Coke Drum Flow Distributions

Presented By

Julian Bedoya - Stress Engineering Services Inc.

Jeyam Kumar - DeltaValve

Conference: Mumbai 2016

Historically, the majority of coke drums, feed the drum vertically, centered in the lower head. With the advent of automated unheading systems it was necessary to move the feed line. The only available option has been to enter the drum through the side, either horizontally, or at an angle, using one or two entry points. These feed entry systems have been adopted by the industry, and have been in service long enough to understand the negative impact of changes to the thermal distribution across the coke drum, resulting in significant decreases in effective service life of coke drums.

The distribution of feed stream into the coke drum is critical to the delayed coking process and the life of the coke drum. The feed distribution determines the coke bed formation as well as the thermal loading on the coke drum during the filling and quenching process. The flow distribution into a coke drum and hence the thermal load is significantly affected by the feed nozzle configuration. The flow behavior in the coke drum for various nozzle configurations is evaluated using computer-based predictive flow analysis.

A multi-disciplinary design-by-analysis approach is applied to develop and design a novel center-feed nozzle. Computer-based predictive flow analysis is applied to design the center-feed nozzle to optimize the feed distribution into the coke drum. The mechanical and structural aspects of the center-feed nozzle are designed and evaluated using computer-based predictive structural analysis based on ASME Boiler and Pressure Vessel Code, Section VIII, Division 2. Creep and fatigue targets for the center-feed nozzle are achieved using design-by-analysis based on API 579 guidelines.

In service data collected from the field shows an improved temperature distribution over the coke drum, which results in predicted increase in remnant life. Several other operational improvements have also been reported.

This paper describes the flow analysis technique and flow behavior in coke drums. The relationship between field data collected and how it relates to understanding of the flow distribution in the drum and thought he coke bed is also discussed. The structural calculations related to design of the center feed nozzle are also described.

Refining Community