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

material Material is a substance or mixture of substances that constitutes an object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical and chemical properties, or on their geolo ...

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 elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...

and

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...

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

mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic ...

and power generation 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 silos, 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 blade, called a "''flighting''", usually within a tube, to move liquid or granular materials. They are used in many bulk handling industries. Screw conveyor ...

s, delivering a predictable

volumetric Volume is a measure of occupied 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 slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fitting ...

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 in a variety of ways. The common types of flowmeters with industrial applications are listed below: * a) Obstruction type (differential pressure or variable area) ...

s to provide a more accurate flow of material.

References

{{DEFAULTSORT:Variable Rate Feeder Industrial equipment