Drum safety valve and drum pressure

For details of Article 1, see GB150.1 Appendix B3.3.2. Secondly, as pressure increases, the boiling point of water rises, and more heat is required to vaporize an equal amount of water ； At the same time, the temperature drop of the heat source decreases, resulting in a reduced total amount of heat supplied. SO generates even less steam. It’s like increasing the pressure to the saturated vapor pressure of water at the highest temperature of the heat source medium – not a single drop of vapor will be produced.

There are three situations in which two or more safety valves are required: 1. Due to limitations in the size of the safety valves, a single safety valve is not sufficient to meet the operational requirements； 2. The two safety valves are provided to take into account different operating conditions; this helps to prevent large fluctuations in the device when only low-level discharge is required, and it also allows for different methods of handling emissions depending on the operating conditions. Two safety valves with different set pressures serve different purposes. A safety valve with a low setting pressure is called a control safety valve, while one with a slightly higher pressure is called a service safety valve. The control safety valve operates first to trigger an alarm; it also helps to reduce the pressure in the waste boiler. If the pressure in the waste boiler continues to rise, then the main safety valve activates. This approach not only helps to reduce steam waste but also prevents excessive fluctuations in the pressure of the waste boiler. 3. Sometimes, in order to meet the requirements for safety valve calibration without affecting production, two safety valves can be used; one of these valves must be capable of handling all operating conditions, and there should be a manual valve in front of the safety valve. It is only in recent years that we have come to know about online verification of safety valves. API 520 and ASME both provide specifications for the set pressure of multiple safety valves. The API specifies that the maximum relief pressure for multi-valve systems is 116% of the maximum allowable operating pressure of the pressure vessel ； ASME VIII.1 specifies that for boilers (waste heat boilers or drum boilers) with a gas generation rate of over 1800 kg/h (like this value), dual valves must be installed, and the maximum set pressure (S.P.) of these dual valves shall not exceed 3% of the vessel’s design pressure. For different operating conditions, API2000 provides two explanations for the use of dual valves in low and medium pressure storage tanks: 1) as a safety backup; 2) to provide an additional valve that meets the drainage requirements in extreme situations such as fires, thereby preventing a single valve from opening frequently due to non-extreme conditions ； Parallel double valves are installed on critical equipment to facilitate online maintenance; isolation valves are placed before and after each valve, with minimum mechanical interlocking required.

I’m currently learning about boilers. Do any of the more experienced colleagues have any relevant materials? Could you share them with me? Thank you