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

The flame arrester might not be necessary. But I think a water-sealed tank is still necessary to ensure intrinsic safety, in cases such as a nitrogen supply interruption.

A molecular seal prevents flashback at the torch tip, while a flame arrester prevents flashback in pipelines; the function of a water seal tank is similar to that of a flame arrester. I think the water-sealed tank flame arrester can be omitted. However, the investment in a flame arrester is not high, and it’s not a bad thing to have an additional safety measure.

There are engineering examples with molecular seals in place 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 emission levels cause fluctuations in temperature; during the cooling process of a single emission, air may be drawn into the flare stack by the flame arrester. The height 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, resulting in damage to the connection points and 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 under accident conditions is dozens of times higher than under normal conditions, a liquid seal is generally not used.

Am I worried that using it for a long time will clog the flame arrester, thereby causing poor venting?

Whether to use a molecular seal or a water seal tank separately, or to use both, depends on their respective functions. 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.

Thank you all. I’m currently working on the torch system, and I’ve learned a lot by reading your posts :victory:

I think both molecular seals and liquid-sealed containers are needed

Agree with the opinion from Floor 6; the water level control in the water seal tank can be handled automatically

If low-temperature gases are emitted, the liquid seal tank can no longer be used. Actually ； What I most want to know is whether having a molecular seal is sufficient, so that there’s no need for a water seal or a flame arrester anymore.

If a molecular seal is used, a water seal is not necessary; it’s a choice between the two. If money is no object, both a molecular seal and a water seal can be used, but remote purging gas is essential.