of the fuel and process air process air entering the burner is caused to spin by the use of a swirl generator the fuel process air mixture proceeds into the combustion section of the burner where the swirling flow is caused to recirculate to ensure complete combustion of the fuel in the combustion chamber the mixture of burned fuel and process gas transfers its energy flamelessly to the process gas circulating outside the burner combustion chamber and is hot enough to ignite the process gas there which then burns separately from the burner combustion chamber such as in the main combustion enclosure of the thermal post combustion device application_number US 35660194 A description turning first to fig6 there is shown a schematic view of a burner 1 mounted as part of a device 100 for the post combustion of a process gas the device 100 features an outer side 101 in which an opening 102 has been made to receive the burner 1 as well as feed openings 103 104 for process gas and exhaust openings 105 106 for combustion substances running parallel to the external face 101 feed ducts 107 108 conduct the process gas entering through feed openings 103 104 respectively which then passes through or along the combustion chamber 50 into a flame tube 109 integrated in the device 100 the process gas flows from one outlet of the cold side of a heat exchanger not shown into the feed ducts 107 108 a portion of the process gas identified by.