Performance characteristics of rotary lobe pumps for high viscosity food medium

Abstract This paper analyses the effects of food media with high viscosity on the performance of rotary lobe pumps. Rotary lobe pumps have long been used in the food industry for pumping highly viscous media and are designed to operate for long periods of time without replacement of any parts. The study utilised publicly available data from factory tests of the PLP 3-4 pump for pumping food media of various viscosities μ (μ above 10,000 cP). The paper presents the results of processing these data, which allow us to draw some conclusions. It is established that the power input of the pump PLP 3-4, due to the viscosity of the food medium, is directly proportional to the rotor speed and increases with its increase. Thus the power spent on overcoming back pressure depends on rotor speed nonlinearly. At the same rotor speed the increase in pressure drop and dynamic viscosity coefficient do not affect the productivity, but lead to a significant increase in power consumption. The obtained results allow to draw a conclusion that it is not necessary to connect the increase of hydraulic efficiency of rotary lobe pump with improvement of energy efficiency of unit utilisation and to take into account the reason of increase of discharge pressure.