Slide valves used to unhead coke drums have had a significant impact on the safety and efficiency of the unheading process in these vessels. Therefore, many refiners have changed to the inherently different inlet flow nozzle configurations that the slide valves have introduced. Single-side entry and dual-side entry have been common alternatives used as a result of the implementation of slide valves. Both of these configurations can depart from a centralized flow pattern and can create adverse flow and temperature distributions. Furthermore, these changes manifest themselves throughout the vessel with measureable mechanical integrity consequences in the cone, skirt, shell, and piping. This paper analyzes historic measured skin thermocouple data as a function of elevation of the coke drum. A total of three different refinery sites were included in this study; two of them having dual-side inlets, and one of them having a single-side entry. A statistical comparison was performed using the measurements focusing on the data that causes mechanical integrity problems in coke drums: temperature differences around the circumference and elevations, peak fill and peak quench rates.

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