Regenerative Thermal Oxidisers (RTOs) play an important role in air pollution control in manufacturing processes. They are often preferred over other air treatment equipment due to their cost effectiveness, high energy efficiency and recovery potential. In previous articles we have described how this plant works and why it offers great value for money compared with some other pollution control measures.
In this article will briefly describe the suitability of the RTO operation for different industries and airborne pollutants.
Air Pollutants Treatable By An RTO
All of the following contaminants can successfully be removed from exhaust waste by an RTO. However, the plant works best when dealing with low concentrations of pollutants, in high-volume waste emissions. For low volume waste streams, treatment with a smaller thermal oxidiser, or afterburner, may be sufficient. For high concentrations of pollutants, pre-treatment may be necessary before the exhaust is fed to the RTO.
Volatile Organic Compounds (VOCs): The VOC category contains a range of organic chemicals with a low boiling point due to their high vapour pressure. VOCs will typically sublimate directly into the atmosphere at room temperature. Not all VOCs are harmful, but some are anthropogenic, and others are damaging to the environment in high concentrations. Their presence in waste exhaust must therefore be strictly controlled. Harmful VOCs include benzene, chlorofluorocarbons (CFCs), ethyl acetate and other solvents, formaldehyde and hexane.
Hydrogen Sulphide: The distinct odour of rotten eggs and yellowish stain associated with some industrial exhaust fumes is the result of high hydrogen sulphide concentrations. The foul smell of hydrogen sulphide is antisocial in its own right, but it also has an acidic effect when it reaches the water table that is detrimental to plant and animal life.
Hazardous Air Pollutants (HAP): A broad category that includes many VOCs, plus a range of inorganic pollutants such as acrylic acid and hydrogen fluoride. All HAP substances can be linked to human health problems and/or environmental damage if they are allowed to accumulate in the food chain.
Nitrogen Oxide (NOx): All 15 nitrogen oxide compounds have been linked to heightened levels of air pollution and a catalogue of serious health conditions. Alongside carbon dioxide, carbon monoxide and particulate matter, NOx is one of the primary targets of clean air legislation. Businesses are strictly monitored on NOx emissions, and the trend is toward ever lower permitted concentrations in waste exhaust.
Carbon Monoxide (CO): CO need almost no introduction. In concentrations above 35 ppm, carbon monoxide is toxic to all animals. As an atmospheric gas carbon monoxide is highly unstable, quickly breaking down into ozone – which has been directly linked to climate change.
Particulate Matter (PM): Particulate Matter covers a very wide range of microscopic particles suspended in industrial exhaust emissions. Some are dangerous when inhaled directly, while others cause environmental damage when dissolved through precipitation and enter the water table. Many particulates are considered Group 1 carcinogens by the World Health Organisation and have been linked to heart conditions, lung cancer and birth defects.
Industrial Applications For RTOs
The broad treatment range of regenerative thermal oxidation means it is used in multiple sectors. In the manufacturing sector, RTOs can be used in the automotive and aerospace industries, paint production, chemical processing, paper, steel and food processing. RTO plant can also be used to treat exhaust emissions from the mining industry, power generation and sewage treatment. In fact, any business that uses an industrial furnace, or whose production process deals with metal and plastic compounds may benefit from an RTO. Their versatility makes them a cost-effective choice when investing in pollution control plant, with the added benefit of being able to reclaim much of the waste heat and recycle it for positive use elsewhere in your facility.
To find out more about the uses of RTOs, please download our free guide to Controlling Air Pollution & Emissions In Manufacturing With Afterburners & RTOs by clicking here.