Exhaust emission purifying apparatus for engine

An exhaust emission purifying apparatus for an engine, comprising:

• a reduction catalyst disposed in an engine exhaust system, for reductively purifying nitrogen oxides with a reducing agent;
• a storage tank storing therein the reducing agent;
• a reducing agent supply device supplying the reducing agent stored in said storage tank to said reduction catalyst;
• a second discharge-forcing device forcibly discharging the gas in an upper space of said storage tank;
• an adsorbing device temporarily adsorbing thereto the gas forcibly discharged by said second discharge-forcing device;
• and
• an oxidation catalyst oxidizing the gas desorbed from said adsorbing device.

An exhaust emission purifying apparatus for an engine, comprising:

• a reduction catalyst disposed in an engine exhaust system, for reductively purifying nitrogen oxides with a reducing agent;
• a storage tank that stores therein the reducing agent;
• a reducing agent supply device that supplies the reducing agent stored in said storage tank to said reduction catalyst;
• a heating device that circulates a heating medium heated by said engine, within said storage tank, to heat said reducing agent stored in said storage tank;
• a blocking device that blocks a passage which leads said heating medium into said storage tank;
• a heating medium temperature detecting device that detects the temperature of said heating medium;
• and
• first control means for controlling said blocking device to block said passage, when the heating medium temperature detected by said heating medium temperature detecting device is higher than the third predetermined temperature.