For the emergency shut-off valve of ammonia ball tanks, is it better to use a valve that operates on air pressure to open or one that operates on air pressure to close?
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I would like to ask everyone: currently, the liquid ammonia spherical tank needs to be modified to include an emergency shutdown system. Which type of valve is better to use for this purpose – a valve that opens when air is supplied or one that closes when air is supplied?
In emergency situations, air-operated valves are generally used; if air-operated valves are chosen, in the event of a serious accident at the facility, there may be no instrument air available. How can you then close such valves? ? ?
What about the inlet cut-off valve for that spherical tank? We are an ammonia synthesis plant
The gas phase of the spherical tank is equipped with gas-operated valves; even in the worst-case scenario of power loss or loss of instrument air, these valves can still be opened, preventing overpressure in the spherical tank. The liquid phase, on the other hand, uses air-operated valves.
Where should the import cut-off device be installed? If it is placed on the low-pressure pipeline, the risk level becomes very high
For gas, it is a valve that opens when gas is present; for the liquid phase, it is a valve that closes when gas is present
Emergency shut-off valves are primarily used to prevent massive leaks of liquid ammonia in the event of serious accidents such as pipe ruptures, which could otherwise lead to uncontrollable situations; therefore, from a safety perspective, FC valves, that is, air-actuated valves, should be chosen. Preventing overpressure still relies on safety valves
The material inlet and outlet pipelines of the spherical tank must be air-operated valves; the purpose of installing quick-cut valves is to isolate the spherical tank as quickly as possible in the event of an accident. For the purpose of protecting the spherical tank itself, the vapor pressure regulating valve for the tank should be a gas-acting valve.