4 replies to this topic

Dear all,

I am new to this forum, was wondering if someone could answer my question below

At present I have a scenario where steam is being reduced from 8 to 5.4 bar and is metered as tonnes used in that area per week. Will I use less tonnage of steam if I was reducing pressure from say 10 bar to 5.4 bar?

Thanks
CLEO

[latexman]

Throttling to a lower pressure is usually treated as isenthalpic. The 5.4 bar steam made from 10 bar steam should have more superheat in it. Therefore , you should use slightly less tonnage.

[S.AHMAD]

Dear all,

I am new to this forum, was wondering if someone could answer my question below

At present I have a scenario where steam is being reduced from 8 to 5.4 bar and is metered as tonnes used in that area per week. Will I use less tonnage of steam if I was reducing pressure from say 10 bar to 5.4 bar?

Thanks
CLEO

Dear Cleo
My understanding is that you may save some steam since the specific enthalpy of steam at higher pressure is higher. A rough estimate shows that if you are currently consuming 1000 kg/h of 8 barG steam, by changing to 10 barG steam you may require about 997 kg/h steam. So some saving could be realized. You may estimate the saving by heat balance or if you have simulation software (such as HYSIS) you may run that simulation.

[VikingUK]

Dear all,

I am new to this forum, was wondering if someone could answer my question below

At present I have a scenario where steam is being reduced from 8 to 5.4 bar and is metered as tonnes used in that area per week. Will I use less tonnage of steam if I was reducing pressure from say 10 bar to 5.4 bar?

Thanks
CLEO

Yes, but you would have to put more energy in to increase the pressure from 8 bar to 10 bar so your total savings would be nil.

[shan]

Dear all,

I am new to this forum, was wondering if someone could answer my question below

At present I have a scenario where steam is being reduced from 8 to 5.4 bar and is metered as tonnes used in that area per week. Will I use less tonnage of steam if I was reducing pressure from say 10 bar to 5.4 bar?

Thanks
CLEO

Everybody agrees 1 ton of 10 bar saturated steam contains more heat duty than 1 ton of 8 bar saturated steam. However, steam consumption is counted as “ton/hr” not “btu/hr”.
Therefore, 1 ton of 5.4 bar steam letdown from 10 bar saturated steam is equivalent 1 ton of 5.4 bar steam letdown steam from 8 bar saturated, although the steam letdown from 10 bar is hotter. You should not expect people pay you more for the hotter steam just as nobody will pay extra energy cost for an over burned Big Mac. Higher steam temperature may result product degradation or faster equipment fouling.
The story will be different, If you have a desuperheater after letdown valve. 10 bar saturated steam will evaporate more BFW and produce more ton of 5.4 bar saturated steam than 8 bar saturated steam will.