A variable rate feeder (often shortened to belt feeder, or simply feeder) is a piece of industrial control equipment used to deliver solid

material A material is a matter, substance or mixture of substances that constitutes an Physical object, object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical property, physical ...

at a known rate into some process.

Belt feeders vs. belt conveyors

In both form and function, belt feeders are essentially short belt conveyors. There are a few key areas in which the two differ, however: * Rate control: feeders are capable of rate control (meaning the rate at which they operate can be varied), while conveyors operate at a constant speed. * Operational speed: feeders typically operate at slower speeds than belt conveyors. * Flow patterns: feeders are flood-loaded (where all of the material in the bin is in motion during withdrawal), while belt conveyors are funnel-loaded (where some of the material in a bin moves while the rest remains stationary).

Industries

* Mining / power generation. Due to rugged design and the ability to continuously move material in low-headroom situations, belt feeders have proven ideal for handling materials like

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...

and

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

. This gentle and economical transportation has proven vital for both the

mining Mining is the Resource extraction, extraction of valuable geological materials and minerals from the surface of the Earth. Mining is required to obtain most materials that cannot be grown through agriculture, agricultural processes, or feasib ...

and

power generation Electricity generation is the process of generating electric power from sources of primary energy. For utilities in the electric power industry, it is the stage prior to its delivery ( transmission, distribution, etc.) to end users or its stora ...

industries. * Bulk material handling. Belt feeders are typically used for handling fairly light, fine, abrasive, free flowing materials. Feeder units are typically placed under storage facilities such as

silo A silo () is a structure for storing Bulk material handling, bulk materials. Silos are commonly used for bulk storage of grain, coal, cement, carbon black, woodchips, food products and sawdust. Three types of silos are in widespread use toda ...

s, surge hoppers or load hoppers, and may be operated either horizontally or on an incline to save headroom. For such applications, belt width is governed by the size of the material being handled and required tons per hour.

Transport mechanisms

A number of different techniques and transport mechanisms are used, but these broadly split into these categories, in descending order of accuracy: * closed-loop feedback systems, where the output from some variable feeder is measured and the feed rate varied by a local control system ensuring the desired rate is maintained. To be noted that the dosing equipment can be a belt but can also be a screw conveyor, a twin screw conveyors or a vibrating tube * volumetric feeders, such as

screw conveyor A screw conveyor or auger conveyor is a mechanism that uses a rotating helical screw (simple machine), screw blade, called a "''flighting''", usually within a tube, to move liquid or granular materials. They are used in many bulk handling in ...

s, delivering a predictable

volumetric Volume is a measure of regions in three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). Th ...

feed, driven at a variable rate * open loop systems where a feeder (e.g. a belt feeder) is driven at a given rate which has been established in advance * open loop systems where a door or

valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or Slurry, slurries) by opening, closing, or partially obstructing various passageways. Valves are technically Pip ...

on a feed hopper is opened by a graduated amount, delivering an approximate rate of feed Any of these may be combined with subsequent checks from beltweighers or (in the case of grains, powders and liquids)

flowmeter Flow measurement is the quantification of bulk fluid movement. Flow can be measured using devices called flowmeters in various ways. The common types of flowmeters with industrial applications are listed below: * Obstruction type (differential pr ...

s to provide a more accurate flow of material.

References

{{DEFAULTSORT:Variable Rate Feeder Industrial equipment