Synchronous desulfurization and denitrification technology of coal-fired flue gas by taking hydrogen sulfide as reducing agent

The invention discloses synchronous desulfurization and denitrification technology of coal-fired flue gas by taking hydrogen sulfide as a reducing agent. The technology comprises the following steps: 1) preparation of dissolved H2S; 2) preparation of a mixed gas of H2S, NO, NO2, and SO2; and 3) synchronous desulfurization and denitrification. According to the technology, integration of a desulfurization and denitrification device is authentically realized. NO and NO2 in the coal-fired flue gas are converted into N2 and water; SO2 and H2S are converted to high-purity elemental sulfur; and organic matters in waste water are further removed, so that treatment of wastes with other wastes is realized. Elemental sulfur is recycled through the technology; one part of elemental sulfur is cycled and utilized to maintain equipment operation; and the other part of elemental sulfur is output as a product. The reducing agent of H2S in the technology is prepared from an in-situ product of elemental sulfur through reduction, can be prepared when used, and does not need to be bought outside. Therefore, cost of purchase, transportation, and storage and potential security risk are avoided. Compared with a mainstream device, the desulfurization and denitrification device is significantly lower with respect to land occupation, construction cost, operation cost, and the like.