Why is the purging signal set to 72 hours for space furnaces?

This is borrowed from Shell furnaces; it’s a safety check before starting up. During major shutdown repairs, the system is usually connected to the atmospheric environment, and it is necessary to repeat the purging procedure to replace the air and ensure safety. This time signal can also be artificially provided as an analog signal based on actual conditions, following the same principle as removing the flame detection signal interlock when starting up the equipment.

It seems to be a very thorough copy; they know the surface details but not the underlying reasons. In that case, analysis can be carried out after the vehicle has been parked for more than 72 hours; if it meets the requirements, a signal can be simulated, which is indeed an easy solution. But if there is a driving signal within 72 hours, no further analysis is carried out; meanwhile, if the oxygen level in the system is also not within acceptable limits, how can an accident in such a situation be explained – is it due to inadequate design or improper operation by the personnel?

This post was last edited by wang06120325 on 2015-10-7 at 18:04. Well, I’ve seen that the control system diagrams for space furnaces generally follow the Shell model; it’s a matter of signal feedback. Additionally, requiring that the oxygen content at the outlet of the water scrubber be less than 0.5 before driving is also a safeguard; therefore, there is no need to worry about safety issues. Previously, the oxygen content value was also determined through direct measurement using instruments, as long as the manual analysis showed satisfactory results. Furthermore, when the oxygen system is operated in automatic mode, steam extraction is generally activated, which also helps to prevent the oxygen content in the system from exceeding the specified level. In any case, foreigners do take quite thorough precautions in this regard. If the purging procedure is to be carried out thoroughly, it will result in a significant waste of nitrogen. Fortunately, the nitrogen piping for purging the vaporization furnace in space furnaces is relatively fewer in number.

Ultimately, it is still people who manually monitor and analyze the oxygen content; if the oxygen level is high, no one will dare to feed material in, even if the logical program permits it. So that signal is completely useless!

The original poster does not fully understand the logic behind space exploration and Shell’s cleaning processes. 72 hours is just one of the criteria to determine whether a purge should be carried out in the vaporization furnace; a purge is necessary when starting up the burner and using diesel, regardless of whether the 72-hour condition is met or not ； When the plant is shut down due to a malfunction only in the pilot burner, the flue gas level inside the furnace is relatively low, so the possibility of safety accidents is essentially none. In the event of a forced shutdown, it is possible to achieve the required oxygen level by performing a vacuuming process through the oxygen injection procedure upon restarting the system. The gasifier also has a logic for \"long and short\" purging

Could you explain in detail the logic behind short and long purges mentioned above? In the past, during replacement operations, a manual purge was used as an alternative to this procedure.

72 hours represents a pulse signal; during this period, the changes in oxygen content inside the furnace are monitored