Method and system for purifying the exhaust gases of a combustion engine

摘要

An SCR method for purifying the exhaust gases of an internal combustion engine of a vehicle, according to which ammonia gas is exclusively metered in the exhaust gases, the method comprising a step of releasing ammonia gas from at least one solid absorbing matrix where it is stored by sorption and a step of metering the released ammonia gas in the exhaust gases. The method is such that it comprises a step of regenerating the solid absorbing matrix that consists in: generating a refilling ammonia gas by thermally decomposing an ammonia precursor in a heater mounted on board the vehicle; directing the refilling ammonia gas to the solid absorbing matrix where it is stored thereon.

主权项

1. A SCR or Selective Catalytic Reduction method for purifying the exhaust gases of an internal combustion engine of a vehicle, according to which ammonia gas is exclusively metered in the exhaust gases, the method comprising a step of releasing ammonia gas from at least one solid absorbing matrix where it is stored by sorption and a step of metering the released ammonia gas in the exhaust gases, wherein the method comprises a step of regenerating the solid absorbing matrix that consists in:
generating a refilling ammonia gas by thermally decomposing a ammonia precursor in a heater mounted on board the vehicle; directing the refilling ammonia gas to the solid absorbing matrix where it is stored thereon, wherein a first tank in which the solid absorbing matrix is stored is connected to a security valve configured to release the excess of gaseous ammonia in order to release the pressure above a given set-point, wherein the ammonia precursor is stored in a second tank and is an aqueous solution of urea, and wherein the excess of gaseous ammonia released by the security valve is first dissolved in an adequate amount of water before being returned to the ammonia precursor tank.