Externally-calcined middle part high-efficiency gypsum calcining kiln

The invention relates to an externally-calcined middle part high-efficiency gypsum calcining kiln which comprises a rotary kiln body and a central flue gas pipeline arranged inside the rotary kiln body, wherein the rotary kiln body is divided into a head feed section, a middle calcining section and a tail discharge section according to the feed sequence. The invention is characterized in that the outer side of the middle calcining section of the rotary kiln body is provided with a heat source heat source flue gas chamber which can contain the outer side of the middle calcining section inside. By changing the position of the heat source, the externally-calcined middle part high-temperature heat supply section of the rotary kiln penetrates through the heat source flue gas chamber, thereby greatly increasing the contact heat exchange area of the hot flue gas and the rotary kiln body and enhancing the heat efficiency. The flue gas subjected to heat exchange enters a flue gas circulation pipeline and the central p