Screw Pump for Drying Treatment

Closed circulation spray dryer

The closed cycle spray drying equipment is operated in a closed environment. The drying medium is inert gas (or nitrogen). It is suitable for drying materials with toxic substances or drying materials that are easy to oxidize in drying process. The system adopts inert gas as a circulating gas and has protection for dry materials. The circulating gas undergoes the process of carrying and dehumidifying, and the medium can be reused. Nitrogen is heated by heater and enters the drying tower. The liquid material is transported to the centrifugal nozzle by screw pump. The powder material atomized by the high-speed circulating atomizer is discharged from the bottom of the tower, and the evaporated organic solvent gas is compressed under the negative pressure of the fan. Under the force, the dust trapped in the gas is condensed into liquid and discharged from the condenser by cyclone separator and spray tower. The non-condensable gas medium is continuously heated and recycled as a drying carrier in the system. The conventional centrifugal spray drying is achieved through continuous conveying and exhausting. It is also a clear difference between the explosion-proof closed centrifugal spray drying equipment and the ordinary centrifugal spray drying equipment. The internal pressure system of the drying system maintains a positive pressure value, and if the internal pressure drops, the pressure is reduced. The transmitter controls the feed automatically to ensure the pressure balance of the system.

Screw Pump Selection of Key Points

The selection of single screw pump mainly focuses on the following parameters:

1. Pressure determination of single screw pump:

The output pressure of a single screw pump is determined by the number of bushing stages, i.e. the guide number of bushing (stator):
Level 1: The maximum working pressure is 0.6 MPa.
Level 2: Maximum working pressure is 1.2 MPa;
Level 4: Maximum working pressure is 2.4 MPa;
Due to the different conditions of the conveying media, the suitable stator series is selected according to the conveying pressure requirements for the medium with severe wear.

2. Selection of rotational speed of single screw pump:

Because of its structural characteristics, single screw pumps are mostly used to transport liquids with high viscosity and liquids containing particles, so the key to the selection of rotational speed is. For single screw pump, the selection of rotational speed is mainly based on the wearability of the medium and the medium viscosity.

3. Selection of Rubber Material for Single Screw Pump Bushing:

The bushing of single screw pump is a rubber product and a vulnerable part of single screw pump. Its choice directly affects the life of bushing. Normally, the life of bushing is 3-6 months. If the bushing is not selected properly, it may fall off from steel pipe or rubber block.

4. Material combination selection:

Transport of different properties of media requires different combinations of materials.

5. Performance:

Generally, the performance tables or characteristic curves of single screw pumps are based on the data when the water at 20 C is used as medium (the viscosity is 1cst). The flow rate and the shaft power are different for conveying different viscosity.

6. Shaft seals:

Mechanical seals and packing seals can be used according to needs and conveying media, and the two structures have interchangeability.

7. Pump driving mode:

Because the single screw pump is a low-speed pump, there are many driving modes of the pump. Generally, there are low-speed motor direct connection (6, 8), gear reducer motor drive, CVT motor drive and so on.