How to deal with a coke tower overpressure situation?

1.2.1 Coke tower overpressure 1.2.1.1 Phenomenon 1) Sudden increase in pressure in the coke tower. 2) The temperature at the top of the coke tower rises. 3) Severe tower surging caused the safety valve to open. 4) The temperature at the bottom of the distillation tower rises suddenly. 5) Sudden changes in the bottom liquid level of the distillation tower. 1.2.1.2 Reason 1) The coke layer is too high, exceeding the safe headspace of the coke tower. 2) Changes in the properties of the raw materials result in a higher foam layer or an increased amount of oil and gas, exceeding the designed empty tower linear velocity for the coke tower. 3) During normal production, the defoamer is not injected in a timely manner, the amount injected is insufficient or the injection is interrupted, resulting in poor defoaming effects ； After tower replacement, the defoamer in the treatment tower was discontinued too early. 4) The unit’s processing capacity is too high, exceeding the designed linear velocity of the empty tower in the coke tower. 5) Excessive small steam volume or water contamination. 6) Excessive small water supply and large steam supply. 7) During preheating, the pressure in the production tower drops too rapidly. 8) When changing the tower, residual oil remains in the treatment tower. 9) The pressure in the distillation system drops too rapidly. 10) The quench oil flow rate is too high, the re-refining oil volume is excessive, or it contains water. 11) Excessive steam injection into the furnace. 12) The furnace outlet temperature is low, and the foam layer is too high. 13) Instrument failure. 1.2.1.3 Handling 1) Overpressure in the production tower: control the pressure in the distillation system to prevent overpressure in the distillation tower ； Reduce the feed rate to the heating furnace and increase the circulation ratio ； Identify the cause of the tower impact promptly and take appropriate action. 2) Address tower surging in the treatment tower, promptly identify the cause of the surging, and take appropriate measures. Go to the fractional distillation unit via the rear route to prevent overpressure in the fractional distillation tower ； For the backside steam blowing and venting unit, fully open the reflux FIC1150 at the contact cooling tower to stabilize the pressure of the contact cooling system. 3) Ensure proper cleaning of the distillation column bottom filter.

Phenomenon: 1) Sudden increase in pressure in the coke tower； 2) Rise in temperature at the top of the coke tower ； 3) In severe tower surging, the safety valve opens ； 4) Sudden increase in the bottom temperature of the distillation tower ； 5) The liquid level in the distillation tower rises; in severe cases, the bottom radiation pump becomes evacuated. Reason: 1) The furnace outlet temperature is low, causing the foam layer to rise ； 2) High processing volume, with the amount of coke produced exceeding the safe level ； 3) The system pressure fluctuates too much ； 4) The preheating temperature of the new tower is insufficient ； 5) When changing the tower, the oil from the new tower was not completely drained ； 6) Changes in raw material properties ； 7) The steam injection volume is too high. Treatment: 1) Increase the furnace exit temperature ； 2) Reduce the processing volume and take emergency tower replacement measures ； 3) Report to the team leader to balance system pressure as soon as possible ； 4) Ensure the preheating temperature of the new tower ； 5) When changing the tower, drain all the oil from the bottom of the new tower ； 6) Strengthen communication to stay informed about the properties of raw materials in a timely manner ； 7) Control the steam injection volume of the furnace properly ；

This post was last edited by lijianhuai on 2012-3-8 at 15:39. In actual production, a situation where the coke tower is overfilled should not occur; firstly, there is no moisture in the feed to the heating furnace, and the pressure at the outlet of the feed pump remains constant. There is only one vaporization hole inside the tower, and the key issue lies in the distillation tower. When steam is supplied in small amounts after cutting the four-way valve, fluctuations are likely to occur in the fractionation tower. It might be due to different manufacturing processes. We have been in production for 7 years, and to the best of my memory, there has never been any issue of tower flooding. Moreover, our gasoline and diesel are produced in a mixing unit before undergoing hydrogenation treatment. There is no control over the dry point of gasoline. In fact, when the distillation column is flooded, the oil-gas mixture carries the heavier components directly to the upper trays of the column. The temperature at the bottom of the tower is decreasing. I don’t know if you’re reading from books or just imagining things

If there is a collapse in the coke tower, the temperature at the bottom of the distillation tower will rise rapidly, as this collapse causes large amounts of petroleum coke and semi-coke to flow into the distillation tower. Petroleum coke and semi-coke are mixtures of liquids and solids; upon entering the distillation tower, they sink to the bottom of the tower, resulting in a rapid increase in the temperature there

It was a coking tower that experienced flooding, not a distillation tower; in one coking plant, the foam layer reached a height of 10 meters. Flooding occurred frequently after each change in the flow direction, and the bottom of the distillation tower became completely blocked. During shutdowns for maintenance, over 100 tons of coke were removed from the bottom of the distillation tower. Just because you haven’t seen it doesn’t mean it doesn’t exist.

The reason for the collapse of the coke tower is an excessive gas phase load inside the tower. It mainly occurs after tower replacement, when steam is supplied to the old tower; this is caused either by steam containing water or by an excessive amount of steam supplied ； Another issue is that large pressure fluctuations during the operation of the coke tower result in significant changes in the gas-phase load ； Reasons such as low feed temperature. Measure: Ensure that the steam is free of water or appropriately reduce the steam supply ； Slightly increase the feed temperature to the coke tower ； Stable operating pressure of the coke tower ； Maintain an appropriate empty height in the coke tower ； Defoamer ； Appropriately reduce the processing volume and maintain a reasonable gas velocity in the coke tower, etc

Why is there semi-coke in a liquid-solid form in petroleum coke? As long as the temperature at the furnace outlet is kept within the normal range and the amount of air supplied is appropriate, this situation should not occur. Besides, with a situation like the one you mentioned, can the quality of the coke be considered satisfactory? Most of what is blown into the fractionation tower is coke powder, with a portion of this coke powder entering the upper trays along with the gas phase. Is your question asking whether hot, high-temperature coke entering the fractionation tower causes the temperature at the bottom of the tower to rise? What happens after that lump of coke is blown away? Is the temperature at the bottom of the distillation tower increasing or decreasing?

Is it the high temperature at the bottom of the fractionation tower or the high temperature at the top of the coke tower? Unless the bottom temperature of your distillation column exceeds 410°, the bottom temperature of the distillation column may drop after a collapse in the coke tower.

In the coke tower, petroleum coke does not exist as a pure solid, but rather as a mixture of solid and liquid phases. Once it enters the distillation tower as a result of overpressure, the coke is cooled by the liquid phase present in that tower, turning it into coke powder. Even when this coke powder is heated to 400 degrees, a portion of it still turns into liquid heavy oil (or what is known as a precursor to coking)

If you have doubts regarding the tower flushing, think carefully: what form does the oil product coming out of the furnace tubes take when it enters the coke tower? Let me say one thing: in which household’s large blowers do not use oil, and the level in the vent tower does not rise (not just for water)? The oil that is heated through the furnace tubes contains gas, coke, volatiles, as well as a portion of heavy oil that has not undergone cracking or coking