Pyrolysis Furnace Tubes

Patent metadata

Field	Value
Publication number	US-2016168480-A1
Application number	US-201514942730-A
Country	US
Kind code	A1
Filing date	Nov 16, 2015
Priority date	Dec 16, 2014
Publication date	Jun 16, 2016
Grant date	—

Abstract

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.

First claim

1 . A weldment suitable for use in a pyrolysis furnace, the weldment comprising:
a) a first tubular member comprising a first steam cracker alloy and having inner and outer surfaces; and b) one or more mixing elements in surface contact with the inner surface of the first tubular member, at least one of the mixing elements comprising a second steam cracker alloy, wherein;
(i) the first steam cracker alloy comprises A 1 wt. % aluminum, based on the weight of the first steam cracker alloy,
(ii) the second steam cracker alloy comprises A 2 wt. % aluminum, based on the weight of the second steam cracker alloy, and
(iii) A 1 is ≧2.0 wt. % and A 2 is ≧2.0 wt. %.

2 . The weldment of claim 1 , wherein A 1 is in the range of from 2.0 wt. % to 10.0 wt. % and A 2 is in the range of from 2.0 wt. % to 10.0 wt. %.

3 . The weldment of claim 1 , wherein A 2 is ≧A 1 .

4 . The weldment of claim 1 , wherein A 2 minus A 1 is ≧0.5 wt. %.

5 . The weldment of claim 1 , wherein A 2 minus A 1 is ≧1.0 wt. %.

6 . The weldment of claim 1 , wherein A 1 is in the range of from 2.0 wt. % to 4.0 wt. %.

7 . The weldment of claim 1 , wherein A 2 is in the range of from 5.0 wt. % to 8.0 wt. %.

8 . The weldment of claim 1 , further comprising a second tubular member in surface contact with the outer surface of the first tubular member.

9 . The weldment of claim 1 , further comprising a carburization-resistant layer over at least a portion of the first tubular member's inner surface and/or at least a portion of at least one of the mixing elements comprising the second steam cracker alloy, wherein the carburization-resistant layer comprises alumina.

10 . The weldment of claim 9 , wherein the carburization-resistant layer is substantially free of chromium.

11 . The weldment of claim 1 , wherein the first steam cracker alloy further comprises 65.0 wt. % iron, ≧17.5 wt. % chromium, and ≧25.0 wt. % nickel.

12 . The weldment of claim 11 , wherein the first steam cracker alloy comprises ≧20.0 wt. % chromium and ≧30.0 wt. % nickel.

13 . The weldment of claim 1 , wherein the second steam cracker comprises 5.0 wt. % to 10.0 wt. % aluminum, and further comprises 18.0 wt. % to 25.0 wt. % chromium, ≦0.5 wt. % silicon, and ≧35.0 wt. % iron; wherein ≧90.0 wt. % of the balance of the second steam cracker alloy is nickel.

14 . The weldment of claim 13 , wherein the second steam cracker alloy comprises 5.0 wt. % to 8.0 wt. % aluminum and 19.0 wt. % to 24.0 wt. % chromium, wherein ≧95.0 wt. % of the balance of the second steam cracker alloy is nickel.

15 . The weldment of claim 1 , wherein the second steam cracker alloy further comprises ≦0.01 wt. % carbon.

16 . The weldment of claim 1 , wherein the second steam cracker alloy further comprises at least one of (i) 0.1 wt. % to 2.0 wt. % of at least one of gallium, germanium, arsenic, indium, tin, antimony, lead, palladium, platinum, copper, silver and gold; (ii) 0.1 wt. % to 2.0 wt. % of at least one of rhenium, ruthenium, rhodium, and iridium; (iii) 0.01 to 2.0 wt. % of at least one of scandium, lanthanum, yttrium, and cerium; and (iv) 0.01 to 4.0 wt. % of at least one of manganese, titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, and tungsten.

17 . The weldment of claim 16 , wherein 0.01 to 2.0 wt. % of the second steam cracker alloy is in the form of one or more particulate oxides.

18 . The weldment of claim 1 , wherein (i) at least a portion of the second steam cracker alloy's aluminum is in the form of Ni 3 Al intermetallic precipitate and/or NiAl intermetallic precipitate and (ii) the total Ni 3 Al intermetallic precipitate and NiAl intermetallic precipitate are present in a total amount (Ni 3 Al intermetallic precipitate+NiAl intermetallic precipitate) in the range of 0.1 wt. % to 30.0 wt. %, based on the weight of the second steam cracker alloy.

19 . The weldment of claim 1 , wherein 0.01 wt. % to 5.0 wt. % of the second steam cracker alloy is in the form of oxide inclusions, carbide inclusions, nitride inclusions, carbonitride inclusions, and combinations thereof.

20 . The weldment of claim 1 , wherein among the mixing elements which comprise the second steam cracker alloy is at least one that is (i) in the form of a protrusion from the inner surface of the first tubular member and (ii) configured to agitate a flow of hydrocarbon passing through the tubular member to distribute the hydrocarbon flow across a transverse internal cross section of the first tubular member to create a generally uniform temperature profile across the transverse internal cross section.

21 . The weldment of claim 1 , wherein (i) among the mixing elements which comprise the second steam cracker alloy is at least one that is in the form of a fin, (ii) the fin projects in a direction substantially intersecting a longitudinal axis of the first tubular member, and (iii) the fin is configured to deflect of a flow of hydrocarbon passing through the tubular member to distribute the hydrocarbon flow across a transverse internal cross section of the first tubular member to create a generally uniform temperature profile across the transverse internal cross section.

22 . The weldment of claim 1 , wherein among the mixing elements which comprise the second steam cracker alloy is at least one that is in the form of a discontinuous and/or helical weld bead.

23 . A heat transfer tube for use in a pyrolysis furnace, the heat transfer tube comprising: a weldment according to claim 1 .

24 . A pyrolysis furnace comprising at least one heat transfer tube, the heat transfer tube comprising a weldment according to claim 1 .

25 . A pyrolysis process, comprising:
(a) providing a pyrolysis furnace, the pyrolysis furnace comprising at least one radiant tube, wherein the radiant tube includes (i) a tubular member comprising a first steam cracker alloy which includes aluminum, the first tubular member having inner and outer surfaces, and (ii) one or more mixing elements in surface contact with the inner surface of the tubular member, at least one of the mixing elements comprising a second steam cracker alloy which includes aluminum; (b) providing hydrocarbon and steam; (c) combining at least a portion of the hydrocarbon with at least a portion of the steam to produce a hydrocarbon+steam mixture, and intruding the hydrocarbon+steam mixture into the radiant tube; (d) exposing the hydrocarbon+steam mixture in the radiant tube to pyrolysis conditions to thermally crack at least a portion of the hydrocarbon; the tubular member's aluminum content being sufficient for forming an alumina-containing carburization-resistant scale on the tubular member's inner surface under the pyrolysis conditions, and the second tubular member's aluminum content being sufficient for forming an alumina-containing carburization-resistant scale on the mixing element under the pyrolysis conditions.

Assignees

• Exxonmobil Chem Patents Inc

Inventors

• Spicer David B
• Chun Changmin

Classifications

• C22C38/44

  with molybdenum or tungsten · CPC title

• C10G9/36

  with heated gases or vapours · CPC title

• C10G9/203 Primary

  chemical composition of the tubes · CPC title

• C10G9/14

  in pipes or coils with or without auxiliary means, e.g. digesters, soaking drums, expansion means · CPC title

• C23C28/345

  with at least one oxide layer · CPC title