Discussion on jacketed vessel design
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This post was last edited by HSLJHZ on 2017-7-8 08:09. Hello everyone from CNOOC: There is a jacketed mixer; during operation, the pressure inside the tank is at atmospheric level (diameter 2800), while the pressure in the jacket is 0.4 MPa (diameter 3000). When selecting the design pressure, 0.001 MPa is adopted for the vessel interior as for a pressure vessel at normal pressure, while 0.42 MPa is used for the jacket. The static pressure of the liquid column on the upper head (flat cover) of the inner cylinder is 0; the static pressure of the liquid column in the inner cylinder is 0.04 MPa, while the static pressure of the liquid column on the lower head is 0.44 MPa. Using sw6 for calculation, only 7 mm is required for the upper head (flat cover). However, during the hydrostatic test of a jacketed vessel, the inner cylinder needs to be maintained at a pressure of 0.028 MPa; if the thickness of the flat cover is calculated based on this pressure, then its thickness would need to be around 30 mm. This results in serious waste. Question: 1. Does this atmospheric pressure inner cylinder not fall under the category of pressure vessels, and therefore does it not require supervision and inspection? 2. When maintaining pressure in the inner cylinder, how should the flat cover be sized – should 30mm be chosen? Are there any calculations for hydraulic pressure verification with a flat cover? 3. Is it possible to provide temporary protection for the flat cover’s reinforcement plates while maintaining pressure in the inner cylinder?
The working pressure of the inner cylinder is at atmospheric pressure, so it does not fall under the category of pressure vessels; however, if steam is present in the jacket, this reactor still needs to be classified and subject to regulation. The flat cover cannot be temporarily reinforced during the hydrostatic test, as pressure testing for future inspections of the reactor also needs to be taken into account. The flat cover has poor stiffness, and it also needs to be strengthened due to the installation of a mixing system.
It’s better to design the flat cover as a reinforced plate right from the start. And doesn’t the inner cylinder need to be designed for negative pressure?
Since there is a liquid inside the jacket, should the flat cover be designed based on the pressure retention value?
Since there is a liquid inside the jacket, should the flat cover be designed based on the pressure retention value?
Since there is a liquid inside the jacket, should the flat cover be designed based on the pressure retention value?
The inner cylinder has been checked under negative pressure.
The inner cylinder has been checked under negative pressure.
The flat cover is stress-checked according to the hydrostatic test pressure, that is, it can be calculated using 0.9REL.
The jacket contains a liquid, and the flat cover as well needs to be designed based on the pressure retention requirements. Pressure retention in the inner cylinder is primarily related to the allowable negative pressure of that cylinder; it has nothing to do with whether there is a liquid in the jacket. If the jacket contains a liquid, the equipment does not need to be classified nor subject to inspection. However, if the jacket contains a gas, then classification and inspection are required.
The jacket contains a liquid, and the flat cover as well needs to be designed based on the pressure retention requirements. Pressure retention in the inner cylinder is primarily related to the allowable negative pressure of that cylinder; it has nothing to do with whether there is a liquid in the jacket. If the jacket contains a liquid, the equipment does not need to be classified nor subject to inspection. However, if the jacket contains a gas, then classification and inspection are required.