Nitrogen (N₂)

Discovered in 1772 by Daniel Rutherford, nitrogen is an important nonmetallic element comprising around 78% of Earth's atmosphere. The element is represented with symbol N and atomic number 7 in the periodic table. It is valued for its inert properties and is extensively used for providing nonreactive atmosphere, especially, in preservation of foods. Heavily used in the chemical industry for making fertilizers, nitric acid, nylon, dyes and explosives. In its liquid form nitrogen is used as a refrigerant. It is also found in RNA, DNA and amino acids, the building blocks of life. Nitrogen production is done through cryogenic distillation of air atmospheric.

Nitrogen Specification

• Nitrogen Purity: 99.99%

Most accepted standards for gas purity recommend that nitrogen production having purity of 99.99% adequately meet the requirements of industrial, chemical, medical and scientific applications.

• Nitrogen Pressure: 150 or above

Compressed nitrogen is filled into high pressure cylinders at a pressure of 150 bar or as required by the client’s requirements. It can also be fed into piping gas systems and can also be used for captive consumption.

• Flow Rate: 25Nm3 to 1000Nm3/hour

Nitrogen cylinders are filed with flow rate between 25Nm3/hour to 1000Nm3/hour. We can customize the flow rates as per the requirements of the clients.

How Cryogenic Nitrogen Plant Works

Cryogenic distillation process used in the air separation plants works by liquefying and separating atmospheric air through difference in their boiling points. The process starts with taking in atmospheric air which is then filtered and compressed. Afterwards, the air moves into a cleanup system comprising of twin molecular sieves and driers for removal of impurities such as carbon dioxide, hydrocarbons and water vapors. Once the air has been purified, it is sent through a series of heat exchangers where it is cooled to cryogenic temperature to achieve liquefaction. Subsequently, the liquefied air enters air separation column where after separation nitrogen is formed at the top of the column and oxygen at the bottom.

Nitrogen Production Technology Process- Layout & Flow Diagram

Cryogenic distillation or fractional distillation is a process that involves liquefaction and separation of air into its constituent parts such as nitrogen, oxygen, argon and assortment of various inert gases based on their different boiling points. The process was pioneered by Carl von Linde which was used for industrial applications in 1902. It has evolved with the new technological advancements in the science of cryogenics. Universal Boschi designing encapsulates compact integration between heat exchangers and separation column for achieving high efficiency. Energy for refrigeration is provided by the compression of the air in the high quality Atlas Copco air compressor near the inlet of the air separation unit.

Important Fractional Distillation Steps

• Air is filtered for removal of dust before compression.
• Compression of air takes place with pressures ranging between 5 and 10 bar.
• Compressed air is passed through a molecular sieve bed removing water vapor, carbon dioxide and hydrocarbon that could lead to explosions. Twin sieves are used running alternatively.
• Purified air is passed through Universal Boschi manufactured plate fin heat exchangers and is cooled to cryogenic temperature. A part of the air is liquefied into a cryogenic liquid with oxygen-rich content. The rest of the air is rich in nitrogen which is distilled to high purity nitrogen in the high pressure distillation column.
• End-product in gaseous form is warmed with the incoming gases to achieve ambient temperature. High level of heat integration is needed for shielding the effect of disturbance due to change of molecular sieve beds. Sometimes external refrigeration is also required during the start up of the ASU.

Configuration and Installations

Universal Boschi provides complete installation services ranging from erection, commissioning, installation, starting up and shutting down at client sites. Our technical team comprises of highly qualified engineers and technicians with extensive knowledge of configuration and installation of nitrogen plants. Our engineer will visit the site and prepares the site area for configuration and installation. After installation is complete the engineer will demonstrate how it will be operated. As the instrumentation of the complete the plant is integrated with the latest PLC system for seamless automation. Important electric signals such as current, voltage and power consumption are displayed on the main system. The demonstration will also cover how to control the working of the plant machinery sitting in the control room. Training will also be provided for carrying out minor maintenance like cleaning filters and changing oils. It is to be noted that the plant can be continuously operated for a period of 24 months before it is shut down for panned defrosting of 12 hours.

Start up and Defrosting Time

Total startup time after defrosting till achieving oxygen product flow: 8 to 10 hours (approx) Defrosting period for the plant is: 12 hours (approx)

Shut Down

The plant can be shut down at any time as per the requirement of the user apart the scheduled maintenance shutdowns which are planned on yearly basis for defrosting

Electricity Specifications for Configuration of the Plant

• Low voltage: 380/400V / 220V, 3-phase, 4-wire system, Earthing for neutral point
• High voltage: 10KV
• Frequency: 50/60Hz
• Field devices and PLC voltage: 24 V. DC

What are the Main Applications of Nitrogen

Nitrogen is used in a wide array of applications in different industries. It is called the largest industrially consumed gas. Some of the industries are given below:

• Chemical
• Fertilizers
• Electronics
• Pharmaceuticals
• Scientific labs
• Metal fabricating
• Oil & gas
• Food beverages
• Wine-making

Frequently Asked Questions