Efforts to reduce global warming are putting emphasis on technologies that reduce emissions of carbon dioxide. The smoke stacks are a source major contaminant emissions including carbon dioxide. There are a number of technologies that can be used to remove pollutants from emissions from smoke chimneys, all of which capture pollutants before they are emitted through them. The type of technology employed depends on process and plant design.
Eliminate pollutants from smoke chimneys
Technologies to eliminate pollutants from chimneys have been designed taking into account the size of the pollutants to be removed, the rate of emissions, temperature, humidity and chemical properties such as flammability and acidity. The choice of technologies includes electrostatic precipitators, cloth filters, scrubbers, cyclones and settlement chambers.
Electrostatic precipitators use magnetic attraction to extract the smallest pollutants from the emission stream. Emission gases pass through a specially designed chamber that first accuses pollutants, causing them to be magnetically attracted to specially marked plates in which they are collected in hoppers. The flow coming out of the chamber is approximately 99% clean of small contaminants.
Fabric filters, also known as bag houses, remove contaminants as the emission stream passes through porous fabric specially designed to remove fine particles. The fabric must be able to withstand high temperatures and corrosive chemical characteristics. Often, emissions at high temperatures should be cooled before entering the bag house.
Scrubbers mix water into the gas emission in specially designed tubes. First, the velocity and pressure are increased to combine the contaminating particles with the water, then the mixing processes are stopped and the droplet / water contaminant particles are deposited out of the gas stream as it exits the tube. This technology uses a large amount of water and forms wastewater that must be treated.
Cyclones are machines that mimic the movement of natural cyclones to force larger polluting particles to fall to a hopper in the bottom and clean emissions of gases to come out through the top. Cyclones are cost efficient and are a low maintenance method for the removal of pollutants from emissions from smoke chimneys, however, they are only suitable for larger particles.
Settlement chambers eliminate large particles of pollutants from emissions. The velocity of gaseous emissions slows as they move through the chamber of what larger particles leave in a hopper. Settlement chambers are most often used in combination with other technologies, and smaller pollutants are likely to remain in emissions emanating from the chamber.
The devices used to control smoke emissions are part of a plan to improve air quality. The plan sets targets with specific standards for atmospheric pollutants. Technologies that remove pollutants from smoke stakes are determined to achieve reductions. After the implementation of these technologies, emission levels are evaluated to see if they have met the air quality objectives. If not, you need to reduce more pollutants.