5 Keys to Optimizing Belt Bucket Elevator Design

5 Keys to Optimizing Belt Bucket Elevator Design

Belt bucket elevators are a type of conveyor used to vertically transport loose bulk materials through a series of buckets attached to a belt. As the belt rotates, the buckets scoop up material at the bottom and release it at the top.

Some common uses and applications for belt bucket elevators include:

  • Transporting grains, cereals, pulses, seeds, etc. in the agricultural and food processing industries.
  • Conveying cement, minerals, fertilizers, etc. in the mining and construction industries.
  • Moving packaged goods in warehouses and distribution centers.

The key components of a belt bucket elevator include:

  • Buckets to contain the material. They can have a variety of shapes like centrifugal discharge and positive discharge buckets.
  • Belts that form a continuous loop to carry the buckets. Rubber, PVC, urethane, and steel cord belts are commonly used.
  • Drive unit to power the belt. This is usually a motor coupled to a gearbox.
  • Casing that encloses the belt and buckets. It is designed for loading, transit, and discharge of material.

Compared to other conveying methods, some of the main advantages of belt bucket elevators include:

  • Ability to lift materials vertically over long heights.
  • High capacity of up to 2000 cubic feet per hour.
  • Enclosed design contains dust and debris.
  • Gentle handling protects fragile materials from damage.
  • Low power consumption relative to capacity.
  • Compact footprint saving floor space.
  • Flexible design to meet specific application needs.

Overall, belt bucket elevators provide an efficient and reliable solution for vertical transportation of bulk materials in many industries. Proper design is key to optimizing their performance and longevity.

Bucket Elevator Configurations

Bucket elevators come in several common configurations to suit different material handling needs:

Horizontal

Horizontal bucket elevators convey material horizontally. The buckets are attached to a belt that travels horizontally and scoops up material at one end, carrying it to the discharge at the other end.

Horizontal configurations are commonly used when there is not enough vertical space for a vertical elevator or an inclined elevator would be too steep. They allow conveying material over long horizontal distances efficiently.

Vertical

Vertical bucket elevators convey material vertically in a straight up and down path. The buckets pick up the material at the bottom and lift it up to the discharge at the top.

Vertical elevators are the most common configuration and widely used when there is adequate headroom. They minimize the footprint and allow vertical changes in elevation for discharge.

Inclined

Inclined bucket elevators convey material at an angle between horizontal and vertical. The buckets elevate the material along the angled belt from a lower intake to an elevated discharge point.

Inclined elevators are utilized when there is limited headroom for a full vertical elevator and material needs to be elevated higher than a horizontal configuration allows. The angle can be adjusted to fit spatial constraints.

The choice of bucket elevator configuration depends on the height material needs to be lifted, horizontal space available, and headroom constraints. Consulting manufacturers on ideal angles and dimensions ensures the elevator is designed for efficiency and safety.

Bucket Types and Design

There are three main types of buckets used in belt bucket elevators:

Centrifugal Buckets

Centrifugal buckets utilize centrifugal force to discharge material. They are open-topped and attached to the belt at one point on the back side. As the bucket reaches the top of the elevator, centrifugal force causes the material to discharge out of the open top.

Centrifugal buckets are a simple and economical choice, but spillage can occur, especially with fine materials. They are best suited for free-flowing materials like grains.

Continuous Buckets

Continuous buckets are designed as a continuous line of enclosed buckets attached to each other and the belt. At the discharge point, the bucket tips upside down to empty its contents.

Continuous buckets provide positive control over the material being conveyed. They can handle most dry bulk materials, even difficult flowing ones like wet clay or chemicals. Capacity per bucket is lower than centrifugal types.

Positive Engagement Buckets

Positive engagement buckets grip the material to ensure complete discharge. They utilize a “digger” arm that extends into the material to positively engage it. As the arm rotates at discharge, it sweeps the bucket clear.

Positive engagement buckets are ideal for difficult materials prone to sticking or bridging, like wet clay, fly ash, or wood chips. They provide the best discharge control but have higher power requirements.

Bucket Materials and Shapes

Buckets are commonly constructed from steel, stainless steel, or plastic. Steel and stainless steel buckets provide durability for demanding applications. Plastic buckets are lighter weight and can be a good choice for corrosive or sticky materials.

Bucket shape is designed based on the material conveyed. V-shaped buckets work well for granular materials while rectangular buckets suit blocky or elongated products. Custom bucket shapes can optimize the elevator for specific materials.

Design Considerations

Proper bucket selection, sizing, and spacing ensures optimal elevator capacity and efficiency. Factors like bulk density of the material, lump size, abrasiveness, and desired capacity guide the design. Consulting an experienced designer is recommended to match the buckets and elevator to the application. With the right bucket design, belt bucket elevators can reliably handle virtually any dry bulk solid material.

Belt Selection and Design

The belt is a critical component of any belt bucket elevator design. Selecting the right belt involves considering several factors:

Belt Types

The most common belt types used in belt bucket elevators are:

  • Rubber – Rubber belts are flexible and have good grip. They are well-suited for handling lightweight materials. Rubber has natural resistance to abrasion but can be damaged by oils.
  • Plastic – Plastic belts like PVC and urethanes are used for medium duty applications. They have good chemical resistance but low traction.
  • Steel – Steel belts are extremely strong and used for heavy loads. They are rigid and may require special pulleys. Steel belts resist wear but can be noisy.

Design Considerations

Key factors to consider when selecting and designing a belt for a belt bucket elevator:

  • Belt Width – Wider belts can carry more load. Belt widths are chosen based on capacity requirements.
  • Belt Strength – The belt must have adequate strength for the weight of the loaded buckets. Materials, layers and reinforcements are selected accordingly.
  • Flexing Ability – The belt needs flexibility to bend around the pulleys. More flexible belts require larger pulley diameters.
  • Pulley Traction – Rubber belts offer the best grip on pulleys. Plastic and steel belts may require lagging or special coatings to increase traction.
  • Abrasion Resistance – Materials like rubber and urethane resist abrasion from the buckets and the casing. Steel belts are prone to wear unless protected.
  • Chemical Resistance – Rubber and steel belts are vulnerable to oils and solvents. Plastic belts like PVC offer better chemical resistance.

Proper belt specification ensures reliable transport and long service life when designing a belt bucket elevator. The belt must be strong enough to handle the load while maintaining flexibility and traction.

Drive Components

The drive components are critical for the proper functioning and longevity of a belt bucket elevator. These include the drive and take-up pulleys, shafts, bearings, and power transmission elements like gearboxes, motors, and drives.

The drive pulley provides the force to move the belt and buckets and is usually the larger pulley located at the discharge end. The pulley needs to be sized and aligned properly to avoid belt slippage or uneven wear. Common drive pulley designs are drum-type or wing pulleys. The pulley material should be selected to match the belt specifications.

The take-up pulley provides the proper belt tensioning and is located at the opposite end of the drive pulley. It is usually adjustable to maintain optimal belt tension as the belt stretches over time. The take-up pulley needs robust bearings to handle the tension loads.

The pulley shafts support the pulleys and transmit the drive forces. They need to be sized appropriately for the torque requirements. Common shaft materials are steel or cast iron. The shafts require sturdy mounting brackets and bearings.

The bearings support the pulley shafts and allow them to rotate smoothly. Different types of bearings like roller bearings, sleeve bearings, or pillow block bearings are used based on the load capacity and shaft size. Proper lubrication of the bearings is essential.

For power transmission, gear reducers or variable frequency drives can be used along with an electric motor to obtain the desired bucket speed. The gearbox increases the torque from the motor. The motor and drive need to be sized properly for the power needs and load characteristics of the elevator. Motor protection equipment is important for safety.

Proper selection, sizing, alignment, and maintenance of the drive components is crucial for optimal performance and longevity of a belt bucket elevator. Consulting manufacturers’ engineering guidelines is recommended.

Bucket Spacing and Speeds

Proper bucket spacing and speed is crucial for optimal performance of a belt bucket elevator. The spacing between buckets, known as pitch, helps determine the capacity and efficiency. Generally, closer bucket spacing provides higher capacity but slower speeds. Wider spacing allows higher speeds but lower capacity.

The optimal pitch is usually between 50-100% of the bucket width. Around 75% is common for general materials. Closer spacing like 50% is better for fine, dusty materials that are harder to capture. Wider spacing like 100% works for large lump materials.

Controlling bucket speed is also important. The maximum speed depends on the belt strength, bucket design, and material characteristics. Excessive speed can cause material to spill out of the buckets. Slow speed reduces capacity. Variable frequency drives can help control and adjust the speed as needed.

Proper bucket design with spacing, speed, and capacity in mind is key for maximum elevator efficiency. Consulting manufacturers and conducting material testing helps determine the ideal bucket size, spacing, and operating speeds. Careful calculation using formulas relating pitch, speed, capacity, and more can optimize these parameters. With good bucket spacing and speed control, belt bucket elevators can elevate a wide range of materials efficiently.

Casing and Chassis Design

The casing, or enclosure, is a key component of belt bucket elevator design. It serves several important functions:

  • Contains material within the system
  • Provides support for the belt, buckets, and other components
  • Protects components from external damage and contamination
  • Reduces noise and dust emissions

There are two main types of casings used in belt bucket elevators:

Steel Casings

Steel is the most common material used for casings due to its high strength and durability. Carbon steel is typically used, although stainless steel or other alloys may be specified for corrosion resistance.

Steel casings consist of formed and welded steel plates, with access doors installed at key locations to allow inspection and maintenance access. Proper design is critical to ensure adequate strength and stiffness of the casing while minimizing weight. Stiffener beams are often used internally for reinforcement.

Plastic Casings

Plastic casings provide an alternative to steel in some applications. High density polyethylene (HDPE) is commonly used. Although not as strong as steel, plastic casings are much lighter, reducing structural requirements. They also eliminate corrosion concerns.

Plastic casings can be advantageous in food production and chemical processing applications where avoiding metal contamination is critical. They also reduce noise transmission. Limitations include temperature resistance and strength, restricting plastic casings to smaller belt bucket elevators.

Key considerations for casing design include:

  • Supporting dead loads of casing and internal components
  • Resisting live loads from material loading
  • Preventing buildup of static electricity
  • Allowing adequate access for inspection and maintenance
  • Minimizing air leakage while providing ventilation
  • Isolating transmitted vibration and noise

With careful attention to design, the belt bucket elevator casing or enclosure provides critical protection and support to the system. The appropriate construction and sizing ensures reliable, long-term operation.

Loading and Discharge

Proper loading and discharge design is critical for efficient belt bucket elevator operation. The inlet and outlet are key areas that can lead to problems if not designed correctly.

Inlet and Outlet Designs

The inlet is where material first enters the belt bucket elevator. It should be designed to allow smooth entry of material into the buckets without spillage. Common inlet designs include box feeders, hoppers, chutes, and conveyors. The inlet often includes a tripping mechanism to tip material into the buckets. It’s important that the inlet matches the elevator’s capacity to avoid flooding or starvation.

The discharge is where material exits the elevator into downstream equipment or processes. The bucket tips and empties as it passes around the head pulley. The discharge chute should be designed to avoid material buildup and allow smooth outflow. Discharge designs typically include impact plates to control trajectory and chutes angled for mass flow. Any transitions should minimize turbulence.

Feeding and Discharging the Buckets

Proper bucket loading requires controlling the feed rate and trajectory. The inlet design should allow centering the feed stream into the buckets as they pass. The feed rate should match the bucket capacity and elevator speed to achieve the target volume. Too little feed will result in empty buckets, while too much can overload and spill.

At the discharge, the bucket tips upside down to empty its contents. This is usually achieved through a cam mechanism on the head pulley. Avoiding buildup and clogging at the discharge transition is critical. The bucket should completely invert and discharge fully before returning to the upright position. Discharge designs must account for the product characteristics like flowability.

Safety and Maintenance

Proper safety and maintenance practices are crucial for belt bucket elevators to operate safely and efficiently over their lifetime. Here are some key considerations:

Safe Design

  • Access platforms and ladders should be provided for inspection and maintenance. These allow safe access to key components.
  • Emergency stop switches should be installed at strategic locations to allow the system to be quickly shut down if needed.
  • The drive unit should have protective guards to prevent accidental contact with moving parts.
  • Sensors can automatically detect belt misalignment or loose buckets and shut down the system before damage occurs.
  • The elevator casing should fully enclose the belt and buckets to prevent material spillage or accidental contact.
  • Dust control systems may be needed for elevators handling fine, dusty materials.

Inspection and Maintenance

  • The belt, buckets and pulleys should be visually inspected regularly for signs of wear, misalignment or damage. Belts should be checked for proper tension.
  • Bearings, drive components and moving parts should be lubricated per the manufacturer’s recommendations.
  • The belt tracking should be checked and adjusted as needed to prevent misalignment.
  • Bucket attachments and welds should be inspected for cracks or looseness.
  • Belt splice joints should be checked for integrity and re-spliced if needed.
  • An annual shutdown allows a more thorough inspection and replacement of worn components like belts, bearings and seals.
  • Keep records of inspections, maintenance and parts replacements.

Following proper safety procedures and preventive maintenance ensures maximum uptime and long service life for belt bucket elevators. Workers should be properly trained on safe operation.

Advantages of Proper Belt Bucket Elevator Design

Properly designed belt bucket elevators provide significant benefits compared to poorly designed systems. Optimizing the design brings cost savings, improved efficiency, higher throughput, and better performance.

Some key advantages of a well-designed belt bucket elevator include:

  • Higher capacity – With the right bucket size, spacing, and speed, capacity can be maximized. This allows you to move more material per hour.
  • Lower power consumption – Optimized bucket loading, spacing, belt tension and drive components reduce energy usage. This saves on electricity costs.
  • Less material degradation – Good bucket and belt selection reduces damage to the material as it travels. Less breakdown improves product quality.
  • Reduced wear and maintenance – Quality components and proper alignment reduce friction and wear. This extends the life of buckets, belts, bearings and drives.
  • Improved safety – Proper guarding, walkways and access points make the elevator safer for workers to operate and maintain.
  • Lower noise levels – Using sound-dampening materials and isolation mounts reduces noise pollution.
  • Smaller footprint – Efficient design allows capacity goals to be reached within a smaller casing size. This saves space.

With an optimized design, belt bucket elevators provide excellent efficiency and performance. The upfront effort to properly design the system pays off over the long run through better throughput, lower costs, and improved reliability.

Contact Us for Your Conveyor Parts Solutions

Facebook
Twitter
LinkedIn