Are there any good methods for removing coke buildup from the convection tubes in coking furnaces?

Online coking removal for convection tubes. Generally, a four-pass design is used; during operation, steam is introduced into one pass while the other three passes operate normally. The steam used for online coking removal, along with the coke that is removed, enters the coke tower together with the oil products in the other three passes. One is the constant temperature method ； The scouring effect of high-speed flowing steam on the coke scale layer is utilized, along with the chemical reaction between steam and coke at high temperatures to produce carbon monoxide and hydrogen. This method is only applicable to coking ovens with a short coking time. Another method is the temperature variation approach, which takes advantage of the difference in thermal expansion coefficients between the metal of the furnace tube and the coke scale layer inside it; by rapidly raising and lowering the temperature of the furnace tube, the coke layer is separated from the tube. Regardless of the method used, it is important to strictly control the wall temperature so that it does not exceed the maximum allowable operating temperature of the furnace tubes. Additionally, it is necessary to ensure that the steam pressure drop in the tube bank used for coking removal is greater than or equal to the internal pressure drop in the other tube banks that are operating normally, in order to prevent hot oil from leaking into the tube bank used for coking removal.

Two-way coking: Coking steam and air connections are provided at the inlet and outlet pipelines of the heating furnace; in actual operation, normal coking can be carried out from the inlet to the outlet. When coking is severe inside the tubes near the furnace inlet in a heating furnace, and normal burning in the usual direction is not effective in removing it, reverse burning from the outlet to the inlet can also be employed. For coking furnaces operating with heavy coking feed at low and ultra-low circulation ratios, where the effect of heat exchange and preheating of the feed material is inadequate, online coking and two-way online coking become more important in order to address the issue of poor burning.

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