Previous in Forum: Steam Line   Next in Forum: Use Nitrogen Cylinders Without Pressure Regulator
Close
Close
Close
4 comments
Active Contributor

Join Date: Sep 2020
Posts: 17

Saturated Steam

10/15/2020 9:03 PM

A vacuum system in the plant require steam supply of 18 bar g. However the current vacuum supply to the plant unable to meet the required pressure. Therefore, a solution is proposed to add a tie-in-point from another plant that supplies steam of 37 bar g. We are adding a PRV to reduce the pressure from 37 bar g to the required pressure which is 18 bar g. It is saturated steam. This is the sketch of proposed solution.
Question 1: Is there any possibilities of condensate formation inside the steam line when the pressure is being reduced?
Question 2: Do we need to add the PSV in the case of overpressure?

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Guru
Hobbies - CNC - New Member Hobbies - DIY Welding - New Member Engineering Fields - Electromechanical Engineering - New Member

Join Date: Aug 2007
Posts: 22774
Good Answers: 411
#1

Re: Saturated steam

10/15/2020 9:32 PM

I believe when the pressure is reduced, it’s just the opposite occurs. Just keep in mind, that the energy content is reduced of the steam is also reduced.

theres a program called WASP (Water and Steam Properies) from Katmar Software. It’s a great program, I think it change its name.... I used it quite often early in my career to get the properties of steam at certain levels and pressures.

__________________
“ When people get what they want, they are often surprised when they get what they deserve " - James Wood
Register to Reply
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 31283
Good Answers: 1733
#2

Re: Saturated steam

10/16/2020 4:08 AM

First of all I'll assume that PRV stands for pressure reducing valve, rather than pressure relief valve... Condensate traps are installed where the heat is being used to heat something, as the heat is transferred the condensate forms and must be drained from the system....Your steam transfer lines should be well insulated and have minimal heat loss...

https://www.armstronginternational.com/files/common/technical/870-EN.pdf

https://www.tlv.com/global/US/calculator/steam-table-pressure.html

Any time there is a possibility of overpressure in a system or vessel, there must be a safety relief valve...and it must be tested on a regular maintenance schedule...

__________________
Break a sweat everyday doing something you enjoy
Register to Reply
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 30407
Good Answers: 819
#3

Re: Saturated steam

10/16/2020 4:09 AM

In reducing the pressure and not the temperature of <...saturated steam...> the material goes from saturated to superheat, as any droplets within it will boil to vapour.

A1) Yes, at startup, and trapping the condensate prior to removal is always good practice.

A2) The forum cannot answer that as the specification for the downstream pipework and equipment cannot be seen from here. Bounce the question into the HazOp Study for the proposed change and see what answers come out.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply Score 1 for Good Answer
Guru

Join Date: Jul 2016
Posts: 1073
Good Answers: 73
#4

Re: Saturated Steam

10/16/2020 11:25 PM

The need for a PSV should already be covered on the supply side. However, a failure of the PRV could expose your lower rated piping after the PRV. It will require a PSV rated for the maximum available flow from your higher pressure supply. The cross tie pipe could actually limit the maximum flow, so over design of the pipe could lead you to having to purchase a higher capacity relief valve than necessary. It is also possible that you may have an existing PSV on the low side, but as PWSlack says, we can’t see that from here.

Register to Reply
Register to Reply 4 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

phoenix911 (1); PWSlack (1); rwilliams (1); SolarEagle (1)

Previous in Forum: Steam Line   Next in Forum: Use Nitrogen Cylinders Without Pressure Regulator

Advertisement