Pressure Swing Absorption (PSA) is a technology used in order to separate certain gases from a mixture of gases under pressure according to the species molecular characteristics and similarly for an absorbent material. It runs at a near ambient temperature and can differ considerably from cryogenic distillation techniques of gas separation. Specific adsorbent material such as activated carbon, molecular sieves etc are then used as a barrier to preferentially absorb the targeted gases at a high pressure. The process then continues by swinging to low pressure to desorb the material.
While Membrane technology on the other hand refers to a number of different filtration processes used to separate substances. Membranes are used as a filter within the separation process within a variety of applications both industrial and scientific. This membrane technology creates a barrier separating two fluids and allowing only certain substances to be delivered across the membrane.
So why choose PSA over Membrane?
Where there is a need for both cost and efficiency, a PSA system is ultimately the technology of choice, with purities above 99.9% it is the first choice for a nitrogen gas generator. While membrane may be an attractive choice when considering both the initial investment and cost of operation the media required is more expensive than the CMS needed for a PSA system. Additionally, as the purity increases, the compressed air requirements rise faster for membrane technology compared to PSA, which means that as both capacity and purity rise PSA technology overtakes as the more cost-effective option.
PSA nitrogen generators have been specifically designed to provide the same flow rates throughout their operational lifespan, these generators are included with a mass flow controller and a built-in oxygen analyser to ensure the purity of nitrogen on the output.When using modular technology several generators tend to work in tandem in order to produce these high flow rates. These systems are able to meet the large demands of nitrogen gas required in serval manufacturing industries such as:
· Oil, Gas & Petrochemical
· Power Generation
· Food & Beverage Production
· Metal Fabrication & Processing
These generators are very reliable, and the CMS used within them has been designed to have substantial lifespan. The limited number of parts used within these generators are also easily replaced. A key benefit of PSA is that this technology delivers you the lowest air-to-nitrogen conversion ratio with compressed air being the main component in the overall operational costs. The repair costs of a PSA nitrogen generator are minimal compared to the thousands spent on membranes.
PSA generators are less vulnerable to both oil and water compared to membrane. This leaves the use of air dryers for the compressors feeding membrane systems more essential than it is for PSA units. Should a dryer fail at the source it could cause damage to the production capacity of the membrane. In the event that water damages occur within the membrane technology the only repair option is to allow it time to dry leaving manufacturing impossible for this period of time, while PSA units would continue to operate as they are far more susceptible to water, and any parts damaged through oil is easily replaceable.
PSA generators produce the same amount of gas each year losing no capacity. Membrane’s age, which means that they will begin producing less nitrogen over the years until they are replaced, for example if a membrane is quoted at 8 scfm it will produce more than 8 scfm at the time of installation however it will begin to lose capacity after a short number of years until its replacement due to the drop in gas production capacity. Compared to PSA generators which maintains the same purity of nitrogen output continuously for years.
In colder weathers PSA generators tend to gain a percentage for every degree of ambient temperature drop below the ideal operating ambient temperatures. While membranes lose the capability to produce nitrogen in lower temperatures.
It is for the aforementioned reasons that organisations which require nitrogen to be continuously produced throughout the year should consider choosing PSA over Membrane. PSA is the ideal option for those looking for a sturdy generator which can work in multiple environments and unpredictable conditions with the maximum return of operating to cost.
Apex's nitrogen gas generators are all manufactured using PSA technology to provide you with an economic and reliable method to separate your mixed gas while achieving a high purity level. If you would like to find out more in regards to Apex's Nitrogen Generators and what we can do for you, follow the link below.