A flat heat exchanger plate typically used in a bulk material heat exchanger is provided. The flat heat exchanger plate is designed to operate under a negative internal pressure to eliminate depressions or dimples that are typically formed into the sides of these types of heat exchanger coils during the manufacture process. With the removal of the depressions or dimples the tendency for bulk material to accumulate to the exterior surface of the plate is reduced, thereby increasing the service period of the plate.