Regarding catalytic top-loop equipment
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May I ask whether the equipment in the overhead circulation system of a heavy oil catalytic distillation tower falls under the category of pressure vessels? Isn’t the pressure in such a system around 0.2 MPa when it is operating normally?
Sure, as for the definition of pressure vessels: A pressure vessel is a closed device used to hold gases or liquids and is subject to certain pressures; it refers to fixed or mobile containers in which the maximum operating pressure is 0.1 MPa (gauge pressure) or higher, and the product of pressure and volume is 2.5 MPa·L or higher, for gases, liquefied gases, and liquids whose maximum operating temperature is equal to or higher than their standard boiling point； Gas cylinders designed for gases, liquefied gases, and liquids with a standard boiling point of 60°C or lower, whose nominal working pressure is 0.2 MPa (gauge pressure) or higher, and whose product of pressure and volume is 1.0 MPa·L or higher ； Oxygen chambers, etc. ”
We have two lift columns here; the back pressure is 0.14–0.15 MPa, while the main distillation pressure is 0.1–0.11 MPa. The top recycle stream is in a low-pressure vessel, and its pressure is above 0.08 MPa by the time it reaches the compressor inlet
1. Class III pressure vessels are those that fall under one of the following categories: high-pressure vessels； Medium-pressure vessels (only for media with extremely high and high toxicity) ； Medium-pressure storage vessels (only for flammable or moderately hazardous media with a pV product of 10 MPa•m3 or greater) ； Medium-pressure reaction vessel (only for flammable or moderately hazardous media with a pV product of 0.5 Pa•m3 or greater) ； Low-pressure vessels (only for media with extremely high or high toxicity levels, and a product of at least 0.2 MPa•m3) ； High-pressure and medium-pressure shell-and-tube waste heat boilers ； Medium-pressure glass-lined pressure vessel ； Pressure vessels manufactured from materials with a high strength level (meaning that the minimum specified value for tensile strength in the relevant standards is 540 MPa or higher) ； Mobile pressure vessels, including railway tank cars (for liquefied gases and cryogenic liquids), tank trucks, and tank containers (for liquefied gases and cryogenic liquids), etc ； Spherical storage tank (volume greater than or equal to 50 m3) ； Low-temperature liquid storage containers (capacity greater than 5 m3). Low-temperature liquid storage containers (with a volume greater than 5 m3). 2. Pressure vessels of Category II: Such vessels are considered to be of Category II if they meet one of the following conditions: Medium-pressure vessels ； Low-pressure vessels (only for media with extremely high and high toxicity) ； Low-pressure reaction vessels and low-pressure storage vessels (only for flammable media or media with moderate toxicity) ； Low-pressure shell-and-tube waste heat boiler ； Low-pressure glass-lined pressure vessels. 3. Category 1 pressure vessels: Low-pressure vessels other than those specified above are classified as Category 1 pressure vessels. It can be seen that the domestic classification method for pressure vessels takes into account various influencing factors such as design pressure, geometric volume, material strength, application scenarios, and the degree of hazard posed by the medium. For example, depending on the properties of the medium contained or the functions of the container, and thus on the level of potential hazard, low-pressure containers can be classified as category 1, category 2, or even category 3 pressure vessels