The present invention is generally directed to a device for injecting heated residual oil into a coke drum as part of a delayed coking process. More particularly, the present invention is directed to a retractable center feed injection device which allows feeding the residual oil into the coke drum from a bottom and center of the coke drum using side-feed entry.
Delayed coking is one process by which petroleum coke can be produced. As a brief overview, the delayed coking process involves heating byproducts of the oil refining process, known as residual oil, in a furnace to its thermal cracking temperature of approximately 485° to 505° C. This heated residual oil is then pumped into a coke drum where the heat and pressure that build up within the coke drum complete the thermal cracking process. As the heated residual oil cools, petroleum coke is formed which can then be removed from the coke drum.
It is typically desirable to feed the heated residual oil from the bottom and center of the coke drum. One reason for this is to minimize the uneven heating of the walls of the coke drum that may otherwise occur if the residual oil is fed towards one side of the wall. To accomplish feeding the residual oil from the center, various so-called “center feed” systems have been developed. These center feed systems employ an injection nozzle which can be inserted into and retracted from the center of the coke drum. Examples of center feed systems are described in U.S. Pat. Nos. 8,702,911 and 8,545,680.
These prior art center feed systems employ an injection nozzle that is contained within an inlet sleeve through which the heated residual oil is fed into the injection nozzle. In other words, the combination of the inlet sleeve and the injection nozzle forms the feedline. As a result, all components, including those used to extend and retract the injection nozzle must be configured to withstand the high temperature and pressure of the heated residual oils that they carry and are therefore relatively costly. Additionally, due to the harsh environment in which these components operate, they can require frequent maintenance leading to downtime in the delayed coking process.