Selection of steam pipe diameter
Thread Content
Supplied superheated steam at 0.5 MPa and 180°C enters the plant area; what should be the diameter of the main pipe? (During normal production, the total steam consumption of the entire plant does not exceed 5 t/h)
In chemical engineering principles, once the total flow rate is known and empirical values for the flow velocity are available, the pipe diameter can be calculated
Superheated steam has flow velocities corresponding to three different pipe diameters; the pipe diameter is determined by the flow velocity. Since the pipe diameter is not known, how can one determine which set of empirical values to use?
Put differently, can superheated steam at 0.5 MPa and 180°C with a DN100 diameter meet a steam consumption of 5 t/h? And how is this calculated?
Calculate the pipe diameters required for the three flow rates; once the appropriate diameter range is identified, it can be verified within that range
Find the density of the superheated steam; for example, a rough estimate of the density is 3.2 kg/m3. Converting 5 t/h to volumetric flow rate gives 1560 m3/h, which is equivalent to 0.43 m3/s. For a DN100 pipe, the flow velocity would be 55 m/s, which is too high! DN125 pipe diameter, flow rate of 35 m/s – suitable! The pipe diameter is DN150, and the flow velocity is 25 m/s, which is too low. Therefore, DN125 should be chosen; considering potential increases in usage and future expansion, it is possible to upgrade to DN150
This post was last edited by Watt Energy Saving on 2017-10-16 22:02. If we use your parameters, there are serious problems. For a DN100 steam pipe, at 5 BARG the flow velocity is 51 m/s; if the length of the pipe is 20 meters, the pressure drop is 12 KPa. If the pipe length is less than 10 meters, the pressure drop is relatively small. If the pipeline length is greater than 50 meters. Then the flow rate is too high, which can easily lead to noise, vibration, and the possibility of water hammer. The pressure at the steam generation point may not meet the requirements.
I think you shouldn’t base it on the normal flow rate; instead, you should use the flow rate during abnormal conditions. A branch pipe should be installed for normal conditions, otherwise you’ll be in trouble when there are abnormal situations
For the original poster, is it correct that the flow velocity for DN125 pipes is 35 m/s, and the flow velocity for DN150 pipes is 25 m/s? If I don’t understand, I’ll just ask you for help.