1. Differences between Operating Temperature and Operating Pressure

Conventional evaporation generally operates under normal pressure or slight negative pressure, with a relatively high evaporation temperature, usually above 80°C, close to the boiling point of water, and belongs to high-temperature evaporation.

Low-temperature evaporation relies on a high degree of vacuum to lower the boiling point of materials, enabling evaporation in the range of 30–60°C. It is a low-temperature, gentle evaporation method aimed at protecting heat-sensitive materials.

MVR evaporation typically operates under medium to high vacuum, with evaporation temperatures generally ranging from 60–90°C. It can also achieve low-temperature operation by increasing the vacuum, resulting in a more flexible temperature range.

2. Differences in Heat Sources and Energy Efficiency

Conventional evaporation relies entirely on external fresh steam or hot water as the heat source. The generated secondary steam is directly condensed and discarded, leading to low heat utilization efficiency and the highest energy consumption.

Low-temperature evaporation also requires external heat sources, but at a lower heating temperature. It can utilize waste heat or residual heat, but does not change the way energy is utilized itself, resulting in moderate energy efficiency.

MVR evaporation does not rely on large amounts of fresh steam. Instead, it recycles the secondary steam generated by the system by compressing it to increase temperature and pressure, then reuses it as the heating source. This results in extremely high energy recycling efficiency, making it the most energy-efficient and cost-effective option among the three in terms of operation.

3. Differences in System Structure and Equipment Composition

Conventional evaporation has the simplest structure, mainly consisting of an evaporator, separator, and condenser, with low investment and easy maintenance.

Low-temperature evaporation must be equipped with a vacuum pump system to maintain high vacuum. It also has higher requirements for tightness, insulation, and heat exchange area, making the equipment more complex than conventional evaporation.

MVR evaporation adds modules such as a steam compressor, anti-surge devices, and intelligent control to the evaporation system. The system is the most complex with the highest equipment investment, but it is more economical in long-term operation.

4. Differences in Applicable Materials and Scenarios

Conventional evaporation is suitable for heat-resistant, non-perishable, and low-cost materials, such as inorganic salts and ordinary wastewater.

Low-temperature evaporation is preferred for heat-sensitive materials, such as food, traditional Chinese medicine, biological products, and fine chemicals, in scenarios where high-temperature heating is not allowed.

MVR evaporation is suitable for large-scale, continuous operations with high evaporation capacity, such as industrial wastewater concentration, seawater desalination, and chemical liquid concentration, particularly in projects with high energy-saving requirements.

5. Differences in Control and Operational Characteristics

Conventional evaporation has simple controls, mainly manual or basic automatic control. It operates stably but is not energy-efficient.

Low-temperature evaporation focuses on controlling vacuum degree, temperature, and liquid level to ensure stable evaporation temperature and avoid thermal damage to materials.

MVR evaporation has the highest requirements for intelligent control. It needs to precisely adjust compressor load, steam pressure, heat transfer temperature difference, prevent liquid hammer, and prevent surge to achieve fully automatic and efficient operation.

6. Summary of the Relationships Between the Three

Conventional evaporation is the basic form, characterized by high energy consumption, high temperature, and simple structure.

Low-temperature evaporation centers on temperature and vacuum, emphasizing material protection.

MVR evaporation centers on energy recycling, emphasizing energy conservation.

The three are not completely mutually exclusive. MVR can also be combined with low temperature to form low-temperature MVR evaporation, achieving both low-temperature, heat-sensitive material protection and high energy efficiency.