Canned Motor Pumps for the Conveying of Liquefied Gases — Alternative for High Pressure

Related Vendors

Lutz Pumpen GmbH

EDL Anlagenbau Gesellschaft mbH

ProMinent GmbH

HERMETIC-Pumpen GmbH

Single-Stage Canned Motor Pumps

A special single-stage pump type CNF has been developed for the conveying of liquefied gas. The partial flow for the cooling of the motor and lubrication of the radial bearings is diverted at the periphery of the impeller and returned to the pressure side after flowing through the motor. Hence an external return line for the partial flow to the supply tank or settling tank can be omitted.

An auxiliary impeller overcomes the incidental hydraulic losses. By means of the partial flow return to the pressure side, the point of greatest heating corresponding to point 5 in the pressure–temperature diagram (see pictures), sufficient distance from the boiling curve. Under otherwise equal conditions, this design can be used to convey fluids with an extremely steep vapour pressure curve.

Multistage Canned Motor Pumps

The multistage series CAM has also been specially developed for the conveying of liquefied gas. Extraordinarily favourable NPSH values enable — according to the type of pump — exceptionally good circulation performance. The pumps are available in 2- to 14-stage designs and can be employed for all liquefied gases.

The partial flow for the cooling of the motor and lubrication of the radial bearings is extracted on the pressure side after the last impeller is guided through the motor compartment. It is returned through the hollow shaft, not to the suction side of the pump, but, in multistage pumps, as a rule is returned after the second or third impeller for the cooling of the motor and lubrication of the radial bearings and therefore does not contribute to the heating of the first impeller on the suction side. It is decisive for the faultless functioning of the pump that the hottest point 6 in the pressure-temperature diagram is still above the vapour pressure curve.

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