Nitrogen is al around us. It is the biggest component of the air we breathe, but we don't use it. In this article we take a look at some of the many things it can be used for.
When you need a supply of an industrial gas like nitrogen and oxygen for your business, the first solution that probably comes to mind is to get it delivered to you in bottles. However, there are a lot more, possibly more efficient, options to consider. In this article we will talk about obtaining nitrogen in bottles, but also in liquid form and by making your own with a PSA or membrane nitrogen generator.
A first option is to buy bottles of nitrogen from a nitrogen producer. This process is very straightforward: You order the desired nitrogen quantity for your application and the supplier delivers it to you in big heavy bottles. N2O2, generated by a cryogenic nitrogen plant, is converted into a gas and bottled under very high pressure (300 bar). This means a lot of nitrogen gas can be stored in a relatively small bottle. However, in order to withstand the high pressure, the walls of the receiver are very thick. These bottles are placed in a rack and get transported to their destination on trucks. After use, the emptied bottles are collected by the gas company.
Liquid Bulk Nitrogen
A second option is to install a liquid nitrogen storage tank on your site and get it filled up periodically by a gas company. These tanks can either be rent (from said gas company) or bought and an evaporator is required for you to be able to use the nitrogen in it. An evaporator transforms the liquid nitrogen into usable nitrogen in gaseous form. Just like nitrogen in bottles, it gets transported to your company by trucks. However, in this case, the nitrogen is transported in a big thermally insulated tank truck. The liquid nitrogen is then pumped from the truck into your insulated storage tank. It is also possible to order liquid nitrogen in smaller cans for smaller consumptions, these small tanks are known as dewars. Also, just like bottled nitrogen, liquid nitrogen is produced by a cryogenic nitrogen plant.
On Site Cryo Production
When your nitrogen consumption is extremely high, a gas company might install a (small) cryogenic nitrogen plant at your production site. This is the same type of nitrogen generator as the one used to create the nitrogen that gets transported in bottles and tank trucks. You can read more about cryogenic nitrogen generators in the article below. (link to article cryo)
As opposed to the previous methods of getting nitrogen, generating your own does not involve the cryogenic process. Its extreme temperatures are nowhere to be found in membrane or Pressure Swing Adsorption (PSA) nitrogen generators. These generators have to separate the air into its components in a different way. PSA and membrane are two very different technologies, however they both need a stream of compressed air in order to work.
Because these technologies are so different from cryo, the composition of the resulting gas will be different. Cryogenic nitrogen gas has a fixed, very high purity level. The nitrogen purity of commercially available generators can be adjusted to match your preferences, but gaining the same level of purity as cryo generated nitrogen is extremely inefficient. With these machines, higher purity levels require more power, resulting in higher running costs. That being said, for most applications the purity levels of cryogenic nitrogen are overkill. You can read more about nitrogen purity here.
Take a Closer Look at PSA and Membrane Generators
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