A lime hydrator integrated into a flue gas desulfurization system or other industrial system is provided that provides an in-situ variable rate of cured hydrated lime production for a variable supply rate of the in-situ produced cured hydrated lime for use within a flue gas stream as a moistened hydrated lime for a reduction of acid gas present in a flue gas stream. Also provided is a method of using a lime hydrator integrated into a flue gas desulfurization system or other industrial system to provide in-situ a variable production rate of cured hydrated lime for a variable supply rate of the in-situ produced cured hydrated lime for use within a flue gas stream as a moistened hydrated lime for a reduction of acid gas present in a flue gas stream.