Furnace tube coatings reduce carbon formation and increase efficiency in olefins plants
By Gerald Parkinson |
Coating technology that essentially eliminates carbon buildup on the interior of steam cracker tubes will be commercialized by Quantiam Technologies Inc. (Edmonton, Alta; www.quantiam.com). Commercial-scale tests in five ethylene crackers indicate that the coating can extend the time between furnace decokings to 1–2 yr for light feedstocks, whereas uncoated tubes have to be decoked about every 30 days, says Steve Petrone, chief executive officer.
Petrone notes that there are two main sources of carbon buildup in furnace tubes: filamentous coke, whose formation is catalyzed at high temperatures from the nickel and iron in the steel tubes; and amorphous coke that deposits from cracking the gaseous hydrocarbon feed. Quantiam’s coating prevents the former by shutting down the coke-forming mechanism. The accumulation of gas-phase coke deposits is prevented by a catalyst in the coating that converts the coke to CO and CO2. Petrone declines to give details on the coating or catalyst, except to say the coating is a composite consisting of a metal matrix with ceramic and intermetallic components.
Petrone says the coating is stable at temperatures up to 1,130°C and has tolerated sulfur levels up to 3,000 ppm. By avoiding carbon…