500 scm liquid oxygen storage cryogenic tank construction

Customer: PAO "Cryogenmash"

End user: Tomsk affiliate "Cryogenmash-Gas" affiliate

Site location: Tomsk region, Tomsk, Kuzovlevskiy trakt, 2-384

Scope of works: Design, equipment procurement, supervision of installation, systems and integrated testing, start up and commissioning.

 

Cryogenic reservoir for О2 storage

Flat bottom cryogenic tank has several purposes:

- to receive liquid oxygen produced at the air separation unit;

- to provide long-term storage capabilities of liquid oxygen product;

- to manage liquid oxygen distribution to the product discharge pumps (centrifugal and reciprocating) and 

- to fill the product to the tanker trucks as well as to receive the liquid oxygen product from the tanker trucks. 

Cryogenic tank construction 

From the construction standpoint the cryogenic reservoir consists of the inner vessel and outer jacket. An inner vessel is manufactured out of the austenitic alloy-treated steel while the jacket is made out of carbon steel. Both the inner vessel and the outer jacket are attached to the foundation via the base plates that are embedded into the  cement pouring during the foundation works.

Thermoinsulating wall spacing between the inner vessel and the outer jacket is filled with thermoinsulating material – expanded perlite powder.

Thermoinsulation between the bottom of the tank and the foundation is achieved with the layer of foamed glass slabs of required density and thermal conductivity.

To prevent ambient precipitation reaching and corrupting the thermoinsulating layers, a constant nitrogen purging of the thermoinsulating layer is maintained through the collector located beneath the vessel at the bottom part of the jacket.

The tank features man-holes for inspection of the inner vessel, thermoinsulating spacing and also ports for perlite loading and unloading 

For service and maintenance operations on the manholes, control and safety valves located at the top section (roofing) of the storage tank, it features fenced gangways/platforms. For access to the platforms either a spiral staircase wound on the outside of the jacket or a standalone stair tower located next to the tank is used.

The storage tank is fitted out with process piping, block and safety valves and an array of the control and measuring instrumentation devices.

Filling of the reservoir with liquid oxygen product is achieved via the process piping either from an air-separation unit or from a tanker truck. 

A required level of the operating pressure inside the inner vessel of the storage tank is achieved and maintained automatically with a pressurization contour. The countour consists of the pressurizer evaporator, located underneath the storage tank, pressure sensors and regulating valves with pneumatic activators.

Storage control system

Cryogenic storage tank facility features a control system in the form of a local control panel that represents and transforms to the End-User’s top level control system the following signals:

• reservoir parameters (temperature, pressure, level of liquid product);

• condition of the valves (automated block valves - open/shut, regulating valves – degree of opening);

• emergency parameters.

Automated block and control valves may be engaged either from a local control panel or from a distant End-User’s control system. 

Cryogenic tank installation procedure

Picture 1. Inner vessel bottom and outer jacket roofing assembly 

Picture 2. Top of the inner vessel and top of the outer jacket 

Picture 3. Outer jacket bottom being assembled at the designed foundation 

Picture 4. A sidewall section of the outer jacket before fitting to the designed foundation 

Pictures 5,6. Laying of the insulating foamed glass blocks at the bottom of the outer jacket 

Pictures 7,8. Cryogenic storage tank prior to commencement of the paint job 

Pictures 9,10. Cryogenic storage tank after completion of the paint job