JPH0436620A - Device detecting boundary surface between two liquid layers by utilizing ultrasonic wave - Google Patents

Abstract

PURPOSE:To easily and accurately detect the boundary surface between two liquid layers in a tank regardless of the kind of liquid including a water medium by shifting an incidence probe and a detecting probe in a position while synchronizing them with each other in the up-down direction. CONSTITUTION:When a suspension of mixed water and oil is settled as it is to separate them, a mixture layer III is present between an oil layer I which is small in specific gravity and a water layer II which is large in specific gravity and sinks downward. An ultrasonic wave pulse is made incident into the liquid in this state through the probe 2 and ultrasonic waves which are transmitted through the oil layer I, mixture layer III, and water layer II and received by a receiver 5 through the detecting probe 3 have waveforms shown by A, B, and C. Namely, the wave which is transmitted through the oil layer I is longer in propagation time than the wave transmitted through the water layer II (T1>T2) and the wave transmitted through the mixture layer III has a composite waveform corresponding to the ratio of the constituent components and two peaks. Therefore, when the waveforms are observed at three vertically adjacent points on the outer periphery of the tank, the presence of the boundary surface can be recognized at the position B of the probe 3.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention is a method of detecting the interface between two liquid layers using ultrasonic waves when two liquids that are substantially immiscible exist in a layer in a tank. It relates to a device for detecting.

[Conventional technology]

For example, in the process of extracting water-soluble substances contained in oily substances by washing them with water, a suspension of water and oil is allowed to stand in a tank and separated, and then extracted separately. At this time, it is necessary to know where the interface between the two liquid layers is in the tank and to check the amount of each liquid. Conventionally, a simple way to determine the boundary surface was to insert a glass tube into a tank, close the top end, pull it out while filling the tube with liquid, and visually observe the inside of the tube.
This is not a very accurate method and is only practical for small tanks. If you install a level gauge outside the tank, you can immediately see the boundary surface, but when separating a suspension liquid as described above, the separation of the liquid inside the gauge has a time lag compared to that inside the tank. and often suffer from a lack of accuracy. On the other hand, a device for detecting the interface between two liquid layers using ultrasonic waves has been proposed (Japanese Patent Application Laid-open No. 120020/1983). This device emits ultrasonic pulses from the outer periphery of the tank wall, calculates the attenuation constant from the height and path length of the reflected echo, which varies depending on the type of liquid, and uses this to determine the boundaries. This method has the problem of being easily affected by noise, especially when one of the liquids is a water medium, and the ratio of the ultrasonic propagation time between the steel, which is the material that usually makes up the tank, and the water is sufficiently large. Due to this fact, it is not easy to detect the liquid interface.

[Problem to be solved by the invention]

The purpose of the present invention is to solve the above-mentioned problems in detecting the interface between two liquid layers using ultrasonic waves, and to easily detect the interface between two liquid layers in a tank regardless of the type of liquid, including water media. The object of the present invention is to provide a device that accurately detects the present invention.

[Means to solve the problem]

As shown in the overall configuration of the device for detecting the interface between two liquid layers using ultrasonic waves according to the present invention, as shown in FIG. A probe (2) for injecting ultrasonic pulses through the tank wall (1) at two points on the outer periphery facing each other across the center of the tank housed in the tank, and a probe (2) for injecting an ultrasonic pulse into the liquid A probe (3) for detecting the transmitted ultrasonic waves is brought into contact with the tank, and the ultrasonic waves are received by the transmitter (4) and the detection probe. [ Effect] When a suspension of water and oil is allowed to stand still and separated, the boundary surface becomes one plane after a very long period of time, but in general, during the separation process, as shown in Figure 2, the boundary surface becomes one plane. In such a case, a mixed layer (II) exists between the oil layer (I), which has a small specific gravity and floats upward, and the water layer (II), which has a large specific gravity and sinks downward. There is virtually no problem even if there is a boundary layer between two liquids with an intermediate layer.When an ultrasonic pulse is introduced into a liquid in the above state, it is received after passing through each of the oil layer, mixed layer, and water layer. The waveforms of the ultrasonic waves are shown in Figure 3 A, B, and C. In other words, the waveforms of the ultrasonic waves that have passed through the oil layer take longer to propagate than those that have passed through the water layer (TI > T2).
), the sound pressure level is lower, with a difference of -40 db. The mixed layer is synthesized according to the ratio of the components constituting the layer, and has a waveform with two peaks. Therefore, when waveforms as shown in FIG. 3 are observed at three vertically adjacent points on the outer circumference of the tank, it means that a boundary surface exists at the position B of the probe. The ultrasonic pulse incident on the tank wall travels through the steel wall and reaches the detection probe (3), but its propagation time is short and it goes without saying that it can be easily distinguished from transmitted waves.
If the target is transmitted waves, unlike when using reflectors, the influence of noise is hardly a problem. [Embodiment] The probes (2, 3) may be set as a set, one each on the incidence side and the detection side, and moved up and down along the outer periphery of the tank wall (1) while matching their positions. . As a mechanism for performing such vertical movement, for example, the one shown in FIG. 4 is useful. That is, a guide (61) is fixed to the outer periphery of the tank wall (1) and has a slot (66) extending vertically parallel to the tank wall, and the guide (61) is located parallel to this guide and is rotationally driven by a motor (62). The screw shaft (63) is engaged with the screw shaft at one end (67), and the probe (2, 3) is held by the case part (68) at the other end and pressed against the outer circumference of the tank wall. , a mechanism (6) consisting of a probe holder (64) that moves up and down as the screw shaft rotates. The above-mentioned mechanism is particularly suitable in cases where the interface between two liquid layers usually exists within a relatively narrow range within a tank. When the position of the boundary surface varies over a wide range, the embodiment shown in FIG. 5 is preferable. In the embodiment shown in FIG. 5, a large number of incident probes (2a, 2b, 2c, -) and detection probes (3a, 3b, 3c, ...) are placed at corresponding positions on the outer periphery of the tank wall in the vertical direction. and between the transmitter (4) and the entrance probe and between the corresponding detection probe and the receiver (5) switch means (7:7a. 7b, 7G, -) and ( 8:8a, 8b, 8c...), and a controller (9) that sequentially connects and disconnects them is provided to direct the ultrasonic pulses passing through the liquid from above to below (or vice versa). ) Scanning achieves the same effect as if the position of the probe were moved sequentially. Of course, the above two methods can also be used in combination. [Effects of the Invention] If the device of the present invention is used to detect the interface between two substantially immiscible liquid layers contained in a tank, the boundary can be quickly and accurately detected regardless of the type of liquid. You can know the face. Therefore, the present invention is expected to find wide applications in various chemical industries, particularly in the petrochemical industry, the food industry, and the cosmetics industry.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the basic configuration of the boundary surface detection device of the present invention. FIG. 2 is a schematic cross-sectional view showing the state of two liquid layers in the separation process. FIG. 3C is a graph showing the waveform of an ultrasonic pulse transmitted through the liquid shown in FIG. Show each thing. FIG. 4 is a side view showing an example of a mechanism for vertically moving a probe for injecting and detecting ultrasonic pulses along the outer periphery of a tank wall in the boundary surface detection device of the present invention. FIG. 5 is a conceptual diagram showing another aspect of the boundary surface detection device of the present invention using the mechanism shown in FIG. 4. ■...Layer of liquid with low specific gravity■...Layer of liquid with high specific gravity■...Mixed layer 1...Tank wall 2 (2a, 2b, 2c, -) -...Injection probe 3 (
3a, 3b, 3C, -> -...Detection probe 4...Transmitter 5...Receiver 6...Probe vertical movement mechanism 61...Guide 62...Motor 63...Screw shaft 64...Probe holder 7 (7a , 7b, 7c,...)...switch means 8 (8
a, 8b, 8c,...)...Switching means 9...Controller 184 Figure 3 Figure 1 Figure 2 Procedural amendment (method) September 25, 1991 1, Indication of case 1990 Patent Application No. 38128 No. 2, Name of the invention Device for detecting the interface between two liquid layers using ultrasonic waves 3, Relationship with the person making the amendment case Patent applicant address: 2-2-1 Otemachi, Chiyoda-ku, Tokyo Name (441) JGC Corporation Representative Eiji Watanabe 4, Agent 104 Address 10, 2-15-14 Tsukiji, Chuo-ku, Tokyo
The paragraph "FIG. 3 C shows..." regarding FIG. 3 on lines 14 to 17 of the page should be rewritten as follows. Figure 3 is a graph showing the waveform of an ultrasonic pulse transmitted through the liquid shown in Figure 2, with the upper row A in the oil layer, the middle row B in the mixed layer, and the lower row C. is in the water layer,
Shows what has passed through each. ” Shipping mortar August 27, 1991 6, Procedural amendment in the column for a brief explanation of the drawings of the specification subject to amendment (September 25, 1991 1, Case indication 1990 Patent Application No. 38128 2. Name of the invention Device for detecting the interface between two liquid layers using ultrasonic waves 3. Relationship with the person making the amendment case Patent applicant address 2-2-1 Otemachi, Chiyoda-ku, Tokyo Name (441) JGC Corporation Representative Eiji Watanabe 4, Agent 104 Address 2-15-14 Tsukiji, Chuo-ku, Tokyo Column 6 of the detailed description of the invention in the specification, Contents of amendment, page 7, No. 5- Rewrite the paragraph in line 13, ``A waveform like the one above.'' as follows. The waveforms of the ultrasonic waves transmitted through the oil layer and the water layer and received are shown in Figure 3. In other words, the waveforms of the ultrasonic waves that have passed through the oil layer are shown in the upper part (A) of the figure, and those that have passed through the water layer are shown in the upper part (A) of the figure. The waveforms are shown in the lower part (C) of the figure, and the former takes longer propagation time than the latter (
TI) T2), the sound pressure level is lower, with a difference of -40 db. As shown in the middle part (B) of the figure, what passes through the mixed layer is a waveform in which the above two types of waveforms are combined according to the ratio of the components constituting the layer, and the peaks appear twice. ”-14・

Claims (4)

[Claims] (1) For a tank containing two substantially immiscible liquids (I, II) in layers, at two points on the outer periphery facing each other across the center, ) for injecting an ultrasonic pulse through the probe (2);
Probe (3) for detecting ultrasonic waves transmitted through the liquid
) in contact with the tank, a transmitter (4) for injecting ultrasonic waves from the incident probe, and a receiver (5) for measuring the waveform and sound pressure level of the ultrasonic waves received by the detection probe. )
An apparatus for detecting an interface between two liquid layers using ultrasonic waves, comprising a mechanism (6) for vertically synchronizing and moving the positions of an incident probe and a detection probe. (2) The apparatus according to claim 1, wherein each set of one entrance probe and one detection probe is moved up and down along the outer periphery of the tank wall while making their positions correspond to each other. (3) In order to move the probe up and down along the outer circumference of the tank wall, a guide (61) is fixed to the outer circumference of the tank wall and has a slot (66) extending vertically in parallel with the guide (61), at a position parallel to this guide. The screw shaft (63) is rotationally driven by the motor (62), and the nut portion (6
A probe holder (64) that engages with this screw shaft at 7) holds the probes (2, 3) at the other end of the case portion (68) and presses them against the outer periphery of the tank wall, and moves up and down as the screw shaft rotates. 3. The apparatus of claim 2, further comprising a mechanism comprising: ). (4) A large number of incident probes (2a, 2b, 2c,...) and detection probes (3a, 3b, 3c,...) are fixed vertically at corresponding positions on the outer circumference of the tank wall, Switches (7a, 7b, 7c, ... and 8a, 8b, 8c, ...) are arranged between the transmitter and the input probe and between the corresponding detection probe and the receiver, and these are sequentially 2. The device according to claim 1, further comprising a controller (9) for connecting and disconnecting, and configured to move the position of the probe by scanning ultrasonic pulses transmitted through the liquid.