Fumes Extraction systems (FES) are air pollution control equipment installed to capture fugitive fume gases, smoke and dust emission generated from various heat processes which are hazardous and detrimental to human health and environment.
The fumes containing dust at high temperature emanating from furnaces are captured by specially designed suction hoods (swiveling type and side draught hoods), then put through suitable treatment and passed into Bag house filters to release clean air into the environment and create dust free working place. The suitable treatment can be temperature reduction by air to air forced draft heat exchanger or by water cooled duct or water quencher. Sparks in the fumes are collected in the equipment called spark arrestor. Primary purpose of this is to break the heat envelope around the spark by creating turbulence. This is possible because of fixed guided vanes inside the spark arrestor which breaks the laminar flow & spark within flow converts to dust/ash which then collected in lower hopper. Spark arrestors also acts as a pre-separator/pre dust collector and reduces the dust load in the bag house.
Our customized systems are compatible to comply with Indian and international standard emission norms. Our clean air solutions are customized, easy to use and designed as per the site layout to suit different applications
Typical Operation of Fume Extraction Systems – Ferro Alloy Furnace
The Furnace comes with Smoke Collection Hood of Low Hood Design, which prevent any fugitive gas emissions. The gas emissions emanating from the furnaces are collected by the smoke collection hoods and passed on to a smoke chimney / stack by natural draft. The smoke chimney has a butterfly valve just a little above the top of the smoke hood with the help of which, the gas emissions are directed to the Air Pollution Control equipment. These gases from the point of Butterfly valve are sucked by means of a powerful I.D. (Induced Draft) fan into the Pollution Control Equipment.
Sparks if any in gas stream are extinguished in ductwork, bends & in Heat Exchanger (Forced Draft Cooler) due to changes of direction. First, gases are passed through a tubular forced draft cooler where they get cooled by atmospheric air being blow over the tubes with the help of axial cooling fans. The much heavier particles in the gases get settled at the bottom of the cooler. The gas with the remaining heavier particles goes to a multi-chamber Bag Filter System after which the I.D. fan is installed. When the gas passes through the filter bags, the dust present in the gases is trapped by these bags and only clean gas comes out of the Bag Filter. This clean gas is then released through the stack to atmosphere.
Bag House Cleaning:
During this process, the bags in the multi-chamber bag filter house collect fume dust and need to be cleaned. The Bag house cleaning is “OFF LINE” (with one compartment isolated) and “ON – DEMAND” on the basis of pressure drop across the bag house. When the pressure drop exceeds the set point, Master controller shall close the Poppet damper at the outlet of the compartment and start cleaning the bags till the pressure drop reaches lower set point. Cleaning is done by compressed air pulses so that the dust accumulated on the bags surface gets shrugged off and gets collected into a collection hopper provided at the bottom of the bag filter housing. After reaching lower set point, cleaning shall stop and Poppet
damper shall open. This cleaning operation shall be done in a sequential fashion as and when pressure drop exceeds preset limits. This loop shall ensure optimum cleaning of the filter bags to improve bag life and reduce emission levels. Accordingly, one chamber after another gets cleaned in a pre-determined cycle.
Tapping Fumes Fan (Booster Fan):
We consider the tapping fumes fan for each furnace, as it works on positive as well as negative pressure, it sucks the fumes from tap hole and pushes it towards the bag filter.
Isolation of Complete System:
Further, system isolation damper with actuator is provided which will isolate the complete system and furnace stack dampers are opened for venting the gases. This provision is useful in the event flue gas temperature is excessively high even after dilution damper is open. Moreover, if it is desired for purpose of maintenance, entire Gas cleaning plant can be isolated by operating these 2 numbers actuated dampers provided at the take off point near furnace hood.
- Different types of Smoke Collection Hood to suit site layout, swiveling type and side draught hoods
- Optimum Power consumption due to lower pressure drops
- Customized Solution to suit the site layout and process needs
- Ability to handle high temperature flue gases
- Design suitable for Online maintenance of Bag Houses
- Online and offline cleaning mechanisms
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