JPH03260508A - strip jet burner - Google Patents

Abstract

PURPOSE:To provide a belt-like injection flow type burner capable of getting a belt-like high temperature and high-speed injection flow having its temperature and injection speed are made uniform in the width direction by a method wherein a combustion chamber made of refratory material is arranged at an injection side of a gas injection hole and an air injection hole, an outlet side of the combustion chamber is throttled to form an elongated slit-like combustion gas injection outlet in parallel with a longitudinal direction of a gas chamber. CONSTITUTION:In this belt-like injection flow type burner 45, fuel gas is supplied into a gas chamber 1 and injected out of a gas injection hole 5. Pre-heated hot air is supplied into an air chamber 6 and injected out of an air injection hole 17 and then the gas is ignited within a combustion chamber 30. The fuel gas substantially completes its combustion within the combustion chamber 30 to become a hot combustion gas. The gas is metered to become a high speed gas and then injected into a furnace from a combustion gas injection port 31. Accordingly, combustion of fuel gas is mainly carried out within the combustion chamber having less disturbance and enclosed by a refractory material, so that a stable combustion can be carried out for various fuel gases. It is possible to get a belt-like hot injection flow of which temperature or injection speed is made uniform in the width direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a burner that spouts a band-shaped high-temperature combustion gas.

[Prior art] For example, when trying to efficiently heat strip materials such as stainless steel plates, cold-rolled steel plates for plating, copper plates, and aluminum plates in a continuous furnace such as a continuous annealing furnace, these strip materials have low emissivity, so convection We have no choice but to rely on strengthening heat transfer. For this reason, in the past, a plurality of ordinary cylindrical flame burners were used in a staggered arrangement, but there was a problem in that the heating was uneven and a striped pattern was formed on the strip material due to uneven oxidation. Therefore, a premixing type slit burner was developed that injects a mixture of fuel and combustion air from a slit-shaped jet port and burns it. It was not possible to convert it into energy. In addition, there are diffusion combustion type slit-type burners disclosed in, for example, Japanese Patent Laid-Open Nos. 59-89919 and 89920, but these only have a mixing chamber and no combustion chamber. Because there is no fuel, combustion is unstable except for COG, which has a fast combustion rate.
There was a problem that when the jet velocity was increased, blowout occurred. In addition, since the combustion of the air-fuel mixture takes place in an open furnace, it is easily affected by the gas flow in the furnace, and combustion may be disturbed especially at the long ends of the slit due to flowing jets or entrainment of gas in the furnace. Uniform heating of the strip material is difficult because a uniform flame cannot be obtained, and in burners with only a mixing chamber, errors in the hole machining of the fuel gas and combustion air nozzle groups directly affect the temperature distribution of the jet stream. Ta.

[Problem to be solved by the invention]

This invention solves the above-mentioned conventional problems. It is possible to perform stable combustion of various fuel gases using preheated combustion air, and the temperature and ejection speed are made uniform in the width direction. An object of the present invention is to provide a band-shaped jet burner that can obtain a band-shaped high-temperature, high-speed jet stream.

[Means to solve the problem]

The strip-shaped jet burner of the present invention includes a long and narrow gas chamber connected to a fuel gas supply source, in which a large number of gas ejection holes are arranged in parallel in a direction substantially perpendicular to the longitudinal direction of the gas chamber. An air chamber extending parallel to the air chamber and connected to a combustion air supply source is provided with a number of air nozzles opening in the vicinity of the gas nozzle, and on the ejection side of the gas nozzle and the air nozzle, The present invention is characterized in that a combustion chamber made of a refractory material is provided, and the outlet side of the combustion chamber is narrowed to form a combustion gas outlet in the form of an elongated slit parallel to the longitudinal direction of the gas chamber.

In the present invention, the volume of the combustion chamber is preferably such that the combustion reaction of the fuel gas is completed by 90% or more,
The degree of completion of the combustion reaction can also be increased by narrowing the combustion chamber outlet. As a result, it is possible to eject a high-temperature jet gas that is strong and has little turbulence from the combustion gas ejection port.

Normally, the combustion chamber volume load is approximately 10 million to 50 million kc.
al/ml h, the slenderness ratio of the slit of the combustion gas nozzle is 1150 or less, and the dimensions of each part are preferably selected so that the jet flow velocity from the combustion gas nozzle is 40 m/s or more.

In the present invention, the refractory forming the combustion chamber is preferably fused alumina or a high alumina refractory brick whose main components are fused alumina and fused mullite (representative properties are shown in Table 1). It is preferable that the outer periphery is further supported by a support casing made of a heat-resistant metal material.

Further, it is preferable to provide a plurality of rectifying plates made of perforated plates arranged perpendicularly to the flow direction of the fuel gas or combustion air inside the gas chamber and the air chamber.

Table 1 [Function] In the strip-shaped jet burner of the present invention, the fuel gas ejected from the gas nozzle and the combustion air ejected from the air nozzle are mixed and combusted for the first time in the combustion chamber, and the combustion is almost completed at a high temperature. The combustion gas is ejected from the combustion gas outlet at high speed as combustion gas or combustion gas mixed with flame. Since it is not a premix type, flashback will not occur even if preheated air is used as combustion air. In addition, since combustion takes place mainly in a combustion chamber surrounded by refractories, stable combustion can be achieved even with fuel gases with high ignition temperatures, such as methane gas, and combustion disturbances due to entrainment of gas in the furnace can be achieved. Therefore, the velocity distribution and temperature distribution of the ejected gas in the longitudinal direction of the combustion gas ejection port are made uniform.

Furthermore, if a refractory made by assembling a group of refractory bricks whose main components are fused alumina or fused alumina and fused mullite is used as the refractory that forms the combustion chamber, these refractory bricks will As exemplified in 1, it has excellent spalling resistance and high-temperature hot strength, which suppresses the occurrence of cracks and defects in the walls of the combustion chamber where high-temperature combustion is performed, making it possible to create a band-shaped jet burner that can withstand long-term use. can get.

Further, since the support casing supports the refractory material forming the combustion chamber, it suppresses the slit width of the combustion gas outlet from expanding and facilitates attachment and detachment of the burner to the furnace body and the like.

Furthermore, the rectifying plate consisting of a perforated plate installed inside the gas chamber and air chamber is an inexpensive structure, and by installing it in multiple stages and repeating the collection and division of the airflow, it rectifies the fuel gas and combustion air. The jetting flow rate from the jetting hole or the air jetting hole is made uniform, and the temperature and velocity distribution of the jet gas from the combustion gas jetting port are made uniform.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG.

In the figure, reference numeral 1 denotes a gas chamber in the form of an elongated closed box that extends horizontally in the direction of the arrow is connected.

The lower part of the gas chamber 1 is stepped and thinned to form a gas nozzle part 4, and the lower end face thereof has gas ejection holes 5, 5 slightly inclined with respect to the vertical direction, in the longitudinal direction of the gas chamber, as indicated by the arrow in FIG. A large number of sets are arranged in parallel in the X direction. 6
The rectifying plate is provided in three stages in the gas chamber 1 and extends in the longitudinal direction of the gas chamber, and is made by punching a number of holes each having a diameter of 1.5 parts m in a stainless steel plate having a thickness of 1.2 parts m. Reference numeral 7 denotes a heat insulating material made of ceramic fiber, which serves to insulate the space between the gas vibrator 3 and the high-temperature preheated air flowing outside the gas vibrator 3 . On the other hand, 10 is a burner casing, which consists of an upper cover 12 divided by a flange 11.11 and a casing body 13. A gas chamber housing space 15 is defined within the casing body 13 by shield plates 14.14, into which the gas chamber 1 is inserted and removed. An air chamber 16.16 is formed which extends horizontally parallel to the air chamber 16.16. On the lower end surface of each air chamber 16, a large number of air ejection holes 17 that open near the gas ejection holes 5 are arranged in parallel in the longitudinal direction of the air chamber (in the direction of arrow X in FIG. 2). Reference numeral 18 denotes a rectifier plate similar to the rectifier plate 6 that extends in the longitudinal direction of the air chamber, and is installed in three stages within the air chamber 16. A flange portion 19 at the upper end of the shield plate 14 is provided with a tapered opening that expands upward, and the end plate 2 of the gas chamber 1 is fitted into this opening via a copper packing 20 for sealing. Reference numeral 21 indicates four air supply ports provided on the side of the upper cover, which are connected to a supply source of preheated combustion air. 22 is an external heat insulating material made of rock wool.

Reference numeral 30 denotes a combustion chamber formed on the ejection side of the gas ejection holes 5 and the air ejection holes 17, which has a substantially rectangular parallelepiped shape extending in the horizontal direction, and has a volume necessary to almost complete combustion of the fuel gas. The lower part of the combustion chamber 30 is constricted to form a slit-shaped combustion gas outlet 31 extending in the horizontal direction.

32 is a refractory that surrounds the combustion chamber 30, and includes an inner layer 34 made of 50 M thick fused alumina bricks 33 lined up and joined together with refractory mortar 33A, and an outer layer 1135 made of 1600° C. class refractory castable, two layers thick. It is composed of three layers including an intermediate layer 36 made of an alumina fiber sheet. The outer layer 35 is supported by a support casing 37 made of heat-resistant steel. 38 is a sea lion hardware fixed to the support casing 37. Reference numeral 50 denotes a furnace wall of a continuous furnace for heating strip material (not shown), and a supporting casing 37
A flange 39 attaches the refractory 32 to the furnace wall 50, and a lower flange 23 of the burner casing 10 supports the burner casing 10 and its contents. 40
is a fireproof sealing material inserted between the casing body 13 and the refractory 32. Also, 41 is a pilot burner,
It is used for ignition at the start of combustion of fuel gas.

In the strip jet burner 45 having the above configuration, fuel gas is supplied into the gas chamber 1 and ejected from the gas ejection holes 5, and preheated high-temperature air is supplied into the air chamber 16 and ejected from the air ejection holes 17. and burn it in the combustion chamber 30. The fuel gas almost completes combustion in the combustion chamber 30 and becomes high-temperature combustion gas, which is throttled and ejected at high speed from the combustion gas outlet 31 into the furnace. Although the temperature inside the combustion chamber 30 may reach a high temperature of around 1700° C., the fused alumina brick 33 exhibits sufficient heat resistance even at the above-mentioned high temperature. Also, fused alumina has high thermal conductivity (λ=2
．． 0 kcal/mh'c), the thermal conductivity is small (λ-0
, 6 to 0.8 kcal/mh℃) An inexpensive refractory castable is used as the outer layer 135, and a high alumina ceramic fiber sheet is used to absorb the difference in thermal expansion caused by the temperature difference and physical property difference between the fused alumina and the refractory castable. is used as the intermediate layer 36, thereby providing an economical refractory structure with excellent durability and high temperature strength.

In the burner casing 10, the fuel gas is rectified by the rectifier plate 6, and the combustion air is rectified by the rectifier plate 18, so that a substantially uniform flow rate distribution in the longitudinal direction of the gas chamber 1 and the air chamber 16 is obtained. The jetting flow rate of the gas jetting hole 5 and the air jetting hole 17 is made uniform, and the temperature and velocity distribution of the jet gas from the combustion gas jetting hole 31 are made uniform. The hot jet gas obtained in this way is
The combustion gas is ejected from the combustion gas outlet 31 into the continuous furnace at high speed, and is used to heat the continuously running strip material to a uniform temperature.

The present invention is not limited to the above embodiment; for example, in the above embodiment, the gas chamber 1 and the air chamber 16 are
Since the gas chamber 1 can be separated and removed, it has the advantage that inspection and assembly of the gas nozzle part 4 are easy. Also, gas chamber 1
The specific shape of the air chamber 16 may also be other than the above. Further, in the above embodiment, the refractory material 32 is
Although the burner of the present invention is used in a low-temperature furnace or when the preheated air temperature is about 200°C, the intermediate layer 36 and the outer layer 35 can be omitted and the inner layer 35 can be omitted. The structure of the refractory 32 may also be other than the above, such as a one-layer refractory made of fused alumina corresponding to 1t34 or a refractory brick group whose main components are fused alumina and fused mullite. Further, the band-shaped jet burner of the present invention may be used for purposes other than heating strip materials. Furthermore, combustion gas may be mixed into the combustion air or fuel gas of the burner of the present invention for low NOx combustion.

〔Effect of the invention〕

As explained above, according to the present invention, the combustion of fuel gas is mainly carried out in a combustion chamber surrounded by refractories with little disturbance, so that stable combustion can be performed for various fuel gases, and temperature and It is possible to obtain a band-shaped high-temperature jet stream with a uniform ejection velocity in the width direction, and since the flame during combustion or the jet stream with uneven temperature does not come into contact with a wide heated object, it is possible to A belt-shaped jet burner suitable for uniformly heating an object to be heated is provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a band-shaped jet burner showing an embodiment of the present invention (a cross-section taken along the line A-A in FIG. 2), and FIG.
It is a sectional view taken along the B line. 1... Gas chamber, 5... Gas outlet, 16...
- Air chamber, 17... Air outlet, 30... Combustion chamber, 31... Combustion gas outlet, 32... Refractory,
33... Electrofused alumina brick, 33A... Fireproof mortar, 34... Inner layer, 35... Outer layer, 36...
- Intermediate layer, 37... Support casing, 45... Band-shaped jet burner.

Claims (1)

[Scope of Claims] 1. A long and narrow gas chamber connected to a fuel gas supply source is provided with a large number of gas ejection holes arranged in parallel in a direction substantially perpendicular to the longitudinal direction of the gas chamber; An air chamber extending parallel to the air chamber and connected to a combustion air supply source is provided with a number of air nozzles opening in the vicinity of the gas nozzle, and on the ejection side of the gas nozzle and the air nozzle,
A belt-shaped jet burner characterized in that a combustion chamber made of a refractory is provided, and an outlet side of the combustion chamber is constricted to form a combustion gas outlet in the form of an elongated slit parallel to the longitudinal direction of the gas chamber. 2. The belt-shaped jet burner according to claim 1, wherein the refractory forming the combustion chamber is formed by assembling and assembling fused alumina or a group of refractory bricks whose main components are fused alumina and fused mullite using refractory mortar. 3. The belt-shaped jet burner according to claim 1 or 2, wherein the outer periphery of the refractory forming the combustion chamber is supported by a support casing made of a heat-resistant metal material. 4.Claim 1, 2 or 3, wherein inside the gas chamber and the air chamber, a plurality of rectifying plates made of perforated plates arranged perpendicularly to the flow direction of the fuel gas or combustion air are provided. The described strip jet burner.