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Home > Articles by: Cement Innovator

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Revolutionizing Cement Transfer: The Air Chain Conveyor Solution

Introduction

Company S operates six Φ18×35 cement silos. As shown in the diagram, there are air transport chutes under silos 1, 2, 3, and 4, 5, 6 to convey materials to the outside elevator. In August 2020, the company planned to increase its cement varieties. This required transferring cement from silo 4 to the chute under silos 1, 2, and 3. Due to the high transfer volume (300 m³/h) and the small height difference between the feed and discharge points, installing an air transport chute was not feasible. Other equipment options were either energy-intensive, prone to wear, or incompatible, making the selection and design process difficult.At this point, the storage and transportation department learned about Darko's air chain conveyor. They contacted Darko's technical team. After a site survey and extensive discussions, they finalized the technical plan to use the air chain conveyor. The order was placed at the end of 2020. Due to tight production schedules, installation only started in July 2021 and was completed within the month. The system performed exceptionally well and met all expectations. Here are the key technical features of the project:

Air Chain Conveyor Drawing

1. Guaranteed Process Height

The air chain conveyor can transport materials horizontally. The design moves material from silo 4 to the chute under silo 2. This setup involves an approximately 135° bend. To save on height, we implemented two measures:

 

First, we changed the feed method at the inlet of the first air chain conveyor from the usual top feed to a side feed. This adjustment allows the material to drop directly from the silo's discharge valve to the side of the equipment, saving about 500 mm of space.

 

Second, at the junction of the two air chain conveyors, we switched from the typical vertical overlap to a horizontal overlap. The discharge from the first conveyor feeds into the side of the second conveyor. Due to the 135° angle, this horizontal overlap created a triangular area where material could accumulate, potentially hindering transport. To prevent material buildup, we installed an air cushion at the junction, supplied by a common Roots blower. This significantly reduced resistance, ensuring smooth material flow. As a result, this design saved about 1000 mm in process height, allowing material from silo 4 to enter the chute under silo 2 smoothly.

 

2. Rational Equipment Selection

For a transfer volume of 300 m³/h, a simple layout with a single device and minimal angles could typically use the FUK630 model. However, given the current process requirements, particularly the 135° junction and end discharge, we opted for the FUK800. After several months of operation, we found that this model met the 300 m³/h requirement and handled sudden increases in pressure within the silo without causing blockages.

 

Air chain conveyor real shooting scene

3. Low Energy Consumption

The specifications for the two air chain conveyors are as follows: the first is FUK800×13.5 meters with a power of 5.5 kW, and the second is FUK800×31.7 meters with a power of 11 kW. Both conveyors share a single 18.5 kW Roots blower for air supply, resulting in a total transport distance of 45.2 meters and total power consumption of 35 kW. This is slightly higher than the FUK630 (30 kW) but significantly lower than traditional chain conveyors (75–90 kW), achieving over 50% energy savings. Additionally, the slightly lower chain speed enhances the lifespan of the conveyor while maintaining complete shell sealing, meeting all environmental standards.

 

Conclusion

While selecting high-performance equipment is essential, the design of the process based on equipment characteristics and site conditions is equally important. The success of the technical solutions depends on how well the equipment features align with the specific situation. Many users prioritize this aspect. Design experience is also invaluable in this process, so it is crucial to choose not only the right equipment but also an experienced manufacturer.

If you are interested in our technical solutions or need further information, please feel free to contact us. We are happy to help!

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Optimizing Roll Press Performance in Cement Grinding

Since the commissioning in May 2007, Company A's cement pre-grinding system has faced frequent failures with the roll press. These issues include low and unstable working pressure on both sides, improper adjustment of the material distribution valve, large particle size of the material exiting the roll press, low hourly output, high grinding energy consumption, and poor overall economic efficiency. This article will share our experiences and improvement measures in controlling the roll press.

 

Problem Analysis and Solutions

1. Causes and Adjustments for Unstable Pressure

Material enters the roll press between the moving and fixed rollers through the upper feeding chute. We found that the material adjusting plate on the moving roller side extended toward the fixed roller. This caused the discharge point to shift toward the fixed roller. As a result, there was too much material on the fixed roller side and almost none on the moving roller side. This uneven distribution led to unstable pressure and ultimately resulted in large particle sizes in the output.

 

To solve this problem, in August 2010, Darko adjusted the material adjusting plate on the moving roller side. We moved its position from the fixed roller side to the outside of the moving roller. We also changed its angle from 45° to 60°. Additionally, we adjusted the initial roller gap to 10 mm. This allowed the material to flow properly between the rollers and distribute evenly, thereby controlling pressure fluctuations.

 

Drawing of moving roller side stopper adjustment plate

2. Causes and Adjustments for Low Working Pressure

After careful observation of the roll press and hydraulic system, we found that the initial pressure on both sides of the system was 6.0 MPa. The equipment could only start when the pressure was loaded to 5.5 to 6.5 MPa. The operators typically increased the pressure to 6.0 MPa and then stopped. Due to the limitations of the initial roller gap, the oil pressure in the hydraulic cylinder was insufficient at 6.0 MPa. Even if the roller gap increased, the pressure could not reach the working pressure of 8.2 MPa.

 

We realized that the initial pressure had a significant impact on the working pressure. Therefore, we adjusted the initial pressure to 6.5 MPa while stabilizing the material flow at the inlet. After this adjustment, the working pressure on both sides increased from 7.4 to 7.8 MPa to 8.2 to 8.6 MPa, resulting in a noticeable reduction in particle size.

3. Adjusting the Material Distribution Valve

During the grinding process, the material forms a cake and discharges from the lower part between the two rollers. With sufficient feeding, the material is effectively pressed. However, the pressing effect on the edge material is not as good as that on the center material. The role of the material distribution valve is to separate well-pressed material from poorly pressed material.

 

We mistakenly believed that a smaller opening of the distribution valve was better and adjusted it to 20%. As a result, the finished product contained coarse material around 10 mm. Upon inspecting the side door of the roll press, we found significant material buildup in the edge chute, which hindered smooth flow. After making further adjustments, we discovered that setting the distribution valve opening to 23% eliminated the material buildup, allowing smooth entry into the return belt.

 

Conclusion

Through these measures, we successfully reduced the average particle size of the clinker from the roll press from 3.81 mm to 1.54 mm. The crushing ratio improved from 4.09 to 10.10. The appearance of the ground material became powdery, and most particles could be easily crushed by hand. Additionally, the hourly output of the ball mill increased by 13.1%, and the system's grinding energy consumption decreased by 16.6%. These improvements significantly enhanced the system's economic efficiency and operational stability. If you face similar issues, please feel free to contact us. We are happy to help!

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How to choose an efficient pulse bag dust collector?

When selecting a pulse bag dust collector, you need to consider multiple factors. This ensures the chosen equipment meets actual production needs and achieves efficient, stable, and economical operation. Here are some key selection steps and important notes:

1. Clarify Working Conditions

1.1 Handling Airflow

Determine the airflow that the dust collector needs to handle. This is the foundation for selection. Airflow directly impacts the specifications and performance of the dust collector. Consider the size of the hood, the distance from the dust emission point, and the filtering wind speed to accurately estimate the required airflow.

 

1.2 Dust Characteristics

Understand the characteristics of the dust, such as particle size, concentration, temperature, humidity, and viscosity. Choose suitable filter materials based on the dust properties, such as polyester, aramid, or fiberglass. For high temperature, high humidity, or highly corrosive dust, select materials that are heat-resistant and corrosion-resistant.

 

2. Determine Dust Removal Efficiency and Emission Standards

2.1 Dust Removal Efficiency

Select a dust collector model that can meet the required efficiency for production. Pulse bag dust collectors typically achieve over 99% efficiency, but this depends on dust characteristics and equipment configuration.

 

2.2 Emission Standards

Clarify the emission standards for the dust collector to ensure compliance with national or local environmental regulations. Set efficiency goals based on these standards and select the appropriate filtering efficiency level.

 

3. Consider Cleaning Methods and Filter Area

3.1 Cleaning Method

Pulse jet cleaning is the most common method for pulse bag dust collectors. Compressed air is injected into the filter bag through a pulse valve for cleaning. Ensure the reliability of the cleaning system and set a reasonable cleaning cycle for maintenance convenience.

 

3.2 Filter Area

Calculate the required filter area based on the handling airflow and filtering wind speed. The size of the filter area directly affects the dust collector's efficiency and investment costs.

 

Two pictures of industrial equipment showing the structure and application of pulse bag dust collector

4. Equipment Layout and Installation

4.1 Installation Location

Determine the installation location and space size for the dust collector based on the layout of the production workshop and equipment placement. Consider the inlet and outlet positions and duct layout to minimize airflow resistance and leakage.

 

4.2 Duct Layout

Design the inlet and outlet positions and duct layout to ensure smooth airflow. If necessary, set up air valves and adjustment devices to control airflow distribution and volume.

 

5. Economic Evaluation

5.1 Cost-Effectiveness

Evaluate the costs of the dust collector, including equipment, installation, operation, and maintenance. Choose a dust collector with high cost-effectiveness to reduce investment costs. Also, assess energy consumption and filter replacement cycles to ensure long-term economic operation.

 

5.2 Energy-Saving Measures

Consider implementing energy-saving measures and efficient cleaning systems to lower operating costs.

 

6. Other Considerations

6.1 Safety Measures

For operations involving toxic or explosive materials, select a dust collector with appropriate safety features. Ensure that the dust collector meets relevant standards for explosion-proof and toxic prevention measures.

 

6.2 Maintenance Convenience

Choose a dust collector that is easy to maintain to reduce maintenance costs and improve equipment reliability. Consider the convenience of filter bag replacement and cleaning system maintenance.

 

Conclusion

In summary, selecting a pulse bag dust collector is a comprehensive process. You must consider working conditions, dust removal efficiency, cleaning methods, equipment layout and installation, economic evaluation, and other important factors. A well-structured selection process can ensure that the dust collector operates efficiently, stably, and economically in practical applications. Choosing the right pulse bag dust collector can enhance production efficiency and effectively protect the environment.For more information or assistance, please feel free to contact us. We look forward to providing you with professional solutions!

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Boiler Baghouse Dust Collector Selection Guide

Boiler baghouse dust collector is key industrial equipment used in various boiler systems. Their main function is to filter and capture particulate matter from flue gases. This process effectively removes dust and improves emission quality, enhancing air quality and aiding environmental protection.

Considerations for Selecting a Boiler Baghouse Dust Collector

When choosing a boiler baghouse dust collector, several factors must be considered to ensure optimal performance and compliance with environmental regulations.

1. Understanding Boiler Specifications

First, assess the boiler's combustion method and rated power. For example, for coal-fired boilers, it is important to understand the type of coal, combustion method, and flue gas volume. This information helps in selecting the right dust collector.

 

2. Following Environmental Policies

Next, be aware of local environmental policies and emission standards. Ensure that the selected dust collector meets these requirements. In areas with strict regulations, you may need a higher-performance dust collector to minimize environmental impact.

 

3. Analyzing Dust Characteristics

Additionally, understanding the physical and chemical properties of the dust is crucial. This knowledge helps in determining the right filter materials and cleaning methods. For flammable or explosive dust, choose a dust collector with explosion-proof features to ensure safety.

 

4. Considering the Process Flow

It is also important to understand the entire process flow. Determine the best location to install the dust collector for optimal effectiveness. In some processes, placing the dust collector before the flue gas discharge can reduce impacts on downstream equipment.

 

5. Impact of Climate Conditions

Moreover, consider local climate conditions such as temperature, humidity, and wind. Choose suitable materials and structures for the dust collector. In high-temperature and high-humidity areas, select collectors with waterproof and corrosion-resistant features to ensure stability and long-term performance.

 

6. Meeting Special Environmental Needs

Finally, for special situations like high temperature, high humidity, or corrosive environments, choose dust collectors with special functions. In corrosive environments, select collectors with anti-corrosion features to extend equipment lifespan.

 

The Boiler Bag Filter is placed in an industrial space, showcasing its importance in maintaining air quality by capturing boiler emissions.

Working Principle of Boiler Baghouse Dust Collectors

Boiler bag filters use the bag filtering principle to capture particulate matter from flue gases, purifying the gas and protecting the environment. After pre-treatment, flue gas enters the dust collector. The gas passes through the bag filter layer, where particles are trapped on the bag surface. The purified flue gas then exits through the outlet.

 

The bags of the dust collectors are made from high-temperature, abrasion-resistant materials. They can withstand the impact and wear of high-temperature flue gases. Additionally, the collectors use a compartmentalized stop-flow pulse jet cleaning method. This method provides long cleaning cycles and low energy consumption.

 

Furthermore, the dust collectors use a top-bag extraction method. During bag replacement, the framework can be easily removed, facilitating operation. The inlet and outlet passages are compactly arranged, leading to low airflow resistance. The equipment is equipped with insulation to prevent low temperatures from causing gas condensation.

 

Conclusion

In summary, when selecting a boiler baghouse dust collector, consider various factors to ensure the equipment's performance and reliability. Make sure it meets environmental requirements. With the right selection and configuration, boiler bag filters can effectively improve emission quality and protect our environment.

Darko looks forward to providing you with professional solutions for boiler baghouse dust collectors! For more information or inquiries, please feel free to contact us!

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Solution to Improve Bulk Steel Silo Loading Speed

Recently, a stone powder company in Shanxi, China, contacted us. They reported that after installing bulk loading equipment on their stone powder steel silo, their loading speed had significantly decreased. Sometimes, it took seven to eight hours to load a single truck, which severely limited their production capacity.

 

Before reaching out to us, this company had tried to communicate with other bulk machine manufacturers. They implemented several measures, such as adding a vibrator to the exterior of the silo cone and installing air supply nozzles and tanks inside. However, these efforts did not yield satisfactory results. Therefore, they requested Darko to provide a solution and sent photos and videos of the on-site equipment.

 

We took their feedback seriously. After carefully analyzing the provided information, we developed a targeted solution. Once we sent our quote, the company quickly signed the contract and made the payment to expedite the order.

 

After shipping the equipment, Darko arranged for technicians to go to the site for installation guidance. Due to limited space and a shortage of installation personnel, the construction took longer than expected. Our technicians stayed on-site for two days to ensure everything was installed correctly before returning.

 

About five days after the modifications were completed, the customer called to express their gratitude. They reported that the loading time for a truck of stone powder had now been reduced to around ten minutes, and they were very satisfied with the results.

 

Key Modifications for the Bulk Steel Silo

1.Installation of Air Supply Boxes:

We installed air supply boxes in suitable positions inside the silo cone, implementing zoned air supply to ensure that the powder material could be evenly fluidized.

 

2.Change of Air Source:

We replaced the original high-pressure air with a Roots blower. Although high-pressure air provided sufficient pressure, its airflow was too small to effectively fluidize the powder material. Additionally, high-pressure air contained moisture, which could cause the powder to clump and block the air supply layer. In contrast, the Roots blower provided a larger airflow and appropriate pressure, and it contained no moisture, making it ideal for this application.

 

3.Shortening of Vertical Pipe Length:

We shortened the vertical pipe length between the cone and the lower discharge gate. The original long vertical pipe could easily form dead zones under prolonged material pressure, which affected the normal flow of materials.

 

Key Modifications for the Bulk Steel Silo

This modification not only improved the customer's loading efficiency but also demonstrated our commitment to addressing customer issues and providing solutions. If you face similar challenges or wish to enhance your production efficiency, please feel free to contact us! We look forward to providing you with professional solutions.

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Optimizing Vertical Grinding Efficiency

In modern industry, the efficiency of vertical grinding systems directly impacts production costs and energy consumption. Here are several effective strategies to reduce power consumption, minimize system resistance, and optimize daily operations.

1. Reduce Main Motor Current

Use mechanical lifting for material handling to lower power consumption more effectively than air lifting. This method reduces the internal circulation load of the vertical mill, enhances grinding efficiency, and decreases equipment resistance. Most vertical mills today have external circulation elevators. However, you need to find the optimal balance between external circulation and system output through ongoing exploration during production.

 

Theoretically, a lower material layer will yield a significantly lower motor current than a higher layer. Therefore, controlling the material layer thickness is crucial. Adjust this thickness using the dam ring. By optimizing the dam ring height, you can achieve a more appropriate thickness for the material layer within the mill. A reduced layer thickness increases the effective force within a unit volume of material, lowers the hydraulic cylinder’s working pressure, and reduces the pressure difference in the mill, leading to lower main motor current.

 

When selecting equipment and designing processes, consider the appropriate ratio of external circulation and the suitable air velocity of the nozzle ring. Ensure that the capacity of the external circulation elevator matches the system requirements. Additionally, controlling the air volume is essential to prevent excessive fine powders during discharge.

 

2. Lower System Resistance

The energy consumed by the circulating fan is closely linked to wind pressure, airflow, and fan efficiency. When system resistance is high, fan efficiency decreases, leading to increased current draw. Therefore, reducing system resistance is essential for enhancing fan efficiency and lowering current consumption.

 

Identify the primary sources of resistance by installing pressure detection devices at key locations: the hot air inlet, classifier outlet, cyclone outlet, and nozzle ring outlet. Comparing pressure differentials at these locations will help pinpoint the main sources of resistance.

3. Address System Air Leaks

Air leaks in the vertical mill system primarily occur in the mill and the dust collector. Ensure that the leak rate remains below 8%. Key leak sources include lock air devices at the mill inlet, roller seals, connection flanges, and expansion joints. In dust collectors, significant leaks often occur at the casing cover and connection flanges.

 

Air leaks increase current consumption by the fan, escalate energy costs, and potentially impact the mill’s output. Therefore, timely management of air leaks is vital for improving system efficiency.

4. Daily Operational Insights

Control the particle size of incoming material, typically within 3% to 5% of the roller diameter. After wear occurs on the roller sleeves and grinding table liners, adjust the gap between the roller and the grinding table. Regularly check the accumulator pressure, maintaining it within 60% to 70% of the roller's working pressure.

 

Higher grinding pressure is not always beneficial. If the output reaches a critical value, further increases in motor current will worsen energy consumption and jeopardize safe operation. Therefore, determine the optimal pressure based on actual production conditions. Additionally, maintain the outlet gas temperature around 85°C to stabilize grinding and classification efficiency.

Two combined scenes of a vertical roller mill, showcasing its operational setup and components in a cement production environment.

5. Central Control Operation Considerations

Grinding Pressure: Aim for a grinding pressure that does not exceed a certain critical value. Further increases can elevate the main motor current and energy consumption. Develop a curve that correlates pressure with output to optimize this aspect.


Outlet Gas Temperature: Keep the outlet gas temperature stable at around 85°C. Deviations can significantly impact grinding and classification efficiency.


Valve Settings: Open all valves, including the inlet air valve, circulation air valve, fan outlet valve, and bypass air valve, to minimize system resistance. To check if the bypass valve should remain open, close it and observe the inlet negative pressure. If it increases, re-open the bypass valve.


Negative Pressure Control: Maintain the negative pressure at the tail end of the dust collector within -500Pa. This pressure affects the volume of supplementary air entering the mill and reduces the current of the exhaust fan. If the negative pressure does not decrease, monitor the site and instruct the central control to gradually lower the tail discharge, addressing any areas where dust escapes.


Control Startup and Shutdown Times: Ensure that the time from starting the first auxiliary equipment to feeding the mill does not exceed 4 minutes. During shutdowns, if no maintenance is required, there is no need to empty the material from the mill.

By implementing these strategies, companies can significantly enhance the efficiency of their vertical grinding systems while lowering energy consumption and optimizing production processes. If you have any questions or need assistance in improving the efficiency of your vertical grinding system, please feel free to contact us. We are here to provide you with professional solutions!

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The Importance and Optimization of Powder Silos

Powder silos are crucial facilities in industrial enterprises. They are responsible for the homogenization, storage, and balancing of production materials. These silos come in different materials, capacities, and structures to meet various needs. However, many companies face issues like low storage capacity, poor homogenization, and difficulties in discharging materials. These problems often disrupt normal production.

 

Many enterprises have tried to innovate their technology, but results have been limited. The main issue lies in the design philosophy. Here are some of my thoughts on optimizing powder silos:

There is a pressure reducing cone on the upper part of the discharge port in the powder storage.

1. Design of the Discharge Cone

Many powder silos have a discharge cone above the outlet. Its purpose is to reduce the pressure of the material inside the silo, allowing for a smooth flow. However, the reality is often different. Without running the aeration discharge system, materials rarely flow out. When the system is on, excessive pressure can make control difficult.

 

I suggest removing the discharge cone and installing a high-efficiency flow valve at the outlet. This valve can monitor material pressure in real time. When pressure is too high or the material level rises, the valve closes quickly. When pressure decreases or the level falls, the valve opens. This system works like an ABS brake system in cars, controlling material flow effectively.

2. Effectiveness of Air Homogenization

Clients often ask how air homogenization equipment achieves material homogenization. In fact, the silo itself has a homogenization function. When materials enter the silo and exit, this process is self-homogenizing. The main role of homogenization equipment is to ensure normal discharge, not to mix materials forcefully. Using fans for gas mixing can harm the strength and efficiency of the silo.

 

The true purpose of air homogenization equipment is to ensure steady discharge of materials. This allows the silo's self-homogenization function to work correctly. However, after long-term use, equipment may fail due to improper operation or material characteristics. When this happens, maintenance and cleaning of the silo become necessary.

3. Optimizing Discharge Equipment

Discharge equipment includes gates, feed devices, metering devices, and conveying equipment. Using the gate and level control system mentioned earlier allows for even material discharge. I recommend using air slide conveyors as the discharge method. This design is popular due to its low investment and operating costs, good sealing, and flexible layout.

 

However, air slide conveyors have some drawbacks. They may struggle to handle hard clumps or wet materials. Therefore, I suggest using air chain conveyors. These devices combine chain conveyors with air slide conveyors. They can effectively manage clumps and moisture while lowering the height of the silo base.

 

According to well-known design firms, using air chain conveyors can save significant construction costs. Their operating costs remain relatively low. More design firms are now adopting air chain conveyors to replace traditional belt conveyors, improving powder transport efficiency and reliability.

 

Conclusion

The design and optimization of powder silos are key to enhancing industrial production efficiency. With proper design and advanced equipment, companies can improve silo functionality and achieve efficient homogenization and stable discharge of materials.

If you have any questions about silo design or related equipment, feel free to contact us. We are Darko, and we are here to provide you with professional support and solutions!

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Unlocking Efficiency with Air Slide Conveyors

Reversible conveyors primarily address the need to transport materials in both forward and reverse directions. They are widely used for short-distance transport. However, when the transport distance is longer, technical limitations reduce their applications. In 2022, Company C proposed using a reversible air slide conveyor with a capacity of 300t/h and a distance of 70 meters for the storage of mineral powder. Although Darko has some experience with short-distance reversible air slide conveyors, this is our first attempt at such a large capacity and distance with multiple discharge points. Therefore, Darko focused on the following technical issues:

Several large metal boxes are stacked together to demonstrate the structure and function of the air slide conveyor

1. Drive System Design

First, we determined that the drive should be at one end of the conveyor. This design avoids the need for two drives at both ends, simplifying operation. When one end is driving, the other end remains inactive. This setup reduces the risk of mechanical accidents and ensures smooth production.

Next, we considered placing the drive in the middle. However, we found that this would complicate the structure and increase stress on the chain, reducing its lifespan. Therefore, we decided to place the drive at one end for simplicity.

2. Chain Tensioning

Once we chose the one-end drive, chain tensioning became critical. The long transport distance requires effective tensioning. We opted for a rear tensioning system, which includes weight tensioning and screw tensioning. After evaluation, we selected a simple rear tensioning method to minimize wear and extend the lifespan of the chain and components.

3. Chain Transition Handling

After deciding on the drive and tensioning methods, we focused on handling chain transitions. Poor transition handling can lead to chain jams and affect normal operation. In reversible operation, we need to manage tensioning for both the upper and lower chains. Thus, we added a transition structure between the drive sprocket and the lower chain to ensure smooth operation.

4. Intermediate Discharge Design

The reversible air slide conveyor is installed at the top of the storage facility, primarily for material entry. Therefore, it must accommodate multiple discharge points. To prevent blockages, we installed discharge openings in the middle and ensured that the opening below the drive sprocket is always open. This design helps manage different types of materials and prevents mixing, which can affect product quality. We implemented high-pressure air blowing at the intermediate discharge points to solve this issue effectively.

Conclusion

Through the design optimization of the reversible air slide conveyor, Darko meets high capacity and long distance transport needs while ensuring stable operation and efficient material entry. We are committed to providing high-quality solutions to enhance production efficiency. For more information, please feel free to contact us.

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Brief analysis of air leakage in raw meal vertical mills

Raw material vertical mills are key grinding equipment in cement production. Their operational stability directly impacts production efficiency and product quality. However, many enterprises often face air leakage issues in the vertical mill system. This not only increases energy consumption but may also lead to equipment failures, affecting the continuity and reliability of production lines. This article analyzes the causes of air leakage in raw material vertical mills and proposes corresponding solutions.

I. Impact of Air Leakage in Vertical Mills

1.Increased Energy Consumption: Air leakage in the vertical mill system causes heat loss. The internal temperature of the mill decreases. To maintain the required temperature, additional hot air supply is necessary, leading to increased energy consumption.


2.Decreased Output: Air leakage results in the loss of some materials. This reduction in material inside the mill lowers the load, which subsequently decreases production output.


3.Equipment Failures: Prolonged air leakage accelerates the wear of internal components, especially seals and pipes. This shortens equipment lifespan and increases maintenance costs.


4.Decline in Product Quality: Air leakage affects the grinding efficiency of materials, leading to either overly fine or coarse products, which compromises product quality.

 

II. Causes of Air Leakage in Vertical Mills

1.Aging or Damaged Seals: Seals, such as roller seals and feeder seals, can age or break after long-term operation, causing air leakage.


2.Loose Pipe Connections: If the ventilation pipes between the vertical mill and the dust collector are installed loosely or improperly connected, air leakage may occur.


3.Unreasonable Design of Locking Feeders: Traditional locking feeders, such as segmented wheels with blades, may cause air leakage if their gaps are too large or too small.


4.Inefficient Roller Seal Structure: The current roller seal design is simple and has poor sealing effectiveness. This is especially true for lower seals, where space is limited, making it difficult to ensure effective sealing.

 

5.Defective Slag Discharge Design: The direct chute from the slag discharge port to the belt conveyor is a major leakage point. The single flap valve used in the original design can easily become jammed by large materials, causing the mill to stop.

 

III. Solutions for Air Leakage in Vertical Mills

1.Replace Aging Seals: Regularly check and replace aging or damaged seals to ensure effective sealing.

 

2.Strengthen Pipe Connections: Conduct a thorough inspection of the ventilation pipes to ensure connections are secure and tight, and reinforce any loose connections.

 

3.Optimize Locking Feeder Design: Implement a material seal at the mill head. Adjust the gaps in the segmented wheels to avoid excessive or insufficient spacing that leads to air leakage.

 

4.Improve Roller Seal Structure: Change the roller seal to a circular silicone wave seal. This design offers better elasticity and sealing effectiveness, effectively reducing air leakage.

 

5.Redesign the Slag Discharge Port: Modify the discharge port to a non-powered flap locking valve. This design combines a valve body with a material curtain, using system negative pressure to create a sealed structure, effectively addressing the air leakage issue.

 

Two combined scenes of a vertical roller mill, showcasing its operational setup and components in a cement production environment.

IV. Case Study

In a cement enterprise with a 4500 t/d clinker production line, the raw material system is equipped with a TRM53.4 raw material vertical mill. Due to severe air leakage, the oxygen content at the kiln tail reached 10.3%, and the electrical consumption for the raw material process was 16.5 kWh/t. The electrical consumption for the circulating fan was as high as 8.6 kWh/t, and the output temperature was low, only 45–55°C.

This severely limited the energy-saving needs of the raw material mill. After addressing the air leakage and improving fan efficiency, the enterprise implemented measures such as replacing the locking feeder, upgrading the roller seals, and redesigning the discharge port.

As a result, air leakage significantly decreased, electrical consumption dropped by 3.8 kWh/t, the output temperature increased, and hourly production improved. After these upgrades, the enterprise saved approximately 2.58 million yuan in energy costs annually, achieving significant economic benefits.

 

V. Conclusion

Air leakage in raw material vertical mills is a complex and critical issue. Enterprises should address this from multiple angles, including design, installation, and maintenance. By optimizing equipment design, enhancing maintenance, and improving sealing effectiveness, companies can effectively reduce air leakage, increase the operational stability of vertical mills, and enhance production efficiency. If you have any questions about improving equipment performance, please feel free to contact us. Darko is here to provide you with professional solutions and support.

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Dust Collector Bag Replacement Guide

In industrial production, the lifespan and replacement frequency of dust collector bags are crucial for efficient operation. First, you must understand when to replace these bags. Next, you need to know how to choose the right filter material. This knowledge can significantly improve dust collection efficiency. Additionally, it can help reduce operating costs.

Dust Collector Bag Replacement Cycle

The theoretical replacement cycle for dust collector bags is about 4-5 years. However, due to working conditions, many bags often last shorter than expected. Extreme environments can cause wear or damage, leading to more frequent replacements. Sometimes, incorrectly chosen bags may need replacement in less than six months.

 

Reasons for Frequent Replacement

Choosing the Right Bag for the Working Condition: Different materials suit different environments. For example, polyester bags can only work in temperatures below 120°C. Using them in high-temperature situations drastically shortens their lifespan.
Quality of the Bags: Generally, high-quality dust collector bags last longer than lower-quality ones. Therefore, when selecting bags, consider both price and quality.
Operating Time and Dust Concentration: The operating time and dust concentration in the gas directly affect bag lifespan. For instance, a collector running 8 hours a day has a different replacement cycle than one running 24 hours. Higher dust concentrations also lead to more frequent replacements.

 

Replacement Recommendations

  • In harsh conditions or when running over 8 hours daily, bags may need replacement within 2 years or even sooner.
  • In milder environments, bags in collectors running 8 hours a day may last about 2-3 years before needing replacement.
High-efficiency dust collector filter bag designed for industrial applications, ensuring optimal dust capture and air quality.

Key Points for Selecting Filter Materials

Different industries have varying needs for dust collector bags, making the choice of filter material important. Here are key points for selecting filter materials for several industries:

1.Steel Plant Blast Furnace Gas Purification

  • Characteristics: High dust output, complex composition, small particles, strong adhesion.
  • Recommended Material: Synthetic fiber materials that withstand temperatures above 200°C, such as aramid, P84, and PTFE.

2.Cement Plant Kiln Tail Dust Collection

  • Characteristics: High gas temperature (around 350°C), high dust concentration, high humidity.
  • Recommended Material: Glass fiber cloth with PTFE coating or P84 and Nomex needle felt.

3.Coal-Fired Power Plant Boiler Dust Collection

  • Characteristics: High-temperature gas with SO₂, NOₓ, and high dust concentration.
  • Recommended Material: PPS and P84 needle felt, resistant to acid and oxidation.

4.Chemical Carbon Black Production

  • Characteristics: High temperatures and corrosive gas with fine particles.
  • Recommended Material: Glass fiber needle felt or Nomex needle felt, durable and resistant to high temperatures.

5.Waste Incineration (Municipal Solid Waste)

  • Characteristics: Severe smoke pollution, high moisture content, strong corrosiveness.
  • Recommended Material: Glass fiber cloth with PTFE coating or PTFE needle felt, suitable for high temperatures and corrosion.

 

Conclusion

The replacement cycle of dust collector bags and the selection of filter materials greatly affect dust collection efficiency and equipment performance. First, understand the characteristics of different working conditions. Then, choose the right bags and materials. This approach helps you extend the lifespan of the bags and improve production efficiency. If you have any questions during the selection or replacement process, contact us. We are here to provide professional advice and support.

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Optimizing Bucket Elevator Discharge Chutes

In 2022, a cement plant initiated a project to renovate its bucket elevator discharge chutes. They entrusted Nantong Darko Building Materials Machinery Co., Ltd. with the entire process, from production to equipment installation and operation. Darko quickly dispatched technicians to the site for an on-the-spot evaluation. They identified several key issues with the discharge chutes.

Main Issues

1.Insufficient Wear Resistance: The discharge chutes used wear-resistant manganese steel plates, which had poor durability. This led to multiple wear-through points and material leakage. The worn manganese steel plates became uneven, causing material to stick.

 

2.Unreasonable Structural Design: The angle in the middle of the discharge chutes was too steep, failing to effectively cushion the material. As a result, the lower part of the chute experienced severe wear.

 

3.Uneven Design of the Sloped Chute: The design of the sloped section was uneven. Material concentrated on one side, while the other side showed little wear. This uneven force distribution caused severe wear on the side in contact with the material and led to material accumulation.

 

Solutions

To address these issues, Darko's technicians proposed practical solutions:

1.Optimize Overall Structure: They adjusted the angle in the middle of the discharge chutes to reduce the impact force of the material. This modification effectively slows down and cushions the material.


2.Redesign the Sloped Chute: They changed the lower sloped section from an irregular rhomboid shape to a parallelogram. This design distributes the impact force more evenly across the bottom and sides, extending the equipment's lifespan.

 

3.Replace Wear Materials: They substituted wear-resistant ceramic liners for the manganese steel plates. The ceramic liners offer superior wear and corrosion resistance, and their smooth surface reduces material buildup.

Vertical bucket elevator system for lifting bulk materials, highlighting the conveyor mechanism and bucket arrangement

Simulation Testing and Expected Results

Darko's technicians conducted simulation tests using the new solutions. They expect to increase the lifespan of the bucket elevator discharge chutes by 3 to 5 times, improve work efficiency by 3% to 12%, and reduce the likelihood of material blockage by 20% to 30%.

These design optimizations will significantly enhance the performance of the discharge chutes. They will ensure the cement plant's production efficiency and the long-term stability of the equipment. If you are facing similar issues, feel free to contact us. We are ready to provide you with professional solutions.

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Effective Dust Control with Stainless Steel Collectors

The stainless steel bag dust collector is an advanced type of bag dust collector, distinguished from traditional iron models by its unique material. Thanks to its excellent corrosion resistance and oxidation resistance, this dust collector performs exceptionally well in many industrial applications. This article explores the working principle, features, and customization considerations of stainless steel bag dust collectors to help you choose the right dust control solution.

 

Working Principle of Stainless Steel Bag Dust Collector

The working process of the stainless steel bag dust collector is simple and efficient. Dust-laden air first enters the hopper or filter bag chamber through the inlet. The air passes through the filter bags, where it is purified before entering the clean air chamber. The clean air then exits through the exhaust port via a fan. As dust accumulates on the filter bag surface, the resistance of the equipment increases. To ensure that the resistance does not exceed 1200Pa, regular dust cleaning is necessary.

The cleaning process is automatically controlled by a PLC program. The controller periodically activates the pulse valve, releasing compressed air (0.5-0.7Mpa) through the blowing pipe. This action draws in several times more surrounding air, causing the filter bags to expand rapidly. The reverse airflow helps dislodge the dust from the bags, achieving effective cleaning.

Reasons to Choose a Stainless Steel Bag Dust Collector

1. Corrosion and Oxidation Resistance

Stainless steel bag dust collectors are primarily made from 304 and 316 stainless steel plates. These materials ensure stability and durability when handling corrosive gases. In contrast, traditional iron dust collectors cannot meet these demanding application needs.

2. Longer Lifespan

Due to the superior properties of stainless steel, these dust collectors have a significantly longer lifespan than traditional models. This feature reduces the frequency of replacements and maintenance costs.

3. Aesthetic Appeal

The appearance of stainless steel is more attractive, making it suitable for industrial environments where aesthetics matter.

 

The Stainless Steel Bag Dust Collector is placed in an open area, effectively removing dust particles from the air to ensure a cleaner workspace.

Considerations for Customizing a Stainless Steel Bag Dust Collector

When customizing a stainless steel bag dust collector, companies should consider the following aspects:

1. Size and Capacity

Choose the appropriate model and specifications based on the actual conditions of the production site. If space is limited, opt for a compact unit. If dust concentration is high, select a larger capacity collector to ensure effective dust removal.

2. Filter Material

Select filter materials based on the size, chemical properties, and temperature of the dust particles. Common materials include polyester fiber, fiberglass, and PPS.

3. Number of Bags

The number of bags should correspond to the dust concentration and air flow rate at the production site. More bags typically result in better dust removal efficiency.

4. Auxiliary Equipment Configuration

Consider configuring cleaning systems and control systems based on actual needs. A cleaning system can effectively remove dust from the bags, ensuring long-term stable operation. An automated control system can enhance efficiency.

Maintenance and Care

To ensure the long-term stable operation of the stainless steel bag dust collector, companies should pay attention to the following points:

Ensure that the materials and manufacturing processes meet relevant standards for stability and durability.
Design the layout based on the production site conditions to ensure effective and safe operation.
Conduct regular maintenance and replace damaged parts and bags promptly.

Conclusion

The stainless steel bag dust collector is an essential piece of equipment in modern industry due to its efficiency and reliability. With proper customization, companies can obtain dust control solutions that meet their specific needs. Darko can provide you with flexible and efficient dust control equipment to improve the cleanliness of your production environment and protect employee health. If you have any needs or questions, please feel free to contact us. We are dedicated to providing you with professional service and support.

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Nantong Darko Building Materials Machinery, a leading manufacturer and supplier in China, specializes in R&D, design, manufacturing, and installation of solutions for desulfurization, denitrification, dust removal, and environmental protection projects, as well as slag micro powder and powder grinding production lines.

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