How to design an ultra long vertical multi-stage semi submersible long shaft deep well turbine pump with an underwater depth of up to 100 meters or even longer?

The design of ultra long vertical multi-stage semi submersible long shaft deep well turbine pumps with an underwater depth of up to 100 meters or even longer requires breaking through the structural limits of conventional pumps, focusing on solving core challenges such as long shaft stability, sealing reliability, material corrosion and fatigue resistance, and maintenance feasibility under deep liquid conditions. At present, ultra long vertical multi-stage semi submersible long shaft deep well turbine pumps are mainly used in extreme engineering scenarios such as deep well water intake, seabed mining, and deep-sea drilling platform ballast systems.
1、 Core structural design: the key to achieving 100 meter underwater operation
Segmented long axis and multi-stage support system
·The shaft system adopts segmented stainless steel or titanium alloy long shaft (single section ≤ 10 meters), connected by high-strength flanges or sleeve couplings to ensure assembly accuracy and coaxiality.
·Set up a guide bearing pivot point every 3 meters, equipped with wear-resistant shaft sleeve and lubricating water film, effectively control radial runout (≤ 0.08mm/m), absorb long axis swing energy, and control vibration amplitude within ≤ 0.05mm (working condition at a water depth of 100 meters).
·The guide bearing material is made of silicon carbide, polytetrafluoroethylene composite material or ceramic matrix composite material, which has self-lubricating and wear-resistant characteristics, and the service life can reach more than 15000 hours.
Multi stage impeller boosting and fluid dynamics optimization
·Adopting a multi-stage centrifugal impeller series structure, the pressure is gradually increased, with a total head of up to 300 meters and a flow range of 10-2000 m ³/h, meeting the high head transportation needs of deep wells.
·The impeller and guide housing have been optimized through hydraulic simulation design to improve efficiency and reduce cavitation risk, and are suitable for complex media with sediment content ≤ 5mm.
High pressure sealing and leak prevention system
·Equipped with a three-stage series mechanical seal (SiC sealing ring), with a pressure capacity of ≥ 10MPa and a leakage rate of<0.1ml/h.
·Inject anti scaling lubricating fluid (such as ethylene glycol solution) into the sealed chamber to prevent deep well high-temperature scaling and extend the sealing life.
·Optional sealless design (media self-lubricating or magnetic coupling drive), completely eliminating the risk of leakage, suitable for highly toxic and flammable media.
Application of corrosion-resistant and high-strength materials
·The main shaft and pump casing are made of 316L stainless steel or titanium alloy (tensile strength ≥ 550MPa), which is resistant to seawater corrosion and high torque loads.
·The impeller is made of duplex stainless steel 2205, which is resistant to chloride ion corrosion (Cl ⁻ ≤ 50000ppm) and suitable for harsh marine and chemical environments.
2、 Adaptive design for deep-sea and ultra deep well operating conditions
·Pressure resistant shell structure: The pump body shell is designed to withstand a pressure of ≥ 15MPa and is suitable for underwater operations below 300 meters; The titanium alloy pump casing can withstand a pressure of ≥ 30MPa and support extreme working conditions such as underwater manganese nodule mining.
·Modular withdrawable design: The rotor components can be extracted as a whole without disassembling the pipeline, making it easy to inspect on the well and significantly reducing maintenance difficulty and costs.
3、 Typical application scenarios
·Deep well water extraction and oil reinjection: used for extracting clean water or sand containing liquids from underground wells up to 100 meters deep, supporting continuous high head transportation.
·Subsea mineral development: discharge of ballast water from deep-sea drilling platforms, cleaning of subsea pipelines (high-pressure water jet pressure ≥ 15MPa).
·Bottom pumping of large storage tanks: Extracting residual liquid from the bottom of crude oil and chemical liquid storage tanks to avoid the risk of manual tank cleaning.
·Emergency drainage in extreme environments: such as mine collapses, tunnel flooding, and other rescue operations in 100 meter deep wells.