Problem of coke powder carryover in delayed coking

Note: Quench oil can prevent the carryover of coke powder from the top of the coke tower.

There is no way to solve it; it’s inevitable that the pace must be slowed down.

The main measure to reduce the amount of coke powder carried away is to decrease the linear velocity in the coke tower; this, however, will inevitably reduce the plant’s processing capacity, and it is generally not adopted in practice. Additionally, injecting quench oil and defoamers can help reduce the amount of coke powder carried away, but they cannot solve the problem fundamentally. Therefore, control measures must be taken in the distillation tower, such as increasing the feed of residue oil, raising the amount of coke powder washing, and controlling the level of coke content in the products. However, this will lead to an increase in the circulation ratio of the coking plant, which in turn reduces its processing capacity. In short, the issue of coke powder carryover in coking units is currently a difficult problem to resolve. It is hoped that those working in the coking industry will pool their ideas to find a thorough solution.

Increasing the processing capacity and reducing coke dust carryover are indeed a contradiction; one must weigh the pros and cons.

In the coke tower, it depends on the settling space; in the pipes, it depends on the flow velocity. Regarding these two key factors, a balance needs to be found with the processing capacity of the plant. Since the two are a pair of contradictions, it is impossible to have the best of both worlds

Problems related to the carryover of coke dust at the top of the coking coke tower: 1. Production must be kept stable, with an appropriate air space height maintained. 2. The dosage of the defoamer should be controlled, and it should be applied for as long a time as possible. 3. The location and amount of quench oil injected need to be appropriate. 4. The amount of steam used for blowing, as well as the duration of this process, should be minimized.

Increase the operating pressure, raise the amount of quench oil injected at the top of the tower, and reduce the height of the foam layer

Coking wax oil contains coke dust; is there a good solution for this?

Delayed coking carries coke dust, and the amount of coke dust carried can be reduced by optimizing the washing process in the fractionation tower.

A delay coking discussion group has been established; everyone is welcome to join it. The delay coking discussion group’s ID is 20389863. Welcome to all experts in delayed coking technology to exchange ideas together.

Oil and gas coke powder entrainment in the coke tower is inevitable, but it can be reduced by injecting quenching agents and using defoamers. There are quench oils that are injected into the middle section, and those that are injected with contaminated oil. I think it’s better to add oil in the middle stage. The height of the coke tower also needs to be properly controlled. Increasing the pressure in the coke tower can reduce the carryover of coke dust, but this approach is not advisable as it leads to a decrease in liquid yield. The pressure control of the coke tower should not exceed 0.18 MPa.

The location and method of injecting quench oil and defoamer at the top of the coke tower are of great importance. Injecting the quench oil in a circular pattern at the lower end of the gas-oil line can effectively serve a washing purpose. The inlet for the defoamer should be positioned about 3 meters inside the coke tower, so that it can reach the foam layer effectively and carry out its defoaming function; otherwise, under conditions of high temperature and high gas flow rates, the defoamer will be carried into the distillation tower before it can have any effect.

I think chemical scale inhibitors and anti-coking agents are more effective!

Pay regular attention to calculating the oil and gas line velocity in the coke tower, ensuring that it remains at or below 0.14 meters per second

Appropriately reduce the height of the coking layer; increase the amounts of defoamer and quench oil as needed. Ensure proper reflux in the fractionation tower, and clean the filters promptly

1. Reduce the linear velocity of the gas in the coke tower. 2. Inject quench oil. 3. Add antifoam agents or coke inhibitors, etc

Control the pressure well, add an antifoaming agent; keep the temperature too high, and reduce the processing volume appropriately

If there isn’t enough headspace, the only options are to inject quench oil and add antifoam agents

Besides what everyone has said, is it possible to add two parallel filters to the main gas line, to be used in case anything goes wrong?

Reply to 20# Li Haifang: By connecting two large filters in parallel, the resistance increases. In a coking unit, it’s better to have a lower pressure; however, once filters are installed, the pressure has to rise.