Definition, working principle, and typical structural analysis of the vertical long axis semi submersible turbine pump equipment

The Vertical Long Shaft Submersible Pump is a centrifugal pump designed specifically for transporting deep liquid level fluids. Its core feature is the vertical layout structure of the motor on top and the pump body on the bottom. Unlike traditional horizontal centrifugal pumps or submersible pumps, the driving motor of this pump is installed above the liquid level, and the power is transmitted to the impeller immersed in the liquid through a long axis that runs through the pump body, achieving direct extraction of medium from deep wells, storage tanks, pools, or underground facilities. Its working principle is based on the action of centrifugal force: when 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, forming a high-pressure zone; At the center of the impeller, a low-pressure zone is formed, and external liquid continues to flow in under the pressure difference. After being pressurized by multi-stage guide vanes, it is vertically lifted through a lifting pipe and finally discharged through a horizontal outlet, completing the transportation task from deep liquid level to high position.
The structure of the pump consists of four core parts: transmission device, energy conversion, water delivery, and lubrication. The transmission device includes a motor, coupling, and thrust bearing, which are responsible for providing power and bearing the axial force of the rotor; The energy conversion part is composed of impellers and guide vanes, and is the core of realizing the conversion of kinetic energy into compressive energy; The water conveyance section consists of multiple sections of lifting pipes, protective pipes, and flange connectors, forming a medium conveying channel; The lubrication part includes guide bearings, lubrication water system, and shaft sealing device to ensure the stable operation of rotating components. Its typical structure is: the inlet is vertically downward, the outlet is horizontal, installed on a single foundation, the motor is directly connected to the pump body, and when viewed from the motor end, it rotates counterclockwise.
Compared with ordinary centrifugal pumps, the biggest structural difference of vertical long shaft semi submersible turbine pumps lies in their segmented long shaft and multi section lifting pipe design. The long shaft is usually composed of multiple sections of high-strength steel shafts connected by sleeve couplings, with each section up to 3-10 meters in length. It can be flexibly increased or decreased according to the depth of the liquid, solving the problem of transporting and installing ultra long shafts on site. The lifting pipe also adopts a modular design with flange connection, which is easy to disassemble and maintain. To suppress the radial runout and flexural deformation of the long axis under high-speed rotation, a guide bearing is installed every 3-5 meters along the axial direction of the pump body to form a multi-point support system. The material of the guide bearing can be selected from reinforced filled polytetrafluoroethylene, Sarlyn bearings, or nitrile rubber according to the characteristics of the medium. Its design allows for self-lubricating when transporting clean water, but requires external clean cooling water for lubrication and cooling when transporting sewage or corrosive media. In addition, the impeller and guide vanes of the vertical long shaft semi submersible turbine pump can be single-stage or multi-stage, and high head output can be achieved through series combination, with a single pump head of over 250 meters.
It is worth noting that there is a fundamental difference between vertical long shaft semi submersible turbine pumps and "long shaft semi submersible sump pumps" or "submersible pumps". Although the traditional long axis semi submersible sump pump has the same long axis structure, its motor and pump body are separated. The pump body is located underwater, and the motor is located on the liquid surface. However, the new submersible pump integrates the motor and pump body coaxially, completely immersed in the liquid. The installation method of the "dry" motor for the vertical long shaft semi submersible turbine pump gives it unique advantages in terms of explosion prevention, maintenance convenience, and high-temperature adaptability, making it the preferred solution for deep well, high corrosion, and high-risk medium transportation scenarios.