SYSTEM FOR SELECTIVE CATALYTIC REUCTION AND METHOD FOR SELECTIVE CATALYTIC REDUCTION

摘要

The present invention relates to a selective catalytic reduction system to reduce nitrogen oxide (NO_x) contained in an exhaust gas emitted by an engine. A selective catalytic reduction system according to an embodiment of the present invention includes: a main exhaust passage wherein the exhaust gas containing NO_x flows; a reactor including a catalyst to reduce the NO_x contained in the exhaust gas by being installed in the main exhaust passage; a reducing agent injecting unit injecting a reducing agent to the exhaust gas to be sent to the reactor; a first concentration sensor measuring the concentration of the NO_x contained in the exhaust gas which has passed through the reactor; a second concentration sensor measuring the concentration of the NO_x contained in the exhaust gas which has not passed through the reactor; and a control unit determining the amount of the reducing agent to be initially injected based on the concentration of the NO_x measured by the second concentration sensor, calculating the concentration of the NO_x (ppm) contained in the exhaust gas which has passed through the reactor in accordance with inputted information by setting a table of a mass flow of the NO_x contained in the exhaust gas which has passed through the reactor per a load of the engine, and revising the injection amount of the reducing agent of the reducing agent injecting unit to allow the concentration of the NO_x measured by the concentration sensor to be the calculated NO_x concentration. The present invention provides the selective catalytic reduction system and the selective catalytic reduction method capable of efficiently reducing NO_x contained in the exhaust gas of the engine by optimally injecting the reducing agent even though an engine condition is changed.