On the spontaneous combustion issue of catalytic devices
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Hello, guys. I’ve just started learning about *catalysis, and there are many things I don’t understand. I hope you can help me figure them out. 1. The problem of spontaneous combustion of FeS. This substance tends to catch fire spontaneously when exposed to air, but when the two containers are heated, why doesn’t the high-temperature air cause spontaneous ignition? Is it because of the open space? If it’s only circulation that prevents spontaneous combustion, then why do some chimneys still catch fire spontaneously? 2. Gas-tightness issue of the distillation tower. Generally, the gas and oil blind flanges on distillation towers are removed after ensuring airtightness; so how is airtightness maintained at the flange openings after they have been removed? Also, how does the distillation tower itself achieve airtightness? I see some people say that steam is used for airtightness – how can one then identify the leakage points? 3. A common-sense question. How to prevent winter fire water from freezing? Can it be circulated directly at the fire water tank, with all the buried pipes being emptied? The lowest temperature here can reach -8 degrees
Bro, the FeS content in those two units isn’t high; FeS is mainly concentrated in the light oil system. Also, since the temperatures in those two units are high, it’s unclear whether spontaneous combustion has occurred； The testing of the distillation tower is of course carried out with the blind flanges in place; after the blind flanges are removed, there are fewer leak detection points on the flanges, allowing the testing to be conducted directly as the temperature of the distillation tower rises.
Yes, for FeS to catch fire spontaneously, a certain concentration is required; just having FeS present does not mean it will ignite on its own.
The FeS concentration in these two units is not high; it generally exists in the light oil fractionation pipelines.
All ferrous salts are prone to spontaneous combustion under certain conditions.
1. FeS will inevitably catch fire when exposed to air in a dry state. Most settlers have linings, with virtually no FeS. Even if there is a little, spontaneous combustion during the heating process is not noticeable, so it’s no problem. 2. After removing the large blind flange, connect the reaction and distillation systems; after increasing the pressure, inspect the area where the large blind flange was located – applying appropriate heat to tighten it is sufficient.
Buried pipelines do not require insulation or venting, as the underground temperature is generally above freezing, except in permafrost areas.
As everyone mentioned above, ferrous sulfide will self-ignite only when it reaches a certain concentration in contact with air. The concentration of ferrous sulfide is high in the oil and gas lines at the top of the fractionation tower as well as in the stabilization system, while its concentration in the settler is low; therefore, self-ignition generally does not occur.
FeS is a solid; how do you express “concentration”?
The lowest temperature there is only -8 degrees, so there will be no problem with buried wires
A common-sense question. How to prevent winter fire water from freezing? Can it be circulated directly at the fire water tank, with all the buried pipes being emptied? The lowest temperature here can reach -8 degrees. There is a water valve under the fire hydrants and cannons that is constantly draining water, so they don’t freeze; besides, the temperature isn’t that low anyway
1. FeS generally accumulates in the fractionated oil and gas separation tanks; reverse regeneration systems are rare. Even if it burns during the heating process, it causes no significant impact! 2. The distillation seal is of course made with steam; any leakage there can be seen at a glance ； In anti-reheat systems, since lining is used in many places, if steam is used, the initial furnace drying process becomes pointless ； Leaks are generally not likely to occur at the large blind flange, and heat tightening can also be carried out during the airtight heating process! 3. It’s not a big problem, but be careful so you don’t get too cold – otherwise it won’t be fun!