Do storage tanks filled with dry gas as the medium require a filling coefficient? ? ?
Thread Content
Both the code requirements and their explanations state that for storage tanks containing liquefied gas, it is necessary to control the filling factor – the tanks should not be filled to capacity – in order to prevent thermal expansion resulting from temperature changes, which could pose safety hazards. But I would like to ask: isn’t a filling factor required for storage tanks of dry gases? Although the compressibility coefficient of gases is relatively high, there must still be a limit. In extreme conditions where the temperature rises significantly and the gas expands greatly, if compression cannot keep up with this expansion, an explosion can still occur, right? Furthermore, is a filling factor required for liquids?
Generally, there is a concept of a filling coefficient for liquefied gases; this concept does not apply when the medium is a gas. Extreme operating conditions should be considered in terms of the design pressure or safety relief devices, to ensure safe use under all conditions.
Reply to 2# jbj_hit: So what if the medium is a liquid, in a purely liquid state? Is it necessary to set a filling factor?
Reply to 3# huanggang1987: For pure liquids, it depends on the situation: 1) When it is completely filled, check whether the highest temperature is higher than its standard boiling point. If it is not very high, it only needs to be designed, manufactured, inspected, and accepted in accordance with GB150; supervision under the Pressure Vessel Code is not required ； If it is higher, it shall be designed, manufactured, inspected, and accepted in accordance with GB150, and subject to supervision under the Pressure Vessel Regulations. 2) Not fully filled: Check whether the temperature or the pressure in the gas phase space is within the standard and regulatory ranges.
Reply to 4# jbj_hit: Brother, isn’t there something wrong here? If the work pressure is higher than its boiling point, shouldn’t it vaporize? It wouldn’t be right if it’s filled to capacity
Reply to 5# huanggang1987: 1) If the liquid medium is not at a temperature higher than its boiling point, then in the presence of pressure it can be considered a pressure vessel, and it is not subject to the regulations regarding pressure vessels. 2) When the temperature is above the boiling point, the operating pressure at that temperature must be calculated; the design pressure can then be determined based on this operating pressure. As long as the operating temperature does not exceed the design temperature, overpressure will not occur. If concerned, a safety valve can be installed.
Reply to 6# jbj_hit: If it’s completely full, which filling coefficient should be used and for what purpose?
Reply to 7# 342502: It is filled with liquid, not liquefied gas; the filling factor for liquefied gas must not exceed 0.95, and generally 0.9 is used
According to clause 3.13 of the new regulations, the filling coefficient should be referred to as the loading coefficient. The old regulatory standards included such a calculation formula: Liquefied gas mass = filling coefficient · volume · liquid density of the liquefied gas at the design temperature. From this, the meaning of the filling coefficient can be understood, that is, the proportion of the liquid volume of liquefied gas to the total volume of the equipment under design conditions. As long as both liquid and gas phases exist simultaneously within a liquefied gas storage tank, it remains in a saturated state; the operating pressure is then the saturation vapor pressure at that temperature, and it can be predicted. If there is not enough gas space, the pressure will rise rapidly as the temperature increases. Therefore, it is necessary to control the filling factor. A pure gas always fills the entire volume, so there is no filling factor. Liquids such as water, when the temperature is below their normal boiling point (100°C), do not boil and vaporize when released into the atmosphere, regardless of the initial pressure; they contain less energy and are therefore less dangerous. If there is gas (such as air) trapped outside the liquid volume, the PV value of that gas phase volume needs to be considered. But this is a different concept from the liquefied gas filling coefficient. Water at temperatures above 100°C is essentially similar to liquefied gas; such water can be considered as steam that has been liquefied under pressure.
This post was last edited and replied to by 342502 on 2011-11-23 at 10:36. Reply 8# jbj_hit: Should a recharging coefficient be applied to liquids whose maximum operating temperature at full load is higher than or equal to their standard boiling point? It is the situation where the final operating pressure is lower than the design pressure of the container, resulting in a two-phase mixture of gas and liquid inside the container. For example, with liquefied gas, there is no need to consider a filling factor since no liquid phase exists; the same applies to oxygen and nitrogen. .
Reply to 9# Pinocchio – the explanation was very thorough; I’ve learned a lot~~:handshake