Airgases Projects offers Vacuum Insulated tanks built to store cryogenic liquids at pressures up to 40 barg. These double wall tanks uses stainless steel material for the inner vessel & carbon steel for the outer vessel. The annular space is filled with perlite with high level of vacuum & special thermal insulating paint on external surface, all ensuring a very low heat in-leak.
Today, the liquefied air gases are used for wide range of applications such as metal processing, medical technology, electronics, water treatment, energy generation and the food industry. With improvement in infrastructure larger volumes of industrial gases are today delivered to customers in liquid form at cryogenic temperatures, enabling them to be stored on site for use as and when required.
These tanks are available in wide range of capacity from few hundreds litres to 300,000 litres and pressure rating from 2.5 barg up to 40 barg . These are designed to meet individual customer needs and complies latest PESO regulations. The inner vessel of these tanks is normally designed to ASME VIII, Div. 1 and outer vessel design follows good engineering practice. These tanks can be designed for vertical or horizontal installation. The inner vessels and piping are made of stainless steel which also ensures high-grade cleanliness – particularly important for the food and electronics industry. The inside wall of outside shell is specially coated and a vacuum-perlite system with an adsorbent is used to retain vacuum insulation for a long time. The tanks from Airgases Projects offer following features/ advantages.
FLAT BOTTOM ATMOSPHERIC PRESSURE TANKS
Under full supervision of experts from Airgases Projects for more than 18 months, recently 6 numbers of large Cryogenic Flat Bottom Storage Tanks were built and commissioned at Reliance Industries, Jamnagr Refinery
Airgases Projects builds large Cryogenic Flat bottom tanks for storing cryogenic liquids at atmospheric pressure with low heat in leak. These are double wall tanks (CS as material of construction for outer tank & SS for inner tank). The cellular glass base insulation, perlite in annular space and special thermal insulating paint on exterior surface, all ensures very low heat in leak and thus very low static evaporation of liquids stored in the tanks. These tanks are available in sizes starting from 200 M3 water volumes and right up to 9000 M3 water volume. Airgases Projects team designs these tanks in-house based on long experience of its senior management team with some of the best tank designers in the world.
The inner tank is designed as per API620 Appendix Q and outer tank designed to API620 with fixed roof. Inner tank is normally designed to a pressure of 200 mbarg plus liquid head as well as vacuum of 5 mbarg and temperature of – 196 deg C. The outer tanks are designed for a pressure of 5 mbarg as well as vacuum of 5 mbarg and ambient temperature. One of important factor to be considered in tank design is seismic conditions and Airgases Projects designs tanks suiting to defined zones as per IS 893. The tanks are provided with suitably designed holding down straps to hold the tank against buoyancy forces.
Airgases Projects builds large Cryogenic Flat bottom tanks for storing cryogenic liquids at atmospheric pressure with low heat in leak. These are double wall tanks (CS as material of construction for outer tank & SS for inner tank). The cellular glass base insulation, perlite in annular space and special thermal insulating paint on exterior surface, all ensures very low heat in leak and thus very low static evaporation of liquids stored in the tanks. These tanks are available in sizes starting from 200 M3 water volumes and right up to 9000 M3 water volume. Airgases Projects team designs these tanks in-house based on long experience of its senior management team with some of the best tank designers in the world.
The inner tank is designed as per API620 Appendix Q and outer tank designed to API620 with fixed roof. Inner tank is normally designed to a pressure of 200 mbarg plus liquid head as well as vacuum of 5 mbarg and temperature of – 196 deg C. The outer tanks are designed for a pressure of 5 mbarg as well as vacuum of 5 mbarg and ambient temperature. One of important factor to be considered in tank design is seismic conditions and Airgases Projects designs tanks suiting to defined zones as per IS 893. The tanks are provided with suitably designed holding down straps to hold the tank against buoyancy forces.
Flat Bottom cryogenic storage tanks are rather inexpensive alternative for storing large volume of liquefied air gases in cryogenic form, compared to that based on vacuum insulation tank system, while still maintaining low heat in leak. . Losses at the base of tank are minimised by layers of cellular glass insulation, divided by layers of inorganic felt, between layers of the base insulation of the tank. The cellular glass is designed to be strong enough to withstand compressive stresses not only from liquid head but also from an earthquake, providing our clients with a secure storage system. The interspace between the inner and outer tank walls is homogeneously filled with expanded perlite powder. The annular space is provided with nitrogen blanketing arrangement to ensure protection against ingress of air along with its moisture. The tank structure employs a pressure distribution plate, which is reinforced and made of cryogenic concrete that ensures a steady load transformation to the insulation. The evaporation losses are minimised to a level of less than 0.2 per cent of full storage capacity of the tank per day at an ambient temperature of 25 deg C for liquid oxygen and less than 0.25% per cent of full capacity per day for liquid nitrogen.
The interconnecting pipework between inner and outer tank is made of SS304 material of construction. The piping is designed keeping in mind stresses arising due to temperature variation from 300 deg K to 77 deg K. This piping design is subjected to stress analysis as per design code. The tanks are site built as per design code and tested as per API code. The tests would include radiographic tests, vacuum box test for bottom plate, hydraulic test, and pneumatic test as well as foundation settling test.
The tanks are provided with elaborate safety systems to ensure safe operation under all conditions and these includes
These tanks will fully comply to EIGA guidelines for “Bulk Liquid Oxygen, Nitrogen and Argon storage systems as production sites” as per IGC Doc 127/04/E. At customer request, we can also provide bottom outlet valve arrangement to minimise “dead stock” of liquid in the tank.
Airgases Projects also provides construction supervision services to customer who is building these tanks themselves. Recently Airgases Projects have provided such services at Reliance Industries, Jamnagar in building 6 nos large flat bottom cryogenic storage tanks.
