Reasons for the decrease in temperature and pressure of steam during long-distance pipeline transportation
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The steam produced by the boiler is superheated steam at 260°C and 0.6 Mpa; the pipeline length for transportation is approximately 2000 meters, with pipes having a diameter of 300 mm. Upon reaching the customer’s site, the steam’s pressure drops to 0.3 Mpa and its temperature falls to 180°C before it is used. What is the analysis of the reasons for the decrease in temperature and pressure? 1. It is because the pipes dissipate heat, which lowers the temperature; as a result, some of the steam condenses into water, leading to a decrease in pressure. 2. It is also because the pressure has decreased, which in turn causes the steam temperature to drop. Furthermore, the heat contained in these two types of steam must be at 260°C; what about steam at 0.6 Mpa?
Pipes inherently have pressure drops in areas such as elbows and expansion joints.
If the traffic volume is high enough, check the process to see if there are any limits, and also take the opportunity to check the insulation
Why, at the end, after accounting for all the losses and resistances, the heat generated by the steam was actually higher than it was at the initial stage, when the temperature was 260 degrees Celsius and the pressure was 0.6 MPa? Despite all those losses, there was still more heat produced
Why, at the end, after accounting for all the losses and resistances, the heat generated by the steam was actually higher than it was at the initial stage, when the temperature was 260 degrees Celsius and the pressure was 0.6 MPa? Despite all those losses, there was still more heat produced
For long-distance steam transmission, expansion joints are definitely necessary to mitigate thermal expansion and contraction as well as thermal stress. Calculate the pressure and temperature losses in these areas.
The pipeline itself has heat transfer losses and frictional resistance, and each elbow, valve, compensator, etc. also presents local resistance; therefore, there is definitely a pressure drop as steam passes through it. From what I’ve found, the enthalpy of steam at 0.6 MPa is 2977 kJ/kg, while at 0.3 MPa it is 2823 kJ/kg, so the enthalpy of the steam must decrease.
It must be because of the temperature and heat dissipation that the pressure decreases, right? ? Isn’t heat related only to temperature? Shouldn’t we be able to determine the calorie content just by looking at the temperature?