Bag house filters in the bakery and confectionery industry

In the bakery and confectionery industry, many dusty raw materials are stored and processed in large quantities. In order to be able to fill and empty silos properly, deaeration is a must, but this often creates very dusty air, which must be separated from its dust particles. A bag house filter is a very efficient dry filter system to purify air from these kinds of suspended solids, thanks to micro-perforated textile in the form of cylindrical bags supported by metal cages. The cages are attached to the filter housing and can be changed at the top of the filter on the clean side. The design of the installation (round or rectangular) allows the treatment of a wide range of pollutants and air volumes.

The aerodynamic filter inlet consists of a pre-chamber, which reduces the air velocity by widening and thus minimizes bag wear. A series of plates ensures that the larger coarse dust particles are separated immediately. Depending on the degree of contamination and particle size, a cyclone can also be used as a pre-separator. The air flow is distributed over the entire filter element surface and crosses it from outside to inside. Once filtered and cleaned, the air is transported to the filter outlet. The dust deposited on the external surface of the filter elements produces a uniform layer of dust that improves filtration efficiency. In order to achieve extra low dust emissions, the filter bags can be additionally equipped with a HEPA (H13) absolute filter. A bag filter in the bakery and confectionery industry is therefore assembled and configured according to customer specific requirements.

The pressure drop will gradually increase due to the contamination, a sensor measures the differential pressure over the filter elements and controls the filter cleaning system. This periodic cleaning of the filter elements is done by a strong compressed air pulse, this way the differential pressure stays within the selected limits. This compressed air pulse cleaning system blows the bags clean from the inside out. As a result, less compressed air is consumed and the bags will last longer.

The bakery and confectionery dust, detached from the filter element surface, falls by gravity to the bottom of the filter funnel and is then collected in a bin, which is emptied periodically. Depending on the application, the hopper at the bottom of the filter can be equipped with a rotating sluice to continuously discharge the powder and collect it in a big-bag, for example. It is also possible to use a screw conveyor to continuously discharge the dust into a container.