The Nektor Team with the PSA oxygen plant. Source: The KGP Chronicle

Last month, the Central Government admitted to oxygen deaths in the state of Andhra Pradesh. While undergoing treatment for the dreadful Covid-19, several patients on ventilator support succumbed to an inadequate oxygen supply. In a time when the dearth of medical oxygen is a significant issue in the country, we have the Nektor Health Science System, Ahmedabad, collaborating with Professor Parthasarathi Ghosh of the Department of Cryogenic Engineering, IIT Kharagpur, to develop an indigenous medical grade oxygen manufacturing plant based on the Pressure Swing Adsorption technology or PSA for short.

What is the Pressure Swing Adsorption technology?

"Put very simply, the basic principle of PSA is selective adsorption. The technology relies on molecular sieves to adsorb the nitrogen in the air, delivering oxygen left behind as a product," says Prof Ghosh. This process occurs at a regulated pressure and temperature to facilitate the physisorption. The system that the professor assisted in developing consists of two such adsorbers packed with Zeolite. When one of the sieves reaches the saturation point and can't hold any more nitrogen, a combination of pressurization and depressurization is employed, and the second adsorber is subjected to the incoming air instead, and the saturated adsorber is "regenerated" by desorbing the collected nitrogen. This to and fro process continues and hence the conferred name for the technology.

Schematic of the PSA process. Source: Wikipedia

Prof Ghosh mentions, "This cyclic process involved in the PSA technology results in the production of 93-96 % pure medical-grade oxygen directly from compressed air, and this is one of the best methods there is." He was concerned with product development through technical advice to the Nektor team, supervising the equipment specifications, and was also involved in testing the prototype.

The Ingenuity

The PSA technology isn't anything new. It has been in use for a long time; particularly for the separation of nitrogen. So how is this project different, you ask? Well, according to Prof Ghosh, who clarifies, "One specific detail that we need to understand is that bare fundamentals weren't enough for us. Even though the concept is old, we weren't aware of the various geometric and process parameters required to upscale the product, which was the primary goal.

A commercial product such as this demanded complex expertise to integrate minute details from various domains." He goes on to add, "For example, we weren't aware of the adsorption process and equipment specifications for maximum output. This data was generated at IIT Kharagpur, while Nektar handled the components' and prototype controls."

After an extensive development on the basic modules of the technology, the upscaling of the system based on PSA now makes it possible to deliver a higher and a customizable amount of oxygen with minimal requirements.

Driven by the firm intent to fulfil the oxygen shortage in the market, this technology is in the process of commercialization at a rapid rate.

Overcoming the hurdles

Dealing with the preliminary calculations since we were building the product from scratch, combined with the severe time constraints in these trying Covid times, was a daunting hurdle. The restricted transportation posed various challenges for the supply of several types of Zeolites that were put to trial. The pandemic demanded a compromise on the workforce and effective communication.

Prof Ghosh sees immense possibilities in the future for the PSA technology. "Producing medical-grade oxygen today at a small scale is a very energy and cost-intensive process, and there is still research going on in this field. The PSA technology could be the most viable solution since the only drawback would be replacing the adsorbers, which isn't a hefty investment," he says.

The technical prowess from the team at Nektor and the expertise from the research at IIT Kharagpur rendered this venture successful.