Tolva de inyeccion de extrusion de polimeros

A hopper is a large, inverted

pyramid A pyramid () is a structure whose visible surfaces are triangular in broad outline and converge toward the top, making the appearance roughly a pyramid in the geometric sense. The base of a pyramid can be of any polygon shape, such as trian ...

al or

conical In geometry, a cone is a three-dimensional figure that tapers smoothly from a flat base (typically a circle) to a point not contained in the base, called the ''apex'' or '' vertex''. A cone is formed by a set of line segments, half-lines, ...

container used in industrial processes to hold

particulate matter Particulate matter (PM) or particulates are microscopic particles of solid or liquid matter suspended in the air. An ''aerosol'' is a mixture of particulates and air, as opposed to the particulate matter alone, though it is sometimes defin ...

or flowable material of any sort (e.g. dust, gravel, nuts, or seeds) and dispense these from the bottom when needed. In some specialized applications even small metal or plastic assembly components can be loaded and dispensed by small hopper systems. In the case of dust collection hoppers the dust can be collected from expelled air. Hoppers for dust collection are often installed in groups to allow for a greater collection quantity. Hoppers are used in many industries to hold material until it is needed, such as flour, sugar or nuts for food manufacturing, food pellets for livestock, crushed ores for refining, etc. Dust hoppers are employed in industrial processes that use

air pollution Air pollution is the presence of substances in the Atmosphere of Earth, air that are harmful to humans, other living beings or the environment. Pollutants can be Gas, gases like Ground-level ozone, ozone or nitrogen oxides or small particles li ...

control devices such as

dust collector A dust collector is a system used to enhance the quality of air released from industrial and commercial processes by collecting dust particle and other impurities from air or gas. Designed to handle high-volume dust loads, a dust collector syste ...

electrostatic precipitator An electrostatic precipitator (ESP) is a filterless device that removes fine particles, such as dust and smoke, from a flowing gas using the force of an induced electrostatic charge minimally impeding the flow of gases through the unit. In c ...

s, and baghouses/fabric filters. Most hoppers are made of

steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

Process

Materials can be added either manually or automatically to the top of a hopper. For dust collection, it enters the hopper from a collection device. For example, baghouses are shaken or blown with

compressed air Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air in vehicle tires and shock absorbers are commonly used for improved traction and reduced vibration. Compressed air is an important medium for t ...

to release caked-on dust from the bag. Precipitators use a rapping system to release the dirt. The crumbling dust falls into the hopper. Once the material in the hopper reaches capacity, it is released through an opening in the bottom with a diameter of about . Hoppers are rectangular or circular in cross section but have sides that slope at about a 60° angle. Slanted sides make it easier for the contained material to flow out. Conveyors are sometimes used to carry away the particulate matter.

Important components

Hopper walls are often insulated to protect the outside environment and personnel from the contents. Often, the bottom 1/4 – 1/3 of the container is heated to eliminate the possibility of condensation inside the hopper. The greatest difficulty associated with the removal of very fine material, like flour or dust, from a hopper is the compaction of the material. Moisture content, particle shape and size, and vibration are all factors that contribute to compaction. Typically, with such fine materials, vibrators are installed on the outer walls of a hopper to shake and release the material, however other kinds of discharging aids can be considered if necessary.

References

{{Reflist Air pollution control systems Material handling