Burner

Abstract

This burner uses a fuel gas containing ammonia and a combustion-supporting gas having an oxygen concentration of 30% or more.

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] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a burner that uses ammonia as fuel and can ensure radiation intensity and flame stability.

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

[0009] [1] A burner that uses a fuel gas containing ammonia and a combustion-supporting gas with an oxygen concentration of 30% or more.

[0010] [2] The burner according to [1], comprising: a fuel gas supply pipe that supplies the fuel gas and ejects the fuel gas from a fuel gas ejection hole at the tip; and a combustion-supporting gas supply pipe that is arranged radially outside the fuel gas supply pipe so as to surround the fuel gas supply pipe, and that supplies the combustion-supporting gas and ejects the gas from a combustion-supporting gas ejection hole at the tip.

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

[0013] [5] The combustion-supporting gas ejection holes are formed on the inner peripheral surface of the tip of the combustion-supporting gas supply pipe, and the inner diameter of the combustion-supporting gas supply pipe at the tip 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 combustion-supporting gas supply pipe, and the distance from the tip of the fuel gas supply pipe to the tip of the combustion-supporting gas supply pipe is L ３ When this is done, L ３ <5 × d ３ The burner according to any one of [2] to [4],

[0014] [6] A burner block having a burner body having the fuel gas supply pipe and the combustion-supporting gas supply pipe, and an opening in which the burner body is disposed, wherein the maximum outer diameter of the 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, D４ ≦D ５ ≦1.1×D ４ the tip of the combustion-supporting 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 combustion-supporting 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 [2] to [5], wherein the ratio 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, it is possible to provide a burner that uses ammonia as fuel and can ensure radiation intensity and flame stability.

[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 the burner shown in FIG. 1; FIG. 3 is a graph showing the relationship between the oxygen concentration of an oxidizer and the adiabatic theoretical flame temperature; and FIG. 4 is a graph showing the relationship between the oxygen concentration of an oxidizer and the 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 6 has at least one burner 1. The heating furnace 6 has a furnace side wall 6a on which the burner 1 is installed. The burner 1 is embedded in the furnace side wall 6a. However, the arrangement of the burner 1 in the heating furnace 6 is not limited to this. The burner 1 burns fuel gas in the internal space 6b of the heating furnace 6 to heat the object to be heated and melt it as necessary.

[0020] The burner 1 uses a fuel gas containing ammonia and a combustion-supporting gas with an oxygen concentration of 30% or more.

[0021] The above configuration realizes a burner 1 that uses ammonia as the fuel gas and can ensure radiation intensity and flame stability. The fuel gas is not particularly limited as long as it contains ammonia, but preferably contains ammonia as the main component (i.e., an ammonia content of more than 50% but not more than 100%). The combustion-supporting gas is not particularly limited as long as it has an oxygen concentration of 30% or more, but it is preferable to use oxygen-enriched air so that the oxygen concentration in the combustion-supporting gas is 30% or more.

[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 includes a fuel gas supply pipe 2a that supplies fuel gas (preferably without premixing oxygen) and ejects it from fuel gas ejection holes 2a1 at its tip, and a combustion-sustaining gas supply pipe 2b that is disposed radially outside the fuel gas supply pipe 2a and surrounds 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-sustaining gas is formed between the outer peripheral surface of the fuel gas supply pipe 2a and the inner peripheral surface of the combustion-sustaining gas supply pipe 2b that is spaced from the outer peripheral surface all around as shown in the figure), and supplies the combustion-sustaining gas (preferably without premixing fuel) and ejects it from the combustion-sustaining gas ejection holes 2b1 at its tip. With the above configuration, the fuel gas ejected from the fuel gas ejection holes 2a1 and the combustion-sustaining gas ejected from the combustion-sustaining gas ejection holes 2b1 can be supplied to the burner flame, thereby achieving stable ammonia combustion while suppressing flashback. The fuel gas supply pipe 2a preferably surrounds the central axis O of the combustion supporting gas supply pipe 2b as shown in the figure, and more preferably is provided coaxially with the combustion supporting gas supply pipe 2b as shown in the figure. 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 gas supply pipe 2b at the tip of the combustion supporting gas supply pipe 2b are each circular in this embodiment, but are not limited to this.

[0026] The burner 1 has a burner body 2 having a double-pipe structure consisting of a fuel gas supply pipe 2a and a 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 2a1 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 where １ <d ２ By setting the above, the flow path of the fuel gas in the vicinity of the fuel gas ejection hole 2a1 becomes narrower toward the fuel gas ejection hole 2a1, and therefore the supply pressure of the fuel gas increases toward the fuel gas ejection hole 2a1. As a result, the supply pressure of the fuel gas at the fuel gas ejection hole 2a1 is made uniform, and therefore the uniformity of the ejection amount of the fuel gas at the fuel gas ejection hole 2a1 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 combustion assisting gas flow path at the tip of the fuel gas supply pipe 2a is small enough for practical use, thereby realizing rapid mixing of the fuel gas and the combustion assisting gas. Therefore, good mixing can be achieved, resulting in good flame stability.

[0028] The combustion-supporting gas ejection holes 2b1 are formed on the inner peripheral surface of the tip of the combustion-supporting gas supply pipe 2b, and the inner diameter at the tip of the 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 combustion-supporting gas supply pipe 2b, and the distance from the tip of the fuel gas supply pipe 2a to the tip of the combustion-supporting 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 gas narrows toward the combustion supporting gas ejection holes 2b1, the supply pressure of the combustion supporting gas increases toward the combustion supporting gas ejection holes 2b1, and as a result, the supply pressure of the combustion supporting gas at the combustion supporting gas ejection holes 2b1 is made uniform, thereby improving the uniformity of the ejection amount of the combustion supporting gas at the combustion supporting 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 The axial direction of the slit 1 extends linearly in parallel with the central axis O within the range of

[0029] The burner 1 has a burner body 2 having a fuel gas supply pipe 2a and a combustion-supporting gas supply pipe 2b, and a burner block 4 having an opening 4a where the burner body 2 is arranged (preferably coaxially as shown in the figure). The maximum outer diameter of the 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 combustion-supporting 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 combustion-supporting 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 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] 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.

[0031] DESCRIPTION OF SYMBOLS 1 Burner 2 Burner body 2a Fuel gas supply pipe 2a1 Fuel gas ejection hole 2b Combustion-supporting gas supply pipe 2b1 Combustion-supporting gas ejection hole 3 Mixing chamber 4 Burner block 4a Opening 5 Combustion chamber 6 Heating furnace 6a Furnace side wall 6b 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 O Center axis

Claims

1. A burner that uses a fuel gas containing ammonia and a combustion supporting gas with an oxygen concentration of 30% or more.

2. A burner as described in claim 1, comprising: a fuel gas supply pipe which supplies the fuel gas and sprays the gas from a fuel gas nozzle at its tip; and a combustion-supporting gas supply pipe which is arranged radially outside the fuel gas supply pipe so as to surround the fuel gas supply pipe, and which supplies the combustion-supporting gas and sprays the gas from a combustion-supporting gas nozzle at its tip.

3. A burner according to claim 2, having a burner body having a double-pipe structure consisting of the fuel gas supply pipe and the 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 gas ejection hole is formed on the inner peripheral surface of the tip of the combustion supporting gas supply pipe, and the inner diameter of the tip of the combustion supporting 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 combustion supporting gas supply pipe, and the distance from the tip of the fuel gas supply pipe to the tip of the combustion supporting gas supply pipe is L ３ When this is done, L ３ <5×d ３ 3. The burner according to claim 2, wherein:

6. A burner block having a burner body having the fuel gas supply pipe and the combustion supporting gas supply pipe, and an opening in which the burner body is disposed, and the maximum outer diameter of the 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 combustion-supporting 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 combustion-supporting gas supply pipe is L ４ When this is the case, 0.2≦{(D ５ / 2) ２ ×π}÷L ４ ２ 3. The burner of claim 2, wherein the ratio of the stoichiometric ratio of the burner to the total stoichiometric ratio is ≦0.

5.

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