JP2000107626A - Fluidized bed type jet pulverizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluidized bed type jet pulverizer excelling in pulverizing efficiency. SOLUTION: This jet pulverizer consists at least of a pulverizing chamber 3 having a central axis, an impact member 7 installed inside the pulverizing chamber 3, and nozzles 5 for jetting high velocity gas toward the impact member 7. In this case, the nozzles 5 are installed in a multistage manner, and when the nozzles 5 are viewed from right above, the nozzles in the upper stage and the nozzles in the lower stage are not placed one upon another.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fluidized-bed jet pulverizer.

[0002]

2. Description of the Related Art A fluidized bed type jet pulverizer generally includes a pulverizing chamber, a collision member and a nozzle, and uses a high-speed gas injected from a plurality of nozzles to pulverize coarse particles. ing. Specifically, the object to be crushed is placed on the high-speed gas ejected from a plurality of nozzles installed on one horizontal plane, and the high-speed gas including the object to be crushed is applied to the collision member installed at the center of the crushing chamber. The object to be crushed is crushed by colliding the object (Japanese Patent Application Laid-Open Nos. 4-271853 and 8-11).
No. 2543). However, such a pulverizer takes too much time to obtain particles having a desired particle size, and has a problem in pulverization efficiency (pulverization ability).

In order to improve the pulverization efficiency, attempts have been made to increase the number of nozzles. However, as the number of nozzles increases, the collision points between the high-speed gas and the collision member approach each other. There has been a problem that the high-speed gas flows interfere with each other and are decelerated, which in turn lowers the grinding efficiency. Although it is conceivable to increase the size of the collision member in order to avoid excessive approach of the collision point, the above problem cannot be solved because a dead space is formed below the enlarged collision member.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fluidized-bed jet pulverizer excellent in pulverization efficiency.

[0005]

Means for Solving the Problems The present invention provides at least:
A crushing chamber having a central axis, a collision member installed inside the crushing chamber, and a fluidized bed jet crusher including a nozzle that injects high-speed gas toward the collision member, wherein the nozzles are provided in multiple stages, The present invention relates to a fluidized bed jet pulverizer characterized in that an upper nozzle and a lower nozzle do not overlap when viewed from directly above.

Hereinafter, a description will be given of the case where the pulverizer of the present invention is provided with two nozzles. The nozzle is provided with n stages (hereinafter, n is an integer of 3 or more). In this case, the present invention is applicable by applying the following description. When the nozzles are installed in n stages, the first stage, the second stage,...
When the (n-1) th stage and the nth stage, the flow path of the high-speed gas derived from the nozzle at the tth stage (t is an arbitrary integer from 3 to n) is (t− 1) It is only necessary that the airflow is not hindered by the updraft from the nozzle up to the stage.

The crusher of the present invention comprises at least a crushing chamber 3 having a central axis, a collision member 7 installed inside the crushing chamber, and a nozzle 5 for jetting high-speed gas toward the collision member. (See FIG. 1A).

In the pulverizer of the present invention, the nozzles are installed in two stages, an upper stage and a lower stage, horizontally toward the central axis of the pulverizing chamber. By arranging the nozzles in the upper and lower stages in this manner, it is possible to prevent the collision point between the high-speed gas and the collision member from excessively approaching, so that the deceleration of the high-speed gas flow is prevented and the pulverization efficiency is improved. The height difference between the upper nozzle and the lower nozzle, that is, the distance between the nozzle axis of the upper nozzle and the nozzle axis of the lower nozzle is 10 mm or more, and preferably 15 mm or more.
mm or more is desirable. The height difference is 10 mm
If it is less than the above, the high-speed gas flow is decelerated due to the excessive approach of the collision points described above, and the pulverization efficiency is reduced.

Further, in the pulverizer of the present invention, the upper nozzle and the lower nozzle do not overlap when the nozzles are viewed from directly above. That is, when the nozzles are viewed from directly above, the upper nozzles do not overlap with any of the lower nozzles. Specifically, each upper nozzle is 30 ° closer to the nearest lower nozzle in the top view when the nozzle is viewed from directly above.
As described above, it is desirable that the device is installed so as to form an angle of preferably 40 ° or more. By avoiding the overlap between the upper nozzle and the lower nozzle when the nozzle is viewed from directly above, the upward airflow (reflected flow) derived from the lower nozzle becomes a flow path of the high-speed gas flow derived from the upper nozzle. Therefore, it is considered that the pulverization efficiency is further improved. If the angle is less than 30 °, the upward air flow tends to obstruct the flow path of the high-speed gas flow from the upper nozzle, which is not preferable.

It is preferable that the nozzles are arranged at equal intervals in each stage so as to have symmetry. More preferably, all nozzles are arranged at equal intervals when the nozzles are viewed from directly above. It is desirable that the number of nozzles is 2 or more, preferably 2 to 6 in each stage.
In addition, it is more preferable that the number of nozzles in each stage is the same from the viewpoint of achieving uniform particle diameter of the obtained fine particles. Air, nitrogen, carbon dioxide, or the like is used as the high-speed gas injected from the nozzle.

Further, for each nozzle in each stage, an angle (hereinafter, referred to as an angle α) between the nozzle axis and the collision member in a longitudinal section including the nozzle axis and the center axis of the pulverizing chamber (hereinafter, referred to as a central longitudinal section). 25-80 °, preferably 40-
Preferably, it is 70 °. In the present specification, the angle α is, as shown in FIG. 6A, an angle formed between the nozzle axis n and the surface of the collision member 7 in a central longitudinal section p including the nozzle axis n and the center axis m of the pulverizing chamber. Point to. In the present invention, by controlling the angle α in the central longitudinal section within the above range, the colliding high-speed gas is released upward,
Since it is possible to forcibly avoid the flow of the high-speed gas into the region below the collision member, it is considered that the pulverization and classification are performed effectively, and the pulverization efficiency is improved. If the angle α is less than 25 °, the object to be pulverized (hereinafter, referred to as the object to be pulverized) is not effectively pulverized, and it is difficult to efficiently obtain a pulverized object having a desired particle size.
On the other hand, if the angle α exceeds 80 °, the high-speed gas after the collision including the pulverized material tends to act as the back pressure of the high-speed gas before the collision which is continuously injected to pulverize the object to be pulverized. In addition, the speed of the material to be ground in the high-speed gas is reduced, so that the material to be ground is not effectively ground, and it is difficult to efficiently obtain the ground material having a desired particle size.

In the present invention, the nozzle 5 is arranged as shown in FIG.
As shown in (b), the collision member 7 in the central longitudinal section p
If the angle α can be secured in relation to the above, the nozzle axis n may be installed so as to form a certain angle γ upward with respect to the horizontal plane h. The nozzle inclination angle γ may be appropriately set so that the angle α falls within the above range as described above, but is 10 to 65 °, preferably 20 to 5 °.
0 ° is preferred.

Further, in the present invention, it is preferable that all nozzles have a constant distance from the tip of the nozzle to the collision member. Here, "distance from nozzle tip to collision member"
Means a distance L from the tip of the nozzle to an intersection A between the nozzle axis n and the surface of the collision member, as shown in FIGS. 6 (a) and 6 (b). In this way, by keeping the distance L constant for each nozzle, the particle size of the obtained fine particles can be made uniform. In the present invention, particularly, the ratio L / r between the distance L and the nozzle inner diameter r is 1
5 or more, preferably 15 to 45, more preferably 25 to
It is preferably 45. By controlling the ratio, the pulverization efficiency can be further improved. In this specification, the nozzle inner diameter r indicates the inner diameter at the opening of the nozzle.

The collision member in the crusher of the present invention is installed inside the crushing chamber having a central axis so as to be centered on the central axis. In the present invention, a single collision member may be provided, or a plurality of collision members may be provided.

When a single collision member is installed, the shape of the collision member is such that it has a surface that can face all the nozzles and can secure an angle α in the central longitudinal section for all the nozzles. If it is not particularly limited, for example, a cone, a pyramid, a sphere, a hemisphere, a prism,
It may have any shape such as a cylindrical shape, but preferably has a cone shape such as a conical shape or a pyramid shape. When the shape of the collision member is a pyramid or a prism, the shape of the collision member is preferably determined depending on the number of nozzles and the installation position. For example, in each stage, two nozzles are installed at equal intervals. In this case, the collision member is preferably a regular pyramid or a regular prism. If three nozzles are installed at equal intervals in each stage, the collision member may be a regular hexagonal pyramid or a regular hexagonal prism. preferable. In the case where the collision member shape is conical, cylindrical, spherical or hemispherical, it does not depend on the number of nozzles, as long as the collision points between the high-speed gas and the collision member do not excessively approach each other. Can be adopted.

When a single hemispherical or spherical impact member is used, the angle α is, as shown in FIG. 7, the nozzle axis n at the center longitudinal section p including the nozzle axis n and the grinding chamber center axis m.
And the plane S contacting the collision member 7 at the intersection A between the nozzle axis n and the collision member 7. In this case, the angle α can be controlled within the above specified range by appropriately setting the position of the intersection A between the nozzle axis n and the collision member 7. In particular, when the shape of the collision member is spherical, the angle α can be ensured by setting the high-speed gas to hit the upper half of the spherical member.

The size of the collision member is such that most of the high-speed gas injected from all the nozzles can be deflected against the collision member. For example, inner diameter 100mm, height 3
In the 33 mm crushing chamber, two nozzles having an inner diameter of 2 mm are installed horizontally at equal intervals in each of the upper and lower stages (the height difference between the upper and lower nozzles; 20 m
m) using, for all of the nozzles in the injection pressure of 6 kg / cm ^2, when performing ground by L / r15, the diameter of the member bottom surface (circular) when using impact member conical 25
The height is preferably from 30 to 50 mm.

When a plurality of collision members are provided, it is preferable that the same number of collision members as the number of nozzles are provided for each nozzle so as to face the nozzles. At this time, it is more preferable that all the collision members are arranged so as to have symmetry with respect to the center axis of the grinding chamber. The shape of each collision member is not particularly limited as long as each collision member and the nozzle installed opposite thereto can secure the above-mentioned angle α, and is the same as when the collision member is installed alone. Can be exemplified. Among these, the shape of each collision member is preferably spherical or hemispherical, and from the viewpoint of making the particle diameter of the obtained fine particles uniform, it is preferable that all collision members have the same shape. When the shape of the collision member is a hemisphere or a sphere, the angle α indicates the same angle as when a single hemisphere or a spherical collision member is used.

The size of each of the collision members is set so that most of the high-speed gas injected from the nozzle provided opposite to each of the collision members can be deflected against the collision member. For example, using a nozzle with an inner diameter of 2 mm, 6 kg
When grinding at L / r15 with an injection pressure of / cm ² ,
When a spherical collision member is used, the diameter is preferably 25 to 40 mm.

As the material for the collision member, it is preferable to use a material that is relatively hard and resistant to wear. Examples of the material include ceramics, cemented carbide, Colmonoy cemented carbide, nitrided steel, and stainless steel. Alternatively, a material coated on stainless steel or the like which is easy to mold may be used.

Hereinafter, a preferred embodiment of the pulverizer of the present invention in which two nozzles are installed in each of the upper and lower stages will be described. However, the present invention should not be construed as being limited thereto, and any number of nozzles may be used. Even if the nozzles are installed in multiple stages up and down, and if the upper nozzle does not overlap the lower nozzle in the top plan view when the nozzle is viewed from directly above, it is clear that the present invention is within the scope of the present invention. is there.

As a preferred embodiment of the collision member and the nozzle in the crusher of the present invention, a crusher as shown in FIG. 1 can be exemplified. FIG. 1A is a schematic longitudinal sectional view of a crusher, and FIG. 1B is a view when the lower part of the crushing chamber in FIG. FIG. 1C is a schematic perspective view, and FIG. 1C is a schematic perspective view of a collision member and a nozzle in the crusher shown in FIG. The crushing chamber 3 is formed by the peripheral wall 6 and the base, and crushing is performed at a lower portion thereof, and classification of the crushed material is performed at an upper portion. The material to be pulverized is introduced into the pulverizing chamber 3 from the supply port 4, accelerated by the high-speed gas injected from the nozzle 5, and pulverized by colliding with the collision member 7. Ground particles (ground material)
Rises to the upper part of the pulverizing chamber together with the high-speed gas which collides and escapes upward, and is classified by the classifying rotor 2 driven by the classifier driving motor 1. In the classifying rotor 2, particles having a particle size equal to or less than a desired particle size pass through a rotor slit and are conveyed to the next step by a ventilation pipe 9 connected to the rotor. And descend again to be pulverized by high-speed gas.

Here, the nozzles 5 are provided in two upper and lower stages, respectively.
The nozzles are arranged horizontally, and the upper nozzles and the lower nozzles are alternately arranged at equal intervals when viewed from directly above. The collision member 7 has a conical shape, and is supported by a support member (not shown) so that the high-speed gas injected from each of the nozzles 5 hits a side surface of the collision member. In this embodiment as well, the above angle α is ensured.

As another preferred embodiment of the crusher of the present invention, a crusher as shown in FIG. 2 can be exemplified. FIG. 2 (a) is a schematic vertical sectional view of the lower portion of the crusher, and FIG. 2 (b) is a plan view of the lower portion of the crusher shown in FIG. FIG. 2C is a schematic perspective view of a collision member and a nozzle in the crusher shown in FIG. The pulverizer shown in FIG. 2 is different from the pulverizer shown in FIG. 1 except that four circular collision members of the same size are respectively opposed to four nozzles and are installed symmetrically with respect to the center axis of the pulverizing chamber. The same is true. At this time, the above-mentioned angle α is secured in the relationship between the individual collision members and the nozzles.

In this embodiment, two circular collision members are provided in the upper stage. One circular collision member is provided in the upper stage such that the center of the member is located on the center axis of the grinding chamber. Is also good. In this case, when a nozzle having an inner diameter of 2 mm and an injection pressure of 6 kg / cm ² is used at L / r15, the diameter of the member is preferably 10 to 20 mm.

In another embodiment of the crusher of the present invention,
A pulverizer as shown in FIG. 8 can be exemplified. FIG.
(A) shows a schematic vertical sectional view of the lower part of the crusher, and FIG.
Fig. 8 (a) is a schematic view of the lower portion of the crushing chamber shown in Fig. 8 (a) cut off horizontally by a straight line "a" and the lower portion of the crushing chamber is viewed from directly above. And a schematic perspective view of a nozzle. The crusher shown in FIG. 8 is different from the crusher shown in FIG.
It is the same as the pulverizer shown in FIG. Thus, the effect of the present invention can be obtained even when the nozzle is inclined. In this embodiment, the above-described height difference between the upper nozzle and the lower nozzle is applied as the height difference between the collision point derived from the upper nozzle and the collision point derived from the lower nozzle. In this embodiment as well, the above angle α is ensured.

In the various embodiments described above, the nozzles are arranged toward the center axis of the crushing chamber, that is, each nozzle is arranged so that the nozzle axis and the center axis of the crushing chamber intersect. Without being limited, the high-speed gas to be injected can be caused to collide with the collision member, and if the effects of the present invention are obtained, the nozzle axis and the pulverizing chamber central axis may have a twisted relationship with each other. . In this case, the angle α refers to the angle formed between the projection nozzle axis that projects the nozzle axis in the horizontal direction and the collision member in a vertical section including the intersection of the nozzle axis and the collision member surface and the central axis of the grinding chamber. I do.

The particles having a desired particle size or less obtained by crushing using the crusher as described above and classifying the coarse particles are conveyed to a cyclone as shown in FIG. 5 in order to further classify the fine particles. Is preferred. FIG. 5 is a schematic configuration diagram of a pulverizing / classifying system including a pulverizer of the present invention (here, the pulverizer of FIG. 1) and a cyclone. Specifically, particles having a size smaller than a desired particle size classified by the classification rotor 2 are conveyed to the cyclone 10 by the ventilation pipe 9. In the cyclone 10, fine powder having an extremely small particle size is removed by the fine powder suction pipe 11, so that particles (product 12) having a desired particle size can be collected.

The above pulverizer has a volume average particle size of 0.0
It is useful when coarse particles (object to be crushed) of about 1 to 1 mm are further finely crushed. The material of the material to be crushed is not particularly limited, but preferably contains a resin as a main component, and the crusher is preferably used for finely crushing a toner comprising at least a resin and a colorant. preferable.

In the pulverizer of the present invention, the number of rotations of the motor for driving the classifying rotor, the size of the slit of the classifying rotor, the high-speed gas flow rate, the suction force of the fine powder suction pipe, the amount of air supplied, and the like are appropriately set. Particles having a volume average particle size (object to be ground) can be finely pulverized to a volume average particle size of 5 to 10 μm.

As a pulverizer of the present invention, a pulverizer in which a horizontal classifying rotor is attached to the upper part of the pulverizing chamber is illustrated in FIG. 5, but is not limited thereto. It is apparent that the effects of the present invention can be obtained even if a rotor, a free vortex type classifier, or the like is employed.

Further, in the above description, a pulverizer of a type provided with a supply port of a pulverized material separately from the nozzle is described. However, the present invention is not limited to this. The present invention can also be applied to a pulverizer of a type in which the powder is charged.

[0033]

Example 1 Coarse particles of a styrene-acryl copolymer (weight average molecular weight: about 200,000) having a volume average particle diameter of 100 μm were pulverized by using a pulverization / classification system shown in FIG. The supply of the coarse particles was continuously performed so that the amount of the coarse particles inside the grinding chamber was not too small or too large. The volume average particle size of the obtained pulverized product was 8.0 μm, and the feed amount was 3.5 kg / h. The grinding conditions and classification conditions are shown below. The crusher is of the type shown in FIG.
G (Germany; manufactured by Alpine, grinding chamber: inner diameter 100 mm)
A modified version was used.

(Pulverization conditions) Impact member: conical (diameter of bottom surface (circle); 40 mm,
Height: 40mm), made of stainless steel-Nozzle: 2-stage type, 2 for both upper and lower stages (total 4)
Book) (four nozzles are installed at equal intervals in the schematic top view shown in FIG. 1 (b)), inner diameter (r) 2 mm, injection pressure 6 kg / cm ² , from nozzle tip to collision member distance (L) 30 mm (to four both), distance 20 mm (classification condition) between the nozzle axis and the nozzle axis of the lower nozzle of the upper nozzle and classification rotor rotating speed: 10000 rpm · attraction: 5 m ³ / min

Example 2 A pulverized product having a volume average particle size of 8.0 μm was obtained at a feed rate of 3.8 kg / h in the same manner as in Example 1 except that the pulverizer shown in FIG. 2 was used. The grinding conditions are shown below. The classification conditions are the same as in Example 1.

(Crushing conditions) Collision member: spherical (diameter 10 mm) (all four), made of stainless steel, distance between centers of two upper spherical collision members 1
5mm, 30m between centers of two lower spherical impact members
・ Nozzle: two-stage type, two upper and lower stages (4 in total)
(In the schematic top view shown in FIG. 2 (b), four nozzles are installed at equal intervals), inner diameter (r) 2 mm, injection pressure 6 kg / cm ² , Distance (L) 30 mm (for all four), distance 20 mm between nozzle axis of upper nozzle and nozzle axis of lower nozzle, distance 2 mm between impact point and horizontal plane including center of spherical impact member

Comparative Example 1 A pulverized product having a volume average particle size of 8.0 μm was obtained at a feed rate of 2.0 kg / h in the same manner as in Example 1 except that the pulverizer shown in FIG. 3 was used. The grinding conditions are shown below. The classification conditions are the same as in Example 1.

(Pulverization conditions) Collision member: conical (diameter of bottom surface (circle): 40 mm
Height: 40mm), made of stainless steel-Nozzle: 2-stage type, 2 for both upper and lower stages (total 4)
(In the schematic top view shown in FIG. 3B, the upper two nozzles and the lower two nozzles are installed so as to overlap), the inner diameter (r) is 2 mm, and the injection pressure is 6 kg / c.
m ² , distance from nozzle tip to collision member (L) 30 m
m (all four), the distance between the nozzle axis of the upper nozzle and the nozzle axis of the lower nozzle is 20 mm

Comparative Example 2 A pulverized product having a volume average particle size of 8.0 μm was obtained at a feed rate of 2.5 kg / h in the same manner as in Example 1 except that the pulverizer shown in FIG. 4 was used. The grinding conditions are shown below. The classification conditions are the same as in Example 1.

(Pulverization conditions) Impact member: conical (diameter of bottom surface (circle); 30 mm,
Height: 30 mm), made of stainless steel Nozzle: one-stage type (four nozzles) (four nozzles are installed at equal intervals in the schematic top view shown in FIG. 4B), inner diameter (r) 2mm, injection pressure 6kg / cm
^2. Distance (L) from nozzle tip to collision member 30mm
(All four)

[0041]

According to the present invention, the pulverizing efficiency of a fluidized bed jet pulverizer can be improved.

[Brief description of the drawings]

FIG. 1 (a) is a schematic sectional view of an example of a pulverizing chamber in a pulverizer of the present invention, and FIG. 1 (b) is a plan view of the lower part of the pulverizing chamber in FIG. FIG. 3C is a schematic perspective view when viewed from the side, and FIG. 3C is a schematic perspective view of a collision member and a nozzle in the crusher shown in FIG.

FIG. 2 (a) is a schematic sectional view of an example of a lower portion of a pulverizing chamber in the pulverizer of the present invention, and FIG. 2 (b) is a horizontal cut-out of the lower portion of the pulverizing chamber in FIG. FIG. 3C is a schematic perspective view when viewed from above, and FIG. 4C is a schematic perspective view of a collision member and a nozzle in the crusher illustrated in FIG.

3A is a schematic cross-sectional view of an example of a lower portion of a pulverizing chamber in a pulverizer used in a comparative example, and FIG. 3B is a plan view of the lower portion of the pulverizing chamber in FIG. Is shown in a schematic view when viewed from directly above, and (c) is a schematic perspective view of a collision member and a nozzle in the crusher shown in (a).

4A is a schematic cross-sectional view of an example of a lower portion of a pulverizing chamber in a pulverizer used in a comparative example, and FIG. 4B is a plan view of the lower portion of the pulverizing chamber in FIG. Is shown in a schematic view when viewed from directly above, and (c) is a schematic perspective view of a collision member and a nozzle in the crusher shown in (a).

FIG. 5 shows a pulverizer comprising the pulverizer of the present invention and a cyclone.
1 shows a schematic configuration diagram illustrating an example of a classification system.

6A is a conceptual diagram illustrating a relationship between a nozzle and a collision member for explaining an angle α when the nozzle is installed horizontally, and FIG. 6B is a diagram illustrating a case where the nozzle is installed inclined upward. FIG. 2 is a conceptual diagram illustrating a relationship between a nozzle and a collision member for explaining the angle α of FIG.

FIG. 7 is a conceptual diagram illustrating a relationship between a nozzle and a collision member for explaining an angle α when the collision member has a hemispherical shape.

8A is a schematic sectional view of an example of a lower portion of a pulverizing chamber in the pulverizer of the present invention, and FIG. 8B is a plan view of the lower portion of the pulverizing chamber in FIG. FIG. 3C is a schematic perspective view when viewed from above, and FIG. 4C is a schematic perspective view of a collision member and a nozzle in the crusher illustrated in FIG.

[Explanation of symbols]

1: motor, 2: classification rotor, 3: crushing chamber, 4: supply port, 5: nozzle, 6: crushing chamber peripheral wall, 7: collision member, 8:
Support member, 9: vent pipe, 10: cyclone, 11: suction pipe, 12: product.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshito Shimoda 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Hideyuki Yoshida Azuchi, Chuo-ku, Osaka-shi, Osaka 2-13, Machicho Osaka International Building Minolta Co., Ltd. F-term (reference) 4D067 CA02 CA07 GA16

Claims (4)

[Claims] 1. A fluidized bed jet pulverizer comprising at least a pulverizing chamber having a central axis, a collision member provided inside the pulverization chamber, and a nozzle for injecting high-speed gas toward the collision member. A fluidized bed jet pulverizer characterized in that nozzles are installed in multiple stages, and when viewed from directly above, upper and lower nozzles do not overlap. 2. The fluidized bed jet pulverizer according to claim 1, wherein the distance from the nozzle tip to the collision member is constant for all nozzles. 3. The fluidized-bed jet pulverizer according to claim 1, wherein the collision member has a cone shape. 4. The fluidized-bed jet pulverizer according to claim 1, wherein a collision member is provided for each nozzle so as to face the nozzle.