A heat exchanger for use in a contact group of a sulfuric acid plant includes a chamber in which a tube bundle is arranged on a circular ring. A gas space is formed between the tube bundle and a chamber casing surrounding the tube bundle. A gas supply opening is provided in the chamber casing and is configured to introduce a gas into the gas space substantially radially to the tube bundle. A gas outlet opening adjoins an interior space enclosed by the tube bundle in a substantially axial direction. A center of the tube bundle is offset with respect to a center of the chamber casing in a direction opposite to the gas supply opening.