Do your units equipped with acid gas for sulfur production have flame arresters?

There is always a flame arrester near the furnace for our acidic gases. It has been available since the first sulfur recovery unit in 1988.

Typically, the devices introduced do not have flame arrestors; domestic devices designed in the early stages did have them, but those designed more recently do not have flame arrestors.

There should be regulations for this; ours was designed in 2010

We have imported the process package; there is no flame arrester

Modern sulfur production furnaces for acidic gases no longer come equipped with flame arrestors, as the design of these furnaces takes into account the pressure that can occur during explosions between acidic gases and air. The design pressure of these furnaces is higher than the pressure at which an explosion might occur, so there is no need for flame arrestors.

I believe it is determined by the type of burner used in the sulfur production furnace; some burners are premix burners, which pose a risk of backflow, and it is unsafe not to install a flame arrester. On the contrary, many burners these days are non-premixed burners, which fundamentally prevent the occurrence of backflow; therefore, the use of flame arrestors is unnecessary.

1. Actually, I also think there’s not much need for acid-resistant pipelines with flame arrestors, but why are they necessary for fuel gas? Under normal operating conditions, neither acidic gas nor fuel gas contains much air. 2. Under normal conditions, for acidic gas nozzles, the actual location where backfire can occur is within the nozzle itself; it is practically impossible for backfire to reach the flame arrester located outside the nozzle. 3. It is required that proper purging of the acidic gas pipelines be carried out before starting up the unit; if the entire acidic gas system is filled with air before acidic gas is introduced, then as the hydrogen sulfide concentration increases after the acidic gas enters, there will always be a period of time during which the concentration falls within the explosive range. 4. Having worked with sulfur for over 20 years, in 2013 I experienced acidic gas tempering in the furnace for the first time, which resulted in the inlet pipeline of the furnace being burned through.

Could you explain in detail the relationship between the design pressure of a furnace and its explosion pressure?

Could you tell me under what circumstances it was tempered at that time? We direct the acidic gas to the valve at the root; the pressure of the acidic gas there is much higher than inside the furnace. It shouldn’t cause backfire when it’s put into use, right?

Now, flame arrestors are not installed on the fuel gas line either. Also, for the acid gas system purging, isn’t it done using nitrogen?