Nowadays, in order to improve air quality, it is important for governments, industry and the public to understand the interconnected components of an air quality management system. Machines that will be used to minimize particulate matter incorporate electrostatic precipitators, dust cyclones, and wet scrubbers. One recent technology in air quality control systems, especially in wet scrubbers, is, removing pollutants in gas streams when they pass by way of a cleaning liquid. As a rule, these wet scrubbers are used in industries as fertilizers, steel and acid plants. Various designs incorporate spray nozzles, misters, cyclonic action, venturi dispersion, and/or wet impingement configurations to capture the dust.
A venturi scrubber typically employs venturi-shaped construction and a spray nozzle on the inlet, which accelerates the water to break it into a fine mist. The higher the velocity, the more efficient the collector becomes. As this occurs, the pressure drop through the system also increases sharply. Design airflow must be maintained constantly or filtration efficiency will drop. Maintaining a clean- or recycled-water supply is important with scrubbers. The concentration of dust particles in the scrubbing fluid must be kept at less than 5% to maintain operating efficiency. In the case of combustible metals, the amount allowed to accumulate in the discharge vats is prescribed in NFPA 484: Standard for Combustible Metals.
An important advantage of wet scrubbers is that when combustible dust particles are captured into the scrubbing liquid, they are removed from contact with oxygen and the combustible dust hazard is controlled. Many metal dust, however, is reactive with water and other metals and may produce hydrogen gas. This should be considered before selecting a wet scrubber. Also, many specks of dust can be considered hazardous, and disposing of wet materials may be costlier than disposing of dry materials due to regulations. Dry media collectors are inherently at higher risk of a combustible dust explosion. As a result, they require more ancillary explosion-protection equipment to meet NFPA standards and control the hazards. Dry collectors typically can scale up to very large airflows and heavy dust loads whereas wet collectors would require multiple systems to handle larger airflows. Heavy dust loading with a wet collector also means more water consumption and treatment. Sometimes the choice between a wet or dry media system will not be clear-cut. Dust testing is the first step in the decision-making process.
Optromix Company presents the new type of wet scrubber – the Scroiler. The Scroiler can be used to remove dangerous gases, particulate matter, vapors and other contaminants from the air to meet EPA and OSHA requirements. Scroiler uses up to 10 times less cleaning liquid than a typical wet scrubber and it has no scale up issues. This water- and reagent-saving device has found wide applications in wet flue gas desulfurization (WFGD).