Full-welding type three-flow-process corrugated plate air preheater

The utility model relates to a full-welding type three-flow-process corrugated plate air preheater, which comprises air inlet and outlet loudspeakers, smoke gas inlet and outlet loudspeakers, a first connecting box, a second connecting box, a first main heat exchange unit, a second main heat exchange unit and a third main heat exchange unit, wherein the three main heat exchange units all consist of a plurality of heat exchange unit modules, corrugated expansion sections and unit frameworks. The utility model has the advantages that 1) a novel corrugated plate is adopted for replacing the traditional heat transfer element, and turbulent flows can be formed at the lower reynold number; 2) the corrugated pipe expansion sections are arranged inside the structure, the temperature difference stress caused by heat expansion of media at two sides can be avoided, and the damage of the temperature difference stress to equipment caused by nonuniform heat expansion of a plate beam and a box body can be avoided; 3) The ma