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Posted by steamer on December 07, 2003 at 01:57:06:

In Reply to: Steam line sizing posted by Rick on November 16, 2003 at 09:30:42:

: I'm researching a project to convert a 12" schedule 80 main steam line from 175 psig to 45 psi using 100% turbine exhaust to feed in instead of pressure reducing stations. I need to find a table or a calculation that can calculate what volume of 45 psig steam a 12" sch 80 line can carry. Currently the line is sized for 240,000 lbs/hr but max plant load is 175,000 lbs/hr.

Hi Tony

Using Spirax Sarco software 'Spiracalc', and for the stated conditions and using saturated steam as is not mentionated the condition of temperature in turbine exaust, you need to have at least a 28" line to carry 175.000lbs/hr at a standard velocity of 80ft/sec.

This in turn gives a pressure drop of 0.06 psi/100 ft.

Please note that a 28" globe valve is equivalent in terms of pressure drop in linear pipe to 900 ft so selection of pipeline ancilliaries is quit important in this case gate valves can be a good choice.

With the actual 12" line you can get a maximum flow of 35000 lbs/hr at 80ft/sec with a pressure drop of 0.2 psi/100 ft

Hope this helps - Kind Regards