Clean Air

Cleaner Technologies for a Greener Tomorrow

Air is vital for the survival of most organisms on earth. With the advancement in technology and the industrial revolution, major air pollutants have been released into the air, causing widespread pollution. High levels of pollution can increase the risk of respiratory infections, among other adverse health outcomes. A major example of the ill effects of air pollution is the ozone hole in the atmosphere formed due to the release of harmful chemicals called chlorofluorocarbons which causes ozone degradation on an unprecedented scale. Such events serve as a reminder of the importance of maintaining strict parameters to ensure that air pollution is minimised.


Types of Air Pollutants

Any material which, when released into the air, can cause adverse effects on humans and the ecosystem are termed air pollutants. Pollutants can be suspended solid particles, liquid droplets or gases. Pollutants are classified as primary or secondary. Primary pollutants are usually produced by processes such as ash from a volcanic eruption or carbon monoxide emitted from vehicles. Secondary pollutants, on the other hand, are not directly emitted. When two or more primary pollutants react with each other, they often give rise to more harmful secondary pollutants. Ground-level ozone is a prominent example of a secondary pollutant. 

Most air pollutants are anthropogenic i.e. of human origin. The most prominent pollutants include:

  • Carbon dioxide (CO2): Described as ‘the leading pollutant’ globally due to its capabilities as a greenhouse gas, air pollution is often measured with respect to net carbon emission. Billions of tonnes of CO2 are emitted annually, leading to an overall rise in global temperature and resulting in drastic weather conditions and a rapid rise in sea levels across the world.
  • Sulphur oxides (SOx): Most common pollutant belonging to the sulphur oxide family is sulphur dioxide (SO2). SO2 is naturally produced in volcanoes but is mainly emitted in various industrial processes. Coal and petroleum also contain sulphur compounds in various forms, and their combustion releases sulphur dioxide as a major pollutant. Further oxidation of SO2 can occur but only in the presence of a catalyst such as NO2, giving rise to sulphuric acid (H2SO4), which then forms acid rain. This is one of the causes for concern over the environmental impact of the use of these fuels as power sources.
  • Nitrogen oxides (NOx): Nitrogen oxides, most commonly nitrogen dioxide, are produced by high-temperature combustion in industries and modern car engines fitted with internal combustion systems. They are responsible for smog formation, which can be seen as a brown haze above cities reducing visibility to mere metres and increasing the chances of accidents.
  • Carbon monoxide (CO): Carbon monoxide is a highly toxic gas formed mainly by the combustion of fossil fuels such as natural gas, coal or wood. Vehicular exhaust thus contributes to the majority of carbon monoxide released into the atmosphere. It is also responsible for smog formation, which is known to cause multiple lung disorders and disruptions in the ecosystem as well.
  • Volatile Organic Compounds (VOC): VOCs are a well-known group of outdoor air pollutants. They are categorised as either methane (CH4) or non-methane (NMVOCs). Methane is an extremely efficient greenhouse gas which contributes to global warming. Other hydrocarbon VOCs are also significant greenhouse gases because of their role in creating ozone and prolonging the life of methane in the atmosphere.
  • Particulate matter: Aerosols and Particulate Matter (PM) are mostly produced by human activities such as the combustion of fossil fuels in automobiles, power plants, and numerous industrial processes. An increase in the levels of fine particles in the air leads to health hazards such as heart disease, more commonly occurring along with altered lung function and lung cancer. Particulates are related to respiratory infections and can seriously affect those with conditions like asthma.


Control of Air Pollution

Thermax has a long and distinguished history of providing environment-friendly solutions that help their customers to protect the environment while not compromising on their production efficiency. Since 1980, the Air Pollution Control arm of Thermax has grown to become a globally renowned brand for industries concerned with the control of particulate and gaseous emissions. Thermax delivers the best solutions to its customers while making use of its extensive engagement with diverse sectors and collaborations with major companies in the field. Thermax’s solution offers double benefits to process-driven industries like cement, steel, aluminium, copper, etc., helping them recover products at various stages of plant processes and also comply with stipulated emission norms.

  • Electrostatic Precipitator (ESP) is a flagship product of Thermax, working successfully across heavy polluting sectors, including power, cement, steel, non-ferrous metallurgical and fertilisers. The Electrostatic Precipitators (ESPs) come in two variants, dry ESP and wet ESP. The former is used on hot process exhaust (50 – 450°C) that operates above the dew point of the gas stream, while wet ESPs are part of a special application system and are used for filtering wet sticky, tarry and oily particulate matter. It is capable of capturing 100+ types of particulate matter from 1 micron to 1000 microns and can filter out harmful particles such as coal as well as 50+ types of biomass fuel from being emitted into the environment.
  • Pulse Jet Bag Filters – Bag filters offered by Thermax are typically of two distinct types – pulse jet bag filters being one of them. Thermax has patented highly technical and innovative pulse jet bag filters. Pulse jet bag filters with filter bags of length more than 6 metre are equipped with unique pulsing systems where bags are cleaned sequentially, even when the dust-laden gas is filtered. The cleaning is controlled automatically by a sequence controller. This operates the assembly of solenoid and pulse valves which direct the airflow into manifolds. Pulse jet bag filters are thus designed to achieve maximum cleaning efficiency.
  • Reverse Air Bag Houses – Thermax has developed several fabric filtration systems, with one of the most significant milestones being the installation of reverse air bag houses for cement kiln and sponge iron industries. In reverse air bag houses, the bags are fastened onto a cell plate at the bottom of the baghouse and suspended from an adjustable hanger frame at the top. Dirty gas flow normally enters the baghouse and passes through the bag from the inside, and the dust collects on the inside of the bags. 

Reverse air bag houses are compartmentalised to allow continuous operation. Thermax’s RABH has four or more independent modules – the modules are set in pairs when the gas flows are on the higher side. Each module can be isolated for inspection or maintenance by closing the inlet, outlet and reverse air damper while other modules are in operation. The flow of the dirty gas helps maintain the shape of the bag. However, to prevent total collapse and during the cleaning cycle, rigid rings are sewn into the bags at intervals. RABH are an innovative solution to help get rid of air pollutants.

  • ComboFilter – ComboFilter is the latest innovation in air pollution control technology that has been developed by Thermax after extensive research and development. ComboFilter is designed to help old pollution control equipment meet stringent environmental norms. A ComboFilter is a combination of an Electrostatic Precipitator (ESP) and a Bag House Filter (BH), which offers the advantages of both systems. ComboFilter offers the benefit of easy coagulation and precipitation of particulate matter through electrostatic precipitation and further reduction of emission through the usage of filter media. ComboFilter is the ultimate solution to comply with the revised stringent emission norms by retrofitting a few fields of the ESP to BH.
  • Flue Gas Desulphurisation (FGD) – FGD is a process that can achieve SO2 removal with more than 97% capture efficiency. A Flue Gas Desulphurisation (FGD) system is majorly available in three variants – Wet Flue Gas Desulphurisation (WFGD), Spray Dryer Absorber (SDA) and Dry Sorbent Injection (DSI), each with distinctive capabilities for emission control. The systems use alkali reagents for sulphur dioxide (SO2) removal. In addition to SO2 removal, these systems also treat HCl, HF, SO3 and fly ash. 
  • Scrubbers – A scrubber is a versatile system capable of handling a wide range of gas volumes for scrubbing the acidic/alkaline nature of gases, hygroscopic, adhesive and explosive materials. It is designed for both particulates as well as gaseous pollution abatement. The variants available for particulate scrubbing are venturi and cyclonic. 

Thermax believes that clean air, free of pollution, can be achieved only by working together and cooperating to create a sustainable ecosystem where technology can peacefully co-exist with nature. With its technologies and innovations in the field of energy and environment, Thermax empowers the customer to contribute to the development of a better future. Thermax’s efficient and stringent pollution control solutions ensure that the invaluable natural resource – air, remains free from pollution.

For enquiries related to clean air, clean energy and clean water solutions, reach out to us at or call us at 1800-209-0115.

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