Thermal relief valve calculaiton 1

[clinar]

As required by the API RP 520, I need to know the way to calculate the thermal expansion coeficient per ºF for a given chemical product.
Can you help me?

 

[butelja]

Measure the density or specific gravity of the product at 2 known temperatures. The relative change will give you the expansion coefficient. For reference, most oil based products have a coefficient on the order of 0.00055 / °C.

 

[rusman]

You can refer to Perrys Chemical Engineers' Handbook. Or alternatively you can refer to the table in API RP 520, for the given specific gravity/density of the product.

Or you can also refer to the Heat Transfer handbook by Kern to name a few.

API Technical Databook will also give some figure.

Hope this help.

thanks
rusman
process

 

[25362]

Be careful when using the rule-of-thumb 0.00055/C value. In design, better go to tables. For example, pentane's beta coefficient @ 25C is 0.00164/C three times the one above. Benzene's beta is 0.00114/C, and octane's 0.00116/C, double the ROT value. Crude oil's beta = 0.00096/C between 25 and 120C.
beta = (1/V) (dV/dT)
Glycerine is at 0.00052/C. Water, as usual, behaves in an unusual way below 4C. Tabulated beta for water @ 25C: 0.000256/C.

Isothermal compressibilities, kappa = - (1/V) (dV/dP) would help in estimating the pressures developed per degree, on heating a packed liquid, by dividing beta by kappa.

For example, for octane kappa @ 25C is 0.00128/MPa. Thus the developed pressure at this temperature level would be : 116/128 MPa/C = 0.9 MPa/C =
9 bar/C. For tetradecane @ 25C: 87/91 x 10 = 9.6 bar/C. For water @ 25C,
(25.6/45) MPa/C = 0.57 MPa/C = 5.7 bar/C.

I hope the above is helpful.