What is the use of the seal oil system in a thermal power plant?

Purpose of Sealing Oil Systems in Thermal Power Plants

In thermal power plants, the sealing oil system (Sealing Oil System) is primarily used to ensure the normal operation of hydrogen-cooled generators. Specifically, the sealing oil system's main purpose is to prevent hydrogen leakage from the generator and to stop outside air from entering the generator. Below are the detailed uses and functions of the sealing oil system:

1. Preventing Hydrogen Leakage

• Hydrogen Cooling: Many large generators use hydrogen as a cooling medium because it has excellent thermal conductivity, effectively removing the heat generated inside the generator. This improves the generator's efficiency and reliability.

• Sealing Function: The sealing oil system provides a high-pressure oil film to the sealing wedges at both ends of the generator, creating a barrier that prevents hydrogen from leaking out of the generator into the external environment. This ensures safe operation and reduces hydrogen loss.

2. Preventing Outside Air Ingress

• Maintaining Hydrogen Purity: If outside air enters the generator, it can dilute the hydrogen, reducing its cooling effectiveness and leading to increased temperatures inside the generator, which could damage the equipment.

• Explosion Prevention: Hydrogen is a flammable gas, and mixing with air can create an explosive mixture. The sealing oil system isolates outside air, thereby minimizing this potential explosion risk.

3. Lubrication and Cooling of Sealing Wedges

• Lubrication: The sealing oil system not only serves as a seal but also provides necessary lubrication to the sealing wedges at both ends of the generator, reducing friction and wear, thus extending the life of the sealing wedges.

• Cooling: As the sealing wedges operate under high-speed rotation, they generate significant heat. The sealing oil system removes this heat through circulating oil, keeping the sealing wedges within a safe operating temperature range.

4. Oil Pressure and Flow Control

• Pressure Regulation: The sealing oil system includes oil pumps, pressure regulators, and monitoring devices to ensure that the oil pressure is always higher than the hydrogen pressure inside the generator. This effectively prevents hydrogen leakage.

• Flow Control: The system also includes flow control devices to ensure the right amount of oil flows through the sealing wedges, meeting sealing requirements without wasting oil or placing unnecessary strain on the generator.

5. Monitoring and Alarms

• Real-Time Monitoring: Modern sealing oil systems are equipped with sensors and monitoring devices to continuously monitor parameters such as oil pressure, oil temperature, and oil level, ensuring the system operates normally.

• Fault Alarms: When the system detects abnormalities (such as low oil pressure or high oil temperature), it triggers alarm signals to alert operators to take timely action and prevent accidents.

6. Maintenance and Inspection

• Regular Inspections: To ensure the long-term stable operation of the sealing oil system, regular inspections and maintenance are required, including filter replacement, oil replenishment, and tank cleaning.

• Preventive Maintenance: Based on equipment operating time and condition, preventive maintenance plans are developed to identify and address potential issues in advance, preventing sudden failures.

Summary

The primary purpose of the sealing oil system in thermal power plants is to ensure the safe and efficient operation of hydrogen-cooled generators. It prevents hydrogen leakage and outside air ingress, maintaining the purity and cooling effectiveness of hydrogen inside the generator. Additionally, it provides essential lubrication and cooling to protect the sealing wedges from excessive wear and high temperatures. Furthermore, the sealing oil system features real-time monitoring and alarm functions to ensure reliability and safety.