Aluminum oxide forming heat transfer tube for thermal cracking

Patent metadata

Field	Value
Publication number	US-10456768-B2
Application number	US-201815999414-A
Country	US
Kind code	B2
Filing date	Aug 20, 2018
Priority date	Sep 12, 2017
Publication date	Oct 29, 2019
Grant date	Oct 29, 2019

Abstract

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.

First claim

The invention claimed is:

1. A heat transfer tube comprising,
a carburization-resistant alloy comprising a) 25 to 55 wt. % nickel; b) 18 to 24 wt. % chromium; c) 4 to 7 wt. % aluminum; d) iron; and e) at least one strengthening mechanism component, the weight percents being based on the total weight of the alloy, wherein the strengthening mechanism includes one or more of:
(i) carbides strengthening mechanisms comprising 1.0 to 2.0 wt. % of at least one element selected from titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, and 0.4 to 0.6 wt. % carbon;
(ii) gamma prime (γ′) strengthening mechanisms comprising Ni 3 Al and less than 0.15 wt. % carbon;
(iii) solid solution strengthening mechanisms comprising 2.0 to 4.0 wt. % of at least one element selected from vanadium, niobium, tantalum, molybdenum, tungsten, and less than 0.4 wt. % carbon; and
(iv) oxide dispersoid strengthening mechanisms comprising 0.1 to 1.0 wt. % of at least one element selected from yttrium, lanthanum, cerium, scandium, praseodymium, neodymium and less than 0.4 wt. % carbon.

2. The heat transfer tube of claim 1 , where the heat transfer alloy comprises one or more of strengthening mechanisms (ii); (iii); or (iv) and less than 0.15 wt. % carbon.

3. The heat transfer tube of claim 1 , where the heat transfer alloy comprises one or more of the following: 4.5 to 6.5 wt. % aluminum, 30.0 to 50.0 wt. % nickel, and 20.0 to 21.9 wt. % chromium.

4. The heat transfer tube of claim 1 , where the carburization-resistant alloy further comprises less than 0.5 wt. % silicon.

5. The heat transfer tube of claim 1 , further comprising a substantially-continuous oxide layer covering at least 75% the tube's inner surface area, wherein the oxide layer comprises oxide of at least a portion of the aluminum.

6. The heat transfer tube of claim 5 , where the oxide layer is substantially free of chromium.

7. A centrifugally cast pyrolysis tube, comprising a) 25 to 55 wt. % nickel; b) 18 to 24 wt. % chromium; c) 4 to 7 wt. % aluminum; d) iron; and e) at least one strengthening mechanism selected from:
(i) carbides strengthening mechanisms comprising 1.0 to 2.0 wt. % of at least one element selected from titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, and 0.4 to 0.6 wt. % carbon;
(ii) gamma prime (γ′) strengthening mechanisms comprising Ni 3 Al and less than 0.15 wt. % carbon;
(iii) solid solution strengthening mechanisms comprising 2.0 to 4.0 wt. % of at least one element selected from vanadium, niobium, tantalum, molybdenum, tungsten, and less than 0.4 wt. % carbon; and
(iv) oxide dispersoid strengthening mechanisms comprising 0.1 to 1.0 wt. % of at least one element selected from yttrium, lanthanum, cerium, scandium, praseodymium, neodymium and less than 0.4 wt. % carbon.

8. A method for producing a heat transfer tube comprising, providing a carburization-resistant alloy and centrifugally casting the carburization-resistant alloy to produce a heat transfer tube, where the carburization-resistant alloy comprises a) 25 to 55 wt. % nickel; b) 18 to 24 wt. % chromium; c) 4 to 7 wt. % aluminum; d) iron; and e) at least one strengthening mechanism component selected from:
(i) carbides strengthening mechanisms comprising 1.0 to 2.0 wt. % of at least one element selected from titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, and 0.4 to 0.6 wt. % carbon;
(ii) gamma prime (γ′) strengthening mechanisms comprising Ni 3 Al and less than 0.15 wt. % carbon;
(iii) solid solution strengthening mechanisms comprising 2.0 to 4.0 wt. % of at least one element selected from vanadium, niobium, tantalum, molybdenum, tungsten, and less than 0.4 wt. % carbon; and
(iv) oxide dispersoid strengthening mechanisms comprising 0.1 to 1.0 wt. % of at least one element selected from yttrium, lanthanum, cerium, scandium, praseodymium, neodymium and less than 0.4 wt. % carbon.

9. A method for producing olefins comprising, pyrolysing a hydrocarbon feed in a heat transfer tube comprising a carburization-resistant alloy, where the carburization-resistant alloy comprises a) 25.1 to 55.0 wt. % nickel; b) 18.1 to 23.9 wt. % chromium; c) 4.1 to 7.0 wt. % aluminum; d) iron; and f) at least one strengthening mechanism comprising:
(i) carbides strengthening mechanisms comprising 1.0 to 2.0 wt. % of at least one element selected from titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, and 0.4 to 0.6 wt. % carbon;
(ii) gamma prime (γ′) strengthening mechanisms comprising Ni 3 Al and less than 0.15 wt. % carbon;
(iii) solid solution strengthening mechanisms comprising 2.0 to 4.0 wt. % of at least one element selected from vanadium, niobium, tantalum, molybdenum, tungsten, and less than 0.4 wt. % carbon; and
(iv) oxide dispersoid strengthening mechanisms comprising 0.1 to 1.0 wt. % of at least one element selected from yttrium, lanthanum, cerium, scandium, praseodymium, neodymium and less than 0.4 wt. % carbon.

10. The method of claim 9 , further comprising forming an oxide layer at the heat transfer tube's inner surface, wherein the oxide layer includes oxide of at least a portion of the aluminum.

11. The method of claim 10 , wherein the oxide layer is substantially free of chromium.

12. The method of claim 10 , wherein the oxide layer is substantially-continuous and covers at least 75% the tube's inner surface area.

13. A steam cracker furnace, the furnace comprising:
(a) a convection section which includes at least one convection tube adapted for indirectly heating a mixture comprising hydrocarbon and steam,
(b) a radiant section which includes at least one radiant tube adapted to (i) receive the heated mixture, (ii) expose the heated mixture in the radiant tube to steam cracking conditions in order to produce cracked products, and (iii) convey away from the radiant section an effluent comprising at least a portion of the cracked products; wherein,
(A) the radiant and/or convection tube comprise a protective layer covering ≥70% of the tube's internal surface area, and
(B) the layer is formed from a carburization-resistant alloy, where the carburization-resistant alloy comprises a) 25.1 to 55.0 wt. % nickel; b) 18.1 to 23.9 wt. % chromium; c) 4.1 to 7.0 wt. % aluminum; d) iron; and f) at least one strengthening mechanism comprising:
(I) carbides strengthening mechanisms comprising 1.0 to 2.0 wt. % of at least one element selected from titanium, zirconium, hafnium, vanadium, niobium, tantalum, molybdenum, tungsten, and 0.4 to 0.6 wt. % carbon; or at least one of:
(II) gamma prime (γ′) strengthening mechanisms comprising Ni 3 Al and less than 0.15 wt. % carbon;
(III) solid solution strengthening mechanisms comprising 2.0 to 4.0 wt. % of at least one element selected from vanadium, niobium, tantalum, molybdenum, tungsten, and less than 0.4 wt. % carbon; and
(IV) oxide dispersoid strengthening mechanisms comprising 0.1 to 1.0 wt. % of at least one element selected from yttrium, lanthanum, cerium, scandium, praseodymium, neodymium and less than 0.4 wt. % carbon.

14. The steam cracker furnace of claim 13 , wherein the protective layer is a substantially-continuous carburization-resistant layer covering ≥90% of the tube's internal surface area.

15. The steam cracker furnace of claim 13 , further comprising a second layer located adjacent to and outward of the carburization-resistant layer, the second layer comprising at least one ferrous alloy.

16. A method for forming a carburization-resistant layer at the inner-surface of a heat transfer tube, the method comp

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Chun Changmin
• Perdomo Jorge J

Classifications

• F16L58/08

  by metal · CPC title

• F16L9/02

  of metal (F16L9/16 - F16L9/22 take precedence) · CPC title

• C22C38/54

  with boron · CPC title

• C22C38/46

  with vanadium · CPC title

• C22C38/38

  with more than 1.5% by weight of manganese · CPC title