Since the 1990s, the rigorous regulations on engine emissions in various countries have greatly promoted the development of engine technology.
China will implement State IV emission regulations on July 1, 2013. The National IV emission standard is the national fourth-phase vehicle pollutant discharge standard. The vehicle emission pollutants mainly include HC (hydrocarbon), NOx (nitrogen oxide), CO (carbon monoxide), PM (particles), etc. The application of technologies such as active layers of good catalytic converters, secondary air injection, and exhaust gas recirculation systems with cooling devices controls and reduces the standards for emissions of pollutants from cars to below specified values. There are also two major upgrades during the National IV era. One is the use of selective catalytic reduction (SCR) technology for the treatment of nitrogen oxides in tail gas using urea solutions; the other is through particle traps (DPFs). ) Or particulate catalytic converter (DOC), EGR (exhaust gas recirculation) technology that processes particulates produced by combustion.
At present, several large-scale diesel engine plants in China reduce the soot through the internal cleaning, and then use the SCR system to reduce the NOX emissions to meet the restrictions of the National IV emission regulations on soot and NOX. The SCR system includes: urea aqueous solution tanks, conveying devices, metering devices, injection devices, catalysts, temperature and exhaust gas sensors, and the like. The basic working principle of the system is that the exhaust gas enters the exhaust mixing pipe after exiting the turbine, and the urea dosing and spraying device is installed on the mixing pipe to inject the urea solution. Urea is hydrolyzed and pyrolyzed at high temperature to generate NH3. The system catalyst surface uses NH3 to reduce NOx, expel N2, and excess NH3 is also reduced to N2 to prevent leakage. Under normal circumstances, the consumption of 100L of fuel will consume 5L liquid urea solution.
China will implement State IV emission regulations on July 1, 2013. The National IV emission standard is the national fourth-phase vehicle pollutant discharge standard. The vehicle emission pollutants mainly include HC (hydrocarbon), NOx (nitrogen oxide), CO (carbon monoxide), PM (particles), etc. The application of technologies such as active layers of good catalytic converters, secondary air injection, and exhaust gas recirculation systems with cooling devices controls and reduces the standards for emissions of pollutants from cars to below specified values. There are also two major upgrades during the National IV era. One is the use of selective catalytic reduction (SCR) technology for the treatment of nitrogen oxides in tail gas using urea solutions; the other is through particle traps (DPFs). ) Or particulate catalytic converter (DOC), EGR (exhaust gas recirculation) technology that processes particulates produced by combustion.
At present, several large-scale diesel engine plants in China reduce the soot through the internal cleaning, and then use the SCR system to reduce the NOX emissions to meet the restrictions of the National IV emission regulations on soot and NOX. The SCR system includes: urea aqueous solution tanks, conveying devices, metering devices, injection devices, catalysts, temperature and exhaust gas sensors, and the like. The basic working principle of the system is that the exhaust gas enters the exhaust mixing pipe after exiting the turbine, and the urea dosing and spraying device is installed on the mixing pipe to inject the urea solution. Urea is hydrolyzed and pyrolyzed at high temperature to generate NH3. The system catalyst surface uses NH3 to reduce NOx, expel N2, and excess NH3 is also reduced to N2 to prevent leakage. Under normal circumstances, the consumption of 100L of fuel will consume 5L liquid urea solution.
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