EXHAUST GAS AFTER-TREATMENT SYSTEM

An exhaust gas after-treatment system includes a first reactor installed in an exhaust flow path, a second reactor disposed at a downstream side from the first reactor, a first reducing agent injection unit configured to inject a reducing agent toward the exhaust gas to be introduced into the first reactor, a second reducing agent injection unit configured to inject the reducing agent toward the exhaust gas to be introduced into the second reactor, a first temperature sensor configured to measure a temperature of the exhaust gas to be introduced into the first reactor, a second temperature sensor configured to measure a temperature of the exhaust gas to be introduced into the second reactor, and a control device configured to control whether to inject the reducing agent from the first and second reducing agent injection units and the amount of reducing agent to be injected on the basis of temperature information provided by the first and second temperature sensors.