Waste heat recovery system of rotary kiln

The waste heat recovery system comprises a movable unit, a supporting frame in the movable unit is arranged on a movable base, a heat preservation side wall is located on one side of a rotary kiln body in the horizontal direction, the lower end of the heat preservation side wall is connected with the supporting frame, and a top heat preservation plate is located above the rotary kiln body. One end of the top insulation board is connected with the upper end of the insulation side wall, the bottom insulation board is located below the rotary kiln body, and one end of the bottom insulation board is connected with the insulation side wall; after the two movable units are arranged on the two sides of the rotary kiln body in the horizontal direction correspondingly, the two movable units are oppositely arranged, a heat preservation cavity covering the periphery of the rotary kiln body can be defined by the top heat preservation plates, the heat preservation side walls and the bottom heat preservation plates of the