IIT-Bombay converts existing nitrogen plant into oxygen generator
At a time when there’s a shortage of medical oxygen supply in the country for treatment of Covid-19 patients, the Indian Institute of Technology-Bombay (IIT-B), has set up a demonstration unit to convert nitrogen generators, which are found in all parts of India, into oxygen generators by fine-tuning the existing nitrogen plant set up.
The oxygen generated by this plant at IIT-B lab was tested and found to be 93-96% pure and at 3.5 atmospheric pressure.
Nitrogen generation plants, which take in air from the atmosphere and separate oxygen and nitrogen to give out liquid nitrogen, can be found in various industries such as oil and gas, food and beverages. Nitrogen is dry in nature and is used commonly for purging and cleaning of oil and gas tankers.
Milind Atrey, institute chair professor, department of mechanical engineering, IIT-B, along with Tata Consulting Engineers Limited (TCE), demonstrated a proof of concept of quickly converting nitrogen plants into oxygen plants.
Nitrogen plants work on pressure swing adsorption (PSA) technology, where air from the atmosphere is sucked in, filtered of impurities and nitrogen is extracted. Oxygen, which is a by-product, is released back into the atmosphere. A nitrogen plant has four components — a compressor to control the pressure of the air sucked in, an air vessel for filtering out impurities, PSU units where the separation takes place, and a buffer vessel into which this separated nitrogen is passed and stored.
Atrey and the team from TCE propose to switch the filter used for nitrogen extraction in the PSA unit with one that can extract oxygen instead.
“In nitrogen plants, the pressure of the air is controlled and then it is cleaned of impurities such as water vapours, oil, carbon dioxide and hydrocarbons. After this step, the purified air goes into the PSA chamber which is fitted with carbon molecular sieves or filters that can separate nitrogen and oxygen. We are proposing that the sieves be replaced with ones that can separate oxygen instead,” said Atrey, a specialist in cryogenic engineering and dean, research and development at IIT-B.
The team replaced the carbon molecular sieves with zeolite molecular sieves in the PSA Nitrogen plant in the Refrigeration and Cryogenics Laboratory of the institute. Zeolite molecular sieves are used for separating oxygen from the air. By controlling the flow rates of the containers, the researchers were able to convert the nitrogen plant into an oxygen generating plant. Spantech Engineers, a city-based company that deals with PSA Nitrogen and Oxygen plant production, partnered on this pilot project and installed the required plant components as a skid at IIT-B for evaluation.
The pilot project was aimed at finding quick and easy solutions to the severe oxygen shortage in medical facilities across the country.
Amit Sharma, managing director of TCE, said, “This pilot displays how an innovative solution for emergency oxygen generation using existing infrastructure can help the country tide over the current crisis.”
“It took us about three days to do the conversion. It is a simple process and can be done quickly within a few days. Nitrogen plants across the country can use this technique to convert their plants into oxygen plants,” said Atrey.
Announced on Thursday morning, the pilot study has gained the attention of many policymakers. “We have received interest from many government officials, not only in Maharashtra but from across the country, on how this can be scaled up and implemented in existing nitrogen plants. We are currently streamlining our processes to help existing plants in adopting this model,” Atrey added.