NNI/PSA NITROGEN GENERATORS

NNI Is A Worldwide Leader In PSA Technology

Here's How It Works
The technology is called PSA or Pressure Swing Absorption. These generators are incredibly reliable for higher purities, generating nitrogen up to 99.99% purity. There are two different techniques, the Mono-Bed and the Dual-Bed systems. In each system you have a prefiltration that includes filters that remove particulates down to 0.01 micron at 99.99% efficiency and all trace amounts of oil vapor. After each bed you have a final sterile air filter to clean the air up before it moves on to your operation.

The way nitrogen is produced is in each carbon bed the air pressurizes in cycles. Inside each bed is a carbon molecular sieve. At higher pressures this CMS has a higher affinity for oxygen and trace amounts of water vapor. This allows the nitrogen molecules to pass through creating a stream of nitrogen up to 99.99% pure. After a set time the pressure is released, the oxygen vented into the atmosphere and the cycle begins again.

In a dual bed system two beds work in tandem, where one is always cycling nitrogen through. There is very little interruption in the generation. In a mono bed system, as you can guess, there is only one cycle so the lag between cycles is evident. This is where the Nitrogen Storage tank as seen above comes into play. It acts as a buffer in between cycles so your drop in production isn’t as evident.

The compressor module, which can be lubricated or non-lubricated, along with its associated motor and controls, is included unless the customer has available plant air to supply the PSA system.

The refrigerated dryer module provides the air treatment for the PSA system. This module, consisting of a surge tank, refrigerated dryer and filters, ensures that the PSA adsorption towers receive only clean and dry compressed air, as required for optimum operating efficiency. Oil and water vapors are converted to liquids and aerosols across the refrigerated dryer's condenser. The liquids are mechanically separated out and the aerosols are removed by a coalescing filter.

The PSA module utilizes NNI's proprietary state-of -the-art pressure swing adsorption (PSA) technology. Two ASME coded pressure vessels are specially charged with carbon molecular sieve (CMS). A solid state programmable controller simply operates the process valves on a cyclic basis, with built-in logic for automatic stop/start. NNI production and purity remain constant, regardless of flow rate peak demands, utilizing an automatic flow control valve. A continuous monitoring oxygen analyzer, with alarms and shut-down, is standard equipment.

Mono-Bed Models
Ranging in flow rate from 200 SCFH to 1200 SCFH @ 99.5% nitrogen purity, the Mono-Bed series of nitrogen gas generator meets the requirements of a large number of industrial applications where the need for an on-site, on-demand nitrogen gas generator is established but the flow rate is moderate. Where supplied nitrogen gas is unavailable or unduly expensive due to regional pricing or delivery difficulties, the Mono-Bed PSA on-site nitrogen generator is a viable solution.

The NNI standardized series of nitrogen generators, which can be designed to include such options as booster compressors, de-oxo catalyst modules, oxygen analyzers, and/or outdoor/freeze protection packages, to meet customer requirements, has long been a preferred solution for many nitrogen gas applications.

......NNI Mono-Bed Performance SCFH of N₂at % Purity:
..Model	95%	96%	97%	98%	99%	99.5%	99.9%	99.95%	99.99%
..MB 1	130	115	103	90	72	60	43	38	14
..MB 3	260	230	207	180	143	120	87	77	27
..MB 5	390	345	310	270	215	180	1,30	115	41

Dual-Bed Models
NNI has designed a series of standardized dual-bed systems with built-in features to optimize the performance of the units, while keeping capital costs to a minimum. With flow rates from 1,200 SCFH to 4,000 SCFH @ 99.5% nitrogen purity, this Dual-Bed series of models picks up where the Mono-Bed series ends.

One of the most important of the economy features of the Dual-Bed series is the standardized sizing. All of the PSA vessels utilized on this Dual Bed line are of ASME coded, in-house manufacture, allowing for the elimination of both vendor vessel manufacturing cost mark-ups and freight charges to transport the vessels from the vendor upon their completion.

While customized options such as booster compressors, de-oxo catalyst modules, high-purity oxygen analyzers and outdoor/freeze protection packages are available for these units, the basic design is a standard one, making design, manufacture and delivery as efficient and expeditious as possible, while, at the same time, containing capital expenditure.

......NNI Dual-Bed Performance SCFH of N₂ at % Purity:
..Model	95%	96%	97%	98%	99%	99.5%	99.9%	99.95%	99.99%
..DB 5	694	630	570	499	416	345	240	204	141
..DB 10	1387	1259	1140	998	831	689	480	409	281
..DB 15	2081	1889	1710	1496	1247	1034	720	613	421
..DB 20	2774	2518	2280	1995	1663	1378	960	817	561
..DB 1200	2850		2200	1894	1490	1200	736	532	284
..DB 1600	3845		2975	2555	2010	1600	992	714	378
..DB 1900	4516		3394	3000	2360	1900	1178	852	452
..DB 2500	6022		4659	4000	3148	2500	1571	1136	602
..DB 4000	9618		7442	6388	5028	4000	2480	1769	943

Catalyst De-Oxo Units
NNI catalyst de-oxo skids can be added to our PSA systems, reducing oxygen concentrations to 10 ppm or less and providing a nitrogen purity of 99.999%. The de-oxo utilizes a palladium catalyst bed and a small stream of hydrogen to combine with the remaining oxygen in the feed product stream to form water. The water is then separated by a Desiccant Tower Dryer to regain the 40ºF dewpoint at pressure. Residual hydrogen carryover is closely controlled to within 0.2% by the use of a PID controller. This de-oxo catalyst unit is completely automatic and alarm setpoints and shutdown capabilities are supplied as standard features.

The addition of a NNI de-oxo catalyst module allows our PSA Nitrogen Gas Generating Systems to be utilized for a number of applications in industry calling for the use of high purity nitrogen, formerly only available by means of costly supplied nitrogen.

Booster Packages
NNI Offers customized booster packages designed to specific customer requirements. Any specific product pressure requirement exceeding the standard NNI nitrogen output pressure can be met by the addition of a custom designed booster package. These booster packages provide the customer with specific additional output pressure to meet the application requirement. Depending on the specific application and optimum pressure required, NNI will source a proper nitrogen product booster compressor and integrate it to the system. Several high pressure storage facility options are also available to accumulate and hold in reserve a customer's peak nitrogen flow rate for on-demand availability. If desired or required, NNI will provide a high pressure cylinder-filling station, in conjunction with the high pressure nitrogen product booster.

Custom Designed Units
In addition to their standard equipment lines, mono-bed and dual-beds, NNI has many years of experience in the design and manufacture of custom packaged PSA nitrogen generating systems. Large flow rates, exceeding that of the largest standard dual-bed model, can be met by custom designed packages. Specific design features to accommodate hazardous environment installations, extreme weather conditions, redundancy considerations and unique application requirements are available. NNI's engineering and manufacturing staff has addressed and solved many challenging project requirements with the development of uniquely designed equipment. NNI has a dedicated knowledgeable staff ready to lend their support to identify and overcome unique project challenges. Our custom designed systems can be found worldwide, providing dependable on-site, on-demand nitrogen gas supplies to a wide variety of industries.