JPH01233367A - Detection of accumulation state for deposit for slurry tank - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting the accumulation status of deposits in a slurry tank.

[Conventional technology]

When slurry (solid particle S81 liquid) is stored in a tank, the specific gravity of the solid particles is usually greater than the specific gravity of the liquid, so solid particles accumulate at the bottom of the tank, causing uneven concentration of the slurry in the tank and causing a decrease in effective storage capacity.

For this reason, it is necessary to constantly monitor the deposition status of sediment in the slurry tank, but conventionally, a wire with a weight attached to it was dropped from the top of the tank, and the weight was placed on the non-flowing sediment layer. The most commonly used method is to measure the length of the wire and detect the deposition status from this (see, for example, Japanese Patent Laid-Open No. 59-62486).

[Problem to be solved by the invention]

However, the conventional detection method described above requires the weight to be seated on the deposited layer, so it can only be applied when there is a clear difference in fluidity between the slurry and the deposited layer. In the case of slurry such as high-concentration coal slurry that forms a deposited layer with a continuous solid particle concentration gradient in the tank as shown in FIG. 3, the state of deposition cannot be detected.

Further, since the above-described conventional detection method includes a mechanical mechanism such as a lifting mechanism for a weight, the detection work is likely to be hindered due to a failure of the mechanical mechanism. Furthermore, if the same point in the tank is measured regularly, the sedimentation layer at that point is disturbed by the vertical movement of the weight, which causes problems such as the sedimentation condition at that point being different from the sedimentation condition in the tank as a whole. There is also.

In view of the above-mentioned current situation, the present invention is capable of detecting the deposition status of slurry that forms a deposited layer with a continuous solid particle concentration gradient in a tank, and even with frequent measurements. An object of the present invention is to provide a method for detecting the state of deposits in a slurry tank, which does not disturb the deposited layer and does not cause the problem that detection work is easily hindered by failure of a mechanical mechanism. It is.

[Means to solve the problem]

A method for detecting the accumulation status of deposits in a slurry tank according to the present invention includes at least an ultrasonic transmitter and an ultrasonic receiver located at a lower part of a slurry tank in which slurry is stored, with an interval in the horizontal direction from each other. One set is installed, and ultrasonic waves are transmitted from the transmitter, propagated through the slurry, and received by the receiver, and from the propagation characteristics of the received ultrasonic waves, it is determined that This method is characterized in that it detects the accumulation status of sediments deposited on the ground.

Hereinafter, the method for detecting the accumulation state of deposits in a slurry tank according to the present invention will be described in detail.

FIG. 1 is an explanatory diagram showing one embodiment of the detection method of the present invention.

In FIG. 1, reference numeral 1 indicates a slurry tank in which slurry 2 is stored, and reference numerals 3 and 4 indicate an ultrasonic transmitter and an ultrasonic receiver, which are spaced apart from each other in the horizontal direction. In this invention, such a transmitter 3 and a receiver 4 are installed in the lower part of the tank 1, and ultrasonic waves are transmitted from the transmitter 3, propagated through the slurry 2, and sent to the receiver 4. By this, tank 1
This is to detect the accumulation status of sediments deposited inside.

The transmitter 3 and the receiver 4 may be installed in one set, but in order to be able to detect the situation in the height direction of the deposited layer, multiple sets of the transmitter 3 and the receiver 4 may be installed at intervals in the height direction, for example. It is preferable to install three sets as shown in the figure. The optimum frequency of the ultrasonic waves transmitted from the transmitter 3 varies depending on the properties of the slurry 2, but is generally preferably about 1 0 Hz to 1 0 MHz.

Moreover, the form of the ultrasonic wave may be a continuous wave or a pulse wave.

When ultrasonic waves are transmitted from the transmitter 3 and propagated through the slurry 2, the intensity attenuation rate and propagation speed, which are the propagation characteristics, are as follows.
It is known that there is a correlation with the solid particle concentration of slurry 2. Therefore, the intensity attenuation rate or propagation speed of ultrasonic waves is measured for a slurry of the same type as the target slurry 2 whose concentration is known, and the relationship between the solid particle concentration of the slurry and the intensity attenuation rate or propagation speed is determined by, for example, calibration. If it is determined in advance in the form of a line, the intensity attenuation rate or propagation velocity can be measured as the propagation characteristic of the ultrasonic wave propagated through the slurry 2 and received by the receiver 4. Solid particle concentration can be measured,
The accumulation status can be detected.

That is, when a set of the transmitter 3 and receiver 4 is installed, the solid particle concentration of the slurry 2 can be measured at the same height as the installation location, and the solid particles are deposited as deposits at that position. It is possible to detect whether a layer is formed or not. When multiple sets of transmitters 3 and receivers 4 are installed, it is possible to not only determine whether or not solid particles form a deposited layer, but also to determine the solid particle concentration distribution in the height direction of the deposited layer. It can also detect the situation.

However, since the propagation characteristics of ultrasonic waves change depending on the temperature of the slurry 2 and the measured solid particle concentration of the slurry 2 also differs, the installation of the transmitter 3 and the receiver 4 is as shown in the figure. A thermometer 5 is installed near the location to measure the temperature of the slurry 2 there, and the measured solid particle concentration is temperature-compensated.

〔Example〕

A pair of ultrasonic transmitter and ultrasonic receiver are installed horizontally opposite each other on the side wall of a cylindrical container with an inner diameter of room and a height of 500 m, at opposite positions at a height of 50 + a from the bottom surface, In addition, a sampling valve was installed at the same height on the side wall of the container. Then, after filling the container with a coal/water slurry with a lime powder content of 5 owt% and letting it stand still, the transmitter periodically transmits l MHz ultrasonic waves and the receiver receives the waves. The intensity attenuation rate due to the propagation of ultrasonic waves through the slurry was measured. At the same time, a coal/water slurry was sampled using a sampling pulp, and the solid particle concentration of the slurry was measured.

Figure 2 shows the time-dependent changes in the ultrasonic attenuation rate and solid particle concentration of the slurry obtained at that time.

As is clear from Fig. 2, the attenuation rate of ultrasonic waves and the solid particle concentration of the slurry change in concert, and by measuring the attenuation rate of ultrasonic waves in the coal/water slurry, It can be seen that the solid particle concentration of the slurry at the same height position can be detected.

Therefore, it can be determined from this whether or not powdered lime of the slurry is forming a deposited layer at that height.

〔Effect of the invention〕

Since the detection method of the present invention is configured as described above, it is possible to detect the deposition status of slurry that forms a deposited layer with a continuous solid particle concentration gradient in a tank. Further, even if the measurement is carried out frequently, the deposited layer is not disturbed, and the problem that the detection work is easily hindered due to failure of the mechanical mechanism does not occur.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the detection method of the present invention, and FIG. 2 shows changes over time in the intensity attenuation rate of ultrasonic waves and the solid particle concentration of the slurry obtained in an example of the present invention. The graph in FIG. 3 is a graph conceptually showing the relationship between the solid particle concentration of the slurry in the tank and the position in the height direction of the tank. In the drawings, 1...slurry tank, 2...slurry, 3...
・Ultrasonic transmitter, 4... Ultrasonic receiver, 5...
thermometer.

Claims (1)

[Claims] At least one set of an ultrasonic transducer and an ultrasonic receiver are installed at the lower part of the slurry tank in which the slurry is stored, and are spaced apart from each other in the horizontal direction, and the ultrasonic wave is transmitted from the transmitter. Then, the ultrasonic waves are propagated through the slurry and received by the receiver, and from the propagation characteristics of the ultrasonic waves received at that time,
A method for detecting the accumulation status of sediment in a slurry tank, comprising detecting the accumulation status of sediment accumulated in the tank.