Heat exchanger

A heat exchanger comprising:

• a gas-tight casing, provided with a sleeve for discharging burnt gases,
• at least one tube, made of a thermally good conductive material and inside which a fluid to be heated can circulate, the at least one tube being helically wound so as to form a helical winding with a longitudinal axis and a plurality of adjacent turns, the helical winding being disposed inside the gas-tight casing,
• means for supplying and/or producing hot gases inside the casing, so as to define a combustion chamber inside the casing,
• the helical winding being arranged so as to provide an interstice between two adjacent turns,
• the at least one tube having a straight section, a front face and a rear face opposite to each other, an intrados side oriented towards the longitudinal axis and an opposite extrados side oriented towards the casing, the front face and the rear face of the tube being planar or substantially planar and being located on either side of the interstice,
• wherein the at least one tube has a shoulder on the front face and/or the rear face,
• wherein the shoulder extends from the intrados side of the tube in the direction of the extrados side of the tube, over part of a height of the straight section of the tube,
• wherein the shoulder also extends either over an entire length of the at least one tube located in the combustion chamber, or over the entire length of the at least one tube located in the combustion chamber with the exception of a first or a last turn of the helical winding,
• wherein each interstice between two adjacent turns is calibrated either using a tooth of a comb introduced into the interstice between two turns, on the extrados side of the tube, or using several protruding elements, formed on the front face and/or on the rear face of the at least one tube, each protruding element formed on one turn of the tube bearing respectively against the rear face and/or the front face of the adjacent turn,
• so that the shoulder makes possible to recover soot and slag entrained in the hot gases that pass through the interstices.