2. General information about evaporation:
2.1. Falling film and forced circulation evaporator
The unit has falling film and forced circulation evaporator.
The falling film evaporator is use for low concentration of vinasses. When the concentration increase the clogging risks are more important and it’s necessary to use a forced circulation evaporator.
Falling film evaporator:
The falling film evaporator is a vertical exchanger. The vinasses at the bottom of the exchanger are sent to the top of the evaporator with a circulation pump. By gravity, the vinasses go to the bottom of the tubes (inside the tubes)
The vinasses are split on all exchange tubes with some distribution plates. The aim is to send enough vinasses in each exchange tubes and decreasing clogging risk.
Inside the tubes there is a thin layer of vinasses. Outside the tubes, there is some steam. This steam hotter than the vinasses are condensate, and condensation energy is transfer to the vinasses. The vinasses are evaporated.
At the bottom of the tubes there is a mix of vinasses and vapor (the amount of vapor is low, less than 5% of the circulation flow is evaporated). The vinasses go back to the circulation pump to be send again to the top of the evaporator.
The vapor goes through the separator to decrease its speed and decrease foaming risk. In this installation, the separator (CO.72.XX) is separated from the calandria (E.72.XX).