Why is the temperature in the upper tower lower than that in the lower tower? Is it the function of the liquid from the lower column to act on the throttle valve in the upper column?
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Why is the temperature in the upper tower lower than that in the lower tower? Is it the function of the liquid from the lower column to act on the throttle valve in the upper column?
Separating the upper tower from the lower tower into two sections is probably because the tower is too tall; it becomes easier to understand if they are stacked together. The feed to the distillation tower and the top reflux are both used to lower the temperature (other functions will be discussed later); in both cases, the temperature at the upper part is lower than that at the lower part. The lighter components above require a lower temperature to be vaporized, while the heavier components below need a higher temperature to be vaporized. In each tray of the tower, the gas and liquid phases are in equilibrium (this is the theory; in practice 3–5 trays are required, but the general trend remains the same)
Pay attention to the tower pressures of the upper and lower towers, as well as their respective saturation temperatures~~
The vast majority of the cooling capacity in air separation comes from expanders, about 85%, with the remainder coming from throttling cryocoolers~~
These basic concepts are all covered in \"Questions and Answers for Oxygen Plant Operators\"~ It can be downloaded or the book can be purchased for reading~~
There is a pressure drop issue inside the tank. Is the pressure greater the lower you go? In an ideal situation, when PV=NRT, the pressure is high and the temperature is relatively high.
The temperature in the upper column is lower than that in the lower column because the pressure in the upper column is much lower than that in the lower column; the liquid from the lower column undergoes throttling, which causes it to cool and lose pressure before entering the upper column.
According to the Joule-Thomson effect, the liquid nitrogen and liquid air at the pressure in the lower column enter the upper column through throttling. This process causes the subcooling temperature of the liquid to decrease due to the pressure drop resulting from throttling; as a result, the liquid nitrogen and liquid air entering the upper column are in a more supercooled state compared to those in the lower column. Hence, the temperature in the upper column is lower than that in the lower column
After heat exchange with the liquid air and liquid nitrogen from the lower column, as well as with the reflux gas from the upper column (which has a low temperature), a certain degree of subcooling is achieved; the temperature drops further after throttling
Different pressures correspond to different saturation temperatures
The temperature in the upper column is lower than that in the lower column, mainly because the pressure in the upper column is lower; the liquid from the lower column, after being cooled by throttling with liquid nitrogen, is fed into the upper column. Now they are arranged separately in parallel; maybe distillation column and rectifier column? \"Going up the tower and down the tower\" was an old term referring to a tower.