industrial furnace

Abstract

To provide an industrial furnace combusting ammonia while effectively decreasing NOx.SOLUTION: An industrial furnace 1 combusting ammonia being supplied together with combustion air and gas fuel to a burner 10 attached to a side wall 3 of a furnace body 2, using a flame F from the burner 10, is characterized in that a refractory 100 for promoting combustion is provided on a position brought into contact with the flame F in the furnace body 2. The industrial furnace is characterized in that a plurality of ammonia injection nozzles 21, 22, 23, 24 injecting ammonia downward, is disposed on a ceiling wall 5 of the furnace body 2 with a gap apart therebetween in the extending direction of the flame F.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an industrial furnace that burns ammonia as fuel. [Background technology]

[0002] In recent years, ammonia, which does not produce carbon dioxide when burned, has been attracting attention as a new fuel from the perspective of curbing global warming. However, when ammonia is mixed with fossil fuels or burned alone, nitrogen oxides (NO X It is known that the amount of emissions of ) increases (see, for example, Patent Document 1).

[0003] The combustion device described in Patent Document 1 solves the problem of increased nitrogen oxides when coal is burned with ammonia added.

[0004] In thermal equipment that requires combustion, such as industrial furnaces, there is always a heating process where the temperature is raised from room temperature. If ammonia is used as the only fuel, unburned ammonia and nitrogen oxides (NO X ) and other environmental problems, which worsen the greenhouse effect and other environmental problems. Furthermore, because ammonia burns slower than existing gas fuels such as city gas, increasing the amount of ammonia supplied to combustion equipment creates a vicious cycle in which the amount of unburned ammonia increases.

[0005] To address this issue, it is possible to increase the size of the thermal equipment, including the industrial furnace, to increase the amount of ammonia burned, but this would require a large initial investment. X It is common to install denitrification equipment as part of exhaust gas treatment facilities to render these substances harmless, but this comes at a cost. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 7020759 Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an industrial furnace that burns ammonia while effectively reducing nitrogen oxides. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides an industrial furnace (1) in which ammonia supplied to a burner (10) together with combustion air and gas fuel is burned by a flame (F) from the burner (10) provided on a side wall (3) of a furnace body (2), A refractory material (100) for promoting combustion was provided in the furnace body (2) at a position in contact with the flame (F). So, The refractory (100) is installed upright from the bottom of the furnace body (2) at a distance from the side wall (3) and the ceiling wall (5) of the furnace body (2). It is characterized by:

[0009] The present invention is also characterized in that the refractory (100) is provided between the front end and the rear end of the flame (F) in the direction of extension and the front end.

[0010] The present invention also provides an industrial furnace (1) in which ammonia supplied to a burner (10) together with combustion air and gas fuel is combusted in a flame (F) from the burner (10) provided on a side wall (3) of a furnace body (2), A refractory material (100) for promoting combustion was provided around the tip of the flame (F) in the furnace body (2). So, The refractory (100) is installed upright from the bottom of the furnace body (2) at a distance from the side wall (3) and the ceiling wall (5) of the furnace body (2). It is characterized by: Here, the vicinity of the tip of the flame (F) includes the case where the refractory material (100) is provided at a position that is not in direct contact with the flame (F), and here, "the vicinity" means within a range of 200 mm from the tip.

[0011] The present invention also provides the refractory (100). Height teeth, Half the height of the flame (F) It is characterized in that:

[0012] The present invention is also characterized in that a plurality of ammonia injection nozzles (21, 22, 23, 24) are provided on the ceiling wall (5) of the furnace body (2) at intervals in the direction in which the flame (F) extends and which inject ammonia downward.

[0013] The symbols in parentheses above indicate corresponding elements or items described in the drawings and in the detailed description of the invention to be described later. [Effects of the Invention]

[0014] According to the industrial furnace of the present invention, when ammonia supplied to the burner together with combustion air and gas fuel is burned by a flame from a burner provided on the side wall of the furnace body, by providing a refractory material for promoting combustion, such as a firebrick, at a position in the furnace body that comes into contact with the flame, the combustion of ammonia can be dramatically promoted compared to when a refractory material is not provided. This makes it possible to reduce unburned ammonia.

[0015] The refractory material is preferably provided between the front end and the rear end in the direction of flame extension and the midpoint between the front end and the rear end. Note that even if a refractory material for accelerating combustion is provided around the tip of the flame inside the furnace body, it is still effective in reducing unburned ammonia. In other words, even if a refractory material for accelerating combustion is provided at a position away from the tip of the flame and not in contact with the flame (a position within 200 mm from the tip), it is still effective in reducing unburned ammonia.

[0016] Furthermore, according to the present invention, a plurality of ammonia injection nozzles are provided on the ceiling wall of the furnace body at intervals in the direction of flame extension, which inject ammonia downward. This reduces the amount of nitrogen oxides (NO X ) emissions can be reduced. That is, if a refractory material for accelerating combustion is provided at a position in contact with the flame inside the furnace body, the combustion of ammonia can be accelerated, but this also increases the amount of nitrogen oxides (NO X) becomes high, so by installing multiple ammonia injection nozzles in the furnace body other than the burner mounting part, the ammonia is heated and a reduction reaction is caused, and nitrogen oxides (NO X ) can be neutralized. When ammonia is completely burned by providing a refractory material, nitrogen oxides (NO X ) may be emitted at levels more than 10 times the regulatory limit, but by installing multiple ammonia injection nozzles as a secondary fuel, nitrogen oxides (NO X ) can be effectively reduced.

[0017] According to the present invention, the size of the thermal equipment including the industrial furnace is increased to increase the amount of ammonia burned, and nitrogen oxides (NO X ) to render them harmless, there is no need to install denitrification equipment or other exhaust gas treatment facilities, which reduces costs accordingly. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a vertical cross-sectional view showing a main part of an industrial furnace according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing a main part of an industrial furnace according to an embodiment of the present invention. [Figure 3] FIG. 2 is a vertical cross-sectional view showing a main part of another industrial furnace according to an embodiment of the present invention. [Figure 4] 1 is a graph comparing the concentrations of exhaust gas components between an industrial furnace provided with a refractory material according to an embodiment of the present invention and an industrial furnace not provided with a refractory material. DETAILED DESCRIPTION OF THE INVENTION

[0019] An industrial furnace 1 according to an embodiment of the present invention will be described with reference to FIGS.

[0020] As shown in FIG. 1, an industrial furnace 1 according to this embodiment (here, a metal heating furnace will be described as an example) has a generally rectangular cross section, and is a furnace 1 in which burners 10 are provided on furnace walls 3 that constitute a furnace body 2, and ammonia (NH3) is mixed and burned with gas fuel by flames from the burners 10.

[0021] Ammonia (NH3) is sent from an ammonia supply device 14 to the burner 10 via a first pipe 11, which is provided with an ammonia on-off valve (solenoid valve) 17. The gas fuel, which is an existing gas such as city gas or propane gas, is sent from a gas supply device 15 to the burner 10 via a second pipe 12, which is provided with a gas on-off valve (solenoid valve) 18. As combustion air, outside air is sent by a blower 16 to the burner 10 via an air pipe 13, which is provided with an air on-off valve (solenoid valve) 19. The burner 10 extends horizontally and radiates a flame F horizontally (from right to left in FIGS. 1 and 2).

[0022] Four ammonia injection nozzles (first ammonia injection nozzle, second ammonia injection nozzle, third ammonia injection nozzle, fourth ammonia injection nozzle) 21, 22, 23, 24 are provided at intervals (equally spaced here) in the direction in which the flame F extends, i.e., from right to left in Figures 1 and 2.

[0023] Ammonia supplied from an ammonia supply device 14 is injected from ammonia injection nozzles 21, 22, 23, and 24 into the furnace via solenoid valves (first solenoid valve, second solenoid valve, third solenoid valve, fourth solenoid valve) 31, 32, 33, and 34, respectively, in a direction perpendicular to the direction in which flame F extends, i.e., from top to bottom. A third pipe 41 for sending ammonia from the ammonia supplier 14 to each of the ammonia injection nozzles 21 , 22 , 23 , and 24 branches off from the first pipe 11 between the ammonia supplier 14 and the ammonia on-off valve 17 . A flue 20 for discharging exhaust gas is provided in a part of the ceiling wall 5 of the industrial furnace 1.

[0024] A refractory material 100 for promoting combustion is provided in the furnace body 2 at a position where it comes into contact with the flame F. The refractory 100 is made of firebricks (or heat-resistant metal), and stands upright from the bottom of the furnace body 2. As shown in Figure 1, the height of the refractory material 100 is approximately half the height of the flame F, and it is positioned between the front end (position indicated by M) and the rear end (inner wall of side wall 3) in the direction in which the flame F extends, and the intermediate position (position indicated by C) between the front end and the rear end (inner wall of side wall 3) (range indicated by R).

[0025] When the refractory material 100 is provided, the flame F comes into contact with the refractory material 100, causing the refractory material 100 to glow red. When ammonia comes into contact with the refractory material 100, the combustion of the ammonia is dramatically accelerated compared to when the refractory material 100 is not provided, and the amount of unburned ammonia can be reduced. This allows ammonia to be used as fuel even when the temperature is low, such as when the temperature of the industrial furnace 1 is rising, and the amount of ammonia burned can be increased.

[0026] In this case, there is no need to increase the size of the thermal equipment, including the industrial furnace, to increase the amount of ammonia burned, and the ammonia combustion field can be made compact, which makes it economical by reducing the initial investment in the equipment. In addition, the heat dissipation effect of the refractory material 100 has the advantage of contributing to increasing the temperature of the thermal equipment.

[0027] In addition, as ammonia combustion progresses, nitrogen oxides (NO X ) becomes high, but by providing a plurality of ammonia injection nozzles 21 to 24 in the furnace body 2 other than the burner mounting portion, the ammonia is heated and a reduction reaction is caused, and the nitrogen oxide (NO X ) can be neutralized, so there is no problem. According to this, nitrogen oxides (NO X ) to render them harmless, there is no need to install denitrification equipment or other exhaust gas treatment facilities, which reduces costs accordingly.

[0028] In addition, since a plurality of ammonia injection nozzles 21 to 24 are provided, the amount of ammonia burned and the nitrogen oxides (NO X ) can be checked in real time, and an appropriate amount of ammonia can be easily supplied from the ammonia injection nozzles 21 to 24.

[0029] In this embodiment, a plurality of ammonia injection nozzles 21 to 24 are provided on the ceiling wall 5 of the furnace body 2. However, the expected nitrogen oxides (NO X ) is small, or if a denitration device or the like is installed even if it is costly, it is possible to not provide multiple ammonia injection nozzles 21 to 24 at all, as shown in FIG.

[0030] 4 shows experimental data comparing the concentrations of exhaust gas components between an industrial furnace equipped with the refractory 100 and an industrial furnace not equipped with the refractory 100. Bricks were used as the refractory 100, and Test Nos. 1 to 3 show cases where red-hot bricks were used due to the furnace temperature, while Test Nos. 4 to 5 show cases where red-hot bricks were not used.

[0031] In test No. 4, the furnace temperature was 946°C and the combustion volume was 40 kW. The unburned gas components were CO (carbon monoxide) 12,242 ppm, CH4 (methane) 1,613 ppm, and NH3 (ammonia) 1,251 ppm. At this time, nitrogen oxides (NO X The amount of NO1 (nitrogen monoxide) emitted was 1 ppm, and the amount of NO2 (nitrogen dioxide) emitted was 2 ppm. The proportion of O2 (oxygen) was 0%. The amount of unburned NH3 (ammonia) was large, so the amount of nitrogen oxides (NO X ) were few.

[0032] Next, in Test No. 5, the furnace temperature was higher than Test No. 4 at 1040°C, the combustion amount was 40kW, and the unburned gas components were CO (carbon monoxide) 141ppm, CH4 (methane) 0ppm, and NH3 (ammonia) 1,749ppm. At this time, nitrogen oxides (NO XThe NO1 (nitrogen monoxide) emissions were 416 ppm, and the NO2 (nitrogen dioxide) emissions were 3 ppm. The proportion of O2 (oxygen) was 0.27%. The furnace temperature was higher than in Test NO4, which promoted combustion, but the amount of unburned NH3 (ammonia) was greater than in Test NO4, and the amount of nitrogen oxides (NO X ) and therefore the amount of NO1 (nitric oxide) emissions also increased.

[0033] In contrast to these, in the test No. 1 in which the refractory 100 was installed, the furnace temperature was 944°C, the combustion amount was 50kW, and the unburned gas components were CO (carbon monoxide) 0.52ppm, CH4 (methane) 0ppm, and NH3 (ammonia) 0ppm. X The amount of NO1 (nitrogen monoxide) emitted was 500 ppm, and the amount of NO2 (nitrogen dioxide) emitted was 96 ppm. The proportion of O2 (oxygen) was 1.80%. There was no unburned NH3 (ammonia) and the resulting nitrogen oxides (NO X ) is greater than in test Nos. 4 and 5.

[0034] In addition, in the test NO2 in which the refractory 100 was installed, the furnace temperature was 1009°C, the combustion amount was 45kW, and the unburned gas components were CO (carbon monoxide) 1.14ppm, CH4 (methane) 0ppm, and NH3 (ammonia) 6ppm. X The amount of NO1 (nitrogen monoxide) emitted was 701 ppm, and the amount of NO2 (nitrogen dioxide) emitted was 12 ppm. The proportion of O2 (oxygen) was 1.63%. The amount of unburned NH3 (ammonia) was extremely small, and the amount of nitrogen oxides (NO X ) is higher than in Test No. 4 and No. 5. Also, because the furnace temperature is higher than in Test No. 1, the amount of nitrogen oxides (NO X ) emissions of NO1 (nitric oxide) are increasing.

[0035] Furthermore, in the test No. 3 in which the refractory 100 was installed, the furnace temperature was 1013°C, the combustion amount was 40 kW, and the unburned gas components were CO (carbon monoxide) 0 ppm, CH4 (methane) 0 ppm, and NH3 (ammonia) 2 ppm. X The amount of NO1 (nitrogen monoxide) emitted was 689 ppm, and the amount of NO2 (nitrogen dioxide) emitted was 12 ppm. The proportion of O2 (oxygen) was 1.73%. The amount of unburned NH3 (ammonia) was extremely small, and the amount of nitrogen oxides (NO X ) is higher than in Test No. 4 and No. 5. Also, because the furnace temperature is higher than in Test No. 1, the amount of nitrogen oxides (NO X ) emissions of NO1 (nitric oxide) are increasing.

[0036] From the experimental data, it was found that when red-hot bricks were used as refractory 100 (Test Nos. 1 to 3), CO (carbon monoxide), CH4 (methane), and NH3 (ammonia) were burned and almost no emissions were observed, proving that the presence of refractory 100 promotes the combustion of NH3 (ammonia). Furthermore, even if the furnace body 2 has the same volume, the combustion amount of the burner 10 can be increased by 5 to 10 kW, such as from 40 kW to 45 kW or 50 kW. In addition, the large amount of remaining O2 (oxygen) can further promote combustion.

[0037] Nitrogen oxides (NO X ) also increases, but this can be reduced by providing a plurality of ammonia injection nozzles (first ammonia injection nozzle, second ammonia injection nozzle, third ammonia injection nozzle, fourth ammonia injection nozzle) 21, 22, 23, 24 secondarily, separately from the burner 10 side, as shown in FIGS. 1 and 2, so there is no problem.

[0038] In this embodiment, the refractory material 100 is erected from the bottom of the furnace body 2, but it may be in any form as long as it can be installed inside the furnace, and for example, it may be supported from the top of the furnace body 2.

[0039] Furthermore, as shown in Figures 1 and 3, the refractory material 100 is provided in a position in contact with the flame F within the furnace body 2, but the effect of reducing unburned ammonia can also be achieved by providing the refractory material 100 for combustion promotion around the tip of the flame F within the furnace body 2. Here, "around the tip of the flame F" includes cases where the refractory material 100 is placed in a position that is not in direct contact with the flame F, and "around" here means within a range of 200 mm from the tip. [Explanation of symbols]

[0040] 1. Industrial furnace 2 Furnace body 3 side wall 5 Ceiling Wall 10 Burner 11 First piping 12 Second piping 13 Air piping 14 Ammonia supply device 15 Gas supply equipment 16 Blower 17 Ammonia on-off valve 18 Gas on-off valve 19 Air on-off valve 20 flue 21 First ammonia injection nozzle 22 Second ammonia injection nozzle 23 Third ammonia injection nozzle 24 No. 4 ammonia injection nozzle 31 First solenoid valve 32 Second solenoid valve 33 Third solenoid valve 34 Fourth solenoid valve 41 Third piping 100 Refractories F Flame

Claims

1. An industrial furnace in which ammonia supplied to a burner together with combustion air and gas fuel is burned with a flame from a burner provided on a side wall of a furnace body, A refractory material for promoting combustion is provided in the furnace body at a position where it comes into contact with the flame, 1. An industrial furnace, wherein the refractory material is installed upright from the bottom of the furnace body at a distance from the side walls and ceiling wall of the furnace body.

2. 2. The industrial furnace according to claim 1, wherein the refractory material is provided between the front end and the rear end of the furnace in the direction of extension of the flame and the front end.

3. An industrial furnace in which ammonia supplied to a burner together with combustion air and gas fuel is burned with a flame from a burner provided on a side wall of a furnace body, A refractory material for promoting combustion is provided around the tip of the flame in the furnace body, 1. An industrial furnace, wherein the refractory material is installed upright from the bottom of the furnace body at a distance from the side walls and ceiling wall of the furnace body.

4. 4. The industrial furnace according to claim 1, wherein the height of the refractory is half the height of the flame.

5. 4. The industrial furnace according to claim 1, wherein a plurality of ammonia injection nozzles are provided on the ceiling wall of the furnace body at intervals in the direction of extension of the flame, for injecting ammonia downward.

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