JPH0253684B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion detection device for detecting a combustion state in a combustion chamber of a pulse combustion device.

Pulse combustion equipment does not require energy for supplying combustion air or for ignition except during startup, and is capable of high-load combustion, as well as efficiently heating the fluid using the tail pipe. However, the noise associated with explosive combustion is intense and countermeasures are important. This noise includes noise that leaks through the intake and exhaust holes, and noise that is generated when the vibrations of the combustion chamber vibrate the entire pulse combustion device. Since the noise leaking through the intake and exhaust holes is reduced by the muffler, it is particularly important to take countermeasures against noise caused by the vibration of the combustion chamber causing the entire pulse combustion device to vibrate.

A conventional combustion detection device 4 includes, for example, a heat-resistant conductive metal rod 3 and an insulator 1, as shown in FIG.
3, an amplifier 14, and a display 40, and the current generated when the heat-resistant conductive metal rod 3 comes into contact with a combustion flame is displayed on the display 40 via the amplifier 14. Combustion air led from the combustion air intake 9 to the decoupling chamber 8 for pulse combustion is supplied to the burner head 2 via a check valve (not shown). The fuel gas supply path 10 is connected to the burner head 2 through another check valve (not shown).
Fuel gas is supplied from In the combustion chamber 1, explosions occur intermittently. A tail pipe 11 forming an exhaust path for combustion exhaust gas is connected to one end of the combustion chamber 1 . The high-temperature combustion exhaust gas exchanges heat with the fluid to be heated supplied in the heat exchange tank 5 through the tail pipe 11, and the heated fluid flows through the outlet 1.
It is discharged from 2. The heat-resistant conductive metal rod 3 is the insulator 1
3, it is fixed to a rigid support cylinder 6 which penetrates the outer wall 7 of the combustion chamber 1 and the heat exchange tank 5 and communicates with the heat exchange tank 5 in an airtight manner. Since the combustion chamber 1 and the heat exchange tank 5 are connected by the rigid support cylinder 6 in this way, the impact vibrations during explosive combustion in the combustion chamber 1 are transmitted through the rigid support cylinder 6. This is transmitted to the heat exchange tank 5, and the entire pulse combustion device vibrates, thereby generating large noise. Further, the support tube 6 must be constructed airtight so as to pass through the heat exchange tank 5, that is, the fluid, and the structure is complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a combustion detection device for a pulse combustion device that detects the combustion state without generating large noise caused by shock vibrations caused by explosive combustion in the combustion chamber and is easy to install. .

The present invention supplies fuel gas and combustion air to one end of a combustion chamber via a check valve, and connects one end of a tail pipe forming a combustion exhaust gas exhaust path to the other end of the combustion chamber. , the air-fuel mixture is explosively combusted in the combustion chamber, and the combustion chamber becomes negative pressure due to the dynamic inertia of the high-speed flow of combustion exhaust gas flowing in the tail pipe due to the explosion, and the combustion chamber is caused to have a negative pressure through the check valve. A pulse combustion device configured to periodically repeat the operation of sucking in fuel gas and combustion air again and detonating the fuel gas and combustion air, comprising: an optical fiber that guides combustion light in the combustion chamber to the outside; It includes a photodetection element that converts light from an optical fiber into an electrical signal, and a bandpass filter that receives the electrical signal from the photodetection element and waves and derives only a signal having the frequency of the explosion of pulsed combustion. This is a combustion detection device for a pulse combustion device characterized by the following.

Embodiments of the present invention will be described below based on the drawings. FIG. 2 is a sectional view of a pulse combustion device equipped with a combustion detection device 15 according to an embodiment of the present invention. From the combustion air intake 16, there is a large spring chamber 17 for relieving the impact pressure of explosive combustion.
The combustion air introduced into the combustion chamber 18 is supplied to the burner head 19 via a check valve (not shown) in the resonance chamber 18. Fuel gas is supplied to the burner head 19 from a fuel gas supply path 45 via another check valve (not shown). In the combustion chamber 20, explosive combustion of the air-fuel mixture occurs intermittently. The period of this explosion is, for example, 50 to 100 times per second, and takes a specific value depending on the structure of the burner. Burner head 19 of combustion chamber 20
A tail pipe 21 forming an exhaust path for combustion exhaust gas is connected to one end of the side that is separated from the tail pipe 21 . The high temperature combustion exhaust gas is removed by this tail pipe 21.
Heat is exchanged with the fluid to be heated supplied in the heat exchange tank 22, and the heated fluid is discharged from the outlet 28.

The combustion detection device 15 according to the invention includes a light detection means 38 , optical fibers 25 , 29 , optical fiber connectors 26 , 27 and a light conductive member 28 inserted into the combustion chamber 20 . The light detection means 38 provided outside the combustion chamber 50 includes a light detection element 24 that converts light from the optical fiber 25 into an electrical signal, and a control circuit 37 to be described later. The photoconductive member 28 is
Any structure that guides combustion light within the combustion chamber 20 may be used, such as a glass rod, a pipe, or a pipe with a convex lens. The optical fiber connector 27 passes through the flange 30 from the side of the burner head 19 and is fixed in an airtight manner. A light conductive member 28 protruding into the combustion chamber 20 is fixed to this optical fiber connector 27 . Light from photoconductive member 28 is directed to one end of optical fiber 29 connected to fiber optic connector 27 . The detection end of the photoconductive member 28 is located on the downstream side of the burner head 19, that is, on the side surface of the combustion chamber 20, in order to reliably guide the combustion light caused by the explosion of pulsed combustion as described later.
Inserted within 0. Combustion light in the combustion chamber 20 is guided from the photoconductive member 28 to the photodetector element 24 via the optical fiber connector 27, the optical fiber 29, the optical fiber connector 26, and the optical fiber 25.
This combustion detection device 15 is configured to detect visible light of combustion flame in the combustion chamber 20.

Since the combustion light is detected by the light detection element 24 through the bendable optical fibers 25 and 29, the combustion state can be detected using the narrow space or gap near the combustion chamber 20. There is no need to penetrate the heat exchange tank 22 filled with fluid as in the prior art described above. Further, by using the optical fibers 25, 29, it is possible to keep the photodetector element 24 and the subsequent control circuit 37 away from the high temperature atmosphere, and vibrations are not transmitted.

FIG. 3 shows a control circuit 3 following the photodetector element 24.
7, and FIG. 4 is a waveform diagram showing an output signal input to line 31 as an output of photodetector element 24. Control circuit 37 includes bandpass filter 32 , amplifier 35 , and safety activation circuit 33 . The output signal from the photodetector 24 is on line 3.
1 to a bandpass filter 32, and is further fed from a line 34 to an amplifier 35 and a line 36 to a safety activation circuit 33. The output signal derived from photodetector element 24 on line 31 is shown in FIG. 4, and the output signal derived from line 36 and applied to safety activation circuit 33 is shown in FIG. The bandpass filter 32 is configured to filter the specific frequency 50 to 100 caused by the above-mentioned pulse combustion explosion.
line 34 with only a signal with a frequency that is attributable to times per second.
It is derived as follows. In Figures 4 and 5, the period T
1, T3 is a period in which pulse combustion is not performed,
Period T2 is a period during which pulse combustion is performed. The safety activation circuit 33 is configured to close a shutoff valve in the fuel gas supply path to cut off the supply of fuel gas, for example, when the output signal on the line 36 indicates that pulse combustion is not occurring. By means of the bandpass filter 32, only the electric signal representing the light that changes due to the specific frequency (50 to 100 times/second) caused by the above-mentioned pulsed combustion explosion is led out to the line 34. Even if an erroneous signal is derived to the line 31 due to disturbance light not caused by combustion, the safety operation circuit 33 does not malfunction and safety is maintained.

FIG. 6 is a sectional view showing another embodiment of the present invention, and corresponding parts are given the same reference numerals. In this embodiment, combustion light is transmitted from the light conductive member 28 and the optical fiber connector 27, which are inserted and fixed airtightly from the outside in the radial direction of the combustion chamber 20, through the optical fiber 29 in the heat exchange tank 22, and into the heat exchange tank 22. The light is applied to the photodetecting element 24 via an optical fiber connector 26 and an optical fiber 25 which are inserted and fixed in an airtight manner.
The other configurations are similar to those of the previous embodiment. Since the optical fiber connectors 26 and 27 are connected by the optical fiber 29 in this way, the vibrations of the combustion chamber 20 are prevented from being transmitted to the heat exchange tank 22, thereby preventing the generation of noise due to the vibrations. It will be done.

In the embodiments described above, the combustion detection device 15 was configured to detect visible light of the combustion flame in the combustion chamber 20, but in other embodiments of the present invention, ultraviolet light, infrared light, etc. may be used instead of visible light. Alternatively, light having different wavelengths may be detected.

Although in the embodiments described above, a light conductive member 28 was provided, the light conductive member 28 may be omitted in other embodiments of the present invention.

Although the foregoing embodiments have been described in connection with so-called premixed pulse combustion devices in which the combustion air and fuel gas are each supplied to the combustion chamber via check valves, other embodiments of the invention may include combustion Of course, it may also be carried out in connection with a so-called original mixing pulse combustion device in which the air and fuel gas are mixed in advance on the upstream side of the combustion chamber and then supplied to the combustion chamber via a common check valve. It is.

As described above, according to the present invention, since the combustion light in the combustion chamber is guided and detected through the optical fiber, the vibrations of explosion combustion in the combustion chamber are not transmitted to the main body of the pulse combustion device through the optical fiber. This prevents noise due to vibration of the pulse combustion device. In addition, since optical fibers are flexible,
It is easy to install by simply inserting one end into the combustion chamber through a narrow space or gap, and it is possible to keep the detector away from the high-temperature atmosphere.

Further, according to the present invention, weak light from an optical fiber is applied to a photodetection element, and the output of the photodetection element is applied to a bandpass filter, and the wave frequency of this bandpass filter is the frequency of the explosion of pulse combustion. This makes it possible to detect pulse combustion without error. In pulse combustion devices, the range of detonation frequencies is narrow, e.g. 80±5
By extracting only signals having such a frequency through a bandpass filter, the combustion state in the pulse combustion device can be known without error. Generally, optical fibers have a fine structure and the amount of light transmitted is small, so it is necessary to improve the signal-to-noise ratio of the signal obtained from the photodetector element for detection. . In the present invention, by using such a bandpass filter, it is possible to detect the explosive combustion state of the pulse combustion device without error.

Further, according to the present invention, the explosion frequency in a pulse combustion device is a constant value for each configuration of the pulse combustion device, and does not vary due to aging or the like. Therefore, although the frequency range of the wave of the band pass filter is narrow, there is no problem of having to adjust the wave frequency of the band pass filter depending on the long-term use of the pulse combustion device, and maintenance is extremely easy. An excellent effect is achieved.
If the range of frequencies through which the bandpass filter passes is set to a wide range, there is a high possibility that the detection of the explosive combustion state of the pulse combustion device will become inaccurate. It is possible to accurately detect the explosive combustion state of a pulse combustion device by setting a narrow frequency range, and it is not necessary to change or adjust the wave frequency range of the bandpass filter over a long period of time. As mentioned above, maintenance is extremely easy. This is important in view of the fact that the sites where pulse combustion devices are installed are often in adverse environments, and in such sites there is a strong demand for easy maintenance.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional combustion detection device, FIG. 2 is a sectional view showing a combustion detection device according to an embodiment of the present invention, and FIG. 3 is a block diagram showing the control circuit of FIG. 4 is a waveform diagram of the output signal of the photodetector element 24, FIG. 5 is a pulse waveform diagram of the electric signal input to the safety operation circuit 33 of FIG. 3, and FIG. 6 is a diagram showing another embodiment of the present invention. FIG. 15... Combustion detection device, 24... Photodetection element,
25, 29... Optical fiber, 26, 27... Optical fiber connector, 28... Photoconductive member, 38...
Light detection means.

Claims (1)

[Claims] 1. One end of a tail pipe that supplies fuel gas and combustion air to one end of the combustion chamber via a check valve, and forms a combustion exhaust gas exhaust path at the other end of the combustion chamber. The air-fuel mixture is explosively combusted in the combustion chamber, and the combustion chamber becomes negative pressure due to the dynamic inertia of the high-speed flow of combustion exhaust gas flowing in the tail pipe due to the explosion, thereby causing the non-return check to occur. In a pulse combustion device configured to periodically repeat the operation of sucking in fuel gas and combustion air again via a valve and detonating it, an optical fiber that guides combustion light in the combustion chamber to the outside, and an optical fiber provided outside the combustion chamber are provided. a photodetection element that converts the light from the optical fiber into an electrical signal; and a bandpass filter that receives the electrical signal from the photodetection element and waves and derives only a signal having the frequency of the explosion of pulsed combustion. A combustion detection device for a pulse combustion device, comprising: