The NMWR 250/500 series is the new hermetically sealed centrifugal pump with permanent magnet coupling. Guaranteed leak-free use for heat transfer oils up to 450 ° C with a maximum flow rate of 1200 m³ / h and a magnetic output of up to 500 kW.
This pump meets the highest demands in the field of modern industrial heat transfer.
Thermal oil is a popular heat transfer medium in industrial heat generation. Thermal oil can transfer higher temperatures at lower pressures compared to hot water systems. Heat transfer oil systems therefore allow lower design pressures. The proper operation of a system depends mainly on the reliability of the pump used and its shaft seal system. Magnetic couplings have proven themselves as a reliable seal with a service life of ten years or more. The construction of DICKOW is air-cooled and absolutely leak-free.
Especially for the use of silicone fluids in a temperature range above 400°C and more recently up to 450°C are sufficient operating experience.
The operating principle of the magnetic coupling is very simple. There are inner and outer rows of magnets separated by a stationary containment shell. In the DICKOW design, the magnets are separated from the hot pump parts by a cooling fin housing. The magnets run on a reduced temperature level of maximum 250°C.
For the fluid-lubricated plain bearing, the material combination SiC/SiC or SiC/WC is used. Especially at the high temperatures mentioned above, it is particularly important that the slide bearing meets the peculiarities of the ceramic material. The design of a high-temperature plain bearing compensates for the problems of differential thermal expansion.
This new plain bearing is tested for use up to 500°C.
The standard gap material is Hastelloy C. If the power dissipation due to the eddy current losses of the magnetic coupling should be too great, a gap pot made of grade 5 titanium is also possible. At the stated temperatures of > 400°C, the heat radiation through the fin housing is usually too small. An additional air-cooled external pipe cooler, possibly supported by a radial fan, must be installed. An auxiliary impeller on the inner magnet carrier generates a constant circulating flow in the gap pot area. This flows through the radiator and sets the maximum temperature level of 250°C.
The plants for industrial heat generation are constantly larger. To support this development, the field of application of the magnetic drive pumps was extended to a flow rate of 1200 m3/h at a delivery height of just under 95 m. The transmission capacity of the magnetic coupling is 450 kW.
Other new design details ensure that this "big hot" can be operated safely even with a wheel diameter of 540 mm.
