| abstract |
The present invention provides an engine exhaust treatment device that has a high NOx removal performance even when the exhaust gas temperature is low, and that can be configured in a small size with low power consumption, and highly efficient engine exhaust gas using the exhaust treatment device. To provide a method for denitration treatment. When an exhaust gas temperature in a diverted gas flow path is lower than a predetermined temperature, an electric heater is energized to heat the diverted gas flow path, and a diverted gas flow from a sub-injection valve. A required amount of urea water is injected into the passage 12 to generate urea vapor in the diverted gas passage 12. When the exhaust gas temperature in the exhaust flue 3 is higher than a predetermined temperature, the electric heater 13 is turned off and a required amount of urea water is injected into the exhaust flue 3 from the main injection valve 10. To do. The power consumption of the electric heater can be reduced and the power supply device can be reduced in size. The NOx treatment can be performed with high performance at low and high temperatures. [Selection] Figure 1 |