JPH09273957A - Level measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the level of a medium even when the condition shifts to a high temperature. SOLUTION: A medium 2 tended to heat up to a high temperature (e.g. 1,000 deg.C) is stored, in layers in a layer storage container 1. A detection end 20 is made up of a guide pipe 21, ceramic 22 and an electrode 23 as main component. An capacitance between the electrode 23 of the detection end 20 and the layer storage container 1 is measured by a capacitance meter 10 to detect the level of the medium 2. The ceramic 22 for insulation between the guide pipe 21 and the electrode 23 is retained at its lower part by the electrode 23, an external sleeve 23d and the like while the upper part thereof is retained by the guide pipe 21, an internal sleeve 21e and the like. The ceramic 22 the dielectric constant of which varies with changes in temperature is not interposed between the guide pipe 21 (the internal sleeve 21e) and a bar-shaped part 23a of the electrode 23 in view of possible electric influence. This eliminates changes in the capacitance attributed to possible temperature changes between the guide pipe 21 and the bar-shaped part 23a thereby enabling accurate detection of the capacitance between the electrode 23 and the layer storage container 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a level measuring device, and in particular, it is devised so that the level of a storage layer of powder or liquid can be accurately measured without being affected by temperature changes. Is.

[0002]

2. Description of the Related Art In order to control various plants, a level measuring device for monitoring the storage amount of a storage facility is indispensable. Among the level measuring devices, the level measuring device of the type that uses capacitance to measure has a strong resistance to the environment inside the reservoir because the detection end is metal and no moving parts are required. It is effective when used for level measurement under environmental conditions such as high temperature and high pressure.

A conventional electrostatic capacitance type level measuring device will be described with reference to FIG. As shown in the figure, a powder or liquid medium 2 is stored in the storage container 1. In order to detect the level of the medium 2, the detection end 3 of the level measuring device is attached so as to project downward from the upper part of the reservoir container 1.

The detection end 3 is mainly composed of a guide pipe 4, a ceramic 5 and an electrode 6. Of these, the guide pipe 4 is a cylindrical guide pipe body 4
a, a flange portion 4b projecting to the outer peripheral side at the upper end of the guide pipe body 4a, and an inward flange portion 4c projecting to the inner peripheral side at the lower inner peripheral surface of the guide pipe body 4a.

A cylindrical ceramic 5 used as an insulating material between the guide pipe 4 and the electrode 6 is inserted and arranged in the lower inner circumference of the guide pipe 4, and the inward flange 4 is provided.
It contacts the lower surface of c and the surface of the inner peripheral surface of the guide pipe body 4a, which is lower than the inward flange 4c.

Further, in the electrode 6, the lower part thereof is the electrode main body 6b having a large diameter, but the upper part thereof is a bar-shaped part 6a having a smaller diameter than that of the lower part. The rod-shaped portion 6a of the electrode 6 is inserted into the center hole of the ceramic 5 and penetrates the center hole of the inward flange portion 4c so as to project above the inward flange portion 4c. In addition, the electrode body 6b projects downward and is inserted into the medium 2.

A ring-shaped insulating material 7 is interposed between the inward flange portion 4c and the rod-shaped portion 6a. Also, the rod-shaped portion 6
A is fastened by a fixing tool 9 via a ring-shaped insulating material 8.

By doing so, the guide pipe 4, the ceramic 5 and the electrode 6 are integrated. Moreover, the insulating state is secured between the guide pipe 4 and the electrode 6 made of metal (conductive material) by interposing an insulating material (ceramic 5, ring-shaped insulating material 7, 8).

The capacitance meter 10 is electrically connected to the reservoir container 1 and the electrode 6 (bar-shaped portion 6a) via a signal line 11. Then, the capacitance meter 10 measures the capacitance between the electrode 6 and the reservoir container 1 (this is referred to as the first capacitance).
Not only the capacitance between the electrode 6 (particularly the rod-shaped portion 6a arranged in the guide pipe 4) and the guide pipe 4 (this is referred to as the second capacitance) is also detected. After all, the overall capacitance detected by the detection end 3 is the sum of the first and second capacitances. The first electrostatic capacitance directly contributes to the level fluctuation detection of the medium 2, but the second electrostatic capacitance does not directly contribute to the level fluctuation detection and does not function as a noise element when there is a temperature change. (Details will be described later).

The level converter 12 includes a storage container 1 and a medium 2
When there is no medium, the value detected by the capacitance meter 10 as the capacitance of the detection end 1 is stored as an initial value. The value detected by the capacitance meter 10 as the capacitance of the detection end 1 is detected as a detection value. Then, calculation is performed based on the change in the detected value and the initial value, the level of the medium 2 is detected, and the level signal indicating this level is output.

[0011]

In the level measuring device utilizing the change in capacitance, the medium 2 and the insulating material (5, 5) are used.
The dielectric constant of 7, 8) affects the measurement accuracy. However, since the permittivity of a substance is highly temperature-dependent, the permittivity may change from the set value if the temperature of the preset permittivity and the temperature at the time of actual level measurement are different, In such a case, accurate level measurement cannot be performed.

Particularly, in the conventional detecting end 3 shown in FIG. 4, an insulating material (ceramic 5, ring-shaped insulating material 7, 8) is inserted in a narrow portion between the guide pipe 4 which is a conductive material and the electrode 6. There is. That is, the surface of the guide pipe 4 and the surface of the electrode 6 face each other via the insulating material (5, 7, 8). For this reason, the second capacitance between the electrode 6 and the guide pipe 4 is much larger than the second capacitance between the electrode 6 and the reservoir container 1. Therefore, when the dielectric constant of the insulating material (5, 7, 8) changes due to the temperature change, the capacitance changes corresponding to the change of the dielectric constant, and the level of the medium 2 to be detected is changed. The change in capacitance due to the change may become unknown.

The insulating material (5,
In order to suppress the change in permittivity (7, 8), a method of using an insulating material having a small permittivity or installing a temperature measuring device to perform temperature correction has been studied. However, the reservoir 1
In the environment where the internal temperature is close to 1000 ° C, there is no insulating material whose dielectric constant changes little. Further, even if the temperature is corrected, the accurate temperature cannot be grasped due to the influence of the temperature distribution and the like, so that the sufficient correction cannot be performed.

In view of the above-mentioned prior art, it is an object of the present invention to provide a level measuring device capable of accurately detecting the level of a medium even if the temperature of the object to be detected changes greatly.

[0015]

The structure of the present invention for solving the above-mentioned problems is achieved by inserting a cylindrical guide pipe, a cylindrical insulating material inserted in the guide pipe, and a central hole of the insulating material. By detecting the capacitance between the detection end, which is formed by the electrode and the electrode at the detection end, and which is attached by projecting downward from the upper part of the storage container in which the medium is stored. In a level measuring device comprising a measuring device for detecting the level of the medium, the electrode at the detection end has a lower part formed on a large-diameter electrode body and an upper part formed on a small-diameter rod-shaped part, The lower part of the inner peripheral surface of the insulating material is attached to the electrode body while the lower part of the inner peripheral surface of the insulating material covers and locks and supports the insulating material from the lower side in a state of covering the lower end surface and the lower part of the outer peripheral surface of the material. When they come into contact with each other, the upper part of the inner peripheral surface is The guide pipe is disposed so as to face the rod-shaped portion, and the guide pipe has an upper locking / supporting portion that locks / supports the insulating material from above in a state of covering the upper end surface and the inner peripheral surface upper portion of the insulating material. It is characterized by having.

Further, the present invention comprises a tubular guide pipe, a tubular insulating material inserted and arranged in the guide pipe, and an electrode inserted through a central hole of the insulating material to store a medium. It consists of a detection end that is attached so as to project downward from the upper part of the layered storage container, and a measuring device that detects the level of the medium by detecting the capacitance between the electrode of the detection end and the storage container. In the level measuring device, the electrode at the detection end has a lower portion formed on a large-diameter electrode body and an upper portion formed on a small-diameter rod-shaped portion, and further, the electrode body of the electrode body is in contact with the lower end surface of the insulating material. The outer peripheral surface has a flange portion that projects in the outer peripheral direction, and an outer sleeve that extends upward from the tip of the flange portion and contacts the lower outer peripheral surface of the insulating material. Contact the electrode body The upper part of the inner peripheral surface of the guide pipe is arranged so as to face the rod-shaped portion with a gap therebetween, and the guide pipe is an inward flange projecting inward from the inner peripheral surface in contact with the upper end surface of the insulating material. And an inner sleeve that extends downward from the tip of the inward flange portion and contacts the upper part of the inner peripheral surface of the insulating material, and further projects to the inner peripheral side at the upper part of the inner peripheral surface and further insulates. It is characterized by having a fixing flange portion for fixing and supporting the rod-shaped portion through a material.

Further, the present invention is characterized in that the tubular insulating material is formed of ceramic, or is formed of a tubular metal and a tubular ceramic arranged so as to surround the tubular metal. And

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. It should be noted that parts having the same functions as those of the conventional technique are designated by the same reference numerals, and overlapping description will be omitted.

FIG. 1 shows the overall structure of a level measuring device according to an embodiment of the present invention, and FIG. 2 shows its detecting end 20. As shown in both figures, the detection end 20 is composed of a guide pipe 21, a ceramic 22 and an electrode 23 as main members.

The guide pipe 21 is made of a heat resistant metal such as Inconel. The guide pipe 21 includes a guide pipe body 21a, a flange portion 21b projecting to the outer peripheral side at an upper end portion of the guide pipe body 21a,
A fixed flange portion 21c protruding toward the inner peripheral side at the upper part of the inner peripheral surface of the guide pipe main body 21a, and the guide pipe main body 21.
It is formed by an inward flange portion 21d that projects to the inner peripheral side at the lower portion of the inner peripheral surface of a, and an inner sleeve 21e that extends downward from the tip of the inward flange portion 21d.

The upper portion of the electrode 23 made of heat-resistant metal is the rod-shaped portion 2.
3a, the lower part is the electrode body 23b. Further, it has a flange portion 23c protruding from the outer peripheral surface of the electrode body 23b to the outer peripheral side, and an outer sleeve 23d extending upward from the tip of the flange portion 23c.

The ceramic 22 is a cylindrical insulating material, and is made of alumina or the like having high temperature and high strength. The lower part of the ceramic 22 is fitted to the electrode 23 with its inner peripheral surface in contact with the outer peripheral surface of the electrode body 23b, its lower end surface in contact with the flange portion 23c, and its outer peripheral surface in contact with the outer sleeve 23d. It is installed. Just the electrode body 23
By b, the flange portion 23c, and the outer sleeve 23d, a locking / supporting member for locking / supporting the lower portion of the ceramic 22 is formed. In addition, the upper part of the ceramic 22 has a rod-shaped portion 23a of the electrode 23 through the gap.
Face to face.

On the other hand, in the upper portion of the ceramic 22, the outer peripheral surface is in contact with the inner peripheral surface of the guide pipe body 21a, the upper end surface is in contact with the inward flange 21d, and the inner peripheral surface is the inner sleeve 21.
The guide pipe 21 is fitted and attached in a state of being in contact with e. Just the guide pipe body 21a,
The inward flange portion 21d and the inner sleeve 21e form a locking / supporting portion that locks / supports while covering the upper portion of the ceramic 22. Moreover, the inner sleeve 21e, which has the same electric potential as the guide pipe body 21a through the inward flange 21d, is made of the ceramic 22
It is located on the inner circumference side of. Therefore, from an electrical point of view, the guide pipe 21 (the inner sleeve 21
e) and the rod-shaped portion 23a of the electrode 23, the ceramic 2
It is configured such that the surface of the guide pipe 21 (inner sleeve 21e) and the surface of the rod-shaped portion 23a face each other with air in between without the interposition of the two. In this way, the surface of the rod-shaped portion 23a and the guide pipe 21 (inner sleeve 21e) can be formed without interposing the ceramic 22 as the insulating material therebetween.
One of the points of the present invention is to make the surfaces of (a) and (b) face each other through a gap (air).

An axial gap is provided between the guide pipe body 21a and the outer sleeve 23d and between the inner sleeve 21e and the electrode body 23b to insulate the guide pipe 21 and the electrode 23 from each other. The state is secured. After all, the axial gap and the ceramic 22 ensure the insulation between the guide pipe 21 and the electrode 23.

On the other hand, the fixed flange portion 21c fixes and supports the upper portion of the rod-shaped portion 23a at its central portion via a ring-shaped insulating material 24 formed of alumina, Teflon, or the like. Further, the fastener 26 is fastened via a ring-shaped insulating material 25 made of alumina or Teflon. Alumina and Teflon are members whose dielectric constant changes little even if the temperature changes to some extent.

Incidentally, the storage container 1, the medium 2 shown in FIG.
The capacitance meter 10, the signal line 11, and the level converter 12 have the same functions as the conventional ones.

In the present embodiment, the guide pipe 21 and the rod-shaped portion 23a may reach a high temperature (about 1000 ° C.) because they are close to the medium 2, but the second portion between the guide pipe 21 and the rod-shaped portion 23a. The capacitance of the sine hardly changes even if the temperature changes. This is because there is no ceramic 22 between the guide pipe 21 (inner sleeve 22e) and the rod-shaped portion 23a, the dielectric constant of which greatly changes due to temperature change, and air whose dielectric constant change due to temperature change is extremely small. It is because it is done.

Further, the fixing flange 26c and the rod-shaped portion 2 are fixed by the fixing tool 26 via the ring-shaped insulating materials 24 and 25.
3a is fixed, but since this part is located away from the medium 2, even if the temperature inside the reservoir 1 changes, the temperature change at the fixing part 26 is small. Therefore, even if the temperature in the storage container 1 changes, the change in the dielectric constant of the ring-shaped insulating materials 24, 25 is extremely small, and this portion (between the rod-shaped portion 23a and the fixed flange portion 21c) caused by the temperature change is small. The change in capacitance in () is extremely small and almost negligible.

As described above, in the present embodiment, even if the temperature inside the reservoir 1 becomes high, the second capacitance having a large capacitance between the guide pipe 21 and the rod-shaped portion 23a is
Since there is almost no change, even if there is a temperature change in the reservoir 1, the capacitance between the electrode 23 and the reservoir 1 can be detected without temperature fluctuations, and the level of the medium 2 can be accurately detected. can do.

Next, a modified example of the detection end 20 will be described with reference to FIG. In this example, the ceramic 22 is replaced by ceramic cylinders 22a, 22b and ceramic ring plates 22c, 22.
A cylindrical metal 27 made of Inconel or the like is inserted between the ceramic cylinders 22a and 22b. In this way, the ceramics 22a, 22
Since the strongest compressive force acts on b, 22c, and 22d, the strength is improved.

[0031]

As described above in detail with the embodiments, according to the present invention, the cylindrical insulating material for insulating between the guide pipe and the electrode is electrically viewed from the rod-shaped portion of the electrode. Since the structure is such that it does not exist between the guide pipe and the guide pipe, it is possible to prevent the capacitance of the detection end from changing due to temperature, and even if the temperature inside the reservoir changes Fluctuations can be detected.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a level measuring device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a detection end used in the embodiment.

FIG. 3 is a configuration diagram showing another example of a detection end.

FIG. 4 is a configuration diagram showing a conventional level detection device.

[Explanation of symbols]

 1 Reservoir Container 2 Medium 3 Detection End 4 Guide Pipe 4a Guide Pipe Body 4b Flange Part 4c Inward Flange 5 Ceramic 6 Electrode 6a Rod Part 6b Electrode Body 7,8 Ring Insulation Material 9 Fixture 10 Capacitance Meter 11 Signal Line 12 level converter 20 detection end 22 ceramic 22a, 22b ceramic cylinder 22c, 22d ceramic ring plate 23 electrode 23a rod-shaped portion 23b electrode body 24, 25 ring-shaped insulating material 26 fixture

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Taketoshi Yamaura 5-717-1, Fukahori-cho, Nagasaki-shi, Nagasaki Sanryo Heavy Industries Ltd. Nagasaki Research Institute

Claims (4)

[Claims] 1. A storage medium comprising a tubular guide pipe, a tubular insulating material inserted and arranged in the guide pipe, and an electrode inserted through a center hole of the insulating material. A level measuring device comprising a detection end that is attached so as to project downward from the upper part of the layer container, and a measuring device that detects the level of the medium by detecting the capacitance between the electrode of the detection end and the reservoir container. In the electrode of the detection end, the lower part is formed in a large diameter electrode body and the upper part is formed in a small diameter rod-shaped part, and further, the insulating material is covered in a state of covering the lower end surface and the outer peripheral surface lower part of the insulating material. Has a lower side locking / supporting portion for locking / supporting from below, the insulating material has a lower inner peripheral surface in contact with the electrode body, and an upper inner peripheral surface thereof has the rod shape through a gap. The guide is arranged so as to face the section. Type, the level measuring device, characterized in that it has an upper locking-support portion for engaging, supporting the insulating material so as to cover the upper surface and the inner peripheral surface upper portion of the insulating material from the upper side. 2. A storage medium formed by a cylindrical guide pipe, a cylindrical insulating material inserted and arranged in the guide pipe, and an electrode inserted through a central hole of the insulating material. A level measuring device comprising a detection end that is attached so as to project downward from the upper part of the layer container, and a measuring device that detects the level of the medium by detecting the capacitance between the electrode of the detection end and the reservoir container. In the electrode of the detection end, the lower portion is formed in a large diameter electrode body and the upper portion is formed in a small diameter rod-shaped portion, and further, from the outer peripheral surface of the electrode body in contact with the lower end surface of the insulating material. A flange portion that projects in the outer peripheral direction and an outer sleeve that extends upward from the tip of the flange portion and contacts the lower outer peripheral surface of the insulating material, and the lower portion of the inner peripheral surface of the insulating material is attached to the electrode body. Contact with that The upper portion of the inner peripheral surface is arranged in a state of facing the rod-shaped portion through a gap, the guide pipe, and an inward flange portion that protrudes inward from the inner peripheral surface in a state of contacting the upper end surface of the insulating material, , An inner sleeve that extends downward from the tip of the inward flange portion and contacts the upper portion of the inner peripheral surface of the insulating material, and further protrudes toward the inner peripheral side at the upper portion of the inner peripheral surface, and other insulating material A level measuring device comprising a fixing flange portion for fixing and supporting the rod-shaped portion through the fixing flange portion. 3. The level measuring device according to claim 1, wherein the cylindrical insulating material is made of ceramics. 4. The cylindrical insulating material is formed of a cylindrical metal and a cylindrical ceramic arranged so as to surround the circumference of the cylindrical metal. Item 2. Level measurement device.