JPH0223950Y2 - - Google Patents

Description

[Detailed Description of the Invention] Purpose of the Invention (Field of Industrial Application) The present invention relates to a burner. More specifically, the present invention relates to a radiant tube burner that converts combustion energy into radiant energy and uses it as a heat source.

(Prior Art) Converting combustion energy to radiant energy and using it as a heat source has been conventionally practiced in radiant gas burners, radiant tube burners, and the like. In particular, radiant tube burners are used as heat sources for heat treatment furnaces, combustion furnaces, etc. that use special atmospheric gases because they do not contaminate the atmospheric gas inside the furnace. This radiant tube burner heats the tube 101 by burning oil or gas within the heat-resistant alloy tube 101, as shown in FIG. 2, and heats the object to be heated with the heat radiated from the tube's outer surface. Also,
There is also a radiant tube burner with a requiperator that exchanges heat between exhaust gas and combustion air and preheats the combustion air to increase overall thermal efficiency (see Figure 3).
This radiant tube burner with a requiperator has a requiperator pipe 104 surrounding the exhaust pipe 103.
It is surrounded by a double pipe, and combustion air is introduced through the outer pipe. In addition, 10 in the figure
2 is a burner, and 105 is a furnace wall.

(Problem to be solved by the invention) However, this radiant tube burner heats the tube 101 while the long flame obtained by burning the burner at one end of the U-shaped tube is discharged from the exhaust pipe 103 at the other end. Since the temperature of the flame near the burner 101 is significantly different from that near the exhaust pipe, for example, in order to maintain the furnace temperature at around 1000°C, the temperature of the exhaust gas that is the lowest in the tube 101 is 1000 near the pipe
Since it must be kept at a temperature of 1200°C or more near the burner.
The temperature must be as high as about 1300° C., which results in uneven heating of the tube 101. For this reason, the tube near the burner 102 is constantly exposed to high temperatures compared to the tube near the exhaust pipe, and as a result, it undergoes severe oxidation and, in some cases, melts and is damaged, resulting in a short tube life. Furthermore, even in the case of a radiant tube burner with a requiperator having a double tube structure, heat efficiency is poor due to indirect heat exchange via the tube wall, and exhaust heat recovery is insufficient.

Therefore, an object of the present invention is to provide a radiant tube burner that can uniformly heat the tubes and efficiently recover waste heat.

Structure of the invention (means for solving the problem) In order to achieve the above object, the radiant tube burner of the invention fills both openings of the radiant tube with a permeable solid and burns only through the permeable solid. While making it possible to send in air for combustion and discharge combustion exhaust gas, each opening is equipped with a burner, and each opening is provided so that it can be selectively connected to a combustion air supply means and an exhaust gas means. Combustion gas is alternately discharged from each opening, while combustion air is preheated and supplied through the air permeable solid at the other opening using the heat of the combustion exhaust gas stored in the air permeable solid, and the burner is alternately fired. I try to let them do it.

(Example) The configuration of the present invention will be described in detail below based on an example shown in the drawings.

In the radiant tube burner of the present invention, both openings 2 of a radiant tube 1 are filled with air permeable solid 3 and are each equipped with a burner 4. This is a two-way flow type burner in which combustion gas is exhausted through a permeable solid 3.

The breathable solid 3 is for temporarily storing the sensible heat of the exhaust combustion gas (referred to as combustion exhaust gas in this specification), and is generally used as a heat storage body and does not have an adverse effect on combustion air or combustion exhaust gas. Any structure and material can be used as long as it does not give any damage. In general, heat storage materials are required to have a large heat transfer area, low pressure loss, and excellent heat resistance, thermal shock resistance, and corrosion resistance, so ceramics, alumina,
Heat-resistant metal etc. are used. In the case of this embodiment, so-called honeycomb ceramics in which a large number of honeycomb-shaped cell holes are formed along the flow direction of combustion gas using spongy ceramics is used. In this specification, the term "breathable solid" includes not only those whose material or material itself is porous, but also those whose structure can ensure air permeability even if the material itself is not breathable. For example, in addition to refractories that have many continuous pores with a relatively small average pore diameter, they can also be used to fill balls of alumina checkers, wire mesh woven with heat-resistant metal fibers, foamed metals, and highly filled ceramics. It can be constructed into any suitable structure or shape, such as a revolver-like cylinder made up of the following. In addition, when using spongy ceramics, in addition to penetrating the cell holes, it is also possible to seal the bottoms of the honeycomb-shaped cell holes alternately in a pine pattern so that the combustion gas can pass through the porous thin walls. It is also possible to increase the heat exchange efficiency. In addition, when the combustion exhaust gas temperature is around 1000℃, iron-chromium-
It is also possible to use a breathable solid material having a structure in which wire mesh made of heat-resistant aluminum alloy FCH-2 woven with a diameter of about 1 mm is layered to an appropriate thickness.

Radiant tube 1 along with this breathable solid 3
The burners 4 installed in both openings 2 of the
It is not necessary to have a special structure, and a burner of a type and type suitable for combustion within the radiant tube 1 may be appropriately selected from known or new burners. For example, since long flame combustion is required for combustion within the radiant tube 1, a nozzle with a high blowing speed is usually employed. The burner 4 is preferably arranged such that the fuel injection nozzle 5 passes through the air permeable solid 3 in order to prevent mixing and diffusion of fuel and combustion air within the air permeable solid 3. Of course, when honeycomb-shaped ceramics are used as the air permeable solid 3, there is no need to install the burner nozzle 5 through the air permeable solid 3 because the fuel and combustion air are shielded by the ceramic partition.

Both openings 2 of the radiant tube 1 are provided so as to be selectively connectable to a combustion air supply means 6 and an exhaust gas means 7. In the case of this embodiment, the other two ports 8c and 8 of the four-way valve 8 have one 8a open to the atmosphere and the other 8b connected to the exhaust fan 9.
Both openings 2 of the radiant tube 1 are connected to d, and each opening 2 is selectively connected to combustion air supply means, that is, the atmosphere, or exhaust means, that is, an exhaust fan 9, by operating the switching damper 10 of the four-way valve 8. It is provided so that it can be connected to. The flow of combustion air and combustion gas can be switched at regular intervals using a timer (not shown) or by measuring the combustion temperature that has passed through the permeable solid 3 with a thermosensor (not shown) until it reaches a predetermined temperature. When you do,
The damper 10 is driven so as to switch the flow in synchronization with fuel injection.

In addition, the means for switching the flow direction of the fuel gas is not limited to the one using the four-way valve 8 described above, but also the one using a known or new flow path switching means, such as a spool valve, or one using a plurality of communication holes. Various methods have been implemented, such as one in which the flow is switched by rotating a circular plate, and a dedicated flow path connected to the combustion air supply means 6 and the exhaust gas means 7 is provided in each opening 2 to open and close them. It is possible.

It should be noted that the exhaust means 5 does not need to have a special structure, and it is sufficient to appropriately select a type and type of exhaust means suitable for the burner from among known or new exhaust means.For example, in this embodiment, a blower is used. has been adopted. Further, the combustion air supply means 6 does not need to have a special structure, and may be selected from known or new air supply means suitable for the burner.
The type of exhaust means may be selected as appropriate; for example, in this embodiment, an air blower is not used, the exhaust means is simply opened to the atmosphere, and induced ventilation using an exhaust fan is employed. Furthermore, the radiant tube 1 can be of known shapes such as straight, U-shaped, T-shaped, W-shaped, O-shaped, L-shaped, etc., as well as new shapes. In this specification, both openings 2 of the radiant tube 1 refer to those connected to an exhaust system and those connected to an air supply system.

(Function) According to the radiant tube burner of the present invention configured as described above, either one of the burners 4
At the same time, the high-temperature combustion gas inside the tube 1 is discharged from the other opening 2 by the operation of the exhaust fan 9, and the inside of the tube 1 is made negative pressure to induce combustion air. After a certain period of time has elapsed, the burner 4 on the opposite side is combusted and the combustion gas is discharged from the opening 2 on the burner side where it had been combusted until then. By repeating this alternate combustion and discharge, the temperature of the tube 1 and the breathable solid 3 is gradually increased. When the tube 1 and the permeable solid 3 reach the set temperature, steady combustion begins. The combustion air and the combustion gas are switched at appropriate intervals, for example, at intervals of 0.5 to 2 seconds, or when the combustion gas to be discharged is at a low temperature, for example, about 200°C. On the other hand, the combustion air is supplied after being preheated to a high temperature, for example, 700 to 800°C, by picking up the heat that the combustion exhaust gas gives up in the air-permeable solid 3.

Effects of the invention As is clear from the above explanation, the radiant tube burner of the invention fills both openings of the radiant tube with a permeable solid, and allows combustion air to be sent in and combustion exhaust gas to be discharged only through the permeable solid. On the other hand, a burner is attached to each of the openings, and each opening is provided so that it can be selectively connected to the combustion air supply means and the exhaust gas means, so that the burners are fired alternately. The surface of the tube can be heated uniformly, the object to be heated can be heated more effectively, and the life of the tube can be extended. In addition, this radiant tube burner discharges the combustion gas inside the tube alternately from each opening, and at the same time exhausts the combustion air through the air permeable solid at the other opening using the heat of the combustion exhaust gas stored in the air permeable solid. Since the exhaust gas is supplied after being preheated, it is possible to recover heat to lower the exhaust gas temperature to 100 to 200°C.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram showing an embodiment of the radiant tube burner of the present invention, Fig. 2 is a central vertical cross-sectional view showing an example of a conventional radiant tube burner, and Fig. 3 is a similar conventional radiant tube with a requiperator. This is a central section. 1... Radiant tube, 2... Breathable solid, 3... Breathable solid, 4... Burner, 6... Combustion air supply means, 7... Exhaust gas means, 8... Channel switching means/four-way valve .

Claims (1)

[Claims for Utility Model Registration] (1) Both openings of the radiant tube are filled with a breathable solid so that combustion air can be fed in and combustion exhaust gas can be discharged only through the breathable solid, while each of the openings is A burner is attached to each tube, and each opening is selectively connected to a combustion air supply means and an exhaust gas means, so that the combustion gas in the tube is alternately discharged from each opening, while the other opening is A radiant tube burner characterized in that combustion air is preheated and supplied through a gas permeable solid using the heat of combustion exhaust gas stored in the gas permeable solid, and the burners are alternately combusted. (2) The radiant tube burner according to claim 1, wherein the air-permeable solid is honeycomb-shaped ceramics. (3) Utility model registration claim 1, characterized in that the breathable solid has honeycomb-shaped passages that communicate in the direction of flow of combustion gas and whose ends are alternately sealed with bottoms in a checkered pattern. Radiant tube burner as described. (4) The radiant tube burner according to claim 1, wherein the breathable solid is made of a refractory material having a large number of continuous pores with a relatively small average pore diameter. (5) The radiant tube burner according to claim 1, wherein the breathable solid is a wire mesh woven with a heat-resistant alloy wire. (6) The combustion air supply means and exhaust gas means are:
Connect both openings of the radiant tube to the other two ports of a four-way valve, one of which is open to the atmosphere and the other connected to an exhaust fan, so that one of the openings is communicated with the atmosphere, and the other is connected to the atmosphere. A radiant tube burner according to claim 1, wherein the radiant tube burner is connected to an exhaust fan so that combustion air is sucked by creating a negative pressure inside the tube by operating the exhaust fan.