Ventilation unit design

Contents

Introduction

At all stages of work with grain, from bakery to packing flour and cereal, by-products are formed in the form of dust, impurities, luzga, otra bey, flour, small and tentacled grain, etc. Those products were a source of possible pollution, both in production facilities and in the environment: air and water basins and soil. Aspiration, processing and disposal of these products is an important area of ​ ​ work of grain processing enterprises

Another object is to provide fire and explosion safety at the grain processing facility, due to the high concentration of dust in the air, as well as dust settled on the surface of the equipment and building structures of the building. Aspiration network is designed to eliminate or minimize the above mentioned negative factors

In this course project, an aspiration plant is designed for the peeling compartment of the cereal mill. Aspirable machines are A1-BRU sizing and A1-BKG-1 grading machines, during the operation of which a large amount of organic dust occurs, which can reach explosive concentrations, as well as concentrations of hazardous to human health

1.3 Aspiration Network Layout

Aspiration networks by spatial, technological,

temperature principles, operational reliability principle and simultaneous operation principle

According to the spatial principle, we combine closely located equipment into one network and prefer vertical ducts when combining equipment, since this makes the networks more economical and operational-reliable

According to the principle of simultaneous operation, we combine equipment operating at the same time into one network. We combine A1-BKG-1 and A1-BRU grains

According to the temperature principle, we do not allow combining equipment having different air temperatures into one network, since when mixing warm and cold air, condensation of water vapors and sticking of dust to the walls of the air duct are possible. The temperature of our equipment is equal to the temperature of the room, that is, 20-22 ° С

According to the technological principle, which takes into account the uniformity of the equipment and the equivalence of dust, we combine equipment in one network in which the dust is the same or close in quality. These are A1-BKG-1 grits and A1-BRU grains. Draw a general view of the aspiration unit

2 Installation of aspiration unit

The drawing of the planar wiring diagram is done on a scale of 1:20, with the exception of straight sections of ducts, which are drawn without observing the scale with breaks, based on uniform filling of the sheet

The wiring diagram shows on a scale all parts of the ducts: straights, confusers, taps, tees, diffusers, etc. The diameters of the ducts are drawn based on the results of the network calculation. Fans and dust collectors on wiring diagrams are drawn schematically. Flanged joints and transverse folds are drawn with main lines, and longitudinal folds of air ducts are not drawn

Air ducts are made of galvanized steel with sheet size of mm. The thickness of sheet steel is assumed depending on the diameter of the duct. For diameters up to 450 mm, take thickness = 0.55 mm

The width of the folds depends on the thickness of the steel sheet. With a thickness of 0.55 mm, the width is 8 mm

Split connections of air duct links are made on flanges: for diameter up to 315 mm from strip steel, for diameters from 355 to 560 mm from angular steel with size of mm. For attachment of flanges on ends of air duct links, edge flanges are made by 8 mm

Air ducts made of thin-sheet non-galvanized steel are covered from the outside with 138GF or GF-017 soil, inside with an olefin. In galvanized sheet steel ducts, only flange joints are coated with olive

Locations of fasteners shall be marked for horizontal sections of ducts D < 400 mm at a distance of not more than

meters and for D > 400 mm not more than 3 m. Vertical air ducts are fixed through

3-4 m. The distance between the air duct, wall and floor shall be at least 100 mm; up to electric drives - at least 300 mm

Air ducts along protruding or open columns should be laid close to them. Free-standing vertical ducts (above the roof) with a height of 1.5 to 5 m should be fastened with three to four braces with a diameter of 6 mm with reliable devices. Do not rest air ducts on equipment, connect suspensions to flanges

3 Explosion safety of aspiration unit

The cause of a fire or explosion in the room (workshop) is the presence of combustible dust and fibers. A large amount of dust is created by machines and units (large-sorting, peeling), as well as installations, the operation of which involves the use of powerful air flows (pneumatic systems, separators, etc.) or the transfer of crushed products (places of loading, transfer, etc.). Some dust is capable of spontaneous combustion. A local flash can cause bursting of settled dust, which in turn can lead to a repeated explosion of more power

The main method of preventing dust pollution in production premises is to seal the equipment, prevent excessive air bleed from it, seal air ducts, organized air supply to the premises

During aspiration of equipment, in which air performs technological or explosion-proof tasks, special inlet holes are designed in the housing. Place of holes is selected so that incoming air crosses the layer of processed product and washes working elements of machine

Conclusion

During the design of the aspiration plant for the peeling compartment of the cereal plant, the necessary parameters of the aspiration network were determined taking into account the parameters of the existing equipment. In this aspiration network design, the VTsP-5 fan with efficiency was selected to ensure the movement of air flows in the aspiration plant

During the design, the following layout principles were observed: technological, spatial, temperature, operational reliability

The aspiration unit calculated a total air flow rate of 4,719 m3/h based on network and cyclone air suction. Since the aspiration network is a recirculated network, a cyclone was used. This cyclone has a high degree of air purification: 99% and higher. VTsP-5 fan is assembled with 4A100L4 electric motor, power 4 kW. Total pressure losses on the main line amounted to 1356.7 Pa