Emissions and Losses in Crude Oil Storage Tanks

During the storage of crude oil, emissions and losses are significant factors that cannot be overlooked. These losses not only impact the economic benefits of the oil but also have the potential to negatively affect the environment. Therefore, understanding and effectively controlling these loss processes of crude oil storage tank is crucial for improving resource utilization, reducing pollution, and optimizing operational management. This article will focus on the analysis of major breathing losses, minor breathing losses, and the impact of the sealing performance of storage tank accessories on these losses, proposing corresponding control measures.

Major Breathing Losses of Crude Oil Storage Tank

Major breathing losses occur during the loading and unloading processes when pressure changes inside the tank lead to the release of oil vapor through the breathing valve. During loading, as the oil level rises, the air space inside the tank decreases, increasing the pressure. When the pressure exceeds the set pressure of the breathing valve, oil vapor starts to escape, leading to evaporation losses. Conversely, during unloading, as the oil level drops, the air space increases, and the pressure decreases. When the internal pressure falls below the set vacuum pressure of the valve, outside air is drawn into the tank, which accelerates the evaporation and further leads to the release of oil vapor.

1. Factors Influencing Major Breathing Losses

Several factors affect the extent of major breathing losses, including:
Oil Properties: The density and composition of the oil directly affect its volatility. Low-density and lighter oils tend to have higher evaporation losses.
Loading and Unloading Speed: Faster loading and unloading speeds cause more significant pressure fluctuations inside the tank, resulting in increased losses.
Tank Pressure Rating: Tanks with higher pressure ratings experience reduced breathing losses. For example, a tank with a pressure rating of 5 kPa can reduce major breathing losses by approximately 25.1%, and a rating of 26 kPa can effectively minimize these losses.
Geographic Location and Climate: The local climate conditions (e.g., temperature, wind speed, etc.) directly affect the pressure variations inside and outside the tank, influencing major breathing losses.

2. Measures to Control Major Breathing Losses

To reduce major breathing losses, the following measures can be implemented:
Increase Tank Pressure Rating: Design tanks with higher pressure capabilities to reduce breathing losses.
Control Loading and Unloading Speed: Adjust the speed of loading and unloading operations to avoid excessive pressure fluctuations.
Strengthen Tank Management: Adjust tank operations based on specific location and external climate conditions to minimize major breathing losses.

Minor Breathing Losses of Crude Oil Storage Tank

Minor breathing losses occur when there is no active loading or unloading. These losses are caused by temperature and atmospheric pressure fluctuations, which lead to periodic changes in the evaporation and condensation of oil vapor. This phenomenon is generally related to factors such as daily temperature differences, seasonal changes, and sunlight intensity.

1. Factors Influencing Minor Breathing Losses

Several factors affect the size of minor breathing losses, including:
Day-Night Temperature Difference: Large temperature fluctuations between day and night cause more significant expansion and contraction of the air space inside the tank, increasing minor breathing losses.
Sunlight Intensity: Intense sunlight raises the internal temperature of the tank, accelerating oil evaporation and increasing minor breathing losses.
Tank Size: Larger tanks, with more extensive air space, tend to experience greater minor breathing losses.
Atmospheric Pressure: Lower atmospheric pressure increases the rate of evaporation, intensifying minor breathing losses.
Tank Filling Level: A higher filling level reduces the air space, which in turn reduces minor breathing losses.

2. Measures to Control Minor Breathing Losses

To minimize minor breathing losses, the following measures can be taken:
Optimize Tank Location: Choose a location that minimizes the impact of strong sunlight and temperature fluctuations on the tank.
Control Tank Filling Levels: Maintain a reasonable filling level to avoid excessive air space, which can increase losses.
Insulate Tanks: In regions with significant temperature fluctuations, insulating tanks can help reduce the impact of temperature changes.

Impact of Tank Accessories Sealing on Losses

The sealing performance of tank accessories directly affects oil losses. If the accessories (such as flame arresters, liquid seals, mechanical breathing valve discs, foam glass chambers, oil measuring ports, etc.) are not properly sealed, air and vapor leaks can lead to significant oil vapor losses. Therefore, ensuring the sealing integrity of tank accessories is an important measure to reduce losses.

Enhancing Sealing Performance

Regular inspection and maintenance of tank accessories can significantly improve their sealing performance and reduce losses:
Regular Inspections and Maintenance: Conduct at least two comprehensive inspections per year to ensure that the sealing performance meets the required standards.
Optimize Equipment Design: Use high-quality sealing materials to prevent leaks due to aging or damage of accessories.

Summary and Optimization Suggestions

The losses in crude oil storage tanks mainly arise from major breathing losses, minor breathing losses, and poor sealing of tank accessories. To reduce these losses, it is essential to optimize the operation, design, and management of the tanks. Measures such as increasing tank pressure ratings, controlling loading and unloading speeds, maintaining appropriate tank filling levels, and enhancing sealing performance can effectively reduce emissions and losses. This will improve resource utilization and reduce environmental pollution. Companies should strengthen management and adopt scientific strategies based on specific geographic and climatic conditions to achieve a balance between economic benefits and environmental protection.