Pressure reducing capacity

[remp]

Hello

I have a boiler system in my factory running at 7 bar.
I have a new user requiring 1,000Kg/hr of steam at 2 bar.
I will have to install a pressure reducing station to drop from 7 bar to 2 bar.
My question is will my boiler be delivering an extra 1,000kg/hr at 7 bar or will it be a reduced figure?

Regards
R

 

[LittleInch]

Mass cannot be created or destroyed.

Is the new user in addition to your current users or replacing some other users?

If the former add the mass, if the latter substitute one for the other.

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

 

[remp]

Hi LittleInch
The new user is brand new, adding to existing users.
Is the mass flow rate (kg/hr) the same either side of the PRV?

R

 

[LittleInch]

YES.

For any steady state system mass in = mass out.

https://en.wikipedia.org/wiki/Conservation_of_mass

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

 

[RVAmeche]

Yes, your boiler will need to generate an additional 1,000 kg/hr if all other users have stayed the same. The only difference is that additional energy was used to make generate steam at 7 bar instead of 2 bar for this user. Your pressure reducing station will drop the pressure to this user (reducing energy) but the mass flow rate will stay the same.

This is different from compressed air systems for example, where there can be significant confusion between volume based flow(CFM) and mass based flow (SCFM).

 

[Bahador_eshghi]

Dear @remp
please be noticed about steam temperature in addition to pressure, if your new device require colder steam you have also reduce its temperature.
in this condition a specific kind of valve with ability to inject water can help.

At the other hand you have to check the temperature reduction due to pressure reduction itself!
for example if your current boiler is generating steam at 7 bar and saturate condition (temp=164 deg C), then reducing pressure to 2 bar by a pressure reducer valve will reduce the temperature to 120 deg C (by considering Iso-Enthalpy process), 40 degree less than original steam.
regards

 

[LittleInch]

Rvamech.

Your last para is incorrect. Both of those units are volume. One might be at a different pressure or temperature but they are both volume (cubic foot).

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

 

[RVAmeche]

LittleInch,

Fair enough, however due nature of the unit (standard temp and pressure), it allows you to convert to mass flow easily since it's actually a unit of molar flow rate. ACFM is meaningless without pressure and temperature. CFM is useless because it could be ACFM or SCFM and you need to get more information.