In the sealing oil system of hydrogen-cooled generator sets, the MR98H overflow relief valve is the core component of pressure control, and its connection method with the return oil pipeline is directly related to the hydrogen sealing efficiency and equipment safety. This article will deeply analyze the connection logic and key technical details of the MR98H overflow valve in the double-flow ring sealing oil system from three dimensions: system principle, structural design, and dynamic adjustment.

1. Sealing oil system architecture and functional positioning of the overflow valve

1.1 Operation principle of double-flow ring sealing oil system

The double-flow ring sealing oil system achieves dynamic balance through two independent oil circuits on the air side and the hydrogen side. The air side oil circuit is directly connected to the lubricating oil system and assumes the basic sealing and lubrication functions; the hydrogen side oil circuit forms a closed loop, and the ±0.49kPa differential control of the air side oil pressure is achieved through the balancing valve. In this architecture, the MR98H relief valve mainly undertakes the following core functions:

• Pressure threshold protection: When the system pressure exceeds the set value (usually higher than the hydrogen pressure of 0.084MPa), it automatically opens the pressure relief to prevent the oil pump from overloading
• Dynamic pressure stabilization: Maintain oil pressure stability by adjusting the valve opening to compensate for pressure fluctuations caused by speed fluctuations or hydrogen pressure changes
• Fault isolation: Form a bypass channel under abnormal working conditions to prevent high-pressure oil from impacting precision components such as sealing tiles

2. Specific connection method of MR98H relief valve and return oil pipeline

2.1 Integrated design of air side oil circuit

On the air side oil pump outlet pipeline, the MR98H overflow valve adopts a three-way parallel connection:

• 1. Main oil channel: oil pump outlet → oil cooler → duplex oil filter → differential pressure valve → sealing bearing air side oil tank
• 2. Overflow branch: oil pump outlet → MR98H overflow valve → air side sealing oil tank or vacuum oil tank

This design enables the overflow valve and the differential pressure valve to form a dual adjustment mechanism. When the oil pressure exceeds the differential pressure valve setting value, the MR98H is activated as a secondary protection. At the same time, in the unit equipped with a vacuum purification system, the overflow oil is first introduced into the vacuum oil tank to accelerate the separation of gas and water through injection diffusion.

2.2 Special configuration of hydrogen side oil circuit

The MR98H overflow valve of the hydrogen side oil circuit adopts closed-loop feedback connection:

1. 1. Main circulation path: hydrogen side oil pump → oil cooler → balance valve → sealing bearing hydrogen side oil tank
2. 2. Overflow circuit: oil pump outlet → MR98H overflow valve → defoaming tank → float oil tank

Key technical features:

Defoaming tank interface anti-gas lock: 45° bevel pipe design is adopted when the overflow oil enters the defoaming tank to avoid bubble accumulation

Float valve linkage control: The automatic oil replenishment and discharge valve in the float oil tank forms a dynamic balance with the overflow volume to maintain the oil level within the range of ±50mm

3. Pressure-flow coordinated control in dynamic operation

3.1 Response to special working conditions in the start-stop stage

Cold start stage: Establish initial oil pressure through the overflow valve bypass to avoid overload of the oil pump motor

Emergency shutdown protection: When the DC standby pump is started, the overflow valve must respond to the sudden change in pressure within 0.5 seconds, and the discharge flow can reach 120% of the rated value

3.2 Adaptive regulation under hydrogen pressure fluctuations

Experimental data show that when the hydrogen pressure drops sharply from 0.3MPa to 0.2MPa, the differential pressure valve completes the main adjustment within 2 seconds. Then the MR98H relief valve assists in releasing excess oil and stabilizes the oil-hydrogen pressure difference within the range of 0.056±0.02MPa.

The precise connection design of the MR98H relief valve and the return oil pipeline reflects the high degree of integration of mechanical, hydraulic and control disciplines in modern power generation equipment. With the application of digital twin technology, the pipeline layout can be further optimized through three-dimensional dynamic simulation in the future, so that the safety margin of the sealing oil system can be increased to more than 99.99%. This exquisite system integration is the core code to ensure the efficient and stable operation of hydrogen-cooled generator sets.

When looking for high-quality, reliable relief valves, 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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