The development of pneumatic conveying and classification
History of the development of pneumatic conveying
Pneumatic conveying applications in industry began in the first half of the 19th century (no more than about 1886), BFStutevant prove solid particles in the air stream in a
controlled delivery. The first pneumatic conveying practice is to use a vacuum fan drive system that is widely used in processing wood chips and grains. Early 20th century, the
greater use of positive pressure system. Conveying speed is relatively high, is transported suspended particle concentration was low in the gas, which is called dilute phase chain conveyor
conveying. If the reference of modern engineering literature documented published articles is H. Gasterstadt discourse published in 1924, he proposed to describe the flow of air
and gas - solid mixture flow pressure drop in the pipeline theoretical laws. His main research work is the delivery of particulate solids and cereals (such as wheat), his roller conveyor
empirical formula for such features as the material is still correct.
Since 1924, then, in this regard the rapid increase of available data and documentation, pneumatic conveying technology gradually be developed. Start the separation cyclone and
airflow through the filter material is transported separated, and then provide technical extended to overcome the pressure drop will reverse bulk solid material into the
conveying line (started using rotary feeder, then spiral pump) .
During World War II, due to the demand for aviation gasoline, creating a solid fluidization technology has been greatly developed. Many industries use pneumatic conveying
particulate material has become common methods, such as pharmaceutical, food, plastics, cement, chemical, glass, mining and metal industries, etc., generally used in the
materials storage, transportation, by the materials and measurement processes.
Classification of pneumatic conveying systems
So far still no elaborate various models of pneumatic conveying systems industry standards. Broadly speaking can be divided into pneumatic conveying and air conveyor trough two
(A) pneumatic conveyors
a. Low pressure pneumatic conveying system
The system material is imported under a vacuum or positive pressure air (or gas) stream. This system consists of an ordinary pressure system, negative (vacuum) system, positive,
negative, and a closed loop system hybrid system composition.
b. Mechanical pneumatic conveying system
The pipeline system through a specially designed inlet turbine spiral like a class of the air and material feeders are mixed together, that the material feeders air nozzles into
the mixing chamber and the contact surface is fed stream. This mechanical strength higher air pressure system, a pneumatic system generates pure dense flow of solids.
c. High-pressure pneumatic conveying system
Air in the system is stored into the material, causing the material flow. Material added called "Send pot" high-pressure position, enter the warehouse material into high-
pressure gas pipeline was carried away, this is called "dense phase" system or "Send pot" system. The higher the mean operating pressure at a higher bulk solids concentration
and the longer distance is conveyed.
d. Pulsed pneumatic conveying system
Pulsed pneumatic conveying system to supplement uninterrupted Tigong air into the pipeline to ensure the delivery of materials to maintain fluidization and transport along the
entire length of the flow.
(2) Air trough
In the system of fine, dry bulk solids fluidized by air, and by the self-gravity movement, the flow angle of repose of the material and the pile density. Housing trough
separated by a specific porous plate into an upper and lower two parts. Air enters through the bottom of the trough so that the material fluidized porous plate and the upper
flow of the trough.