Horizontal mud-water separator
By designing the screen structure and centrifugal force in a horizontal mud-water separator, efficient separation of solid-liquid phase mixture and multi-stage screening of solid-phase particles is achieved, solving the problems of high cost and large land use of existing equipment, and improving production efficiency and system stability.
Patent Information
- Application Number
- CN202422460971.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-11
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2034-10-11
AI Technical Summary
When handling solid phase grading products, existing horizontal separators need to add additional conveying equipment and screening equipment, which increases equipment cost and labor cost, and also requires site size, which cannot meet the needs of multi-stage solid phase separation.
A horizontal mud-water separator is designed, adopting a screen body structure, including liquid phase screen sections and solid phase screen sections. The size of the screen hole is designed as needed, combined with the inclination setting of the screen body and the centrifugal force, the solid-liquid phase separation and solid phase grading screening are achieved synchronously.
It realizes efficient separation of solid-liquid phase mixture and multi-stage screening of solid-phase particles, reducing the number of equipment and footprint, reducing costs, and improving system stability and production efficiency.
Smart Images
Figure CN223170501U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of mud-water separation, in particular to a horizontal mud-water separator. Background Art
[0002] Most of the mainstream horizontal separators on the current market only separate the solid phase and the liquid phase from the solid-liquid mixture. This separation method is very effective for a single solid-liquid mixture. However, when there is a need for classified products of the solid phase, this horizontal mud-water separation equipment cannot meet the requirements. Additional conveying equipment and screening equipment need to be added, which increases the equipment cost, the labor cost, and also has certain requirements for the site size. Summary of the Utility Model
[0003] An embodiment of the utility model discloses a horizontal mud-water separator, which is used to synchronously realize the classification and screening of the remaining solid-phase particles in the mixture on the basis of separating the solid-liquid mixture into the solid phase and the liquid phase.
[0004] An embodiment of the utility model provides a horizontal mud-water separator, including: a screening body, which is provided with screening holes. The screening body includes a liquid-phase screening section and a solid-phase screening section connected in sequence. The screening holes of the liquid-phase screening section are smaller than those of the solid-phase screening section. The screening holes of the liquid-phase screening section are used to screen out the liquid and fine particles in the mixture, and the screening holes of the solid-phase screening section are used to screen out the solid-phase particles in the mixture that are larger than the fine particles in size.
[0005] Further, the solid-phase screening section includes a plurality of particle screening sections. The sizes of the screening holes of the plurality of particle screening sections are different, and the screening holes of the plurality of particle screening sections increase in sequence in the direction away from the liquid-phase screening section.
[0006] Further, the screening body is inclined, the inlet end of the screening body is higher than the outlet end of the screening body, the inlet end of the screening body is close to the liquid-phase screening section, and the outlet end of the screening body is close to the solid-phase screening section.
[0007] Further, a plurality of the screening holes are provided on each screening section of the screening body.
[0008] Further, the number of the screening holes of each screening section decreases as the size of the screening holes increases.
[0009] Further, a housing is arranged outside the screening body. Discharge ports corresponding to each screening section are sequentially arranged below the housing, and a partition is arranged between the discharge ports corresponding to adjacent screening sections.
[0010] Further, the discharge port corresponding to the liquid-phase screening section is funnel-shaped, and the discharge port corresponding to the solid-phase screening section is open-type.
[0011] Further, a storage tank is arranged below the outlet end of the screening body and above the discharge port.
[0012] Further, the screening body is a rotating drum, which is a hollow columnar structure. The sieve holes are arranged on the side wall of the rotating drum. The rotating drum is used to rotate around its central axis, thereby generating a centrifugal force to make the material move radially along the rotating drum, realizing material screening.
[0013] Further, the rotating drum is cylindrical.
[0014] It can be seen from the technical solution that the embodiments provided by the present utility model have the following advantages:
[0015] In this embodiment, a liquid-phase sieve section and a solid-phase sieve section are arranged on the screening body of a horizontal sludge separator. The sieve holes of the liquid-phase sieve section are smaller than those of the solid-phase sieve section. The liquid and the carried fine particles will be separated through the sieve holes of the liquid-phase sieve section. The solid-phase particles larger than the fine particles cannot pass through the sieve holes of the liquid-phase sieve section and are separated on the liquid-phase sieve section. Then, they further pass through the sieve holes on the solid-phase sieve section and are separated. Finally, the remaining solid-phase objects that cannot pass through the sieve holes of the solid-phase sieve section are separated on the solid-phase sieve section and wait to be recycled. Therefore, a horizontal sludge separator in this example realizes the grading screening of the remaining solid-phase particles in the mixture while separating the solid-liquid mixture into solid and liquid phases. Description of the Drawings
[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0017] Figure 1 It is a schematic structural diagram of a horizontal sludge separator provided in an embodiment of the present utility model.
[0018] Reference numerals: 1, rotating shaft; 2, belt; 3, motor; 4, support frame; 5, baffle; 6, fine sieve discharge port; 7, medium sieve sand receiving tank; 8, coarse sieve sand receiving tank; 9, slag stone tank; 10, storage tank; 11, coarse sieve section; 12, medium sieve section; 13, fine sieve section; 14, housing; 15, feed pipe. Detailed Embodiments
[0019] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.
[0020] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.
[0021] In the description of this specification, specific features, structures, materials, or characteristics can be combined in a suitable manner in any one or more embodiments or examples.
[0022] An embodiment of the present utility model discloses a horizontal mud-water separator.
[0023] Please refer to Figure 1 , an embodiment of a horizontal mud-water separator provided in an embodiment of the present utility model includes:
[0024] A screening body is provided with screening holes. The screening body includes a liquid-phase screening section and a solid-phase screening section connected in sequence. The screening holes of the liquid-phase screening section are smaller than those of the solid-phase screening section. The screening holes of the liquid-phase screening section are used to screen out the liquid and fine particles in the mixture, and the screening holes of the solid-phase screening section are used to screen out the solid-phase particles in the mixture that are larger in size than the fine particles.
[0025] It can be understood that the liquid and the carried fine particles will be separated through the screening holes of the liquid-phase screening section. The solid-phase particles larger in size than the fine particles cannot pass through the screening holes of the liquid-phase screening section and are separated on the liquid-phase screening section. Further, they pass through the screening holes on the solid-phase screening section and are separated. Finally, the remaining solid-phase materials that cannot pass through the screening holes of the solid-phase screening section are separated on the solid-phase screening section and wait to be recycled. Therefore, through the setting of the above structure, this embodiment can synchronously classify and screen the solid-phase sediment after realizing mud-water separation.
[0026] In a more specific embodiment, the solid-phase sieve section can be further divided into multiple particle sieve sections with different sieve hole sizes according to the requirements of the screening size of the solid-phase material. The sieve holes of the multiple particle sieve sections increase sequentially in the direction away from the liquid-phase sieve section. The sieve holes of different sizes are used to guide the corresponding solid-phase particle heads of different sizes to discharge from the sieve holes respectively, thereby automatically realizing the multi-stage screening of the solid-phase particles.
[0027] In a more specific embodiment, the screening body is inclined, with the inlet end of the screening body higher than the outlet end. The inlet end of the screening body is close to the liquid-phase sieve section, and the outlet end of the screening body is close to the solid-phase sieve section. The liquid-phase sieve section is higher than the solid-phase sieve section, so that the solid-phase material that has undergone solid-liquid screening and is separated on the liquid-phase sieve section can transition to the solid-phase sieve section under the action of gravity for solid-phase classification screening. In some more specific embodiments, the screening body is horizontally arranged, and a thrust device is provided on the screening body, so that the solid-phase material that has undergone solid-liquid screening and is separated on the liquid-phase sieve section can transition to the solid-phase sieve section under the action of thrust.
[0028] In a more specific embodiment, multiple sieve holes are provided in each sieve section of the screening body to improve the screening efficiency.
[0029] In a more specific embodiment, the number of sieve holes in each sieve section decreases as the size of the sieve holes increases. Smaller-sized screening materials require more refined screening, and the number of sieve holes in the corresponding sieve section needs to increase, thereby increasing the screening area, improving the screening accuracy and screening efficiency. At the same time, for smaller-sized screening materials, they are prone to accumulate at the sieve holes, resulting in blockage. Increasing the number of sieve holes can disperse the distribution of the materials, reduce the load on a single sieve hole, and reduce the risk of blockage. At the same time, more sieve holes can also give the blocked materials more opportunities to pass through other sieve holes, maintaining the continuity of screening.
[0030] In some more specific embodiments, according to the requirements of different screening effects and processing costs, regular-shaped or irregular-shaped sieve holes can be reasonably selected to improve the performance and adaptability of the screening equipment and meet the requirements of various industrial production and processing. In some more specific implementation manners, the sieve holes are circular sieve holes. The circular sieve holes have the same size in all directions, and have good uniformity for the screening of granular materials. No matter from which angle the particles pass through the sieve holes, the passing probability is relatively stable, and the particle size of the screened particles can be controlled more accurately. Compared with some irregular-shaped sieve holes, circular sieve holes are not prone to unstable screening results due to different orientations of the particles. In some other more specific implementation manners, the sieve holes are square sieve holes. Compared with circular sieve holes, square sieve holes can provide more effective screening area per unit area, and the processing of square sieve holes may be easier than that of circular sieve holes. In the processing such as punching and laser cutting, the square shape is easier to achieve high-precision processing, and the processing cost is relatively low.
[0031] In a more specific embodiment, the screening body is a rotating drum. The rotating drum is a hollow columnar structure, and the sieve holes are arranged on the side of the rotating drum. When the rotating drum rotates, the material in the rotating drum is affected by the centrifugal force and is thrown towards the side of the rotating drum. At the same time, the material is also affected by gravity and has a tendency to move downward. The material continuously moves in the rotating drum as the rotating drum rotates. When the material reaches the side of the rotating drum, if it meets the screening requirements, it can pass through the sieve holes and be discharged. The material that does not meet the requirements continues to move in the rotating drum until it is screened out or discharged from the end of the rotating drum. In this embodiment, the centrifugal force and gravity difference generated by the rotation of the rotating drum are used to separate the material. The smaller-sized material is more likely to pass through the sieve holes on the surface of the rotating drum under the action of the centrifugal force, while the larger-sized material continues to move forward in the rotating drum until it is discharged from the discharge port. In some more specific implementation manners, the rotating drum is cylindrical. The internal space of the cylindrical rotating drum is relatively large, which can accommodate more materials and improve production efficiency. In operations such as screening, mixing, and drying, the materials can fully tumble and flow in the rotating drum, making full contact with the inner wall and internal structure of the rotating drum to achieve better processing effects. Moreover, the rotation stability of the cylindrical rotating drum is also relatively good, which can reduce the vibration and noise generated due to unbalanced rotation, and lower the operation cost and maintenance difficulty of the equipment. In some other more specific implementation manners, the rotating drum is cuboid-shaped, and each surface of the cuboid rotating drum can be conveniently connected and integrated with other equipment.
[0032] In some more specific implementation manners, the screening body is a vibrating sieve plate. The material is affected by the vibration on the sieve plate and moves along the sieve surface. The smaller-sized material passes through the sieve holes and falls, while the larger-sized material continues to move on the sieve surface to achieve accelerated screening.
[0033] In a more specific embodiment, a feed pipe is provided at the inlet end of the screening body, and the end of the feed pipe 15 extends into the liquid-phase screening section, enabling the material to be screened to enter and fall into the liquid-phase screening section.
[0034] In a more specific embodiment, a baffle 5 is provided at the end of the liquid-phase screening section, and the feed pipe 15 is arranged in the middle of the baffle 5. The baffle 5 is used to prevent the sediment in the drum from splashing out of the drum from the starting end of the liquid-phase screening section into the housing 14, affecting the screening effect.
[0035] In a more specific embodiment, a housing 14 is provided outside the screening body. The housing 14 includes a feed inlet, which is arranged on one side of the liquid-phase screening section. The feed inlet is connected to the feed pipe 15 to enable the material to enter the screening body and first complete the solid-liquid screening process.
[0036] In a more specific embodiment, discharge outlets corresponding to each screening section of the screening body are provided at the lower end of the housing 14, and partitions are provided between the discharge outlets corresponding to each screening section. Among them, a liquid-phase discharge outlet corresponds to the liquid-phase screening section and a solid-phase discharge outlet corresponds to the solid-phase screening section, and a partition is provided between the liquid-phase discharge outlet and the solid-phase discharge outlet. In a more specific embodiment, the solid-phase screening section includes multiple particle screening sections, and multiple solid-phase particle discharge outlets are also correspondingly provided at the lower end of the housing, and partitions are also provided between the multiple solid-phase particle discharge outlets.
[0037] In a more specific embodiment, the liquid-phase discharge outlet is funnel-shaped. The funnel-shaped discharge outlet can effectively prevent the liquid material from splashing out during the discharging process, can better control the outflow direction of the material, and enable the liquid material to flow out stably.
[0038] In a more specific embodiment, the solid-phase discharge outlet is open-type, which can improve the recovery speed of solid-phase particles and reduce the risk of blockage.
[0039] In a more specific embodiment, the liquid-phase discharge outlet is connected to the muddy water recovery pipeline.
[0040] In a more specific embodiment, a receiving groove 10 is provided below the outlet end of the drum and above the discharge outlet. The receiving groove 10 is inclined and is connected to the housing 14. The receiving groove 10 is used to collect the slag stones remaining on the drum in the drum and moving to the outlet end of the drum under the action of gravity. The slag stones moving to the outlet end of the drum further fall into the receiving groove under the action of gravity to achieve the recovery of large-diameter slag stones.
[0041] In a more specific embodiment, a slag stone groove 9 is provided below the receiving groove 10.
[0042] In a more specific embodiment, the housing 14 is disposed outside the drum and does not rotate with the drum. The housing 14 serves as a collection container to collect the separated liquid or solid substances, while the drum rotates at a high speed inside to achieve the separation operation.
[0043] In a more specific embodiment, the rotating shaft 1 is disposed on the central axis of the drum and is fixedly connected to the drum to ensure that the drum rotates together when the rotating shaft rotates. In a more specific embodiment, since the inlet end of the drum needs to insert the feed pipe, connection components are provided at the outlet and / or middle of the drum and fixedly connected to the rotating shaft 1. It can be understood that the setting of the connection components does not affect the output of large-diameter screening stones from the outlet end of the drum, nor does it affect the transition of materials between the screening zones. In a more specific embodiment, the connection components are disposed at the junctions of the screening zones, which can increase the residence time of materials in each screening zone to a certain extent and make the screening more thorough.
[0044] In a more specific embodiment, the connection components adopt a hollow structure.
[0045] In a more specific embodiment, both ends of the rotating shaft 1 are installed in the bearing seats and are rotatably connected to the bearing seats. The bearing seats are fixed on the support frame 4 to provide a stable support structure for the entire drum system, bearing the weights of the drum, the rotating shaft 1, and the materials, as well as the centrifugal force generated during rotation.
[0046] In a more specific embodiment, the drum is installed inside the housing 14. The housing 14 provides external protection and a working space for the drum. A certain gap is usually maintained between the drum and the housing 14 to avoid friction and collision during rotation. The housing 14 can be fixed on the support frame 4, the bearing seats, or other basic structures to ensure its stable position.
[0047] In a more specific embodiment, an observation window is provided outside the housing 14.
[0048] In a more specific embodiment, one end of the rotating shaft 1 extends out of the bearing seat and is connected to the motor. In some more specific embodiments, the rotating shaft 1 is connected to the motor 3 by means of belt 2 transmission. An active pulley is installed on the motor shaft, and a driven pulley is installed on the rotating shaft 1. The power of the motor 3 is transmitted to the rotating shaft 1 through the belt 2. The belt 2 transmission has an overload protection function. When the load is too large, the belt 2 will slip to avoid damage to the motor 3 and the rotating shaft 1. In other more specific embodiments, the rotating shaft 1 is connected to the motor 3 by means of gear transmission connection. An active gear is installed on the motor shaft, and a driven gear is installed on the rotating shaft 1. The power of the motor is transmitted to the rotating shaft through the meshing of the gears. The gear transmission has the advantages of high transmission efficiency, accurate transmission ratio, and strong load-bearing capacity.
[0049] In a more specific embodiment, an adjustable component is provided on the support frame 4 for changing the height of the support frame and thus adjusting the tilt angle of the drum. Devices such as hydraulic jacks, screw jacks, or electric push rods can be used as the adjustment mechanism for the support frame. During installation, the drum is installed on the support frame 4, and the tilt angle of the drum is changed by adjusting the height of the jack or the length of the screw push rod.
[0050] In a more specific embodiment, the drum of a horizontal mud-water separator is composed of a fine sieve section 13, a medium sieve section 12, and a coarse sieve section 11. The fine sieve section 13 is a liquid-phase sieve section, and the medium sieve section 12 and the coarse sieve section 11 are solid-phase sieve sections. The angle between the rotating shaft 1 of the drum and the horizontal plane is 10° - 25°, so that the sediment inside the drum is continuously moved towards the outlet end of the drum under the influence of gravity.
[0051] The mesh number of the sieve holes in the fine sieve section 13 is about 75 meshes, and the aperture of the sieve holes is 0.2 mm.
[0052] The mesh number of the sieve holes in the medium sieve section 12 is about 20 meshes, and the aperture of the sieve holes is 0.9 mm.
[0053] The mesh number of the sieve holes in the coarse sieve section 11 is about 8 meshes, and the aperture of the sieve holes is 3 mm.
[0054] At the lower end of the housing 14, three discharge ports are divided according to the three sections of the fine sieve section 13, the medium sieve section 12, and the coarse sieve section 11, and there are partitions between the discharge ports of each section.
[0055] Among them, the fine sieve section 13 mainly separates water in the liquid phase, and the set discharge port is the fine sieve discharge port 6. The fine sieve discharge port 6 is funnel-shaped, and a connecting flange is welded at the end.
[0056] The medium sieve section 12 and the coarse sieve section 11 mainly contain solid-phase sediment, and the set discharge ports are open ports, and there are a medium sieve sand receiving groove 7 and a coarse sieve sand receiving groove 8 respectively below.
[0057] At the end of the housing 14, there is a receiving groove 10 corresponding to the outlet of the drum. The receiving groove 10 receives the large-particle-size slag and stones separated by the drum, and the other end of the receiving groove 10 extends into the slag groove 9.
[0058] The working principle of the horizontal mud-water separator in this embodiment is as follows:
[0059] Taking shield mud as an example, the mud enters from the feed port and reaches the fine sieve section of the equipment drum. The motor 3 of the equipment drives the rotating shaft to rotate at a high speed through the belt 2. Since the rotating shaft 1 and the drum are connected together, the drum rotates together with the rotating shaft 1, and the drum rotates at a high speed around the rotating shaft 1.
[0060] Stage 1:
[0061] The mud will rotate at high speed under a strong centrifugal force in the fine sieve section 13, and the liquid and the fine soil carried will be separated through the sieve holes of the fine sieve section 13. Since the entire drum is at a certain inclination angle, the mud will gradually move from the fine sieve section 13 to the medium sieve section 12. During the process of the mud moving to the medium sieve section 12, water and fine soil will be continuously separated. The separated water and fine soil form clay mud, which is finally transported to the next treatment process through the funnel-shaped fine sieve discharge port 6 and the slurry pump.
[0062] Stage Two:
[0063] The mud reaching the medium sieve section 12 is mainly composed of sediment and sand, with a moisture content of less than 70%. The medium sieve section 12 mainly screens out fine sand products smaller than 1 mm from the mud coming from the fine sieve section 13. The fine sand products fall into the medium sieve sand receiving trough 7 through the sieve holes.
[0064] Stage Three:
[0065] The coarse sieve section 11 mainly screens out coarse sand products smaller than 3 mm from the materials coming from the medium sieve section 12. The coarse sand products fall into the coarse sieve sand receiving trough 8.
[0066] The final product separated from the outlet end of the entire drum is slag stone, which falls from the slag stone trough into the storage trough 10 and can be used as concrete aggregate.
[0067] This embodiment has the following beneficial effects:
[0068] This embodiment realizes the integration of the mud-water separation process and the sediment screening process. After the mud-water separation is achieved, the solid-phase sediment can be graded and screened synchronously. Combining the mud-water separation and sediment screening processes reduces the complexity of the equipment. The integrated process only requires one integrated device. Compared with using a mud-water separation device and a sediment screening device separately, the device has a high integration degree, making the device have a smaller volume, greatly reducing the floor area of the device; and the design of the integrated device is more compact and efficient, which can reduce energy consumption and operating costs; the integrated process completes the mud-water separation and sediment screening in one device, reducing the material transportation link, simplifying the process flow, improving the stability and reliability of the system, having lower maintenance costs, and reducing labor, site, and upfront capital investment.
[0069] It should be noted that the terms describing the positional relationship in the above examples and drawings are only for illustrative purposes and should not be construed as a limitation of this patent; the above various embodiments of the present invention are merely examples given to clearly illustrate the present invention and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.
Claims
1. A horizontal mud-water separator, characterized in that, Comprising: A screening body, on which there are screening holes. The screening body includes a liquid-phase screening section and a solid-phase screening section connected in sequence. The screening holes of the liquid-phase screening section are smaller than those of the solid-phase screening section. The screening holes of the liquid-phase screening section are used to screen out the liquid and fine particles in the mixture, and the screening holes of the solid-phase screening section are used to screen out the solid particles in the mixture that are larger in size than the fine particles.
2. The horizontal mud-water separator according to claim 1, wherein, The solid-phase screening section includes a plurality of particle screening sections. The sizes of the screening holes of the plurality of particle screening sections are different, and the screening holes of the plurality of particle screening sections increase in sequence in a direction away from the liquid-phase screening section.
3. A horizontal muddy water separator according to claim 1, characterized in that, The screening body is inclined, with the inlet end of the screening body higher than the outlet end. The inlet end of the screening body is close to the liquid-phase screening section, and the outlet end of the screening body is close to the solid-phase screening section.
4. A horizontal muddy water separator according to claim 1, characterized in that, A plurality of the screening holes are provided on each screening section of the screening body.
5. A horizontal mud separator according to claim 4, characterized in that, The number of the screening holes in each screening section decreases as the size of the screening holes increases.
6. A horizontal mud-water separator according to claim 1, characterized in that, A housing is provided outside the screening body. Below the housing, discharge ports corresponding to each screening section are sequentially provided, and a partition is provided between the discharge ports corresponding to adjacent screening sections.
7. A horizontal mud-water separator according to claim 6, characterized in that, The discharge port corresponding to the liquid-phase screening section is funnel-shaped, and the discharge port corresponding to the solid-phase screening section is open-type.
8. A horizontal muddy water separator according to claim 6, characterized in that, A receiving groove is provided below the outlet end of the screening body and above the discharge port.
9. A horizontal muddy water separator according to claim 1 or 3, characterized in that The screening body is a rotating drum, which is a hollow columnar structure. The screening holes are provided on the side wall of the rotating drum. The rotating drum is used to rotate around its central axis, thereby generating a centrifugal force to make the material move along the radial direction of the rotating drum to achieve material screening.
10. A horizontal muddy water separator according to claim 9, characterized in that, The rotating drum is cylindrical.