Compound fertilizer

A bucket elevator is composed of several main components, each playing a vital role in its operation. The structure includes buckets, a drive mechanism, top and bottom rollers or sprockets, belts (or traction chains), tensioning devices, and a casing. Here's a breakdown of the key components and their specific characteristics:

1. The traction components of bucket elevators can vary based on the design and application: Rubber Belts are attached to the bucket mouth using screws and elastic gaskets. These belts are generally 35–40 mm wider than the bucket. Standard belts are suitable for conveying materials with temperatures up to 60°C, while heat-resistant belts can handle materials as hot as 150°C.

2. Chains are another traction option. Single chains are mounted on the back wall of the bucket, while double chains connect to both sides. For bucket widths of 160–250 mm, single chains are used, whereas widths of 320–630 mm employ double chains. Although chains are durable, they experience significant wear between links, requiring more frequent maintenance.

3. Sprockets are used in chain-driven bucket elevators. These components mesh precisely with the chain links to transfer motion. Designed for smooth and accurate engagement, sprockets minimize impact and stress on the chain during operation. The sprocket material is heat-treated to ensure strength and wear resistance, while its teeth are shaped to enable easy entry and exit of chain links.

4. The bucket design is tailored to the material being conveyed:
Cylindrical Buckets with deep, inclined openings are ideal for dry, free-flowing granular materials.
Shallow Buckets are used for damp, flowable granular materials, as their reduced depth prevents clogging.
Deep Buckets are suited for dry and free-flowing materials with good handling characteristics.
Triangular Buckets are used for materials discharged in a directed, self-flowing manner.
Angular Buckets feature extended sidewalls forming a channel with the base, making them effective for transporting sticky or heavy bulk materials.
Each component of a bucket elevator is meticulously designed to ensure efficient material handling and long-term reliability. From traction systems to bucket types, these features are chosen based on the material properties and operational requirements.

Bucket elevators are widely used vertical lifting devices that are categorized based on their transmission structure to meet various industry requirements:

1. TD Series: This series includes models like TD160, TD250, TD315, and others. Commonly used models are TD160, TD250, and TD315. These elevators use rubber belts for transmission and are suitable for materials with light to moderate abrasiveness.

2. TH Series: TH bucket elevators are driven by forged round link chains, offering higher mechanical strength. They are ideal for lifting powders, small granules, and small blocks with greater density. Their lifting capacity and operational efficiency surpass those of the TD series.

3. NE Series: NE elevators use plate chains for transmission and are modern replacements for older TB models. The naming system is based on lifting capacity (e.g., NE150 refers to a capacity of 150 tons per hour). This series is efficient and available in high-speed variants (NSE models).

4.TB Series: These older models also use plate chains but have largely been replaced by the NE series.

5.TG Series: Designed for grain transportation, TG elevators use steel-reinforced belts and offer superior transmission capabilities. These are specialized grain elevators.
Other Models: Additional types include HL series, GTD series, and GTH series, which are variations or evolutions of older models.

Bucket elevators discharge materials in three main ways based on bucket speed:
1. Centrifugal Discharge: High-speed discharge for powders, granules, and small block materials with low abrasiveness.
2. Gravity Discharge: Slow discharge for larger, heavier, and highly abrasive materials like limestone or clinker.
3. Mixed Discharge: A combination of the above for specific applications.

Traction components include chains, plate chains, and belts:
1. Chains: Simple and durable, suitable for highly abrasive materials but heavier in weight.
Plate Chains: Lightweight and robust, ideal for high-capacity elevators but prone to joint wear.
2. Belts: Easy to construct but unsuitable for abrasive materials. Temperature limits depend on belt type, with standard belts handling up to 60°C, steel-reinforced belts up to 80°C, and heat-resistant belts up to 120°C. Chains and plate chains can manage material temperatures up to 250°C.

Model selection depends on:
1. Material Form: Powder, granular, or small blocks.
2. Material Properties: Adhesion, moisture content, and abrasiveness.
3. Material Density: Models are typically designed for bulk densities below 1.6. Heavier materials require customized calculations for traction and tensile strength.
4. Capacity Requirements: The required conveying volume per unit of time.
The discharge method determines the bucket type, which affects overall capacity. The selection process involves evaluating material density, transmission method, material properties, discharge type, bucket form, lifting capacity, and ultimately choosing the appropriate model.

For the installation of bucket elevators, it is crucial to ensure that the machine is securely mounted on a solid concrete foundation. The surface of the concrete should be smooth and level to ensure that the bucket elevator is installed vertically after setting. For taller bucket elevators, it is important to anchor the middle and upper shells to adjacent structures such as silos or workshops to enhance stability. The installation process begins with the lower components being mounted and secured using anchor bolts, followed by the installation of the middle shell, and finally, the upper shell. After installation, verticality should be checked. A plumb line should be used from top to bottom, with a deviation of less than 10mm. Both upper and lower shafts should be parallel and in the same plane.

For shorter bucket elevators, all shells should be connected on a flat surface and adjusted as a whole before being lifted and fixed onto the concrete foundation. Once the shells are installed, the chain and buckets should be installed. The buckets are connected using U-shaped screws, which serve as both chain connectors and bucket fixings. The nuts on the U-shaped screws must be tightened securely to prevent loosening.

After the chain and buckets are installed, proper tension should be applied. Lubricate the gearbox and bearing seats with the appropriate amount of oil and grease. The gearbox should be lubricated with industrial gear oil, while the bearing seat can be lubricated with either calcium or sodium-based grease.

Following the installation, the machine should undergo a trial run. Before this, a no-load test run should be conducted to ensure smooth operation. The no-load test should be conducted for a minimum of 2 hours without reversing and without any collisions. The bearings should not exceed a temperature rise of 25°C, and the gearbox should not exceed 30°C. If these conditions are met, a load test can be performed. During the load test, material should be fed uniformly to prevent blockage and ensure smooth operation.

1. The bucket elevator should only be started when it is empty. Before stopping, all materials should be emptied from the buckets to prevent overloading when restarting.
2. Reversing the machine is not allowed, as it can lead to chain derailment. Troubleshooting derailment can be complicated and time-consuming.
3. Ensure uniform feeding to prevent sudden increases in the material flow rate. The feeding rate should not exceed the conveying capacity of the elevator to avoid serious blockages at the bottom and potential “stuck” incidents.
4. Regularly and adequately add lubricating oil.
5. Damaged or severely worn chains and buckets should be replaced promptly.

Safety Regulations

1. The bucket elevator must be maintained and managed by designated personnel. The keys to the power switch box should be under the control of a specified individual.
2. The elevator must be equipped with a safety limiter and a travel limit switch. The limiter should stop the pulley automatically when it is within 300mm of the drum or pulley.
3. There must be a maximum load sign indicating that the weight during lifting or lowering should not exceed 1 ton.
4. After powering on, check the action of the safety limiter, travel limit switch, interlock switch, and other safety devices to ensure they are functioning properly and conduct a test lift.
5. Before lifting or lowering, sound a warning signal to indicate that the operation is about to begin.
It is strictly prohibited for personnel to ride on the elevator up or down.
6. After completing work, lower the elevator bucket to the ground, then cut off the power and secure the upper and lower guardrail doors.
7. Keep the surrounding environment of the elevator clean and tidy at all times.

1. Slipping of the Bucket Belt

Problem: The bucket elevator operates by utilizing the friction torque between the bucket belt and the head wheel drive shaft. If the tension in the bucket belt is insufficient, it can lead to slipping. Immediate shutdown is required to adjust the tensioning device to tighten the bucket belt. If the tensioning device cannot fully tighten the belt, this indicates that the travel distance of the device is too short and needs readjustment.

Solution: Detach the bucket belt joint, adjust the tensioning device on the bottom wheel to its highest position, place the bucket belt through the head and bottom wheels, and connect the ends. Ensure that the belt is in a state of tension but not fully tightened. Then, completely tighten the tensioning device, ensuring that the unused travel of the tension screw is not less than 50% of the full travel.

2. Overloading of the Elevator

Problem: When the bucket elevator is overloaded, the resistance torque increases, causing the bucket belt to slip. This can be resolved by reducing the feed rate of the material and aiming for uniform feeding. If adjusting the feed rate does not alleviate the slipping, it may be due to a buildup of material inside the machine seat or an obstruction preventing the buckets from moving properly. In such cases, a shutdown and inspection are necessary to clear the blockage.

Solution: Ensure that the material is fed evenly and monitor for obstructions in the machine seat or blocks in the buckets.

3. Smooth Surfaces on Head Wheel Drive Shaft and Bucket Belt

Problem: Over time, the surfaces of the head wheel drive shaft and bucket belt may become too smooth, reducing the friction between them and causing the bucket belt to slip. To solve this, a layer of adhesive can be applied to increase the friction between the surfaces.

Solution: Apply a rubber layer or other friction-enhancing material to the drive shaft and bucket belt.

4. Stiff Bearings on the Head and Bottom Wheels

Problem: If the bearings on the head and bottom wheels are stiff, the resistance torque increases, resulting in slipping of the bucket belt. This requires disassembly, cleaning, and lubrication of the bearings or replacement if necessary.

Solution: Regularly inspect and service the bearings, lubricate as needed, or replace if damaged.

5. Misalignment of Head and Bottom Wheel Shafts

Problem: The incorrect installation of the head and bottom wheel shafts can cause misalignment, leading to issues such as the bucket belt running off track. This misalignment can also lead to collisions between the buckets and the casing or damage to the belt.

Solution: Ensure that the head and bottom wheel shafts are installed correctly with the drive wheels aligned on the same vertical plane and positioned horizontally. The vertical deviation should not exceed 2mm at a 1000mm height, with cumulative deviations not exceeding 8mm.

6. Poorly Aligned Bucket Belt Joints

Problem: If the bucket belt joints are not correctly aligned, the edges of the belt do not lie on the same straight line, causing uneven tension and subsequent misalignment of the belt.

Solution: Adjust and realign the joints, ensuring the edges are in a straight line, which prevents the belt from moving off track.

7. Excessive Return of Material (Spillage)

Problem: Excessive return of material indicates that not all material is being discharged properly from the elevator, resulting in reduced efficiency and increased wear and tear.

Solution: Adjust the speed of the bucket elevator according to the type of material being conveyed. Ensure that the unloading flap or outlet is correctly positioned to prevent spillage and make adjustments as necessary.

8. Bucket Falling Off

Problem: Buckets falling off from the bucket belt can occur due to overfeeding, low positioning of the feed inlet, or weak material strength of the buckets.

Solution: Ensure the feed inlet is above the center line of the bottom wheel, adjust the feed rate to prevent overloading, and use materials with sufficient strength for the buckets. Regularly check the integrity of the bucket connections to avoid loosening or detachment.

9. Belt Tears

Problem: Tears in the bucket belt are often caused by misalignment, bucket detachment, or sharp objects in the material.

Solution: Conduct a thorough inspection to identify the cause of the tear, such as foreign objects in the material, and take preventive measures like installing steel wire mesh or magnets at the feed inlet to filter out larger debris. Regularly monitor belt tension and alignment to prevent excessive wear.