JP2004290859A - Method and apparatus for deaerating liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for deaerating a liquid, by each of which the air bubbles contained in the liquid can efficiently be removed surely. <P>SOLUTION: The liquid L containing the air bubbles to be removed is housed in a vacum tank 10 the inside of which can be kept in negative pressure. The liquid L is fluidized, the flow of the liquid L is made to be a turbulent flow and the flow velocity of the liquid L is made as high as possible by rotating a main agitation blade 21 and an auxiliary agitation blade 25 in the directions opposite to each other. As a result, the air bubbles in the liquid L expand under the reduced pressure and rise to the liquid surface, are combined with one another and become larger or are crushed by the power of the liquid L of the high flow velocity so that all of the air bubbles in the liquid L can be removed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
[Industrial applications]
The present invention relates to a liquid material such as a paint or an adhesive, a viscous liquid such as a natural or synthetic resin, and a liquid such as a coating liquid such as a coated paper, an inkjet paper, a thermosensitive recording paper, and a pressure-sensitive pseudo-adhesive paper for information recording. The present invention relates to a liquid degassing method and a degassing device for removing bubbles mixed therein.
[0002]
[Prior art]
In the process of producing a liquid having a relatively high viscosity, such as a paint, it is inevitable that bubbles are mixed in the liquid. In addition, bubbles are naturally not easily removed from these high-viscosity liquids. When these liquids containing air bubbles, for example, paint, are used for painting, uneven paint such as pinholes, streaks, craters, and baldness may occur on the painted surface, making the painted surface unattractive or applying paint. There is a risk that the commercial value of the finished product will be lost. For this reason, this type of liquid requires a deaeration process for removing bubbles.
[0003]
As a general method for degassing such a liquid, there are a stationary method, a decompression method, a stationary decompression method, and the like. The stationary method is a method in which a liquid containing air bubbles is allowed to stand still for a certain period of time to naturally cause air bubbles to float and release the air to the atmosphere. The decompression method is a method in which bubbles are expanded by reducing the pressure of a liquid to promote the floating of bubbles. The decompression method may be performed by combining liquid agitation processing.For example, a liquid to be subjected to deaeration processing is stored in a decompression tank, and a stirring blade or the like is swirled to promote the floating of bubbles, and furthermore, the liquid surface Bubbles that have floated are crushed and removed by a foaming means such as a swirling bar that swirls along the liquid surface, and the liquid is collected from the lower part of the decompression tank to obtain a liquid containing no bubbles as much as possible. . In addition, the static pressure reduction method is a method in which bubbles such as air float naturally in a pressure reduction tank without performing a process such as stirring.
[0004]
In the conventional degassing device using a decompression method using a stirring means and a foam breaking means, very fine bubbles have a low buoyancy in a viscous liquid, so the moving speed to the liquid surface is low, and the Is accompanied by the phenomenon that the bubbles are drawn into the liquid again before they are crushed, and the bubbles cannot be efficiently removed. In addition, a large amount of bubbles float on the liquid surface, and there is a possibility that bubbles that cannot be completely crushed by the bubble breaking means are generated. These remaining air bubbles may be sucked into the suction pipe for decompression, clogging a decompression device such as a vacuum pump, and cause a failure. If the processing speed is reduced to avoid this problem, the work efficiency may be reduced.
[0005]
In order to solve the above-mentioned disadvantages of the conventional degassing device, the present applicant has proposed a liquid degassing method and a degassing device. In this deaerator, air bubbles are crushed by blowing compressed air from above a decompression tank to air bubbles that have floated to the liquid surface by a decompression method (see Patent Document 1).
[0006]
In addition, the gas dissolved in the liquid is efficiently generated as bubbles, and the bubbles contained in the liquid are efficiently floated on the surface of the liquid so that degassing in the liquid can be performed in a short time. The proposed deaerator was proposed. This deaerator is a stirrer in which a plurality of rotating blades are attached at predetermined intervals up and down to a rotating shaft provided in a vertical direction in a decompression tank, and the uppermost rotating blade is attached to a plate surface. A plate-shaped perforated rotary blade provided with a number of blades along the outer circumference of a disk having a hole formed therein, and the rotary blade attached below the plate-shaped perforated rotary blade, It is a stirrer that is a plate-side non-rotating blade having a larger diameter than a plate-side holed rotary blade and having a number of blades provided along the outer circumference of a disk having no hole in the plate surface (Patent) Reference 2).
[0007]
[Patent Document 1]
Japanese Patent Application 2001-300773
[Patent Document 2]
Japanese Patent Application 2002-98013
[0008]
[Problems to be solved by the invention]
However, in the degassing device described in Patent Document 1 described above, since the pressurized air is supplied into the decompression tank, the pressure in the tank increases, which may hinder the promotion of air bubble floating. For this reason, it takes time to obtain a sufficiently degassed liquid, and there is a possibility that work efficiency may be reduced. In addition, in order to crush bubbles with pressurized air, the liquid film of the bubbles needs to be thin. For this purpose, it is necessary to grow the bubbles largely until the liquid film becomes thick enough to be easily crushed. If the bubbles floating on the liquid surface are not sufficiently grown, they may be returned into the liquid by the blown pressure air. Therefore, it may take more time to obtain a sufficiently degassed liquid.
[0009]
Further, in the deaerator described in Patent Literature 2, although the floating of bubbles in the liquid can be promoted, the bubbles for floating are not actively crushed. Therefore, the air bubbles floating on the liquid surface may be returned into the liquid again, and it may take a long time until the bubbles are sufficiently degassed.
[0010]
Therefore, an object of the present invention is to provide a deaeration method and a deaeration apparatus for a liquid, which can maintain the pressure in a decompression tank and can surely crush bubbles floating on the liquid surface. .
[0011]
[Means for Solving the Problems]
As a technical means for achieving the above object, a liquid degassing method according to the present invention is directed to a liquid degassing method for floating air bubbles in a liquid to a liquid surface and removing the air bubbles from the liquid. The tank containing the liquid to be taken care of is depressurized, the depressurized liquid in the depressurization tank is sufficiently turbulently stirred, and the flow rate of the liquid is increased to cause bubbles included in the liquid to float on the liquid surface. In addition to increasing the chances, it is also possible to increase the size of bubbles by combining fine bubbles and to promote the thinning of bubbles by decompression while preventing bubbles from rising again to the liquid surface and then being drawn into the liquid again by flux. The method is characterized in that the liquid is crushed by utilizing the pressure of the fluid and the liquid is taken out from below the liquid surface of the liquid whose flow in the pressure reducing tank has been stopped.
[0012]
By reducing the pressure in the tank and stirring vigorously, the bubbles contained in the stored liquid associate, combine and expand, and rapidly rise to the liquid surface under high buoyancy. The air bubbles that have floated combine with each other and grow larger. At this time, a force is applied to return the liquid into the liquid by the flux of the liquid being stirred.However, since the large-grown bubbles have a small thickness of the liquid film, the force is applied before returning to the liquid. Crushed.
[0013]
Further, the liquid degassing method according to the invention of claim 2 is characterized in that the stirring is performed intermittently.
[0014]
Bubbles in the liquid in the pressure reducing tank expand under reduced pressure and float. If the liquid is not agitated when it floats, the liquid level is at rest. When stirring is started from this state, the liquid receives a large acceleration and the liquid surface vibrates violently. The bubbles are easily crushed by the force at this time.
[0015]
The liquid degassing method according to the invention of claim 3 is characterized in that the stirring is performed in accordance with the state of bubbles generated on the liquid surface.
[0016]
If the stirring is continued in a state where an appropriate amount of bubbles stays on the liquid surface, the bubbles can be crushed and removed more efficiently.
[0017]
The liquid degassing method according to a fourth aspect of the invention is characterized in that the liquid is swirled when the liquid is stirred.
[0018]
When the liquid is swirled, the liquid surface becomes mortar-shaped. In addition, the air bubbles that have floated receive the flux and collect at the bottom of the mortar in the center of the decompression tank, and try to be pushed into the liquid with a large force. At this time, the bubbles are crushed by the pressure of the liquid.
[0019]
A degassing method according to a fifth aspect of the present invention is characterized in that the pressure in the tank when the liquid is taken out is substantially equal to the pressure before the liquid is taken out.
[0020]
When the vacuum pump or the like for reducing the pressure is stopped in a state where the removal of the bubbles is completed, the internal pressure of the pressure reducing tank and the internal pressure of the collecting tank from which the liquid is taken out are made equal. Thus, the liquid can be smoothly moved from the decompression tank to the collection tank, and the degassed liquid can be transferred to the collection tank without using a transfer pump or the like.
[0021]
In order to realize this degassing method, the liquid degassing device according to the present invention is a liquid degassing device that floats bubbles in the liquid to the liquid surface and removes the bubbles from the liquid. A decompression tank containing a liquid to be taken care of, the interior of which is adjusted to a negative pressure, a stirring means for sufficiently turbulently flowing the liquid in the decompression tank, and an outlet provided at a lower portion of the decompression tank Wherein the flow rate of the liquid is increased by agitation by the agitation means, and the flux promotes the coupling between the bubbles to quickly increase the size of the bubbles.
[0022]
Bubbles contained in the liquid stored in the decompression tank expand and float due to the negative pressure. The air bubbles that have risen are combined with each other and grow to form a thin film, and are crushed under the pressure of the fluid produced by vigorous stirring. At this time, the agitation increases the chances of the bubbles meeting and combining, so that the growth of the bubbles is promoted and the size is rapidly increased. Therefore, bubbles in the liquid can be quickly removed.
[0023]
Further, the liquid degassing apparatus according to the invention of claim 7 is characterized in that the stirring means is operated intermittently.
[0024]
When stirring a liquid in a stationary state, the acceleration at the start of stirring becomes large. At that time, bubbles are easily broken by receiving a force from the liquid.
[0025]
Further, in the liquid degassing apparatus according to the invention of claim 8, the decompression tank is provided with bubble detection means for detecting a state of generation of bubbles, and bubbles on the liquid surface are generated by a predetermined amount or more by the bubble detection means. In this case, the stirring means is stopped.
[0026]
That is, when a predetermined amount or more of the air bubbles stay on the liquid surface, the air bubbles are sucked into the suction pipe for depressurizing the inside of the tank, which may hinder the suction operation of the pressure reducing device. In addition, when a certain amount or more of the air bubbles stay, the amount of the air bubbles floating on the liquid surface may be larger than the amount of the crushed air bubbles, so that the air bubbles are more easily sucked into the intake pipe. Therefore, when the bubble detecting means detects that a predetermined amount or more of bubbles are staying on the liquid surface, the stirring means is stopped to reduce the amount of bubbles floating on the liquid surface. When the amount of bubbles on the liquid surface becomes equal to or less than a predetermined amount, the stirring means is operated. Therefore, bubbles can be efficiently removed and energy efficiency can be improved.
[0027]
The liquid degassing apparatus according to the invention of claim 9 is characterized in that the stirring means makes the liquid vortex.
[0028]
Bubbles floating on the liquid surface collect on the mortar-shaped bottom in the center of the decompression tank due to the eddy current of the liquid. The collected bubbles receive a force that is pushed into the liquid, and are crushed by this force.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a liquid degassing method and a degassing apparatus according to the present invention will be specifically described based on the illustrated preferred embodiments. FIG. 1 is a schematic sectional view illustrating a structure of a deaerator 1 suitable for realizing a liquid deaeration method according to the present invention. The deaerator 1 mainly includes a pressure reducing tank 10 for reducing the internal pressure to, for example, 10 kPa or less. The decompression tank 10 is composed of a tank body 11 containing the liquid L to be degassed and a lid 12, and the inside is sealed with the lid 12 covered on the tank body 11. A supply pipe 13 and an intake pipe 14 are connected to an upper portion of the lid 12. The supply pipe 13 supplies the liquid L to be degassed to the decompression tank 10, and has a supply valve 13a interposed in the middle. The suction pipe 14 connects the inside of the pressure reducing tank 10 to a vacuum pump (not shown), and the air in the pressure reducing tank 10 is sucked from the suction pipe 14.
[0030]
A main stirring motor 16 and a sub stirring motor 17 are mounted adjacent to the main stirring motor 16 at the upper center of the lid 12. The output shaft 16a of the main stirring motor 16 is connected to a transmission 18, and the output shaft 18a of the transmission 18 is inserted into the pressure reducing tank 10 through the top plate of the lid 12. The rotation of the main stirring motor 16 may be controlled by inverter control or the like without using the transmission 18. In this case, the output shaft of the main stirring motor 16 is inserted into the pressure reducing tank 10. The tip end of the output shaft 18a reaches near the lower portion of the tank main body 11, and a plurality of main stirring blades 21 are fitted therein so that the output shaft 18a rotates by rotation of the output shaft 18a. Then, the rotation of the main stirring blade 21 causes the liquid L to flow at a speed of, for example, 1 m / s or more and 40 m / s or less. The flow rate is adjusted by changing the speed ratio of the transmission 18 so as to set the flow rate in accordance with the properties of the liquid L, the state of the bubbles contained in the liquid L, and the like. Further, the main stirring blade 21 may be a propeller type or a turbine type. However, in order to generate a flow from the inside to the outside of the pressure reducing tank 10, the main stirring blade 21 is a turbine blade. Is more advantageous.
[0031]
A hollow drive shaft 22 is loosely fitted to the output shaft 18a, and the drive shaft 22 is connected to the output shaft 17a of the sub drive motor 17 via a drive belt 23. The drive shaft 22 has a distal end extending to the vicinity of the lower portion of the lid 12 and a bracket ring 24a fitted at the lower end. A support arm 24 extending obliquely downward is attached to the bracket ring 24a. It is provided integrally. The tip of the support arm 24 reaches near the inner wall of the tank body 11, and further provided with a sub-agitating blade 25 formed along the inner wall. A buffer member 25a is attached to the outer side of the sub stirring blade 25 so that the inner wall surface is not damaged even if the inner wall of the tank body 11 is rubbed. The auxiliary stirring blade 25 is turned along the inner wall surface of the tank body 11 by the rotation of the drive shaft 22, and is turned in a direction opposite to the turning direction of the main stirring blade 21.
[0032]
Further, a bubble detecting means 26 is attached to the lid 12, and the air bubble detecting means 26 detects bubbles appearing on the surface of the liquid L stored in the decompression tank 10. In addition, the detection of the bubble is performed by detecting that the bubble has risen to an appropriate height.
[0033]
The lower half of the tank body 11 of the pressure reducing tank 10 is formed in a substantially conical shape, and a discharge pipe 27 is connected to a bottom of the tank main body 11 through a discharge valve 27a.
[0034]
The operation of the liquid degassing method and degassing apparatus according to the embodiments of the present invention configured as described above will be described below.
[0035]
When the supply valve 13a is opened, the liquid L containing bubbles to be removed is supplied to the pressure reducing tank 10 through the supply pipe 13. When a predetermined amount of the liquid L is supplied, the supply valve 13a is closed. Next, the vacuum pump is operated to suck the air in the pressure reducing tank 10 from the suction pipe 14 to reduce the pressure. Further, the main stirring motor 16 and the sub stirring motor 17 are operated to stir the liquid L in the decompression tank 10. At this time, the swirling direction of the main stirring blade 21 swirled by the main stirring motor 16 and the sub-stirring blade 25 swirled by the sub-stirring motor 17 are in opposite directions, so that the liquid L is more violently and complicatedly turbulent. Will flow.
[0036]
When the pressure inside the decompression tank 10 is reduced to an appropriate pressure, the bubbles contained in the liquid L expand due to their own pressure, and the density difference with the liquid L increases, causing the liquid L to float. In addition, when the liquid L is being stirred, the bubbles are combined with each other and become larger, resulting in a larger difference in density and easily floating. When the air bubbles rise to the liquid level, they further combine and grow with each other, and the air bubbles become larger. For this reason, the liquid film of the bubbles becomes thin and bursts due to the internal pressure, and the bubbles disappear.
[0037]
Further, since the liquid L is agitated, the bubbles are crushed by receiving pressure due to the flux. For this reason, the flow rate of the liquid L generated by stirring the liquid L should be a speed suitable for crushing the bubbles in consideration of the properties of the liquid L and the state of the bubbles contained in the liquid L. Preferably, the flow rate is as high as possible, so that the bubbles can be more reliably crushed. Further, by vigorously stirring and complicatedly turbulently flowing, bubbles in the liquid are more likely to associate with each other and collide with each other. Will emerge.
[0038]
Then, the flow rate of the liquid L generated by the stirring is set to a size corresponding to the viscosity of the liquid. For example, under the condition that the inner diameter of the decompression tank 10 is 1400 mm, the viscosity of the liquid L is 400 mPs, and the ambient temperature is 25 ° C., when the operation is performed using the existing equipment, the desired degassing is performed with the rotation speed of the main stirring blade 21 set to 400 rpm. The air treatment could be performed. At this time, the remaining air bubbles after the degassing process are, for example, the liquid L after the degassing process is sampled in a cell having a thickness of about 0.5 mm, the image is continuously monitored, and the image is analyzed. The state in which the number of bubbles to be counted was 0 was evaluated as the completion of the deaeration process. In the continuous operation in which the deaerator according to the present invention is mounted, the main stirring blade 21 is operated at 800 rpm. If the flow velocity is too high, the liquid level may jump due to the viscosity, and the efficiency of crushing bubbles may be reduced.
[0039]
The liquid L to be deaerated by the deaeration method or the deaerator according to the present invention is assumed to have a high viscosity. This is because, in the case of the liquid L having a viscosity of 100 mPs or less, the bubbles can easily float, and the deaeration can be sufficiently performed by the stationary method. That is, in the case of the liquid L having a viscosity of 100 mPs or more, the degassing method according to the present invention is particularly effective.
[0040]
Since the liquid L from which the air bubbles float and are crushed and the air bubbles in the liquid are removed is discharged from the exhaust pipe 27 at the lower part of the decompression tank 10, if the liquid L is contained in a desired container such as a recovery tank, the air bubbles are not included. A liquid is obtained. When discharging, the discharge valve 27a is opened, and when the discharge is completed, the discharge valve 27a is closed.
[0041]
In the above-described operation, it has been described that air bubbles are crushed while the inside of the decompression tank 10 is stirred. However, the stirring of the liquid L may be intermittent. Since the inside of the decompression tank 10 is at a negative pressure, even when the liquid L is stationary, the bubbles expand due to the pressure, and float on the liquid surface due to the density difference with the liquid L. The main stirrer motor 16 and the sub stirrer motor 17 are operated in a state where an appropriate amount of air bubbles floats to stir the liquid L. At this time, since the liquid L starts to flow from the state of "0" and reaches the maximum velocity, the acceleration rapidly changes and becomes large, and the bubbles that have floated are easily crushed by receiving a large force due to this acceleration. Will be. Therefore, the stirring of the liquid L may be performed intermittently. In order to perform the operation intermittently, the stirring motors 16 and 17 can be operated at a predetermined cycle using a timer device.
[0042]
Further, the stirring operation may be performed in a state where the floating bubbles stay in an appropriate amount. In this case, the stirring may be performed by operating the stirring motors 16 and 17 based on an output signal generated when the bubble detection unit 26 detects a bubble. Further, it is preferable to stop the stirring operation when the air bubbles stay more than a predetermined amount. This is because, if a predetermined amount or more of air bubbles stay on the liquid surface, the air bubbles may be sucked in from the suction pipe 14 and affect a vacuum pump or the like, which may hinder the operation thereof. This predetermined amount is determined from the amount of air bubbles to be crushed and the amount of air bubbles to float. When the amount of water increases, the stirring is stopped. Then, when the amount of bubbles on the liquid surface becomes equal to or less than a predetermined amount, the stirring motors 16 and 17 are operated to restart stirring.
[0043]
Since the stirring of the liquid L is performed by the main stirring blade 21 and the sub stirring blade 25 that rotate in the opposite directions, the flow of the liquid L can be easily turbulent. Thereby, the bonding between the bubbles due to the stirring is promoted, the bubbles become larger, and the floating becomes easier. On the other hand, the main stirring blade 21 is swirled at a high speed to form a vortex. When the vortex is formed, the liquid surface becomes mortar-shaped. The air bubbles that have floated up to the liquid surface are moved inward, that is, in the direction of the mortar-shaped bottom, due to the speed difference between the outside and the inside of the liquid surface, and combine with each other to grow large. For this reason, the liquid film becomes thin, and the bubbles burst and disappear. Furthermore, the bubbles that have moved to the mortar-shaped bottom, that is, the center of the decompression tank, receive a force that is sucked into the liquid, and are crushed and extinguished by this force.
[0044]
In the embodiment shown in FIG. 1 described above, the supply and discharge of the liquid L are performed quantitatively, and the acquisition of the liquid L from which bubbles have been removed is discontinuous, that is, a so-called batch method. In order to continuously obtain the liquid L from which bubbles have been removed, for example, as shown in FIG. 2, a continuous deaerator 30 having a structure in which depressurizing tanks are connected is used. FIG. 2 shows a structure in which three decompression tanks 31 a, 31 b, and 31 c are connected, and the three decompression tanks 31 a, 31 b, and 31 c are separated by partitions 32 and 33. The partition wall 32 is suspended from above to form a gap Gb between the lower end and the bottom surface, and the partition wall 33 rises from the bottom surface to form a gap Gu between the upper end portion and the ceiling surface. The partition 32 and the partition 33 form a buffer chamber 40. A supply chamber 34a is provided outside the partition 32 of the decompression tank 31a, and a partition 33 and a discharge chamber 34b are provided outside the partition 32 of the decompression tank 31c. The supply pipe 35 is connected to the supply chamber 34a through a supply valve 35a, and the liquid L is supplied to the supply chamber 34a. Further, the intake pipe 36 is connected to each of the decompression tanks 31a, 31b, 31c, and can decompress the decompression tanks 31a, 31b, 31c separately. The main stirring blade 37 and the sub stirring blade 38 are arranged in each of the decompression tanks 31a, 31b, 31c, and these stirring blades 37, 38 can be operated independently. The discharge pipe 39 is connected to the discharge chamber 34b via a discharge valve 39a.
[0045]
In the continuous deaerator 30 according to the embodiment shown in FIG. 2, the liquid L from which bubbles have been removed can be continuously obtained. The liquid L containing bubbles sent from the supply pipe 35 is supplied to the supply chamber 34a, passes through the gap Gb below the partition 32, is sent to the buffer chamber 40, and is sent from the gap Gu above the partition 33 to the decompression tank 31a. Sent to At this time, most of the bubbles in the liquid, which are above the gap Gb, cannot pass through the gap Gb and float, and pass with the liquid flow to reach the buffer chamber 40. Further, the air bubbles also float when passing through the gap Gu 2 above the buffer chamber 40, and the liquid L reaches the decompression tank 31a. In the decompression tank 31a, the bubbles rise due to the difference in density with the liquid L, and the liquid L from which the bubbles have been appropriately removed is sent from the buffer chamber 40 to the decompression tank 31b through the gap Gb below the partition 32. The liquid L degassed in the decompression tank 31b is sent to the decompression tank 31c via the buffer chamber 40, where it is further degassed, sent to the discharge chamber 34b through the buffer chamber 40, and Will be taken out. Therefore, while continuously supplying the liquid L containing bubbles from the supply pipe 35, the liquid L from which bubbles have been removed can be taken out from the discharge pipe 39.
[0046]
FIG. 3 is a schematic diagram showing a schematic structure of the third embodiment. In this embodiment, the stirring blade 42 provided in the decompression tank 41 can be turned. The stirring blade 42 is rotatably supported by a tip end of a main shaft 43 inclined from a vertical direction. The main shaft 43 extends through the center of the lid 41a of the pressure reducing tank 41 and extends above the lid 41a. A shaft support member 44 that rotatably supports the main shaft 43 and maintains the hermetically sealed state of the decompression tank 41 is provided in a portion of the cover 41a through which the main shaft 43 penetrates. The base end of the main shaft 43 is connected to a turning arm 46 via a universal joint 45 such as a ball joint. The turning arm 46 is connected to an output shaft 47a of a driving motor 47, and is turned substantially in a horizontal plane by the operation of the driving motor 47. It should be noted that a disk may be used instead of the swivel arm 46.
[0047]
In the deaerator according to the third embodiment, when the driving motor 47 operates, the turning arm 46 turns. Since the base end of the main shaft 43 is connected to the turning arm 46 via the universal joint 45, the base end turns around the output shaft 47 a of the drive motor 47. Since the main shaft 43 is supported to be inclined with respect to the vertical direction, the tip also pivots about the output shaft 47a, and the stirring blade 42 attached to the tip pivots in the decompression tank 41. The liquid contained in the pressure reducing tank 41 is stirred. As a result, bubbles in the liquid collide with each other, grow, and float on the liquid surface. Then, the bubbles are crushed by the stirring action of the liquid and degassed.
[0048]
FIG. 4 shows a modification of the third embodiment. In this embodiment, a shaft support beam 48 for supporting the main shaft 43 is provided so as to span an intermediate portion of the pressure reducing tank 41. The output shaft 47a of the drive motor 47 penetrates through the lid 41a and projects into the pressure reducing tank 41. A turning arm 46 is attached to the output shaft 47a, and the base end of the main shaft 43 is connected to the turning arm 46 via a universal joint 45. The main shaft 43 is arranged to be inclined with respect to the vertical direction. The main shaft 43 is supported in the middle at the center of the shaft support beam 48, and the stirring blade 42 is attached to the tip.
[0049]
In the embodiment shown in FIG. 4, since the main shaft 43 does not penetrate the lid 41a, the hermeticity of the decompression tank 41 can be easily maintained.
[0050]
FIG. 5 schematically shows a fourth embodiment. In this embodiment, a stirring blade 52 for causing a flow in a substantially horizontal direction and stirring the liquid therein is arranged inside a pressure reducing tank 51. A supply pipe 53 for supplying a liquid from which bubbles are to be removed from a substantially horizontal direction is provided on one wall of the decompression tank 51, and a discharge pipe 54 is provided on the opposite wall extending from the supply pipe 53. . The stirring blade 52 is provided so as to rotate about a straight line connecting the supply pipe 53 and the discharge pipe 54 as an axis. An intake pipe 55 is connected to the pressure reducing tank 51. The liquid L supplied to the pressure reducing tank 51 is maintained such that the liquid level is higher than the supply pipe 53, the discharge pipe 54, and the stirring blade 52.
[0051]
In the degassing device according to the fourth embodiment, the liquid L degassed from the discharge pipe 54 can be continuously obtained while supplying the liquid L from the supply pipe 53. That is, the liquid L supplied from the supply pipe 53 is agitated by the agitating blades 52, and the contained bubbles grow, float, and are crushed. In addition, since the stirring blade 52 causes the liquid L supplied from the supply pipe 53 to flow toward the discharge pipe 54, the supplied liquid L can be continuously degassed. In addition, by connecting and providing a plurality of pressure reducing tanks 51, continuous degassing can be performed more reliably.
[0052]
FIG. 6 schematically shows a fifth embodiment of the deaerator according to the present invention. In this deaerator, two circulation pumps 62 and 63 are disposed in a decompression tank 61 to which a liquid to be deaerated is supplied. The discharge ports 62a, 63a of these circulating pumps 62, 63 are arranged facing each other, and the suction ports 62b, 63b are arranged appropriately separated from each other.
[0053]
In the deaerator according to the fifth embodiment, the liquid in the pressure reducing tank 61 is circulated by the circulation pumps 62 and 63. The liquid discharged from the circulation pumps 62 and 63 collides at the center of the pressure reducing tank 61 because the discharge ports 62a and 63a of the circulation pumps 62 and 63 are opposed to each other. Due to this collision, bubbles contained in the liquid grow and float on the liquid surface smoothly and are crushed.
[0054]
FIG. 7 is a schematic diagram showing a modification of the fifth embodiment shown in FIG. In this modification, the liquid L is circulated by connecting six circulation pumps 71 to 76 to the decompression tank 77 and operating each of them. Moreover, two of the six circulation pumps 71 to 76 are provided so that the discharge ports 71a, 72a, 73a, 74a, 75a, and 76a face each other. In other words, the discharge ports 71a, 74a, the discharge ports 72a, 75a, and the discharge ports 73a, 76a are arranged to face each other in pairs. Note that an intake pipe 78 is connected to the pressure reducing tank 77.
[0055]
In the embodiment shown in FIG. 7, the liquid in the pressure reducing tank 77 is collided by the operation of the circulation pumps 71 to 76, and the contained bubbles grow. In addition, since the outlets 71a to 76a of the circulation pumps 71 to 76 are provided radially, the chances of air bubbles meeting and combining increase. For this reason, the growth of bubbles is promoted and the bubbles easily float. Moreover, since the liquid discharged from the radial direction is easily turbulent, the air bubbles floating on the liquid surface are easily broken by this flow, and the air bubbles are removed.
[0056]
【The invention's effect】
As described above, according to the liquid degassing method or the degassing apparatus according to the present invention, the bubbles in the liquid stored in the decompression tank expand due to the pressure of the liquid itself, and the space between the liquid and the liquid is reduced. It rises due to the density difference. The bubbles that have risen are broken by the force of the flux of the liquid being stirred. Therefore, bubbles are removed from the liquid.
[0057]
Further, according to the liquid degassing method according to the second aspect of the present invention or the degassing apparatus according to the seventh aspect of the present invention, an appropriate amount of bubbles is efficiently stirred by being retained on the liquid surface. Bubbles can be broken.
[0058]
Further, according to the liquid degassing method according to the third aspect of the present invention or the degassing apparatus according to the eighth aspect of the present invention, the state of the bubbles remaining on the liquid surface is monitored, and the state in which an appropriate amount of the air bubbles is retained. The liquid can be agitated by the above, so that bubbles can be crushed more efficiently.
[0059]
According to the liquid degassing method according to the fourth aspect of the invention or the degassing apparatus according to the ninth aspect of the invention, the bubbles floating on the liquid surface receive the force of the vortex, and the center of the decompression tank, that is, the vortex. Is transported to the center of the liquid, and receives a force drawn into the liquid from the center, and is crushed by this force. Therefore, the bubbles are efficiently crushed.
[0060]
Further, according to the degassing method according to the fifth aspect of the present invention, the liquid can be smoothly discharged from the decompression tank after the degassing process, and can be smoothly transferred to the recovery tank or the like. For this reason, the structure of the deaerator can be simplified.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic structure for explaining a deaerator which realizes a liquid deaeration method according to the present invention.
FIG. 2 is a view showing a second embodiment of a liquid deaerator according to the present invention, and is a view showing a schematic structure of a deaerator suitable for continuous deaeration.
FIG. 3 is a schematic diagram showing a schematic structure of a third embodiment of a deaerator according to the present invention.
FIG. 4 is a schematic diagram showing a modification of the third embodiment shown in FIG.
FIG. 5 is a schematic diagram showing a schematic structure of a fourth embodiment of a deaerator according to the present invention.
FIG. 6 is a schematic diagram showing a schematic structure of a fifth embodiment of the deaerator according to the present invention.
FIG. 7 is a schematic diagram showing a modification of the fifth embodiment shown in FIG.
[Explanation of symbols]
L liquid
1 deaerator
10 Decompression tank
11 Tank body
12 Lid
13 Supply pipe
14 Intake pipe
16 Main stirring motor
17 Sub stirring motor
18 Transmission
21 Main stirring blade
24 Support arm
25 Secondary stirring blades
26 air bubble detection means
27 Discharge pipe
30 Continuous deaerator
31 Decompression tank
32 partition
33 Partition
34a Supply chamber
34b discharge chamber
35 Supply pipe
36 Intake pipe
37 Main stirring blade
38 Secondary stirring blade
39 discharge pipe
40 buffer room
41 Decompression tank
42 stirring blade
43 spindle
44 Shaft support member
45 Universal Joint
46 Swivel arm
47 Drive motor
48 axis support beam
51 Decompression tank
52 stirring blade
53 Supply pipe
54 discharge pipe
55 intake pipe
61 Decompression tank
62, 63 Circulation pump
62a, 63a outlet
62b, 63b Suction port
71-76 Circulation pump
77 Decompression tank
71a, 72a, 73a, 74a, 75a, 76a Discharge port
78 Intake pipe

Claims (9)

In a liquid degassing method in which bubbles in the liquid float on the liquid surface and the bubbles are removed from the liquid,
Depressurize the tank containing the liquid to be degassed,
The liquid in the depressurized tank under reduced pressure is sufficiently turbulent and stirred,
The flow rate of the liquid is increased to increase the chances of floating bubbles included in the liquid on the surface of the liquid, and the fine bubbles are combined to increase the size of the bubbles. By utilizing the pressure of the fluid and the promotion of thinning of bubbles by decompression while preventing it from being drawn into the liquid again,
A method of degassing a liquid, wherein the liquid is taken out from below the liquid level of the liquid whose flow in the pressure reducing tank has been stopped. The method according to claim 1, wherein the stirring is performed intermittently. The method for degassing a liquid according to claim 1, wherein the stirring is performed according to the state of bubbles generated on the liquid surface. The method for degassing a liquid according to any one of claims 1 to 3, wherein the liquid is swirled when the liquid is stirred. 2. The method according to claim 1, wherein the pressure in the tank when the liquid is taken out is substantially equal to the pressure before the liquid is taken out. In a liquid deaerator that floats bubbles in the liquid to the liquid surface and removes bubbles from the liquid,
A decompression tank containing a liquid to be degassed and having a negative pressure inside,
Stirring means for bringing the liquid in the pressure reducing tank into a sufficiently turbulent state,
With a take-out port provided at the bottom of the decompression tank,
A liquid degassing apparatus characterized in that the flow rate of a liquid is increased by agitation by the agitating means, and the flux promotes the coupling between the bubbles to quickly increase the size of the bubbles. The liquid deaerator according to claim 6, wherein the stirring means is operated intermittently. Providing bubble detection means for detecting the generation state of bubbles in the pressure reducing tank,
7. The liquid deaerator according to claim 6, wherein the stirring unit is stopped when bubbles on the liquid surface are generated by a predetermined amount or more by the bubble detection unit. The liquid deaerator according to any one of claims 4 to 7, wherein the stirring means makes the liquid vortex.

Images