JP4396269B2 - Cleaning condition monitoring device and cleaning condition monitoring method - Google Patents

Description

  The present invention relates to apparatus cleaning.

  Conventionally, when cleaning equipment such as pipes and tanks in a plant, etc., it is impossible to directly determine the cleaning status, so it is not possible to determine when the cleaning has been performed sufficiently, and excessive cleaning is performed. May increase the processing load of waste liquid, etc., or on the contrary, the cleaning may be stopped due to incomplete cleaning, resulting in a malfunction of the product.

  On the other hand, Patent Document 1 discloses an apparatus that performs electrochemical measurement instead of observing a minute change in the content of a solution.

JP 2003-14681 A

  Therefore, an object of the present invention is to provide a method for monitoring the progress of the cleaning situation in real time when cleaning equipment.

The present invention includes a pipe through which a cleaning solution for cleaning equipment flows, and an electrode of an electrochemical sensor disposed in contact with the cleaning solution. The electrochemical sensor includes electrochemical current noise and electric current. This is a device for measuring chemical potential noise, and the above problem has been solved by a cleaning status monitoring device that monitors the progress of cleaning of the equipment by measuring the electrochemical current noise and electrochemical potential noise. is there.

  According to the present invention, since it is possible to know when the cleaning of the apparatus has been sufficiently completed, it is possible to prevent the cleaning from being stopped incompletely and causing problems in the subsequent products. On the contrary, it is not necessary to perform excessive cleaning, so that it is possible to suppress excessive waste liquid processing and processing time.

Hereinafter, the present invention will be described in detail.
As shown in FIG. 1, the cleaning state monitoring apparatus according to the present invention has electrochemical sensor electrodes 21 to 23 attached to a cleaning solution pipe 15 through which a cleaning solution for cleaning equipment flows.

  The equipment that can use the present invention includes, for example, a tank such as a chemical plant, a tower, a pipe itself, and the like. The progress of the cleaning of the equipment can be monitored by examining the physical properties of the cleaning solution in the piping downstream of the equipment where the cleaning solution for cleaning the equipment flows, and the cleaning is appropriately adjusted and terminated. Can be made.

The electrochemical sensor is a device that measures electrochemical current noise and electrochemical potential noise. With reference to FIG. 1 which is an example of a block diagram of a cleaning condition monitoring apparatus including the present embodiment and an electrochemical sensor disposed thereon, the current / voltage measuring means 20 constituting this electrochemical sensor will be described.

  The current / voltage measuring means 20 includes a measuring electrode, a zero resistance ammeter 24, a voltmeter 25, and bandpass filters 26 and 27. The measurement electrode has first, second and third electrodes 21, 22 and 23 made of the same material. These electrodes need to be disposed in the cleaning solution pipe 15 so as to be in contact with the cleaning solution that has cleaned the equipment, and are desirably under the same temperature condition. Further, it is desirable that the size of each electrode and the contact area with the cleaning solution be as close as possible to each other. Furthermore, it is desirable that the distance between the electrodes 21 and 22 and the distance between the electrodes 22 and 23 are the same. The distance is preferably such that the electrochemical noise resistance Rn can be calculated within an appropriate range. As the shape of these electrodes, it is more desirable that the inner surface of the pipe through which the cleaning solution passes is annularly surrounded because it has a large area and is easy to detect, and is not easily influenced by minute deviations in the liquid.

  The electrode 21 and the electrode 22 are connected by a non-resistance ammeter 24, and the electrochemical current a generated during this period is measured. This non-resistance ammeter is an ammeter whose resistance value and impedance are close to zero. The electrode 22 and the electrode 23 are connected by a voltmeter 25 having a very large resistance and input impedance in order to measure the electrochemical potential difference b so that the reaction does not proceed excessively between the electrodes. The electrochemical potential difference b between them is measured. However, the non-resistance ammeter 24 and the voltmeter 25 desirably have high sensitivity in order to measure electrochemical noise.

The above-described electrochemical current a and electrochemical potential difference b include not only electrochemical noise but also coupling current I _mean corresponding to the degree of progress of corrosion on each electrode surface and fluctuations due to other than reactions. Before sending these data to the computer 40, it is desirable to pass through the band pass filters 26 and 27 which are analysis means. By extracting fluctuations in the low frequency region, particularly in the frequency region of 1 Hz or less, preferably in the frequency region of about 0.01 to 1 Hz by using these band pass filters, the electrochemical current noise In And the electrochemical potential noise Vn can be obtained from the above electrochemical potential difference b. If the band-pass filter is not passed, the coupling current I _mean can be obtained from the current electrochemical current a, and the potential difference V _mean can be obtained from the electrochemical potential difference b. Further, it is desirable that these are converted by the converter 30 so as to be data that can be recognized by the computer 40.

  Details of specific circuit means for data processing until the current and voltage measurement data via the band pass filters 26 and 27 and the converter 30 are input to the computer 40 are shown in FIGS. 2 (a) and 2 (b). This will be described with reference to FIGS. 3A and 3B.

FIG. 2 shows an example when the processing circuit until the voltage and current measurement data signals are input to the computer 40 is constituted by an analog circuit. In this case, first, the current data, that is, the electrochemical current a between the first electrode 21 and the second electrode 22 is measured by the non-resistance ammeter 24 as shown in FIG. The frequency component of about 1 Hz or less is extracted by the band pass filter 26, and then the RMS circuit for obtaining the mean square of the signal → the DC circuit for converting the obtained signal into direct current → the signal converted into direct current is converted into a logarithm The logarithmic conversion is performed by a converter (hereinafter referred to as a “logarithmic converter”) 31 including a LOG circuit that further performs digital conversion by an analog / digital converter (hereinafter referred to as an “A / D converter”) 33, and then the computer. 40 is input as electrochemical current noise In. On the other hand, the data of the electrochemical current a can be passed through the logarithmic converter 31 and the A / D converter 33 without passing through the bandpass filter 26 and input to the computer 40 as the coupling current I _mean .

Next, the voltage data, that is, the electrochemical potential difference b between the second electrode 22 and the third electrode 23 is first measured by a voltmeter 25 as shown in FIG. After a frequency component of about 1 Hz or less is extracted from this signal by the band pass filter 27, it is logarithmically converted by the logarithmic converter 32 and further digitally converted by the A / D converter 34 in the same manner as the current data. Are input to the computer 40 as electrochemical potential noise Vn. On the other hand, the electrochemical potential difference b data can be passed through the logarithmic converter 32 and the A / D converter 34 without passing through the bandpass filter 27 and input to the computer 40 as the potential difference V _mean .

  On the other hand, FIGS. 3A and 3B are examples when the data processing circuit is configured by a digital circuit corresponding to the analog circuit configuration of FIGS. 2A and 2B. Are the same or corresponding parts, and the same operation can be obtained by the above digital circuit configuration. The converter 30 shown in FIG. 1 shows the case where the analog circuit shown in FIG. 2 is used, and the logarithmic converters 31 and 32 are omitted when the digital circuit shown in FIG. 3 is used. Will be.

In addition, when obtaining the data of the electrochemical current noise In, in addition to the method using the bandpass filter as the analysis means as described above, the electrochemical current noise In is obtained by using the data of the coupling current I _mean . It can also be obtained by directly calculating the computer 40 as an analysis means and obtaining its standard deviation. Similarly, when obtaining the data of the electrochemical potential noise Vn, the data of the potential difference V _mean between the electrodes 22 and 23 can be directly calculated by the computer 40 and the standard deviation thereof can be obtained. .

The data of the electrochemical current noise In and the electrochemical potential noise Vn input to the computer 40 constituting the electrochemical sensor, or the data of the coupling current I _mean and the potential difference V _mean are in chronological order. Recorded in the recording means 50. The recording means 50 includes not only a storable medium for storing these data but also a semiconductor memory or the like which is a temporary recording means for handling the data by the calculating means 60 and the determining means 70. This is because the condition of cleaning may be directly monitored and adjusted without saving the data.

Each data recorded in the recording means 50 is analyzed by the calculation means 60. When the bandpass filters 26 and 27 are not used, the coupling current I _mean and the potential difference V _mean are analyzed by the calculation means 60 to calculate the electrochemical current noise In and the electrochemical potential noise Vn. Good. Whether calculated by the calculation means 60 or previously extracted using the bandpass filters 26 and 27, the calculation means 60 uses the Ohm's law from the electrochemical current noise In and the electrochemical potential noise Vn. The electrochemical noise resistance Rn is calculated according to the following formula (1). In this calculation, it is necessary to match the time series. The calculated electrochemical noise resistance Rn may be recorded in time series by the recording means 50.

  Rn = Vn / In (1)

  The electrochemical noise resistance Rn that has been calculated or read once after being recorded in the recording means 50 is sent to the determination means 70 to set a preset limit value, past accumulated data, etc. And whether or not the above-described equipment has been cleaned is determined. Specifically, if a value higher than the set value of the electrochemical noise resistance Rn is maintained for a certain period of time, it is considered that impurities and dirt that can be contained in the cleaning solution and become ions can be sufficiently removed. It is determined that the cleaning is completed. At this time, the electrochemical current noise In and the electrochemical potential noise Vn as well as the electrochemical noise resistance Rn may be sent to the determination means 70 and comprehensively determined together with the value of the electrochemical noise resistance Rn.

  When the electrochemical sensor measures the electrochemical current noise In and electrochemical potential noise Vn of the cleaning solution with the current / voltage measuring means 20, and the determination means 70 determines that the cleaning in the facility is complete, the computer It is preferable to control the adjustment means 80 of the entire equipment from 40 to stop the cleaning and restart the original process of the equipment. Further, it is more desirable that the adjusting means 80 not only stop the cleaning but also finely adjust the amount of cleaning as the cleaning progresses. Specific examples of the adjusting means 80 include an electromagnetic valve that can adjust the flow rate of the cleaning liquid by an external signal.

FIG. 4 shows an installation example of the cleaning condition monitoring apparatus according to the present invention, to which the electrochemical sensor A is attached.
The equipment 12 to be cleaned is, as a specific example, a tank, a tower, a pipe, etc. in the plant, and a substance flowing from the upstream pipe 11 is allowed to pass through, stay in it, or undergo a process such as reaction or change. Then, it is sent to the downstream pipe 13. In cleaning the equipment 12, the inflow from the upstream pipe 11 and the outflow to the downstream pipe 13 are temporarily stopped, and the cleaning liquid p is allowed to flow in from the separately provided cleaning liquid pipe 14 to The cleaning solution q after the cleaning and the cleaning is finished flows out into the cleaning solution pipe 15 provided separately downstream and sent to the waste liquid treatment process.

  An electrochemical sensor A for controlling the flow rate of the cleaning liquid p in accordance with the progress of the cleaning is provided in a pipe downstream of the facility 12 through which the cleaning solution q flows. The electrodes 21 to 23 are attached so as to be in contact with the cleaning solution q. In addition, as long as the piping through which the cleaning solution q flows, the cleaning solution piping 15 branched from the downstream piping 13 may be provided. When the cleaning liquid p supplied to the facility 12 comes out as a cleaning solution q after cleaning, the amount of dirt contained varies depending on the progress of cleaning of the facility 12. This changes the current and potential difference measured by the electrodes 21-23.

  When the electrochemical sensor A measures the cleaning solution q and determines that the cleaning of the equipment 12 has been completed, the cleaning liquid p is closed to end the cleaning. Furthermore, when the electrochemical sensor A is capable of finely determining the numerical value of the cleaning solution q, and according to the determined cleaning status, the adjusting means 80 can finely control the pump stroke of the valve that supplies the cleaning liquid p. Reliable cleaning is possible.

  After the cleaning of the equipment 12 is finished and the supply of the cleaning liquid p is stopped, the valve connected to the cleaning solution pipe 15 is closed, and then the valves connected to the upstream pipe 11 and the downstream pipe 13 are opened, and the equipment is restored. 12 is activated.

  As shown in FIG. 1, the result determined by the determination means 70 is sent to the output means 90, and displayed on the screen of the display 91 such as a CRT or a liquid crystal or on the printout of the printer 92. Then, the valve of the cleaning liquid p may be adjusted. However, in terms of efficiency, it is desirable to control the valve of the cleaning liquid p directly from the computer 40 by the adjusting means 80.

Further, together with the above judgment results, the electrochemical noise resistance Rn, electrochemical current noise In, electrochemical potential noise Vn, coupling current I _mean , potential difference V _{mean and the} like are sent to the output means 90 for each measurement. The instantaneous value of data, the transition of trend values expressed in time series, the accumulated value, etc. may be displayed separately or in association with each other. Further, it is more desirable to record and accumulate these data in the recording means 50 and to make a judgment material for obtaining a more optimal setting for indicating the completion of cleaning.

The cleaning condition monitoring apparatus according to the present invention is particularly effective in the piping section of an aqueous plant. If it is an aqueous system, even if water is used as the cleaning liquid p, the plant can be restarted quickly without requiring thorough drying after cleaning.

  The present invention will be described more specifically with reference to the following examples. In addition, the apparatus which has the structure and function shown in FIG. 1 thru | or FIG. 4 was used as a cleaning condition monitoring apparatus.

  FIG. 5 shows the time-series transition of the electrochemical noise resistance Rn of the cleaning solution at the time of cleaning at the Mitsubishi Chemical Mizushima Plant, and the concentrations of ammonia and hydrogen sulfide in the cleaning solution at that time. Shown in In the cleaning, the pump stroke of the cleaning liquid p was increased stepwise, and then the pump stroke was decreased stepwise according to the change in the electrochemical noise resistance Rn.

  It can be confirmed that the electrochemical noise resistance Rn decreases according to the amount of dirt in the cleaning solution. With this electrochemical noise resistance Rn, the progress of cleaning can be monitored, and the pump stroke can be adjusted. The cleaning was sufficient and less wasteful.

The block diagram which shows the outline of the circuit example of the electrochemical sensor which processes the data which is measured with the cleaning condition monitoring device The block diagram which shows an example when the circuit of the electrochemical sensor of FIG. 1 is comprised with an analog circuit. The block diagram which shows an example when the circuit of the electrochemical sensor of FIG. 1 is comprised with a digital circuit. The block diagram which shows the outline | summary of arrangement | positioning of the cleaning condition monitoring apparatus concerning this invention with respect to an installation The graph which shows the change of ammonia, hydrogen sulfide, and Rn when adjusting a pump stroke according to transition of Rn in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Upstream piping 12 Equipment 13 Downstream piping 14 Cleaning liquid piping 15 Cleaning solution piping 20 Current voltage measuring means 21 1st electrode 22 2nd electrode 23 3rd electrode 24 Non-resistance ammeter 25 Voltmeter 26, 27 Band pass Filter 30 Converter 31, 32 Logarithmic converter 33, 34 A / D converter 40 Computer 50 Recording means 60 Calculation means 70 Determination means 80 Adjustment means 90 Output means 91 Display 92 Printer a Electrochemical current b Electrochemical potential difference In Electrochemical Current noise Vn Electrochemical potential noise I _mean Coupling current V _mean Potential difference Rn Electrochemical noise resistance A Electrochemical sensor p Cleaning solution q Cleaning solution

Claims (5)

A pipe through which a cleaning solution for cleaning equipment flows, and an electrode of an electrochemical sensor arranged in contact with the cleaning solution, wherein the electrochemical sensor includes electrochemical current noise and electrochemical potential noise; A device for measuring
A cleaning status monitoring device that monitors the progress of cleaning of the equipment by measuring the electrochemical current noise and the electrochemical potential noise. The cleaning condition monitoring apparatus according to claim 1, wherein the electrode is an electrode that annularly surrounds an inner surface of a pipe through which the cleaning solution passes. The electrochemical sensor has three electrodes connected in parallel, and current voltage measuring means for measuring data of current and potential difference generated between the electrodes,
Analytical means for obtaining electrochemical current noise and electrochemical potential noise data from the above current and voltage data,
Recording means for recording the data of the above electrochemical current noise and electrochemical potential noise in chronological order,
And the data of the electrochemical current noise and the electrochemical potential noise is taken out from the recording means, and has a calculation means for calculating the electrochemical noise resistance of the cleaning solution in order of time series from this data. The cleaning condition monitoring apparatus according to claim 1 or 2. The cleaning condition monitoring apparatus according to claim 3, wherein the electrochemical sensor includes a determination unit that analyzes data of the electrochemical noise resistance and determines completion of cleaning of the apparatus .   A cleaning status monitoring method for monitoring the progress of cleaning of the equipment, using the cleaning status monitoring device according to claim 1.

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