Shell-and-tube heat exchanger

The utility model discloses a shell-and-tube heat exchanger, which relates to the technical field of heat exchangers and comprises a tube body, an outer shell is fixedly connected to the outer side of the tube body, an air inlet pipe and an air outlet pipe are fixedly connected to the two sides of the outer shell respectively, and a water scraping mechanism comprises a bidirectional lead screw arranged in the outer shell. A set of fan blades are fixedly connected to the outer side, located at one end of the air inlet pipe, of the bidirectional lead screw in the circumferential direction, an inner threaded ring is in threaded connection with the outer side of the bidirectional lead screw, a sliding ring is slidably connected to the outer side of the pipe body, a water absorption sponge is fixedly connected to the inner ring face of the sliding ring, and annular scraping plates are fixedly connected to the two sides of the sliding ring; the fan blades are driven by hot steam to rotate, the two-way lead screw is