There is growing demand in the area of flue gas cleaning, gas scrubbing or surface cleaning for vertical submersible pumps that can cope with high delivery pressures. These types of pumps are necessary to enable more reliable operating sequences and faster cleaning processes.
However, state-of-the-art technology used in metal pumps cannot simply be applied to the design of plastic pumps without further modification due to the technical characteristics of the material. Since the thermal resilience of plastic is limited, plastic pumps cannot handle the same high bearing loads that a metal pump can withstand.
As impeller dimensions increase, so too do the demands placed on main and intermediate bearings in single-stage pumps with immersion depths greater than 2000 mm when it comes to balancing the high radial forces generated by these pumps operating at high speeds. This exposes the limitations of thermoplastic materials.
For this purpose, the modular system was applied in order to develop a two-stage pump series with a nominal speed of 1450 rpm, which meets the requirements of operational safety and system availability even during continuous operation. Two impellers arranged one behind the other achieve pumping heads of up to 85 m. Two-stage pumps offer significantly better bearing wear characteristics than single-stage pumps operating at high speed when it comes to pumping fluids containing solids or media with low lubricating properties.
Another important advantage is the significantly smaller installation dimensions – an important aspect of plant engineering. Thanks to the use of 4-pole drive systems, the pumps generate significantly lower levels of noise.
The new two-stage centrifugal pumps can achieve flow rates of up to 280 m³/h and pumping heads of up to 85 m. The temperature limits range from -10 to +90°C depending on the choice of material. The pumps can be supplied with immersion depths of up to 4000 mm. Gas seals to protect the bearing and motor are fitted as atmospheric shaft seals. The shaft can also be sealed using single-acting standard balanced mechanical seals.
Axial forces are absorbed by greased/oiled rolling bearings. Residual radial forces are absorbed by generously dimensioned main bearings which are made of PTFE-GF/ceramic or SiC/SiC depending on the condition of the pumped medium.
Polypropylene and PVDF are offered as housing materials. Versions using glass-fibre reinforced or coated polypropylene are available for high-temperature applications.
The two-stage B80 KGK G3 pump series sets new standards in the plastic centrifugal pump segment, which open up new dimensions of reliability and operational safety for plant engineers and operators.
Picture: Lutz Pumpen
Source: Lutz Pumpen