In Oil industry and other industries, they used a spherical tank. What are the advantages of these types of tanks. I tink, there are many reasons for this type of shape, such as:
1) distribution of forces exerted by liquid on the spherical wall.
2) Distribution oh heat and mass transfer.
3) avoid dead zones.
Spheres are more cost effective than bullets for large sizes primarily because they take up less space and require less metal to build. Cylyndrical bullets are used for smaller applications.
A spherical pressure vessel has approximately twice the strength of a cylindrical pressure vessel with the same wall thickness, so it is often more economical for large sizes.
https://bnhgastank.files.wordpress.com/2014/09/comparison-of-lpg-sphere-with-lpg-cylindrical-bullet.pdf
The spherical storage is used for high pressure gases. The distribution of pressure is uniform upon the tank storage. There is no dead zone in the shape of the tank. It is suitable for Ammonia industry and for LPG industry.
on an cylyndrical tank you have weldings in a "sharp" angle at the roof which are less strong than the linear weldings of a spherical tank and therefore it's making the spherical tank stronger to pressure, mostly the spherical tanks are used for liquefied gasses.
Dear Eric,
Ok, thank you very much for the answer. It's good from you.
kind regards!
Dear Rick Manner,
Thank you very much. Your answer is accurate and detailed.
Kind regards!
Dear Fakhri Ibraheem,
Thank you very much for the answer. It's good from you.
best regards!
Sphere contains more volume for the surface area. Also metal thickness is sometimes about half as much as a cylinder of the same diameter for the same pressure rating. Pressure can be contained by spreading the stresses and strains more uniformly. Pressure vessel handbook is a good reference. In every case you need a qualified designer who applies the accepted standards for the situation, both for new and old equipment, and for unusual cases like leaks and the range of possible operating problems.
Dear Adel Queslati,
Following Advantages
1. The stress resistance will be uniform.
2. Sphere contains more volume for the surface area.
3. Also metal thickness is sometimes about half as much as a cylinder of the same diameter for the same pressure rating.
4. Pressure can be contained by spreading the stresses and strains more uniformly.
5. The cost --- The wall thickness of a spherical shell will be about half the wall thickness needed for a cylindrical shell for holding in the same pressure. So, in a spherical container you use a thinner shell which means lesser cost and weight.more economical.
6. Area:Volume ratio --- The area that a sphere occupies will be lesser compared to a cylindrical container of the same volume.
Disadvantages
Spherical shell pressure vessels are more expensive than cylindrical pressure vessels to fabricate, and this higher price is only justifiable for large vessels.
Difference in the Post Weld Heat Treatment (PWHT) Process
If PWHT is a code or process requirement, the PWHT for cylindrical shell pressure vessels generally are done in the furnace, and if the vessel is too long, it is done in two heating process with a 5 ft. overlap.
But PWHT for spherical shell pressure vessels are done by one or more high velocity burners that are fired into the vessel using the top or bottom man ways (or both) as burner entry and exhaust positions.
This is done because using a PWHT furnace is not possible.
regards,
Prem Baboo
Dear Yin Zhe,
Thank you very much. It's goos answer from you.
kind regards!
Adel
The spherical tanks can withstand very high pressure, this is why they are used to store liquid gasses such as LPG.
As we know that, pressure is directly proportional to temperature. In sphere, during day time, only 1/4 th of the surface area is covered by the sun-rays. in other shapes, almost(1/2) 50% of the surface area will be covered by the sun-rays. As in a sphere, less area is covered by the sun rays and hence gas will be absorbing less heat and hence less effect on pressure rise. As in an industry, gases always handled safely hence storing a gas in a sphere is more safer than other.........
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