2 replies to this topic

[Ah Jib Gor]

Greetings to all

I'm currently working on a falling film evaporator. From a couple of books I read, I understand that it requires low temperature difference between the steam and the liquid. My liquid flows in at 55 degree celcius, and I've decided to use steam at 1 bar which carries a temperature of 99.6 degree celcius. Hence, I would like to know if this temperature difference is still acceptable for falling film evaporation?

[Ah Jib Gor]

Hi brondy, thanks for the feedback.

Does this mean the heat absorbed are mainly used for the phase change of the liquid to be heated? I'm planning to heat the liquid from 55 degree celcius to 150 degree celcius to get the fraction of components I want. Hence, some components in my feed mixture might be even superheated after changing to gas phase.

So far, my understanding on one of falling film characteristics would be small temperature difference between feed inlet and steam inlet. The temperature difference between feed inlet and outlet does not need to be low, the same goes for steam inlet and outlet.

[isbarqi]

According to Perry's Engineering Handbook, falling film evaporators type work well at all temperature difference.

So, the higher temperature difference might obtain a smaller heating surface area, that can reduce the capital cost.