Up Time Magazine- August/September 2008

infrared upload Crack Thermography Using Infrared To Inspect Catalytic Cracking Units by Bob Winship T he ducts and vessels on oil refinery catalytic cracking units are lined with refractory materials to safely and efficiently contain the high internal temperatures and pressures of the processes inside. Failure to detect anomalies in these refractory linings can have costly, even deadly consequences. Infrared thermography has proven itself to be the best overall tool for detecting these heat anomalies. The following is a case study explaining how the infrared scanning process is used to find anomalies, examples of false positives and corrective actions taken to repair problems. into the lighter forms desired. Once this reaction takes place, the processed petroleum products are pumped off for further refining, whereas the spent catalyst is recycled and regenerated to be used again. The spent catalyst exits the Reactor through a Spent Catalyst Standpipe. The spent catalyst is then fed into the catalyst Regenerator through the Reactor Spent Catalyst Riser to be regenerated and cleaned for the next cycle. Hot CO gasses are also fed into the Regenerator through a Regenerator Flue Gas Line to provide the heat necessary for the regenerator operation. The regenerated catalyst is then fed from the regenerator into a Regenerated Catalyst Standpipe to be carried back to the Reactor through the Catalyst Feed Riser. Up to 55 tons of catalyst can be cycled per hour. To better explain how infrared benefits the oil refining process, it is helpful to first understand how crude oil is processed into fuels and petroleum products that the consumer uses daily. Crude oil is made up of many various and complex hydrogen/ carbon (hydrocarbon) atoms. As crude oil is boiled, various hydrocarbon molecules are driven off at different temperatures. Temperatures in this process range from 100°F to over 1000°F. Since fractions of these hydrocarbon molecules are driven off in varying quantities and temperatures, the first step in the refining of crude oil is to fractionate (boil) the crude in a fractionator. Figure 1 - Catalytic Cracker This process will only yield, if at all, a limited amount of a desired hydrocarbon molecule, such as gasoline, depending on the type of crude oil being processed. To obtain the greatest amount of gasoline from a batch of crude, the heavier hydrocarbon molecules derived in the fractionating process must be further processed by “cracking” the heavier hydrocarbon molecules with a chemical catalyst into the lighter hydrocarbon molecules desired thus the term “Catalytic Cracking Unit” or “Cat Cracker”. A catalytic cracking unit can run at internal temperatures of up to 1500°F. The catalyst used is composed of a fine granular powder which may be zeolite, aluminum hydrosilicate, bauxite and silica-alumina, etc. Figure 1 gives an overall view of a catalytic cracking unit. There are several ducts and vessels involved in the cracking of heavy hydrocarbon molecules which contain circulating hot catalyst and heated carbon monoxide gases. The actual process of cracking takes place in the Reactor where the catalysts breaks down the heavy carbon/hydrogen molecules The Work The job of the infrared thermographer is to examine every square inch of the Reactor, Regenerator, Spent Catalyst Standpipe, Reactor Spent Catalyst Riser, Regenerator Flue Gas Lines/Ducts, Regenerated Catalysts Standpipes, and Catalyst Feed Riser Pipes, and determine if there are any ‘hot spots’ on the surface, indicating a breakdown of the protective refractory lining on the inside of these ducts and vessels. One might consider the surveying to be a relatively easy and straight-forward task, i.e. survey the vessels and find the hot spots. But, the following examples in Figures 2, 3, 4 and 5 illustrate that it is not always quite as simple as that. Figure 2 - These images reveal a false positive hot spot on the side of the Reactor. But it is not a problem, as the heat pattern shows a symmetrical shape, giving a strong indication there is probably an internal structure connected to the inner wall of the Reactor, which was the reason for this anomaly. august/september 2008 30

Table of Contents Feed for the Digital Edition of Up Time Magazine- August/September 2008

Up Time Magazine- August/September 2008 Contents Upfront Upclose Information Technology Lubrication Infrared Maintenance Management Motor Testing Precision Maintenance Reliability Ultrasound Vibration Upgrade

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