In which type of evaporator is the control of brine density least important?

In flash evaporators, the control of brine density is less critical because the primary function of this type of evaporator is to utilize the phenomenon of flash evaporation. This occurs when seawater is subjected to reduced pressure, allowing a portion of it to vaporize rapidly without the need for heating. The design allows for the separation of vapor and liquid phases in a manner that is less dependent on the actual density of the brine compared to other evaporator types.

In contrast, tube evaporators and plate evaporators typically involve direct contact between the heating medium and the brine, where consistent brine density is important for maintaining efficient heat transfer and proper operational conditions. Falling film evaporators also require careful management of brine density because they rely on a thin film of liquid flowing down heated surfaces—any fluctuation in density can affect the thermal performance and efficiency of the system.

Thus, the operational characteristics and design of flash evaporators reduce the reliance on tightly controlled brine density, making them distinct in this aspect.