In modern thermal power plants, the fire-resistant oil (EH oil) of the turbine regulating system is one of the core media to ensure the safe and stable operation of the unit. As a key component in the EH oil system, the air permeability design of the main oil pump inlet filter element HQ25.200.11Z-1 directly affects the transmission efficiency and system reliability of the fire-resistant oil. However, the foam characteristics of fire-resistant oil pose a unique challenge to the air permeability of the filter element. This paper will start from the foam characteristics of fire-resistant oil, deeply analyze its special requirements for the air permeability design of the filter element, and explore the corresponding technical optimization path.

1. Fire-resistant oil foam characteristics and their impact on the system

Foam is easy to form under high temperature, high pressure and mechanical shear force. The formation of foam is mainly due to the following mechanisms:

Air entrainment: tiny bubbles are mixed into the oil during the circulation process;

Chemical stability: degradation of additives leads to reduced surface tension;

Mechanical disturbance: pump body or valve action causes violent flow of oil.

The presence of foam can lead to the following problems:

Air blocking effect: bubbles accumulate inside the filter element, hindering the normal flow of oil and reducing the suction efficiency of the pump;

Accelerated oxidation: foam increases the contact area between oil and air, exacerbating oil quality deterioration;

Pressure fluctuation: compression and expansion of bubbles in the oil cause system pressure pulsation, threatening the adjustment accuracy.

These characteristics require that the filter element design must take into account both air permeability and foam suppression capabilities to ensure stable operation under complex working conditions.

2. Basic requirements for filter element air permeability design

Air permeability is the core indicator for measuring filter element performance and must meet the following basic conditions:

High-efficiency filtration: intercepting particulate pollutants;

Low pressure drop: maintaining oil flow resistance within the allowable range of the system (generally less than 0.15MPa);

Long-term stability: high temperature resistance (EH oil operating temperature can reach above 60°C) and chemical corrosion resistance.

However, under the influence of the foam characteristics of fire-resistant oil, traditional air permeability design needs to be further optimized to cope with the additional challenges brought by foam.

3. Special requirements of fire-resistant oil foam characteristics on the air permeability design of filter elements

1. Layered air permeability structure design

Conventional filter elements use homogeneous filter materials, but fire-resistant oil foam is easy to form an air film on the surface of the filter material, resulting in a sudden drop in local air permeability. For this reason, the HQ25.200.11Z-1 filter element adopts a multi-layer gradient pore structure to achieve a dynamic balance of “foam interception-gas escape-oil penetration” through physical stratification.

2. Synergistic effect of composite filter materials

The composite structure of glass fiber and polyester fiber is used to increase mechanical strength while improving surface roughness and inhibiting foam aggregation.

3. High-precision welding process

The laser micro-melting technology is used for welding the filter element pleats to avoid local flow dead zones. The weld surface has good polishing and reduces bubble nucleation points.

When looking for high-quality, reliable steam turbine oil filters, YOYIK is undoubtedly a choice worth considering. The company specializes in providing a variety of power equipment including steam turbine accessories, and has won wide acclaim for its high-quality products and services. For more information or inquiries, please contact the customer service below:
E-mail: sales@yoyik.com
Tel: +86-838-2226655
Whatsapp: +86-13618105229

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