Different methods to generate gas
There are two basic ways to generate nitrogen on site, and one way to generate oxygen on site. Nitrogen can be generated on site using two different methods – membrane and PSA (pressure swing adsorption). On Site Gas Systems utilize both technologies, so in each case we assess your individual circumstances and make a recommendation as to which option is right for you. With oxygen generation, unlike nitrogen, there is only one method to generate on site oxygen, and this is via PSA technology.
How it works:
Membranes are a series of hollow fibers with holes in their walls small enough that O2 molecules will exit through them under pressure. These same holes, however, are too small to accept N2 molecules. By forcing air down the fiber, the smaller O2 molecules escape and the N2 molecules are captured at the other end. The air in the membrane is usually heated to excite the molecules and increase the chance that they will permeate through the holes.
We use compressed air to pressurize a vessel, filled with either carbon or zeolite, which separates molecules by physical composition or structure. By forcing air into the vessel, either N2 or O2 molecules get trapped, while the other gas floats free. Pressure is released to draw off the O2 or N2 molecules which are collected in a tank. A pressure release valve vents the captured molecules of the unwanted gases into the air, where they immediately combine back to ambient percentages. With our systems, we use two sieve beds that work at opposing ends of the cycle to provide a consistent flow of the desired gas.
General PSA system layout – Nitrogen
General PSA system layout – Oxygen
High Pressure PSA system layout – Nitrogen