Energy recovery apparatus suitable for the thermal treatment of fluids or solids, comprising: - means for the first fluid inflow; - a first containment chamber for the containment of a first fluid, provided with a deflector that develops itself in the chamber interior substantially along its whole length giving it the form of a first hollow annulus (2"); - thermal exchange means for thermal exchange between the first fluid and a second fluid or a solid, comprising a second chamber for the solid or, for the second fluid, a second hollow annulus placed in contact, externally or internally, with said containment chamber of the first fluid and having parallel longitudinal symmetry axis preferably coinciding with the longitudinal symmetry axis of said containment chamber, wherein in the thermal exchange between the first fluid and the second fluid, said second hollow annulus is suitable for containing conduits that extend over at least one of the external wall of the containment chamber, in helicoidal form or in linear form with longitudinal symmetry axis parallel to the longitudinal symmetry axis of said containment chamber, which are suitable for making the second fluid flow, between entrance and exit, in equicurrent, in countercurrent or in equicurrent and countercurrent sequence with the circulation direction of the first fluid, wherein the second fluid is a diathermic oil and wherein the second chamber, suitable for circulating solids inside, substantially cylindrical, positioned externally to said first containment chamber, is suitable to rotate around its longitudinal symmetry axis preferably parallel or coincident with the longitudinal axis of the first containment chamber and forming an interspace with the external wall of the first containment chamber, the solids to be treated being moved by means of the contact with the internal wall of the rotating second chamber; - means for the first fluid outflow; - possible means for the treatment of emitted fluids or solids; the means for the first fluid inflow being suitable for sending in equicurrent or in countercurrent with the circulation direction of the second fluid or of the solid, said means for the inflow and outflow of the first fluid comprising connections, and the containment chamber and the thermal exchange means being realised in metallic material resistant to high temperature, and the first chamber and the second chamber being made of materials resistant to temperatures in the range 200-1000 °C. - means for the first fluid inflow; - a first containment chamber for the containment of a first fluid, provided with a deflector that develops itself in the chamber interior substantially along its whole length giving it the form of a first hollow annulus (2"); - thermal exchange means for thermal exchange between the first fluid and a second fluid or a solid, comprising a second chamber for the solid or, for the second fluid, a second hollow annulus placed in contact, externally or internally, with said containment chamber of the first fluid and having parallel longitudinal symmetry axis preferably coinciding with the longitudinal symmetry axis of said containment chamber, wherein in the thermal exchange between the first fluid and the second fluid, said second hollow annulus is suitable for containing conduits that extend over at least one of the external wall of the containment chamber, in helicoidal form or in linear form with longitudinal symmetry axis parallel to the longitudinal symmetry axis of said containment chamber, which are suitable for making the second fluid flow, between entrance and exit, in equicurrent, in countercurrent or in equicurrent and countercurrent sequence with the circulation direction of the first fluid, wherein the second fluid is a diathermic oil and wherein the second chamber, suitable for circulating solids inside, substantially cylindrical, positioned externally to said first containment chamber, is suitable to rotate around its longitudinal symmetry axis preferably parallel or coincident with the longitudinal axis of the first containment chamber and forming an interspace with the external wall of the first containment chamber, the solids to be treated being moved by means of the contact with the internal wall of the rotating second chamber; - means for the first fluid outflow; - possible means for the treatment of emitted fluids or solids; the means for the first fluid inflow being suitable for sending in equicurrent or in countercurrent with the circulation direction of the second fluid or of the solid, said means for the inflow and outflow of the first fluid comprising connections, and the containment chamber and the thermal exchange means being realised in metallic material resistant to high temperature, and the first chamber and the second chamber being made of materials resistant to temperatures in the range 200-1000 °C.