Bomba de descarga

Discharge pump for extracting polymer an prepolymer from vessels or reactorsBomba de engranajes de alta presión para la descarga del reactor de fluidos de media y alta viscosidad. La entrada tiene una abertura mayor que garantiza un flujo uniforme a los engranajes en condiciones extremas de baja presión succión neta positiva en el cabezal (NPSH) o bajo vacio.


Este equipo se ofrece con la opción de una entrada redonda para conectar directamente la bomba a la brida de succión que a su vez se conecta a la brida de salida del reactor o como una versión baja NPSH donde la bomba se conecta entre las bridas de la bomba y del reactor, para tener una entrada mayor y más corta. Aplicaciones comunes son el PET, PS, PC, ABS y otros polímeros.

Especificaciones:

Caja:
Acero nitrurado, acero herramental,
opciones: Acero especial, recubrimiento de
la superficie, engranajes helicoidales, en
granajes de espina

Engranajes:
De acero nitrurado, acero herramental,
acero especial, engranajes helicoidales,
engranaje de espina

Cojinetes de fricción:
Acero herramental, Al-Bronce, Níquel-plata
opcional: Materiales especiales
recubrimiento de la superficie

Sellos del eje:
Sello de viscosidad, caja de relleno,
combinaciones, doble sello mecánico

Sistemas de Calefacción:
Aceite o vapor

Parámetros de Operación:*

Viscosidad:
Hasta 40,000 Pas

Temperatura:
Hasta 400° C (752 ° F)

Presión de aspiración:
Desde vacío hasta 15 bar (218 psi)

Presión diferencial:
Hasta un máximo de 250 bar (3,626 psi)

Capacidad de la bomba:
De 22/22 a 360/360
(4.7 cm3/rev a 25,000 cm3/rev)

 

 Aplicación

Bio-polymers

There are two types of Poly:
a) Standard design: The suction flange is also the fastening flange to the reactor.
b) The Low NPSH design: In this case, the fastening flange is designed as an alifning flange and is seated on the delivery side of the pump. The pump is clamped between the aligning flange and the reactor flange. This design provides an extremly large and short suction opening, promotin product flow. The opening can be circular, squate or rectangular.

Low NPSH Version

The loss of pressure on the suction side of the pump is dependent upon a number of factors. Parameters like viscosity and flow rate are largely predetermined by the process. According to the Hagen-Poiseuille equation, the pressure loss is linearly proportional to the length of the inlet path and inversely proportional to the fourth power of the diameter. The unique WITTE low NPSH version utilises this knowledge and offers an extremely large diameter, short suction inlet.

With the Low NPSH version, the connecting flange is foreseen as a loose flange and is located on the pressure side of the pump. The pump itself is connected between the loose flange and the reactor flange. This configuration allows an extremely large diameter, short suction inlet to be incorporated into the housing. The shape of the inlet is variable and can for example be round, quadratic or square.

Due to the fact that the pressure losses at the suction side have been reduced to a minimum, even critical applications can be reliably realised, e.g. discharging high viscosity or foaming melts.

Types of Seals:

Vacuum viscoseal with stuffing box
The vacuum viscoseal is a special version of the viscoseal and can also be provided with heating or cooling. The return flow to the suction side is adjusted by means of a needle valve, so that the choked product forms a barrier. This makes it possible to operate the pump with vacuum conditions on the suction side. Due to the fact that it is a dynamic seal, it is often combined with a buffered stuffing box. This combination prevents air from entering the reactor, even when the pump is at a standstill.

 

 

 

 

Stuffing Box
The stuffing box is a simple (static) seal for WITTE gear pumps. It can be provided with buffering if so desired. The range of application is similar to that of the viscoseal. The standard material used for the packing rings is graphite but it goes without saying, that other materials are also available.

 

 

 

 

 

 

Vacuum viscoseal with lip seal
As an alternative, the vacuum viscoseal can also be combined with a lip seal instead of a stuffing box. The buffer fluid of this static shaft seal acts as barrier. If the pump is stopped for a short time this design prevents air getting sucked in the pump through the shaft seal.

 

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