Nitrogen content of natural gas

Nitrogen is taken from air or from the nitrogen content of natural gas. This is carried out by low temperature fractionation of air, which is preferred when pure oxygen is required as an oxidizing agent in the production of synthesis gas. Alternatively air is employed directly in the production of synthesis gas and the oxygen is removed by the to be oxidized reaction partners. 

They have also shown that it is possible to reduce the nitrogen content of natural gas from 18% to less than 5% with a 90% recovery of methane. 

Helium and Natural-Gas Systems Separation Helium is produced primarily by separation of hehum-rich natural gas. The hemim content of the natural gas from plants operated by the U.S. Bureau of Mines normally has varied from 1 to 2 percent while the nitrogen content of the natural gas has varied from 12 to 80 percent. The remainder of the natural gas is methane, ethane, and heavier hydrocarbons. 

Applicable quantities of nitrogen or helium in the natural gas should lower the saturated water content of the gas.11 Again, limited data are available, but the decrease could be as much as five percent on Figure 16-18 and ten percent on Figure 16-19. 

Most of the work on catalytic combustion applications has dealt with the use of natural gas, since this is a clean gaseous fuel with low nitrogen content. However, a number of other hydrocarbon fuels have been investigated as well [99-101], such as propane, gasoline, diesel fuel, and kerosenes. 

With the nitrogen content of subquality natural gas, it is another story. The two principal methods in current but limited use are low-temperature, or cryogenic separation or distillation, and selective adsorption. The former is judged too costly the latter is starting to make inroads. Membrane separations wait in the wings. More on the general subject of upgrading natural gas follows. 

Depending on the deposit, there are large differences in the composition of natural gas. It is often the case that heavier natural gas, i.e. rich in higher hydrocarbons, can be found in deep reservoirs and vice versa. Increased helium contents are often accompanied by high nitrogen content. 

In case the nitrogen content of the natural gas falls below 25% by volume, the process described above is no longer suitable for the separation of nitrogen with the required volume and purity. In such cases, a process with pre-separation column (10) (see Fig. 7.23) is applied. Here, in the first heat exchanger the feed gas is... 

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