US3738795A - Regenerative hot blast stoves and their operation - Google Patents

Regenerative hot blast stoves and their operation Download PDF

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Publication number
US3738795A
US3738795A US00157874A US3738795DA US3738795A US 3738795 A US3738795 A US 3738795A US 00157874 A US00157874 A US 00157874A US 3738795D A US3738795D A US 3738795DA US 3738795 A US3738795 A US 3738795A
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United States
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blast
stoves
cold air
hot
furnace
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US00157874A
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English (en)
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A Heuer
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Didier Werke AG
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Didier Werke AG
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B9/00—Stoves for heating the blast in blast furnaces
    • C21B9/16—Cooling or drying the hot-blast

Definitions

  • ABSTRACT A method and apparatus for operating regenerative hot'blast stoves which are heated successively or alternately to supply the hot-blast required in blast furnaces.
  • Each furnace is provided with a group of at least two hotblast stoves which share a common cold air supply manifold and a common hot-blast pipe leading to the furnace.
  • the stove which is ready to go on-wind is first filled with compressed air from a source independent of the cold air supply manifold and then is directed to the cold air supply manifolds.
  • Each blast furnace stove is connected by a valve controlled filling connection to a common filling pipe communicating with an air tank connected to a blower.
  • This invention relates to regenerative hot-blast stoves, also known as Cowper stoves, for supplying the necessary hot blast to blast furnaces.
  • the furnace is blown with compressed air, often referred to as the wind, raised to high temperatures in hot-blast stoves.
  • compressed air often referred to as the wind
  • the volume and temperature of this hot blast are controlled and kept constant at given levels. If for any reason whatsoever these levels change the blast furnace at once reacts by instability in operation and, depending upon the magnitude and duration of the failure in control, major operational difficulties may result.
  • the temperature of the hot blast is conventionally kept constant by mixing it with a part of the cold air supply which by-passes the on-wind stove, the proportion thus mixed being that necessary for maintaining the predetermined temperature of the hot blast.
  • the sum of the volumes of the air that flows through the stove that is on-wind and of the cold air that bypasses the stove for mixture with the hot blast is equal to the total volume of air that is kept constant by the volume control and that enters the blast furnace during theon-wind period.
  • valve means onfthe cold air side are provided with relieving devices which upon initiation of the valve opening process first open a relatively small flow cross section and allow filling air to flow through this section until the pressure in the blast furnace stove is roughly equal to that in the cold air supply system.
  • the cold air gate valve can then be opened without an undue expenditure of power and drive means.
  • the withdrawal of the filling air is also accompanied by a sudden temperature drop of the hot blast entering the furnace, because the reduction in the velocity of the air in contact with the checkerwork of the stove that is still on-wind results in a reduced transfer of heat to the air which thus accepts less heat per unit of volume.
  • the hot-blast stove that is ready to go on-wind is first filled with compressed air from a source that is independent of the cold air supply manifold, and is then connecting to the cold air supply manifold by opening the cold air valve.
  • This proposal enables the rate at which the hot blast is supplied to the blast furnace to be steady in every phase of operation of the furnace, i.e., the blast furnace will be blown with a substantially constant supply of hot air and the smelting and reducing processes inside the blast furnace will proceed satisfactorily. Expensive troubles and interruptions in .the operation of the furnace are thus largely avoided.
  • each hot-blast stove is connected through a valve-controlled filling connection to a compressed-air storage tank associated with a blower.
  • This arrangement has the advantage that a supply of compressed air for filling is always available, i.e., that the supply of filling air is not directly dependent upon the operating times and capacity of a blower.
  • the blower in the proposed arrangement may be started up whenever the pressure in the air storage tank has dropped below a minimum level. When a predetermined maximum pressure has been built up in the tank than the air pressure in the stove. Generally speaking the pressure and the capacity of the air storage tank will be so chosen that with due regard to local conditions economic efficiency is an optimum.
  • the calculation of the pressure required in the tank poses no problems.
  • the unobstructed capacity of the hot-blast stove is first determined and the quantity of air is calculated that will fill this capacity at the required pressure. Account must be taken of the temperature rise experienced by the inflowing filling air and the volume of flue gas still in the stove.
  • the necessary capacity of the blower for filling the air tank depends upon the size of the tank and the time available for filling the same. This time must not exceed that between the change-over of two consecutive stoves from on-gas to on-wind, less the time needed for opening and closing the associated valves.
  • the inlet of the filling blower to the cold air blower on the delivery side thereof, so that the filling blower will be called upon to supply only the difference in pressure between that of the cold air supply and the final pressure in the air tank.
  • the uniform consumption of cold air distributed uniformly over the entire filling time which substantially corresponds to the on-wind time and which has been calculated to amount to about 1 percent of the hourly volume of blown air may be allowed for (without affecting the operation of the blast furnace) by a suitable adjustment of the blower generating the blast or of the volume control elements.
  • the invention is applicable to any method of operation of hot-blast stoves irrespectively as to whether two, three, four or more stoves are operated alternatively, parallel in pairs simultaneously or displaced in phase.
  • FIG. 1 is a fragmentary schematic diagram of a hotblast stove installation for a blast furnace.
  • FIG. 2 is a fragmentary schematic diagram of a modification of the system of FIG. 1.
  • a set of hot-blast stoves for a blast furnace includes at least two hot-blast stoves 1 and 2 having external combustion chambers 3 and 4 for the production of the hot gases used for heating the checkerwork inside the stoves.
  • the media for combustion (fuel gas and air) are admitted through pipes 5, 6 and 7, 8 whereas the exhaust gases escape through conduits 9 and 10.
  • Both hot-blast stoves are connected through cold air gate valves 11 and 12 to a cold air manifold 13 supplied by a blower not shown in the drawing, and through hot blast gate valves 14 and 15 to a hot blast pipe 16 which carries the hot blast to the blast furnace.
  • a bypass pipe 17 connected to the cold air manifold 13 has branches 20, 21 leading respectively to the combustion chambers 3 and 4 and incorporating respective stop valves 18 and 19 for use as mixer valves.
  • a blower 22 is provided for filling a compressed air tank 23 from which a pipe 24 having branches 25 and 26 is connected through stop valves 27 and 28 to the pipe between each hot-blast stove 1 or 2 and its associated cold air gate valve 11 or 12, downstream of the gate valve.
  • the set of hot-blast stoves (of which there may be more than two) is operated as follows, at least in so far as this is relevant to the invention.
  • the stop valve 28 is first opened to fill the hot-blast stove 2 with air through pipes 24, 26.
  • valve 28 is reclosed and the cold air gate valve 12 is opened.
  • the hot blast gate valve 15 and the mixer valve 19 which introduces cold air into the hot blast for adjusting the latter to the prescribed temperature level are opened.
  • the cooled hot-blast stove 1 is shut down.
  • the compressed air tank 23 has effected the equalization of volume and pressure in the stove 2 the blower 22 cuts in automatically and refills the tank 23 to a prescribed maximum pressure.
  • each stove has connected thereto an individual blower 22.
  • This modification otherwise operates in the manner described above with regard to FIG. 1.
  • a method of operating regenerative hot-blast stoves which are heated successively or alternatively and then supply the hot blast required in blast furnaces, each furnace being provided with a group of at least two hot-blast stoves which share a common cold air supply manifold and a common hot blast pipe leading to said furnace, said method comprising first filling one of said stoves which is ready to go on-windwith compressed air from a source independent of the cold air supply manifold and then connecting said stove to the cold air supply manifold by the opening of its cold air valve.
  • a system for supplying the hot blast to a blast furnace comprising a plurality of hot-blast stoves, means for heating said stoves successively or alternatively, a common cold air supply manifold connected to each stove through a closable cold air valve, and a separate filling blower connected to each stove for filling it with compressed air.
  • a method of operating regenerative blast furnace stoves which are heated alternatively and then supply the hot blast required in blast furnaces comprising providing each furnace with a group of at least two blast furnace stoves which share a common cold air supply manifold, providing a common hot blast pipe to said furnace, first filling one of said stoves which is ready to go on-wind with air from a source independent of said cold air supply manifold, and then connecting said stove to said cold air supply manifold by opening a cold air valve.
  • said compressed air supply means comprises a compressed air reservoir supplied by a filling blower.
  • said compressed air supply means comprises a filling blower and a common filling pipe connected thereto, said filling pipe being connected to the valve controlled connection to each of said stoves.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Drying Of Solid Materials (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
US00157874A 1970-07-01 1971-06-29 Regenerative hot blast stoves and their operation Expired - Lifetime US3738795A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19702032498 DE2032498A1 (enrdf_load_stackoverflow) 1970-07-01 1970-07-01

Publications (1)

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US3738795A true US3738795A (en) 1973-06-12

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US00157874A Expired - Lifetime US3738795A (en) 1970-07-01 1971-06-29 Regenerative hot blast stoves and their operation

Country Status (12)

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US (1) US3738795A (enrdf_load_stackoverflow)
JP (1) JPS5026482B1 (enrdf_load_stackoverflow)
AT (1) AT320697B (enrdf_load_stackoverflow)
BE (1) BE769333A (enrdf_load_stackoverflow)
CA (1) CA949320A (enrdf_load_stackoverflow)
DE (1) DE2032498A1 (enrdf_load_stackoverflow)
ES (1) ES198008Y (enrdf_load_stackoverflow)
FR (1) FR2097105B1 (enrdf_load_stackoverflow)
GB (1) GB1308109A (enrdf_load_stackoverflow)
LU (1) LU63425A1 (enrdf_load_stackoverflow)
NL (1) NL7108949A (enrdf_load_stackoverflow)
ZA (1) ZA714014B (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3951586A (en) * 1975-01-09 1976-04-20 Compressor Controls Corporation Method of operating the heating stoves
US5517767A (en) * 1995-02-01 1996-05-21 Schechinger; Thomas M. Grass and other yard waste materials dryer apparatus and method
US5700420A (en) * 1994-12-02 1997-12-23 Kawasaki Steel Corporation Non-oxidizing heating method and apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3951586A (en) * 1975-01-09 1976-04-20 Compressor Controls Corporation Method of operating the heating stoves
US5700420A (en) * 1994-12-02 1997-12-23 Kawasaki Steel Corporation Non-oxidizing heating method and apparatus
US5517767A (en) * 1995-02-01 1996-05-21 Schechinger; Thomas M. Grass and other yard waste materials dryer apparatus and method

Also Published As

Publication number Publication date
BE769333A (fr) 1971-11-03
LU63425A1 (enrdf_load_stackoverflow) 1971-09-24
GB1308109A (en) 1973-02-21
ES198008U (es) 1975-05-01
ZA714014B (en) 1972-02-23
FR2097105A1 (enrdf_load_stackoverflow) 1972-03-03
NL7108949A (enrdf_load_stackoverflow) 1972-01-04
DE2032498A1 (enrdf_load_stackoverflow) 1972-03-23
CA949320A (en) 1974-06-18
JPS5026482B1 (enrdf_load_stackoverflow) 1975-09-01
FR2097105B1 (enrdf_load_stackoverflow) 1975-02-07
AT320697B (de) 1975-02-25
ES198008Y (es) 1975-10-01

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