Many technological processes in production are accompanied by air pollution, which necessitates the timely cleaning of the workspace to improve sanitary conditions. Ventilation systems, even in industrial design, are not able to provide sufficient performance when removing small particles produced by processing equipment. Therefore, in solving such problems, special dust collecting units of various types and modifications are used.
Basic equipment classification
Dust collectors are part of the general group of industrial apparatuses designed for air purification along with gas filtration systems. Such aggregates are usually used in food, woodworking and chemical manufacturing industries, providing a delay and removal of both fine dust and husks. One of the main signs of the separation of dust collecting units into types is the principle of interaction with the ventilation system. According to this parameter, two main types of this equipment are distinguished:
- Installations that are used to clean the air flow entering through the ventilation system. Such equipment can be integrated into the communications of air heating and air conditioning.
- Installations, which are also used to clean the air, but on the path of emission into the atmosphere of polluted streams from an exhaust ventilation system.
In both groups, the devices can operate on a different principle and, accordingly, have a different structural device.
Gravity Dust Collectors
In this category dust collectors and dust precipitation chambers stand out. In the first embodiment, we are talking about screw collectors that perform the function of preliminary air purification. The dust collector is installed in front of the suction filter and cuts off solid particles, subsequently leaving them in a special bag or on the walls of the exhaust pipe. Periodically, the flow transfer circuits are cleaned or replaced. As for sedimentary chambers, this is also a kind of ventilation dust collecting unit for preliminary, but already rough cleaning.
Such systems, in particular, are used to service grain processing plants that produce coarse dust. The gravitational principle of separating dust particles from air involves the use of the kinetic energy of foreign elements in order to collect them at the bottom of a special chamber. In the duct, conditions are created for laminar or turbulent movement of flows with dust at a speed sufficient for the suspension of suspended particles. In this case, there may be several chambers, which increases the cleaning efficiency. But even in this case, it is impossible to achieve the effect of fine filtration that meets sanitary requirements.
Inertial units
An extensive group of devices that are used to clean the air from dust of different fractions - including broken and fibrous elements, grain husk particles, etc. The greatest filtration effect is achieved by an inertial dust collecting unit called a cyclone. Actually, this is one of the steps in the comprehensive cleaning of dusty air, but it is also the most productive.
The design of such an aggregate is formed by a storage hopper, a special duct with a narrowed section (directly a cyclone), bag filters, an outlet pipe, a casing and, in some cases, an automatic shaking system. Due to the expanded cross section at the inlet to the duct, the air flow rate decreases, after which it is twisted into a cyclone spiral and is directed perpendicular to the original direction. During this process, dust settles in the storage hopper, which is also cleaned with a certain frequency.
Wet Type Units
To clean the air from fine, sticky and flammable dust, special installations with wet capture are used. In essence, this is a modification of a cyclone with a water film, which delays pollution with fibrous inclusions. The unit consists of a cylindrical duct with a conical bottom, air outlet pipes and a conductive scroll. The principle of operation of the dust collecting unit is to retain solid particles on the walls of the air duct, which are irrigated by nozzles located in the upper part of the cyclone under a pressure of about 2-2.5 kPa. When cleaning from target particles with a fraction of 5 to 10 ΞΌm, it is possible to achieve an efficiency coefficient of up to 95%. The water consumption in this case is 0.2-0.3 l / m3.
Features of recirculation apparatus
Especially for the removal of fine dust in small concentrations (up to 20 mg / m3) a recirculation unit is intended. Such units are used not only in the maintenance of industrial processing equipment, but also in spot welding, as well as in technological operations associated with the soldering of parts.
The main design features of recirculation dust collecting units include two-stage cleaning, which is provided by filtering materials that allow manual regeneration. Unlike many other systems that remove air, the separated streams in this case are not brought out completely, but are stored in the room after cleaning. Despite the decrease in filtration quality, such a solution has a significant advantage, which consists in maintaining the thermal regime. This allows you to reduce the cost of heating industrial premises in cold weather by reducing the flow of street air at low temperature.
Conclusion
In the Russian market, dust collectors are presented in a wide assortment, and the nomenclature is segmented not only by functional and structural characteristics, but also by the peculiarities of operating conditions. So, specifically for medium - sized enterprises of the woodworking industry , the PU-1500 dust collecting unit is designed to delay shavings, sawdust, and also small particles with a fraction of 5 microns or more. In the metalworking industry, ZIL series units are widely used. These are industrial vacuum cleaners that are interfaced with grinding, metal-cutting and grinding machines. It is recommended to select specific models based on the area of ββthe room, the characteristics of dust and impurities, as well as the technical conditions of installation and connection of equipment at the place of operation.