Feed condition of the falling film evaporator
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Is the feed to the falling film evaporator in a saturated state? What happens if it is subcooled? Will a film fail to form? For example, if water at 95 degrees is used as the feed and the evaporator operates at atmospheric pressure, with 5 degrees left until the boiling point of 100 degrees, is that sufficient?
An evaporator is, in essence, a place where heat transfer occurs. If the solution reaches its boiling point, it will boil; if it does not reach that point, its temperature will rise. Both boiling and temperature increase are processes of heat transfer, and they both follow the laws of heat transfer. The total amount of heat transferred is proportional to the heat exchange area and the temperature difference involved in the heat transfer. Therefore, a falling film evaporator can accept feed at low temperatures; once the feed enters the evaporator, it first heats up and then boils, as long as the total heat exchange area is sufficient.
The feed state to the evaporator is generally a two-phase mixture of gas and liquid, with the gas flow rate varying depending on the circumstances
Saturation is not required; to determine whether it can become MO, consider the shape of the centrifugal MO generator. There are many different shapes available at present.
It should be possible, but it’s unreasonable. If it’s possible to raise the temperature using a cheap and compact heat exchanger, why not do so? But if the capacity of your falling film evaporator is already sufficient to meet the requirements, there is no need to add an additional preheater.