The invention relates weldments useful as heat transfer tubes in pyrolysis furnaces. The invention relates to tubes that are useful in pyrolysis furnaces. The weldments include a tubular member and at least one mixing element. The tubular member comprises an aluminum-containing alloy. The mixing element comprises an aluminum-containing alloy. The mixing element's aluminum-containing alloy can be the same as or different from the tubular member's aluminum-containing alloy. Other aspects of the invention relate to pyrolysis furnaces which include such weldments, and the use of such pyrolysis furnaces for hydrocarbon conversion processes such as steam cracking.

Systems and methods are provided for performing ethane steam cracking at elevated coil inlet pressures and/or elevated coil outlet pressures in small diameter furnace coils. Instead of performing steam cracking of ethane at a coil outlet pressure of ?22 psig or less (?150 kPa-g or less), the steam cracking of ethane can be performed in small diameter furnace coils at a coil outlet pressure of 30 psig to 75 psig (?200 kPa-g to ?520 kPa-g), or 40 psig to 75 psig (?270 kPa-g to ?520 kPa-g). In order to achieve such higher coil outlet pressures, a correspondingly higher coil inlet pressure can also be used, such as a pressure of 45 psig (?310 kPa-g) or more, or 50 psig (?340 kPa-g) or more.

An apparatus has a surface exposable to a byproduct carbonaceous material formation environment and comprising a perovskite material having an ABO.sub.3 perovskite structure and being of formula A.sub.aB.sub.bO.sub.3-, wherein 0.9<a1.2; 0.9<b1.2; 0.5<<0.5; A is a combination of a first element and a second element, the first element is selected from yttrium, bismuth, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and any combination thereof, the second element is selected from calcium, strontium, barium, lithium, sodium, potassium, rubidium and any combination thereof; and B is selected from silver, gold, cadmium, cerium, cobalt, chromium, copper, dysprosium, erbium, europium, ferrum, gallium, gadolinium, hafnium, holmium, indium, iridium, lanthanum, lutetium, manganese, molybdenum, niobium, neodymium, nickel, osmium, palladium, promethium, praseodymium, platinum, rhenium, rhodium, ruthenium, antimony, scandium, samarium, tin, tantalum, terbium, technetium, titanium, thulium, vanadium, tungsten, yttrium, ytterbium, zinc, zirconium, and any combination thereof. An associated method is also described.

A system for producing chemicals, such as, ethylene or gasoline, at high temperature (above 1100 degrees C.) having a feedstock source. The system includes a chemical conversion portion connected with the feedstock source to receive feedstock and convert the feedstock to ethylene or gasoline. The conversion portion includes a coil array and a furnace that heats the feedstock to temperatures in excess of 1100 C. or 1200 C. or even 1250 C. or even 1300 C. or even 1400 C. A method for producing chemicals, such as ethylene or gasoline, at high temperature.

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 MnCr.sub.2O.sub.4 having a thickness up to 5 microns.

This application relates to a heat transfer tube, its method of manufacture and its use for thermal cracking hydrocarbon feeds, such as thermal cracking in furnaces. The heat transfer tube comprises a chromium and aluminum carburization-resistant alloy capable of generating a typically continuous aluminum oxide scale under thermal cracking conditions that reduces coking and thereby enhances heat transfer. The carburization-resistant alloy comprises 25.1 to 55.0 wt. % nickel; 18.1 to 23.9 wt. % chromium; 4.1 to 7.0 wt. % aluminum; and iron. Additionally, the carburization-resistant alloy has at least one strengthening mechanism to provide desirable mechanical properties. The carburization-resistant alloy composition is also resistant to the formation of cracks during centrifugal casting.

This disclosure relates to weldments useful as heat transfer tubes in refinery processes dealing with gas phase hydrocarbon process streams at high temperatures. This disclosure also relates to tubes that are useful in refinery processes dealing with gas phase hydrocarbon process streams at high temperatures. The weldments include a tubular member and at least one mixing element. The tubular member comprises an aluminum-containing alloy. The mixing element comprises an aluminum-containing alloy. The mixing element's aluminum-containing alloy can be the same as or different from the tubular member's aluminum-containing alloy. Other aspects of the disclosure relate to refinery processes dealing with gas phase hydrocarbon process streams at high temperatures which include such weldments.

Furnace tubes for cracking hydrocarbons that in an embodiment have a longitudinal array of pins having i) a maximum height from about 2 to about 4.8 cm; ii) a contact surface with the tube, having an area from about 0.1% to about 10% of the tube external cross section area iii) a uniform cross section along the length of the pin. (i.e., they are typically not tapered); and iv) a length to diameter ratio from about 4:1 to about 2:1 have an improved heat transfer over bare fins and reduced stress relative to a fined tube.

An anti-coking surface having a thickness up to 15 microns comprising from 15 to 50 wt. % of MnCr.sub.2O.sub.4 (for example manganochromite); from 15 to 25 wt. % of Cr.sub.0.23Mn.sub.0.08Ni.sub.0.69 (for example chromium manganese nickel); from 10 to 30 wt. % of Cr.sub.1.3Fe.sub.0.7O.sub.3 (for example chromium iron oxide); from 12 to 20 wt. % of Cr.sub.2O.sub.3 (for example eskolaite); from 4 to 20 wt. % of CuFe.sub.5O.sub.8 (for example copper iron oxide); and less than 5 wt. % of one or more compounds chosen from FeO(OH), CrO(OH), CrMn, Si and SiO.sub.2 (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.

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.