BOTTOM ASH HANDLING SYSTEM SUBMERGED SCRAPER CONVEYOR SYSTEM

Bottom Ash Handling System: Submerged Scraper Conveyor (SSC) System

The Submerged Scraper Conveyor (SSC) is a critical component of a Bottom Ash Handling System (BAHS), particularly in coal-fired power plants and waste-to-energy plants. It plays a vital role in the safe, efficient, and environmentally friendly transport of bottom ash from the combustion chamber to designated storage or disposal areas.

Bottom ash is generated after the combustion process in boilers, and it must be removed quickly to maintain the efficiency of the power plant. The SSC system provides a solution for efficiently transporting this ash while minimizing dust emissions and preventing excessive wear on equipment.

How the Submerged Scraper Conveyor System Works

1. Ash Discharge:
   • Bottom ash is collected from the boiler’s discharge hoppers or slag taps. Hot ash is then conveyed into a water-filled trough where the SSC system is located. The submerged environment helps cool down the hot ash while minimizing the risk of combustion and dust emissions.
2. Submerged Ash Transport:
   • The scraper blades attached to a chain system move along the bottom of the trough. These scrapers effectively scrape the ash from the bottom of the trough and push it along to the discharge point. The water serves two primary purposes: cooling the hot ash and suppressing dust that would otherwise be released into the atmosphere.
3. Continuous Ash Removal:
   • As the scraper chain moves through the trough, the ash is constantly lifted and transported towards the discharge area. The continuous motion ensures there is no ash buildup, preventing any blockage in the system. The scraper system is specifically designed to handle dense, sticky ash, ensuring reliable and uninterrupted operation.
4. Ash Discharge:
   • At the end of the submerged conveyor system, the bottom ash is discharged into a storage hopper, cooling pit, or other disposal areas. The design allows the ash to be further processed, stored, or transported as required.
5. Water Circulation System:
   • The water in the submerged trough is continuously circulated to ensure effective cooling and efficient ash transport. The water circulation system helps prevent the buildup of debris or ash sludge, maintaining smooth conveyor operation.

Key Components of the Submerged Scraper Conveyor System

1. Submerged Trough:
   • This is where the bottom ash is transported. The trough is designed to hold water and submerge the conveyor chain and scrapers. It acts as a cooling zone for the hot ash and also helps suppress dust emissions.
2. Scraper Blades and Chain:
   • The scraper blades are attached to a durable chain that moves along the trough. The scrapers scrape the ash from the bottom of the trough and transport it to the discharge point. The chain and scrapers must be robust to handle the abrasive and dense nature of bottom ash.
3. Drive Mechanism:
   • The drive system powers the chain and scraper blades. It ensures continuous movement and reliable operation of the conveyor. The motorized system is designed for durability and long-term performance, as it needs to operate in harsh conditions (high temperatures, water, and abrasive ash).
4. Water Circulation System:
   • This system circulates water through the trough to cool the ash and maintain the submerged condition. The water also helps prevent the formation of clogs and ensures smooth ash transport.
5. Discharge Area:
   • At the end of the conveyor system, the ash is discharged into a storage hopper, cooling pit, or another processing area. The design of the discharge system ensures that the ash is moved quickly and efficiently.
6. Inspection and Maintenance Ports:
   • Inspection and maintenance ports allow plant operators to inspect, clean, and perform preventive maintenance on the system to ensure continuous, trouble-free operation.

Advantages of Submerged Scraper Conveyor Systems for Bottom Ash Handling

1. Dust-Free Operation:
   • The submerged design prevents bottom ash from becoming airborne, significantly reducing dust emissions. This helps ensure a cleaner work environment and compliance with air quality regulations.
2. Efficient Cooling of Ash:
   • By submerging the ash in water, the system ensures rapid cooling of hot ash, protecting the equipment from excessive heat and preventing any fire hazards in the handling process.
3. Handling of Dense and Sticky Ash:
   • The scraper mechanism is effective at handling dense, sticky, and abrasive bottom ash. This allows the system to keep ash moving through the trough without blockages, even with difficult-to-handle material.
4. Durability and Low Maintenance:
   • The system is built to withstand harsh conditions, including high temperatures, water exposure, and abrasive ash. With proper maintenance, the SSC system can last for many years with minimal wear and tear, reducing long-term operational costs.
5. Continuous Operation:
   • The SSC system provides continuous operation, ensuring that the plant’s bottom ash handling process remains efficient without interruptions. This is essential to maintaining the overall efficiency of the power plant.
6. Environmental Compliance:
   • The dust suppression and cooling provided by the submerged design help meet environmental regulations concerning emissions and water use.
7. Space-Saving Design:
   • The compact design of submerged scraper conveyors makes them easy to integrate into a variety of plant layouts, even in areas with limited space.

Applications of Submerged Scraper Conveyor Systems

1. Coal-Fired Power Plants:
   • SSC systems are commonly used in coal-fired power plants to manage the bottom ash generated during the combustion process. These systems help remove and transport ash from the boiler to storage or disposal locations.
2. Waste-to-Energy Plants:
   • In waste-to-energy plants, SSCs handle the bottom ash produced from the incineration of municipal solid waste. These plants typically require systems that can handle large volumes of ash and operate under challenging conditions.
3. Cement Plants:
   • Cement production often involves the combustion of waste materials in rotary kilns, producing bottom ash. SSC systems are effective in handling this ash and transporting it for disposal or further processing.
4. Steel and Metallurgical Plants:
   • In metallurgical facilities, submerged scraper conveyors handle slag and other byproducts generated during metal production, ensuring efficient removal and processing.
5. Incineration Facilities:
   • Submerged scraper conveyors are used to transport and handle bottom ash in incineration facilities. These systems help manage the byproducts of waste-to-energy processes.

Maintenance and Operational Considerations

1. Water Quality Management:
   • It’s essential to monitor and manage the quality of the water in the submerged trough. Contaminants, such as ash sludge, should be removed regularly to ensure efficient cooling and ash transport.
2. Wear on Scraper Blades and Chain:
   • Regular inspections of the scraper blades and chain are necessary to detect wear caused by the abrasive nature of bottom ash. Components may need to be replaced periodically to ensure optimal performance.
3. Inspection of the Drive System:
   • The motor and drive system should be inspected periodically to ensure it is operating efficiently. Any signs of malfunction or reduced performance should be addressed to prevent downtime.
4. Water Circulation Maintenance:
   • The water circulation system should be regularly maintained to prevent blockages or breakdowns in the pump system. Proper water flow is essential to maintaining efficient cooling and transport.
5. Lubrication of Moving Parts:
   • Lubricating the moving parts of the conveyor, such as the chain and scrapers, helps reduce friction and wear, ensuring the system runs smoothly and lasts longer.

Why Choose a Submerged Scraper Conveyor (SSC) System for Bottom Ash Handling?

• Efficiency: Continuous operation with minimal downtime ensures that bottom ash is removed from the combustion area promptly, keeping the plant running smoothly.
• Environmentally Friendly: The dust suppression and water cooling reduce harmful emissions, helping meet stringent environmental regulations.
• Durability: Designed for long-lasting performance in demanding conditions, SSCs reduce the frequency of repairs and the overall operational costs.
• Versatility: The system can handle a variety of bottom ash types and can be adapted to different plant layouts.

If you have specific requirements for bottom ash handling or need a tailored Submerged Scraper Conveyor solution, feel free to reach out for further consultation!

Submerged Scraper Conveyors (SSC) are commonly used to remove ash from big power stations’ coal-fired boilers. They usually employ a two-chain conveying system, with a driving station that uses sprockets (toothed or pocket wheel type) and a chain guided by intermediate and reverse wheels that follows the path required for carrying bulk material. The ends of the chain are many meters long.

They’re made with extraordinary accuracy (length tolerance in each pair is no more than 0.05 percent) and coupled together with unique couplings; scraping elements are attached directly to the chain using specific fittings. Improve the handling of ash or slag following your boiler or kiln’s combustion operation. Our Submerged Scraper Chain Conveyor (SSCC) uses established technology to remove and cool the ash and slag produced in a smooth and efficient manner. This dependable technology has proven to withstand temperatures of up to 1,000° C (1,832° F) during feeding.

Ash and slag transport with a submerged scraper chain conveyor

Submerged Scraper Chain Conveyors are designed to extinguish, cool, and transfer ash, slag, and other combustion remnants in a dust-free manner. Their gas-tight design prevents vapors and particles from escaping while also successfully blocking the entry of outside air, which can disrupt combustion operations.

The material enters the enclosed trough via a water-filled conveyor compartment, where it is extinguished, cooled, and moved via a drag chain conveyor for complete dust- and vapor-proof handling. Swimming materials (upper-strand carrying) and sinking materials are both acceptable for submerged scraper conveyors (lower-strand conveying). Our SSCCs may simply be integrated into existing systems due to their self-supporting structure, needing minimal space.

Combustible material handling that is safe and reliable

1. High level of dependability

Our Submerged Scraper Chain Conveyor systems may run unattended for up to 24 hours, 7 days a week. Wear is reduced by operating at a constant speed.

2. Minimal water usage

As it departs the trough, the conveyor inclines, helping to dewater the material and enabling water reuse.

3. Free of dust and vapors

The gas-tight design prevents the escape of vapors and dust while also efficiently inhibiting the entrance of outside air that could interfere with the combustion process, assuring the boilers’ reliable and continuous operation.

Aspects of Design

1. Chain tensioning unit that works automatically:

The tension of the SSC chain is automatically controlled using a device that uses an oil/inert gas differential. This fully automated system accurately tensions the chain under all load circumstances. It can send data back to the PLC in the control center for visual or aural notification.

2. Hydraulic power pack and drive:

We generally configure dual motors to make use of the inherent torque characteristics of this technology, providing exceptional start-up performance and greater flexibility under upset circumstances.

3. Chain of transmission:

We use three types of sprockets and chain wheels with our unique heavy strength case hardened round link chain to suit the SSC’s demanding demands.

Submerged Scraper Chain Conveyor – designed to last a long time.

 We use our Type V vertical arrangement, which enables for conveying up high inclines (typical operation is at 45°) and is built with our renowned Drag Chain Conveyors. Dust-proof, water-tight, and pressure-tight are all features of our SSCCs.

Our Drag Chain Conveyor, which is at the heart of the SSCC, has drop-forged links with the welding lug built into the forged piece. We use a specific flash-butt welding procedure to secure the flights to the lug, which prevents them from breaking off. The conveyor chains’ functionality and tensile strength provide excellent availability and long service life. Flights come in a variety of shapes and sizes to fit your material and purpose.