How should steam purging conditions be considered in the design of pressure vessels?
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As the title suggests, during the design process, how should steam purging be taken into account? Is it necessary to conduct a thorough verification of the pressure and temperature during steam purging?
It’s generally not used, I guess. 1. Since the process requires steam purging, the design temperature and pressure of the equipment generally do not deviate much from the steam pressure and temperature; otherwise, such a requirement would not arise ； 2. After all, purging is not a normal operating condition in production, and its duration is also short ； 3. Measures to prevent cross-contamination of media under production conditions must be considered ； 4. Setting of purge lead points.
If the design temperature and pressure can be accommodated within the envelope, no verification is needed; if not, it’s still advisable to conduct a verification
The requirements specified in the process are generally steam at 1.0 Mpa/250 degrees; however, the design pressure of many devices is only around 0.45/100 degrees, which clearly results in failure to meet the requirements. Is it then necessary to increase the pressure for steam purging? It’s hard to determine this degree
If the steam purging conditions are more severe than the normal operating conditions of the equipment, were the design conditions for steam taken into account in the equipment design?
The purge pressure is adjusted according to the equipment pressure. Increasing the wall thickness to accommodate the purge pressure is not a waste.
The container is designed for the most demanding conditions in which it will operate； Since there is a purging process, and the pressure and temperature under those conditions are higher than those required for the normal operation of the container itself, you must design and verify it according to the purging conditions. When designing special equipment, safety comes first over cost; it is a matter of principle
I saw some drawings designed by Beijing Huafu; they had the steam purging conditions checked
The steam purging condition certainly needs to be taken into account (there will be no problems with the equipment during steam purging). However, the design pressure and design temperature in the technical specifications should still be indicated as per normal conditions. The notes section for technical requirements specifies the temperature and pressure under steam purge conditions.