JPH06279845A - Forcedly convective heat-transferring surface combustion furnace - Google Patents

Abstract

PURPOSE:To obtain a surface combustion furnace achieving uniform atmospheric gas temp. distribution by arranging surface combustion burner at the roof part of the furnace wall and also an acoustic energy generating means at the side furnace wall part and forcedly stirring the atmospheric gas near just below the burner. CONSTITUTION:In the furnace wall roof part of the surface combustion furnace, the surface combustion burners 1 are embedded with a specific pitch in the longitudinal direction and the width direction of the furnace and at the furnace bottom part side, a hearth carrier 2 for conveying steel materials is arranged so as to be freely travelled. Further, the faced opening parts 3 are provided near the burner at the upper part of both side walls of the furnace body, and connected to an acoustic vibrator 6 through a U-shaped resonant tube 4. By this constitution, gas is supplied into the burners 1 through a header tube 5 to form the flame toward the inner part of the furnace from panel surfaces. The acoustic energy is supplied into the furnace from the opening hole part 3 through the resonant tube 4 from the acoustic vibrator 6 to vibration-stir the flame. By this method, the temp. and composition of the atmospheric gas in the furnace can be uniformized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forced convection heat transfer type surface combustion furnace used for heating steel materials and the like, and more particularly to a surface combustion furnace capable of achieving a uniform atmospheric gas temperature distribution.

[0002]

2. Description of the Related Art A surface combustion burner in which a mixed gas of combustion gas and air is supplied from the back and a plate-like flame is emitted from a ceramic porous panel on the surface for combustion, is used to heat various metallic materials and non-metallic materials. In recent years, it has been put to practical use, and is installed and used in a furnace for heating steel materials, for example.

When the surface combustion burner is applied to a gas heating furnace for heating a steel material, a plurality of surface combustions are formed on the ceiling portion of the furnace wall or the ceiling portion and the furnace bottom portion in the longitudinal and width directions of the furnace. A panel is attached, and a flame is emitted from the panel to heat the atmosphere gas in the furnace.

[0004]

However, in the conventional surface combustion technology, a stable amount of fuel / air mixture per opening area is required for stable combustion, and the entire surface of the furnace body over a wide range is required. It is industrially impossible to cover the surface with a surface burning panel. Therefore, as mentioned above, the combustion panels are arranged at a constant pitch, and the number of panels is reduced as much as possible within a range that does not hinder the temperature distribution.

Therefore, in the above-mentioned situation, the temperature difference between the atmospheres immediately below and between the panels is large and the temperature distribution is not uniform, so that the temperature difference of the atmosphere gas is eliminated by separating the steel material from the panel as much as possible. So that
Therefore, the panel could not be placed close to the steel material.
Moreover, in the case of gas heating, the limit of the temperature distribution of the atmosphere gas in the furnace is about ± 10 ° C. at most, and further improvement cannot be expected.

The present invention is capable of overcoming such a limitation of conventional gas heating and making the temperature distribution and the component distribution of the atmosphere gas in the furnace uniform, and is about ± 2 to 3 ° C., which is equivalent to that of electric heating. It is an object of the present invention to provide a surface-burning furnace capable of limiting distribution.

[0007]

The gist of the present invention for achieving the above object is as follows. (1) The surface combustion burners are arranged at a constant pitch in at least the ceiling portion of the furnace wall in the furnace longitudinal direction and the furnace width direction, and at least the side wall portion of the furnace wall is directed to the atmospheric gas in the vicinity immediately below the surface combustion burner. A forced convection heat transfer type surface combustion furnace provided with an acoustic energy generating means for applying an oscillating flow for forcibly stirring the gas into the furnace. (2) The surface combustion furnace according to (1) above, wherein the acoustic energy generating means is composed of an acoustic oscillator provided outside the furnace and a resonance tube connected to the oscillator and having an outlet opening on the side wall of the furnace body.

[0008]

[Operation] By applying acoustic energy, the flame (frame) near the surface burning burner vibrates and stirs, the adjacent frames of the burners interfere with each other, and it is as if multiple burners form one frame. Burning like
This makes the temperature and composition of the atmosphere gas in the furnace uniform.

The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 shows a specific example of a surface combustion furnace according to the present invention, in which a furnace body wall portion having a rectangular cross section is made of refractory material, a surface combustion burner 1 is buried in a furnace wall ceiling portion, and a furnace bottom portion side is provided. Is provided with a hearth trolley 2 that conveys a steel material so that it can travel. Further, an opening 3 facing each other is provided in the upper part of both side walls of the furnace body near the burner, and the outlet of the resonance tube 4 is located in the opening 3.

A plurality of surface combustion burners 1 are arranged at a constant interval in the width direction of the furnace body as shown in the figure, and are also arranged at a constant pitch in the longitudinal direction of the furnace body. A mixed gas is supplied, a frame is formed from the panel surface toward the inside of the furnace, and the atmosphere in the furnace is heated. The surface combustion burner 1 is shown as an example provided on the furnace ceiling portion as shown in the figure, but it may be arranged on the side wall portion and, in some cases, on the bottom side together with the ceiling portion. Can be appropriately determined in consideration of other conditions such as equipment and operation.

Further, the resonance tube 4 is symmetrically formed in a U shape, and the acoustic oscillator 6 is connected to the opposite side of the outlet side.
By operating the acoustic oscillator 6, acoustic energy is supplied from the opening 3 into the furnace through the resonance tube 4, and becomes a vibrating flow to vibrate and stir the frame from the burner 1. It is necessary to provide at least one set of this acoustic energy applying means along the side wall of the furnace body, but providing a plurality of sets will increase the vibration stirring efficiency.

FIGS. 2A and 2B show an example in which acoustic energy applying means are provided on the inlet side and the outlet side of the furnace body so as to face each other in the furnace longitudinal direction. The surface combustion burners 1 are arranged at a constant pitch in the furnace width and furnace length directions, and resonance tube outlets 3a are provided above the furnace body inlet side and outlet side so as to impart an oscillating flow in the furnace longitudinal direction. The frequency of the oscillated sound wave is preferably 20 Hz or less in order to suppress the generation of noise.

As described above, in the present invention, the direction of applying acoustic energy may be either the furnace width direction or the furnace length direction, but it may be at least a direction intersecting with the flame ejection direction from the surface combustion burner. Is forcibly stirred by the oscillating flow generated by the resonance energy,
Adjacent frames interfere with each other and each frame becomes one frame as a whole, and the atmosphere in the furnace is heated uniformly, and as a result, the atmosphere temperature and the atmosphere components are made uniform.

[0014]

EXAMPLE In a surface combustion furnace having the structure shown in FIG. 1, surface combustion burners were arranged in parallel in the furnace width direction, the surface combustion burners were burned under the following conditions, and an oscillating flow was applied to heat the atmosphere in the furnace. FIG. 3 shows the results of examining the temperature distribution in the case of a part in the furnace width direction. (Combustion / vibration conditions) Surface combustion burner: Arrange 400 × 400 mm panels at 200 mm pitch Fuel gas calorific value: 1800 kcal / Nm ³ Combustion surface load: 40 × 10 ⁴ kcal / m ² hr Oscillating flow sound pressure: 3 KPa 〜 30KPa (exit position), 20KPa in FIG.

As can be seen from FIG. 3, when the oscillating flow of the present invention is applied, the temperature difference between immediately below the surface combustion burner and the adjacent burner is within about 50 ° C., and the normal oscillating flow is applied. It is clear that the uniformity of the temperature distribution is remarkably improved as compared with the case where the temperature difference is 150 ° C. or more in the case of not performing. Also, in this case, it is possible to fill the space between the panels with a surface combustion burner in order to eliminate the temperature difference,
It requires 1.5 times the total amount of heat input, which is extremely uneconomical.

[0016]

As described above, according to the surface combustion furnace of the present invention,
It is possible to homogenize the atmospheric gas temperature in the furnace and the distribution of components relatively easily without significantly modifying the existing surface-burning furnace. The distribution can be achieved, and at the same time, the distribution can be made almost uniform near the surface combustion panel, so that the object to be heated and the burner can be close to each other, and the furnace structure can be made compact and simple. It will be possible. As described above, the present invention can be used for various heat treatments of steel materials, and its industrial effect is extremely large.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a surface combustion furnace according to the present invention.

FIG. 2 is a schematic side view showing another example of the furnace of the present invention and a panel layout view of the ceiling portion.

FIG. 3 is a graph showing the results of implementation of the present invention and a conventional example.

[Explanation of symbols]

 1 surface combustion burner 2 hearth trolley 3 opening 4 resonance tube 5 piping 6 acoustic oscillator

Claims (2)

[Claims] 1. A surface-combustion burner is arranged at least at a ceiling portion of a furnace wall at a constant pitch in a furnace longitudinal direction and a furnace width direction, and at least a side wall portion of the furnace wall is provided with an atmospheric gas in the vicinity of a position directly below the surface-combustion burner. A forced convection heat transfer type surface combustion furnace, characterized in that it is provided with an acoustic energy generating means for giving an oscillating flow that directs and forcibly stirs the gas into the furnace. 2. The surface combustion furnace according to claim 1, wherein the acoustic energy generating means comprises an acoustic oscillator provided outside the furnace and a resonance tube connected to the oscillator and having an outlet opening on a side wall of the furnace body.