By vaporizing liquid carbon dioxide, by how much can its own temperature be reduced?
Thread Content
As the title suggests, when liquid carbon dioxide vaporizes, by how much does its temperature decrease? During the initial operation of a 90% liquid carbon dioxide distillation process, should the liquid level be established first in the reflux tank, or in the bottom of the distillation tower?
By consulting the saturation vapor pressure curve for carbon dioxide, the relationship between pressure and temperature at equilibrium in an adiabatic system is indicated on that vapor pressure curve. In fact, there is significant heat exchange between the system and the environment, and the gas inside the system is not pure carbon dioxide. Judging from the question you asked, your understanding is far too poor; even if I explain it, you won’t understand it
380,000 tons of damage was incurred; it actually involved carbon dioxide purification processes. The top condenser in these systems was cooled using cold water at -20°C. At the beginning of the feeding process, the system pressure was low, and the liquid feed vaporized instantly, absorbing heat in the process and causing the system pressure to rise. Meanwhile, the temperature at the feeding point also decreased. I am aware that heat exchange occurs, but the vaporization rate is fast, while the rate of heat exchange with the surrounding environment is not so fast. So there is a question: does the rapid drop in temperature due to heat absorption occur faster, or does the cooling effect of the -20-degree cold water at the top of the tower happen faster? Does liquid appear first in the reflux tank, or at the bottom of the tower?
http://www.doc88.com/p-1466074069964.html Looking at the vapor pressure curve of carbon dioxide in this table, it is possible for the temperature to drop below -60°C after carbon dioxide flashes, under the condition that there is no gaseous carbon dioxide in the initial feed system. The feeding is interrupted; the liquid feed flows downward while vaporizing at the same time. It’s hard to say whether it flows faster or vaporizes faster
It must be that carbon dioxide enters from the inside and vaporizes, causing a rapid drop in temperature; waiting for the heat exchange resulting from condensation at the top of the tower to take effect is too slow.
In principle, both liquid levels must be replenished through the startup pipeline before starting up. If it’s not possible to replenish the liquid level in the top reflux tank, it is sufficient to maintain only the liquid level at the bottom of the tower.
I have a question: looking at the carbon dioxide phase diagram, it seems that there is no liquid carbon dioxide below -56 degrees Celsius. However, some data tables show vapor pressures at temperatures as low as -60 degrees or even lower. What’s going on here? Please ask an expert to clarify this, thank you!
Carbon dioxide sublimates to produce vapor. I haven’t studied the equilibrium relationship between the vapor pressures of solids and gases*
It’s already the 5G era – are we still looking at profile pictures? The phase diagram accuracy is too low, and the listed data is limited. A chemical engineering calculation app that allows you to accurately calculate the saturated vapor pressure of pure substances at any temperature and pressure. In the current latest version 4.0, only the calculation of properties for gas mixtures has been released; the calculation of properties for pure substances is still under development. This feature has not been released yet, just for your reference. Detailed introduction to the chemical engineering calculation APP: https://bbs.hcbbs.com/thread-2693876-1-1.html