Coker drum

These gigantic pressure vessels were over 100 ft. (30 m) high, 27 ft. (8.2 m) in diameter, and the main body was a straight side cylinder 74 ft. (23 m) long. The cokers were designed for 55 psig (380 kPa) internal pressure. The coker drum has a dome-shaped top... 

Figure 3-10 Conditions at the time of the failure of the coker drum.

Figure 3-11 Close-up of the destroyed coker drum—crushed in like an aluminum beer can. Courtesy of S. O. Kapenieks.

Further study revealed that the A Unit was being steamed out just after the pre-op crew shut off steam to the B Unit. The steam in the B Unit continued to condense as the unit cooled while steam continued in the A Unit for two additional days. The range of the pressure transmitter on the B Coker Drum was 0 to 60 psig, therefore it could not indicate a negative pressure. 

The investigation team recommended that the vent line be modified to eliminate any possibility of a trap in the vent line. The team also recommended that a low-pressure alarm be engineered and installed to alert the control room operator of low-pressure conditions within the coker drums. 

Cracking and Coking. The dilute bitumen is pumped into coker drums, where it is cracked to yield gas and crude oil overhead, which goes to the refinery. Residual coke contains all of the residual sand and clay which could not be removed in the final extraction, and therefore it is used only as a fuel for the boilers. 

Figure 3-9 Collapsed coker drum in a refinery. Courtesy of S. 0. Kapenieks.

The pre-op crew steamed out the B Unit first and vented it through the 8-inch steam vent piping. The failure occurred about four days later. An eyewitness in the operators shelter heard what sounded like a muffled explosion and ran out the backdoor to. see if he could locate fire or smoke. Fortunately, no fire could be seen, but the collapsed coker drum was very visible. 

Figure 1 depicts the 100 ml, 7/8" ID steel coker drum used in these experiments. The coker was heated in a furnace, fitted with three independently controlled zones, and was equipped with gas and liquid measurement and recovery systems. Coke recovery in the form of plugs was carried out by the use of a hydraulic ram or lathe operating on an aluminum rod with the same diameter as the preheater plug. 

Figure 1. Experimental coker drum and typical temperature profile.

Coker drum safety switch interlocks and controls are important. A few issues related these systems shall include but not be limited to the following ... 

SIS TECH Introduces Coker Drum Safety System for Crude Oil Refineries, September 2010. http //www.automation.com/product showcase/sis tech introduces coker drum safety system for Crude Oihrefineries. 

Coker Drum De-Heading SIS Tech Application Catalog http //siS tech.com/applications/ diamond Sis/coker drum de-heading/. 

The forest has largely reclaimed the Amoco Refinery in Destre-han, Louisiana. A large sugar maple sprouts from a long since forgotten control room. If one didn t know, the delayed coker drum structure might be mistaken for a ruined temple. Brick chimney stacks rise defiantly above the feathery tops of the cypress trees. 

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