Regarding high-pressure saturated steam entering low-pressure superheated steam
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The main pipe has a diameter of DN400, with a pressure of PN4.2 MPa; the steam temperature is 430 degrees, and the flow rate is 230 T/H. The branch pipes have a diameter of DN100, with a pressure of PN5.5 MPa; the steam temperature is 270 degrees, and the flow rate is 20 T/H. How should these two pipes be combined? Does it require special handling?
This post was last edited by xyc114 on 2011-11-30 at 13:33. Regarding what you just described, according to relevant safety requirements and standards, it is best to install a mixer between steams with different physical properties. Negative pressure entrainment can take place within a tube, but I have never seen high-pressure saturated steam directly entering low-pressure superheated steam.
It is recommended to consider installing a steam mixer on the main pipe to introduce the branch pipes, while also considering installing pressure relief valves and associated drain valve assemblies on the branch pipes first.
It should be handled based on the principle of giving priority to maintaining the parameters of the main steam, while also reducing the thermal stress in the mixed metal. If it is used to drive a turbine for power generation, I believe such mixing is not worthwhile, as the temperature difference between the two materials is too large; irreversible losses occur during the mixing process, resulting in a loss of power generation capacity
Reply to 2# xyc114: Could you please specify the exact specifications?
Reply to 3# dongjiang1001: Are there specific specifications available for steam mixers?
Reply to 4# gjn1970: Since saturated steam is useless, someone came up with this solution. Do you have any better suggestions for such a situation? Thank you
Reply: 7# sailan, PN4.2mpa, temperature 430; it falls under medium-pressure parameters； PN5.5MPa, temperature 270 – these are sub-high pressure parameters. Do you have units with such sub-high pressure parameters where you are? If available, find a way to heat this saturated steam into superheated steam with a temperature matching that of its feed steam, so that it can be mixed with the main steam to drive the sub-high pressure steam turbine to produce work. If not, reduce the pressure further as appropriate (taking pipe resistance into account); after heating, achieve a pressure of 4.2 and a temperature of 430 degrees, and then consider mixing this superheated steam with the main pipeline
Reply to 8# gjn1970: Thank you very much. Could you provide a reference value regarding the approximate pipeline resistance for steam? Or even a calculation formula would work
This post was last edited and replied to by gjn1970 on 2011-12-2 at 11:48. Reply 9# sailan: The resistance in the steam pipes can be calculated, including that in the superheater; 5% of the initial pressure can be taken as a value for this purpose. Given the large pressure difference between the two, it is entirely possible to ignore such resistance