Heat exchanger with tube bundle convenient to replace

The heat exchanger comprises a shell, a pipeline positioning plate is inserted into the shell in a sliding mode, handles are symmetrically and fixedly installed at the side ends of the pipeline positioning plate, and positioning devices are symmetrically and fixedly installed at the top and the bottom of the end, close to the pipeline positioning plate, of the shell. The butt joint device is slidably inserted into the end, away from the shell, of the positioning device, the positioning device comprises an air cylinder, a piston rod, a first connecting block, a butt joint round head and a U-shaped bolt rod, the piston rod is slidably inserted into the air cylinder, and the first connecting block is fixedly connected to the center of the end, away from the air cylinder, of the piston rod; the butt joint round head is fixedly connected to the center of the end, away from the piston rod, of the first connecting block, and the U-shaped bolt rod is slidably inserted into the side end of the first connecting block.