Relationship between material evaporation rate and steam flow rate in a distillation column
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Our distillation tower operates intermittently and is equipped with two heating methods: jacket steam and forced-circulation reboiler. After feeding to 80% level, heating and distillation are carried out. The vacuum level is around -60, and the material boils at 70 degrees. When only the jacket is used, the temperature can meet the requirements, but the evaporation rate is low (no reflux, complete extraction). Can the evaporation rate be increased by raising the steam flow rate when other conditions are not favorable?
High temperature and low pressure are favorable for analysis; based solely on your description, it is achievable. Additionally, if you want to see the actual effect, it is also related to the quality of the steam
A high steam flow rate does not necessarily mean an increase in heating capacity; a large portion of the heating power provided by steam comes from the enthalpy drop as steam turns into water. Without this enthalpy drop, simply changing the flow rate may not yield good results.
Increasing the steam flow rate (by opening the bypass) will certainly increase the evaporation volume, but when the heat exchange area remains constant, the relationship between steam heating efficiency and flow rate is not linear; therefore, increasing the steam flow rate is not cost-effective, as it is less economical than using a forced-circulation reboiler.
Q1=KS△T; this is mainly limited by the heat transfer coefficient of the equipment； Q2=Wr*m, which is limited by the heat medium flow ； When Q1 > Q2, increasing the steam flow rate can increase the evaporation rate ； When Q1 < Q2, increasing the steam flow rate does not increase the evaporation volume.
I don’t understand what it means for the temperature to reach the required level. When only a jacket is used, the heat exchange area is small; increasing the steam pressure can improve the heat exchange efficiency by raising the temperature difference for heat exchange, but the visible effect is average. It is recommended to turn on the forced circulation reboiler as well.
I don’t understand what it means for the temperature to reach the required level. When only a jacket is used, the heat exchange area is small; increasing the steam pressure can improve the heat exchange efficiency by raising the temperature difference for heat exchange, but the visible effect is average. It is recommended to turn on the forced circulation reboiler as well.