How Flash Column Works

Flash refers to the saturated water and saturated water under the pressure of the container when the saturated water at high pressure enters the container at low pressure. In the process of chemical production, the flash tower can realize the rough gas-liquid separation of materials, and the flash tower can be roughly separated before entering the atmospheric furnace, so as to reduce the load of the atmospheric furnace.

When water is heated at atmospheric pressure, 100℃ is the maximum temperature allowed for liquid water at that pressure. Reheating does not raise the temperature of the water but converts it into steam. The heat absorbed by water in the process of heating to the boiling point is called sensible heat, or sensible heat of saturated water. The heat required to convert saturated water into steam at the same atmospheric pressure is called latent heat.

However, if the water is heated under a certain pressure, the boiling point of the water will be higher than 100℃, so more sensible heat is required. The higher the pressure, the higher the boiling point of water, and the higher the heat content. When the pressure drops, some sensible heat is released, and this excess heat is absorbed in the form of latent heat, causing part of the water to “flash” into steam.

In fact, in the distillation calculation of the tower, each theoretical plate is required to perform such a flash calculation, but the general name is the “equilibrium stage” calculation, which is more rigorous in theory, and the content of the calculation is exactly the same. Each strict or “flash” calculation or “equilibrium stage” calculation must satisfy the following three major equilibria: mass equilibrium, energy equilibrium, and phase equilibrium. Thus, a standard “flash” calculation module can handle changes in pressure (rise or fall) as well as the exchange of heat and work.

empty flash column chromatography

The exchange of internal and external work and heat exchange are mainly reflected in the energy balance, while the mass balance and phase balance mainly determine the vaporization fraction and the composition of the vapor and liquid phases. In addition, the “flash” calculation has a very important and difficult task, which is to judge whether the state you specify is in the vapor and liquid phases, or just the vapor phase or liquid phase only. In addition, the calculation of liquid-liquid equilibrium generally requires the “flash” calculation, of course, some software is taken out alone, because the calculation is more difficult.

Operating principle
Flash column is when the saturated water at high pressure enters the container at low pressure and becomes saturated water vapor and saturated water under the pressure of the container due to the sudden decrease of the pressure. By taking advantage of the differences in the volatilization of the components in a liquid mixture, the method of partially vaporizing the components in the vapor phase with the medium of heat energy to enrich the light components in the liquid phase and separate them by combining the components.

Causes of flash:
When water is heated at atmospheric pressure, 100℃ is the maximum temperature allowed for liquid water at that pressure. Reheating does not raise the temperature of the water but converts it into steam. The heat absorbed by water in the process of heating to the boiling point is called sensible heat, or sensible heat of saturated water. The heat required to convert saturated water into steam at the same atmospheric pressure is called latent heat.

However, if the water is heated under a certain pressure, the boiling point of the water will be higher than 100℃, so more sensible heat is required. The higher the pressure, the higher the boiling point of water, and the higher the heat content. When the pressure drops, some sensible heat is released, and this excess heat is absorbed in the form of latent heat, causing part of the water to “flash” into steam.

The actual situation
Flash column appears in the pipeline system, easy to cause cavitation damage to the valve, you can choose anti-cavitation high-pressure valve, its characteristics are multiple throttle allocation of pressure difference, also can choose cavitation erosion material. Flash can also be used as energy for recovery of boiler drainage and geothermal power generation in thermal power plants.