JP2010058059A - Method of manufacturing spherical particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a spherical particle, in which a material having a high-melting point such as magnesia and zirconia is spheroidized without damaging the productivity and economic efficiency in a flame method. <P>SOLUTION: Raw powder is fed into a flame formed by a burner 13 for manufacturing a high-pressure combustion spherical particle in a high-pressure atmosphere inside a high-pressure combustion chamber 16, and is melt-treated in the high-temperature atmosphere of the flame formed at high pressure to be spheroidized. Since the flame having a higher temperature than the flame formed in atmospheric pressure can be formed by forming the flame in the high-pressure atmosphere, the material having the high-melting point such as magnesia and zirconia, which cannot be spheroidized in the atmospheric pressure, can be spheroidized. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing spherical particles, and more particularly to a method for producing spherical particles suitable for spheroidizing a high melting point material such as magnesia or zirconia.

Various methods are known as methods for producing inorganic oxide spherical particles, but the flame method is widely used industrially from the viewpoint of productivity and economy. In this flame method, the raw material powder is put into a flame formed by jetting fuel and supporting gas (support gas) from a burner, and the raw material powder is melted or semi-melted in a high temperature atmosphere of the flame to obtain surface tension. Spherical particles are obtained by spheroidizing the powder surface (see, for example, Patent Documents 1 and 2).
JP 2005-288399 A JP 2007-15588 A

  However, in the flame method in which the melting process is performed in the high temperature atmosphere of the flame formed by the combustion reaction heat of the gas fuel containing methane or propane as the main component, it is impossible to melt a material having a melting point higher than the flame temperature. There was a limit to the material that could be melted. For example, when the stoichiometric ratio in the propane-oxygen system is satisfied, the chemical species are thoroughly mixed, and the theoretical maximum temperature-adiabatic equilibrium flame temperature in a fully reacted state is 3095 K, a melting point of 3095 K or more is required. It is theoretically impossible to melt a material such as magnesia (MgO, melting point 3098K).

It is also known that the theoretical melting throughput [kg / Nm ³ · fuel] per unit fuel flow rate decreases as the melting point approaches 3095 K even for materials having a melting point of less than 3095 K. Further, in the flame method, a large amount of soot is generated if the mixing method of the fuel and the combustion-supporting gas is mistaken, and soot is mixed as impurities in the spherical particles of the recovered product. Incorporation of soot into the product significantly reduces the performance of the spherical particles when used as an electronic material.

  Accordingly, an object of the present invention is to provide a method for producing spherical particles that enables spheroidization of a high-melting-point material such as magnesia or zirconia without impairing productivity and economic efficiency in the flame method.

  In order to achieve the above object, the method for producing spherical particles of the present invention is characterized in that raw material powder is put into a flame formed in a high-pressure atmosphere, and the raw material powder is spheroidized, and in particular, the raw material The pressure of the high-pressure atmosphere that forms the flame is adjusted according to the melting point of the powder. Further, the flame is formed by fuel and a combustion-supporting gas ejected from a burner, a part of the combustion-supporting gas is ejected from the burner as a swirling flow, and the remaining combustion-supporting gas is discharged from the burner. It is characterized by being ejected as a straight flow in the axial direction. Further, the high-pressure atmosphere is in a range of 0.2 to 10 MPa, and the raw material powder is magnesia or zirconia.

  According to the method for producing spherical particles of the present invention, a flame having a higher temperature than a flame formed at atmospheric pressure can be formed by forming a flame in a high-pressure atmosphere. It was possible to spheroidize the high melting point material. Further, by adjusting the pressure of the high-pressure atmosphere to an appropriate pressure according to the melting point of the material, the high melting point material can be efficiently spheroidized. Furthermore, the residence time of the raw material powder in the flame can be increased by forming a long flame by using a part of the combustion-supporting gas as a swirl flow and the remaining combustion-supporting gas as a straight flow in the axial direction. The melting point material can be reliably heated and melted.

  FIG. 1 is a system diagram showing an embodiment of a spheroidized particle production apparatus capable of implementing the method for producing spherical particles of the present invention. In this spheroidized particle manufacturing apparatus, the raw material powder cut out by the high-pressure feeder 11 is transported to the burner 13 for manufacturing high-pressure combustion spherical particles along with the carrier gas supplied from the path 12. The burner 13 for producing high-pressure combustion spherical particles is supplied with the pressurized combustion-supporting gas from the combustion-supporting gas supply facility 14 and the pressurized fuel from the fuel supply facility 15, so that a high-pressure combustion chamber is provided. A flame is formed in the high-pressure atmosphere in the high-pressure combustion chamber 16. The raw material powder conveyed to the burner 13 for producing high-pressure combustion spherical particles is put into the flame formed in the high-pressure atmosphere in the high-pressure combustion chamber 16 from the burner 13 for producing high-pressure combustion spherical particles, and in the high-temperature flame. It spheroidizes by melting or semi-melting.

  The spheroidized particles are cooled by pressurized air supplied from the passage 17 into the high-pressure combustion chamber 16, captured by the high-pressure cyclone 18 and the candle filter 19, and collected as product spherical particles P. The combustion exhaust gas from which the spherical particles are separated is depressurized to near atmospheric pressure by the exhaust valve 20 and released into the atmosphere. The pressure in the system until the spherical particles are produced and separated and recovered is adjusted to a preset high-pressure atmosphere by controlling the opening degree of the exhaust valve 20. Each path is provided with a drain 21 as necessary, and condensed water generated in the system is appropriately discharged.

  In this way, since the temperature of the flame can be increased by spheronizing the raw material powder with a flame formed while maintaining the inside of the system in a high-pressure atmosphere, the spherical shape of the high melting point material that was impossible in an atmospheric pressure atmosphere Can be made. The pressure in the system, particularly the pressure in the high-pressure combustion chamber 16 where a flame is formed, varies depending on the melting point of the material, the fuel used, etc., but the range of 0.2 to 10 MPa is usually appropriate. If the pressure is less than 2 MPa, the effect of increasing the flame temperature as a high-pressure atmosphere cannot be obtained sufficiently, and if it exceeds 10 MPa, there is a problem that the costs of various devices and piping used in the apparatus increase.

  As the fuel, those generally used in the flame method can be used, and liquefied natural gas (LNG), city gas (13A), liquefied petroleum gas (LPG), dimethyl ether (DME), hydrogen, etc. are used. Is possible. Among these, although hydrogen has the advantage that a higher flame temperature can be obtained, there is a problem in terms of cost at present, so when considering the cost per unit calorie, liquefied natural gas, city gas, liquefied petroleum Gas is practical. As the combustion-supporting gas, an appropriate gas can be used depending on the required flame temperature, but oxygen (industrial oxygen) is optimal for obtaining a high-temperature combustion flame. The carrier gas can be any gas, but oxygen, nitrogen, a mixed gas thereof, or the like can be used.

  2 and 3 show a first embodiment of a high-pressure combustion spherical particle production burner that can be used in the method for producing spherical particles of the present invention. FIG. 2 is a sectional view, and FIG. It is III sectional drawing.

  The high pressure combustion spherical particle manufacturing burner 30 includes a raw material powder supply path 31 for supplying a raw material powder conveyed to a carrier gas, a fuel gas supply path 32 installed on the outer periphery of the raw material powder supply path 31, and the fuel A swirling oxygen supply path 33 installed on the outer periphery of the gas supply path 32, a straight oxygen supply path 34 installed on the outer periphery of the swirl oxygen supply path 33, and cooling water installed on the outer periphery of the straight oxygen supply path 34 Each of the fluids excluding the cooling water flowing in the cooling water passages 35a and 35b is ejected from each outlet provided at the tip of each supply passage.

  At the tip of the raw material powder supply path 31, there is provided a raw material powder ejection port 31s composed of a plurality of small holes, and the raw material powder is ejected so as to spread outward along with the carrier gas. The fuel gas jet 32s provided at the tip of the fuel gas supply passage 32 on the outer peripheral side of the raw material powder jet 31s jets the fuel gas in a cylindrical shape by a straight flow in a direction parallel to the burner axis. The swirl oxygen outlet 33s provided at the tip of the swirl oxygen supply path 33 on the outer peripheral side of the fuel gas spout 32s ejects oxygen as a swirl flow by swirl vanes and the like, and the oxygen ejected from the swirl oxygen spout 33s is It flows forward while turning in a spiral. Further, the straight oxygen outlet 34s provided at the tip of the straight oxygen supply passage 34 on the outer peripheral side of the swirling oxygen jet 33s ejects oxygen in a cylindrical shape by a straight flow in a direction parallel to the burner axis.

  4 and 5 show a second embodiment of a high-pressure combustion spherical particle production burner that can be used in the spherical particle production method of the present invention. FIG. 4 is a sectional view, and FIG. 5 is a front view of the burner. It is a front view.

  In the same way as described above, the burner 40 for producing high-pressure combustion spherical particles includes a raw material powder supply path 41 for supplying the raw material powder conveyed to the carrier gas, and a fuel gas supply path 42 installed on the outer periphery of the raw material powder supply path 41. A swirl oxygen supply path 43 installed on the outer periphery of the fuel gas supply path 42, a rectilinear oxygen supply path 44 installed on the outer periphery of the swirl oxygen supply path 43, and an outer periphery of the straight oxygen supply path 44. A cone-shaped combustion chamber 47 whose front is expanded is provided at the tip of the burner main body 46 formed in a multiple tube structure having the cooling water passages 45a and 45b.

  In the center of the bottom of the combustion chamber 42, a raw material powder jet 31s is formed which is composed of a plurality of small holes for jetting the raw material powder supplied from the raw material powder supply passage 31 so as to spread outward. On the outer peripheral side of the raw material powder outlet 31s, on the front side of the combustion chamber 42, a plurality of small nozzles for jetting the fuel gas supplied from the fuel gas supply passage 32 in a straight line flow in a direction parallel to the burner axis. The fuel gas jets 32s formed of holes are provided at equal intervals in the circumferential direction. Since the swirl flow oxygen supplied from the swirl oxygen supply path 33 is spouted as a swirl flow on the outer peripheral side of the fuel gas outlet 32s and on the front side of the combustion chamber 42, the ejection direction is inside the combustion chamber 42, and Swirling oxygen jets 33 s composed of a plurality of small holes inclined toward the tangential direction of the combustion chamber 42 are provided at equal intervals in the circumferential direction. Further, on the outer peripheral side of the swirling oxygen outlet 33 s and on the front side of the combustion chamber 42, the straight-flowing oxygen supplied from the straight-ahead oxygen supply passage 34 is jetted in a cylindrical shape with a straight-forward flow in a direction parallel to the burner axis. A straight oxygen outlet 34s composed of a plurality of small holes is provided at equal intervals in the circumferential direction.

  The amount of oxygen ejected from the swirling oxygen outlets 33s, 43s and the straight oxygen outlets 34s, 44s in the burner 30, 40 for producing high-pressure combustion spherical particles formed in this way is the swirl oxygen supply path 33, 43 and the straight oxygen supply passages 34 and 44 can be arbitrarily adjusted by adjusting the amounts of oxygen supplied to the straight oxygen supply passages 34 and 44, respectively. By adjusting the flow rate ratio and flow rate ratio with the straight oxygen that is ejected from the flame, the propulsive force of the combustion flame formed in front of the burner and the spread to the surroundings can be controlled, and the shape and flame of the flame And the temperature distribution can be adjusted.

  That is, when the ratio of the swirling oxygen to the straight oxygen is increased, the straight flow becomes relatively weak and the flame shape becomes short, and the combustion gas flow characteristics with a lot of spiral flow swirling with respect to the flame central axis are obtained. A flame having strong characteristics has a greater effect of dispersing the raw material powder ejected from the raw material powder jet ports 31s and 41s to the front of the flame center axis, but the residence time in the high-temperature flame is shortened. descend. Further, the fuel gas ejected from the fuel gas ejection ports 32 s and 42 s may also disperse and deviate from the oxygen flow, so that the ratio of the fuel present in the region having a low oxygen concentration increases and soot is easily generated.

  On the other hand, when the ratio of the swirling oxygen to the straight oxygen is decreased, the straight flow is relatively strong, so that a long flame shape is obtained, and a straight combustion gas flow characteristic with a small spiral flow swirling with respect to the flame central axis is obtained. A flame having such strong characteristics is less effective in dispersing the raw material powder ejected from the raw material powder jet outlets 31s and 41s in front of the flame center axis, but the residence time of the raw material powder in the high-temperature flame becomes longer. The melting capacity is improved.

  In this case, the raw material powder outlets 31 s and 41 s are shaped so that the raw material powder is ejected so as to spread outward as described above, and the raw material powder is formed so as to be sufficiently dispersed. It becomes possible to fully disperse the powder. Further, since the straight flow that is jetted from the straight oxygen jets 34s and 44s located on the outer peripheral side of the burner is strengthened, dispersion of the fuel gas jetted from the inner fuel gas jets 32s and 42s can be suppressed, and the fuel gas is oxygenated. Since it can be burned in a high concentration region, the generation of soot is reduced.

  Therefore, by appropriately setting the ratio of straight oxygen and swirling oxygen according to the conditions such as the properties of the raw material powder and the atmospheric pressure, the spheroidization of the raw material powder made of not only the low melting point material but also the high melting point material can be efficiently performed. It can be done reliably.

  For example, when a low-melting-point material such as silica is spheroidized in an atmospheric pressure atmosphere using a burner having the same structure as shown in FIGS. 2 and 3, swirling oxygen relative to the total amount of straight oxygen and swirling oxygen By setting the ratio to about 30%, the raw material powder can be appropriately heated and melted, and adhesion and coarsening of the molten particles can be prevented.

  However, when spheroidizing high melting point materials such as magnesia and zirconia, the flame is shorter than the combustion flame in the atmospheric pressure atmosphere because it is a combustion in the high pressure atmosphere, which is the same as the atmospheric pressure atmosphere. If the ratio of swirling oxygen to the total amount of oxygen is set to around 30%, soot tends to occur as described above. For this reason, the ratio of the swirling oxygen to the total oxygen amount is reduced as compared with that under the atmospheric pressure atmosphere. Usually, the ratio of the swirling oxygen is set in a range of 5 to 20% of the total oxygen amount, and the ratio of the straight oxygen is relatively set. By making it increase, the flame can be lengthened and the generation of soot can be suppressed.

  On the other hand, when the amount of the straight-ahead oxygen amount is increased to reduce the swirling oxygen amount, the effect of improving the fluidity of the fuel gas due to the swirling oxygen tends to decrease relatively, but the fuel gas is ejected from the fuel gas outlets 32s and 42s. By increasing the jet speed of the straight oxygen jetted from the straight oxygen jet outlets 34s and 44s rather than the jet speed of the fuel gas, the flow of the fuel gas can be wrapped with the straight oxygen flow. For example, the ejection speed of the fuel gas ejected from the fuel gas ejection ports 32 s and 42 s may be in a general range of 15 to 40 m / s, and the ejection speed of the rectilinear oxygen ejected from the rectilinear oxygen ejection ports 34 s and 44 s at this time By setting the fuel gas in a range of 1.1 to 3 times the jetting speed of the fuel gas, the flow of the fuel gas can be sufficiently wrapped with the flow of straight oxygen.

  FIG. 6 shows the fuel supply when the pressure (atmospheric pressure) in the high-pressure combustion chamber (16) is set to an intermediate pressure of 0.5 MPa, LNG is used as the fuel source, and liquid oxygen is used as the combustion-supporting gas source. It is a systematic diagram showing an example of equipment and oxygen supply equipment. LNG is sent from the LNG storage tank 50 to the LNG evaporator 51 for vaporization, and liquid oxygen is sent from the liquid oxygen storage tank 52 to the oxygen evaporator 53 for vaporization, and the flow rate is adjusted by the flow rate controllers 54 and 55. Then, it is supplied to the burner 13 for producing high-pressure combustion spherical particles through the supply pipes 56 and 57.

FIG. 7 shows that the pressure in the high-pressure combustion chamber (atmospheric pressure) is set to an intermediate pressure of 0.5 MPa, LPG (C ₃ H ₈ concentration 90% or more) is used as the fuel source, and liquid oxygen is used as the combustion-supporting gas source. It is a systematic diagram which shows an example of the fuel supply equipment and oxygen supply equipment when each is used. The LPG is sent from the LPG storage tank 60 to the evaporator 61 for vaporization, and the liquid oxygen is sent from the storage tank 62 to the evaporator 63 for vaporization. It is supplied to the burner 13 for producing high-pressure combustion spherical particles via pipes 66 and 67. In the supply pipe 66 on the LPG side, a pipe heater 66H for heating the supply pipe 66 to 30 to 70 ° C. is installed in order to prevent the fuel gas vaporized by the evaporator 61 from being reliquefied in the pipe. An electric heater, a steam trace, or the like can be arbitrarily used as the heating source of the pipe heater 66H.

  FIG. 8 shows an example of fuel supply equipment and oxygen supply equipment when the pressure in the high-pressure combustion chamber is set to a high pressure of 2.3 MPa, LNG is used as the fuel source, and liquid oxygen is used as the combustion-supporting gas source. It is a systematic diagram shown. The LNG is led out from the storage tank 70 and pressurized to 2.3 MPa or more, for example, 2.5 to 2.6 MPa by the LNG pump 71, and then sent to the LNG evaporator 72 and vaporized. Similarly, liquid oxygen is led out from the storage tank 73 and pressurized to 2.5 to 2.6 MPa by the oxygen pump 74 and then sent to the evaporator 75 to be vaporized. The vaporized fuel and oxygen are adjusted in flow rate by the flow rate controllers 76 and 77 and supplied to the burner 13 for producing high-pressure combustion spherical particles through the supply pipes 78 and 79.

  FIG. 9 shows an example of fuel supply equipment and oxygen supply equipment when the pressure in the high-pressure combustion chamber is set to a high pressure of 2.3 MPa, LPG is used as the fuel source, and liquid oxygen is used as the combustion-supporting gas source. It is a systematic diagram shown. The LPG is led out from the LPG storage tank 80, pressurized to 2.5 to 2.6 MPa as described above by the LPG pump 81, and then sent to the evaporator 82 to be vaporized. Similarly, liquid oxygen is led out from the storage tank 83 and pressurized to 2.5 to 2.6 MPa by the oxygen pump 84 and then sent to the evaporator 85 to be vaporized. The vaporized fuel and oxygen are adjusted in flow rate by the flow rate controllers 86 and 87, and supplied to the burner 13 for producing high-pressure combustion spherical particles through the supply pipes 88 and 89. In the supply pipe 88 on the LPG side, a pipe heater 88H for heating the supply pipe 88 to 80 to 120 ° C. is installed in order to prevent the fuel gas vaporized by the evaporator 82 from being reliquefied in the pipe. As a heating source of the pipe heater 88H, an electric heater, a steam trace, or the like can be arbitrarily used.

The pressure in the high-pressure combustion chamber was set to a high pressure of 0.5 MPa, and the burner (40) for producing high-pressure combustion spherical particles having the structure shown in the second embodiment of FIGS. 4 and 5 was used, as shown in FIG. LPG (C ₃ H ₈ concentration 97% or more) is vaporized from the fuel supply facility and supplied as fuel gas, and oxygen gas (oxygen concentration 99%) vaporized from the oxygen supply facility is used as a combustion-supporting gas. As a raw material powder, an experiment was carried out in which spherical magnesia particles were produced using crushed magnesia powder (MgO purity 98.0%) having an average particle diameter (D ₅₀ ) of 20.5 μm.

The crushed magnesia powder uses 7.5 Nm ³ / h oxygen as a carrier gas and supplies 3.5 kg / h to the burner, the fuel gas is 5 Nm ³ / h, and the oxygen gas is 17 in total amount of swirling oxygen and straight oxygen. 0.5 Nm ³ / h (total amount with carrier gas was 25 Nm ³ / h). The ejection speed of the fuel gas ejected from the fuel gas ejection port was 25 m / s, and the ejection speed of the rectilinear oxygen ejected from the rectilinear oxygen ejection port was 37.7 m / s. The atmospheric temperature in the high-pressure combustion chamber during operation was 1000 to 1600 ° C. The flow rate [Nm ³ / h] represents a value converted to atmospheric pressure and 0 ° C., and the ejection velocity [m / s] represents a value converted to 0 ° C.

  When the experiment was performed by changing the ratio of the swirling oxygen amount to the total oxygen amount, “(swirl oxygen amount) / (swirl oxygen amount + straight-ahead oxygen amount)”, the ratio of the swirling oxygen amount was reduced to 20% or less As a result, there was little mixing of soot generated from the flame, and spherical magnesia particles with a high degree of circularity that were well melted were obtained. As a result of observing the spherical particles collected by the candle filter when the ratio of the amount of swirling oxygen is 20% or less, the particle size distribution is substantially the same as the raw material powder, and the spherical particles have an average particle size of 20 to 30 μm. confirmed.

  On the other hand, when the ratio of the swirling oxygen flow rate to the total oxygen flow rate was 30% and 40%, soot was mixed in the spherical particles collected by the candle filter, and many unmelted non-spherical particles were also observed. In addition, the pressure in the combustion chamber was set to 0.15 MPa (substantially atmospheric pressure) and each supply amount was the same, but in this case, the flame temperature did not rise sufficiently due to the low pressure, and the total Under any conditions where the ratio of the amount of swirling oxygen to the amount of oxygen was 0 to 50%, the raw material powder could not be melted in the flame, and spherical particles with a high degree of circularity were not obtained at all.

The pressure in the high-pressure combustion chamber is set to a high pressure of 0.5 MPa, and the fuel supply shown in FIG. 7 is performed using the burner for producing high-pressure combustion spherical particles having the structure shown in the second embodiment of FIGS. LPG (C ₃ H ₈ concentration 97% or more) is vaporized from the facility and supplied as fuel gas, and oxygen gas (oxygen concentration 99%) vaporized from the oxygen supply facility is supplied as combustion-supporting gas. In addition, an experiment was conducted in which spherical zirconia particles were produced using crushed zirconia powder (ZrO ₂ purity 99.3%) having an average particle diameter (D ₅₀ ) of 10.9 μm as the raw material powder.

Crushed zirconia powder uses 7.5 Nm ³ / h oxygen as a carrier gas and supplies 13 kg / h to the burner, fuel gas is 5 Nm ³ / h, oxygen gas is 17.5 Nm in total amount of swirling oxygen and straight oxygen ³ / h (total amount with carrier gas is 25 Nm ³ / h). The ejection speed of the fuel gas ejected from the fuel gas ejection port was 25 m / s, and the ejection speed of the rectilinear oxygen ejected from the rectilinear oxygen ejection port was 37.7 m / s. The atmospheric temperature in the high-pressure combustion chamber 16 during operation was 1000 to 1600 ° C.

  Experiments were performed by changing the ratio of the amount of swirling oxygen to the total amount of oxygen. By reducing the ratio of the amount of swirling oxygen to 20% or less, the soot generated from the flame was reduced, and the melted circularity was good. High spherical zirconia particles were obtained. As a result of observing the spherical particles collected by the candle filter when the ratio of the amount of swirling oxygen is 20% or less, it is a spherical particle having a particle size distribution substantially the same as the raw material powder and an average particle size of 10 to 20 μm. confirmed.

  On the other hand, when the ratio of the swirling oxygen flow rate to the total oxygen flow rate was 30% and 40%, soot was mixed in the spherical particles collected by the candle filter, and many unmelted non-spherical particles were also observed. Further, in the state where the ratio of the swirling oxygen amount is 20%, when the ejection speed of the fuel gas ejected from the fuel gas ejection port is set to 10 m / s, the ejection speed of the rectilinear oxygen ejected from the rectilinear oxygen ejection port is further increased. When the fuel gas ejection speed was 0.9 times or less, soot was observed in all cases, and the proportion of unmelted non-spherical particles increased.

The fuel supply shown in FIG. 9 is performed by setting the pressure in the high-pressure combustion chamber to a high pressure of 2.3 MPa and using the burner for producing high-pressure combustion spherical particles having the structure shown in the second embodiment of FIGS. LPG (C ₃ H ₈ concentration 97% or more) is vaporized from the facility and supplied as fuel gas, and oxygen gas (oxygen concentration 99%) vaporized from the oxygen supply facility is supplied as combustion-supporting gas. In addition, an experiment was conducted in which spherical magnesia particles were produced using crushed magnesia powder (MgO purity 98.0%) having an average particle diameter (D ₅₀ ) of 20.5 μm as the raw material powder.

The crushed magnesia powder supplies 5.5 kg / h to the burner using 7.5 Nm ³ / h oxygen as a carrier gas, the fuel gas is 5 Nm ³ / h, and the oxygen gas is 17 in total amount of swirling oxygen and straight oxygen. 0.5 Nm ³ / h (total amount with carrier gas was 25 Nm ³ / h). The ejection speed of the fuel gas ejected from the fuel gas ejection port was 25 m / s, and the ejection speed of the rectilinear oxygen ejected from the rectilinear oxygen ejection port was 37.7 m / s. The atmospheric temperature in the high-pressure combustion chamber 16 during operation was 1000 to 1600 ° C.

  When the experiment was performed by changing the ratio of the swirling oxygen amount to the total oxygen amount, “(swirl oxygen amount) / (swirl oxygen amount + straight-ahead oxygen amount)”, the ratio of the swirling oxygen amount was reduced to 20% or less. As a result, there was little mixing of soot generated from the flame, and spherical magnesia particles having a high degree of circularity that were well melted were obtained. As a result of observing the spherical particles collected by the candle filter when the ratio of the amount of swirling oxygen is 20% or less, the particle size distribution is substantially the same as the raw material powder, and the spherical particles have an average particle size of 20 to 30 μm. confirmed. On the other hand, when the ratio of the swirling oxygen flow rate to the total oxygen flow rate was 30% and 40%, soot was mixed in the spherical particles collected by the candle filter, and many unmelted non-spherical particles were also observed.

It is a systematic diagram which shows one example of the spheroidized particle manufacturing apparatus which can implement the manufacturing method of the spherical particle of this invention. It is sectional drawing which shows the 1st example of a high pressure combustion spherical particle manufacturing burner which can be used with the manufacturing method of the spherical particle of this invention. FIG. 3 is a sectional view taken along line III-III in FIG. 2. It is sectional drawing which shows the 2nd example of a high pressure combustion spherical particle manufacturing burner which can be used with the manufacturing method of the spherical particle of this invention. It is the front view similarly seen from the burner front. FIG. 3 is a system diagram showing an example of a fuel supply facility and an oxygen supply facility when the pressure in the high-pressure combustion chamber is set to 0.5 MPa, LNG is used as a fuel source, and liquid oxygen is used as a combustion-supporting gas source. FIG. 3 is a system diagram showing an example of a fuel supply facility and an oxygen supply facility when the pressure in the high-pressure combustion chamber is set to 0.5 MPa, LPG is used as a fuel source, and liquid oxygen is used as a combustion-supporting gas source. It is a systematic diagram showing an example of a fuel supply facility and an oxygen supply facility when the pressure in the high-pressure combustion chamber is set to 2.3 MPa, LNG is used as a fuel source, and liquid oxygen is used as a combustion-supporting gas source. It is a systematic diagram which shows an example of a fuel supply equipment and an oxygen supply equipment when the pressure in a high pressure combustion chamber is set to 2.3 MPa, LPG is used as a fuel source, and liquid oxygen is used as a combustion-supporting gas source.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... High pressure feeder, 13 ... High pressure combustion spherical particle manufacturing burner, 14 ... Combustion gas supply equipment, 15 ... Fuel supply equipment, 16 ... High pressure combustion chamber, 18 ... Cyclone, 19 ... Candle filter, 20 ... Exhaust valve , 21 ... Drain, 30, 40 ... Burner for producing high-pressure combustion spherical particles, 31, 41 ... Raw material powder supply passage, 31s, 41s ... Raw material powder injection port, 32, 42 ... Fuel gas supply passage, 32s, 42s ... Fuel gas Spout, 33, 43 ... swirling oxygen supply path, 33s, 43s ... swirling oxygen spout, 34, 44 ... straight oxygen supply path, 34s, 44s ... straight oxygen discharge, 35a, 35b, 45a, 45b ... cooling water passage 46 ... Burner body, 47 ... Combustion chamber, 50 ... LNG storage tank, 51 ... LNG evaporator, 52 ... Liquid oxygen storage tank, 53 ... Oxygen evaporator, 54, 55 ... Volume controller, 56, 57 ... supply piping, 60 ... LPG storage tank, 61 ... LPG evaporator, 66H ... piping heater, 71 ... LNG pump, 74 ... oxygen pump, 80 ... LPG storage tank, 81 ... LPG pump, 88H ... Pipe heater, P ... Product spherical particles

Claims (5)

  A method for producing spherical particles, characterized in that raw material powder is put into a flame formed in a high-pressure atmosphere, and the raw material powder is spheroidized.   The method for producing spherical particles according to claim 1, wherein the pressure of the high-pressure atmosphere forming the flame is adjusted according to the melting point of the raw material powder.   The flame is formed by a fuel and a combustion-supporting gas ejected from a burner, a part of the combustion-supporting gas is ejected from the burner as a swirling flow, and the remaining combustion-supporting gas is ejected in the axial direction of the burner. 3. The method for producing spherical particles according to claim 1, wherein the particles are ejected as a straight flow.   The method for producing spherical particles according to any one of claims 1 to 3, wherein the high-pressure atmosphere is in a range of 0.2 to 10 MPa.   The method for producing spherical particles according to any one of claims 1 to 4, wherein the raw material powder is magnesia or zirconia.

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