Low-Temperature Separation Systems (Hydrate Formation)

A third phenomenon that must be considered is the possible formation of hydrates when water is present in the natural gas stream. Technical Data used in the field explained in petroleum courses in Islamabad.  Hydrates are materials that have fixed chemical compositions but exist without chemical bonds and are called “clathrates.” They form a solid similar to snow at temperatures above 32°F (the freezing point of water) when the gas is under pressure.

They appear to be hydrates of a mixture of the component gases and not a mixture of the hydrates of the individual gases. The hydrates form at a temperature that is characteristic of a given gas mixture rather than at the hydrate temperature for the individual components in the mixture. The hydrates normally include several water molecules for each hydrocarbon molecule so that the presence of liquid water is generally considered necessary for the formation of hydrates in sufficient quantity to cause plugging of a line, valve, etc. Turbulence accelerates the formation of hydrates and for this reason they frequently occur downstream from valves, regulators, chokes, orifice plates, sharp bends, etc. Fig. 14.4 can be used to estimate hydrate-forming conditions for different natural  gases. Caution also must be used in Fig. 14.4 because, as shown by the different hydrate-forming lines for O.&gravity gases, there can be considerable difference in the hydrate temperature of gases of the same gravity. Some more details of petroleum courses in Islamabad are as under.

If the composition of the gas is known, a composition dependent calculation of the hydrate temperature, either by hand3 or by computer, I will give a much better estimate  of the hydrate temperature than will  A necessary condition for hydrate formation is the presence of liquid water. Prediction of the temperature where free water will occur will help identify the first point at which hydrates might form. The chart  gives the water vapor content of sweet [no hydrogen sulfide (HlS) or CO21 natural gas as a function of temperature and pressure. As the temperature decreases at a given pressure the water content required for saturation also decreases. This will result in condensation of liquid water for a saturated gas stream as it is cooled. As an example, suppose a well is flowing 1 MMscf/D of natural gas at 1,000 psia saturated with water vapor but containing no liquid water at 110°F. The gas is cooled to 60°F because of ground and atmospheric cooling. At 1,000 psia and 1 lO”F, the gas contains 80 lbm water vapor/MMscf and at 60°F it contains only 18 IbmiMMscf. One day of gas production will result in the formation of 62 Ibm of free water because of the cooling. Referring if the gas flowing has a specific gravity greater than 0.6, hydrates are likely to form in the flow line at some point of turbulence. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for Pakistani Students who wants to join petroleum courses in Rawalpindi.