Abstract:
An atomizing apparatus for the production of powders or spray deposits, having an atomization device for receiving a liquid stream of molten metal or metal alloy to be atomized; at least two primary atomization gas jets for directing an atomization gas at an angle into the liquid stream in an atomization zone at an impinging point of the atomization jets to break the stream into atomized droplets; and at least two secondary jets for direction a controlling fluid at a pressure, flow rate and direction, the jets being aimed at the atomization gas jet or into the atomization zone, wherein said secondary jets control a backpressure generated by the primary atomization gas jets. The apparatus also includes means for in-situ controlling at least one of the relative positions among the primary atomization jets, the secondary jets, and the liquid delivery nozzle.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of application Ser. No. 09/388,494, filed Sep. 2, 1999, now abandoned entitled “Atomizing Apparatus &amp; Process”, which was a divisional application of parent patent application Ser. No. 08/751,970, filed Nov. 19, 1996, now U.S. Pat No. 5,993,509, issued Nov 30, 1999. The aforementioned application(s) are hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a method and apparatus for atomizing a liquid stream of metal or metal alloy. This invention relates to producing powders as well as to spray deposition process. 
     DESCRIPTION OF RELATED ART 
     For both powder production and spray deposition process, there are traditionally two kinds of atomization devices for atomizing a liquid stream of metal or metal alloys coming out of the liquid delivery nozzle into a spray of droplets. One is the “Free Fall” type of design, in which the stream of metal or metal alloy is atomized at a certain distance away from the exit of the liquid delivery nozzle. The other design is the “Confined” type of design, in which the stream of metal or metal alloy is atomized at the exit of the liquid delivery nozzle. The Confined type of atomization device gives more efficient and uniform transfer of energy from atomization gas to the stream of metal or metal alloy, due to the shorter distance between the atomization gas and the stream of metal or metal alloy and prefilming of the molten metal or metal alloy over the end of the liquid delivery nozzle. However, since the impingement point of the atomization gas is close to the exit of the liquid delivery nozzle, the molten metal or metal alloy is easier to freeze-up inside the liquid delivery nozzle, which blocks further atomization. The Free-Fall type atomization device doesn&#39;t have the freeze-up problem; however, the atomization efficiency is reduced compared to the Confined type of atomization device, resulting in coarser atomized powder and coarser microstructures due to a lower cooling rate. 
     During atomizing, a backpressure is created by the impingement of the atomization gas jets around the atomization zone below the exit of the liquid deliver nozzle. The backpressure has two effects. One effect is generating backsplash during atomization, in which molten metal or metal alloy is backsplashed upwards away from the atomization zone. The backsplashed molten metal or metal alloy may either deposit back onto the atomization device and block further atomization, or become coarse and irregular shaped powders, which may not be desired. Another effect is influencing the atomization rate, or the flow rate of the metal or metal alloy stream coming out of the liquid delivery nozzle. In the extreme, a complete blockage of the metal or metal alloy stream from coming out of the liquid delivery nozzle is likely to happen due to the backpressure. The present invention provides a method of atomizing and an atomizing apparatus to control the backpressure. 
     During atomizing, the intensities and directions of the atomization gas jets affect the atomization characteristics, such as atomization efficiency, atomization rate, the cooling rate of atomized droplets, trajectories and velocities of atomized droplets, shapes and sizes of atomized droplets, the spatial flux distribution of atomized droplets, etc. The intensities of the atomization gas jets are manipulated through controlling the pressure and/or flow rate of the atomization gas. However, the directions of the atomization gas jets are fixed by the design of the atomization device. In U.S. Pat. No. 4,779,802, and U.S. Pat. No. 4,905,899, the atomization device is scanned to control the directions of the atomization gas jets. The present invention provides a method of atomizing and an atomizing apparatus to control both the intensities and directions of the atomization gas jets. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention is to control the created backpressure, which, in turn, controls the backsplash and the atomization rate, or the flow rate of the metal or metal alloy stream coming out of the liquid delivery nozzle. Another aspect of the present invention is to control the atomization characteristics by controlling the intensities and directions of the atomization gas jets, which, in turn, controls the droplet characteristics, such as the variations of size, shape, temperature, heat content and microstructure of droplets, etc., and/or powder characteristics, such as powder size distribution, the powder shape distribution, the microstructure variations of powders, etc., and/or spray-deposit characteristics, such as the morphology, macrostructures and microstructures of the deposit, etc. 
     According to one aspect of the present invention there is provided a method of atomizing a liquid stream of metal or metal alloy consisting of the steps of: 
     teeming a stream of molten metal or metal alloy into an atomization device, 
     atomizing the stream with atomization gas to form droplets of metal or metal alloy, and 
     directing controlling fluid at an atomization gas jets or at atomization zone to control the backpressure and, if desired, the intensities and directions of the atomization gas jets. 
     Preferably the atomization gas issues from first jets, and the controlling fluid issues from second jets directed at the atomization gas jets or at the atomization zone. The intensity, flow rate and pressure of the secondary jets are preset to control or are in-situ adjusted to in-situ control the backpressure and/or the intensities and directions of the atomization gas jets. The method may be for the production of powder to control the powder characteristics. Alternatively, the method may be for the production of spray deposits to control the deposit characteristics. Alternatively, the secondary jets may be so arranged, through which solid particles or whiskers of the same or different composition (either metallic or non-metallic) of the metal to be atomized are introduced into the controlling fluid which acts as a transport vehicle for the particles or whiskers to be co-deposited with the atomized droplets to form spray-deposited composite materials. Alternatively, the particles or whiskers are introduced from above the secondary jets, which also gives a mixture of the particles or whiskers with the spray to form spray-deposited composite materials. Suitably, the controlling fluid is an inert gas, such as Argon, Helium and Nitrogen, or air. Alternatively, the controlling fluid may be cryogenic liquefied gas which changes to a gaseous phase upon heating by the metal or metal alloy stream. The atomization gas is suitably an inert gas, such as Argon, Helium and Nitrogen, or Air. The selection of gases is made in accordance with the compatibility with the liquid metal or metal alloy to be atomized. 
     According to another aspect of the invention there is provided an atomizing apparatus consisting of an atomization device for receiving a stream of molten metal or metal alloy to be atomized, means for directing atomization gas at the liquid stream to atomize the stream, and means for directing controlling fluid at atomization gas jets or at an atomization zone to control the backpressure and/or the atomization characteristics. In the preferred arrangement, the means for directing the atomization gas consists of primary jets and the means for directing the controlling fluid consists of secondary jets directed at the atomization gas jets or at the atomization zone. The intensity, flow rate and pressure of the secondary jets are preset to control or are in-situ adjusted to in-situ control the backpressure and/or the intensities and directions of the atomization gas jets. Suitably, the controlling fluid is an inert gas, such as Argon, Helium and Nitrogen, or air. Alternatively, the controlling fluid may be cryogenic liquefied gas which changes to a gaseous phase upon heating by the metal or metal alloy stream. The atomization gas is suitably an inert gas, such as Argon, Helium and Nitrogen, or air. The selection of gases is made in accordance with the compatibility with the liquid metal or metal alloy to be atomized. 
     Alternatively, the apparatus may be used to produce spray deposits on a suitable collector. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a schematic sectional side elevation of a gas atomizing apparatus according to the invention. 
     FIG. 2 is a schematic side elevation of apparatus for producing powders including the atomizing apparatus according to the invention together with an alternative base arrangement. 
     FIG. 3 is a Process Map of P u  vs. P 1  for R=15 mm for water atomization. 
     FIG. 4 is a Process Map of P u  vs. P 1  for R=20 mm for water atomization. 
     FIG. 5 is a Process Map of P u  vs. P 1  for R=25 mm for water atomization. 
     FIG. 6 shows the atomization phenomena for region A in the Process Map of P u  vs. P 1 . 
     FIG. 7 shows the atomization phenomena for region B in the Process Map of P u  vs. P 1 . 
     FIG. 8 shows the atomization phenomena for region C in the Process Map of P u  vs. P 1 . 
     FIG. 9 shows the atomization phenomena for region D in the Process Map of P u  vs. P 1 . 
     FIGS.  10 ( a ) through  10 ( i ) show the distributions of the powder sizes for each set of process parameters with the application of controlling fluid technique. 
     FIG. 11 shows the mass distribution of powders produced with the application of controlling fluid technique. 
     FIGS.  12 ( a ) through  12 ( g ) show the variations of the intensities and directions of the atomization gas jets as the pressure of the controlling fluid varies. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1, an atomizing apparatus for gas atomizing liquid metal or alloy is shown consisting of a refractory or refractory lined crucible or tundish ( 1 ) for containing liquid metal or metal alloy ( 2 ). The crucible ( 1 ) has a liquid delivery nozzle ( 3 ) to provide a liquid metal or metal alloy stream ( 4 ) of a desired diameter. The liquid metal or metal alloy stream ( 4 ) teems into a central opening in a primary gas atomization device ( 5 ) which causes a number of atomization gas jets ( 6 ) to be directed at the liquid metal or metal alloy stream ( 4 ) so as to atomize the stream into a spray of atomized droplets ( 7 ). The primary atomization gas jets ( 6 ) preferably spray Nitrogen, Argon or Helium, but air may also be used. The atomizing assembly also consists of a secondary controlling fluid jets device ( 8 ), disposed upstream of the primary atomization gas jets ( 6 ), containing a number of controlling fluid jets ( 9 ) which apply Nitrogen, Argon, Helium, air, or cryogenic liquefied gas to the atomization gas jets ( 6 ) or to the atomization zone ( 10 ). The pressure and flow rate of the controlling fluid applied at the secondary controlling fluid jets device ( 8 ) is controlled to manipulate the backpressure and the atomization characteristics. The controlling can be made in-situ during atomizing. 
     The atomization characteristics, such as mass flux distribution, droplet size distribution and droplet velocity, can be detected by the sensors, such as Phase-Doppler Anemometry (PDA) ( 11 ), and be fed back to the central process unit, such as computer ( 12 ). The central process unit ( 12 ) then sends a command after calculation to actuate the position driver of primary gas atomization device ( 13 ) and/or position driver of secondary controlling fluid jets device ( 14 ) to in-situ control the relative positions among the primary atomization device ( 5 ), the secondary controlling fluid jets device ( 8 ), and/or the liquid delivery nozzle ( 3 ). 
     FIG. 2 shows the apparatus of FIG. 1 as applied to powder production apparatus. In this figure, the crucible/tundish metal dispensing system ( 15 ) with liquid metal ( 16 ), the gas atomization device ( 17 ) and the controlling fluid jets device ( 18 ) are positioned on a spray chamber ( 21 ). Atomization gas is supplied to the gas atomization device ( 17 ) via an inlet pipe ( 19 ), and controlling fluid is supplied to the controlling fluid jets device ( 18 ) via a separate inlet pipe ( 20 ). At the base of the spray chamber is a powder collection vessel ( 22 ), the chamber additionally containing a gas exhaust pipe ( 23 ). The flow rate of the controlling fluid applied at the secondary controlling fluid jets device ( 18 ) is controlled by activating the controlling fluid control valve ( 25 ) via a current to pneumatic pressure (P/I) converter ( 24 ). The controlling can be made in-situ during atomizing. The atomization characteristics, such as mass flux distribution, droplet size distribution, and droplet velocity, can be detected by the sensors, such as Phase-Doppler Anemometry (PDA) ( 26 ) and be fed back to the central process unit, such as computer ( 27 ). The central process unit ( 27 ) then sends a command after calculation to actuate the position driver of primary gas atomization device ( 28 ) and/or position driver of secondary controlling fluid jets device ( 31 ) to in-situ control the relative positions among the atomization device ( 5 ), the secondary controlling fluid jets device ( 8 ), and/or the liquid delivery nozzle ( 3 ). The horizontal and vertical movements of the primary atomization device ( 5 ) are controlled by one set of the horizontal actuator ( 29 ) and vertical actuator ( 30 ), respectively. The horizontal and vertical movements of the secondary controlling fluid jets device ( 8 ) are controlled by another set of the horizontal actuator ( 32 ) and vertical actuator ( 33 ), respectively. 
     During atomizing, the backpressure is controlled by the controlling fluid jets device, which controls the extent of the backsplash and the atomization rate, or the flow rate of the metal or metal alloy stream coming out of the liquid delivery nozzle. In addition, the intensities and directions of the atomization gas jets are controlled by the controlling fluid jets device, which controls the atomization characteristics. Consequently, the droplet characteristics, such as the variations of size, shape, temperature, heat content and microstructure of droplets, etc., and powder characteristics, such as powder size distribution, the powder shape distribution, the microstructure variations of powders, etc., are controlled. The pressure and/or flow rate of the controlling fluid are in-situ adjustable during atomizing to in-situ control the backpressure and/or the intensities and directions of the atomization gas jets. 
     EXAMPLE OF THE USE OF NITROGEN GAS AS THE CONTROLLING FLUID IN THE ATOMIZATION OF WATER 
     The example below illustrates the principles of selecting the process parameters by illustrating the conditions used for the atomization of water employing the controlling fluid technique. P u  is the nitrogen gas pressure used for the controlling fluid jets device, P 1  is the nitrogen gas pressure used for the gas atomization device, and R is the vertical distance between the controlling fluid jets device and gas atomization device. 
     The principles of selection of R is discussed below for this example. When R&gt;25 mm, the controlling fluid jets device was too far from the gas atomization device, so that when the controlling fluid became large enough to suppress the backpressure, the water was atomized by the controlling fluid also, which rendered the controlling fluid jets device meaningless. When R&lt;5 mm. As a result, the R needed to be limited between 5 mm and 25 mm in this example. 
     The principles of selection of P u  and P 1  is discussed below for this example. FIGS. 3,  4 , and  5  show the Process Maps of P u  vs. P 1  for R=15, 20, and 25 mm, respectively. In the figures, each map is divided into Regions A, B, C, and D. The effects of the controlling fluid jets device on the atomization characteristics of water for each Region are shown schematically in FIGS. 6 to  9 , separately. In Region A, the controlling fluid jets are not able to suppress the backpressure completely. In Regions B and C, the backpressure is suppressed by the controlling fluid jets device; however, the water stream between the controlling fluid jets device and gas atomization device in Region C is more turbulent than that in Region B. Region D is the transition region between Region A and Regions B or C. In summary, Regions B and C are the regions suitable for water atomization in this example. 
     EXAMPLE OF THE USE OF NITROGEN GAS AS THE CONTROLLING FLUID 
     IN THE PRODUCTION OF Pb—Sn POWDERS 
     The example below illustrates the conditions used for the production of Pb-50 wt % Sn powders. Table 1 lists the process parameters used for the production of powders. P u  is the nitrogen gas pressure used for the controlling fluid jets device, P 1  is the nitrogen gas pressure used for the gas atomization device, and R is the vertical distance between the controlling fluid jets device and gas atomization device. 
     
       
         
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 P 1   
                 P u   
                 R 
               
               
                   
                 Experimental No. 
                 (Mpa) 
                 (Mpa) 
                 (mm) 
               
               
                   
                   
               
             
             
               
                   
                 A035 
                 0.40 
                 0.20 
                 25 
               
               
                   
                 A036 
                 0.30 
                 0.30 
                 25 
               
               
                   
                 A037 
                 0.20 
                 0.20 
                 15 
               
               
                   
                 A038 
                 0.30 
                 0.20 
                 20 
               
               
                   
                 A039 
                 0.20 
                 0.30 
                 20 
               
               
                   
                 A040 
                 0.40 
                 0.40 
                 20 
               
               
                   
                 A042 
                 0.30 
                 0.40 
                 15 
               
               
                   
                 A043 
                 0.40 
                 0.30 
                 15 
               
               
                   
                 A044 
                 0.20 
                 0.40 
                 25 
               
               
                   
                   
               
             
          
         
       
     
     Table 2 lists the first and second peak values of the distribution of powder sizes. For the condition of P u =0, P 1 =0.30 MPa and R=20 mm, the backsplash created due to the backpressure was so severe that nearly no atomization took place, which resulted in no powder being produced. However, when the controlling fluid jets device was switched on and P u  was set to be 0.20 MPa, the backpressure was so controlled that backsplash was eliminated and the powder was produced as illustrated by the A038 production. Using controlling fluid to control the backpressure is demonstrated. 
     
       
         
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                 First Peak 
                 Second Peak 
                 Second Peak/ 
               
               
                 Experimental No. 
                 μm 
                 μm 
                 First Peak 
               
               
                   
               
             
             
               
                 A035 
                 177-250 
                 53-74 
                 0.36 
               
               
                 A036 
                 250-420 
                 53-74 
                 0.24 
               
               
                 A037 
                 250-420 
                  88-105 
                 0.31 
               
               
                 A038 
                 250-420 
                 53-74 
                 0.18 
               
               
                 A039 
                 250-420 
                 53-74 
                 0.17 
               
               
                 A040 
                 250-420 
                 53-74 
                 0.17 
               
               
                 A042 
                 177-250 
                 53-74 
                 0.34 
               
               
                 A043 
                 177-250 
                 53-74 
                 0.75 
               
               
                 A044 
                 250-420 
                 53-74 
                 0.29 
               
               
                   
               
             
          
         
       
     
     FIG. 10 shows the distributions of the powder sizes for each set of process parameters. It is shown that the first and second peak values of the distribution of powder sizes are controllable by varying the pressure and position of the controlling fluid jets. FIG. 11 shows the mass distribution of powders are controllable by varying the pressure and position of the controlling fluid jets. Using controlling fluid to control the atomization characteristics is demonstrated. 
     FIG. 12 shows the variations of the intensities and directions of the atomization gas jets as P u  varies. It is shown that the intensity of the atomization gas jets for P u =0.14 MPa is relatively small compared to that for P u =0.40 MPa, which gives a more scattered spray for the former. In addition, the direction of the atomization gas jets for P u =0.14 MPa is also different from that for P u =0.40 MPa, and the former has a larger included angle for the spray cone. Using controlling fluid to control the intensities and directions of the atomization gas jets is demonstrated. 
     A further application of the use of controlling fluid is in the production of spray deposits. In the production of spray deposits, liquid metal or metal alloy is atomized into a spray of droplets, which consists of a mixture of fully liquid, semi-solid/semi-liquid and solid particles. The resulting spray of metal droplets is directed onto an appropriate collector, where a preform is continuously deposited by these droplets. The process is essentially a rapid solidification technique with an integrated gas-atomizing/spray depositing operation. Deposits with different morphologies, such as tubes, billets, flat products, coated articles, etc., can be produced by manipulating the movement and shape of the collector, and by, in many situations, moving the spray itself. Such products can either be used directly or can be further processed normally by hot or cold working with or without the collector. 
     During atomizing, the backpressure is controlled by the controlling fluid jets device, which controls the extent of the backsplash and the atomization rate, or the flow rate of the metal or metal alloy stream coming out of the liquid delivery nozzle. In addition, the intensities and directions of the atomization gas jets are controlled by the controlling fluid jets device, which controls the atomization characteristics. Consequently, the droplet characteristics, such as the variations of size, shape, temperature, heat content and microstructure of droplets, etc., and spray-deposit characteristics, such as the morphology, macrostructures and microstructures of the deposit, etc., are controlled. The pressure and/or flow rate of the controlling fluid are in-situ adjustable during atomizing to in-situ control the backpressure and/or the intensities and directions of the atomization gas jets. Alternatively, the secondary controlling fluid jets may be so arranged, through which solid particles or whiskers of the same or different composition (either metallic or non-metallic) of the metal to be atomized are introduced into the controlling fluid which acts as a transport vehicle for the particles or whiskers to be co-deposited with the atomized droplets to form spray-deposited composite materials. Alternatively, the particles or whiskers are introduced from above the controlling fluid jets, which also gives a mixture of the particles or whiskers with the spray to form spray-deposited composite materials. 
     EXAMPLE OF THE USE OF NITROGEN GAS AS THE CONTROLLING FLUID IN THE PRODUCTION OF SPRAY-DEPOSITED PB-50%SN ALLOY PREFORMS 
     The example below illustrates the conditions used for the production of Pb-50%Sn spray-deposited preforms. Table 3 lists the atomization process parameters used to produce Pb-50% Sn powder employing the controlling fluid technique. 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                   
                   
                 Example 
                 Example 
               
               
                 Process Parameter 
                 Symbol 
                 A 
                 B 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Metal Dispensing Temperature (° C.) 
                 T spray   
                 266 
                 266 
               
               
                 Metal Flow Rate (Kg/sec) 
                 J melt   
                 0.18 
                 0.18 
               
               
                 Atomization gas pressure (MPa) 
                 P 1   
                 0.30 
                 0.30 
               
               
                 Controlling fluid pressure 
                 P u   
                 0.00 
                 0.20 
               
               
                 Vertical distance between the 
                 R 
                 20 
                 20 
               
               
                 controlling fluid jets device 
               
               
                 and gas atomization device (mm) 
               
               
                 Spray Height (mm) 
                 Z 
                 600 
                 600 
               
               
                 Results 
                   
                 Process 
                 Process 
               
               
                   
                   
                 Failed 
                 Succeeded 
               
               
                   
               
             
          
         
       
     
     In Example A, only atomization gas was used in the conventional manner of production of spray-deposited preforms. However, since the backsplash created due to the backpressure was so severe that nearly no atomization took place, which resulted in no preform being produced. In Example B, controlling fluid of Nitrogen was introduced by the controlling fluid jets device above the main atomization gas jets. Otherwise, the atomizing was carried out under identical conditions to Example A. The backpressure was so controlled by the controlling fluid jets device that backsplash was eliminated and a spray-deposited preform was produced. Using controlling fluid to control the backpressure in the spray deposition process was demonstrated. 
     Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 Reference Number of Elements In The Drawings 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 crucible or tundish 
               
               
                 2 
                 liquid metal or metal alloy 
               
               
                 3 
                 liquid delivery nozzle 
               
               
                 4 
                 liquid metal or metal alloy stream 
               
               
                 5 
                 primary gas atomization device 
               
               
                 6 
                 primary atomization gas jets 
               
               
                 7 
                 a spray of atomized droplets 
               
               
                 8 
                 a secondary controlling fluid jets 
               
               
                   
                 device 
               
               
                 9 
                 controlling fluid jets 
               
               
                 10 
                 atomization zone 
               
               
                 11 
                 sensors, such as Phase-Doppler 
               
               
                   
                 Anemometry (PDA) 
               
               
                 12 
                 central process unit, such as 
               
               
                   
                 computer 
               
               
                 13 
                 position driver of primary gas 
               
               
                   
                 atomization device 
               
               
                 14 
                 position driver of secondary 
               
               
                   
                 controlling fluid jets device 
               
               
                 15 
                 crucible/tundish metal dispensing 
               
               
                   
                 system 
               
               
                 16 
                 liquid metal 
               
               
                 17 
                 the gas atomization device 
               
               
                 18 
                 the secondary controlling fluid 
               
               
                   
                 jets device 
               
               
                 19 
                 inlet pipe 
               
               
                 20 
                 separate inlet pipe 
               
               
                 21 
                 a spray chamber 
               
               
                 22 
                 a powder collection vessel 
               
               
                 23 
                 a gas exhaust pipe 
               
               
                 24 
                 a current to pneumatic 
               
               
                   
                 pressure(P/I) converter 
               
               
                 25 
                 controlling fluid control valve 
               
               
                 26 
                 sensors, such as Phase-Doppler 
               
               
                   
                 Anemometry (PDA) 
               
               
                 27 
                 central process unit, such as 
               
               
                   
                 computer 
               
               
                 28 
                 position driver of primary gas 
               
               
                   
                 atomization device 
               
               
                 29 
                 horizontal actuator of primary 
               
               
                   
                 gas atomization device 
               
               
                 30 
                 vertical actuator of primary gas 
               
               
                   
                 atomization device 
               
               
                 31 
                 position driver of secondary 
               
               
                   
                 controlling fluid jets device 
               
               
                 32 
                 horizontal actuator of secondary 
               
               
                   
                 controlling fluid jets device 
               
               
                 33 
                 vertical actuator of secondary 
               
               
                   
                 controlling fluid jets device