JP7259590B2 - Fouling diagnosis device for wetted parts - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for diagnosing fouling that adheres to materials that come into contact with liquid such as water.

When water that contains scale-forming components such as river water, groundwater, and recovered water, or that has the potential for biofouling is used as raw water and water is generated using a separation membrane module, particularly a reverse osmosis (RO) membrane, If the scale component is concentrated beyond its solubility, scale will precipitate. Acid agents and scale dispersants are used to suppress scale deposition, but if the agents are insufficient, scale deposits. Further, excessive addition of the chemical not only increases the cost of the chemical, but may also cause contamination problems due to gelation of the excessively added chemical.

Biofouling of the separation membrane also causes deterioration of the water permeability of the separation membrane. When biofouling progresses, it is necessary to stop the operation and perform a cleaning operation. If the biofouling is significant, performance recovery is not sufficient even after washing, and continuous operation becomes difficult. A slime control agent is added to suppress biofouling, but if the amount added is insufficient, it is difficult to suppress biofouling, and if the amount added is excessive, the cost of the agent increases. Furthermore, depending on the type of slime control agent, the separation performance of the separation membrane may be lowered.

As a device for detecting dirt (slime, corrosion products, scale) generated in water on the surfaces of wetted parts such as the walls of heat exchangers and pipes, and the membrane surface of a membrane separation device, Patent Document 1 has been proposed. There is a device described in

The device for detecting adherents to a liquid-contacting member of Patent Document 1 includes a case through which the liquid to be measured flows, a transparent portion provided in a part of the case, and a transparent portion facing the transparent portion inside the case. It comprises a installed reflector, a light-emitting part that transmits light through the transparent part and projects the light toward the reflector, and a light-receiving part that receives the reflected light from the reflector that has passed through the transparent part. It is.

Paragraphs 0028 and 0035 of Patent Document 1 describe that an RGB color sensor is used as a light receiving sensor, the color of the deposit is obtained from the light receiving wavelength distribution, and the type of the deposit is estimated based on this color. .

JP 2017-150846 A

In paragraph 0028 of Patent Document 1, it is described that the attached matter having the corresponding color is identified from the correspondence table data of the attached matter and the attached matter, but the specific relationship between the attached matter and the color is described. not

SUMMARY OF THE INVENTION An object of the present invention is to provide a fouling diagnosis apparatus for wetted members capable of diagnosing one or both of the formation tendency of biofouling and the formation tendency of scale fouling.

A fouling diagnosis device for a liquid-contacting member of the first invention comprises a case through which a liquid to be measured flows, a fouling formation section installed in the case so that the liquid to be measured contacts the case, and the fouling formation section. A light-emitting part that projects projected light onto the surface that contacts the liquid to be measured, and a light-receiving part that receives the reflected light of the projected light from the fouling forming part and outputs a signal corresponding to the intensity of the reflected light. and a diagnosis section for diagnosing the formation tendency of bio-fouling in the fouling-formation section based on the intensity decrease tendency of the signal.

In one aspect of the first invention, the fouling-forming portion is substantially white.

In one aspect of the first invention, the fouling-forming portion is provided with a mesh.

A fouling diagnosis device for a liquid contacting member of the second invention comprises a case through which a liquid to be measured flows, a fouling formation section installed in the case so that the liquid to be measured contacts the case, and the fouling formation section. A light-emitting part that projects projected light onto the surface that contacts the liquid to be measured, and a light-receiving part that receives the reflected light of the projected light from the fouling forming part and outputs a signal corresponding to the intensity of the reflected light. and a diagnostic section for diagnosing the tendency of scale formation in the fouling-forming section based on the increasing tendency of the intensity of the signal.

In one aspect of the second invention, the fouling-forming portion is substantially black.

In another aspect of the first and second inventions, the fouling-forming portion is substantially gray in color.

Since biofouling is colored, the reflected light intensity decreases as fouling progresses. On the other hand, since the scale is whitish dirt, the reflected light intensity increases as the fouling progresses.

According to the apparatus for diagnosing fouling for wetted members of the present invention, it is possible to diagnose one or both of the formation tendency of biofouling and the formation tendency of scale fouling.

According to the apparatus for diagnosing fouling of liquid-contact members of the present invention, the bio-fouling formation tendency and/or scale fouling formation tendency of liquid-contact members such as heat exchangers and pipes provided in a water system can be diagnosed with high accuracy. Therefore, based on this detection result, it is possible to appropriately control chemical injection such as an anti-scaling agent and an anti-slime agent into the water system. By measuring the amount of dirt adhered after the use of scale inhibitors, slime inhibitors and removers, the effect of chemicals can be confirmed.

Membrane fouling potential is affected by water quality fluctuations. In particular, changes in temperature and precipitation due to seasons are factors that cause water quality to fluctuate. By recording information on past changes in operating conditions, it is possible to learn seasonal changes in water quality and reflect them in operating condition change logic.

1 is a cross-sectional view of an adhering matter detection device of a fouling diagnosis device for a wetted member according to an embodiment; FIG. FIG. 10 is a cross-sectional view of an attached matter detection device of a fouling diagnosis device for a wetted member according to another embodiment; It is a graph which shows a measurement result. It is a graph which shows a measurement result. It is a graph which shows a measurement result. It is a graph which shows a measurement result. It is a graph which shows a measurement result.

FIG. 1 is a cross-sectional view of an attached matter detection device that constitutes a fouling diagnosis device for wetted members according to an embodiment of the present invention. This deposit detection device 1 includes a case 2 through which a liquid to be measured is passed. The shape of the case 2 may be rectangular parallelepiped, cylindrical, or the like.

A liquid inlet 3 is provided at one longitudinal end of the case 2 and a liquid outlet 4 is provided at the other longitudinal end. A straightening plate 5 is provided so as to face the inlet 3 and traverse the inside of the case 2 in the flow direction. As a result, the liquid that has flowed into the case 2 from the inlet 3 flows through the case 2 substantially uniformly. The straightening plate 5 may be provided in multiple stages (for example, two plates with an interval). The straightening plate 5 is made of a plate through which a large number of holes penetrate in the thickness direction.

A transparent portion 6 is provided on a part of the longitudinal side surface of the case 2 . The transparent portion 6 is made of transparent glass or synthetic resin. The case 2 other than the transparent portion 6 is made of a light-shielding material, and the inner surface is preferably black.

A fouling forming plate 7 is provided in the case 2 in parallel with the transparent portion 6 . The fouling forming plate 7 is supported by a columnar holding member (not shown) erected from the inner surface of the case 2 opposite to the transparent portion 6, but the installation structure of the fouling forming plate 7 is not limited to this. . It is also possible to arrange a separation membrane on the surface of the fouling formation plate 7 and measure fouling on the membrane surface of the separation membrane.

The surface roughness of the fouling forming plate 7 or separation membrane correlates with the fouling rate. Therefore, the fouling formation plate 7 or the separation membrane may be overlaid with a mesh to increase the deposition rate.

The reflected light intensity increases as scales are formed on the fouling forming plate 7 or separation film. Therefore, in order to detect the scale, it is preferable that the fouling forming plate 7 or the separation membrane is black with an L ^* value of about 0 to 60. As the black fouling formation plate 7 or separation membrane, a black plate or black membrane may be used, or a fouling formation plate or separation membrane coated with black paint may be used.

In addition, the reflected light intensity decreases as biofouling is formed on the fouling formation plate 7 or the film surface. Therefore, when detecting biofouling, the fouling forming plate 7 or the film surface is preferably white with an L ^* value of about 40-100.

In the case of detecting both the bio-fouling formation tendency and the scale fouling formation tendency with one fouling-forming plate 7, it is recommended to use a gray color between white and black, specifically, a gray color having an L ^* value of about 40 to 60. is a color suitable for the surface color of the fouling forming plate 7 or separation membrane.

A light-emitting portion 8 and a light-receiving portion 9 are provided outside the case 2 so as to face the transparent portion 6 . As the light emitting section 8, one having a light emitting element such as an LED is preferable.

In this embodiment, the B (blue) sensor is basically sufficient for measurement with high sensitivity, so it is sufficient to use a blue LED and a blue light receiving sensor. That is, since the scale has a high reflectance of blue, the amount of received light signal of blue increases in the light receiving portion as fouling caused by the scale progresses.

Since biofouling generally exhibits a red color, as biofouling progresses, the reflection of blue light, which is the complementary color of red, decreases. Therefore, it is possible to diagnose the progress of biofouling based on the decrease in the blue signal in the light-receiving part.

However, it uses a white LED equipped with three types of light-emitting elements to emit visible light in the three primary colors of blue, green, and red, and the light-receiving part can measure the light reception intensity of blue, green, and red wavelengths. (for example, an RGB color sensor) may be used.

The light emitting unit 8 and the light receiving unit 9 are surrounded by a cover 10 to prevent the influence of ambient light. A cover 10 covers the entire transparent portion 6 . In addition, it is preferable that the inner surface of the cover 10 is also black. The light emitting section 8 projects light obliquely onto the fouling formation plate 7 . The optical axis of the light receiving portion 9 is substantially perpendicular to the fouling formation plate 7 . The crossing angle θ of the optical axes is preferably about 0 to 60°.

Although not shown, a light-shielding plate or a light-shielding block is arranged between the light-emitting portion 8 and the light-receiving portion 9 to prevent the light from the light-emitting portion 8 from directly entering the light-receiving portion 9 .

In the present invention, the transparent portion for the light-emitting portion and the transparent portion for the light-receiving portion may be installed separately.

An operation signal is given to the light emitting unit 8 from the control unit 11, and the light receiving signal of the light receiving unit 9 is transmitted to the diagnosis unit 12 via the control unit 11 and data-processed. membrane) is diagnosed with a tendency to form fouling.

Preferably, the light-emitting portion 8 is operated intermittently, and the light-receiving portion 9 is operated to receive light only when the light-emitting portion 8 is operated to emit light. The present invention is used in systems through which liquids pass. For example, when monitoring water-based deposits such as cooling water, scrubbers, wastewater, RO, paper paprocell, tap water, iron and steel, petroleum refining, and petrochemical processes, the light emission timing of the light emitting unit 8 is 30 minutes to 3 days. It is preferable to emit light once, particularly once every 60 minutes to 12 hours. By adopting the intermittent luminescence measurement method in this way, the amount of light irradiated onto the fouling forming plate 7 is reduced, and the propagation of algae on the surface of the fouling forming plate 7 is suppressed. Also, the life of the element is lengthened.

The diagnosis unit 12 receives the absorbance or received light intensity signal from the control unit 11 . The diagnosis unit 12 diagnoses the formation tendency of biofouling and the formation tendency of scale fouling based on the absorbance or the intensity of received light.

The diagnosis unit 12 may include an estimation unit that obtains the color of the deposit from the wavelength distribution of light received by the light receiving unit 9 and estimates the type of the deposit based on this color. Color determination based on the wavelength distribution can be performed, for example, by comparing the received light intensities of blue, green, and red.

By decomposing the reflected light information into R, G, and B, each gives different information on film contamination. Slime formation due to biofouling is diagnosed by a decrease in B intensity, and scale formation is diagnosed by an increase in B intensity. By combining these pieces of information, the cause of contamination of the separation membrane module can be diagnosed, and the performance of the separation membrane module can be maintained by changing operating conditions such as chemical addition, water amount change, and pressure change. Furthermore, by recording information on changes in operating conditions based on diagnostic results and changes in the state of the separation membrane module, and adding time and timing information to modify the logic for changing operating conditions, more accurate separation membranes can be obtained. Module performance can be maintained.

The diagnosis result of the diagnosis unit 12 may be displayed on a display unit (not shown), or may be transmitted to a water system management device using a communication line.

In the present invention, by narrowing the distance between the transparent portion 6 and the fouling forming plate 7 to 10 mm or less, for example, 0.1 to 10 mm, particularly 2.0 to 6.0 mm, the transparent portion 6 and the fouling forming plate 7 are separated from each other. It is possible to reduce the amount of light absorption due to turbidity in the liquid flowing between and and measure the amount of deposits on the fouling formation plate 7 with high accuracy.

The case 2 preferably has a water flow rate of about 0.05 to 1.0 m/sec, but it can also be used in a stationary state (immersed in a water system).

In order to diagnose the bio-fouling formation tendency and/or the scale fouling formation tendency of a water-system wetted member, water diverted from the water system is continuously passed through the case 2, and the light-emitting unit 8 and the light-receiving unit 9 is preferably operated intermittently to diagnose biofouling formation tendency and/or scale fouling formation tendency based on the received light intensity and/or the received light wavelength distribution signal of the light receiving section 9 .

FIG. 2 shows an attached matter detection device 20 used in another embodiment. In this detection device 20 , a separation membrane 22 made of a flat membrane is arranged on a water-permeable porous support plate 23 in a case 21 . The separation membrane 22 may be an RO membrane, a UF membrane, an MF membrane, or the like. A primary chamber (raw water chamber) 24 is provided on the primary side of the separation membrane 22, and a secondary chamber (permeated water chamber) 25 is provided on the secondary side. That is, the separation membrane 22 is provided so as to separate the raw water chamber 24 and the permeated water chamber 25 .

Raw water is supplied to the inlet 24 a of the raw water chamber 24 by a pump (not shown), and permeated water that has passed through the separation membrane 22 and the support plate 23 is taken out from the outlet 25 a of the permeated water chamber 25 .

At least part of the primary side of the case 21 is provided with a transparent portion T made of a transparent resin (for example, polycarbonate). A light-emitting portion 8 and a light-receiving portion 9 are arranged outside the transparent portion T. As shown in FIG. Based on the light receiving signal of the light receiving unit 9, one or both of the biofouling formation tendency and the scale fouling formation tendency on the membrane surface of the separation membrane 22 are diagnosed in the same manner as in the embodiment of FIG. do.

[Example 1]
In the deposit detection device of the fouling diagnosis device for wetted members ^shown in FIG. A fluoroethylene membrane (Millipore: JCWP) was used.

Concentrated water obtained by concentrating the following synthetic water with an RO membrane (Nitto Denko ultra-low pressure RO membrane ES20) was used as raw water.

As synthetic water, ultrapure water contains 100 mg/L sodium chloride, 84 mg/L sodium bicarbonate, 10 mg/L calcium (as calcium chloride), 0.1 mg/L aluminum (as polyaluminum chloride), 100 mg/L silica as sodium acid) was added, and the pH was adjusted to 7 with hydrochloric acid and sodium hydroxide.

This synthetic water was passed through the above RO membrane at a flux of 0.57 m/d at a recovery rate of 75%. The RO membrane was flushed to release the pressure for 1 hour out of 24 hours. The following fouling measurement experiment was performed using this RO concentrated water.

<Experiment 1>
Concentrated water was passed through the attached matter detection device 20 of FIG. 2, and changes over time in the intensity of the RGB light received by the light receiving portion and the membrane flux were measured.

FIG. 3 shows the results of plotting changes from the initial values of the intensities of R, G, and B (hereinafter referred to as Δintensities) against time. B has a Δ intensity of 10 or more in the initial 20 hours. The delta intensity of R and G is lower than that of B. The Δ intensity of B became 135 after 310 hours.

FIG. 4 shows changes over time in the flux ratio (the ratio to the initial value when the initial value is 1.00). After 200 hours, the flux decreased to 16% of the initial value (flux ratio=0.16).

<Experiment 2>
In Experiment 1, when the Δ intensity of B reached 10 or more in the initial 20 hours, hydrochloric acid was added to adjust the pH of the RO feed water to 6.5. Other than that, the test was conducted under the same conditions as in Experiment 1. As a result, as shown in FIG. 4, after 200 hours, the flux was 58% of the initial value (flux ratio=0.58).

<Experiment 3>
In Experiment 1, when the Δ strength of B reached 10 or more in the initial 20 hours, hydrochloric acid was added to adjust the pH of the RO supply water to 6.5, and Kurita Water Industries, Ltd. made Kurita Water Industries Ltd. as a scale inhibitor. 1.2 mg/L of N195 was added. Other than that, the test was conducted under the same conditions as in Experiment 1. As a result, after 200 hours, the flux was 83% of the initial value (flux ratio=0.83) as shown in FIG. 4, and the Δ intensity of B was about 22 as shown in FIG.

[Example 2]
Raw water, which will be described later, was passed through the attached matter detection apparatus of FIG. 1 to conduct a test.

The case 2 has a longitudinal length of 150 mm, a cross section perpendicular to the longitudinal direction of 40×62 mm, and the transparent portion 6 is a transparent acrylic plate of 42×60×1 mm. The fouling formation plate 7 was a white PVC plate of 30×60×1 mm, and an RO membrane was placed on the upper surface thereof, and a mesh was overlaid thereon and bolted. The mesh is made of nylon with a wire diameter of 0.36 mm and an opening of 2 mm. The distance between the transparent portion 6 and the fouling forming plate 7 was set to 5 mm. As the straightening plate 5, a plate having a thickness of 5 mm and having ten holes with a diameter of 6 mm was used. Two rectifying plates 5 were arranged with an interval of 10 mm. A white LED was used as the light emitting unit 8 . As the light receiving section 9, an RGB color sensor is used.

As raw water, general wastewater from Kurita Water Industries Co., Ltd. Kurita Development Center was subjected to biological treatment, flocculation treatment, pressure flotation treatment, double-layer filtration and UF filtration, and then passed through an activated carbon tower. .67 mg/L added was used.

This raw water was passed at 5 L/min.

A slime index value (hereinafter referred to as SI value) calculated by the following equation was calculated from the RGB light receiving intensity of the light receiving unit 9 .

SI value =
[log(Rin/R)]+[log(Gin/G)]+[log(Bin/B)]
Rin: initial received light intensity of red
Gin: Initial received light intensity of green
Bin: Initial received light intensity of blue
R: measured intensity of red
G: Measured intensity of green
B: Measured intensity of blue

FIG. 6 shows changes over time in log(Rin/R), log(Gin/G) and log(Bin/B), and FIG. 7 shows changes over time in the SI value, which is the sum of these three values.

[Example 3]
The test was conducted under the same conditions as in Example 1 except that no mesh was provided. FIG. 7 shows changes in SI values over time.

<Discussion>
As shown in FIG. 6, among log (Rin/R), log (Gin/G) and log (Bin/B), log (Bin/B) has the largest change over time, and the use of blue light makes the film sensitive. It was observed that surface fouling could be detected.

As shown in FIG. 7, by not overlapping the mesh on the RO membrane, the change in the SI value over time is reduced, so it was confirmed that the placement of the mesh promotes fouling.

REFERENCE SIGNS LIST 1, 20 Attached matter detection device 2 Case 6 Transparent part 7 Fouling forming plate 8 Light emitting part 9 Light receiving part 11 Control part 12 Diagnosis part 22 Separation membrane 23 Porous support plate 24 Raw water chamber (primary chamber)
25 permeated water chamber (secondary chamber)

Claims (6)

a case in which the liquid to be measured is circulated;
a fouling forming part installed in the case so as to be in contact with the liquid to be measured;
a light-emitting portion that projects light onto a surface of the fouling-forming portion that is in contact with the liquid to be measured;
a light receiving unit that receives reflected light from the fouling forming portion of the projected light and outputs a signal corresponding to the intensity of the reflected light;
A fouling diagnostic device for a wetted member , comprising a diagnostic unit that diagnoses a bio-fouling formation tendency in the fouling-forming portion based on the intensity reduction tendency of the signal,
A fouling diagnostic device for a liquid contacting member, wherein a mesh is provided in the fouling forming portion. 2. The fouling diagnosis device for a liquid contacting member according to claim 1, wherein said fouling forming portion is substantially white. a case in which the liquid to be measured is circulated;
a fouling forming part installed in the case so as to be in contact with the liquid to be measured;
a light-emitting portion that projects light onto a surface of the fouling-forming portion that is in contact with the liquid to be measured;
a light receiving unit that receives reflected light from the fouling forming portion of the projected light and outputs a signal corresponding to the intensity of the reflected light;
A fouling diagnostic device for a wetted member , comprising a diagnostic unit for diagnosing a tendency of scale formation in the fouling-forming portion based on an increasing tendency of the intensity of the signal,
A fouling diagnostic device for a liquid contacting member, wherein a mesh is provided in the fouling forming portion. 4. A fouling diagnostic device for a liquid contacting member according to claim 3 , wherein said fouling forming portion is substantially black. 4. The fouling diagnosis device for a liquid contacting member according to claim 1 , wherein said fouling forming portion is substantially gray in color. The gray color L ^* The fouling diagnosis device according to claim 5, wherein the value is 40-60.

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