8 replies to this topic

Dear All,

i need help on how to size the control valve. The specifications stated as below:

Fluid: Crude Oil
Fluid State: Liquid
Flow Rate: 160 m3/h
Inlet Pressure: 0.70 MPa G
Outlet Pressure: 0.65 MPa G
Inlet Temperature: 85 Deg C
Specify Gravity: 851.1 kg/m3

Given Cv under Subcritical Flow

Cv = 1.17Q √(SG/dP) whereby

Q = flow rate m3/h
SG = Specific gravity at flowing temperature (water = 1 @ 15 Deg C)
dP = delta P in between inlet and outlet

Kindly help in getting the correct SG. Note that if based on Density_12MB spreadsheet, 851.1 kq/m3 of crude oil at 85 Deg C in equivalent to 799.81 kg/m3. Should i divide by 1000 or leave it as it is (since SG = density of liquid over density of water)?

Once SG is acquired, Cv value can be calculated. Based on Cv value, is there any formula/table in getting the correct valve size?

Kind help is much appreciated. Thanks

[breizh]

Hi Faiz ,
Let you download the MASONEILAN Control valve sizing handbook .
Hoppe it helps .
Regards
Breizh

Dear Breizh,

Thanks for replying my topic. By the way, I've already downloaded the Masoneilan Control Valve Sizing Handbook but still it didn't help much in solving my problem. If you noticed my first post, i need clarification on few parameters there.

Thanks again for giving me the info. Much appreciated.

[shan]

Dear All,

i need help on how to size the control valve. The specifications stated as below:

Fluid: Crude Oil
Fluid State: Liquid
Flow Rate: 160 m3/h
Inlet Pressure: 0.70 MPa G
Outlet Pressure: 0.65 MPa G
Inlet Temperature: 85 Deg C
Specify Gravity: 851.1 kg/m3

<u>Given Cv under Subcritical Flow</u>

Cv = 1.17Q √(SG/dP) whereby

Q = flow rate m3/h
SG = Specific gravity at flowing temperature (water = 1 @ 15 Deg C)
dP = delta P in between inlet and outlet

Kindly help in getting the correct SG. Note that if based on Density_12MB spreadsheet, 851.1 kq/m3 of crude oil at 85 Deg C in equivalent to 799.81 kg/m3. Should i divide by 1000 or leave it as it is (since SG = density of liquid over density of water)?

Once SG is acquired, Cv value can be calculated. Based on Cv value, is there any formula/table in getting the correct valve size?

Kind help is much appreciated. Thanks

Please see the attachment for the Cv / Valve Size table.  20090812104823662.pdf   143.34KB   178 downloads

[demank]

Specify Gravity: 851.1 kg/m3

ndly help in getting the correct SG. Note that if based on Density_12MB spreadsheet, 851.1 kq/m3 of crude oil at 85 Deg C in equivalent to 799.81 kg/m3. Should i divide by 1000 or leave it as it is (since SG = density of liquid over density of water)?

ind help is much appreciated. Thanks

To your first quetion about SG. I use frequently divided by 1000 for simplicity. ALthough if you want more precise, the density value is divided by 998

Edited by demank, 12 August 2009 - 10:06 PM.

Thanks Demank for the info. Should i divide into 1000 or 998 to be precised, still the temperature is based on 15 Deg C right? how if the inlet temperature given was at 85 Deg C. Is there any changes in formulating it?

Another thing, anybody knows the Isoentropic Exponent(Specific Heat Ratio) for Crude Oil? Most of the tabled given on Net are based on Gases, not liquid state as crude oil. Any advise?

[demank]

Thanks Demank for the info. Should i divide into 1000 or 998 to be precised, still the temperature is based on 15 Deg C right? how if the inlet temperature given was at 85 Deg C. Is there any changes in formulating it?

Another thing, anybody knows the Isoentropic Exponent(Specific Heat Ratio) for Crude Oil? Most of the tabled given on Net are based on Gases, not liquid state as crude oil. Any advise?

Hallo,
no matter what the inlet temperature, the spesific gravity is equal to density (kg/m3) divided by 1000 kg/m3.
For spesific heat ratio. that value is for what? of course the term k (Cp/Cv) is only used in gas state.

[demank]

I think you mean critical pressure ratio, rite?
cause to determine maximum allowable pressure difference, you need this value.

critical pressure ratio is a function of (vapor pressure / critical pressure).
Rememver, critical pressure ration is not the same with (vapor pressure / critical pressure).

Thanks Demank for the info. Should i divide into 1000 or 998 to be precised, still the temperature is based on 15 Deg C right? how if the inlet temperature given was at 85 Deg C. Is there any changes in formulating it?

Another thing, anybody knows the Isoentropic Exponent(Specific Heat Ratio) for Crude Oil? Most of the tabled given on Net are based on Gases, not liquid state as crude oil. Any advise?

Hallo,
no matter what the inlet temperature, the spesific gravity is equal to density (kg/m3) divided by 1000 kg/m3.
For spesific heat ratio. that value is for what? of course the term k (Cp/Cv) is only used in gas state.

thanks again bro for the SG clarification.Now i fully understand.

Back to specific heat ratio, if the parameter k (Cp/Cv) is only used in gas state, means that in liquid state as crude oil, the parameter k is void and non-applicable?