BURNER

Abstract

The invention relates to a burner comprising a fuel gas supply tube constructed for the supply of ammonia-containing fuel gas and the injection of fuel gas from a fuel gas injection orifice at its end; a first combustion-assisting gas supply tube arranged outward radially from the fuel gas supply tube such that it surrounds the fuel gas supply tube and is constructed for the supply of first combustion-assisting gas and the injection of first combustion-assisting gas from a first combustion-assisting orifice at its end; and a second combustion-assisting gas supply tube constructed for the supply of second combustion-assisting gas and the injection of second combustion-assisting gas from a second combustion-assisting orifice such that the second combustion-assisting gas is incorporated into the rear of the burner flame from the first combustion-assisting orifice.The oxygen concentration of the combustion support gas is the combination of the first and second combustion support gases at 30% or more, the oxygen concentration of the second combustion support gas at 90% or more, and 0.38 ≤ (V1 + V2) / V3 ≤ 1.1, where V1 is the volumetric flow rate of oxygen at the first combustion support gas nozzle, V2 is the volumetric flow rate of oxygen at the second combustion support gas nozzle, and V3 is the volumetric flow rate of ammonia at the fuel gas nozzle.

Description

Burner

[0001] The present invention relates to a burner.

[0002] A burner using a fuel gas and a combustion-supporting gas is known (see, for example, Patent Document 1).

[0003] Patent No. 4261753

[0004] In industrial furnaces such as metal heating furnaces, glass melting furnaces, and aluminum melting furnaces, burners that combust fuel with an oxidizer are commonly used as heat sources. The fuels used include various fossil fuels, such as solid fuels like pulverized coal, liquid fuels like kerosene or heavy oil, and gaseous fuels like natural gas or LPG. In industrial furnaces, the material to be heated is heated by radiant heat transfer from the flame generated by burning fuel.

[0005] When fossil fuels are used, a large amount of CO is contained in the combustion exhaust gas. ２ Since this involves the inclusion of ammonia, in recent years it has been proposed to use ammonia.

[0006] Ammonia burns but produces CO ２ However, since it does not contain carbon, the flame radiation intensity is low, and the combustion speed is slow, resulting in an unstable flame.

[0007] Therefore, an object of the present invention is to provide a method for producing ammonia as a fuel, and to produce NOx while ensuring radiation intensity and flame stability. Ｘ The present invention aims to provide a burner capable of suppressing the occurrence of

[0008] One aspect of the present invention is as follows.

[0009] [1] A combustion assisting apparatus comprising: a fuel gas supply pipe that supplies a fuel gas containing ammonia and injects the fuel gas from a fuel gas injection hole at a tip thereof; a first combustion assisting gas supply pipe that is provided radially outside the fuel gas supply pipe so as to surround the fuel gas supply pipe and that supplies a first combustion assisting gas and injects the gas from the first combustion assisting gas injection hole at a tip thereof; and a second combustion assisting gas supply unit that supplies a second combustion assisting gas and injects the gas from the second combustion assisting gas injection hole so as to join a burner flame downstream of the first combustion assisting gas injection hole, wherein the oxygen concentration of the combined combustion assisting gas of the first combustion assisting gas and the second combustion assisting gas is 30% or more, the oxygen concentration of the second combustion assisting gas is 90% or more, and the volumetric flow rate of oxygen at the first combustion assisting gas injection hole is V １ The volume flow rate of oxygen at the second combustion-supporting gas nozzle is V ２ The volumetric flow rate of ammonia at the fuel gas nozzle is V ３ When 0.38≦(V １ +V ２ ) / V ３ ≦1.1, burner.

[0010] [2] The momentum of the first combustion-supporting gas ejected from the first combustion-supporting gas ejection hole per unit time is q １ and the momentum of the second combustion-supporting gas ejected from the second combustion-supporting gas ejection hole per unit time is q ２ When 0.1≦q １ / q ２ ≦2.0.

[0011] [3] The burner according to [1] or [2], which has a burner body having a double-pipe structure consisting of the fuel gas supply pipe and the first combustion-supporting gas supply pipe.

[0012] [4] The fuel gas ejection holes are formed on the inner peripheral surface of the tip of the fuel gas supply pipe, and the inner diameter of the fuel gas supply pipe at the tip is d １ and the outer diameter is D １ The distance from the tip is L １ The inner diameter at the position where ２ When this is done, 5 x d １ ≦L １ ≦10×d １ At the position where １<d ２ and {(D １ -d １ ) / D １} × 100≦20. The burner according to any one of [1] to [3].

[0013] [5] The combustion-supporting first gas ejection holes are formed on the inner peripheral surface of the tip of the combustion-supporting first gas supply pipe, and the inner diameter of the tip of the combustion-supporting first gas supply pipe is d ３ The distance from the tip is L ２ The inner diameter at the position where ４ When this is done, 5 x d ３ ≦L ２ ≦10×d ３ At the position where ３ <d ４ the tip of the fuel gas supply pipe is located closer to the base end than the tip of the first combustion-assisting gas supply pipe, and the distance from the tip of the fuel gas supply pipe to the tip of the first combustion-assisting gas supply pipe is defined as L ３ When this is done, L ３ <5 × d ３ The burner according to any one of [1] to [4],

[0014] [6] A burner block having a burner body having the fuel gas supply pipe and the first combustion-supporting gas supply pipe, and an opening in which the burner body is disposed, wherein the maximum outer diameter of the first combustion-supporting gas supply pipe at the portion disposed at the opening is D ４ The inner diameter at the tip of the opening is D ５ When this is done, D ４ ≦D ５ ≦1.1×D ４ the tip of the first combustion-assisting gas supply pipe is located closer to the base end than the tip of the opening, and the distance from the tip of the opening to the tip of the first combustion-assisting gas supply pipe is L ４ When this is the case, 0.2≦{(D ５ / 2) ２ ×π÷L ４ ２ The burner according to any one of [1] to [5], wherein the ratio of the refrigerant concentration to the refrigerant concentration is ≦0.5.

[0015] [7] A heating furnace in which at least one burner according to any one of [1] to [6] is installed.

[0016] According to the present invention, ammonia is used as fuel and NO is generated while ensuring radiation intensity and flame stability. Ｘ It is possible to provide a burner that can suppress the occurrence of

[0017] 1 is a cross-sectional view showing a heating furnace according to an embodiment of the present invention; FIG. 2 is a partially enlarged view of a burner shown in FIG. 1; FIG. 3 is a graph showing the relationship between the oxygen concentration of an oxidizer and an adiabatic theoretical flame temperature; and FIG. 4 is a graph showing the relationship between the oxygen concentration of an oxidizer and a combustion speed.

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] As shown in Figures 1 and 2, in one embodiment of the present invention, a heating furnace 7 has at least one burner 1. The heating furnace 7 has a furnace side wall 7a on which the burner 1 is installed. The burner 1 is embedded in the furnace side wall 7a. However, the arrangement of the burner 1 in the heating furnace 7 is not limited to this. The burner 1 burns a fuel gas in the internal space 7b of the heating furnace 7 to heat the object to be heated and melt it as necessary.

[0020] The burner 1 includes a fuel gas supply pipe 2a that supplies ammonia-containing fuel gas (preferably without premixing oxygen) and jets the fuel gas from a fuel gas jet hole 2b at the tip thereof, and a combustion-supporting first gas supply pipe 2b that is disposed radially outside the fuel gas supply pipe 2a so as to surround the fuel gas supply pipe 2a (preferably the tip of the fuel gas supply pipe 2a as shown in the figure) (preferably so that a flow path for the combustion-supporting first gas is formed between the outer circumferential surface of the fuel gas supply pipe 2a and the inner circumferential surface of the combustion-supporting first gas supply pipe 2b that is spaced from the outer circumferential surface all around). a first combustion-stimulating gas supply pipe (2b) that supplies a second combustion-stimulating gas (preferably without premixing fuel) and jets it out from a first combustion-stimulating gas jet hole (2b1) at the tip thereof; and a second combustion-stimulating gas supply section (6) that supplies a second combustion-stimulating gas and jets it out from a second combustion-stimulating gas jet hole (6a) so as to join the burner flame downstream of the first combustion-stimulating gas jet hole (2b1). The oxygen concentration of the combined first combustion-stimulating gas and second combustion-stimulating gas is 30% or more, and the oxygen concentration of the second combustion-stimulating gas is 90% or more. The volumetric flow rate of oxygen at the first combustion-stimulating gas jet hole (2b1) is V １ The volume flow rate of oxygen at the second combustion-supporting gas nozzle 6a is V ２ The volumetric flow rate of ammonia at the fuel gas nozzle 2b is V ３ When 0.38≦(V １ +V ２ ) / V ３ ≦1.1.

[0021] According to the above configuration, the combustion-supporting gas, which is the sum of the first combustion-supporting gas and the second combustion-supporting gas, has an oxygen concentration of 30% or more, so that ammonia can be used as the fuel gas and radiation intensity and flame stability can be ensured. Furthermore, the combustion-supporting gas has an oxygen concentration of 30% or more, the oxygen concentration of the second combustion-supporting gas is 90% or more, and 0.38≦(V １ +V ２ ) / V ３ ≦1.1, the ammonia is decomposed into nitrogen molecules and hydrogen molecules (NH ３ →0.5N ２ +1.5H ２ ) by creating a reducing combustion state Ｘ (NO derived from N in fuel gas Ｘ) is suppressed, and further, by causing the second combustion-supporting gas to merge with the burner flame downstream of the first combustion-supporting gas ejection hole 2b1, the thermal NO Ｘ (NO derived from N in the second combustion-supporting gas) Ｘ Therefore, it is possible to burn (preferably completely burn) hydrogen molecules while suppressing the generation of NO. Ｘ This allows realizing a burner 1 that can suppress the generation of ammonia. The fuel gas is not particularly limited as long as it contains ammonia, but preferably contains ammonia as a main component (i.e., the ammonia component is more than 50% but not more than 100%). The combustion-supporting first gas is not particularly limited as long as it has an oxygen concentration sufficient to satisfy the above conditions, but a configuration using oxygen-enriched air is preferable. The fuel gas supply pipe 2a preferably surrounds the central axis of the combustion-supporting first gas supply pipe 2b as shown in the figure, and more preferably is provided coaxially with the combustion-supporting first gas supply pipe 2b as shown in the figure. In this embodiment, the inner and outer circumferential surfaces of the fuel gas supply pipe 2a at the tip of the fuel gas supply pipe 2a and the inner and outer circumferential surfaces of the combustion-supporting first gas supply pipe 2b at the tip of the combustion-supporting first gas supply pipe 2b are each circular, but this is not limited thereto.

[0022] The radiation intensity and flame stability of the burner 1 are related to the flame temperature and combustion rate, and the flame temperature and combustion rate are related to the oxygen concentration of the combustion-supporting gas. For example, the relationship between the oxygen concentration of the oxidizer (combustion-supporting gas) and the adiabatic theoretical flame temperature of fossil fuels (methane) and ammonia is shown in Figure 3, and the relationship between the oxygen concentration of the oxidizer (combustion-supporting gas) and the combustion rate of fossil fuels (methane) and ammonia is shown in Figure 4. As such, ammonia has a lower flame temperature and combustion rate than fossil fuels. In light of the above, it has been found that by setting the oxygen concentration of the combustion-supporting gas to 30% or more, radiation intensity and flame stability sufficient for practical use in industrial furnaces can be ensured.

[0023] CH, the main component of common fossil fuels ４ (methane) and NH ３ The chemical formulas for the combustion of ammonia are as follows: (1) CH ４ +20 ２ +8N ２→CO ２ +2H ２ O+8N ２ (2) CH ４ +20 ２ →CO ２ +2H ２ O (3) NH ３ +0.75O ２ +3N ２ →1.5H ２ O+3.5N ２ (4) NH ３ +0.75O ２ →1.5H ２ O+0.5N ２ Formula (1) is CH ４ is burned in air. ４ is burned in oxygen. ３ is burned in air. ３ is burned in oxygen.

[0024] CO included on the right side of each equation ２ and H ２ O is known as a radiative gas, and these gases contribute to the radiation performance of the combustion flame. Comparing the formulas, the concentrations of each radiative gas are as follows, and it can be seen that changing the oxidizer from air to oxygen improves the radiation performance of the flame. However, in formula (2), CO in the exhaust gas ２ In addition, in equation (3), CO ２ The concentration of the radiative gas is zero, and the concentration of the radiative gas is greater than that in equation (1). Furthermore, in equation (4), where the oxidant is changed from air to oxygen, the concentration of the radiative gas is further improved. Therefore, it can be seen that increasing the oxygen concentration of the oxidant is effective for ammonia, which has a low flame temperature.

[0025] The burner 1 determines the momentum of the first combustion-supporting gas ejected from the first combustion-supporting gas ejection holes 2b1 per unit time as q １ The momentum of the second combustion-supporting gas ejected from the second combustion-supporting gas ejection holes 6a per unit time is q ２ When 0.1≦q １ / q ２≦2.0, where q １ For example, the mass of the first combustion-supporting gas ejected from the first combustion-supporting gas ejection hole 2b1 per unit time is m １ and the flow velocity of the first combustion-supporting gas at the first combustion-supporting gas ejection hole 2b1 is v １ When q １ = m １ v １ and q ２ For example, the mass of the second combustion-supporting gas ejected from the second combustion-supporting gas ejection hole 6a per unit time is m ２ The flow velocity of the second combustion-supporting gas at the second combustion-supporting gas ejection hole 6a is v ２ When q ２ = m ２ v ２ According to the above configuration, when the second combustion-supporting gas is joined to the burner flame, the external atmosphere (furnace atmosphere, etc.) can be entrained in the second combustion-supporting gas, so that the temperature of the burner flame can be prevented from rising too much locally, and as a result, NO Ｘ The generation of oxygen can be suppressed. Excess oxygen in the external atmosphere can also be used for combustion.

[0026] The burner 1 has a burner body 2 having a double-pipe structure consisting of a fuel gas supply pipe 2a and a first combustion-supporting gas supply pipe 2b. With the above-mentioned configuration, radiation intensity and flame stability can be ensured with a simple structure.

[0027] The fuel gas ejection holes 2b are formed on the inner peripheral surface of the tip of the fuel gas supply pipe 2a, and the inner diameter of the tip of the fuel gas supply pipe 2a is d １ and the outer diameter is D １ The distance from the tip is L １ The inner diameter at the position where ２ When this is done, 5 x d １ ≦L １ ≦10×d １ At the position where １ <d ２ and {(D １ -d １ ) / D １}×100≦20. １ ≦L １ ≦10×d １ At the position where１ <d ２ By setting the above, the flow path of the fuel gas in the vicinity of the fuel gas ejection holes 2b becomes narrower toward the fuel gas ejection holes 2b, and therefore the supply pressure of the fuel gas increases toward the fuel gas ejection holes 2b. As a result, the supply pressure of the fuel gas at the fuel gas ejection holes 2b is made uniform, and therefore the uniformity of the ejection amount of the fuel gas at the fuel gas ejection holes 2b can be improved. １ -d １ ) / D １}×100≦20, the distance between the outer circumferential surface of the fuel gas flow path and the inner circumferential surface of the first combustion-supporting gas flow path at the tip of the fuel gas supply pipe 2 a is small enough for practical use, thereby realizing rapid mixing of the fuel gas and the first combustion-supporting gas. Therefore, good mixing can be achieved, resulting in good flame stability.

[0028] The first combustion-supporting gas ejection holes 2b1 are formed on the inner peripheral surface of the tip of the first combustion-supporting gas supply pipe 2b, and the inner diameter of the tip of the first combustion-supporting gas supply pipe 2b is d ３ The distance from the tip is L ２ The inner diameter at the position where ４ When this is done, 5 x d ３ ≦L ２ ≦10×d ３ At the position where ３ <d ４ The tip of the fuel gas supply pipe 2a is located closer to the base end than the tip of the first combustion-assisting gas supply pipe 2b, and the distance from the tip of the fuel gas supply pipe 2a to the tip of the first combustion-assisting gas supply pipe 2b is L ３ When this is done, L ３ <5 × d ３ According to the above configuration, 5×d ３ ≦L ２ ≦10×d ３ At the position where ３ <d ４Since the flow path of the combustion-supporting first gas narrows toward the combustion-supporting first gas ejection holes 2b1, the supply pressure of the combustion-supporting first gas increases toward the combustion-supporting first gas ejection holes 2b1, and as a result, the supply pressure of the combustion-supporting first gas at the combustion-supporting first gas ejection holes 2b1 is made uniform, thereby improving the uniformity of the ejection amount of the combustion-supporting first gas at the combustion-supporting first gas ejection holes 2b1. ３ <5 × d ３ By setting the temperature to 0.5°C, the mixing chamber 3 can be formed while suppressing the possibility of flashback, and therefore, better mixing can be achieved, resulting in better flame stability. ２ ≦10×d ３ It extends linearly parallel to the central axis within the range.

[0029] The burner 1 has a burner body 2 having a fuel gas supply pipe 2a and a first combustion-supporting gas supply pipe 2b, and a burner block 4 having an opening 4a in which the burner body 2 is arranged (preferably coaxially as shown in the figure), and the maximum outer diameter of the first combustion-supporting gas supply pipe 2b at the part arranged at the opening 4a is D ４ The inner diameter at the tip of the opening 4a is d ５ When this is done, D ４ ≦d ５ ≦1.1×D ４ The tip of the first combustion-assisting gas supply pipe 2b is located closer to the base end than the tip of the opening 4a, and the distance from the tip of the opening 4a to the tip of the first combustion-assisting gas supply pipe 2b is L ４ When 0.2≦{(d ５ / 2) ２ ×π÷L ４ ２ According to the above configuration, D ４ ≦d ５ ≦1.1×D ４ The tip of the first combustion-supporting gas supply pipe 2b is located closer to the base end than the tip of the opening 4a, and 0.2≦{(d ５ / 2) ２ ×π÷L ４ ２By satisfying a value of ≦0.5, the opening 4a of the burner block 4 can form a good combustion chamber 5 while protecting the burner body 2 from radiant heat from the installation environment, such as an industrial furnace. The burner 1 is not limited to a configuration having the burner block 4, and may be configured to have, for example, a water-cooled jacket instead of or in addition to the burner block 4. In this embodiment, the opening 4a is configured as a circular through-hole, but is not limited to this.

[0030] The second combustion-supporting gas supply unit 6 is configured by the burner block 4, which has a second combustion-supporting gas supply path 4b for supplying the second combustion-supporting gas, and the tip of the second combustion-supporting gas supply path 4b forms a second combustion-supporting gas ejection hole 6a. With the above configuration, the second combustion-supporting gas supply unit 6 can be realized with a simple structure. In this embodiment, the second combustion-supporting gas supply path 4b extends linearly and inclined with respect to the central axis. The inner circumferential surface (second combustion-supporting gas ejection hole 6a) at the tip of the second combustion-supporting gas supply path 4b is circular in this embodiment, but is not limited to this. In this embodiment, the second combustion-supporting gas ejection hole 6a is located vertically below the opening 4a, but is not limited to this.

[0031] The distance between the fuel gas ejection hole 2b and the point (preferably the intersection point) on the central axis of the first combustion-supporting gas supply pipe 2b that is closest to the axis of the second combustion-supporting gas supply passage 4b ​​is defined as L. ５ When this is the case, (0.06 × V3) × 0.5 ≦ L ５ ≦(0.06×V3)×1.5. Ｘ This makes it easier to obtain the inhibitory effect.

[0032] The tip of the opening 4a and the second combustion supporting gas orifices 6a are arranged in parallel on the tip end surface of the burner block 4 (that is, the tip of the opening 4a is provided radially outward from the second combustion supporting gas orifices 6a, and the second combustion supporting gas orifices 6a are provided radially outward from the tip of the opening 4a). The distance between the central axis of the opening 4a on the tip end surface of the burner block 4 and the axis of the second combustion supporting gas orifices 6a is defined as L. ６ When this is done, L ６ is not particularly limited, but it is better to set it as large as possible to reduce NO due to the reduction combustion state. Ｘ This makes it easier to obtain the inhibitory effect.

[0033] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be modified in various ways without departing from the gist of the present invention.

[0034] DESCRIPTION OF SYMBOLS 1 Burner 2 Burner body 2a Fuel gas supply pipe 2a1 Fuel gas ejection hole 2b First combustion-supporting gas supply pipe 2b1 First combustion-supporting gas ejection hole 3 Mixing chamber 4 Burner block 4a Opening 4b Second combustion-supporting gas supply path 5 Combustion chamber 6 Second combustion-supporting gas supply section 6a Second combustion-supporting gas ejection hole 7 Heating furnace 7a Furnace side wall 7b Internal space d １ Inner diameter d ２ Inner diameter d ３ Inner diameter d ４ Inner diameter d ５ Inner diameter D １ Outer diameter D ２ Outer diameter D ３ Outer diameter D ４ Outer diameter L １ distance L ２ distance L ３ distance L ４ distance L ５ distance L ６ Distance O Center axis P Axial center

Claims

1. A combustion assisting gas supply pipe that supplies a fuel gas containing ammonia and ejects the gas from a fuel gas nozzle at the tip; a first combustion assisting gas supply pipe that is provided radially outside the fuel gas supply pipe so as to surround the fuel gas supply pipe and that supplies a first combustion assisting gas and ejects the gas from a first combustion assisting gas nozzle at the tip; and a second combustion assisting gas supply section that supplies a second combustion assisting gas and ejects the gas from a second combustion assisting gas nozzle so as to join a burner flame downstream of the first combustion assisting gas nozzle, wherein the oxygen concentration of the first combustion assisting gas and the second combustion assisting gas is 30% or more, the oxygen concentration of the second combustion assisting gas is 90% or more, and the volumetric flow rate of oxygen at the first combustion assisting gas nozzle is V １ The volumetric flow rate of oxygen at the second combustion supporting gas nozzle is V ２ The volumetric flow rate of ammonia at the fuel gas nozzle is V ３ When 0.38≦(V １ +V ２ ) / V ３ ≦1.1, burner.

2. The momentum of the first combustion supporting gas ejected from the first combustion supporting gas ejection hole per unit time is q １ The momentum of the second combustion supporting gas ejected from the second combustion supporting gas ejection hole per unit time is q ２ When 0.1≦q １ / q ２ 2. The burner of claim 1, wherein the .lambda.R is .ltoreq.2.

0.

3. A burner as claimed in claim 1, having a burner body having a double-pipe structure consisting of said fuel gas supply pipe and said first combustion supporting gas supply pipe.

4. The fuel gas ejection hole is formed on the inner peripheral surface of the tip of the fuel gas supply pipe, and the inner diameter of the tip of the fuel gas supply pipe is d １ The outer diameter is D １ The distance from the tip is L １ The inner diameter at the position where ２ When this is done, 5 x d １ ≦L １ ≦10×d １ At the position where １ <d ２ and {(D １ -d １ ) / D １ }×100≦20.

5. The combustion-supporting first gas ejection hole is formed on the inner peripheral surface of the tip of the combustion-supporting first gas supply pipe, and the inner diameter of the tip of the combustion-supporting first gas supply pipe is d ３ The distance from the tip is L ２ The inner diameter at the position where ４ When this is done, 5 x d ３ ≦L ２ ≦10×d ３ At the position where ３ <d ４ The tip of the fuel gas supply pipe is located closer to the base end than the tip of the first combustion-supporting gas supply pipe, and the distance from the tip of the fuel gas supply pipe to the tip of the first combustion-supporting gas supply pipe is L ３ When this is done, L ３ <5×d ３ 2. The burner according to claim 1, wherein:

6. A burner body having the fuel gas supply pipe and the first combustion supporting gas supply pipe, and a burner block having an opening in which the burner body is disposed, and the maximum outer diameter of the first combustion supporting gas supply pipe at the portion disposed at the opening is D ４ The inner diameter at the tip of the opening is D ５ When this is done, D ４ ≦D ５ ≦1.1×D ４ The tip of the first combustion-assisting gas supply pipe is located closer to the base end than the tip of the opening, and the distance from the tip of the opening to the tip of the first combustion-assisting gas supply pipe is L ４ When this is the case, 0.2≦{(D ５ / 2) ２ ×π}÷L ４ ２ 2. The burner of claim 1, wherein the ΔT is ≦0.

5.

7. A heating furnace having at least one burner according to any one of claims 1 to 6 installed therein.

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