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Delayed Coker Overview
A Delayed Coker or Delayed Coking Unit (also called a DCU or Coker) is a refinery unit employed to process the heaviest components of crude oil. The Coker cracks (converts) the asphalt-like feedstock to a combination of products for further processing to gasoline and diesel feedstock, a coal-like material called petroleum coke, plus light gas and byproducts. The feedstock is heater to 900 to 950 degrees Fahrenheit and then sent to a large Coke drum where it cracks and is 'coked'. The process results in lighter material separating from the heaviest material, which is converted to solid petroleum coke. Coke is a material resembling coal.
The gaseous and liquid products recovered from the process are hydrotreated to remove sulfur and other contaminants and sent to other refining process unit to be further processed into gasoline, diesel fuel, and other marketable products.
The Coking process is cyclic, i.e., two coke drum are operated in parallel with one drum being on the 'Coking' cycle while the other drum has the solid coke removed, i.e., cut from the drum with high pressure water jet and dumped into a concrete pit or onto a concrete pad. The typical coker consists of a two, four or more Coke Drums, a Coker Furnace, a jet water pump, compressor, fractionation, multiple heat exchanges, etc. All of this equipment is important and the reliability and capability to reliably operate, clean, and maintain the equipment should be the main 'driver' to the selection of the technology and contractor.
Coker Drums
Design and installation of the Coke Drums is critical to the long-term success of the Delayed Coker. Although the design of all equipment items is critical and can determine whether a Coker runs 3 years or 5-6 years between turnarounds, the Coke Drums are cyclic, receive the most stresses, and are the most costly and time consuming component of the Coker to replace if a more design and installation is initially selected.
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