1. How Does an Axial Flow Pump Work?
First of all, the fluid to be pumped enters through the pump's suction port and reaches the elbow of the pump, where it comes into contact with the impeller blades. The rotation of the impeller causes the fluid to move axially. Key parameters such as the impeller diameter, rotation direction, and blade angle jointly determine the pump's flow rate, fluid direction, and pressure output. As the blades rotate, they convert the fluid's kinetic energy into pressure energy, thereby increasing the fluid pressure proportionally with the increase in rotational speed. Once the fluid reaches the desired pressure level, it is discharged through the impeller outlet of the axial flow pump.
In summary, the axial flow pump accelerates the fluid from the suction end to the discharge end through the rotational movement of its impeller blades. Due to this working principle, the axial flow pump is an ideal choice for applications that require high flow rates while maintaining a relatively low discharge pressure.
2. What Is the Structure of an Axial Flow Pump?
An axial flow pump primarily consists of a pump casing (or pump elbow), an impeller, a pump shaft, and a mechanical seal. The impeller is mounted at the pump inlet, while the pump elbow serves as the outer housing, enclosing all internal components. Together, these parts work to direct fluid flow and generate pressure within the pump.
2.1 Suction & Discharge
The suction and discharge directions of the axial flow pump can be customized according to customer requirements, and they can be interchanged. Usually, this pump adopts a structure of suction at the end and discharge at the top, but there are also other configurations available to meet specific application needs.
2.2 Impeller
The impeller is the core component of an axial flow pump. Its characteristic is that multiple inclined blades are installed on a central hub. When the pump shaft rotates, the design of the blades will interact with the fluid, thereby forming a directional flow along the axial path of the pump.
2.3 Pump Bearings
The pump shaft is the central component of the entire rotating system, supporting the impeller and mechanical seal. Its diameter and structural strength must be precisely designed to withstand the stresses generated during operation. The bearing system plays a dual critical role: maintaining the precise alignment of the rotating components (impeller and mechanical seal), and reducing rotational friction. The bearing configuration used for different pumps varies greatly, and each design is customized according to specific load and performance requirements of the axial flow pump.
2.4 Sealing System
The shaft seal is of vital importance at the connection point between the pump elbow pipe and the rotating shaft in an axial flow pump. Its function is to prevent liquid leakage. Currently, there are mainly two sealing methods: mechanical seal and packing seal. However, the packing seal no longer meets modern environmental protection standards, while the mechanical seal has become the preferred solution in the industry due to its outstanding sealing reliability (especially when dealing with chemical solutions).
2.5 Bearing Housing & Base Plate
The bearing housing of the axial flow pump serves as the installation structure for the pump bearings and the rotating shaft, and also provides a connection interface for the pump casing (often referred to as the pump elbow pipe). The base plate acts as the foundation support platform, integrating all the main pump components such as the pump casing, the bearing housing, and the prime mover (such as an electric motor or diesel engine) into a complete unit.
2.6 Seal Flushing System & Bearing Lubrication
To prevent the axial flow pump from being damaged due to high temperature, a reasonable flushing plan must be formulated to cool the mechanical seal chamber and dissipate the accumulated heat. Moreover, for the bearings that support the shaft, adequate lubrication is crucial because they generate a large amount of friction heat during operation - the bearing housing must be filled with lubricating oil up to the specified level to ensure that both bearings and the shaft components are adequately lubricated, thereby achieving optimal performance.
2.7 Driving Unit
The rotation of the impeller is powered by the drive unit, which transmits torque through a coupling that connects the drive shaft and the pump shaft. Axial flow pumps can be connected to various drive devices, including electric motors, diesel engines or turbines, to meet the specific needs and application requirements of different customers.
3. Characteristics & Advantages of Axial Flow Pumps
Axial flow pumps are specifically designed for high-capacity and low-head applications, and can efficiently convey large volumes of fluid with relatively low discharge pressure. Their optimized design enables effective handling of large flow rates while maintaining energy-efficient operation.
3.1 Higher Efficiency
3.11 Less Dynamic Loss. The axial flow pump's impeller features shorter blades that minimize fluid rotation, thereby reducing dynamic losses and improving hydraulic efficiency.
3.12 Specialized Design. The axial flow pump adopts advanced dynamic design principles. The configuration of the impeller and guide vanes has been optimized to minimize the turbulence and impact losses within the pump casing (pump elbow). This meticulously designed approach ensures that the fluid flow throughout the entire pump chamber is extremely smooth.
3.13 Higher Energy Conversion. During operation, the axial-flow pump uniformly sucks the liquid into the rotating impeller through its suction port. Here, the mechanical energy of the driving device is converted into pressure energy and kinetic energy through centrifugal force. Subsequently, the guide vanes efficiently direct this energy-rich fluid through the pump casing (elbow) and reduce energy loss, thereby achieving the usually high efficiency of this system.
3.14 Excellent Sealing & Lubrication Systems. The mechanical seals in the axial flow pump play a crucial barrier role, preventing contaminants from entering the pump casing. At the same time, the lubricating oil in the bearing box can maintain the stability of the shaft, reduce friction during operation, and improve energy efficiency throughout the pumping process.
3.2 Multi-purpose Applications. Axial flow pumps have extensive applications in various industries, including flood control systems, water conservancy projects, environmental protection projects, and chemical production processes, etc.
3.3 Low-Maintenance Design: Axial flow pumps feature a simplified construction with fewer core components, significantly reducing maintenance requirements compared to centrifugal pump systems.
3.4 Performance Adjustability Some axial-flow pumps are equipped with propeller blades driven by hydraulic power. These blades can be dynamically adjusted during operation to meet different flow requirements. This real-time control of blade angles can achieve optimal performance under various operating conditions and maintain the pump's efficiency.
3.5 Structural Customizability: The axial flow pump offers fully customizable installation configurations to meet the specific requirements of each project. It includes various drive options (direct coupling, gearbox drive, V-belt drive or pipe installation) as well as adjustable vertical column lengths designed according to the specific requirements of the customers. This flexible design approach ensures optimal integration with existing systems while meeting unique space needs.
4. Where the Axial Flow Pumps Can be Used?
4.1 Chlor-alkali Application: Chemical axial flow pumps meticulously manufactured using titanium alloys or super duplex stainless steels possess outstanding corrosion resistance when handling corrosive media such as caustic soda, chlorine alkali, and brine solutions. They can maintain stable performance even at temperatures as high as 130°C. These robust materials ensure reliable operation in the most demanding chlor-alkali processing environments.
4.2 Lithium Battery Application: The rapid growth demand in the electric vehicle industry has made high-flow axial flow pumps extremely important in the processing of lithium, as their outstanding flow capacity can effectively promote the crystallization of lithium carbonate. These specialized pumps perform exceptionally well in lithium-rich brine concentration and solvent recovery systems, providing reliable forced circulation performance, which is crucial for efficient production of battery materials.
4.3 Fertilizer Production Application: The high-efficiency axial flow pump is the preferred solution for the ammonium nitrate and urea evaporation system. In multi-effect evaporators, its large flow design significantly improves the heat transfer efficiency. By optimizing the forced circulation performance, these pumps can reduce energy consumption compared to traditional pumps, thereby directly enhancing the operational efficiency of the fertilizer production process.
4.4 MVR & ZLD Application: Axial flow pumps are highly efficient circulation pumps suitable for demanding industrial applications. These applications include MVR/ZLD multi-effect evaporators for treating high-salinity wastewater and large-scale heat exchange systems that require a large capacity for cooling water circulation. Their robust design ensures reliable operation when handling liquids with high total dissolved solids (TDS), and they can also save energy while maintaining high efficiency.
4.5 Evaporation Crystallization: Axial flow pumps are Specifically designed for precision evaporation systems, the low-speed chemical axial flow pump provides an ideal circulation system for applications sensitive to crystals (such as salt-water concentration and pharmaceutical production). Its gentle pumping action (operating range of 50 - 70 revolutions per minute) can maintain fluid flow while not damaging the integrity of the crystal structure, and its corrosion-resistant construction ensures reliable performance even when in contact with strong acidic chemical solutions.
4.6 Irrigation and Flood Management Solutions: Vertical and horizontal axial flow pumps are widely used in agricultural and flood control applications due to their strong water transportation capacity, which enables them to quickly convey large volumes of water under high-efficiency requirements.
4.7 Wastewater Treatment Application: Axial flow pumps are key components in wastewater treatment plants. With their high flow capacity and anti-clogging design, they can achieve efficient transportation of wastewater between treatment stages. These chemical axial flow pumps can reliably handle raw sewage containing up to 5% solids, while maintaining 20% to 30% higher energy efficiency compared to traditional solutions. Therefore, they are highly suitable for continuous operation processes such as primary treatment, aeration, and final discharge.
4.8 Application in Shipyards and Terminals: Vertical axial flow pumps are indispensable drainage equipment in shipyards and terminals. With their powerful drainage capacity, they can efficiently remove accumulated water during the start-up and maintenance operations of ships.
4.9 Application in Shrimp Farming: Axial flow pumps are highly suitable for shrimp farming operations. Due to their high pumping capacity, they can meet the urgent need for rapid water exchange in both saltwater and freshwater farming systems.
