PROCESS AND INSTALLATION FOR HEATING A METALLIC STRIP, NOTABLY FOR AN ANNEALING

• US 20130277896A1
• Filed: 06/04/2013
• Published: 10/24/2013
• Est. Priority Date: 05/30/2007
• Status: Active Grant

• Current Assignee: Gdf Suez
• Original Assignee: Gdf Suez
• Inventors: Richard, Nicolas, Lhomme, Pierre-Jacques, BUCHET, Philippe
• Granted Patent: US 9,611,519 B2
• Time in Patent Office: Days
• US Class Current: 266/44
• CPC Class Codes: C21D 1/34 Methods of heating C21D1/06 takes precedence
• CPC Class Codes: C21D 9/0006 Details, accessories not peculiar to any of the following furnaces control devices C21D11/00
• CPC Class Codes: C21D 9/54 Furnaces for treating strips or wire
• CPC Class Codes: C21D 9/56 Continuous furnaces for strip or wire
• CPC Class Codes: F23L 15/02 Arrangements of regenerators
• CPC Class Codes: F27B 9/02 of multiple-track type; of multiple-chamber type; Combinations of furnaces
• CPC Class Codes: F27B 9/28 for treating continuous lengths of work
• CPC Class Codes: F27B 9/36 Arrangements of heating devices
• CPC Class Codes: F27D 13/00 Apparatus for preheating charges; Arrangements for preheating charges
• CPC Class Codes: Y02E 20/34 Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Abstract

The invention pertains to the heating of a metal strip, and relates to equipment for heating a metal strip that comprises a pre-heating housing provided with a device for projecting hot gases towards the strip, a heating housing with regenerative burners, a duct for discharging the gases from the heating housing, a three-way adjustable valve and an adjustment device including a sensor for detecting the setpoint temperature of the metal strip and a member for adjusting the three-way valve so that it can adjust the amount of hot gases fed to the projection device. The invention can be used in equipment for heating narrow strips before annealing the same.

Claims

1-10. -10. (canceled)

11. Preheating unit with regenerative burners wherein, in a first phase, some heat extracted from combustion gases is accumulated, and, in a second phase, the accumulated heat is returned to the combustion air comprising:

two burners mounted in tandem, a first burner working in a combustion mode in which some combustion air in a first duct circulates through a first regenerative mass before participating to a combustion providing still reducing combustion gases, and a second burner working in a heat recuperation mode in which the combustion gases from the first burner circulate through a second regenerative mass and heat the second regenerative mass, and after a certain length of time, the first and second burners exchange their ways of working,

wherein the first and second burners each comprise an air feeding device introducing, in the recuperation working mode, post-combustion air which mixes with the still reducing combustion gases, the regenerative mass recuperating heat from post-combustion reaction of still reducing gases with the post-combustion air introduced by the air feeding device, said post-combustion emanating an additional quantity of heat.

12. Preheating unit according to claim 11, wherein the air feeding device working in a regeneration mode introduces an essentially constant quantity of air, which is at least sufficient for the gases emanating from the post-combustion to have no reducing power.

13. Installation for heating a metallic strip to a set temperature needing the presence of a reducing combustion atmosphere, that comprises

a preheating unit according to claim 11,

a preheating chamber provided with a projection device for projecting hot gases from the post-combustion of the burner in the heat recuperation mode towards the strip,

a heating chamber comprising said burners, wherein the metallic strip is heated by the burner in the combustion mode.

14. Installation according to claim 13, further comprising an adjustable three-way valve with an entry connected to a duct for evacuating gases from the heating unit, an exit connected to the gas projection unit of the preheating chamber, and an exit connected to a duct for evacuating the gases outside the installation.

15. Installation according to claim 14, that further comprises a control device comprising a set temperature sensor for the metallic strip and an adjustment component for the three-way valve, in order that this valve controls the quantity of hot gases transmitted to the projection device.

16. Installation according to claim 13, that comprises a second control device which comprises a sensor for measuring the reducing power of the gases and an adjustment component for adjusting the introduced quantity of air according to the signal from the sensor for measuring the reducing power, and which is configured to control the quantity of air introduced by the air feeding device.

17. Installation according to claim 13, wherein the preheating and heating chambers are adjacent and collinear.

18. Device for heating air entering an oven, that comprises:

a first open fire burner comprising a first chamber and, inside said first chamber,

a first duct for inputting air and

a first regenerative mass for preheating the air input by said first duct,

a first air feeding device for at least introducing post-combustion air inside said first chamber,

at least one first gas entry for inputting gas at the first open fire burner, inside the oven,

a second open fire burner comprising a second chamber and, inside said second chamber,

a second duct for inputting air and

a second regenerative mass for preheating the air input by said second duct,

a second air feeding device for at least introducing post-combustion air inside said second chamber,

at least one second gas entry for inputting gas at the second open fire burner, inside the oven,

an operation unit for having

the first burner working in a combustion mode and burning, inside the oven, gas input from the at least one first gas and air input from the first duct and preheated by the first regenerative mass the first burner providing reducing combustion gas inside the oven and

the second burner working in a heat recuperation mode and burning reducing combustion gas entering the second chamber from the oven with post-combustion air input from the second air feeding device to heat the second regenerative mass and

after a certain length of time, exchanging the combustion mode and recuperation mode of the burners.

19. Device for heating air according to claim 18, wherein the air feeding device working in a regeneration mode introduces an essentially constant quantity of air, which is at least sufficient for the gases emanating from the post-combustion to have no reducing power.

20. Installation for heating a metallic strip to a set temperature needing the presence of a reducing combustion atmosphere, that comprises

a device for heating air according to claim 18,

a preheating chamber provided with a projection device for projecting hot gases from the post-combustion of the burner in the heat recuperation mode towards the strip,

a heating chamber comprising said burners, wherein the metallic strip is heated by the burner in the combustion mode.

21. Installation according to claim 20, further comprising an adjustable three-way valve with an entry connected to a duct for evacuating gases from the heating unit, an exit connected to the gas projection unit of the preheating chamber, and an exit connected to a duct for evacuating the gases outside the installation.

22. Installation according to claim 21, that further comprises a control device comprising a set temperature sensor for the metallic strip and an adjustment component for the three-way valve, in order that this valve controls the quantity of hot gases transmitted to the projection device.

23. Installation according to claim 20, that comprises a second control device which comprises a sensor for measuring the reducing power of the gases and an adjustment component for adjusting the introduced quantity of air according to the signal from the sensor for measuring the reducing power, and which is configured to control the quantity of air introduced by the air feeding device.

24. Installation according to claim 20, wherein the preheating and heating chambers are adjacent and collinear.

25. Process for preheating air with regenerative burners wherein, in a first phase, some heat extracted from combustion gases is accumulated, and, in a second phase, the accumulated heat is returned to the combustion air, wherein two burners mounted in tandem,

wherein, a first burner works in a combustion mode in which some combustion air in a first duct circulates through a first regenerative mass before participating to a combustion providing still reducing combustion gases, and

a second burner works in a heat recuperation mode in which the combustion gases from the first burner circulate through a second regenerative mass and heat the second regenerative mass, and

after a certain length of time, the first and second burners exchange their ways of working,

that further comprises, in the recuperation working mode, feeding post-combustion air which mixes with the still reducing combustion gases, and recuperating, with the regenerative mass, heat from post-combustion reaction of still reducing gases with the post-combustion air introduced by the air feeding device, said post-combustion emanating an additional quantity of heat.

26. Process for preheating air according to claim 25, wherein the quantity of post combustion air introduced for the mixing to the combustion gases is sufficient for the evacuated gases to have no reducing power.

27. Process for heating a metallic strip to a set temperature needing the presence of a reducing combustion atmosphere, that comprises the steps of the process for preheating air according to claim 25 and

a preheating of the strip to an intermediary temperature needing not the presence of a protective atmosphere, by projecting hot gases from the post combustion, towards at least one side of the strip, and

a heating of the strip with the burner in the combustion mode, in a reducing combustion atmosphere from the intermediary temperature to the set temperature.

28. Process for heating a metallic strip according to claim 27, that further comprises a control of the set temperature by varying the quantity of hot gases projected onto the metallic strip for the preheating of the metallic strip.

29. Process for heating a metallic strip according to claim 27, wherein the mixing of the combustion gases to the post-combustion air introduced before the passage of the combustion gases through the regenerative mass is adjusted according to the result of a measure of the reducing power of the combustion gases.

30. Process for heating a metallic strip according to claim 27, that further comprises implementing of a gas circulation directly from the heating step to the preheating step and the injection of post-combustion air between both these steps.