A Short Guide On Hot Gas Filters

What are hot gas filters? One would be right to associate this with a factories and industries that use the filters to expel toxic waste gas. These are used in conjunction with other equipment in the factory, to create a complete gas filtering treatment. These have much more in terms of being able to release the gas safely and efficiently. Most of the filter elements are made from a ceramic material as this can withstand high level of heat better than any other material.

Ceramic filters are much more stable and can hold their form well under extreme heat as long as it is not in a housing that is fabricated with mild steel. These are shaped like a long tube, flanged at one and closed at the other end. They hang vertically within their vessel and attached to their header plate, keeping the dirty and clean compartments separated for a more efficient filtration process. How they work is when the hot gas is released, it is sucked through the filter from the outside to the inside. The particles are deposited on the outer surface of the tube.

Then there are intervals of controlled and sharp pulses of gas that is blown back down inside the filter element, which causes a temporary reversal of flow. The reversing flow causes the solids which have now accumulated, to detach itself and fall into a hopper section ready to be released or discharged. They usually detach in patches rather than as a whole depending upon the strength of the pulses. The solids are deposited on the outer surface making it easier to detach.

A filter capacity is determined by how many filter elements are contained in the vessel. Vessel designs can vary, if they are not big enough then two more can be installed. This is usually done for animal carcass incineration. There is however standard designs for a range of filter capacities that are not always suitable for large amounts of waste disposal. As the filters are in frequent use they would need to be treated and maintained in order to make sure that they are successfully disposing hot waste gas effectively.

Usually the gasses are treated beforehand to prevent any chemical reactions with the materials in the vessel. These are treated from any potential pollutants and when used in a ceramic filter vessel, the gas will need to be cooled or a sorbent will need to be added if acid gases are being used. Lime can react well with acid gases however the reaction with CO2 can be very slow. Ceramic filters can normally be made with carbon steel and not necessarily in stainless steel.