The description of all the processes involved in the operation and working of the Low pressure Turbo Plant is as follows:

1. COMPRESSION OF ATMOSPHERIC AIR BY AIR:

In the first step of operation of the plant air is compressed at a very low pressure of 5-7 bar (kg/cm2) with the help of advance technology trouble free rotary screw compressor.

2. PRE COOLING SYSTEM

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

3. PURIFICATION OF AIR BY PURIFIER:

In the purification unit the air enters a purifier consisting of twin Molecular Sieve drier, which works 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 Centigrade.

5. SEPARATION IF LIQUID AIR INTO OXYGEN AND NITROGEN BY AIR SEPARATION COLUMN

The air free from oil, moisture and Carbon dioxide now 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% up to 3ppm simultaneously without loss of oxygen product.

6. Compression 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 up to higher as required.

A few of the latest technological features incorporated into the Oxygen & Nitrogen plants are listed below.

• Purity of Oxygen produced from all plants is minimum 99.6% and Nitrogen Purity is available up to 1 PPM (Depending upon requirement of the customer).
• All plants use “Oil free” rotary screw /centrifugal oil compressor working between 0.6 to 1.0 mpa.
• All plants incorporate Aluminum Brazed exchangers and packed columns for high efficiency.
• 
  Turbo expander (Oil or Air Bearing) for trouble free operation.
• All plants above “500” are supplied with automatic PLC control.
• Engineering support along with complete quality control is provided by our company.
• We provide qualified engineers for Supervision, Installation and start up of all our plants as well as training of manpower at customers’ site.
• Very low power consumption with proven performance and virtually Zero maintenance required for the machines.
• Purity of Nitrogen is very high i.e. 99.99%
• No loss in the production of Oxygen while producing high purity Nitrogen.
• AIR SEPARATION UNIT: This Unit employs a front-end two bed pressure swing adsorption system which is used to remove impurities from the air feed.
• The Cold Box plays the main role in the Oxygen/Nitrogen plant as this is the equipment which separates the gaseous mixture of oxygen and nitrogen. This is done by means of Liquification of air to a temperature of minus 1900C in the Double Rectification Stainless Steel Column.
• The Air Separation Unit houses all the instruments (such as Heat Exchangers, Sub Coolers, Distillation Columns and Condensers all made in Stainless Steel) responsible for the sub-zero cooling of the air thus giving it the name COLD BOX.
• The Air Separation Unit is of CRYOGENIC TYPE operating at extremely low-pressure of 7 Kg/cm2. The separation of gases is done at liquification state.
• EXPANSION TURBINE: The expansion turbine or Turbo expander is a centrifugal or axial flow turbine through which a high pressure gas is expanded to produce work that is typically used to drive a compressor. Because work is extracted from the expanding high pressure gas, the expansion is isentropic and the low pressure exhaust gas from the turbine is at a very low temperature, often as low as 200 K (-100 °F) or less.
• The turbo expander has a composite metal shaft with a compressor wheel attached to one end of the shaft and an expander wheel attached to the other end of the shaft. Both the wheels are completely detached from one another.
  Along with the common shaft a sealing system is used for the prevention of the process fluids present at each wheel from getting contact with leakage along the shaft. We use a gas seal system as a sealing system in our Plant. The advantage of using a gas seal system is that the sealing fluids cannot leak into and accumulate in downstream equipment.