Exhaust gas cleaning system

Recently, there are more and more signs that the ocean can no longer withstand continuous pollution, and we must protect the ocean. Ports, wharves, loading and unloading stations and ships that load and unload oil must prepare oil spill pollution emergency plans and be equipped with corresponding oil spill pollution emergency marine environmental protection equipment.

Exhaust gas cleaning mainly refers to the treatment of industrial waste gas such as dust particles, smoke and dust, odorous gases, and toxic and harmful gases generated in industrial places. Common waste gas purification includes factory dust and waste gas purification, workshop dust and waste gas purification, organic waste gas purification, waste gas odor purification, acid-base waste gas purification, chemical waste gas purification, etc. A complete exhaust gas cleaning system generally consists of five parts, which are the exhaust gas collection device (gas collecting hood) that captures the polluted gas, the pipes connecting the various components of the system, the purification device that purifies the polluted gas, and provides power for the gas flow The ventilator makes full use of the atmospheric diffusion dilution ability to reduce pollution of the chimney. The exhaust gas cleaning system is a system that uses exhaust ventilation to control the diffusion of air pollutants in the production plant. The purification device adopts different treatment methods and devices according to different treatment objects (such as dust-containing gas, harmful gas in the sea, flammable and explosive gas, etc.). At present, the commonly used exhaust gas purification methods include condensation method, combustion method, adsorption method and absorption method, etc., which are set at local pollution sources, collect pollutants in the air, and discharge them outdoors or at high altitudes after purification. It is the most effective and common method for producing and controlling air pollution.

Selective catalytic reduction (SCR) is a means of converting nitrogen oxides, also referred to as NOx with the aid of a catalyst into diatomic nitrogen (N2), and water (H2O). A reductant, typically anhydrous ammonia (NH3), aqueous ammonia (NH4OH), or a urea (CO(NH2)2) solution, is added to a stream of flue or exhaust gas and is reacted onto a catalyst. As the reaction drives toward completion, nitrogen (N2), and carbon dioxide (CO2), in the case of urea use, are produced. Selective catalytic reduction of NOx using ammonia as the reducing agent was patented in the United States by the Engelhard Corporation in 1957. Development of SCR technology continued in Japan and the US in the early 1960s with research focusing on less expensive and more durable catalyst agents. The first large-scale SCR was installed by the IHI Corporation in 1978. Commercial exhaust gas SCR systems are typically found on large utility boilers, industrial boilers, and municipal solid waste boilers and have been shown to reduce NOx by 70-95%. More recent applications include diesel engines, such as those found on large ships, diesel locomotives, gas turbines, and even automobiles. Several nitrogen-bearing reductants are currently used in SCR applications including anhydrous ammonia, aqueous ammonia or dissolved urea. All those three reductants are widely available in large quantities.