Mechanical Cleaning Technology for Crude Oil Storage Tanks

Mechanical cleaning technology for crude oil storage tanks is an efficient, safe, and environmentally friendly cleaning method widely used in oil depots and petroleum storage and transportation systems. This technology involves a specially designed cleaning system that connects cleaning equipment to the storage tank via temporary piping, allowing for the execution of the cleaning process. Compared to traditional manual cleaning methods, mechanical cleaning significantly improves work efficiency, shortens cleaning cycles, enhances safety, and reduces environmental pollution risks.

During the mechanical cleaning process, the flowable crude oil at the bottom of the tank is transferred to a recovery tank. Then, cleaning oil and hot oil are sprayed using a cleaning machine, breaking up and dissolving the sludge and solidified oil inside the tank through heating and pressurizing. The cleaned oil is filtered and returned to the recovery tank, while the remaining water and oil-water mixture are processed in an oil-water separator before being recovered. Finally, clean water is used to thoroughly wash all parts of the tank, ensuring no oil residue remains and providing a safe environment for subsequent maintenance and hot work operations.

Mechanical Cleaning Steps for Crude Oil Storage Tanks

The mechanical cleaning process for crude oil storage tanks involves a series of efficient and orderly steps. Each step, from equipment installation to the completion of the cleaning, is crucial in ensuring both the effectiveness and safety of the operation. Below are the key steps involved.

1. Installation of Equipment and Piping

The installation of equipment and piping is carried out according to the temporary piping layout plan, ensuring that all connections are secure and meet construction requirements. The entire system undergoes a pressure test to ensure a leak-free and sealed condition, preventing any leakage incidents. Additionally, electrical systems and gas detection systems, including oxygen and combustible gas detectors, are installed to ensure environmental safety during the operation.

2. Crude Oil Transfer

Using the system's transfer module, the flowable crude oil in the tank is transferred to the recovery tank, providing the necessary oil source for subsequent cleaning operations. This process ensures the effective recovery of flowable oil within the tank, preventing oil waste.

3. Cleaning Operation

In the cleaning module, the crude oil in the tank is heated and pressurized, and a specialized cleaning machine sprays the oil inside the tank. The spray action dissolves solidified oil and breaks up the sludge deposits. The cleaned oil is then filtered to remove impurities and returned to the recovery tank, effectively removing oil residues from the tank's interior.

4. Water Cleaning Cycle

Clean water is added to the oil-water separator, and after being heated and pressurized, it is used by the cleaning machine to thoroughly clean all areas of the tank. This ensures that all oil residues and solid deposits are completely removed. During the cleaning process, the oil-water separator separates the oil-water mixture generated during cleaning, with the recovered crude oil being pumped back into the recovery tank, while clean water continues to circulate for further cleaning.

5. Safety Measures

To prevent accidents such as explosions, inert gases like nitrogen are continuously injected into the tank being cleaned to maintain a safe atmosphere. Oxygen and combustible gas detectors are used in real-time to monitor oxygen levels and the presence of combustible gases, ensuring that the oxygen concentration remains below 8% by volume, maintaining a safe environment throughout the process.

Advantages of Mechanical Cleaning Technology

Mechanical cleaning technology offers significant advantages over traditional manual cleaning methods, particularly in terms of efficiency, safety, environmental friendliness, economic benefits, and superior cleaning results. These advantages make mechanical cleaning a more reliable and sustainable solution for cleaning crude oil storage tanks.

1. Efficiency and Time Savings

Mechanical cleaning significantly reduces operation time. Traditional manual cleaning of an oil tank could take more than one and a half months, while mechanical cleaning can complete the process in just 24 days, greatly improving work efficiency. This highly efficient cleaning process is irreplaceable for large-scale oil depot cleaning.

2. Increased Safety

Mechanical cleaning eliminates the need for workers to enter the tank, removing the significant safety risks associated with manual cleaning, such as oxygen deficiency, poisoning, and explosions. Inert gas protection and continuous monitoring of oxygen and combustible gases ensure that the tank environment remains within safe limits. Since the entire cleaning process occurs within a sealed environment, workers are not exposed to hazardous oil and gas conditions, greatly improving safety.

3. Environmental Protection and Resource Recovery

Mechanical cleaning uses a closed cleaning system to prevent oil leaks and avoid environmental pollution. During cleaning, crude oil is separated and recovered through the oil-water separator, while remaining clean water is reused in a circular process, ensuring no resource waste. As there is no need to handle large amounts of residual oil and sludge, the entire operation does not release any pollutants, ensuring a clean and safe environment.

4. Significant Economic Benefits

The recovery rate of crude oil during mechanical cleaning exceeds 98%, meaning nearly all crude oil is recovered back into the storage system, avoiding the economic losses from the 150 tons of oil and sludge that would typically be unrecoverable in manual cleaning. In addition to improving resource utilization, mechanical cleaning reduces cleaning cycles and downtime, enhancing the overall economic efficiency of the oil depot.

5. Superior Cleaning Results

Mechanical cleaning technology can thoroughly remove crude oil residues, particularly solidified oil and sludge at the bottom of the tank. This thorough cleaning meets industrial safety standards for hot work, avoiding the risk of oil and gas vaporization and potential fire or explosion during welding or other operations. After cleaning, the tank's metal surfaces are free from oil residues, and gas detection results show zero concentrations of H2S and combustible gases, ensuring high-quality cleaning.

Conclusion

Mechanical cleaning technology for crude oil storage tanks offers clear advantages over traditional manual cleaning, especially in terms of efficiency, safety, environmental protection, and economic benefits. Through the use of a closed cleaning system, mechanical cleaning effectively prevents environmental pollution and resource waste while providing a safer and more reliable cleaning process. As technology continues to develop, mechanical cleaning will play an increasingly important role in the maintenance of crude oil storage tanks, providing stronger support for the safe operation of oil depots and petroleum storage and transportation systems.