For the structure of LNG cryogenic storage tank, there are mainly three structures of inner tank wall, cold insulation layer and concrete outer tank. For different structures, they also have different structural characteristics. The tank wall is the primary component of the low temperature storage tank, which is welded by steel plates with low temperature resistance and good mechanical properties. Next, let’s talk about it in detail.
(I) Inner tank wall
The inner tank wall is the primary component of the low temperature storage tank. It is welded by steel plates with low temperature resistance and good mechanical properties. Generally, special steels such as A5372 grade, A516 Gr.60, Gr18Ni9, and ASME 304 are used.
For example, the bottom plate and ring plate of a tank are made of A537 CL2 steel plate with a thickness of 16mm, and the other plates can be made of A537 CL1 steel plate with a thickness of 6.35mm.
(II) Cold insulation layer, there are three types of cold insulation layer:
Tank wall cold insulation
The inner side of the outer tank liner is sprayed with polyurethane foam. Generally, the thermal conductivity of the polyurethane foam is ≤0.03 W/(m·K), the density is 40-60kg/m3, and the thickness is about 150mm.
Tank top cold storage
The inner tank top adopts a suspended rock wool cold insulation layer. For example, a tank top is equipped with 4 layers of glass fiber cold insulation layers, each layer is 100mm thick, the density of glass fiber wool is 16 kg/m3, and the thermal conductivity is 0.04W/(m3 ·K).
Tank bottom cold
It is more complicated to keep cold at the bottom of the tank. In addition to spraying polyurethane foam under the steel plate, it is necessary to plan a waterproof structure. The cold insulation structure at the bottom of a tank includes 65mm thick cushion, 60mm thick dense concrete, 2mm thick waterproof linoleum, two layers of 100mm thick foam glass, and finally covered with 70mm thick concrete to protect the outer tank concrete from being damaged. affected by low temperature.
(III) Concrete outer tank
The concrete outer tank wall and outer tank top are composed of prestressed reinforced concrete and low temperature resistant steel lining board. Concrete strength should be ≥ 25MPa. The outer tank roof and tank wall should be able to withstand the internal pressure caused by accidental gas leakage, therefore, the reinforced concrete should have sufficient tensile strength.
For large storage tanks, in order to make the prestressed concrete tank wall bear the force evenly, the planning method of equal strength and unequal thickness or equal thickness and unequal strength can be adopted.
The above is about the characteristics of the components of the LNG cryogenic storage tank, I hope it will be helpful to everyone. If you still want to know more information, please continue to pay attention to this website, we will update it for you from time to time.
Post time: Feb-17-2022