DUAL MODE REGENERATIVE BURNER SYSTEM AND A METHOD OF HEATING A FURNACE USING A DUAL MODE REGENERATIVE BURNER SYSTEM

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This patent claims priority to United States Provisional Patent Application No. 62/458,253, filed February 13, 2017 entitled "Dual Mode Regenerative Burner System and a Method of Heating a Furnace Using a Dual Mode Regenerative Burner System".

BACKGROUND OF THE INVENTION

Field of the Invention

[0002] This invention relates to a system for and a method of heating a furnace using a dual mode regenerative burner system, and more specifically, a method of heating a furnace wherein the fuel may be changed from a low calorific fuel to a high calorific fuel and a regenerative media bed within the burners used to heat the furnace may be used to heat either the low calorific fuel or combustion air.

Description of Related Art

[0003] Prior art regenerative burner systems utilize two burner assemblies, each having a burner and one or two regenerative media beds.

[0004] In regenerative burner systems having a single regenerative bed for each burner assembly, either the fuel or the oxidizing gas can be preheated. When the oxidizing gas is preheated, it is necessary to utilize high calorific fuel in order to achieve high efficiency of the burner. When the fuel is preheated, it is necessary to utilize low calorific fuel as high calorific fuel will clog the regenerative media bed.

[0005] Regenerative burner systems having two regenerative beds for each burner assembly are specifically designed for use with low calorific fuels in order to increase the efficiency of the burner.

[0006] European Patent Application Publication No. EP 2071236 A2 discloses a pair of regenerative burners heating an industrial furnace. The heat of the flue gas leaving the furnace is stored in a heat buffer and regenerated by the combustion air. A lance supplying an additional oxidant having an oxygen content of at least 80% is additionally provided. The lance is arranged in the hot oxidant duct.

[0007] Therefore, there is a need for a regenerative burner system capable of efficiently switching between high calorific fuel and low calorific fuel while also providing means to preheat the fuel or the oxidizing gas as needed depending on the fuel that is used and a reduction in the size of the regenerative burner system as compared to the prior art systems having a total of four regenerative media beds so that the regenerative burner system occupies less space upon installation.

SUMMARY OF THE INVENTION

[0008] The present invention is directed to a method of heating a furnace using a regenerative burner system, wherein the regenerative burner system comprises a first burner assembly and a second burner assembly, each burner assembly comprising a burner and a regenerative media bed. The first burner assembly is operated in a firing mode and the second burner assembly is operated in a regeneration mode for a first period of time. The operation of the first burner assembly is switched from the firing mode to the regeneration mode, and the operation of the second burner assembly is switched from the regeneration mode to the firing mode. The second burner assembly is operated in the firing mode, and the first burner assembly is operated in the regeneration mode for a second period of time. The burner assembly in the firing mode may be fired in either a first operating mode or a second operating mode. The first operating mode comprises supplying the burner with low calorific fuel that has been preheated in the regenerative media bed and supplying the burner directly with oxidizing gas, and the second operating mode comprises supplying the burner with oxidizing gas that has been preheated in the regenerative media bed and supplying the burner directly with high calorific fuel. The burner assembly in the regeneration mode may function as a flue such that the regenerative media bed is heated by products of combustion exhaust flowing from the first burner assembly.

[0009] The high calorific fuel may be a hydrocarbon-bearing fuel subject to thermal decomposition reactions that generate free carbon and may be a gaseous fuel having a heating value of 5.9-118.1 MJ/Nm³ (150-3,000 BTU/scf) or an oil having a heating value of 23.3-46.5 MJ/kg (10,000 to 20,000 BTU/pound), for example, natural gas, coke gas, oil, and mixed coke/blast furnace gas.

[0010] The low calorific fuel may have a heating value of 2.9-3.9 MJ/Nm³ (75-100 BTU/scf), for example, an off gas from a blast furnace or a similar process.

[0011] In the first operating mode, the oxidizing gas may be preheated prior to being supplied to the burner and/or supplemental high calorific fuel may be supplied to the burner.

[0012] In the second operating mode, the high calorific fuel may be preheated prior to being supplied to the burner and/or supplemental oxidizing gas that has not passed through the regenerative media bed is supplied to the burner for nozzle cooling.

[0013] The present invention is also directed to a regenerative burner system for a furnace comprising a first burner assembly and a second burner assembly each comprising a burner and a regenerative media bed, an oxidizing gas supply, a low calorific fuel supply, a high calorific fuel supply, an inlet for exhaust gases from the furnace, and an outlet for exhaust gases that have passed through the regenerative media bed. The regenerative bed of each burner assembly can be supplied with oxidizing gas or low calorific fuel, and the burner of each burner assembly can be directly supplied with oxidizing gas and/or a high calorific fuel.

[0014] Each of the burner assemblies can be operated in a firing mode where fuel and oxidizing gas flow into the burner assembly and in a regeneration mode where combustion gases from the furnace flow into the burner assembly and through the regeneration bed. When the first burner assembly is in the firing mode, the second burner assembly is in the regeneration mode, and when the first burner assembly is in the regeneration mode, the second burner assembly is in the firing mode. The burner assembly in the firing mode may be operated in a first operating mode in which fuel is supplied to the regenerative bed and oxidizing gas is supplied to the burner or in a second operating mode in which oxidizing gas is supplied to the regenerative bed and fuel is supplied to the burner. In the first operating mode, the fuel is supplied from the low calorific fuel supply and, in the second operating mode, the fuel is supplied by the high calorific fuel supply.

[0015] The regenerative burner system may further comprise a preheater for the oxidizing gas supply such that, in the first operating mode, the oxidizing gas is preheated prior to being supplied to the burner and/or a preheater for the high calorific fuel supply, such that, in the second operating mode, the high calorific fuel is preheated prior to being supplied to the burner.

[0016] In the first operating mode, supplemental high calorific fuel may be supplied to the burner, and in the second operating mode, supplemental oxidizing gas that has not passed through the regenerative media bed may be supplied to the burner for nozzle cooling.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 

FIG. 1 is a schematic showing the apparatus and method according to the invention when the first burner is in firing mode and the second burner is in regeneration mode;

FIG. 2 is a schematic showing the apparatus and method according to the invention when the first burner is in a first firing mode using low calorific fuel and the second burner is in regeneration mode;

FIG. 3 is a schematic showing the apparatus and method according to the invention when the first burner is in a second firing mode using high calorific fuel and the second burner is in regeneration mode;

FIG. 4 is a schematic showing the apparatus and method according to the invention when the first burner is in regeneration mode and the second burner is in firing mode;

FIG. 5 is a schematic showing the apparatus and method according to the invention when the second burner is in a first firing mode using low calorific fuel and the first burner is in regeneration mode; and

FIG. 6 is a schematic showing the apparatus and method according to the invention when the second burner is in a second firing mode using high calorific fuel and the first burner is in regeneration mode.

DESCRIPTION OF THE INVENTION

[0018] It is to be understood that the invention described herein may assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments or aspects of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments or aspects disclosed herein are not to be considered as limiting. As used herein, any numerical values are expressed using a period as a decimal point and a comma as a thousand separator, for example, 1,234 would be one thousand two hundred thirty four, and 1.2 would be one and two tenths. Unless otherwise expressly specified, all numbers such as those expressing values, ranges, amounts or percentages may be read as if prefaced by the word "about", even if the term does not expressly appear. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include any and all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10, that is, all subranges beginning with a minimum value equal to or greater than 1 and ending with a maximum value equal to or less than 10, and all subranges in between, e.g., 1 to 6.3, or 5.5 to 10, or 2.7 to 6.1. Plural encompasses singular and vice versa. When ranges are given, any endpoints of those ranges and/or numbers within those ranges can be combined with the scope of the present invention. "Including", "such as", "for example" and like terms means "including/such as/for example but not limited to".

[0019] The present invention is directed to a method of heating a furnace, for example, a reheat furnace, using a regenerative burner system that may be operated in two modes, one using a high calorific fuel and one using a low calorific fuel.

[0020] A regenerative combustion burner system comprising a first burner 10A coupled to a first regenerative media bed 12A and a second burner 10B coupled to a second regenerative media bed 12B is provided. Each burner 10A, 10B is cycled between a firing mode and a regeneration mode. When the first burner 10A is firing, the second burner 10B functions as a flue, and the second regenerative media bed 12B collects heat from the products of combustion exhaust (arrow E) flowing from the first burner 10A. After the regenerative media in the second regenerative media bed 12B has been heated by the exhaust flowing from the first burner 10A, the burners 10A, 10B are cycled such that the second burner 10B is placed in the firing mode, the first burner 10A functions as a flue, and the first regenerative media bed 12A collects heat from the products of combustion exhaust (arrow E) flowing from the second burner 10B. At the same time, one of the necessary gases for combustion, fuel or combustion air, passes through the heated second regenerative media bed 12B where the gas is preheated before entering the second burner 10B. When the collected heat in the second regenerative media bed 12B has been depleted and the first regenerative media bed 12A has been sufficiently heated, the burners 10A, 10B are cycled again such that the first burner 10A is placed in the firing mode, the second burner 10B functions as a flue, and the second regenerative media bed 12B collects heat from products of combustion exhaust (arrow E) flowing from the first burner 10A. At this time, one of the necessary gases for combustion, fuel or combustion air, passes through the heated first regenerative media bed 12A where the gas is preheated before entering the first burner 10A. The burners 10A, 10B continue to be cycled in this manner while heating the furnace.

[0021] The fuel supplied to the burners 10A, 10B may be high calorific fuel or may be low calorific fuel. High calorific fuels are hydrocarbon-bearing fuels that are subject to thermal decomposition reactions which generate free carbon. The decomposition of these high calorific fuels having high concentrations of methane and/or higher order hydrocarbons may begin at temperatures as low as 500°C (932°F) (Younessi-Sinaki et al., "Kinetic model of homogeneous thermal decomposition of methane and ethane", International Journal of Hydrogen Energy, Vol. 34, pp. 3710-3716, 2009). Since the free carbon created during decomposition tends to clog regenerative media beds, these high calorific fuels are not suitable for regenerative heating. Heating values of such industrial high calorific fuels would typically be 5.9-118.1 MJ/Nm³ (150-3,000 BTU/scf) for gaseous fuels and 23.3-46.5 MJ/kg (10,000-20,000 BTU/pound) for oils. Constituents of high calorific fuels include hydrocarbon compounds in the range of about 5-100%, with hydrogen and carbon monoxide representing possible additional combustible compounds, and the balance inert gases, such as carbon dioxide, nitrogen, and water vapor. Such high calorific fuels include natural gas, coke gas, oil, or mixed coke/blast furnace gas.

[0022] Low calorific fuels have typical heating values of 2.9-5.5 MJ/Nm³ (75-140 BTU/scf), for example, 1.8-3.9 MJ/Nm³ (45-100 BTU/scf). Primary constituents of low calorific fuels include hydrogen, carbon monoxide, carbon dioxide, and nitrogen, and water vapor. Low calorific fuels may also include hydrocarbons, for example, methane, and oxygen in trace amounts (less than about 3%). Such low calorific fuels may include off gas from a blast furnace or similar process and producer gas produced by carburetting air or other gases without pyrolysis through processes such as fixed-bed gasification of lump fuel, gasification of granular or pulverulent fuels in suspension, gasification using molten salts or metals, carburetting by pyrolysis of carbonaceous material in a fuel bed and carburetting by pyrolysis of carbonaceous material in a carburetor.

[0023] In order to increase the efficiency of the burners 10A, 10B when using low calorific fuel, the fuel can be preheated prior to entering the burners 10A, 10B. In order to increase the efficiency of the burners 10A, 10B when using high calorific fuel, the combustion air can be preheated prior to entering the burners 10A, 10B.

[0024] The inventive method allows for the operation of the regenerative burner system in two different modes. In the first mode, in which low calorific fuel is used, the low calorific fuel is regeneratively preheated. In the second mode in which high calorific fuel is used, combustion air is regeneratively preheated. In this manner, the inventive method efficiently utilizes a single-bed regenerative burner system with both low calorific fuel and high calorific fuel. In the first mode, the combustion efficiency is maximized by regeneratively preheating the low calorific fuel, which has a larger mass flow than the required combustion air. In the second mode, the combustion efficiency is maximized by utilizing the regenerators to preheat the combustion air.

[0025] In the first mode, low calorific fuel preheated in the regenerative media bed and combustion air are provided directly to the burner. In the second mode, combustion air preheated in the regenerative media bed and high calorific fuel are provided to the burner. This method has several advantages. Based on availability, the lowest cost fuel can be efficiently used in the same burner system. Both high calorific fuels, which cannot be heated in a regenerative media bed, and low calorific fuels, which require preheating for higher efficiency, can be used in the same regenerative combustion burner system. High fuel efficiency can be achieved regardless of the fuel that is used by using the regenerative media bed for preheating at least one of the supply gases in each mode. Only a single regenerative media bed is needed for each burner, whereas prior art double regeneration systems utilized two regenerative media beds for each burner, one for fuel and one for combustion air. This allows the burner system to be installed in smaller spaces. All of these advantages result in increased versatility and substantial cost savings over prior art double regeneration systems.

[0026] FIGS. 1-3 show the inventive method and system when the first burner 10A is in the firing cycle and the second burner 10B is in the regeneration cycle. As shown generally in FIG. 1 and more specifically in FIG. 2, in the first mode, a low calorific fuel, for example, blast furnace gas, flows through the first regenerative media bed 12A and into the first burner 10A and combustion air is supplied directly to the first burner 10A. The products of combustion exhaust (arrow E) flow through the furnace 14, through the second burner 10B, through the second regenerative media bed 12B, and are exhausted with an exhaust fan 16 or other suitable device.

[0027] As can been seen in FIG. 2, the control valve 18 between the first regenerative media bed 12A and the first supply line 20 supplying combustion air and/or fuel to the first regenerative media bed 12A is open and the control valve 22 between the second regenerative media bed 12B and the second supply line 24 supplying combustion air and/or fuel to the second regenerative media bed 12B is closed.

[0028] The control valve 26 between the combustion air supply 30 and the first supply line 20 and the second supply line 24 is closed. The control valve 32 between the combustion air supply 30 and the first burner 10A is open, and the control valve 34 between the combustion air supply 30 and the second burner 10B is closed. As a result, combustion air is supplied directly to the first burner 10A. The combustion air may be preheated in a recuperator or another preheating device prior to entering the first burner 10A. The combustion air may be supplied at a pressure of 13.8-68.9 mbar (0.2-1.0 psig), for example, 34.4 mbar (0.5 psig), and at a temperature of 371-538°C (700-1000°F). No combustion air is supplied to the second burner 10B.

[0029] The control valve 36 between the low calorific fuel supply LCF and the first supply line 20 and the second supply line 24 is open. As a result of the positioning of the control valves 18, 22, 36 between the low calorific fuel supply LCF, the first regenerative media bed 12A, and the second regenerative media bed 12B, low calorific fuel flows through the first regenerative media bed 12A where the fuel is preheated and then into the first burner 10A. The low calorific fuel may be supplied at a pressure of 13.8-68.9 mbar (0.2-1.0 psig), for example, 34.4 mbar (0.5 psig), and at a temperature of 21-52°C (70-125°F), for example, 38°C (100°F). No low calorific fuel is supplied to the second regenerative media bed 12B or the second burner 10B.

[0030] Control valves 38, 40 between the high calorific fuel supply HCF and the first burner 10A and between the high calorific fuel supply HCF and the second burner 10B are closed. As a result, no high calorific fuel is supplied to either of the burners 10A, 10B.

[0031] The control valve 42 between the first regenerative media bed 12A and the exhaust fan 16 is closed, and the control valve 44 between the second regenerative media bed 12B and the exhaust fan 16 is open. Typically, 50-60% of the products of combustion exhaust is exhausted through the exhaust fan 16.

[0032] In an alternative embodiment, the control valve 38 between the high calorific fuel supply HCF and the first burner 10A may be opened to supply supplemental fuel to the first burner 10A.

[0033] As shown generally in FIG. 1 and more specifically in FIG. 3, in the second mode, combustion air flows through the first regenerative media bed 12A and into the first burner 10A and high calorific fuel is supplied directly to the first burner 10A. The high calorific fuel may be preheated prior to entering the first burner 10A. The products of combustion exhaust (arrow E) flow through the furnace 14, through the second burner 10B, through the second regenerative media bed 12B, and are exhausted with an exhaust fan 16 or other suitable device.

[0034] As can been seen in FIG. 3, the control valve 18 between the first regenerative media bed 12A and the first supply line 20 supplying combustion air and/or fuel to the first regenerative media bed 12A is open and the control valve 22 between the second regenerative media bed 12B and the second supply line 24 supplying combustion air and/or fuel to the second regenerative media bed 12B is closed.

[0035] The control valve 26 between the combustion air supply 30 and the first supply line 20 and the second supply line 24 is open. The control valves 32, 34 between the combustion air supply 30 and the first burner 10A and between the combustion air supply 30 and the second burner 10B are closed. As a result of the positioning of the control valves 18, 22, 26 between the combustion air supply 30, the first regenerative media bed 12A, and the second regenerative media bed 12B, combustion air is supplied to the first regenerative media bed 12A where the combustion air is preheated and then into the first burner 10A. No combustion air is supplied to the second regenerative media bed 12B or the second burner 10B.

[0036] The control valve 36 between the low calorific fuel supply LCF and the first supply line 20 and the second supply line 24 is closed. As a result, no low calorific fuel is supplied to either of the regenerative media beds 12A, 12B or the burners 10A, 10B.

[0037] The control valve 38 between the high calorific fuel supply HCF and the first burner 10A is open, and the control valve 40 between the high calorific fuel supply HCF and the second burner 10B is closed. As a result, high calorific fuel is supplied to the first burner 10A. No high calorific fuel is supplied to the second burner 10B.

[0038] In an alternative embodiment, the control valve 32 between the combustion air supply 30 and the first burner 10A may be opened to supply air for nozzle cooling.

[0039] FIGS. 4-6 show the inventive method and system when the second burner 10B is in the firing cycle and the first burner 10A is in the regeneration cycle. As shown generally in FIG. 4 and more specifically in FIG. 5, in the first mode, a low calorific fuel, for example, blast furnace gas, flows through the second regenerative media bed 12B and into the second burner 10B and combustion air is supplied directly to the second burner 10B. The combustion air may be preheated in a recuperator or another preheating device prior to entering the second burner 10B. The products of combustion exhaust (arrow E) flow through the furnace 14, through the first burner 10A, through the first regenerative media bed 12A, and are exhausted with an exhaust fan 16 or other suitable device.

[0040] As can been seen in FIG. 5, the control valve 18 between the first regenerative media bed 12A and the first supply line 20 supplying combustion air and/or fuel to the first regenerative media bed 12A is closed and the control valve 22 between the second regenerative media bed 12B and the second supply line 24 supplying combustion air and/or fuel to the second regenerative media bed 12B is open.

[0041] The control valve 26 between the combustion air supply 30 and the first supply line 20 and the second supply line 24 is closed. The control valve 32 between the combustion air supply 30 and the first burner 10A is closed, and the control valve 34 between the combustion air supply 30 and the second burner 10B is open. As a result, combustion air is supplied directly to the second burner 10B. The combustion air may be supplied at a pressure of 13.8-68.9 mbar (0.2-1.0 psig), for example, 34.5 mbar (0.5 psig), and at a temperature of 371-538°C (700-1000°F). No combustion air is supplied to the first burner 10A.

[0042] The control valve 36 between the low calorific fuel supply LCF and the first supply line 20 and the second supply line 24 is open. As a result of the positioning of the control valves 18, 22, 36 between the low calorific fuel supply LCF, the first regenerative media bed 12A, and the second regenerative media bed 12B, low calorific fuel flows through the second regenerative media bed 12B where the fuel is preheated and then into the second burner 10B. The low calorific fuel may be supplied at a pressure of 13.8-68.9 mbar (0.2-1.0 psig), for example, 34.4 mbar (0.5 psig), and at a temperature of 24 to 52°C (75 - 125 °F), for example, 37.8°C (100°F). No low calorific fuel is supplied to the first regenerative media bed 12A or the first burner 10A.

[0043] Control valves 38, 40 between the high calorific fuel supply HCF and the first burner 10A and between the high calorific fuel supply HCF and the second burner 10B are closed. As a result, no high calorific fuel is supplied to either of the burners 10A, 10B.

[0044] The control valve 42 between the first regenerative media bed 12A and the exhaust fan 16 is open, and the control valve 44 between the second regenerative media bed 12B and the exhaust fan 16 is closed.

[0045] In an alternative embodiment, the control valve 40 between the high calorific fuel supply HCF and the second burner 10B may be opened to supply supplemental fuel to the second burner 10B.

[0046] As shown generally in FIG. 4 and more specifically in FIG. 6, in the second mode, combustion air flows through the second regenerative media bed 12B and into the second burner 10B and high calorific fuel is supplied directly to the second burner 10B. The high calorific fuel may be preheated prior to entering the second burner 10B. The products of combustion exhaust (arrow E) flow through the furnace 14, through the first burner 10A, through the first regenerative media bed 12A, and are exhausted with an exhaust fan 16 or other suitable device.

[0047] As can been seen in FIG. 6, the control valve 18 between the first regenerative media bed 12A and the first supply line 20 supplying combustion air and/or fuel to the first regenerative media bed 12A is closed and the control valve 22 between the second regenerative media bed 12B and the second supply line 24 supplying combustion air and/or fuel to the second regenerative media bed 12B is open.

[0048] The control valve 26 between the combustion air supply 30 and the first supply line 20 and the second supply line 24 is open. The control valves 32, 34 between the combustion air supply 30 and the first burner 10A and between the combustion air supply 30 and the second burner 10B are closed. As a result of the positioning of the control valves 18, 22, 26 between the combustion air supply 30, the first regenerative media bed 12A, and the second regenerative media bed 12B, combustion air is supplied to the second regenerative media bed 12B where the combustion air is preheated and then into the second burner 10B. No combustion air is supplied to the first regenerative media bed 12A or the first burner 10A.

[0049] The control valve 36 between the low calorific fuel supply LCF and the first supply line 20 and the second supply line 24 is closed. As a result, no low calorific fuel is supplied to either of the regenerative media beds 12A, 12B or the burners 10A, 10B.

[0050] The control valve 38 between the high calorific fuel supply HCF and the first burner 10A is closed, and the control valve 40 between the high calorific fuel supply HCF and the second burner 10B is open. As a result, high calorific fuel is supplied to the second burner 10B. No high calorific fuel is supplied to the first burner 10A.

[0051] In an alternative embodiment, the control valve 34 between the combustion air supply 30 and the second burner 10B may be opened to supply air for nozzle cooling.

[0052] While the inventive method has been discussed herein as using combustion air, any suitable oxidizing gas may be used, for example, oxygen. In addition, the specific valving shown in the figures and described herein may be adapted in any way as long as the described flow paths for the fuels and the combustion air are maintained.

Claims

1. A method of heating a furnace (14) using a regenerative burner system, wherein the regenerative burner system comprises a first burner assembly and a second burner assembly, each burner assembly comprising a burner (10A,10B) and a regenerative media bed (12A,12B), the method comprising:

operating the first burner assembly in a firing mode and the second burner assembly in a regeneration mode for a first period of time;

switching the operation of the first burner assembly from the firing mode to the regeneration mode and switching the operation of the second burner assembly from the regeneration mode to the firing mode; and

operating the second burner assembly in the firing mode and the first burner assembly in the regeneration mode for a second period of time,
characterized in that

the burner assembly in the firing mode is fired in either a first operating mode or a second operating mode,

the first operating mode comprising supplying the burner (10A,10B) with low calorific fuel that has been preheated in the regenerative media bed (12A,12B) and

supplying the burner (10A,10B) directly with oxidizing gas, and

the second operating mode comprising supplying the burner (10A,10B) with oxidizing gas that has been preheated in the regenerative media bed (12A,12B) and supplying the burner (10A,10B) directly with high calorific fuel,

thereby utilizing the first burner assembly and the second burner assembly with both low calorific fuel and high calorific fuel.

2. The method of claim 1, wherein the burner assembly in the regeneration mode functions as a flue such that the regenerative media bed (12A,12B) is heated by products of combustion exhaust flowing from the first burner assembly.

3. The method of claim 1, wherein the high calorific fuel is a hydrocarbon-bearing fuel subject to thermal decomposition reactions that generate free carbon.

4. The method of claim 1, wherein the high calorific fuel is a gaseous fuel having a heating value of 5,589 to 111,777 kJ/Nm3 (150 to 3000 BTU/scf) or an oil having a heating value of 23,260 to 46,520 kJ/kg (10,000 to 20,000 BTU/pound).

5. The method according to claim 1, wherein the high calorific fuel is one or more selected from the group consisting of natural gas, coke gas, oil, and mixed coke/blast furnace gas.

6. The method of claim 1, wherein the low calorific fuel has a heating value of 2,794 to 3,726 kJ/Nm3 (75-100 BTU/scf), or wherein the low calorific fuel is an off gas from a blast furnace or a similar process.

7. The method according to claim 1, wherein in the first operating mode, the oxidizing gas is preheated prior to being supplied to the burner (10A,10B).

8. The method according to claim 1, wherein in the first operating mode, supplemental high calorific fuel is supplied to the burner (10A,10B).

9. The method according to claim 1, wherein in the second operating mode, the high calorific fuel is preheated prior to being supplied to the burner (10A,10B), or wherein in the second operating mode, supplemental oxidizing gas that has not passed through the regenerative media bed (12A,12B) is supplied to the burner (10A,10B) for nozzle cooling.

10. A regenerative burner system for a furnace (14) comprising:

a first burner assembly and a second burner assembly each comprising a burner (10A,10B) and a regenerative media bed (12A,12B), an oxidizing gas supply, a low calorific fuel supply, a high calorific fuel supply, an inlet for exhaust gases from the furnace (14), and an outlet for exhaust gases that have passed through the regenerative media bed (12A,12B),

wherein the regenerative media bed (12A,12B) of each burner assembly can be supplied with oxidizing gas or low calorific fuel, and the burner (10A,10B) of each burner assembly can be directly supplied with oxidizing gas and/or a high calorific fuel.

11. The regenerative burner system of claim 10, wherein each of the burner assemblies can be operated in a firing mode where fuel and oxidizing gas flow into the burner assembly and in a regeneration mode where combustion gases from the furnace (14) flow into the burner assembly and through the regenerative media bed (12A,12B).

12. The regenerative burner system of claim 10, wherein, when the first burner assembly is in the firing mode, the second burner assembly is in the regeneration mode, and when the first burner assembly is in the regeneration mode, the second burner assembly is in the firing mode.

13. The regenerative burner system of claim 12, wherein the burner assembly in the firing mode can be operated in a first operating mode in which fuel is supplied to the regenerative media bed (12A,12B) and oxidizing gas is supplied to the burner (10A,10B) or in a second operating mode in which oxidizing gas is supplied to the regenerative media bed (12A,12B) and fuel is supplied to the burner (10A,10B).

14. The regenerative burner system of claim 13, wherein either:

- in the first operating mode, the fuel is supplied from the low calorific fuel supply and, in the second operating mode, the fuel is supplied by the high calorific fuel supply, or

- in the first operating mode, supplemental high calorific fuel is supplied to the burner (10A,10B), or

- in the second operating mode, supplemental oxidizing gas that has not passed through the regenerative media bed (12A,12B) is supplied to the burner (10A,10B) for nozzle cooling.

15. The regenerative burner system of claim 13, further comprising either:

- a preheater for the oxidizing gas supply such that, in the first operating mode, the oxidizing gas is preheated prior to being supplied to the burner (10A,10B), or

- a preheater for the high calorific fuel supply, such that, in the second operating mode, the high calorific fuel is preheated prior to being supplied to the burner (10A,10B).

Ansprüche

1. Verfahren zum Heizen eines Ofens (14) unter Verwendung eines regenerativen Brennersystems, wobei das regenerative Brennersystem eine erste Brenneranordnung und eine zweite Brenneranordnung umfasst, wobei jede Brenneranordnung einen Brenner (10A, 10B) und ein regeneratives Medienbett (12A, 12B) umfasst, wobei das Verfahren umfasst:

Betreiben der ersten Brenneranordnung in einem Feuerungsmodus und der zweiten Brenneranordnung in einem Regenerationsmodus für eine erste Zeitdauer;

Umschalten des Betriebs der ersten Brenneranordnung von dem Feuerungsmodus in den Regenerationsmodus und Umschalten des Betriebs der zweiten Brenneranordnung von dem Regenerationsmodus in den Feuerungsmodus; und

Betreiben der zweiten Brenneranordnung in dem Feuerungsmodus und der ersten Brenneranordnung in dem Regenerationsmodus für eine zweite Zeitdauer,

dadurch gekennzeichnet, dass

die Brenneranordnung in dem Feuerungsmodus in entweder einem ersten Betriebsmodus oder einem zweiten Betriebsmodus befeuert wird,

der erste Betriebsmodus Zuführen von niederkalorischem Brennstoff, der in dem regenerativen Medienbett (12A, 12B) vorgeheizt wurde, zu dem Brenner (10A, 10B) und Zuführen von Oxidationsgas direkt zu dem Brenner (10A, 10B) umfasst, und

der zweite Betriebsmodus Zuführen von Oxidationsgas, das in dem regenerativen Medienbett (12A, 12B) vorgeheizt wurde, zu dem Brenner (10A, 10B) und Zuführen von hochkalorischem Brennstoff direkt zu dem Brenner (10A, 10B) umfasst,

wobei dadurch die erste Brenneranordnung und die zweite Brenneranordnung mit sowohl niederkalorischem Brennstoff als auch hochkalorischem Brennstoff genutzt werden.

2. Verfahren nach Anspruch 1, wobei die Brenneranordnung in dem Regenerationsmodus als ein Rauchabzug derart dient, dass das regenerative Medienbett (12A, 12B) durch Produkte von Verbrennungsabgas erhitzt wird, das von der ersten Brenneranordnung strömt.

3. Verfahren nach Anspruch 1, wobei der hochkalorische Brennstoff ein kohlenwasserstoffhaltiger Brennstoff ist, der thermischen Zersetzungsreaktionen unterzogen wird, die freien Kohlenstoff erzeugen.

4. Verfahren nach Anspruch 1, wobei der hochkalorische Brennstoff ein gasförmiger Brennstoff, der einen Heizwert von 5.589 bis 111.777 kJ/Nm3 (150 bis 3.000 BTU/scf) aufweist, oder ein Öl, das einen Heizwert von 23.260 bis 46.520 kJ/kg (10.000 bis 20.000 BTU/Britisches Pfund) aufweist, ist.

5. Verfahren nach Anspruch 1, wobei der hochkalorische Brennstoff eines oder mehrere ist, die ausgewählt sind aus der Gruppe bestehend aus Naturgas, Koksgas, Öl und Koks-/Gichtgasgemisch.

6. Verfahren nach Anspruch 1, wobei der niederkalorische Brennstoff einen Heizwert von 2.794 bis 3.726 kJ/Nm3 (75-100 BTU/scf) aufweist, oder wobei der niederkalorische Brennstoff ein Abgas aus einem Hochofen oder einem ähnlichen Prozess ist.

7. Verfahren nach Anspruch 1, wobei in dem ersten Betriebsmodus das Oxidationsgas vorgeheizt wird, bevor es dem Brenner (10A, 10B) zugeführt wird.

8. Verfahren nach Anspruch 1, wobei in dem ersten Betriebsmodus ein ergänzender hochkalorischer Brennstoff dem Brenner (10A, 10B) zugeführt wird.

9. Verfahren nach Anspruch 1, wobei in dem zweiten Betriebsmodus der hochkalorische Brennstoff vorgeheizt wird, bevor er dem Brenner (10A, 10B) zugeführt wird, oder wobei in dem zweiten Betriebsmodus ein ergänzendes Oxidationsgas, das nicht durch das regenerative Medienbett (12A, 12B) passiert ist, dem Brenner (10A, 10B) zur Düsenkühlung zugeführt wird.

10. Regeneratives Brennersystem für einen Ofen (14), umfassend:

eine erste Brenneranordnung und eine zweite Brenneranordnung, die jeweils einen Brenner (10A, 10B) und ein regeneratives Medienbett (12A, 12B), eine Oxidationsgaszufuhr, eine niederkalorische Brennstoffzufuhr, eine hochkalorische Brennstoffzufuhr, einen Einlass für Abgase aus dem Ofen (14) und einen Auslass für Abgase, die durch das regenerative Medienbett (12A, 12B) passiert sind, umfasst,

wobei dem regenerativen Medienbett (12A, 12B) jeder Brenneranordnung Oxidationsgas oder niederkalorischer Brennstoff zugeführt werden kann, und dem Brenner (10A, 10B) jeder Brenneranordnung direkt Oxidationsgas und/oder hochkalorischer Brennstoff zugeführt werden kann.

11. Regeneratives Brennersystem nach Anspruch 10, wobei jede der Brenneranordnungen in einem Feuerungsmodus, in dem Brennstoff und Oxidationsgas in die Brenneranordnung strömen, und in einem Regenerationsmodus, in dem Verbrennungsgase aus dem Ofen (14) in die Brenneranordnung und durch das regenerative Medienbett (12A, 12B) strömen, betrieben werden kann.

12. Regeneratives Brennersystem nach Anspruch 10, wobei, wenn die erste Brenneranordnung in dem Feuerungsmodus ist, die zweite Brenneranordnung in dem Regenerationsmodus ist, und wenn die erste Brenneranordnung in dem Regenerationsmodus ist, die zweite Brenneranordnung in dem Feuerungsmodus ist.

13. Regeneratives Brennersystem nach Anspruch 12, wobei die Brenneranordnung in dem Feuerungsmodus in einem ersten Betriebsmodus, in dem Brennstoff dem regenerativen Medienbett (12A, 12B) zugeführt wird und Oxidationsgas dem Brenner (10A, 10B) zugeführt wird, oder in einem zweiten Betriebsmodus, in dem Oxidationsgas dem regenerativen Medienbett (12A, 12B) zugeführt wird und Brennstoff dem Brenner (10A, 10B) zugeführt wird, betrieben werden kann.

14. Regeneratives Brennersystem nach Anspruch 13, wobei entweder:

- in dem ersten Betriebsmodus der Brennstoff von der niederkalorischen Brennstoffzufuhr zugeführt wird und in dem zweiten Betriebsmodus der Brennstoff von der hochkalorischen Brennstoffzufuhr zugeführt wird, oder

- in dem ersten Betriebsmodus ein ergänzender hochkalorischer Brennstoff dem Brenner (10A, 10B) zugeführt wird, oder

- in dem zweiten Betriebsmodus ergänzendes Oxidationsgas, das nicht durch das regenerative Medienbett (12A, 12B) passiert ist, dem Brenner (10A, 10B) zur Düsenkühlung zugeführt wird.

15. Regeneratives Brennersystem nach Anspruch 13, ferner umfassend entweder:

- eine Vorheizung für die Oxidationsgaszufuhr, so dass in dem ersten Betriebsmodus das Oxidationsgas vorgeheizt wird, bevor es dem Brenner (10A, 10B) zugeführt wird, oder

- eine Vorheizung für die hochkalorische Brennstoffzufuhr, so dass in dem zweiten Betriebsmodus der hochkalorische Brennstoff vorgeheizt wird, bevor er dem Brenner (10A, 10B) zugeführt wird.

Revendications

1. Procédé de chauffage d'un fourneau (14) en utilisant un système brûleur régénératif, dans lequel le système brûleur régénératif comprend un premier ensemble brûleur et un second ensemble brûleur, chaque ensemble brûleur comprenant un brûleur (10A, 10B) et un lit de matériau régénératif (12A, 12B), le procédé comprenant :

la mise en fonctionnement du premier ensemble brûleur dans un mode d'allumage et du second ensemble brûleur dans un mode de régénération pendant une première période ;

la permutation du fonctionnement du premier ensemble brûleur du mode d'allumage au mode de régénération et la permutation du fonctionnement du second ensemble brûleur du mode de régénération au mode d'allumage ; et

la mise en fonctionnement du second ensemble brûleur dans le mode d'allumage et du premier ensemble brûleur dans le mode de régénération pendant une seconde période,

caractérisé en ce que

l'ensemble brûleur dans le mode d'allumage est allumé dans un premier mode de fonctionnement ou un second mode de fonctionnement,

le premier mode de fonctionnement comprenant l'alimentation du brûleur (10A, 10B) en un combustible à faible pouvoir calorifique qui a été préchauffé dans le lit de matériau régénératif (12A, 12B) et l'alimentation du brûleur (10A, 10B) directement en un gaz oxydant, et

le second mode de fonctionnement comprenant l'alimentation du brûleur (10A, 10B) en un gaz oxydant qui a été préchauffé dans le lit de matériau régénératif (12A, 12B) et l'alimentation du brûleur (10A, 10B) directement en un combustible à haut pouvoir calorifique,

ainsi l'utilisation du premier ensemble brûleur et du second ensemble brûleur avec le combustible à faible pouvoir calorifique ainsi qu'avec combustible à haut pouvoir calorifique.

2. Procédé selon la revendication 1, dans lequel l'ensemble brûleur dans le mode de régénération sert de carneau de telle sorte que le lit de matériau régénératif (12A, 12B) soit chauffé par des produits d'échappement de combustion s'écoulant à partir du premier ensemble brûleur.

3. Procédé selon la revendication 1, dans lequel le combustible à haut pouvoir calorifique est un combustible porteur d'hydrocarbures soumis à des réactions de décomposition thermique qui génèrent du carbone libre.

4. Procédé selon la revendication 1, dans lequel le combustible à haut pouvoir calorifique est un combustible gazeux ayant un pouvoir calorifique de 5589 à 111777 kJ/Nm3 (150 à 3000 BTU/scf) ou une huile ayant un pouvoir calorifique de 23260 à 46520 kJ/kg (10000 à 20000 BTU/livre).

5. Procédé selon la revendication 1, dans lequel le combustible à haut pouvoir calorifique est un ou plusieurs sélectionnés parmi le groupe constitué de gaz naturel, de gaz de coke, d'huile, et de gaz de coke/de haut fourneau mélangé.

6. Procédé selon la revendication 1, dans lequel le combustible à faible pouvoir calorifique a un pouvoir calorifique de 2794 à 3726 kJ/Nm3 (75-100 BTU/scf), ou dans lequel le combustible à faible pouvoir calorifique est un effluent gazeux provenant d'un haut fourneau ou d'un processus similaire.

7. Procédé selon la revendication 1, dans lequel, dans le premier mode de fonctionnement, le gaz oxydant est préchauffé avant d'être fourni au brûleur (10A, 10B).

8. Procédé selon la revendication 1, dans lequel, dans le premier mode de fonctionnement, un combustible supplémentaire à haut pouvoir calorifique est fourni au brûleur (10A, 10B).

9. Procédé selon la revendication 1, dans lequel, dans le second mode de fonctionnement, le combustible à haut pouvoir calorifique est préchauffé avant d'être fourni au brûleur (10A, 10B), ou dans lequel, dans le second mode de fonctionnement, un gaz oxydant supplémentaire qui n'est pas passé à travers le lit de matériau régénératif (12A, 12B) est fourni au brûleur (10A, 10B) pour refroidissement de tuyère.

10. Système brûleur régénératif pour un fourneau (14), comprenant :

un premier ensemble brûleur et un second ensemble brûleur, chacun comprenant un brûleur (10A, 10B) et un lit de matériau régénératif (12A, 12B), une alimentation en gaz oxydant, une alimentation en combustible à faible pouvoir calorifique, une alimentation en combustible à haut pouvoir calorifique, une entrée pour des gaz d'échappement provenant du fourneau (14), et une sortie pour des gaz d'échappement qui sont passés à travers le lit de matériau régénératif (12A, 12B),

dans lequel le lit de matériau régénératif (12A, 12B) de chaque ensemble brûleur peut être alimenté en gaz oxydant ou combustible à faible pouvoir calorifique, et le brûleur (10A, 10B) de chaque ensemble brûleur peut être directement alimenté en gaz oxydant et/ou un combustible à haut pouvoir calorifique.

11. Système brûleur régénératif selon la revendication 10, dans lequel chacun des ensembles brûleurs peut être mis en fonctionnement dans un mode d'allumage, où un combustible et un gaz oxydant s'écoulent dans l'ensemble brûleur, et dans un mode de régénération, où des gaz de combustion provenant du fourneau (14) s'écoulent dans l'ensemble brûleur et à travers le lit de matériau régénératif (12A, 12B).

12. Système brûleur régénératif selon la revendication 10, dans lequel, lorsque le premier ensemble brûleur est dans le mode d'allumage, le second ensemble brûleur est dans le mode de régénération, et, lorsque le premier ensemble brûleur est dans le mode de régénération, le second ensemble brûleur est dans le mode d'allumage.

13. Système brûleur régénératif selon la revendication 12, dans lequel l'ensemble brûleur dans le mode d'allumage peut être mis en fonctionnement dans un premier mode de fonctionnement, dans lequel un combustible est fourni au lit de matériau régénératif (12A, 12B) et un gaz oxydant est fourni au brûleur (10A, 10B), ou dans un second mode de fonctionnement, dans lequel un gaz oxydant est fourni au lit de matériau régénératif (12A, 12B) et un combustible est fourni au brûleur (10A, 10B).

14. Système brûleur régénératif selon la revendication 13, dans lequel :

- dans le premier mode de fonctionnement, le combustible est fourni depuis l'alimentation en combustible à faible pouvoir calorifique et, dans le second mode de fonctionnement, le combustible est fourni par l'alimentation en combustible à haut pouvoir calorifique, ou

- dans le premier mode de fonctionnement, un combustible supplémentaire à haut pouvoir calorifique est fourni au brûleur (10A, 10B), ou

- dans le second mode de fonctionnement, un gaz oxydant supplémentaire qui n'est pas passé à travers le lit de matériau régénératif (12A, 12B) est fourni au brûleur (10A, 10B) pour refroidissement de tuyère.

15. Système brûleur régénératif selon la revendication 13, comprenant en outre:

- un préchauffeur pour l'alimentation en gaz oxydant en telle sorte que, dans le premier mode de fonctionnement, le gaz oxydant soit préchauffé avant d'être fourni au brûleur (10A, 10B), ou

- un préchauffeur pour l'alimentation en combustible à haut pouvoir calorifique, de telle sorte que, dans le second mode de fonctionnement, le combustible à haut pouvoir calorifique soit préchauffé avant d'être fourni au brûleur (10A, 10B).

Drawing