Method for preventing delayed coking fractionation tower high temperature section oil collection tank coking

Abstract

The present invention relates to a method for preventing delayed coking fractionation tower high temperature section oil collection tank coking. According to the present invention, the bottom disk of the oil collection tank adopts an inclined design; a liquid collection tank is arranged on the lowest end; a circulation oil or wax oil cold reflux inlet pipeline is arranged on the highest end position of the inclined bottom disk, and is connected with a distributor inlet pipe; a distributor pipe and the distributor inlet pipe are vertically paved on the inclined bottom disk; the inclined bottom disk is provided with gas rise holes; a circulation oil or wax oil extraction pipeline is connected with a tank type filter; reaction oil gas enters the lower portion of a fractionation tower; the liquid collection tank is pumped out through a circulation oil or wax oil reflux oil pump; and after the coke powder-containing circulation oil or wax oil is filtered through the tank type filter to remove the carried coke powder, the obtained substance is divided into two parts to return to the coking fractionation tower, wherein the one part returns to the position below the oil collection tank, and the other part returns to the coking fractionation tower oil collection tank. With the method, high temperature coking is avoided, cleaning of the media in the tower is ensured, coking and coke powder deposition are effectively slowed down, and the oil collection tank coke powder deposition problem is solved.

Description

technical field [0001] The invention relates to a method for preventing coking of an oil collecting tank in a high temperature section of a delayed coking fractionation tower. Background technique [0002] Delayed coking process is a deep thermal cracking process in which heavy oil is converted into dry gas, liquefied petroleum gas, coker gasoline, coker diesel oil, coker wax oil and petroleum coke in the coke tower. In addition to petroleum coke, other components escape from the top of the coke tower into the bottom of the fractionation tower in the form of high-temperature superheated reaction oil gas, and reversely contact with the washing oil for heat and mass transfer to produce circulating oil fractions, which return to the coking reaction section together with fresh raw materials Further high-temperature pyrolysis and condensation reactions are carried out to generate high-temperature reaction oil gas and petroleum coke. [0003] The fractionation tower of the delaye...

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Problems solved by technology

[0003] The fractionation tower of the delayed coking unit is a space for heat and mass transfer of high-temperature oil and gas from the reaction oil gas feed section to the wax oil extraction section at about 410°C to 360°C. The design of the oil collection tank in the high temperature section has always followed the conventional type, and the delay coking unit has not been considered The coke powder carried by the special medium causes widespread coke powder deposition and coking problems caused by high temperature, which affects the long-term operation of the fractionation tower and causes abnormal shutdown

However, as the raw materials become more and more inferior and the operating cycle ratio becomes lower and lower, this conventional oil collection tank design can no longer meet the current requirements for long-term operation of the device.

[0004] When the circulation ratio is lowered in order to increase liquid recovery, under the condition of low circulation ratio (less than 0.2), only a small amount of washing oil contacts with a large amount of high-temperature reaction oil gas to wash off superheating, and the reaction oil gas carries more in the upward process of the fractionation tower. Coke powder mostly comes from the coke tower; for raw materials with high asphaltene content and poor thermal stability, it is very easy to coke in the high-temperature section of the coking fractionation tower and the oil collection tank; because the oil collection tank requires a certain liquid level and residence time, coke powder The deposition problem is also becoming more and more prominent

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