# Vapor

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

Vapor is the gas state of a liquid or solid.  Both vapor and gas are basically the same thing.  Gas just happens to be the term normally used.

## Casing Vapor Recovery

The main objectives of a casing vapor recovery system are to

• Minimize back pressure on wells
• Minimize discharge of hydrocarbons and other fugitive gasses to the environment
• Recovery of heat from casing gasses
• Collect hydrocarbon condensate in the gas streams for addition to the sales stream.

In oil fields that are on steam-flood or steam lift, there is an overt effort to maintain a low back pressure on the producing formation.  This is done by keeping the wells "pumped off" and by lowering the pressure in the annulus.

In a system that has steam injected, steam vapor often times will come up through the annulus and will condense in the CVR system.

## Evaporation

The condition that occurs when heat is absorbed by the surface of a liquid and it changes to vapor.

## Liquid Vapor Mixture

Liquid vapor mixture (called a two-phase) of the same substance can coexist at the same pressure and temperature.

## Saturated Vapor

Saturated vapor is a vapor at a temperature of the boiling point on the verge of condensing.

## Superheated Vapor

Superheated vapor is when vapor has absorbed more heat than is needed to vaporize.  It will not condense when small amounts of heat is removed.

## Vapor Quality

The mass friction of a vapor in a liquid vapor mixture in a two-phase liquid vapor regoin is called vapor quality, also called dryness fraction.

### Vapor Quality formula

 $$\large{ x = \frac{m_{vapor}}{m_{liquid \;+\;m_{vapor} }} }$$ $$\large{ x\;<\;1 \;\rightarrow\; }$$ (wet steam) $$\large{ x\;>\;1 \;\rightarrow\; }$$ (dry steam)

### Where:

$$\large{ x }$$ = steam quality

$$\large{ m_{liquid} }$$ = mass of liquid

$$\large{ m_{vapor} }$$ = mass of vapor

## Water Vapor Diffusion

The process by which water vapor spreads or moves through permeable materials caused by a difference in water vapor pressure.