The bag filter is a “dry” type dust collector. It is used for cleaning dust and gas compositions and is characterized by a high degree of efficiency. In terms of processing quality, it is noticeably superior to wet cleaning equipment and electrostatic precipitators. The device is equipped with filter elements operated at high temperature conditions and made of materials such as polyamide and polytetrafluoroethylene.
Description
The bag filter belongs to the category of universal equipment, since it can be used with equal efficiency in most technological processes, characterized by a large amount of generated dust. It does not require constant monitoring and maintenance, and functioning is carried out continuously.
It is also worth noting the possibility of manufacturing a device with various sizes, design features and identical characteristics suitable for operating conditions. Depending on the limitations and dimensions of the installation site, the design of the products can be selected or developed individually.
The characteristics of the dust-forming compositions determine the type of processing of the material, which can be, for example, oil-repellent or antistatic, as well as the structure itself. To make the right choice, dust analysis is often performed in special laboratories.
Application
The scope of use of the equipment is quite extensive, bag filter provides purification of aspiration emissions and flue gases in various industries, such as:
- manufacturing of building materials;
- non-ferrous and ferrous metallurgy;
- Foundry;
- automotive industry;
- energy and mining ;
- food production;
- metalworking;
- furniture, glass and chemical industries.
Bag filter calculation
The installation may have a different area of the filter material, the determining factor is the pressure drops occurring on the fabric. Other key criteria should also be taken into account, including the following:
- dew point temperature ;
- moisture level;
- pressure and temperature indicators;
- gas properties;
- volume of medium to be cleaned;
- gas explosion hazard;
- output concentration of dust and its type;
- technological process parameters;
- the presence of toxic substances in the composition.
To calculate the bag filter, it is necessary to establish the flow rate of purge gas and dusty compounds per material. It is also necessary to consider the filtration rate of the type of fabric used.
Sleeve
The filtering element of the equipment is a sleeve made of needle-punched non-woven fabric. There are two main designs:
- elliptical, placed both vertically and horizontally;
- round, suitable for upright use only.
The average period of operation of the sleeves is about 3 years, in some cases they can be used for more than 7 years. Despite this, the effectiveness of the equipment directly depends on the regular replacement of the sleeves. The use of modern fabrics that reduce residual dustiness is also recommended.
Regeneration system
Regeneration of bag filters ensures their functioning and autonomous mode of operation. Several regeneration systems are used, the impulse variety is considered the most efficient and reliable. It is carried out using compressed air, which is previously cleaned of dust and oil contaminants, with a pressure of not more than 0.6 MPa. This process does not require a stop of the working cycle and is performed automatically. Two main regeneration modes are used for the production of filters, each of which is selected depending on the operating conditions:
- Standard , in which the regeneration and purification of gas occur simultaneously.
- Mode for demanding applications. It is carried out after disconnecting one of the sections of a functioning device. A bag filter FR in this embodiment may have the ability to completely shut off each of the sections on either side, which simplifies the replacement of filter elements and carrying out maintenance work on functioning equipment.
The inclusion of pulsed regeneration is possible by timer and diaphanometer. Devices with this mode make up a large part of the market. There is also the possibility of manufacturing equipment in accordance with the characteristics of production, for example, products with mechanical shaking and reverse blowing.
Kinds
There are many varieties of filters, it is worth noting the most common of them:
- pressure head;
- products with horizontal placement of sleeves (service is carried out from a side platform;
- bag filter for gas purification with vertical placement of the sleeve;
- cyclone devices are equipped with a louvre separator for preliminary cleaning and are available in a round case;
- point equipment used to aspirate feed hoppers and conveyors;
- explosion-proof bag filter;
- high-performance devices suitable for a large volume of gas and providing a low level of residual dust;
- compact equipment equipped with corrugated sleeves.
Harsh environments
The bag filter, the characteristics of which are selected in accordance with the conditions of use, is suitable for work in the open air and indoors. In the first embodiment, an addition is required in the form of the following constituent elements:
- thermal insulation of the hull, which is of particular importance in the condensation of vapors;
- heating of equipment bins and regeneration systems;
- special shelter that prevents exposure to atmospheric phenomena.
Among the main types of devices, it is worth noting a two-row design, in the middle part of which there are pipes for the entry of contaminated and purified gas, as well as a single-row, in which the pipes are on the side of the structure.
Equipment is transported by freight. To simplify this process, the bag filter, the drawing of which is presented above, is implemented in a partially disassembled form. The units are made in various variations in accordance with the operating conditions. To assemble the structure, the welded method and bolted joints are used. Most of the devices are designed to operate with excessive discharge or pressure.
Increased efficiency
In some cases, insufficient work efficiency is noted, despite the observance of the conditions for the choice of material and competent calculation. Improving the result is possible by intensifying the method of carrying out regeneration, but this contributes to an increase in costs due to a decrease in the period of operation of matter, which accounts for strong mechanical loads. It is also possible to reduce the filtration rate and increase the layer of accumulated dust, in this case, the size of the equipment increases. The bag filter device often requires additional sections that provide continuous operation and the possibility of repair work without stopping the device.