×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

pressure-temperature

pressure-temperature

pressure-temperature

(OP)
Dears

we have boilers produce steam with 7 bar and we use it for Dairy application we have PRV's to get 4 bar, 1 bar and 0.3 bar so please what is the Corresponding temperature for each pressure


Thank you

RE: pressure-temperature

Steam tables http://www.thermopedia.com/content/1150/

Note that P in the table appears to be absolute pressure, hence 1.3 bara = 108C, 2 bara = 120C and 5 bara = 153C all based on saturated steam

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: pressure-temperature

Assuming a throttling process with no loss of heat, the temperature will fall as pressure is decreased, but the steam will become superheated as the pressure falls. You need to determine the enthalpy for saturated steam at the initial pressure (absolute) and then use that enthalpy to determine the temperature at each of the lower pressures.

For example, if 7 bar is a gauge pressure (barg), the absolute pressure will be approximately 8 bara. The enthalpy at 8 bara is approximately 661.2 kJ/kg. Using this enthalpy, the approximate temperature at each pressure is as follows:

5 bara (4 barg) ==> 160 deg-C

2 bara (1 barg) ==> 150 deg-C

1.3 bara (0.3 barg) ==> 147 deg-C

Best of luck!

RE: pressure-temperature

(OP)
Thank you stgrme

please why we consider initial steam from the boiler as saturated steam and the steam after PRV's as superheated steam

Regards

RE: pressure-temperature

Steam at the PRV's outlet keeps approx the same enthalpy as at the valve's inlet. Being the steam pressure reduced, this may translate in a superheated steam or in a higher steam quality (depending on upstream conditions and amount of pressure reduction)

RE: pressure-temperature

Please pardon me. I assumed that the steam from your boiler was saturated since you did not give a temperature. However, the procedure for determining the temperature at each pressure is the same as I had indicated in my previous post. Determine the enthalpy of the steam at 8 bara and use this enthalpy along with each pressure to find the corresponding temperatures.

Please note that in my previous post, I incorrectly stated that the enthalpy of saturated steam at 8 bara was 661.2 kJ/kg. This enthalpy is actually for saturated liquid. The correct enthalpy for saturated steam is 2768.3 kJ/kg. Also note that the temperatures at each pressure I noted in my previous post are correct.

Best of luck!

RE: pressure-temperature

Quote:

please why we consider initial steam from the boiler as saturated steam

OP never stated steam from boiler was superheated, ergo others will ASSume only dry saturated steam is being delivered.

As LittleInch noted, providing more information yields better answers!

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources