Air preheater

The utility model provides an air preheater. The air preheater comprises a box; a separator is arranged in the box to divide the box into a heat dissipation region and a heat absorption region which are arranged up and down and communicated with each other; a plurality of heat pipes are mounted on mounting holes formed in the separator by inserting flanges; heat-absorbing spiral fins are connected to the surfaces of the heat pipes in the heat absorption region; heat-dissipating spiral fins are connected to the surfaces of the heat pipes in the heat dissipation region. The air preheater has the advantages that the cross flow of cold and hot fluids is effectively avoided, each heat pipe is an independent seal unit and mounted and sealed in the box by use of the flange, and also is convenient to demount, the number of the heat pipes or the heat transfer area ratio of the cold and hot sides of the heat pipes is adjusted so that the wall temperature of the heat pipes is kept above a dew point temperature and dew p