JP3605378B2 - Vapor diffusion spray humidification method and humidifier - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a humidification method and a humidification device used for an air conditioner, and more particularly to a humidification method and a humidification device of a vapor diffusion spray type.
[0002]
[Prior art]
A method is known in which a diffusion plate is installed on the lee side of a steam spray pipe, and steam is diffused by a vortex generated by the diffusion plate.
A method is also known in which a diffusion plate is arranged on the windward side of a steam spray section as shown in FIG. 16 and the steam is diffused by a vortex generated by the diffusion plate.
[0003]
[Problems to be solved by the invention]
In steam humidifiers, it seems that steam quickly dissolves into the airflow, and ideal humidification can be performed.However, in practice, the steam after spraying condenses and condenses on the inner surface of the air conditioner and fans. It is often seen. Condensation and condensation of the vapor may cause rust in ducts, fans and other parts, and may cause bacteria to propagate, which is extremely undesirable. On the other hand, recent air conditioners have been miniaturized, and in a humidifier provided in the miniaturized air conditioner, sufficient evaporation of steam is desired over a very short distance after steam spraying. Without the above, there is a problem that the above-mentioned problem of preventing rusting and bacterial propagation cannot be solved.
[0004]
Further, in the humidifier as shown in FIG. 16, since the steam is supplied from below the diffusion plate, the rising distance of the steam ejected vertically upward from the spray hole differs depending on the amount of the ejected steam. As shown in FIG. 17, when the steam amount is small, it becomes low, and as shown in FIG. 18, it becomes high when the steam amount is large. The difference in steam density on the spray surface due to the difference in the rising distance of the steam generated at this time cannot be made uniform even by the effect of the diffusion plate installed upstream.
[0005]
Further, in the above-mentioned known humidifier, the supply steam pressure may increase at the terminal spray hole of the spray pipe, and as a result, the amount of steam at the terminal spray hole may increase as shown in FIG. . Also, as shown in FIG. 20, there is a case where the reverse is the case, so that there is a problem that uniform steam supply cannot be performed.
[0006]
In addition, the steam has a characteristic that it gradually gathers vertically upward in the airflow after the humidifier due to the difference in specific gravity from the air. In the above-mentioned known humidifier, there is no mechanism having a measure against this phenomenon, so that even if a sufficient distance is secured, the inside of the air conditioner, the fan and the like will be wetted.
[0007]
The present invention has been made in view of the above-mentioned problems of the known art, and makes uniform steam supply to the humidifying space, and further reduces the diffusion distance and the evaporation distance of the steam, obtains efficient humidification, and forms condensation and steam. The purpose is to prevent condensation as much as possible, to eliminate the adverse effects on air conditioners, and to make it sanitary. Also, prevent the drain water from being mixed into the spray vapor, and it is easy to evaporate uniformly from the humidifier It is an object to obtain effective humidification by supplying only steam to the humidification space.
[0008]
[Means for Solving the Problems]
For this purpose, the vapor diffusion spray type humidification method and the vapor diffusion spray type humidifier of the present invention provide a spray tube having a spray hole, arrange the spray hole on the windward side, provide a diffusion box having an opening, and provide a diffusion box having the opening. Is located on the leeward side, and the spray tube and the diffusion box are positioned opposite to each other with the spray tube positioned in a negative pressure region formed by the diffusion box, and vapor sprayed from the spray hole of the spray tube is generated by the diffusion box. It was made to diffuse by eddy current. That is, in the present invention, the diffusion of the vapor is defined as a diffusion box, and since the spray pipe is arranged in the negative pressure region formed by the diffusion box, even if the flow velocity of the steam ejected from the spray hole changes, The vapor is always attracted to the diffusion box in the same state, and the vapor attracted into the diffusion box moves while forming a vortex along the inner wall of the diffusion box, so coarse vapor particles are captured at the inner wall of the diffusion box at that time As a result, only vapor that is likely to evaporate homogeneously is discharged out of the diffusion box.
[0009]
Further, in the vapor diffusion spray type humidification method and the vapor diffusion spray type humidification device of the present invention, a negative pressure region is provided outside the diffusion box to re-diffuse the vapor. That is, the vapor once discharged from the diffusion box is again attracted to the negative pressure area outside the diffusion box, so that the contact time with air is extended and the evaporation distance is shortened.
[0010]
Furthermore, in the vapor diffusion spray type humidifier of the present invention, the spray holes are oriented so that the steam from the spray holes is jetted toward the central axis of the diffusion box. As a result, the diffusion of the vapor in all directions is made uniform, and the evaporation distance of the vapor is shortened.
[0011]
In the vapor diffusion spray type humidifier of the present invention, the diffusion box has a shape such that the area of the opening of the diffusion box is equal to or smaller than the projected area of the surface opposite to the opening of the diffusion box. A negative pressure portion region is formed outside. For example, specifically, a negative pressure section region is formed by providing a re-diffusion plate outside the diffusion box or by inclining the side wall of the diffusion box inward. That is, the negative pressure region formed around the diffusion box is enlarged by this configuration, and the evaporation distance of the steam can be further reduced.
[0012]
Furthermore, in the vapor diffusion spray type humidifier of the present invention, a plurality of the above-described diffusion boxes are provided, and the diffusion boxes are provided to face each spray hole group including one or more spray holes. That is, the vapor diffusion can be made uniform by the opposed arrangement of the spray hole group and the diffusion box.
[0013]
Further, in the vapor diffusion spray type humidifier of the present invention, a space through which an airflow passes is provided between the diffusion boxes, and the diffusion boxes are arranged at intervals. That is, an airflow can be passed between the diffusion boxes provided opposite to the spray hole groups, and the vapor diffused by the adjacent diffusion boxes can be prevented from interfering with each other downstream.
[0014]
Furthermore, in the vapor diffusion spray type humidifier of the present invention, the total area value of each spray hole group including one or two or more spray holes corresponding to the diffusion box is set at the tip side with respect to the inflow direction into the spray pipe. It is set to be small. That is, this makes it possible to equalize the amount of steam in each spray hole of the steam spray tube, and when the steam flow rate per spray hole is 3 m / s or more, the spray hole at the end of the spray tube in the steam inflow direction is formed. Since the amount of steam increases, by setting the spray hole diameter from the steam inflow direction to the terminal direction so as to gradually become smaller, uniform planar spray can be performed. Also, by making the spray hole diameter of the steam spray tube equal to each of the plurality of diffusion boxes and decreasing the number of spray holes sequentially from the steam inflow direction to the terminal direction, a uniform planar steam spray can be obtained. You can do it.
[0015]
Further, in the vapor diffusion spray type humidifier of the present invention, the pitch between the spray hole groups consisting of one or two or more spray holes corresponding to the diffusion box is located on the tip side with respect to the direction of steam flow into the spray pipe. The size is set so as to be large, and the size of the diffusion box is set to correspond to the pitch between the spray hole groups. That is, in a steam spray tube having a plurality of spray holes, the diameter of each spray hole of the steam spray tube is made equal, and the pitch between the spray hole groups is changed and assigned according to the amount of steam of each spray hole. When the dimensions of a plurality of diffusion boxes are set in accordance with the inter-pitch, the diffusion boxes having individual dimensions uniformly diffuse steam with respect to the spray cross-sectional area of the humidifying space according to the steam amount at each spray hole. Therefore, the vapor density is equal in any of the diffusion boxes, and the vapor can be sprayed in a uniform plane.
[0016]
Further, the vapor diffusion spray type humidifier of the present invention has a casing that covers the entire periphery of each and the entirety of a pair or two or more pairs of the spray pipe and the diffusion box. That is, the effect of agitating steam and air becomes stable and the best, so that steam can be sprayed in a uniform plane.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments will be described with reference to the drawings. In FIG. 1, reference numeral 6 denotes a steam spray tube, and reference numeral 5 denotes one or two or more spray holes. Then, the spray hole 5 provided in the spray pipe 6 is arranged on the windward side, a diffusion box 7 having an opening is provided, and the opening is arranged on the leeward side. Numeral 6 is positioned in the negative pressure region 8 formed by the diffusion box 7 so as to be opposed thereto, so that the vapor sprayed from the spray hole 5 of the spray pipe 6 is diffused by the vortex generated by the diffusion box 7. If the depth of the diffusion box, that is, the distance from the bottom surface of the diffusion box to the opening surface is large, the diffusion effect cannot be expected, so this distance is preferably 300 mm or less. The spray hole 6 has a cylindrical projection 16 directed toward the inside of the spray pipe, and separates the steam and the drain generated in the pipe to supply only the steam to the diffusion box 7.
[0018]
As shown in FIG. 2, by disposing the spray pipe 6 in the negative pressure area 8 formed by the diffusion box 7 upstream of the spray pipe 6, even if the flow velocity of the steam ejected from the spray pipe 6 changes, Is always attracted to the diffusion box in the same state. That is, even when the flow velocity of the steam is low, the steam is reliably guided into the diffusion box. As in the steam flow 9 shown in FIG. 2, the steam drawn into the diffusion box 7 moves while forming a vortex along the inner wall of the diffusion box. Therefore, only a uniform vapor of about 10 μm which is easily evaporated is released to the outside of the diffusion box. Further, the vapor once discharged from the diffusion box is again attracted by the negative pressure section regions 10 and 11 formed around the upstream end of the diffusion box. The effect of extending the contact time between air and steam has the effect of shortening the evaporation distance.
The reason why steam is re-attracted in the negative pressure region generated upstream of the diffusion box is that a vortex is generated at the corner of the upstream end of the diffusion box, and the shape of the upstream end of the diffusion box is close to a right angle or less than a right angle. Preferably, a gentle curve (R-bend) or an obtuse angle does not have the effect of making it difficult to generate a vortex.
[0019]
In addition, as shown in FIG. 3, when the re-diffusion plates 12 and 13 for re-diffusion are installed around the diffusion box, the area of the negative pressure portion formed around the diffusion box is enlarged, so that the evaporation distance can be further reduced. Can be. The re-diffusion plate is disposed so as to have an angle with respect to a plane parallel to the air flow. Here, the phenomenon that the steam is re-attracted to the negative pressure section region 11 formed particularly at the lower part of the diffusion box suppresses the vertical upward transfer of the steam due to the difference in specific gravity between the steam and the air downstream of the steam atomizer. Has the effect of doing In addition, in order to obtain the effect of enlarging the negative pressure portion area around the diffusion box, as shown in FIGS. 4 and 5, the opening area of the diffusion box may be formed to be smaller than the projection area of the opposing surface. . For this purpose, the re-diffusion plates 12 and 13 may be provided, or the side walls 14 and 15 of the diffusion box may be inclined inward. Here, the side walls may be the upper and lower side walls or the left and right side walls of the diffusion box.
[0020]
Since there is a limit to the width of the diffusion box in order to have a uniform vapor diffusion effect, it is not possible to diffuse steam at a uniform density in the width direction with one diffusion box in the longitudinal direction of the spray pipe. The vapor diffusion in the lateral direction can be made uniform by providing a plurality of spray holes 5 of the spray pipe 6 so as to face each other (see FIG. 6). Also, as shown in FIG. 7, by providing a space 17 through which an airflow passes between the diffusion boxes provided in the spray holes 5, it is possible to prevent the vapors sprayed from the adjacent diffusion boxes from interfering with each other on the downstream side. Can be prevented. Therefore, the evaporation effect can be obtained more efficiently.
[0021]
FIG. 8 shows an embodiment of the steam spray state in the steam spray apparatus of the present invention. The graph shown in FIG. 9 shows the amount of steam at each spray hole 5, and the total amount per one hole in the steam spray pipe 6. This is an example where the average vapor flow rate is 10 m / s and the spray hole diameter is φ10. It can be seen that the amount of steam is larger in the spray hole 5 at the end of the spray pipe 6 in the steam inflow direction. In order to equalize the amount of steam in each of the spray holes 5, in the example shown in FIG. 10, the hole diameter is set to φ21, φ19, φ17.5, φ15, φ13 (mm) in order from the steam inflow direction. This makes it possible to perform a wide area spray. Further, as in the example shown in FIG. 11, the diameter of the spray hole of the steam spray tube is made equal to each of the plurality of diffusion boxes (φ9), and the number of spray holes is sequentially set to 6, 5, 4 from the steam inflow direction to the terminal direction. , 3 and 2 can also provide uniform planar steam spray.
[0022]
As in the example shown in FIG. 12, in a steam spray pipe 6 having a plurality of spray holes 5, each spray hole diameter of the steam spray pipe 6 is made equal, and two spray holes 5 are formed as one group. In accordance with the steam amount, the pitch between the spray hole groups is changed and assigned. That is, the pitch between the spray hole groups is set with respect to the difference in the amount of steam between the spray hole groups, and the spray hole groups are sequentially set as a first hole group, a second hole group, and a third hole group from the front of the steam inflow direction. Assuming that the respective steam amounts are G1, G2, and G3, in the second hole group, the vapor is diffused and sprayed in an area (G2 / G1) times the area in which the first hole group is diffused and sprayed. This means that the vapor density is made uniform in the cross section of the airflow by spraying the steam in an area (G3 / G1) times the area of the first hole group for diffusion spraying. Therefore, since the widths of the plurality of diffusion boxes are individually set in accordance with the pitch between the spray holes, the diffusion boxes are uniformly spread in the width direction of the humidified space even when the vapor amount of each spray hole is different. Since the vapor is diffused, the vapor density on the cross section of the air flow becomes uniform. FIG. 13 shows an example in which a diffusion box having a width of 1000 mm is considered based on the data in the graph of FIG.
[0023]
In the steam atomizer of the present invention, it is important that the negative pressure portion around the diffusion box is always stable, and the above-described stirring and diffusion of the steam and air is only performed when a stable airflow is always supplied around the diffusion box. The effect will be obtained. Therefore, as shown in FIGS. 14 and 15, by providing the spray pipe 6 and the casing 18 surrounding the diffusion box, a stable and uniform planar vapor spray effect can be obtained.
[0024]
The test was performed with the device of the present invention under the following conditions.
Conditions, inlet air temperature = 15 ° C, wind speed = 2.5m / s,
Vapor amount = corresponding to a saturation efficiency of 60% The following results were obtained.
With casing: evaporation distance 500mm
Without casing: evaporation distance 800mm
Similarly, in order to compare the evaporation distance between the conventional steam atomizer having a diffusion plate on the upstream side and the steam atomizer of the present invention, a test was performed under the following conditions.
Conditions, inlet air temperature = 15 ° C, wind speed = 2.5m / s,
Vapor amount = corresponding to a saturation efficiency of 60% The following results were obtained.
Evaporation distance of conventional steam spraying apparatus having a diffusion plate on the upstream side: 1500 mm
Evaporation distance of the steam atomizer according to the present invention: 500 mm
[0025]
【The invention's effect】
The vapor diffusion spray type humidification method and the vapor diffusion spray type humidifier of the present invention are provided with a spray pipe having a spray hole, the spray hole is arranged on the windward side, a diffusion box having an opening is provided, and the opening is located on the leeward side. And the spray tube and the diffusion box are positioned opposite each other with the spray tube positioned in a negative pressure region formed by the diffusion box, and the vapor sprayed from the spray hole of the spray tube is diffused by the vortex generated by the diffusion box. Therefore, even if the flow velocity of the steam ejected from the spray hole changes, the steam is always drawn into the diffusion box in the same state, and the steam drawn into the diffusion box forms a vortex along the inner wall of the diffusion box. At that time, coarse vapor particles are captured by the inner wall of the diffusion box, and only the vapor that is easy to evaporate is discharged out of the diffusion box to form a uniform planar steam supply to the humidified space. To obtain the vapor diffusion distance and evaporation distance Can be shortened, good humidification is obtained a hygienic and efficient. Further, it has the effect of equalizing the amount of steam at each spray hole of the steam spray pipe and keeping the steam density in the cross section of the humidified space constant. Furthermore, by shortening the vapor diffusion and evaporation distance, it is possible to reduce the humidification space of air conditioners and ducts, and also to incorporate them into small spaces. There is also an economic effect of extending the life of each component in the aircraft.
[0026]
In addition, the vapor diffusion spray type humidification method and the vapor diffusion spray type humidification device of the present invention provide a negative pressure portion area outside the diffusion box so as to re-diffuse the steam, so that the steam was once discharged from the diffusion box. The vapor is again attracted to the negative pressure area outside the diffusion box, so that the contact time with the air is prolonged and the evaporation distance is shortened.
[0027]
Furthermore, in the vapor diffusion spray type humidifier of the present invention, since the spray holes are directed so as to inject the steam from the spray holes toward the central axis of the diffusion box, the diffusion of the steam in all directions is uniform. This has the advantage of shortening the evaporation distance of the steam.
[0028]
In the vapor diffusion spray type humidifier of the present invention, the diffusion box has a shape such that the area of the opening of the diffusion box is equal to or smaller than the projected area of the surface opposite to the opening of the diffusion box. A negative pressure portion region is formed outside. For example, specifically, a re-diffusion plate is provided on the outside of the diffusion box, or the side wall of the diffusion box is inclined inward to form a negative pressure portion region. The reduced negative pressure region is expanded, and the vapor evaporation distance can be further reduced.
[0029]
Further, in the vapor diffusion spray type humidifier of the present invention, since the plurality of diffusion boxes are provided and the diffusion boxes are provided to face each spray hole group including one or two or more spray holes, a plurality of diffusion boxes are provided. There is an advantage that the vapor diffusion can be made uniform by the opposed arrangement.
[0030]
Further, in the vapor diffusion spray type humidifier of the present invention, since a space through which the airflow passes is provided between the diffusion boxes and the diffusion boxes are arranged at intervals, the airflow is provided between the diffusion boxes provided opposite to the spray hole groups. It is possible to prevent the vapor that is passed and diffused in the adjacent diffusion box from interfering with each other downstream, and efficient humidification can be obtained.
[0031]
Furthermore, in the vapor diffusion spray type humidifier of the present invention, the total area value of each spray hole group including one or two or more spray holes corresponding to the diffusion box is set at the tip side with respect to the inflow direction into the spray pipe. Is set to be smaller, the amount of steam in each spray hole of the steam spray tube can be equalized, and when the steam flow rate per hole is 3 m / s or more, the steam inflow direction of the spray tube Since the amount of steam in the spray holes on the terminal side increases, by setting the diameter of the spray holes in the terminal direction sequentially smaller from the steam inflow direction, uniform planar spray can be performed. Also, by making the spray hole diameter of the steam spray tube equal to each of the plurality of diffusion boxes and decreasing the number of spray holes sequentially from the steam inflow direction to the terminal direction, a uniform planar steam spray can be obtained. There is an effect that can be done.
[0032]
Further, in the vapor diffusion spray type humidifier of the present invention, the pitch between the spray hole groups consisting of one or two or more spray holes corresponding to the diffusion box is located on the tip side with respect to the direction of steam flow into the spray pipe. It is set to be large, and the diffusion box size is set to correspond to the pitch between the spray hole groups, so that in a steam spray tube having a plurality of spray holes, each spray hole diameter of the steam spray tube is made equal, The pitch between the spray hole groups is changed and assigned according to the vapor amount of each spray hole, and when the dimensions of a plurality of diffusion boxes are set in accordance with the pitch between the spray hole groups, each of the diffusion boxes has an individual size. Since the diffusion box uniformly diffuses the vapor with respect to the cross-sectional area of the humidified space in accordance with the amount of vapor at each spray hole, the vapor density is equal in each diffusion box, and the vapor is sprayed in a uniform plane. so There is an advantage in that.
[0033]
In addition, the vapor diffusion spray type humidifier of the present invention has a casing that covers the individual and entire circumferences of a pair or two or more pairs of the spray tube and the diffusion box, thereby providing the effect of stirring steam and air. Is stable and the best, and a uniform surface can be sprayed with steam.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a combination of a diffusion box and a steam spray tube of the humidifier of the present invention. FIG. 2 is an explanatory view showing a steam flow of the humidifier of the present invention. FIG. FIG. 4 is a cross-sectional view of an embodiment in which the side walls of the diffusion box are inclined obliquely inward. FIG. 5 is an embodiment in which a re-diffusion plate and a side wall in which the side walls are inclined obliquely are combined. FIG. 6 is a schematic view of a structure in which a diffusion box is provided in each of a plurality of vapor spray holes. FIG. 7 is a schematic view of a structure in which an airflow is provided between diffusion boxes. FIG. 8 is a steam spray tube of the present invention. FIG. 9 is a graph showing the steam flow per hole in the steam spray tube shown in FIG. 8; FIG. 10 is a schematic diagram showing the case where the spray hole diameter of the steam spray tube in FIG. 7 is individually set; FIG. 11 is a schematic diagram in the case where the number of spray holes of the steam spray pipe of FIG. 7 is individually set. FIG. 13 is a schematic diagram showing a case in which the pitch between spray hole groups and the width of the diffusion box are set according to the amount of steam in each steam spray hole group in a combination of boxes. FIG. 15 is a schematic front view of a combination of a steam spray tube and a diffusion box and a casing installed therearound. FIG. 15 is a schematic side view of a combination of a steam spray pipe and a diffusion box and a casing installed therearound. FIG. 17 is an explanatory view showing an example of a spray state of a conventional steam humidifier. FIG. 17 is an explanatory view showing an example of a vertical steam distribution with a small amount of steam of a conventional steam humidifier. FIG. 18 is a steam amount of a conventional steam humidifier. FIG. 19 is an explanatory diagram showing an example of a vertical steam distribution with a large amount. FIG. 19 is an explanatory diagram showing an example of a steam distribution when a supply steam pressure to a conventional steam humidifier is high. FIG. 20 is a supply to a conventional steam humidifier. When the vapor pressure is low Explanatory view showing an example of a steam distribution EXPLANATION OF REFERENCE NUMERALS
5 Spray hole 6 Steam spray pipe 7 Diffusion box 8 Negative pressure area 9 Steam flow 10, 11 Negative pressure section area 12, 13 Redistribution plate 14, 15 Side wall 16 Cylindrical projection 17 Space 18 Casing

Claims (11)

A spray tube having a spray hole is provided, the spray hole is arranged on the leeward side, a diffusion box having an opening is provided, and the opening is arranged on the leeward side. Positioned and opposed to a negative pressure region formed by a diffusion box, so that vapor sprayed from a spray hole of a spray pipe is diffused by a vortex generated by the diffusion box, and a negative pressure part region is provided outside the diffusion box. A vapor diffusion spray humidification method in which the vapor is rediffused. A spray tube having a spray hole is provided, the spray hole is arranged on the leeward side, a diffusion box having an opening is provided, and the opening is arranged on the leeward side. Positioning and facing the negative pressure region formed by the diffusion box, so that the vapor sprayed from the spray hole of the spray pipe is diffused by a vortex generated by the diffusion box, and a negative pressure portion region is provided outside the diffusion box, A vapor diffusion spray humidifier that re-diffuses steam. 3. The vapor diffusion spray type humidifier according to claim 2 , wherein the spray holes are directed so as to inject steam from the spray holes toward a central axis position of the diffusion box. The billing area of the opening of the diffusion box is located as the shape of equal to or less made such diffusion box than the projected area of the opposite surface to the opening portion of the diffusion box, which forms a negative pressure region outside the diffusion box Item 4. A vapor diffusion spray humidifier according to item 2 or 3 . 5. The vapor diffusion spray type humidifier according to claim 4 , wherein a re-diffusion plate is provided outside the diffusion box to form a negative pressure portion region. The vapor diffusion spray type humidifier according to claim 4 , wherein the side wall of the diffusion box is inclined inward to form a negative pressure section region. The vapor diffusion spray type humidifier according to any one of claims 2 to 6 , wherein a plurality of the diffusion boxes are provided, and the diffusion boxes are provided to face each spray hole group including one or two or more spray holes. apparatus. The vapor diffusion spray type humidifier according to claim 7 , wherein a space through which an air current passes is provided between the diffusion boxes, and the diffusion boxes are arranged at intervals. 9. The method according to claim 7, wherein the total area value of each spray hole group including one or two or more spray holes corresponding to the diffusion box is set to be smaller on the distal end side with respect to the inflow direction to the spray pipe. 9. The vapor diffusion spray type humidifier according to 8 . The pitch between the spray hole groups consisting of one or more spray holes corresponding to the diffusion box is set to be larger on the distal end side with respect to the direction of vapor flow into the spray pipe, and the diffusion box size is set to this value. 9. The vapor diffusion spray type humidifier according to claim 7 , wherein the vapor diffusion spray type humidifier is set to correspond to the pitch between the spray hole groups. The vapor diffusion spray type humidifying device according to any one of claims 2 to 10 , further comprising a casing that covers the individual and entire circumferences of the device composed of a pair or two or more pairs of a spray tube and a diffusion box.

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