The chimney is a tall structure used to ventilate or exhaust off all gases generated during the Combustion of Fuel. Although it may be self-supported or supported by ropes, a huge structure made of steel or concrete but its primary function is just to vent off poisonous or harmful gases at a height where it does not come in contact with any human.
As the pollution laws are getting stringent day-by-day, all the industries using boilers or furnaces involving the process of exhausting harmful gases to surrounding atmosphere must install the chimney in their process. There are also some laws related to the height of chimney depending upon the type of region. Thermodyne Engineering System has designed, manufactured and installed several industrial chimneys all over the world. We have a vast experience in designing chimney that involves a draft calculation based on flue gas temperature at the inlet and the outlet of the chimney.
We have supplied many chimneys along with our Steam Boiler Assembly. General process involves generating flue gases from the combustion of fuel be it any fuel (solid/liquid/gaseous). Then the flue gases travel from Boiler to Air Preheaters and dust collectors. After exiting the dust collector, flue gases enter the chimneys through Induced Draft Fan to conclude this process before getting released into the atmosphere.
Industrial Chimney Working in Boilers
The chimney’s working is based on the natural draft or stack effect. As we know, the density of a gas reduces, with rising in its temperature, so because of this reason when the flue gases enter the chimney, the buoyancy forces of air come into action and help in carrying the flue gases out of the chimneys.
In the case of a Boiler assembly employing an Induced Draft Fan, the flue gases are brought to the chimney by this fan and then buoyancy forces deliver them to the atmosphere. These buoyancy forces depend upon the weight of the air displaced by the flue gases in the chimneys. Greater the weight, greater are the buoyancy forces present. And this weight can be increased by increasing the height of the chimneys.
Back in time, when Lancashire Boilers were in fashion, induced draft fans were not used. The reason was the extremely high temperature of flue gases at the chimney inlet, this high temp. of flue gases reduced the density of flue gases to a great extent. Now they were even lighter and the buoyancy forces produced were of greater magnitude.
This removal of flue gases in the chimneys created a vacuum at the chimneys inlet. So, because of this vacuum (pressure difference between boiler furnace and chimney inlet), the flue gases traveled all the way from the boiler to the chimneys, eliminating the need for an Induced Draft Fan.
We, at Thermodyne Boiler, have successfully designed, manufactured, supplied and erected both structure and self-supported Chimneys in compliance with IS-6533 (part-1&2) to many of our clients.