Two-stage cyclone separator system

Abstract

The invention discloses a two-stage cyclone separator system. The two-stage cyclone separator system comprises a first-stage cyclone separator and a second-stage cyclone separator, the number of the first screwing-in opening pipes is two, and the two first screwing-in opening pipes are located on the two sides of the first screwing-in shell correspondingly and evenly distributed in the circumferential direction of the first screwing-in shell. A seam hole is vertically formed in the two-screw-up gas pipe, and the top of the seam hole is located below an outlet of the two-screw-up inlet pipe. On the horizontal section, the seam hole deflects from the center line of the seam hole to the position of the axis of the two-rotation gas rising pipe, and the deflection direction is the same as the flowing direction of gas flow which flows around the two-rotation gas rising pipe in the circumferential direction outside the two-rotation gas rising pipe. The invention can be used in gas-solid fluidized bed equipment of various process devices such as petroleum refining catalytic cracking, coal chemical methanol-to-olefin and the like.

Description

Technical Field

[0001] This invention belongs to the technical field of gas-solid separation equipment, specifically relating to a two-stage cyclone separator system. Background Technology

[0002] In industries such as oil refining, chemicals, metallurgy, building materials, and power generation, many gas-solid fluidization systems utilize cyclone separators for gas-solid separation. For example, the regenerators in petroleum refining catalytic cracking units use cyclone separators to separate and recover valuable catalysts at high temperatures, maintaining the fluidized bed operation of the regenerator. The regenerator's process operation demands high overall separation efficiency from the cyclone separators; therefore, two-stage cyclone separator systems are commonly employed. See also... Figure 1 A two-stage cyclone separator system in the prior art is used in the regenerator of a catalytic cracking unit, comprising a first-stage cyclone separator and a second-stage cyclone separator connected in series. The first-stage cyclone separator includes a cyclone shell 11, a cyclone inlet pipe 12, a cyclone ash hopper 13, a cyclone feed leg 14, a cyclone riser pipe 15, and a cyclone outlet pipe 16. The second-stage cyclone separator includes a second cyclone shell 21, a second cyclone inlet pipe 22, a second cyclone ash hopper 23, a second cyclone feed leg 24, a second cyclone riser pipe 25, and a second cyclone outlet pipe 26. The inlet of the second cyclone inlet pipe 22 is connected to the first cyclone outlet pipe 16, and the outlet of the second cyclone inlet pipe 22 is connected to the second cyclone shell 21. Both the first cyclone shell 11 and the second cyclone shell 21 are composed of an upper cylindrical body and a lower inverted truncated conical body. The first cyclone inlet pipe 12 is composed of a volute tube, a straight pipe, and a bell mouth. An anti-reverse cone 3 is provided below the first rotating material leg 14, and the bottom of the second rotating material leg 24 is connected to the wing valve 4.

[0003] Using the existing two-stage cyclone separator system described above can increase the overall separation efficiency, but the overall pressure drop of the two-stage cyclone separator system will also be relatively large, thereby increasing the energy consumption of the process unit. In addition, the first-stage cyclone separator is equipped with a single-cyclone inlet pipe 12, which causes uneven airflow distribution into the single-cyclone shell 11, affecting the separation efficiency of the first-stage cyclone separator. Summary of the Invention

[0004] The purpose of this invention is to provide a two-stage cyclone separator system to solve the problem of large total pressure drop in existing two-stage cyclone separator systems, as well as the problem of uneven airflow distribution and reduced separation efficiency of the first-stage cyclone separator caused by only having one cyclone inlet pipe.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0006] A two-stage cyclone separator system comprises a first-stage cyclone separator and a second-stage cyclone separator, the first-stage cyclone separator comprises a first-stage cyclone shell, a first-stage cyclone inlet pipe, a first-stage cyclone riser pipe and a first-stage cyclone outlet pipe, the second-stage cyclone separator comprises a second-stage cyclone shell, a second-stage cyclone inlet pipe, a second-stage cyclone riser pipe and a second-stage cyclone outlet pipe, the inlet of the second-stage cyclone inlet pipe is connected with the first-stage cyclone outlet pipe, and the outlet of the second-stage cyclone inlet pipe is connected with the second-stage cyclone shell, the first-stage cyclone shell and the second-stage cyclone shell are both composed of an upper cylindrical barrel and a lower inverted truncated conical barrel, two first-stage cyclone inlet pipes are arranged, and the two first-stage cyclone inlet pipes are arranged on the two sides of the first-stage cyclone shell and are uniformly distributed around the circumference of the first-stage cyclone shell, a slit is vertically arranged on the second-stage cyclone riser pipe, the top of the slit is below the outlet of the second-stage cyclone inlet pipe, and in a horizontal cross section, the slit is deflected from the position of the center line of the slit to the position of the axis of the second-stage cyclone riser pipe, and the deflection direction is the same as the flow direction of the gas flow around the second-stage cyclone riser pipe.

[0007] The system further has the following features: a first-stage cyclone riser pipe flared mouth is arranged at the bottom air inlet of the first-stage cyclone riser pipe, a second-stage cyclone riser pipe flared mouth is arranged at the bottom air inlet of the second-stage cyclone riser pipe, the first-stage cyclone riser pipe flared mouth and the second-stage cyclone riser pipe flared mouth are both circular flared mouths, and the generatrix of the circular flared mouths is an arc.

[0008] The system further has the following features: in a horizontal cross section, the angle of deflection of the slit from the position of the center line of the slit to the position of the axis of the second-stage cyclone riser pipe is 30-70 degrees, the width of the slit is 1-3 mm, and the total flow area of the slit is 0.2-5 times the area of the bottom air inlet of the second-stage cyclone riser pipe.

[0009] The system further has the following features: the radius of the arc of the generatrix of the first-stage cyclone riser pipe flared mouth and the second-stage cyclone riser pipe flared mouth is 0.2-0.3 times the diameter of the bottom air inlet of the first-stage cyclone riser pipe and the bottom air inlet of the second-stage cyclone riser pipe, respectively.

[0010] The system further has the following features: the first-stage cyclone riser pipe is a straight pipe or an inverted truncated conical barrel with a circular cross section, the second-stage cyclone riser pipe is a straight pipe or an inverted truncated conical barrel with a circular cross section, the diameter of the bottom air inlet of the first-stage cyclone riser pipe and the second-stage cyclone riser pipe is 0.2-0.6 times the diameter of the cylindrical barrel of the first-stage cyclone shell and the cylindrical barrel of the second-stage cyclone shell, respectively, and when the first-stage cyclone riser pipe and the second-stage cyclone riser pipe are inverted truncated conical barrels, the taper angle C is 6-14 degrees.

[0011] The present application has the following beneficial effects:

[0012] 1. The second cyclone shell is provided with a slit hole, which can make part of the upward airflow in the second cyclone shell flow into the second cyclone riser through the slit hole in advance, thereby reducing the airflow entering the second cyclone riser from the bottom inlet of the second cyclone riser, and reducing the pressure drop of the second-stage cyclone separator. The top of the slit hole is located below the outlet of the second cyclone inlet pipe, which can fully utilize the separation capacity of the annular space above the top of the slit hole in the second cyclone shell, reduce the amount of particles reaching the outer surface area of the section where the slit hole is arranged, and help reduce the probability of particle loss. The setting direction of the slit hole makes the airflow outside the second cyclone riser have to change direction sharply before entering the second cyclone riser from the slit hole, so most of the particles carried by the rotating airflow outside the second cyclone riser are difficult to follow the airflow into the second cyclone riser from the slit hole due to inertia, thereby reducing the damage to the separation efficiency caused by the slit hole arranged on the second cyclone riser. In addition, the slit hole arranged on the second cyclone riser can increase the insertion depth of the second cyclone riser in the second cyclone shell, making the inner vortex in the second cyclone shell more stable, which helps to reduce the pressure drop and increase the separation efficiency.

[0013] 2. Two primary inlet pipes are arranged, and the particle-containing gas enters the primary cyclone shell from the two primary inlet pipes, so that the airflow distribution is more uniform, and the symmetry of the inner vortex is better than that of the existing first-stage cyclone separator with one primary inlet pipe, which can increase the separation efficiency of the first-stage cyclone separator.

[0014] 3. In the existing first-stage cyclone separator and second-stage cyclone separator, the bottom inlet of the primary cyclone riser and the secondary cyclone riser is a circular flat mouth, which makes the resistance of the airflow entering the primary cyclone riser and the secondary cyclone riser larger. In a preferred mode of the present application, a primary cyclone riser horn is arranged at the bottom inlet of the primary cyclone riser, and a secondary cyclone riser horn is arranged at the bottom inlet of the secondary cyclone riser, which can make the resistance of the airflow entering the primary cyclone riser and the secondary cyclone riser smaller.

[0015] The present application can be used in gas-solid fluidized bed equipment for various process devices such as petroleum refining catalytic cracking, coal chemical methanol-to-olefin, etc. Compared with the existing two-stage cyclone separator system, under the condition that the particle-containing gas inlet amount at the horn of the primary inlet pipe is basically the same, the total pressure drop of the two-stage cyclone separator system of the present application can be reduced by 15% to 30%, and the separation efficiency of the first-stage cyclone separator can be increased by 0.2% to 0.3%. The structure of the present application is simple and easy to popularize and apply. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic diagram of a two-stage cyclone separator system in the prior art.

[0017] Figure 2 is Figure 1 the top view of the two-stage cyclone separator system shown in

[0018] Figure 3is a schematic diagram of a two-stage cyclone separator system of the present application.

[0019] Figure 4 is Figure 3 is a top view of the two-stage cyclone separator system shown in

[0020] Figure 5 is Figure 3 is an A-A sectional view (enlarged) of

[0021] Figure 6 is a schematic diagram of the two-stage cyclone separator system in which the secondary cyclone riser pipe 25 is an inverted frusto-conical pipe.

[0022] In the figure: 11, primary cyclone housing; 12, primary cyclone inlet pipe; 13, primary cyclone hopper; 14, primary cyclone leg; 15, primary cyclone riser pipe; 16, primary cyclone outlet pipe; 17, primary cyclone riser pipe bell mouth; 21, secondary cyclone housing; 22, secondary cyclone inlet pipe; 23, secondary cyclone hopper; 24, secondary cyclone leg; 25, secondary cyclone riser pipe; 26, secondary cyclone outlet pipe; 27, secondary cyclone riser pipe bell mouth; 3, anti-inversion cone; 4, wing valve; 5, slot. DETAILED DESCRIPTION

[0023] The present application will be further described in conjunction with the accompanying drawings and specific embodiments.

[0024] Referring to Figure 3 and Figure 4 , a two-stage cyclone separator system (referred to as system) of the present application comprises a first stage cyclone separator and a second stage cyclone separator. The first stage cyclone separator comprises a primary cyclone housing 11, a primary cyclone inlet pipe 12, a primary cyclone hopper 13, a primary cyclone leg 14, a primary cyclone riser pipe 15, and a primary cyclone outlet pipe 16. The second stage cyclone separator comprises a secondary cyclone housing 21, a secondary cyclone inlet pipe 22, a secondary cyclone hopper 23, a secondary cyclone leg 24, a secondary cyclone riser pipe 25, and a secondary cyclone outlet pipe 26. The secondary cyclone inlet pipe 22 is composed of a secondary cyclone inlet pipe straight pipe and a secondary cyclone inlet pipe volute pipe, and the cross-sectional shape of the secondary cyclone inlet pipe straight pipe is rectangular. The inlet of the secondary cyclone inlet pipe 22 is connected to the primary cyclone outlet pipe 16, and the outlet of the secondary cyclone inlet pipe 22 (i.e. the outlet of the secondary cyclone inlet pipe volute pipe) is connected to the secondary cyclone housing 21. Both the primary cyclone housing 11 and the secondary cyclone housing 21 are composed of an upper cylindrical barrel and a lower inverted frusto-conical barrel, the primary cyclone leg 14 is provided with an anti-inversion cone 3 below, and the bottom of the secondary cyclone leg 24 is connected to a wing valve 4.

[0025] The system of the present application, one rotation inlet pipe 12 is provided with two, two one rotation inlet pipe 12 is located at the two sides of one rotation shell 11 respectively, and is uniformly distributed around the circumferential direction of one rotation shell 11.Each one rotation inlet pipe 12 is composed of one rotation inlet pipe volute pipe, one rotation inlet pipe straight pipe and one rotation inlet pipe horn mouth.The one end (outlet) of one rotation inlet pipe volute pipe is connected with the cylindrical barrel of one rotation shell 11, and the other end is connected with one end of one rotation inlet pipe straight pipe.The other end of one rotation inlet pipe straight pipe is connected with one rotation inlet pipe horn mouth, and one rotation inlet pipe horn mouth serves as the inlet of one rotation inlet pipe 12.The cross-sectional shape of one rotation inlet pipe straight pipe is rectangular.The overall shape of one rotation inlet pipe horn mouth is rectangular, and the cross-sectional shape of each side of the rectangle is circular arc.

[0026] Referring to Figure 3 , Figure 5 and Figure 6 , a plurality of slits 5 are vertically arranged on the two-rotation gas lift pipe 25, the slits 5 are strip-shaped holes, and the top of the slits 5 is located below the outlet of the two-rotation inlet pipe 22.In the horizontal cross-section, the slits 5 themselves are deflected from the center line through the position of the axis of the two-rotation gas lift pipe 25, and the deflection direction is the same as the flow direction of the gas flow (as shown by the arrow without the reference sign and the size in Figure 5 .

[0027] Figure 3 As shown in the system of the present application, the bottom air inlet of the one-rotation gas lift pipe 15 is provided with a one-rotation gas lift pipe horn mouth 17, and the bottom air inlet of the two-rotation gas lift pipe 25 is provided with a two-rotation gas lift pipe horn mouth 27.Both the one-rotation gas lift pipe horn mouth 17 and the two-rotation gas lift pipe horn mouth 27 are circular horn mouths, and the generatrix shape is circular arc.

[0028] The preferred scheme of the present application is that, in the horizontal cross-section, the angle B of the deflection of the slits 5 themselves from the center line through the position of the axis of the two-rotation gas lift pipe 25 is generally 30-70 degrees, and the width W of the slits 5 is generally 1-3 millimeters.The slits 5 are uniformly distributed in the circumferential direction of the two-rotation gas lift pipe 25 to form a slit 5 setting section.The total flow area of the slits 5 is generally 0.2-5 times the area of the bottom air inlet of the two-rotation gas lift pipe 25.

[0029] The radius of the generatrix circular arc of the one-rotation gas lift pipe horn mouth 17 and the two-rotation gas lift pipe horn mouth 27 is generally 0.2-0.3 times the diameter of the bottom air inlet of the one-rotation gas lift pipe 15 and the bottom air inlet of the two-rotation gas lift pipe 25 respectively.

[0030] The one-rotation gas lift pipe 15 can be a straight pipe with circular cross-section (as shown in Figure 3 ) or an inverted truncated conical surface pipe, and the two-rotation gas lift pipe 25 can be a straight pipe with circular cross-section (as shown in Figure 3 ) or an inverted truncated conical surface pipe (as shown in Figure 6The inverted truncated conical surface shaped tube of the first lift gas pipe 15 is omitted in the drawing, and can be referred to the inverted truncated conical surface shaped tube of the second lift gas pipe 25. Figure 6 The diameters of the bottom inlets of the first lift gas pipe 15 and the second lift gas pipe 25 are generally 0.2-0.6 times the diameters of the cylindrical barrel of the first cyclone shell 11 and the cylindrical barrel of the second cyclone shell 21 respectively. When the first lift gas pipe 15 and the second lift gas pipe 25 are inverted truncated conical surface shaped tubes, the cone angle C is generally 6-14 degrees (see the drawing). Figure 6 The advantage of using the inverted truncated conical surface shaped tube is that the probability of particles entering the first lift gas pipe 15 and the second lift gas pipe 25 and being lost can be reduced. The various dimensions of the present application, such as those related to the inner and outer surfaces of the relevant components, are measured and calculated based on the inner surface of the relevant components.

[0031] Figure 3 Figure 4 When the system of the present application shown in the drawing is applied to a gas-solid fluidized bed device such as a regenerator of a catalytic cracking unit, the working process is as follows: The gas containing particles enters the first stage cyclone from the two first stage cyclone inlet pipes 12. In the first cyclone shell 11, the gas forms a rotating downward outer vortex flow and a rotating upward inner vortex flow. The particles in the gas flow are affected by the centrifugal force generated by the rotation of the gas flow, and the relatively coarse and heavy particles move to the edge wall of the first cyclone shell 11 and then spiral downward, with most of them entering the first stage cyclone dust hopper 13. The particles in the first stage cyclone dust hopper 13 are discharged from the first stage cyclone through the first stage cyclone leg 14, completing the first cyclone separation process. The gas flow in the first cyclone shell 11, which is entrained with light and fine particles, spirals upward through the first lift gas pipe bell mouth 17, the first lift gas pipe 15, and the first stage cyclone outlet pipe 16, and then enters the second stage cyclone shell 21 of the second stage cyclone through the second stage cyclone inlet pipe 22, forming a rotating downward outer vortex flow and a rotating upward inner vortex flow.

[0032] The second stage cyclone separates the light and fine particles that were not separated by the first stage cyclone for a second time. The particles separated in the second cyclone shell 21 enter the second stage cyclone dust hopper 23 and are then discharged from the second stage cyclone through the second stage cyclone leg 24 and the wing valve 4. The particles that are not separated in the second cyclone shell 21 spiral upward with the gas flow, enter the second lift gas pipe 25 through the second lift gas pipe bell mouth 27 and the slit 5, and are finally discharged from the second stage cyclone through the top outlet of the second stage cyclone outlet pipe 26.

[0033] The particles discharged from the second stage cyclone are the particles lost from the two-stage cyclone system of the present application. The two-stage cyclone system of the present application and the wing valve 4 can be used in a gas-solid fluidized bed device such as a regenerator of a catalytic cracking unit. Figure 1 Figure 2 ​​The pressure difference between the inlet pipe bell mouth of the first stage cyclone separator and the outlet of the second stage cyclone gas lift pipe 25 is the total pressure drop of the two-stage cyclone separator system. The calculation method of the separation efficiency of the first stage cyclone separator is as follows: the ratio of the particle concentration in the gas at the outlet of the second stage cyclone inlet pipe 22 to the particle concentration in the gas at the inlet pipe bell mouth of the first stage cyclone separator is calculated, then 1 is subtracted from the ratio, and finally the result is expressed in percentage.

[0034] Comparative Example

[0035] According to the scheme shown in Figure 1 , Figure 2 A laboratory cold model test system was established according to the scheme shown in the figure. The diameters of the cylindrical barrels of the first stage cyclone separator shell 11 and the second stage cyclone separator shell 21 are both 300 mm. The height of the straight pipe of the first stage cyclone inlet pipe is 197 mm, and the width is 83 mm. The first stage cyclone gas lift pipe 15 and the second stage cyclone gas lift pipe 25 are both straight pipes with circular cross sections, and no first stage cyclone gas lift pipe bell mouth and second stage cyclone gas lift pipe bell mouth are provided. The diameter of the first stage cyclone gas lift pipe 15 is 110 mm. The structure of the second stage cyclone inlet pipe 22 is the same as that of the second stage cyclone inlet pipe 22 of the present application, the height of the straight pipe of the second stage cyclone inlet pipe is 174 mm, and the width is 74 mm. The diameter of the second stage cyclone gas lift pipe 25 is 96 mm, and the insertion depth in the second stage cyclone separator shell 21 is 236 mm. No slits 5 are provided on the second stage cyclone gas lift pipe 25. The gas containing particles is fed into the inlet pipe bell mouth of the first stage cyclone separator at a rate of 800-1250 cubic meters / hour (the same as in the examples).

[0036] The test of the comparative example (and the following examples) was carried out in an atmospheric environment at normal temperature and pressure. The gas containing particles was air containing silicon powder, the concentration of the silicon powder was 0.1 kg / m3, and the silicon powder was 800-mesh silicon powder (measured by sieving method). The normal temperature was 20°C, and the normal pressure was 1 atm (absolute pressure).

[0037] The test results of the comparative example were as follows: the total pressure drop of the two-stage cyclone separator system was 9-13.7 kPa, and the separation efficiency of the first stage cyclone separator was 89%-90%.

[0038] Example

[0039] According to the scheme shown in Figure 3 , Figure 4The shown scheme establishes a laboratory cold model test system. The diameters of the cylindrical cylinders of the first and second cyclone bodies 11 and 21 are both 300 mm. The height of the straight tube of the first cyclone inlet pipe is 131 mm, and the width is 65 mm. The diameter of the first cyclone riser pipe 15 and the bottom gas inlet of the first cyclone riser pipe 15 is 110 mm, and the radius of the generatrix circular arc of the first cyclone riser pipe bell mouth 17 is 25 mm. The height of the straight tube of the second cyclone inlet pipe is 176 mm, and the width is 73 mm. The diameter of the second cyclone riser pipe 25 and the bottom gas inlet of the second cyclone riser pipe 25 is 90 mm, the radius of the generatrix circular arc of the second cyclone riser pipe bell mouth 27 is 18 mm, and the total insertion depth of the second cyclone riser pipe 25 and the second cyclone riser pipe bell mouth 27 in the second cyclone body 21 is 300 mm. In the horizontal cross section, the angle B by which the slit hole 5 itself deviates from the position of the axis of the second cyclone riser pipe 25 through the center line of the slit hole 5 is 30 degrees, the width W of the slit hole 5 is 3 mm, and the total flow area of the slit hole 5 is 0.5 times the area of the bottom gas inlet of the second cyclone riser pipe 25.

[0040] Compared with the test results of the comparative examples, under the condition that the particle-containing gas inlet amount at the bell mouth of the first cyclone inlet pipe is the same, the total pressure drop of the two-stage cyclone separator system in the examples is reduced by 15% to 30%, and the separation efficiency of the first-stage cyclone separator is increased by 0.2% to 0.3%.

Claims

1. A two-stage cyclone separator system comprising a first stage cyclone separator and a second stage cyclone separator, the first stage cyclone separator comprising a first cyclone housing (11), a first cyclone inlet pipe (12), a first cyclone upcomer (15), a first cyclone outlet pipe (16), the second stage cyclone separator comprising a second cyclone housing (21), a second cyclone inlet pipe (22), a second cyclone upcomer (25), a second cyclone outlet pipe (26), the inlet of the second cyclone inlet pipe (22) being connected to the first cyclone outlet pipe (16), the outlet of the second cyclone inlet pipe (22) being connected to the second cyclone housing (21), the first cyclone housing (11) and the second cyclone housing (21) each comprising an upper cylindrical section and a lower inverted frustoconical section, characterized in that: Two one-rotation inlet pipes (12) are arranged on both sides of the one-rotation shell (11) and are uniformly distributed in the circumferential direction of the one-rotation shell (11). The two-rotation lift pipe (25) is provided with a slit (5) in the vertical direction. The top of the slit (5) is located below the outlet of the two-rotation inlet pipe (22). In the horizontal cross section, the slit (5) itself is deflected from the position of the center line of the two-rotation lift pipe (25) axis, and the deflection direction is the same as the flow direction of the gas flow around the two-rotation lift pipe (25).

2. The two-stage cyclone separator system of claim 1, wherein: The bottom air inlet of the one-rotation lift pipe (15) is provided with a one-rotation lift pipe horn (17), and the bottom air inlet of the two-rotation lift pipe (25) is provided with a two-rotation lift pipe horn (27). The one-rotation lift pipe horn (17) and the two-rotation lift pipe horn (27) are both circular horns, and the generatrix is a circular arc.

3. The two-stage cyclone separator system according to claim 1 or 2, characterized in that: In the horizontal cross section, the angle B of the slit (5) itself deflected from the position of the center line of the two-rotation lift pipe (25) axis is 30-70 degrees. The width W of the slit (5) is 1-3 mm, and the total flow area of the slit (5) is 0.2-5 times the area of the bottom air inlet of the two-rotation lift pipe (25).

4. The two-stage cyclone separator system of claim 3, wherein: The radius of the generatrix circular arc of the one-rotation lift pipe horn (17) and the two-rotation lift pipe horn (27) is 0.2-0.3 times the diameter of the bottom air inlet of the one-rotation lift pipe (15) and the two-rotation lift pipe (25), respectively.

5. The two-stage cyclone separator system of claim 4, wherein: The one-rotation lift pipe (15) is a straight pipe or an inverted truncated conical pipe with a circular cross section. The two-rotation lift pipe (25) is a straight pipe or an inverted truncated conical pipe with a circular cross section. The diameter of the bottom air inlet of the one-rotation lift pipe (15) and the two-rotation lift pipe (25) is 0.2-0.6 times the diameter of the cylindrical barrel of the one-rotation shell (11) and the cylindrical barrel of the two-rotation shell (21), respectively. When the one-rotation lift pipe (15) and the two-rotation lift pipe (25) are inverted truncated conical pipes, the taper angle C is 6-14 degrees.

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