Chapter 10H

10 H. Static Pressure Due to Elevation Change, Equations 10.49 and 10.50 Back to Main

This page is used to determine the static pressure due to elevation changes in the line. In actual practice the line may be going uphill or downhill causing a change in potential energy affecting and . Since the gas is compressible and the temperature varies, many models may be used, but the simplest equation is

(10.49)

Where: H = head

= gas relative density

= mean gas temperature

= mean gas compressibility

= pressure at bottom of static column

= pressure at top of static column

A = constant

Equation (10.49) also can be written in the form

(10.50)

Where:

To calculate the static pressure due to elevation changes the Gas relative density, Average gas compressibility factor, Wellhead pressure , Elevation change, and Average gas temperature must be entered into their entry space. To do so use the mouse to click the courser in the entry spaces and input the data. Once this has been done, select Run to execute the solution. For more information, please refer to Example 10.9 in the book Gas Processing and Conditioning Volume 1.

Gas relative density is the density of the gas divided by the density of air or the molecular weight of the gas divided by the molecular weight of air at atmospheric pressure.

(1.2)

Average gas compressibility factor is the measurement of how much the gas at a given temperature and pressure deviates from ideal-gas behavior. This is the same as the mean gas compressibility.

Wellhead pressure is the pressure at the top of the static column.

Elevation change is the pipe length in the vertical direction from beginning to end.

Y = elevation change

L

Y

X

Since the gas is compressible, the temperature varies. In this equation, an average temperature is used. The average temperature is also termed as the mean temperature.

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