Low Pressure Liquid Oxygen Nitrogen Plant

(I)Air Compressor: Screw/low pressure- type: (or oil free piston or centrifugal types)
We employ the most advanced compressor series available in the market. They have a unique combination, meeting customer requirements for low installation, operating and maintenance costs with high dependability and ease of use. Screw type rotary compressors are one of the most advanced and trouble free.

Centrifugal Type:
No other turbo type oil free compressor can match its efficiency and economy. This ensures a consistent and highly reliable source of air supply. Maintenance is extremely low.

The final product in the form compressed Oxygen or Nitrogen goes to the high pressure oxygen cylinders at 150 bar or upto higher as required.

(II)Pre – Cooling system:
The pre-cooling system is a highly efficient skid mounted equipment provided with the main purpose of cooling down the air to a temperature of 5 to 8 degrees Celsius and thus to discharge the condensed water. We are using highly reliable compressors of European origin.

(III)Purifier:
The purifying system is the secondary process unit which is responsible for the removal of moisture, carbon dioxide, hydrocarbons as well as rare gases that are considered to be impurities in the process cycle of air separation. The structure essentially consists of double layered molecular sieves from “Zeochem” (Switzerland) along with alumina which acts as an adsorbent.

The process purifier is vital to the entire process and is greatly responsible for the purity of the final product i.e. Oxygen and Nitrogen in the Air separation Column. It consists of 2 skid mounted molecular sieve regeneration batteries that work on shifts and switch alternatively either manually or through a PLC control (optional).

(IV)Air separation Unit:
The Key to the entire Air separation Process lies within the Air Separation Unit (A.S.U). Here, the mixture of Oxygen and Nitrogen is separated by virtue of the difference in their liquefication temperatures.

The design and efficiency of the A.S.U determines the quality of the final product i.e. Oxygen and Nitrogen in terms of quantity and quality. The Boschi design A.S.U features highly efficient fin type aluminium heat exchangers and column, wherein the entire upper column is a packed column thus reducing the operational pressure and increasing the Oxygen, Nitrogen and Argon recovery.

Argon is recovered by a revolutionary technique employing full rectification without using the hydrogen and De-Oxo unit thus saving further on power costs, operational costs and investment. This makes the Boschi design machines highly versatile and economical thanks to all the research and development done over the years.

(V)Turbo expander:
The Turbo expander is a gas or oil bearing expansion refrigeration turbine that is much more efficient than any other expansion device.

It works on the technique of induced cooling via expansion due to which the operational pressure of the plant is further reduced and the performance of the distillation column is stabilized for constant production and high purity.

1. Compression Of Atmospheric Air By Air Compressor
Air is compressed at a very pressure of 5-7 bar (kg/cm2). Air can be compressed at such low pressure by trouble free rotary compressor (Screw / Centrifugal Type advanced technology is employed in lieu of old bulky piston compressor)

2. Pre Cooling System
The second stage of the process uses a low pressure refrigerant for pre-cooling the processed air to temperature around 12 deg C before it enters the purifier.

3. Purification Of Air By Purifier
The air enters a purifier consisting of twin Molecular Sieve driers, working alternatively. The Molecular Sieves remove the Carbon dioxide & moisture from the processed air before the air enters Air Separation Unit.

4. Cooling Of Air By Turbo (Expander)
The air has to be cooled to sub zero temperatures for liquification & the cryogenic refrigeration & the cooling is provided by highly efficient turbo expander, which cools the air to temperature almost below -165 to-170 deg C

5. Separation Of Liquid Air Into Oxygen And Nitrogen By Air Separation Column
Oil free, moisture free and Carbon Dioxide free air enters into low pressure fin type HEAT EXCHANGER where the air is cooled below sub zero temperatures by air expansion process in the turbo expander.

Air gets liquefied when it enters the air separation column & gets separated into oxygen & nitrogen by the process of rectification. Oxygen is available at the outlet of the ASU at a purity of 99.6%. Nitrogen is also available at the outlet as a second product at purity of 99.9% upto 3ppm simultaneously without loss of oxygen product.

6. Compression Of Oxygen And Filling Of Oxygen In Cylinders
The final product in the form compressed Oxygen/Nitrogen goes to the high pressure oxygen cylinders at 150 bar or upto higher as required.