Regarding coking due to the backflow of slurry.
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Coking is severe due to the backflow of slurry; during each maintenance task, manual cleaning of the liquid accumulation trays in that area is required. Are there any good suggestions that can significantly reduce coking? It’s best to use renovation methods.
Slurry return fluid accumulation distribution tank? Generally, it is due to severe coking at the bottom of the tower or coking on the trays above the chevron baffles. Let’s start with the operations. First, determine the location of the vapor-phase temperature thermocouple, and then decide on the temperature control range. Strictly control the temperature of the vapor and liquid phases. Control the oil slurry circulation rate. Do not exceed the temperature limit. Our unit has not experienced coking under strict regulations for many years, ensuring long-term operation.
The chevron plates have long been able to prevent coking; there is only a slight amount of coking at the bottom of the tower. However, some coking also occurs in the area where the gas returns upward to the tower, as this area has a sump-like structure that makes it difficult to clean. Therefore, we strive to minimize coking. The temperature of the gas flowing upward in this area is around 300–310 degrees, and during each maintenance session, coking becomes quite severe in this region.
Coking? It really has never happened; tell me about your working conditions.
In daily production, control the slurry circulation rate, slurry solid content, and slurry density.
The fact that no coking occurs at the bottom of the tower while severe coking takes place at the area where the fluid returns to the tower indicates that the circulation rate in that returning section is low, and the temperature there is somewhat high. 1. Increase the circulation rate in the section where the fluid returns to the tower； 2. To prevent coking in the entire slurry system, it is possible to increase the circulation rate of the slurry system, that is, to operate it at a higher circulation rate.