Rotary positive displacement pump

A method for heating a rotor casing and/or a fluid product within the rotor casing of a rotary positive displacement pump having a front side and a rear side, wherein the rotary positive displacement pump comprises a transmission housing and the rotor casing, wherein the transmission housing gives rotational support to first and second parallel and axially extending drive shafts having gears in constant mesh condition, such that the first and second drive shafts are arranged to rotate in opposite directions, wherein the rotor casing is connected to a front side of the transmission housing and having an axial rear wall, an axial front wall and a circumferential side wall jointly defining a stationary interior pumping cavity, wherein the rotor casing houses a first rotor that is drivingly connected to the first drive shaft and a second rotor that is drivingly connected to the second drive shaft, wherein the first and second rotors are configured for rotating in opposite directions and mutually interacting for providing a positive pumping effect on a fluid product that enters the pumping cavity via a rotor casing inlet and exits the pumping cavity via a rotor casing outlet, wherein the rotor casing further includes first and second sealing arrangements configured for preventing fluid product from leaking out from the stationary pumping cavity towards the rear side of the rotor casing along the first and second shafts, respectively, the method comprising:

• detachably fastening a heating device to the axial rear wall of the rotor casing, the heating device being separate from both the transmission housing and the rotor casing, the heating device being detachably fastened to the axial rear wall of the rotor casing so that the heating device is separable from the rotor casing, and
• activating the heating device for heating the rotor casing, the first and second sealing arrangements and/or any fluid product within the rotor casing.

A rotary positive displacement pump for pumping a fluid product, the pump having a front side and a rear side and comprising:

• a transmission housing providing rotational support to first and second parallel and axially extending drive shafts having gears in constant mesh condition, such that the first and second drive shafts are arranged to rotate in opposite directions, the transmission housing having an axial front wall;
• a rotor casing connected to a front side of the transmission housing and having an axial rear wall, an axial front wall and a circumferential side wall jointly defining a stationary interior pumping cavity;
• the rotor casing housing a first rotor that is drivingly connected to the first drive shaft and a second rotor that is drivingly connected to the second drive shaft;
• the first and second rotors being configured for rotating in opposite directions and mutually interacting for providing a positive pumping effect on a fluid product that enters the pumping cavity via a rotor casing inlet and exits the pumping cavity via a rotor casing outlet;
• the rotor casing including first and second sealing arrangements configured for preventing fluid product from leaking out from the pumping cavity towards the rear side of the rotor casing along the first and second drive shafts, respectively;
• the axial rear wall of the rotor casing and the axial front wall of the transmission housing facing one another and being spaced apart from one another by virtue of an axially protruding portion that extends between the rotor casing and the transmission housing;
• an intermediate space bounded by the axial rear wall of the rotor casing and the axial front wall of the transmission housing that are spaced apart from one another and by the axially protruding portion;
• and
• a heating device configured to heat the rotor casing, the first and second sealing arrangements and/or any of the fluid product within the rotor casing, the heating device being separate from both the rotor casing and the transmission housing, being positioned in the intermediate space and being detachably fastened to the axial rear wall of the rotor casing.

A rotary positive displacement pump for pumping a fluid product, the pump having a front side and a rear side and comprising:

• a transmission housing providing rotational support to first and second parallel and axially extending drive shafts having gears in constant mesh condition, such that the first and second drive shafts are arranged to rotate in opposite directions, the transmission housing having an axial front wall;
• a rotor casing connected to a front side of the transmission housing and having an axial rear wall, an axial front wall and a circumferential side wall jointly defining a stationary interior pumping cavity;
• the rotor casing housing a first rotor that is drivingly connected to the first drive shaft and a second rotor that is drivingly connected to the second drive shaft;
• the first and second rotors being configured for rotating in opposite directions and mutually interacting for providing a positive pumping effect on the fluid product that enters the pumping cavity via a rotor casing inlet and exits the pumping cavity via a rotor casing outlet;
• the rotor casing further including first and second sealing arrangements configured for preventing the fluid product from leaking out from the pumping cavity towards the rear side of the rotor casing along the first and second drive shafts, respectively;
• the axial rear wall of the rotor casing having an axial rear wall surface that faces towards the axial front wall of the transmission housing;
• and
• a heating device configured to heat the rotor casing, the first and second sealing arrangements and/or any of the fluid product within the rotor casing, the heating device comprising a heating casing that is separate from both the rotor casing and the transmission housing, the heating casing being provided with a channel and being detachably fastened to the axial rear wall surface of the rotor casing.