JPH06339645A - Polluted fluid capturing apparatus - Google Patents

Abstract

PURPOSE:To quickly capture polluted fluid in a wide area at high efficiency by installing a polluted fluid capturing hood in the center of an apparatus and an outer circumferential whirling flow generating part in the outer circumference of the hood and making the suction amount of the capturing hood larger than the amount to be blown to the outer circumference. CONSTITUTION:One or more whirling flow guiding plates 6 have the center part which is made to form an enclosing circle and a capturing hood 1 in which an impeller 2 of a centrifugal pump is built is so arranged as to set the suction inlet 3 upward and further a circular duct-like outer circumferential whirling flow generating part 9 is set in the outer circumference of the hood concentrically. A slit-like circular blowing outlet 4 is opened in the inner circumference of the upper end part of the whirling flow generating part 9 while being set to face the outer circumference of the guiding plate 6, and a dust 8 extended in the rotary direction of the impeller 2, which is the tangential direction of the side wall, is installed in the side face of the capturing hood 1 and communicated with the outer circumferential whirling flow generating part 9. The suction amount of the suction inlet 3 is made to be larger than the spiralling and blowing amount from the outer circumference of the apparatus. In this way, the spiralling whirling flow can be accelerated and the force to move upward of the fluid is increased and the capturing work is heightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid contaminated or polluted with a pollutant from a wide range of fluid (liquid or gas) (hereinafter, simply referred to as "contaminated fluid"), such as oil in the case of fluid. Organic solvents, liquids contaminated with heavy metals, etc.
And the water area where red tides and water-blooms are generated by microorganisms, and in the case of gas, a gas atmosphere contaminated with soot, dust, oil mist, or exhaust substances (CO, CO ₂ , NO _X SO _X, etc.) from fossil fuels, etc. , Is rapidly collected and concentrated by the centripetal force due to the swirling vortex and discharged to the outside, or other filtration, adsorption,
The present invention relates to an apparatus for preventing the progress of environmental pollution by using a known purifying means such as chemical treatment.

[0002]

2. Description of the Related Art Up to now, there have been a centrifugal force method and a centripetal force method as fluid separation and recovery methods by a swirling vortex flow, but the former is used for separation from a two-liquid mixed fluid utilizing the difference in specific gravity due to high speed swirling, while the latter is used. Is used for separating and recovering mutually insoluble two liquids represented by oil and water by centripetal force by a low speed swirling vortex system.
The present invention relates to the latter swirling vortex centripetal force method of the above methods.

[0003]

However, since the centripetal force method used so far is based on the swirling vortex flow from the impeller in the collection hood, it exhibits a high centripetal force near the hood at the center of the device. Therefore, since the centripetal force hardly acts, the centripetal collection speed becomes slow, and it takes a long time to collect and remove the contaminated fluid in a wide area. Therefore, the present invention is
A swirl generator is also provided in the peripheral portion of the device, and a new method that should be considered as an external centripetal swirl vortex method is used to solve the conventional drawbacks.

[0004]

As described above, in order to rapidly collect and remove the contaminated fluid in a wide area by the centripetal force method, it is important how to efficiently draw the contaminated fluid from the outer periphery of the trapping device. It is an issue. Therefore, let us consider the physical phenomenon of turning centripetal force before entering the solution.
First, referring to FIG. 6, theoretically three apparent forces act on the rotating coordinate system. In order to simplify the explanation, when an object of mass m is moving around the point O in the same plane at a radius r and a rotational angular velocity ω at a constant rotational circular motion, the centrifugal force f ₁ , is applied to the object. Centripetal force f ₂ , Coriolis force f ₃
The three apparent forces of are acting. (Note) Coriolis force: Gaspard Gustave
de Corioli (1792-1843) 1828
Announced in. In a coordinate system that rotates at a constant angular velocity, when an object moves, the apparent force that tends to deviate in the direction of rotation of that coordinate system. : On the earth, it is known that the wind direction of the northern hemisphere turns clockwise when viewed from above, and low pressure (typhoon etc.) turns counterclockwise. In FIG. 6, for the sake of explanation, when the object tries to move to the center O by the centripetal force, it is assumed that the Coriolis force acts in a direction perpendicular to the center O, that is, in a direction coinciding with the rotation direction. And f
₁ = mrω ² (1), f ₂ = −mrω ² (2), f
₃ = mrω ² (3) Since the centripetal force method is the main object of the method of the present invention, the examination of the solution to the problem will be advanced from the equations (2) and (3). First, as a means for effectively drawing in the fluid in the outer peripheral portion of the device by the present centripetal force method, from the formula (2), a method of increasing the radius r of the centrifugal pump or the rotational angular velocity ω so as to strengthen the centripetal force of the fluid can be considered. However, the former is not a good idea with a significant energy loss because the shaft power is proportional to the fifth power of the pump impeller diameter from the performance conversion formulas of the two similar pumps. Therefore, it is more effective to accelerate the rotation of the impeller to recirculate the fluid sucked by the pump to the outer peripheral portion of the device, and to generate a swirling flow inward from the fluid to assist the centripetal force. Here, there is an item to be examined from another element. That is, the former is significantly larger than the latter in the physical mass and kinematic viscosity of liquids and gases. Therefore, in the case of a liquid, the swirling flow velocity is attenuated by the fluid resistance, and the flow is lengthened because the flow is biased in the swirling direction by the Coriolis force until it reaches the suction port. Further, the centripetal force tends to decrease more and more from the equation (2) as the radius r becomes smaller toward the center of the apparatus. Therefore, providing a vortex flow guide plate that guides mechanically so that the circulation flow path is shortened and reaches the suction port before the swirling flow velocity from the outer circumference is weakened is an effective means for solving problems in the liquid region. It is provided. Here, the effect of this eddy current guide plate will be described. In FIG. 6, the mass m described above
When the above object hits the envelope surface of the vortex flow guide plate 6 at the point P, the following force relationship occurs. (Effect of Bernoulli's theorem in order to simplify the explanation in Nao此omitted.) That induction force _{f o} is represented by _{f o = f 3 (cosφ-} μsinφ), primarily to the cosine component of the Coriolis force _{f 3} Because,
The envelope is drawn with a force stronger than the centripetal force f ₂ and is rapidly guided to the center. As described above, the vortex flow guide plate has a function of guiding the swirl flow velocity to the suction port with a short circulation passage as a strong vortex flow while the swirling flow velocity is not attenuated. The above is the outline of the action and effect of the eddy current guide plate. Next, the solution is similarly examined for the gas region of the present invention. In this case, a phenomenon completely different from that of the liquid is exhibited. That is, since the mass is small, the centripetal force is weak, but the suction pressure on the suction side should be increased accordingly. Then, since the kinematic viscosity coefficient is extremely small, the swirling vortex flow is hardly attenuated and is rapidly drawn to the center. Therefore, from the theoretical formula, as the radius r of the vortex becomes smaller, the rotational angular velocity ω increases, the rotational velocity is further accelerated, and the centripetal force tends to be increased. It can be said that this phenomenon is completely opposite to the case of liquid. It is not necessary to provide the vortex flow guide plate as in the case of the above liquid, because it will rather hinder the vortex flow and have an adverse effect. Further, in this case, the fine powder contained in the fog, dust, etc. has a large centripetal force because the mass m is larger than the surrounding gas, converges to the center of the vortex, and is sucked into the suction port while being concentrated. With the knowledge from the above theory and phenomenon engineering in mind, if the external centripetal swirling vortex system of the present invention is used in combination with a conventionally known air curtain system, it can be an effective means for solving problems in the gas region. is there. Examples of the method of the present invention will be described below with respect to the liquid region and the gas region.

[0005]

Embodiment 1 FIGS. 1 and 2 show an embodiment in a liquid region of a pollutant fluid collecting device by a new external centripetal vortex flow system according to the present invention. FIG. 1 is a plan view and FIG. A- in FIG.
FIG. First, in FIG. 1 and FIG. 2, one or more eddy current guide plates 6 are configured so that the center part draws a substantially envelope circle.
It is semi-submerged in the water surface and appropriately held horizontally by a support, and the member of the guide plate 6 is constructed so that the peripheral portion is shallow from the water surface and the envelope cylinder portion in the central portion is deeply immersed. Below this is the impeller 2 of the centrifugal pump driven by the prime mover 5.
Collection hood 1 with a built-in suction inlet 3 (water side)
An outer peripheral vortex generator 9 formed of an annular duct is disposed concentrically with the hood 1 on the outer periphery of the device, and a slit-shaped annular outlet 4 is provided on the inner periphery of the upper end of the vortex generator to guide the upward vortex flow. The plate 6 is concentrically opened so as to face the outer periphery of the plate 6. Further, a duct 8 extending in the tangential direction of the side wall and in the same direction as the rotation of the impeller 2 is provided on the side surface of the collection hood 1 and is connected to the outer peripheral vortex generator 9 so that the liquid is circulated from the hood side. Keep it. In addition, at least one duct 8 is evenly provided on the outer periphery of the hood, and the swivel damper 7 for adjusting the flow rate is built-in.
Further, liquid escape holes 12 are provided downward near the hood, and the damper 7 is appropriately adjusted so that the swirling flow blows out uniformly from the annular outlet 4 over the entire circumference. Since the rotation of the impeller may be low, the prime mover 5 may be an underwater electric motor with a speed reducer or a hydraulic or pneumatic motor. Then, the suction amount of the suction port 3 is set to be larger than the swirl blowing amount from the outer periphery of the device. The present apparatus configured as described above is provided with a plurality of support members 10
Shall be held horizontally from the bottom of the water. In the apparatus configured as described above, when the contaminated fluid S _o such as an oil agent is floating on the water surface in the form of a film, the impeller 2 in the collection hood 1 is rotated clockwise by the prime mover 5 as shown in FIG. Then, water is sucked from the suction port 3 on the upper surface by a centrifugal pump action, is diffused to the outer periphery of the hood, and is discharged into the outer peripheral vortex generator 9 through the four ducts 8 equally divided in the tangential direction. Then, while rotating in the same direction as the rotation of the impeller 2, it is blown out as a centripetal swirling flow from the annular outlet 4 toward the center of the device. At this time, the centripetal swirl flow is blown out uniformly over the entire circumference by adjusting the flow rate by the damper 7. The external centripetal swirling flow thus generated has the following effects. That serves to attract contaminated fluid S _o floating surface water and there around the vicinity of the annular air outlet 4 as the wake in the centripetal swirling flow. Then, a swirling vortex is formed in the vortex flow guide plate 6, and as described in the above section "Means for Solving the Problem", the Coriolis force and the guide plate enveloping surface promote the centripetal force while guiding the envelope. To be done. This action has the effect of accelerating the swirling vortex flow, collecting it rapidly and efficiently in a short circulation passage, and enhancing the collection action. In this way, when the collected contaminated fluid has a floating property such as oil, it is accumulated as a thick layer in the envelope cylinder as shown in FIG.
It is sucked and discharged at 1. On the other hand, the liquid below the guide plate 6 is sucked into the collection hood 1 through the suction port 3 and is returned to the outer peripheral vortex generator 9 via the duct 8. In this collecting work, the suction amount is set to be larger than the outer peripheral blowing amount, but not all of the swirling vortex flow including the wake is sucked into the suction port 3, and a part thereof is collected. It is diverged and diffused from around 1 to below the device. The above is the description of the operation function and the operation effect of one embodiment in the liquid region of the present invention. Incidentally, to supplement the explanation here, for example, although not shown in FIGS. 1 and 2, the outer peripheral vortex generator 9 may not necessarily be an annular duct, and may be a plurality of divided fan-shaped ducts. Alternatively, in practice, four or more linear ducts may be arranged in a plan view in an equilateral polygon such as a quadrangle or more hexagon or octagon as shown in FIG. Also, the cross section may be a round pipe as shown in FIG. Further, when the intake amount on the hood side and the blowout amount on the outer circumference are appropriately set as described above, the adjustment damper 7 and the escape hole 12 are provided.
May be omitted. Further, a fluid blowout adjusting plate (deflector) (not shown) is provided in the blowout port 4 of the outer peripheral vortex generator 9 so that the external centripetal swirling flow can be adjusted so as to coincide with the winding direction of the vortex flow guide plate 6. A plurality of angle-adjustable spot air outlets as shown in FIG. 5B may be arranged.
A filter material (not shown) may be attached to the suction port 3 of the collection hood to filter microorganisms such as red tide or water-bloom and suspended matter such as scum. Furthermore, the outer circumference eddy current generator 9
Water may be supplied to the pump not by the collection hood but by a conventionally known pump provided separately from the present device. In such a case, the duct 8 becomes unnecessary. Alternatively, the collected liquid may be filtered and then circulated to the water supply pump. In such a case, the centrifugal pump in the collection hood becomes unnecessary. If the device is used in the ocean, a river, a swamp, or the like, a floater may be attached to the device or a special ship may be provided to provide a floating collection device. The above is the outline of the embodiment of the present invention in the liquid region. When such a contaminated fluid collector is used, it is possible to rapidly collect a contaminated fluid in a wide area, and therefore, it is not only useful for oil recovery work such as large-scale oil spill accidents, but also for dams. When it is used as a circulation device that collects oxygen-rich dissolved water in the surface layer of lakes such as Numa Lake or the ocean and introduces it into the deep layer, it can be used as a water quality purification device.

[0006]

[Embodiment 2] Next, as another embodiment of the method of the present invention,
The case corresponding to the gas region will be described. FIG. 3 is a vertical cross-sectional view of a contaminated fluid collecting device in a gas region by an external centripetal swirling vortex system, which is a feature of the present invention. FIG. 4 is a plan view of FIG. 3 viewed from the lower side. In FIGS. 3 and 4, a collection hood 1 having impellers 2 and 2 ′ of a two-stage centrifugal pump driven by a prime mover 5 is provided in the center of the device with its suction port facing downward, and is horizontally held by a supporter 10. In addition, four peripheral vortex generators 9'are arranged so as to surround the four sides at an appropriate height between the floor surface below the hood, and a known blower 13 such as a sirocco fan is installed. It is built in and held by the hanger 10 '. Each of the main members configured in this way has exactly the same structural requirements and functions as those described in the first embodiment. The only basic difference is that there is no eddy current guide plate, and that an air curtain device is added instead. Other than that, as shown in FIGS. 3 and 4, the box body of the collection hood 1 has a quadrangular shape (although it may be a cylindrical shape), and the impeller has a two-stage structure. Hereinafter, these will be described step by step. First 2
Regarding the stepped impeller, it is made into an integrated structure of upper and lower joints, and the suction port leading to the upper step impeller 2 is open in the center of the disk member of the lower step impeller 2 ', and the blades are short and the number of the The centrifugal action of the other side is stronger than that of the lower side. Next, the collection hood 1 is divided into upper and lower two chambers by a partition plate 15 corresponding to the impeller, and the upper chamber is a dedicated chamber for the upper impeller 2 and the duct 8
And the lower chamber is connected to the outside, while the lower chamber has a slit-shaped outlet 4'at the hood outer edge of the impeller as shown in FIG.
Is provided. This outlet may be an equilateral polygon, a fan shape, or an annular shape. And it has become as down blown as an air curtain S ₁ of the exhaust of the lower impeller 2 'in the vertical direction.
In this embodiment, this air curtain is a swirling air curtain due to the impeller rotation. Next, the peripheral vortex generator 9 '
Is between the collection hood 1 and the floor surface, and may be an equilateral polygon other than the one shown, a fan shape, or an annular shape. The air outlet 4 is arranged so as to blow out from the outer periphery of the air curtain S ₁ toward the inside. The fluid outlet adjusting plate 16 provided in the outlet 4
Is adjusted so as to blow out in the same direction as the turning direction of the air curtain S ₁ . Then, the air currents blown out from the four directions merge to form a swirling vortex, creating an air curtain S ₂ of the vortex. Here, the air curtain S ₁ will be described. The airflow may be a conventionally known laminar flow that does not swirl, but it is preferable that the airflow slightly swirl. However, its direction must be the same as that of the vortex air curtain S ₂ . Then, a part of the airflow is drawn in the negative pressure direction at the center of the device, but at the same time, the gas is also drawn in from the outer peripheral direction by the turning centripetal force and descends. And in the moment and each other out in the vortex air curtain S ₂ joined vigorously, is focused in the center become a powerful vortex. Next, regarding the vortex air curtain S _2, the height and position of the vortex air curtain S ₂ may be arbitrary so long as they are blown from the outside of the air curtain S ₁ , and as shown in FIG. Does not have to reach. Therefore, the air curtain S ₁ may be blown so that it is sheared directly from the side. Further, when it is desired to make the air curtain S ₁ sufficiently long, the vortex air curtain S ₂ may be from the floor surface. The wind pressure at the confluence of both air curtains is set to be higher in the vortex air curtain. In addition, the suction pressure of the suction port 3 is set to be higher (negative pressure) than either of these air curtains. In the device configured under the above conditions, 2 in the collection hood 1
When the stepped impeller is driven by the prime mover 5, in the intake air from the intake port 3, the central intake air is sucked from the central hole of the lower stage impeller to the upper side impeller 2 side with strong suction force, and the peripheral intake air is sucked to the lower stage impeller 2'side. Be done. The former is discharged to the outside through the duct 8, and the latter is the swirling air curtain S from the outlet 4 ′ around the hood as described above.
It becomes ₁ and is blown down. Well whereas towards the periphery vortex generators 9 'is blown vortex air curtain S ₂ from the vortex air outlet 4 arranged on the outer periphery of Ekakaten S ₁ as described above. On the other hand, since the central portion of the device strongly sucks gas from the suction port 3, the combined airflow of the air curtains S ₁ and S ₂ becomes a powerful swirling vortex and converges to the central part of the device. As described above in the section “Means for Solving the Problems”, the swirling vortex is accelerated in rotation as it approaches the center, and finally, the artificial tornado S ₃ with a thin columnar shape is formed in the center.
Cause The above is the outline of the gas collecting action. Comparing these series of actions with the case of the liquid region of the first embodiment described above, it is assumed that the air curtain S ₁ corresponds to the external centripetal swirl flow and the vortex air curtain S ₂ corresponds to the vortex flow guide plate. I can see it. However, the former is a mechanical guide method, whereas the latter is a fluid guide method. However, the major feature of both is that the centripetal force is promoted by the participation of the external centripetal vortex. Next, a method of sucking the gas captured in the center will be described. As the tornado S ₃ generated in the center is understood by the formula (2) of the centripetal force, a substance having a larger mass than the surrounding gas tends to be condensed and concentrated in the central portion, so that the trapped airflow is completely collected and removed. However, as shown in FIG. 3, it is more effective to select and suction only the columnar tornado portion from the central portion of the suction port 3 to the upper impeller 2 side. Then, it is preferable to treat these concentrated polluted gases with a conventionally known purifying means separately provided.
Since the capture air flow around over hand tornado is less contaminant is sucked into the lower impeller 2 'side through the annular filter 14 as the orゝor embodiments, also in the manner to be returned to the air curtain S ₁ Good. The above is the outline of the operation functions and effects of the present embodiment. Here, supplementing the above description, the air curtain S ₁ of this embodiment may use a conventionally known air curtain device. In that case, the two-stage impeller need only be one stage on the upper stage side. Further, the collection hood 1 of the present apparatus, the air curtain generator, the outer peripheral vortex generator 9 ', etc. may be respectively connected to a conventionally known blower. In that case, the impeller is unnecessary. However, the atmospheric pressure conditions of each part must be satisfied. When the target air space is low and wide, only the vortex air curtain S ₂ may be used, and when the target air space is low and narrow, only the air curtain S ₁ may be used. However, in this case, it is necessary to increase the turning speed of the air curtain S ₁ . This method can be applied even if the entire device is turned upside down. In that case, the air curtain and the flow of the artificial tornado are only turned upside down. Therefore, the installation method may be selected depending on whether the contaminated fluid is retained up or down.
The above is the outline of the embodiment of the present invention in the gas region.
To summarize the collecting action of this method, first, the ambient gas is taken in as a wake of the air curtain in the first stage, and this air flow is merged with the centripetal swirling flow of the vortex air curtain in the second stage, and rapidly. It is guided to the center and captured as an artificial tornado. Therefore, it is possible to collect and remove pollutants in a wide space area rapidly and efficiently with energy saving, and it is suitable for purification work of a space containing dust, soot, mist, odor, and other pollutant pollutants. It also has extremely beneficial effects on improving the living environment and improving health care.

[0007]

As described above, in the pollutant fluid collecting apparatus of the external centripetal vortex system of the present invention, the collecting hood for sucking the fluid is first provided at the center of the apparatus, and the outer periphery of the apparatus is blown inward at the outer peripheral portion thereof. A vortex flow generator is provided, and a centripetal vortex flow by this is used to draw the fluid around the device as a wake to the inside. With this as a basic component and function, in order to expand the applicable range of this device to the gas / liquid region, by adding a vortex flow guide plate in the liquid region,
In addition, in the gas region, it is used together with an air curtain to accelerate the swirling vortex flow, thereby promoting the centripetal force of the fluid and enhancing the collection work. Therefore, the amount of intake / exhaust is smaller than that of the conventional centrifugal separation or dust collection ventilation system, and various contaminated fluids in the open region can be collected rapidly and efficiently. Moreover, the work of collecting the contaminated fluid over a wide area is completed in a short time, and the power consumption is also reduced to a fraction of a few, which has the effect of extremely saving energy.

[0008]

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment when applied to a liquid region of a device of the present invention.

2 is a sectional view taken along line AA of FIG.

FIG. 3 is a vertical cross-sectional view of one embodiment when applied to the gas region of the device of the present invention.

FIG. 4 is a bottom view seen from the bottom of FIG. 3.

FIG. 5 is an embodiment showing a cross section of the air outlet of the peripheral vortex generator, (1) shows a case where the vortex generator is cylindrical, and (2) shows a case where the angle adjustment type is spot type.

FIG. 6 is an explanatory diagram of three apparent forces in a rotating coordinate system and a guiding action of a vortex flow guide plate.

[Explanation of symbols]

1 Collection Hood 9 Outer Peripheral Vortex Generator 2 Impeller 10 Support Tool 3 Suction Port 11 Suction Pipe 4 Blowout Port 12 Escape Hole 5 Motor 13 Blower 6 Vortex Induction Plate 14 Filter 7 Damper 15 Partition Plate 8 Duct 16 Fluid Blowout Adjustment Plate S _o Contaminated fluid S ₁ Air curtain S ₂ Vortex air curtain S ₃ Artificial tornado N Force of normal direction of envelope surface at point P μ Coefficient of friction between material and envelope surface φ Coriolis force f ₃ direction and tangential direction of envelope surface Angle f'is the component of Coriolis force f _{3 in} the tangential direction of the envelope surface f "Frictional resistance in the tangential direction of the envelope surface f _o Induction force in the tangential direction of the tangential surface of the envelope surface

Claims (3)

[Claims] 1. A collection hood having a fluid suction port at the center of one side in the vertical direction of a hermetically sealed box body and a fluid discharge port on the back or side surface thereof, and a duct-shaped member on the outer peripheral portion thereof. Is formed into an annular shape or a plurality of fan shapes, or isosceles polygonal shapes of quadrangle or more, and a slit-shaped fluid outlet is provided along the member, and an outer peripheral vortex flow generator is provided slightly inward, Is disposed concentrically with the suction surface of the suction port, and the blowing surface is arranged in front of the suction surface so that the swirl swirl angle from the blowing port is directed inward from the tangential direction of the circumference including at least the blowing port, and A polluted fluid collection device, characterized in that a suction amount at a hood side suction port is larger than a blowing amount from a generator. 2. A vortex flow guide plate having one or more spirals, the central portion of which is formed into a substantially enveloped cylinder shape, which is semi-submerged in the water surface and held horizontally, and the member below the water surface of the guide plate is enveloped in the cylinder shape. The part is configured to be deeper from the water surface than the peripheral part, and the collection hood and the outer peripheral vortex generator described in claim 1 are provided under the water, and both the suction port and the blowout port are swirled. 2. The contaminated fluid collecting device according to claim 1, wherein the contaminated fluid collecting device is arranged concentrically toward the guide plate side, and the swirl direction of the outer peripheral vortex flow is the same as the winding direction of the vortex flow guide plate. 3. The apparatus according to claim 1, wherein the entire apparatus is held horizontally, and a peripheral edge portion of the collecting hood has an annular or plural fan shape or a slit-shaped outer edge outlet which forms a substantially equilateral polygon. Are provided concentrically, and a swirling air curtain having a swirling angular velocity of at least 0 is created in the vertical direction from the air outlet, and an outer peripheral vortex generator is arranged at the end edge of the air curtain or the outer peripheral part in the middle. The polluted fluid collecting device according to claim 1, wherein the swirling direction of the outer peripheral vortex is the same as the swirling direction of the air curtain.