JP2013087928A - Monitoring method and monitoring apparatus for piston of dry type gas holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor not only piston inclination but also eccentricity.SOLUTION: A monitoring method for a piston of a dry type gas holder is provided with: a cylindrical holder body which extends in a vertical direction in order to store gas inside; a drop-lid-like piston which is disposed to be movable vertically within the holder body; and a seal mechanism for airtightly sealing a gap between a peripheral edge part of the piston and an inner circumferential surface of the holder body. In each of at least three positions on the piston in the equal distance from a center of the piston, there is provided an eccentricity measuring table with a predetermined size while being protruded by a predetermined height from an upper surface of the piston. In an upper end part of the holder body, there is provided a range finder for measuring a height direction distance to the eccentricity measuring table with no contact. When change occurs in the height direction distances measured by the range finder from the range finder to the eccentricity measuring tables in at least three positions: when the change is sharp, it is determined that eccentricity occurs in the piston; and when the change is smooth, it is determined that inclination occurs in the piston.

Description

  The present invention relates to a dry gas holder, and more particularly, to a method and apparatus for monitoring the eccentricity and tilt of a piston so as to keep the piston installed in the dry gas holder in a vertically movable manner.

  Combustible gas generated in blast furnaces, coke ovens, steel making, etc. at steelworks is used as fuel in heating furnaces, etc., but the amount of combustible gas generated varies. Therefore, a gas holder with a variable storage amount is used for storing and supplying surplus flammable gas.

  Gas holders are usually classified into wet and dry types. In the case of wet gas holders, a cylindrical holder main body that extends in the vertical direction, and the water in the holder main body that can be moved up and down in the holder main body, etc. And a cup-shaped piston with a vertically long side wall immersed in the sealing liquid.The pressure of the gas stored in the piston raises and lowers the piston in the holder body to increase or decrease the storage amount. Leakage of the stored gas is prevented by moving up and down while the vertically long side wall is immersed in the sealing liquid. For this reason, the piston is structurally unlikely to be inclined because the vertically long side wall portion is supported by the holder body.

  On the other hand, in the case of a dry-type gas holder, a cylindrical holder main body that extends in the vertical direction in order to accommodate gas therein, a drop-lid piston that is disposed so as to be movable up and down in the holder main body, It has a sealing mechanism that hermetically seals the gap between the periphery and the inner peripheral surface of the holder body, and the stored amount is increased or decreased by raising and lowering the piston in the holder body due to the pressure of the gas stored in the holder body. The gas stored therein is prevented from leaking out by hermetically sealing between the peripheral edge of the piston and the inner peripheral surface of the holder body with a sealing mechanism.

  There are also wet and dry seal mechanisms for pistons of such dry gas holders, and in the wet seal mechanism, a seal liquid tank that is provided at the peripheral edge of the piston and accumulates seal liquid between the inner peripheral surface of the holder body, The bottom of the seal liquid tank is arranged so as to be movable in a liquid-tight manner, and has a sliding plate or a seal rubber that is pressed against the inner peripheral surface of the holder body and slidably contacts the inner surface of the holder body from the vicinity of the upper end thereof. The seal liquid that flows down is collected in the seal liquid tank, and a slight gap between the inner peripheral surface of the holder main body and the sliding plate or seal rubber is sealed while hermetically sealing between the peripheral edge of the piston and the inner peripheral surface of the holder main body. It flows down along the inner peripheral surface of the holder body from the gap, is collected, and is supplied again into the holder body. Some use grease instead of the sealing liquid.

  On the other hand, in the dry seal mechanism, an elastic curtain such as rubber extending in the circumferential direction between the peripheral edge of the piston and the inner peripheral surface of the holder body has a sufficient length in the vertical direction. It is stretched in a U-shape, and the U-shaped folded part of the curtain moves as the piston moves up and down, so that the curtain seals between the peripheral edge of the piston and the inner peripheral surface of the main body. doing.

  However, in a dry gas holder, any sealing mechanism requires a certain amount of clearance between the peripheral edge of the piston and the inner peripheral surface of the holder body, and the piston does not have a vertically long side wall. The piston may tilt due to the difference in frictional force between the holder body and the inner peripheral surface between different positions in the circumferential direction of the holder. When the piston is tilted, the piston is raised and lowered. The gap between the peripheral edge of the holder and the inner peripheral surface of the holder body increases, and in the wet seal mechanism, the seal liquid moves from the raised part of the peripheral part to the lowered part and the seal liquid is insufficient at the raised part. However, there is a possibility of gas leakage, and even if grease is used in place of the sealing liquid, there is a possibility that gas leakage may occur due to insufficient grease at the large gap. There are, on the other hand, in the dry seal mechanism, partially damaged elastic body made of curtain forced to deformed excessively, there is a possibility that the gas leakage occurs from the damaged part. In any sealing mechanism, the lower part of the peripheral edge partly strongly presses the inner peripheral surface of the holder main body, so that the inner peripheral surface of the holder main body is partially damaged and gas leakage occurs from the damaged portion. there is a possibility.

  Accordingly, various types of monitoring devices for the inclination of the piston of the dry gas holder have been proposed. For example, in Patent Document 1, three or more laser type distance meters provided on the top of the holder body are used in the circumferential direction of the peripheral portion of the piston. The distance to different parts is measured, and the inclination of the piston is monitored from the measurement results and displayed on the display device. Also, for example, in Patent Document 2, the height of the liquid level of the sealing liquid in the sealing liquid tank at three or more different locations in the circumferential direction of the peripheral edge of the piston is measured, and the inclination of the piston is monitored from the measurement results. Is displayed on the display device.

JP 2006-058205 A JP 2006-275262 A

  However, since all of the conventional devices as described above display the inclination when the piston is inclined, in some cases, the inclination of the piston becomes too large, and the piston is found after the inclination is detected. It may take too much time to return to a flat state, leading to problems.

  Therefore, an object of the present invention is to provide a piston monitoring method and apparatus that advantageously solves the problems of the prior art by monitoring not only the piston inclination but also the eccentricity.

A method for monitoring a piston of a dry gas holder of the present invention that achieves the above-described object is as follows.
A cylindrical holder main body that extends in the vertical direction to contain gas therein, a drop-lid piston that can be moved up and down in the holder main body, a peripheral portion of the piston, and an inner peripheral surface of the holder main body In the method for monitoring a piston of a dry gas holder comprising a sealing mechanism for hermetically sealing a gap between
The piston is provided with an eccentricity measurement table of a predetermined size at a predetermined height located at at least three locations equidistant from the center of the piston,
A distance meter is provided at the upper end of the holder body to measure the distance in the height direction to the eccentricity measurement table in a non-contact manner,
When a change occurs in the distance in the height direction from the distance meter measured by the distance meter to the at least three eccentricity measurement tables, if the change is abrupt, it is determined that the piston is eccentric. When the change is gentle, it is determined that the piston is inclined.

Moreover, the monitoring device for the piston of the dry gas holder of the present invention that achieves the above-mentioned object is as follows.
A cylindrical holder main body that extends in the vertical direction to contain gas therein, a drop-lid piston that can be moved up and down in the holder main body, a peripheral portion of the piston, and an inner peripheral surface of the holder main body In the piston monitoring device of the dry gas holder comprising a sealing mechanism that hermetically seals the gap between
An eccentricity measurement table of a predetermined size at a predetermined height provided to be located at at least three positions equidistant from the center of the piston;
A distance meter that is provided at the upper end of the holder body and measures the distance in the height direction to the eccentricity measurement table in a non-contact manner;
When a change occurs in the distance in the height direction from the distance meter measured by the distance meter to the at least three eccentricity measurement tables, if the change is abrupt, it is determined that the piston is eccentric. If the change is gentle, it is determined that the piston is inclined, and a piston eccentric inclination determining means for outputting the determination result;
It is characterized by comprising.

  According to the piston monitoring method and apparatus of the dry gas holder of the present invention, at least three positions equidistant from the center of the piston from the distance meter measured by the distance meter provided at the upper end of the holder body. When a change occurs in the distance in the height direction to the eccentricity measurement table of a predetermined size at a predetermined height provided for each piston, if the change is abrupt, it is determined that eccentricity has occurred in the piston, If the change is moderate, it is determined that the piston has been tilted. Therefore, not only the piston tilt but also the occurrence of piston eccentricity that may cause the piston tilt can be monitored. The occurrence of this can be prevented in advance, and even if the piston is tilted, it can be dealt with promptly before it causes a problem.

  In the dry gas holder piston monitoring method and apparatus according to the present invention, it is preferable that the eccentricity measurement table includes a donut-shaped one. In this way, due to the presence of a step on the surface of the eccentricity measurement table in the center hole and around the hole, the gentle distance change while the distance meter is measuring the surface of the eccentricity measurement table in the center hole is It is thought that the piston is tilted, and the sudden distance change when the distance meter moves from the measurement of the eccentricity measurement table surface in the center hole to the measurement of the eccentricity measurement table surface around the hole is considered to be the eccentricity of the piston. The inclination and eccentricity of the piston can be easily and reliably determined. Here, the distance meter may measure the piston surface exposed in the central hole of the eccentricity measurement table.

  In the dry gas holder piston monitoring method and apparatus according to the present invention, the eccentricity measurement table includes two tangential directions with respect to the center of the piston and extending in directions perpendicular to each other. preferable. In this way, the eccentric direction of the piston can be measured by identifying which of the two tables in the tangential direction has a sudden change in distance.

  In the method and apparatus for monitoring a piston of a dry gas holder of the present invention, it is preferable that the eccentricity measurement table includes one that extends in a radial direction with respect to the center of the piston. In this way, it is possible to measure the rotation of the piston by identifying whether there is a sudden distance change in the radial table.

  Furthermore, in the method and apparatus for monitoring a piston of a dry gas holder according to the present invention, it is preferable that the eccentricity measurement table includes a surface whose surface is stepped or inclined. In this way, the eccentric amount of the piston can be measured stepwise or continuously on the stepped or inclined surface.

It is a basic diagram which shows one Embodiment of the monitoring apparatus of the piston of the dry gas holder of this invention used for implementation of one Embodiment of the monitoring method of the piston of the dry gas holder of this invention with the dry gas holder of a see-through | perspective state. (A) And (b) is the perspective view and sectional drawing which show one Embodiment of the eccentric amount measurement table which can be used for the monitoring apparatus of the piston of the holder of the said embodiment. (A) And (b) is the perspective view and sectional drawing which show other one Embodiment of the eccentric amount measurement table which can be used for the monitoring apparatus of the piston of the holder of the said embodiment. (A) And (b) is the perspective view and sectional drawing which show another one Embodiment of the eccentric amount measurement table which can be used for the monitoring apparatus of the piston of the holder of the said embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the dry gas holder piston monitoring apparatus according to the present invention, which is used for carrying out the embodiment of the dry gas holder piston monitoring method according to the present invention, together with the dry gas holder in a transparent state. FIGS. 2A and 2B are a perspective view and a cross-sectional view showing an embodiment of an eccentricity measuring table that can be used in the monitoring device for the piston of the holder of the above embodiment. Reference numeral 1 denotes a dry gas holder.

  The dry-type gas holder 1 here has a cylindrical holder body 2 extending in the vertical direction in order to accommodate the gas G therein, and a disk-shaped disk that forms a drop lid that can be moved up and down in the holder body 2. It comprises a piston 3 and a sealing mechanism 4 that hermetically seals the gap between the peripheral edge of the piston 3 and the inner peripheral surface of the holder body 2, and the holder body 2 is pressurized by the pressure of the gas G stored in the holder body 2. The amount of stored gas is increased or decreased by moving the piston 3 up and down, and the gas G to be stored leaks out by sealing the space between the peripheral edge of the piston 3 and the inner peripheral surface of the holder body 2 with a sealing mechanism 4. It is preventing. Here, the sealing mechanism 4 may be any of the dry sealing mechanism and the wet sealing mechanism described above.

  In the dry gas holder 1, in the dry gas holder piston monitoring apparatus of the present embodiment, as shown in FIG. 1, at least three positions of the piston 3 that are equidistant from the center of the piston 3, for example, in the illustrated example, Eccentricity measurement tables 5 having a predetermined size and a predetermined height are installed at three positions at equal intervals in the circumferential direction on the seal mechanism 4 provided at the peripheral edge of the piston 3.

  In the piston monitoring device of the dry gas holder of the present embodiment, for example, a reference plane that passes through at least three points spaced apart from each other in the circumferential direction of the peripheral portion of the piston 3 is formed on the lower surface of the ceiling 2a located at the upper end of the holder body 2. An initial position where the piston 3 is horizontal and the peripheral edge of the piston 3 is spaced equidistant from the inner peripheral surface of the holder body 2 in each horizontal direction, and the direction of rotation around the vertical center axis of the piston 3 is a predetermined direction. In the state where the piston 3 is present, it is positioned directly above the three eccentricity measurement tables 5 on the piston 3, and the height direction distance to the eccentricity measurement table 5 is measured in a non-contact manner. Place the distance meter 6 on the table downward.

  Further, in the monitoring device for the piston of the dry gas holder of the present embodiment, the output signals of the three distance meters 6 are input to a determination device 7 having a normal computer, for example, as piston eccentric inclination determination means, and the determination is made. The output signal of the device 7 is input to a display device 8 having a normal display panel, for example, and information based on the output signal of the determination device 7 is displayed on the display panel of the display device 8.

  Here, as shown in FIG. 2, for example, each of the three eccentricity measurement tables 5 has a donut-shaped upper surface 5a, a substantially cylindrical side wall portion 5b that supports the upper surface at the upper end portion, and the side wall portion. The upper surface 5a of the eccentricity measuring table 5 is, for example, parallel to the reference plane of the piston 3 and its reference plane. Is projected at a height of 300 to 600 mm, has an outer diameter of 400 to 800 mm, and has a central hole with an inner diameter of 50 to 200 mm. The support plate 5c has, for example, a thickness of 10 mm and an outer diameter of 800 mm (in the case of a dry seal mechanism (a film made of an elastic body such as rubber), since the allowable amount of eccentricity is relatively large, the inner diameter is growing).

  Each distance meter 6 emits a laser beam directly below, and in the state where the piston 3 is in the initial position, the laser beam passes through the center of the central hole of the upper surface 5a of the eccentric amount measurement table 5 directly below, Reflected by the surface of the lower support plate 5c and received by the distance meter 6, each distance meter 6 has a phase difference between the received laser light and the reference light inside the distance meter, or a time difference between light emission and light reception. Based on this, the distance in the height direction from the distance meter 6 to the support plate 5 c is measured, and a signal indicating the distance is input to the determination device 7.

  Thus, when the piston 3 rotates eccentrically or around the vertical axis while being horizontal from the initial position, if the eccentricity or rotation amount exceeds 50 mm, the distance is measured by any one of the three eccentricity measurement tables 5. The laser beam from the meter 6 is reflected by the upper surface 5a of the eccentricity measurement table 5 directly below and received by the distance meter 6, and the distance in the height direction output from the distance meter 6 is that from the distance meter 6 to the upper surface 5a. Therefore, it changes rapidly.

  In addition, when the piston 3 is gradually inclined from the initial position, the eccentricity measurement table 5 in which the laser beam from the distance meter 6 is directly below the eccentricity measurement table 5 of any one of the three. Reflected by the surface of the support plate 5 c and received by the distance meter 6, the height direction distance changes gently while the height direction distance from the distance meter 6 to the support plate 5 c is measured.

  Therefore, in the dry gas holder piston monitoring device of this embodiment, the determination device 7 inputs signals from the three distance meters 6 as described above in accordance with the dry gas holder piston monitoring method of this embodiment. Then, the change state of these signals is examined at a predetermined interval, for example, every 10 minutes, and the distance in the height direction from the distance meter 6 measured by any one of the three distance meters 6 to the eccentricity measurement table 5 immediately below the distance meter 6 is measured. In the case where there is a change from the previous measurement result, if the change is abrupt, it is considered that the measurement position has moved from the surface of the support plate 5c to the upper surface 5a as described above. If it is determined that the change is moderate, it is considered that the measurement position is maintained on the surface of the support plate 5c as described above, so that it is determined that the piston 3 is inclined.

  Then, the determination device 7 outputs a signal indicating the determination result and the height direction distance measured by each distance meter 6 to the display device 8, and the display device 8 is based on the output signal of the determination device 7. The display panel displays information on the determination result indicating whether the displacement is eccentric, rotation, or tilt, and the distance in the height direction measured by each distance meter 6.

  Therefore, according to the monitoring method and apparatus for the piston of the dry gas holder of this embodiment, the distance meter 6 measured at the upper end of the holder body 2 is equidistant from the center of the piston 3. If there is a change in the distance in the height direction to the eccentric amount measurement table 5 of a predetermined size at a predetermined height provided in the piston 3 at at least three positions, if the change is abrupt, the piston 3 is determined to be eccentric, and if the change is gentle, it is determined that the piston 3 is inclined, so that not only the inclination of the piston 3 but also the piston 3 that may cause the inclination of the piston 3 The occurrence of eccentricity can also be monitored, and the piston 3 is biased using a known means such as a cylinder (not shown) that presses the sliding plate of the seal mechanism 4 or the seal rubber against the inner peripheral surface of the holder body 2. By eliminating the generation of inclination of piston 3 can be prevented, also the inclination of the even piston 3 it can be quickly addressed before causing a problem even in the event.

  Moreover, according to the method and apparatus for monitoring the piston of the dry gas holder of this embodiment, since the eccentricity measurement table 5 has a donut shape, the surface of the eccentricity measurement table between the center hole and the periphery of the hole is provided. Due to the presence of steps 5c and 5a, the gentle distance change while the distance meter 6 measures the surface 5c of the eccentricity measurement table in the central hole is considered to be the inclination of the piston 3, and the distance meter 6 is in the central hole. Since a sudden change in distance when shifting from the measurement of the eccentricity measurement table surface 5c to the measurement of the eccentricity measurement table surface 5a around the hole is considered to be eccentricity or rotation of the piston 3, the inclination and eccentricity of the piston 3 or The rotation of the piston 3 occurs when the rotation of the piston 3 is restricted by the guide structure that can easily and reliably discriminate the rotation. In Ino, the inclination of the piston 3 and the eccentric and can be distinguished easily and reliably.

  FIGS. 3A and 3B are a perspective view and a cross-sectional view showing another embodiment of an eccentricity measurement table that can be used in the method and apparatus for monitoring the piston of the holder of the above embodiment. The eccentricity measurement table 5 includes a concentric circular stepped upper surface 5a, a substantially cylindrical side wall portion 5b having the upper surface, and a disk-shaped support plate 5c that supports the lower end portion of the side wall portion. It is set as the thing which has. If the eccentricity measurement table 5 of this embodiment is used instead of or in addition to the eccentricity measurement table 5 of the previous embodiment, the eccentricity of the piston 3 can be measured stepwise on its stepped upper surface 5a. Since this is possible, the state of the piston 3 can be known in more detail. The upper surface 5a of the eccentricity measurement table 5 may be an inverted truncated cone having an inclined surface instead of a circular step shape. In this case, the eccentricity of the piston 3 can be continuously measured. Since this is possible, the state of the piston 3 can be known in more detail.

  FIGS. 4A and 4B are a perspective view and a cross-sectional view showing still another embodiment of an eccentricity measurement table that can be used in the method and apparatus for monitoring the piston of the holder of the above embodiment. The eccentricity measurement table 5 here has a linear stepped upper surface 5a, a substantially rectangular parallelepiped side wall 5b having the upper surface, and a rectangular support plate 5c that supports the lower end of the side wall. It is supposed to be of a configuration. If the eccentricity measurement table 5 of this embodiment is used instead of or in addition to the eccentricity measurement table 5 of any of the previous embodiments, the eccentricity of the piston 3 is measured stepwise on its stepped upper surface 5a. Therefore, the state of the piston 3 can be known in more detail. The upper surface 5a of the eccentricity measurement table 5 may be an inclined surface instead of a step shape. In this case, since the eccentricity of the piston 3 can be continuously measured, the state of the piston 3 Can know in more detail.

  Two of the eccentricity measurement tables 5 are formed on the piston 3 at the reference position so that the support plate 5c extends in the tangential direction of the peripheral edge of the piston 3 and extends in the horizontal direction perpendicular to each other. If the piston 3 is eccentric in the width direction of any of the eccentricity measurement tables 5, the laser beam is removed from the upper surface 5a of the eccentricity measurement table 5, and a sudden distance change occurs. It is possible to measure the eccentric direction of the piston 3 by identifying which one of the two eccentricity measurement tables 5 has a sudden distance change or both of which has a sudden distance change, and there is no sudden distance change. The eccentric amount of the piston 3 can be measured by the change in distance in the other eccentric amount measurement table 5.

  Further, if one eccentricity measurement table 5 is arranged on the piston 3 at the reference position so that the support plate 5c extends in the radial direction with respect to the center of the piston 3 and extends in the horizontal direction. When the piston 3 rotates, the laser beam is removed from the upper surface 5a of the radial eccentricity measurement table 5 and a sudden distance change occurs. Therefore, by identifying that there is a sudden distance change, the piston 3 Rotation can be measured.

  Although the present invention has been described based on the illustrated examples, the present invention is not limited to the above-described examples, and can be appropriately changed within the scope of the claims as required. For example, the eccentricity measurement table 5 may be installed on the piston 3, and in that case, the support plate 5c may be omitted and the distance to the surface of the piston 3 may be measured. Further, the distance meter 6 does not use the reflection of the laser beam, but may radiate an ultrasonic wave, a microwave or the like toward the eccentricity measurement table, and measure the time when the reflected light returns. Then, the height, size, number of arrangement, arrangement position, and the like of the eccentricity measurement table 5 can be appropriately changed according to the size of the dry gas holder 1, measurement accuracy, and the like.

  Thus, according to the method and apparatus for monitoring a piston of a dry gas holder of the present invention, at least three positions equidistant from the center of the piston from the distance meter measured by a distance meter provided at the upper end of the holder body. If there is a change in the height direction distance to the eccentricity measurement table of a predetermined size at a predetermined height provided for each piston, if the change is abrupt, it is determined that eccentricity has occurred in the piston. If the change is moderate, it is determined that the piston has been tilted. Therefore, not only the piston tilt but also the occurrence of the piston eccentricity that may cause the piston tilt can be monitored. The occurrence of inclination can be prevented in advance, and even if the inclination of the piston occurs, it can be dealt with promptly before incurring problems.

DESCRIPTION OF SYMBOLS 1 Dry type gas holder 2 Holder main body 2a Ceiling 3 Piston 4 Seal mechanism 5 Eccentricity measurement table 5a Upper surface 5b Side wall part 5c Support plate 6 Distance meter 7 Judgment device 8 Display device G Gas

Claims (10)

A cylindrical holder main body that extends in the vertical direction to contain gas therein, a drop-lid piston that can be moved up and down in the holder main body, a peripheral portion of the piston, and an inner peripheral surface of the holder main body In the method for monitoring a piston of a dry gas holder comprising a sealing mechanism for hermetically sealing a gap between
The piston is provided with an eccentricity measurement table of a predetermined size at a predetermined height located at at least three locations equidistant from the center of the piston,
A distance meter is provided at the upper end of the holder body to measure the distance in the height direction to the eccentricity measurement table in a non-contact manner,
When a change occurs in the distance in the height direction from the distance meter measured by the distance meter to the at least three eccentricity measurement tables, if the change is abrupt, it is determined that the piston is eccentric. The method for monitoring a piston of a dry gas holder, wherein if the change is gentle, it is determined that the piston is inclined.   2. The method of monitoring a piston of a dry gas holder according to claim 1, wherein the eccentricity measurement table includes a donut shape.   The dry gas holder piston monitoring according to claim 1, wherein the eccentricity measurement table includes two tangential directions with respect to the center of the piston and extending in directions perpendicular to each other. Method.   The method of monitoring a piston of a dry gas holder according to any one of claims 1 to 3, wherein the eccentricity measurement table includes one that extends in a radial direction with respect to a center of the piston. .   The method for monitoring a piston of a dry gas holder according to any one of claims 1 to 4, wherein the eccentricity measurement table includes a surface having a stepped or inclined surface. A cylindrical holder main body that extends in the vertical direction to contain gas therein, a drop-lid piston that can be moved up and down in the holder main body, a peripheral portion of the piston, and an inner peripheral surface of the holder main body In the piston monitoring device of the dry gas holder comprising a sealing mechanism that hermetically seals the gap between
An eccentricity measurement table of a predetermined size at a predetermined height provided to be located at at least three positions equidistant from the center of the piston;
A distance meter that is provided at the upper end of the holder body and measures the distance in the height direction to the eccentricity measurement table in a non-contact manner;
When a change occurs in the distance in the height direction from the distance meter measured by the distance meter to the at least three eccentricity measurement tables, if the change is abrupt, it is determined that the piston is eccentric. If the change is gentle, it is determined that the piston is inclined, and a piston eccentric inclination determining means for outputting the determination result;
A monitoring device for a piston of a dry gas holder, characterized by comprising:   The apparatus for monitoring a piston of a dry gas holder according to claim 6, wherein the eccentricity measurement table includes a donut-shaped table.   8. The monitoring of the piston of the dry gas holder according to claim 6, wherein the eccentricity measurement table includes two tangential directions with respect to the center of the piston and extending in directions perpendicular to each other. apparatus.   9. The monitoring device for a piston of a dry gas holder according to claim 6, wherein the eccentricity measurement table includes one that extends in a radial direction with respect to a center of the piston. 10. .   10. The monitoring device for a piston of a dry gas holder according to any one of claims 6 to 9, wherein the eccentricity measurement table includes a surface having a stepped shape or a sloped shape.

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