Double-screw conveyor

Abstract

A double-screw conveyor includes: a first screw shaft having a first extension axis and rotatable about the first extension axis in a first direction; the second spiral shaft is provided with a second extension axis parallel to the first extension axis and can rotate around the second extension axis in a second direction opposite to the first direction; the first blade is arranged on the first spiral shaft and extends along the first spiral shaft in a spiral manner; the first blade is arranged on the first spiral shaft, the second blade is arranged on the second spiral shaft, extends along the second spiral shaft in a spiral mode and is configured to be meshed with the first blade, a first crushing area is formed between one of the first blade and the second blade and the opposite spiral shaft, and a second crushing area is formed between the other one of the first blade and the second blade and the opposite spiral shaft. And a second crushing area is formed between the first blade and the second blade.

Description

Technical Field

[0001] The present disclosure relates to a double screw conveyor. Background Art

[0002] Screw conveyor is a commonly used solid material conveying equipment. The material is pushed axially by the rotation of the screw shaft with spiral blades to achieve material conveying. In this process, the material is affected by the friction of the material trough or the conveying pipe wall and does not rotate with the screw shaft, so it has relative motion along the surface of the spiral blades. In conventional applications, screw conveyors are suitable for conveying powdery, granular, and small block materials that are easy to disperse, but not suitable for conveying materials that are easy to deteriorate, highly viscous, large in size, and easy to agglomerate.

[0003] In the field of sludge treatment, screw conveyors are a commonly used sludge conveying equipment, mainly because of their simple structure, compact size, low cost, and easy maintenance and management. In addition, in the process of conveying materials, screw conveyors crush materials by friction between the spiral blades and the materials, and by squeezing the materials in the gap between the spiral blades and the trough. However, this friction and squeezing effect is relatively random, so screw conveyors are usually not used as a means of particle size control.

[0004] With the popularization of high-pressure plate and frame filter press dewatering machines, the moisture content of the dehydrated sludge can be reduced to below 60%, and the volume and mass of the sludge are significantly reduced, which brings convenience to the subsequent sludge transportation and treatment and disposal. The sludge after plate and frame dehydration is originally in the form of large, irregular, non-fluid, cake-like materials with a thickness of more than ten to thirty millimeters. It has a certain hardness and strong abrasiveness, and is often transported by a screw conveyor. If the sludge after plate and frame dehydration is to be further processed or disposed of, such as aerobic fermentation, drying, carbonization, incineration, etc., it is generally necessary to carry out specific crushing or pretreatment according to the process requirements to reduce the particle size of the sludge and control the particle size distribution, which requires the installation of a dedicated crusher. However, since the sludge after plate and frame dehydration is not a homogeneous material, the moisture content of the mud cake in different time periods may vary with the different properties of the sludge and operating conditions, and the moisture content of the same mud cake shows a characteristic of gradually increasing from the outside to the inside. When the mud cake is broken, the moisture content of sludges of different particle sizes will be differentiated and increased. Since the part with high moisture content inside the sludge is exposed, the sludge particle size changes, which will cause the properties of the sludge to change greatly, especially the small and high-water material, which is easy to absorb moisture, has high viscosity, and is easy to adhere, aggregate, wrap rotating parts, and form arches and bridges, which ultimately affects the crushing effect. Therefore, it has always been a technical problem to select a crusher that can adapt to this change in properties in engineering applications. In addition, when the step-by-step treatment method of crushing the sludge after spiral conveying is adopted, the properties of the sludge have changed because the spiral conveying process has already caused a certain degree of crushing of the sludge, and the above problems are more prominent. Summary of the invention

[0005] Therefore, the purpose of the present disclosure is to provide a double screw conveyor, which crushes the sludge during the process of conveying the sludge and controls the particle size of the sludge at the same time. Therefore, the double screw conveyor can be particularly applied to plate and frame dewatering sludge, and has a simple and compact structure, reducing the manufacturing cost and sludge conveying cost.

[0006] The above objects are achieved by the double screw conveyor described below.

[0007] The present disclosure provides a double screw conveyor, comprising: a first screw shaft, having a first extension axis and capable of rotating around the first extension axis in a first direction; a second screw shaft, having a second extension axis parallel to the first extension axis and capable of rotating around the second extension axis in a second direction opposite to the first direction; a first blade, arranged on the first screw shaft and extending along the first screw shaft in a spiral manner; and a second blade, arranged on the second screw shaft, extending along the second screw shaft in a spiral manner, and configured to mesh with the first blade, wherein a first crushing area with a first minimum distance is formed between a blade portion of one of the first blade and the second blade located in a meshing area and the relative screw shaft, and a second crushing area with a second minimum distance is formed between a blade portion of one of the first blade and the second blade located in a meshing area and a corresponding blade portion of the other of the first blade and the second blade. By setting the first crushing area between the spiral blade and the relative screw shaft and the second crushing area between the meshing spiral blades, the sludge can be crushed and the crushed particle size can be controlled.

[0008] The double screw conveyor of the present disclosure may also have the features described in the following embodiments individually or in combination.

[0009] In one embodiment, the edges of the first blade and the second blade are respectively provided with a plurality of tooth-shaped grooves. By providing the tooth-shaped grooves, it is possible to prevent the spiral blades from rolling and compacting the sludge at the bottom of the shell to form a dense mud layer.

[0010] In one embodiment, each of the first blade and the second blade has a plurality of periodic sections, and the number of the tooth-shaped grooves provided on each of the plurality of periodic sections is between two and six.

[0011] In one embodiment, the edges of the first blade and the second blade are each further provided with a plurality of V-shaped groove groups. By providing the V-shaped groove groups, the spiral blades can clamp and grasp the mud blocks when rotating to prevent the mud blocks from sliding, and can also produce a piercing and crushing effect on the mud blocks, so that fine particles are not easily produced like squeezing mud blocks, and the negative impact of fine particles or powder on crushing can be avoided.

[0012] In one embodiment, on each of the plurality of periodic sections, the V-shaped groove groups and the tooth-shaped grooves are alternately arranged.

[0013] In one embodiment, the first crushing area is formed between the tooth-shaped groove or V-shaped groove group on one of the first blade and the second blade and the relative spiral axis; the second crushing area is formed between the tooth-shaped groove or V-shaped groove group on one of the first blade and the second blade and the edge of the other of the first blade and the second blade.

[0014] In one embodiment, the first minimum distance is in the range of 10 mm to 50 mm; and / or the second minimum distance is in the range of 10 mm to 50 mm. By controlling the size of the first crushing area and the second crushing area, not only the sludge can be crushed, but also the crushed particle size can be controlled to achieve precise control.

[0015] In one embodiment, the rotation speed of the first screw shaft and / or the second screw shaft is variable frequency regulated, so as to prevent serious wear caused by high rotation speed and avoid affecting the continuous and stable operation of the screw shaft.

[0016] In one embodiment, the rotation speed of the first screw shaft is different from the rotation speed of the second screw shaft. In this way, the meshing mode between the blades on the two screw shafts can be controlled to create conditions for optimizing crushing.

[0017] In one embodiment, the double screw conveyor further comprises a housing for accommodating the first screw shaft, the second screw shaft, the first blade and the second blade, wherein a gap is formed between the bottom of the housing and the first blade and / or the second blade, and the gap is not more than 10 mm. This can prevent the spiral blades from being unable to effectively destroy the structure of the mud layer through the scraping effect when a thick mud layer accumulates at the bottom of the housing, so that the mud layer gradually thickens and causes the screw shaft to be supported, and finally the screw cannot operate normally.

[0018] In one embodiment, the double screw conveyor further comprises a crushing assembly, which is arranged near the discharge port of the double screw conveyor and comprises a first crushing element and a second crushing element, wherein the first crushing element is arranged on the shell, and the second crushing element is arranged on the first screw shaft and / or the second screw shaft. The crushing assembly is a supplement to the aforementioned crushing area, intercepts and crushes the mud blocks that are not crushed by the spiral blades, and ensures the overall crushing effect.

[0019] In one embodiment, the first crushing element and the second crushing element are each provided with a sawtooth structure, which can crush the sludge more effectively and reduce the particle size of the sludge to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The advantages and purposes of the present disclosure can be better understood from the preferred embodiments of the present disclosure described in detail below in conjunction with the accompanying drawings. In order to better show the relationship between the various components in the accompanying drawings, the accompanying drawings are not drawn to scale. In the accompanying drawings:

[0021] Figure 1 A schematic diagram of a screw conveyor conveyor according to the prior art is shown.

[0022] Figure 2 A schematic projection diagram of a double screw conveyor according to an embodiment of the present disclosure is shown.

[0023] Figure 3 A partial schematic diagram of a double screw conveyor according to an embodiment of the present disclosure is shown.

[0024] Figure 4 A partial schematic diagram of a double screw conveyor according to an embodiment of the present disclosure is shown.

[0025] Figure 5 A schematic end projection diagram of a double screw conveyor according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the technical solution of the present disclosure clearer, the technical solution of the embodiment of the present disclosure will be clearly and completely described in combination with the drawings of the specific embodiments of the present disclosure. The same figure marks in the drawings represent the same parts. It should be noted that the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0027] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The words "first", "second" and similar words used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not necessarily indicate a quantity limitation. Words such as "include", "comprise" or "have" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to the physical or mechanical connections or connections shown in the drawings, but may include connections or connections equivalent thereto, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0028] Figure 1 A known conventional screw conveyor is shown, which can be used to crush the sludge after plate frame dewatering. The screw conveyor includes a trough and a screw shaft and a spiral blade arranged in the trough, and the spiral blade is a continuous spiral surface blade. The sludge can be crushed by the friction between the spiral blade and the sludge when the spiral blade rotates, and by using the spiral blade to squeeze the sludge blocks to break them up through the space between the edge of the spiral blade and the trough. The above-mentioned space includes the space between the spiral blade and the trough wall of the trough and the space between the spiral blade and the bottom wall of the trough. However, the above-mentioned conventional screw conveyor has the following problems.

[0029] Firstly, the sludge blocks after plate and frame dehydration enter the above-mentioned extrusion space randomly. Only particles that meet a certain particle size have the opportunity to enter the above-mentioned space. The sludge blocks are also easy to slide and escape. Therefore, the crushing uncertainty of the screw conveyor is high and the crushing effect guarantee rate is low.

[0030] Secondly, the particle size distribution of the sludge crushed by extrusion is uneven, which easily produces fine-sized materials or powders. These materials or powders have strong hygroscopicity and high adhesion, and are easy to adhere to and cover the spiral blades and spiral shafts, reducing the effective space of the spiral action, thereby weakening or even losing the crushing effect of the spiral blades.

[0031] Furthermore, after the sludge is crushed, the part with high water content is exposed, and there is more sludge with fine particles or powder. Therefore, the sludge has strong cohesion and is easily compacted into a dense mud layer and gradually thickened by continuous spiral blades at the bottom or bottom wall of the trough, thereby forming a support for the spiral blades, causing the rotation of the spiral shaft to deviate from the axis, damaging the driving structure of the spiral shaft, and causing the spiral blades to lose their crushing effect. Figure 1The sludge layer accumulated on the bottom wall of the trough is shown in light grey.

[0032] The above problems and defects result in that conventional screw conveyors cannot be widely used in the conveying and crushing of plate and frame dewatered sludge.

[0033] Below, see Figures 2 to 5 Embodiments of the present disclosure are described in detail.

[0034] Figure 2 The projection along the axial direction to the discharge end of the machine is shown. According to the present disclosure, a double screw conveyor is provided, which has two screws. Specifically, the double screw conveyor includes a first screw shaft 1, a second screw shaft 2, a first blade 3, a second blade 4, and a housing 7. The housing 7 is used to accommodate the first screw shaft 1, the second screw shaft 2, the first blade 3 and the second blade 4. The housing 7 may include a trough and a top cover, may have a substantially rectangular cross-sectional shape, and includes a bottom wall 8, a side wall 10 and a top cover 9, the top cover is provided with a sludge feed port, and the bottom wall may be provided with a sludge discharge port.

[0035] In addition, the double screw conveyor also includes a motor, which can output a suitable rotation speed after starting, for example, via a reduction device, and the output shaft of the motor can be connected to one screw shaft in the double screw conveyor through a bearing, and connected to the other screw shaft through a gear device and a bearing.

[0036] The first screw shaft 1 has a first extension axis 11 and can rotate around the first extension axis 11 in a first direction R1. The second screw shaft 2 has a second extension axis 12 and can rotate around the second extension axis 12 in a second direction R2. The above rotations are all centered on the corresponding extension axis. Both ends of the first screw shaft 1 and the second screw shaft 2 can be installed through the housing. Figure 4 As shown, the second extension axis 12 is parallel to the first extension axis 11. The first direction R1 is opposite to the first direction R1. For example, the first direction R1 is Figure 2 The first direction R1 is the clockwise direction, and the second direction R2 is the counterclockwise direction. For example, the rotation speed of the first spiral shaft 1 is equal to the rotation speed of the second spiral shaft 2, but the present disclosure is not limited thereto.

[0037] The first blade 3 is disposed on the first spiral shaft 1 and extends in a spiral manner along the first spiral shaft 1. The second blade 4 is disposed on the second spiral shaft 2 and extends in a spiral manner along the second spiral shaft 2, and is configured to mesh with the first blade 3. The meshing described herein means that a blade portion, such as a convex portion, of one spiral blade can be embedded in a blade portion, such as a concave portion, of another spiral blade, such as Figure 4As shown. In other words, the convex part of the spiral blade is transverse to the spiral axis and passes through the center line between the two spiral axes. A meshing area is formed at the corresponding convex part and concave part, for example, between the two. It should be noted that the first blade 3 and the second blade 4 of the present disclosure are continuously extended spiral blades with a continuous surface.

[0038] like Figure 4 As shown, the first blade 3 and the second blade 4 have opposite rotation directions, and their respective rotation directions match the rotation directions of their corresponding spiral axes. This matching ensures that the two spirals do not interfere with each other during rotation.

[0039] See again Figure 4 , a first crushing area A1 having a first minimum distance S1 is formed between the blade portion of one of the first blade 3 and the second blade 4 located in the meshing area and the relative screw axis, and a second crushing area A2 having a second minimum distance S2 is formed between the blade portion of one of the first blade 3 and the second blade 4 located in the meshing area and the corresponding blade portion of the other of the first blade 3 and the second blade 4. The "minimum distance" described herein refers to a distance that is smaller than other blade portions, and may be a distance interval having a range of values.

[0040] For example, a first crushing area A1 is formed between the edge of the blade part of one of the first blade 3 and the second blade 4 located in the meshing zone and the relative spiral axis, and a second crushing area A2 is formed between the edge of the blade part of one of the first blade 3 and the second blade 4 located in the meshing zone and the edge of the corresponding blade part of the other blade.

[0041] like Figure 4 As shown, the first blade 3 and the second blade 4 each have a plurality of periodic sections P. Figure 3 , a schematic diagram of the second blade 4 is shown in FIG. 1 , and the periodic section P refers to the blade portion of the spiral blade that rotates one circle around the corresponding spiral axis, which can also be called the pitch.

[0042] See again Figure 2 , the edges of the first blade 3 and the second blade 4 are respectively provided with a plurality of tooth-shaped grooves 5. The tooth-shaped grooves 5 may have a geometric shape that is approximately rectangular or trapezoidal. Additionally or alternatively, the edges of the first blade 3 and the second blade 4 are respectively provided with a plurality of V-shaped groove groups 6. Each V-shaped groove group 6 has at least 3 V-shaped grooves. Every two V-shaped grooves of the V-shaped groove group 6 form a sawtooth structure, so the whole structure may also be called a sawtooth structure.

[0043] The number of tooth-shaped grooves 5 provided on each of the plurality of periodic sections P is between two and six. Figure 2As shown, two tooth-shaped grooves 5 are provided on each periodic section P. For example, the plurality of tooth-shaped grooves 5 are evenly distributed along the circumference on the projection surface of the spiral blade, such as Figure 2 As shown in . For example, the width of each toothed groove 5 at the widest point is 60 mm to 100 mm.

[0044] The toothed grooves can break up the sludge, such as Figure 2 The sludge shown in light grey on the bottom wall 8 of the middle shell can be shredded by the toothed grooves. By providing the toothed grooves, it is possible to prevent the spiral blades from rolling and compacting the sludge at the bottom of the shell (e.g., on the bottom wall 8) to form a dense mud layer.

[0045] See also Figure 2 In each of the plurality of periodic sections P, the V-groove groups 6 and the tooth-shaped grooves 5 are arranged alternately. For example, the plurality of V-groove groups 6 are evenly distributed along the circumference on the projection surface of the spiral blade, such as Figure 2 For example, the width of the widest part of the V-grooves of each V-groove group 6 is 30 mm to 50 mm.

[0046] By setting up a V-shaped groove group, the spiral blade can clamp and grab mud blocks (such as Figure 2 The sludge shown in light gray in the figure is clamped by the V-shaped groove group), which prevents the mud blocks from sliding and can also produce a puncture and crushing effect on the mud blocks. Therefore, it will not easily produce fine particles like squeezing the mud blocks, and can avoid the negative impact of fine particles or powder on crushing.

[0047] A first crushing area A1 having a first minimum distance S1 is formed between the tooth-shaped groove 5 or the V-shaped groove group 6 on one of the first blade 3 and the second blade 4 and the opposite spiral shaft. A second crushing area A2 having a second minimum distance S2 is formed between the tooth-shaped groove 5 or the V-shaped groove group 6 on one of the first blade 3 and the second blade and the edge of the other of the first blade 3 and the second blade 4. In other words, the crushing area is formed by the gap between the meshing blades or between the blades and the opposite spiral shaft. For example, Figure 4As shown, a first crushing area A1 is formed between the tooth groove 5 of the first blade 3 (specifically, the edge corner of the tooth groove 5) and the second spiral shaft 2, and has a first minimum distance S1 in a direction transverse to, for example, perpendicular to, the second extension axis 12; a second crushing area A2 is formed between the tooth groove 5 of the first blade 3 (specifically, the edge corner of the tooth groove 5) and the edge of the blade part of the second blade 4 closest thereto, and has a second minimum distance S2 in a direction transverse to, for example, perpendicular to, for example, perpendicular to the edge of the blade part of the second blade 4. Similarly, a first crushing area A1 is formed between the tooth groove 5 of the second blade 4 (specifically, the edge corner of the tooth groove 5) and the first spiral shaft 1, and has a first minimum distance S1 in a direction transverse to, for example, perpendicular to, the first extension axis 11; a second crushing area A2 is formed between the tooth groove 5 of the second blade 4 (specifically, the edge corner of the tooth groove 5) and the edge of the blade portion closest to it of the first blade 3, and has a second minimum distance S2 in a direction transverse to, for example, perpendicular to, for example, perpendicular to the edge of the blade portion of the first blade 3. That is, in one periodic section P, the number of the first crushing area A1 and the second crushing area A2 is multiple.

[0048] For example, the first minimum distance S1 ranges from 10 mm to 50 mm, and the second minimum distance S2 ranges from 10 mm to 50 mm. Of course, the first minimum distance S1 can range from 10 mm to 50 mm or the second minimum distance S2 can range from 10 mm to 50 mm.

[0049] By setting a first crushing area between the spiral blade and the relative spiral shaft and a second crushing area between the meshing spiral blades, and controlling the sizes of the first crushing area and the second crushing area, not only can the sludge be crushed, but also the crushed particle size can be controlled to achieve precise control.

[0050] For example, the rotation speed of the first spiral shaft 1 and the second spiral shaft 2 is adjustable by variable frequency. Of course, it is also possible that the rotation speed of the first spiral shaft 1 or the second spiral shaft 2 is adjustable by variable frequency. For example, the rotation speed of the first spiral shaft 1 and / or the second spiral shaft 2 is between 10 and 50 rpm. In this way, it is possible to prevent a higher rotation speed from causing more serious wear, and avoid affecting the continuous and stable operation of the spiral.

[0051] For example, the rotation speed of the first screw shaft 1 and / or the second screw shaft 2 can be variable frequency regulated, and the rotation speed of the first screw shaft 1 and the rotation speed of the second screw shaft 2 can be adjusted to be different from each other, so as to have a certain speed difference. In this way, the meshing mode, such as the meshing degree, between the blades on the two screw shafts can be controlled to create conditions for optimizing crushing.

[0052] For example, a gap is formed between the bottom wall 8 of the housing 7 and the first blade 3 and the second blade 4, respectively. Figure 3 As shown, the dimension of the gap S3 in the direction transverse to the second extension axis 12, for example, does not exceed 10 mm. In this way, when a thick mud layer accumulates at the bottom of the shell, the edge or edge of the spiral blade cannot effectively destroy the structure of the mud layer through the scraping effect, so that the mud layer gradually thickens and causes the spiral shaft to be supported, and finally the spiral cannot operate normally.

[0053] For example, the double screw conveyor further comprises a crushing assembly 10, which is arranged near the discharge port of the double screw conveyor. Figure 5 As shown in the schematic projection diagram along the axial direction to the discharge end of the machine, the crushing assembly 10 includes a first crushing element 13 and a second crushing element 14, the first crushing element 13 is arranged on the shell 7, and the second crushing element 14 is arranged on the first screw shaft 1 and the second screw shaft 2. In other examples, the second crushing element 14 can be arranged only on the first screw shaft 1 or only on the second screw shaft 2. When the rotating second crushing element 14 meets the fixed first crushing element 13, a scissors-like effect is formed to shear and crush the mud blocks between the two crushing elements. There is a gap between the first crushing element 13 and the second crushing element 14 in the axial direction, and the gap is not greater than 10 mm. The axial position of the first crushing element 13 is adjustable, for example, the axial gap between the first crushing element 13 and the second crushing element 14 can be adjusted according to the material characteristics.

[0054] For example, the first crushing element 13 is fixedly arranged on the side wall 10, the bottom wall 8 and the top cover 9 of the shell. For example, for each spiral shaft, at least three first crushing elements 13 are arranged, wherein at least one first crushing element 13 is arranged perpendicular to the bottom wall 8, at least one first crushing element 13 is arranged perpendicular to the top cover 9, and at least one first crushing element 13 is arranged obliquely relative to the side wall 10. The second crushing element 14 can rotate following the corresponding spiral shaft. For example, the second crushing element 14 can be arranged on the corresponding spiral shaft at uniform intervals. For example, for each spiral shaft, four to eight second crushing elements 14 are arranged. For example, in the direction toward the discharge port along the extension axis of the corresponding spiral shaft, the first crushing element 13 is closer to the discharge port than the second crushing element 14.

[0055] For example, the first crushing element 13 is provided with a sawtooth structure 15, and the second crushing element 14 is provided with a sawtooth structure 16. For example, the sawtooth structures 15 and 16 are each formed by a plurality of V-shaped grooves. According to the requirements for the particle size control of the sludge, the width of the widest part of the V-shaped groove is controlled to be, for example, between 30 mm and 50 mm. For example, the sawtooth structure 16 on the second crushing element 14 is configured to protrude toward the rotation direction of the corresponding spiral shaft (i.e., the direction of the tip of the tooth), that is, the sawtooth structure 16 of the second crushing element 14 on the first spiral shaft 1 protrudes toward the first direction R1, and the sawtooth structure 16 of the second crushing element 14 on the second spiral shaft 1 protrudes toward the second direction R2. In addition, the protruding direction of the sawtooth structure 15 on the first crushing element 13 is opposite to the protruding direction of the sawtooth structure 16 on the corresponding second crushing element 14.

[0056] The crushing assembly 10 is a supplement to the aforementioned crushing area. By providing an additional crushing assembly 10, the mud blocks that are not crushed by the spiral blades can be intercepted and crushed, thereby ensuring the overall crushing effect.

[0057] The double screw conveyor disclosed in the present invention can control the particle size of the sludge while conveying the sludge, which can well meet the particle size control requirements of subsequent treatment, and has a simple and compact structure, reducing the manufacturing cost and the sludge conveying cost. For example, the double screw conveyor disclosed in the present invention can reduce the particle size to less than 50 mm while conveying the plate frame dewatered sludge, and the mass proportion of particles less than 30 mm is 70% to 85%. In other words, the particle size control requirements required for subsequent treatment are met.

[0058] In addition, the technical features disclosed above are not limited to the disclosed combinations with other features. Those skilled in the art may also make other combinations between the technical features according to the purpose of disclosure to achieve the purpose of this disclosure.

Claims

1. A double screw conveyor, comprising: A first screw shaft (1) having a first extension axis (11) and capable of rotating about the first extension axis in a first direction (R1); a second spiral shaft (2) having a second extension axis (12) parallel to the first extension axis and capable of rotating about the second extension axis in a second direction (R2) opposite to the first direction; A first blade (3) is arranged on the first spiral shaft (1) and extends along the first spiral shaft in a spiral manner; as well as A second blade (4) is arranged on the second spiral shaft (2), extends along the second spiral shaft in a spiral manner, and is configured to mesh with the first blade (3). A first crushing area (A1) having a first minimum distance (S1) is formed between a blade portion of one of the first blade and the second blade located in the meshing zone and the relative screw axis, and a second crushing area (A2) having a second minimum distance (S2) is formed between a blade portion of one of the first blade and the second blade located in the meshing zone and a corresponding blade portion of the other of the first blade and the second blade.

2. The double screw conveyor according to claim 1, wherein: The first blade (3) and the second blade (4) are each provided with a plurality of tooth-shaped grooves (5) on their edges.

3. The double screw conveyor according to claim 2, wherein: The first blade (3) and the second blade (4) each have a plurality of periodic sections (P), and the number of tooth-shaped grooves (5) provided on each of the plurality of periodic sections is between two and six.

4. The double screw conveyor according to claim 3, wherein: A plurality of V-shaped groove groups (6) are also provided on the edges of each of the first blade and the second blade.

5. The double screw conveyor according to claim 4, wherein: On each of the plurality of periodic sections, the V-shaped groove groups and the tooth-shaped grooves are alternately arranged.

6. The double screw conveyor according to claim 5, wherein: The first crushing area is formed between the tooth-shaped groove or V-shaped groove group on one of the first blade and the second blade and the opposite screw shaft; The second crushing area is formed between the tooth-shaped groove or the V-shaped groove group on one of the first blade and the second blade and the edge of the other of the first blade and the second blade.

7. The double screw conveyor according to claim 5, wherein: The first minimum distance ranges from 10 mm to 50 mm; and / or the second minimum distance ranges from 10 mm to 50 mm.

8. The double screw conveyor according to claim 1, wherein: The rotation speed of the first screw shaft and / or the second screw shaft can be adjusted by variable frequency.

9. The double screw conveyor according to claim 8, wherein: The rotation speed of the first screw shaft is different from the rotation speed of the second screw shaft.

10. The double screw conveyor according to claim 1, wherein: The double screw conveyor further comprises a housing (7) for accommodating the first screw shaft, the second screw shaft, the first blade and the second blade, wherein a gap is formed between the bottom wall (8) of the housing and the first blade and / or the second blade, and the gap does not exceed 10 mm.

11. The double screw conveyor according to claim 10, wherein: The double screw conveyor further comprises a crushing assembly (10), which is arranged near the discharge port of the double screw conveyor and comprises a first crushing element (13) and a second crushing element (14), wherein the first crushing element (13) is arranged on the shell (7), and the second crushing element (14) is arranged on the first screw shaft (1) and / or the second screw shaft (2).

12. The double screw conveyor according to claim 11, wherein: The first crushing element (13) and the second crushing element (14) are each provided with a sawtooth structure (15, 16).

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