26-06-2014, 02:28 PM
Bharat Heavy Plates and Vessels Limited
[attachment=65371]
Introduction
Bharat Heavy Plate and Vessels Limited is established in 1969 by the subsidiary of “BHARAT HEAVY ELECTRICALS LIMITED” by the government of India to fabricate process plant equipment like fertilizer, petroleum, chemical, petro-chemical and alloyed industries.
Cryogenics
Cryogenics is the study of the production of extremely low temperatures. This field of science also looks at what happens to a wide variety of materials from metals to gases when they are exposed to these temperature.
It determines the physical properties of structural and applications of low temp techniques and process.
Air intake
Air is a mixture of nitrogen and oxygen. This accounts for 99 %. The remainder consists of argon, carbon dioxide and other rare gases. Oxygen, nitrogen ,argon, as well as the rare gases neon, xenon and krypton are obtained from the air by the method of low temperature rectification.
Preliminary purification
Before the air is separated into its gaseous components ,unwanted ingredients must be removed. These are filtered out, chemically absorbed of surfaces or frozen out.
Compression
The air that has been sucked in is compressed at a pressure of around 6 bar. Heat is created as a result.
Preliminary cooling
The compressed air is first cooled down to a temperature of minus 180°C. As it expands in the separation columns, it cools down still further . As a result it liquefies to some extent
(the temperature being lower than the boiling point).
Cooling and separating
By means of the separation column, the air is separated into its components. Here it is oxygen preeminently, with its higher boiling point (-183 degrees C), which condenses out of the stream of gas. The drops of liquid, on the other hand, give rise for preference to evaporating nitrogen, with its lower boiling point of -196°C
Gaseous nitrogen collects, in consequence, at the top of the separation column, while liquid oxygen collects at the bottom of the column. The oxygen at the bottom is vaporized, while nitrogen in liquid form is introduced at the top of the column. This process is continued as long as is required to reach the desired level of purity.
Filling
Liquid oxygen, nitrogen and argon are filled into cryogenic tanks or road tankers or compressed to 300 bar, vaporized and filled into steel vessels
Cryogenic tanks are special containers designed for the storage and protection of cryogenic liquids such as, nitrogen, hydrogen and argon.
Cryogenic Vessel is essentially a double walled cylindrical tank, annular space between inner and outer vessel is filled with insulating material and evacuated to a high vacuum to achieve minimum evaporation losses.
PROPERTIES OF CRYOGENIC MATERIALS
Some of the properties of the cryogenic material are as follows:
The metals and alloys should have face centered cubic structure such that this will remain elastic and deformable at sub zero conditions.
The tensile stress should be lower than yield stress.
The materials having well weldability, workability and ease in fabrication of equipment.
Corrosion resistance is important for air separation equipment as well as cryogenic storage tanks especially while handling Oxygen storage tanks.
Fracture toughness i.e., ability to resist rapid crack propagation should be high.
Different Cryogenic Materials:
STAINLESS STEELS:
Austenitic stainless steels are suited for cryogenic applications as they remain tough and ductile even at -269°C.
9% NICKEL STEELS:
9% nickel steels are usually classified as ferrite steel however this constitutes austenitic ferrite and magnetite. The presence of austenitic has given excellent strength and resistance to brittle fracture
COPPER ALLOYS:
Copper alloys like alpha brass and phosphorous-di-oxide, copper were easy material of construction for cryogenic equipments
Aluminum alloys:
Aluminum alloys like 5083 (Mg 0.445%, Mn 0.6% and cr 0.15%), 6003 (Mn 1.26% and Cu 0.12%) are used in manufacture of cryogenic storage vessel, columns in air separation plant and brazed aluminum of heat exchangers. These show no ductile to brittle transformation even down to the temperature of liquid helium i.e., -269°C.
Industrial applications;
Liquid nitrogen and helium are use in many industrial applications. Liquid nitrogen is the most widely used and liquid helium is used to attain the lowest attainable temperatures worldwide. They are stored in Dewar flasks.
Cryogenic processing
Materials attain more hard when cooled to low temperatures. Tools were subjected to cryogenic tempering as an alternative to heat treatment.
. Chilling and freezing applications
Other applications of cryogenics include fast freezing of some foods and the preservation of some biological materials such as livestock semen as well as human blood, tissue, and embryos
Shell and tube heat exchanger:
Shell and tube heat exchangers are comprised of multiple tubes through which liquid flows. The tubes are divided into two sets: the first set contains the liquid to be heated or cooled. The second set contains the liquid responsible for triggering the heat exchange, and either removes heat from the first set of tubes by absorbing and transmitting heat away—in essence, cooling the liquid—or warms the set by transmitting its own heat to the liquid inside. When designing
A set of tubes is called the tube bundle and can be made up of several types of tubes: plain, longitudinally finned, etc. Shell and tube heat exchangers are typically used for high-pressure applications (with pressures greater than 30 bar and temperatures greater than 260 °C).
This is because the shell and tube heat exchangers are robust due to their shape.
[attachment=65371]
Introduction
Bharat Heavy Plate and Vessels Limited is established in 1969 by the subsidiary of “BHARAT HEAVY ELECTRICALS LIMITED” by the government of India to fabricate process plant equipment like fertilizer, petroleum, chemical, petro-chemical and alloyed industries.
Cryogenics
Cryogenics is the study of the production of extremely low temperatures. This field of science also looks at what happens to a wide variety of materials from metals to gases when they are exposed to these temperature.
It determines the physical properties of structural and applications of low temp techniques and process.
Air intake
Air is a mixture of nitrogen and oxygen. This accounts for 99 %. The remainder consists of argon, carbon dioxide and other rare gases. Oxygen, nitrogen ,argon, as well as the rare gases neon, xenon and krypton are obtained from the air by the method of low temperature rectification.
Preliminary purification
Before the air is separated into its gaseous components ,unwanted ingredients must be removed. These are filtered out, chemically absorbed of surfaces or frozen out.
Compression
The air that has been sucked in is compressed at a pressure of around 6 bar. Heat is created as a result.
Preliminary cooling
The compressed air is first cooled down to a temperature of minus 180°C. As it expands in the separation columns, it cools down still further . As a result it liquefies to some extent
(the temperature being lower than the boiling point).
Cooling and separating
By means of the separation column, the air is separated into its components. Here it is oxygen preeminently, with its higher boiling point (-183 degrees C), which condenses out of the stream of gas. The drops of liquid, on the other hand, give rise for preference to evaporating nitrogen, with its lower boiling point of -196°C
Gaseous nitrogen collects, in consequence, at the top of the separation column, while liquid oxygen collects at the bottom of the column. The oxygen at the bottom is vaporized, while nitrogen in liquid form is introduced at the top of the column. This process is continued as long as is required to reach the desired level of purity.
Filling
Liquid oxygen, nitrogen and argon are filled into cryogenic tanks or road tankers or compressed to 300 bar, vaporized and filled into steel vessels
Cryogenic tanks are special containers designed for the storage and protection of cryogenic liquids such as, nitrogen, hydrogen and argon.
Cryogenic Vessel is essentially a double walled cylindrical tank, annular space between inner and outer vessel is filled with insulating material and evacuated to a high vacuum to achieve minimum evaporation losses.
PROPERTIES OF CRYOGENIC MATERIALS
Some of the properties of the cryogenic material are as follows:
The metals and alloys should have face centered cubic structure such that this will remain elastic and deformable at sub zero conditions.
The tensile stress should be lower than yield stress.
The materials having well weldability, workability and ease in fabrication of equipment.
Corrosion resistance is important for air separation equipment as well as cryogenic storage tanks especially while handling Oxygen storage tanks.
Fracture toughness i.e., ability to resist rapid crack propagation should be high.
Different Cryogenic Materials:
STAINLESS STEELS:
Austenitic stainless steels are suited for cryogenic applications as they remain tough and ductile even at -269°C.
9% NICKEL STEELS:
9% nickel steels are usually classified as ferrite steel however this constitutes austenitic ferrite and magnetite. The presence of austenitic has given excellent strength and resistance to brittle fracture
COPPER ALLOYS:
Copper alloys like alpha brass and phosphorous-di-oxide, copper were easy material of construction for cryogenic equipments
Aluminum alloys:
Aluminum alloys like 5083 (Mg 0.445%, Mn 0.6% and cr 0.15%), 6003 (Mn 1.26% and Cu 0.12%) are used in manufacture of cryogenic storage vessel, columns in air separation plant and brazed aluminum of heat exchangers. These show no ductile to brittle transformation even down to the temperature of liquid helium i.e., -269°C.
Industrial applications;
Liquid nitrogen and helium are use in many industrial applications. Liquid nitrogen is the most widely used and liquid helium is used to attain the lowest attainable temperatures worldwide. They are stored in Dewar flasks.
Cryogenic processing
Materials attain more hard when cooled to low temperatures. Tools were subjected to cryogenic tempering as an alternative to heat treatment.
. Chilling and freezing applications
Other applications of cryogenics include fast freezing of some foods and the preservation of some biological materials such as livestock semen as well as human blood, tissue, and embryos
Shell and tube heat exchanger:
Shell and tube heat exchangers are comprised of multiple tubes through which liquid flows. The tubes are divided into two sets: the first set contains the liquid to be heated or cooled. The second set contains the liquid responsible for triggering the heat exchange, and either removes heat from the first set of tubes by absorbing and transmitting heat away—in essence, cooling the liquid—or warms the set by transmitting its own heat to the liquid inside. When designing
A set of tubes is called the tube bundle and can be made up of several types of tubes: plain, longitudinally finned, etc. Shell and tube heat exchangers are typically used for high-pressure applications (with pressures greater than 30 bar and temperatures greater than 260 °C).
This is because the shell and tube heat exchangers are robust due to their shape.