Metal heating furnace, and method for combusting ammonia by using metal heating furnace

Abstract

OBJECT To provide a metal heating furnace that burns ammonia while decreasing nitrogen oxides efficiently and a method of burning ammonia in the metal heating furnace. MEANS OF REALIZING THE OBJECT A metal heating furnace 10 includes a burner nozzle 31, plural injection nozzles 41, 42, 43 for ammonia, and a controlling unit 100. The burner nozzle 31 is provided on a furnace wall 11 and emits flame F, which is used to burn ammonia. The injection nozzles 41, 42, 43 for ammonia are provided on a ceiling wall 13 at intervals in a direction in which the flame F extends, and are used to eject ammonia in a direction perpendicular to the flame F. The controlling unit 100 optimizes an amount of ammonia ejected from each of the injection nozzles 41, 42, 43 for ammonia.

Description

TECHNICAL FIELD

[0001] The present invention generally relates to a metal heating furnace that burns ammonia and a method of burning ammonia in the metal heating furnace.BACKGROUND ART

[0002] The recent trend toward prevention of global warming has drawn attention to ammonia as new fuel, which emits no carbon dioxide under combustion. Ammonia, when mixed with fossil fuel or burnt alone, is known to increase emission of nitrogen oxides (NO x ) (see, for example, Patent document 1).

[0003] A combustion device in Patent document 1 is designed to solve the problems related with increase in nitrogen oxides under the mixed combustion of coal with ammonia.

[0004] In this connection, Fig. 5 has a control means 23, a distribution means 25, plural distribution transport paths 26 as well as an ammonia supply means 22, which are provided outside a burner, and is not modified in the configuration of the burner. The ammonia supply means 22 supplies ammonia to an air-fuel mixture flow path body 21, which is provided inside the burner. The control means 23 controls supply of ammonia by referring to operating conditions. The distribution means 25 distributes ammonia supplied by the ammonia supply means 22 to the air-fuel mixture flow path body 21 and inlets 24 through the plural distribution transport paths 26, attached to the distribution means 25. The control means 23 controls the distribution status of ammonia in the distribution means 25.RELATED ART DOCUMENTSPATENT DOCUMENTS

[0005] Patent document 1: Japanese Patent No. 7020759DISCLOSURE OF THE INVENTIONPROBLEMS TO BE SOLVED BY THE INVENTION

[0006] The combustion burner in Patent document 1 includes the distribution means 25 and the plural distribution transport paths 26, attached to the distribution means 25, as well as the ammonia supply means 22, which supplies ammonia to the air-fuel mixture flow path body 21 inside the nozzle. Unfortunately, however, the position of the inlets 24 and the inflow of ammonia are unchangeable, and therefore, the combustion burner remains ineffective in decreasing nitrogen oxides efficiently.

[0007] To solve the above problems, it is an object of the present invention to provide a metal heating furnace that burns ammonia while decreasing nitrogen oxides efficiently and a method of burning ammonia in the metal heating furnace.MEANS OF SOLVING THE PROBLEMS

[0008] To achieve the above object, an aspect of the present invention provides a metal heating furnace (10). The metal heating furnace (10) includes a burner nozzle (31), plural injection nozzles (41, 42, 43) for ammonia, and a controlling unit (100).

[0009] The burner nozzle (31) is provided on a furnace wall (11). The burner nozzle (31) emits flame (F). The flame (F) is used to burn ammonia.

[0010] The injection nozzles (41, 42, 43) for ammonia are provided on a side wall (12) or a ceiling wall (13) at intervals in a direction in which the flame (F) extends. The injection nozzles (41, 42, 43) for ammonia are used to eject ammonia in a direction perpendicular to the flame (F).

[0011] The controlling unit (100) optimizes the amount of ammonia ejected from each of the injection nozzles (41, 42, 43) for ammonia.

[0012] In addition, according to an aspect of the present invention, ammonia is mixed with combustion air supplied to the burner nozzle (31).

[0013] In addition, according to an aspect of the present invention, the metal heating furnace (10) further includes a feeding nozzle (45) for ammonia. The feeding nozzle (45) for ammonia is provided on the furnace wall (11) and is parallel with the burner nozzle (31). The feeding nozzle (45) for ammonia is used to feed ammonia.

[0014] In addition, an aspect of the present invention provides a method of burning ammonia in a metal heating furnace (10). The metal heating furnace (10) includes a burner nozzle (31), plural injection nozzles (41, 42, 43) for ammonia, and a controlling unit (100).

[0015] The burner nozzle (31) is provided on a furnace wall (11). The burner nozzle (31) emits flame (F). The flame (F) is used to burn ammonia.

[0016] The injection nozzles (41, 42, 43) for ammonia are provided on a side wall (12) or a ceiling wall (13) at intervals in a direction in which the flame (F) extends. The injection nozzles (41, 42, 43) for ammonia are used to eject ammonia in a direction perpendicular to the flame (F).

[0017] The controlling unit (100) optimizes the amount of ammonia ejected from each of the injection nozzles (41, 42, 43) for ammonia.

[0018] The controlling unit (100) controls the amount of ammonia ejected from the plural injection nozzles (41, 42, 43) for ammonia in a manner to minimize nitrogen oxides relative to the size of the flame (F).

[0019] In addition, an aspect of the present invention provides a method of burning ammonia in a metal heating furnace (10). The metal heating furnace (10) includes a burner nozzle (31), plural injection nozzles (41, 42, 43) for ammonia, and a controlling unit (100).

[0020] The burner nozzle (31) is provided on a furnace wall (11). The burner nozzle (31) emits flame (F). The flame (F) is used to burn ammonia.

[0021] The injection nozzles (41, 42, 43) for ammonia are provided on a side wall (12) or a ceiling wall (13) at intervals in a direction in which the flame (F) extends. The injection nozzles (41, 42, 43) for ammonia are used to eject ammonia in a direction perpendicular to the flame (F).

[0022] The controlling unit (100) optimizes the amount of ammonia ejected from each of the injection nozzles (41, 42, 43) for ammonia.

[0023] The controlling unit (100) performs on / off control of ammonia ejected from the plural injection nozzles (41, 42, 43) for ammonia in a manner to minimize nitrogen oxides relative to the size of the flame (F).

[0024] In addition, according to an aspect of the present invention, the controlling unit (100) performs control by referring to an empirical data.

[0025] Symbols in parentheses show constituents or items corresponding to the drawings.Advantageous Effects of Invention

[0026] According to the present invention, the flame emitted by the burner nozzle, which is provided on the furnace wall, is used to burn ammonia. The plural injection nozzles for ammonia are provided on the side wall or the ceiling wall at intervals in the direction in which the flame extends. The injection nozzles for ammonia are used to eject ammonia in the direction perpendicular to the flame.

[0027] Traditional metal heating furnaces have the side wall or the ceiling wall at right angles to the furnace wall with the burner nozzle. The configuration, however, is not limited and the side wall or the ceiling wall may be curved, for example, not right-angled.

[0028] In addition, the controlling unit of the metal heating furnace optimizes the amount of ammonia ejected from each of the injection nozzles for ammonia. This simplifies variation in the amount of ammonia ejected from each of the injection nozzles for ammonia relative to the size of the flame.

[0029] In addition, according to the method of the invention of burning ammonia in the metal heating furnace, the controlling unit controls the amount of ammonia ejected from the plural injection nozzles for ammonia in a manner to minimize nitrogen oxides relative to the size of the flame. The amount of ammonia is controlled by, for example, using an on / off control, which switches on or off a solenoid valve, or a flow regulating valve, which optimizes ratio of valve opening continuously. The on / off control is easier to control and is lower in unevenness.

[0030] With this configuration, the reduction reaction of ammonia reduces nitrogen oxides generated by burner combustion. Also, injecting ammonia into a lower-oxygen furnace leads to thermal decomposition of part of the ammonia, enhances reduction effect for the effect of the resultant hydrogen gas, and keeps the nitrogen oxides generated by oxidation of the injected ammonia to a low concentration.

[0031] In addition, the controlling unit performs the control by referring to the empirical data. This enables a simple control to burn ammonia while minimizing nitrogen oxide.

[0032] In addition, ammonia is mixed with the combustion air supplied to the burner nozzle, or the metal heating furnace further includes the feeding nozzle for ammonia, which is parallel with the burner nozzle. This enables combustion of more amount of ammonia.BRIEF DESCRIPTION OF THE DRAWINGS

[0033] [Fig. 1] It is a sectional side view of the main components of a metal heating furnace according to an embodiment of the present invention. [Fig. 2] It is a block diagram of an electrical configuration of a controlling unit, which controls combustion of ammonia in the metal heating furnace illustrated in Fig. 1. [Fig. 3] It is a graph showing the relation between the position of plural injection nozzles for ammonia provided on the metal heating furnace according to an embodiment of the present invention and the amount of generated nitrogen oxides (NO x ). [Fig. 4] It is a sectional side view of the main components of a metal heating furnace according to another embodiment of the present invention. [Fig. 5] It is a schematic side view of a traditional metal heating furnace. MODE FOR CARRYING OUT THE INVENTION

[0034] Referring to Fig. 1 to Fig. 3, a metal heating furnace 10 according to an embodiment of the present invention will be described.

[0035] As illustrated in Fig. 1, the metal heating furnace 10 in this embodiment has a substantially rectangular-shaped cross section, and has a burner nozzle 31 provided on a furnace wall 11 on the left. The furnace wall 11 extends in an upper and lower direction. The burner nozzle 31 emits flame F, which is used to burn ammonia. The burner nozzle 31 extends horizontally to the right from the left on the furnace wall 11, and emits the flame F toward the right-side part inside the furnace.

[0036] Fossil fuel is supplied to the burner nozzle 31 through a control valve 32 alongside of open air for use as combustion air supplied by a blower 33.

[0037] The metal heating furnace 10 has three injection nozzles 41, 42, 43 for ammonia (first injection nozzle for ammonia, second injection nozzle for ammonia, third injection nozzle for ammonia) provided on a ceiling wall 13 at intervals (regular intervals in this embodiment) in the direction in which the flame F extends, that is from the left to the right in Fig. 1.

[0038] Ammonia is supplied to the injection nozzles 41, 42, 43 for ammonia through solenoid valves (first solenoid valve, second solenoid valve, third solenoid valve) 51, 52, 53, and is ejected into the furnace from the injection nozzles 41, 42, 43 for ammonia in the direction orthogonal to the direction in which the flame F extends, that is from an upper side part to the lower side part.

[0039] A flue 15 is provided on part of the ceiling wall 13 of the metal heating furnace 10 to discharge exhaust gas.

[0040] A controlling unit 100 controls the entire electrical system of the metal heating furnace 10 and opens or closes each of the solenoid valves 51, 52, 53.

[0041] As illustrated in Fig. 2, the controlling unit 100 includes a CPU 101 as a controller and a memory 102. The memory 102 includes a ROM, which stores a control program, and a RAM used for writing and retrieving data.

[0042] The CPU 101 is connected with an input unit 103, such as a key switch, and an output unit 104, such as a monitor or printer. In addition, the CPU 101 receives data input regarding the amount of fossil fuel and the amount of combustion air supplied to the burner nozzle 31. In addition, the CPU 101 is connected with a first solenoid driver 61, a second solenoid driver 62, and a third solenoid driver 63, which drive opening or closing of the first solenoid valve 51, the second solenoid valve 52, and the third solenoid valve 53, respectively, and outputs on / off signals.

[0043] The controlling unit 100 performs on / off control of the amount of ammonia ejected from the plural injection nozzles 41, 42, 43 for ammonia in a manner to minimize nitrogen oxides relative to the size of the flame F.

[0044] More specifically, the controlling unit 100 determines the flame F inside the furnace by referring to the amount of fossil fuel and the amount of combustion air. The controlling unit 100 retrieves details of the control suitable for the respective size of the flame F from an empirical data in the RAM of the memory 102, and performs the control by referring to the details.

[0045] For example, Fig. 3 shows the amount of emission of nitrogen oxides (NO x ) when ammonia is ejected from the injection nozzle 41 for ammonia (No1), the injection nozzle 42 for ammonia (No2), the injection nozzle 43 for ammonia (No3), the injection nozzles 41, 42, 43 for ammonia (No4), and the injection nozzles 41, 42 for ammonia (No5) with the flame F having the size illustrated in Fig. 1. The size is determined by the amount of fossil fuel and the amount of combustion air. The results show that the emission of nitrogen oxides (NO x ) is minimized when ammonia is ejected from the injection nozzle 43 for ammonia (No3).

[0046] The CPU 101, therefore, outputs a signal to turn off the first solenoid driver 61, turn off the second solenoid driver 62, and turn on the third solenoid driver 63, such that only the third solenoid valve 53 is opened, and ammonia is ejected solely from the injection nozzle 43 for ammonia.

[0047] The combination of the injection nozzles 41, 42, 43 for ammonia that minimizes the emission of nitrogen oxide (NOx) relative to the size of the flame F when ammonia is ejected from each of the injection nozzles 41, 42, 43 for ammonia is stored as patterned empirical data obtained through experimentation. The size of the flame F is determined by the amount of fossil fuel and the amount of combustion air.

[0048] The optimal combination of the injection nozzles 41, 42, 43 for ammonia suitable for minimizing the emission of nitrogen oxide relative to the size of the flame F, determined by the amount of fossil fuel and the amount of combustion air, is retrieved from previously patterned empirical data, and the solenoid valves 51, 52, 53 are controlled to open or close accordingly.

[0049] In this embodiment, ejecting ammonia from the injection nozzle 43 for ammonia is stored as patterned empirical data suitable for minimizing the emission of nitrogen oxide (NOx) relative to the size of the flame F illustrated in Fig. 1. Ram is used to store and retrieve patterned empirical data whenever necessary, that is which of the injection nozzles 41, 42, 43 for ammonia or which combination of at least two of the injection nozzles 41, 42, 43 for ammonia is suitable for minimizing the emission of nitrogen oxide (NOx) relative to respective size of the flame F.

[0050] The metal heating furnace 10 in this embodiment burns ammonia while minimizing nitrogen oxides.

[0051] With this configuration, the reduction reaction of ammonia reduces nitrogen oxides generated by burner combustion. Also, injecting ammonia into a lower-oxygen furnace leads to thermal decomposition of part of the ammonia, enhances reduction effect for the effect of the resultant hydrogen gas, and keeps the nitrogen oxides generated by oxidation of the injected ammonia to a low concentration.

[0052] Alternatively, ammonia may be mixed with the combustion air supplied to the burner nozzle 31, or as illustrated in Fig. 4, the metal heating furnace may further include a feeding nozzle 45 for ammonia, which is parallel with the burner nozzle 31. This enables combustion of more amount of ammonia. The feeding nozzle 45 for ammonia has an extra solenoid valve 46 attached.

[0053] In this embodiment, three injection nozzles 41, 42, 43 for ammonia are provided on the ceiling wall 13 at intervals in the direction in which the flame F extends. However, the number of injection nozzle for ammonia is not limited and a greater number of injection nozzles for ammonia may be provided. Alternatively, the injection nozzles 41, 42, 43 for ammonia may be provided on a side wall 12 (front or back of paper of Fig. 1), not the ceiling wall 13, of the metal heating furnace 10, to eject ammonia in the direction perpendicular to the flame F.

[0054] In this embodiment, the controlling unit 100 performs on / off control of ammonia ejected from the plural injection nozzles 41, 42, 43 for ammonia in a manner to minimize nitrogen oxides relative to the size of the flame F. Alternatively, flow regulating valves (illustration omitted) may substitute for the solenoid valves 51, 52, 53, to optimize ratio of valve opening continuously and perform control more precisely.

[0055] A combustion burner for ammonia discussed in this embodiment is applicable to various fields that burn ammonia (thermal power generation, for example).DESCRIPTION OF NUMERALS

[0056] 10metal heating furnace 11furnace wall 12side wall 13ceiling wall 20combustion burner for ammonia 21air-fuel mixture flow path body 22ammonia supply means 23control means 24inlet 25distribution means 26distribution transport path 31burner nozzle 41first injection nozzle for ammonia 42second injection nozzle for ammonia 43third injection nozzle for ammonia 45feeding nozzle for ammonia 46extra solenoid valve 51first solenoid valve 52second solenoid valve 53third solenoid valve 61first solenoid driver 62second solenoid driver 63third solenoid driver 100controlling unit 101CPU 102memory 103input unit 104output unit Fflame

Claims

1. A metal heating furnace comprising: a burner nozzle provided on a furnace wall, the burner nozzle being configured to emit flame, and the flame being configured to burn ammonia; plural injection nozzles for ammonia, the injection nozzles for ammonia being provided on a side wall or a ceiling wall at intervals in a direction in which the flame extends, and the injection nozzles for ammonia being configured to eject ammonia in a direction perpendicular to the flame; and a controlling unit configured to optimize an amount of ammonia ejected from each of the injection nozzles for ammonia.

2. The metal heating furnace as claimed in Claim 1, wherein ammonia is mixed with combustion air supplied to the burner nozzle.

3. The metal heating furnace as claimed in Claim 1 or Claim 2, further comprising: a feeding nozzle for ammonia, the feeding nozzle for ammonia being provided on the furnace wall, the feeding nozzle for ammonia being parallel with the burner nozzle, and the feeding nozzle for ammonia being configured to feed ammonia.

4. A method of burning ammonia in a metal heating furnace, the metal heating furnace comprising: a burner nozzle provided on a furnace wall, the burner nozzle being configured to emit flame, and the flame being configured to burn ammonia; plural injection nozzles for ammonia, the injection nozzles for ammonia being provided on a side wall or a ceiling wall at intervals in a direction in which the flame extends, and the injection nozzles for ammonia being configured to eject ammonia in a direction perpendicular to the flame; and a controlling unit configured to optimize an amount of ammonia ejected from each of the injection nozzles for ammonia; wherein the controlling unit controls the amount of ammonia ejected from the plural injection nozzles for ammonia in a manner to minimize nitrogen oxides relative to a size of the flame.

5. A method of burning ammonia in a metal heating furnace, the metal heating furnace comprising: a burner nozzle provided on a furnace wall, the burner nozzle being configured to emit flame, and the flame being configured to burn ammonia; plural injection nozzles for ammonia, the injection nozzles for ammonia being provided on a side wall or a ceiling wall at intervals in a direction in which the flame extends, and the injection nozzles for ammonia being configured to eject ammonia in a direction perpendicular to the flame; and a controlling unit configured to optimize an amount of ammonia ejected from each of the injection nozzles for ammonia; wherein the controlling unit performs on / off control of ammonia ejected from the plural injection nozzles for ammonia in a manner to minimize nitrogen oxides relative to a size of the flame.

6. The method as claimed in Claim 4 or Claim 5 of burning ammonia in the metal heating furnace, wherein the controlling unit performs control by referring to an empirical data.

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