Pneumatic double-layer flap valve

The utility model belongs to the technical field of alternative fuel conveying, and particularly relates to a pneumatic double-layer flap valve which comprises a valve body. The valve body is arranged in a two-section mode, a storage frame communicated with the valve body is arranged in the middle of the valve body, two fixing frame plates are sequentially arranged on the inner wall of the valve body, one fixing frame plate is located on the upper portion of the storage frame, the other fixing frame plate is located on the lower portion of the storage frame, and the valve body is connected with a plate turning mechanism matched with the two fixing frame plates. The opening and closing states of the two groups of turning plate mechanisms are opposite; during feeding, after high-temperature flue gas in the decomposing furnace enters the alternative fuel conveying channel, the situation that the high-temperature flue gas ignites the alternative fuel, a fire disaster is formed, and conveying equipment is burnt is