Patent Publication Number: US-11383195-B2

Title: Device for capturing particles

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefits of U.S. provisional application Ser. No. 62/938,463 filed on Nov. 21, 2019, and Taiwan application Serial No. 108148409 filed on Dec. 30, 2019, the disclosures of which are incorporated by references herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates in general to a device for capturing particles, and more particularly to the capturing device that can collect effectively particles from an exhaust gas. 
     BACKGROUND 
     For different manufacturing fields such as semiconductor and optoelectronic industries, generation of some acidic and/or alkaline gases are inevitably generated in various manufacturing processes. Generally, a wet scrubber is usually applied to handle these acidic and/or alkaline gases. 
     In the art, a conventional wet scrubber can only provide limited capacity for handling low-concentrated inorganic exhaust gas, micro particles and droplets. In particular, for handling particles and droplets having a diameter less than 2 μm, the conventional wet scrubber is hard to provide a satisfied performance. In some examples, specific particles such as salt granules would be easy to be accumulated and thus jam the device, and from which poor defogging can be foreseen. In addition, with a huge amount of particulate matters emitted into the atmosphere, severe air pollution would occur. In this disclosure, the term “particles” can stand for salt granules soluble in water, solid matters insoluble in water, or a combination of the foregoing two matters. 
     In the art, type of mist eliminator applicable to conventional scrubbers can be classified in Table 1 as follows. 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                   
                 Type 
               
            
           
           
               
               
               
            
               
                   
                 Wire Mesh 
                 Vane/Chevron 
               
            
           
           
               
               
               
               
            
               
                   
                 Fiber demister 
                 demister 
                 demister 
               
               
                   
               
               
                 Occupation 
                 Large space, 
                 Less space, 
                 Less space, 
               
               
                   
                 Independent 
                 inside the 
                 inside the 
               
               
                   
                 installation 
                 scrubber 
                 scrubber 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Upper bound of 
                 ~0.5 
                 m/s 
                 ~2.8 
                 m/s 
                 ~5.0 
                 m/s 
               
               
                 superficial 
                   
                   
                   
                   
                   
                   
               
               
                 velocity 
                   
                   
                   
                   
                   
                   
               
               
                 Pressure drop 
                 200~300 
                 mm H 2 O 
                 100~150 
                 mm H 2 O 
                 50~100 
                 mm H 2 O 
               
               
                 (under the above 
                   
                   
                   
                   
                   
                   
               
               
                 mentioned 
                   
                   
                   
                   
                   
                   
               
               
                 superficial 
                   
                   
                   
                   
                   
                   
               
               
                 velocity) 
                   
                   
                   
                   
                   
                   
               
               
                 Droplets/Particles 
                 &gt;1 
                 μm 
                 &gt;10 
                 μm 
                 &gt;100 
                 μm 
               
               
                 capture range 
               
               
                   
               
            
           
         
       
     
     As listed in Table 1, though the fiber demister can capture droplets/particles having a diameter about 1 μm, yet the superficial velocity through the fiber demister shall not exceed 0.5 m/s. Hence, the fiber demister needs to occupy more space. On the other hand, each of the mesh and vane/chevron demisters is defined with a larger upper bound of superficial velocity and a smaller occupation. However, since only droplets/particles with specific sizes can be surely captured, thus technical difficulty exists in handling the droplets/particles having a diameter less than 10 μm. 
     Currently, to the granular pollutants (droplets/particles) with diameters less than 2 μm and there is a demister thereinside, which is easily blocked by accumulated particles such as salt granules Thus, beside a poor defogging performance, the current wet scrubber also emits a large amount of particulate matters into the atmosphere, and therefore to induce severe air pollution. 
     Accordingly, an improved device for capturing particles that can collect effectively particles from exhaust gases, avoid accumulation, jam or emission of particulate matters to further cause air pollution, and occupy less space is urgent. 
     SUMMARY 
     In one embodiment of this disclosure, a device for capturing particles includes a gas-guiding unit, a mist-elimination unit and a liquid-circulation unit. The gas-guiding unit has a channel with a first end and a second end opposing the first end. The mist-elimination unit is disposed at the second end of the gas-guiding unit. The liquid-circulation unit, disposed under the mist-elimination unit by surrounding the gas-guiding unit, is furnished with a through hole below the gas-guiding unit, a gap being formed between the gas-guiding unit and the liquid-circulation unit. 
     In this embodiment, a gas containing particles is introduced into the channel of the gas-guiding unit via the first end, and then to enter the mist-elimination unit via the second end; wherein, while the gas flows into the channel of the gas-guiding unit, the liquid in the liquid-circulation unit is inhaled into the channel of the gas-guiding unit via the gap to have the particles in the gas to be contained into the liquid so as to form droplets to be captured. After the droplets to be captured are captured by the mist-elimination unit, the liquid formed at the mist-elimination unit by capturing the droplets to be captured flows down into the liquid-circulation unit to reform the liquid in the liquid-circulation unit, and then the liquid is inhaled back to the channel of the gas-guiding unit via the gap. 
     Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present disclosure and wherein: 
         FIG. 1  is a schematic front view of an embodiment of the device for capturing particles in accordance with this disclosure; 
         FIG. 2  is a schematic view showing the embodiment of  FIG. 1  in a state of collecting particles; 
         FIG. 3  is a schematic view of the embodiment of  FIG. 1  applied inside a scrubber; 
         FIG. 4  is a schematic front view of another embodiment of the device for capturing particles in accordance with this disclosure; and 
         FIGS. 5A-5H  demonstrate schematically top views of various exemplary examples in accordance with this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
     Referring to  FIG. 1 , a device for capturing particles  100  includes a gas-guiding unit  10 , a mist-elimination unit  20  and a liquid-circulation unit  30 . In this embodiment, the particles can be soluble salt granules, insoluble solid matters, a combination of the aforesaid two, and/or particles contained in droplets. 
     The gas-guiding unit  10  has a first end  111  and a second end  112  opposing the first end  111 . A channel  11  is formed by connecting spatially the first end  111  and the second end  112 . As shown, in comparison with the second end  112 , the first end  111  is located closer to the liquid-circulation unit  30 . In this embodiment, the channel  11  can be arbitrarily shaped, such as a regular or irregular, circular or polygonal hollow column, and the channel  11  is extended in a direction parallel to a first direction F 1 . 
     The mist-elimination unit  20  is disposed at the second end  112  of the gas-guiding unit  10 . In one embodiment, the mist-elimination unit  20  having a top end plate  21  is used for capturing the liquid carried by the passing gas, in particular by dropping the liquid onto the liquid-circulation unit  30  through gravity. 
     The liquid-circulation unit  30  is disposed to surround, mainly under, the gas-guiding unit  10  and the mist-elimination unit  20 . In this embodiment as shown in  FIG. 1 , the liquid-circulation unit  30  is constructed peripherally to surround both the gas-guiding unit  10  and the mist-elimination unit  20 , with a complete coverage upon the gas-guiding unit  10 . For the liquid-circulation unit  30  to surround the gas-guiding unit  10 , a through hole  31  is furnished to a surface of the liquid-circulation unit  30 , and the gas-guiding unit  10  is located right above the through hole  31 . The mist-elimination unit  20  is disposed on top of the gas-guiding unit  10 . In another embodiment not shown herein, the liquid-circulation unit  30  is furnished with a plurality of through holes  31 , and each of the through holes  31  is furnished thereabove a gas-guiding unit  10  and a mist-elimination unit  20 . 
     A shape of the through hole  31  on the surface of the liquid-circulation unit  30  is not limited to a specific shape, but can be a regular or irregular circle or geometric polygon. The shape of the through hole  31  and the shape of the channel  11  can be different. For example, the through hole  31  and the channel  11  can be both rectangular or circular, or the through hole  31  is shaped to be a circle while the channel  11  is shaped to be a rectangle. 
     As shown in  FIG. 1 , a gap G ranging from 3˜20 mm exists at a junction between the gas-guiding unit  10  and the liquid-circulation unit  30 . 
     In this embodiment, the liquid-circulation unit  30  includes a collecting plate L located under the first end  111  of the channel  11 . In particular, the collecting plate L located below the gap G is parallel to a second direction F 2 , and protrudes into the channel  11  by a length, in which the second direction F 2  is perpendicular to the first direction F 1 . 
     Referring to  FIG. 2 , a gas G 0  flows in the first direction F 1  to enter the channel  11  via the through hole  31  and the first end  111 , and then further to reach the mist-elimination unit  20 . Generally speaking, the gas G 0  can include solid particles S, foggy or liquid first droplets W containing no particles, or second droplets WS containing particles. 
     In this embodiment, the gas G 0  enters the gas-guiding unit  10  via the first end  111 , flows through the channel  11 , and finally enters the mist-elimination unit  20 . When the gas G 0  flows into the channel  11  of the gas-guiding unit  10 , the liquid W 1  in the liquid-circulation unit  30  would be inhaled or sucked automatically into the channel  11  through the gap G to further mix the gas G 0 . Thereupon, the first droplets W containing no particles would grow into the bigger third droplets W′, and the second droplets WS containing particles would grow into bigger droplets to be captured WS′. Part of the third droplets W′ would further send the particles S in the gas G 0  into the droplets to be captured WS&#39; containing particles. 
     In one embodiment, the diameter of the first droplet W and the second droplet WS is smaller than another diameter of the third droplet W′ and the droplet to be captured WS′. In particular, the diameter of the third droplet W′ or the droplet to be captured WS&#39; is no less than 2 μm. 
     Then, after the droplets to be captured WS&#39; and the third droplets W′ are captured at the mist-elimination unit  20 , these captured droplets WS&#39; and W′ would flow down along lateral sides of the mist-elimination unit  20  via gravity, and finally drop into the liquid-circulation unit  30 . After the collection at the liquid-circulation unit  30  to reform the liquid W 1 , the liquid W 1  would be then inhaled into the channel  11  again via the gap G. Thereupon, a circulation of the liquid W 1  is formed. 
     To realize the aforesaid circulation, an internal pressure drop would exist inside the channel  11  of the gas-guiding unit  10 , and the gas G 0  has a specific superficial velocity. Through an appropriate match of the pressure drop and the superficial velocity, the liquid W 1  in the liquid-circulation unit  30  can be inhaled into the channel  11  via the gap G. Thus, while the first droplets W and the second droplets WS enters the channel  11 , the third droplets W′ and the droplets to be captured WS&#39; with larger diameters would be formed inside the channel  11 , and be raised up to enter the mist-elimination unit  20 . 
     It shall be explained that, in  FIG. 2 , the gas G 0  includes the solid particles S, the first droplets W in a foggy or liquid state, and the second droplets WS containing particles. However, according to this disclosure, the aforesaid embodiment can be also applied to the gas G 0  containing the particles S only, and the mist-elimination unit  20  can be used for capturing the particles S from the gas G 0 . 
     In this disclosure, the aforesaid pressure drop is not specifically restrictions but depends on the practical requirements. For example, the pressure drop can be ranging from 80˜250 mmH 2 O, and the gas G 0  entering the channel  11  from the first end  111  can have a superficial velocity ranging from 16˜28 m/s, such that the pressure drop is sufficient for the gas G 0  through the channel  11  without dropping down the liquid W 1  inhaled into the channel  11  through the gap G. 
     If any of the third droplets W′ and the droplets to be captured WS&#39; fails to flow into the liquid-circulation unit  30  but drops directly down into the channel  11  from the mist-elimination unit  20 , the collecting plate L can be used for collecting the droplets W′ or WS&#39; flowing down along the channel  11 . These collected droplets would be recycled back to the channel  11  along with the liquid W 1  inhaled into the channel  11  via the gap G. 
     Referring to  FIG. 3 , in this embodiment, the liquid-circulation unit  30  is disposed inside a scrubber  200 . A ventilation opening  202  is furnished to a top of the scrubber  200 . On a surface of the liquid-circulation unit  30 , a plurality of through holes  31  are provided. Every through hole  31  is designed relevantly to pair a gas-guiding unit  10  located right above the respective through hole  31 , and further one individual mist-elimination unit  20  is provided correspondingly to top the respective gas-guiding unit  10 . 
     In  FIG. 3 , the gas G 0  flows upward to pass through the liquid-circulation unit  30  via these through holes  31 , enters each of the gas-guiding units  10 , and then enters the corresponding mist-elimination units  20  through the respective gas-guiding units  10 . While the gas G 0  flows into the channels  11  of the respective gas-guiding units  10 , the liquid W 1  in the liquid-circulation unit  30  would be inhaled into the channels  11  via the gaps to mix the gas G 0 , such that the first droplets W containing no particles would grow into bigger third droplets W′, and the second droplets WS containing particles would grow into bigger droplets to be captured WS′. In addition, part of the third droplets W′ would further capture the particles S in the gas G 0  so as to form the droplets to be captured WS&#39; containing particles. Then, after the droplets to be captured WS′ and the third droplets W′ are captured by the mist-elimination units  20 , they would flow down to the liquid-circulation unit  30  by gravity along lateral sides of the mist-elimination units  20 . After the drop-down droplets are collected by the liquid-circulation unit  30  to form the liquid W 1 , the liquid W 1  would be then recycled back to the channels  11  through the respective gaps G. 
     It shall be explained that, in  FIG. 3 , the gas G 0  includes the solid particles S, the first droplets W in a foggy or liquid state, and the second droplets WS containing particles. However, according to this disclosure, the aforesaid embodiment can be also applied to the gas G 0  containing the particles S only, and the mist-elimination units  20  can be used for capturing the particles S from the gas G 0 . 
     Referring to  FIG. 4 , in another embodiment of this disclosure, the device for capturing particles  110  includes a gas-guiding unit  10 , a mist-elimination unit  20  and a liquid-circulation unit  30 . 
     In this embodiment, besides having a top end plate  21 , the mist-elimination unit  20  further has a packing material  40  regularly or irregularly disposed inside the mist-elimination unit  20 . According to this disclosure, the type, material and shape of the packing material  40  are not specifically restrictions. For example, the packing material  40  can be chevron plates, regular or irregular packed structured packing, or random packing. The packing material can be made of plastics, metal or a combination of the aforesaid materials. The packing material  40  can be different structures according to sizes of the droplets to be captured. For example, the packing material  40  can be a wire mesh, a plate, or a combination of the aforesaid two. 
     In this embodiment, the method for capturing droplets and particles contained inside the droplets can be the same as that for the embodiment of  FIG. 2 . Therefore, there is no need to repeat the details. Importantly, the mist-elimination unit  20  of  FIG. 4  and that of  FIG. 2  might be slightly different, but, anyway, both of them can be used for capturing particles from the gas G 0 . 
     Referring to  FIGS. 5A ˜ 5 H, each of the devices for capturing particles  100 A˜ 100 H includes a gas-guiding unit  10 , a mist-elimination unit  20 A˜ 20 H and a liquid-circulation unit  30 . As shown in  FIG. 5A ˜ 5 H, the major difference among these devices for capturing particles  100 A˜ 100 H is the pattern of the mist-elimination unit  20 A˜ 20 H. The pattern for the mist-elimination unit  20 A˜ 20 H according to this disclosure can be rectangles, circles, ellipses, regular polygons, irregular polygons and arbitrary combinations of aforesaid shapes with different dimensions. 
     In summary, in the device for capturing particles provided by this disclosure, with the appropriate pressure drop in the channel of the gas-guiding unit and the appropriate superficial velocity of the gas containing particles, so that liquids and gases inside the channel can be well mixed to produce a great amount of larger-size droplets or foggy drops. Then, with the mist-elimination unit to capture these larger-size droplets and foggy drops, the particles in the gas can be captured. In addition, the superficial velocity of the gas can be varied to control the size of the mixed droplets, such that the capture ratios of collecting the particles can be relevantly controlled. 
     With respect to the above description then, it is to be realized that the dimensional relationships for the parts of the disclosure, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present disclosure.