JP2006308110A - Burner and combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a burner capable of surely detecting presence or absence of flame by an optical flame detector regardless of a condition in a furnace such as generation of white fuming, powder dust, steam and an oxidized gas, and to provide a combustion device comprising the burner and capable of being stably operated for a long period. <P>SOLUTION: This burner 2 has a burner inner cylinder 2a for supplying fuel and a burner outer cylinder 2b for supplying air for combustion, and the optical flame detector 6 is mounted at a rear end side in the burner outer cylinder 2b, for detecting the presence or absence of the flame 5 of the burner 2. When an accidental fire detection signal is transmitted from the optical flame detector 6 to a control device 8, a cut-off signal is output, the fuel supply pipe 3 is closed by a solenoid cutoff valve 7, and the fuel supply to the burner 2 is cut off. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a combustion apparatus equipped in a drying furnace or a heating furnace, and a burner used in the combustion apparatus.

  Generally, in a combustion apparatus equipped in a furnace such as a drying furnace or a heating furnace, a flame detector for confirming the combustion state of the burner is attached together with a burner that generates a flame by burning fuel. As one type of such a flame detector, an optical flame detector is known that detects the presence or absence of a flame based on the amount of radiant energy such as ultraviolet or infrared rays of the flame.

  A specific example of a combustion apparatus equipped with a conventional optical flame detector is shown in FIG. The burner 2 fixed to the furnace wall 1 has a double pipe structure comprising a burner inner cylinder 2a and a burner outer cylinder 2b arranged coaxially on the outer side of the burner inner cylinder 2a. The burner outer cylinder 2 b is connected to the combustion air supply pipe 4. Then, the fuel supplied to the burner inner cylinder 2a is burned by the combustion air supplied to the burner outer cylinder 2b, and the flame 5 is released from the tip of the burner 2 into the combustion chamber of the furnace.

  In the conventional combustion apparatus, an optical flame detector 6 for confirming the presence or absence of the flame 5 of the burner 2 is attached at a position different from the burner 2 of the furnace wall 1. An annular passage 6a that penetrates the furnace wall 1 from the optical flame detector 6 and reaches the inside of the furnace is provided in order to guide ultraviolet rays, infrared rays, and the like of the flame 5 to the optical flame detector 6. The fuel supply pipe 3 to the burner 2 is provided with an electromagnetic cutoff valve 7, and the electromagnetic cutoff valve 7 is closed by a cutoff signal output from the control device 8 that has received a misfire detection signal from the optical flame detector 6. It is like that.

  When the burner 2 misfires for some reason, the optical flame detector 6 determines that a misfire has occurred by reducing the amount of radiant energy to be detected to a predetermined amount or less, and issues a misfire detection signal. This misfire detection signal is sent to the control device 8, and a cutoff signal is output from the control device 8 to the electromagnetic cutoff valve 7. When this cutoff signal is received by the electromagnetic cutoff valve 7, the electromagnetic cutoff valve 7 closes the fuel supply pipe 3 and shuts off the supply of fuel to the burner 2, thereby avoiding the risk that the fuel stays in the furnace and explodes. be able to.

  However, since the conventional optical flame detector 6 separate from the burner 2 is usually installed obliquely above or obliquely below the flame 5 of the burner 2, a large amount of it is placed in a furnace such as a drying furnace or a heating furnace. When white smoke is generated due to hydrochloric acid gas, or when a large amount of dust is scattered during firing of pellets mainly composed of incineration fly ash of municipal waste, the ultraviolet rays and infrared rays of the flame 5 are The radiant energy that reaches the optical flame detector 6 is easily reduced by being blocked by dust. As a result, even if the burner 2 is normally burned, the optical flame detector 6 determines that misfire has occurred and fuel is shut off by the fuel shut-off valve 7, so that stable continuous operation becomes difficult. It was.

  In general, the optical flame detector 6 is vulnerable to heat, and the heat in the furnace is easily transmitted through the annular passage 6 a that guides the ultraviolet rays, infrared rays, and the like of the flame 5 to the optical flame detector 6. Furthermore, if white smoke, dust, water vapor, etc. generated in the furnace pass through the annular passage 6a and adhere to the optical flame detector 6, normal misfire detection becomes impossible. Therefore, in the conventional optical flame detector, for example, as shown in FIG. 1, it is necessary to supply the cooling air to the annular passage 6a that communicates with the optical flame detector 6 and the inside of the furnace (for example, Japanese Patent Laid-Open No. 2003-2003). -287227).

JP 2003-287227 A

  In the combustion apparatus provided with the conventional burner and the optical flame detector separately, it is necessary to supply cooling air to cool the optical flame detector as described above. However, there is a problem that the supplied cooling air cools the optical flame detector and enters the furnace, thereby reducing the furnace temperature. In addition, since excessive oxygen is supplied into the furnace by the cooling air, there is a problem that it is difficult to control the combustion state in the furnace or to operate in a reducing atmosphere.

  On the other hand, as a flame detector that is hardly affected by white smoke, powder, water vapor, etc. generated in the furnace and does not need to supply cooling air, an electrode is inserted into the flame to set the current value. A frame rod type measuring device and a thermocouple type measuring device directly measuring the temperature around the flame are also known. However, any type of flame detector has a drawback in that it is easily deteriorated due to the flame because it is installed in or near the flame, and corrosion easily proceeds when hydrochloric acid gas or the like is generated in the furnace.

  In view of such a conventional situation, the present invention can reliably detect the presence or absence of a flame with an optical flame detector regardless of the in-furnace situation such as generation of white smoke, dust, water vapor or oxidizing gas. An object of the present invention is to provide a burner that can be used, and by using this burner, it is easy to control the combustion state in the furnace, and to provide a combustion device that is always capable of stable and long-term operation.

  In order to achieve the above object, a burner provided by the present invention is a burner having a burner inner cylinder for supplying fuel and a burner outer cylinder for supplying combustion air arranged coaxially outside the burner inner cylinder. Thus, an optical flame detector for detecting the presence or absence of the flame of the burner is provided on the rear end side in the burner outer cylinder through which combustion air flows.

  Further, the combustion apparatus provided by the present invention includes a burner provided with the above-described optical flame detector according to the present invention, an electromagnetic shut-off valve installed in a fuel supply pipe to the burner, and a misfire detection from the optical flame detector. And a control device that outputs a shut-off signal to the electromagnetic shut-off valve according to the signal.

  According to the present invention, since the optical flame detector is incorporated in the burner outer cylinder, the flame at the tip of the burner can be captured at the shortest distance from between the burner outer cylinder and the burner inner cylinder. Therefore, even if a large amount of white smoke or dust is generated in the furnace, the flame of the burner can be reliably detected, and the fuel will not be shut off despite the burner being burned normally. It becomes possible to operate the heating furnace continuously for a long time in a stable state.

  Further, since the optical flame detector incorporated in the burner is constantly exposed to the combustion air supplied to the burner outer cylinder, it is cooled by the combustion air and there is no need to supply cooling air separately. . As a result, a decrease in furnace temperature and an increase in furnace oxygen concentration due to the inflow of cooling air can be prevented, the combustion state in the furnace can be easily controlled, and operation in a reducing atmosphere is also possible. Furthermore, white smoke, dust, water vapor, and oxidizing gas generated in the furnace cannot enter the burner outer cylinder due to combustion air and do not touch the optical flame detector. In this respect, stable long-term continuous operation is possible.

  For example, as shown in FIG. 2, the burner according to the present invention includes a burner inner cylinder 2a for supplying fuel to the burner 2 and a burner outer cylinder 2b for supplying combustion air, and the burner outer cylinder 2b is a part of the burner inner cylinder 2a. It has a double tube structure arranged coaxially on the outside. In the burner outer cylinder 2b of the burner 2, a normal optical flame detector 6 is installed on the rear end side which is the outside (outside of the furnace) of the combustion chamber when the burner 2 is mounted on the furnace wall 1. . Therefore, the optical flame detector 6 can catch the flame 5 at the tip of the burner 2 through the shortest distance from the rear through the burner inner cylinder 2a and the burner outer cylinder 2b, so that white smoke or dust generated in the furnace, etc. Therefore, the flame 5 of the burner 2 can be reliably detected without being interrupted by.

  Further, the optical flame detector 6 disposed in the burner outer cylinder 2b is cooled by the combustion air supplied from the combustion air supply pipe 4 to the burner outer cylinder 2b, so that cooling air is separately supplied. There is no need. As a result, the air flowing into the combustion chamber in the furnace is only the combustion air, and it is possible to prevent a decrease in the furnace temperature and an increase in the furnace oxygen concentration due to the inflow of cooling air as in the prior art. Moreover, when the burner 2 is attached to the furnace wall 1, the optical flame detector 6 is located outside the furnace and is protected by the flow of combustion air in the burner outer cylinder 2b. There is no corrosion due to internal gas, and it can be used stably for a long time.

  The combustion apparatus of the present invention includes a burner 2 provided with the above-described optical flame detector 6, and outputs a cutoff signal to the electromagnetic cutoff valve 7 disposed in the fuel supply pipe 3 to the burner 2 and the electromagnetic cutoff valve 7. A control device 8 is provided. When the optical flame detector 6 detects that the amount of radiant energy of the flame 5 has decreased below a predetermined amount, the optical flame detector 6 determines that the burner 2 has misfired and sends a misfire detection signal to the control device 8. In response to this misfire detection signal, the control device 8 sends a shut-off signal to the electromagnetic shut-off valve 7 so that the fuel supply pipe 3 is shut off.

  The burner and combustion apparatus of the present invention will be described in more detail with reference to FIG. FIG. 2 is a specific example of a combustion apparatus equipped with the burner 2 of the present invention, and shows a state where the combustion apparatus is attached to a furnace wall 1 of a rotary kiln used for burning pellets mainly composed of incineration fly ash of municipal waste.

  The burner 2 has a double pipe structure of a burner inner cylinder 2a and a burner outer cylinder 2b. The burner inner cylinder 2a is made of a SUS304 steel pipe having a diameter of 40 mm, and the burner outer cylinder 2b is made of a SUS310S steel pipe having a diameter of 150 mm. Has been. An optical flame detector 6 is attached to the rearmost end of the burner outer cylinder 2b, and the flame 6 is misfired by judging the presence or absence of the flame 5 by detecting the amount of radiant energy generated by the flame 5 of the burner 2. A misfire detection signal is sent to the control device 8.

  A fuel supply pipe 3 for supplying fuel to the burner 2 is connected to the rear end side of the burner inner cylinder 2a, and combustion air supply for supplying combustion air to the burner 2 is connected to the rear end side of the burner outer cylinder 2b. A tube 4 is connected. The fuel supply pipe 3 is provided with an electromagnetic shut-off valve 7 electrically connected to the control device 8, and an electromagnetic signal is received from the control device 8 that receives the misfire detection signal of the optical flame detector 6. The shutoff valve 7 shuts off the fuel supply pipe 3 and stops the fuel supply.

  Actually, using a rotary kiln equipped with the combustion apparatus of the present invention shown in FIG. 2, an experiment for burning pellets mainly composed of incineration fly ash of municipal waste was conducted. That is, the firing was carried out by adjusting the composition of the pellets mainly composed of incinerated fly ash and the molding pressure so that a large amount of dust was scattered in the furnace during firing. As a result, even when a large amount of dust is generated in the furnace, the radiant energy of the burner 2 by ultraviolet rays or infrared rays reaches the optical flame detector 6 without being blocked by the dust, and the burner 2 burns normally. I was able to confirm that.

  Further, since the optical flame detector 6 attached to the burner 2 is cooled by the combustion air flowing in the burner outer cylinder 2b, it is normal even if the cooling air is not supplied to the optical flame detector 6 separately. It was confirmed that it works. Furthermore, since the combustion air in the burner outer cylinder 2b flows toward the inside of the furnace, the furnace atmosphere such as dust generated in the furnace does not enter the burner outer cylinder 2b, and the optical flame detector 6 It did not adversely affect.

  When the burner 2 actually misfires, the optical flame detector 6 detects that the amount of radiant energy has decreased to a predetermined amount or less, determines that misfire has occurred, and sends a misfire detection signal to the control device 8. The electromagnetic shut-off valve 7 that received the shut-off signal from the valve closed the fuel supply pipe 3 to shut off the fuel supply. With this operation, it is possible to eliminate the danger of fuel continuing to be supplied into the furnace despite the misfire of the burner 2 and staying in the high temperature furnace and exploding.

It is a schematic sectional drawing which shows the combustion apparatus provided with the conventional burner. It is a schematic sectional drawing which shows one specific example of the combustion apparatus provided with the burner by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace wall 2 Burner 2a Burner inner cylinder 2b Burner outer cylinder 3 Fuel supply pipe 4 Combustion air supply pipe 5 Flame 6 Optical flame detector 7 Electromagnetic shut-off valve 8 Control device

Claims (2)

  A burner having a burner inner cylinder for supplying fuel and a burner outer cylinder for supplying combustion air arranged coaxially on the outer side of the burner inner cylinder, the rear end side in the burner outer cylinder through which combustion air flows And an optical flame detector for detecting the presence or absence of the flame of the burner. A burner provided with the optical flame detector according to claim 1, an electromagnetic cutoff valve installed in a fuel supply pipe to the burner, and a cutoff signal output to the electromagnetic cutoff valve by a misfire detection signal from the optical flame detector And a control device.

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