Auto ignition temperature identification of Ammonia plant streams

Forums Risk Registers Discussions New near misses in ammonia plants Auto ignition temperature identification of Ammonia plant streams

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      Hi everyone,
      I am Muhammad Umar Riaz, Sr. Process Engineer from Fatima Fertilizer company Ltd, Pakistan.
      Recently we faced Feed gas leakage at inlet of Primary Reformer piping but luckily we managed to contain the leakage with box up clamp without any downtime and safety concern.
      As a plant operator we want to identify the auto ignition temperature for all gaseous streams of Ammonia plant in order to document the risk associated with potential leak at plant and its associated safety hazard.
      I request from members of this forum to mention if they did identification of auto ignition streams at their plant or there is any company doing this type of study for plants.?

      Muhammad Umar Riaz


        you only need to worry about primary reformer exit & secondary reformer exit as these are of higher temperatures which can autoignite hydrogen present in the process gas of the stream
        Autoignition of Hydrogen is 500c


          Hi Muhammad,
          One other factor to consider is the risk of static discharge supplying the energy required for ignition even though the actual gas temperature is well below autoignition temperature. This is a common event and very unpredictable depending on atmospheric charge gradient and local charge generation by the jet of gas.
          I hope others have more depth of knowledge re: this topic and join the conversation.


            Yes process gas containing H2 could catch fire even at ambient conditions with static discharge and hence, please fix any H2 gas leaks on a high priority.


              To concur with the good advice cautioning that fluid temperature and auto-ignition is not the only mechanism by which rich H2 can ignite, I’d suggest that those interested consult the advice found in API STD 521, Pressure-Relieving and Depressuring Systems. My 7th Ed. copy at Release of Hydrogen-rich Streams recounts empirical work by NASA and notes that energy as low as 0.017 mJ has been found to ignite H2. Iron/Iron Oxide particles, such as that found in a vent, can also provide a source of ignition.

              In short, in practice hydrogen is extremely easy to light off.

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