Desulfurization, denitrification and dust removal integrated flue gas treatment device and method for cement kiln

The invention discloses desulfurization, denitrification and dust removal integrated flue gas treatment device and method for a cement kiln. The device comprises a kiln tail preheater, an inlet flue and a comprehensive reactor, which are connected in sequence, wherein the inlet flue is provided with a reducing agent injection port, a heavy metal/dioxin injection port and a deacidifying agent injection port; the comprehensive reactor comprises a reaction tank and a double-layer filter sleeve arranged in the reaction tank; the double-layer filter sleeve comprises an outer-layer high-temperature-resistant filter pipe and an inner-layer high-temperature-resistant filter pipe impregnated with a catalyst. According to the invention, desulfurization, denitrification, dioxin removal and dust removal can be carried out simultaneously; pollutants such as dust, NOx and SO2 in the flue gas passing through the comprehensive reactor are greatly reduced, the emission concentration meets the ultralowemission requirement; mea