JP5736607B2 - Chemical injection control method and chemical injection control device - Google Patents

Description

  The present invention relates to a chemical injection control method and a chemical injection control device for a water treatment chemical to circulating cooling water in an open circulating cooling water system.

  In a so-called open circulating cooling water system, air is forced into the cooling tower and the air is brought into gas-liquid contact with the circulating cooling water sent from a heat exchanger such as a refrigerator. Cooling is performed by evaporating a part of the cooling water. Since the circulating cooling water is circulated between the heat exchanger and the cooling tower, corrosion, scale, slime and other obstacles are likely to occur, and various water treatment chemicals have been added to prevent these obstacles. Used above.

  In order to maximize the effects of water treatment chemicals, it is necessary to manage the water treatment chemicals at a constant concentration or higher at all times in the circulating cooling water. For this purpose, water treatment chemicals are injected into the circulating cooling water by various methods. To do (medicine) is done. For example, in the chemical injection control method of Patent Document 1 below, the load of the cooling tower is obtained from the temperature difference between the circulating cooling water entering the cooling tower and the circulating cooling water exiting the cooling tower, and based on the obtained load. Controlling the dose of water treatment chemicals has been carried out.

JP 2009-30936 A

  However, in the above-described conventional chemical injection control method, in the case of the evaporation loss of the circulating cooling water, the blow water amount is calculated based on the obtained load, and the chemical injection amount is obtained based on the blow water amount and scattered. In the case of loss, the chemical injection amount is obtained from the total amount of the scattering loss amount and the blow water amount and the set chemical concentration. For this reason, there are problems that the control related to the chemical injection of the water treatment chemical is complicated and the entire system is expensive. Further, in the conventional general control, the medicine injection operation is a timer control, and since the blow operation and the medicine injection operation are not interlocked, it is difficult to maintain an effective medicine concentration. Thus, for example, there is known a method that directly measures the drug concentration in the circulating cooling water to control the drug injection, but in this case, the entire system becomes expensive.

  The present invention eliminates the problems caused by the prior art described above, and a chemical injection control method and a medicine capable of maintaining the chemical concentration in the circulating cooling water in an effective state without complicated control that can be configured at low cost. Note To provide a control device.

  The chemical injection control method according to the present invention is a chemical injection control method for injecting a water treatment chemical into the circulating cooling water of an open circulating cooling water system, wherein the circulating cooling water is blown during the circulating cooling water blowing operation in a cooling tower. Control is performed so as not to perform the medicine pouring operation of the water treatment chemical into the water.

  For example, after the blow operation is performed, the circulation operation is controlled so as to perform the medicine injection operation proportional to the opening time of the blow valve, or when the blow valve is not operated for a predetermined time, for example, You may control to perform the auxiliary | assistant medicine injection | pouring operation | movement which inject | pours the predetermined amount of said water treatment chemical | medical agents into cooling water.

  A chemical injection control device according to the present invention is a chemical injection control device that controls injection of a water treatment chemical into circulating cooling water in an open circulating cooling water system, and controls blow valve operation control that controls the operation of a blow valve in a cooling tower. Means and a chemical injection control means for controlling a chemical injection device for injecting the water treatment chemical into the circulating cooling water, the chemical injection control means based on the signal from the blow valve operation control means, Control is performed so that the medicine injection device does not perform the medicine injection operation during the operation of blowing the circulating cooling water.

  The chemical injection control means controls the chemical injection device to perform the chemical injection operation in proportion to the opening time of the blow valve after the blow operation is performed, for example, When the valve has not been operated for a predetermined time, it is controlled to cause the chemical injection device to perform an auxiliary chemical injection operation for injecting a predetermined amount of the water treatment chemical into the circulating cooling water.

  According to the present invention, the chemical concentration of the circulating cooling water can be maintained in an effective state without complicated control that can be configured at low cost.

It is a distribution diagram showing cooling equipment of an open circulation cooling water system to which a medicine injection control method and medicine injection control device concerning one embodiment of the present invention are applied. It is a block diagram which shows the internal structure of the same medicine injection control apparatus. It is a flowchart which shows an example of the chemical injection control processing procedure by the chemical injection control method. It is a wave form diagram which shows operation | movement of the cooling equipment.

  Embodiments of a chemical injection control method and a chemical injection control device according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a system diagram showing a cooling facility of an open circulating cooling water system to which a chemical injection control method and a chemical injection control device according to an embodiment of the present invention are applied, and FIG. 2 shows an internal configuration of the chemical injection control device. It is a block diagram. As shown in FIG. 1, the cooling system of the open circulation cooling water system is configured to include, for example, a cooling tower 1, a refrigerator 2, a circulation pump 3, a control device 10, and a chemical injection device 20.

  The circulating cooling water heated by the refrigerator 2 is sprinkled from the sprinkler 4 in the cooling tower 1 and collected in the lower water tank 6. The circulating cooling water accumulated in the lower water tank 6 is circulated to the refrigerator 2 by the circulation pump 3.

  This circulating cooling water is lost due to evaporation and scattering while being circulated between the refrigerator 2 and the cooling tower 1. For this reason, an amount of makeup water corresponding to the amount of splash loss including the evaporation loss amount of the circulating cooling water in the cooling tower 1 and the blow water amount accompanying the blow operation by the operation of the blow valve 7 passes through the replenishment valve 8 to the 1 is supplied.

  Note that the circulating cooling water accumulated in the lower water tank 6 is discharged by operating the discharge valve 9 while the overflow is discharged to the outside through the discharge pipe 9a so that the water surface in the lower water tank 6 is constant. May be discharged to the outside. The makeup water supplied into the cooling tower 1 is supplied so that the water surface of the lower water tank 6 is kept constant. For this reason, even if the evaporation loss amount and the scattering loss amount fluctuate or the blow operation is performed, the amount of the circulating cooling water in the cooling facility is kept substantially constant.

  Such water level control in the cooling tower 1 can be automatically performed by using a ball tap valve or the like as the replenishment valve 8, for example, and the blow operation is appropriately performed when the quality of the circulating cooling water is deteriorated. Whether or not the quality of the circulating cooling water has deteriorated can be determined by measuring the electrical conductivity of the circulating cooling water, as is known in the art.

  Circulating cooling water is pre-added with various water treatment chemicals to prevent the occurrence of failures such as corrosion, scale, and slime in the equipment, but circulating cooling water repeats such replenishment and loss. The water treatment chemical is appropriately injected from the chemical liquid tank 22 of the chemical injection device 20 by the chemical injection pump 21 so that the chemical concentration in the circulating cooling water can be maintained. This prevents the occurrence of troubles such as corrosion, scale, slime and the like.

  On the other hand, the control device 10 that controls the operation of these cooling facilities controls, for example, the entire cooling facility, and includes a blow operation control unit 11, a chemical injection operation control unit 12, and an electrical conductivity measurement unit 13 therein. It is configured.

  The blow operation control unit 11 controls the operation of the blow valve 7 based on information from the conductivity measurement unit 13 described later.

  The medicinal operation control unit 12 controls the entire medicinal injection device 20 and controls the operation of the medicinal pump 21 based on the information related to the blow operation from the blow operation control unit 11 to perform water treatment from the medicinal solution tank 22. The medicine injection device 20 is caused to perform a medicine injection operation for injecting the medicine into the circulating cooling water. Details of the drug injection operation controlled by the drug injection operation control unit 12 will be described later.

  The conductivity measuring unit 13 determines the conductivity of the circulating cooling water based on information from, for example, a throw-type conductivity sensor 15a attached to the lower water tank 6 or a flow-type conductivity sensor 15b provided in the circulation line. taking measurement.

  The chemical injection control in the cooling equipment configured as described above is performed, for example, as follows. FIG. 3 is a flowchart showing an example of a chemical injection control processing procedure by the chemical injection control method according to the embodiment of the present invention, and FIG. 4 is a waveform diagram showing the operation of the cooling facility. The chemical injection control process by the chemical injection control method according to the present embodiment is characterized by the following points.

  That is, the medicine injection operation generally performed by a timer is (1) not performed during the blow operation, (2) performed in proportion to the time when the blow valve 7 is opened after the blow operation is performed, (3) It is characterized in that when the blow valve 7 has not been operated for a predetermined period of time, a supplementary amount of water treatment chemical is injected.

  First, the electrical conductivity measurement unit 13 measures the electrical conductivity of the circulating cooling water, and the blow operation control unit 11 increases the electrical conductivity based on the information from the electrical conductivity measurement unit 13 as shown in FIG. It is then determined whether or not the control start point has been reached (step S100). If it is determined that the electrical conductivity is equal to or higher than the control start point (Y in step S100), the blow operation control unit 11 controls the operation of the blow valve 7 to perform the blow operation (step S102).

  That is, as is well known, by utilizing the property that the electrical conductivity increases when the water quality of the circulating cooling water deteriorates, the blow operation control unit 12 allows the blow operation control unit 12 to blow when the electrical conductivity exceeds a predetermined control start point. The valve 7 is opened and a blow operation is performed. When the blow operation is performed in this way, the quality of the circulating cooling water is improved and the electrical conductivity is lowered.

  Then, the blow operation control unit 11 determines whether or not the conductivity has become lower than the control stop point based on the information from the conductivity measuring unit 13 (step S104). When it is determined that the electrical conductivity is equal to or lower than the control stop point (Y in Step S104), the blow operation control unit 11 controls the operation of the blow valve 7 and stops the blow operation (Step S106).

  That is, as is well known, when the water quality of the circulating cooling water is improved from the deteriorated state, the conductivity is lowered. Therefore, the blow operation control unit 11 causes the blow valve 7 when the conductivity falls below a predetermined control stop point. To stop the blow operation. When the blow operation is stopped in this way, the quality of the circulating cooling water begins to deteriorate again, and the conductivity increases.

  As described above, when the blow operation is performed by determining the level of the electrical conductivity of the circulating cooling water in the cooling facility, the water treatment chemical injection operation is performed independently of the blow operation as in the conventional chemical injection control method. If it is carried out, loss of water treatment chemicals will occur, or the chemical concentration in the circulating cooling water will increase excessively, which is not preferable.

  Therefore, in the chemical injection control process according to the present embodiment, the chemical injection operation is not performed in synchronization with the blow operation as described in (1) above (that is, the chemical injection operation is not performed during the blow operation). . Specifically, based on information from the blow operation control unit 11, when the blow operation is stopped (step S106), the medicinal operation control unit 12 operates the medicinal pump 21 as shown in FIG. Then, a medicine injection operation is performed (step S108).

  The chemical injection operation at this time may be performed by injecting a predetermined amount of the water treatment chemical, or as shown in the above (2), the chemical injection amount or chemical injection is proportional to the time when the blow valve 7 is opened. You may make it decide at time. When the chemical injection operation is performed, as shown in FIG. 4, the chemical concentration in the circulating cooling water increases.

  Then, based on the information from the blow operation control unit 11, the medicine injection operation control unit 12 determines whether or not the time during which the blow valve 7 is not operating and the blow operation is stopped is longer than the predetermined time T (predetermined) It is determined whether or not it is equal to or longer than time T (step S110). As shown in FIG. 4, for example, when the blow operation is not performed, it corresponds to the case where the circulation operation is performed at a low load of the cooling facility, and when the blow operation is frequently performed, This corresponds to the case where high-load operation is performed.

  If it is determined that the time during which the blow operation is stopped is longer than the predetermined time T (Y in step S110), the drug concentration in the circulating cooling water continues to decrease, resulting in an adverse effect. Performs an auxiliary medicine injection operation (auxiliary medicine injection operation) so as to inject a predetermined amount of the water treatment chemical into the circulating cooling water as in (3) above (step S112), and the process proceeds to step S100. repeat. Note that the amount and time of the auxiliary drug injection operation are appropriately set according to various conditions of the cooling facility. This auxiliary medicine operation may be the same amount or time as the above-mentioned medicine operation, or may be a different amount or time.

  If it is determined in step S100 that the conductivity is not equal to or higher than the control start point (N in step S100), the process proceeds to step S110 and the time during which the blowing operation is stopped is longer than the predetermined time T. It is determined whether or not. If it is determined in step S104 that the conductivity is not equal to or lower than the control stop point (N in step S104), the process proceeds to step S102 and the blowing operation is continued. Further, when it is determined that the time during which the blow operation is stopped is shorter than the predetermined time T (less than the predetermined time T) (N in step S110), the process proceeds to step S100 and the process is repeated.

  As a result of performing such chemical injection control processing, as shown in FIG. 4, the chemical concentration in the circulating cooling water is such that the water treatment chemical is in an effective state regardless of the high load operation or low load operation of the cooling facility. It became possible to maintain. That is, according to the chemical injection control process according to the present embodiment, since the chemical injection operation is performed as in (1) to (3) above, the water treatment chemical is excessively injected compared to the chemical injection operation by the timer operation. In addition, since a separate flow meter for measuring the flow rate of blow water is unnecessary and the loss of the water treatment chemical is reduced, the cost can be reduced and the apparatus can be configured at low cost. Of course, it goes without saying that the effect of the present embodiment can be achieved even in a system in which a flow meter is already installed.

  In addition, based on the information regarding the blow operation from the blow operation control unit 11, the drug injection operation control unit 14 performs control so that the drug injection operation is performed after the blow operation or when the blow operation stop period is longer than a predetermined time. Further, the chemical concentration of the water treatment chemical for the circulating cooling water can be maintained in an effective state without performing complicated arithmetic processing and control.

DESCRIPTION OF SYMBOLS 1 Cooling tower 2 Refrigerator 3 Circulation pump 4 Sprinkling device 6 Lower water tank 7 Blow valve 8 Replenishment valve 9 Drain valve 9a Drain pipe 10 Controller 11 Blow operation control unit 12 Chemical injection operation control unit 13 Conductivity measurement unit 15a Conductivity sensor 15b Conductivity sensor 20 Chemical injection device 21 Chemical injection pump 22 Chemical solution tank

Claims (4)

A chemical injection control method for injecting a water treatment chemical into circulating cooling water in an open circulating cooling water system,
During the blowing operation of the circulating cooling water by the operation control of the blow valve in the cooling tower, and controlling so as not to perform the chemical injection operation of the water treatment chemical to the circulating cooling water,
The blow valve is controlled not to operate for a predetermined time during a high load operation, and to perform an auxiliary medicine injection operation for injecting a predetermined amount of the water treatment chemical into the circulating cooling water during a low load circulation operation. A chemical injection control method characterized. The method according to claim 1, wherein after the blow operation is performed, control is performed so as to perform the drug injection operation in proportion to a time during which the blow valve is opened. A chemical injection control device that controls injection of a water treatment chemical into circulating cooling water in an open circulating cooling water system,
Blow valve operation control means for controlling the operation of the blow valve in the cooling tower;
A chemical injection control means for controlling a chemical injection device for injecting the water treatment chemical into the circulating cooling water,
The medicine injection control means includes
Based on the signal from the blow valve operation control means, during the blow operation of the circulating cooling water, the medicine injection device is controlled not to perform the medicine injection operation, and the blow valve is operated at the time of high load operation. Control to cause the chemical injection device to perform an auxiliary chemical injection operation for injecting a predetermined amount of the water treatment chemical into the circulating cooling water during a circulation operation at a low load that has not been operated for a predetermined time longer than a blow cycle. A chemical injection control device characterized by that. The said chemical injection control means controls the said chemical injection apparatus to perform the said chemical injection operation in proportion to the time when the said blow valve opened after the said blow operation was performed. 3. The chemical injection control device according to 3.

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