What are the design requirements for carbon dioxide storage tanks?

What are the design requirements for carbon dioxide storage tanks?

At present, the design temperature of carbon dioxide storage tanks produced in my country is generally-40 °C, and the design pressure is 2.16 MPa. Due to the particularity of the structure of the storage tank, it is impossible to open inspection holes on such a small storage tank. Therefore, it should be noted that the welding joint coefficient of the carbon dioxide storage tank must be taken as 1.0, and all welds of Class A and B must be 100% radiographic inspection, and the results should meet the requirements of Class II in NB/T47013.

Considering that the design temperature of the carbon dioxide storage tank has reached-40 °C, the ordinary pressure vessel steel plate can no longer meet its requirements. Combined with the economy and actual situation, the 16MnDR steel plate is selected. The lower limit of the service temperature of the steel plate is-40 °C. Meet the requirements of the equipment. As a result, the main design parameters and materials of the carbon dioxide storage tank have been determined.

The corrosion of 16MnDR by carbon dioxide is relatively slight, but considering the internal undetectability of the carbon dioxide storage tank in the future, in order to improve its safety, a corrosion allowance of 2mm is taken. After the above steps, the main design of the equipment has been completed. Since the working temperature of carbon dioxide storage tanks is generally around-40 ~-20 ℃, the equipment should especially consider the influence of stress concentration on low temperature brittle fracture.

In order to reduce the local high stress of the carbon dioxide storage tank caused by structural discontinuity and make the structure have sufficient flexibility, the design requirements should meet the requirements:

1) The structure of the carbon dioxide storage tank should be as simple as possible to reduce constraints.

2) Avoid excessive temperature gradients.

3) The sudden change of structural shape should be avoided as much as possible to reduce local high stress, and the nozzle end should be polished into a rounded corner, showing a smooth transition.

4) The manufacture or outrigger of the container must be equipped with a backing plate, and it must not be directly welded on the shell. The design and process requirements have comprehensively considered the above situation. For the possible residual stress, it should be eliminated through the final post-welding heat treatment. Finally, the storage tank should be considered. The cold preservation measures of the tank, the purpose of the liquid carbon dioxide storage tank’s cold preservation is to prevent the surrounding water vapor from infiltrating into the insulation body, and prevent the outer layer of the storage tank from condensing or even producing ice.

The above are the design requirements for carbon dioxide storage tanks.