When it comes to cleaning industrial gases of particulate matter, filtration is one of the most efficient and versatile techniques ever discovered. 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. There are different ways of trapping dust as gas passes through the fabric, but three of the most usual methods used are diffusion, direct interception and inertial impaction.
Why Fabric Filters?
There are several advantages to the use of fabric filters, and below are the most crucial:
> 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.
> Collection efficiency not influenced by the combustion fuel’s sulfur content unlike in ESPs
> Less particle size distribution sensitivity
> Works with no specific requirements in voltage
> Filters flammable dust
> Capable of sub-micron smoke and fume removal with the help of 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. As a two-dimensional network woven in many possible ways, tissue offers 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. 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.
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 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. Dioxins can also be eliminated through catalytic fabric filters.
Fabric filters are currently used in various industries, such as chemicals, metal processing, food, waste processing and cattle-feed.