JPS61139726A - Flame detection apparatus - Google Patents

Abstract

PURPOSE:To enhance detection accuracy by widening a visual field for monitoring a fire to a large extent, by performing the detection of flame and the transmission of detected light by using an optical fiber and attaching one or more of said optical fiber. CONSTITUTION:The light of flame is not only detected but also transmitted by an optical fiber. That is, three grooves are formed to the leading end part of a lighting head 2 toward the leading end opening part 3a thereof at different angles and three optical fibers (4a, 4b, 4c) are received in and arranged to said grooves so as to have definite visual fields around wires 5a, 5b, 5c. Three optical fibers 4 reach the window box 8 attached to the base part of an outer cylinder 1 through a connector 7. Cooling air A entering the window box 8 passes through an inner cylinder 6 and a part thereof is injected from the circumference of the lighting head 2 while the other part is injected from the opening part 3a provided to the leading end of the lighting head 2 through the optical fiber receiving grooves 2b of said head 2 to cool the main body and the optical fibers received therein.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application> The present invention relates to a flame detection device, and particularly to a device that can reliably monitor flames.

<Prior art and its problems> Accurately detecting the combustion state of various combustion devices, including large boilers in business establishments, is extremely important from the economic and safety standpoints. Taking a large boiler for a power plant as an example, an increase in the number of burners installed due to the increase in boiler capacity, an increase in the number of burner ignitions and extinguishments due to medium load operation of large boilers, and an increase in nitrogen oxide (NOx)
), as well as changes in combustion behavior due to diversification of fuels, it is desired to further improve the reliability of burner flame detection.

Flame detectors detect flames by detecting heat, light, or electrical properties of flames, but among these methods, the method of detecting flames by detecting light simply detects the presence or absence of flames. In addition to detecting the flame, it is basically possible to analyze the properties of the flame by analyzing the frequency of the light emitted by the flame, which allows us to obtain a lot of information about the flame.

In conventional optical flame detectors, a heat-resistant mirror or lens is placed at the tip of a cylindrical head, and the light detected by these mirrors is guided to the outside of the boiler through the head. The presence or absence of flame was detected. However, with this method, the field of view is limited to one depending on the angle at which the mirror or lens is attached, and although it is possible to detect a part of the flame, it is not possible to detect the brightness distribution of the entire flame, and the properties of the flame cannot be detected. It was virtually impossible to detect. In addition, the narrow field of vision
This makes it difficult to distinguish between light from other flames and the light from the burner flame that should be detected, and often causes detection errors. Furthermore, in order to achieve low NOx combustion, there is a considerable amount of unburnt material floating near the flame formation area, reducing the permeability of the entire furnace, making conventional equipment with a single field of view even more reliable. The reality is that it is declining.

OBJECTS OF THE INVENTION The present invention aims to eliminate the above-mentioned problems and provide a flame detection device that can accurately detect flames.

<Summary of Means for Solving the Problems> In short, the present invention detects flames and transmits the detected light using optical fibers, and by attaching these optical fibers to multiple locations, the field of view for flame monitoring is improved. This device is designed to significantly expand the detection accuracy and improve detection accuracy.

<Example> Examples of the present invention will be described below.

In FIG. 1, reference numeral 1 denotes an outer cylinder constituting the main body of the device, and 2
is a lighting head attached to the vicinity of the tip inside the outer cylinder 1 via a support member 3. Three grooves are formed at the tip of the lighting head 2 at different angles toward the tip opening 2a, and three optical fibers (4a, 4b) are connected to each groove.

4c) are stored and arranged, and each is [
5a, 5b, and 5o are arranged so as to have a constant field of view. For example, the angle α1. formed by the center lines 5&~5C of these visual fields. α1 is set as αl→α2415. In addition, in order to protect the optical fiber housed inside, it is desirable that at least the support member 3 of the lighting head 2 and the lighting head support member 3 be formed of a heat-resistant material such as ceramics.

Next, reference numeral 6 denotes an inner cylinder disposed within the outer cylinder 1 with a certain space therebetween, and numeral 7 denotes a connector disposed within the inner cylinder 6.
The main optical fiber 4 passes through the connector 7 to the outer tube 1
This leads to the window rack 8 attached to the base of the. In addition to being used for supplying cooling air, the box 8 is configured to house a photoelectric converter, perform photoelectric conversion in the box C, and output the detected flame light as an electrical signal to the outside of the box. It's okay. In addition, the cooling air A that has entered the wind box 8 passes through the inner cylinder 6 and is injected partly from around the lighting head 2, and the other part passes through the optical fiber storage groove 2b of the lighting head 2 and is ejected from the opening 3a at the tip of the head. , cools the main body and the optical fiber housed inside.

FIG. 2 shows the detection device described below attached to the burner of a large boiler. The outer cylinder 1, which is the main body of the device, is supported @
20 is arranged close to the burner 9, and monitors the burner flame F in multiple fields so that the center of the field of view is 5a, 5b, and 5o.

FIG. 3 shows an example of a method for detecting flame using this flame detector.

First, light detected by each optical fiber in the lighting head 2 reaches the photoelectric conversion section 10 and is converted into an electrical signal.

Next, in the switching unit 11, the burner switching unit 1 is set so that the signal from the head 2 placed on the burner for which flame detection is to be performed is inputted.
Do step 1a. Incidentally, since one head 2 is arranged for each burner, in the case of FIG. 3, flame detection is performed for two burners. Next, the center of the detection field of view is selected by fiber switching lie, and photoelectric element switching 1it) is performed to switch the photoelectric element that receives light from this fiber to a charging element that responds to the frequency component to be detected. The electric signal (analog) selected in this way is converted into a digital signal in the A/D converter 12, and then the presence or absence of flame and the properties of the flame are determined in the flame determination section 13, and this determination result is sent to the CR.
Output to T14, printer 15, etc.

Effects> Since the present invention has the above configuration, the flame can be accurately monitored and not only the presence or absence of flame but also the flame properties can be analyzed, so that the combustion device can be controlled more appropriately.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of a flame detection device showing an embodiment of the present invention, Fig. 2 is a sectional view of a burner showing an example of how the flame detection device is installed, and Fig. 3 shows an example of use of the device of the invention. It is a flowchart. 1... Outer cylinder 2, mountain, daylighting head 3... daylighting head support member 4... optical fiber 9... burner

Claims (1)

[Claims] 1. One or more optical fibers are arranged in a support cylinder arranged near the flame forming part, and the optical fibers are configured to detect flame light and transmit this light. Flame detection device. 2. The flame detection device according to claim 1, wherein a plurality of the optical fibers are arranged and the angles at which the light-receiving side ends of these optical fibers are attached are made different to enlarge the field of view. 3. The optical fiber is housed in the lighting head, and cooling air is passed through at least one of the inside of the lighting head and the periphery of the lighting head, as claimed in claim 1 or 2. Flame detection device as described in section.