Hydraulic coking removal in delayed coking

Debinding will not block the feed inlet. Flat-bottomed covers generally have two feed inlets at the top; during coking removal, powdered coke can enter these inlets, and it is necessary to purge them before closing the tower to prevent the inlets from getting blocked

Our facility uses automatic gate-type bottom cover machines; since it is not possible to inspect the feed line, it is necessary to purge the feed line. On several occasions, the feed line has become blocked by coke dust and could not be cleared, which made the process quite time-consuming and troublesome. How can this be avoided during the coke removal process?

There are two reasons for this phenomenon. One reason is improper operation during low-pressure steam supply, high-pressure steam supply, or water supply adjustments, which results in a thick layer of hard asphalt-like substance forming on the walls of the feed line – we call this sticky oil. It melts at high temperatures; at room temperature, it sticks to the walls of the feed line like coke. Sometimes it can be quite thick; I guess everyone has seen this phenomenon when they were still using machines with manual bottom covers. At the same time, during the coking removal process, as the drill operates, the broken pieces of coke flow along with the coking water into the main water and steam supply lines through the feed line of the coke tower. Generally, at this stage the coke inside the tower has not yet been connected from top to bottom, so the coke and water cannot flow smoothly through the coke channels into the coke tank. These days, with the use of automatic bottom cover machines, a cross-shaped baffle is welded at the point where the feed line enters the cone section of the tower bottom cover to prevent large amounts of coke chunks from entering the feed line. However, when the amount of coke entering is large, or when the oil buildup on the walls of the feed line is too thick, resulting in a reduced flow cross-sectional area, and when steam is supplied too quickly during the purging process, a large amount of coke gets stuck inside the feed line or at the cross-section area. It causes blockage in the feed line. Later, we added a valve leading to the coking tank to the main steam and water pipeline; this valve remained open throughout the coking process, allowing the coke to flow back to the coking tank along with the water. When cleaning the pipeline with steam, we first cleaned this pipeline. This **reduces the occurrence of pipeline blockages.