JPS63289424A - Light detector - Google Patents

Abstract

PURPOSE:To simultaneously observe a plurality of the combustion light sources in a combustion chamber and to suppress the rising in the temp. of a convex lens and the adhesion of soot to said lens, by providing the convex lens rotating at a high speed to the observation window provided to the combustion chamber and providing a plurality of light detectors on the side opposite to the combustion chamber. CONSTITUTION:A convex lens 25 rotating at a high speed is provided to the observation window 5 provided to a combustion chamber 1 and a plurality of light detection parts 33A, 33B detecting a plurality of the combustion light sources S1-S3 in the combustion chamber 1 are provided on the side opposite to the combustion chamber 1 of the convex lens 25. When the convex lens 25 is rotated at a high speed by the motor 27, the images of the combustion light sources S1-S3 are formed at the focuses P1-P3 in a housing 22 when there are said combustion light sources S1-S3. Therefore, for example, when the light detection parts 33A, 33B are preliminarily moved to the focuses P2, P3, the combustion light sources S2, S3 can be observed. No soot is adhered to the surface of the convex lens since the convex lens 25 is rotated at a high speed. Further, since cooling effect is obtained by the high speed rotation of the lens, the deformation of the lens due to heat is not generated.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is applicable to, for example, the ignition state of a boiler in a thermal power plant,
The present invention relates to a photodetection device for measuring combustion characteristics of fuel.

(Prior Art) Conventionally, in a boiler or the like of a thermal power plant, a torch burner is used in a combustion chamber to burn fuel to generate steam. In order to observe the combustion state inside the combustion chamber, a photodetector as shown in the plan view of FIG. 12 is used.

In FIG. 12, reference numeral 1 denotes a combustion chamber, in which a torch 2 is provided, a torch burner 3 is provided therein, this torch burner 3 is ignited by a pilot burner 4, and a fuel F
is burned to heat water and generate steam. 5 is an observation window provided in the combustion chamber 1, and a light detection device 1) is attached to this.
are set up consecutively.

The photodetector 1) includes a convex lens 12 provided opposite to the observation window 5, a photodetector 13 provided near the focal point of the convex lens 12, and an optical fiber 14 that guides the light incident from the photodetector 13. , a photoelectric conversion element 15 such as a photodiode that photoelectrically converts the light emitted from the optical fiber 14.

Note that 16.17 indicates the convex lens 12 and the light detection unit 1.
Support member 3 and 18 are output lines of the photoelectric conversion element 15, and as the light detection section 13, the input end of the optical fiber 14 itself, a transparent body, or the like is used.

[Problems to be Solved by the Invention] In the above case, even if there is only one torch burner 3, there are a plurality of combustion light sources S in the combustion chamber 1 depending on the distribution state of the fuel F. However, the conventional photodetector 1 shown in FIG.
), even if it is possible to focus on one of these plurality of combustion light sources S (only three are shown in the figure) on the optical axis of the convex lens 12, it is impossible to focus on a plurality of combustion light sources S. As a result, it was not possible to obtain sufficient data to accurately understand combustion conditions. Furthermore, the heat inside the combustion chamber 1 is transferred to the photodetector 1) through the convex lens 12 and other members, and not only the convex lens 12 itself but also the inside of the photodetector 1) become high temperature. There was a problem in that soot adhered to the surface on the combustion chamber 1 side, making observation impossible.

This invention was made to solve the above problems, and allows simultaneous observation of multiple combustion light sources in the combustion chamber.
Moreover, it is an object of the present invention to provide a photodetecting device that can suppress temperature rise and soot adhesion to a convex lens.

(Means for Solving the Problems) A photodetection device according to the present invention includes a convex lens that rotates at high speed in an observation window provided in a combustion chamber, and a plurality of photodetection units provided on the opposite side of the convex lens from the combustion chamber. It is something that

[Effect]

In this invention, a plurality of combustion light sources generated within a combustion chamber are detected by a plurality of light detection sections provided in a light detection device, and the combustion state within the combustion chamber is accurately determined by the output of each of these light detection sections. can be grasped. Since the convex lens rotates at high speed, soot and the like do not adhere to its surface.

〔Example〕

FIGS. 1 and 2 are a partially sectional plan view and a side view, respectively, showing an embodiment of the present invention. In these figures, 21 is a photodetector, which is composed of the following parts. That is, 22 is a housing, which is attached to the observation window 5 of the combustion chamber 1. 23 is a frame attached to the observation window 5, 24 is a mounting member for the housing 22, and 25 is a large diameter convex lens, the periphery of which is covered with a protective ring 26. Reference numeral 27 denotes a motor, and a threaded portion at the tip of a shaft 28 passes through the center hole of the convex lens 25, and the convex lens 25 is fixed to the shaft 28 by a collar 29 and a nut 30 provided on the shaft 28. The shaft 28 is supported by a bearing 31, and the bearing 31 is supported by a support member 32 attached to the housing 22. Reference numerals 33A and 33B are photodetecting units (hereinafter collectively referred to as simply 33. The same applies to other symbols), which transmit incident light via optical fibers 34A and 34B, respectively, to a photoelectric conversion element 35A.

35B, and outputs are obtained from output lines 36A and 36B.

The photodetectors 33A and 33B are configured to be movable in the X, Y, and Z directions. Taking the photodetecting section 33A as an example, for example, FIG. 3(a) shows.

As shown in (b), for movement in the Y direction, rack plate 3
7 and the guide rod 38 are attached between the support plates 39 on both sides, the casing of the light detection unit 33A is slidably attached to the rack plate 37 and the guide rod 38, and the pinion 41 is rotated by the stepping motor 40. The photodetector 33A is moved along the rack plate 37 that engages with the pinion 41. Although the details of the movement in the X direction are omitted, the photodetector 33A can be moved by the steng motor 42 using the rack 37, pinion 41, etc. as described above. moreover,
In the Z direction, using the guide rod 43 as a guide, the stepping motor 44. The support plates 39 on both sides can be moved together using the pinion 45, rack plate 46, and the like. In addition,
The same applies to the light detection section 33B. FIG. 4 is a partially cross-sectional schematic diagram illustrating the state of the combustion chamber 1, and the shape of the combustion chamber 1 is different from that in FIG. 1 for convenience of explanation. FIG. 5 is a partial bottom view of FIG. 4.

In these figures, 6.7 is an electromagnetic fuel valve,
Burner for torch 3. It is attached to the pilot burner 4. Then, as shown in FIG. A plurality of photodetecting devices 21 are provided along the length direction of the combustion chamber 1 and around the outer circumference. 8 is a control unit, and the photodetector 2
The fuel valve 6.7 is controlled according to the output of 1 to indicate combustion control.

Next, the operations shown in FIGS. 1 and 2 will be explained.

First, the convex lens 25 is moved by the motor 27, for example,
Rotate at a high speed higher than Orpm. If there are combustion light sources S, . . . S2 and S3 as shown in FIG. Image is formed on p3. Therefore, if the light detection units 33A and 33B are moved to, for example, the focal point P2°P3, the combustion light source S2. S3 can be observed. Regarding the focal point PI, in this example, the focal point P2. Although it cannot be observed simultaneously with P3, it can be observed by moving either of the photodetectors 33A, 33B.

Further, by further increasing the number of light detection units 33, more combustion light sources S can be observed. Mo, convex lens 2
5 rotates at high speed, soot etc. do not adhere to the surface. In addition, since the high-speed rotation has a cooling effect, deformation due to heat does not occur. Then, based on the data obtained from the photodetector 21 shown in FIG. 4, the control section 8 controls the fuel valve 6.7 to achieve the desired combustion state.

FIG. 6 shows a photodetector 33 and an optical fiber 3 used in this invention.
4 shows a light guide 5o that is integrated with the light guide 5o.

In this figure, numeral 51 is a glass tube, a concave lens 52 is attached to the front end of the tube to constitute the light detection section 33, and the other end is sealed with a transparent plate 53. 54 is an exhaust pipe, which is connected to a vacuum pump 56 via a valve 55. Then, a reflective surface is provided on the inner or outer surface of the glass tube 51 as appropriate. For example, attach silver paper to the outer surface. However, this is not essential because it increases the reflection efficiency.

In use, after the inside of the glass tube 51 is evacuated by the vacuum pump 56, the valve 55 is closed, and the concave lens 52 is used while adjusting the required focus. The light incident from the concave lens 52 reaches the other end while being reflected by the inner surface of the glass tube 51, passes through the transparent plate 53, and enters the photoelectric conversion element 35.

In the embodiment shown in FIG. 6, a vacuum pump 56 is connected.
After the inside of the glass tube 51 is evacuated as shown in FIG. 7, it may be sealed with a sealing part 57. In place of the glass tube 51, synthetic resin, metal, or other materials may also be used.

As described above, by using a pipe body such as the glass tube 51 whose interior is evacuated, the transmission loss of light can be extremely reduced.

FIG. 8 is an explanatory diagram of a measurement example, in which the convex lens 25 has a diameter of 1
) cm, focal length 30 cm, TLN-101 made by KEL Co., Ltd. was used as the optical fiber 34 at 1 m, PIN-PD also made by KEL Co., Ltd. was used as the photoelectric conversion element 35, and Iwasaki Tsushinki V manufactured by Co., Ltd.
Combustion light sources S, S2 were measured using an OAC-787 voltmeter.

FIG. 9 shows data when the photodetector 33 is moved over the measurement position 450 mm from the convex lens 25 as shown in FIG. Note that the distance between the convex lens 25 and the combustion light sources S, S2 is approximately 1000 mm.

FIG. 10 shows data regarding the light guide 5o shown in FIG. 6, and shows the relationship between the degree of internal vacuum and the number of times ultraviolet rays are detected. That is, ultraviolet rays are emitted in the combustion light source S at irregular levels and timing, and the detection sensitivity, that is, the number of times the ultraviolet rays are emitted, is determined by the light guide connecting the photoelectric conversion element 35 and the light detection section 33. 50 characteristics.

That is, in FIG. 10, the horizontal axis is the degree of vacuum, the vertical axis is the number of ultraviolet rays detected, and a is when the light guide 5o is not used.
b is a case where three glass tubes 51 with an inner diameter of 1 mmφ are put together and used as a light guide 50 with air inside without creating a vacuum,
C has the same inner diameter of 10 mmφ and is used as the light guide 50 with air inside without being evacuated, BL is the same glass tube 51 as described above, and when the inside of each tube is evacuated, C1 is the same as that of C. The characteristics are shown when the inside of the glass tube 51 is evacuated. In both cases, the distance between the combustion light source S and the measurement position was 1200 mm.

As can be seen from FIG. 10, when the degree of vacuum exceeds 500 mmHg, the number of times ultraviolet rays are detected increases rapidly. This is because the loss in the light guide 50 is reduced, making it possible to detect even low-intensity ultraviolet rays.

Figure 1) shows another embodiment of the convex lens 25, in which the outer periphery of the protective ring 26 is provided with diagonal knurling 26A. In this way, when the convex lens 25 moves at high speed, air flows due to the fan effect of the diagonal knurling 26A, and as shown in FIG.
Since the air flows toward the housing 22, an increase in temperature within the housing 22 can be prevented. In this case, as shown in the cross section of Figure 1), the protective ring 26 is caulked from above and below to sandwich and fix the periphery of the convex lens 25, and is fixed with an adhesive if necessary. Further, instead of the diagonal knurling 26A, a convex portion may be formed to provide a more positive fan effect.

In addition, in the above embodiment, the X and Y of the light detection section 33.

Although a rack, a pinion, and a stepping motor are used to drive Z, other means may of course be used. Further, it is preferable that the housing 22 of the embodiment shown in FIGS. 1 and 2 is provided with an air inlet.

〔Effect of the invention〕

As explained above, this invention provides a convex lens that rotates at high speed in an observation window provided in a combustion chamber, and a plurality of light detectors each detecting a plurality of combustion light sources in the combustion chamber on the side opposite to the combustion chamber of this convex lens. Since the combustion chamber is provided with a section, a plurality of combustion light sources in the combustion chamber can be observed simultaneously, and therefore the combustion state can be accurately grasped. Therefore, especially when a plurality of torches are provided, combustion does not occur uniformly in the combustion chamber, but if the combustion state of each part can be grasped by this invention, the proportion of fuel (lime powder, 1 heavy oil, light oil, L
It becomes possible to control the mixture ratio (mixing ratio of PG, etc.) and the amount, thereby making it possible to improve fuel efficiency and reduce pollution. In addition, the cooling effect caused by the high-speed rotation of the convex lens not only prevents thermal deformation of the convex lens, but also prevents soot from adhering to the surface of the convex lens on the combustion chamber side, making it impossible to observe it as before. It has extremely excellent advantages such as no

[Brief explanation of the drawing]

FIGS. 1 and 2 are a partially sectional plan view and side view showing an embodiment of the present invention, and FIGS. 3(a) and 3(b) similarly show details of the drive mechanism of the photodetector. top view and side view,
Fig. 4 is a partially cross-sectional schematic diagram for explaining the state of the combustion chamber, Fig. 5 is a partial bottom view of Fig. 4, and Figs. 6 and 7 are examples of light guides used in this invention. A plan view showing each
FIG. 8 is an explanatory diagram of a measurement example, FIG. 9 is a diagram showing an example of data obtained by the measurement example of FIG. 8, and FIG. 10 is a diagram of data showing the characteristics of the light guide of FIG. 6. Fig. 1) is a partial sectional view showing another embodiment of the convex lens, and Fig. 12 is a partially sectional plan view showing an example of a conventional photodetecting device. In the figure, 21 is a photodetector, 22 is a housing, 23 is a frame, 24 is a mounting member, 25 is a convex lens, 26 is a protection ring, 27 is a motor, 28 is a shaft, 29 is a collar, 30 is a nut,
31 is a bearing, 32 is a support member, 33A, 33B is a photodetector, and 34A. 34B is an optical fiber, 35A and 35B are photoelectric conversion elements,
36A, 36B are output lines, 37.46 is a rack plate, 38
．． 43 is a guide rod, 39 is a support plate, 40, 42, 44 is a stepping motor, and 41° and 45 are binions. #i! I18 foil - Thatched roof δ88 Iijo moon mouth - [

Claims (2)

[Claims] (1) A convex lens that rotates at high speed is provided in the observation window provided in the combustion chamber, and a plurality of light detection units that respectively detect a plurality of combustion light sources in the combustion chamber are provided on the opposite side of the convex lens from the combustion chamber. A photodetection device characterized by: (2) The photodetecting device according to claim (1), wherein the convex lens is provided with a protective ring that covers the periphery, and a diagonal knurling is formed on the outer periphery of the protective ring.