Vertical Sugar mill rollers are large, metal, cylindrical parts. Sugar Mill rollers crush sugarcane and extract juice from them.
Vertical Sugar mill consists of three or four rollers arranged vertically. They rotate in opposite directions and crush the sugarcane. The rollers apply the force when the cane passes through the “nip” between rotating rollers. Finally, they collect the juice and the bagasse separately.
This is how a typical vertical sugar mill roller looks like.
2. Types of Sugar Mill Rollers
2.1 Vertical Sugar Mill Rollers
Explanation of Vertical Sugar Mill Rollers
Mills combine two or three rollers and mount them vertically. They move in the opposite direction and crush the sugarcane when the cane passes through the nip. This way the sugar mill rollers crush the cane and extract the juice. The image below shows this concept.
Differences Between Vertical Sugar Mill Rollers and Horizontal Sugar Mill Rollers
Feature | Vertical Sugar Mill Rollers | Horizontal Sugar Mill Rollers |
Roller Orientation | They have vertical axis of rotation. | They have horizontal axis of rotation |
Cane Feed | The machine feeds the cane from the top. The force is gravity-assisted. | The machine feeds the cane from horizontal side. It is assisted by moving along a conveyor belt, and goes into the rollers horizontally. |
Juice Flow | Simply drains downwards. | Drains downwards and forwards into juice pans. |
Number of Mills | Typically single-mill units. | Sugarcane mills arrange them in tandems. It allows continuous extraction. |
Imbibition | Not very feasible. | It has become an industry standard to maximize juice extraction. |
Extraction Eff. | Low | High |
Capacity | Very low. | Very high. |
Bagasse Disposal | Labor removes the bagasse manually. | Conveyor belts remove the bagasse. |
Safety | Highly hazardous for the operators. | Relatively safer mechanized operation. |
Complexity | Simple construction. | Complex design, hydraulic controls, and automated feeding systems. |
Modern Relevance | You find them in small operations. | It has become an industry standard for all large, commercial sugar mills. |
2.2 High Precision Sugar Mill Roller
Role of Precision in the Sugar Mill Roller
Precision means high accuracy. Similarly precision in sugar mill rollers provide perfect squeeze gap, minimized runout, and dynamic balance. All these lead to improved operation, higher efficiency and better juice extraction.
This is how a high precision vertical sugar mill roller looks like:
These high precision sugar mill rollers have the following roles that makes it efficient.
Perfect squeeze gap:
The gap between the rollers must be of uniform distance throughout. All the cane will not be squeezed if the gap is wide at one spot and tight in the other spot. High precision sugar mill rollers ensures the gap is uniform throughout.
Minimised Runout
The rollers must spin perfectly round. If a roller wobbles, it means the gap changes as it spins. This leads to uneven squeezing. This also causes shaking and damage to the mill over time. Precision makes them spin smoothly.
Dynamic Balance
When the rollers spin very fast, they need to balance perfectly. If they don’t balance, they will vibrate a lot. These vibrations can be disastrous. These can lead to wearing out parts like bearings and even cracking the strong metal frame of the mill. High precision sugar mill rollers ensure balance, preventing these costly vibrations.
Rough, Grippy Surface
The roller surface needs to be rough, to grab the cane effectively. We can increase roughness by welding special patterns onto the roller. The cane will lose grip and slip if the rollers lack roughness. High precision sugar mill rollers ensure they apply this grippy surface uniformly, so the rollers always pull the cane in strongly
Perfect Grooves:
The rollers have special patterns cut into their surface. These grooves do three important tasks. They assist the rollers grab the cane, make channels for the juice to escape, and help break up the cane fibers.
Benefits of high precision:
Maximized Juice Extraction: High precision sugar mill rollers extract 94-97% juice from sugarcane. This is efficient as compared to vertical roller mills, which extracts only 55-65% of juice.
Reduced Power Consumption: High precision sugar mill rollers reduce energy consumption significantly. Studies suggest that they save 30-45% energy compared to typical rollers.
Increased Mill Capacity/Throughput: Continuous feeding ensures more sugarcane is processed per unit time. This prevents chocks and delays.
Extended Roller and Component Lifespan: Improved sugar mill rollers can reduce the wear and tear of the parts. This increases its life by at least three times as compared to typical rollers.
Improved Bagasse Quality: Modern mills can save over 13% of bagasse as compared to old style operations. Furthermore, higher juice extraction results in a drier bagasse collected. This dryness improves its calorific value by 10-20%, which makes it an efficient fuel.
Heavy Duty Sugar Mill Roller
Features of Heavy Duty Sugar Mill Rollers
Heavy Duty Sugar Mill Rollers are used for juice extraction. They focus on the machine’s strength, durability, high pressures capacities. Moreover, they are composed of strong metal.
These have the following key features:
Material Composition: Heavy duty rollers are constructed from strong iron alloys. These rollers prevent fracturing and deformation due to high hydraulic pressures. Furthermore they can withstand extreme torsional and bending stresses.
Greater Wall Thickness and Weight: Heavy Duty Mill Rollers have thicker shells and greater mass. This provides greater inertia for stable crushing of the sugarcane.
Optimized Stress Distribution and Design: Modern computers are attached to heavy duty mill rollers to detect weak spots of the machine. This helps them to remove weak areas where the roller might break. It prevents failures.
Applications in Large-Scale Mills:
Sugar Mills use heavy duty rollers to extract juice in 3 main steps.
- First Squeeze: Mills place Heavy Rollers in the very first and second squeezing machines. Sugarcane first enters these rollers and is crushed to extract the maximum amount of the juice.
The diagram below shows the first squeeze.
- Subsequent Crushing Mills: After the first few squeezes, the sugarcane residue moves through third, fourth, and even more squeezing machines. These rollers need to apply even more crushing force to get out the last bits of juice.
The picture below represents a series of working rollers.
- Feeder Rollers: they make sure that the cane feeds smoothly: There are special feeder rollers attached before the squeezing rollers. These rollers don’t do the main juice squeezing, but they push and pack the cane very tightly into the first main squeezing rollers.
The picture below shows the working of feeder rollers.
3. Parts of Vertical Sugar Mill Rollers
3.1 Roller Grooving
Importance of Grooved Rollers in Vertical Sugar Mill Rollers.
Roller grooving are special patterns of ridges that are cut onto the roller’s surface. Roller groovings improve the grip to push sugarcane into the rollers without them slipping. This improves juice extraction and efficiency.
This is how the patterns on the surface of the roller looks like.
How Grooving Improves Crushing Efficiency of Vertical Sugar Mill Rollers.
- Better Cane Grip & Feeding: Grooves help to improve the roller’s grip and push the sugarcane into the nip.
- Juice Drainage: The grooves provide channels for extracted juice. This helps to collect the juice and prevent juice reabsorption into the bagasse.
- Pressure Distribution: Groove patterns distribute the crushing pressure uniformly across the rollers. This improves overall juice extraction.
3.2 Roller Shaft
Function of the Roller Shaft in Vertical Sugar Mill Rollers.
The roller shaft is the central component that provides rotational power (torque) from the mill drive to the roller shell. It then enables the crushing action. It also absorbs hydraulic loads exerted during cane compression.
Design and Material Considerations
Material Choice: Roller shafts are made of strong, medium carbon alloy steels. This helps superior toughness, high extractions, and fatigue resistance under extreme loads.
Better Geometry: Rollers are designed using Finite Element Analysis. It helps to establish accurate diameters and lengths. This improves uniform pressure distributions to the rollers and prevents failure.
Robust Shell-to-Shaft Connection: Shell to shaft connection makes sure the roller and its shaft spin together. This ensures that all crushing power is used to push all the cane into the rollers without any slipping.
Precision Bearing Journals: Bearings are attached to the ends of the shaft. These minimize friction and wear, and ensure smooth rotation.
Durability Focus: The overall design aims for longevity and prevents fatigue failures.
3.3 Mill Roller Shaft Design
Design Considerations for Mill Roller Shafts:
How Design Affects Performance: A superior shaft design directly translates to:
- Reliability: It prevents shaft failure, reducing costly, unplanned downtime.
- Efficiency: It ensures that full torque power transmits to the roller shell. It maximizes crushing power.
- Lifespan: low vibrations and smooth operation means lower wear and tear of the machine. It improves the overall working lifetime to 3 times as compared to conventional rollers.
3.4 Cast Iron Rollers
Why Cast Iron is Ideal for Mill Rollers:
Iron cast rollers are made of iron casting primarily due to its superior capabilities, wear resistance and strength.
- Superior Castability: melted cast iron can easily fill up any detailed mold. It allows you to create the roller’s exact shape.
- Effective Wear Resistance: The hardness and strength of the iron cast allows the iron cast roller to prevent continuous wear.
- Proven Weldability for Hardfacing: cast iron alloys show excellent weldability properties. This critical attribute allows repeated, high-quality operations of the rollers. It makes it wear-resistant and maintains surface roughness and longevity.
Durability and Cost Benefits:
Cast iron for mill rollers provide long-term durability and economic advantages:
Increased Lifespan: Specialized cast iron rollers provide an operational lifespan of almost 5-7 crushing seasons. Sometimes it can also reach up to 10 seasons before requiring full replacement. This reduces frequent capital replacement expenditures.
Cost-Effectiveness: The manufacturing cost of a cast iron roller shell can be 30-50% less as compared to high-alloy forged steel components. This means a lot of capital cost is reduced.
Enhanced Repairability: Iron cast rollers have the potential to be repaired rather than to be replaced. This reduces the lifetime cost of ownership by up to 40-50% compared to frequent full roller replacements.
3.5 Grooved Shells
3.5 What are Grooved Shells?
A grooved shell is the outer, cylindrical body of a sugar mill roller. It has various patterns of ridges and channels (grooves) that aid the sugarcane gripping and crushing. This way the juice is extracted from the bagasse.
How Grooved Shells Help in Efficient Crushing:
- Cane Inducement and Positive Feed: The rough design, and the helix angle of the grooves helps to push the sugarcane into the nip. This prevents cane from slippage and provides a continuous, controlled feed. Thus it improves the throughput and efficiency.
- Enhanced Juice Expression and Drainage: The grooves provide special channels for the collection of the juice. This function prevents juice reabsorption, particularly on the discharge side of the rollers. This improves the overall efficiency in juice extraction.
- Bagasse Blanket Stability: After leaving the rollers,the bagasse maintains a stable, uniform, and dense blanket. This is just due to the rough surface of the grooved shells. This prevents unwanted channeling or uneven material flow.
5. Capacity and Efficiency
5.1 Cane Crushing Capacity
Factors Influencing Crushing Capacity:
Cane crushing capacity refers to the amount of sugarcane juice a mill can extract per unit time. It is measured in Tons Cane per Hour or Tons Cane per Day.
Modern vertical rollers can extract up to 500 tons of cane per hour or even more. This capacity depends on the number and size of its rollers, the power of its drives and the cane preparation.
- Rollers Length: Larger rollers provide a larger surface area for the cane crushing. This increases the juice extracted per unit time.
- Number of Rollers: Higher the number of rollers, higher is the output. Mills typically employ a series of rollers. Each roller contributes to extracting more juice.
- Grooving and Surface Treatment: advanced grooving surfaces provide better gripping, crushing and improved channels for juice collection.
- Cane Preparation: The sugarcane preparations before entering the rollers significantly impacts capacity and extraction. Mills cut the cane into pieces before squeezing that improves the juice collection.
- Roller Gaps: It is very important to keep an accurate gap between the rollers. Accurate gap is essential for correct pressure applied on the cane for maximum juice extraction.
- Mill Drives and Power: The mill’s power and torque influence the crushing force. Mills should transmit maximum power to rollers for efficient sugarcane crushing.
How Vertical Sugar Mill Rollers Improve Capacity and Efficiency
Vertical sugar Mill rollers improve the operation capacities due to the following reasons:
- Gravity-Assisted Feeding: cane is vertically feeded from the top of the machine. It uses the natural gravity forces. So, it reduces the need for feeding mechanisms and reduces the energy consumption by 20-25%.
- Prevents cane choking: Vertical structures prevent the cane getting struck in the rollers. It decreases the feed chokes by up to 15-20%. This leads to higher output.
- Reduced Reabsorption: The extracted juice flows downwards directly due to the mill’s vertical structure. . This prevents reabsorption of juice into the bagasses by 1-3%. This overcomes a common challenge in conventional horizontal mills.
- Reduced Space Requirements: The vertical design reduces the floor space required. A vertical mill demands 30-50% less factory footprint than a multi-tandem horizontal mill
- Efficient Pressure Distribution: Vertical rollers allow an even distribution of crushing pressure. This has seen a 5-10% improvement in the grinding processes.
5.2 Mill Used for Crushing Sugar Cane
Different Mills for Cane Crushing
Large scaled sugar mills employ roller mills arranged in a series and in order. The main types are defined by the number and arrangement of rollers:
Two-Roller Mills:
Description: It consists of two horizontally opposed rollers which rotate in opposite directions. The cane passes through the nit and is crushed.
They are used for small scale operations or the initial stage of precrushing in large mills.
Efficiency: 50 TO 70% of the juice is extracted by this process.
Limitations: it has high re-absorption chances and has limited capacity.
Three-Roller Mills:
Description: They consist of a triangular arrangement of three rollers: a top roller, a feed roller, and a discharge roller. Initially, cane is fed between the feed and top rollers. It then passes between the top and discharge rollers for a second compression.
Efficiency: It can extract 80-97% of juice in the sugarcane. Still the effectiveness depends on the number of mills operating in the tandem.
Advantages: It has high reliability, high capacity and a strong construction. Furthermore, juice is extracted in multiple stages. Thus, the output increases.
Four-Roller Mills:
Description: These mills add an extra roller to the three-roller setup. The “fourth roller” often called “pressure feeder” works with the feed roller to pre-compress the cane.
Application: It improves cane feeding, increases capacity, and increases efficiency.
Efficiency: Studies show that four roller mills increases crushing efficiency up to 64% in single units.
Conclusion
Vertical sugar mill rollers provide high precision, maximized juice extraction with reduced energy consumption. Modern advancements in roller designs include cast iron, and multi-roller configurations. This has improved capacity, durability, and safety, leading to efficient juice extraction.