US3642262A - Method for operating a regenerative gas heater, and a gas heater for use in this method - Google Patents

Method for operating a regenerative gas heater, and a gas heater for use in this method Download PDF

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Publication number
US3642262A
US3642262A US653A US3642262DA US3642262A US 3642262 A US3642262 A US 3642262A US 653 A US653 A US 653A US 3642262D A US3642262D A US 3642262DA US 3642262 A US3642262 A US 3642262A
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US
United States
Prior art keywords
air
gas
burner
heater
blast
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Expired - Lifetime
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US653A
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English (en)
Inventor
Aart Kornelis Vroege
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Koninklijke Nederlandsche Hoogovens en Staalfabrieken NV
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Koninklijke Hoogovens En Staal
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D17/00—Regenerative heat-exchange apparatus in which a stationary intermediate heat-transfer medium or body is contacted successively by each heat-exchange medium, e.g. using granular particles
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B9/00—Stoves for heating the blast in blast furnaces

Definitions

  • the improvement consists in that during the on blast period cold air is supplied through the burner, to be mixed with the hot blast inside the stove.
  • cold air is supplied through the burner, to be mixed with the hot blast inside the stove.
  • the supply of blast air into the stove and of mixing air through the burner is controlled to obtain a constant quantity of hot blast per unit time, of a constant temperature.
  • This invention relates to a method for operating a regenerative gas heater, for instance and in particular an air preheater for preheating the air for a blast furnace, a so called hot blast stove or cowper. Moreover this invention relates to a gas heater for use with this method.
  • Heat regenerators or so-called gas or air preheaters are known in several fields of the art for regenerating heat generated during some process or for regenerating combustible components in a gas.
  • One of the best known applications of such air preheaters is in the blast furnace field, where the latent heat present in coke oven or blast furnace gas or in other fuel such as natural gas is transferred into sensible heat by combustion in a burner stack or shaft, which heat is stored in a pile of porous bricks (the checker work).
  • the air for the blast furnace is preheated by guiding it through the heated preheater in the reverse direction.
  • a quite usual system is one in which cold air for mixing is supplied to the manifold or collecting duct into which the several air preheaters dispense their heated air (the socalled hot blast main), said mixing air being supplied to that end of said main which is opposite to the end connected to the blast furnace.
  • a disadvantage of this method consists in that the part of this main between the first and the last air preheater when switching these preheaters periodically will take at one moment the temperature of the hottest preheated air and at another moment the temperature of the cold mixing air.
  • the air temperatures used gradually increase (in the last few years they have been raised from about 600 to about l,l C. or even higher) this causes serious problems in design and maintenance.
  • the steel hot blast main and the refractory lining thereof will expand and shrink considerably, and moreover this will take place in a manner which differs from place to place along the main. Also the joint of the air preheaters to this main causes serious complications by this phenomenon.
  • a further earlier suggested method consists in that cold air is mixed to the preheated air in more than one mixing chamber, each mixing chamber being positioned between an air preheater and the hot blast main.
  • the present invention aims at removing the said objections of prior proposals. As will be explained below the application of the invention moreover gives additional advantages.
  • the present invention consists in that during the on blast" (air preheating) period of the preheater cold air is introduced through the supply for the combustion air into the burner stack of the preheater and is in said stack mixed with the hot air. It is remarked that the supply for the combustion air is already present on existing air preheaters for forming a combustible mixture in the burner stack during the heating up of the air preheater (on gas" period). As mixed air thus enters the hot blast main this main will remain at a substantially constant temperature.
  • An important advantage of the new method moreover consists in that a good mixing within the burner stack is obtainable so that the provision of additional mixing chambers is superfluous.
  • the burners applied are of a type in which the combustion air causes heavy turbulence in the burner stack. The supply of the cold mixing air through said burners thus assures a good mixing with the hot air within the burner stack.
  • the burner during the heating-up (on gas) period is cooled by the combustion air flowing through it and along it.
  • the air preheating (on blast) period the head or end face of the burner is heated to a very high temperature by the hot air which flows downwardly through the burner stack.
  • the burner head will be cooled by the mixing air also during the preheating period (on blast) so that this burner is much less subjected to thermal shocks.
  • valves for the preheated air which without applying the invention should be able to withstand the highest occurring air preheating temperature in the preheater, will, when applying the invention, never obtain a higher temperature than for instance 150 C. below this highest temperature. With the gradually increasing preheating temperatures said valves cause a very difficult problem and the necessity of expensive structures in order to have them operate reliably.
  • this invention also relates distance thereof before its connection to the blast furnace. to thepreheaters which are used for realizing this invention.
  • Such a preheater is according to this invention characterized in that the supply duct for the combustion air is connected to means for blowing air against the pressure of the air preheated in the preheater into the burner stack in a quantity which is controllable from to 20 percent of the total quantity of preheated air leaving the preheater.
  • the said means could consist of a separate compressor, but it is also possible to have the cold air supplied by the same compressor which also compresses the air to be preheated, which flows through the pile of bricks (checker work).
  • Known preheaters have either interior or exterior burner stacks. Both types could have exterior burners mainly from metal or they could have ceramic burners positioned in the burner stack.
  • air preheaters with a so-called ceramic burner are preferred.
  • Such a ceramic burner appeared to be able to give a better mixing within the burner stack over a shorter length of this stack.
  • the outflow opening for the preheated air according to this invention at a short distance above the burner head.
  • the height of that part of the burner stack, along which considerably varying temperatures could occur during the on gas and on blast periods will thus be very small. Thereby damage to the refractory lining is reduced to a minimum.
  • FIG. 1 shows diagrammatically an air preheater (hot blast stove) with internal burner stack and interior ceramic burner in longitudinal section, and
  • FIG. 2 shows diagrammatically an apparatus arrangement for carrying out the invention.
  • FIG. 1 of the drawing reference numeral 1 shows the easing of the air preheater, which, together with the bottom 2, upon which it rests, forms a masonry structure.
  • the brick casing is surrounded by a steel outer lining (not shown).
  • a set of piles or columns 3 upstanding from the bottom 2 carries a grid 4 which serves for supporting perforated bricks piled thereon (checker work), which have not been shown, and through which alternately hot combustion air flows downwardly (on gas period) and air to be heated flows upwardly (on blast period).
  • This so-called pile of bricks is separated by a separating wall 5 from the burner stack which in its turn is bordered at its other side by a segment of casing 1.
  • the air preheater at its upper end is closed by a brick dome 6 and a steel dome 7.
  • the gaseous fuel and the air for generating the hot combustion gases are supplied by a passage 8 and by annular duct 9 respectively, guiding these gases to burner block 10.
  • burner has been shown diagrammatically in the drawing. It is a so-called ceramic burner known as such and arranged entirely within the lining l of the preheater in the lower end of the burner stack.
  • This cold air flowing from burner block 10 mixes intimately with the hot air flowing from above downwardly through the burner stack, after which the mixtureis guided through port 12 to a collecting duct of manifold (hot blast -main, not shown), from where it flows to the blast furnace.
  • Port 12 with its air valve V, FIG. 2, at the outside, is arranged in the wall of casing l at the shortest possible distance above the burner head 10.
  • the mixing zone proper is thus restricted to that part of the height of the burner stack which is between the burner head 10 and this port 12. Thereby the refractory bricks of the burner stack are subjected as little as possible to thermal shock.
  • the cold mixing air which flows through the burner head 10 also takes care of cooling this head during the on blast period, so that this burner head both during the on gas period and the on blast period is cooled.
  • the burner head 10 is made of ceramic material. In other respects the shape of this burner head is not essential for the present invention.
  • the temperature responsive flow proportioning means 20 is controlled by temperature responsive means 21 responsive to the temperature T of the mixed gas leaving the port 12 during the on blast period (when valve V is open), and operates suitable means, shown as throttle valves 22 and 23, to vary the amounts of cold and hot gases 0] and Q2 being mixed to form the quantity Q; the quantity Q1 of cold gas from 17 of course being at its maximum, e.g., 20 percent of Q, when the checker work is hottest, and being of course reduced, with corresponding increase in the quantity Q2 of gas from 16, as the checker work cools during the progress of the on blast period.
  • a method according to claim 1 characterized in that the quantities per unit time of cold gas introduced through said supply for combustion air and of gas to be heated as supplied to the gas heater are varied during operation so as to obtain a constant quantity of the mixture thereof per unit time leaving the heater at a constant temperature.
  • a regenerative gas heater having a burner, of which a supply duct for combustion air is connected to means for blowing a gas such as air into a burner stack of the heater against the pressure of the gas to be heated therein, means being provided to control the quantity of said gas blown into the burner stack in a quantity region per unit time of 0 to percent of the quantity per unit time of the heated gas leaving the heater.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Air Supply (AREA)
US653A 1969-01-16 1970-01-05 Method for operating a regenerative gas heater, and a gas heater for use in this method Expired - Lifetime US3642262A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6900740A NL6900740A (es) 1969-01-16 1969-01-16

Publications (1)

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US3642262A true US3642262A (en) 1972-02-15

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US653A Expired - Lifetime US3642262A (en) 1969-01-16 1970-01-05 Method for operating a regenerative gas heater, and a gas heater for use in this method

Country Status (6)

Country Link
US (1) US3642262A (es)
JP (1) JPS4816939B1 (es)
BE (1) BE744408A (es)
DE (1) DE2000766A1 (es)
GB (1) GB1250443A (es)
NL (1) NL6900740A (es)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3824070A (en) * 1972-05-13 1974-07-16 Otto & Co Gmbh Dr C Air heater with internal combustion chamber
US4582485A (en) * 1985-02-13 1986-04-15 White Jr Herbert A Blast furnace stove
US20080199820A1 (en) * 2005-02-01 2008-08-21 Danieli Corus Bv Support Assembly For Supporting Heat Regeneration Checker Work In A Hot Blast Stove, Hot Blast Stove Provided With Said Support Assembly, Method Of Producing Hot Air Using Said Hot Blast Stove
RU2445376C1 (ru) * 2009-12-29 2012-03-20 Украинский Государственный Научно-Технический Центр По Технологии И Оборудованию, Обработке Металлов, Защите Окружающей Среды И Использованию Вторичных Ресурсов Для Металлургии И Машиностроения "Энергосталь" Воздухонагреватель доменной печи

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL1007581C2 (nl) * 1997-11-19 1999-05-20 Hoogovens Tech Services Keramische brander voor gassen en regeneratieve warmtegenerator voorzien daarvan.

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2175611A (en) * 1937-01-30 1939-10-10 Koppers Co Inc Gas heater
US3082995A (en) * 1960-12-21 1963-03-26 United States Steel Corp Apparatus for heating blast furnace stoves

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2175611A (en) * 1937-01-30 1939-10-10 Koppers Co Inc Gas heater
US3082995A (en) * 1960-12-21 1963-03-26 United States Steel Corp Apparatus for heating blast furnace stoves

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3824070A (en) * 1972-05-13 1974-07-16 Otto & Co Gmbh Dr C Air heater with internal combustion chamber
US4582485A (en) * 1985-02-13 1986-04-15 White Jr Herbert A Blast furnace stove
US20080199820A1 (en) * 2005-02-01 2008-08-21 Danieli Corus Bv Support Assembly For Supporting Heat Regeneration Checker Work In A Hot Blast Stove, Hot Blast Stove Provided With Said Support Assembly, Method Of Producing Hot Air Using Said Hot Blast Stove
RU2445376C1 (ru) * 2009-12-29 2012-03-20 Украинский Государственный Научно-Технический Центр По Технологии И Оборудованию, Обработке Металлов, Защите Окружающей Среды И Использованию Вторичных Ресурсов Для Металлургии И Машиностроения "Энергосталь" Воздухонагреватель доменной печи

Also Published As

Publication number Publication date
BE744408A (nl) 1970-07-14
GB1250443A (es) 1971-10-20
DE2000766A1 (de) 1970-07-30
NL6900740A (es) 1970-07-20
JPS4816939B1 (es) 1973-05-25

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