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PZGO LLC > Articles > Smoke and exhaust sources, methods and equipment for neutralizing harmful gaseous and particulate emissions

Smoke and exhaust sources, methods and equipment for neutralizing harmful gaseous and particulate emissions

fume-extraction-system-title

Despite tangible progress in the development of alternative power sources, even in the 21st century, our civilization cannot completely abandon the consumption of hydrocarbons.

Fortunately, the gas and air purification industry is keeping up with the times, and today highly efficient exhaust scrubbers, fume absorbers and smoke extraction systems are available on the market.

Coal, fuel oil, diesel, gasoline, kerosene – this is not the whole list of hydrocarbon fuels, whose consumption exceeds 10 million kilograms per minute.

fume extraction system

Smoke extraction system after medical waste incineration (produced at PZGO LLC, Russia)

Within this page, the main sources of waste / exhaust emissions (fumes, vapors, aerosol and dust) will be reviewed, as well as methods and equipment for their industrial-scale capture, removal and neutralization.

PZGO LLC has been improving and modernizing industrial air purification technologies for over 30 years. To date, our smoke / exhaust extraction systems and fly-ash collectors demonstrate the near 100% air filtering efficiency at more than 200 industrial enterprises in Russia, the CIS, Asia and Europe.

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Chemical composition and biohazard of gases, fumes, vapors and aerosols resulting from the combustion of hydrocarbons

Before turning directly to industrial fume extraction systems, smoke absorbers and exhaust scrubbers, we have to justify the strict need for their use in the field of deactivating harmful emissions generated by power plants (steam generators), incinerators, steel mills (furnaces), oil and gas companies, and, of course, cars.

When the term “exhausts” is used, it is usually referring to smoke emissions after combustion or thermal decomposition of hydrocarbon feedstocks.

In general, the exhausts come into existence because the feedstock is not combusted completely. As a result, the flue gases contain a whole bunch of compounds of varying degrees of danger.

The table below lists the main pollutants present in flue emissions. All of the elements and compounds listed below, as well as many others can be effectively captured or neutralized by means of advanced air-cleaning / exhaust extraction systems manufactured at PZGO LLC.

Pollutant / Element / Compound Negative impact Danger rating
Nitrogen oxides (NOx) 10 times more dangerous than carbon monoxide, and dramatically affect all living organisms ★★★★★
Sulfur dioxide (SOx) in contact with body fluids sulphur oxide is converted into sulfuric acid, which causes dramatic damage to all living cells ★★★★☆
Carbon monoxide binds to hemoglobin and stops the oxygen supply of cells ★★★☆☆
Benzpyrene replaces parts of the DNA chains, which leads to serious mutations during cell replication ★★★★★
Cadmium and mercury cumulative poisons that can accumulate in the body. The biological hazard of these components, contained in small quantities in smoke emissions, is a negative impact on life-critical sulfur-containing enzymes and amino acids ★★★★★
Hydrochloric acid / Hydrogen chloride an extremely dangerous compound that causes burns of the skin. Acids are usually present in smokes in the form of a fine aerosol mixed with water vapor ★★★★☆
Hydrogen sulfide H2S one of the most dangerous sulfur-containing compounds, causing pulmonary edema, convulsions, nerve paralysis and coma / death. The danger of hydrogen sulfide this gas is that it paralyzes the olfactory nerves, and the person stops feeling the smell of H2S while continuing to inhale extremely dangerous poison ★★★☆☆
Anthracene a poison and a carcinogen that negatively affects the skin, to the extent of pigmentation and keratinization of the skin integument ★★☆☆☆
Aldehydes strong neurotoxins that can accumulate in the body indefinitely, causing irreversible damage to the brain and the nervous system ★★★★☆
Paraffins, olefins, naphthenes and aromatic hydrocarbons capable of oxidizing to extremely hazardous oxygen-containing compounds ★★☆☆☆
Microscopic particles of soot and ash contaminate the pulmonary surfactant and interfere with normal lung function ★☆☆☆☆
Particular attention should be paid to the variability of the composition of exhaust gases in different machines / circumstances. For example, when gasoline is burned out, more carbon monoxide is released, and emissions after the combustion of diesel fuel contain more carbon dioxide. The same applies to other types of fuel.

Equipment for capturing and neutralizing flue, waste and exhaust gases

Despite the fact that the properties of separate components of the exhaust gases are studied sufficiently, due to the high chemical activity of smoke components, it is often impossible to precisely predict the exact composition and properties of the resulting gaseous compounds.

Stationary smoke emissions are regulated by the Standards Catalogue ISO 13.040.40.

During the thermal decomposition of solid household waste / SMW, the spectrum of gaseous pollutants may include even more dangerous chemical combinations and pure elements: heavy metals, ketones, alkaline and acid fumes, alcohols, esters, amines, and many other components hazardous to human health and environment.

fluidized bed exhaust scrubber

Fluidized bed exhaust absorber for the complex capture of gaseous and mechanical pollutants from an asphalt plant

Thus, equipment for cleaning waste gases / smoke emissions must be able to simultaneously capture all harmful gaseous substances, as well as mechanical dust in the form of microdisperse soot, ash and slag particles.

Exhaust scrubbers, smoke absorbers and large-scale fume extraction systems

As shown by numerous experiments carried out in the laboratories of PZGO LLC, exhaust scrubbers, smoke absorbers and fume extraction systems operating on the fluidized bed principle showed maximum efficiency.

Design and principle of operation

Exhaust arrester and industrial dust extractors in most cases are vertical columns. Vertical orientation greatly simplifies the movement of contaminated flow through the tower, and, thus, reduces the materials consumption and the cost of apparatus.

The heart of the industrial air scrubber is a working chamber filled with a movable bed. The fluid bed itself is an array of hollow, thin-walled polypropylene balls that can easily change their position relative to each other (under the pressure of the gas-mechanical phase).

This demo stand vividly depicts the movement / floating of the ball-type filling inside the working chamber of the filter

The difference between fume scrubbers and absorbers in this particular case is formal and depends on the technical conditions in which the device operates. So, if a fluidized bed apparatus processes a gas stream that is heavily polluted by mechanical inclusions, then it can be called a scrubber. If the same apparatus is used to a greater extent to neutralize chemical pollutants in the stream, it can be called an absorber.

The ability of the bed to float is ensured by the state of balance of opposing forces.

  1. Contaminated flow is fed to the scrubber through the lower inlet (by means of an exhaust fan).
  2. In parallel with this, the atomizing section abundantly irrigates the tray (or trays) on which the array of polypropylene balls is placed.
  3. The vectors of the kinetic forces of the polluted stream (upwards the column) and the direction in which water irrigation occurs (downwards) are oppositely directed.
  4. The precise calculation of the flow speed, volume, mass and density of the floating bodies in the working chamber allows balls to achieve a suspended state, which is called the fluidized bed / pseudoliquid layer state (solid separate bodies behave like a liquid).
  5. The balls chaotically move inside the layer of process water (like in a bingo-machine). In the case of high chemical activity of the gas stream, the reagent may be a weak acid-, alkaline-, manganese-, lime- or other aqueous solution. The continuous mechanical contact of the floating bed with the inner surface of the working chamber provides for self-cleaning of the working compartment from mechanical impurities, if any, present in the air flow.
  6. In exhaust filters of this type, the contact area of pollutants with the floating layer is maximum, and the efficiency of smoke extraction (sorption of undesirable or harmful substances) is 96-99%.
  7. Resulting liquid sludge / pulp is discharged into the sludge collector, which can be equipped with a scraper-conveyor mechanism for automatic removal of residua.
  8. To trap the remaining microdroplets, an additional demister is installed upstream of the scrubber outlet.

The working reagent of the smoke absorber can be selected in such a way that an economically valuable product is formed as sludge / pulp. For example, the use of an aqueous solution of lime to trap sulfur dioxide makes it possible to obtain a solution of artificial high-purity gypsum as slurry.

The working chamber of the smoke extractor may be lined with heat- and acid-resistant material.

Multistage gas cleaning plants

It should be noted that scrubbers and absorbers can function not only as independent devices, but also as gas cleaning stages in multistage air treatment facilities.

industrial smoke absorption

Multi-stage scrubber-based smoke absorption plant

This feature is especially needed when it is necessary to clean the complex and hot polluted smoke stream.

  1. For example, a fluidized bed scrubber (FBS) can be used as the first cleaning stage. It captures most of the gaseous and mechanical impurities, and also reduces the temperature of the stream.
  2. The second stage of the gas treatment plant can be a chemical absorber. It effectively retains gases with exceptional chemical activity.
  3. In the third stage, the gas stream can be passed through a dry adsorption tower. Dry adsorption towers are usually the final stages of gas cleaning facilities and are often regarded as hygienic air cleaning equipment.

At each stage, it is possible to obtain an ecologically-safe, (and sometimes valuable) residua. Desorption of the adsorbent allows to obtain chemical compounds and chemical elements of the highest degree of purity.

Equipment engineering, manufacture, delivery and commissioning in Europe and Asia

For any questions regarding the individual design, manufacture or delivery of equipment to Europe and Asia, please send us an email or fill out the Customer’s questionnaire.

If necessary, local commissioning of the equipment is possible, as well as training of your staff.

Please do not hesitate to contact us; we are open for fruitful and mutually beneficial cooperation.

manufacture of industrial adsorption towers

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