JP2016013514A - Method and device for generating dry powder and spray device assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for generating dry powders where the dry powders are generated by drying powders suspended in a liquefied gas without agglomeration and to provide a spray device assembly used in the device.SOLUTION: A gas (G) is discharged from a nozzle or an orifice (3). A negative pressure region or a pressure reduction region (4) is formed at the downstream of the nozzle or the orifice (3). A suspension (S) of a liquefied gas (LG) and powders (P) is supplied to the negative pressure region or the pressure reduction region (4). Thus, a plurality of droplets (S1) of the suspension (S) are formed, the liquefied gas (LG) is vaporized by heating the droplets (S1), the powders (P) are heated to around normal temperature and then the agglomeration of the powders (P) is prevented by the volume expansion of the droplets (S1) accompanying the vaporization of the droplets (S1).

Description

  The present invention relates to a dry powder production method and apparatus for producing a dry powder by drying a powder suspended in a liquefied gas so as not to agglomerate. The present invention also relates to a spray device assembly used in the dry powder production method and apparatus.

  Japanese Patent Laid-Open No. 2003-1129 is characterized in that a suspension in which a material to be pulverized is dispersed in a liquefied inert gas is pulverized by a medium stirring mill, and then the liquefied inert gas is vaporized to obtain a dry powder. The manufacturing method of fine powder is disclosed. In order to recover the powder suspended in the liquefied gas in this way as a dry powder, the suspension is left in the atmosphere without applying a special drying process, or the suspension is physically removed. The liquefied gas was evaporated by, for example, stirring. However, generally, since the boiling point of the liquefied gas is extremely low, the powder becomes low temperature when the liquefied gas evaporates. As a result, moisture in the atmosphere condenses on the powder, causing the powder to aggregate.

  In claim 7 of JP 2000-515901 A, first, a binder and a crosslinking agent and optionally other conventional auxiliaries and additives are dissolved or dissolved in a liquefied gas or a supercritical gas, preferably supercritical carbon dioxide. The powder coating material according to any one of claims 1 to 6, wherein the powder coating material is obtained by producing powder particles by suspending and subsequently spraying. Further, in claim 11 of the same publication, in the method for producing a powder coating material according to claim 7, first, a binder and a cross-linking agent and optionally other conventional auxiliaries and additives are used as a liquefied gas or a supercritical gas. Describes a method for producing a powder coating, characterized in that powder particles are produced by dissolving or suspending in supercritical carbon dioxide and subsequently spraying. As described in these claims, these inventions are aimed at producing composite particles in which a plurality of components (particles) such as a binder, a crosslinking agent, an auxiliary agent and an additive are aggregated. In order for the powder coating material to function, it is necessary that these plural components (particles) exist as aggregates. Therefore, the powder particles produced by these inventions are aggregated particles.

  There is a spray drying method as a method for producing the aggregated particles. The starting material of the spray drying method is a solution or suspension, and by spraying these solutions or suspensions, a large number of droplets are generated, and the components (particles) confined in each droplet are agglomerated, Granulate as aggregates. In this sense, an apparatus for carrying out the spray drying method can be called a granulator. The size of the agglomerates granulated here depends on the droplet size.

  According to claim 15 of JP-T-8-503163, an apparatus for carrying out the method according to any one of claims 1 to 14 is used for 1) a powder storage container or a powder suspension. Having an insulated storage container, 2) a spray nozzle, 3) an optionally thermally insulated conduit coupling the storage container with the spray nozzle, and 4) a device for supplying the amount of heat necessary for evaporation of the liquid gas droplets An apparatus for forming a powder coating is described. Since the invention described in claims 1 to 14 of the publication is a method of forming a powder coating, it is supplied by an apparatus for supplying heat necessary for evaporation of liquid gas droplets in claim 15 of 4) It is understood that the amount of heat is used to agglomerate multiple components (particles) of the powder coating within each droplet.

Japanese Patent Laid-Open No. 2003-1129 Special Table 2000-515901 Japanese National Patent Publication No. 8-503163

  An object of the present invention is to provide a dry powder production method and apparatus for producing a dry powder by drying a powder suspended in a liquefied gas so as not to agglomerate.

  Another object of the present invention is to provide a spray device assembly for use in the aforementioned dry powder production method and apparatus.

  In the method for producing a dry powder of the present invention, gas is discharged from a nozzle or orifice, a negative pressure region or a reduced pressure region is generated downstream of the nozzle or orifice, and a liquefied gas and a powder are produced in the negative pressure region or the reduced pressure region. To produce a large number of droplets of the suspension, to heat the droplets to vaporize the liquefied gas in the droplets, to heat the powder to near room temperature, Aggregation of the powder is prevented by volume expansion of the droplet accompanying vaporization of the droplet.

  The method for producing a dry powder according to the present invention is characterized in that the liquefied gas is liquid nitrogen, and the volume of the droplet changes about 700 to 800 times.

  The dry powder production method of the present invention is also characterized in that the flow rate of the gas discharged from the nozzle or orifice is about 50 to 60 m / s.

  The dry powder production method of the present invention is characterized in that the gas discharged from the nozzle or orifice is a heated nitrogen gas.

  The dry powder producing apparatus of the present invention comprises a spray nozzle or a venturi-nozzle that discharges a gas from a nozzle or an orifice and creates a negative pressure region or a reduced pressure region downstream of the nozzle or orifice, and the spray nozzle or venturi. A drying chamber, a raw material hopper, a raw material hopper, and the negative pressure region or reduced pressure, which are formed downstream of the nozzle and surround the negative pressure region or the reduced pressure region; And a feeding nozzle that supplies the suspension to the negative pressure region or the reduced pressure region in the drying chamber, and a filter that captures the powder. A dust collector, a part of the gas sucked into the dust collector, an exhaust valve, and a part of the gas sucked into the dust collector into the spray nozzle or ventu A first reflux passage for refluxing the nozzle, a spray blower for pressurizing the gas flowing through the first reflux passage and supplying the pressurized gas to the spray nozzle or venturi nozzle; and the spray blower is the spray nozzle or And a temperature raising heater for heating the gas supplied to the venturi nozzle.

  The dry powder production apparatus of the present invention is characterized in that a powder recovery chamber is defined in a lower portion of the drying chamber.

  The dry powder generating apparatus of the present invention also includes a second reflux passage for refluxing a part of the gas sucked into the dust collector to the drying chamber at a position higher than the powder recovery chamber, The second reflux passage is provided with a reflux fan that pressurizes the gas flowing through the second reflux passage and supplies the gas to the drying chamber.

  The dry powder producing apparatus of the present invention is also characterized by having a temperature raising heater for heating the gas supplied from the second reflux passage to the drying chamber.

  The spray device assembly according to the present invention has a hollow container whose upper surface and side surfaces are closed and whose lower surface is opened, and a gas inflow port outside the upper surface of the hollow container. A spray nozzle or a venturi nozzle attached to the hollow container so as to have a gas outlet, and a suspension of liquefied gas and powder fixed to the side surface of the hollow container from the outside of the hollow container A raw material hopper, and a charging nozzle attached to the hollow container so as to supply the suspension accommodated in the raw material hopper to a lower part of the discharge port of the spray nozzle or the venturi nozzle; Have

  The spray device assembly of the present invention is characterized in that the spray nozzle or the venturi nozzle has a tapered passage having a diameter reduced from the gas inlet to the gas outlet.

  According to the method for producing a dry powder of the present invention, particles existing in a suspended state in a liquefied gas can be taken out into the gas phase while maintaining the form as much as possible. In other words, it is intended to change (vaporize) only the liquid phase in which the particles are present. That is, by spraying a suspension of liquefied gas and particles in the form of fine droplets, the liquefied gas is vaporized instantaneously, and agglomeration of particles is prevented by utilizing the energy of rapid volume expansion at this time. These particles can be recovered in the form present in the liquid phase as much as possible. Here, as an example of volume expansion, when the liquefied gas is liquid nitrogen, the volume change is about 650 times. The time unit required for the volume expansion of liquid nitrogen is suitably measured in milliseconds. The method for producing a dry powder of the present invention is not intended to form a new powder from a substance dissolved in a liquid phase or to produce secondary particles (aggregates). The method for producing a dry powder of the present invention is intended to prevent dry aggregation and to recover individual particles in a form as close as possible to the form in the liquid phase.

  Therefore, according to the method for producing a dry powder of the present invention, by spraying a powder suspended in a liquefied gas in a suspension (slurry) state, a large number of fine droplets of the suspension are generated. Then, these droplets can be heated to instantly vaporize the liquefied gas in the droplets. Thereby, drying time can be shortened. In addition, since the powder can be heated to near room temperature and the volume expansion of the droplets accompanying the vaporization of the droplets can prevent the powder from agglomerating, there is no need for a further step of pulverizing the agglomerated powder. A dry powder can be obtained immediately. Here, normal temperature means 5 to 35 degrees Celsius, but if the moisture in the air is prevented from condensing on the powder, the formation of aggregates can be prevented, so that the formation of aggregates can be prevented. It is understood that the powder is not limited to this normal temperature range, and the powder may be heated to about room temperature in the place where the method of the present invention is performed.

  Moreover, according to the dry powder production | generation apparatus of this invention, since powder can be dried in the sealed space closed from the outside, contamination of dry powder can be prevented. Further, when liquid nitrogen is used as the liquefied gas, the powder can be dried in a nitrogen atmosphere, so that the oxidation of the powder can be prevented. Furthermore, since the dry powder generation apparatus of the present invention has a temperature raising heater that heats the gas supplied from the spray blower to the spray nozzle, the temperature at which the liquefied gas is vaporized can be arbitrarily set.

  Further, the dry powder generating apparatus of the present invention is provided with a second reflux passage for refluxing a part of the gas sucked from the drying chamber to the drying chamber at a position higher than the powder recovery chamber. If a reflux fan is provided that pressurizes the gas flowing through the second reflux passage and supplies it to the drying chamber, the droplet sprayed with the gas flowing into the drying chamber from the second reflux passage is lowered at the room temperature of the drying chamber. Therefore, a large number of droplets can be heated more uniformly. If a temperature raising heater is installed in the second reflux passage, the sprayed droplets can be heated from below at an arbitrary temperature.

  Further, the spray device assembly of the present invention integrates a hollow container constituting a housing, a spray nozzle or a venturi nozzle, a raw material hopper, and a charging nozzle into a module, and thus has a drying capacity having various processing capabilities. It can be easily attached to the powder generator.

  Specific embodiments of the dry powder production method and apparatus and the spray device assembly according to the present invention will be apparent from the following description of embodiments with reference to the drawings.

FIG. 1 is a schematic diagram for explaining a method for producing a dry powder according to the present invention. FIG. 2 (A) shows a state in which the liquefied gas in the liquid gas droplet is rapidly vaporized by the method for producing a dry powder of the present invention, and the particles in the droplet exist as dry particles without agglomeration. FIG. 2 (B) is a schematic diagram showing that particles and active ingredients in a droplet are condensed when a solvent in the droplet is vaporized from a droplet generated by a general spray drying method. It is a schematic diagram showing the state granulated as an aggregate. FIG. 3 is a block diagram of an embodiment of the dry powder producing apparatus of the present invention. FIG. 4 is a diagram showing a more specific configuration of the dry powder production apparatus of the present invention. FIG. 5 is a front view of an embodiment of the dry powder producing apparatus of the present invention. FIG. 6 is a longitudinal sectional view of an embodiment of the spray device assembly of the present invention.

  Hereinafter, the method and apparatus for producing dry powder and the spray apparatus assembly of the present invention will be described by taking a vertical apparatus as an example.

  As shown in FIG. 1 and FIG. 2 (A), the method for producing a dry powder of the present invention discharges gas G from the nozzle or orifice 3 of the spray nozzle or venturi-nozzle 2 of the sprayer assembly 1 and A negative pressure region or a reduced pressure region 4 is generated downstream of the nozzle or orifice 3 depending on the effect. Then, by supplying the suspension S of the liquefied gas LG and the powder P from the raw material hopper 5 to the negative pressure region or the decompression region 4 via the charging nozzle 6, the droplet S1 of the suspension S is formed. Generate many. Next, these droplets S1 are heated by the gas G to vaporize the liquefied gas LG in the droplets S1. As the droplet S1 vaporizes, the droplet S1 rapidly expands in volume, and the energy of the volume expansion is used to prevent the powder P from aggregating. The powder P is also heated to near room temperature by the gas G. This prevents moisture in the gas around the powder P from condensing on the powder P. In FIG. 1, reference numeral 7 indicates a hollow container constituting the housing of the spray device assembly 1, and reference numeral 8 is a support plate of the hollow container 7. An opening 9 is formed in the support plate 8. Further, in FIG. 1, reference numeral 10 indicates that the suspension S of the liquefied gas LG and the powder P supplied from the raw material hopper 5 through the charging nozzle 6 to the negative pressure region or the decompression region 4 has a lot of fineness. The outline of the flow when the droplets S1 are heated and the droplets S1 are heated to rapidly expand in volume and move downward is shown.

  As shown in FIG. 1 and FIG. 2 (A), the liquefied gas LG is instantly vaporized by spraying the suspension S of the liquefied gas LG and the particles P in the form of fine droplets S1. Aggregation of the particles P is prevented by utilizing the energy of rapid volume expansion. When the liquefied gas is liquid nitrogen, for example, the volume change is about 650 times per millisecond. The volume of the droplet S1 may vary from about 700 to 800 times. The flow rate of the gas G discharged from the nozzle or orifice 3 is, for example, about 50 to 60 m / s.

  FIG. 2B shows a case in which the solvent P in the droplet D is vaporized from the droplet D generated by a general spray drying method, and the particles P1 and the active ingredient P2 in the droplet D. It is a schematic diagram showing the state granulated as the aggregate C.

  FIG. 3 shows a schematic configuration of the dry powder production apparatus 11 of the present invention. The dry powder generation device 11 discharges the gas G from the nozzle or orifice 3 and generates a negative pressure region or a reduced pressure region 4 downstream of the nozzle or orifice 3, and the spray nozzle or venturi nozzle 2. A raw material hopper 5, which is formed downstream of the venturi nozzle 2 and encloses a negative pressure region or a decompression region 4, a drying chamber 12, a suspension S of liquefied gas LG and powder P, and a raw material hopper 5 And a negative pressure region or a reduced pressure region 4, and supply a suspension S to the negative pressure region or the reduced pressure region 4 in the drying chamber 12, and a filter 13 for capturing the powder P. A dust collector 14 that sucks the gas G in the drying chamber 12 through the filter 13, a part of the gas G sucked by the dust collector 14 is discharged to the outside, and is sucked by the dust collector 14. Part of gas G is sprayed nozzle or There are a first reflux passage 16 to be refluxed to the venturi nozzle 2, a spray blower 17 that pressurizes the gas G flowing through the first reflux passage 16 and supplies the pressurized gas G to the spray nozzle or the venturi nozzle 2, and a spray blower 17. A heating heater 18 for heating the gas G supplied to the spray nozzle or the venturi nozzle 2 is provided. In the dry powder production apparatus 11, a powder recovery chamber 19 is defined in the lower portion of the drying chamber 12. The dry powder generation device 11 is further provided with a second recirculation passage 20 that recirculates a part of the gas G sucked into the dust collector 14 to the drying chamber 12 at a position higher than the powder recovery chamber 19. Yes. The second recirculation passage 20 is pressurized with the gas G flowing through the second recirculation passage 20 and supplied to the drying chamber 12, and the second recirculation passage 20 is supplied to the drying chamber 12. g A heater 22 for heating the gas is provided. Thus, according to the dry powder production | generation apparatus 11, since powder can be dried in the sealed space closed from the outside, contamination of dry powder can be prevented.

  4 and 5 are diagrams showing a more specific configuration of the vertical dry powder production apparatus 11. FIG. FIG. 4 shows a spray device assembly 1, a spray nozzle or venturi nozzle 2, a raw material hopper 5, a charging nozzle 6, a hollow container 7 constituting a housing of the spray device assembly 1, a filter 13, and an exhaust fan 14 </ b> A of a dust collector 14. , Spray blower 17, heating heater 18, and recovery box 19 are shown, and the moving direction of gas (nitrogen gas) G, suspension S, and dry powder P is indicated by arrows attached to these components. Has been.

  FIG. 5 shows a vertical apparatus 23 in which the constituent elements of the dry powder generating apparatus 11 shown in FIG. 4 are assembled. FIG. 5 shows a spray device assembly 1, a spray nozzle or venturi nozzle 2, a raw material hopper 5, a charging nozzle 6, a hollow container 7 constituting the housing of the spray device assembly 1, a drying chamber 12 and a recovery chamber (recovery box). ) 19, a filter 13, a dust collector 14, an exhaust fan 14 </ b> A, an exhaust valve 15, a first reflux passage 16, a spray blower 17, and a temperature raising heater 18 are assembled in a compact manner. In FIG. 5, reference numeral 10 indicates that the suspension S of the liquefied gas LG and the powder P supplied from the raw material hopper 5 through the charging nozzle 6 to the negative pressure region or the decompression region 4 is a large number of fine droplets. S1 shows the outline of the flow when these droplets S1 are heated to rapidly expand in volume and move downward.

  FIG. 6 is a longitudinal sectional view of one embodiment of the modularized spray assembly 1. The spray device assembly 1 includes a hollow container 7 having an upper surface 7A and a side surface 7b closed and a lower surface 7C opened, and a gas G inlet 2A outside the upper surface 7A of the hollow container 7. The spray nozzle or venturi nozzle 2 attached to the hollow container 7 so as to have the gas G discharge port 2B in the internal space 7D, and fixed to the side surface 7B of the hollow container 7 from the outside of the hollow container 7, The raw material hopper 5 that contains the suspension S of LG and powder P, and the suspension S that is contained in the raw material hopper 5 are supplied to the lower part of the discharge nozzle 2B of the spray nozzle or the venturi nozzle 2. An injection nozzle 6 is attached to the hollow container 7. The spray nozzle or venturi nozzle 2 has a tapered passage 2C having a diameter reduced from the gas G inlet 2A toward the gas G outlet 2B. Thus, since the spray device assembly 1 integrates the hollow container 7 constituting the housing, the spray nozzle or venturi-nozzle 2, the raw material hopper 5, and the charging nozzle 6 into a module, various processes are performed. It can be easily attached to an apparatus for producing a dry powder having capacity.

  According to the present invention, particles present in a suspended state in a liquefied gas can be recovered as dry particles in a short time. And this dry particle does not produce aggregation. Therefore, the further pulverization process which grind | pulverizes the aggregated powder becomes unnecessary.

DESCRIPTION OF SYMBOLS 1 Spraying device assembly 2 Spraying nozzle or venturi-nozzle 3 Nozzle or orifice 4 Negative pressure area or pressure reduction area 5 Raw material hopper 6 Input nozzle 7 Hollow container 8 Support plate 9 Opening 10 From raw material hopper through an injection nozzle, a negative pressure area or The suspension of the liquefied gas and powder supplied to the decompression zone becomes a large number of fine droplets, and these droplets are heated to rapidly expand in volume and move downward. line

Claims (10)

  Gas is discharged from a nozzle or orifice, a negative pressure region or a reduced pressure region is generated downstream of the nozzle or orifice, and a suspension of liquefied gas and powder is supplied to the negative pressure region or reduced pressure region. A large number of turbid liquid droplets are generated, the droplets are heated to vaporize the liquefied gas in the droplets, the powder is heated to near room temperature, and the droplets generated by vaporization of the droplets are heated. A method for producing a dry powder, wherein the powder is prevented from agglomerating by volume expansion.   2. The method of claim 1, wherein the liquefied gas is liquid nitrogen and the volume of the droplet varies from about 700 to 800 times.   3. The method according to claim 1 or 2, wherein the flow rate of the gas discharged from the nozzle or orifice is about 50 to 60 m / s.   4. The method according to claim 2, wherein the gas discharged from the nozzle or orifice is a heated nitrogen gas. A spray nozzle or a venturi-nozzle that discharges gas from a nozzle or orifice and generates a negative pressure region or a reduced pressure region downstream of the nozzle or orifice;
A drying chamber formed downstream of the spray nozzle or venturi nozzle and surrounding the negative pressure region or the reduced pressure region;
A raw material hopper containing a suspension of liquefied gas and powder;
An input nozzle that extends between the raw material hopper and the negative pressure region or the reduced pressure region, and supplies the suspension to the negative pressure region or the reduced pressure region in the drying chamber;
A dust collector comprising a filter for capturing the powder, and sucking the gas in the drying chamber through the filter;
An exhaust valve for discharging a part of the gas sucked into the dust collector to the outside;
A first reflux passage for refluxing a part of the gas sucked into the dust collector to the spray nozzle or the venturi nozzle;
A spray blower that pressurizes the gas flowing through the first reflux passage and supplies the gas to the spray nozzle or venturi nozzle;
A temperature raising heater that heats the gas that the spray blower supplies to the spray nozzle or the venturi nozzle;
An apparatus for producing dry powder, comprising:   6. The apparatus according to claim 5, wherein a powder recovery chamber is defined in a lower part of the drying chamber.   The apparatus according to claim 6, wherein a second reflux passage is provided for refluxing part of the gas sucked into the dust collector to the drying chamber at a position higher than the powder recovery chamber, and the second reflux is provided. The apparatus according to claim 1, wherein the passage is provided with a reflux fan that pressurizes the gas flowing through the second reflux passage and supplies the pressurized gas to the drying chamber.   8. The apparatus according to claim 7, further comprising a heating heater for heating the gas supplied from the second reflux passage to the drying chamber. A hollow container with the top and sides closed and the bottom open;
A spray nozzle or a venturi-nozzle attached to the hollow container so as to have a gas inlet outside the upper surface of the hollow container and to have the gas outlet in the internal space of the hollow container;
A raw material hopper fixed to the side surface of the hollow container from the outside of the hollow container and containing a suspension of liquefied gas and powder;
A dosing nozzle attached to the hollow container so as to supply the suspension contained in the raw material hopper to the lower part of the discharge port of the spray nozzle or venturi nozzle;
A spraying device assembly.   10. The assembly according to claim 9, wherein the spray nozzle or the venturi nozzle has a tapered passage having a diameter reduced from the gas inlet to the gas outlet. Solid.

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