High Pressure PSA Nitrogen Generator
High Pressure PSA Nitrogen Generator How exactly do Pressure Swing Adsorption Nitrogen Generators Work? PSA technology utilizes two towers filled with carbon molecular sieve (CMS). Compressed air enters the bottom of the tower and flows up through the CMS. Oxygen and other trace gases are...
High Pressure PSA Nitrogen Generator
How exactly do Pressure Swing Adsorption Nitrogen Generators Work?
PSA technology utilizes two towers filled with carbon molecular sieve (CMS). Compressed air enters the bottom of the tower and flows up through the CMS. Oxygen and other trace gases are preferentially adsorbed by the CMS, allowing nitrogen to pass through. After a pre-set time the tower automatically switches to the regenerative mode, venting contaminants from the CMS. CMS differs from ordinary activated carbons as it has a much thinner range of pore openings. This allows small molecules i.e. oxygen to penetrate the pores and separate from nitrogen molecules which are too large to enter the CMS. The larger molecules by-pass the CMS and emerge as nitrogen gas. Specific features of PSA nitrogen generators are that the capital cost is low relative to the purity the unit will produce. Purity for PSA units are typically high (above 99%). From a cold start, PSA nitrogen generators will take 30 minutes to 12 hours depending on purity. PSA generators typically operate at maximum delivery pressure without post compression - typically less than 125 psig and are better suited for lower temperature operations. Optimum temperature is between 40 deg. F and 95 deg. F. PSA generators are expected to work efficiently and effective for approximately 10 -15 years with the proper maintenance adhered. Maintenance of the units would include changing the filters: every 6mos. - 1year; changing the O2 sensor (yearly); a valve rebuild every 2 years; an actuator rebuild or replacement (every 2 years); muffler changes (yearly); and topping up the CMS as required. PSA nitrogen generators have 8 -12 switching valves with actuators depending on design. The cycle time is typically less than one minute which adds up to over ½ million cycles per year so make sure the valves used are high quality, high cycle valves. If you see the possibility of an increase in the future, research new modular units that can be expanded simply by adding additional "banks", compared to traditional twin tower designs. Installation is straight forward. A connection from your house compressed air system to the nitrogen generator is required, as well as an electrical supply. Depending on the size of the PSA system, PSA nitrogen generators are shipped without the CMS and have to be filled on-site by experienced personnel. As for health and safety issues, a Material Safety Data Sheet (MSDS) is required for CMS and nitrogen with possible training required. The noise level that a PSA generator operates at is less than 85 decibels - however hearing protection may be required depending on the size of the nitrogen generator and the individual business' Healthy and Safety Departments. Are PSA nitrogen generators right for you? You now know the features, how they work and which industries applications can benefit from a PSA generator. Please always ensure that when purchasing a nitrogen generator you do some research on the supplier you are dealing with to ensure that they have your company's best interests in mind (i.e. have dealt with like businesses and have recommended the same unit) and that they are reputable and have been in the business for at least 5 years. ContactCompressed Gas Technologies for more information on nitrogen generators (PSA).
Nitrogen PSA Generator Systems use the basic principle of passing air over a bed of engineered adsorbent material, which bonds with oxygen, leaving a rich stream of nitrogen gas to exit.
The adsorption separation is accomplished by the following process steps:
FEED AIR COMPRESSION AND CONDITIONING
The inlet (ambient) air is compressed by an air compressor, dried by an air dryer, and filtered, before entering the process vessels.
PRESSURIZATION AND ADSORPTION
The pre-treated and filtered air is directed into a vessel filled with Carbon Molecular Sieve (CMS) where the oxygen is adsorbed preferentially in the CMS pores. This allows concentrated nitrogen, with an adjustable purity, (as low as 50 ppm O2) to remain in the gas stream and flow out of the vessel. Before the full adsorption capacity of the CMS is reached, the separation process interrupts the inlet flow, and switches to the other adsorber vessel.
The oxygen-saturated CMS is regenerated (the adsorbed gases are released) by means of a pressure reduction, below that of the previous adsorption step. This is achieved by a simple pressure release system where the exhaust (waste) gas stream is vented from the vessel, usually through a diffuser or silencer and back into safe surrounding atmosphere. The regenerated CMS is refreshed and can now be used again for the generation of nitrogen.
ALTERNATING VESSELS or SWING
Adsorption and desorption should take place alternately at equal time intervals. This means that the continuous generation of nitrogen can be achieved by using two adsorbers; while one is adsorbing, the other is in regeneration mode; and switching back and forth, provides for a continuous and controlled flow of nitrogen.
Constant nitrogen product flow and purity is ensured by a connected product buffer vessel that stores the nitrogen output. This can be designed for nitrogen purities up to 99.9995% and pressures up to 150 psig (10 bar).
The result product is a constant stream of On Site produced, high purity Nitrogen, at a cost significantly below the price of liquid or bottled gases.