Pressure swing adsorption and membrane technologies are popularly applied in nitrogen generation systems today. It helps to continuously generate pure nitrogen from compressed air. Moreover, the inconvenience of changing risky high pressure cylinder as well as interrupting gas supply gets completely eliminated.
Advantageous features of nitrogen generator
Commitment in providing stable long term nitrogen costs
Continuous supply of pure nitrogen is available in minutes (designed to operate for 24/7)
Easy to install ; connect compressed air pipeline to generator inlet and attach generator outlet to the nitrogen pipeline
Flexible – Units are available in basically three forms – as a free standing, skid mounted or fixed in a cabinet unit (selection depends on application)
Highly efficient coalescing pre-filters (automatic drains)
Nitrogen storage tank
Activated carbon adsorption
Final membrane filter (0.01 micron)
Oxygen analyzer is an interesting feature that can be used to open backup supply, process stream, signal remote alarm or completely shut down the nitrogen generating process for protecting downstream equipment
Little maintenance ; Only the filtration cartridges need regular changing
Two technology used in nitrogen generation process
Membrane technology
The membrane in the nitrogen generators separates the compressed air in two streams ;
First stream has 95% – 99% pure oxygen
Second stream includes an amalgamation of oxygen, carbon dioxide and traces of other gases
The compressed air gets separated into component gases, when it is passed through semi-permeable membranes, which has individual hollow fibers in bundles. Each fiber has circular cross section with a uniform centered bore. The fibers are very small and many can be packed in a limited space providing a very large membrane surface region to produce high volume stream.
Oxygen, water vapor and traces of other gases easily seeps into the membrane fiber, gets discharged through permeate port. On the other hand, nitrogen is enclosed within the membrane, flows through outlet port. The nitrogen gas is dry (-58° F) because water vapor also gets filtered through the membrane.
Applications
Food and beverage sectors ; Residual oxygen inside packages can promote bacterial growth that can adversely affect product quality as well as shelf-life. Nitrogen helps to reduce the existing oxygen level, preserving quality and radically enhancing shelf-life.
Chemical sectors ; Many industries use dangerous chemicals for manufacturing products, so blanketing vessels with nitrogen ensures chemical integrity and safety. Nitrogen controls oxygen concentration and moisture inside the vessel preventing the product from getting contaminated, degraded or chemically changed. Ultimately, the chances of explosion get minimised.
PSA technology
Compressed air entering the nitrogen generator includes 78% nitrogen and 21%oxygen. This gas separation process adsorbs oxygen using CMS (carbon molecular sieve). The CMS has great affinity for carbon dioxide, oxygen and water vapor at high pressure in comparison to low pressures. The CMS pressures can be increased and decreased to capture all the contaminants. Thus nitrogen gets passed through as a by-product. De-pressurisation phase of CMS releases absorbed oxygen with other contaminant gases.
Applications
Metal processing ; High temperature can cause oxide formation on surfaces of dies that can alter the shape of newly formed piece. Constant nitrogen supply reduces the contact of oxygen enhancing the quality of final products.
Power generation ; During electrical generation at the gas and oil wells nitrogen blanketing are used to seal the natural gas compressor, which can be dangerous.
Both nitrogen generation technologies are virtually compatible with every machine and procedure to operate accurately, effectively and consistently.