JP3196689B2 - Sediment detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deposit detector for detecting an amount of deposit accumulated with time in a pipe of a manufacturing facility or the like.

[0002]

2. Description of the Related Art Conventionally, this kind of deposit detector is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-215958.
In order to inspect the inside of the pipe, it has been performed by constructing a system for radiating ultrasonic waves from the outside and observing an echo signal from the inside. This device is shown in FIG.

A conventional deposit detector shown in FIG. 7 scans a transducer 18 in a circumferential direction or an axial direction of a pipe 11, and transmits an echo wave from the inside to an amplifying unit 12, A controlled by a controller unit 17. The configuration is such that image data is displayed on the television monitor 16 via the / D conversion unit 13, the data memory 14, and the D / A conversion unit 15.

[0004]

However, the prior art shown in FIG. 7 is a method of detecting the amount of deposits in a pipe by emitting an ultrasonic wave and monitoring a reflected wave, that is, an echo signal. Then, the thickness of the exhaust pipe used in a normal semiconductor manufacturing plant (φ50-75mm)
However, there is a problem that it is difficult to accurately detect the sediment of the object.

[0005] The reason is that the ultrasonic waves must always be emitted toward the center of the pipe in order to prevent the ultrasonic waves from being affected by the scattered waves in other parts of the pipe. This is due to being affected by scattered waves to a considerable extent due to unevenness rather than uniform thickness. In addition, when the pipe diameter is small, accurate centering may not be achieved unless a dedicated transducer corresponding to each pipe diameter is prepared. Furthermore, when the pipe diameter is small,
It is conceivable that the echo signal due to the deposit on the opposite side wall is multiplied by the echo signal due to the deposit on the side wall on the transducer side, and this separation is difficult and measurement accuracy cannot be obtained.

Another problem is that data of a plurality of pipes to be measured cannot be measured continuously and instantaneously.

[0007] The reason is that the system itself is large and the mobility and mobility of the system are impaired, and that the transducer must be operated by a human. This means that it is impossible to cope with a case where pipes are installed under the floor as seen in a recent semiconductor manufacturing plant.

As a method for solving the above two problems,
A method disclosed in JP-A-8-210836 has been proposed. This device is shown in FIG. The device shown in FIG.
Three capacitance measuring electrodes 32, 33, 3 are provided on the outer periphery of the pipe 31.
4 is attached via spacers 36, 37, 38, 39,
The capacitance between the electrodes is drawn out to the outside by the conducting wire 40, and the amount of the deposit is monitored.

However, in the conventional example shown in FIG. 8, there is a problem that usable portions and applicable gas types are limited.

[0010] The reason for this is that, since the electrodes are arranged in parallel with the outer peripheral portion of the pipe, the material of parts for insulating between the electrodes is limited to an insulator such as a nonmetal. is there. Thus, it is understood that the method is not suitable for monitoring a corrosive gas or the like.

Another problem is that accurate monitoring cannot be performed depending on the dielectric constant of the deposit.

The reason is that the parasitic capacitance of the insulator is added at the time of monitoring because the inter-electrode insulating portion has a large area. This means that it is not suitable for deposits having a low dielectric constant.

An object of the present invention is to provide a deposit detector for detecting the amount of deposit accumulated over time by a change in capacitance between electrodes.

[0014]

In order to achieve the above object, a deposit detector according to the present invention has a plate-like shape in a pipe for detecting the amount of deposit accumulated in a pipe over time based on a change in interelectrode capacitance.
An electrode having an inner plate-shaped electrode,
The shape is a waveform.

[0015]

[0016]

[0017]

Further, the deposit detector according to the present invention is provided in a pipe.
A deposit detector having a plate-shaped electrode on the
The poles consist of pairs of electrodes and are installed along the inner wall of the pipe
The amount of sediment accumulated between the pair of electrodes changes
And the plate-like electrode has a surface shape.
The shape is a waveform.

[0019]

The electrodes are made of a ceramic material.
It is electrically insulated by the insulating insulator .

[0021]

Next, the principle of the present invention will be described. In the case of a plate-like electrode installed in a pipe, the capacitance between the electrodes is considered as a capacitor having the dielectric constant of air when there is no deposit (FIG. 5). For example, the electrode area is S and the distance between the electrodes is d.
Then, since the dielectric constant of air is almost 1, if this capacitance is Co, C = εS / d = S / d. That is, the capacitance Co measured at this time becomes the initial value. On the other hand, as shown in FIG. 6, when a deposit having a dielectric constant of ε ″ is deposited between the electrodes, for example, a capacitor having an apparent dielectric constant of air and a capacitor having a dielectric constant of ε ″ are formed. A circuit connected in series has been formed, and the total permittivity of this circuit changes with respect to the initial value.

Specifically, for example, when a deposit having a dielectric constant ε ″ is deposited by d ″, the combined capacity of this system is represented by C _total ,
Assuming that the capacity at the place where no deposit exists is C ₁ and the capacity at the place where the deposit having dielectric constant ε ″ is C ₂ , C _total = (C ₁ × C ₂ )
/ (C ₁ + C ₂ ). Here, C ₁ = S / (d−
d ″), C ₂ = ε ″ S / d ″.

This combined capacitance C _total can be monitored from the outside, and the thickness d ″ of the deposit can be calculated from the combined capacitance C _total obtained.

At this time, the amount of change in the dielectric constant can be controlled by setting the electrode area and the distance between the electrodes according to the magnitude of the dielectric constant of the deposit, the ease of deposition, and the like. It becomes possible to monitor.

As described above, by using the deposit detecting component according to the present invention, the deposit amount can be continuously and easily measured from outside the pipe.

[0025]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a perspective view showing Embodiment 1 of the present invention, and FIG. 2 is a sectional view.

In FIG. 1, 1 is a pipe through which gas flows, 2 is an upper electrode for measuring the capacity in the pipe 1, 3 is a lower electrode, and 4 is an upper electrode and an upper electrode which are insulated from each other. An insulating insulator for separation, an electrode lead wire 5, and an electrode insulating spacer 7 for insulating the lower electrode 3 from the pipe 1. In FIG. 2, reference numeral 6 denotes a sediment in the pipe attached to the inside of the pipe 1, and reference numeral 8 denotes a bolt for pulling out.

As shown in FIG. 1, the deposit detector according to the first embodiment of the present invention has an upper electrode 2 and a lower electrode 3 in a pipe 1 along a pipe shape. Is an insulator between electrodes 4, and the lower electrode 3 and the pipe 1 are electrically insulated by an electrode insulating spacer 7, respectively.

Further, from each of the electrodes 2 and 3, a lead bolt 8 passes through the insulating insulator 4, from which a lead wire 5 is drawn, and beyond which a capacitance measuring meter (typically shown) is used. Is connected.

The upper electrode 2 and the lower electrode 3 are, for example, S
A commonly used electrode material such as US may be used, but a metal having high corrosion resistance to flowing gas is selected as the electrode material. The size of the electrode is not fixed, and may be an appropriate size depending on the size of the pipe and the type of gas flowing. Also,
An insulating insulator 4 is used to maintain the electrical insulation of the upper and lower electrodes 2 and 3 and to maintain the same distance. Insulation insulator 4
, A general ceramic material may be used.

The ceramic material used as the material of the insulating insulator 4 has a large relative dielectric constant of generally 8 to 10, but if its size is reduced, it does not impede the gas flow in the pipe and the effective area as a capacitor is reduced. Smaller,
The effect can be ignored. Even if it cannot be neglected, the capacitance of the insulating insulator 4 can be calculated in advance from the relative permittivity and each dimension, so that the measured value obtained can be corrected. Also, electrode insulating spacer 7
Since it is used for the same purpose as the insulating insulator 4, it is formed of the same material.

In the present invention, it is possible to freely optimize the electrode area and the inter-electrode distance based on the ease of deposition of the deposit and the relative permittivity. It is possible to increase the amount of change in capacitance from a certain case. FIG. 3 shows a specific example. In FIG. 3, the electrode area is 1 cm ² , the distance between the electrodes is 0.1 cm, and the initial state when the deposit is silicon oxide (relative permittivity ≒ 4), that is, when the capacitance when there is no deposit is Co. 2 shows the amount of change from the combined capacity C _total of FIG. FIG. 3 shows that even when the thickness of the deposit 6 changes by 0.01 cm, the thickness of the deposit 6 can be reliably measured because the change amount is large.

As described above in detail, according to the first embodiment of the present invention, a plate-like electrode comprising a pair of upper and lower electrodes is provided in a pipe, and the combined capacitance value between the electrodes is continuously or By measuring regularly, the thickness of the sediment in the pipe can be monitored regardless of the size and material of the pipe. Can be prevented.

Although not shown in the drawing, if the joints such as the VCR joint and the Swagelok joint are connected in advance to both sides of the pipe for installing the present invention, the maintenance of the deposit detector of the present invention can be performed. Becomes easier.

(Embodiment 2) Next, Embodiment 2 of the present invention will be described in detail with reference to FIG. Embodiment 2 shown in FIG. 4 is characterized in that the electrode shape is a wave shape. By making the shape of the electrodes 2 and 3 corrugated, a large area can be obtained while keeping the size of the electrodes small. Therefore, compared to the case of the first embodiment,
It becomes possible to install the deposit detector of the present invention even in a smaller pipe diameter. Naturally, even in this case, although not shown in the drawing, if the joints such as the VCR joint and the Swagelok joint are connected in advance on both sides of the pipe for installing the present invention, the sediment detector of the present invention can be used. Maintenance becomes easy.

[0036]

As described above, according to the present invention, it is possible to measure the thickness of a deposit having any dielectric constant in piping of any material and size.

The reason is that the size of the electrode and the area of the electrode can be freely adjusted according to the size of the pipe to be measured and the dielectric constant of the deposit.

Further, by measuring the volume of the sediment, it is possible to continuously and accurately detect the amount of the sediment in the pipe by centralized control, thereby preventing an accident due to the clogging of the sediment and an abnormal stop of the production equipment. Can be prevented.

The reason is that if the dielectric constant of the deposit is known, the thickness of the deposit can be easily calculated from the value, the measured capacitance value, the electrode area and the distance.

[Brief description of the drawings]

FIG. 1 is a partially sectional perspective view showing Embodiment 1 of the present invention.

FIG. 2 is a structural sectional view showing Example 1 of the present invention.

FIG. 3 is a diagram illustrating a relationship between a deposit thickness and a capacitance change amount in the first embodiment of the present invention.

FIG. 4 is a partially sectional perspective view showing Embodiment 2 of the present invention.

FIG. 5 is a diagram illustrating the principle of the present invention.

FIG. 6 is a diagram illustrating the principle of the present invention.

FIG. 7 is a diagram showing a conventional example.

FIG. 8 is a diagram showing another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piping 2 Upper electrode 3 Lower electrode 4 Insulation insulator between electrodes 5 Lead wire 6 In-tube sediment 7 Electrode insulating spacer 8 Pull-out bolt

Claims (3)

(57) [Claims] 1. A deposit having an in- tube plate electrode for detecting the amount of deposit accumulated in a pipe over time by a change in interelectrode capacitance .
A detector, the tube plate electrodes, sediment detector, characterized in that is obtained by the surface shape a waveform. 2. A deposit detector having a plate-like electrode in a pipe, wherein the plate-like electrode comprises a pair of electrodes, is installed along an inner wall of the pipe, and accumulates between the pair of electrodes. A deposit detector for detecting an amount of a deposit by a change in interelectrode capacitance, and wherein the plate-like electrode has a waveform of a surface shape. 3. The deposit detector according to claim 1, wherein the electrode is electrically insulated by an insulating insulator made of a ceramic material.