Delayed Coking
Delayed coking is a thermal cracking process used in petroleum refineries to upgrade and convert petroleum residuum (bottoms from atmospheric and vacuum distillation of crude oil) into liquid and gas product streams leaving behind a solid concentrated carbon material, petroleum coke. A fired heater with horizontal tubes is used in the process to reach thermal cracking temperatures of 485 to 505oC (905 to 941oF). With short residence time in the furnace tubes, coking of the feed material is thereby "delayed" until it reaches large coking drums downstream of the heater. Three physical structures of petroleum coke: shot, sponge, or needle coke can be produced by delayed coking. These physical structures and chemical properties of the petroleum coke determine the end use of the material which can be burned as fuel, calcined for use in the aluminum, chemical, or steel industries, or gasified to produce steam, electricity, or gas feedstocks for the petrochemicals industry.
Operational Objectives
Pound for pound, coking is the most energy intensive of any operation in modern refining. Large amounts of energy are required to heat the thick, low grade petroleum residue to the 900-950 ºF temperatures required to crack the heavy hydrocarbon molecules into lighter, more valuable products. Due to complex relationships within the production process and the constraints of physics, coking is an expensive and volatile process.
Maintaining steady state operating conditions, ensuring plant safety and controlling energy consumption are imperative for the customer also responsible for turning a profit.
Operational Challenges
Refineries make significant investments in plant automation projects including distributed control systems to support process monitoring and control. While they collect and archive huge volumes of data on a daily basis, they have struggled with how to exploit this data to improve performance. They often generate, collect, store and then routinely purge the data, forever losing the value locked into this asset.
The Pattern Discovery approach will help your refinery leverage historical data, visualize performance problems before reaching critical thresholds, measure operator effectiveness to control the process, and determine economic impact of control variables by linking to energy consumption.
