Exhaust Gas Post Processing System and Control Method Thereof

Abstract

An exhaust gas processing method may include desulfurizing a catalyst by raising temperature of the catalyst to a predetermined value, if the front/end temperature difference ΔT is less than a predetermined temperature difference X, while reducing agent is being injected, determining whether travel distance, fuel consumption amount, or travel time exceeds a first reference value, after the desulfurization, determining whether fuel is replenished by detecting the fuel amount, and determining whether a high sulfur fuel is refueled or not, if the first reference value does not exceed a predetermined value, the fuel is replenished, and the temperature difference (ΔT) is less than the predetermined temperature difference (X) during injection of the reducing agent. Accordingly, while the nitrogen oxide purification mode is being performed so as to eliminate the nitrogen oxide, the desulfurization control is performed according to a temperature difference between the front and the rear of the catalyst, and if the abnormal desulfurization control is repeatedly performed, it is determined that the high sulfur fuel is replenished. Further, this method has the vehicle driver effectively determine whether the high sulfur fuel is replenished or not and guide the vehicle driver not to replenish the high sulfur fuel some other time.

1 . An exhaust gas processing method, comprising:
 desulfurizing a catalyst by raising temperature of the catalyst to a predetermined value, if a front/end temperature difference ΔT is less than a predetermined temperature difference X, while a reducing agent is being injected;   determining whether a travel distance, a fuel consumption amount, or a travel time exceeds a first reference value, after the desulfurization;   determining whether fuel is replenished by detecting the fuel amount; and   determining whether a high sulfur fuel is refueled or not, if the first reference value does not exceed a predetermined value, the fuel is replenished, and the temperature difference (ΔT) is less than the predetermined temperature difference (X) during injection of the reducing agent.   
     
     
         2 . The exhaust gas processing method of  claim 1 , further comprising:
 desulfurizing the catalyst irregularly, after determining whether the high sulfur fuel is replenished, if the first reference value does not exceed a predetermined value, the fuel is replenished, and the temperature difference (ΔT) is less than the predetermined temperature difference (X);   counting the number of times of the irregular desulfurization; and   giving alarm that the high sulfur fuel is replenished, if the counting number is larger than a predetermined value.   
     
     
         3 . An exhaust gas processing system, comprising:
 a catalyst eliminating particulate matter of exhaust gas;   a detecting portion detecting driving condition of a vehicle, and   a control portion performing a predetermined program for regenerating the catalyst according to the driving condition detected by the detecting portion,   wherein the predetermined program includes an instruction for performing the method of  claim 1 .   
     
     
         4 . The exhaust gas processing system of  claim 3 , wherein the catalyst is
 an oxidation catalyst eliminating harmful material,   a diesel particulate filter trapping particulate matter of exhaust gas, or   a nitrogen oxide purification catalyst eliminating nitrogen oxide of exhaust gas.