Horizontal flue soot blowing system

Abstract

The utility model discloses a soot blowing system for a horizontal flue. The soot blowing system comprises a spiral generating part, a plurality of spiral maintaining parts and a plurality of soot blowing parts, wherein the spiral generating part is arranged in the horizontal flue; the spiral maintaining parts are arranged in the horizontal flue and behind the spiral generating part; each soot blowing part is provided with an air curtain machine matched with the soot blowing part. And a plurality of ash discharge ports matched with the ash blowing parts are formed in the horizontal flue. According to the soot blowing system for the horizontal flue, an active working part is not arranged in the horizontal flue, so that flue gas automatically carries fly ash to fly out, the complexity of an internal channel of the horizontal flue is reduced, the maintenance and repair cost of a product can be effectively reduced, and the development and progress of the industry are well promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of horizontal flue matching equipment, in particular to a horizontal flue soot blowing system. BACKGROUND

[0002] The boiler is a kind of energy conversion equipment, the energy input to the boiler has chemical energy in fuel, electric energy, the boiler outputs steam, high-temperature water or organic heat carrier with certain heat energy. The boiler commonly used in industry at present includes coal-fired boiler, biomass boiler etc., when coal or biomass fuel burns in the hearth, a large amount of flue gas will be generated, the fly ash particles carried by the flue gas are accumulated in the flue and the heat surface tube screen to form the ash, especially in the long horizontal flue, due to the change of the flow field in the flue, the fly ash particles are easy to accumulate at the horizontal flue, forming the ash layer. The ash of the horizontal flue is thicker, which not only affects the heat exchange efficiency of the superheater and reheater in it, but also causes the increase of ventilation resistance, which increases the power consumption of the air supply fan and the induced draft fan, and in severe cases, the horizontal flue may be deformed or even broken due to temperature difference. Therefore, the existing horizontal flue generally installs a soot blowing device to clean the ash on the heat receiving surface, but the existing soot blowing device mainly sets corresponding equipment in the horizontal flue to clean the inner wall, and the installation of the equipment not only increases the complexity of the internal passage of the horizontal flue, further affects the normal discharge of flue gas, but also increases the maintenance difficulty and maintenance cost of the active working part installed in the internal passage of the horizontal flue. CONTENT OF THE UTILITY MODEL

[0003] In view of the deficiencies of the prior art, the present application provides a horizontal flue soot blowing system, which does not set an active working part in the internal passage of the horizontal flue, so that the fly ash is carried out of the flue by the flue gas, which not only reduces the complexity of the internal passage of the horizontal flue, but also effectively reduces the maintenance and repair cost of the product, and promotes the development and progress of the industry.

[0004] A horizontal flue soot blowing system, comprising a spiral generating part arranged in the internal passage of the horizontal flue, a plurality of spiral maintaining parts arranged in the internal passage of the horizontal flue and located behind the spiral generating part, and a plurality of soot blowing parts arranged at the lower side of the horizontal flue; each soot blowing part is provided with a wind curtain machine matched therewith; the horizontal flue is provided with a plurality of ash discharge ports matched with the soot blowing parts.

[0005] As a preferred, the spiral generating part is arranged at the inlet of the horizontal flue; the distance between any one of the spiral maintaining parts and the adjacent spiral generating part or another spiral maintaining part is 5-12 meters.

[0006] Further, the spiral generating part is composed of a generating part outer ring in a tubular shape, a generating conical column arranged at the center of the generating part outer ring and coaxial with the generating part outer ring, and a plurality of generating wind guide wings arranged around the generating conical column.

[0007] Preferably, the outer diameter of the generating part outer ring is the same as the inner diameter of the horizontal flue, and the generating part outer ring is integrated with the horizontal flue;

[0008] The front section of the generating conical column is conical, and the rear section is cylindrical, and the front section of the generating conical column is arranged to face the inlet direction of the horizontal flue;

[0009] One end of the generating wind guide wing is integrated with the generating conical column, and the other end is integrated with the generating part outer ring, and the angle between the generating wind guide wing and the central axis of the generating conical column is 40-50°.

[0010] Further, the spiral maintaining part is composed of a maintaining part outer ring in a tubular shape, a maintaining conical column arranged at the center of the maintaining part outer ring and coaxial with the maintaining part outer ring, a plurality of maintaining wind guide wings arranged around the maintaining conical column, a lower supporting wind guide slope arranged below the maintaining part outer ring, and a plurality of supporting rods arranged around the outer side of the maintaining part outer ring except for the lower side; the ash discharge port is matched with the lower supporting wind guide slope.

[0011] Preferably, the outer diameter of the maintaining part outer ring is smaller than the inner diameter of the horizontal flue;

[0012] The supporting rods are arranged along the radial direction of the maintaining part outer ring, one end of the supporting rod is fixed on the maintaining part outer ring, and the other end is fixed on the horizontal flue;

[0013] The front section of the maintaining conical column is conical, and the rear section is cylindrical, and the front section of the maintaining conical column is arranged to face the inlet direction of the horizontal flue;

[0014] One end of the maintaining wind guide wing is integrated with the maintaining conical column, and the other end is integrated with the maintaining part outer ring, and the angle between the maintaining wind guide wing and the central axis of the maintaining conical column is 40-50°.

[0015] Further, the ash blowing part is composed of an upper box body and a lower box body arranged above and below and communicating with each other, an air inlet arranged at the top left side of the upper box body and communicating with the ash discharge port through a mixing air pipe, an air outlet arranged at the top right side wall of the upper box body and connected with an air outlet pipe, a partition air guide plate arranged at the top inside of the upper box body and between the air inlet and the air outlet, an air curtain port arranged at the left side wall of the upper box body, a double-sided slope block arranged at the inside of the right side wall of the upper box body, a rotating shaft arranged in the lower box body, four spatial partition pieces evenly distributed on the rotating shaft, and an ash leakage hopper arranged at the bottom end of the lower box body;

[0016] The air curtain machine is arranged on the left side wall of the upper cabinet, and the air curtain outlet of the air curtain machine is arranged correspondingly with the air curtain opening, and the air curtain blown by the air curtain machine blows horizontally to the right side wall of the upper cabinet through the air curtain opening.

[0017] The rotating shaft is connected with a stepping motor capable of driving the rotating shaft to rotate by a fixed angle.

[0018] As preferred, the left side of the separation air guide plate is a vertical surface parallel to the left side wall of the upper cabinet, and the right side of the separation air guide plate is an arc surface guiding the arc-shaped air outlet.

[0019] The horizontal distance between the air curtain opening and the separation air guide plate is greater than or equal to the distance between the separation air guide plate and the left side wall of the upper cabinet.

[0020] The upper and lower sides of the double-slope block are arc-shaped slope surfaces symmetrically arranged with the center surface as a dividing surface, and the horizontal position of the center dividing surface of the double-slope block is higher than or equal to the upper end position of the air curtain opening.

[0021] As preferred, the rotating shaft penetrates through the lower cabinet front and back;

[0022] The front and back ends of the space separation piece are respectively abutted against the front side and the back side of the lower cabinet, the top end of the space separation piece on the upper side is abutted against the lower end of the right side wall of the upper cabinet, and the top end of the space separation piece on the left side is abutted against the left side wall of the lower cabinet.

[0023] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0024] The utility model discloses a horizontal flue inside does not set up the active working part, makes the flue gas fly ash fly out smoke by oneself, not only has reduced the complexity of horizontal flue inside passage, can effectively reduce the maintenance and repair cost of product, has promoted the development and progress of industry well.

[0025] Some of the additional features of the present application can be described in the following description. Some of the additional features of the present application will be apparent from the following description and the corresponding drawings, or can be learned by practice or operation of the examples. The features disclosed by the present application can be realized and achieved by practicing or using various methods, means and combinations of the specific embodiments described below. BRIEF DESCRIPTION OF DRAWINGS

[0026] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The schematic embodiments of the present application and the description thereof are used to explain the present application, and do not constitute a limitation on the present application. In the drawings, the same reference numerals represent the same components. Among them,

[0027] Figure 1 It is a cross-sectional structure schematic view of the utility model.

[0028] Figure 2 It is the front structure schematic view of spiral generating part of the utility model.

[0029] Figure 3 It is the front structure schematic view of spiral maintaining part of the utility model.

[0030] Mark explanation:

[0031] 100, horizontal flue; 101, ash outlet;

[0032] 200, spiral generating part; 201, generating part outer ring; 202, generating conical column; 203, generating wind guide wing;

[0033] 300, spiral maintaining part; 301, maintaining part outer ring; 302, maintaining conical column; 303, maintaining wind guide wing; 304, lower support wind guide slope; 305, support rod;

[0034] 400, soot blowing part; 401, mixed air pipe; 402, air inlet; 403, air outlet; 404, separation wind guide plate; 405, air curtain opening; 406, double-sided slope block; 407, air outlet pipe; 408, rotating shaft; 409, space separation piece; 410, ash leakage hopper; 411, upper box body; 412, lower box body;

[0035] 500, air curtain machine. DETAILED DESCRIPTION

[0036] In order to make the person skilled in the art better understand the scheme of the present application, the technical scheme in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present application.

[0037] It should be noted that if the specification and claims of the present application and the above-mentioned drawings involve the terms "first", "second", etc., they are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein. In addition, if the terms "include" and "have" and any variations thereof are involved, it is intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to the clearly listed steps or units, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0038] In this application, when terms such as "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" are used, they indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are mainly for better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0039] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0040] Furthermore, in this application, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] Example 1

[0043] like Figure 1 As shown, a horizontal flue soot blowing system comprises a spiral generating section 200 disposed inside a horizontal flue 100, a plurality of spiral maintaining sections 300 disposed inside the horizontal flue 100 and located after the spiral generating section 200, and a plurality of soot blowing sections 400 disposed on the lower side of the horizontal flue 100; each of the soot blowing sections 400 is provided with a cooperating air curtain fan 500; the horizontal flue 100 is provided with a plurality of ash discharge ports 101 cooperating with the soot blowing sections 400.

[0044] The spiral generating part 200 is located at the inlet of the horizontal flue 100; the distance between any one of the spiral maintaining parts 300 and the adjacent spiral generating part 200 or another spiral maintaining part 300 is 5-12 meters.

[0045] The distance is adjusted according to the flow rate of the flue gas flowing in the horizontal flue, and the higher the flow rate of the flue gas, the longer the distance, and vice versa.

[0046] The spiral generating part 200 is composed of a generating part outer ring 201 in a tubular shape, a generating conical column 202 arranged at the center of the generating part outer ring 201 and coaxial with the generating part outer ring 201, and a plurality of generating wind guide wings 203 arranged around the generating conical column 202.

[0047] The outer diameter of the generating part outer ring 201 is the same as the inner diameter of the horizontal flue 100, and the generating part outer ring 201 is integrated with the horizontal flue 100;

[0048] The front section of the generating conical column 202 is conical, and the rear section is cylindrical, and the front section of the generating conical column 202 is arranged facing the inlet direction of the horizontal flue 100;

[0049] One end of the generating wind guide wing 203 is integrated with the generating conical column 202, and the other end is integrated with the generating part outer ring 201, and the included angle between the generating wind guide wing 203 and the central axis of the generating conical column 202 is 45°.

[0050] After the flue gas enters the horizontal flue, it first passes through the spiral generating part, and under the guidance of the generating wind guide wing, the flue gas will move in the direction of 45° cutting angle to the rear, thereby making the flue gas in the entire horizontal flue move in a spiral manner to the rear, and due to the action of centrifugal force, the ash in the flue gas will be thrown to the side wall of the horizontal flue, thereby effectively making the ash in the flue gas gather near the side wall of the horizontal flue and spiral forward with the flue gas.

[0051] The spiral maintaining part 300 is composed of a maintaining part outer ring 301 in a tubular shape, a maintaining conical column 302 arranged at the center of the maintaining part outer ring 301 and coaxial with the maintaining part outer ring 301, a plurality of maintaining wind guide wings 303 arranged around the maintaining conical column 302, a lower supporting wind slope surface 304 arranged below the maintaining part outer ring 301, and a plurality of supporting rods 305 arranged around the remaining parts of the maintaining part outer ring 301 except the lower part; the ash discharge port 101 cooperates with the lower supporting wind slope surface 304.

[0052] The outer diameter of the maintaining part outer ring 301 is smaller than the inner diameter of the horizontal flue 100;

[0053] The supporting rod 305 is arranged in the radial direction of the maintaining part outer ring 301, one end of the supporting rod 305 is fixed on the maintaining part outer ring 301, and the other end is fixed on the horizontal flue 100;

[0054] The front section of the maintaining conical column 302 is conical, the rear section is cylindrical, and the front section of the maintaining conical column 302 is arranged to face the inlet direction of the horizontal flue 100;

[0055] One end of the maintaining wind guide wing 303 is integrated with the maintaining conical column 302, and the other end is integrated with the maintaining outer ring 301, and the angle between the maintaining wind guide wing 303 and the central axis of the maintaining conical column 302 is 45°.

[0056] When the spiral moving smoke passes through the spiral maintaining part, part of the smoke carrying dust located in the outer layer will be discharged from the horizontal flue through the dust discharge port under the guidance of the lower supporting wind guide slope surface, and the remaining smoke located in the outer layer will continue to move spirally backward through the aperture between the maintaining outer ring and the horizontal flue, and the smoke located in the central part will continue to move in the direction of 45° cutting angle to the rear under the guidance of the maintaining wind guide wing, thereby better maintaining the spiral moving mode of the smoke, so that the dust will always be gathered at the outer ring layer under the action of the centrifugal force.

[0057] The dust blowing part 400 is composed of an upper box body 411 and a lower box body 412 arranged above and below and in communication with each other, an air inlet 402 arranged at the top left side of the upper box body 411 and connected to the dust discharge port 101 through the mixed air pipe 401, an air outlet 403 arranged at the top of the right side wall of the upper box body 411 and connected with the air outlet pipe 407, a partition air guide plate 404 arranged inside the top of the upper box body 411 and located between the air inlet 402 and the air outlet 403, an air curtain port 405 arranged in the left side wall of the upper box body 411, a double-sided slope block 406 arranged inside the right side wall of the upper box body 411, a rotating shaft 408 arranged in the lower box body 412, four space partition plates 409 evenly distributed on the rotating shaft 408, and a dust hopper 410 arranged at the bottom end of the lower box body 412;

[0058] When arranged, the air outlet pipe can be connected to the dust collector or directly introduced into the last section of the horizontal flue according to actual needs.

[0059] The air curtain machine 500 is arranged at the left side wall of the upper box body 411, and the air curtain outlet of the air curtain machine 500 is arranged correspondingly with the air curtain port 405, and the air curtain blown by the air curtain machine 500 is horizontally blown to the right side wall of the upper box body 411 after passing through the air curtain port 405;

[0060] The rotating shaft 408 is connected with a stepping motor capable of driving the rotating shaft 408 to rotate at a fixed angle.

[0061] The left side of the partition air guide plate 404 is a vertical surface parallel to the left side wall of the upper box body 411, and the right side of the partition air guide plate 404 is an arc-shaped surface guiding the air outlet 403;

[0062] The horizontal distance between the air curtain opening 405 and the partitioned air deflector 404 is greater than or equal to the distance between the partitioned air deflector 404 and the left side wall of the upper cabinet 411.

[0063] The upper and lower sides of the double-sided slope block 406 are arc-shaped slope surfaces symmetrically arranged with the center surface as the dividing surface, and the horizontal position of the center dividing surface of the double-sided slope block 406 is higher than or equal to the upper end position of the air curtain opening 405.

[0064] The rotating shaft 408 penetrates the lower cabinet 412 front and back;

[0065] The front and back ends of the space partitioning piece 409 are respectively abutted against the front side and the back side of the lower cabinet 412, the top end of the space partitioning piece 409 located on the upper side is abutted against the lower end of the right side wall of the upper cabinet 411, and the top end of the space partitioning piece 409 located on the left side is abutted against the left side wall of the lower cabinet 412.

[0066] After the smoke carrying a large amount of ash enters the upper cabinet, the smoke first moves vertically downward in the channel formed by the left side wall of the upper cabinet and the left side wall of the partitioned air deflector, and due to the presence of the air curtain in the middle of the upper cabinet, the entering smoke will move rightward under the driving of the air curtain, and the ash will enter the air curtain under the action of inertia. When the smoke and the air curtain move to the double-sided slope block, the smoke will move upward under the guidance of the upper arc-shaped slope surface and finally enter the air outlet pipe through the air outlet, and the air curtain will move downward under the guidance of the lower arc-shaped slope surface and finally make the ash fall on the space partitioning piece; the space partitioning piece will rotate with the rotation of the rotating shaft and finally make the ash be collected by the ash leakage hole and discharged.

[0067] Embodiment 2

[0068] The difference between this embodiment and embodiment 1 is that the included angle between the generating air deflector 203 and the central axis of the generating conical column 202 is 40°.

[0069] The included angle between the maintaining air deflector 303 and the central axis of the maintaining conical column 302 is maintained at 40°.

[0070] Embodiment 3

[0071] The difference between this embodiment and embodiment 1 is only that the included angle between the generating air deflector 203 and the central axis of the generating conical column 202 is 50°.

[0072] The included angle between the maintaining air deflector 303 and the central axis of the maintaining conical column 302 is maintained at 50°.

[0073] It should be noted that all the features disclosed in the specification, or the steps in all the disclosed methods or processes, can be combined in any manner, except for the features and / or steps that are mutually exclusive.

[0074] In addition, the above specific embodiments are exemplary, and those skilled in the art can think of various solutions under the inspiration of the disclosure of the utility model, and these solutions also belong to the disclosed range of the utility model and fall within the protection scope of the utility model. Those skilled in the art should understand that the utility model specification and its drawings are all illustrative and do not constitute a limitation on the claims. The protection scope of the utility model is defined by the claims and their equivalents.

Claims

1. A horizontal flue sootblowing system characterized by, The utility model relates to a horizontal flue dust blowing device, which comprises a spiral generating part (200) arranged inside a horizontal flue (100), a plurality of spiral maintaining parts (300) arranged inside the horizontal flue (100) and behind the spiral generating part (200), and a plurality of blowing parts (400) arranged at the lower side of the horizontal flue (100); each blowing part (400) is provided with a wind curtain machine (500) matched therewith; the horizontal flue (100) is provided with a plurality of ash discharge ports (101) matched with the blowing parts (400).

2. A horizontal flue sootblowing system according to claim 1, characterized in that The spiral generating part (200) is arranged at the inlet of the horizontal flue (100); the spacing between any one of the spiral maintaining parts (300) and the adjacent spiral generating part (200) or another spiral maintaining part (300) is 5-12 m.

3. A horizontal flue sootblowing system according to claim 2, wherein The spiral generating part (200) comprises a tubular generating part outer ring (201), a generating conical column (202) arranged at the central position of the generating part outer ring (201) and coaxial with the generating part outer ring (201), and a plurality of generating wind guide wings (203) arranged around the generating conical column (202).

4. A horizontal flue sootblowing system according to claim 3, wherein The outer diameter of the generating part outer ring (201) is the same as the inner diameter of the horizontal flue (100), and the generating part outer ring (201) is integrated with the horizontal flue (100); The front section of the generating conical column (202) is conical, and the rear section is cylindrical; the front section of the generating conical column (202) faces the inlet direction of the horizontal flue (100); One end of the generating wind guide wing (203) is integrated with the generating conical column (202), and the other end is integrated with the generating part outer ring (201); the included angle between the generating wind guide wing (203) and the central axis of the generating conical column (202) is 40-50°.

5. A horizontal flue sootblowing system according to claim 2 wherein, The spiral maintaining part (300) comprises a tubular maintaining part outer ring (301), a maintaining conical column (302) arranged at the central position of the maintaining part outer ring (301) and coaxial with the maintaining part outer ring (301), a plurality of maintaining wind guide wings (303) arranged around the maintaining conical column (302), a lower supporting wind guide slope (304) arranged below the maintaining part outer ring (301), and a plurality of supporting rods (305) arranged around the remaining parts of the maintaining part outer ring (301) except the lower part; the ash discharge port (101) is matched with the lower supporting wind guide slope (304).

6. A horizontal flue sootblowing system according to claim 5, wherein The outer diameter of the maintaining part outer ring (301) is smaller than the inner diameter of the horizontal flue (100); The supporting rod (305) is arranged along the radial direction of the maintaining part outer ring (301); one end of the supporting rod (305) is fixed to the maintaining part outer ring (301), and the other end is fixed to the horizontal flue (100); The front section of the maintaining conical column (302) is conical, and the rear section is cylindrical; the front section of the maintaining conical column (302) faces the inlet direction of the horizontal flue (100). One end of the maintaining guide vane (303) is integrated with the maintaining conical column (302), and the other end is integrated with the maintaining outer ring (301), and the included angle between the maintaining guide vane (303) and the central axis of the maintaining conical column (302) is 40-50°.

7. A horizontal flue sootblowing system according to claim 6, wherein The blowing ash part (400) is composed of an upper box (411) and a lower box (412) arranged above and below and communicating with each other, an air inlet (402) arranged at the top left side of the upper box (411) and communicating with the ash outlet (101) through a mixed air pipe (401), an air outlet (403) arranged at the top of the right side wall of the upper box (411) and connected with an air outlet pipe (407), a partition air guide plate (404) arranged inside the top of the upper box (411) and located between the air inlet (402) and the air outlet (403), an air curtain outlet (405) arranged on the left side wall of the upper box (411), a double-sided slope block (406) arranged inside the right side wall of the upper box (411), a rotating shaft (408) arranged in the lower box (412), four space partition plates (409) evenly distributed on the rotating shaft (408), and an ash leakage chute (410) arranged at the bottom end of the lower box (412); The air curtain machine (500) is arranged on the left side wall of the upper box (411), and the air curtain outlet of the air curtain machine (500) is arranged correspondingly with the air curtain outlet (405), and the air curtain blown out by the air curtain machine (500) blows horizontally to the right side wall of the upper box (411) through the air curtain outlet (405); The rotating shaft (408) is connected with a stepping motor capable of driving the rotating shaft (408) to rotate at a fixed angle.

8. A horizontal flue sootblowing system according to claim 7, characterised in that The left side of the partition air guide plate (404) is a vertical surface parallel to the left side wall of the upper box (411), and the right side of the partition air guide plate (404) is an arc-shaped surface guiding the air outlet (403); The horizontal distance between the air curtain outlet (405) and the partition air guide plate (404) is greater than or equal to the distance between the partition air guide plate (404) and the left side wall of the upper box (411); The upper and lower sides of the double-sided slope block (406) are arc-shaped slope surfaces symmetrically arranged with the central dividing surface, and the horizontal position of the central dividing surface of the double-sided slope block (406) is higher than or equal to the upper end position of the air curtain outlet (405).

9. A horizontal flue sootblowing system according to claim 8, wherein The rotating shaft (408) penetrates the lower box (412) front and back; The front and back ends of the space partition plate (409) abut against the front and back side walls of the lower box (412) respectively, the top end of the upper space partition plate (409) abuts against the lower end of the right side wall of the upper box (411), and the top end of the left space partition plate (409) abuts against the left side wall of the lower box (412).

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