Pressure vessel

1. Definition of pressure vessel
   The heat exchange equipment, reaction equipment, tower equipment, and other chemical equipment used in chemical production have different functions due to different service targets. The shape and structure vary greatly, the size varies greatly, and the internal structure is even more numerous. There are many kinds, but they all have a shell, which we call a chemical container. Therefore, the chemical container is the general term for housing the equipment used in chemical production.
   The medium usually has higher or lower pressure in chemical production, and chemical containers usually have to withstand pressure. According to the “Regulations for the Safety and Technical Supervision of Stationary Pressure Vessels,” chemical vessels meeting the following conditions are called pressure vessels.
   ① The working pressure is greater than or equal to 0.1MPa.
   ② The volume is greater than or equal to 0.03m, and the inner diameter (non-circular section refers to the maximum geometric size of the inner boundary of the section) is greater than or equal to 150mm.
   ③ The containing medium is gas, liquefied gas, and liquid whose maximum working temperature is higher than or equal to its standard boiling point.
   There are many ways to classify pressure vessels, which can be classified according to their purpose, wall thickness, pressure level, safety management level, shape, etc., into welding materials, etc., which can be determined according to actual needs.
   (1) Classification according to the nature of pressure
   It can be divided into two types: internal pressure and external pressure vessels. When the internal pressure of the vessel is greater than the external pressure, it is called an internal pressure vessel, and vice versa, it is an external pressure vessel. The internal pressure vessel can be divided into four levels according to the design pressure: low-pressure vessel, medium pressure vessel, high-pressure vessel, and super high-pressure vessel.
   ① Low pressure container (code L): 0.1MPa＜p＜1.6MPa.
   ②Medium pressure vessel (code M): 1.6MPa＜p＜10MPa.
   ③High pressure vessel (code H): 10MPa＜p＜100MPa.
   ④Ultra-high pressure vessel (code U): p=100MPa.
   The p in the above formulas is gauge pressure, which is the container’s design pressure. In an external pressure vessel, when the internal pressure of the vessel is less than an absolute atmospheric pressure (about 0.1 MPa), it is called a vacuum vessel.
   (2) Classified according to the role in the process
2. Reaction pressure vessel (code R)
   It is mainly used to complete the pressure vessel of the physical and chemical reactions of the medium. Such as various reactors, reaction kettles, polymerization kettles, and
   Towers, conversion furnaces, gas generators, etc.
3. Heat exchange pressure vessel (code E)
   The container is mainly used to complete the heat exchange of the medium. Such as various heat exchangers, coolers, condensers, evaporators, etc.
4. Separate the pressure vessel (code S)
   The pressure vessel is mainly used to complete the fluid pressure balance buffering of the medium and the gas purification and separation. Such as various separators, 10% filters, oil collectors, scrubbers, absorption towers, buffers, copper scrubbers, drying towers, stripping towers, sub-cylinders, deaerators, etc.