JPS5885105A - Device for detecting height of fluid layer - Google Patents

Abstract

PURPOSE:To measure the actual height of a layer accurately, by attaching temperature sensitive elements to the outer surface of a furnace wall, and detecting the height of the fluid layer from the temperature difference between the fluid layer and a vacant tower part. CONSTITUTION:A fluid medium such as quartz sand is put on a distributing plate 2 of a main device body 1. The fluid layer 4 is formed by fluidizing gas which is sent from a wind box 3 below the distributing plate. The vacant tower part 5 is formed on the layer 4. A side wall 6 constituting the main furnace body 1 comprises a water cooling wall. Many temperature sensitive elements 7 are fixed to said side wall 6 in the up and down directions along the part including the fluid layer 4 and the vacant tower part 5. A water pipe of the furnace wall 6 is communicated to a drum 10 through upper and lower headers 8 and 9. Yielded vapor is taken away through a line 11. Meanwhile, a water in the drum 10 is recirculated to the pipe of the furnace wall 6. In this constitution, the temperature in the up and down directions of the furnace wall 6 are detected by the temperature sensitive elements 7. The results are transduced into electric signals, amplified, and displayed on a recorder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluidized bed combustion apparatus trap, and more particularly to an apparatus for detecting the height of a moving bed in a fluidized bed combustion apparatus such as a fluidized bed boiler.

Fluidized bed boiler 2 is attracting attention now that coal is once again attracting attention as a fuel because it burns low-grade coal well and has good heat transfer characteristics in the fluidized bed. In a fluidized bed boiler, the heat transfer load of the fluidized bed can be adjusted by adjusting the height and depth of the fluidized bed; for example, increasing the height of the fluidized bed increases the amount of heat transfer, and decreasing the height of the fluidized bed decreases the amount of heat transfer. It is also known that heat transfer through heat transfer tubes in a fluidized bed is several times higher than heat transfer through heat transfer tubes above the fluidized bed. For this reason, it is extremely important to know the relative position of the heat exchanger tubes and the fluidized bed, and to detect the height of the fluidized bed and the extent of the presence of the medium in order to control the height of the fluidized bed. .

Conventional methods for detecting the height of the fluidized bed include, for example, installing a level meter that can be observed at its own limit, or inserting a contact needle from the top or side wall of the furnace, and detecting the top surface of the fluidized bed based on the change in resistance. It was getting worse.

However, Tawara's method may not display an accurate level due to fluid clogging inside, and Tawara's method detects the fluid bed surface by contact resistance, so it is inaccurate and does not measure the fluid bed height. It was inappropriate for K to constantly monitor the situation. Additionally, attempts have been made to detect the differential pressure between the fluidized bed section and the void section above the fluidized bed, and calculate the fluidized bed height from the differential pressure and the bulk specific gravity of the fluidized medium. varies depending on the superficial velocity, type of medium, increase in ash content, etc., and the bed height estimated from this also differs, so there is a drawback that the actual bed height cannot be accurately determined.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly accurate fluidized bed height detection device that can eliminate the drawbacks of the prior art described above and can reliably detect the actual fluidized bed height.

The present invention provides a temperature sensing element in the vertical direction of the outer surface of the main body including the fluidized bed part and the empty tower part above the fluidized bed combustion apparatus, and measures the temperature gradient in the vertical direction with the cough temperature sensing element, and measures the temperature gradient in the vertical direction. The feature is that the fluidized bed is determined from the change in slope.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a sectional view of a fluidized bed combustion apparatus for explaining one embodiment of the present invention. In the figure, a fluidizing medium such as silicic acid is placed on the dispersion plate (perforated plate) 2 of the device main body 1, and is fluidized by a fluidizing gas (for example, air) supplied upward from the wind box 3 under the dispersion plate. Layer 4 is formed. Above the fluidized bed 4 is a hollow tower section 5. The side wall 6 forming the furnace body 1 is a so-called water-cooled wall, which is a furnace wall with high thermal conductivity that can withstand the internal high temperature, for example, a metal furnace wall with heat transfer tubes (water tubes) arranged therein. has a temperature sensing element 7,
For example, a large number of thermocouples, temperature-sensitive semiconductors, etc. are fixed in the vertical direction including the fluidized bed section and the empty column section.

Fixing the temperature sensing element 7 is easier, for example, in the case of a heating pair, if one with a Para) 7A attached to the tip is used, the butt 7 is fixed to the outer surface 6 of the furnace wall by argon welding or the like. be able to. The water pipes in the furnace wall 6 are connected to the drum 10 via the upper and lower headers 8 and 9, and the generated steam is taken out from the line 11, while the water in the drum 10 is connected to the water pipes in the furnace wall 6 via the header 9. Recirculated.

In the above configuration, the temperature in the vertical direction of the furnace wall 6 is detected by the temperature sensing element 7, converted into an appropriate electric signal, amplified, and displayed on a recorder (not shown) K.

Figure 2 shows an example of the temperature of the furnace wall 6 relative to the height from the dispersion plate 2. It can be seen that the tower is significantly lower. Therefore, it can be seen that the inflection point of the curve connecting these plots, in other words, the point where the temperature gradient changes the most is the fluidized bed height level H4.
In the above embodiments, it is preferable that the distance between the temperature sensing elements to be attached to the furnace wall 6, which is made of alumel, for example, be as small as possible in order to improve accuracy. When thermocouples are used, the pitch can be less than 10. Note that providing a temperature-sensitive element inside the furnace wall obstructs the flow of the medium in the fluidized bed, complicates the mounting method, and limits the number of elements, so it should be avoided. Furthermore, if one ordinary thermometer is arranged instead of the temperature sensing element of the present invention, the interval between the installations of each thermometer will be as large as about 100, making it impossible to perform highly accurate measurements.

As described above, according to the present invention, a temperature sensing element is attached to the outer surface of the furnace wall, and the height of the fluidized bed is detected based on the temperature difference between the fluidized bed section and the empty column section. The actual layer height can be measured accurately without causing errors.Also, since the temperature sensing element is installed outside the furnace, considerations such as wear resistance, strength, installation method, etc. can be made just like inside the furnace. Excellent effects can be obtained, such as a desired number of devices can be provided at short intervals without the need for additional devices, and installation is easy.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view of a fluidized bed combustion apparatus showing an embodiment of the present invention, and Fig. 2 shows the relationship between the height from the dispersion plate and the furnace wall temperature to explain the method of the present invention. It is Gura 7. 1... Combustion device (furnace) main body, 2... Dispersion plate, 3...
・Wind box, 4--Fluidized bed, 5-- Sky tower section, 6-- Furnace wall, 7-- Temperature sensing element, 7A-- Bat, 8.9--
・Header, 1o...Drum. Agent Patent Attorney Takenaga Kawakita Figure 1 Figure 2

Claims (1)

[Claims] (1) Temperature-sensing elements are provided in the vertical direction of the outer surface of the main body including the fluidized bed part and the empty tower part above the fluidized bed combustion apparatus, and the temperature gradient in the direction is measured by the temperature-sensing element. A fluidized bed height detection device characterized in that the fluidized bed height is determined from changes.