JP2014234944A - Water quality monitor - Google Patents

Abstract

To provide a water quality monitor capable of satisfactorily determining the quality of boiler water without being affected by changes in detection of a temporary water quality abnormality caused by water supply or concentration blow of the boiler. A water quality monitor (10) is installed in a boiler (80) and generates a water quality signal corresponding to the water quality of the boiler water. The water quality monitor (10) is connected to the water quality sensor (20) and determines the water quality of the boiler water based on the water quality signal. The controller 40 acquires the water quality signal of the water quality sensor 20 at a predetermined sampling period, sequentially calculates the average value of the water quality signal in a predetermined average calculation period, and sets the average value to the average value. Based on this, the water quality of the boiler water is determined. [Selection] Figure 3

Description

  The present invention relates to a water quality monitor for managing the quality of boiler water.

  If the dissolved oxygen concentration or harmful ion concentration in the boiler water increases, or the boiler water quality deteriorates due to low boiler water pH, etc., Since corrosion may occur, boiler water quality inspection has been conventionally performed.

  For example, in Patent Documents 1 and 2 below, a water quality sensor including a pair of electrodes is installed in a boiler can body, and the water quality is inspected based on a sensor output signal such as a current flowing between the electrodes according to the water quality of the boiler water. Thus, an apparatus for detecting the corrosiveness of boiler water is disclosed.

No. 7-34370 Japanese Patent Laid-Open No. 10-332623

  However, usually, in the boiler, events such as water supply and concentration blow are performed, so that the quality of the boiler water temporarily changes abruptly. For this reason, in the water quality inspection based on the output signal of the water quality sensor, there may be a problem that such a temporary change in water quality due to a sudden change in the water quality signal is detected and it is determined that the water quality has deteriorated.

  The present invention has been made in view of such a problem, and is not affected by a temporary change in water quality caused by boiler water supply, concentration blow, or the like, and can perform water quality determination of boiler water satisfactorily. The purpose is to provide a monitor.

  In order to solve the above problems, a water quality monitor according to the present invention is installed in a boiler and generates a water quality signal corresponding to the water quality of the boiler water, and is connected to the water quality sensor, and based on the water quality signal. A controller for determining the water quality of the boiler water, the controller acquires the water quality signal of the water quality sensor at a predetermined sampling period, and sequentially calculates the average value of the water quality signal in a predetermined average calculation period. The water quality of the boiler water is determined based on the average value.

  According to the water quality monitor according to the present invention, it is possible to satisfactorily determine the quality of boiler water without being affected by a temporary change in water quality caused by water supply or concentration blow of the boiler.

FIG. 1 is a diagram schematically showing a part of the configuration of a water quality monitor according to an embodiment of the present invention. FIG. 2 is a diagram showing the installation status of the water quality monitor according to the embodiment of the present invention. FIG. 3 is a flowchart for explaining the flow of water quality determination processing in the controller according to the embodiment of the present invention. FIG. 4 is a diagram illustrating a time-lapse model of the output signal of the water quality sensor according to the embodiment of the present invention.

  Hereinafter, a water quality monitor according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing a part of the configuration of a water quality monitor 10 according to the present embodiment. In addition, in FIG. 1, some water quality sensors 20 are shown with sectional drawing. FIG. 2 is a diagram schematically illustrating an installation state of the water quality monitor 10 according to the present embodiment on the boiler 80.

  The water quality monitor 10 is a device that is installed in the boiler 80 to determine the water quality of the boiler water. The water quality sensor 20 generates a water quality signal corresponding to the water quality of the boiler water, and the boiler water based on the output signal. And a controller 40 for determining water quality.

  The water quality sensor 20 is a corrosion sensor using galvanic corrosion (dissimilar metal contact corrosion), and outputs a water quality signal corresponding to the dissolved oxygen concentration, pH, and harmful ion concentration of boiler water. The dissolved oxygen concentration, pH, and harmful ion concentration in the boiler water are highly correlated with the corrosivity of the boiler water in the can 81, and the water quality monitor 10 determines the quality of the boiler water based on the water quality signal from the water quality sensor 20. Thus, the corrosivity of boiler water can be evaluated.

  As shown in FIG. 1, the water quality sensor 20 includes an electrode holder 21, a first electrode 23, a second electrode 25, a sensor cable 30, and an amplifier 33. The electrode holder 21 is a holder for supporting and fixing the first electrode 23 and the second electrode 25 with a predetermined gap.

  The first electrode 23 is an electrode made of iron (SS: rolled steel for general structure) and has a hollow substantially cylindrical shape. The second electrode 25 is a stainless steel (SUS) electrode and has a thin cylindrical shape. The second electrode 25 is disposed concentrically in parallel with a predetermined gap in the hollow portion of the first electrode 23, and is fixed to the electrode holder 21 with a set screw.

  The sensor cable 30 has one end connected to the first electrode 23 and the second electrode 25 and the other end connected to the controller 40. An amplifier 33 is installed in the sensor cable 30, and a water quality signal flowing through the sensor cable 30 is amplified by the amplifier 33 and sent to the controller 40.

  As shown in FIG. 2, a sensor socket 83 for fixing and installing the water quality sensor 20 is installed on the side surface of the lower header 82 of the can 81. The main body portion of the water quality sensor 20 is fixed to the sensor socket 83 so that the first electrode 23 and the second electrode 25 protrude into the can 81.

  The sensor socket 83 is installed on the side surface of the lower header 82 and near the water pipe on the burner side. The vicinity of the water pipe on the burner side of the lower header 82 is a portion where corrosion is likely to proceed even in the can body 81. Therefore, if the water quality sensor 20 is installed in the vicinity, the corrosiveness of the boiler water in the can body 81 can be accurately measured. It can be detected well.

  In the water quality sensor 20 installed in the boiler 80 as described above, a galvanic current (water quality signal) flows between different electrodes according to the dissolved oxygen concentration, pH, and harmful ion concentration of the boiler water.

  The controller 40 determines the quality of the boiler water based on this water quality signal, and evaluates the corrosiveness of the boiler water in the can 81. The controller 40 may be configured integrally with the controller of the boiler 80. FIG. 3 is a flowchart for explaining the flow of water quality determination processing by the controller 40 according to the present embodiment.

  The controller 40 calculates the average value of the water quality signal every day while sampling the water quality signal every second, and determines the abnormality of the water quality based on the change amount and magnitude (absolute value) of the average value. It is characterized by doing.

  Specifically, first, in S1, the controller 40 acquires a water quality signal that is an output signal of the water quality sensor 20 with a sampling period of 1 second. Next, in S2, it is determined whether one day (average value calculation period) has elapsed since the start of acquisition of the water quality signal. If one day has passed, the process proceeds to S3, where the average value of the water quality signal is calculated for one day. To do.

  In S4, the quality of water quality is determined based on the change amount of the average value. That is, the controller 40 obtains a change amount that is a difference between the average value of the previous time (previous day) and the average value calculated this time, and when the calculated change amount is equal to or greater than a predetermined change amount reference value (100 μA). Advances to S6, determines that the water quality is abnormal, and if not, advances to S5 and performs the next determination.

  In S5, the quality of the water is determined based on the average value. That is, when the average value calculated this time is equal to or greater than the predetermined absolute value reference value (300 μA), the controller 40 proceeds to S6 and determines that the water quality is abnormal. Is not abnormal, the process returns to S1, and the water quality signal is continuously sampled.

  If it is determined in S6 that the water quality is abnormal, the boiler water is in a highly corrosive state such as a state where the dissolved oxygen concentration is high, the pH is deteriorated, or the harmful ion concentration is high. Therefore, there is a high possibility that can puncture will occur in the future. Therefore, the manager of the boiler 80 investigates the cause of the deterioration of the water quality and takes measures such as changing the chemical to be used.

  In this embodiment, since the average calculation period is one day, when the cause of the deterioration of water quality is the repair of the boiler 80 or the replacement of parts, the administrator can look back on the work performed on that day. In some cases, the cause can be easily identified.

  As described above, the controller 40 calculates the average value of the water quality signal acquired at the predetermined sampling period in the predetermined average calculation period (one day), and determines the water quality of the boiler water based on the average value. Therefore, the quality of the boiler water can be well determined without unnecessarily detecting a temporary sudden change in the water quality signal due to an event such as short-time water supply or concentration blow.

  Moreover, even if the output of the water quality sensor 20 is reduced by determining the water quality based on the calculated change amount of the average value, the sudden deterioration of the boiler water quality is reliably detected. Can do. For example, in the initial stage of boiler introduction, an oxide film is formed on the surface of the iron first electrode 23 of the water quality sensor 20 and a chemical reaction on the electrode surface is suppressed. Even in such a case, good water quality determination can be performed.

  On the other hand, in the case of water quality determination based on the amount of change, the output signal of the water quality sensor 20 gradually increases, such as when the water quality of the water supply source (ground water, industrial water, tap water, etc.) to the boiler 80 is slowly deteriorating. When it does, it cannot detect deterioration of water quality. However, by performing water quality determination based on the calculated average value as in the present embodiment, it is possible to perform good water quality determination even when the water quality gradually deteriorates.

  Of course, the water quality determination processing method can be changed as appropriate. For example, the order of the determination process based on the amount of change in S4 and the determination process based on the absolute value in S5 may be changed or performed simultaneously. good.

  In S4, the water quality is determined using the difference between the current average value and the previous day's average value as the amount of change. However, the difference between the current average value and the average value for the past several days is determined as the amount of change. May be.

  Moreover, the value of each parameter used in the water quality determination process can be changed as appropriate. For example, in the above embodiment, the sampling period is 1 second, but the sampling period may be 1 second or less, or 1 second or more (for example, 5 seconds or 10 seconds). However, in order to make it possible to detect a change in water quality due to an event such as water supply or concentration blow of the boiler 80, the sampling period is preferably shorter than the period when the water supply is performed or the period when the concentration blow is performed. .

  Further, the period during which the controller 40 calculates the average value (average calculation period) can be changed as appropriate, and may be, for example, 1 hour, 5 hours, half day, 2 days, or the like. However, if the average calculation period becomes too short, a temporary sudden change in water quality due to water supply or concentration blow of the boiler 80 may be detected, and the average value may become too large temporarily.

  Therefore, it is desirable that the average calculation period is a length of time such that water supply (for example, the cycle is about 5 minutes) and concentration blow (for example, the cycle is about 20 to 30 minutes) are performed a plurality of times. On the other hand, if the average calculation period is too long, the amount of change in the average value may become too small, so it is necessary to make the length so that deterioration of water quality can be detected.

  Further, the change amount reference value, which is the water quality determination criterion in S4, and the absolute value reference value, which is the water quality determination criterion in S5, can be changed as appropriate according to the installation environment of the boiler 80 and the like.

  Next, an example of water quality determination processing according to the present embodiment will be described with reference to FIG. FIG. 4 is a diagram illustrating the time lapse of the water quality signal of the water quality sensor 20 according to the present embodiment, where the vertical axis indicates the water quality signal [μA] and the horizontal axis indicates the time.

In FIG. 4, the operation start time of the boiler 80 after the trial operation is set to t _0, and then water quality abnormality detection by the change amount determination (t ₃ ), water quality abnormality detection by the absolute value determination (t ₄ ), total concentration blow and sensor cleaning (T ₅ ), the state where the event of concentration blow (t ₇ ) has occurred is shown as a model.

First, at t ₀ , the boiler water quality is not stable because it is in the initial stage of boiler introduction after the trial operation, and there is a high possibility that the water quality signal shows a large output value. Therefore, in the present embodiment, the controller 40 pauses the water quality determination by the water quality monitor 10 for a predetermined period X ₆ (t _{0 to} t ₁ ) until the water quality is stabilized.

In the present embodiment, the determination idle period X ₆ is 50 hours at high fire converted. In this way, by setting the period during which the boiler water quality is not stable as the determination suspension period, it is possible to prevent unnecessary detection of a water quality change that is not related to the corrosiveness of the boiler water.

Further, the t _3, the controller 40, the change amount determining S4, described above (arrow A), determines that the water quality abnormality. That is, at t ₃ , the controller 40 calculates the average value of the average calculation period X ₃ (1 day) of the water quality signal and then calculates the average value of the average calculation period X ₂ (1 day) calculated at t ₂ of the previous day. The change amount X ₁ (100 μA) that is the difference between the two is obtained. In the present embodiment, since the change amount reference value is 100 μA, the controller 40 determines that the water quality is abnormal at t ₃ .

Further, the t _4, the controller 40, the absolute value determination S5, described above (arrow B), determines that the water quality abnormality. That is, at t ₄ , the controller 40 calculates the average value X ₅ (300 μA) of the average calculation period X ₅ (1 day) of the water quality signal. In this embodiment, since the absolute value reference value is 300 μA, the controller 40 determines that the water quality is abnormal at t ₄ .

Further, when the total blowdown and sensor washed with t ₅ is performed, replaced large boiler water in the can body 81, the water quality of the boiler water is not stable. Therefore, the water quality determination by the water quality monitor 10 is suspended as in the above-described t ₀ to t ₁ . The determination pause period X ₇ (t _{5 to} t ₆ ) for preventing unnecessary detection of abnormal water quality is 20 hours in terms of high combustion.

Further, when the concentration blow is performed at t ₇ , the water quality is not stabilized due to the replacement of the boiler water. Therefore, the controller 40 similarly stops the water quality determination by the water quality monitor 10. The determination suspension period X ₈ (t _{7 to} t ₈ ) for preventing unnecessary detection of abnormal water quality is 1 hour in terms of high combustion.

  As mentioned above, although this embodiment was described, according to this embodiment, the water quality determination of boiler water can be performed satisfactorily without being influenced by a temporary change in water quality caused by water supply or concentration blow of the boiler 80. .

  Then, the modification of this embodiment is demonstrated. In the present modification, in the water quality determination of the boiler water according to the above embodiment, the water quality deterioration is further determined based on a second average value that is an average value every 60 seconds of the water quality signal of the water quality sensor 20. Yes.

  Specifically, the controller 40 sequentially calculates a second average value in a second average calculation period (60 seconds) shorter than the average calculation period (1 day), and the average of the second average values When the maximum value in the calculation period (one day) is equal to or greater than the maximum value reference value, it is determined that the water quality is abnormal.

  Here, the maximum value reference value is a predetermined value, and may be the same as the absolute value reference value (300 μA) or a different value. However, it is desirable that the water quality change due to the water supply or concentration blow of the boiler 80 is set to a value that does not determine that the water quality has deteriorated.

  In this way, by performing the water quality determination based on the second average value in the shorter second average calculation period (60 seconds), the effect of the average value in units of one day is temporarily erased. It will be possible to detect changes in water quality signals.

  For example, in a boiler system with multiple cans, there may be a case where condensed water is brought into a low-load operation boiler and temporarily increases the corrosiveness of the boiler water in a low-load operation boiler. In such an average value, such a change in water quality cannot be detected.

  On the other hand, according to this modification, it is possible to detect temporary deterioration of water quality due to the flow of condensed water into the low-load operation boiler, and to improve the corrosivity of boiler water by taking some measures. be able to.

  Of course, the second average calculation period can be changed as appropriate. If the period is shorter than the average calculation period (one day), a change in water quality that cannot be detected by the absolute value determination in S5 can be detected. Note that the second average calculation period is set to 30 seconds or more so as not to detect a temporary rapid increase in the water quality signal caused by the water supply (about 10 seconds) of the boiler 80, which has no correlation with the corrosiveness of the boiler water. Is desirable.

  As mentioned above, although embodiment of this invention was described including the modification, embodiment of this invention is not limited to the said embodiment, A various deformation | transformation is possible within the range which does not deviate from the main point of this invention. It is. For example, the material of the electrode of the water quality sensor can be changed as appropriate. However, in the case of a corrosion sensor using galvanic corrosion, it is necessary to combine electrodes made of different metals having different ionization tendencies.

  Moreover, in the said embodiment, although the corrosion sensor using the galvanic corrosion which makes a galvanic current a water quality signal is used, if it is a water quality sensor which outputs the water quality signal according to the water quality of boiler water, another sensor will be used suitably. Can be used. For example, a polarization resistance type sensor may be used.

DESCRIPTION OF SYMBOLS 10 Water quality monitor 20 Water quality sensor 21 Electrode holder 23 First electrode 25 Second electrode 30 Sensor cable 33 Amplifier 40 Controller 80 Boiler 81 Can body 82 Lower header 83 Sensor socket

Claims (4)

A water quality sensor installed in the boiler to generate a water quality signal corresponding to the quality of the boiler water;
A controller connected to the water quality sensor and determining the quality of boiler water based on the water quality signal;
The controller acquires a water quality signal of the water quality sensor at a predetermined sampling period, sequentially calculates an average value of the water quality signal in a predetermined average calculation period, and determines the water quality of the boiler water based on the average value A water quality monitor.   The water quality monitor according to claim 1, wherein the controller determines the water quality of the boiler water based on the magnitude and change amount of the average value.   The predetermined sampling period is a period shorter than a period in which the concentration blow is performed in the boiler and a period in which the water supply is performed, and the predetermined average calculation period includes a plurality of times of the concentration blow and the water supply in the boiler, respectively. The water quality monitor according to claim 1, wherein the water quality monitor is a period of time for implementation.   The controller further sequentially calculates a second average value in a second average calculation period, which is a period shorter than the predetermined average calculation period, and a maximum of the second average value in the predetermined average calculation period. The water quality monitor according to any one of claims 1 to 3, wherein the water quality of the boiler water is determined based on the value.

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