Points to Consider While Selection of Rotary Feeder

Rotary feeder is also called as rotary valve or rotary airlock valve. The application of this versatile valve is volumetric feeding / dosing of dry bulk solids material. The key factors that determine the capacity of the valve include:

1.       Bulk density of the material

2.       RPM

3.       Size of the rotor

To fine tune the throughput capacity, speed adjustment can be provided through variable frequency drives for special feeding applications.  The selection of rotary valve is important. In today’s competitive business environment companies focus on energy efficiency like never before. As for example in cement industry, the production process consumes vast amounts of energy. Hence energy efficiency of all equipment is important. Rotary valve is extensively used in cement industries, energy efficient rotary feeders help in reducing the energy costs. 

Where wet and sticky materials need to be handled via rotary airlock valve, care needs to be taken in selection of the motor hp. A positive mechanical scrapper can be used to avoid choking of the valve. However such scrapper mechanism increases the size of the valve considerably. Certain materials change their property when they catch moisture from the atmosphere. They may become cohesive and thereby trip the motor due to the resulting sluggishness due to moisture. It is important to understand such characteristics of materials before selection of the feeding equipment. In case of handling abrasive materials, the material of construction of rotary feeders need to be wear-resistant or in stainless steel. For materials with adhesive properties a coating of non-stick needs to be applied for effective operation of the equipment.

Cast iron or cast stainless steel is used as material of construction for rotary valves. Abrasion resistant liners like Teflon can be used at the tip of the rotor vanes for wear resistance. Attachable gear motors provide a compact manufactured size which is easy to install. Outbound bearings ensure that the dust do not ingress into the bearings thereby causing undue problems in the operation of the valve.

The material passes through the inlet to the discharge outlet through the rotor. The rotor is housed in the body and rotates. Pockets are formed in the rotor through vanes which can be 6 or 8 in number depending on the capacity required, material to be handled and the application.