S3 medical oxygen generator

Team Lead: S Dasappa
Email: dasappa@iisc.ac.in

Background
The Gasification group at IISc, which specializes in low pressure multi-species gas separation, has developed an oxygen generation system for small-scale medical requirements. The process uses low power and meets the specifications as per the MoH&FW.

The process draws ambient air through a compressor along with an air conditioning system to remove any contaminants in the air before the separation. The oxygen separation takes place within a twin-bed Vacuum Swing Adsorption system integrated with a small storage volume as a discharge vessel and various safety systems. The equipment build material and the oxygen produced fulfills the gas quality requirements as prescribed by Indian Pharmacopeia and can be used in ICU/CCU/OT and other clinical wards. The choice of materials for the equipment meets the prescribed standards.

Specifications

Sl. No.	Parameter	Specifications
01.	Product	Medical grade oxygen
02.	Feed air requirement	33 Nm3/h
03.	Oxygen generation capacity	3 Nm3/h
04.	Equivalent number of hospital beds served	20
05.	Number of oxygen cylinder equivalent per day	11
06.	Product quality	Purity: 93 ± 3 vol% CO level: < 5 ppm CO2 level: < 300 ppm SO2: 0 ppm NOx: 0 ppm
07.	Product dew point	– 73 oC (Approx.)
08.	Operating temperature	50 oC (Maximum)
09.	Operating pressure	5 bar-abs
10.	Product pressure	4 bar-abs (can be regulated)
11.	Operating relative humidity	≤ 95%
12.	Oxygen surge vessel volume	150 liters
13.	Electrical supply	230 V, 1 Phase ‘OR’ 415 V, 3 Phase
14.	Adsorber and vessel design pressure	8 bar-abs/vacuum (ASME Section VIII)
15.	Hydraulic test pressure	10 bar-abs
16.	Change over valves	Electrically actuated solenoid valves
17.	Operation	Continuous
18.	Noise level	< 65 dB
19.	Feed fluctuation allowed	± 10%
20.	Mounting	Skid-mounted
21.	Oxygen analyser	Calibrated with sensor rated for O2

Brief description of the process

Ambient air is drawn through a filter using a compressor operating at about 6 bar-abs pressure. At the exit of the compressor, a dehumidifier removes any moisture in the gas and also condenses any undesirable compounds with due point around 10 degrees Celsius. The dried air through further conditioning is sent through a column of adsorbents as shown in the figure below. Pure oxygen is discharged into the oxygen surge vessel where further conditioning of the oxygen is carried to meet the specifications. During the desorption process, the second column will be in action. The process continues. Safety interlocks along with the pressure relief valves are provided for safe operation.

Simplified process flow diagram

Salient features

• Six step cyclic continuous process with efficient desorption and increased life of adsorbents
• Fulfills the normative requirement of the quantity of oxygen for a 20-bed hospital as prescribed by the Ministry of Health & Family Welfare
• Product gas quality as per the guidelines prescribed by the Indian Pharmacopeia
• Non-polluting, reliable, automatic unit with all safety features
• Availability of product gas at 4 bar-abs pressure which can be regulated
• Uninterrupted product gas supply for 15 minutes in case of power failure
• A rugged system with ± 10% fluctuation in the input/feed flow rate allowed
• Standard accessories and components compatible with oxygen with all pipes and valves made up of SS 316L (recommended)
• Continuous monitoring of product purity using online oxygen analyzers and alarms
• Control and acquisition using a programmable logic controller with a provision for emergency stop
• Utilization of vent gas for product gas composition maintenance and particulate filter regeneration
• Low noise levels
• Bacterial filtration on the output line
• Can be coupled to a DG/genset, renewable power as a decentralized system
• The general design principle can be adopted for any throughput requirement

Team

• Arashdeep Singh
• Anand M S
• S Dasappa

Interested agencies, institutions and individuals who are interested in using the IISc design can contact the following address for further details to manufacture the above product:
Prof. S. Dasappa
Centre for Sustainable Technologies
Indian Institute of Science
Bengaluru – 560 012, India
Email: dasappa@iisc.ac.in, scube@iisc.ac.in

Support will be extended in terms of sharing of complete product engineering drawing, bed material information and necessary control logics under Open Source Licensing terms.