Safety valves and control valves are installed simultaneously
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I would like to ask the experts: why is there both a safety valve leading to the flare and a control valve leading to the flare at the same tower top? Is this intended as a secondary safety measure? ), if it is intended to relieve pressure when there is a slight excess pressure, then how should the maximum discharge capacity of the control valve be determined? Are there any regulations regarding this? Furthermore, if the control valve is used to relieve pressure in case of overpressure, can a safety valve also perform this function? I just can’t figure out what the purpose of adding another control valve is If it is absolutely necessary, then how is the discharge volume determined? It’s a bit messy written:)
Seeking advice from experts! Push it yourself
I would appreciate some guidance from experts; I’m also confused as to which standard and which clause specifies the requirement to add pressure relief valves to LPG storage tanks :Q
The control valve should be a fire emergency relief valve, that is, a BDV
Right above that, the functions of the BDV valve are as follows: 1. The BDV (blowdown valve) is related to the emergency shutdown system; its purpose is to safely release the materials inside the system (mostly gas) in the event of an emergency such as a fire, thereby reducing the pressure within the system. This avoids having to wait until the pressure exceeds the design limit before the safety valves take action to release pressure. It is recommended to consult API RP 521 – according to this standard, in the event of a fire, the stress levels on the steel plates of pressure equipment due to the heat cause them to fail even before the pressure reaches the level at which the safety valves would open. Therefore, it is necessary to reduce the pressure within the system to 7 kg/cm2 or half of the operating pressure (whichever is lower) within 15 minutes of a fire starting, so that the equipment will not explode even if it is affected by the fire. There are many constraints regarding the operation of the BDV valve; for example, the emergency shut-off valves must be closed before and after releasing the materials. It is closely linked to the ESD system, and this valve will not be opened unless there is proper authorization. 2. The installation of the flow-limiting orifice plate downstream of the BDV valve is intended to achieve throttling effects, by ensuring that the pressure drop occurs at the orifice plate rather than on the BDV valve itself. This helps to prevent erosion of the valve and thus extends its service life.
The safety valve is used for emergency discharge; it is a safety component that releases fluid when the set pressure is exceeded, thereby preventing the system from experiencing overpressure. The amount of fluid discharged is the maximum possible amount. The control valve is used to stabilize the discharge; it is a component that ensures system stability. At normal operating pressure, if the system becomes unstable and the pressure rises, discharge begins, and the amount of discharge can be controlled
:Lol, I’ve learned it! Thank you so much for your guidance.