Mixed-flow pumps and axial-flow pumps are frequently used in the forced circulation evaporators of salt solutions.
The differences between the two and the selection precautions are as follows:
I. Differences in parameters between the two:
A: The mixed-flow pump is available in medium-flow and low, medium, and high head series (low head 2 - 5.4 meters, medium head 4 - 14 meters, high head 7 - 34 meters). The mixed-flow pump is horizontally fed and vertically discharged. The mixed-flow pump has excellent anti-suction erosion performance.
B: The axial flow pump is a series for high flow rate and low head (the head cannot exceed 4.5 meters). The pump is fed from the top and discharges horizontally. The axial flow pump has almost no suction head.
2: Differences in performance between the two:
A: The mixed-flow pump low-head series is suitable for low-resistance evaporation devices with low head requirements such as single-heater chambers and low-position evaporation chambers (where the evaporation chamber is lower than 10 meters and the installation height of the evaporation device is low), as well as forced circulation evaporation devices with multiple-heater chambers or multi-mode heating chambers. The medium-head series is suitable for new types of evaporators such as those with double-heater chambers connected in series or with multiple heating chambers, as well as forced circulation evaporation devices and reverse circulation evaporation devices with high viscosity and high circulation resistance, and also for evaporation devices for concentrating high-viscosity materials. The mixed-flow pump can be applied to various low-resistance and high-resistance evaporation devices and evaporation devices with high viscosity and high circulation resistance due to its multiple head options. Additionally, it is suitable for small processing volumes, low circulation volumes, and low installation heights (below 10 meters) of evaporation devices because of its high suction head and the ability to resist vacuum. The high-head series is generally only suitable for transporting large volumes of materials and corrosive media with certain particles, and is not suitable for evaporation devices under vacuum conditions.
B: The axial-flow pump is only suitable for low-resistance evaporators with low head requirements in single-heater chambers and high-position evaporation chambers (where the evaporation chamber is higher than 10 meters and the installation height of the evaporation device is high). The axial-flow pump is not suitable for multi-mode heating chambers or forced circulation evaporation devices with high viscosity and high circulation resistance, nor for reverse circulation evaporation devices because of its low suction head and lack of the ability to resist vacuum. It is suitable for evaporation devices with large processing volumes, high circulation volumes, and high installation heights (above 10 meters) and low circulation resistance.
3: Differences in device usage between the two:
A: The mixed-flow pump has excellent anti-suction cavitation performance. It has a certain suction head and the ability to withstand vacuum. Under high vacuum conditions, the installation height of the device can be reduced by at least 4-5 meters compared to the axial-flow pump. This can lower the cost of the foundation steel platform and concrete structure, reduce the length of the connecting and inlet/outlet pipelines for the pump in the separation chamber and heater, and lower the overall cost of the equipment. This results in a lower overall cost and also enhances the convenience of installation and construction, and increases the importance of installation and construction.
B: The axial-flow pump has almost no suction head and has high requirements for the installation height of the device. Due to its low manufacturing difficulty and less material usage compared to the mixed-flow pump, the overall cost of the axial-flow pump is lower than that of the mixed-flow pump. It is more suitable for devices with large flow and large processing capacity.
4: The similarities between the two:
The stable shaft power characteristics show that the mixed-flow pump has higher efficiency than the axial-flow pump. The axial-flow pump has a lower head. The final matching power difference is not significant, and the energy-saving difference is also not significant. The mechanical seals are all of the integrated type, which are easy to install, have a long service life, and good reliability. The pump body is supported at the center, and the thermal alignment is good. The pump shaft is thick, with good rigidity, and it has three-disc bearings. The bearing housing is water-cooled for adequate cooling. The operation is more stable and it is suitable for single pump continuous operation. The installation methods can be selected from multiple options, such as direct motor connection, belt drive, spring-type base, and suspended installation.
