US3268371A - Process and apparatus for annealing metal plates - Google Patents

Process and apparatus for annealing metal plates Download PDF

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Publication number
US3268371A
US3268371A US444894A US44489465A US3268371A US 3268371 A US3268371 A US 3268371A US 444894 A US444894 A US 444894A US 44489465 A US44489465 A US 44489465A US 3268371 A US3268371 A US 3268371A
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furnace
gases
cooling
furnaces
hydrogen
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US444894A
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English (en)
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Daubersy Jean
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/767—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material with forced gas circulation; Reheating thereof
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D3/00—Diffusion processes for extraction of non-metals; Furnaces therefor
    • C21D3/02—Extraction of non-metals
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/663—Bell-type furnaces
    • C21D9/667—Multi-station furnaces

Definitions

  • the present invention relates to a process and apparatus for annealing soft steel plates in moist hydrogen.
  • the technique now recommended consists in using annealing furnaces very similar to the bell furnaces traditionally employed for non-expanded coils and which comprise like these traditional furnaces a hearth provided with a system of internal circulation of the-atmospheres gases (fan).
  • Their use for a decarburizing-denitrifying annealing operation comprises in principle a period of heating under a neutral protective gas (such as HNX gas), a period of soaking (maintenance at constant temperature) in an atmosphere of moist H gas and a period of cooling under a protective gas such as dry HNX gas, which is a mixture of N with 5 to H So used, these furnaces give after annealing, non-aging steels.
  • a neutral protective gas such as HNX gas
  • dry HNX gas which is a mixture of N with 5 to H So used
  • This circulation internal to the furnace comprises the successive flowing of the gases through the turbine, along the heated walls of the bell and through the spirals of the coils, the cycle beginning again endlessly with a flow resulting from the motive power due to the fan and the internal resistance of the circuit.
  • On thi internal circulation there is superposed an external circulation comprising the injection in the furnace of a certain quantity of fresh gases and the extraction of an approximately equal volume of gas contaminated by the impurities coming from the chemical reactions which take place in the furnace.
  • the fan has without doubt an appreciable efieot on the time of heating in a relatively dense atmosphere such as HNX gas (more than of N but when the gases become heated and especially when the protective atmosphere is replaced by moist hydrogen considerably lighter and carried to temperatures of the order of 700 C. the flows .shut down considerably.
  • HNX gas more than of N but when the gases become heated and especially when the protective atmosphere is replaced by moist hydrogen considerably lighter and carried to temperatures of the order of 700 C. the flows .shut down considerably.
  • the flow circulating in the coils measured in standard cubic meters, was in the period of soaking with moist hydrogen reduced to less than of the flow of gas realized at the beginning of the heating under HNX gas.
  • the fresh gas injected when the fan delivers on the internal circuit, the fresh gas injected must necessarily be mixed with the contaminated gas in circulation and the high degrees of purity necessary for denitrification are only very slowly attained.
  • the process is characterized in that expanded coils are introduced into several furnaces and subjected simultaneously to successive operations of heating under protective atmosphere (HNX), of soaking under moist hydrogen and cooling under protective atmosphere (HNX) in a that the atmospheres gases effect a simple travel through .each furnace and its charge (that is to say without superare characterized chiefly by the following features:
  • furnaces used have their own system of heating and cooling but have no fan for internal circulation.
  • the arrangement according to the invention is particularly well adapted to the recovery of the contaminated hydrogen gas, its purification and its recycling by a process already disclosed by the inventor.
  • the number of units to be grouped in series is limited on the one hand because the pressures necessary for cir culation of the gases in each of the furnaces are added and pose a problem of tightness of the joints and, on the other hand, by the fact that the simultaneous operation of several furnaces breaks the continuity of the rhythm of supplying and emptying the coil annealing plant.
  • Groups of four or five units of two superposed coils give satisfaction in these two respects, but this is far from being restrictive.
  • a period of soaking with moist hydrogen one must not exceed 200 mm. of water for flows of the order of 2000 cu. m. per hour. This gives acceptable operating conditions for the packed joints of the bells and permits reducing annealing time by about 50%.
  • a heating by a heater of the protective gases which is interposed between each furnace in the same manner as the cooler; these two devices may even be combined so as to serve alternatively as a heater or as a cooler.
  • FIGURE 1 is a vertical cross section partly in diagrammatic outline of a two furnace group
  • FIGURE 2 is a diagrammatic view of three groups of four furnaces.
  • FIGURE 1 shows two furnaces of a group equipped and connected according to the invention with 1 and 2 representing transportable heating caissons which cover the two furnaces.
  • Each furnace has a perforated foundation 3 connected in a tight manner by means of a coder 4 to the outlet pipe line 5 for the protective gases.
  • a coder 4 On this foundation rest the open coils 6.
  • the latter are covered with a hell 7 which isolates them by means of a packed joint 8.
  • the free circular crown 9 between the bell and the coils is connected in a tight manner to the inlet pipe 10 for the protective gases.
  • FIG. 2 represents a diagram ofan installation illustrating 3 groups of 4 furnaces, the first group being rep resented as for heating, the second group as cooling and the third group for discharging orcharging.
  • Each furnace or base is shown on its foundation 3, the different elements being marked with ;the' same numerals as in FIG. 1.
  • Each group has in front of the head furnace a gas heater l'and at the back of the last furnace of the group a gas cooler 17.
  • the feeding of H gas is effected under the operating pressure of the gasholder 18 with the aid of a pipe 19 and valves 20.
  • the hydrogen gas circulates in series in each of the furnaces of the group, is cooled in the cooler 17 and recovered by the circuit comprising the valve 21, the pipe 22, the compressor 23, the purifier 24 which frees it from the CO impurities and the combined nitrogen; the gas thus returning to the gas holder through the conduit 25.
  • the feeding with fresh hydrogen is effected at 26 and the cleaning at 27.
  • HNX The feeding of HNX is effected under the motive pressure of the gas holder 28 and of the compressor 29 through the pipe 30 and the valves 31.
  • the gas HNX can be recovered in the gas holder 28 by the circuit comprising the valves 32 and the conduit 33.
  • the addition of fresh HNX is effected at 34.
  • the purges of HNX gas contaminated by oil vapor at the beginning of the heating are effected through the pipe 33 provided with valves 36 and oil extractors 37.
  • the numeral 43 indicates the cooling bells. In order to simplify the diagram the moistening of the hydrogen has not been shown; it may carried out by known means once for all for the series of furnaces.
  • valves 20 and 21, which are used for cold hydrogen, at relatively slight pressure, to be tight.
  • Such valves are available as commercial units.
  • the intermediate coolers are placed out of service by the appropriate manipulation of the short circuit flap valve and/or the cutting off of the cooling fluid.
  • the heating furnaces are withdrawn and they are replaced by the cooling bells (middle group of FIG. 2) and the intermediate coolers are put into service.
  • the replacement of the H gas by HNX gas is effected at the opportune time by manipulations analogous to those already described for the reverse change.
  • the HNX by a more important circulation of air after having actuated the fan 38. The air is allowed to escape at the outlet through the valve 42 and the pipe 41.
  • Process for the decarburization and denitrification of steel sheets annealed in expanded coils under a hell by moist hydrogen comprising introducing the expanded coils into a plurality of bell-shaped furnaces, subjecting simultaneously all the coils to the successive operation of heating at 6 750 C.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Furnace Details (AREA)
US444894A 1961-03-07 1965-03-11 Process and apparatus for annealing metal plates Expired - Lifetime US3268371A (en)

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BE38977 1961-03-07

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AT (1) AT244374B (de)
GB (1) GB986685A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3966509A (en) * 1975-01-22 1976-06-29 United States Steel Corporation Method for reducing carbon deposits during box annealing
US4069071A (en) * 1975-04-11 1978-01-17 Societe Chimique De La Grande Paroisse, Azote Et Produits Chimiques Method for generating a reducing atmosphere for heat-treating installations
AT395321B (de) * 1983-07-05 1992-11-25 Ebner Ind Ofenbau Verfahren zum abkuehlen von chargen in diskontinuierlich arbeitenden industrieoefen, insbesondere von stahldraht- oder - bandbunden in haubengluehoefen

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1727192A (en) * 1926-08-20 1929-09-03 Thaddeus F Baily Annealing equipment and method
US1849561A (en) * 1929-07-06 1932-03-15 Wiberg Frans Martin Method of treating solid materials with gases
US1864593A (en) * 1929-05-15 1932-06-28 Gustafsson Emil Gustaf Torvald Method of producing metal sponge
GB497480A (en) * 1937-04-15 1938-12-15 James Macdonald Improvements in or relating to furnaces for the heat treatment of materials or of articles
US2998303A (en) * 1958-08-26 1961-08-29 Midland Ross Corp Method for purifying hydrogen contaminated with methane
US3109877A (en) * 1960-07-01 1963-11-05 Wilson Lee Apparatus for modifying the composition of strip metal
US3127289A (en) * 1964-03-31 hoursx
US3185463A (en) * 1960-07-18 1965-05-25 Metallurg D Esperance Longdoz Apparatus for conditioning air and gases for annealing steel plates and the like

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3127289A (en) * 1964-03-31 hoursx
US1727192A (en) * 1926-08-20 1929-09-03 Thaddeus F Baily Annealing equipment and method
US1864593A (en) * 1929-05-15 1932-06-28 Gustafsson Emil Gustaf Torvald Method of producing metal sponge
US1849561A (en) * 1929-07-06 1932-03-15 Wiberg Frans Martin Method of treating solid materials with gases
GB497480A (en) * 1937-04-15 1938-12-15 James Macdonald Improvements in or relating to furnaces for the heat treatment of materials or of articles
US2998303A (en) * 1958-08-26 1961-08-29 Midland Ross Corp Method for purifying hydrogen contaminated with methane
US3109877A (en) * 1960-07-01 1963-11-05 Wilson Lee Apparatus for modifying the composition of strip metal
US3185463A (en) * 1960-07-18 1965-05-25 Metallurg D Esperance Longdoz Apparatus for conditioning air and gases for annealing steel plates and the like

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3966509A (en) * 1975-01-22 1976-06-29 United States Steel Corporation Method for reducing carbon deposits during box annealing
US4069071A (en) * 1975-04-11 1978-01-17 Societe Chimique De La Grande Paroisse, Azote Et Produits Chimiques Method for generating a reducing atmosphere for heat-treating installations
AT395321B (de) * 1983-07-05 1992-11-25 Ebner Ind Ofenbau Verfahren zum abkuehlen von chargen in diskontinuierlich arbeitenden industrieoefen, insbesondere von stahldraht- oder - bandbunden in haubengluehoefen

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GB986685A (en) 1965-03-24
AT244374B (de) 1966-01-10

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