Mechanical Vapor Recompression
- Process wastewater is fed by the feed pump through the feedstock heat exchanger and into the circulating stream. The feedstock heat exchanger is used to heat the wastewater by transferring sensible heat from the hot condensate to the cooler feed.
- The recirculation pump circulates wastewater from the separation tank through the main heat exchanger, to the orifice plate, and back into the separation tank. The latent heat from the compressed vapor is transferred to the wastewater via the main heat exchanger.
- An orifice plate is used to reduce the pressure of the circulating stream. The downstream pressure is low enough to allow flashing of the circulating stream into liquid and vapor components.
- The liquid and vapor then flow to the separation tank where they are separated. The liquid steam exits the tank at the bottom and flows back to the recirculation pump. The vapor stream exits the tank at the top and flows to the roots type PD blower.
- A mist pad is provided at the top of the separation tank to remove small droplets of liquid from the vapor.
- The roots type PD blower compresses the vapor (raising the temperature and pressure), and sends the vapor to the main heat exchanger, where it transfers its latent heat to the wastewater in the recirculation loop.
- High temperature condensate exits the main heat exchanger and flows to the condensate tank, where any remaining vaporis separated. The hot condensate is then pumped to the feedstock heat exchanger, where it transfers sensible heat to the incoming feed wastewater.
- Upon reaching steady-state at the target concentration, the concentrated wastewater is purged from the recirculation loop, using the residue valve. Depending on the energy balance, energy can be added to the system by electric heaters / process steam or excess energy can be removed from the system by the steam relief valve.
2.0 MVR Technical Principles
Mechanical Vapor Recompression (MVR) is a proven energy-saving evaporative concentration technology, which uses low-value waste steam and heat:
MVR Thermodynamic Cycle
- MVR’s theoretical basis is Boyle’s law
- From the physics it is known for a gas that Pressure * Volume / Temperature is constant (PV/T=K)—which means that during compression as the volume of gas decreases, the pressure and the temperature increase. From this, energy can be reused.
- According to this principle, the energy normally lost in the compression is recovered, leading to a highly-efficient evaporation process.
- Since this compression is realized by a simple mechanical compressor, the process is called MVR.
MVR Process Diagram
3.0 MVR Technical Characteristics
- MVR technology reuses secondary steam instead of live primary steam so uses only a small amount of fresh steam
- MVR technology does not require a cooling tower, greatly reducing the use of cooling water
- MVR technology is more efficient than traditional multi-effect evaporation technology which saves energy, reducing operating costs
- MVR technology is truly energy-saving, water-saving, environmentally sound, and helps with resource recycling
- MVR technology achieves low-temperature evaporation, greatly reducing the impact on your material
- MVR technology system structure is simple, fully-automated, with continuous operation
- MVR system consists of heaters, compressors, separators, pumps, piping, instrumentation, and electrical control components
4.0 MVR Applications
MVR energy-saving, low-temperature evaporation technology is widely used in many applications, including:
- Industrial wastewater treatment discharge concentration
- Chemical industry for evaporation, crystallization, and purification
- Salt brine concentration
- Beverage industry (milk, juice, sugar, etc.) concentration
- Food industry (MSG, soy, protein, sugar) concentration
- Pharmaceutical industry (medicines, vitamins) concentration
Mechanical Vapor Recompression | Mechanical Vapor | Vapor Recompression