What are the hazards of coking inside the reaction heating furnace tubes?

When coking occurs in the tubes of the reaction heating furnace, the temperature of the reaction materials drops. This leads to an increase in the amount of fuel gas used, resulting in excessively high temperatures inside the furnace. As the furnace temperature rises, the temperature of the outer walls of the tubes also increases. Once this temperature exceeds a certain level, the outer surface of the furnace turns dark red; if this condition persists for too long, there is a risk of tube rupture. So it is indeed very dangerous.

Local high temperatures cause significant damage to the furnace tubes; when they exceed the tube’s maximum tolerance temperature, it can lead to serious accidents

In addition to the hazards mentioned by those above, I would like to add that due to coking, the coke particles will end up in the reactor inlet distributor and the catalyst bed, causing the reactor pressure difference to increase rapidly; in severe cases, the operation must be stopped immediately.

Coking occurs inside the furnace tubes, which reduces their heat transfer efficiency. The medium flowing within the tubes does not reach the temperature required by the process, and the outer walls of the tubes are not cooled properly; as a result, the wall temperatures become too high, increasing the risk of tube rupture and leading to serious consequences!

I. Coking is the phenomenon in which the oil inside the furnace tubes undergoes thermal cracking when the temperature exceeds a certain threshold (the heavier the oil, the lower the critical temperature), resulting in the formation of free carbon that accumulates on the inner wall of the tubes. Coking causes a sharp rise in the tube wall temperature, exacerbating corrosion and high-temperature oxidation of the furnace tubes, leading to bulging and cracking of these tubes. It also increases the pressure drop within the tubes, deteriorating the operation of the furnace; in some cases, this even forces the installation to shut down prematurely. II. The process of tube damage caused by coking is as follows: coking begins inside the tube, which raises the temperature of the tube wall and thus intensifies surface oxidation. Oxidation thins the wall of the furnace tube, and the thinned areas bulge first under the combined effect of internal pressure and heat. When the furnace tube bulges, a gap is created between the inner wall of the tube and the coke layer, which causes the temperature in other parts of the furnace tube to rise as well. This leads to further oxidation and thinning of the tube, ultimately resulting in its rupture.

1 Reduced heating efficiency of the furnace 2 Low initial dew point of crude oil 3 Local overheating is detrimental to the furnace tubes

The thermal efficiency of the furnace decreases; if this happens over a short period of time, it can cause localized overheating of the furnace tubes as well as elevated local pressures! Under high pressure, the pipes are prone to bursting! It’s dangerous·