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Evaporation compression startup and control

Start Compression evaporation model with default parameters. The objective of this exercise is to start the installation and set it to produce a 20% mass fraction concentrate from a 7% mass fraction feed

  • Fully open reboiler shell degasing valve to atmosphere
  • Start centrifugal compressor at 10% power, follow suction and discharge pressure, and look at anti-surge controller (mini-flow)
  • Controlling suction and discharge pressure, increase compressor power to reach boiling in the evaporator
  • When boiling occur, maintain inert purge to atmosphere until condensation begins
  • Increase slowly compressor power up to 80%
  • Set condensate level controller to automatic mode and start condensate pump
  • Feed evaporator to keep bottom level constant until concentrate mass fraction objective of 20% is reached
  • When evaporator concentrate is at objective, feed evaporator to keep this concentrate composition
  • When installation is in steady state, check global and partial mass balances
  • Check the energy balance, comparing various heat flux: feed pre-heat, vaporization in evaporator, condensation on condenser shell side, compressor power
  • Calculate evaporator economy (or performance coeficient) as the ratio between power given to evaporator and power used by centrifugal compressor