JPH07145916A - Oxygen burner - Google Patents

Abstract

PURPOSE:To ensure furnace temperature distribution which is suited to even heating of an object by forming a burner having a triple nozzle in the middle, i.e., a primary oxygen nozzle, a fuel nozzle, and a steam nozzle arranged from the center, and by arranging a plurality of secondary oxygen nozzles at the baffle provided at the periphery 7 the steam nozzle on the side of the forward end. CONSTITUTION:From a primary oxygen nozzle 2 at the center of a burner 1 primary oxygen in the amount of 10-30% of the total supply of oxygen is directly fed into a furnace, this primary oxygen is induced by a high velocity fuel from a fuel nozzle 3 and primary combustion is effected in a manner of stabilizing a flame. On the other hand, from a plurality of secondary oxygen nozzles 6 secondary oxygen is ejected at high velocity and mixed in a manner of induced mixing with the gas of low oxygen concentration inside the furnace. Furthermore, steam ejected from a steam nozzle 4 forms a film of steam at the periphery of the flame of primary combustion so that the mixing of the secondary oxygen with the primary combustion gas which contains unburnt combustibles in large quantities is restrained. As a result, the burning reaction is restrained and flames become long and it is possible to ensure flat furnace temperature distribution which is suited to even heating of an object for the heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating furnace, a soaking furnace, and a heat treatment furnace for heating objects to be heated such as slabs, billets and strips to a predetermined target temperature (generally referred to as heating furnace in the present invention).
Oxygen burner for

[0002]

2. Description of the Related Art Conventionally, in this type of heating furnace, an air burner which burns a fuel with air to heat an object to be heated has been generally used, but recently, a fuel is burned with oxygen or oxygen-enriched air. Oxygen burners, which heat the object to be heated, are drawing attention. Compared with the conventional air burner, this oxygen burner has a combustion gas amount of about 1/4 and a high concentration of carbon dioxide (CO ₂ ) and water vapor (H ₂ O). In addition to the large energy-saving effect due to the increase in gas radiative heat transfer, it also has the advantage that carbon dioxide, a global warming substance, can be easily recovered.

On the other hand, the oxygen burner has a high flame temperature and a small amount of combustion gas, so that the uniform heating property of the object to be heated is poor, and a large amount of nitrogen oxide (NO _x ) is produced, so that it cannot be applied to a heating furnace. There was a problem. On the other hand, for example, there is a two-stage combustion burner as disclosed in JP-A-56-82306. The feature of this technique is to suppress high-temperature flame and nitrogen oxides. To achieve this, as shown in FIG. 3, the burner tile 10 has primary combustion chamber 11 and secondary combustion chamber 12 with different diameter steps. The fuel supplied from the fuel nozzle 3 is provided to the primary air nozzle 13 and the secondary air nozzle 1.
The combustion air supplied from No. 4 is used for two-stage combustion.

[0004]

In the method of the above construction, the two-stage combustion of the fuel is carried out in the primary combustion chamber 11 and the secondary combustion chamber 12 in the burner tile 10. Therefore, in the oxygen burner with a high burning velocity, the furnace temperature distribution Was extremely high and there was a problem that the object to be heated could not be heated uniformly. As a method of solving this problem, the applicant has already proposed in Japanese Patent Application No. 5-43809 a burner tile, that is, an oxygen two-stage combustion burner without a combustion chamber. The present invention was devised to solve the above problems, and its purpose is to secure a flat furnace temperature distribution necessary for uniform heating of an object to be heated, and for a heating furnace that suppresses nitrogen oxides. To provide an oxygen burner.

[0005]

SUMMARY OF THE INVENTION The present invention has the following structure. (1) In an oxygen burner that burns fuel with oxygen or oxygen-enriched air, the burner has a triple tube nozzle at its center, and the triple tube nozzle is a primary oxygen nozzle, a fuel nozzle, and a steam nozzle from the center side. In addition, a plurality of secondary oxygen nozzles are arranged on a baffle provided on the outer circumference of the water vapor nozzle on the tip side. (2) A plurality of shielding plates are provided at the tip of the water vapor nozzle.

[0006]

The oxygen burner of the present invention is a burner tileless oxygen two-stage combustion burner that forms a steam film on the outer periphery of the primary combustion flame, and the steam film forms a primary combustion gas containing a large amount of unburned components. Since the slow combustion is performed by suppressing the mixing of the secondary oxygen, the flame becomes longer and the flat furnace temperature distribution required for uniform heating of the object to be heated can be secured and the nitrogen oxides can be suppressed. If necessary, install a shielding plate at the tip of the steam nozzle to
Since the area of the steam film around the secondary combustion flame is adjusted and the mixed combustion reaction of the primary combustion flame and secondary oxygen is adjusted, an arbitrary furnace temperature distribution can be formed even with fuels having different burning speeds.

[0007]

1 is a longitudinal sectional view showing an embodiment of the oxygen burner of the present invention, and FIG. 2 is a side view of the oxygen burner of FIG. 1 seen from the inside of the furnace. As shown in FIGS. 1 and 2, a triple tube nozzle is arranged at the center of the burner 1, and the primary oxygen nozzle 2, the fuel nozzle 3, and the steam nozzle 4 are arranged in this order from the center side of the triple tube nozzle. 10 to 30% of the total amount of oxygen required for combustion is supplied from the secondary oxygen nozzle 2, and fuel such as coke oven gas and natural gas is usually supplied from the fuel nozzle 3 at 60 m / s.
The steam is jetted at the above high speed, and steam is jetted from the steam nozzle 4 into the heating furnace at a speed of usually 30 m / s or more.

Further, for a fuel having a slow burning rate such as natural gas, a shielding plate 9 is provided at the tip of the steam nozzle 4 to adjust the area of the steam film around the primary combustion flame, if necessary. Further, a baffle 5 is provided on the outer circumference on the tip side of the steam nozzle 4, and a plurality of secondary oxygen nozzles 6 are arranged on the virtual circumferential line of the baffle 5 to heat the secondary oxygen at a high speed of usually 60 m / s or more. Gush out inside. The secondary oxygen nozzles 6, which have a circular cross section, are arranged in the circumferential direction at equal pitches in an amount of 4 to 8 pieces.

The burner 1 thus constructed is attached to the furnace wall 7 so that the inner surface of the furnace wall 7 of the heating furnace and the tip of the burner 1 are substantially flush with each other, and the gap between the burner 1 and the furnace wall 7 is filled. Material 8 is filled. The burner nozzles 2, 3, 4, 6
Since a sealing property, heat resistance and oxidation resistance are required, a stainless steel material is usually used, and a baffle 5 is usually made of an alumina high temperature refractory material because heat resistance and oxidation resistance are required.

Next, the operation function of the present invention will be described.
A primary oxygen amount of 10 to 30% of the total oxygen supply amount (= primary oxygen amount + secondary oxygen amount) is directly supplied from the center of the burner 1 into the furnace, and this primary oxygen is attracted by high-speed fuel on the outer circumference. Then, the primary combustion is performed, and the flame is stabilized by the primary combustion flame. on the other hand,
Secondary oxygen is injected at high speed from a plurality of secondary oxygen nozzles arranged outside the primary combustion flame, and this injection energy induces and mixes a low-oxygen concentration in-furnace gas to induce secondary oxygen concentration. To lower. Further, a water vapor film is formed on the outer periphery of the primary combustion flame to suppress the mixing of the primary combustion gas containing a large amount of unburned components with the secondary oxygen.

As a result, the combustion reaction between the primary combustion gas and the secondary oxygen is suppressed and the flame becomes a long flame, so that a flat furnace temperature distribution suitable for uniform heating of the object to be heated is secured and nitrogen oxides are generated. Can be suppressed. Further, since steam is a radioactive gas, the amount of heat transfer does not decrease due to the gas radioactivity even when added in large amounts, and it is also advantageous in terms of thermal efficiency if steam is generated by utilizing the sensible heat of combustion exhaust gas. It should be noted that the present invention is not limited to the above embodiment, and for example, (1) a swirl vane is attached to any nozzle for primary oxygen, fuel, and steam for adjusting the flame shape. (2) The injection angle of the secondary oxygen nozzle is arbitrarily inclined with respect to the burner central axis. It is also possible to make various modifications without departing from the gist of the present invention.

[0012]

EFFECTS OF THE INVENTION According to the oxygen burner of the present invention, (1) fuel and oxygen are directly injected into the furnace to perform two-stage combustion, and
Since a steam film is formed on the outer periphery of the primary combustion flame to suppress secondary combustion, it is possible to secure a flat furnace temperature distribution required for uniform heating of the heated object by lowering the flame temperature and lengthening the flame. Nitrogen oxide can be suppressed. (2) Since the shielding plate is provided at the tip of the steam nozzle to adjust the area of the steam film, the furnace temperature distribution suitable for uniform heating can be secured even for the fuel having a slow burning rate. And so on.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of an oxygen burner according to the present invention.

FIG. 2 is a front view of the oxygen burner of FIG. 1 viewed from the inside of a furnace.

FIG. 3 is a vertical sectional view of a two-stage combustion burner showing a conventional technique.

[Explanation of symbols]

 1 Burner 2 Primary Oxygen Nozzle 3 Fuel Nozzle 4 Steam Nozzle 5 Baffle 6 Secondary Oxygen Nozzle 7 Furnace Wall 8 Filling Material 9 Shielding Plate 10 Burner Tile 11 Primary Combustion Chamber 12 Secondary Combustion Chamber 13 Primary Air Nozzle 14 Secondary Air nozzle

Claims (2)

[Claims] 1. An oxygen burner that burns fuel with oxygen or oxygen-enriched air, wherein the burner has a triple tube nozzle at the center thereof, and the triple tube nozzle is a primary oxygen nozzle from the center side, a fuel nozzle, An oxygen burner comprising a water vapor nozzle and a plurality of secondary oxygen nozzles arranged on a baffle provided on the outer periphery of the water vapor nozzle on the tip side. 2. The oxygen burner according to claim 1, wherein a plurality of shielding plates are provided at the tip of the water vapor nozzle.