JP2004321860A - Liquid chemical injection control unit and liquid chemical injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid chemical injection control unit capable of detecting abnormality inexpensively, easily and accurately even if the injection amount of a liquid chemical is controlled so as to be changed over a wide range in response to the fluctuations in the flow velocity of a fluid to be treated, or the like. <P>SOLUTION: The liquid chemical injection control unit is equipped with a target injection amount operation means 8 for operating and leading out the target injection amount SV of the liquid chemical on the basis of the detected flow rate of tap water due to a flowmeter 1b and the target concenteration of the liquid chemical, an injection amount control means 9 for outputting the drive control signal MV corresponding to a drive frequency signal to an inverter 10 being the drive circuit of a chemical injection pump 5 so that the detected injection amount PV of the liquid chemical injected by the liquid chemical injection pump 5 and detected by a liquid chemical flowmeter 4b becomes the target injection amount SV, and a monitor means 11 for self-diagnosing the operation state of a liquid chemical injection device on the basis of the drive control signal MV, the detected injection amount PV and table data. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to injection of a chemical solution such as a scale inhibitor, a deoxidizer, and a condensate into feed water flowing into a boiler feed pipe, injection of sodium hypochlorite (NaClO) as a disinfectant into a water supply pipe, The present invention also relates to a chemical injection control device for controlling an injection amount of a chemical such as a predetermined coagulant or a ph regulator into a fluid to be processed in various fluid processing devices, and a chemical injection device provided with the chemical injection control device.
[0002]
[Prior art]
Conventionally, irrespective of the type of fluid, as a drug solution injection device that can inject a drug solution into a fluid flowing in a pipe in a flow rate proportional injection method, a flow rate sensor disposed in a pipe, and from this flow rate sensor An inverter to which the flow rate signal is input, a chemical injection pump for proportionally controlling the discharge amount of the chemical based on the signal from the inverter, and a chemical injection path for injecting the chemical discharged from the chemical injection pump into the pipeline. A device provided with a chemical solution injection mechanism has been proposed.
[0003]
[Patent Document 1]
JP-A-9-264507
[Problems to be solved by the invention]
However, according to the above-described conventional technology, an open-loop control mechanism that proportionally controls a discharge amount of a chemical solution based on a flow rate signal of a fluid to be processed from a flow rate sensor is employed, and is injected into a pipeline. However, it is not guaranteed that the amount of the chemical solution is always controlled to the target injection amount. Also, regarding the abnormality detection mechanism required for that, when the discharge amount is almost constant, a pressure alarm is provided on the pump discharge side, and when a predetermined pressure level is detected, it is determined that an abnormality is present and an alarm is issued. Although it is possible to set the alarm level, if the amount of the injected chemical solution is controlled to change in a wide range in response to fluctuations in the flow rate of the fluid to be processed, a single pressure alarm meter There was a problem that it did not work effectively. In addition, in order to determine the cause of an abnormality in the system, various sensors must be arranged at locations where the cause is assumed to occur, and an abnormality level must be individually set to determine an abnormality based on the detection detected by the sensor. There was also a problem that it was expensive and complicated. In particular, in the case of injecting a chemical solution into a fluid to be treated, which has a large fluctuation in flow velocity, such as injecting sodium hypochlorite (NaClO) as a disinfectant into a water supply pipe, it is difficult to detect the abnormality at low cost and easily. there were.
[0005]
The present invention has been made in view of the above-described conventional problems, and even when the amount of a chemical solution to be injected is controlled to change in a wide range in response to a change in the flow rate of a fluid to be processed. Another object of the present invention is to provide a low-cost, easy, and accurate chemical liquid injection control device capable of accurately detecting an abnormality, and a chemical liquid injection device including the chemical liquid injection control device.
[0006]
[Means for Solving the Problems]
In order to achieve the above-described object, the chemical liquid injection control device according to the present invention is characterized in that, as described in claim 1 of the claims section, the fluid to be processed flowing through the transport pipeline or the chemical liquid mixing tank is used. A target injection amount calculating means for calculating and deriving a target injection amount of the chemical based on the detected flow rate of the fluid to be processed and the target chemical concentration with respect to a chemical injection mechanism including a chemical injection pump for injecting a chemical from a chemical tank. A chemical liquid injection control device comprising injection amount control means for outputting a drive control signal to the chemical liquid injection pump so that a detected chemical liquid injection amount of the chemical liquid injected by the chemical liquid injection pump becomes the target injection amount, A monitoring means for self-diagnosing the operation state of the apparatus based on the drive control signal and the detected chemical liquid injection amount is provided.
[0007]
The injection amount control means outputs a drive control signal to the chemical injection pump by feedback control so that the detected chemical injection amount of the chemical injected by the chemical injection pump becomes the target injection amount obtained by the target injection amount calculating means. Therefore, even when the amount of the chemical solution to be injected changes in a wide range in response to a change in the flow rate of the fluid to be processed, the amount of the injected chemical solution can be accurately controlled. Then, the monitoring means self-diagnoses the operation state of the apparatus based on the drive control signal and the detected liquid injection amount, so that there is no need to install a separate sensor for diagnosis in the system and the self-diagnosis can be performed at low cost. is there.
[0008]
In the second feature configuration, as described in claim 2 of the same column, in addition to the first feature configuration, the monitoring unit stores, as table data, a permissible range of a chemical solution injection amount with respect to a preset drive control signal. Storage means for performing the diagnosis, and a notification means for notifying the result of the diagnosis, and a self-check based on whether or not the relationship between the actual drive control signal for the liquid injection pump and the detected liquid injection amount falls within the allowable range defined by the table data The present invention is characterized in that a predetermined signal is output to a diagnosis unit for performing a diagnosis and the notification unit based on a result of the diagnosis unit.
[0009]
In performing the self-diagnosis, the diagnosis means makes a simple determination as to whether or not the relationship between the actual drive control signal for the chemical injection pump and the detected chemical injection amount is within the allowable range based on the table data stored in the storage means. This may be performed, and a predetermined signal is output to the notification means based on the result, so that the operator does not need to constantly monitor the operation state of the device.
[0010]
In the third feature configuration, as described in claim 3 of the same column, in addition to the second feature configuration, the table data is divided into an operation allowable region and an abnormal operation region, and the diagnosis unit performs the chemical injection. When the relationship between the actual drive control signal for the pump and the detected chemical liquid injection amount belongs to the abnormal operation region, a stop signal is output to the injection amount control means, and an abnormality occurrence signal is output to the notification means. is there.
[0011]
The diagnosing unit outputs a stop signal to the injection amount control unit to stop the device when the diagnosis unit determines that the relationship between the actual drive control signal for the liquid injection pump and the detected injection amount belongs to the abnormal operation region. This makes it possible to avoid aggravation of the situation, and to output an abnormality occurrence signal to the notification means, so that the worker can wait for an appropriate response.
[0012]
The fourth feature configuration is, as described in claim 4 of the same column, in addition to the third feature configuration, the abnormal operation region is divided into a plurality of regions corresponding to the abnormality occurrence region, and Another point is that a different abnormality occurrence signal is output to the notification means based on whether or not the abnormality is in the abnormality occurrence area.
[0013]
Since it is possible to determine what the abnormal state of the system is from the relationship between the drive control signal and the amount of injected chemical solution, it is possible to quickly formulate a countermeasure according to the notification result by the notification means. It is.
[0014]
The fifth characteristic configuration, as described in claim 5 in the same column, in addition to any one of the second to fourth characteristic configurations, the operation allowable region is further divided into a normal operation region and an inspection request region, The diagnostic means outputs an inspection request signal to the notifying means when the relationship between the actual drive control signal for the chemical liquid injection pump and the detected chemical liquid injection amount belongs to the inspection request operation area.
[0015]
There is no urgent problem if the operating state of the system is within the allowable operation range. However, depending on the degree of durability deterioration of the system, the time when maintenance is required may be approaching. Depending on the operating state of the system, regular maintenance may not be possible. In view of this, if the table data is partitioned on the table data with an inspection request area in which a tendency such as a blockage of a chemical solution injection channel can be grasped based on the relationship between the drive control signal and the detected chemical solution injection amount, the inspection can be performed. By performing a check when notified by the notification means based on the request signal, it is possible to appropriately cope with the situation before serious damage is caused.
[0016]
The sixth characteristic configuration is, as described in claim 6 in the same column, in addition to any one of the second to fifth characteristic configurations, when a drive control signal for the chemical liquid injection pump is changed within a predetermined range. Calibration operation control means for generating the table data based on the detected liquid injection amount and storing the table data in the storage means is provided.
[0017]
The table data described above needs to be set individually depending on the system because various factors such as the diameter of the pipeline and the degree of pressure loss are involved. Therefore, it becomes possible to generate accurate table data by changing the drive control signal for the chemical liquid injection pump within a predetermined range and driving the same by the calibration operation control means, and detecting the amount of chemical liquid injected from the chemical liquid injection pump. It is. Here, the operation of the calibration operation control means can be performed after the system is installed and before the durability is deteriorated, or at the time after maintenance is completed, but the operation is performed at an initial time when the device is installed. Preferably.
[0018]
The seventh characteristic configuration is, in addition to any one of the second to sixth characteristic configurations, as set forth in claim 7 in the same column, wherein the diagnostic means further includes a predetermined remaining amount of the detected chemical liquid in the chemical liquid tank. When it becomes, it is preferable that a stop signal is output to the injection amount control means and a chemical solution decrease signal is output to the notification means.
[0019]
The characteristic configuration of the drug solution injection device according to the present invention includes a drug solution tank, a drug solution injection pipe line for injecting a drug solution into a fluid to be processed flowing through a transport pipeline or a drug solution mixing tank, and a drug solution injection channel from the drug solution tank. A chemical solution injection mechanism having a chemical solution injection pump for injecting a chemical solution, and a chemical solution injection control device according to any one of the first to seventh chemical solution injection control devices described above. It is possible to provide a highly reliable liquid injector.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to an example of a chemical liquid injector for injecting sodium hypochlorite (NaClO) as a drug into a water distribution pipe of a water supply system.
[0021]
As shown in FIG. 1, the drug solution injection device includes a drug solution tank 2 filled with a sodium hypochlorite solution as a drug solution, a first supply pipe 3 for transporting the drug solution from the drug solution tank 2 to the drug solution injection pump 5, A second supply line 4 as a chemical liquid injection line for injecting the sodium hypochlorite solution into tap water 1a as a fluid to be treated flowing through a water distribution tube 1 as a conveying line; A chemical solution injection mechanism 6 including a chemical solution injection pump 5 for sucking a chemical solution through the first supply line 3 and injecting the chemical solution from the second supply line 4 into tap water; And a chemical liquid injection control device 7 for controlling the injection of the chemical liquid to maintain the residual chlorine concentration of tap water in the water distribution pipe 1 within a predetermined range.
[0022]
The first supply line 3 is provided with a valve mechanism 3a for permitting / disabling the flow of the chemical solution and a strainer 3b for removing foreign matters. A pressure valve mechanism 4a is provided, and a chemical liquid flow meter 4b for measuring the injection amount of the chemical liquid is provided upstream of the pressure valve mechanism 4a, and a connection between the second supply pipe 4 and the water distribution pipe 1 Flow meters 1b for measuring the flow rate of tap water are provided on the upstream side of the flow direction of tap water flowing therethrough. Here, an electromagnetic flow meter is used for each flow meter, but a flow meter of an optimal type may be used according to the characteristics of the fluid to be processed.
[0023]
The chemical liquid injection pump 5 is constituted by an internal gear pump provided with an inverter motor, and a capacitance type level switch 5b is provided on a gas vent pipe 5a for discharging a vaporized gas (chlorine gas) of a chemical liquid in a pump chamber. In addition, the pump can be prevented from being idle due to a decrease in the chemical supplied from the chemical liquid tank 2 and the like.
[0024]
The chemical liquid injection control device 7 injects by the chemical liquid injection pump 5 with a target injection amount calculating means 8 for calculating and deriving a target liquid injection amount SV based on the detected flow rate of tap water and the target chemical concentration by the flow meter 1b. The drive frequency signal corresponding to the inverter 10 which is the drive circuit of the chemical solution injection pump 5 was adjusted so that the chemical solution injection amount PV of the chemical solution detected by the chemical solution flow meter 4b became the target injection amount SV. An injection amount control means 9 for outputting a drive control signal MV, and a monitoring means 11 for self-diagnosing the operation state of the apparatus based on the drive control signal MV and the detected chemical liquid injection amount PV are provided.
[0025]
Here, the target chemical concentration is a value set based on the residual chlorine concentration measured by a chemical concentration sensor (not shown) installed downstream of the water distribution pipe into which the chemical is injected. Usage of tap water supplied from the distribution pipe after it has been done, that is, the residual chlorine concentration value in the distribution pipe varies variously depending on the residence time of the water in the distribution pipe, but the value falls within a predetermined allowable range. Then, the target chemical concentration is determined. For example, when the water usage is relatively large and the residual chlorine concentration is maintained at a high level, the target chemical concentration is set to a lower value.When the water usage is low and the water stays in the water distribution pipe for a long time, the residual chlorine concentration becomes low. Since it is low, the target chemical concentration is set high so that the value is maintained within the allowable range. If the tap water remaining in the drainage pipe network is used at the end and it is clear that the residual chlorine concentration is within a predetermined allowable range, the target chemical solution concentration may be a fixed value.
[0026]
The monitoring unit 11 includes a storage unit 11a that stores, as table data, a permissible range of the chemical injection amount PV with respect to a preset drive control signal MV, an informing unit 11b that notifies a diagnosis result, and an actual Diagnostic means 11c for performing a self-diagnosis based on whether or not the relationship between the drive control signal MV and the detected chemical liquid injection amount PV falls within an allowable range defined by the table data. , A predetermined signal is output to the notifying means 11b, and the notifying means 11b having received the signal executes a predetermined notifying operation to the operation monitoring staff.
[0027]
The chemical liquid injection control device 7 further generates the table data based on the detected chemical liquid injection amount PV when the drive control signal MV for the chemical liquid injection pump 5 is changed within a predetermined range, and stores the table data in the storage unit 11a. Calibration operation control means 12 for storing is provided. More specifically, the calibration operation control means 12 is configured to operate as a function of the injection amount control means 9 by switching a mode switch (not shown). When the operation is performed, the operation mode is the calibration operation mode, and the drive control signal MV corresponding to the drive frequency signal for the inverter 10 is increased at a predetermined time interval, and at a predetermined operation amount interval from the off state so as to increase the chemical solution supply amount, The detected chemical injection amount PV at that time is input as a sampling value, and a value obtained by adding a predetermined variation allowable range to the input value is stored in the storage unit 11a as table data indicating the allowable range of the chemical injection amount with respect to the drive control signal. Is stored.
[0028]
As shown in FIG. 2, the table data is a two-dimensional coordinate system in which the X-axis is a drive control signal MV and the Y-axis is a detected chemical injection amount PV. It is divided into regions (c and d portions in the figure), and the allowable operation region is a normal operation region (a portion in the diagram) having a width of 10% above and below the sampling value and a 10% to 15% range from 10% above and below the sampling value. The width is an inspection request area (part b in the figure), and the abnormal operation area is an area above the operation allowable area (part c in the figure) and an area below the operation allowable area (part d in the figure). Has been split.
[0029]
The normal operation area indicates a state in which there is no problem in the operation of the device, and the inspection request area indicates a state in which there is no problem in the operation of the device, but it is judged that an inspection is necessary because it may cause an abnormality. The abnormal operation region is a region in which the amount of the liquid medicine injection is abnormally large with respect to the output value of the drive control signal MV, and the second supply line 4 is damaged or damaged in the line downstream of the liquid medicine flow meter 4b. This indicates a state in which it is determined that a failure such as breakage of the pressure valve 4a has occurred. The lower abnormal operation region is a region in which the amount of the liquid injection is abnormally reduced with respect to the output value of the drive control signal MV. Abnormality of the inverter 10, disconnection, breakage of the second supply line 4 on the upstream side of the chemical flow meter 4b, adhesion of scale on the first supply line 3 or the second supply line 4, Due to stagnation of bubbles generated from air, strainer Shows a state in which it is determined that the failure of clogging of b.
[0030]
The diagnosis unit 11c determines that the relationship between the actual drive control signal MV for the chemical liquid injection pump 5 and the detected chemical liquid injection amount PV belongs to the abnormal operation area (parts c and d in the figure) based on the table data. At this time, a stop signal is output to the injection amount control means 9 and a different abnormality occurrence signal is output to the notification means 11b based on which abnormality occurrence area is abnormal. The notifying unit 11b sounds an alarm to the operation monitoring member based on the input abnormality occurrence signal, and a monitor (not shown) attached to the notification unit 11b displays an abnormal state corresponding to the abnormality occurrence signal, that is, the abnormal state described above. The site where the failure is determined is displayed as diagnostic information.
[0031]
The diagnosis unit 11c further outputs an inspection request signal to the notification unit 11b when the relationship between the actual drive control signal MV for the chemical injection pump and the detected chemical injection amount PV belongs to the inspection request operation region. The notification means 11b displays an inspection request message on an attached monitor. Here, when it is determined that the inspection area is in the inspection request area, the diagnosis unit 11c determines which side of the normal operation area is the inspection area, and the notification unit 11b determines which area is the inspection area. By outputting an identifiable inspection request signal, the notifying means 11b can display an accurate message including a part requiring inspection.
[0032]
The diagnostic means 11c is further provided with a signal for detecting the decrease in the amount of the chemical, which is the output signal of the level switch 5b as a remaining amount of the chemical for measuring the remaining amount of the chemical in the chemical tank 2. A stop signal is output to the amount control means 9 and a chemical liquid decrease signal is output to the notification means 11b. On the other hand, the notifying unit 11b sounds an alarm and displays the reduced amount of the chemical solution on the monitor.
[0033]
Hereinafter, another embodiment will be described.
[0034]
In the above-described embodiment, an example has been described in which the calibration operation unit 12 is set to the calibration operation mode at the initial stage when the liquid injector is installed. However, the calibration operation mode is not limited to the one performed at the initial stage of installation. Alternatively, the inspection may be performed at the time of completion of the periodic inspection work, or may be performed at the time of completion of repair after some trouble has occurred.
[0035]
In the above-described embodiment, the operation allowable area indicated by the table data is a normal operation area having a width of 10% above and below the sampling value (part a in the drawing), and an inspection area having a width of 10% to 15% above and below the sampling value. The abnormal operation area is divided into an upper area (part c in the figure) of the operation allowable area and a lower area (part d in the figure) of the operation allowable area. However, the range of the normal operation region and the range of the inspection request region are not limited thereto, and may be set as appropriate. Further, the table data may be simple data for simply determining whether or not the operation is in the normal operation range. The intermediate data not specified by the table data may be obtained by a linear interpolation method using the data on both sides nearest to the data.
[0036]
In the above-described embodiment, the chemical liquid injection mechanism including the chemical liquid injection pump for injecting the chemical liquid from the chemical liquid tank into the liquid to be processed flowing through the transport pipeline has been described. The same applies to a drug solution injection mechanism provided with a drug solution injection pump for injecting a drug solution from a drug solution tank.
[0037]
In the above-described embodiment, the chemical liquid injection device for injecting sodium hypochlorite (NaClO) as a chemical into the water pipe of the water supply system has been described as an example. However, the chemical liquid injection control device and the chemical liquid injection device according to the present invention are not limited thereto. However, it does not control the injection amount of chemicals such as scale inhibitors, oxygen scavengers, and condensate treatment agents to the feedwater flowing through the boiler feedwater pipes. It goes without saying that the present invention can be applied to a chemical liquid injection control device that controls the injection amount of a chemical liquid such as a predetermined flocculant or a ph regulator into the processing fluid, and a chemical liquid injection device provided with the chemical liquid injection control device.
[0038]
【The invention's effect】
As described above, according to the present invention, even when the amount of the chemical solution to be injected is controlled to change in a wide range in response to a change in the flow rate of the fluid to be processed, it is inexpensive, easy, and It has become possible to provide a chemical injection control device capable of accurately detecting an abnormality and a chemical injection device provided with the chemical injection control device.
[Brief description of the drawings]
FIG. 1 is a block diagram of a chemical solution injection device according to the present invention; FIG.
1: Conveyance pipeline (water pipe)
1a: Fluid to be treated (tap water)
2: Chemical solution tank 3: First supply line 4: Chemical solution injection line (second supply line)
5: Chemical solution injection pump 6: Chemical solution injection mechanism 7: Chemical solution injection control device 8: Target injection amount calculating means 9: Injection amount control means 10: Inverter 11: Monitoring means 11a: Storage means 11b: Notification means 11c: Diagnosis means 12: Calibration operation control means

Claims (8)

Based on the detected flow rate and the target chemical concentration of the fluid to be processed, a chemical injection mechanism having a chemical injection pump for injecting a chemical from the chemical tank into the fluid to be processed flowing through the transport pipeline or the chemical mixing tank. A target injection amount calculating means for calculating and deriving a target injection amount of the liquid medicine; and a drive control signal for the liquid injection pump so that the detected liquid injection amount of the liquid injected by the liquid injection pump becomes the target injection amount. A drug solution injection control device provided with an injection amount control means,
A chemical injection control device provided with monitoring means for self-diagnosing the operation state of the device based on the drive control signal and the detected chemical injection amount. The monitoring means includes storage means for storing, as table data, a permissible range of the liquid injection amount with respect to a preset drive control signal, notification means for notifying a diagnosis result, and detection of an actual drive control signal for the liquid injection pump. Diagnostic means for performing a self-diagnosis based on whether or not the relationship between the amounts of injected chemicals falls within an allowable range defined by the table data; and outputting a predetermined signal to the notification means based on a result of the diagnostic means. The chemical liquid injection control device according to claim 1. The table data is divided into an operation allowable region and an abnormal operation region, and the diagnostic means determines that the injection amount is smaller when the relationship between the actual drive control signal for the chemical injection pump and the detected chemical injection amount belongs to the abnormal operation region. 3. The chemical liquid injection control device according to claim 2, wherein a stop signal is output to the control means and an abnormality occurrence signal is output to the notification means. The abnormal operation region is divided into a plurality of regions corresponding to the abnormality occurrence region, and the diagnosis unit outputs a different abnormality occurrence signal to the notification unit based on which abnormality occurrence region is abnormal. 3. The chemical injection control device according to 3. The operation allowable region is further divided into a normal operation region and an inspection request region, and the diagnostic means notifies the user when the relationship between the actual drive control signal for the chemical liquid injection pump and the detected chemical liquid injection amount belongs to the inspection request operation region. 5. The chemical liquid injection control device according to claim 2, wherein an inspection request signal is output to the means. 6. A calibration operation control means for generating the table data based on a detected chemical liquid injection amount when a drive control signal for the chemical liquid injection pump is changed within a predetermined range and storing the table data in the storage means is provided. The chemical liquid injection control device according to any one of the above. The diagnostic means further outputs a stop signal to the injection amount control means and outputs a chemical decrease signal to the notification means when the detected remaining amount of the chemical liquid in the chemical tank reaches a predetermined remaining amount. 7. The chemical liquid injection control device according to any one of 2 to 6. A chemical solution including a chemical solution tank, a chemical solution injection pipeline for injecting a chemical solution into a fluid to be processed flowing through a transport pipeline or a chemical solution mixing tank, and a chemical solution injection pump for injecting a chemical solution from the chemical solution tank to the chemical solution injection pipeline. A drug solution injection device comprising an injection mechanism and the drug solution injection control device according to any one of claims 1 to 7.

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