JP4759306B2 - Oil-water separation method and oil-water separation device - Google Patents

Description

  The present invention relates to an oil / water separation method and an oil / water separation device, and in particular, generates fine bubbles in a liquid to be treated containing oil contained in a treatment tank, and causes the oil contained in the liquid to be treated to float together with the bubbles. The present invention relates to an oil-water separation method and an oil-water separation device by a flotation separation method for separating a liquid into water and an oil component.

  As described in Patent Document 1 below, as a separation apparatus based on the levitation separation method, gas suction means is provided in the liquid suction port of the vortex pump, and air is dissolved in the liquid to be processed in the pressurization process of the vortex pump. Some gas bubbles are mixed and dissolved, and fine bubbles are generated in the liquid to be treated in the treatment tank by depressurizing and discharging from the nozzle in the treatment tank. There are also those that generate microbubbles by electrolysis.

Japanese Patent Laid-Open No. 2003-236305

  In the prior art described in the above-mentioned patent document, gas-liquid mixing and dissolution are promoted using a vortex pump to generate microbubbles, but the pump power is converted into heat to heat the liquid to be processed. In the case of electrolysis, the liquid to be treated is energized. As a result, Joule heat is generated in the liquid to be treated and the temperature rises.

  When the temperature of the liquid to be treated rises, the microbubbles expand in the liquid to be treated, the buoyancy increases, and the microbubbles rapidly rise. If it does so, the opportunity for the oil component contained in a to-be-processed liquid to contact with microbubbles will fall, and oil-water separation performance will fall. Moreover, evaporation of moisture is suppressed by the film on the liquid surface made of floating oil, and the temperature of the liquid to be processed further increases.

  When the eddy current pump is used, when the temperature of the liquid to be treated increases, there is a problem that the amount of dissolved air decreases, the amount of microbubbles generated decreases, and the oil / water separation performance decreases.

  FIG. 7 shows a situation in which microbubbles are generated by the conventional technique described in the above-mentioned patent document. 11 is a processing tank in which the processing liquid is stored, and 81 is a processing liquid stored in a part of the processing tank 11. Separation unit for separating oil and water, 13 is a large bubble separation unit incorporating a nozzle 33, 37 is a pipe for supplying a liquid to be treated in which air is dissolved from a vortex pump (not shown), and 14 is a nozzle 33 An elbow discharge pipe that guides the large bubbles a generated in the large bubble separating unit 13 to the vicinity of the surface of the liquid to be processed of the separating unit 81 when the micro bubbles b are generated from the sprayed liquid to be processed, 61 is a liquid level of the liquid to be processed, 62 is the oil surface that floated along with the fine bubbles in the oil-water separation.

  When the liquid to be treated is ejected from the nozzle 33, the air dissolved in the liquid to be treated is depressurized to become microbubbles b and flows laterally together with the jet water flow and supplied to the liquid to be treated in the separation unit 81. The large bubbles a generated at the same time gather at the ceiling of the large bubble separation unit 13 and reach the liquid level 61 of the separation unit 81 through the elbow discharge pipe 14.

  In this case, the large bubbles a are aggregated and integrated at the horizontal portion of the elbow-type discharge pipe 14 and become larger giant bubbles c, which are irregularly ejected from the opening of the elbow-type discharge pipe 14 to be treated. Is pushed up rapidly. The oil level 62 is pushed away by the sudden rise of the liquid level 61 to be processed, and the liquid level 61 to be processed is exposed.

  Then, the liquid surface 61 that has risen is lowered like a ripple generated on the liquid surface by the stones thrown into the pond, and as shown by the alternate long and short dash line, the liquid surface is lowered, and the oil surface 62 pushed away to the periphery is The liquid surface 61 to be processed becomes unstable due to repeated ejection and shielding by the oil surface 62 due to the irregular ejection of the giant bubbles c, and the water in the liquid to be processed does not evaporate. Therefore, stable oil / water separation cannot be expected.

  Therefore, an object of the present invention is to provide an oil / water separation method and an oil / water separation device capable of suppressing an increase in the temperature of liquid to be treated in a treatment tank and obtaining a desired oil / water separation performance.

  Another object of the present invention is to provide an oil / water separation method and an oil / water separation device capable of suppressing the increase in the temperature of the liquid to be treated in the treatment tank and stably obtaining desired oil / water separation performance.

  A feature of the oil / water separation method of the present invention that achieves the above object is that fine bubbles are generated in the liquid to be treated containing the oil stored in the treatment tank, and the oil contained in the liquid to be treated is floated together with the bubbles. In the oil-water separation method for separating the liquid to be treated into water and oil, the flow of the liquid to be treated is continuously provided toward the liquid surface of the liquid to be treated to expose the liquid surface of the liquid to be treated, thereby exposing the liquid to be treated. This is to prevent the temperature of the liquid to be treated from rising due to water evaporation on the liquid surface.

The oil / water separation device of the present invention that achieves the above object is characterized in that the oil contained in the liquid to be treated is floated by supplying microbubbles into the liquid to be treated stored in the treatment tank to separate the water and the oil. In the oil / water separator to be provided, a nozzle for injecting a liquid to be processed in which air is dissolved by an air supply means is provided at the lower part of the processing tank, and the nozzle injects large bubbles generated from the liquid to be processed into fine bubbles. A large bubble separation unit is provided for supplying the microbubbles into the liquid to be treated stored in the treatment tank, and the large bubbles separated in the large bubble separation part are guided near the liquid surface of the liquid to be treated stored in the treatment tank. A discharge pipe for exposing the liquid surface by forming a continuous flow of the liquid to be processed on the liquid surface of the liquid to be processed is provided.

  According to the present invention, the liquid surface of the liquid to be processed is always exposed by the continuous flow of the liquid to be processed toward the liquid surface of the liquid to be processed. As the moisture of the liquid to be treated evaporates stably on the exposed liquid surface of the liquid to be treated, the rising speed of the microbubbles is suppressed as the temperature of the liquid to be treated is lowered, and the desired oil / water separation performance is obtained. be able to.

  In addition, the presence of a constantly exposed region on the liquid surface of the liquid to be processed allows the water evaporation of the liquid to be processed to be stable, and the desired oil / water separation performance can be stably obtained.

  Hereinafter, an oil-water separator according to an embodiment of the present invention will be described.

  The oil-water separator 10 shown in FIG. 1 is used as an example for treating drain discharged from an air compressor.

  In FIG. 1, a treatment tank 11 stores a liquid to be treated in the tank and separates oil and water into the separation tank (described as a treatment tank in the claims) 81 and a floating oil that collects oil separated and floated by the separation section 81. There is a receiving portion 83, and a shielding plate 12 that separates both the portions 81 and 83 is provided. In the lower part of the side wall of the processing tank 11, the large bubble separating unit 13 is connected to the separating unit 81.

  The pipe 30 attached to the bottom of the separation part 81 in the treatment tank 11 is connected to the circulation pump 31 via the valve 36 and the pipe 32, and the outlet side pipe 37 of the circulation pump 31 is installed in the large bubble separation part 13. It is connected to the nozzle 33. The pipes 30, 32, and 37 constitute an external circulation system of the liquid to be processed in the separation unit 81, and the liquid to be processed in which air is dissolved is ejected from the nozzle 33 by the operation of the circulation pump 31 as described later.

  By pressurizing with the circulation pump 31, air is dissolved in the liquid to be treated. As an example of the circulation pump 31, a vortex pump is used. Although not shown, a gauge for measuring the pressure (water pressure) of the liquid to be treated is provided at the outlet of the circulation pump 31.

  The large bubble separation unit 13 is provided with a straight discharge pipe 14 which prevents excessive air having a large bubble diameter ejected from the nozzle 33 from passing to the separation unit 81 and prevents bubbles from being combined in the pipe. The discharge port of the discharge pipe 14 is located above the separation unit 81 and below the liquid surface 61 to be processed.

  The discharge pipe 14 is a means for continuously providing the flow of the liquid to be processed toward the liquid surface 61 of the liquid to be processed, and the situation in which the flow of the liquid to be processed toward the liquid surface 61 is continuously formed is as follows. It will be described later. The micro bubbles separated by the large bubble separation unit 13 are supplied to the liquid to be treated in the separation unit 81.

  A supply pipe 23 having a supply pump 21 and a valve 22 and constituting a supply system for an unprocessed liquid is connected to the pipe 32. The supply pipe 23 may be connected to the lower part of the separation unit 81 to supply untreated liquid to the separation unit 81.

  A discharge pipe 51 for discharging the processed liquid to be processed is provided at the upper part of the separation unit 81, and the discharge pipe 51 is lifted from a connection part (tube seat) with the separation part 81, and its downstream is connected to the separation part 81. The pipe is piped to a position lower than the connecting portion, and has a valve 52 in the middle thereof. The highest position of the discharge pipe 51 is set lower than the highest position of the shielding plate 12 of the treatment tank 11 to have a positional difference D1.

  Therefore, when supplying and storing the liquid to be processed in the separation unit 81, if the valve 52 is opened, the liquid to be processed flows out of the discharge pipe 51, and the liquid surface 61 to be processed in the separation part 81 is discharged from the discharge pipe. If the valve 52 is closed and the liquid to be treated is supplied into the separation tank 81, the liquid surface 61 to be treated rises above the highest level of the discharge pipe 51. 51 has a function of discharging the liquid to be treated and adjusting the water level by opening and closing the valve 52.

  Here, the pipe 53 provided in the discharge pipe 51 is open to the atmosphere so as not to be drained below the highest horizontal plane of the discharge pipe 51 by the siphon effect. In addition, a floating oil liquid level 62 of the floating oil that has been raised by the oil-water separation is formed on the top of the liquid surface 61 to be treated.

  A partition plate 15 is provided to prevent microbubbles and oil particles rising in the separation unit 81 from entering the treated liquid that has flowed out of the separation unit 81 via the discharge pipe 51, and the pocket-shaped suction unit 82 is provided. Is formed. That is, the separation unit 81 is configured such that the lowering speed of the processing liquid in the suction part 82 determined by the outflow amount of the processing liquid in the discharge pipe 51 and the inlet area of the suction part 82 is slower than the rising speed of the bubbles. The microbubbles and oil particles that are rising are not flown into the suction portion 82 and out of the discharge pipe 51.

  The highest position of the partition plate 15 is lower than the highest position of the discharge pipe 51, that is, the liquid surface 61 to be processed when the valve 52 is opened, so as to have a positional difference D2. Further, the highest position of the partition plate 15 is set higher than the connection portion (tube seat) with the separation portion 81 of the discharge pipe 51 so as to have a positional difference D3.

  An oil discharge pipe 55 is provided at the bottom of the floating oil receiving portion 83 to discharge the waste oil 63 that flows over the shielding plate 12 from the separation portion 81 and flows in (overflows). Moreover, although not shown in figure, piping is provided outside from the bottom part of the processing tank 11, the valve | bulb is provided in the middle, and these are used when it is necessary to discharge | emit the liquid inside the separation part 81.

Next, the operation of the oil / water separator 10 shown in FIG. 1 will be described.
The drain (liquid to be treated containing oil) discharged from the air compressor has a large drain flow rate and a low oil concentration in the drain when the absolute humidity is high (summer season). On the other hand, when the absolute humidity is low (winter and spring / autumn), the drain flow rate is small and the oil concentration in the drain is high. A continuous operation process is preferable when the absolute humidity is high (summer), and an intermittent operation process is preferable when the absolute humidity is low (winter and spring / autumn).

  First, the continuous processing operation performed when the absolute humidity is high will be described. As a preparation, the valve 52 is opened and the separation unit 81 of the treatment tank 11 is filled with fresh water or a treated liquid to be treated. When the treated liquid level 61 coincides with the highest level of the discharge pipe 51, the circulation pump 31 is operated. Let At this time, the valve 22 is closed and the supply pump 21 is stopped. The valves 36 and 42 are open.

  Next, the opening of the valve 36 is adjusted so that the inlet pressure of the circulation pump 31 (not shown) is lower than the atmospheric pressure. In the operation of the circulation pump 31, fresh water or a treated liquid to be treated is sucked from the separation unit 81, is pressurized, and flows from the pipe 37 to the nozzle 33, whereby the air supply pipe 41 side further becomes negative pressure and the dissolving air is air It flows from the supply pipe 41 and reaches the pipe 32.

  In the circulation pump 31, the air is divided and dissolved in fresh water or a processed liquid to be processed. However, the air that cannot be dissolved flows through the pipe 37 to the nozzle 33 as a large bubble. The to-be-processed liquid pressurized by the circulation pump 31 and the dissolved air are decompressed by being discharged from the nozzle 33 into the to-be-processed liquid of the separation unit 81, and the air dissolved in the water becomes minute bubbles.

  The amount of air dissolved in the liquid to be treated by the pressurization by the circulation pump 31 follows the Henry's law under the pressure, and the pressure applied to the fresh water flowing through the pipe 37 or the treated liquid to be treated and the pipe 37 The amount of dissolved air increases in proportion to the flowing flow rate. Further, the lower the temperature of the fresh water flowing through the pipe 37 or the processed liquid to be processed, the more air is dissolved. In actual operation, the operation is performed so that the pressure and flow rate are constant.

  Air that has been decompressed by being discharged from the nozzle 33 into the liquid to be treated in the separation unit 81 and dissolved in water becomes minute bubbles, but air that cannot be dissolved becomes excess bubbles (large bubbles) to separate large bubbles. It occurs in the part 13.

  The generated surplus bubbles (large bubbles) continuously rise toward the liquid surface 61 by the straight discharge pipe 14 without being combined with each other. The smaller the difference in the upper height between the upper portion of the discharge pipe 14 and the liquid surface 61 to be treated, the higher the flow rate of the floating flow caused by the difference in density between the gas and the liquid, the smaller the expansion of the large bubbles in the lateral direction, The swell on the liquid surface to be treated can be increased, and a water surface without an oil film can always exist. The heat of vaporization is increased by evaporation, and the temperature rise of the liquid to be treated can be suppressed.

  If the specific shape of the discharge pipe 14 is approximately the opposite direction in which the gravity acts or is almost straight, the coalescence of the bubbles can be suppressed. Further, if the difference in height between the liquid surface 61 to be treated and the opening of the discharge pipe 14 is within the inner diameter of the discharge pipe 14, that is, the diameter of the discharge pipe and the position of the opening in the discharge pipe If the distance is larger than the distance to the liquid level, the rise on the surface of the liquid to be processed is large, and the liquid surface 61 to be processed without an oil film becomes wide (the exposed area of the liquid surface 61 to be processed becomes wide). The cooling effect is great. In this case, the position of the liquid level of the liquid to be treated with respect to the opening of the discharge pipe 14 is not the position of the liquid level in the section that is ejected from the opening and is rising, but the section where the separated oil is present above the level. Says the position at.

  As described above, the air dissolved in the liquid to be treated is decompressed by being discharged from the nozzle 33 and becomes bubbles, and floats in the separation unit 81. The amount of air dissolved is adjusted by the valve 42 so that the bubbles are discharged from the nozzle 33. A large bubble having a large diameter floats faster than a microbubble because buoyancy works greatly.

  The rapid rise of bubbles does not contribute to the oil-water separation, and the flow in the separation unit 81 is disturbed to impede contact between the microbubbles and the oil component, which may reduce the separation performance. Since it can be considered that large bubbles are generated due to the presence of air that has not been dissolved in the liquid to be treated even when the circulation pump 31 is pressurized, the amount of the dissolving air taken in from the air supply pipe 41 is controlled by the valve 42. Adjust so that excess air does not enter as much as possible, so that large bubbles do not rise continuously.

  While maintaining this operating state, the valve 22 is opened and the supply pump 21 is driven to operate the supply system of the liquid to be processed (drain), and the fresh water or the processed liquid being circulated in the external circulation system of the separation unit 81 is operated. An untreated liquid (drain) is mixed with the treatment liquid. Then, drain is ejected from the nozzle 33 together with the microbubbles, the oil in the drain adheres to the microbubbles and floats, and the oil is separated from the liquid to be treated (water). As a result of the temperature of the liquid to be treated in the separation part 81 being kept low, the microbubbles rise slowly and the separation performance is improved.

  In the suction part 82 at the upper part of the separation part 81, the processed liquid to be processed corresponding to the unprocessed liquid to be processed supplied from the pipe 23 is sucked at a speed slower than the rising speed of the microbubbles, and the discharge pipe 51. To discharge from.

  The pressure at the outlet of the circulation pump 31 is preferably about 0.3 to 0.8 MPa in consideration of reducing the required power and reducing the diameter of the microbubbles. Considering that the amount of dissolved air is proportional to the pressure, the circulating water flow rate is 30 to 100 times the amount of untreated liquid to be treated supplied from the untreated liquid supply system, and the untreated liquid is circulated. Since it is diluted 30 to 100 times with water, the oil content of the liquid to be treated supplied to the separation unit 81 has a low concentration.

  In the oil / water separation process, in which the oil / water separation process is performed with microbubbles, the oil particles with a large diameter in the liquid to be treated float and separate before the oil particles with a small diameter. Even if it remains in the liquid, it can be continuously discharged in a state where the concentration of the processing liquid reaches a target value (for example, oil concentration 5 mg / L), and the processing capacity is high.

  The floating oil accumulates on the upper part of the separation unit 81. When the valve 52 provided in the middle of the discharge pipe 51 is temporarily closed during the continuous processing operation, the liquid surface 61 to be treated and the floating oil liquid level 62 in the separation unit 81 rise, and the floating oil liquid level 62 becomes the shielding plate. When the height exceeds 12, the floating oil overflows (overflows) and flows down to the floating oil receiving portion 83. When the floating oil in the separation unit 81 decreases, the valve 52 is opened slowly, the liquid to be processed is discharged from the discharge pipe 51, the liquid surface 61 to be processed is lowered, and the continuous processing is continued.

Next, the intermittent processing operation will be described.
First, as a preparation, the valve 52 is closed, and the circulating pump 31 is operated in a state where the separation unit 81 is filled with fresh water or a processed liquid to be processed. Although the valve 22 is closed, the valves 36 and 42 are open, and the dissolving air flows from the air supply pipe 41. The power of the circulation pump 31 becomes heat and is transmitted to the liquid to be processed, and the temperature of the liquid to be processed in the separation unit 81 is increased. In order to reduce the density of the liquid to be processed, a heating unit for increasing the temperature of the liquid to be processed may be provided in the separation unit 81.

  When the liquid to be processed rises to a predetermined temperature, the operation of the circulation pump 31 in the circulation system is stopped, the valve 42 is closed, the valve 22 of the liquid supply system to be processed is opened, and the supply pump 21 is operated. A liquid to be processed in a processing state is supplied. The liquid to be processed flows from the nozzle 33 to the separation unit 81 via the path of the pipe 30 and the pipes 32 and 37.

  Since the liquid to be processed has a lower temperature and a higher density than the fresh water or the processed liquid to be processed in the separation unit 81, the liquid to be processed accumulates at the bottom of the separation unit 81, and the processed liquid with a low processed and low oil concentration. Is pushed up to the top of the separation part 81 and discharged from the suction part 82 via the discharge pipe 51 and the valve 52. For example, the volume from the upper end of the partition plate 15 to the bottom of the separation unit 81 is 40 L, the temperature of fresh water or treated liquid to be treated is 320 K, the temperature of untreated liquid to be treated is 283 K, and the untreated liquid to be treated is supplied. Is performed at 20 L / h, only 30 L or more of the processed liquid can be discharged.

  When only the processed liquid to be processed is discharged, the valve 22 and the valve 52 are closed to stop the supply of the unprocessed liquid to be processed, and the circulation pump 31 performs circulation outside the tank.

  The amount of air dissolved in the liquid to be processed by the pressurization by the circulation pump 31 follows the Henry's law under the pressure, and the pressure applied to the fresh water or the processed liquid to be processed flowing through the pipe 37 and the pipe 37. The amount of dissolved air increases in proportion to the flow rate flowing through the. Further, the lower the temperature of the fresh water flowing through the pipe 37 or the processed liquid to be processed, the more air is dissolved. In actual operation, the operation is performed so that the pressure and flow rate are constant.

  The valve 52 is closed, and micro bubbles are present in the liquid to be processed in the separation unit 81, so that the liquid surface 61 to be processed is higher than the highest position of the discharge pipe 51. In this state, the floating oil accumulates above the liquid surface 61 to be treated in the separation unit 81, but the upper end position of the shielding plate 12 is set higher than the floating oil liquid surface 62, and the floating oil is collected during circulation of the liquid to be treated. There is no overflow from the shielding plate 12 to the floating oil receiving portion 83.

  During the circulation outside the tank, the oil content below the separation unit 81 rises due to the microbubbles and is separated into oil and water. In the floating oil separation method, the higher the oil content, the better the separation performance.

  The low concentration region has separation performance close to continuous processing. According to the observation by the present inventors, the oil concentration of the liquid to be treated in the untreated state decreases to about 1/5 of the intermediate concentration or less in the first half 50% of the circulation outside the tank, and intermediate in the second half 50% of the time. It has been confirmed that the oil concentration is lower than the concentration, and further reduced to a low concentration of about 1/5 (the target concentration in the continuous treatment). The ratio of reduction in the first half is about the same, but in terms of absolute value, most of the oil is separated in the first half.

  When the liquid to be processed in the separation unit 81 decreases to the target concentration, the circulation pump 31 is stopped, the valve 42 is closed, the valves 22 and 52 are opened, and the supply pump 21 is operated to operate the untreated state. The processing liquid is supplied from the bottom of the separation unit 81. During this period, the processed liquid to be processed in the upper part of the separation unit 81 flows out from the discharge pipe 51 by the same amount as the newly supplied unprocessed liquid to be processed.

  When the supply pump 21 and the circulation pump 31 are alternately operated and stopped for supplying and circulating the liquid to be treated as described above, and the difference between the floating oil liquid level 62 and the liquid surface 61 to be treated increases, When the floating oil collects on the upper part of the separation unit 81, the valve 52 of the discharge pipe 51 is closed during the operation of the supply pump 21, and the liquid surface 61 to be treated is flush with the shielding plate 12 to shield the floating oil. It overflows from the upper end of the plate 12 and is discharged to the floating oil receiving portion 83.

  In a normal screw-type air compressor, about 1 mm of floating oil is accumulated by continuous operation for one week, and therefore, the floating oil may be discharged about once a week. This discharge time can be determined not only by the operation time but also by measuring the amount of floating oil and the thickness of the floating oil.

  In this intermittent treatment, clean water or a treated liquid to be treated and a liquid to be treated of about 50% in an untreated state are mixed in the separation unit 81 to perform an oil / water separation treatment, and the oil content is reduced from a high concentration to a low concentration. It will be lowered in time.

  As described above, the drain flow rate is high and the oil concentration is low when the amount of moisture in the atmosphere corresponding to summer is high. When the amount of water in the atmosphere corresponding to winter is small, the drain flow rate is small and the oil concentration is high. Therefore, taking advantage of the features of the above two operation methods, it is possible to perform continuous processing when the drain flow rate is high and the oil concentration is low, and by performing intermittent operation when the drain flow rate is low and the oil concentration is high, small and high speed processing is possible. A possible oil / water separator can be constructed.

  In the intermittent treatment operation, it is possible to prepare a plurality of patterns with different lengths of the circulation period outside the tank and the liquid supply period to be treated to widen the margin of the intermediate concentration range. In addition, the apparatus can be configured only by the intermittent processing operation.

  Information on the drain flow rate or oil concentration is necessary for selecting these operation patterns. Since there is no method for measuring the oil concentration in a short time, information on the drain flow rate is used for selecting an operation pattern. The drain flow rate can be calculated from the amount of moisture in the atmosphere, the discharge air pressure of the air compressor, the outlet temperature of the air cooler, and the condensate collection efficiency. Accordingly, the atmospheric temperature and atmospheric humidity may be measured. On the other hand, a tank for storing drainage from the air compressor is usually provided, and a liquid level gauge may be attached therein, and the drain flow rate may be calculated from the change in the liquid level. It is also possible to measure only the atmospheric temperature, calculate the maximum drain flow rate with an atmospheric humidity of 100%, and use this value for control. Actually, these methods are used alone or in combination for the control. These patterns and operation mode switching are prepared as a sequence program in a control device (not shown), and based on the measurement results of each item described above, such as humidity in the atmosphere for checking the oil concentration, a calendar, etc. It can also be switched appropriately.

  Next, a state where large bubbles rise in the processing tank will be described with reference to FIG.

  Liquid to be treated and large bubbles (excess air) ejected from the nozzle 33 a. The micro bubbles b are sent to the large bubble separator 13. In the large bubble separation unit 13, surplus air (large bubbles) a having a large bubble diameter with a high rising speed is sent to the liquid surface 61 to be processed through the discharge pipe 14 together with a part of the liquid to be processed. The remaining liquid to be processed is sent to the separation unit 81. The discharge pipe 14 is provided with an opening of the discharge pipe 14 in the same direction as the rising direction of the surplus air (large bubbles) a, and has a structure in which bubbles are prevented from coalescing in the pipe.

  Due to such a structure, the large bubbles a are continuously sent to the liquid surface 61 due to the density difference between the large bubbles a and the liquid to be treated, and the liquid to be treated continues in the discharge pipe 14 accordingly. As a result, the liquid surface 61 can be lifted up. As a result, the liquid surface 61 without the floating oil liquid surface 62 can always be present in an exposed form. Therefore, the evaporation of the liquid to be processed is continued, and the amount of evaporation increases as the liquid temperature to be processed increases. The effect of increasing the heat of vaporization can be used, and the temperature rise can be suppressed.

  In FIG. 3, an example of the rise suppression result of the to-be-processed liquid temperature of this invention is shown.

  In FIG. 3, the liquid temperature on the vertical axis is the temperature of the liquid to be treated in the separation unit 81, the horizontal axis is the processing operation time, and in the case of a straight pipe that suppresses the coalescence of bubbles in the discharge pipe 14 (straight) Shape) and the case where there is a large pipe resistance (elbow shape) in which the discharge pipe 14 has a pipe shape perpendicular to the rising direction of excess air (large bubbles) as usual.

  In any case, as the liquid temperature increases, the amount of evaporation increases and the heat is dissipated by the heat of vaporization. Therefore, the increase in the liquid temperature gradually decreases and is stable at a constant temperature, but the straight pipe (straight shape) discharge pipe 14 Since the liquid surface 61 to be treated without oil film can always be present, the amount of water evaporation is large and the liquid temperature can be kept low.

  FIG. 4 shows a main part of an oil / water separator 10 according to another embodiment of the present invention.

  In this embodiment, the guide plate 16 is provided in the large bubble separation unit 13 so that the liquid to be processed ejected from the nozzle 33 increases toward the liquid surface 61 to be processed. The flow is partially restricted, and the large bubbles a are guided to the discharge pipe 14 together.

  The flow of the liquid to be processed toward the liquid surface to be processed 61 formed by the rise of the large bubble a shown in FIG. 2 is forced by the guide plate 16, and the flow toward the liquid surface to be processed 61 is constant. Thus, the exposed range of the liquid surface 61 to be processed is expanded.

  FIG. 5 shows a main part of an oil / water separator 10 according to still another embodiment of the present invention.

  In this embodiment, the amount of dissolving air taken in from the air supply pipe 41 in the embodiment shown in FIG. The liquid to be treated is continuously (continuously) formed.

  Instead of the discharge pipe 14 shown in FIG. 1, a straight pipe (pipe) 17 is provided in the separation part 81 from the bottom of the tank to the vicinity of the liquid surface 61 to be treated, and a pump 18 is provided in the middle. The pump 18 is a liquid feeding means and is driven by the motor 19. However, since the pump 18 only needs to generate a flow, it is sufficient to rotate at a low speed, and the required power of the motor 19 is small. Heating of the liquid to be treated by operation is negligible.

  In this embodiment, the large bubble separating unit 13 and the straight pipe 17 may be communicated, and the large bubble a in the large bubble separating unit 13 may be guided to the straight pipe 17. Since the flow in the straight pipe 17 sucks the large bubbles a from the communicating portion, there is no time to gather and grow into huge bubbles, and since it is agitated by the pump 18 and miniaturized, it can be communicated No problem.

  FIG. 6 shows an oil / water separator 10 according to still another embodiment of the present invention.

  This embodiment is the embodiment of FIG. 1 in which continuous processing operation is performed, and when the amount of dissolving air taken in from the air supply pipe 41 can be adjusted by the valve 42 so that excess air hardly enters, A part of the untreated liquid to be treated supplied from the pipe 23 is guided from the pipe 24 branched from the pipe 23 to the liquid surface 61 to be treated by the pipe 26 through the valve 25 and ejected.

  Along with the continuous operation of the supply pump 21, the flow rate of the unprocessed liquid that flows through the pipe 26 continuously toward the liquid surface 61 to be processed is determined by adjusting the opening of the valve 25, and the unprocessed liquid to be processed. Is ejected to the liquid surface 61 to be treated by the pressure of the supply pump 21.

  The untreated liquid to be treated that is continuously (continuously) ejected from the opening of the pipe 26 exudes floating oil to expose the liquid surface 61 to be treated, and promotes evaporation of the liquid to be treated in the separation tank 11. To prevent high temperatures.

  Since the untreated liquid to be treated ejected from the opening at the tip of the pipe 26 is at a lower temperature than the liquid to be treated in the separation tank 11, the liquid to be treated in the separation tank 11 is cooled and the separation tank 11 is also cooled. It descends to the bottom of the tank by convection inside and is used for oil-water separation.

  Since the untreated liquid to be treated ejected from the opening at the tip of the pipe 26 only needs to push out the floating oil, it is not necessary to eject a large amount of the liquid to be treated.

  Also in this embodiment, the large bubble separating unit 13 and the pipe 26 may be communicated to guide the large bubble a of the large bubble separating unit 13 to the pipe 17. Since the flow in the straight pipe 17 sucks in the large bubbles a from the communicating portion, there is no time for aggregation and growth into huge bubbles, and there is no problem even if they are communicated.

  In addition, although illustration is abbreviate | omitted, embodiment which uses the piping 17 and 26 of FIG.5, FIG.6 etc. generate | occur | produces a bubble by electrolyzing a to-be-processed liquid with the electrode provided in the processing tank which stored the to-be-processed liquid. The present invention can also be applied to an oil / water separation apparatus.

It is a figure which shows the oil-water separator which becomes one Embodiment of this invention. It is the figure which showed the state in which a large bubble raises the inside of a processing tank with the oil-water separator shown in FIG. It is an example figure which shows the temperature rise of the to-be-processed liquid in oil-water separation. It is a figure which shows the principal part of the oil-water separator which becomes other embodiment of this invention. It is a figure which shows the principal part of the oil-water separator which becomes further another embodiment of this invention. It is a figure which shows the oil-water separator which becomes further another embodiment of this invention. It is the figure which showed the state in which a large bubble raises the inside of a processing tank with the oil-water separator which becomes a prior art.

Explanation of symbols

10 ... oil-water separator 11 ... treatment tank
12 ... Shield plate
13 ... Large bubble separation part
14 ... discharge pipe
21 ... Supply pump
22, 36, 42, 52 ... valve
23, 30, 32, 37, 41, 51 ... piping
31 ... circulation pump
33 ... Nozzle
61 ... Liquid surface to be treated
62 ... Floating oil level
81. Separation part

Claims (8)

In the oil-water separation method of floating the oil contained in the liquid to be treated together with the bubbles by supplying microbubbles into the liquid to be treated containing the oil stored in the treatment tank, and separating the liquid to be treated into water and oil.
The flow of the liquid to be treated is continuously provided toward the liquid surface of the liquid to be treated so that the liquid surface of the liquid to be treated is always exposed, and the temperature of the liquid to be treated in the treatment tank is caused by water evaporation on the exposed liquid surface to be treated. An oil-water separation method characterized by preventing the rise. In the oil / water separator for separating the water and the oil component by floating the oil contained in the liquid to be treated by supplying microbubbles into the liquid to be treated stored in the treatment tank,
A nozzle for injecting a liquid to be processed in which air is dissolved by an air supply means is provided in the lower part of the processing tank, and the nozzle injects large bubbles generated from the liquid to be processed from the microbubbles to remove the microbubbles from the processing tank. A large bubble separation unit that supplies the liquid to be treated stored in the liquid tank, and guides the large bubbles separated by the large bubble separation unit to the vicinity of the liquid surface of the liquid to be treated stored in the treatment tank. An oil-water separator having a straight discharge pipe that continuously forms the flow of the liquid to be treated and exposes the liquid surface at all times .   3. The oil-water separator according to claim 2, wherein the discharge pipe is a straight pipe that extends from the large bubble separating portion toward the liquid surface of the liquid to be treated stored in the treatment tank.   4. The oil / water separator according to claim 3, wherein the diameter of the discharge pipe is larger than the distance between the position of the opening in the discharge pipe and the surface of the liquid to be treated. In the oil / water separator for separating the water and the oil component by floating the oil contained in the liquid to be treated by supplying microbubbles into the liquid to be treated stored in the treatment tank,
A straight tube to induce the liquid to be treated which is stored in the processing tank to the liquid surface near the Sosoko portion provided, the flow of the liquid to be treated was continued toward the liquid surface of the liquid to be treated by providing a liquid feed means to said straight pipe And the liquid level is always exposed to form an oil-water separator. In the oil / water separator for separating the water and the oil component by floating the oil contained in the liquid to be treated by supplying microbubbles into the liquid to be treated stored in the treatment tank,
A nozzle for injecting a liquid to be treated in which air is dissolved by an air supply means is provided at the bottom of the treatment tank,
A pump for continuously supplying the liquid to be processed to the processing tank is provided, and a pipe for guiding a part of the liquid to be processed to be supplied to the processing tank by the supply pump to the vicinity of the liquid surface of the liquid to be processed stored in the processing tank. An oil / water separator, characterized in that the liquid surface is always exposed by forming a continuous flow of the liquid to be treated toward the liquid surface of the liquid to be treated. Oite to claim 5 above, means for supplying microbubbles during the treatment liquid stored in a treating tank, a nozzle which is provided in the lower portion of the processing tank for injecting the liquid to be treated is dissolved air in air supply means Or it is an electrode which electrolyzes the to-be-processed liquid stored in the processing tank, The oil-water separator characterized by the above-mentioned. In the oil / water separator for separating the water and the oil component by floating the oil contained in the liquid to be treated by supplying microbubbles into the liquid to be treated stored in the treatment tank,
An electrode for electrolyzing the liquid to be treated stored in the treatment tank is provided,
A pump for continuously supplying the liquid to be processed to the processing tank is provided, and a pipe for guiding a part of the liquid to be processed to be supplied to the processing tank by the supply pump to the vicinity of the liquid surface of the liquid to be processed stored in the processing tank. An oil / water separator, characterized in that the liquid surface is always exposed by forming a continuous flow of the liquid to be treated toward the liquid surface of the liquid to be treated.

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