JPS6113932Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a capacitance type level meter, and more particularly to a capacitance type level meter that is effective for use as a level meter for detecting the amount of hot bin stored in an asphalt plant.

The inside of a hot bin in an asphalt plant is divided into a plurality of spaces, and each storage space stores aggregates classified according to the size of each particle. The internal shape of these hot bins is complicated due to constraints such as the installation location and the difference in demand due to the size of aggregate particles, and since the hot bin is in a high temperature, high humidity, and dusty area, conventional technology A level meter that detects changes in capacitance between the electrode and the tank by suspending a single electrode, such as a wire, inside the tank, can be used for tanks with complex shapes like this hot bin. It could not be used against.

Therefore, as shown in FIG. 6, as a conventional device for detecting the amount of food stored in a hot bin, rotating blades A or reciprocating flat plates are installed at at least two locations above and below the hot bin B to detect the amount of food stored in the hot bin. A device has been used that detects the upper and lower limit positions by preventing the aggregate C from moving. However, the above-mentioned conventional devices can only monitor large increases and decreases, and it is difficult to perform accurate feeding operations in response to increases and decreases due to factors such as changes in the particle size structure and mix of aggregate. Therefore, overflow due to excessive supply or material waiting due to insufficient supply were likely to occur, which could impede the smooth operation of the plant.

In view of the above points, the present invention uses two electrodes, and forms an inclined part on the upper part of a heat-resistant insulating plate that holds the space between the two electrodes. The purpose of the present invention is to provide a capacitance type level meter that can be used without any trouble even in tanks with complicated shapes such as hot bins by having the capacitance level meters installed parallel to each other at offset positions. That is.

Next, an embodiment of the capacitive level meter according to the present invention will be described with reference to the drawings.

In the figure, 1 is a mixing tower installed in an asphalt plant. This tower 1 is fixed to the ground by a pedestal 2 and an elevator 3 for aggregate, etc., and a multi-stage pedestal is installed in the middle of the pedestal 2. 4 are installed to form the structure of the tower 1. A screen 5, a hot bin 6, a measuring plate 7, and a mixer 8 are attached to this structure in order from the top, and dry heated aggregate, etc., which is a medium for asphalt products, is supplied from a hopper 9 to the base of the elevator 3. After that, the aggregate is poured into a screen 5 from the top of the elevator 3, divided into aggregates with different particle sizes, and then fed into a hot bin 6. Furthermore, after being weighed and mixed during the falling process, the product is dropped onto a dump truck.

The inside of the hot bin 6 is divided into a plurality of spaces by a partition plate 10, as shown in FIG.
Each of these divided spaces serves as a storage space 12 in which aggregates 11 of different particles are separated and stored. Each of the storage spaces 12 is set to a variety of sizes depending on the demand for the aggregate 11 to be stored, and a detection unit 13 of the electrostatic level meter according to the present invention is attached to each storage space 12. ing. This detection unit 13 is roughly composed of two electrodes 14 and 15 and a heat-resistant insulating plate 16, and the insulating plate 16 is made by molding a tetrafluoroethylene material into the shape shown in FIG. ing. That is, this insulating plate 16 has a substantially rectangular parallelepiped shape, and one half of the front side of the upper part is cut obliquely toward the upper rear side to form a front side inclined part 17. The back side of the insulating plate corresponding to the inclined portion 17 is an electrode mounting surface 18 . Also,
The upper part of the other half on the electrode mounting surface 18 side is cut obliquely toward the upper front side to form a rear side inclined part 19, and the back side of the insulating plate corresponding to this rear side inclined part 19. The other half of the front side inclined portion 19 serves as an electrode mounting surface 20 . Electrode mounting screw holes 21, 21 are formed at the upper and lower positions of each of the electrode mounting surfaces 18, 20, and the width of the electrode mounting surfaces 18, 20, that is, the inclined portion 17, Plate-shaped electrodes 14 and 15 having a width equivalent to the width of electrode 19 are fixed with mounting screws 22 and 22. In this way, the electrodes 14 and 15 are held parallel to each other at offset positions by the heat-resistant insulating plate 16, as shown in FIG.

The detection unit 13 with the above configuration has a coaxial cable 23
It is connected to a capacitance change detecting device 24 provided outside the hot bin 6 via a capacitance change detecting device 24, and a CR coupling amplifier is used as the detecting device 24 in this embodiment. Further, this capacitance change detection device 24 is connected to an indicating device 25, and the capacitance change is converted into a storage amount and displayed.

The operation of the capacitive level meter described above will be explained below.

The aggregate 11 in the hot bin 6 is sequentially sent to the mixer 8 via the weighing machine 7 according to demand, and when the amount of aggregate 11 stored in the hot bin 6 decreases, the gap between the electrodes 14 and 15 is reduced. The aggregate 11 that was acting as an electrostatic body decreases, and the capacitance between the electrodes 14 and 15 decreases accordingly. This change in capacitance is detected by the capacitance change detection device 24, converted into a storage amount, and displayed on the indicator 25. When the indicated value displayed on the indicating device 25 falls below a certain value, the aggregate 11 is automatically or manually operated.
is supplied into the hot bin 6, and by this operation of supplying the aggregate 11, the electrodes 14, 1
As the aggregate 11 continues to be filled between the electrodes 14 and 15, the capacitance between the electrodes 14 and 15 increases, and when the indicated value of the indicating device 25 exceeds a certain value, the supply amount of the aggregate 11 is controlled manually or automatically. is reduced. In this way, the amount of aggregate 11 stored can be constantly monitored and it is possible to recognize whether the amount is increasing or decreasing, so the amount of aggregate 11 supplied can be adjusted. It can be made certain. Further, when the aggregate 11 increases or decreases, the heat-resistant insulating plate 16 is covered with the aggregate 11, but the upper part of the insulating plate 16 has an inclined portion 1.
7 and 19 are formed, even if the amount of aggregate 11 falls below the position of the insulating plate 16, the aggregate 1
There is no risk that 1 will remain deposited on the insulating plate 16, and an accurate storage amount will be detected.
In addition, since the electrodes 14 and 15 are held at positions shifted from each other, there is no risk that the aggregate 11 will remain sandwiched between the electrodes 14 and 15 and the detected value will be erroneous. Furthermore, since two electrodes are used, accurate detection values can be obtained regardless of the internal shape of the hot bin 6.

In addition, in the above embodiment, the capacitance change detection device 2
4, a CR coupling amplifier is used, but a detection device using a high frequency oscillator, a tuned amplifier, etc. may also be used.

As explained above, according to the present invention, two wires constituting the sensor section of a capacitance type level meter, one
Since the pair of electrodes 14 and 15 are connected together in advance by the heat-resistant insulating plate 16, handling such as moving and installing the sensor part is easy, and it is suitable for use in hopper-type hot bins in asphalt plants without top lids. It can be accurately attached to a suitable location independently of the outer wall of the hot bin, and has the effect of obtaining accurate detection values regardless of the internal shape of the hot bin. Furthermore, the inside of a hot bin in an asphalt plant is high temperature, high humidity, and highly dusty, and aggregates supplied from the top of the hot bin are deposited or cross-linked between the two electrodes, especially on the top of the heat-resistant insulating plate 16. However, since the heat-resistant insulating board of the present invention has a sloped portion at the top, even when stored materials such as aggregate increase or decrease, the stored materials remain accumulated on the insulating board. This has the effect of being able to accurately detect the stored amount without the risk of the storage being caused, and furthermore, since the two electrodes are held at mutually shifted positions, it is possible to prevent the stored material from being held between the electrodes. This has the effect that there is no risk that the detected value will go awry over time.

Therefore, if the capacitance type level meter according to the present invention is used in a hot bin, it is possible to constantly monitor the amount of aggregate stored and to recognize whether the amount of stored aggregate is increasing or decreasing. Therefore, the amount of aggregate supplied to the hot bin can be reliably adjusted, and the plant can be operated smoothly.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a mixing tower of an asphalt plant having a hot bin, Fig. 2 is a sectional view of the hot bin to which a level meter according to the present invention is attached, Fig. 3 is a perspective view of a heat-resistant insulating plate, and Fig. 4 is a perspective view showing a mixing tower of an asphalt plant having a hot bin. The figure is a perspective view showing the state in which electrodes are attached to the heat-resistant insulating plate shown in Fig. 3, Fig. 5 is a plan view of Fig. 4, and Fig. 6 shows the main parts of a hot bin to which a conventional level meter is attached. FIG. 14, 15... Electrode, 16... Heat resistant insulating plate, 1
7... Front side inclined part, 19... Rear side inclined part, 1
8, 20... Electrode mounting surface, 24... Capacitance change detection device.

Claims (1)

[Scope of utility model registration request] It is equipped with a pair of electrodes 14 and 15 that are held parallel to each other, and a capacitance change detection device 25 that detects the capacitance between these two electrodes, and the electrodes are inserted into a hot bin. In a capacitive level meter for detecting the amount stored in a hopper-type hot bin in a retained asphalt plant,
A heat-resistant insulating plate 16 is interposed and fixed between the two electrodes in the hot bin, and the heat-resistant insulating plate 16 has a substantially rectangular shape, and one half of the upper half of the front side is inclined toward the upper rear side. As a result, a front side inclined part 17 is formed, and the back side of the insulating plate corresponding to this front side inclined part 17 is a back side electrode mounting surface 1 to which one of the electrodes is attached.
8, and the upper part of the rear side of the other half of this rear side electrode mounting surface 18 side is inclined upwardly toward the front side, thereby forming a rear side inclined part 19, and this rear side A capacitive level meter characterized in that the front side of the insulating plate corresponding to the inclined part 19 is configured as a front side electrode mounting surface 20 to which the other electrode is attached.