Overheated steam pressure issue
Thread Content
As we all know, the pressure of saturated water vapor is related to temperature. However, I have a question that I would like fellow enthusiasts to help answer: Suppose 0.8 MPa of saturated water vapor is superheated to 250°C. At 250°C, will the pressure of this superheated vapor be the same as the pressure of saturated water vapor before it was superheated?
This post was last edited by ylb913 on 2015-7-19 13:51. Steam is in motion; what’s the use of steam that isn’t moving? There is pressure loss associated with flow; therefore, after saturated steam is superheated, its pressure only decreases.
Theoretically, the pressure remains unchanged after heating; of course, in practice it decreases due to pressure drop
Did I fail to understand the question posed by LZ, or did LS fail to understand it? What does it have to do with pressure drop? Superheated steam is achieved by increasing the temperature while keeping the pressure constant.
As the temperature rises, increased molecular motion leads to higher pressure, right?
It depends on whether it is isochoric heating or isobaric heating. Isochoric heating: volume remains constant, temperature rises and pressure increases ； During isobaric heating, the pressure remains constant while the volume increases.
Lz is asking about the isobaric heating process, right? Think about the vapor property curve.
Superheated steam is generated by further heating saturated steam after it has been discharged from the boiler; it is a dynamic transfer process, and the pressure downstream can only be less than or equal to the pressure upstream – otherwise, what’s the point of such a reverse flow?
This post was last edited by Little Worker on 2015-7-21 at 16:50. Saturated steam has a one-to-one relationship between temperature and pressure, but this is not the case for superheated steam; superheated steam at 0.8 MPa can have multiple temperatures – it can be 150 degrees, 200 degrees, or 250 degrees. When you heat saturated steam to turn it into superheated steam, it depends on whether the volume of the gas remains constant. If it remains constant, then the pressure will definitely increase. If the volume keeps changing, it’s hard to say how the pressure will change. Generally, when talking about superheated steam, one first mentions the steam pressure and then determines the specific conditions of the steam based on the temperature. But you are determining the superheated steam pressure based on the temperature; in my opinion, the order of these steps is reversed