MVC Evaporator Process Description

MVC Evaporator Process Description

Principles of Operation

The ENCON MVC Evaporator is a forced circulation flash evaporator utilizing mechanical vapor compression. By using this design, the ENCON MVC Evaporator allows for minimal scaling, maximum uptime, and low operating costs.

  • What is Evaporation?
  • What is a Forced Circulation Flash Evaporator?
  • What is Mechanical Vapor Compression?

Process Description (refer to diagram below)

  • 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 vapor compressor(s).
  • A mist pad is provided at the top of the separation tank to remove small droplets of liquid from the vapor.
  • The vapor compressor 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 vapor is 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.