I’m confused about the throttle valve of the cold box
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From what I understand, a throttle valve has high-pressure input and low-pressure output, and the temperature at the outlet is even lower than that at the inlet. So two problems arise. The first problem is that, as the name suggests, high pressure on the inlet side and low pressure on the outlet side results in a reduced flow rate; but won’t an increased inflow rate cause pressure buildup? The second question is why does the temperature drop when low pressure is applied?
Are there any experts who know the answer to this question? It has been bothering me for a long time without a solution.
The change in pipe diameter before and after the throttle valve results in a lower pressure and increased volume after throttling. The overall quantity remains unchanged; only the pressure decreases while the volume increases. This decrease in pressure and increase in volume causes heat to be absorbed, leading to a drop in temperature
Confused? To resolve confusion, it’s better to read more books; I recommend \"Principles of Chemical Engineering\". He will resolve your confusion. “From what I understand, a throttle valve has high pressure on the inlet side and low pressure on the outlet side; (it is likely that when the fluid flows through the throttle valve, the pressure before the valve is higher than the pressure after it. If it is at rest, when equilibrium is reached, the pressures at both ends are the same. ) And the temperature coming out is even lower than the input temperature. (After throttling, there is a temperature change relative to the pressure behind the valve; that is, gas compression generates heat, and a decrease in pressure leads to a temperature drop.) ) So two problems arise. The first problem is that with high pressure on the inlet and low pressure on the outlet, literally speaking, the flow rate exiting decreases; then, won’t an increased inflow rate cause pressure buildup? (Because your air intake flow is controlled by the allowable pressure before the valve; overpressure cannot occur, and this needs to be adjusted – it’s not possible for overpressure to happen as you might think, or there must be some means of control.) The second question is: why does the temperature drop when low pressure is produced? ”(Refer to Master 3#’s answer). To be honest, your question gives me the impression that you’re focusing only on the valves, without considering anything else, and that’s why you have this issue. It is recommended to consider issues from the perspective of the overall process.
:Handshake – thanks for your guidance, brother; it was very useful. I’ll also take a look at that book on chemical engineering principles you recommended. :lol
:Handshake. Thank you for the guidance; it’s much clearer now. :lol
Should I read the fifth edition of the book \"Principles of Chemical Engineering\"?
This makes little difference in terms of version; it’s enough to solve your problem.
May I ask the original poster, where is the cold box used?
Throttle valves sometimes also serve to control flow rate; additionally, a decrease in temperature can be attributed to the Joule-Thomson effect