Design of Large Size Industrial Cryogenic Liquid Air Storage Tank

Abstract

Cryogenic storage tanks (Liquid nitrogen, Liquid oxygen, Liquid Argon tanks) are an inevitable portion of Air Separation system. The Usage of air separation unit is spread over various industrial sectors like petroleum industries, chemical industries, food processing industry, fabrication etc. But the number of cryogenic tanks for storage of liquid air compared with other equipments in the family is less and the technology available is with few contractors (most of them in the far east). Though the technology and experience is confined to very few companies that carry out construction, the consultancies in India need to have knowledge about its various aspects like concept, construction, instrumentation, mechanical design and considerations, materials selection, operation etc. For design of such tanks, even though many standards are available, the proper method and sequence is not deduced from the standards. A proper design sequence and procedure is necessary for a valid design as low temperature liquid by itself can be fatal to life. The project report deals with detail understanding of the concept of cryogenic storage system for for storage of products like liquid oxygen, liquid nitrogen and liq- uid argon. A detailed mechanical design procedure with sequence has been provided in the course. The design procedure include the reference of API 620[1] (American petroleum Institute) as primary and API 650[2] standards as secondary. The proce- dure also include references of AIGA 031/13[3], ASCE 7[4] to supporting the design. Finite Element Analysis has also been performed for roof stability check of inner and outer tank and that of nozzles. The project was successfully carried out using microsoft excel, wherein the calculations and the various data in the file the user only needs to enter the input to obtain the results. It can also be concluded that API 620 together with API 650 can be successfuly used to cover major portion of design of above mentioned cryogenic tanks.