Questions regarding temperature and pressure of LPG storage tanks
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Is the pressure inside a liquefied petroleum gas storage tank always at a balanced level? (Ignoring the ambient temperature, as insulation is in place.) If the temperature and pressure of the liquid fed into the tank remain constant, and there are no ways for pressure to be released from the tank, can liquid keep flowing in continuously? What I was thinking was that the liquid phase would fill the gas phase space in the tank, thereby increasing the pressure. But when the pressure rises, at that temperature liquid will precipitate out again; so by filling the tank in this way, its pressure won’t increase. I’m not sure if this idea is correct – I haven’t understood it yet. Thank you!
Since there is inevitably non-condensable gas in liquefied gas, the higher the liquid level, the greater the pressure.
This post was last edited by *angmf on 2015-9-11 22:39. If there is no non-condensable gas, does that mean the LPG is in a balanced state? The LPG I’m dealing with comes from the bottom reboiler; there’s very little non-condensable gas, at most just a little ethane, which has already been dissolved. Moreover, no non-condensable gas is shown in the HYSYS simulations, so it’s unclear what the actual situation will be. Do LPG storage tanks in ordinary factories have automatic pressure relief mechanisms, in case the liquid level rises and no more liquid can flow in?
In addition to vapor pressure, pump pressure and the effects of thermal expansion must also be considered.
Hello! I would like to ask whether the pressure in propane or LPG storage tanks in factories is generally at a balanced level? It is still greater than the saturated vapor pressure, thank you!
Can you use your brain when doing work? ? ? You currently have an LPG tank with a capacity of 100 cubic meters; 80 cubic meters of this is liquid LPG, while the remaining 20 cubic meters is gaseous space. If this tank is left alone for a month, equilibrium will naturally be reached between the liquid and gas phases. After a month, if you try to extract all 80 cubic meters of LPG and transfer it into smaller commercial LPG tanks, due to the short time frame – say, half an hour – the LPG won’t have enough time to vaporize and fill up the entire 100 cubic meter space. As a result, the 20 cubic meters of gas present will have to fill that 100 cubic meter space, which causes the pressure to drop rapidly, sometimes even reaching vacuum levels. In such cases, nitrogen needs to be added to the tank – this is what’s referred to as “insufflation”. The same principle applies when filling an empty tank; it’s just “exhaustion” in that case. If the gas inside the tank isn’t removed in time, pressure buildup will occur. This is what’s meant by the “breathing” mechanism that exists in all storage tanks. It takes time for equilibrium between the liquid and gas phases to be established. It’s fine to focus on achieving equilibrium, but focusing solely on it can be problematic. It takes you three bowls of rice to feel full, but you don’t have time to eat three bowls; after eating just two bowls, you’re not full yet. . You’ll get full if you eat four bowls. . Three bowls represent a state of equilibrium, which is a thermodynamic concept; the process of eating, with two bowls or four bowls, as well as the time it takes to have a meal, are processes, which are dynamic concepts. When driving a car, there is also a process of going from rest to a speed of 100 km/h – does the car reach 100 km/h right away once it’s started? ? ?
Is LPG not having enough time to vaporize? Could the time required for this gasification process be determined? If this container is thermally insulated, let’s assume it’s ideally insulated, then its temperature will definitely drop until it reaches the temperature corresponding to that pressure. How can we calculate the time required for this process? Should it be calculated using the specific heat of vaporization?
For your question, take a look at this post; my reply is on floor 8. In process design, the design of process flows for storage tanks is the most fundamental aspect and must be mastered. http://bbs.hcbbs.com/thread-1019654-1-1.html