Double tube-sheet heat exchanger just avoids the unsafety resulted from leakage at the connection point between the heat-exchange tube and the tube-sheet; however, if heat exchange tube leakage is still unavoidable, Funke has developed a type of heat exchanger of both double tube-sheet and double layers of heat-exchange tubes, in this way, danger resulted from medium leakage at the shell side and tube side can be thoroughly eliminated; besides, an alarm device is also installed for monitoring equipment operation at any time. Funke puts customer demands at the first position, personalizes the products, and keeps product developing and self challenging, which are fully rendered by the success of double tube and double tube-sheet heat exchanger. This product is mainly used in industries where explosion hazards exist for mixing of medium at the tube side and the shell side and those of high requirements for environment protection such as chemical, metallurgy, food and multicrystal silicon industries etc.