| Re: Pressure Swing Absorption, 95% O2?
PSA units are of great interest but just a word of caution. IMHO there are three methods of producing oxygen with the pressure swing absorption PSA or VPSA method being the only practical end user option.
There are however liabilities and huge responsibilities in self generation for breathing purposes that should be investigated before going down this route.
The practical method using a synthetic zeolite mixture (molecular sieve) for breathing purposes would require an adequate method of analysis before I would be happy and would suggest a paramagnetic means and not a galvanic fuel cell as means of analysis at the very least. Further a minimum double rack system for >99% purity and not allow the industrial <95% PSA plants that are not 100% effective, and go off purity surprisingly often. Frankly they are not suitable for diving and should not be used if at all possible.
In remote areas military field hospitals for example there is a case for use, then the supplier responsibility comes into play. For medical oxygen use of 95% has been deemed adequate for use but this is more for production capability than patient.
The process gas needs to be analyzed accurately, there is no scope for variance or error here. When I pay for a product I expect it to be what it says on the label. Oxygen for breathing purposes is spectrographically analyses for purity and certified. The PSA produced oxygen is not.
Secondly PSA produce oxygen is produced at a very low pressure <2 barg (25psig) So in addition to the huge amount of electrical power wasted in producing the product in the first place you then have to compress the low pressure oxygen up to high pressure with all the associated risk and concerns involved in compressing high pressure oxygen. The risk for example on a live aboard storing high pressure oxygen is less than that of oxygen generation but practicalities may preclude storage.
Jpeg is a 11,000l/min (400scfm) PSA plant (we built earlier) 700Kw of low pressure air is used to generate the oxygen. Iain Middlebrook. |