1. Vacuum Evaporation Process

Brine treatment  →  Preheating  →  Multiple-effect evaporation  →  Evaporative crystallization  →  Salt slurry separation  →  Centrifugal dewatering  →  Drying and packaging

Within the evaporator, steam heats the brine and converts water into secondary vapour. As the NaCl concentration continues to rise, salt crystals precipitate once the solution reaches the required level of saturation.

2. Role of Vacuum Pumps in Saltworks Evaporation Systems

2.1 Reducing the Boiling Point and Improving Evaporation Efficiency

At atmospheric pressure, water boils at 100 °C. A liquid ring vacuum pump reduces the operating pressure and, in turn, lowers the boiling point. This allows brine to evaporate at a lower temperature, reducing steam demand and improving heat utilisation.

2.2 Removing Non-condensable Gases

Non-condensable gases may enter a vacuum-evaporation system and impair heat transfer. This can compromise the purity of precipitated salt crystals and reduce product quality. A liquid ring vacuum pump removes air and other non-condensable gases from the evaporator, stabilises evaporation pressure, and maintains heat-exchanger performance.

2.3 Controlling Salt Crystal Formation

Vacuum level affects the overall evaporation rate, salt-solution concentration, and crystal growth rate. A stable vacuum supports the formation of salt crystals with a uniform particle size and consistent quality, suitable for high-purity industrial salt and food-grade salt.

3. Vacuum Pump Solutions for Saltworks

We select vacuum pumps according to plant capacity and operating requirements. Small- and medium-sized saltworks commonly use 2BV/2BE-series liquid ring vacuum pumps; a single pump will often meet the required duty. An ultimate pressure of 3,300 Pa is generally sufficient to maintain vacuum conditions in the evaporator. These pumps feature a simple design, easy maintenance, and suitability for continuous operation.

Larger saltworks more commonly use a Roots vacuum pump and liquid ring vacuum pump package. Recirculating the service liquid helps avoid unnecessary waste while the combined system provides a higher vacuum level and greater pumping capacity. For large saltworks, improved efficiency and reduced resource consumption directly strengthen market competitiveness.

4. Summary

During vacuum evaporation in saltworks, a vacuum pump is not used to convey brine. Its role is to create and maintain the negative-pressure environment inside the evaporator. By lowering the boiling point of water, it improves brine evaporation efficiency and removes non-condensable gases to ensure stable precipitation of salt crystals.

For saltworks, liquid ring vacuum pumps remain the most mature and reliable choice. Large-scale vacuum salt-production projects more commonly employ combined Roots-pump and liquid-ring-vacuum-pump systems. If your saltworks requires a vacuum solution, please contact FORYOU.