High-temperature and low-temperature gas-phase composite desulfurization and denitration method

The invention provides a high-temperature and low-temperature gas-phase composite desulfurization and denitration method. The high-temperature and low-temperature gas-phase composite desulfurization and denitration method comprises the following steps: a) introducing flue gas; b) uniformly distributing the flue gas; c) carrying out flue gas turbulence; enabling the flue gas to penetrate through awater layer concentrated at the bottom of a catalytic contactor to realize sufficient contact between the water layer and a spraying solution; d) carrying out desulfurization and denitration treatment, wherein the spraying solution is a water solution containing NaClO and NaOH; e) removing nitric acid and nitrite in water and mixing the water with an ammonium chloride solution. The desulfurizationand denitration method provided by the invention comprises the following steps: firstly, absorbing NO, SO2 and less NO2 in the flue gas by utilizing the water solution containing the NaClO and the NaOH; then transforming the