Oxygen is mainly used as the main oxidizing agent oil and gas. However, compressed process air is still used but use of pure gaseous oxygen is preferred as it is more effective. Elimination of inert gases must be transported through the system with air oxidation yields numerous advantages like reduced costs and lesser environment impact.
Substantial boost in productivity
Application of oxygen is known to boost productivity of plants that use air oxidation. In numerous cases, the oxygen enrichment of the process air provides an alternative to intensify the process. It has been observed that capacity increases by 10 and 15 per cent. This kind of productivity can only be achieved by injecting gaseous oxygen into the process air ducting. The cost does not increase significantly. Oxygen supplies are met through onsite generation, liquefied gas supply and pipeline network.
It goes without saying that oxidation steps in petrochemical processes involve use of catalysis. Oxidation takes place in the heterogeneous gas phase on a solid catalyst surface. It is also carried out in the homogeneous gas/liquid phase through the admission of a gas stream containing oxygen. In the petro-chemical industry, the oxidation of liquid p-xylene to terephthalic acid, crucial for polyesters, is very important. In this process, oxygen enrichment is used for boosting capacity.
Use of nitrogen in inerting procedures
In the oil and gas industry, nitrogen is used chiefly for inerting processes and for various other industrial purposes. Gaseous nitrogen is mixed with other gases as diluent with H2 for hydrogenation applications as it is done in the purification of terephthalic acid. Hydrogen and nitrogen mixtures are applied for activating catalyst materials such as hydrogenations. Cryocondensation is expected to become more popular in future. It involves cooling of gases by cryogenic liquid nitrogen plant. And, the purpose of inerting is to remove atmospheric oxygen, moisture or combustible gases with nitrogen.
Use of nitrogen for safety measures
- Safe startup and shutdown of plants and apparatus
- Prevention of formation of an explosive atmosphere
- Reduction of explosion hazard when combustible liquids are being handled
Three types of inerting
- Dilution purging
- Displacement purging
- Pressure swing purging
Main benefits of using nitrogen include
- It is inert, nontoxic, noncombustible and dry
- Simple to deliver as cryogenic LIN stored in tanks or sourced by users as GAN from customized nitrogen plants or from pipeline systems.