CN212770591U

CN212770591U - Cyclone for remelting ash

Info

Publication number: CN212770591U
Application number: CN202021688791.9U
Authority: CN
Inventors: 刘淑媛; 张建胜; 毕大鹏; 胡振中
Original assignee: Tsinghua University; Shanxi Research Institute for Clean Energy of Tsinghua University
Current assignee: Tsinghua University; Shanxi Research Institute for Clean Energy of Tsinghua University
Priority date: 2020-08-13
Filing date: 2020-08-13
Publication date: 2021-03-23
Anticipated expiration: 2030-08-13

Abstract

The utility model discloses a cyclone for ash remelting, which comprises an upper cyclone barrel and a lower cyclone barrel, wherein the inner wall of the upper cyclone barrel is provided with a membrane water-cooling wall, the upper cyclone barrel comprises a premixer, a secondary air inlet and a guide plate, the premixer sequentially comprises an ignition fuel channel, an ash channel and a primary air channel from inside to outside, and a cyclone structure is formed in the primary air channel; the secondary air inlet is of a volute structure; the guide plate inclines downwards from the side wall of the upper cyclone barrel to face the central shaft of the upper cyclone barrel and shrinks to form a necking; the lower cyclone barrel comprises a blowing device, a slag blocking tube panel, a hot flue gas outlet and a cold slag outlet, the upper end of the lower cyclone barrel is connected with the lower end of the upper cyclone barrel, the inner wall of the lower cyclone barrel is provided with a water-cooled wall, and the blowing device is arranged below the throat; the slag blocking tube panel extends from the inner wall of the lower cyclone cylinder to the central axis direction of the lower cyclone cylinder; the hot flue gas outlet is positioned below the slag stopping pipe bundle, and a slag catching pipe bundle is arranged in the hot flue gas outlet; the cold slag outlet is arranged at the lower end of the lower cyclone cylinder.

Description

Cyclone for remelting ash

Technical Field

The utility model belongs to the coal gasification field, in particular to a cyclone for remelting ash.

Background

The carbon-containing fly ash and fine slag generated in the production processes of gasification and the like have the carbon content of 20-60 percent and the average grain diameter of less than 50 mu m, and can not be directly used as building material raw materials without treatment. In the related technology, the carbon-containing fly ash is mostly collected by a dry dust collector, so that the fly ash is easy to raise dust and difficult to store; the fine slag is mostly generated by a wet dust removal process, the stacking occupied area is large, and the reverse osmosis of the slag can cause soil and underground water pollution.

Therefore, the existing processing technology of carbon-containing fly ash and fine slag in gasification and other production processes needs to be improved.

SUMMERY OF THE UTILITY MODEL

The present invention aims at solving at least one of the technical problems in the related art to a certain extent. Therefore, an object of the present invention is to provide a cyclone for ash remelting, which can fully recover residual heat value in ash (carbon-containing fly ash and/or fine slag), and solve the problems of difficult storage, difficult treatment, easy environmental pollution, etc. and the recovered heat can be used for producing saturated steam or superheated steam as a byproduct, thereby saving the consumption of high-quality coal and achieving significant energy saving and environmental protection effects.

In one aspect of the utility model, the utility model provides a cyclone for lime-ash remelting. According to the embodiment of the utility model, a cyclone for ash remelting includes:

the inner wall of last spin dryer is equipped with the membrane wall, and last spin dryer includes:

the premixer is arranged at the upper end of the upper cyclone barrel and sequentially comprises an ignition fuel channel, an ash channel and a primary air channel from inside to outside, and a cyclone structure is formed in the primary air channel;

the secondary air inlet is formed in the side wall of the upper cyclone barrel and is of a volute structure;

the guide plate is arranged at the lower part of the side wall of the upper cyclone barrel, inclines downwards from the side wall of the upper cyclone barrel to face the central shaft of the upper cyclone barrel and shrinks to form a necking;

the upper end of lower cyclone cylinder with the upper cyclone cylinder lower extreme links to each other, the inner wall of lower cyclone cylinder is equipped with the water-cooling wall, and lower cyclone cylinder includes:

the blowing device is arranged on the side wall of the lower cyclone barrel and is arranged below the necking;

the slag blocking pipe screen is arranged on the side wall of the lower cyclone barrel and extends from the inner wall of the lower cyclone barrel to the central axis direction of the lower cyclone barrel;

the hot flue gas outlet is arranged on the side wall of the lower cyclone barrel and is positioned below the slag stopping tube bundle, and a slag catching tube bundle is arranged in the hot flue gas outlet;

and the cold slag outlet is arranged at the lower end of the lower cyclone cylinder.

According to the cyclone for ash remelting of the embodiment of the utility model, ash (carbon-containing fly ash and/or fine slag) is supplied to an ash passage in a premixer, ignition fuel is supplied to the ignition fuel passage, primary air is supplied to a primary air passage, a cyclone structure is arranged in the primary air passage, so that ash and primary air form rotational flow at the outlet of the premixer and enter an upper cyclone barrel, carbon in the ash generates combustion reaction in the upper cyclone barrel to release heat, meanwhile, the ash is fully melted to form liquid slag, a secondary air inlet in a volute structure is arranged on the side wall of the upper cyclone barrel, secondary air supplied by the cyclone can generate tangential rotational flow, thereby carrying the liquid slag to be adhered on the inner wall surface of the upper cyclone barrel, simultaneously, under the action of air flow and gravity, the liquid slag flows downwards along the inner wall surface of the upper cyclone barrel, and a guide plate is arranged at the lower part of the side wall of the upper cyclone barrel, the retention time of liquid slag in the upper cyclone can be prolonged, the probability of remelting the slag is improved, the slag remelting capacity is enhanced, the liquid slag obtained in the upper cyclone enters the lower cyclone through a necking formed by the guide plate, under the action of the blowing device on the side wall of the lower cyclone, the blowing medium sprayed out by the blowing device breaks up the descending liquid slag and air flow to carry out mixing, reaction and cooling again, so that unburned carbon further reacts, meanwhile, the surface of the slag is rapidly cooled and solidified, the water wall arranged on the inner wall of the lower cyclone can absorb the residual heat of hot flue gas and slag to generate saturated steam, in addition, a hot flue gas outlet is arranged on the side wall of the lower cyclone, a slag trapping tube bundle is arranged in the hot flue gas outlet, the slag trapping tube bundle can effectively block the slag carried by the hot flue gas and reduce the solid content in the hot flue gas, and a slag blocking tube screen is arranged above the hot flue gas outlet, the flow field of the air flow can be changed, so that the molten slag moves towards the central cold slag outlet and falls into the cold slag outlet under the action of gravity, the quantity of the molten slag carried by hot flue gas is reduced, and the cooled solid slag is discharged from the cold slag outlet at the lower end of the lower cyclone cylinder and is subjected to deep quenching and cooling to be changed into glass slag. Therefore, the cyclone can be used for fully recovering the residual heat value in ash (carbon-containing fly ash and/or fine slag), simultaneously solving the problems of difficult storage, difficult treatment, easy environmental pollution and the like, and the recovered heat can be used for producing saturated steam or superheated steam as a byproduct, thereby saving the consumption of high-quality coal and having obvious energy-saving and environment-friendly effects.

In addition, the cyclone for ash remelting according to the above embodiment of the present invention may also have the following additional technical features:

preferably, the surface of the mode water-cooled wall is provided with a fireproof protective layer. Therefore, the surface of the mode water wall can be protected from being corroded by the liquid slag.

Preferably, a plurality of premixers are arranged at the upper end of the upper cyclone barrel, and the premixers are uniformly distributed at the upper end of the upper cyclone barrel. Therefore, the ash and slag supplied by a plurality of premixers collide with each other to form a combined rotational flow, so that the ash and slag are sufficiently mixed in the upper cyclone cylinder.

Preferably, a plurality of secondary air inlets are arranged on the side wall of the upper cyclone barrel, and the plurality of secondary air inlets are arranged at intervals along the periphery of the upper cyclone barrel. Therefore, the liquid slag generated in the upper cyclone barrel can flow downwards along the inner wall surface of the upper cyclone barrel.

Preferably, along the height direction of the upper cyclone barrel, a plurality of layers of secondary air inlets are arranged on the side wall of the upper cyclone barrel. Therefore, the liquid slag generated in the upper cyclone barrel can flow downwards along the inner wall surface of the upper cyclone barrel.

Preferably, the angle between the side wall of the guide plate and the side wall of the upper cyclone barrel is 110-130 degrees. The residence time of the liquid slag in the upper cyclone can thereby be increased.

Preferably, the blowing device includes: a ring pipe arranged along an outer wall of the lower cyclone cylinder; and one end of the blowing pipe is communicated with the annular pipe, and the other end of the blowing pipe extends into the lower cyclone barrel in a downward inclined mode. Therefore, the blowing medium can break up descending liquid slag and airflow, and the liquid slag and the airflow are mixed, reacted and cooled again, so that unburned carbon further reacts, and the slag surface is rapidly cooled and solidified.

Preferably, the angle between the discharge hole direction of the blowing pipe and the side wall of the lower cyclone barrel is 50-70 degrees. Therefore, the blowing medium can break up descending liquid slag and airflow, and the liquid slag and the airflow are mixed, reacted and cooled again, so that unburned carbon further reacts, and the slag surface is rapidly cooled and solidified.

Preferably, a plurality of blowing pipes are arranged on the side wall of the lower cyclone barrel, and the plurality of blowing pipes are arranged at intervals along the circumferential direction of the side wall of the lower cyclone barrel. Therefore, the blowing medium can break up descending liquid slag and airflow, and the liquid slag and the airflow are mixed, reacted and cooled again, so that unburned carbon further reacts, and the slag surface is rapidly cooled and solidified.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic view of a cyclone for ash remelting according to one embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present invention, and should not be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present application, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In one aspect of the utility model, the utility model provides a cyclone for lime-ash remelting. According to an embodiment of the present invention, referring to fig. 1, the cyclone cartridge includes an upper cyclone cartridge 100 and a lower cyclone cartridge 200.

According to the embodiment of the utility model, refer to fig. 1, the inner wall of upper cyclone barrel 100 is equipped with membrane water-cooling wall (not shown), and this upper cyclone barrel 100 includes premixer 11, overgrate air import 12 and guide plate 13, wherein this membrane water-cooling wall surface coating refractory castable is as the protective layer, liquid slag forms stable slag blanket on the castable surface simultaneously, can effectively protect the water-cooling wall face not receive the wearing and tearing of slag, and its low heat conductivity can make upper cyclone barrel form stable high temperature reaction zone again, be favorable to going on of lime-ash remelting reaction. Specifically, boiler water is introduced into the membrane water-cooled wall, and saturated steam generated after heating is sent to the steam superheater or directly sent to the pipe network.

According to the specific embodiment of the utility model, refer to fig. 1, premixer 11 is established in the upper end of upper cyclone 100 to premixer 11 includes ignition fuel passageway 111, ash passageway 112 and wind passageway 113 from interior to exterior in proper order, forms the whirl structure in the wind passageway 113, makes ash and wind form the whirl and get into the upper cyclone in premixer exit, and the carbon in the ash takes place combustion reaction in upper cyclone and releases the heat, and the ash fully melts simultaneously and forms liquid slag. Preferably, a plurality of premixers 11 may be provided at the upper end of the upper cyclone 100, and the plurality of premixers 11 are uniformly distributed at the upper end of the upper cyclone 100. Therefore, ash supplied by a plurality of premixers collide with each other to form combined rotational flow, so that the ash is fully mixed in the upper cyclone cylinder, the operation load is convenient to adjust, and the ignition, operation and system switching-out can be independently carried out, thereby being convenient for on-line maintenance. It should be noted that, a person skilled in the art may select a specific structure of the swirling flow structure in the primary air passage 113 according to actual needs, as long as the above functions are achieved.

According to the specific embodiment of the utility model, referring to fig. 1, overgrate air import 12 is established on the lateral wall of last whirlwind section of thick bamboo 100 to overgrate air import 12 is the spiral case structure, and the overgrate air of supplying with through this overgrate air import 12 can produce the tangential whirl, thereby carries liquid slag adhesion on the internal face of last whirlwind section of thick bamboo, and simultaneously under air current and action of gravity, liquid slag flows downwards along the inner wall face of last whirlwind section of thick bamboo. Preferably, a plurality of secondary air inlets 12 are provided on the side wall of the upper cyclone barrel 100, and the plurality of secondary air inlets 12 are arranged at intervals along the periphery of the upper cyclone barrel 100, and a plurality of layers of secondary air inlets 12 are provided on the side wall of the upper cyclone barrel 100 along the height direction of the upper cyclone barrel 100.

According to the embodiment of the present invention, referring to fig. 1, the guide plate 13 is disposed at the lower portion of the sidewall of the upper cyclone barrel 100, and the guide plate 13 is downwardly inclined from the sidewall of the upper cyclone barrel 100 toward the central axis of the upper cyclone barrel 100 and is contracted to form the throat 101. Therefore, the guide plate 13 is arranged at the lower part of the side wall of the upper cyclone cylinder 100, so that the retention time of liquid slag in the upper cyclone cylinder 100 can be prolonged, the remelting probability of ash slag is improved, the remelting capacity of ash slag is enhanced, and the liquid slag obtained in the upper cyclone cylinder 100 enters the lower cyclone cylinder 200 through the necking 101 formed by the guide plate 13. According to a specific embodiment of the present invention, the angle between the sidewall of the guide plate 13 and the sidewall of the upper cyclone barrel 100 is 110 ° to 130 °. The inventor finds that if the angle between the side wall of the guide plate 13 and the side wall of the upper cyclone barrel 100 is too small, the guide plate 13 is too gentle, which affects the fluidity of the slag, and the slag is easily accumulated on the guide plate 13, thereby increasing the pressure difference of the throat 101; if the angle between the side wall of the guide plate 13 and the side wall of the upper cyclone barrel 100 is too large, the inward contraction effect of the guide plate 13 is not obvious, the trapping and rebounding capacity of the guide plate on solid particles is reduced, the back mixing effect on air flow is reduced, and therefore the ash slag remelting efficiency is reduced.

According to the embodiment of the utility model, referring to fig. 1, the upper end of lower cyclone 200 links to each other with upper cyclone 100 lower extreme, and the inner wall of lower cyclone 200 is equipped with water-cooling wall (not shown), and this water-cooling wall can absorb the waste heat production saturated steam of hot flue gas and slag to lower cyclone 200 is including jetting device 21, slag-stopping tube panel 22, hot exhanst gas outlet 23 and cold sediment export 24.

According to the embodiment of the present invention, referring to fig. 1, the injection device 21 is disposed on the sidewall of the lower cyclone barrel 200, and the injection device 21 is disposed below the throat 101, so that under the action of the injection device 21 on the sidewall of the lower cyclone barrel 200, the injected medium sprayed from the injection device 21 breaks up the descending liquid slag and the air flow, and the liquid slag and the air flow are mixed, reacted and cooled again, so that the unburned carbon further reacts, and the slag surface is rapidly cooled and solidified. According to an embodiment of the present invention, referring to fig. 1, the blowing device 21 includes a ring pipe 211 and a blowing pipe 212, wherein the ring pipe 211 is disposed along an outer wall of the lower cyclone tube 200, one end of the blowing pipe 212 communicates with the ring pipe 211, and the other end of the blowing pipe 212 extends obliquely downward into the lower cyclone tube 200. Preferably, the angle between the discharge hole direction of the blowing pipe 212 and the side wall of the lower cyclone barrel 200 is 50 to 70 degrees. The inventor finds that the slag flows downwards under the carrying effect of gravity and air flow, the blowing angle can influence the effects of remixing, reaction and cooling, and the blowing angle within the range can ensure the uniform contact of the slag and the air flow, so that the cooling effect of the slag is improved. Meanwhile, a plurality of injection pipes 212 may be provided on the sidewall of the lower cyclone 200, and the plurality of injection pipes 212 may be arranged at intervals in the circumferential direction of the sidewall of the lower cyclone 200. Specifically, the blowing medium is supplied into the ring pipe 211, and the blowing medium is supplied into the lower cyclone barrel 200 through the blowing pipes 212. It should be noted that the injected medium can be selected from water, air and flue gas after cooling and purification in the post-stage, and a person skilled in the art can switch the injected medium according to the reaction condition and the process condition, so that the reaction is more sufficient, and the solidification capacity of the slag is increased.

According to the specific embodiment of the utility model, referring to fig. 1, the pushing off slag tube panel 22 is established on the lateral wall of lower cyclone 200, and pushing off slag tube panel 22 extends from the central axis direction of the downward cyclone 200 of the inner wall of lower cyclone 200, and it can change the flow field of air current, makes the slag move to central cold slag export 24, goes into cold slag export 24 under the effect of gravity, reduces hot flue gas and carries the slag volume. Preferably, in order to prevent slag from remaining on the shield 22, an upper end surface of the shield 22 is inclined to extend as shown in FIG. 1.

According to the utility model discloses a specific embodiment, refer to fig. 1, hot exhanst gas outlet 23 is established at the lateral wall of lower cyclone 200 and is located the below of pushing off slag tube bank 22 to be equipped with in the hot exhanst gas outlet 23 and catch slag tube bank 231, should catch slag tube bank 231 and can effectively block the slag that hot flue gas carried, reduce the solid content in the hot flue gas.

According to the specific embodiment of the utility model, referring to fig. 1, the cold slag outlet 24 is arranged at the lower end of the lower cyclone barrel 200, and the solid slag obtained after cooling is discharged through the cold slag outlet 204 at the lower end of the lower cyclone barrel 200 to be deeply quenched and cooled to become glass slag.

According to the cyclone for ash remelting of the embodiment of the utility model, ash (carbon-containing fly ash and/or fine slag) is supplied to an ash passage in a premixer, ignition fuel is supplied to the ignition fuel passage, primary air is supplied to a primary air passage, a cyclone structure is arranged in the primary air passage, so that ash and primary air form rotational flow at the outlet of the premixer and enter an upper cyclone barrel, carbon in the ash generates combustion reaction in the upper cyclone barrel to release heat, meanwhile, the ash is fully melted to form liquid slag, a secondary air inlet in a volute structure is arranged on the side wall of the upper cyclone barrel, secondary air supplied by the cyclone can generate tangential rotational flow, thereby carrying the liquid slag to be adhered on the inner wall surface of the upper cyclone barrel, simultaneously, under the action of air flow and gravity, the liquid slag flows downwards along the inner wall surface of the upper cyclone barrel, and a guide plate is arranged at the lower part of the side wall of the upper cyclone barrel, the retention time of liquid slag in the upper cyclone can be prolonged, the probability of remelting the slag is improved, the slag remelting capacity is enhanced, the liquid slag obtained in the upper cyclone enters the lower cyclone through a necking formed by the guide plate, under the action of the blowing device on the side wall of the lower cyclone, the blowing medium sprayed out by the blowing device breaks up the descending liquid slag and air flow to carry out mixing, reaction and cooling again, so that unburned carbon further reacts, meanwhile, the surface of the slag is rapidly cooled and solidified, the water wall arranged on the inner wall of the lower cyclone can absorb the residual heat of hot flue gas and slag to generate saturated steam, in addition, a hot flue gas outlet is arranged on the side wall of the lower cyclone, a slag trapping tube bundle is arranged in the hot flue gas outlet, the slag trapping tube bundle can effectively block the slag carried by the hot flue gas and reduce the solid content in the hot flue gas, and a slag blocking tube screen is arranged above the hot flue gas outlet, the flowing direction of the air flow and the slag can be changed, so that the slag moves to the central cold slag outlet and falls into the cold slag outlet under the action of gravity, and the quantity of the slag carried by hot flue gas is reduced. And the solid slag obtained after cooling is discharged from a cold slag outlet at the lower end of the lower cyclone cylinder, is subjected to deep quenching and cooling and then is changed into glass slag. Therefore, the cyclone can be used for fully recovering the residual heat value in ash (carbon-containing fly ash and/or fine slag), simultaneously solving the problems of difficult storage, difficult treatment, easy environmental pollution and the like, and the recovered heat can be used for producing saturated steam or superheated steam as a byproduct, thereby saving the consumption of high-quality coal and having obvious energy-saving and environment-friendly effects.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art without departing from the scope of the present invention.

Claims

1. A cyclone for ash remelting, comprising:

2. The cyclone for ash remelting according to claim 1 wherein the membrane wall surface is provided with a refractory protective layer.

3. The cyclone for ash remelting according to claim 1, wherein a plurality of the premixers are arranged at the upper end of the upper cyclone barrel, and the premixers are uniformly distributed at the upper end of the upper cyclone barrel.

4. The cyclone for ash remelting according to claim 1, wherein a plurality of secondary air inlets are provided on a side wall of the upper cyclone tube, and the plurality of secondary air inlets are arranged at intervals along the outer circumference of the upper cyclone tube.

5. The cyclone for ash remelting according to claim 4, wherein a plurality of layers of secondary air inlets are formed in the side wall of the upper cyclone tube in the height direction of the upper cyclone tube.

6. The cyclone for ash remelting according to claim 1, wherein the angle between the sidewall of the baffle and the sidewall of the upper cyclone is 110 ° to 130 °.

7. The cyclone for ash remelting according to claim 1, wherein the blowing device comprises:

a ring pipe arranged along an outer wall of the lower cyclone cylinder;

and one end of the blowing pipe is communicated with the annular pipe, and the other end of the blowing pipe extends into the lower cyclone barrel in a downward inclined mode.

8. The cyclone for ash remelting according to claim 7, wherein the angle between the discharge port direction of the injection tube and the side wall of the lower cyclone is 50-70 °.

9. The cyclone for ash remelting according to claim 7 or 8, wherein a plurality of the blowing pipes are arranged on the side wall of the lower cyclone, and the plurality of blowing pipes are arranged at intervals in the circumferential direction of the side wall of the lower cyclone.