Tank Emissions Control Guide

Introduction to Tank Emissions Control

Tank emissions are a significant source of volatile organic compounds (VOCs) and other hazardous air pollutants (HAPs) in petroleum facilities. These emissions can have detrimental effects on the environment, human health, and the facility's overall operations. In this comprehensive guide, we will explore the importance of tank emissions control, the regulatory framework governing it, and the best practices for minimizing tank emissions.

Overview of Tank Emissions in Petroleum Facilities

Petroleum facilities, such as refineries, terminals, and storage facilities, use tanks to store crude oil, petroleum products, and other chemicals. These tanks can be a significant source of emissions, including VOCs, HAPs, and greenhouse gases (GHGs). The emissions occur due to various factors, such as:

• Evaporation of stored products
• Tank breathing (expansion and contraction of vapors due to temperature changes)
• Tank filling and emptying operations
• Leaks and spills

Importance of Tank Emissions Control

Controlling tank emissions is crucial for several reasons:

• Environmental protection: VOCs and HAPs can contribute to air pollution, negatively impacting local ecosystems and human health.
• Regulatory compliance: Petroleum facilities must comply with various regulations and standards governing tank emissions.
• Operational efficiency: Minimizing tank emissions can help reduce product losses, improve facility operations, and lower maintenance costs.
• Safety: Uncontrolled tank emissions can create safety hazards, such as explosions and fires.

Regulatory Framework for Tank Emissions

The regulatory framework for tank emissions control varies by country and region. In the United States, for example, the Environmental Protection Agency (EPA) regulates tank emissions under the Clean Air Act (CAA). The EPA has established various standards and guidelines for tank emissions control, including:

• New Source Performance Standards (NSPS) for VOC emissions from storage tanks
• National Emission Standards for Hazardous Air Pollutants (NESHAP) for petroleum refineries and other facilities
• Risk Management Program (RMP) regulations for facilities handling hazardous substances

Tank Design and Operation for Emissions Reduction

Tank design and operation play a critical role in minimizing tank emissions. By incorporating design considerations and operational practices that reduce emissions, facilities can lower their environmental impact and improve overall efficiency.

Design Considerations for Minimizing Tank Emissions

When designing tanks, consider the following factors to minimize emissions:

• Tank type: Choose tank types that are designed to minimize emissions, such as floating-roof tanks or internal floating-roof tanks.
• Tank size and configuration: Optimize tank size and configuration to reduce the surface area exposed to the atmosphere.
• Sealing and fittings: Ensure that tanks are properly sealed, and fittings are designed to prevent leaks.
• Vapor recovery: Incorporate vapor recovery systems to capture and recover vapors emitted during tank operations.

Operational Practices for Reducing Tank Emissions

Implement the following operational practices to reduce tank emissions:

• Minimize tank filling and emptying: Optimize tank filling and emptying operations to reduce the frequency and volume of emissions.
• Monitor tank levels and pressures: Regularly monitor tank levels and pressures to detect potential leaks or other issues.
• Maintain tank integrity: Regularly inspect and maintain tanks to prevent leaks and other damage.
• Use vapor recovery systems: Use vapor recovery systems to capture and recover vapors emitted during tank operations.

Maintenance Strategies for Preventing Emissions

Regular maintenance is essential to preventing tank emissions. Implement the following strategies:

• Regular inspections: Regularly inspect tanks and associated equipment to detect potential issues.
• Predictive maintenance: Use predictive maintenance techniques, such as monitoring tank conditions and analyzing data, to identify potential problems before they occur.
• Repair and replacement: Promptly repair or replace damaged or faulty equipment to prevent emissions.

Control Technologies for Tank Emissions

Various control technologies are available to reduce tank emissions. The choice of technology depends on factors such as the type and quantity of emissions, facility operations, and regulatory requirements.

Vapor Recovery Units (VRUs) for Emissions Control

Vapor recovery units (VRUs) are designed to capture and recover vapors emitted during tank operations. VRUs can be used to control emissions from various sources, including tank filling and emptying operations.

The following diagram illustrates a typical VRU system:

graph LR;
    A["Tank"] -->|"Vapors"| B["Vapor Recovery Unit (VRU)"];
    B -->|"Recovered Vapors"| C["Storage Tank or Process"];
    B -->|"Non-Condensable Gases"| D["Flare or Vent"];

VRUs typically consist of the following components:

• Vapor collection system: Captures vapors emitted from the tank.
• Vapor processing system: Processes the collected vapors to recover the desired products.
• Control system: Regulates the VRU's operation and ensures safe and efficient emissions control.

Flare Systems for Safe and Efficient Emissions Management

Flare systems are used to safely dispose of gases that cannot be recovered or processed. Flares are designed to burn the gases, reducing the risk of explosions and minimizing emissions.

The following diagram illustrates a typical flare system:

graph LR;
    A["Tank or Process"] -->|"Gases"| B["Flare System"];
    B -->|"Burned Gases"| C["Atmosphere"];
    B -->|"Flare Tip"| D["Ignition System"];

Flares are designed to operate safely and efficiently, with features such as:

• Flare tip design: Optimized to ensure complete combustion of gases.
• Ignition system: Ensures reliable ignition of the flare.
• Monitoring and control: Allows for real-time monitoring and control of flare operations.

Other Control Technologies for Tank Emissions

Other control technologies for tank emissions include:

• Activated carbon adsorption: Uses activated carbon to adsorb VOCs and other pollutants.
• Thermal oxidation: Uses heat to oxidize VOCs and other pollutants.
• Biofiltration: Uses microorganisms to biodegrade VOCs and other pollutants.

Conclusion

Tank emissions control is a critical aspect of petroleum facility operations. By understanding the importance of tank emissions control, the regulatory framework governing it, and the best practices for minimizing tank emissions, facilities can reduce their environmental impact and improve overall efficiency. By incorporating design considerations, operational practices, and control technologies, facilities can minimize tank emissions and ensure safe and efficient operations.

References

1. EPA: New Source Performance Standards for VOC Emissions from Petroleum Refinery Wastewater Systems
2. EPA: National Emission Standards for Hazardous Air Pollutants for Petroleum Refineries
3. API: Tank Emissions Control

FAQ

Q: What are the main sources of tank emissions in petroleum facilities?

A: The main sources of tank emissions are evaporation of stored products, tank breathing, tank filling and emptying operations, and leaks and spills.

Q: What are the benefits of controlling tank emissions?

A: Controlling tank emissions can reduce environmental impact, improve regulatory compliance, improve operational efficiency, and enhance safety.

Q: What are some common control technologies used to reduce tank emissions?

A: Common control technologies include vapor recovery units (VRUs), flare systems, activated carbon adsorption, thermal oxidation, and biofiltration.

Q: How can facilities minimize tank emissions through design and operation?

A: Facilities can minimize tank emissions by incorporating design considerations, such as tank type and size, sealing and fittings, and vapor recovery systems. Operational practices, such as minimizing tank filling and emptying, monitoring tank levels and pressures, and maintaining tank integrity, can also help reduce emissions.