JPH0830686B2 - Damage detection method for equipment lining layer - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) For equipment with a corrosion-resistant lining layer such as glass lining, if the lining layer is damaged due to an unexpected cause during use, the base metal ion If the metal is eluted to cause a loss of the product, or if the corrosive effect is significant, the base metal may be penetrated in a short time, leading to a serious accident.

TECHNICAL FIELD The present invention relates to an improvement in a technique that enables damage of a lining layer in such a device to be detected at the earliest time during use of the device and to take countermeasures while the damage is slight.

(Prior Art) FIG. 4 is a view showing in principle an example of a prior art for detecting damage to a lining layer of this type of lining equipment.

Connect the (+) pole (4) of the DC power supply (3) to the base metal (2) of the equipment that has been made corrosion resistant by applying the corrosion resistant lining layer (1) such as glass lining and store it in the equipment. a high corrosion resistance electrodes such as platinum electrode carrier is placed in the conductive liquid medium of the reaction process material (5) (6) (7) (-) resistors R ₁ and insulating connecting the electrode conductive liquid medium The change in the value of the current flowing through the high resistance R ₂ of the lining layer (1) is measured. That is, if the corrosion-resistant lining layer (1) is sound, the electric current value is small because the electric resistance value R ₂ is large, but if the lining layer is damaged, the electric resistance value of the portion is reduced and the electric current value decreases. The basic principle is that the value increases. This circuit is the detection circuit (A).

In this case, the property of the conductive liquid medium in the equipment should be constant, but in actual operation, temperature change, concentration change, etc. occur, that is, if the temperature changes, for example, the electrical resistance of the lining layer and the conductive liquid medium is changed. Changes and the current value also changes correspondingly, making it difficult to identify the change in current value due to damage to the lining layer. Therefore, the electrode (7) is shared in the conductive liquid medium, a pair of electrodes (8) is provided, and an AC voltage is applied between both electrodes (7) and (8) from an external AC power source (9) in the conductive liquid medium. A reference circuit (B) for measuring the value of the current flowing through is provided. The current value of the reference circuit (B) is used as the denominator, and the current value of the direct current detection circuit (A) is used as the numerator to calculate the ratio to determine the degree of damage to the corrosion-resistant lining layer. As a result, the difficulty of discrimination due to the temperature change and the concentration change of the conductive liquid medium can be eliminated to some extent.

(Problems to be Solved by the Invention) In the above-mentioned conventional technique, since damage to the corrosion-resistant lining layer is continuously monitored, both the reference circuit and the detection circuit are simultaneously energized.

In this case, the detection circuit current usually has only a small current because the electrical resistance of the corrosion-resistant lining layer is large, but in the reference circuit, a current according to the resistance value of the conductive liquid medium flows, and the current The value is 10 to 20 times the current value of the detection circuit.

As a result, depending on the type of the conductive liquid medium, a product caused by an electrochemical action adheres to the electrodes (7) and (8) and increases with time.
In this case, since the amount of the attached product is proportional to the amount of electricity supplied, the resistance of the electrode portion gradually increases and acts to reduce the current value of the circuit. Thus, in addition to the current change caused by the temperature and concentration change state at a certain point, the current change caused by a secondary factor such as the generation of deposits that increase with time is added. Therefore, an error is generated in the temperature and concentration change compensation reference which is the purpose of, and the reliability and accuracy of the flaw detection result decrease.

An object of the present invention is to eliminate the above-mentioned problems of the conventional damage detection technology for equipment lining layers.

(Means for Solving Problems) In the present invention, when a reference circuit is used together with a detection circuit, in order to reduce deposits due to an electrochemical action generated by energizing the reference circuit, The current is not applied continuously but is applied intermittently by limiting the duration to the minimum required and sufficient for detecting damage to the lining layer. In this case, the detection circuit may be continuously energized, but a short time lag between them is added to clarify the separation of the energization time so as not to overlap with the energization to the reference circuit as much as possible. It is desirable to alternately carry out through.

That is, the damage detection method for the equipment lining layer of the present invention, as an overall configuration, contains a conductive liquid medium in order to detect damage to the lining layer of the equipment that is made corrosion resistant by applying the corrosion resistant lining layer. Applying a DC voltage between the base metal of the device as one pole and another electrode installed in the liquid medium, the current flowing through the series electric resistance of the liquid medium and the lining layer is measured, and the change causes the lining layer to change. Circuit (A) for detecting breakage of the liquid and a voltage between the two electrodes by applying an AC voltage between the two electrodes installed in the liquid medium in order to compensate for the change in the current of the detection circuit caused by the change in the property of the liquid medium. Further, in the damage detection circuit configured by the reference circuit (B) for measuring the current flowing through the resistance of the liquid medium, the reference circuit is energized intermittently.

When one of the reference circuit electrodes is shared with the detection circuit electrode as a preferred embodiment, the energization of the reference circuit and the detection circuit is alternately repeated with a short time lag.

The method of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a time chart of circuit energization according to the present invention. The horizontal axis indicates the passage of time, and the vertical axis indicates the presence or absence of energization by connection ON-OFF.

In the upper half of FIG. 1, the energization waveform of the reference circuit (B) repeats the energization of the energization continuation time T ₁ at intervals with a constant time interval.

Energization waveform to the detection circuit (A) in the lower half a preferred embodiment of Figure 1, butt manner during the energization of the energization time duration T ₂ during associated the non-energized time interval between energization of the reference circuit Then, do not overlap with the energization of time T ₁ . A short time lag time T _O is provided between the energization durations T ₁ and T ₂ in order to ensure that the overlap is avoided.

(Operation) In the present invention, for the purpose of continuously detecting damage to the lining layer, the detection circuit cannot be energized within the reference circuit energization time T ₁ and the time lag time T _O , but the time T ₁ is short, for example, about 30 sec., And the time T _O can be further shortened. On the other hand, the detection circuit energization time is sufficiently long, for example, about 300 sec., So practically it is almost continuous without impairing the stability state. Near detection is possible.

Since the energization time T ₁ to the reference circuit (B) is short and the energization time interval is long, the cumulative amount of electricity supplied to the reference circuit is significantly smaller than that in the continuous application method of the prior art, and adhesion to the electrode is generated. Not only does it significantly reduce the number of objects and prolong the electrode life, but also the time lag time is short and the difference between both energization times is short, so the role of reference compensation is sufficient for the subsequent electrical measurement results during energization of the detection circuit (A). Can be done accurately.

FIG. 2 shows the results of an experiment conducted to confirm the effectiveness of the method of the present invention. The test was conducted at a temperature of 21 ° C. using 25 wt% lactic acid as a conductive liquid medium. ) And the reference circuit current (mA) is plotted on the vertical axis to show the time change.

According to the method of the present invention, the detection circuit continuous energization time T ₁ 300
Second, the reference circuit current value when intermittently energized with the reference circuit continuous energization time T ₂ 30 seconds shows little decrease as shown by the line (a). In comparison with this, when the reference circuit is continuously energized, the current drop is remarkable as shown by the line (b). This allows
It is clear that the conduction time affects the current reduction.
Furthermore, if both circuits are energized continuously by conventional technology,
As shown by the line (c), the decrease in current value is the most remarkable. From this, the influence of the superposition of AC and DC voltages in each circuit is clear.

(Example) As an example, FIG. 3 shows a circuit of an apparatus used directly for carrying out the method of the present invention. Since the device has much in common with that of the prior art, the same reference numerals are used to indicate the components common to the principle explanatory view of FIG. 1, and duplicate description is omitted.

Explaining the difference from the device of the prior art, in the reference circuit (B), the continuous energization time from the AC power source (9) to the electrodes (7) and (8) by closing the contacts of the relay (10).
An alternating voltage is applied intermittently at T ₁ , and the current value is transmitted to a control calculator (13) via an amplifier (11) and an A / D converter (12).

In the detection circuit (A), the DC voltage is intermittently applied between the DC power source (3), the base metal (2), and the electrode (7) at the continuous energization time T ₂ by closing the contact of the relay (14). The applied current value is transmitted to the control calculator (13) via the amplifier (15) and the A / D converter (16).

In the control arithmetic unit (13), both current signals are compared with each other through the memory, and a lining damage degree signal is output to the output line (17).

A voltage application signal is transmitted from the control arithmetic unit (13) to the relays (10) and (14) via the control lines (18) and (19) so as to have a timing and a time lag T _O.

(Effects of the Invention) According to the method of the present invention, the generation of electrode deposits that cause reference compensation error of the reference circuit is reduced when detecting damage to the lining layer during use of a device provided with corrosion resistance by applying the corrosion-resistant lining layer. Enables accurate detection of damage level,
This has the effect of preventing accidents due to product contamination and equipment damage.

[Brief description of drawings]

FIG. 1 is a timing chart of circuit energization according to the present invention, FIG.
FIG. 3 is a diagram showing the change in current value due to the adhered products on the reference circuit electrodes, with the horizontal axis representing time and the vertical axis representing the reference circuit current value, and FIG. FIG. 4 is a circuit configuration diagram showing in principle an example of a conventional technique for detecting damage to a lining layer. (1) …… lining layer, (2) …… base metal, (3)
...... DC power supply, (4) …… + pole, (5) …… conductive liquid medium, (6) …… electrode carrier, (7) (8) …… electrode,
(9) …… AC power supply, (10) (14) …… Relay, (11)
(15) …… Amplifier, (12) (16) …… A / D converter, (1
3) …… Control calculator, (18) (19) …… Control line, (A)
…… Detection circuit, (B) …… Reference circuit, (T ₁ ) (T ₂ ) (T _O ) ……
Time, (a) (b) (c) ... Curve.

Claims (2)

[Claims] 1. In order to detect damage to the lining layer of a device which is made corrosion resistant by applying a corrosion resistant lining layer, the base metal of the device containing the conductive liquid medium is set as one pole and installed in the liquid medium. By applying a DC voltage between the electrodes and measuring the current flowing through the series electric resistance of the liquid medium and the lining layer and detecting the damage of the lining layer due to that change, the change of the property of the liquid medium In order to compensate the change in the detection circuit current that occurs, an AC voltage is applied between two electrodes installed in the liquid medium, and a reference circuit that measures the current flowing through the resistance of the liquid medium between the two electrodes detects damage. A method for detecting damage to a device lining layer, characterized in that, in a circuit configuration, the reference circuit is energized intermittently. 2. The method according to claim 1, wherein when one of the electrodes for the reference circuit is shared with the electrode for the detection circuit, energization to the reference circuit and the detection circuit is alternately repeated with a short time lag.
A method for detecting damage to the equipment lining layer according to the item.