Bag filters offer high collection efficiency at a reasonable cost. In this type of filters, the air is cleaned by passing it through long and cylindrical bags made of cotton or wool fabric. These filtering devices capture particulate contaminants as they pass through a special fabric filter. The most common example of a filter device is a “baghouse”. This filter captures airborne dust that passes over many layers of fabric. Gradually a layer of dust builds up on the fabric. This dust also acts as a filter, increasing the dust collection efficiency of the initial system. Then, it becomes excessively clogged as a result of continuous accumulation of dust on the fabric. The dust is removed automatically by changing the fabric bag or by shaking the bag. Thus, the dust removed from the air stream remains inside the bags. In these devices, the air is cut from time to time and the bag filters are shaken by mechanical vibration or compressed air. It is saved from the dust it has held. By this means, most of the dust is collected in the lower funnel. The usage areas of bag filters are the same as those of pulse cartridge filters. Industrial type bag filters can be designed in two different ways.
Industrial type pulsed (jet pulse) bag filters
Industrial type bag filters with walker motor
Places where a common fabric collection system is used include industrial foundries, grain processing, material handling and crushing and milling.
Industrial Type Jet Pulse Bag Filters
Capacity range of 5,000 – 200,000 m³/h
Special design suitable for all operating conditions
Emission values below the Environmental Legislation at the filter outlet
Filter bags produced from fabrics suitable for the load and chemical structure of the dust to be captured, the humidity and temperature of the fluid.
Minimum compressed air consumption thanks to fully automatic PLC control unit and improved cleaning system
Electro galvanized, filter bag wires
Optional explosion cap on each module
Rigid system mounted on a steel chassis, completely bolted assembly
With the effect of the vacuum created by the ventilator at the end of the system, dusty gases pass through the pipes and enter the upper part of the bunker (via the inlet hood) and disperse into the bunker before reaching the bags. It is done from the outside of the filtering bags to the inside. At the same time, the dust layer accumulated on the bag surface helps filtering.
The cleaned gases pass through the inner surface of the bag and fill the clean gas cell at the top, and pass through the clean gas outlet pipe from there and are discharged to the atmosphere from the fan chimney (filtered clean air passes through the fan).
Cleaning the dust layer accumulated outside the filter bags is done by means of compressed air. Dust spilled from the bags is taken out from the filter bottom bunker with an air-lock and a screw conveyor or collected in a bucket. During the cleaning process, the effect of compressed air on the filter bags is provided with short pulses. These air pulses produce two types of effects on the bag:
The vibration created by the compressed air on the bag and accordingly the dust spilling on the bag surface,
The compressed air dispersed on the inner surface of the bag inflates the bag, and the air trying to escape from the inner surface to the outer surface opens the pores of the bag and throws the dust out.
The process of spraying the compressed air into the filter bags in short time intervals is provided by an electronic timer. Timer cleaning times can be set arbitrarily.
The flattening of the bags by the effect of the vacuum inside the filter body (negative air pressure) is prevented by a cage. The assembly or replacement of the bags is done from the top, after the filter top cover is opened.
Thanks to the automatic cleaning system, maintenance and operating costs are very low, filtering efficiency and filter life are very high.
Pulsed bag filters are generally used in central system dust and fume extraction applications. The polluted air collected from any pollutant source is brought to the filter with air channels designed in appropriate diameters and thicknesses. In general, self-flange round ducts are preferred for dust.
Particles carried by the polluted air entering from the inlet channel of the filter cabinet are held by a collision plate. In this section, the speed of the air is reduced and the desired filtration is achieved quickly.
In addition, sparks, large and abrasive particles that may come to the filter are kept and directed to the collection bucket at the bottom of the bunker. Thus, the life of the filters is extended. The trapped dust is automatically cleaned thanks to the pulse cleaning system.
The sprayed air makes short-sudden pressure pulses on the inner surface of the bags. This pressure is obtained by venturi and cleaning is done. The cleaned air is sucked from the cabin by means of a centrifugal fan and pressed to the desired environment. Dust moves from the outer surface of the filter to the inside. Filtered gases pass through the venturi to the clean room section and from there to the outlet pipe.
