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After looking at the previous posts on the forum, I have a question about the oxygen removal law. Is it Guy-Lussac's law or Henry's law? Saw another Dalton’s Law/ This post was last edited by zg19870901 on 2009-3-30 18:59 ]
It should be the law of partial pressure, which is Dalton's law.
That’s right, it’s Dalton’s Law!
When water is heated to boiling in the atmosphere, the saturated vapor pressure of water is equal to the atmospheric pressure at the air-water interface, and the partial pressure of oxygen is equal to zero. At this time, the solubility of oxygen in water drops sharply and flows out of the water. This is the principle of thermal deoxygenation. Dalton's law of partial pressure is used.
The principle of oxygen removal is based on Henry's law, Dalton's law, and the law of heat and mass transfer. ① Henry's Law: At a certain temperature, when the gas dissolved in water and the gas separated from the water are in dynamic equilibrium, the mass b of the gas dissolved in unit volume of liquid is proportional to the partial pressure Pb of the gas on the liquid surface, that is, b = KPb/Po (mg/L) K—mass solubility coefficient of the gas Po—full pressure on the liquid surface. When the partial pressure of the gas on the water surface is less than the equilibrium pressure corresponding to the dissolved gas, the gas will separate from the water and out of the water surface under the action of the unbalanced pressure difference ΔP until a new equilibrium state is reached. The key is how to make the partial pressure of non-condensable gas on the water surface approximately 0. ② Dalton's Law: The total pressure of a mixed gas is equal to the sum of the partial pressures of the component gases. P=∑Pi +Ps (MPa) As the water flow is continuously heated by steam, the water gradually evaporates, the water vapor pressure on the water surface gradually increases, the partial pressure of other gases gradually decreases, and the gas molecules in the water gradually come out and are discharged with the residual steam. ； When the water is heated to the saturation temperature under the working pressure of the deaerator, the partial pressure of water vapor on the water surface is equal to the pressure of the deaerator head, that is, the partial pressure of steam is equal to the total pressure, and the partial pressure of other gases is approximately 0. This allows each gas in the water to be completely released, and the dissolved amount of gas in the water is close to 0. ③ Mass Transfer Law The amount of gas segregated from water is proportional to the surface area of the water A and the unbalanced pressure difference ΔP, that is, G=KmAΔP Km-mass transfer coefficient or segregation coefficient. And I think Henry's Law and Mass Transfer Law are more appropriate. Dalton's Law mainly explains the state of the gas and does not explain the process of oxygen removal clearly.