JPH06129803A - Detecting device for scale thickness - Google Patents

Abstract

PURPOSE:To calculate the scale thickness from the relation between the scale thickness and capacity by providing an arithmetically operating unit for calculating the scale amount based on an electrostatic electricity capacity change between electrodes arranged opposite to each other in a steam pipe, which is measured by an electrostatic capacity measuring device. CONSTITUTION:Scale is grown on the inner face of a main steam pipe 1 and simultaneously scale is formed on the surface of both electrodes 2. The dielectric constant between the electrodes changes accordingly and electrostatic capacity changes. The capacity is measured by a capacity measuring device 4 and A/D converted by an A/D converter 5, and then sent to an arithmetic operation unit 6. In the unit 6, data obtained by a test on the relation between the scale thickness and capacity is preliminarily stored. Consequently, according to the input the unit 6 calculates the scale thickness and it is sent to a display 7 and displayed. It is thus possible to measure at all times including the time of operation without cutting the pipe 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a main steam of a thermal power generation facility,
The present invention relates to a scale thickness detecting device for a reheat steam pipe.

[0002]

2. Description of the Related Art Conventionally, the only method for grasping the state of scale adhesion on a main steam pipe or the like is to melt the pipe and visually inspect it.

[0003]

High-purity water is used as a working fluid in thermal power generation equipment. In addition to a trace amount of residual components contained in the working fluid, various metal ions, etc., which are eluted from the pipe wall at high temperature are used. Including. These components may adhere to and grow on the wall of the pipe over a long period of time, eventually peeling off and scattering downstream. There is a risk that these scattered materials may collide with the turbine blades on the downstream side and cause rapid erosion.

[0004]

The present invention takes the following means in order to solve the above problems.

That is, as a scale thickness detecting device,
Electrodes provided to face each other in the steam pipe, a capacity measuring means connected to the electrodes, and an arithmetic means connected to the capacity measuring means to calculate a scale amount from a change in capacity are provided.

[0006]

[Function] When the scale adheres to the inside of the vapor pipe, the scale also adheres to the electrodes. Then, the capacitance between the electrodes changes. This capacity is measured by the capacity measuring means and sent to the calculating means. The calculation means calculates the scale thickness from the relationship between the scale thickness and the capacity that are input in advance.

In this way, the scale thickness in the steam pipe can be easily measured.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is an overall structural system diagram, FIG. 2 is a sectional view of an electrode portion, FIG. 3 is a detailed sectional view of an electrode portion, FIG. 4 is a view taken along line AA of FIG. 3, and FIG. 5 is line BB of FIG. 6 is a perspective view of the insulating sleeve portion, FIG. 7 is a C-C view of FIG. 2, and FIG. 8 is a D-D of FIG. 7.
It is a perspective view.

In FIG. 1, an electrode 2 is mounted in the main steam pipe 1. The electrode 2 is connected to the capacitance measuring device 4. The output of the capacitance measuring device 4 is sent to the calculator 6 via the A / D converter 5. The output of the calculator 6 is sent to the display 7.

As shown in FIGS. 3 to 5, the electrodes 2 are attached to a rectangular parallelepiped-shaped ceramic electrode holder 3 having protrusions b on the lower side. A groove a is provided in the center of the upper surface of the electrode holder 3. Rectangular electrodes 2 are embedded facing each other along the groove a. The lead wire 8 of the electrode 2 passes through the electrode holder 3 and is drawn out to the side of the protrusion b on the lower surface. The electrode holder 3
Has a curved portion c in the vicinity of. Further, it has a conical (tapered) protrusion d. The lead wire 8 is plated with platinum.

The electrode 2 is attached as shown in FIGS. The main steam pipe 1 is provided with a tapered hole e along the cross section. The hole e has a ceramic sleeve 9 with a taper.
Inserted. Then, the lead wire 8 is passed through the sleeve 9. At this time, the protrusion d is housed in the tapered portion of the sleeve 9. Further, the surface of the projection b of the electrode holding base 3 contacts the inner surface of the main steam pipe 1, and the groove a is arranged so as to be parallel to the axis of the main steam pipe 1.

As shown in FIGS. 7 and 8, the fixed cover 10 is a two-piece piece, and the shape of the outer periphery h when paired is an elliptical shape. The major axis is arranged parallel to the generatrix of the main steam pipe 1. Further, a depression f is provided on the pressing surface side of the central portion and is divided into two by a line orthogonal to the long axis. The two divided surfaces g are arranged so that the distance between them is equal to the width of the groove a. The inner surface side has a shape that contacts the inner surface of the main steam pipe 1. Further, the outer surface is also a curved surface, and the outer periphery h makes smooth contact with the inner surface of the main steam pipe 1 without any step, and is welded all around. At this time, fixed cover 1
0 and the contact surface of the electrode holder 3 are provided with a predetermined clearance.

In the above, the scale grows on the inner surface of the main steam pipe 1, and at the same time, the scale also adheres to the surface of the electrode 2 made of the same material. Then, the dielectric constant between the two electrodes 2 changes, so that the capacitance changes. This capacity is measured by the capacity measuring device 4, A / D converted by the A / D converter 5, and sent to the arithmetic unit 6.

On the other hand, the arithmetic unit 6 is preliminarily input and stored with data obtained by a test on the relationship between the scale thickness and the electrostatic capacitance. Therefore, the calculator 6 calculates the scale thickness from the input and sends it to the display 7 for display.

In the above, the curved portion c of the lead wire 8 and the clearance between the fixed cover 10 and the electrode holder 3 prevent the generation of excessive stress due to thermal expansion and contraction. The platinum plating of the lead wire 8 is for reducing scale adhesion. The taper of the sleeve 9 takes into consideration the pressure difference between the inside and the outside (250 kgf / cm ² ). The surface shape of the fixed cover 10 is such that no fluid resistance occurs.

As described above, according to this embodiment, the main steam pipe 1 can be constantly measured without disconnecting it, even during operation. Installation work is simple and can be added to the existing equipment. Further, since the structure is simple, there are no moving parts, and a material resistant to heat is used, highly reliable measurement values can be obtained.

[0018]

As described above, according to the present invention, the scale thickness can be constantly and accurately measured.

[Brief description of drawings]

FIG. 1 is an overall configuration system diagram of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an electrode part of the example.

FIG. 3 is a cross-sectional view of an electrode part of the example.

FIG. 4 is a sectional view taken along line AA of FIG. 3 of the same embodiment.

FIG. 5 is a BB view of FIG. 3 of the embodiment.

FIG. 6 is a perspective view of a sleeve portion of the embodiment.

FIG. 7 is a CC view of FIG. 2 of the same embodiment.

8 is a cross-sectional view taken along the line DD of FIG. 7 of the same embodiment.

[Explanation of symbols]

 1 main steam pipe 2 electrode 4 capacity measuring device 5 A / D converter 6 calculator 7 indicator

Claims (1)

[Claims] 1. An electrode provided in a steam pipe so as to face each other, a capacity measuring means connected to the electrode, and an arithmetic means connected to the same capacity measuring means to calculate a scale amount from a change in capacity. A scale thickness detecting device characterized by: