In the lubricating oil system of the generator set of a large power plant, the three-screw pump HSNH210-46ZA, as the core power equipment, bears the important responsibility of stably delivering lubricating oil and ensuring the safe operation of the unit. Its unique axial force balance design can effectively solve the vibration and wear problems caused by pressure fluctuations in traditional positive displacement pumps, and has become a typical representative of high-efficiency fluid transportation in the modern industrial field.

1. Structure and working principle of the three-screw pump HSNH210-46ZA

The screw pump HSNH210-46ZA adopts a three-screw meshing structure, which consists of an active screw and two driven screws. During operation, the active screw is driven by the motor to rotate, driving the driven screw to run synchronously to form a continuous and closed spiral chamber. After the lubricating oil is sucked from the inlet end, it is transported to the outlet without pulsation under the axial displacement of the spiral chamber, and the flow stability can reach within ±1%. Its design flow rate is 200L/min, working pressure is 1.0MPa, and it is compatible with 5.5KW motor power, which can meet the needs of power plant lubrication system for high pressure and large flow.

The generation of axial force is due to the thrust difference of the screw end face under the action of high-pressure oil. If it is not effectively balanced, it will cause problems such as bearing overload and seal failure. HSNH210-46ZA introduces high-pressure oil into the end cavity of the screw through hydraulic balancing technology, forming a reverse thrust to offset the axial load, so that the force of the master and slave screws reaches dynamic balance. This design reduces the axial force fluctuation to less than 20% of the traditional pump type, significantly extending the service life of the equipment.

2. Analysis of the core technology of axial force balance

Hydraulic balancing system

The balancing system of the lubricating oil pump HSNH210-46ZA includes three key components: balancing piston, pressure oil channel and oil return structure. The balancing piston is installed at the end of the active screw, and the thrust is precisely controlled by adjusting the oil pressure. High-pressure oil is introduced into the balance chamber through a dedicated channel, and its pressure value is automatically adjusted through the feedback mechanism inside the pump body to ensure that the axial force can be maintained stable under different working conditions. This design reduces the bearing load by more than 60%, while avoiding mechanical shock caused by sudden pressure changes.

Bearing and seal collaborative design

The screw pump HSNH210-46ZA provides two bearing configuration options: built-in (model N) and external (model W1). The power plant scene mostly adopts an external bearing structure, and the bearing is isolated from the conveying medium through an independent lubrication system, which not only prevents lubricating oil contamination, but also facilitates maintenance. The mechanical seal is made of carbide and combined with the low-pressure environment of the balance oil chamber to achieve zero leakage operation. The measured data shows that after the pump has been running continuously for 5,000 hours at 150°C, the sealing performance attenuation rate is less than 3%.

3. Practical advantages in the lubrication system of power plants

Improved operating stability

Through the axial force balancing technology, the vibration amplitude of HSNH210-46ZA is controlled within 0.05mm and the noise is less than 75dB. The application case of a million-kilowatt power plant shows that after replacing the traditional gear pump, the failure rate of the lubrication system dropped by 82%, and the annual maintenance cost was reduced by 350,000 yuan. Its rated speed design of 1450r/min can not only match the speed change requirements of the generator set, but also avoid cavitation caused by excessive speed.

Medium adaptability and energy-saving performance

The pump can transport lubricating oil with a viscosity of 3-760cSt, covering the L-TSA32 to L-TSA68 grades commonly used in power plants. The special spiral surface design makes the volumetric efficiency reach 98%, which is 15%-20% energy-saving compared with similar products. Calculated based on a single unit running for 8,000 hours per year, it can save about 65,000 degrees of electricity, equivalent to 21 tons of standard coal. For recycled lubricating oil containing trace impurities, its wear-resistant bushing design can reduce the wear rate to 0.01mm/thousand hours, greatly extending the overhaul cycle.

Installation and configuration points

The lubricating oil pump HSNH210-46ZA supports horizontal (H type) and flange (F type) installation. The power plant recommends a structure with a thermal insulation jacket to cope with low temperature conditions in winter. It is recommended to configure a 100-mesh filter at the inlet to prevent foreign matter from entering the meshing gap. During commissioning, the pressure needs to be gradually increased to the rated value to avoid instantaneous high pressure impact on the balance system.

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E-mail: sales@yoyik.com
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