How should the calculation of the safety valve for the mixed-phase medium in the liquefied gas washing tank be determined?
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Hello everyone, please help. Liquefied gas washing tank, with a ratio of liquefied gas to water of 1.5:1.0; now it is necessary to calculate the area of the safety valve. If calculations are done assuming that the medium is entirely liquefied gas, it is clear that the area of the safety valve would need to be much larger. In foreign process package projects, the discharge capacity specified for the safety valves of liquefied gas washing tanks is significantly lower than that required when the medium is entirely liquefied gas. I would like to ask: for such a mixed-phase medium that is stratified inside the equipment, how should the safety valve be calculated?
You mean the fire condition, right? Under stratified conditions, the lower layer should be dominated by water
Yes, it is in a fire condition, with water in the lower part.
Calculated according to the API521 method for fire conditions
The medium cannot all become gas; only by dividing the heat absorbed by the latent heat can one determine how much gas there is, and it doesn’t happen all at once
The medium cannot all become gas; only by dividing the heat absorbed by the latent heat can one determine how much gas there is, and it doesn’t happen all at once
My opinion is for reference only: The assumption is that the selection and calculation are based on fire conditions； Since the liquefied gas is at the top of the container, in case of a fire, it will first vaporize and cause overpressure ； The medium can be calculated based on liquefied gas monomers. For the specific calculation formula, either GB150 or API521 can be used; the difference is not significant. Under these operating conditions, it cannot strictly be considered a multiphase flow.