Fly ash storage silos are crucial facilities for storing fly ash, an industrial by-product, in power plants, cement plants, and other industrial enterprises. They effectively centralize and manage fly ash, providing a stable supply of raw materials for subsequent industrial production processes.
However, a lack of regular cleaning and maintenance of fly ash silos over long periods of use can lead to a series of problems. Regular cleaning and maintenance not only prevents fly ash accumulation and blockage within the silo, ensuring the safe operation of the silo and related equipment, but also maintains good storage efficiency and ensures the smooth flow of fly ash in and out of the silo. Conversely, improper cleaning methods or neglected cleaning can lead to safety hazards within the silo, such as structural damage, and can also affect the flow of fly ash, hindering the smooth progress of industrial production.
1. Why Is It Necessary To Clean Fly Ash Steel Silos?
First, long-term storage of fly ash in steel silos can lead to hardening and accumulation. This hardened fly ash can block the discharge port, preventing proper discharge. It can also damage the ventilation system, affecting ventilation efficiency within the silo and further exacerbating the hardening of the fly ash.
Second, long-term accumulation of fly ash can cause uneven loading on the steel silo, creating additional stress on the silo structure. Over time, this stress can accumulate and, in severe cases, lead to structural deformation or even a major safety accident, such as silo collapse.
Furthermore, regular cleaning of fly ash steel silos ensures good flowability of the fly ash within the silo, reduces equipment failure rates, and thus extends equipment life, improving the operational efficiency of the entire storage system and providing strong support for stable production.
2. Precautions Before Using Fly Ash Steel Silos
Before cleaning, it is essential to understand the proper use of steel silos. Before the first loading, ensure the interior of the steel silo is dry. A humid environment can cause fly ash to clump and adhere to the silo walls, hindering subsequent storage and unloading.
Before loading, a thorough inspection of the silo is also necessary to remove debris such as bricks, wood, and slag to prevent them from mixing with the fly ash and affecting its quality. This also prevents debris from clogging the unloading equipment.
In addition, carefully inspect the dust collector ducting to ensure it is unobstructed, ensuring proper air circulation within the silo and avoiding excessive dust concentrations caused by poor ventilation. Also, verify that the iron removal system is operating properly to prevent metallic impurities from entering the silo and contaminating the fly ash and damaging related equipment. The safety of the air supply and return valves must also be verified to ensure they are leak-free and operate smoothly to avoid blockages caused by valve problems.
3. Preparations for Fly Ash Silo Cleaning
Before cleaning begins, install temporary warning signs around the silo to clearly demarcate the work area and prohibit unauthorized personnel from entering to prevent accidents. All storage and feed pipes must be closed and properly secured to prevent fly ash leaks or other debris from entering the pipes during the cleaning process.
Lighting tools must be explosion-proof and well-insulated to prevent electrical leakage in the humid or dusty environment of the warehouse, ensuring the safety of workers.
Ladders, platforms, and the warehouse structure must also be carefully inspected for stability to prevent falls or equipment damage caused by structural instability during the cleaning process.
In terms of personnel allocation, professionally trained personnel must be assigned to perform cleaning operations, and a strict 2:1 staffing ratio must be adhered to: for every worker working inside the warehouse, two supervisors must be on duty outside to ensure timely response to emergencies.
4. Worker Safety Requirements
All personnel involved in cleaning operations must wear complete and standard safety protective equipment, including goggles and dust masks to prevent dust from entering the eyes and respiratory tract, protecting their vision and respiratory health. They must also wear hard hats to protect their heads from accidental impacts, and protective shoes to protect their feet from sharp objects or crushing heavy objects.
Workers must also wear safety belts and dual safety lines, one secured to the dust collector bracket and the other to the ladder, providing dual protection to prevent falls while working inside the warehouse.
For communication, workers inside the warehouse and supervisors outside the warehouse must maintain real-time communication using walkie-talkies to ensure timely communication of work status and instructions, allowing for rapid coordination and resolution of any issues.
During the cleaning process, the use of explosives or other high-risk tools is strictly prohibited to prevent serious safety hazards such as explosions and fires.
For special work environments, such as high-altitude cleaning, a dedicated safety plan must be developed in advance to clearly define the work process, safety precautions, and emergency measures to ensure safe and orderly cleaning operations in these special environments.
5. Detailed Procedures for Cleaning Fly Ash Silos
(1) Preliminary Inspection
Workers enter the silo from the top and conduct a comprehensive inspection of the fly ash’s hardness and remaining volume. By observing and touching, they determine whether there are large areas of hardened fly ash, as well as the approximate volume and distribution of the remaining fly ash.
At the same time, they carefully inspect any blockages within the silo to determine their specific location and severity. They also check the unobstructed access to the discharge port and related passageways, providing a basis for developing a reasonable cleaning plan.
(2) Air Blowing and Material Softening
Using a compressed air gun, starting from the bottom of the silo and working upwards, blow away any hardened fly ash within the silo. The compressed air pressure should be adjusted appropriately based on the degree of hardening of the fly ash to avoid excessive pressure that could cause fly ash splashing, secondary contamination, or damage the silo structure.
Blowing with compressed air gradually loosens and softens the hardened fly ash, allowing it to flow naturally along the inclined surface of the silo toward the discharge port, preparing for subsequent material cleanup. During the purge process, operators must constantly adjust the angle and position of the compressed air gun to ensure effective purge of hardened fly ash in every area.
(3) Manual Cleaning and Material Removal
For fly ash clumps that remain after air purge, operators must manually loosen them using tools such as long iron rods or shovels. During this operation, operators must pay attention to force and angle to avoid scratching or impacting the silo walls, thereby preventing damage to the silo structure.
For stubborn, difficult-to-loose fly ash accumulations, temporary discharge chutes can be installed at appropriate locations. The location and angle of the temporary discharge chute must be carefully calculated to ensure smooth flow of fly ash toward the discharge port, improving material removal efficiency.
If the pressure cone of a steel silo becomes clogged, a small inspection hole, approximately 400mm x 500mm, can be opened at an appropriate location within the cone. Operators can access the cone through the inspection hole and use specialized tools to clear and unclog the blockage, ensuring smooth flow and ensuring proper discharge. During the process of opening inspection holes and clearing obstructions, safety precautions must be implemented to prevent injury to workers and material leaks.
(4) Stepwise Cleaning and Inspection
Cleaning should be carried out step by step, from top to bottom. This prevents fly ash from above from contaminating the cleaned areas below during the cleaning process and ensures that fly ash is evenly cleaned in all areas of the silo.
During the cleaning process, workers should regularly check the cleaning progress to see if there is any residual fly ash in the cleaned areas and that the silo walls are clean and tidy. When the fly ash level in the silo drops to the level of the side inspection door, additional workers can enter through the inspection door to collaborate with existing workers in the silo to complete the remaining cleaning work, improving cleaning efficiency. Before additional workers enter the silo, they must reconfirm the safety of the silo and ensure proper ventilation and structural stability.
(5) Completion of Cleaning and Site Cleanup
Once the cleaning work is substantially complete, workers must conduct a comprehensive inspection of the interior of the steel silo, carefully checking the silo walls, discharge openings, ladders, platforms, and other areas to ensure that all fly ash residue has been completely removed and that there are no debris or blockages inside.
After confirming that the cleaning quality meets the standards, workers will re-inspect the silo’s safety to ensure that the temporarily installed equipment is stable and that the safety features are intact. Once these inspections are complete, they will begin dismantling the temporary equipment and protective barriers, taking care to avoid damage to the silo and existing equipment during the dismantling process.
Finally, the work site will be cleaned up, and all debris and garbage generated during the cleaning process will be removed from the site to ensure a clean and tidy work area. At the same time, the relevant equipment in the steel silo will be restored to normal operation, and equipment commissioning and inspection will be completed to ensure that the silo is ready for immediate use.
6. Engineering Technical Recommendations
During daily use, regularly inspect and maintain the gasification plate and discharge cone of the steel silo. Check for damage or blockage on the gasification plate, and for deformation or wear on the discharge cone. If any problems are found, promptly repair or replace them to prevent fly ash accumulation and blockage caused by gasification plate and discharge cone failure.
Develop a comprehensive inspection and cleaning plan, regularly inspect the steel silo. Schedule appropriate times for partial or full cleaning based on the fly ash accumulation and frequency of use. This prevents excessive fly ash accumulation caused by prolonged inactivity, which increases cleaning difficulty and safety risks. This also reduces production downtime caused by cleaning.
For large-capacity fly ash silos, due to their large internal space and the difficulty of cleaning, it is recommended to use specialized cleaning tools. These tools offer high efficiency, safety, and excellent cleaning results. If an enterprise lacks in-house cleaning capabilities and equipment, it may be advisable to hire a professional cleaning service. These services have experienced personnel and advanced cleaning equipment to ensure high-quality and safe cleaning.
7. Common Safety Misconceptions to Avoid
It is strictly forbidden to enter a steel silo without adequate ventilation and monitoring the silo environment. Long-term storage of fly ash in a silo may lead to the accumulation of hazardous gases or insufficient oxygen concentration. Entering without ventilation and monitoring can result in serious safety accidents such as poisoning and suffocation. Before entering the silo, first turn on the ventilation equipment to ventilate the silo. After a period of ventilation, use professional gas detection equipment to test the gas composition and oxygen concentration inside the silo. Only after confirming that they meet safety standards can workers enter.
During cleaning operations, the use of safety belts and double safety harnesses must never be neglected. Some workers may take chances, believing that the work time is short or the work location is safe, and not wear safety protective equipment or wear them improperly. This can lead to personal safety in the event of an accident. All workers must strictly wear safety belts and double safety harnesses as required and ensure that the safety harnesses are securely fastened.
Untested equipment and non-insulated lighting tools must not be used. Untested equipment may have performance problems or safety hazards, and they are prone to leakage, malfunction, and other issues during use, potentially leading to accidents. Non-insulated lighting tools are also highly susceptible to leakage in the humid and dusty environment of the silo, posing a threat to the lives of workers. All equipment and lighting used in cleaning operations must undergo rigorous testing and inspection to ensure reliable performance and proper insulation.
During the cleaning process, communication between workers inside the silo and supervisors outside the silo must be crucial. Good communication is key to ensuring the safe and orderly conduct of cleaning operations. Poor communication prevents supervisors from being able to understand the ongoing operations. When emergencies occur, they cannot take effective emergency measures, delaying rescue efforts and exacerbating losses. During operations, both parties must maintain continuous and clear communication, sharing progress and safety information in a timely manner.
8. Conclusion
In summary, during fly ash steel silo cleaning, safety and adherence to operating procedures are paramount and must always be prioritized.
Standardized, thorough cleaning not only effectively prevents safety accidents and ensures the safety of personnel and equipment, but also ensures good flowability of fly ash within the silo, improving storage efficiency and extending the silo’s service life, effectively safeguarding the company’s stable production.
If a company is unsure of the internal conditions of a steel silo or encounters difficult problems during cleaning, it is recommended to promptly seek assistance from a professional inspection or cleaning service to avoid safety accidents or compromised cleaning results due to blind operation.