JP5500475B2 - Two-fluid nozzle - Google Patents

Description

  The present invention relates to a two-fluid nozzle that atomizes a liquid by the action of an air current. More specifically, the present invention relates to a novel two-fluid nozzle that can generate a fine mist even when the gas supply pressure is low, and that does not clog the liquid. The present invention relates to a fluid nozzle.

  The two-fluid nozzle that atomizes the liquid by the kinetic energy of gas is used for various applications such as coating of paint, spraying of water and water-soluble drugs, and fuel spraying. FIG. 7 is a diagram showing the structure of the most typical two-fluid nozzle. This is the “two-fluid nozzle” disclosed in Patent Document 1. The liquid nozzle 11 is arranged coaxially with the gas nozzle 12, and the liquid flowing out from the liquid nozzle in a liquid column shape is a mechanical action of an annular jet ejected from the annular opening 16 between the liquid nozzle outlet 11 a and the gas nozzle outlet 12 a. Is atomized. FIG. 8 shows a “nozzle” disclosed in Patent Document 2, in which gas swirl vanes 18 are arranged as means for swirling the annular jet. The swirling of the gas has the effect of promoting atomization of the liquid and increasing the spatial spread of the spray.

  Compared with a one-fluid atomizing nozzle that pressurizes liquid to high pressure and ejects it from a fine hole, the two-fluid nozzle has a feature that it can easily generate fine mist over a wide liquid flow rate range. As the gas, compressed air pressurized to several atmospheric pressure or more is usually used. Compared to liquids with little compressibility, the energy required to compress the gas is very large. In recent years, CO2 reduction has been promoted as a measure against global warming. However, a two-fluid nozzle that can obtain good atomization has been desired.

[0004]
In the above-described liquid column atomization type two-fluid nozzle, when the gas pressure and flow rate are the same, the smaller the outlet diameter of the liquid nozzle, that is, the smaller the diameter of the liquid column, the more the atomization is promoted. As is known, there is a problem that the liquid nozzle is easily clogged. In addition, the amount of spray is reduced by the amount the liquid nozzle outlet diameter is reduced. In order not to reduce the spray amount, the outflow speed of the liquid from the liquid nozzle outlet must be increased, the relative speed between the liquid and the airflow is decreased, and the atomization is deteriorated. Therefore, there is also a problem that the upper limit of the spray amount that can achieve good atomization is restricted. The size of the outlet of the liquid nozzle is about 1 mm even if it is small, and in order to atomize into particles having a diameter of about 10 microns, it is indispensable to use a compressed gas of several atmospheres as the atomizing gas.
[Prior art documents]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2005-103366 “Two Fluid Nozzle” Published on April 21, 2005 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-224592 “Nozzle” published on August 13, 2002

  JP-A-2005-103366 “Two-fluid nozzle” Released on April 21, 2005   JP 2002-22459 A “Nozzle” Published on August 13, 2002

  In the conventional two-fluid nozzle, it is difficult to reduce the outlet diameter of the liquid nozzle due to the problem of clogging of the liquid nozzle, so the use of high-pressure compressed gas is indispensable for very good atomization. there were. The production of high-pressure compressed gas requires a large amount of energy, and there is a problem in that not only the viewpoint of reducing CO2 emission but also the operating cost of the gas compressor of the spray device is increased. There is also a problem that the initial cost of the compressor is high. In the conventional two-fluid nozzle, there is a problem to be solved in terms of improving atomization performance particularly when the pressure of the atomizing gas is low.

  An object of the present invention is to provide a novel two-fluid nozzle that has better atomization performance than each conventional two-fluid nozzle and is free from the problem of clogging.

Two-fluid nozzles of the present invention, the gas nozzle, the liquid film forming nozzle, becomes liquid dispensing nozzle, and from the base, the liquid film forming nozzle is arranged in the gas nozzle and coaxial, the inner peripheral wall rotary symmetric The liquid distribution nozzle is provided with a plurality of spiral flow paths located at the outer periphery of the central axis and twisted with respect to the central axis. A liquid distribution channel that communicates with the channel and extends radially and opens into the spiral channel is disposed, and a part of the gas is formed between the outlet of the gas nozzle and the outlet of the liquid film forming nozzle. The remaining part of the gas flows into the spiral flow path, and the liquid flowing out from the opening of the liquid distribution flow path into the spiral flow path through the liquid flow path. After blowing off, a swirling airflow is generated along the liquid film forming surface, and blown away. The liquid spreads along the liquid film forming surface, forms a liquid film on the liquid film forming surface by the action of the swirling airflow, and flows out as an annular liquid film from the outlet of the liquid film forming nozzle, The annular liquid film swirls along the liquid film forming surface from the inner peripheral side, and is atomized by being sandwiched by the annular jet from the outer peripheral side and the swirling jet ejected from the liquid film forming nozzle outlet. I did it.

  In the two-fluid nozzle of the present invention, the gas flow formed by the liquid film forming nozzle outer wall surface of the liquid film forming nozzle and the inner wall surface of the gas nozzle is provided as means for turning the annular jet ejected from the annular opening. Arranged on the road.

Moreover, two-fluid nozzles of the present invention, the liquid dispensing nozzle at the tip, the liquid film forming nozzle coaxial to a rotary symmetric shape of the center body, the diameter of the liquid film forming surface of the liquid film forming nozzle outlet I tried to expand towards.

  The term spiral channel in this specification refers to a channel in which the direction of gas flow in the channel is geometrically “twisted” with respect to the central axis. It includes all flow channel shapes that can form a flow path that forms a swirling flow of gas in the space surrounded by the inner peripheral wall surface of the liquid film forming nozzle in combination with the inner peripheral wall surface, and has a linear flow path Of course included.

According to the present invention, the gas nozzle, the liquid film forming nozzle, the liquid dispensing nozzle, and made from the base, the liquid film forming nozzle, the disposed gas nozzle coaxially, inner peripheral wall surface rotation symmetric form of the A liquid film forming surface is formed, and the liquid distribution nozzle is provided with a plurality of spiral flow paths at a position twisted with respect to the central axis on the outer peripheral portion, and a liquid flow path and a liquid flow path in the liquid distribution nozzle. A liquid distribution channel that communicates and extends radially and opens into the spiral channel is disposed, and a part of the gas is formed between the outlet of the gas nozzle and the outlet of the liquid film forming nozzle. An annular jet is ejected from the opening, and the remaining part of the gas flows into the spiral channel, and blows away the liquid flowing out from the opening of the liquid distribution channel to the spiral channel through the liquid channel. Later, a swirling air flow is generated along the liquid film forming surface and blown away. The liquid film forming surface spreads along the liquid film forming surface, forms a liquid film on the liquid film forming surface by the action of the swirling airflow, and flows out as an annular liquid film from the outlet of the liquid film forming nozzle. The film swirls along the liquid film forming surface from the inner peripheral side and is atomized by being swung between the swirling jet ejected from the liquid film forming nozzle outlet and the annular jet from the outer peripheral side. Therefore, the liquid is blown away by the air flow, and some of the particles become fine particles, and the remaining coarse particles and liquid mass collide from the direction inclined on the liquid film formation surface by receiving the gas force and centrifugal force received from the swirling air flow. However, it is spread as a very thin annular liquid film with high uniformity in the thickness in the circumferential direction, and the thin liquid film is sandwiched between the inner and outer peripheral sides by a gas jet and has a strong shearing action. As a result, the fine particles are generated by the annular jet flowing in contact with the liquid column at the outer periphery Compared to conventional two-fluid nozzle which is atomized into much finer particles. Further, in the above-described embodiment, the liquid distribution channel is opened to the spiral channel through which the gas flows, and the gas pressure, more precisely, the static pressure there is as low as corresponding to the velocity energy of the gas. Therefore, there is an advantage that the gas flows out more easily than the case where the gas flow velocity is small in the space upstream or downstream of the spiral flow path. The liquid film forming nozzle has a swirling airflow in the center of the cross section, and the entire cross section of the nozzle is not filled with liquid, so the size of the outlet can be set large regardless of the amount of spray liquid. Unlike the conventional liquid column atomization type two-fluid nozzle that fills the entire cross section of the liquid nozzle, a two-fluid nozzle that can solve the clogging problem even when the amount of spray liquid is small can be realized.

  According to the present invention, the means for turning the annular jet ejected from the annular opening is disposed in the gas flow path formed by the outer wall surface of the liquid film forming nozzle and the inner wall surface of the gas nozzle. Therefore, the effect of further promoting the atomization of the annular liquid film was produced by the action of the swirling airflow. In addition, there is an effect of increasing the spread of the spray. If the direction of the swirling of the gas in the liquid film forming nozzle and the swirling direction of the annular jet are reversed, the shearing action of the gas acting on the annular liquid film is strengthened and atomization is promoted.

Further, according to the present invention, the liquid dispensing nozzle at the distal end, provided with the liquid film forming nozzle and the rotational symmetry shaped center body coaxially, the diameter of the liquid film forming surface of the liquid film forming nozzle towards the outlet The presence of this center body stabilizes the swirling of the airflow in the liquid film forming nozzle, improves the uniformity of the circumferential direction of the liquid film, and promotes atomization. Since the circumference of the outlet of the liquid film forming nozzle is increased by the liquid film forming surface that spreads forward, the increase in the thickness of the liquid film can be suppressed even when the spray amount is large, and the atomization performance can be maintained. There are advantages. Appropriate changes in the axial direction of the diameter of the center body and the inner peripheral surface of the liquid film forming nozzle, that is, the axial direction change of the diameter of the liquid film forming surface, suppress the weakening of the swirling of the gas in the annular channel. As a result, the uniformity of the liquid film in the circumferential direction is ensured, and good atomization performance is obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

One of the best modes for carrying out the present invention is shown in FIG. 1A is a cross-sectional view of a cross section including the central axis of a two-fluid nozzle, B is an external view of a liquid distribution nozzle, C is a cross-sectional view of a liquid distribution flow path of the liquid distribution nozzle, and D is a liquid supply in a spiral flow path. It is a figure which shows the approximate position of a hole. The two-fluid nozzle 1 includes a gas nozzle 12, a liquid film forming nozzle 13, a liquid supplier 14 and a base 15. The base 15 is provided with a gas inflow passage 15a and a liquid inflow passage 15b, and a screw for screwing a pipe joint is provided at each entrance. Gas nozzle 12 is connected to the base 15, liquid film forming nozzle 13 is disposed in the gas nozzle 12 and coaxial, to form a rotational symmetric shape on the inner peripheral liquid film forming surface 13b, the liquid supply unit 14 therein A liquid flow path 14a communicating with the liquid inflow path is disposed, and a plurality of spiral flow paths 14b that are twisted with respect to the central axis are disposed on the outer periphery, and the liquid flow path 14a extends radially. A liquid distribution channel 14c that opens to the spiral channel 14b is provided in communication, and the liquid that has flowed in from the liquid inflow channel 15b passes through the liquid channel 14a and the liquid distribution channel 14c, and the spiral channel 14b. A part of the gas flowing out from the gas inflow passage 15 a passes through the gas flow path 17 formed by the inner wall surface 12 b of the gas nozzle 12 and the liquid film formation nozzle outer wall surface 13 c of the liquid film formation nozzle 13. , Axial flow system arranged as a means to give swirl The airflow swirl vanes 18 are swirled to eject from an annular opening 16 formed between the outlet 12a of the gas nozzle 12 and the outlet 13a of the liquid film forming nozzle 13, and the remainder of the gas is a spiral channel 14b. The liquid flowing into the liquid distribution flow path 14c and the liquid flowing out from the opening 14d of the liquid distribution flow path 14c collide with the liquid film forming surface 13b. The liquid flows on the liquid film forming surface, and the liquid film forming nozzle 13 The annular liquid film flows out from the spiral flow path 14b from the inner peripheral side, and turns into a swirl flow along the liquid film forming surface 13b of the liquid film forming nozzle 13 to form a liquid film forming nozzle outlet 13a. By the gas flow ejected from the outer peripheral side, it is sandwiched by the gas flow ejected from the annular opening 16 and atomized.

  In the form of FIG. 1, the liquid film forming surface 13 b of the liquid film forming nozzle 13 has a diameter that increases toward the outlet, and the peripheral length of the outlet of the liquid film forming nozzle increases, so that the spray amount is large. However, the increase in the thickness of the liquid film can be suppressed, and the atomization performance can be maintained. The center body also adapts to the expansion of the liquid film forming nozzle, and its diameter increases toward the outlet, so that the flow velocity of the air current in the liquid film forming nozzle does not decrease and the rotation is stabilized. Therefore, the uniformity in the circumferential direction of the liquid film is improved and atomization is promoted. In addition, as for clogging, the annular flow path between the liquid film forming surface of the liquid film forming nozzle and the outer peripheral surface of the center body can increase the gap, thereby avoiding the problem of clogging. Of course, the liquid film forming nozzle may be a thin cylinder, and can be manufactured at low cost by using a thin pipe.

  The tip of the liquid film forming nozzle 13 is preferably thin as shown in FIG. 1 from the viewpoint of atomization. In addition, the shape of the tip of the liquid supplier extending as the center body along the central axis to the vicinity of the outlet of the liquid film forming nozzle is the air flow in the annular space formed along the inner peripheral wall surface of the liquid film forming nozzle. Not only is this effective in stabilizing the swirling flow, but also the gas outflow speed at the outlet of the liquid film forming nozzle can be increased, which is effective in promoting atomization. Due to the swirling flow, a negative pressure region is formed in the vicinity of the mandrel, and the negative pressure also has an effect of preventing the gas from flowing backward from the outlet 13a of the liquid film forming nozzle into the annular space.

  The gas pressure acting on the liquid flowing out from the opening 14d of the liquid distribution channel 14c of the spiral channel 14b will be described with reference to FIG. For simplicity, it is assumed that there is no energy loss of the gas flow in the spiral channel. The pressure acting on the liquid at the opening 14d of the liquid distribution channel is the static pressure of the fluid there. The static pressure is the total pressure at the inlet and outlet by the dynamic pressure corresponding to the energy of the velocity according to Bernoulli's theorem. Lower than. That is, the pressure of the gas acting on the liquid is smaller when the liquid outlet is disposed in the middle of the spiral flow path than when the liquid outlet is disposed in the space formed on the inner peripheral surface of the liquid film forming nozzle. Since the dynamic pressure of the gas flowing in the spiral flow path increases in proportion to the square of the flow velocity, the larger the gas velocity, the smaller the pressure acting on the liquid and the smaller the pressure required to supply the liquid. I'm sorry. Even in the annular liquid film atomization type two-fluid nozzle of the present invention in which the liquid and the gas are mixed in the two-fluid nozzle by optimally designing the liquid film forming nozzle, the gas nozzle, the spiral flow path, etc. Depending on the altitude difference from the liquid outlet and the gas supply pressure, the liquid can be self-primed. Note that the liquid distribution channel is preferably disposed with its outlet inclined with respect to the axis in the direction of gas flow.

  Another best mode for carrying out the present invention is shown in FIG. The liquid film forming nozzle has a tapered shape, and the center body at the tip also has a tapered shape suitable for it. This form has an advantage that the amount of air used can be reduced because the opening of the liquid film forming nozzle can be made small. On the other hand, there is a disadvantage that the pressure of the internal gas increases and the liquid is easily returned. This problem can be alleviated by shortening the center body and increasing the opening area as shown in FIG.

  FIG. 4 shows still another best mode for carrying out the present invention. In this embodiment, a radial flow type airflow swirl vane 18 is disposed in a gas flow path 17 formed by the inner peripheral wall of the gas nozzle 12 and the outer peripheral wall surface of the liquid film forming nozzle 13, and gas is passed through this. A strong swirl is given to the flow of the gas ejected from the annular opening 16 formed between the outlet of the nozzle 12 and the outlet 13a of the liquid film forming nozzle 13. The airflow swirl blade is not limited to the axial flow method and the radial flow method, and may be a mixed flow method. By giving swirl to the airflow from the annular opening, not only can atomization of the annular liquid film be promoted, but also the spray spread can be changed by changing the strength of the swirl. .

  Another best mode for carrying out the present invention is shown in FIG. In this embodiment, the outlet 13a of the liquid film forming nozzle 13 is disposed so as to protrude more appropriately than the outlet 12a of the gas nozzle. By doing so, a negative pressure is generated by the flow of gas ejected from the gas nozzle, acting in a direction to lower the pressure in the liquid film forming nozzle, and reducing the pressure of the gas acting on the liquid distribution channel opening. Convenient.

  Example 1 of the spraying apparatus using the two-fluid nozzle of the present invention is shown in FIG. The spraying device 2 includes an air pump 21, a liquid container 22, a two-fluid nozzle 1 according to the present invention, a atomizing gas pipe 23, a liquid pipe 24, and a pressurizing gas pipe 25, and the gas from the gas pump 21 is atomized. The gas container 23 is supplied to the two-fluid nozzle 1 according to the present invention, the liquid container 22 is an airtight container, and communicates with the discharge port of the gas pump 21 through the pressurizing gas pipe 25 and is discharged from the gas pump. The liquid in the liquid container is supplied to the two-fluid nozzle through the liquid supply pipe using the pressure of the gas that is generated. This configuration is intended to provide a simple spraying device that does not require a liquid feed pump. In this embodiment, the atomizing gas pipe is branched into two systems, and a shutoff valve 26 is provided on one of them, and after the air pump is started, the shutoff valve is opened after the liquid reaches the two-fluid nozzle. There is a feature in point.

  In general, in a spray device that employs a two-fluid nozzle, it is desirable that air flows into the two-fluid nozzle first, and then liquid flows into the nozzle. If the order of supply is reversed, the liquid is ejected without being atomized, which is inconvenient. In the two-fluid nozzle of the present invention, the liquid can easily flow out from the opening of the liquid distribution channel that opens in the spiral groove by utilizing the decrease in the static pressure of the gas flowing into the spiral channel as described above. However, as long as the structure is such that the liquid and the gas are mixed in the nozzle, the liquid and the gas are not mixed until they reach the atmosphere. In contrast, since the liquid is exposed to the pressure of the gas, it is inevitable to receive a force in the direction in which the liquid is pushed back to the liquid supply pipe. In the above-described spraying apparatus that does not use the liquid feed pump, there is a problem that when the two-fluid nozzle 1 is slightly higher than the liquid level in the liquid container, the liquid cannot be supplied or the supply is intermittent. Even if it can be supplied, if there is a distance between the liquid container and the two-fluid nozzle, the liquid pipe is not filled with liquid at the first use, so the liquid arrives at the two-fluid nozzle and sprays. There may be a problem that it takes time to start. In this embodiment, since the shutoff valve is closed when the air pump is started, a part of the air from the air pump is supplied to the two-fluid nozzle, but it is more in the liquid container than when the shutoff valve is open. A large amount of air can be sent, and the pressure in the liquid container increases due to the increase in flow resistance by the shutoff valve, so the liquid in the liquid container flows through the liquid pipe at a high speed and flows into the two-fluid nozzle in a short time. Atomization starts early. If the shut-off valve is opened immediately, more air is supplied to the two-fluid nozzle and atomization is promoted.

  The atomization nozzle according to the present invention can be widely applied to an apparatus for atomizing a liquid into a mist. For example, it can be used for a coating machine, a humidifying device, a chemical spraying device, a powder production device using a freeze drying method, and the like. Also, new fields are expected to be applied to sterilization and odor removal by mist, improving the efficiency of air conditioners by mist (air cooling of outdoor units), fire extinguishing devices by mist, and reducing the amount of solar radiation by mist.

It is a figure which shows one embodiment of the two-fluid nozzle of this invention. It is a figure which shows another one Example of embodiment of the two-fluid nozzle of this invention. FIG. 3 is a diagram showing a modification of the embodiment shown in FIG. 2. It is a figure which shows another one Example of embodiment of the two-fluid nozzle of this invention. It is a figure which shows the modification of the two-fluid nozzle of this invention shown in FIG. It is a figure which shows one Example of the spraying apparatus using the two-fluid nozzle of this invention. It is a figure which shows the typical form of the conventional two fluid nozzle. It is a figure which shows another typical form of the conventional two-fluid nozzle.

DESCRIPTION OF SYMBOLS 1 Two-fluid nozzle 2 Spraying device 11 Liquid nozzle 11a Liquid nozzle exit 12 Gas nozzle 12a Gas nozzle exit 12b Gas nozzle inner wall surface 13 Liquid film formation nozzle 13b Liquid film formation surface 13c Liquid film formation nozzle outer wall surface 14 Liquid supply 14a Liquid flow Passage 14b spiral passage 14c liquid distribution passage 14d opening 15 base 15a gas inflow passage 15b liquid inflow passage 16 annular opening 17 gas passage 18 gas swirl vane 21 air pump 22 liquid container 23 atomization gas piping 24 liquid piping 25 Gas piping for pressurization

Claims (3)

Gas nozzle, becomes liquid film forming nozzle, the liquid dispensing nozzle, and from the base, the liquid film forming nozzle is arranged in the gas nozzle and coaxial, the inner peripheral wall forming a liquid film forming surface of the universal type versus rotation The liquid distribution nozzle is provided with a plurality of spiral channels arranged at the outer periphery of the center axis and in a twisted position. The liquid channel is connected to the liquid channel and the liquid channel, and extends radially. A liquid distribution channel that opens to the spiral channel, and part of the gas becomes an annular jet from an annular opening formed between the outlet of the gas nozzle and the outlet of the liquid film forming nozzle. The remaining part of the gas flows into the spiral flow path, blows off the liquid flowing out from the opening of the liquid distribution flow path to the spiral flow path through the liquid flow path, and then forms the liquid film formation surface. A swirling airflow is generated along A liquid film is formed on the liquid film forming surface by the action of the swirling airflow, and flows out as an annular liquid film from the outlet of the liquid film forming nozzle. A two-fluid nozzle characterized in that it is swirled along the liquid film forming surface and is atomized by being swung between the swirling jet ejected from the liquid film forming nozzle outlet and the annular jet from the outer peripheral side.   Means for turning the annular jet ejected from the annular opening is disposed in a gas flow path formed by the outer wall surface of the liquid film forming nozzle and the inner wall surface of the gas nozzle. The two-fluid nozzle according to claim 1. The liquid dispensing nozzle at the distal end, provided with the liquid film forming nozzle and the rotational symmetry shaped center body coaxially, the diameter of the liquid film forming surface of the liquid film forming nozzle is characterized in that the expanding towards the outlet The two-fluid nozzle of Claim 1 or Claim 2.

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