JPH0638951B2 - How to monitor water-based dirt - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for monitoring contaminants in a water system, and in particular, to the attachment of suspended substances as contaminants in a circulating cooling water system where inflow and outflow of suspended substances occur. -A method for monitoring water-based fouling that can easily and accurately monitor deposition and increase in suspended solids.

[Prior Art] In the open circulation cooling water system, industrial water is mainly circulated. In such a water system, the amount of retained water decreases due to evaporation, scattering, and blowing, so supplementary water is added by that amount so that the amount of retained water is adjusted to be constant. In recent years, the suspended solids of industrial water have been increasing along with the deterioration of water quality. Suspended substances in industrial water are concentrated in the cooling water system and discharged out of the system.On the other hand, they are attached to the part where the flow is stagnant in the process of being concentrated in the cooling water system and the heat exchanger with a slow flow rate. -There is a problem that it accumulates and causes various obstacles such as heat transfer inhibition, flow path blockage, and corrosion of metallic materials.

In order to solve such a problem, conventionally, a water treatment agent such as a dispersant or a slime control agent is added to the cooling water system, or a filtration treatment for suppressing the suspended substance in the system to a low concentration is performed. Such measures have been taken.

[Problems to be Solved by the Invention] However, it is necessary to grasp the adhesion and deposition behavior of suspended solids in the system, which changes momentarily due to seasonal fluctuations, water quality fluctuations, etc., and to add a water treatment agent at an appropriate concentration and frequency. Moreover, it is very difficult to set an appropriate amount of filtered water. Therefore, conventionally, the setting conditions of these treatment methods have been empirically determined, and an excessive or excessive addition of the water treatment agent,
If the amount of filtered water is too small or too large, sufficient treatment effect cannot be obtained and the above-mentioned trouble cannot be prevented, or
This caused problems such as the processing cost rising more than necessary.

The present invention solves the above-mentioned conventional problems and sufficiently copes with the situation in the system that changes moment by moment, and easily, accurately, and rapidly monitors the dirt (suspended substance) in the water system. The purpose of the present invention is to provide a method for monitoring water-based dirt that enables appropriate anti-fouling measures to be implemented.

[Means for Solving the Problems] The method for monitoring the contamination of a water system according to the present invention is a circulation cooling system in which the amount of water held in a cooling water system not provided with a filter or a cooling water system provided with a filter is replenished with makeup water. A method for monitoring the contamination of a water system by monitoring the adhesion or accumulation tendency of suspended matter in the water system, wherein the electric conductivity or ion concentration of cooling water and the electric conductivity or ion concentration of makeup water are calculated. Each numerical value by the following formula (I) To calculate the concentration multiple of cooling water, determine the turbidity of the cooling water and makeup water, and, in the case of a cooling water system without a filter, further determine the residence time of the circulating cooling water,
Formula (II) below In accordance with the calculation of the dirt calculation value as an index of the degree of adhesion or deposition tendency of the suspended matter of the cooling water system, in the case of a cooling water system provided with a filter, further the residence time of the circulating cooling water,
Calculate the amount of filtered water, the turbidity of the outlet water of the filter, and the amount of retained water, and use the following formula (III) In accordance with the above, a calculated fouling value, which is an index of the degree of adhesion or accumulation tendency of suspended matter in the cooling water system, is calculated, and the calculated fouling calculation value is compared with a preset reference value to determine the suspension of the cooling water system. It is characterized by monitoring the degree of adhesion or deposition tendency of turbid substances.

[Operation] In the present invention, in the case of a cooling water system not provided with a filter, circulation determined by the turbidity and electrical conductivity or ion concentration of the cooling water and makeup water and the scale and operating conditions of the cooling water system. From the residence time of the cooling water, the calculated soiling value, which serves as an index of the amount of suspended solids or the degree of deposition tendency, is calculated. Further, in the case of a cooling water system provided with a filter, a fouling calculation value is further calculated using the filtered water amount, the turbidity of the filter outlet water, and the retained water amount.

The suspended substance is a contaminant such as sand taken in by microorganisms or outside the system and is not an ion. Therefore, it is completely different from salinity.

The formulas (II) and (III), which are calculation formulas for the calculation value of the contamination of the cooling water system depending on the presence or absence of the filter, will be described below.

In the above formula (II), the molecule “turbidity of makeup water × concentration factor−turbidity of cooling water” is the total turbidity brought in from the makeup water minus the actual cooling water turbidity. If this value becomes +, it means that the turbidity component tends to adhere and accumulate as dirt in the system, and if it becomes −, on the other hand, microorganisms grew in the water system, or The turbidity component in the atmosphere tends to be brought into the system.

The retention time of the denominator is provided so as to be per unit retention time, and is for grasping the degree of adhesion or deposition tendency regardless of the scale of the cooling water system.

If there is a filter in the system, it is necessary to correct the turbid mass removed by the filter, which is calculated by the formula (III) [filtered water amount x (turbidity of cooling water-turbidity of filter outlet water. Degree) / amount of water held].

In any case, it is shown that when the calculated soiling value exceeds a certain range, the degree of adhesion or deposition tendency of suspended solids increases, and therefore, in the present invention, the calculated soiled calculated value is a predetermined criterion. The value is compared with the value, and chemical injection control is performed so that the calculated stain value is within a certain range.

As a device for measuring the turbidity of the makeup water and the cooling water, an SS meter, a turbidimeter, or an alternative thereto, for example, a device capable of quantitatively measuring the absorption of light in an optical path at a certain distance. Can be used. However, in the case of the SS meter, that value may be used, but when using other values such as turbidity, obtain the proportional constant from the relationship between suspended matter content and turbidity in advance and use it. To correct the value.

And the concentration multiple of the cooling water is the conductivity meter (μs / c
It can be determined from the measurement value of m) or various ion meters and the like by the above formula (I).

The present inventor has found that fouling occurs when the calculated stain value determined by the formula (II) or (III) exceeds the range of ± 0.1 g / m ₃ / hr. In such a case, if the chemical injection pump is stopped, operate the chemical injection pump.

Dosing volume is 2 to 50 when dosing pump is operating
%increase.

And so on. Blowing can be performed instead of chemical dosing, but since SS is contained in the inflow water, there is almost no difference in SS amount even by blowing. Therefore, the chemical injection treatment is more effective. In addition, treatment such as increasing the amount of filtered water can be taken. Needless to say, the criterion for determining the stain is not limited to the range where the calculated stain value, which is the calculated value of the formula (II) or (III), is ± 0.1 g / m ₃ / hr, and may be any other value. .

In the present invention, it is advantageous to automatically perform the calculation of the concentration multiple and the calculated soil value and the chemical injection control by using a microprocessor, a sequencer or a personal computer.

Embodiments Embodiments will be described below with reference to the drawings.

FIG. 1 is a system diagram of a cooling water system for explaining an embodiment of the present invention. Reference numeral 10 is a cooling tower, and 12 is a heat exchanger. A cooling water supply pipe 14 and a cooling water return pipe 16 are provided between the cooling tower 10 and the heat exchanger 12, and a circulation pump 17 is provided in the cooling water supply pipe 14.

In the cooling tower 10, a filler 20 is installed inside a casing 18, and a water sprinkler 22 is provided above the filler 20.
The cooling water return pipe 16 is connected to the sprinkler 22. A pit 24 for receiving the cooling water sprinkled from the sprinkler 22 is provided below the filling material 20.
4 is connected to the cooling water supply pipe 14. Further, a blow pipe 25 for blowing is provided. A fan 26 is installed on the top of the casing 18, and a ventilation opening 28 is provided on the side surface.

The heat exchanger 12 is installed as a heat removal part, and the cooling tower 10 is installed as a heat dissipation part. A circulation system is formed by the heat exchanger 12, the cooling tower 10, the cooling water supply pipe 14, and the cooling water return pipe 16.

Reference numeral 30 denotes a makeup water supply pipe (hereinafter referred to as a makeup pipe) for supplying makeup water to the cooling water system, and the tip of the makeup water supply pipe is installed so as to be inserted into the casing 18.

Further, a chemical injection pipe 32 is installed so as to be inserted into the casing 18 as a chemical injection means for injecting a water treatment agent such as a scale inhibitor into the cooling water system. It is connected to a chemical injection tank 36 via an injection pump 34.

Next, an apparatus configuration for performing water quality inspection of the circulation system and the replenishment system will be described.

Piping 3 for drawing cooling water from the cooling water supply pipe 14
8 is branched, a valve V ₁ , a turbidity meter 40 and an electric conductivity meter 42 are provided in the pipe 38, and the tip thereof is inserted into the casing 18.

In addition, the supply pipe 30 has a pipe 44 for extracting makeup water.
Is branched, and a valve V ₂ and a turbidimeter 4 are connected to the pipe 44.
6 and an electric conductivity meter 48 are provided, the tip of which is inserted into the casing 18.

Detected values of turbidimeters 40 and 46 and electric conductivity meters 42 and 48 (turbidity meters 40 and 46 and electric conductivity meters 42 and 48)
Each of the outputs of 4 to 20 mA) is input to an arithmetic unit (with an arithmetic circuit and a drug injection control transmission function) 50.

On the other hand, an inverter (injection amount regulator of the chemical injection pump) 52 is connected to the chemical injection pump 34, and the chemical injection amount can be controlled by a signal from the calculation unit 50.

The operation of the cooling water system configured as described above will be described below.

The cooling water supplied from the cooling tower 10 to the heat exchanger 12 via the circulation pump 17 and the cooling water supply pipe 14 is
After depriving the heat at, it is returned to the cooling tower by the cooling water return pipe 16.
In addition, makeup water is replenished into the system from the replenishment pipe 30 in order to supplement the evaporated water, blow water, and water lost by scattering. Further, a scale inhibitor or the like is dosed from the dose pipe 32.

The turbidity and electrical conductivity of the water circulating in this circulation system and the turbidity and electrical conductivity of the makeup water are determined by the turbidity meters 40 and 46 and the electrical conductivity meters 42 and 48, and the opening and closing of the valves V ₁ and V ₂ . Is continuously or intermittently measured by the calculation unit 50, and in the calculation unit 50, the fouling calculation value is calculated according to the above-described calculation formula based on the detection signals and the residence time of the circulating cooling water determined by the scale and operating conditions of the cooling water system, The determination is made based on that value. And the dirt calculation value exceeds the reference range,
When it is determined that dirt has occurred, the operation of the chemical injection pump 34 is controlled by the inverter 52 to control the chemical injection amount.

In addition, in the example shown in FIG. 1, the case without a filter is shown, but it goes without saying that the present invention can be applied to a system using a filter. In this case, it is necessary to provide a device for detecting the turbidity of the outlet water of the filter.

Hereinafter, the present invention will be described more specifically with reference to experimental examples.

Experimental Example 1 The apparatus shown in FIG. 1 was installed in the cooling water system of a petrochemical plant, the state of dirt was monitored according to the present invention, and the injection amount of 5 wt% sodium hypochlorite was controlled based on the result. . The suspended matter content / turbidity of this cooling water system had a relationship of 1. The injection frequency of sodium hypochlorite is
In this experimental example, the injection stroke is controlled within the range of 60 / hr ± 30 / hr so that the calculated soil value by the formula (II) is within the range of ± 0.1 g / m ₃ / hr in this experimental example. did.

For comparison, the control by the device shown in FIG.
The injection amount of 5% by weight sodium hypochlorite is 8 in April to October.
The results in the case of setting 0 / hr and 50 / hr from November to March are shown in FIG. 3 and Table 1.

In FIGS. 2 and 3, the numerical values in the graphs represent the stain calculation values calculated by the equation (II). Also,
● indicates the turbidity of the cooling water (measured value), and ∇ indicates the calculated value obtained by multiplying the turbidity of the makeup water (measured value) by the concentration multiple obtained by the formula (I).

In the plant of this example, an increase in turbidity due to theoretical calculation is seen from early spring to summer. Before the device shown in FIG. 1 was attached, dirt was accumulated in the system and the turbidity of the cooling water system was lowered (FIG. 3). On the other hand, after mounting the device shown in FIG. 1, there is almost no difference between the theoretical value and the actually measured value (second
(Fig.) As shown in Table 1, the situation at the time of inspection was such that before the installation of the device in Fig. 1, the adhesion and accumulation of dirt was severe and the secondary corrosion was observed. After that, almost no dirt was attached or accumulated, and corrosion was hardly generated.

[Effects of the Invention] As described in detail above, according to the method for monitoring water-based dirt of the present invention, the state of water-based dirt, which changes from moment to moment due to seasonal fluctuations, etc. It can be detected easily and accurately with good responsiveness. Therefore, by adopting the present invention and performing chemical injection or filtration treatment based on the result, proper chemical treatment can be performed according to the state of dirt.

Loss due to excessive drug injection can be reduced.

Appropriate filtration processing can be performed.

The performance of the filtration device can also be evaluated. That is, poor filtration,
For example, channeling in the filtration layer can be found early.

It is possible to effectively prevent various obstacles due to adhesion and accumulation of dirt in the system, such as heat transfer inhibition, flow path blockage, and secondary corrosion.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention, FIG. 2 and FIG.
The figure is a graph showing the results of Experimental Example 1. DESCRIPTION OF SYMBOLS 10 ... Cooling tower, 12 ... Heat exchanger, 14 ... Cooling water supply pipe, 16 ... Cooling water return pipe, 17 ... Circulation pump, 30 ... Supply pipe, 32 ... Chemical injection pipe, 34 ... Chemical injection pump, 40, 46 ... Turbidity meter, 42, 48 ... Electrical conductivity meter, 50 ... Calculation unit, 52 ... Inverter.

Claims (1)

[Claims] Claims: 1. By monitoring the adhesion or accumulation tendency of suspended matter in a circulating cooling water system in which the amount of water held in a cooling water system not provided with a filter or in a cooling water system provided with a filter is replenished with makeup water. This is a method of monitoring water-based dirt, in which the electric conductivity or ion concentration of cooling water and the electric conductivity or ion concentration of makeup water are obtained, and each numerical value is substituted into the formula (I) below to obtain cooling water. And calculate the turbidity of the cooling water and makeup water,
Moreover, in the case of a cooling water system without a filter, the retention time of the circulating cooling water is further calculated, and dirt that is an index of the degree of adhesion or accumulation tendency of suspended matter in the cooling water system is calculated according to the following formula (II). Calculate the calculated value, and in the case of a cooling water system equipped with a filter, calculate the retention time of circulating cooling water, the amount of filtered water, the turbidity of the water at the outlet of the filter, and the amount of retained water. By calculating the calculated fouling value as an index of the degree of adhesion or accumulation tendency of suspended matter in the cooling water system according to the formula, and comparing the calculated fouling calculation value with a preset reference value, the cooling water system A method for monitoring contaminants in a cooling water system, which comprises monitoring the degree of adhesion or deposition tendency of suspended solids.