Design principle and application maintenance of vertical submersible multi-stage long shaft turbine pumps

1、 Design Technology
The design of the vertical submersible multi-stage long axis turbine pumps focuses on high reliability, corrosion resistance, and long axis stability, and is suitable for harsh working conditions such as deep wells, chemical storage tanks, and mine drainage. The key technologies include:
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Segmented long shaft structure: made of high-strength alloy steel (such as 316L stainless steel, titanium alloy), with a single section length of up to 10 meters. Modular connection is achieved through sleeve couplings, making it easy to transport and install, and suitable for underwater depths of 30-400 meters. The shaft body has undergone mirror polishing treatment, with radial runout controlled at ≤ 0.08mm/m, significantly suppressing vibration.
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Multi stage segmental pump body: composed of an inlet section, multiple intermediate sections (including impellers and guide vanes), and an outlet section clamped by high-strength screws, forming a detachable modular structure for easy maintenance and replacement of vulnerable parts. Each level of independent hydraulic unit can be independently optimized to improve overall efficiency.
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Hydraulic model and axial force balance: Adopting the IS type high-efficiency and energy-saving hydraulic model, the impeller is a closed structure, and the front cover plate is equipped with a balance hole to achieve hydraulic self balance of most axial forces; The residual axial force is borne by thrust bearings (angular contact ball bearings or double row tapered roller bearings), lubricated with grease or thin oil, and can be connected to an external cooling water system.
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Materials and corrosion-resistant design:
·Impeller and guide vanes: Made of duplex stainless steel 2205, ceramic coating or high chromium cast iron, resistant to sand containing media (≤ 30% solid content) and corrosive environments with pH 3-14.
·Pump casing: Fluorine plastic lining+316L shell composite structure, suitable for extreme media such as concentrated sulfuric acid and cyanide solution.
·Guide bearing: filled with polytetrafluoroethylene (PTFE), Teflon or nitrile rubber, self-lubricating when transporting clean water, and requiring external cooling water when transporting sewage.
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International standard compliance: The design complies with API 610 (Petroleum and Chemical Industry), ISO 5199 (Universal Centrifugal Pumps), and EN 733 (Vertical Pumps) standards, ensuring global universality of structural strength, sealing performance, and testing specifications.
2、 Working principle
The pump is based on a multi-stage series boosting mechanism driven by centrifugal force, achieving efficient vertical transportation of deep liquid level:
1. No filling start: The impeller is always immersed in the liquid, without the need for water intake or vacuum pumping, and can be started directly to avoid cavitation and air resistance.
2. Energy conversion: The motor drives the long shaft to drive the impeller to rotate at high speed. The liquid is thrown from the center of the impeller to the edge under the action of centrifugal force, and the kinetic energy is converted into pressure energy, which is collected by the guide vanes (energy conversion device) and guided to the inlet of the next impeller.
3. Multi stage boosting: Each stage impeller and guide vane form a boosting unit, and the liquid is sequentially connected in series through multiple stages, with pressure added step by step, achieving a hundred meter head output (typical head range: 24-240m).
4. Axial force balance mechanism:
·Hydraulic balance: The impeller balance hole tends to balance the pressure in the front and rear chambers, offsetting most of the axial thrust.
·Mechanical balance: The residual axial force is borne by the thrust bearing, and some high-end models adopt a thrust disc+balance chamber structure to achieve active force balance and extend the bearing life.
5. Lubrication and cooling:
·Lubrication of guide bearings: In clear water medium, liquid self-lubricating; In sewage or media containing impurities, it is necessary to connect clean cooling water externally and form an independent lubrication channel with the guide bearing body through a protective tube.
·Shaft seal cooling: Double end mechanical seals (silicon carbide/silicon carbide) are equipped with a flushing fluid circulation system to prevent particle deposition and overheating wear.
3、 Key points of engineering application and maintenance
·Applicable scenarios: municipal water supply and drainage, acid and alkali transportation in chemical plants, extraction of tailings slurry from mines, fire pressure boosting in high-rise buildings, and seawater desalination systems.
·Installation points: Ensure that the motor seat is coaxial with the pump body, the verticality deviation of the lifting pipe is ≤ 0.5 °/m, and the lubrication water pressure of the guide bearing is ≥ 0.2MPa.
·Maintenance cycle:
·Every 500 hours: check the leakage of the shaft seal and the flow rate of lubricating water;
·Every 2000 hours: replace the guide bearing and sealing ring;
·Every 10000 hours: Conduct a comprehensive inspection of the impeller and shaft wear.