Centrispun tube technology entered the North and South American markets on Mar. 1 with the inauguration of the Schmidt & Clemens Brasil Ltda.'s production facility in Jundiai, Brazil. Schmidt & Clemens Brasil Ltda. is a subsidiary of the Schmidt & Clemens Group headquartered in Lindlar, Germany.
The plant uses three new technologies: S+COPE, SuperBent, and Centralloy 60 HT. Production capabilities include casting and assembly of ethylene coils, reformer harps, radiant coils, furnace rolls, glendons, and offshore bushes. Over 80% of output is sent to ethylene crackers, ammonia plants, refinery hydrogen reformers, and fertilizer furnaces.
S+COPE
S&C's centrispun steam cracker tube profile, patented under the name Schmidt + Clemens Optimized Profile for Ethylene (S+COPE), offers homogenous heat distribution for increased selectivity, fluid rotation, and coke reduction.
The internal profile of the nickel-based (>50% Ni) alloy metallurgy is rifled to improve heat transfer, flow pattern, and reduce weight and tube metal temperature. The profile is intended to accelerate feed gas cracking temperature and reduce pressure drop. According to S&C, the technology should result in predictable operations with higher olefin yield and less fouling for most applications.
SuperBent
S&C's SuperBent technology entails producing centrifugal cast tubes that are induction bent to very tight radii, for steam cracker plants. Superbent is intended to replace conventional static cast fittings such as elbows or return bends. The bend radius factor is reduced from 5-10 times tube diameter to as small as 1.2 times tube diameter to cut down hanger systems, furnace structure, the number of cast parts that must be welded together and x-rayed, and the creep rate of straight tube legs. The similar material chemistry, microstructure, and wall thickness simplify welding. Reduced bend radii are expected to minimize erosion found in most conventional fittings. The uniform tube wall thickness is designed to reduce system stress in the coils to avoid thermal fatigue rupture.
Centralloy 60 HT
S&C's Centralloy 60 HT technology includes a protective oxide basis— alumina in addition to chromia. In contrast to the conventional chromia protection, which becomes unstable at temperatures above 1,050° C./1,950° F., Centralloy 60 HT is stable up to 1,200° C./2,200° F. Stable aluminum oxide scale facilitates reduction in catalytic coking and extends the cycle time between decokes.
Field tests demonstrated performance of the new alloy compared with conventional 45/35 alloys. Three commercial contracts for retubing entire furnaces with Centralloy 60 HT have been signed in Europe and South America.
