Chemical engineers collaborate for ‘cookie-cutter’ oxygen units

THREE chemical engineers at different universities around the world are collaborating to develop “cookie-cutter” portable oxygen conversion units that can be easily assembled from locally-sourced equipment, to prevent “thousands” of Covid fatalities in India.

Research group Center for Global Development, says India’s official death count at the end of June was 400,000 but adds that the reality is “catastrophically” worse. Large waves of Covid in the country have consumed large amounts of resources and depleted available oxygen supplies. Responding to increasing numbers of patients in wards, India’s hospitals have commandeered liquid oxygen – used for steelmaking – for medical use. However, the refrigerated trucks needed for transport are in short supply.

To address the oxygen shortage in India, Paul Webley, IChemE Fellow and Professor of Chemical Engineering at Monash University, Australia began working with Tejas Bhatalia and Abishek Sharma. Bhatalia is a Senior Research Fellow at Curtin University, and Sharma is a Chemical Engineering Professor at Manipul University Jaipur, India. Webley formerly worked as an engineer on designs for oxygen plants at an American industrial gas company.

Working via video link they aim to develop oxygen conversion units that technicians could build “on-the-ground” in India, enabling self-sufficiency. Additionally, the units would be portable and able to produce oxygen where needed. Portable oxygen conversion units for patients with chronic respiratory problems are typically set up in homes. However, Webley’s version is larger, intended to treat multiple patients at a time.

Webley explained further, saying: “Our plan is to use readily available equipment items – vessels, compressors, valves, piping…Our emphasis has been on simplicity and low cost, not performance.”

Webley also said that the system should be easy to repair and able to run on a diesel generator.

The original design required more sophisticated compressors and system operating design, but this was adapted to accommodate equipment items available.

The system also requires a silicon molecular sieve to filter out nitrogen; oxygen conversion units strip nitrogen from the atmosphere, leaving oxygen gas behind. Though the type of sieve required is specialised, it is inexpensive and relatively easy for chemical engineers to buy.

Monash University

The group is currently working with prototypes and is currently in the debugging phase. Sharma works using the main large prototype and sends data to Webley, who uses simulation tools to help diagnose operations, interpret data, and suggest changes. Using a smaller prototype, Bhatalia also helps to debug the large unit.

Webley said he expects to make further modifications to the system, but believes the team will achieve a rapidly reproducible “cookie-cutter” unit, after three or four more iterations.

The researchers are also working to improve the oxygen purity that the system can achieve. Webley explained that the medical profession has strict standards and requirements to which the group has to adhere. “The main restriction is purity – it must be supplied at a minimum of 90% purity,” he said. Currently the team has achieved 70% purity.

Though the team intends to achieve the 90% purity required – by fine-tuning and correcting the operating conditions – Webley highlighted that it is well-known that “80% or even 70% oxygen can be beneficial and save lives, but the medical industry is very conservative and is not easily accepting of this”.

Webley further highlighted that another obstacle that the team’s development will have to overcome is that the current model of oxygen supply is large, centralised facilities providing oxygen trucked to sites. “It will take a fair amount of social and medical institutional acceptance to shift to a model where each hospital or clinic has its own oxygen generators,” he said.

The team is currently testing, with plans to achieve 90% purity and required production by early August, before deploying to a local hospital for further testing.

“The first prototype is planned to deliver about 50 L/min – enough for about 8–10 patients,” said Webley. “Based on the need, we may look to build slightly larger ones in the future.  We will only know when we understand the market in more detail.”

In addition to the system that Webley is collaborating on for India, he is collaborating with Brazilian engineers to develop a similar DIY unit for the country. It could also be adapted for other countries in need, such as in Africa, Bangladesh, or Nepal.

Webley said: “An important lesson to learn is that a good, quick, low-cost design is better than a perfect, optimized design.  Saving lives is paramount and can’t wait for us while we perfect our work.”