Liquefaction and Fractional Distillation,Oxygen & Nitrogen Generation

MAIN EQUIPMENTS/MACHINERY FOR OXYGEN AND NITROGEN PLANTS

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AIR COMPRESSOR

PROCESS SKID

EXPANDER

AIR SEPARATION UNIT

LIQUID OXYGEN PUMP WITH CYLINDER FILLING STATION

DETAILED PROCESS

Step 1

Air Compressor

The free saturated air is sucked from atmosphere through a highly efficient dry-type suction filter into the first stage of the horizontally balanced opposed, lubricated reciprocating air compressor.

Step 2

Purification of Air (Process Skid)

This consists of purification of the air by removing moisture, oil traces and carbon-dioxide in the process air.

Compressed air is chilled to 12°C in a chilling unit and evaporation cooler, compressed air passes through the coils of the chilling unit at a temperature of 12°C to a moisture separator, where the condensed moisture gets removed before entering into Molecular Sieve Battery. Before sending the air to MOLECULAR SIEVE BATTERY, air is passed through an OIL ABSORBER where air becomes oil free.

Chilled air passes through the Molecular Sieve Battery consisting of Twin Tower packed with molecular sieves to remove moisture and carbon dioxide present in the air.

Molecular Sieve Battery operates on Twin Tower System, when one tower is under production the other tower is regenerated by passing waste nitrogen gas at 200°C through a REACTIVATION HEATER. After interval of 8 to 10 hours, the tower under production gets exhausted and regenerated by similar process before use and, thus the cycle continues. Any dust particle gets filtered in the DUST FILTER before air enters the AIR SEPARATION COLUMN All the equipments are mounted on process skid. (See our Catalog)

Step 3

Expander (Expansion Engine)

The process air before liquefication in the air separation unit needs to be cooled to temperatures sub-zero (cryogenic). The main portion of the air after the process skid enters the expansion engine through the heat exchanger no. I after pre-cooling. The temperature of the air drops to around -165degC by the Expander which is a very highly efficient advanced design with Teflon piston rings and completely hydraulic mechanism with leakproof ball valves.

Rest of air at (-80) deg C from Heat Exchanger No. I enters into a highly efficient EXPANSION ENGINE, where the air further gets cooled down to (-150) deg C before entering into bottom column. The liquefied air from both these streams collected at the BOTTOM COLUMN is known as RICH LIQUID

Step 4

Air Separation Unit

After the process skid, the air enters the air separation unit (cold box) where the air converts into liquid air by deep cooling at cryogenic (low temperatures) and is separated into liquid oxygen and nitrogen.

Chilled, Oil-free and moisture-free air enters into multi-pass HEAT EXCHANGER No. 1 where it gets cooled to (-80) deg C by cold gained from outgoing waste nitrogen and oxygen.

A part of air, this enters a multi-pass HEAT EXCHANGER NO. II or LIQUEFIER made of special alloy tubes. This air cools to (-170) deg C before passing through an expansion valve. Due to Joule Thompson Effect, after the expansion valve, air gets further cooled down and gets liquefied before entering into Bottom Column.

The RICH LIQUID in the BOTTOM COLUMN enters into feed tray of top column. Similarly the liquid nitrogen called POOR LIQUID enters into top column as a reflux & it takes away the latent heat of condensing oxygen and gets vaporized whereas the liquid oxygen flows down the trays of the TOP COLUMN into the Condenser. Liquid Oxygen from CONDENSER passes through a SUB-COOLER to a LIQUID OXYGEN PUMP.