Manufacturing processes are often accompanied by the release of dust components or gases which pollute the air in the room. Help solve the problem of aspiration systems, designed and installed in accordance with regulatory requirements.
We look at how to work, and where such devices are used, what are the kinds of air treatment systems. We denote the principal operating units, will describe the design standards and rules for installation of aspiration systems.
The content of the article:
- How it works
- Why do you need to design
- Features installation of such structures
- Why are there problems
- Conclusions and useful videos on the topic
How it works
Air pollution - an inevitable part of many industrial processes. To comply with established health standards of air purity using the process of aspiration. They can be used to effectively remove dust, dirt, fibers and other similar impurities.
Aspiration is a suction which is carried out by creating in the vicinity of the pollution source area of low pressure.
To create such a system, it requires serious expertise and practical experience. Although the work of aspiration funds is closely linked to the functioning of ventilation systemsNot just on ventilation expert to cope with the design and installation of this type of equipment.
To achieve maximum efficiency combined ventilation and aspiration techniques. The ventilation system in the workplace must be equipped with Supply and exhaust complexTo ensure a continuous supply of fresh air from outside.
Aspiration is widely used in the fields of industry:
- crushing production;
- processing timber;
- production of consumer goods;
- Other processes which are accompanied by the release of large amounts of harmful substances for inhalation.
Ensure the safety of employees standard protective equipment is not always possible, and aspiration may be the only opportunity to establish safe manufacturing process in the workshop.
Extractors are designed to efficiently and quickly remove the air from various small contaminants, which are formed in the process of industrial production
Removal of contaminants by this type of system is performed by special ducts, which have a large angle of inclination. This position allows you to prevent the emergence of so-called stagnation zones.
Mobile ventilation-suction plant easy to install and use, they are ideal for small businesses or even home workshop
Indicator of the effectiveness of such a system is considered the degree of nevybivaniya, ie ratio of contaminants which have been removed, to the mass of harmful substances which are not caught in the system.
There are two types of aspiration systems:
- modular system - a stationary device;
- monoblock - mobile units.
In addition, aspiration systems are classified according to the level of pressure:
- low-pressure - less than 7.5 kPa;
- srednenapornye - 7,5-30 kPa;
- high pressure - more than 30 kPa.
Options suction system of modular and monoblock type is different.
Notes to Scheme 1 - a source selection fell (grain processing equipment), 2 - umbrella, 3 - a centrifugal fan 4 - ducts, 5 - cyclone 6 - dust collecting hopper (+)
Monoblocks composed of such elements:
- fan;
- separator;
- waste storage device.
The separator is a filter for cleaning the air passing through the device. Waste accumulator may be either stationary, i.e. built-in monoblock and removable.
This unit can be purchased ready-made and easy to install in a suitable location for performing aspiration procedures. In this case, they are not difficult to connect to the existing centralized systems.
Modular harder to install and more expensive, but their use is much more effective than with the one-piece construction. Such systems are not typical, their first design to the specific conditions and challenges.
This takes into account a number of factors:
- characteristics of the production facilities;
- particular process;
- the quality of the transported medium, etc.
Usually it is a centralized system, which consists of set of ducts and a suction unit. For large enterprises system can be used with not one, but two or more such blocks.
Duct material may be different, depending on the nature and amount of pollution that is expected to transport them.
And suction cover is mounted as close as possible to the zone from which the pollution will be deleted, but it should not interfere with the staff to perform work duties
It is considered the most durable design made of black metal, but they are also the most expensive. In any case, the individual air line portions hermetically connected by flanges bolted.
Among the advantages of aspiration systems can be noted:
- relative simplicity of design;
- compatibility with various types of production equipment;
- safety for the environment;
- possibility of automation;
- improving fire safety facilities, etc.
The disadvantage of such systems include, above all, the rise in energy costs, especially at the wrong design, and low resistance metal ductwork to wear. These points should be considered when selecting a suitable design.
Why do you need to design
To create a modular system design aspiration unit following elements:
- local exhaust;
- inclined ducts;
- filter system;
- high-pressure fan, etc.
In different models of devices, such as suction sides, designs such as "umbrella", "cover" may be used as the local exhaust and others. Ducts paving from the fence waste position to the point of displacement in the outer space.
The filtration system may assume as removing purified air mass of the room, and return them back to the place after filtering fence.
Stationary suction systems in large enterprises - a large structure, which should be designed to taking into account the features of the room, the characteristics of contamination of the ventilation system configuration and many other indicators
Before the drafting of the suction installation is necessary to carry out a technical examination of the object's state. At this stage it is possible to identify and eliminate the shortcomings of the system. Such as checking and can be subjected to existing ventilation systems and aspiration.
Efficacy aspiration depends on the volumes of air that pass through the ducts per unit of time. The larger the number, the more expensive construction installation, as well as its operating costs.
If you pick up the components of the system correctly, the costs, both initial and maintenance can be significantly reduced.
The stationary aspiration system consists of a plurality of modules and components, the configuration of which is selected separately for each plant to provide maximum efficiency (+)
This includes the selection of a suitable device for air suction, competent calculations for distribution of supply air etc. As a result, the load on the system will drop, filters will require less cleaning, service life and increase the fan etc.
Some owners of industrial capacity in the selection of treatment systems are the path of least resistance. They are repelled by the cyclone type parameter settings, just tell your conditions of its operation: flow rate and nature of contamination.
As a result, they obtained a device whose performance is chosen from the tables without considering other parameters. Experienced designers argue that this approach usually leads to increased costs and reduced efficiency of the equipment.
The cost of the cyclone unit, the higher the volume of air that moves through it. If you optimize the existing air distribution system, it is possible to pick up exhausts and filters that will give the desired effect with less air consumption.
Such equipment will be cheaper, the savings could reach about one-third of the total cost. That is why the choice of equipment for the aspiration system should take care of the technical expertise and invite experienced designers.
Features installation of such structures
Since the duct aspiration systems are transported significant amounts of impurities, such that structures and imposed greater demands on strength, in contrast to the inlet air systems.
Their use for manufacturing steel of thickness 1.2 to 5.0 mm, and for shaped parts it is recommended to take a steel whose thickness is greater by 1.0 mm than that of the duct material.
use a solid steel sheet is not less than 1.2 mm thick for air aspiration systems. Releasable connections facilitate the process of purification system from contaminants
Do not fasten the suction duct collars on the suspension. It allowed only the use of straps, attached with brackets, in some cases as a chain attachment used.
The maximum distance between the brackets should be three meters for tubes with diameters greater than 40 mm and four meters - structures with a diameter of 400 mm or less. These parameters provide sufficient structural strength and reduce the risk of breakage duct during operation.
Another feature of the suction ducts is that they often have to disassemble to clean the accumulated dirt on the walls. Furthermore, the individual elements have to be replaced periodically due to rapid wear.
For this reason, it is recommended to use for quick mounting elements Connection designs, rather than the traditional flanges which from frequent disassembly-assembly are easily damaged.
To design aspiration system contamination do not accumulate, it is necessary to give the correct inclination duct which depends on the calculated air mass moving speed
To adjust air flows use the slanting vanes that exhibit minimal flow resistance and better prevent accumulation of contaminants. Application of the adjustment of the throttle valves is not recommended aspiration systems. It is important that the ducts are arranged at right angles.
The position depends on the design of a given air flow rate, which is determined by the nature of contaminants removed. Thus, to provide a speed of about 20 m / s, a bias is needed in the 60 °, for a speed of 45 m / s - angle of less than 60 °, etc.
If the nature of contamination allows to predict the accumulation of sticky dust in the ducts, such systems Industrial aspiration is recommended initially be designed to maximize the speed of movement air masses.
In small systems for aspirating suction device may be used a plastic pipe of suitable diameter. This is convenient, but not very durable item that will eventually need to be replaced
To facilitate the construction of purification, inserted into the duct special inserts from the film, paper and other suitable materials. Ordinary household and even some commercial ventilators for aspiration systems are not suitable, even if have sufficiently high productivity.
Need device with increased resistance to wear, which can operate for a long time under high load without interruption.
A common problem for low-efficient aspiration systems - air loss. To prevent this phenomenon, experts recommend choose fans with some reserve power. in practice air loss can reach 30% in comparison with the calculated data.
Wrong choice of local exhaust may adversely affect the entire system. You can not select an element without considering the peculiarities of the process.
In some cases it will effectively cover type "umbrella", in others - "Showcase", a fume hood, cab, etc. This point is mandatory should be aligned with the technologist in a particular industry.
Most of aspiration systems designed for moving the purified air to the atmosphere, but sometimes such air masses is returned to the premises (+)
For a rough cleaning air from dust using the dust bag, the dust besperegorodochnye chamber flues obunkerovannye dry cyclones and other such devices depending on the nature of the dust.
For the middle frequently used cleaning scrubbers, and fine purification is performed using a set of resources, which may include The cyclone-type precipitator and baghouse, in some cases, a high-pressure venturi tube or other suitable units.
Why are there problems
Even with a suction system in the production area, it is necessary to periodically check the level of pollution in the air. It so happens that the system is operating normally, the filters in the order, but air pollution remains far too high.
The reason for the shortcomings can be some phenomenon:
- dust accumulated in the ducts;
- low exhaust fan performance;
- too much air flow;
- insufficient inflow of fresh air mass.
If the air condition ducts accumulate a large amount of dust, it is said that the project was originally laid too low speed of movement of air masses. Another reason for this phenomenon - CI flaws in the aspiration system.
Impede timely removal of dust particles from the system availability can excessively sharp turns, portions with a small slope, the lack of sufficient cleaning hatches etc.
If aspiration system is designed and / or installed with flaws, she will experience increased loads and soon will become worthless
Improper installation or errors may cause too high losses of air in the system, resulting in an overall decrease in device performance. Leakage of air flow can also occur as a result of malfunction of the filtration system. For this reason, the calculation is recommended to lay a sufficient percentage for such losses.
If the system passes through a sufficient amount of air, but the operation of the system still does not show the expected efficiency should perhaps reconsider the design of local exhaust-shelter.
It should be positioned so as to collect the maximum amount of contaminants, preventing them from getting into the room air. This structure is designed in such a way that it does not interfere with the work and the movement of personnel.
Before drafting a stationary aspiration system is necessary to carry out technical examination of manufacturing facilities to determine the size of ventilation and basic parameters of (+)
If the room is not good supply of fresh air, it will not have enough for the aspiration system. To compensate for the increased efficiency of ventilation, on the production floor mounted inflow ventilation with heat recovery.
The hot shops heating the incoming outside air is not needed, make enough opening in the wall and close the shutter.
Conclusions and useful videos on the topic
Here is an overview of unpacking and mounting RIKON DC3000 aspiration of mobile systems for the woodworking industry:
In this video, we demonstrated steady aspiration system used in the production of furniture:
Aspiration system - a modern and reliable method of cleaning air in industrial areas of hazardous contaminants. If the structure is well designed and installed correctly, it will demonstrate the high efficiency at minimum cost.
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