Coal-fired double-hearth lime kiln with low nitrogen oxide emission

The utility model relates to the technical field of lime kilns, in particular to a coal-fired double-hearth lime kiln with low emission of nitrogen oxides, the double-hearth kiln can reduce the generation of nitrogen oxides in the lime production process, and flue gas generated by the double-hearth kiln is connected to a smoke exhaust fan through a flue gas pipeline and then is exhausted through a chimney. A part of flue gas exhausted by the lime kiln is exhausted through a chimney, a part of flue gas is sent back into the double-chamber kiln through a flue gas pipeline, the flue gas is mixed with pulverized coal at the mixer after being pressurized by a booster fan and a Roots blower, then the mixture is conveyed to a spray gun arranged in the lime kiln through a pulverized coal distributor, and the spray gun can be in the form of a single-layer pipe or a double-layer sleeve. A pulverized coal mixture taking flue gas as a conveying medium directly circulates in the single-layer pipe; the double-layer sleeve