Centrifugal pump, canned-motor

High-pressure specification canned-motor centrifugal pumps can provide the solution for the hardest pumping duties. The pump illustrated in Figures 8 and 8.1 has to pump a corrosive suspension in a continuous flow at a starting temperature of 250°C and an inlet pressure of... 

Piping and pumps used for transfer of the butanols can be made of the same metal as tanks. Centrifugal pumps with explosion-proof electric motor drives are recommended (34). 

The most common maintenance problem with centrifugal pumps is with the seals. Mechanical seal problems account for most of the pump repairs in a chemical plant, with bearing failures a distant second. The absence of an external motor (on canned pumps) and a seal is appeahng to those experienced with mechanical seal pumps. 

Most induction ac motors are fixed-speed. However, a large number of motor applications would benefit if the motor speed could be adjusted to match process requirements. Motor speed controls are the devices which, when properly applied, can tap most of the potential energy savings in motor systems. Motor speed controls are particularly attractive in applications where there is variable fluid flow. In many centrifugal pump, fan, and compressor applications mechanical power grows roughly with the cube of the fluid flow. To move 80 percent of the nominal flow only half of the power is required. Centrifugal loads are therefore excellent candidates for motor speed control. Other loads that may benefit from the use of motor speed controls include conveyers, traction drives, winders, machine tools and robotics. 

Fig. 4.1-27 shows a multistage canned-motor centrifugal pump with a separate water-cooling circuit for the motor, such as is used, for example, to circulate carbon dioxide at 300 bar system pressure. The pump rotor is mounted in the motor area the tandem pump stages operate over-mounted on both sides of the bearings. This arrangement is recommended if the required differ-... 

Fig. 4.1-27. Ten-stage canned-motor centrifugal pump (HERMETIC)...

Hermetic canned motor centrifugal pumps in high-pressure processes... 

Continuous product flows under high-pressure conditions (p > 30 MPa) can only be achieved with hermetic centrifugal pumps. Although the two drive systems that can be used - the permanent magnet coupling and the asynchronous canned motor - have the same mode of operation, they differ in their applications and their safety ranges. 

CANNED-MOTOR CENTRIFUGAL PUMPS IN THE HIGH-PRESSURE RANGE... 

The versatile drive system of the asynchronous canned motor has set fresh yardsticks for centrifugal pumps operating under high-pressure conditions. The operating limits for pressure, temperature and toxicity of the flow product have been extended by some orders of magnitude. This is the logical result of the response to heightened safety environment requirements, and means that technical processes can now be implemented for the manufacture of new products. 

TYPICAL APPLICATIONS AND SPECIFICATIONS OF HIGH-PRESSURE CANNED-MOTOR CENTRIFUGAL PUMPS... 

The primary circuit can operate at temperatures of up to 400°C, whilst the motor circuit temperature will not pig. 7 High-pressure canned-motor centrifugal pump integrated into a exceed 60 to 80°C. nuclear fuel rod (Te = 360°C Q = 600 m7h H = 35 m P2 = 125 kW ... 

Fig. 9 Twelve-stage canned-motor centrifugal Fig. 9.1 Illustration of tandem high-pressure pump in a high-pressure specification centrifugal pump as per Figure 9...

Fig. 10 Single-stage, semi-hermetic high-pressure canned-motor centrifugal pump...

Fig. 12.1 Illustration of tandem canned-motor centrifugal pump as per Figure 12...

High-pressure specification canned-motor centrifugal pumps solve problems in areas which could not previously be aided by conventional pumps. Simple, space-saving construction, high availability, absence of emissions thanks to prevention of fluid escape and greatly reduced noise output are characteristics that are desired in modem industrial plant not only by operators but also by legislators. 

Type of power supply. Rotary positive-displacement pumps and centrifugal pumps are readily adaptable for use with electric-motor or intemal-combus-tion-engine drives reciprocating pumps can be used with steam or gas drives. 

---