JPS6236524B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring the flow rate of granular materials such as pulverized coal or lumps of coal, etc., transported along a transportation route.

Conventionally, devices for measuring the flow rate of granular materials such as pulverized coal transported in pipes include gravimetric flowmeters,
There are impact flowmeters, differential pressure flowmeters, etc., but gravimetric flowmeters and impact flowmeters are difficult to install in the middle of a transportation pipe, and differential pressure flowmeters are difficult to install in the middle of a transportation pipe, and differential pressure flowmeters are difficult to install because powder or granules are present at the outlet that detects the differential pressure. It has the disadvantage of being clogged.

In view of the drawbacks of the conventional devices as described above, the present invention provides an excellent microwave flow rate measuring device that can be installed even in the middle of a transportation route and does not have the disadvantage of powder and granular materials accumulating in the middle of the transportation route. The purpose is to provide the following.

In the present invention, the resonant frequency of a microwave resonator interposed in the middle of a transport path has a constant relationship with the dielectric constant of a dielectric material attached to the inner surface of the microwave resonator, and the dielectric constant is There is a certain relationship with the density of the powder, etc., which is a dielectric material, passing through the microwave resonator, so the density of the powder, etc. can be determined by detecting the resonant frequency of the microwave resonator. However, when detecting the resonant frequency, the microwave standing waves existing in the microwave resonator act as a spatial filter for the so-called powder and granular materials, and are Since the resonant frequency is changed at a constant frequency, the moving speed of the powder or granular material is measured by measuring the periodic change in the resonant frequency. Note that in the present invention, microwave means a high frequency wave having a frequency of 300 MHz to 30 GHz.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Below, a microwave flow rate measuring device according to the present invention (hereinafter referred to as the present invention flow rate measuring device) will be explained based on drawings showing one embodiment thereof.

FIG. 1 is a block diagram of the flow rate measuring device of the present invention, in which 1 indicates a particulate material 2 such as pulverized coal with a white arrow A.
This is a transportation pipe made of metal such as steel or plastic such as vinyl chloride, used for transportation as shown in the figure. An open-ended microwave resonator 3 is formed in the middle of the transport pipe 1 as shown below. That is, a resonant metal pipe 31 having an inner diameter larger than the inner diameter of the transport pipe 1 and made of metal such as steel is connected to an appropriate metal member 32 (in the embodiment shown in FIG. 1, the metal member 32 has flanges at both ends thereof). The resonant metal pipe 31 has an inner pipe member made of a dielectric material such as Teflon or polyethylene on the inner wall 31a side of the resonant metal pipe 31. 33 is installed so that the inner surface 33a of the inner pipe member 33 and the inner surface 1a of the transport pipe 1 are connected in a substantially flush state. In addition,
When the transport pipe 1 is made of metal, the resonant metal pipe 31 is directly screwed and communicated with the outer edge 1b of the transport pipe 1, as shown in FIG. 2, without intervening an appropriate metal member 32. It's okay. Alternatively, as shown in FIG. 5, a suitable metal member 32 may be formed by a flange 1a provided at the end of the metal transport pipe 1. 34 is a microwave input section provided on the resonant metal pipe 31 of the microwave resonator 3, and 35 is a microwave output section provided on the resonant metal pipe 31.

Reference numeral 4 denotes a resonant frequency measuring circuit for measuring the resonant frequency of the microwave resonator 3 configured as described above, and in the illustrated embodiment, it includes a frequency modulation microwave generating circuit 5, a resonant frequency detecting circuit 6, and a pulse generator. It consists of a generating circuit 7.

The frequency modulation microwave generation circuit 5
High frequency oscillator 5 that generates a 1MHz high frequency signal a
1 and a 10-bit counter 52 which inputs the high frequency signal a [see FIG. 3 a] output from the high frequency oscillator 51 and measures the number of vibrations of the high frequency signal a.
and all bit signals output from the counter 52
An appropriate width (for example, 2.9 Voltage control that generates frequency modulated microwaves (from 3.2GHz to 3.2GHz)
This circuit outputs a frequency modulated microwave d (see FIG. 3d) to the microwave input section 34 of the microwave resonator 3.

The pulse generating circuit 7 is a circuit that inputs the start signal b output from the counter 52 and outputs a pulse signal g every time the measurement is restarted from O [see FIG. 3g].

The resonant frequency detection circuit 6 includes a detector 61 that detects the microwave output output from the microwave output section 35 of the microwave resonator 3, and a monostable circuit that removes noise from the signal output from the detector 61. 62, the resonance pulse e outputted from the monostable circuit 62 (see FIG. 3e), and the all-bit signal b' outputted from the counter 52, and the resonance frequency is analyzed and detected. A latch circuit 63 that holds the frequency value until the next resonance, a latching resonance frequency signal f output from the latch circuit 63, and a pulse signal g output from the pulse generation circuit 7.
is input to the latch circuit 64 [third
See figure h. Note that Fig. 3 (i) shows the overall waveform of the signal of which the signal in Fig. (h) is a part.]
and a D/A converter 6 which analogizes the latching resonance frequency signal h output from the latch circuit 64 and converts it into a resonance frequency signal j (see FIG. 3 j).
It consists of 5.

8 inputs the resonance frequency signal j [see FIG. 3 j] output from the resonance frequency measurement circuit 4,
This is a density calculating circuit that calculates the density ρ of the powder or granular material 2 based on the resonance frequency signal j, and in the illustrated embodiment, the resonant frequency and the powder or granular material density are constant, which is determined by experiment in advance. The linearizer 81 calculates the density from the value of the input resonance frequency signal j based on the functional relationship between '', the density is changed periodically by a small amount, so the filter 82 includes a low-pass filter 82 for determining the average density ρ.

9 is a speed calculating circuit which inputs the resonant frequency signal j output from the resonant frequency measuring circuit 4 and calculates the transport speed v of the powder or granular material 2 by paying attention to periodic changes in the resonant frequency signal j. , in the illustrated embodiment, a high pass filter 91 and a speed calculation circuit 92.
It consists of. That is, in the microwave resonator 3 having a length L, a microwave standing wave M having a period T exists as shown in FIG. Each time, the resonant frequency becomes smaller and smaller. In other words, the microwave standing wave M constitutes a so-called spatial filter having a length L and a period T. Therefore, the frequency ν of the periodic change in the resonant frequency signal j due to the action of the spatial filter is detected by the high-pass filter 91, and the frequency ν and the period T of the microwave stationary M are calculated in the speed calculation circuit 92. By multiplying, the velocity v(ν×T) can be found.

10 inputs the speed signal v output from the speed calculation circuit and the density signal ρ output from the density calculation circuit 8, and multiplies the value of the speed signal v by the value of the density signal ρ, thereby calculating the transport speed. This is a flow rate calculation circuit that calculates the flow rate V of the powder and granular material 2 sent through the pipe 1.

The flow rate measuring device of the present invention having the configuration as described above is used as described below.

The powder 2 sent through the transport pipe passes through the microwave resonator 3, but the inner pipe member 33 of the microwave resonator 3 has an inner surface 33a and an inner surface 1a of the transport pipe 1 in a plane. Since the microwave resonator 3 is installed so as to be connected in one state,
There are no gaps at all inside the microwave resonator 3, so the powder 2 flows smoothly inside the microwave resonator 3 without being accumulated in the gaps. Since the granular material 2 flowing in this way is a dielectric material, the dielectric constant within the microwave resonator 3 changes as the density of the granular material 2 changes, and eventually the resonant frequency depends on the density of the granular material 2. Change according to change. The resonant frequency measuring circuit 4 measures the changing resonant frequency, and the density calculating circuit 8 inputs the resonant frequency signal j output from the resonant frequency measuring circuit 4, and calculates the particle size based on the value of the resonant frequency signal j. Calculate body density ρ. Other speed calculation circuit 9
inputs the resonant frequency signal, analyzes and detects the period of the resonant frequency signal j that changes periodically by the microwave standing wave spatial filter, and calculates the transport speed v of the powder and granular material 2 based on the period. The flow rate calculation circuit 10 calculates the flow rate V of the powder or granular material 2 based on the velocity v and the density ρ of the powder or granular material 2. The flow measuring device of the present invention has a pulverized coal injection amount of 9.2 t/H, an air injection amount of 5.2×10 ³ Nm ³ /H, a transport pipe inner diameter of 52.9 mm,
The length of the resonant metal pipe is 675 mm, the inner diameter of the resonant metal pipe is 67.9 mm, the inner pipe member is made of Teflon, and the accuracy was within ±2% when tested under the conditions of a microwave frequency of 2.9 to 3.2 GHz, which is suitable for practical use. It was proven that there were no problems at all.

By the way, although this embodiment was applied to powder and granular materials, it goes without saying that the present apparatus can also be applied to lumps such as coal.

As is clear from the above description, the density measuring device of the present invention and the flow rate measuring device of the present invention can be easily installed in the middle of a transportation route, and even if they are installed, powder and granules will not be contained in these devices. This is an excellent device for measuring the flow rate of powder and granular materials that does not accumulate.

[Brief explanation of the drawing]

The drawings are for explaining embodiments of the flow rate measuring device of the present invention, and FIG. 1 is a block diagram of the density measuring device of the present invention and the flow rate measuring device of the present invention, and FIG. 2 is a cross section of a microwave resonator. Figures 3 and 3 are graphs showing the output signals of each circuit of the flow rate measuring device of the present invention (vertical axis: each signal value, horizontal axis: time), in which figure a is a diagram of the output signal of the high frequency oscillator, figure b Figure c is a diagram of the output signal of the counter, Figure c is a diagram of the output signal from the D/A converter 53, Figure d is a simplified diagram of the frequency modulated microwave output from the frequency modulation circuit, and Figure e is the output from the microwave resonator. Signal diagrams: Figure G is an output signal diagram from the pulse generation circuit, Figure H is an output signal diagram from a latch circuit, Figure I is an overall signal waveform diagram that includes the output signal from the latch circuit as a part, and Figure J is a diagram of the output signal from the latch circuit. FIG. 4 is a sectional view of a microwave resonator for explaining a spatial filter for microwave standing waves, and FIG. 5 is a sectional view of the microwave resonator. 1... Transport pipe, 1a... Inner surface, 2... Powder, 3
...Microwave resonator, 31...Resonant metal pipe, 3
1a...Inner wall, 32...Appropriate metal member, 33...Inner pipe member, 33a...Inner surface, 4...Resonance frequency measurement circuit, 5...Frequency modulation microwave generation circuit, 6...
Resonant frequency detection circuit, 7... Pulse generation circuit, 8...
Density calculation circuit, 9... Speed calculation circuit, 10... Flow rate calculation circuit.

Claims (1)

[Claims] 1. A microwave resonator that is installed in a transport path for transporting powder, granular materials, etc. and has a member made of a dielectric material attached to its inner surface, a resonant frequency measuring circuit that measures the resonant frequency of the microwave resonator, and A density measurement system includes a density calculation circuit that calculates the density of powder, granular material, etc. flowing in the transportation route based on a resonance frequency signal output from the resonance frequency measurement circuit, and a speed calculating circuit which inputs a resonant frequency signal generated in the microwave resonator, analyzes a change in the resonant frequency caused by the microwave standing wave spatial filter generated in the microwave resonator, and calculates the transport speed of the powder or granular material from the changed frequency; , a flow rate calculation circuit that receives the speed signal output from the speed calculation circuit and the density signal output from the density calculation circuit and calculates the flow rate of the powder or granular material, etc. Flow measurement device.