As the core power equipment in thermal power generation, chemical production and ship propulsion, the operation stability of steam turbines is directly related to the efficiency and safety of the entire system. As the “central nervous system” of the hydraulic control system of steam turbines, the pressure regulating valve group undertakes the key task of accurately regulating steam flow and pressure. In the pressure regulating valve group, the filter element is the “purification barrier” of hydraulic oil, and its performance status is often underestimated. Once the filter element fails, it will not only cause hydraulic system pollution, but also trigger a chain reaction such as decreased control accuracy of the unit, regulation lag and even unplanned shutdown. This article takes the LH0110D010BN/HC oil filter element as an example, starting from the technical mechanism, control logic and actual cases, and systematically analyzes the potential threat of filter element failure to steam turbine control accuracy.

1. Functions and design features of LH0110D010BN/HC filter element

The hydraulic oil filter element LH0110D010BN/HC is a precision filter element specially used for steam turbine pressure regulating valve group. Its core functions include:

•  - Oil purification: filter metal particles, colloidal precipitation and other pollutants in hydraulic oil (the filtration accuracy is usually 10μm) to ensure the reliability of the action of the pressure regulating valve actuator;
•  - Pressure buffering: balance the oil pressure fluctuation through the internal multi-layer filter material structure to reduce the instantaneous interference of hydraulic shock on the valve;
•  - System protection: prevent foreign matter from entering the servo valve, proportional valve and other precision components to avoid valve core jamming or wear.

This type of lube oil filter element adopts high-strength glass fiber composite material and stainless steel skeleton composite process, which has the characteristics of high temperature resistance, high pressure resistance and long life. However, in actual operation, factors such as oil contamination, mechanical vibration and maintenance omissions may cause it to fail prematurely.

2. Typical modes and causes of filter element failure

The failure of LH0110D010BN/HC hydraulic filter elements is mainly manifested in the following two categories:

1. Blockage failure

Cause: The filter element has not been replaced for a long time or the oil pollution exceeds the standard, resulting in the accumulation of impurities on the surface of the filter material and the pressure difference exceeding the design threshold.

Features: The oil circuit flux decreases, the response speed of the pressure regulating valve decreases, and the load of the hydraulic pump increases.

2. Structural failure

Cause: The bypass valve opens abnormally due to damage to the filter material, aging of the sealing ring or improper installation.

Features: Contaminants directly enter the downstream system, the probability of servo valve jamming increases, and the control signal and valve action deviate.

Statistical data show that among the unplanned shutdown events of steam turbines, about 35% are related to hydraulic system pollution, of which filter element failure accounts for more than 60%.

3. The direct impact of filter element failure on control accuracy

When the filter element is blocked, the hydraulic oil flow is limited, the full stroke action time of the pressure regulating valve is extended, and the main steam pressure fluctuation amplitude is enlarged.

On the other hand, if the filter fails structurally and causes oil contamination, the servo valve core may not be able to accurately follow the control command due to particle jamming. In addition, the hydraulic hysteresis caused by filter failure and the superposition of valve nonlinear characteristics may cause the entire pressure control loop to fall into continuous oscillation, and even force the unit to operate at reduced load.

4. Prevention and response strategies

1. Strengthen status monitoring: Real-time monitoring of the pressure difference before and after the filter element, set the warning threshold; regularly test the oil cleanliness and strictly follow the NAS 1638 standard.

2. Optimize maintenance management: shorten the filter element replacement cycle according to the operating environment; use the “pressure difference – time” dual dimension to judge the filter element life to avoid excessive maintenance or failure risks caused by fixed cycles.

3. System design improvement: Add redundant filter elements or parallel filter circuits to the pressure regulating valve group to improve the system’s fault tolerance; upgrade the filter element material to extend the service life under harsh conditions.

Although the LH0110D010BN/HC filter element is a small component, its failure has a diffusion-like “butterfly effect” effect on the control accuracy of the steam turbine. From pressure fluctuations to regulation lag, from valve jamming to system oscillation, the accumulation of deviations in each link may evolve into major operational risks. As the power industry moves towards the goal of “zero unplanned downtime”, only by incorporating filter element management into the refined maintenance system can the accuracy and reliability of the steam turbine control system be fundamentally guaranteed.

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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