The function of the steam turbine main EH oil tank is to collect and distribute the lubricating oil return from various parts of the steam turbine. At the same time, the water vapor in the oil and the gas carried in the return oil are discharged from the factory through the exhaust fan of the oil tank. The main oil tank is also connected to an oil purification device to further treat impurities in the oil and ensure the quality of the oil.
Due to the inclusion of mechanical impurities in the oil flowing back from the steam turbine to the EH oil tank, these impurities may be products of wear and tear on the bearing shells, speed control oil valves, and turning gear, as well as welding slag and metal oxide scales left in the bearing box and oil system during manufacturing, installation, and maintenance. Sometimes there is steam leakage at the shaft end, and a portion of water will also be mixed in the oil. Therefore, the purification of turbine oil by the main oil tank is of great significance. These impurities can be filtered, precipitated, and separated in the oil tank to avoid being sent back into the oil system.

The main EH oil tank is generally welded from steel plates. There are two layers of filters inside the oil tank, which filter out impurities in the oil and reduce the flow rate of the oil. The bottom of the fuel tank is tilted to quickly drain the separated water, sediment, or other impurities from the bottom drain pipe. An air filter is installed on the top of the fuel tank to effectively dehumidify and prevent water and particles from entering the EH oil tank.

Generally speaking, the main EH oil tank air filter needs to meet the following requirements:

Efficient filtration: the filters need to be able to filter out most impurities and particles in the air to ensure that the oil in the fuel tank is not contaminated.

Low pressure drop: The design of the air filter should minimize the pressure loss when air passes through, to ensure that air can smoothly enter the fuel tank.

Corrosion resistance: The materials of air filters need to have good corrosion resistance to cope with high humidity and high temperature environments.

Easy to maintain: it requires regular cleaning or replacement, so the design should consider easy disassembly and maintenance.

The air filter BR110 is the most commonly used air breather for the main oil tank of steam turbines. When the air passes through the desiccant, the water is absorbed. After passing through the desiccant, the solid particles in the air are removed through the air filter element EF4-50, which can effectively prevent the water and solid particles from entering the oil tank due to the pressure difference caused by the rise and fall of the liquid level and thermal expansion, effectively improve the working performance and reliability of the hydraulic system, and extend the service life of the oil and equipment.

The effectiveness of the BR110 filter element is mainly reflected in three aspects:

The use of efficient filtering materials and structural design can effectively filter impurities such as moisture, dust, and particles in the air, providing cleaner air.

The material of the filter element has been treated to have anti-corrosion, antibacterial and other characteristics, extending the service life of the filter element.

It has high filtration efficiency and air flow rate, and will not have a negative impact on engine performance.