Features of PSA Nitrogen Generators
[dropcap]If you’ve decided to make the switch to on-site nitrogen production, the next step in your process would be to find a nitrogen generator supplier and discuss your businesses’ needs in order to assess which unit is best for your process.[/dropcap]
Experienced nitrogen generator suppliers will review the operations your business partakes in on regular basis, evaluate the process you currently use (cylinders; dewars; bulk liquid; etc.) as well as several other factors. Pressure Swing Adsorption Nitrogen Generators can be extremely economical for a variety of businesses. Applications that are best suited to PSA (Pressure Swing Adsorption) generators are: snack food packaging, bottling (wineries), laser cutting with nitrogen, tank blanketing, tire filling, power stations, Injection Molding (Gas Assist), fruit storage, beer dispensing and mine fires. However there are several additional applications that can benefit from PSA generators.
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.
Contact Compressed Gas Technologies for more information on nitrogen generators (PSA).