JPS6352285B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for monitoring the combustion state inside a furnace of a power generation boiler, and particularly to a flame shape monitoring method most suitable for application to a boiler used for thermal power generation. Conventionally, methods for determining the combustion status from the flame in the boiler furnace include monitoring the flame during combustion using an ITV attached to the wall facing the burner nozzle, and inspecting it through a viewing window attached to the furnace wall. The main method was to control the temperature of heat transfer tubes, and the only automatic monitoring device used was a flame detector to determine automatic burner ignition and extinguishment for furnace protection. Moreover, since there was no quantified output value for monitoring the combustion state during boiler operation, operators had to rely on their experience and intuition, and there was a problem in that they were unable to take prompt action. In addition, when monitoring the combustion status using ITV, the ITV installed on the furnace wall is used to monitor the burner nozzle on the opposite wall, so the flame swirls during operation, making it difficult to accurately judge the combustion status. This was difficult and relied on the operator's experience and intuition. An object of the present invention is to provide a method for monitoring the combustion state inside the furnace of a power generation boiler. The present invention is to monitor the combustion state in the furnace by determining a monitoring area according to the shape and properties of the flame depending on the distance from the tip of the burner to the base of the flame. An embodiment of the invention is shown in FIG. In FIG. 1, the boiler burns fuel supplied from a burner 1 in a furnace 7 to convert water in heat exchanger tubes 3 into steam.
In order to monitor the combustion state in the furnace 7, for example, an image fiber 5 and its cooling device 4 are attached to the wall of the furnace 7. An example of the mounting direction and its angle when the viewing angle is θ is shown in FIGS. 2a and 2b. The mounting angle is such that the base of the flame 2 at the tip of one or more burners 1 can be detected, and the mounting position is determined by the viewing angle θ of the image fiber 5. For example, an image signal (light) of the base of the flame 1 detected by a detection unit having such a structure is converted into an analog signal (electricity) by the imaging device 6,
The signal is converted into a digital signal by the A/D converter 8 and taken into the electronic computer 9. An embodiment of the invention is shown in FIG. When the burners 1 are provided facing each other or in multiple stages (rows), it is necessary to install and monitor a plurality of image fibers 5. FIG. 3 shows an example where the burners 1 are installed facing each other. The shape of the flame is detected by the image fiber 5, and for example, as shown in FIG. Furthermore, since the distance L from the tip of the burner 1 to the flame root in FIG. 4 is considered to be a function of the load, the length l of the flame to be monitored is determined based on the distance L (here, the length l of the flame to be monitored is The length l of the flame is considered to be the stable part of the flame). That is,
When the load increases, the distance L increases, and the length l of the flame to be monitored is lengthened; conversely, when the load decreases, the distance L decreases, and the length l of the flame to be monitored is shortened. From this, by changing the length l of the flame to be monitored in proportion to the distance L, good flame monitoring (shape) can be achieved. The image signal (light) of the flame detected by the image fiber 5 etc. to include these above ranges is as follows:
It is converted into an analog signal (electrical) by using the imaging device 6, and further converted into a digital signal by the A/D converter 8 and taken into the electronic computer 9. Captured image signal (digital signal)
detects the stable part of the flame by the method described above,

【table】

【table】

[Table] Comparison using the stable part and the flame shape stored in advance (for example, Table 1) or the characteristics of the flame root shown in Table 3 (for example, the characteristics extracted from the patterns in Table 1) do. When Table 1 is used, there is a problem that it cannot be handled if there is a size relationship between the flame shape and the standard pattern. Therefore, we further investigated the characteristics of the flame pattern and determined l ₁ (thickness of the flame in the upstream part of the flame), l ₂ (thickness of the flame in the downstream part of the flame), and θ ₁ to _{θ 4} (angle) under the conditions shown in Table 3. By setting each range obtained from the standard flame pattern in advance for each, and determining whether or not the standard flame pattern and the flame shape are similar shapes, the shape can be determined regardless of the size of the flame shape. . Using the results determined in this way, it becomes possible to perform state determination, such as determining the flame properties based on Table 2, or detecting flame abnormalities from the relationship between the load and distance L determined in advance. As described above, by classifying flame patterns according to their characteristics and storing them in advance, it is possible to automatically, quickly and accurately grasp the combustion state of the boiler.

[Table] Yes. Furthermore, the same effects as the present invention can be obtained by using data obtained by statistically processing (for example, averaging) image signals. Furthermore, the same effect can be obtained even if an imaging device or a detection device for infrared rays, ultraviolet rays, etc. is installed directly in the detection section.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the present invention, Fig. 2 shows a case where an image fiber is attached, Fig. 3 shows an embodiment of the invention, and Fig. 4 shows a flame root portion. Each figure shows the distance L from the burner tip. 1... Burner, 2... Flame, 3... Heat exchanger tube, 4
...Cooling device, 5...Image fiber, 6...
Imaging device, 7... Furnace, 8... A/D converter, 9
...Electronic computer, 10...Display device.

Claims (1)

[Claims] 1. In a method of monitoring flame shape using a sensor, the distance from the burner tip to the flame root is detected, an area including the flame root of the flame to be monitored is determined in proportion to the distance, and the area including the flame root is determined in proportion to the distance. A flame shape monitoring method characterized by monitoring a flame area.