Where is the first bit of liquid produced when the air conditioner starts?
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The process simulates a steady-state process, but driving is actually a dynamic process. The steady-state process actually ignores many things, many factors. The actual operating conditions are also dynamic. Only by in-depth discussion of dynamic issues can we understand the air separation process more truly and comprehensively. Here to draw out some ideas, you might as well discuss, where will the first liquid come from when the air separation starts?
Is it a place where the pressure and temperature meet the conditions for liquefaction at the same time? It’s usually at the last stage of cooling equipment, right?
After the expanded air enters the throttle valve of the upper tower? Or cooled air?
It should be that during the cooling stage at the top of the lower tower, the temperature difference between the upper and lower towers is not very large, but the pressure of the lower tower is much higher than the pressure of the upper tower.
The first drop of liquid is produced at the bottom of the liquefier. If there is no liquefier, it will be generated at the bottom of the plate heat exchanger.
It should be generated in the cold box, which may be the upper or lower tower, or the main condensing evaporator, or the main exchange plate bottom. It is necessary to carefully analyze whether there is any dynamic simulation. If there is a dynamic simulation result, it will be more convincing.
It should be that the cooled air enters the lower tower first to produce droplets. If the expanded air enters the upper tower and is to be liquefied, it first needs the low temperature of the subcooler, and at this time there is no liquid supply in the subcooler.
I think it should be determined based on the pressure level. Everyone knows that the high-pressure air (about 6MPa) coming out of the final stage of the air booster enters the main heat exchanger to exchange heat with nitrogen and oxygen products and then enters the lower tower through the throttle valve. The temperature of the air after entering the heat exchanger is -170 degrees Celsius. At normal pressure, the air will condense into liquid air at -178 degrees Celsius. The air at 6MPa and -170 degrees Celsius will also liquefy, so the first drop of liquid in the air separation unit is produced in the main heat exchanger (personal opinion, please give me some advice)
Personally, I agree with the 8th floor’s opinion.
The first drop of liquid in the air separation unit is produced in the subcooler, where the pressure is the pressure of the lower tower and the temperature is slightly lower than that of the lower tower.
In the gas-liquid separator (after high-pressure liquid air throttling)