We are engaged in manufacturing and supplying PSA plants for our clients spread worldwide.
PSA oxygen generator uses zeolite molecular sieve as sorbent, produces oxygen by making use of the PSA principle. Under certain pressure, zeolite molecular sieve has different oxygen/nitrogen adsorption capacity, i.e. much more nitrogen adsorption capacity than oxygen adsorption capacity.
Our PSA oxygen plants has the purity of 93- 95% and nitrogen generators has purity of 98% with range up to 2000m3/hr.
The Air Compressor compresses air upto 7.5 Bar and is cooled to ambient temperature in a shell and tube type heat exchanger . Compressor is unloaded by a mechanical unloader fitted on compressor at 7 Bar. To kill the pulsation in bottle is installed just near to compressor which also reduces the vibration in discharge line. One High Pressure Switch is provided at Compressor's discharge line to trip the compressor at 8.0 Bar pressure in case the unloader fails. For extra safety of discharge pressure one safety valve is provided at discharge line which will blow at 8.5 Bar discharge pressure. We shall supply Oil Filters before Air Receiver.
This serves as a buffer vessel / small storage for compressed air for continuous feed of air to the system. This also kills the pressure pulsation and supply air at almost constant pressure. Here moisture is also drain out by Auto Drain from the bottom.
There are two towers filled with a special grade Carbon Molecular Sieves (CMS) to adsorb O2 & CO2 present in the air . At the bottom of each tower M.S. perforated plate with 10mm dia. hole and SS wire mesh is welded to hold the CMS filled in the tower. Just above the plate, the ceramic balls are put to act as a holding bed for CMS .The Carbon Molecular Sieves is being filled up to the straight portion at the top of tower. The perforated plate facing the bottom or the cover is the supporting element while the adsorbent is prevented from flowing out by the wire mesh. A 50 mm thick Coconut fiber mat is packed as the cover to fix the adsorbing bed . The upper perforated plate compresses adsorbent fill to avoid undesired void. The coconut fiber mat is squeezed together when the cover is tightened.
Cycle time of PSA Unit is 1 + 1 Minute .Each tower has air inlet valves (VI & V2) bottom , gas outlet valves (V7 & V8) at top and exhaust outlet valves (V3 & V4) at the bottom. Besides these, a valve V6 is for pressure equalization at the top and a valve V5 after exhaust valves (V3 & V4) at the bottom. The air inlet line from air receiver has 1 No. globe valve V9 to control the flow of air so that the max. pressure in the adsorbing towers goes to 7.5 Kg/cm2 G.
Oxygen from PSA Module will have varying purity depending upon the pressure in the adsorber during the one minute cycle time. This vessel gives product Oxygen at constant pressure with constant average gas purity. For analyzing the O2 percentage in the Nitrogen gas, one needle valve for sampling is provide over this vessel . One pressure gauge is also provided on the vessel .In Surge tank , One NRV is fitted in reverse direction through which some of N2 gas goes back to PSA towers after the equalization cycle , so that there is drop of 0.2 to 0.3 Barg pressure of surge tank. This gas decrease the time required for the pressure rise in PSA towers , which leads to more production time , and better purity of Nitrogen Gas .Middle vent valve is provided through which the Nitrogen is vented until the Oxygen content comes down to 1% at Surge Tank.
Rotameter is provided at the outlet of Oxygen Surge Vessel to check the quantity of Oxygen flow drawn from PSA system.
To monitor oxygen Percent level at outlet a digital on-line oxygen analyzer is installed.
The back pressure controller is installed in outlet line after the N2 Surge Vessel, when the inlet pressure signal exceed the spring setting, the outlet port of BPC will open and in case this pressure goes down, it will close the outlet port. This would always maintain 5.0 Barg pressure in the Surge Vessel . The setting of back pressure controller can be changed by adjusting the bolt provided at the top. Three-way vent valve is a pneumatically operated 3-way valve. With no compressed air signal , its bottom port is open to atmosphere. Thus when the gas generator is started the gas initially of low purity will go to atmosphere through this 3-way valve. This valve close its bottom port when it gets compressed air through solenoid valve and then Nitrogen gas starts going to Suction Pot. The solenoid valve will get energized when the vent push - button is pressed after checking the quality of product gas for some time. In case of any abnormality in the plant , the control valve will open automatically and the gas will be vented to atmosphere.
Oxygen storage vessel is provided for storing nitrogen gas at 5.5 Kg/cm2 G pressure. This serves as a buffer stock for Oxygen Gas in emergency in case of break down in the plant or power failure. One no pressure switch is installed on it to open the final vent valve in case of high pressure.