A method for cracking hydrocarbon, comprises: providing steam and hydrocarbon; and feeding steam and hydrocarbon into a reactor accessible to hydrocarbon and comprising a perovskite material of formula A.sub.aB.sub.bC.sub.cD.sub.dO.sub.3-, wherein 0<a<1.2, 0b1.2, 0.9<a+b1.2, 0<c<1.2, 0d1.2, 0.9<c+d1.2, 0.5<<0.5; A is selected from calcium, strontium, barium, and any combination thereof; B is selected from lithium, sodium, potassium, rubidium and any combination thereof; C is selected from cerium, zirconium, antimony, praseodymium, titanium, chromium, manganese, ferrum, cobalt, nickel, gallium, tin, terbium and any combination thereof; and D is selected from lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, titanium, vanadium, chromium, manganese, ferrum, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, gallium, indium, tin, antimony and any combination thereof.

Some embodiments of the present invention provide components for a serpentine fluid reactor which is optimized for one or more objective functions of interest such as pressure drop, erosion rate, fouling, coke deposition and operating costs. The components are designed by computer modeling the components individually and collectively in which the cross section of flow path is substantially circular under industrial conditions to validate the model design and its operation. Then iteratively the component designs are deformed and the operation of the deformed part(s) is modeled and compared to values obtained with other deformed models until the value of the objective function is optimized (e.g. at an extreme) or the change in the objective function is approaching zero.

In an embodiment of the invention, furnace tubes for cracking hydrocarbons having a longitudinal array of pins having i) a maximum height from 0.5-1.3 cm; ii) a contact surface with the tube, having an area from 0.1%-10% of the tube external surface area iii) a uniform cross section along the length of the pin. (i.e. they are not tapered); and iv) a length to diameter ratio from 1.5:1 to 0.5:1 have an improved heat transfer over bare fins and reduced stress relative to a fined tube.

A composition useful in methods and apparatuses for inhibiting the build-up of byproduct carbonaceous material includes a perovskite material or a precursor therefor; and a yttrium doped ceria or a precursor therefor.

Processes for steam cracking hydrocarbons. The process can include introducing a hydrocarbon that can include ethane, propane, or a mixture thereof into radiant coils under steam cracking conditions that produce a steam cracker effluent and deposit coke on an inner surface thereof. An ethane conversion can be 75% or a. propane conversion can be 93%. Introduction of the hydrocarbon into at least one of the radiant coils can be periodically stopped. A decoking feed can be introduced into the at least one of the radiant coils under decoking process conditions that can include: (i) a decoking effluent that can have a coil outlet temperature of >900 C. (ii) introducing the decoking feed at a. mass flux rate at the quench exchanger inlet of >39 kg m.sup.2 second.sup.1, and/or (iii) introducing the decoking feed while maintaining introduction of the first hydrocarbon feed into one or more of the radiant coils in the plurality of radiant coils.