The principle of a flash evaporator
Thread Content
This post was last edited by qazxsw119 on 2009-12-24 at 12:24. Could any member help me by explaining the principles of various types of flash evaporators, as well as the specific methods for implementing them? Thank you very much
What is commonly used is high-pressure steam condensate being fed into a flash tank to generate 5 KG of steam. Specifically, the flasher here is just a tank.
Principle: According to Henry’s law P=EX, the solubility of gas-phase solutes in the liquid solvent varies at different temperatures and partial pressures. When the solvent pressure decreases, the solute in the solvent is rapidly desorbed and released automatically, resulting in flashing. The energy for flashing is provided by the solvent itself, so the temperature of the solvent decreases during the flashing process. From a higher constant pressure to a lower constant pressure, when desorption equilibrium is reached, the amount of solute desorbed remains constant, and the amount of solute remaining in the solvent also remains constant. Therefore, there is only one control target for flashing, and that is the flashing pressure
Henry’s law applies to the gas-liquid equilibrium of ideal dilute solutions. It is generally used in gas-liquid absorption, while flash evaporation, in my understanding, falls under distillation; in that case, Raoult’s law, which deals with ideal solutions, should be used to determine the gas-liquid equilibrium. I don’t have any practical experience, so I’m not sure if it’s correct. If Raoult’s law applies, then y = p * x, where y and x are the molar fractions of a certain component in the gas and liquid phases, respectively. For two-component gas-liquid equilibrium, according to the phase rule, the system has 2 degrees of freedom. By selecting T and P as the system variables, when P is fixed, a specific value of T allows one to determine the mole fractions of each component in the gas and liquid phases at different gas-liquid equilibria. Thus, by maintaining a constant pressure in the flash tank, gas and liquid phases with different compositions can be obtained. The flash tank operates under vacuum; in my opinion, there is no need to heat the material to very high temperatures, which is advantageous for the separation of heat-sensitive materials
It’s recommended to go back and look at the textbook on principles of chemistry; you might find satisfactory answers there
Hucarehu is right; use Raoult’s law to calculate it
In simple terms, a small amount of material is fed into the flash vessel, and steam is used to rapidly evaporate the water contained within that material
You’re wrong; it is the solvent that evaporates, not the solute.
The principle of a flash evaporator is to use pressure changes on the working fluid (water) to cause it to vaporize at the same temperature. I agree with the suggestion from above; you should read a book.
Oh, okay, I’ve learned it. Thank you all for your guidance. I wasn’t in the chemical industry before; I’ve changed careers now, so there are many things I don’t understand, which is why I asked. Thank you