FIELD: machine building.
SUBSTANCE: invention discloses a method and system for purifying an exhaust gas stream, which is formed by combustion in an internal combustion engine and contains nitrogen oxides NOx. Method involves first oxidation of compounds containing one or more of nitrogen, carbon and hydrogen in a stream of exhaust gases. Besides, the first supply of the first additive in the exhaust gas stream is controlled. Said control is performed to prevent accumulation of soot over threshold soot value in catalytic filter arranged in exhaust gas purification system. This threshold value of soot depends on at least modes of operation of internal combustion engine, which influence level of flow rate for exhaust gas stream. First reduction of nitrogen oxides NOx in stream of exhaust gases is performed using reduction characteristics of at least partially catalytic coating contained in catalytic filter and using supplied first additive. Besides, soot particles are trapped and oxidized in the exhaust gas stream. Second feed of second additive is controlled in exhaust gas stream, followed by second reduction of nitrogen oxides NOx in the exhaust gas stream using the first and/or second additives in the reducing catalytic device.
EFFECT: invention discloses a method and a system for purifying an exhaust gas stream.
56 cl, 5 dwg
