Wet process ultralow temperature flue gas high efficiency denitration device and method

The invention relates to a wet process ultralow temperature flue gas high efficiency denitration device and method. The device consists of a denitration tower, a pressurization fan, a gas-liquid separation apparatus, a gas distribution apparatus, a circulation tank and a sedimentation tank. The denitration tower is internally equipped with mixed denitration catalyst carrier layers, a demisting unit and spray units; flue gas passes through the pressurization fan, the gas-liquid separation apparatus and the gas distribution apparatus in order to enter the denitration tower; the spray units are communicated with the circulation tank through pipelines, and the circulation tank is internally provided with a liquid catalyst and a reductant; the sedimentation tank is communicated with a position of the denitration tower close to the bottom, and the sedimentation tank is communicated with the circulation tank through an overflow pipe; after entering the denitration tower from the gas distribution apparatus, the flue