Abstract: A method for heat-treating a metal strip, where the metal strip is pre-heated continuously in a pre-heating zone with the aid of hot gas and subsequently undergoes further heat treatment in a directly fired furnace in a reducing and/or oxidizing atmosphere. The metal strip is pre-heated in the pre-heating zone with hot inert gas and further heated with an electric heating system before entering the directly fired furnace. A furnace plant for implementing the process and a related heat recovery system are also disclosed.

Abstract: The invention relates to a method for treating metal strip in a directly fired furnace through which the metal strip is guided. The furnace is fired directly by gas burners and has a non-fired zone through which the exhaust gases from the fired zone flow and thus heat the metal strip. After leaving the non-fired zone, the exhaust gases from the furnace undergo post-combustion in an afterburner chamber. According to the invention, methane is injected into the non-fired zone, which causes nitrogen oxides contained in the waste gas to be converted into hydrogen cyanide.

Abstract: The invention relates to a method for treating metal strip in a directly fired furnace through which the metal strip is guided. The furnace is fired directly by gas burners and has a non-fired zone through which the exhaust gases from the fired zone flow and thus heat the metal strip. After leaving the non-fired zone, the exhaust gases from the furnace undergo post-combustion in an afterburner chamber. According to the invention, methane is injected into the non-fired zone, which causes nitrogen oxides contained in the waste gas to be converted into hydrogen cyanide.

Abstract: A method for treating a metal strip, where the metal strip undergoes heat treatment in a directly fired furnace and is subsequently heat-treated further in a radiant tube furnace. At least part of the exhaust gases from the radiant tubes is fed to the directly fired furnace.

Abstract: A method for heat-treating a metal strip, where the metal strip is pre-heated continuously in a pre-heating zone with the aid of hot gas and subsequently undergoes further heat treatment in a directly fired furnace in a reducing and/or oxidizing atmosphere. The metal strip is pre-heated in the pre-heating zone with hot inert gas and further heated with an electric heating system before entering the directly fired furnace. A furnace plant for implementing the process and a related heat recovery system are also disclosed.

Abstract: A method of drying and/or curing an organic coating on a continuously running metal strip, includes heating the strip by electromagnetic induction in a tunnel furnace having an enclosure with hot internal walls and heating the enclosure. The heating of the strip by electromagnetic induction is coupled with heating by infrared radiation and heating by convection with a combustion gas. The heating of the enclosure of the furnace is performed by convection using the same combustion gas used for heating the strip by convection. A device for implementing the method is also provided.

Abstract: Equipment and a method for preheating a continuously moving steel strip, in particular before feeding the same into a continuous annealing or hot-dip galvanizing furnace, involves the continuous movement of the steel strip in a preheating chamber including a preheating circuit having at least one preheating tube, the inner surface of which is in contact with externally-recovered burnt gases (e.g. from the furnace). A portion of the outer surface of the preheating tube is disposed directly opposite a surface of the strip in order to provide a first preheating mode by irradiating heat onto the strip and the walls of the chamber, and a second preheating mode, mainly by convection, of a gas constituting a controlled atmosphere in the preheating chamber.

Abstract: A method for guaranteeing the oxidation of a strip designed to prevent the selective oxidation of alloy elements of the steel in a continuous steel strip galvanizing annealing furnace having a pre-heating section and a hold section and provided only with radiant tubes. The oxidation of the strip is designed to prevent the selective oxidation of elements of the steel alloy. The novel method includes the following steps: installation of at least one modified tube capable of injection an oxidizing medium at least one point in the oven heating section and/or at least one point in the hold section and injection of the oxidizing medium by means of the modified tube(s), the oxidizing medium having a composition such that in the conditions of the temperature of the oxidizing medium and the steel strip and as a function of the chemical composition of the strip said medium has a dew point which guarantees an in-depth oxidation of the alloy elements of the steel strip.

Abstract: A method for operating a continuous annealing or galvanizing line for a metal strip, uses a direct flame heating section with an upstream zone and a downstream zone. The direct flame heating section is followed by a radiant tube heating section. The metal strip is indirectly heated in the direct flame heating section. The heating of the metal strip is achieved in the upstream zone by combustion of a mixture of atmospheric air and fuel such that the temperature of the combustion gas is between 1250° C. and 1500° C., preferably close to 1350° C. and in the downstream zone, the heating of the metal strip is achieved by combustion of a superoxygenated substoichiometric mixture of air and fuel such that the temperature of the combustion gas achieved at the end of the upstream zone is maintained until the end of the downstream zone of the direct flame heating section.

Abstract: A method and a device adjust the cooling of a steel strip in an annealing or galvanization phase. The device is suitable for the forced cooling of a steel strip continuously running in a plant adapted for the continuous annealing or the continuous tempering galvanization. The device has at least one exchange member for transferring the heat of the steel strip to cooling water and includes an outlet for the cooling water thus heated up. At least one cooling unit is provided and has a sealed enclosure connected to the outlet of the exchange member and includes at least one outlet to a Venturi effect device such as a vapor outlet ejector and in which the cooling water itself is subjected to a vacuum-vaporization cooling. An auxiliary outlet of the sealed enclosure is connected to an inlet of the exchange member.

Abstract: Equipment and a method for preheating a continuously moving steel strip, in particular before feeding the same into a continuous annealing or hot-dip galvanizing furnace, involves the continuous movement of the steel strip in a preheating chamber including a preheating circuit having at least one preheating tube, the inner surface of which is in contact with externally-recovered burnt gases (e.g. from the furnace). A portion of the outer surface of the preheating tube is disposed directly opposite a surface of the strip in order to provide a first preheating mode by irradiating heat onto the strip and the walls of the chamber, and a second preheating mode, mainly by convection, of a gas constituting a controlled atmosphere in the preheating chamber.

Abstract: A method and a device adjust the cooling of a steel strip in an annealing or galvanization phase. The device is suitable for the forced cooling of a steel strip continuously running in a plant adapted for the continuous annealing or the continuous tempering galvanization. The device has at least one exchange member for transferring the heat of the steel strip to cooling water and includes an outlet for the cooling water thus heated up. At least one cooling unit is provided and has a sealed enclosure connected to the outlet of the exchange member and includes at least one outlet to a Venturi effect device such as a vapor outlet ejector and in which the cooling water itself is subjected to a vacuum-vaporization cooling. An auxiliary outlet of the sealed enclosure is connected to an inlet of the exchange member.

Abstract: A method of drying and/or curing an organic coating on a continuously running metal strip, includes heating the strip by electromagnetic induction in a tunnel furnace having an enclosure with hot internal walls and heating the enclosure. The heating of the strip by electromagnetic induction is coupled with heating by infrared radiation and heating by convection with a combustion gas. The heating of the enclosure of the furnace is performed by convection using the same combustion gas used for heating the strip by convection. A device for implementing the method is also provided.

Abstract: A method for operating a continuous annealing or galvanizing line for a metal strip, uses a direct flame heating section with an upstream zone and a downstream zone. The direct flame heating section is followed by a radiant tube heating section. The metal strip is indirectly heated in the direct flame heating section. The heating of the metal strip is achieved in the upstream zone by combustion of a mixture of atmospheric air and fuel such that the temperature of the combustion gas is between 1250° C. and 1500° C., preferably close to 1350° C. and in the downstream zone, the heating of the metal strip is achieved by combustion of a superoxygenated substoichiometric mixture of air and fuel such that the temperature of the combustion gas achieved at the end of the upstream zone is maintained until the end of the downstream zone of the direct flame heating section.

Abstract: A method for guaranteeing the oxidation of a strip designed to prevent the selective oxidation of alloy elements of the steel in a continuous steel strip galvanizing annealing furnace having a pre-heating section and a hold section and provided only with radiant tubes. The oxidation of the strip is designed to prevent the selective oxidation of elements of the steel alloy. The novel method includes the following steps: installation of at least one modified tube capable of injection an oxidizing medium at least one point in the oven heating section and/or at least one point in the hold section and injection of the oxidizing medium by means of the modified tube(s), the oxidizing medium having a composition such that in the conditions of the temperature of the oxidizing medium and the steel strip and as a function of the chemical composition of the strip said medium has a dew point which guarantees an in-depth oxidation of the alloy elements of the steel strip.