Exhaust emission control system and purification control device

An exhaust emission control system comprising:

• a fuel reformation device that generates a reducing agent to reduce nitrogen oxide contained in an exhaust gas emitted from an engine by reforming fuel used for the engine;
• a catalyst that purifies the nitrogen oxide in the exhaust gas by the use of the reducing agent supplied by the fuel reformation device;
• a plurality of degradation sensing parts that are arranged in the catalyst along a flow direction of the exhaust gas and that sense a physical quantity relating to degradation of the catalyst;
• a degradation estimation part that produces a degradation distribution of the catalyst in the flow direction on the basis of sensed values of the plurality of degradation sensing parts and that estimates a portion which is less degraded of the catalyst from the degradation distribution;
• and
• a reformation control part that controls reformation of the fuel by the fuel reformation device to have the reducing agent to reach the portion of the catalyst, which is estimated to be less degraded by the degradation estimation part, in an active state;
• wherein when the degradation estimation part estimates that a portion on a downstream side in the flow direction of the catalyst degrades, the reformation control part controls the reformation of the fuel to increase the activity of the reducing agent supplied from the fuel reformation device.

An exhaust emission control system comprising:

• a fuel reformation device that generates a reducing agent to reduce nitrogen oxide contained in an exhaust gas emitted from an engine by reforming fuel used for the engine;
• a catalyst that purifies the nitrogen oxide in the exhaust gas by the use of the reducing agent supplied by the fuel reformation device;
• a plurality of degradation sensing parts that are arranged in the catalyst along a flow direction of the exhaust gas and that sense a physical quantity relating to degradation of the catalyst;
• a degradation estimation part that produces a degradation distribution of the catalyst in the flow direction on the basis of sensed values of the plurality of degradation sensing parts and that estimates a portion which is less degraded of the catalyst from the degradation distribution;
• a reformation control part that controls reformation of the fuel by the fuel reformation device to have the reducing agent to reach the portion of the catalyst, which is estimated to be less degraded by the degradation estimation part, in an active state;
• and
• a reducing agent sensing part that is positioned between the fuel reformation device and the catalyst and that senses a state of the reducing agent supplied from the fuel reformation device,
• wherein the reformation control part corrects a degree of activity of the reducing agent supplied from the fuel reformation device on the basis of a sensing result of the reducing agent sensing part to have the reducing agent in an active state to reach a portion which is less degraded of the catalyst.