Filtration is one of the most efficient and versatile methods of eliminating particulate mater from industrial gases. The process primarily relies on filter fabrics, also known as baghouse filters, compact filters or sleeve filters, among many other names, is made of either felted or woven material.
Filter fabrics are placed in a housing with a gas inlet and outlet connections, collection hopper, and a mechanism that periodically removes the collected dust from the fabric. As gas passes through the filter, dust may be trapped in the fabric through different mechanisms, such as diffusion, inertial impaction and direct interception.
Fabric Filter Advantages
There are a number of advantages to using fabric filters, and here are the most important:
> Up to 99.9+% collection efficiency and with more variations in particle size and inlet grain loadings When pitted against other single dust collector types, fabric collectors, under certain limits, can maintain consistency in static pressure and efficiency for a wider variation of particle concentrations and sizes.
> Sulfur content of combustion fuel has no effect on collection efficiency, as in ESPs
> Minimal sensitivity to particle size distribution
> No specific voltage requirements
> Picks up flammable dust
> Removes smoke and fumes at sub-micron levels using special fibers or filter aids
> Available in an entire variety of inlet and outlet locations, sizes and configurations
Types of Fabric Materials
Tissue and felt are two types of materials that may be used to construct fabric filters. As a two-dimensional network woven in many possible ways, tissue offers varying degrees of permeability and pliability. Additionally, the properties of tissue are a product of the individual characteristics of the thread or fibre that was used to make it, along with the coating and surface treatment. The dust cake that accumulates on the filter dictates the filter qualities of tissue.
With its three-dimensional fiber network, felt works better for filtration purposes. High fabric loading is possible with felt, which is mechanically stronger than felt, while a smaller filter installation works fine.
Polytetrafluorethylene and ryton are two examples of materials that filter fabrics in flue gas applications are made of, and they all have specific advantages and disadvantages related to temperature, chemical resistance, mechanical strength and even cost.
Fabric filters come in handy for many different processes, and with the right filter material, limitations can be conquered. This method absorbs dioxins or gets rid of acid components when activated carbon or lime, respectively, is injected into the fume channel. Through catalytic fabric filters, dioxins can be removed as well.
Several industries make use of fabric filters these days, including but not limited to waste-processing, foodstuffs, chemicals, and metal processing.