is generated during evaporation, the sensor will automatically trigger the injection of defoamer to prevent foam from interfering with steam condensation.
4、 Crystallization control and separation
1. Crystallization condition adjustment
In a vacuum environment, the solution is rapidly cooled to 30-35 ℃ by flash evaporation, promoting solute supersaturation and crystallization.
Use mechanical scraper or stirring device to continuously clean the inner wall of the evaporator to prevent crystallization from adhering and scaling.
2. Crystallization endpoint determination
Monitor the concentration of the concentrated solution through a density meter or conductivity meter, and stop evaporation after reaching the preset value.
5、 Steam condensation and product collection
1. Steam treatment
The evaporated secondary steam enters the condenser and liquefies through the circulation of cooling water or refrigerant, generating distilled water and storing it.
2. Concentrated solution and crystal discharge
The concentrated liquid is discharged into the storage tank through a pneumatic valve, and the crystalline solid is collected by centrifugal separation or filtration device.
6、 System shutdown and maintenance
1. Shutdown operation
Close the compressor, vacuum pump, and feed valve in sequence, and drain the residual liquid.
Use clean water or cleaning agents to cycle and rinse the evaporator and pipelines to prevent blockage caused by residual crystallization.
2. Daily maintenance
Regularly check the oil level, refrigerant pressure, and sensor accuracy of the vacuum pump to ensure long-term stable operation of the equipment.
Through the above steps, the vacuum low-temperature crystallization evaporator can achieve efficient and low-energy concentration and crystallization treatment, suitable for scenarios such as thermosensitive materials and high salt wastewater.