Mechanical Vapor Recompression Evaporator

MVR is the abbreviation for “Mechanical Vapor Recompression”. Therefore, an MVR evaporator is also known as an MVR mechanical compression evaporator, fully named as Mechanical Vapor Recompression Evaporator. The basic principle of an MVR evaporator is to recover and mechanically recompress the waste heat steam generated during the evaporation process, improving the cleanliness and enthalpy of the waste heat steam for reuse, thus achieving the goals of energy conservation and environmental protection.

The MVR evaporator is a new type of high-efficiency energy-saving evaporation equipment in the pharmaceutical industry. It adopts low-temperature and low-pressure steam technology and clean new energy – electric energy – to generate steam, separating moisture from the medium. As the most advanced evaporation technology internationally, it serves as an upgraded replacement for traditional evaporators. Main types of MVR evaporators include:

The MVR evaporator differs from ordinary single-effect falling film or multi-effect falling film evaporators. As a single-unit evaporator, it integrates the functions of multi-effect falling film evaporators. Depending on the required product concentration, it adopts segmented evaporation. That is, if the product cannot reach the required concentration after the first pass through the effect body, it is pumped from the lower part of the effect body to the upper part through external pipelines by a vacuum pump, repeating the passage through the effect body until the target concentration is achieved.

Inside the effect body are arranged fine tubes. The product flows through the tube interior, while steam surrounds the tubes. As the product flows downward, the increased inner tube area causes it to flow in a film shape, maximizing the heat transfer area. A vacuum pump creates negative pressure within the effect body, lowering the boiling point of water in the product for concentration. The evaporation temperature of the product is approximately 60°C.

After the product is heated and evaporated in the effect body, the generated condensed water, partial steam, and residual steam from heating are separated by a separator. The condensed water flows out from the lower part of the separator to preheat the incoming product, while the steam is pressurized by a fan supercharger (higher steam pressure corresponds to higher temperature). The pressurized steam then converges with primary steam and re-enters the effect body through pipelines.

During startup, a portion of steam is required for preheating. After normal operation, steam consumption is significantly reduced. As the fan supercharger pressurizes the secondary steam, electrical energy is converted into steam thermal energy, leading to reduced steam demand but increased power consumption during operation.

Throughout the product’s flow in the effect body, the temperature remains around 60°C, and the temperature difference between the heating steam and the product is maintained at approximately 5–8°C. A smaller temperature difference between the product and the heating medium is more conducive to preserving product quality and effectively preventing tube fouling.

When the required concentration is around 50%, the MVR evaporator alone can complete the task. For a target concentration of 60%, a flash evaporation device needs to be installed.