Cement line kiln tail flue gas medium and low temperature SCR (Selective Catalytic Reduction) denitration system

The utility model provides a cement line kiln tail flue gas medium-low temperature SCR denitration system which can achieve ultralow emission of nitric oxide in cement line kiln tail flue gas, the SCR denitration system comprises an SCR reaction tower, an SCR catalyst and compressed air supply system, ash blowing equipment, ash conveying equipment and an ammonia water injection system, the SCR reaction tower is arranged between a high-temperature draught fan and a raw mill, and the high-temperature draught fan is connected with the raw mill. One or more layers of SCR catalysts are arranged in the SCR reaction tower, 4-5 rake type soot blowers and 4-7 sound wave soot blowers are arranged above each layer of catalyst, the compressed air supply system is provided with an air preheater and an electric heater and supplies compressed air with the temperature of 200 DEG C or above to the rake type soot blowers, and soot conveying equipment is arranged on the lower portion of the SCR reaction tower; according to the