If the flare system is equipped with a molecular seal, is it then possible to omit the water seal tank or flame arrester?

It’s better to have it for greater safety.

It is also best to install a liquid separation tank to filter out droplets of 6 microns, in order to prevent fire rain. Assume that the water seal groove, in addition to preventing air backflow, can also control the pressure of the exhaust air.

There are engineering examples with molecular seals installed but no flame arresters or liquid seal tanks. In some cases, it is indeed only possible to set a molecular seal. Because: although flame arresters serve to prevent air from entering, they can become clogged quite easily, especially with gases that are highly corrosive and contain condensate. Moreover, changes in emissions cause fluctuations in temperature; during the cooling process following a single emission, air may be drawn into the flare stack by the flame arrester. The level of the liquid seal in the liquid-sealed tank has a significant impact on emissions. An improper design can affect the pressure of the exhaust gases, and fluctuations in pressure often lead to vibrations, which can cause damage to the connection points and result in leaks. The selection of the liquid seal height also has a certain effect on flame stability. When using a liquid seal tank, valves must be installed to control the liquid level. In the event of an accident, it is not possible to adjust these valves in a timely manner; as a result, large amounts of superheated gas can carry the water from the liquid seal tank to the flare tip, blocking the cylinder and reducing the gas flow area. Therefore, when the gas emission volume in an accident situation is dozens of times higher than under normal conditions, a liquid seal is generally not used

The molecular seal is generally installed at the upper part of the flare stack and below the flame burner; its main function is to seal the entire flare stack with nitrogen, thereby ensuring the safe operation of the flare stack. The water seal tank is generally located at the lower part of the flare stack, after the liquid separation tank. Its main function is to ensure the isolation between the torch cylinder and the venting system, as well as to guarantee the safety of the venting pipeline in front of the water seal tank during operation. Recommendation: Neither of the two security measures should be omitted

The selection of the liquid seal height also has a certain effect on flame stability. When using a liquid seal tank, valves must be installed to control the liquid level. In the event of an accident, it is not possible to adjust these valves in a timely manner; as a result, large amounts of superheated gas can carry the water from the liquid seal tank to the flare tip, blocking the cylinder and reducing the gas flow area. Therefore, when the gas emission volume in an accident situation is dozens of times higher than under normal conditions, a liquid seal is generally not used. The view expressed on the 4th floor cannot be agreed with. It is indeed impossible to ensure the timely opening of the valves in an accident scenario; in fact, valve operation was not considered during the design phase. The water level in the local water seal tank is determined based on the system’s pressure drop. The scale of the torch is designed based on the conditions of the accident ； In most cases, a water seal is used, provided that the water in the seal does not contain volatile, flammable, or toxic substances.

Usually, a molecular seal is used in combination with a water seal tank, or together with a flame arrester; flame arresters are employed because some flare gases cannot be mixed with water.