JPH06317393A - Water quality control method for circulating cooling water in cooling tower - Google Patents

Abstract

PURPOSE:To prevent the concentration shortage of a water processing agent due to splashed water from happening by replenishing the water processing agent by a predetermined quantity in response to the quantity of splashed water by predetermined time intervals during an operation separately from a proportional injection of the water processing agent in response to a blow-down quantity. CONSTITUTION:A blow-down quantity by the operation of a blow device (upside down U-shaped siphon pipe) 6 is measured, and cooling water is replenished in response to the measured blow-down quantity. At the same time, a water processing agent is injected in circulating/cooling water of a cooling tower 1 by operating a water processing agent injecting device 12. Also, separately from the proportional injection of the water processing agent in response to the blow-down quantity, the water processing agent is replenished by a predetermined quantity in response to the quantity of splashed water by predetermined time intervals during an operation to maintain the concentration of the water processing agent in the circulating/cooling water always at a desired level. By this method, a dissipated portion of the water processing agent due to the splashed water is compensated, and a concentration shortage of the water processing agent due to splashed water can be prevented from generating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water quality control method for circulating cooling water in a cooling tower equipped with a blowing device and a water treatment agent injection device.

[0002]

2. Description of the Related Art As is generally known, a cooling tower cools water by directly contacting cooling water with air to evaporate the water and cool the water by its latent heat. The cooling water and the air are in direct contact with each other. Therefore, it has features such as higher heat transfer efficiency than an air-cooled heat exchanger that simply heats the air to transfer heat, can be made compact and at low cost, and therefore various cooling towers from large to small have been proposed. It is used for freezing and air conditioning. By the way, problems that occur in the management of the cooling tower include corrosion damage, scale damage and slime damage that occur in the circulating cooling water system.In particular, in the open type circulating cooling water system, part of the circulating cooling water evaporates in the cooling tower. ,
The dissolved salts in the circulating cooling water will be concentrated in the circulating cooling water. In addition, calcium, silica, etc. existing in the form of ions in the circulating cooling water are a source of scale formation. These obstacles not only reduce the heat exchange efficiency, but also damage the refrigerator, piping, and the like. To prevent such obstacles, a blowdown and an anticorrosive agent that discharges part of the circulating water to keep the content of salt and other impurities contained in the circulating water below a certain value, to the outside of the circulating cooling water system, Drugs such as scale inhibitors are injected. Concentration control and chemical injection control of the circulating cooling water system by blowdown usually employ a method of measuring the electric conductivity of circulating water, calculating the concentration ratio of circulating water based on it, and automatically controlling the amount of blown water. On the other hand, water treatment agents such as anticorrosion agents and scale inhibitors must always maintain an appropriate concentration in circulating water.
The amount of water treatment agent required for this holding and input is determined according to the amount of blown agent, the amount of scattering loss, the amount of makeup water, etc. based on the set retention concentration of the agent, and the amount of water treatment agent set by the agent injection device is replenished. I try to inject it.

By the way, in water quality control, especially in the injection of chemicals such as anticorrosion agents and scale inhibitors, the conductivity of the circulating cooling water in the water tank in the cooling tower is periodically measured, and the input amount is determined based on the measured data. Although it is determined, when the circulating cooling water evaporates and the concentration of the drug reaches the set upper limit, the conductivity sensor senses this and starts blowing, and the concentration of the drug is less than the differential value smaller than the set upper limit. When, the blow is stopped. In the conventional method, the injection amount of the drug is set regardless of the blow amount, and the amount of the drug set by the metering injection pump is injected regardless of the concentration. Therefore, when the outside air is low, the drug concentration is high, and the outside air temperature starts to rise to reach the prescribed amount, so that a person having knowledge and experience decides the injection amount according to the time. On the other hand, when there is no such person who can manage the pump, it is general to set the pump based on around July to August when the load (evaporation amount) is large. Therefore, in Japanese Patent Application No. 3-11956, a method of directly managing the blow amount and the chemical injection amount was proposed, thereby eliminating the waste of the chemical and keeping the concentration of the water treatment agent almost constant over time. It became possible to keep it constant.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The water quality control method for circulating cooling water in a cooling tower provided with a blowing device and a water treatment agent injecting device, previously proposed in the above-mentioned patent application, includes a blowdown amount due to operation of the blowing device. The water treatment agent is supplied according to the measured blowdown amount and the water treatment agent injection device is operated to inject the water treatment agent into the circulating cooling water in the cooling tower to obtain the concentration of the water treating agent in the circulating cooling water. It consists of maintaining at the level of. As a result, as described above, the blowdown operation and the water treatment agent injection operation can be automatically performed as a series of water management operations, and the water treatment agent injection is performed in proportion to the measured operation time of the blower. Since the amount of the water treatment agent injected by the device is set, it is not necessary to inject the water treatment agent in excess, and the concentration of the water treatment agent can always be kept substantially constant. However, in the actual operation, the cooling water is circulated or loaded to circulate and evaporate, and is also scattered from the cooling tower. This amount of splashed water varies depending on the structure and shape of the cooling tower to be used, the installation location of the cooling tower, and the weather conditions (for example, strong wind down or easy exposure to strong wind). Therefore, in the case of a cooling tower in which the amount of blow is relatively large, the concentration of the water treatment agent becomes insufficient in the case of a cooling tower in which the amount of blow is relatively large. Therefore, the present invention can solve the above-mentioned problems and prevent the occurrence of insufficient concentration of the water treatment agent due to splashed water, regardless of the structure of the cooling tower, and in any operating environment, in the circulating cooling water. An object of the present invention is to provide a water quality control method for circulating cooling water in a cooling tower that can always maintain the concentration of a water treatment agent at a desired level.

[0005]

In order to achieve the above object, a method for controlling the quality of circulating cooling water in a cooling tower equipped with a blowing device and a water treatment agent injection device according to the first invention of the present invention is The blowdown amount due to the operation of the blow device is measured, cooling water is supplied according to the measured blowdown amount, and the water treatment agent injection device is operated to inject the water treatment agent into the circulating cooling water in the cooling tower. Separately from the proportional injection of the water treatment agent according to the blowdown amount, the water treatment agent is replenished at a predetermined time interval during operation at a predetermined time interval according to the amount of scattered water, and the amount of the water treatment agent in the circulating cooling water is increased. The feature is that the concentration is always maintained at a desired level. Further, in the water quality control method for circulating cooling water in a cooling tower according to the second aspect of the present invention, the blowdown amount due to the operation of the blower device is measured, and the cooling water is replenished according to the measured blowdown amount and the water is supplied. The treatment agent injection device is operated to inject the water treatment agent into the circulating cooling water in the cooling tower, and the conductivity of the cooling water during operation is independent of the proportional injection of the water treatment agent according to the blowdown amount. When the conductivity of the water is higher than the initial injection, the water treatment agent is replenished at a predetermined time interval at a predetermined amount according to the amount of scattered water to maintain the concentration of the water treatment agent in the circulating cooling water at a desired level at all times. It is characterized by that.

[0006]

In the method according to the first aspect of the present invention, the water treatment agent is adjusted at a predetermined time interval during operation separately from the proportional injection of the water treatment agent depending on the blowdown amount according to the amount of the splashed water. By replenishing the water treatment agent in a predetermined amount, the amount of the water treatment agent dissipated by the splashed water is compensated, and the concentration of the water treatment agent in the circulating cooling water can be reliably maintained at a desired level. Further, in the method according to the second aspect of the present invention, the replenishment of the water treatment agent to the splashed water is carried out only when the conductivity of the cooling water is higher than the conductivity at the time of the initial injection of the water treatment agent. The concentration of the water treatment agent in the cooling water can be more accurately maintained at a desired level.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an example of a cooling tower and a water management apparatus for carrying out the method of the present invention. Reference numeral 1 is a cooling tower, and in this cooling tower 1, cooling water circulation pipe lines 2 and 3 and a water supply pipe are provided. Four
Are connected. Further, an overflow pipe 5 is arranged in the lower water tank of the cooling tower 1, and an inverted U-shaped siphon pipe 6 which constitutes a blower is installed across the upper end of the overflow pipe 5, and one end of the siphon pipe 6 is attached. Is a water supply means 7 including a pump for sending the cooling water in the lower water tank to the siphon pipe 6 to cause the siphon phenomenon.
Is attached, and the other end of the siphon pipe 6 extends into the overflow pipe 5. An air supply pipe 8 for supplying air to stop the siphon phenomenon communicates with the bent top of the siphon pipe 6, and an opening / closing valve 9 of an appropriate type is attached to the air supply pipe 8. The on-off valve 9 in the water supply means 7 and the air supply pipe 8 is connected to the blow operation control device 10 and is configured to control the blow operation by the siphon pipe 6. Reference numeral 11 is a detector for detecting the conductivity of the cooling water, and a signal representing the conductivity detected by the detector 11 is supplied to the blow operation control device 10. Reference numeral 12 is a water treatment agent injection device for introducing a water treatment agent such as an anticorrosive agent or a scale inhibitor into the cooling water, and its operation is controlled by the blow operation control device 10. Further, 13 is the duration of the siphon phenomenon from the start of the operation of the water supply means 7 to the opening of the open / close valve 9, that is, the blow time, in response to the operation of the water supply means 7 and the opening / closing valve 9 of the air supply pipe 8 in the blower. This is a timer device for setting the blow time to be measured.
The blow time signal measured by is sent to the blow operation control device 10, and the water treatment agent injection device is proportional to the blow time measured.
Used to control 12 movements. Further, in FIG. 1, reference numeral 14 is a splash replenishment operation control device for the water treatment agent, and the splash replenishment operation control device 14 is supplied with a signal representing the conductivity detected by the detector 11. And the scattering supplement operation control device 14
Is only when the conductivity detected by the detector 11 is higher than the conductivity at the time of the initial injection of the water treatment agent, the water treatment agent injection device 12 is operated at a predetermined time interval at a predetermined time interval, and a predetermined amount of the water treatment agent is supplied. It is configured to be supplied in cooling water. in this case,
The amount of splashed water is calculated in consideration of the shape of the cooling tower 1 to be used, the weather condition of the installation location, etc., and the frequency and amount of replenishment operation by the splash replenishment operation control device 14 can be set based on that. . Further, although not shown, the same power source is used as the power source of each element constituting the blowing device, the water treatment agent injection device, the timer device and each operation control device,
For example, a solar cell can be used, and when the solar cell is used as a driving power source, the method of the present invention can be carried out without the need for special electrical wiring work for an existing cooling tower.

The operation of actually managing the cooling water by using the apparatus configured as described above will be described. Regarding the proportional injection operation, a blow start control signal is sent from the blow operation control device 10 to the water supply means 7 of the blow device in accordance with a preset required blow amount based on the conductivity of the cooling water detected by the detector 11. Then, the water supply means 7 is operated and the cooling water in the lower water tank is sent to the siphon pipe 6 to cause the siphon phenomenon. In this case, the water supply means 7 is stopped as soon as the siphon phenomenon occurs in the siphon pipe 6. In this way, the blowing of the cooling water is started via the siphon pipe 6, and when the blowing reaches the predetermined amount, the opening / closing valve 9 of the air supply pipe 8 is opened by the blow end control signal from the blow operation control device 10, and the air supply pipe 8 is opened. Air is supplied to the inside of the siphon pipe 6 to stop the siphon phenomenon,
The blow operation ends. During this time, the timer device 13 measures the actual blow time, and the blow time is sent to the blow operation control device 10. In the blow operation control device 10, the water treatment agent injection command signal is supplied to the water treatment agent injection device 12 according to the actually measured blow time, and the water treatment agent injection device 12 is operated, whereby the blow time actually measured is set. A proportional water treatment agent is injected into the cooling water. In this case, the continuous injection amount can be set so that the concentration in the cooling water circulating the cooling water is equal to or higher than the lower limit concentration for exerting the drug effect, for example, 200 PPM. Naturally, the required amount of makeup water is supplied through the water supplement pipe 4 in accordance with the blow amount.

Next, regarding the splash replenishment operation, the splash replenishment operation control device 14 is operated only when the conductivity detected by the detector 11 is higher than the conductivity at the time of the initial injection of the water treatment agent. In the splash replenishment operation control device 14, for example, according to the amount of splash water during operation calculated in advance based on the shape of the cooling tower to be used and the weather condition of the installation location (for example, a relatively strong wind constantly blows) The amount of the water treatment agent to be replenished is set to 10%, 20%, 30%, and accordingly, the scattering replenishment operation control device 14 outputs an operation signal corresponding to the set amount of the water treatment agent to be replenished. Supply to the injection device 12. Thereby, the water treatment agent injecting device 12 replenishes the cooling water with a set amount of the water treatment agent at predetermined time intervals.

In the illustrated embodiment, the replenishment injection of the water treatment agent is configured to be performed only when the conductivity detected by the detector 11 is higher than the conductivity at the time of the initial injection of the water treatment agent. Regardless of the conductivity at the time of initial injection of the water treatment agent,
Replenishment injection may be performed at a predetermined rate according to the amount of splashed water. Further, in the above embodiment, the water treatment agent injection is set in proportion to the actual blow time, but instead, the actual blow flow rate of the cooling water is measured by, for example, an integrating flow meter, and the measured blow flow rate is measured. It is also possible to control the operation of the water treatment agent injecting device 12 in proportion to, and to control the operation so as to inject a necessary amount of the water treatment agent. Furthermore, in the illustrated embodiment, the water treatment agent is shown to be injected into the lower water tank, but it is of course possible to inject it into the cooling water circulation line.

[0011]

As described above, according to the present invention, the blowdown amount by the operation of the blower is measured,
The water treatment agent is injected into the circulating cooling water in the cooling tower in accordance with the measured blowdown amount, and is configured to be supplementally injected in accordance with the amount of scattered water. The escape can be automatically compensated, whereby the drug concentration in the cooling water can be maintained substantially constant, and the water quality control of the circulating cooling water in the cooling tower can be fully automated. As a result, it is possible to significantly reduce the total amount of water treatment agent used throughout the year, and it is possible to greatly simplify water management.
It is expected that the running cost of the equipment will be greatly reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of a cooling tower implementing a water quality control method for circulating cooling water in a cooling tower according to the present invention.

[Explanation of symbols]

 1: Cooling tower 2: Cooling water circulation pipe 3: Cooling water circulation pipe 4: Water supply pipe 5: Overflow pipe 6: Reverse U-shaped siphon pipe 7: Water supply means 8: Air supply pipe 9: Open / close Valve 10: Blow operation control device 11: Cooling water conductivity detector 12: Water treatment agent injection device 13: Timer device 14: Scattering replenishment operation control device

Claims (2)

[Claims] 1. A method for controlling the quality of circulating cooling water in a cooling tower equipped with a blower and a water treatment agent injection device, in which the blowdown amount due to operation of the blow device is measured, and cooling is performed according to the measured blowdown amount. Water is replenished and the water treatment agent injection device is operated to inject the water treatment agent into the circulating cooling water in the cooling tower, and the scheduled time during the operation is independent from the proportional injection of the water treatment agent according to the blowdown amount. The water quality of the circulating cooling water in the cooling tower is characterized in that the concentration of the water treating agent in the circulating cooling water is constantly maintained at a desired level by replenishing the water treating agent at a predetermined amount according to the amount of scattered water at intervals. Management method. 2. A water quality control method for circulating cooling water in a cooling tower equipped with a blower and a water treatment agent injection device, in which the blowdown amount due to the operation of the blow device is measured, and cooling is performed according to the measured blowdown amount. Water is replenished and the water treatment agent injection device is operated to inject the water treatment agent into the circulating cooling water in the cooling tower, and the cooling water during operation is separated from the proportional injection of the water treatment agent according to the blowdown amount. When the conductivity is higher than the conductivity at the time of initial injection of the water treatment agent, the water treatment agent is replenished at a predetermined time interval in accordance with the amount of scattered water at a predetermined amount to constantly maintain the concentration of the water treatment agent in the circulating cooling water. A water quality control method for circulating cooling water in a cooling tower, which is characterized by maintaining a desired level.