Bypass ventilation system with series-parallel multi-stage cyclones
By using a bypass ventilation system with multi-stage cyclones connected in series and parallel, and employing high-efficiency cyclones for gas-solid separation, the problem of excessively low exhaust gas temperature affecting subsequent equipment is solved, achieving efficient removal of harmful substances and treatment of exhaust gas at a suitable temperature.
Patent Information
- Application Number
- CN202520558170.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-27
- Publication Date
- 2026-03-20
- Estimated Expiration
- 2035-03-27
AI Technical Summary
The existing bypass ventilation system results in excessively low exhaust gas temperature, which affects the working performance of subsequent equipment, especially the working quality of equipment such as SCR.
A bypass ventilation system with multi-stage cyclone separators connected in series and parallel is adopted. High-efficiency cyclone separators are used instead of bag filters. Gas-solid separation is achieved through multi-stage cyclone separators connected in series, which increases the temperature of the exhaust gas and improves the gas-solid separation efficiency.
It achieves efficient removal of harmful substances, with the exhaust gas temperature reaching approximately 330℃, meeting the temperature requirements of subsequent treatment equipment and avoiding the impact of low-temperature flue gas on the equipment.
Smart Images
Figure CN224010072U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of bypass ventilation in cement clinker production lines, specifically to a bypass ventilation system with multi-stage cyclone separators connected in series and parallel. Background Technology
[0002] With the gradual advancement of energy conservation and carbon reduction, more and more cement clinker production lines are using alternative fuels and co-processing various solid and hazardous wastes. According to theoretical calculations, the interfering elements (K, Na, S, Cl) brought into the cement kiln system by alternative fuels or solid and hazardous wastes account for about 50-60% of the total interfering elements. These elements will undergo a cycle enrichment phenomenon in the cement clinker calcination system, which can seriously affect the quality of cement clinker products, and even interfere with the entire thermal regime and the normal operation of the cement kiln system.
[0003] Based on the volatilization and condensation characteristics of various compounds (potassium chloride, sodium chloride, etc.) produced by interfering elements, the current method of removing interfering elements from the cement clinker calcination system is to use bypass ventilation.
[0004] Currently, bypass venting mainly employs an "air cooler / boiler + bag filter" method. This cools the flue gas, causing interfering elements to condense into solid particles, which are then effectively separated using a bag filter. Due to the operating temperature limitations of the bag filter, the temperature of the flue gas entering the bag filter needs to be reduced to around 200℃. This is typically achieved through a two-stage cooling process to condense the interfering elements.
[0005] First, a certain amount of high-temperature air is drawn from the kiln tail flue through the air intake device. The high-temperature gas is then cooled by an air cooler to about 400°C. At this temperature, the gas temperature is far below the melting point of harmful substances such as potassium chloride, causing them to condense. These condensed solid particles enter the cyclone separator along with the flue gas for gas-solid separation, resulting in coarse particles with fewer interfering elements. The flue gas after gas-solid separation then enters a heat exchanger or waste heat power generation boiler for secondary cooling, at which point the flue gas temperature drops to 180°C. Fine particles are then removed by a bag filter. The filtered gas enters the waste gas treatment system, and the collected ash is stored and then disposed of in a harmless manner once a certain amount is reached.
[0006] Using the above treatment method, the final outlet temperature of the exhaust gas is relatively low, only around 180°C. Since subsequent treatment equipment, such as SCR (Selective Catalytic Reduction), typically requires an operating temperature of no less than 300°C, the excessively low exhaust gas temperature will affect the performance of these downstream devices. Therefore, the current bypass draft system negatively impacts the operational quality of subsequent exhaust gas treatment equipment (such as SCR). Utility Model Content
[0007] The purpose of this invention is to provide a bypass ventilation system with multi-stage cyclone separators connected in series and parallel. This bypass ventilation system uses high-efficiency cyclone separators instead of bag filters, eliminating the need for secondary cooling of flue gas, increasing the exhaust gas outlet temperature, and ensuring the working quality of subsequent exhaust gas treatment equipment.
[0008] To achieve the above objectives, this utility model provides a bypass ventilation system with multiple cyclones connected in series and parallel. The bypass ventilation system with multiple cyclones connected in series and parallel includes an air intake, a quenching device, a primary cyclone, a high-efficiency cyclone, and an exhaust fan connected in sequence.
[0009] The insertion depth L of the inner cylinder of the high-efficiency cyclone separator is set to 1200-5200mm, and the air velocity at the air inlet of the high-efficiency cyclone separator is set to 20-30m / s.
[0010] Preferably, the outlet temperature of the quenching equipment is set to be below 450°C.
[0011] Preferably, multiple high-efficiency cyclones are provided, and multiple high-efficiency cyclones are connected in parallel to form a group of two-stage cyclones.
[0012] Preferably, a gate valve is provided at the inlet of the high-efficiency cyclone separator to control the air intake speed of the high-efficiency cyclone separator.
[0013] Preferably, the number of high-efficiency cyclones in a set of two-stage cyclones is set to an even number.
[0014] Preferably, multiple sets of secondary cyclones are provided, and the multiple sets of secondary cyclones are connected in series.
[0015] Preferably, the high-efficiency cyclone separator further includes an upper shell and a cone connected to the upper shell, with one end of the inner cylinder inserted into the upper shell, and a tail vortex isolator disposed at the connection between the upper shell and the cone.
[0016] The inlet is located on the upper shell, the bottom of the cone has an outlet for ash, and the upper end of the inner cylinder has an outlet for air.
[0017] According to the above technical solution, the flue gas of this invention, after being extracted by the air intake, enters the quenching equipment. After being cooled by the quenching equipment, the temperature of the flue gas reaches 300-450℃, which is far lower than the melting point of harmful substances such as potassium chloride. Therefore, the harmful substances quickly condense and adhere to the surface of solid particles. These solid particles are mixed in the flue gas and enter the primary cyclone separator for preliminary gas-solid separation. Due to the low separation efficiency of the primary cyclone separator, coarse solid dust particles are captured in the primary cyclone separator. Most of these captured solid particles are raw materials produced by the system. Due to their large size and small specific surface area, there are fewer harmful substances adhering to them. These coarse solid particles can be recycled back to the cement kiln system as raw materials. The small amount of harmful substances recovered with the coarse solid particles has little impact on the cement kiln system.
[0018] After being separated by the primary cyclone separator, the flue gas enters the high-efficiency cyclone separator for efficient gas-solid separation. This high-efficiency cyclone separator is mainly responsible for capturing small particles in the flue gas.
[0019] The inlet velocity of this high-efficiency cyclone separator is set to 20-30 m / s, which is higher than that of the primary cyclone separator. This allows the flue gas to generate greater centrifugal force as it rotates within the high-efficiency cyclone separator. Under the action of this large centrifugal force, the dust in the flue gas adheres closer to the wall surface, effectively increasing the friction between the dust and the wall surface. This facilitates the capture of dust by the cyclone separator during rotation, thereby achieving a reliable gas-solid separation effect. Therefore, setting a larger inlet velocity can effectively improve the gas-solid separation efficiency of this high-efficiency cyclone separator 4.
[0020] The inner cylinder insertion depth L11 of the high-efficiency cyclone separator is set to 1200-5200mm, which is greater than that of the primary cyclone separator. By setting a larger inner cylinder insertion depth, the residence time of gas within the high-efficiency cyclone separator can be effectively increased. Therefore, by increasing the air inlet velocity while simultaneously increasing the inner cylinder depth, the high-efficiency cyclone separator allows for more effective separation of solid particles in the flue gas, thereby achieving a better gas-solid separation effect.
[0021] The dust collection efficiency of the high-efficiency cyclone separator is about 98%. Compared with bag dust collectors, the high-efficiency cyclone separator will have a certain amount of ash and chlorine escape. However, the 2% ash and chlorine escape has a small impact on the cement kiln system and will not affect the normal production of the cement kiln system.
[0022] The problem of ash and chlorine escape in high-efficiency cyclones can be mitigated by increasing the intake air volume. By increasing the intake air volume, the bypass ventilation system of multi-stage cyclones connected in series and parallel can extract more harmful substances per unit time, achieving sufficient separation of harmful substances within the system and thus compensating for the partial ash and chlorine escape from the high-efficiency cyclones. Preferably, increasing the ventilation ratio by approximately 0.5% can effectively compensate for the ash and chlorine escape problem that occurs during the dechlorination process of high-efficiency cyclones.
[0023] In conclusion, using this high-efficiency cyclone separator can replace bag filters to achieve efficient capture of fine particles, thereby achieving almost the same removal rate of harmful substances.
[0024] This multi-stage cyclone separator bypass ventilation system uses high-efficiency cyclones to separate small particulate solids in flue gas. Because the high-efficiency cyclones have a wide operating temperature range, high-temperature flue gas does not need to be cooled twice and can be directly introduced into the high-efficiency cyclones.
[0025] Therefore, the high-temperature flue gas after being treated by the quenching equipment can undergo gas-solid separation with almost no heat loss. The gas temperature after being treated by the high-efficiency cyclone can reach about 330℃, which can meet the working temperature requirements of subsequent processing equipment.
[0026] Therefore, using a bypass ventilation system with multi-stage cyclone separators connected in series and parallel can effectively remove harmful substances while avoiding the impact of low flue gas temperature on the working performance of subsequent equipment.
[0027] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description
[0028] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the following detailed description to explain the present invention, but do not constitute a limitation thereof. In the drawings:
[0029] Figure 1 This is a schematic diagram of a bypass ventilation system with multiple cyclones connected in series and parallel.
[0030] Figure 2 It is a two-stage cyclone configuration;
[0031] Figure 3 It is a two-stage cyclone configuration;
[0032] Figure 4 It is a two-stage cyclone configuration;
[0033] Figure 5 This is a schematic diagram of a primary cyclone separator.
[0034] Figure 6 This is a structural schematic diagram of a high-efficiency cyclone separator;
[0035] Figure 7 This is a layout diagram of a multi-stage cyclone bypass ventilation system connected in series and parallel within a factory.
[0036] Explanation of reference numerals in the attached figures
[0037] 1. Air intake 2. Sudden cooling equipment
[0038] 3. Primary Cyclone Duct 4. High-Efficiency Cyclone Duct
[0039] 5 exhaust fans 61 inner cylinder
[0040] 7 Gate valve 62 upper housing
[0041] 63 cone cylinder, 64 inlet
[0042] 65 Ash outlet 66 Air outlet
[0043] 10 Cement Kiln System 8 Air Inlet Pipes
[0044] 67 Wake Vortex Isolator Detailed Implementation
[0045] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.
[0046] In this utility model, unless otherwise stated, directional words such as "in sequence, parallel, series, below, coaxial, bottom, and top" contained in the terminology only represent the orientation of the term in its conventional use or are common terms understood by those skilled in the art, and should not be regarded as limitations on the terminology.
[0047] This utility model provides a bypass ventilation system with multiple cyclones connected in series and parallel. The bypass ventilation system with multiple cyclones connected in series and parallel includes an air intake 1, a quenching device 2, a primary cyclone 3, a high-efficiency cyclone 4, and an exhaust fan 5 connected in sequence.
[0048] The insertion depth L11 of the inner cylinder 61 of the high-efficiency cyclone 4 is set to 1200-5200mm, and the air velocity at the air inlet of the high-efficiency cyclone 4 is set to 20-30m / s.
[0049] Through the implementation of the above technical solution, the flue gas, after being extracted by the air intake, enters the quenching device 2. After being cooled by the quenching device 2, the temperature of the flue gas reaches 300-450℃, which is far lower than the melting point of harmful substances such as potassium chloride. Therefore, the harmful substances quickly condense and adhere to the surface of solid particles. These solid particles are mixed in the flue gas and enter the primary cyclone separator 3 for preliminary gas-solid separation. Since the separation efficiency of the primary cyclone separator 3 is not high, coarse solid dust particles are captured in the primary cyclone separator 3. Most of these captured solid particles are raw materials produced by the system. Due to their large size and small specific surface area, there are fewer harmful substances adhering to them. These coarse solid particles can be recycled back to the cement kiln system 10 as raw materials. The small amount of harmful substances recovered with the coarse solid particles has little impact on the cement kiln system 10.
[0050] After being separated by the primary cyclone separator 3, the flue gas enters the high-efficiency cyclone separator 4 for efficient gas-solid separation. The high-efficiency cyclone separator 4 is mainly responsible for capturing small particles in the flue gas.
[0051] The inlet velocity of the high-efficiency cyclone separator 4 is set to 20-30 m / s, which is higher than that of the primary cyclone separator 3. This allows the flue gas to generate greater centrifugal force as it rotates within the high-efficiency cyclone separator 4. Under this greater centrifugal force, the dust in the flue gas adheres more closely to the wall surface, effectively increasing the friction between the dust and the wall. This facilitates the capture of dust by the cyclone separator during rotation, thereby achieving reliable gas-solid separation. Therefore, setting a higher inlet velocity can effectively improve the gas-solid separation efficiency of the high-efficiency cyclone separator 4.
[0052] The insertion depth L11 of the inner cylinder 61 of the high-efficiency cyclone separator 4 is set to 1200-5200mm, which is greater than that of the inner cylinder 61 of the primary cyclone separator 3. By setting a larger insertion depth of the inner cylinder 61, the residence time of gas within the high-efficiency cyclone separator 4 can be effectively increased. Therefore, by increasing the air intake velocity while simultaneously increasing the depth of the inner cylinder 61, the high-efficiency cyclone separator 4 allows for more effective separation of solid particles in the flue gas within the high-efficiency cyclone separator 4, thereby achieving a better gas-solid separation effect.
[0053] The dust collection efficiency of the high-efficiency cyclone separator 4 is about 98%. Compared with bag dust collectors, the high-efficiency cyclone separator 4 will have a certain amount of ash and chlorine escape. However, the 2% ash and chlorine escape has a small impact on the cement kiln system 10 and does not affect the normal production of the cement kiln system 10.
[0054] The problem of ash and chlorine escape in the high-efficiency cyclone separator 4 can be mitigated by increasing the intake air volume. By increasing the intake air volume, the bypass venting system of the multi-stage cyclone separators connected in series and parallel can extract more harmful substances per unit time, achieving sufficient separation of harmful substances within the system, thereby compensating for the partial ash and chlorine escape from the high-efficiency cyclone separator 4. Preferably, increasing the venting ratio by approximately 0.5% can effectively compensate for the ash and chlorine escape problem that occurs during the chlorination process of the high-efficiency cyclone separator 4.
[0055] In summary, using this high-efficiency cyclone separator 4 can replace bag filters to achieve efficient capture of fine particles, thereby achieving almost the same removal rate of harmful substances.
[0056] Example 1
[0057] The multi-stage cyclone separator bypass venting system has a capacity of 7700 Nm. 3 The flue gas from the cement kiln system 10 is extracted at a flow rate of / h. After treatment, the exhaust gas is input into the existing PH boiler. The dust content and chlorine content at the inlet of the existing PH boiler are measured before and after the exhaust gas is introduced. The results are shown in Table 1.
[0058]
[0059]
[0060] As can be seen from the data in Table 1, this multi-stage cyclone separator series-parallel bypass venting system achieves a flow rate of 7700 Nm. 3 The system extracts flue gas from the cement kiln system 10 at a flow rate of / h, with a dust collection efficiency of approximately 98%. The treated exhaust gas is discharged with a dust volume of approximately 0.02t / h, of which the chlorine content is approximately 18%.
[0061] The temperature and power generation at the inlet of the PH boiler were measured before and after the exhaust gas was introduced, and the results are shown in Table 2.
[0062]
[0063] As can be seen from the data in Table 2, this multi-stage cyclone separator series-parallel bypass venting system achieves a capacity of 7700 Nm. 3 The system extracts flue gas from the cement kiln system 10 at a flow rate of / h. The treated exhaust gas has a temperature higher than 330℃. This exhaust gas can increase the power generation of the original PH boiler by about 1.84kWh / t.cl.
[0064] The bypass ventilation system of the multi-stage cyclone separators connected in series and parallel uses a high-efficiency cyclone separator 4 to separate small particulate solids in the flue gas. Since the high-efficiency cyclone separator 4 has a wide operating temperature range, the high-temperature flue gas does not need to be cooled in the second stage and can directly enter the high-efficiency cyclone separator 4.
[0065] Therefore, the high-temperature flue gas after being treated by the quenching device 2 can undergo gas-solid separation with almost no heat loss. The gas temperature after being treated by the high-efficiency cyclone 4 can reach about 330℃, which can meet the working temperature requirements of subsequent processing equipment.
[0066] Therefore, using a bypass ventilation system with multi-stage cyclone separators connected in series and parallel can effectively remove harmful substances while avoiding the impact of low flue gas temperature on the working performance of subsequent equipment.
[0067] After the flue gas passes through the high-efficiency cyclone separator 4 for dust removal, the exhaust gas enters the exhaust gas treatment system. The collected ash is stored and then disposed of in a harmless manner.
[0068] In this embodiment, preferably, the outlet temperature of the quenching device 2 is set to be below 450°C.
[0069] A certain amount of high-temperature air is drawn from the kiln tail flue gas chamber through the air intake device. The extracted high-temperature flue gas immediately enters the quenching device 2 and is rapidly cooled. The temperature of the cooled flue gas is much lower than the melting point of harmful substances such as potassium chloride. Ultimately, potassium chloride and other substances are condensed and adhere to the surface of solid powder in the flue gas. Preferably, the outlet temperature of the quenching device 2 is set to 300-450℃.
[0070] In this embodiment, preferably, multiple high-efficiency cyclone separators 4 are provided, and multiple high-efficiency cyclone separators 4 are connected in parallel to form a group of two-stage cyclone separators.
[0071] After being processed by the primary cyclone separator 3, the solid particles in the flue gas have smaller diameters, necessitating the use of even smaller diameter cyclones for separation. Generally, the smaller the diameter of the cyclone separator, the smaller the particles it can collect. However, a small diameter cyclone separator results in a limited air volume processed per unit time. Therefore, multiple high-efficiency cyclones 4 need to be connected in parallel to increase the flue gas processing capacity of the multi-stage cyclone separator series-parallel bypass ventilation system per unit time.
[0072] In this embodiment, preferably, a gate valve 7 is provided at the inlet of the high-efficiency cyclone 4, and the gate valve 7 controls the inlet wind speed of the high-efficiency cyclone 4.
[0073] The gate valve 7 installed at the inlet of the high-efficiency cyclone 4 can not only adjust the inlet air velocity of the cyclone, but also open or close the high-efficiency cyclone 4 in the bypass ventilation system of multi-stage cyclone ducts connected in series and parallel by opening or closing some of the gate valves 7.
[0074] In this embodiment, preferably, the number of high-efficiency cyclones 4 in a set of two-stage cyclones is set to an even number.
[0075] To ensure uniform air intake in a set of two-stage cyclones, an even number of high-efficiency cyclones 4 are usually connected in parallel in a set of two-stage cyclones.
[0076] Preferably, a set of two-stage cyclones typically includes two or four high-efficiency cyclones 4.
[0077] like Figure 2-4 As shown, taking a group of four high-efficiency cyclones 4 as an example, the four high-efficiency cyclones 4 can be distributed in three ways. Considering the relative positions of the four high-efficiency cyclones 4 and the distribution of the air inlet pipes 8 of each high-efficiency cyclone 4, the preferred method is... Figure 3 and Figure 4 The distribution method, by closely arranging the four high-efficiency cyclones, can effectively improve the space occupation of the equipment.
[0078] This multi-stage cyclone separator series-parallel bypass venting system uses a high-efficiency cyclone separator 4 to achieve dechlorination of the flue gas. This not only increases the outlet temperature of the exhaust gas, but also features a simple overall structure. Figure 7 As shown, the entire bypass ventilation system can be installed within the existing preheater system tower, which can effectively reduce investment costs such as civil engineering and lower fixed asset investment.
[0079] In this embodiment, preferably, multiple secondary cyclones are provided, and the multiple secondary cyclones are connected in series.
[0080] High-efficiency cyclone separators 4 may experience some ash and chlorine escape. In addition to increasing the air intake to separate more harmful substances, multiple secondary cyclone separators connected in series can be used to effectively collect solid particles in the flue gas.
[0081] Connecting multiple secondary cyclones in series can effectively improve the gas-solid separation effect of the bypass venting system with series and parallel secondary cyclones, and reliably improve the problem of ash and chlorine escape.
[0082] In this embodiment, preferably, the high-efficiency cyclone 4 further includes an upper shell 62 and a cone 63 located below and connected to the upper shell 62. One end of the inner cylinder 61 is inserted into the upper shell 62, and the tail vortex isolator 67 is disposed in the cone 63. The tail vortex isolator 67 is coaxially disposed with the cone 63.
[0083] The upper shell 62 is provided with an inlet 64, the bottom of the cone 63 is provided with an ash outlet 65, and the upper end of the inner cylinder 61 is provided with an air outlet 66.
[0084] After entering the high-efficiency cyclone separator 4 through inlet 64, the flue gas begins to rotate centrifugally. During the high-speed rotation of the flue gas, centrifugal force acts on the solid particles, causing these solid particles to rub against the inner wall of the high-efficiency cyclone separator 4. Under the action of friction, the speed of the solid particles gradually slows down and eventually separates from the gas, sliding down the inner wall of the high-efficiency cyclone separator 4 and finally being discharged through ash outlet 65. The exhaust gas after the solid particles have been separated enters from below the inner cylinder 61 and is finally discharged through air outlet 66.
[0085] Since inserting the inner cylinder 61 too deeply may affect the flow field of the cone and cause dust, the high-efficiency cyclone 4 is equipped with a tail vortex isolator 67 near the lower part of the cone 63. The tail vortex isolator 67 can effectively prevent dust from being generated by the equipment.
[0086] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0087] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, this utility model will not describe the various possible combinations separately.
[0088] Furthermore, various different embodiments of this utility model can be combined in any way, as long as they do not violate the spirit of this utility model, they should also be regarded as the content disclosed by this utility model.
Claims
1. A bypass ventilation system for multi-stage cyclone separators connected in series and parallel, characterized in that, The multi-stage cyclone bypass ventilation system includes an air intake (1), a quenching device (2), a primary cyclone (3), a high-efficiency cyclone (4), and an exhaust fan (5) connected in sequence. The insertion depth L of the inner cylinder (61) of the high-efficiency cyclone (4) is set to 1200-5200mm, and the air velocity at the air inlet of the high-efficiency cyclone (4) is set to 20-30m / s.
2. The bypass ventilation system of multi-stage cyclone separators connected in series and parallel according to claim 1, characterized in that, The outlet temperature of the quenching equipment (2) is set to be below 450°C.
3. The bypass ventilation system of multi-stage cyclone separators connected in series and parallel according to claim 1, characterized in that, Multiple high-efficiency cyclones (4) are set up, and multiple high-efficiency cyclones (4) are connected in parallel to form a group of secondary cyclones.
4. The bypass ventilation system of multi-stage cyclone separators connected in series and parallel according to claim 3, characterized in that, A gate valve (7) is installed at the inlet of the high-efficiency cyclone (4), and the gate valve (7) controls the inlet wind speed of the high-efficiency cyclone (4).
5. The bypass ventilation system of multi-stage cyclone separators connected in series and parallel according to claim 3, characterized in that, The number of high-efficiency cyclones (4) in a set of secondary cyclones is set to an even number.
6. The bypass ventilation system of multi-stage cyclone separators connected in series and parallel according to claim 3, characterized in that, Multiple sets of secondary cyclones are set up, and multiple sets of secondary cyclones are connected in series.
7. The bypass ventilation system of multi-stage cyclone separators connected in series and parallel according to any one of claims 1-6, characterized in that, The high-efficiency cyclone separator (4) also includes an upper shell (62) and a cone (63) connected to the upper shell (62). One end of the inner cylinder (61) is inserted into the upper shell (62), and the tail vortex isolator (67) is set at the connection between the upper shell (62) and the cone (63). An inlet (64) is provided on the upper shell (62), an outlet (65) is provided at the bottom of the cone (63), and an air outlet (66) is provided at the top of the inner cylinder (61).