Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
  • C10G9/14—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils in pipes or coils with or without auxiliary means, e.g. digesters, soaking drums, expansion means
  • C10G9/18—Apparatus
  • C10G9/20—Tube furnaces
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium

Definitions

• the present disclosure relates to a radiant tube formed of a material that meets requirements such as creep strength, ductility and service life in cracking furnaces, preferably furnaces for ethylene cracking.
• hydrocarbons are cracked into ethylene, H 2 C ⁇ H 2 C, which constitutes a raw material for the plastics industry.
• the cracking takes place by hydrocarbons being led through a radiant tube, which has been heated by means of surrounding burner to sufficiently high temperature, for instance, about 1,100° C., for ethylene being formed in the tube.
• the tube usually is made from a FeCrAl material.
• a dense aluminum oxide Al 2 O 3 is formed on the outside and inside of the tube. This oxide prevents Fe contacting the gas flowing in the tube when Fe acts as a catalyst for coke formation in the tube. If coke is formed in the tube, the same is deposited on the inside of the tube, the flow of gas in the tube becoming smaller and the heat transfer to the interior of the tube becoming lower. Coke may also entirely clog the tube.
• Swedish Patent No. 513 989 a method for the manufacture of a FeCrAl material by gas atomization is disclosed.
• a problem in gas atomization is that in the manufacture of a FeCrAl material containing titanium, small particles of TiN and TiC are formed in the charge before the atomization, which particles are caught on the melt nozzle that is used for the atomization and that the same is clogged.
• Swedish Patent No. 513 989 proposes that the charge that is to be atomized being brought to contain 0.05 to 0.50% by weight of tantalum and simultaneously less than 0.10% by weight of titanium.
• the material may contain molybdenum (Mo).
• the present disclosure relates to a radiant tube in a cracking furnace, where hydrocarbons are cracked into ethylene in a tube through which hydrocarbons flow, which tube is heated from the outside to a temperature where cracking of hydrocarbons occurs, and is characterized in that the tube is made from a FeCrAl material containing, in addition to Fe, 10 to 25% by weight of Cr, 1 to 10% by weight of Al and 1.5 to 5% by weight of Mo.
• the material comprises up to a total of 2.2 wt. %, preferably up to 2.0 wt. % and more preferably up to 1.0 wt. %, of one or more alloying materials selected from the group consisting of tantalum, hafnium, zirconium, yttrium, nitrogen, carbon and oxygen.
• a radiant tube is found in a cracking furnace, where hydrocarbons are cracked into ethylene in a tube through which hydrocarbons flow.
• the tube is heated from the outside to a temperature where cracking occurs.
• the temperature of the tube, at the inlet end of the gas is 900° C. and at the outlet end 1,125° C.
• the tube is made from a FeCrAl material containing, in addition to Fe, 10 to 25% by weight of Cr, 1 to 10% by weight of Al and 1.5 to 5% by weight of Mo.
• the material contains smaller fractions of one or more of the alloying materials, tantalum, hafnium, zirconium, yttrium, nitrogen, carbon and oxygen.
• the material comprises up to a total of 2.2 wt. %, preferably up to 2.0 wt. % and more preferably up to 1.0 wt. %, of one or more alloying materials selected from the group consisting of tantalum, hafnium, zirconium, yttrium, nitrogen, carbon and oxygen.
• the material contains 2 to 3.5% by weight of molybdenum.
• the tube is made from a material having a creep strength high enough that the time to break of the tube at a temperature of 1,100° C. and a load of 2.2 MPa exceeds 100,000 hours. This corresponds to substantially a twice as high a creep strength in comparison with tubes made from the material disclosed in the Swedish Patent No. 467 414.
• the higher creep strength entails a corresponding considerable increase of the service life of the tube.
• a cracker tube may typically be 10 to 17 meters long.
• Such a tube consists of two or more tubes welded together in the longitudinal direction. According to a preferred embodiment, the tube is formed in one piece having a length exceeding 10 meters.
• Additional exemplary embodiments of the tube may be varied in respect of the material composition, above all regarding alloying materials having a low percentage in the material.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Physics & Mathematics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Thermal Sciences (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Combustion Of Fluid Fuel (AREA)
• Gas Burners (AREA)

Applications Claiming Priority (2)

Publications (1)

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Cited By (2)

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Citations (5)

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• 2003
  • 2003-05-20 SE SE0301500A patent/SE0301500L/xx not_active IP Right Cessation
• 2004
  • 2004-05-14 JP JP2006532193A patent/JP2007506866A/ja active Pending
  • 2004-05-14 EP EP04733228A patent/EP1627093A1/en not_active Withdrawn
  • 2004-05-14 WO PCT/SE2004/000757 patent/WO2004104257A1/en active Application Filing
  • 2004-05-14 CN CNB2004800137969A patent/CN100365151C/zh not_active Expired - Fee Related
  • 2004-05-17 US US10/846,593 patent/US20050019202A1/en not_active Abandoned

Patent Citations (5)

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