Fabric Filters: Uses and Advantages
Filtration is one of the most efficient and versatile methods of eliminating particulate mater from industrial gases. The process is made possible with the use of filter fabrics – also called baghouse filters, cartridge filters, sleeve filters and many other names – made of woven or felted material.
Filter fabrics are placed in a container that has gas inlet and outlet connections and a dust collection hopper, along with a cleaning system that removes the collected dust at regular intervals. When gas passes through the fabric, dust can be trapped by way of different mechanisms, the most common of which are direct interception, diffusion and inertial impaction.
Fabric Filter Advantages
Fabric filters offer a lot of advantages, including:
> Up to 99.9+% collection efficiency and with more variations in particle size and inlet grain loadings Compared to other types of single dust collectors, fabric filters can have consistent static pressure and efficiency for more particle sizes and concentrations within certain limits.
> Sulfur content of combustion fuel has no effect on collection efficiency, as in ESPs
> Less particle size distribution sensitivity
> No specific voltage requirements
> Filters flammable dust
> Removes smoke and fumes at sub-micron levels using special fibers or filter aids
> Come in a whole range of configurations, inlet/outlet locations and sizes
Types of Fabric Materials
There are two types of materials used to make fabric filters: tissue and felt. Tissue is a 2D network that could be woven in multiple ways and thus come with varying degrees of permeability and pliability. The properties of tissue are also affected by the individual characteristics of the thread or fibre used, the coating and the surface treatment. Tissue’s filter qualities are largely determined by the dust cake that gathers on the filter.
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.
Aromatic polyamide and glass fibre are two examples of basic materials used to make filter fabrics in gas applications, each having their own unique pros and cons in relation to chemical resistance, temperature, mechanical strength and cost.
Fabric filters have several applications where limitations are easily overcome simply with the right choice of filter material. By injecting activated carbon or lime into the fume channel, this technique can eliminate acid components or absorb dioxins, respectively. Catalytic fabric filters can remove dioxins too.
Several industries make use of fabric filters these days, including but not limited to waste-processing, foodstuffs, chemicals, and metal processing.