PSA Nitrogen Gas Generator

Key Features

Comparison

One of the most popular application of Pressure Swing Adsorption or P S A Technology is in the operation of Nitrogen Generators. This Process is based on the selective adsorption phenomena of gas molecules. In this case it is carbon based Molecular Sieve (C. M. S.) The process works like this, in Pressure Swing Adsorption system as soon as compressed air is entered through an adsorption tower filled with Carbon molecular sieve the molecules of gases like oxygen, moisture & other undesired gases are adsorbed on surface of the adsorbent. While Nitrogen that is not adsorbed passes out of adsorption tower.

It is then collected in a surge vessel. For continuous flow of nitrogen two Adsorption towers are installed. They are interconnected with Auto change over valves. These Auto change over valves are controlled by PLC in the control panel. As the saturation of one tower with oxygen gets completed, in built mechanism makes the process automatically switch to another tower and thus the nitrogen production remains continuous. Nitrogen has a wide range of industrial application primarily to reduce or eliminate altogether oxidation in raw material and food processing. Additional usages can include medical, tyre-filling, swimming pool, sanitation, photo development, etc. In effect it means where oxidation is a problem then a Nitrogen system is the solution.

PSA Process for Nitrogen Generation

Key features of PSA Nitrogen Generator:
There are an enormous number of variety available depending on the user's requirements of purity, space constraints, economics etc. A brief of the features that a PSA Nitrogen Generator incorporates is given below:

• Purity: 99.5% purity nitrogen can be produced at rates as low as 200 Standard Cubic Feet per hour (5 Nm3/h) or as high as around 1000 Nm3/hr (38,000 Standard cubic feet per hour). Also Nitrogen at purity of 99.999% can be effectively produced by a two-step process. That involves a 99.5% purity PSA combined with a "de-oxo" unit that reduces residual oxygen to the required level.
• Delivery pressures: Typically delivery pressures can come in the range of 6 to 7 Bar(g) (87 to 102 pounds per square inch of pressure. More higher pressures are also obtained with the aid of booster compressors like pressures upto to 240 barg (3500 psig).
• Bed type: Mono-Bed nitrogen gas generator the flowrate ranges from 200 SCFH - 1000 SCFH @ 99.5% nitrogen purity, while the Dual bed comes with flowrates of 1200 SCFH to 6000 SCFH @ 99.5% nitrogen purity.
• Wide range of dew points: Can range from: - 45^oC to 600^oC

Comparison of PSA with Membrane separation with respect to PSA Nitrogen generators:

PSA	Membrane Separation
Suits Critical Applications Requirement of compressed air is lower More tolerant to ambient temperature swings PSA offers more nitrogen capacity as the purity consideration goes higher. For e.g. as purity is increased from 95 to 99% capacity drop will be 45% (example 8 scfm will drop to 4.4 scfm).	Best suitable for Critical Requirements Compressed air requirements are higher than PSA systems Less tolerant to ambient temperature swings Capacity for production of nitrogen will drop 60% when nitrogen purity is increased from 95% to 99% (for example 8 scfm will drop to 3. 1 scfm)