Bulk Solid Feeders

Bulk Solid Feeders

What are bulk solids feeders?

Large amounts of bulk raw material are transferred from one point to another during bulk material handling activities, such as the transfer of bulk material from a silo to a tanker truck. Bulk equipment known as bulk solid feeders, which are vital in the processing of bulk materials, are used for feeding bulk materials.

Bulk material feeding methods

Volumetric and gravimetric bulk solid feeders are the two most common types of bulk feeders used in bulk industries for bulk material handling.

(i) Volumetric feeders

Volumetric feeders, as the name implies, regulate and control the discharging volumetric flow rate of dry bulk materials. These are dosing systems that supply dry bulk materials to systems or units with a specific volume at specific time intervals. Screw feeders and rotary feeders (also known as rotary valves) are some of the common models.

(ii) Gravimetric feeders.

These feeders control the bulk mass flow rate of dry materials, which can be done continuously or in batches. The former is concerned with the regulation of material mass discharge per unit time and the latter involves feeder shut off after the discharge of a specific material mass. Weighing instruments, such as load cells, can be used to determine the amount of the bulk material discharged. Gain-in-weight (GIW) and loss-in-weight (LW) are the two common gravimetric feeding methods.


Rotary Valve Application ExampleTypes of Bulk Solids Feeders

There are many types of bulk feeders, this includes the following: screw feeders, rotary feeders (rotary valves), belt feeders, apron belt feeders, vibrating pan feeders etc.

Screw feeders

In comparison to belt feeders, screw feeders have an enclosed design and are able to handle bulk solids without emitting dust to the environment which makes them suitable for handling a broad range of dry bulk materials in granular or powdered form. They’re utilized to mechanically feed dry bulk solids to downstream equipment.
A screw feeder can be placed almost anywhere in a production line and can be connected directly to a hopper, silo, dosing system or bin. A housing surrounds the screw (tubular or U-shaped volume). The housing features an inlet port that connects to upstream equipment and an outlet port where bulk materials are discharged.Dry bulk materials are fed to the equipment through the inlet port during operation. The screw is turned by a drive motor, which moves the bulk material one pitch every rotation.The bulk material is moved down the screw housing’s longitudinal axis until it reaches the discharge point (outlet port). This bulk material is fed to the downstream system or unit by the rotating screw through the outlet. The feeder can be positioned horizontally or at an angle.
Screw feeders come in a variety of models, although the most popular ones use single helicoidal screw shafts. Tubular screw feeders, U-type screw feeders, dosing screw feeders, micro-dosing screw feeders, and custom-designed screw feeders are some of the various models Polimak offers. Agriculture, chemical, cement, and lime, foundry, and paper are just a few of the industries that use screw feeders. They’re used in a variety of industrial settings, including mixing, dosing, and batching systems.

Rotary feeders

Depending on the application requirements, rotary feeders have almost the same design as rotary valves. Vanes on the feeders rotate at a specific rpm to discharge bulk materials into a unit or system. They are capable of precisely discharging and feeding bulk materials in powder or granular form from hoppers or silos. The valve can operate as an airlock feeder in some situations when pressure differentials are present, such as a pneumatic operating line. This allows for material flow while also limiting air loss. The vanes of the rotary valve establish a slight seal against the housing surface, reducing air leakage.
Polimak has a wide range of rotary feeders to assist its customers in handling bulk solid materials efficiently. We aim to design and manufacture state-of-the-art rotary feeders aimed at rendering quality performance during bulk material handling. Airlock feeders are used in a variety of industries, including chemical, foundry, mining, food, and many more.

Feeders selection procedure

Feeding rate, handled bulk material, upstream and downstream equipment, pressure and temperature are some of the factors that influence the selection of a feeder. Once these factors are properly determined, the manufacturer can advise on which bulk feeder would be appropriate for the desired application. When it comes to selecting the best bulk feeder for a certain application, Polimak ensures that its customers are guided and provided with technical assistance.Whether the solids feeder type is a volumetric feeder or a gravimetric feeder, it should render at least the following attributes. :

  • Required amount of bulk material discharge with determined precision and accuracy for a stipulated period.
  • Swift, reliable and smooth bulk material flow from the upstream/source equipment. (iii) Steady bulk material withdrawal from the upstream equipment especially for mass flow models.

In a measurement context, the terms precision and accuracy are normally used. If a measurement or produce is said to be precise, it simply reflects the reproducibility of the measurements, and if it is accurate, it simply reflects or considers how close a specific measurement is to the acceptable value. In other words, precision is the degree to which a process or system repeats the same measurement, while accuracy is the degree of closeness to the actual measurement.  Precision and accuracy are two important aspects in dosing, weighing and batching processes. Having long years of expertise in bulk solids handling industry, Polimak’s engineers provide suitable levels of precision and accuracy for extensive range of applications.

Handled materials

Cement, calcite, ash, glass powder, marble powder, soybean, sesame, rice, rice flour, dried fruit, nuts, peanut, almond, sunflower seed, cottonseed, grain cereals, chestnut, coffee grain, coffee powder, sugar, salt, spice plastic pellets, sawdust, fly ash, coal, coal dust, wheat, flour, barley, feed, seed, corn, chickpea, bean, etc., are some of the bulk materials that bulk feeders can handle.

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