Sunday, 21 October 2012

How to operate Vacuum Pump and Working of Liquid Nitrogen Plant

How to operate Vacuum Pump and Working of Liquid Nitrogen Plant
Want to know about "How to operate Vacuum Pump and Working of Liquid Nitrogen Plant"?

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1. How to operate Vacuum Pump

Vacuum requirements is one of the critical factor that affects the cryogenics temperature. Without Vacuum no cryogenics systems survive. Look at Pulse Tube Cryocooler and related Cryocooler, which always require vacuum to keep resists atmospheric temperature and minimize conduction and convection losses because Vacuum is having no medium and heat transfer requires medium except radiation heat transfer.
Once you have Vacuum pump but it is not sufficient, you need to know how to operate it. Visit URL as under:

How to operate Vacuum Pump?

2. Construction and Working of Liquid Nitrogen Plant? 

Liquid Nitrogen (77 K boiling point) is one of the important cryogen in liquid state and which is used for precooling medium to produce liquid Helium and Hydrogen. Liquid Nitrogen is also used to improve the cold and cryo working of metal in metallurgical field. It is also used to cool and store the foods, tissues, blood. Cryosurgery and Cryo biology is one of the prime application areas for liquid nitrogen. Market cost of liquid nitrogen is Rs. 20 per litre.

To produce liquid Nitrogen, one need to operate Liquid Nitrogen Plant which absorbs atmospheric air and abstract gaseous Nitrogen from the air by Pressure Adsorption System (PSA). This gas is cooled in refrigeration system before going to Stirling Cryocooler where it is liquefy at 77 K temperature and is stored in Dewar vessel to keep atmospheric effect away from liquid Nitrogen.
Introduction of liquid Nitrogen liquefaction

Liquid Nitrogen Plant (LNP) extracts Nitrogen gas from atmospheric air and then liquefies.

Nitrogen can be liquefied by two methods:
a. Distillation of liquid air.
b. Pressure Swing Adsorption system with Cryogenerator

LNP works on principle of reversed stirling cycle.
Construction of liquid Nitrogen plant:

There are mainly two important parts of LNP.
1. Pressure Swing Adsorption System (PSA)
The main objective of PSA system is to extract Nitrogen gas from compressed atmospheric air.

2. Cryogenerator
It liquefies gases Nitrogen to liquid state and liquid Nitrogen is collected in Dewar vessel (vacuum insulated vessel)

Working of liquid Nitrogen plant:

1. Atmospheric air is sucked to compressor whereby it is compressed to high temperature about 7 bar pressure with high temperature.
2. This high temperature compressed air is cooled in external refrigeration system.
3. Cooled compressed air is then passed through moisture separator to trap the moisture from the air.
4. This dry compressed air passes through bed of carbon molecular sieves whereby oxygen and nitrogen from air is separated and remaining contents of air is purged to atmosphere.
5. Separated Nitrogen is now allowed to pass through Cryogenerator which works on Stirling cycle which cools the gaseous Nitrogen to liquid state at 77 Kelvin which is boiling point of nitrogen.
6. Liquid Nitrogen is now collected to Dewar vessel to store it for application purpose
Applications of liquid Nitrogen:

1. Serves as coolant for computers and vaccum pump systems
2. Cooling of superconductors
3. Storage of foods for food preservations
4. Cryopreservation of bloods
5. Cryosurgery for removing dead cells from brain
6. Preservation of semen
7. Working substance for liquid nitrogen power vehicle and many more.

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