JPH04273022A - Foaming detection method for water treatment device and defoaming device - Google Patents

Abstract

PURPOSE:To control deforming operation with foaming produced on a water surface in a reaction tank detected by combinedly using an ultrasensitive electrode type level meter responding to water or foam and a general use electrode type level meter responding to only water. CONSTITUTION:Bubble is generated in water with air diffusing tubes 8 in a reaction tank 1. Either of foam or water is judged for the foam 9 grew up on a water surface with an ultrasensitive type level switch 10 having an operating resistant sensitivity of several MOMEGA or more and a general use level switch 11 having an operating resistant sensitivity of several KOMEGA or more. Then liquid in a tank 2 is sprayed on the foam 9 from a washing spray nozzle 15 with a high pressure pump 14 to wash an electrode rod 12. Concurrently the liquid in the tank 2 is sprayed in an upper space 19 in a reaction tank 1 from a defoaming spray nozzle 18 with a high pressure pump 16 to dissolve the foam 9 expanding in the reaction tank 1, in water.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention detects bubbles that form on the water surface mainly due to surfactants, which are pollutants in rivers, lakes, etc., in reaction tanks in advanced water treatment equipment using ozone. , this relates to a defoaming filter device.

0002

[Prior Art] Foaming in reaction tanks in advanced water treatment facilities using ozone is mainly caused by pollution of rivers and lakes, which are water sources, and an increase in the concentration of surfactants in water due to drought. be.

[0003] Foaming by surfactant is 0.5 mg/l.
However, the present inventors have confirmed that it actually occurs at lower concentrations. Therefore, even if the surfactant concentration is measured using manual analysis or a continuous analyzer, other factors related to foaming are unclear, and information regarding the likelihood of foaming and the degree of foaming remains unclear. is difficult to obtain.

[0004] As a method of checking bubbles generated on the water surface in an ozone reaction tank, if the reaction tank has a structure in which a viewing window is provided on the side surface, the bubbles can be observed through the viewing window. Foaming also occurs when air is drawn into water where there is a difference in water level, so it can also be observed during such water treatment processes. However, no other method for detecting foaming is known.

[0005] Currently, the most effective defoaming method is to add activated carbon in the water treatment process before ozone treatment in order to reduce the surfactant in the water to be treated. There are only about a dozen water treatment plants in Japan that have installed this equipment, and among the water treatment plants that use heavily polluted rivers and lakes where foaming is expected to occur, water treatment using ozone is the only option. As there are only a few places that have introduced this equipment, antifoaming measures have not yet been sufficiently studied.

[0006]

However, the above-mentioned method for confirming foaming is not reliable, and even as a countermeasure against foaming, there is a problem in that it involves an increase in cost and an expansion of equipment. In other words, observing through a viewing window is a good way to confirm foaming, as long as you can observe the foam at the right time, but if this is not the case, there is a risk of bubbles entering the exhaust ozone system. However, due to contamination of the exhaust ozone treatment tower, the ozone decomposition catalyst deteriorates, causing ozone to be emitted into the atmosphere without being decomposed and causing the concentration measuring device to malfunction, making observation through a viewing window inappropriate. Not only that, but by the time you find bubbles at this point, it's often too late. Observing foaming in places where there is a difference in water level is also not a reliable method.

On the other hand, regarding the defoaming method, it is certain to remove the surfactant, which is a foaming component, by adding activated carbon in the water treatment process before the ozone treatment.
In addition to the large amount of activated carbon input, the cost of activated carbon itself is high, resulting in a significant increase in cost.

The present invention has been made in view of the above points, and its purpose is to detect foaming occurring on the water surface in a reaction tank in an advanced water treatment facility using ozone, and to detect foaming based on the information. An object of the present invention is to provide a defoaming device that performs operational control.

[0009]

[Means for Solving the Problems] In order to solve the above problems, the foam detection method of the present invention has a sensitivity with an operating resistance of several MΩ or more, from the viewpoint that the object to be controlled is foam.
Ultra-sensitive electrode level meter that responds to water or foam,
It is used in combination with a general-purpose electrode level meter that has a sensitivity of several kilohms or more and responds only to water, and determines whether the water level is changing or foam is generated, and the signal is used to control the defoaming device. Control driving.

As the defoaming device, a plurality of nozzles for spraying treated water or treated water onto foam are provided below the exhaust ozone gas outlet. This nozzle has two purposes and is a combination of sprays that produce a full cone shape. That is, one is to prevent foam from scattering into the reaction tank and entering the exhaust ozonation treatment system.
One has an angle of 35 degrees, and the other one has an angle of 0 to 45 degrees with the water surface to dissolve the foam into the water.

[0011]

[Operation] When the bubbles generated in the reaction tank rise to the surface of the water using the above-mentioned foam detection method and defoaming device, the bubbles are detected by an ultra-sensitive electrode level meter installed in the reaction tank. Based on the signal, water to be treated or treated water is sprayed onto the foam from a spray nozzle adjusted at a predetermined angle, thereby preventing foam from accumulating in the reaction tank. Pollution, deterioration in the performance of the exhaust ozone treatment system, and failure of ozone concentration measuring instruments will no longer occur.

0012

EXAMPLES The present invention will be explained below based on examples.

FIG. 1 is a schematic diagram for explaining the main structure and process of a water treatment apparatus to which the present invention is applied. Figure 1
A commercially available liquid synthetic detergent is added to the water in reaction vessels 1 and 2 so that the surfactant concentration is approximately 1 ppm, and the surfactant solution is pumped from tank 2 to reaction vessel 1 using pump 3. It flows in from the inlet 4 and flows out from the outlet 5 of the reaction tank 1. In this state, air bubbles are generated in the water from the compressor 6 via the flow meter 7 and the aeration pipe 8 in the reaction tank 1. The foam 9 that has grown on the water surface is transferred to an electrode rod 12 connected to an ultra-sensitive level switch 10 having a sensitivity of several MΩ or more in operating resistance and a general level switch 11 having a sensitivity of several kilohms or more in operating resistance. When it comes into contact with the water, the controller 13 determines whether it is foam or water, and then
From the cleaning spray nozzle 15 by the high pressure pump 14,
The liquid in the tank 2 is sprayed onto the foam 9 to clean the electrode rod 12. The electrode rod 12 is provided at a portion of the water surface in the reaction tank 1 where the foam 9 first grows. At the same time as cleaning the electrode rod 12, the liquid in the tank 2 is sprayed into the upper space 19 of the reaction tank 1 at a rate of 1 to 5 kg/cm2 from the defoaming spray nozzle 18 provided at the bottom of the exhaust ozone gas outlet 17 using the high-pressure pump 16. Spray with pressure to dissolve the foam 9 that spreads in the reaction tank 1 into the water. The water used at this time may be either treated water or treated water. Note that 20, 21, and 22 are partition walls provided in the reaction tank 1, and arrows indicate the direction of water flow.

As described above, the present invention includes an electrode type level meter and controller 13 having level switches 10 and 11 with different sensitivities connected to an electrode rod 12, high pressure pumps 14 and 16 operated according to instructions thereof, and a cleaning sprayer. A defoaming device combining a nozzle 15 and a defoaming spray nozzle 18 detects foaming and performs a defoaming action.

FIG. 2 shows the above-mentioned defoaming action, the responses of the level switches 10 and 11 to the water level in the reaction tank 1 and the presence or absence of foaming, and the defoaming pumps, that is, the high-pressure pumps 14 and 16 in FIG.
FIG. 2 is an explanatory diagram related to the operation of the vehicle. As shown in FIG. 2, the electrode rods 12 have electrode rods 12a and 1 having different lengths.
2b and 12c, and the longest electrode rod 12a is the ultra-high sensitivity level switch 10 shown in FIG. The other end is always submerged in water, and the shorter electrode rod 12b is connected for general use, and the other end is normally (normal water level). The electrode rod 12c, which has the shortest length, is connected with ultra-high sensitivity, and the other end does not come into contact with the water surface. Ultra-high sensitivity sensors with operating resistance of several MΩ or more respond to foam or water, but general-use sensors with operating resistance of several kilohms or more respond only to water. Here, each pattern shown in FIG. 2 will be explained.

[0016] Unless foaming occurs at the normal water level, each level switch and each defoaming pump will not operate.

(2) When the water level rises and the electrode rod 12b comes into contact with the water surface, only the general level switch operates. At this time, only a rise in the water level is detected.

[0018] When the water level is normal and bubbles occur on the water surface and the electrodes 12b and 12c come into contact with the bubbles, the general level switch will not respond, but the ultra-high sensitivity level switch will respond and each defoaming pump will Activate. However, the foamed state is electrode rod 12.
If the electrode rod 12c contacts the electrode rod 12c but not the electrode rod 12c, the level switch will not respond at all.
It is necessary to set a difference in length between the electrode rod 2b and the electrode rod 12c.

■When the water level rises and the electrode rod 12b comes into contact with the water surface, foaming also occurs on the water surface, and the bubbles contact the electrode rod 12c, both level switches respond and each defoaming pump operates. .

[0020] In this way, the present invention uses a combination of electrode level meters with different sensitivities and changes the lengths of these electrode rods so that the defoaming pump can be operated only when the water level has risen. This is because we have taken care to avoid this.

FIG. 3 is an external view for explaining the defoaming spray nozzle 18 shown in FIG. 1 in more detail.
(a) is a front view seen from below, and (b) is a side view. As described above, the defoaming spray nozzle 18 is installed at the bottom of the exhaust ozone gas outlet 17, but as shown in FIG. A plurality of nozzles 24 are provided to prevent the foam 9 from being crushed over a wide range from scattering into the reaction tank 1 and entering the exhaust ozonation treatment system, and a plurality of nozzles 24 are used to dissolve the crushed foam 9 into the water. It is composed of a nozzle 25. The main body 23 has a vertical body and a trapezoidal part formed integrally with its lower part, and six nozzles 24 are attached to the circumference of the vertical body of the main body 23 at equal intervals so as to be parallel to the water surface. The nozzles 25 are mounted on the horizontal surface of the trapezoidal part of the main body 23, one facing downward perpendicularly to the water surface, and six nozzles 25 that are at an angle of 30 degrees with this nozzle are mounted on the inclined surface of the trapezoidal part of the main body 23 at equal intervals. .

FIG. 4 is a diagram showing the defoaming effect with respect to the mounting angle of the nozzle 25. That is, FIG. 4 shows the experimental results when the nozzle 25 for dissolving the foam 9 into water was installed at an angle of 0 to 60 degrees perpendicular to the water surface and water was sprayed. 9 shows the size of the water surface area that appears when it dissolves in water. According to FIG. 4, the installation angle of the nozzle 25 is the highest when spraying at an angle of 30 degrees, and 0 to 4 degrees.
There was sufficient effect within the range of 5°. However, if the angle is made larger than that, the defoaming effect will drop sharply.

On the other hand, the nozzle 24 for crushing the foam 9 is
The angle is preferably about 45 to 135 degrees with respect to the direction perpendicular to the water surface. In order to cover the entire circumference of the main body 23 without any gaps in the spray range, the number of installed nozzles 24 and 25 is 6 if the spray spread of each nozzle is approximately 60°.
If you use a piece of about 120 degrees, you only need 3 pieces, so 3 pieces are enough.
~6 pieces. If there is a gap in the spray area, bubbles will rise from there and cannot be defoamed.

[0024]

[Effect of the invention] Conventionally, bubbles generated in a reaction tank have been efficiently detected in advanced water treatment equipment using ozone.
Although there was no effective means to eliminate foam, in the present invention, as described in the examples, a high-sensitivity electrode level meter and a general-purpose electrode level meter are combined, and foam growth begins at the end of the electrode rod. It quickly and reliably detects the occurrence of bubbles, operates a high-pressure pump based on the signal, and pumps water adjusted to a predetermined pressure and flow rate to the lower part of the exhaust ozone gas outlet at a predetermined height relative to the water surface. Multiple nozzles installed at an angle enable effective defoaming by spraying foam in a conical shape, eliminating the possibility of foam remaining on the water surface and eliminating various inconveniences caused by foam generation. Maintenance is easy and water treatment can be performed with high efficiency.

[Brief explanation of the drawing]

[Fig. 1] A schematic diagram for explaining the main part configuration and process of a water treatment device to which the present invention is applied.

[Fig. 2] An explanatory diagram of the relationship between the foaming detection method of the present invention and the defoaming device

FIG. 3 is an external view of the defoaming spray nozzle used in the defoaming device of the present invention, in which (a) is a front view seen from below, and (b)
) is its side view

[Fig. 4] Relationship diagram between nozzle installation angle and defoaming effect used in the defoaming device of the present invention

[Explanation of symbols]

1 Reaction tank 2 Tank 3 Pump 4 Inlet 5 Outlet 6 Compressor 7 Flow meter 8 Diffusion tube 9 Foam 10 Ultra-high sensitivity level switch 11 General level switch 12 Electrode 12a Electrode 12b Electrode 12c Electrode 13 Controller 14 High pressure pump 15 Cleaning spray nozzle 16 High pressure pump 17 Exhaust ozone gas outlet 18 Defoaming spray nozzle 19 Upper space 20 Partition 21 Partition 22 Partition 23 Main body 24 Nozzle 25 Nozzle

Claims (3)

[Claims] Claim 1: A method for detecting bubbles formed on the water surface in a reaction tank of a water treatment device using ozone, comprising an ultra-high sensitivity electrode-type level meter with a sensitivity of several MΩ or more and an operation resistance. Combined with a general-purpose electrode level meter with a sensitivity of several kilohms or more, the electrode rod is shortened to allow the ultra-sensitive electrode level meter to respond when it comes in contact with water or foam, making it suitable for general use only when in contact with water. By increasing the length of the electrode rods that respond to the water level meter and positioning the free ends of these electrode rods in the area where bubbles first grow on the water surface, the rising water level and the formation of bubbles can be detected separately. A method for detecting foaming in a water treatment device, characterized in that: 2. An apparatus to which the method according to claim 1 is applied, comprising: a. It is connected to both an ultra-sensitive electrode level meter with a sensitivity of several MΩ or more in operating resistance and a general electrode level meter with a sensitivity of several kΩ or more in operating resistance, and its free end is connected above the water surface in the reaction tank. The electrode rod with the longest length is located in the water in the area where the bubbles first grow, and is connected to an ultra-sensitive electrode level meter, and its free end is connected to the electrode rod with the longest length located in the water area where the bubbles first grow. The electrode rod is located near the growing area and has the shortest length to make the level meter respond when it comes in contact with water or bubbles, and is connected to a general electrode type level meter, with its free end above the water surface in the reaction tank. an electrode rod having a length intermediate between said two electrode rods located near the area where bubbles first grow and causing its level meter to respond only upon contact with water; b. a controller comprising the ultra-high sensitivity electrode level meter and the general electrode level meter; c. a high-pressure pump that transports treated water or water to be treated into the reaction tank based on a signal from the ultra-sensitive electrode level meter, and sprays this water toward the electrode rod near the water surface in the reaction tank. cleaning spray nozzle, d. A high-pressure pump separate from the above for transporting treated water or water to be treated into the reaction tank according to a signal from the ultra-sensitive electrode level meter; A defoaming device for a water treatment system using ozone, characterized in that it is equipped with a defoaming spray nozzle that sprays the transported water onto the foam spreading on the water surface in the reaction tank. 3. The defoaming spray nozzle according to claim 2,
The main body consists of a vertical body and a trapezoidal part integrally formed below the vertical body, and on the circumferential side of the vertical body, there is a water surface of 45 to 1
3 to 6 bubble-crushing nozzles having an angle of 35° and arranged at equal intervals; one nozzle having a direction perpendicular to the water surface on the horizontal plane of the trapezoidal portion; and a nozzle having a direction perpendicular to the water surface on the horizontal plane of the trapezoidal portion, and 3 to 6 arranged at equal intervals with an angle of 0 to 45 degrees
A defoaming device for water treatment equipment using ozone, characterized by comprising a nozzle that dissolves bubbles into water.