Reactor system steel portion

• US 5,648,178 A
• Filed: 12/28/1994
• Issued: 07/15/1997
• Est. Priority Date: 01/04/1994
• Status: Expired due to Fees

• Current Assignee: Chevron Chemical Company (Chevron Corp.)
• Original Assignee: Chevron Chemical Company (Chevron Corp.)
• Inventors: Heyse, John V., Kunze, Alan G.
• Primary Examiner(s): ZIMMERMAN, JOHN J
• Application Number:
  US08/365,855
• Time in Patent Office: 930 Days
• Field of Search: 428/610, 428/627, 428/667, 428/629, 428/614, 428/664, 428/665, 428/663, 422/240, 422/241
• US Class Current: 428/627
• CPC Class Codes: B01J 19/002 Avoiding undesirable reactions or side-effects, e.g. avoiding explosions, or improving the yield by suppressing side-reactions
• CPC Class Codes: B01J 19/02 Apparatus characterised by being constructed of material selected for its chemically-resistant properties
• CPC Class Codes: B01J 2219/00186 controlling the composition of the reactive mixture
• CPC Class Codes: B01J 2219/00247 Fouling of the reactor or the process equipment
• CPC Class Codes: B01J 2219/0236 Metal based
• CPC Class Codes: C01B 2203/0233 the reforming step being a steam reforming step
• CPC Class Codes: C01B 2203/048 the impurity being an organic compound
• CPC Class Codes: C01B 2203/0816 Heating by flames
• CPC Class Codes: C01B 2203/1241 Natural gas or methane
• CPC Class Codes: C01B 2203/1247 Higher hydrocarbons
• CPC Class Codes: C07C 11/04 Ethylene
• CPC Class Codes: C07C 15/46 Styrene; Ring-alkylated styrenes
• CPC Class Codes: C07C 4/04 Thermal processes C07C4/025 takes precedence
• CPC Class Codes: C07C 5/327 Formation of non-aromatic carbon-to-carbon double bonds only
• CPC Class Codes: C10G 9/16 Preventing or removing incrustation
• CPC Class Codes: C10G 9/203 chemical composition of the tubes
• CPC Class Codes: C23C 26/00 Coating not provided for in groups C23C2/00 - C23C24/00
• CPC Class Codes: C23C 28/322 only coatings of metal elements only
• CPC Class Codes: C23C 28/34 including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
• CPC Class Codes: C23C 28/341 with at least one carbide layer
• CPC Class Codes: C23C 28/345 : with at least one oxide layer
• CPC Class Codes: C23C 8/02 : Pretreatment of the material to be coated C23C8/04 takes precedence
• CPC Class Codes: F28F 19/06 : of metal
• CPC Class Codes: Y10T 428/12576 : Boride, carbide or nitride component
• CPC Class Codes: Y10T 428/12833 : Alternative to or next to each other
• CPC Class Codes: Y10T 428/12854 : Next to Co-, Fe-, or Ni-base component

Abstract

Methods for cracking hydrocarbons in reactor systems having improved resistances to carburization and coking. The reactor system comprises a steel portion having provided thereon a Group VIB metal protective layer to isolate the steel portion from hydrocarbons, applied to a thickness effective for isolating the steel portion from the hydrocarbon environment. The protective layer is anchored to the steel substrate through an intermediate carbide-rich, bonding layer.

Claims

1. A steel portion of a reactor system in contact with steam and hydrocarbons, said steel portion having a Group VIB metal protective layer and at least one intermediate, carbide-rich, bonding layer, wherein said protective layer is substantially free of unfilled cracks or Group VIB oxides extending to said bonding layer, wherein the protective layer is formed by bonding a Group VIB metal layer to steel in the presence of a nitrogen-containing compound at a temperature effective to form the carbide-rich bonding layer and to fill cracks in the Group VIB metal layer with Group VIB metal nitride which effectively seals off and isolates the Group VIB carbide-rich bonding layer from later H₂ O/steam attack.

2. A steel portion according to claim 1, wherein the nitrogen-containing compound is nitrogen gas.

3. A steel portion according to claim 1, wherein the temperature effective to form the bonding layer and to fill cracks is in the range of from about 1200°

to 2000°

F.

4. A steel portion according to claim 1, wherein the temperature effective to form the bonding layer and to fill cracks is at least 1500°

C.

5. A steel portion according to claim 1, wherein the thickness of the carbide-rich bonding layer is in the range from about 1-2 microns and the thickness of the Group VIB metallic layer is in the range from about 50 to 100 microns.

6. A steel portion according to claim 1, wherein the Group VIB metal is chromium.