5 replies to this topic

[premjagan]

Dear sirs,

                           How to calculate the energy losses occured through the control valve in terms of cost?

[Steady]

'Energy loss' is not the right word for the contol valve. Control valve is meant to control the pressure-flow dynamics of the system by adjusting the valve opening so i am not sure why you saying its an energy loss !? Please explain what you meant by this.

 

I am not an experienced process engineer but I think loss of pressure across the control valve can be considered as the energy lost by the system. You can calculate the cost (pumping/compression) to get the fluid back it to its inlet pressure.

[Jiten_process]

I really could not control my curiosity but to ask you why you have come up with a question of so called energy loss through control valve. 

 

anyways, as steady said it is not exactly a energy loss. Its like you are burning a petrol to run a car. It is a loss of fuel but you need it to run the car. 

 

But anyway, if you want to calculate that "loss".  Theoratical way is get the pressure drop value across the control valve. Calculate the pumping power required to overcome that amount of resistance (pressure drop). This can be calculated by simple BKW pump formula and there instead of system DP, use the DP across control valve. Then take standard utility cost at your region and equate it with power requirement calculated to overcome DP across control valve. That might give you some logical figure. I guess this is the best "basis" to know about that "loss". 

 

good luck...

[S.AHMAD]

Hi

1. Energy loss probably is not the right term.

2. Energy consumed probably is more representative for control valves.

[premjagan]

Dear sirs,

                           Actually, boiler feed water flow control valve let down the pressure from 120 kscg to 108 kscg.The supply from boiler feed water is from Turbine driven pump, I just want to decrease the turbine speed, let open the control valve fully.Then modify the Drum level control from feed water flow controller to turbine RPM.So i want to calculate the energy gain through this modification.This is why, i mentioned as ENERGY LOSS.

[latexman]

Calculate the power draw of turbine pump for the two cases - speed not decreased and speed decreased.  Subtract the two power draws.  Multiply by time to get energy savings.  Multiply by the cost of energy.  Finished!