Abstract: In chemical processes for cracking hydrocarbons, reactors are subject to coking. This results in carburization of the metal substrate for the reactor leading to a reduced reactor life. If the reactor is subject to a decoke process, followed by a steam scour and nitrogenating there is a reduced tendency to carburization of the metal substrate improving the reactor life.

Abstract: A substrate steel of the comprising from 0.01 to 0.60 wt. % of La, from 0.0 to 0.65 wt. % of Ce; from 0.06 to 1.8 wt. % of Nb up to 2.5 wt. % of one or more trace elements and carbon and silicon may be treated in an oxidizing atmosphere to product a coke resistant surface coating of MnCr2O4 having a thickness up to 5 microns.

Abstract: An anti-coking surface having a thickness up to 15 microns comprising from 15 to 50 wt. % of MnCr2O4 (for example manganochromite); from 15 to 25 wt. % of Cr0.23Mn0.08Ni0.69 (for example chromium manganese nickel); from 10 to 30 wt. % of Cr1.3Fe0.7O3 (for example chromium iron oxide); from 12 to 20 wt. % of Cr2O3 (for example eskolaite); from 4 to 20 wt. % of CuFe5O8 (for example copper iron oxide); and less than 5 wt. % of one or more compounds chosen from FeO(OH), CrO(OH), CrMn, Si and SiO2 (either as silicon oxide or quartz) and less than 0.5 wt. % of aluminum in any form provided that the sum of the components is 100 wt. % is provided on steel.

Abstract: In chemical processes for cracking hydrocarbons, reactors are subject to coking. This results in carburization of the metal substrate for the reactor leading to a reduced reactor life. If the reactor is subject to a decoke process, followed by a steam scour and nitrogenating there is a reduced tendency to carburization of the metal substrate improving the reactor life.

Abstract: An anti-coking surface having a thickness up to 15 microns comprising from 15 to 50 wt. % of MnCr2O4 (for example manganochromite); from 15 to 25 wt. % of Cr0.23Mn0.08Ni0.69 (for example chromium manganese nickel); from 10 to 30 wt. % of Cr1.3Fe0.7O3 (for example chromium iron oxide); from 12 to 20 wt. % of Cr2O3 (for example eskolaite); from 4 to 20 wt. % of CuFe5O8 (for example copper iron oxide); and less than 5 wt. % of one or more compounds chosen from FeO(OH), CrO(OH), CrMn, Si and SiO2 (either as silicon oxide or quartz) and less than 0.5 wt. % of aluminum in any form provided that the sum of the components is 100 wt. % is provided on steel.

Abstract: A substrate steel of the comprising from 0.01 to 0.60 wt. % of La, from 0.0 to 0.65 wt. % of Ce; from 0.06 to 1.8 wt. % of Nb up to 2.5 wt. % of one or more trace elements and carbon and silicon may be treated in an oxidizing atmosphere to product a coke resistant surface coating of MnCr2O4 having a thickness up to 5 microns.

Abstract: A substrate steel of the comprising from 0.01 to 0.60 wt. % of La, from 0.0 to 0.65 wt. % of Ce; from 0.06 to 1.8 wt. % of Nb up to 2.5 wt. % of one or more trace elements and carbon and silicon may be treated in an oxidizing atmosphere to product a coke resistant surface coating of MnCr2O4 having a thickness up to 5 microns.

Abstract: In chemical processes for cracking hydrocarbons, reactors are subject to coking. This results in carburization of the metal substrate for the reactor leading to a reduced reactor life. If the reactor is subject to a decoke process, followed by a steam scour and nitriding there is a reduced tendency to carburization of the metal substrate improving the reactor life.

Abstract: Crackers for hydrocarbon such as naphtha and C2-C4 paraffins contain a radiant section and a convection section. The exhaust gases leaving the radiant section pass through the convection. Generally fouling from the convection section was low relative to fouling (e.g., coke build up) in the radiant section. With improved metallurgy and operating conditions, the time between decokes of the radiant section has increased and now there is a need to reduce fouling from the convection section. This may be achieved by using stainless steel, and particularly high nickel, high chrome stainless steel in the passes in the convection section.

Abstract: A substrate steel of the comprising from 0.01 to 0.60 wt. % of La, from 0.0 to 0.65 wt. % of Ce; from 0.06 to 1.8 wt. % of Nb up to 2.5 wt. % of one or more trace elements and carbon and silicon may be treated in an oxidizing atmosphere to product a coke resistant surface coating of MnCr2O4 having a thickness up to 5 microns.

Abstract: In chemical processes for cracking hydrocarbons, reactors are subject to coking. This results in carburization of the metal substrate for the reactor leading to a reduced reactor life. If the reactor is subject to a decoke process, followed by a steam scour and nitriding there is a reduced tendency to carburization of the metal substrate improving the reactor life.

Abstract: An anti-coking surface having a thickness up to 15 microns comprising from 15 to 50 wt. % of MnCr2O4; from 15 to 25 wt. % of Cr0.23Mn0.08Ni0.69, from 10 to 30 wt. % of Cr1.3Fe0.7O3, from 12 to 20 wt. % of Cr2O3, from 4 to 20 wt. % of CuFe5O8, and less than 5 wt. % of one or more compounds chosen from FeO(OH), Cr+3O(OH), CrMn, Si and SO2 (either as silicon oxide or quartz) and less than 0.5 wt. % of aluminum in any form provided that the sum of the components is 100 wt. % is provided on steel.

Abstract: High temperature industrial radiant heaters may be improved by coating a refractory or lining in and adjacent to the flame impingement zone which refractory or lining does not transmit fuel to the burner with a metal oxide catalyst or metal oxide catalyst precursor other than iron, iron oxides or mixtures thereof, to promote the burning of one or more of the fuel, and combustion products thereof.

Abstract: A stainless steel comprising at least 20 weight % of chromium and at least 1.0 weight % of manganese is adapted to support an overcoating having a thickness from 1 to 10 microns of a spinel of the formula MnxCr3-xO4 wherein x is from 0.5 to 2. Preferably the overcoating is on chromia and has stability against chemical reaction at temperatures at least 25° C. higher than the uncoated chromia.

Abstract: In a radiant heating box there is a convection current which flows over the surface of tubes in the box. Adding ribs to the external surface of vertical tubes provides an enhancement to the heat transfer by convection and increases the heat transfer to the tubes.

Abstract: A stainless steel comprising at least 20 weight % of chromium and at least 1.0 weight % of manganese is adapted to support an overcoating having a thickness from 1 to 10 microns of a spinel of the formula MnxCr3-xO4 wherein x is from 0.5 to 2. Preferably the overcoating is on chromia and has stability against chemical reaction at temperatures at least 25° C. higher than the uncoated chromia.

Abstract: An outermost surface covering not less than 55% of stainless steel, said surface having a thickness from 0.1 to 15 microns and being a spinel of the formula MnxCr3-xO4 wherein x is from 0.5 to 2 is not prone to coking and is suitable for hydrocarbyl reactions such as furnace tubes for cracking.