A method and a system for injection of a solution of a compound into a gas
at elevated temperature. The method includes the steps of injecting the
solution into an injection channel being provided into at least a portion
of an outer channel and being surrounded by and spaced apart from the
outer channel, passing the gas along space between inner wall of the
outer channel and outer wall of the injection channel and along inner
space of the injection channel, evaporating the solution in and on inner
wall of the injection channel, and decomposing the compound in and on the
inner wall of the injection channel and in the gas. The solution can be
aqueous solution comprising urea or ammonia, the gas is an exhaust gas
from combustion, and the injection channel is a cylindrical channel
concentrically installed in the outer channel.