Abstract: A method for welding two or more conduits includes aligning end portions thereof in an abutting relationship to define a gap. The method includes performing a spatter free root weld along the gap to configure a root layer while the inner circumferential surface side is unobstructed. After the root weld is complete, an outward thrust is applied along the inner circumferential surfaces of the conduits. During the application of the outward thrust, a filler weld is performed along the gap to fill the gap and to facilitate shrinkage of the filler and root weld materials longitudinally and radially outward while preventing pressing out of the filler and root weld materials radially inward of the inner circumferential surface.

Abstract: A tube bundle heat exchanger has tubes which are held at each side in tube plates or oval-tube collecting-tube plates and are connected to these in each case by means of a weld seam. The connection of the tubes to the inlet-side tube plate or oval-tube collecting-tube plate is formed in each case by means of a conical and/or trumpet-shaped transition piece. The cross section of the transition piece reduces as viewed in the gas flow direction in such a way that the inlet-side end, as viewed in the gas flow direction, of the transition piece is connected in a buttjoint to the tube plate or oval-tube collecting-tube plate. The inner and outer contours of the transition piece and of the welded connection region are formed without gaps and comers to the tube plate or oval tube collecting-tube plate and so as to be straight and/or with a radius, measured from the outer contour, of at least 5 mm.

Abstract: An industrial production plant including at least one reactor for producing a flue gas and including a heat exchanger system having a first heat exchanger section for heat exchange between the flue gas and a fluid and a second heat exchanger section for heat exchange between the flue gas and reaction air for the reactor, which can be preheated by the second heat exchanger section. The first heat exchanger section is configured as a double-tube heat exchanger with first tubes each arranged one-way in a respective first jacket tube, and the second heat exchanger section is configured as a tube bundle heat exchanger with a tube bundle of second tubes arranged in a second jacket tube and each arranged one-way in the jacket tube.

Abstract: A heat exchanger having a first section, through which a first medium can flow, and a second section, through which a second medium can flow. During operation a heat exchange takes place between the first and the second medium. The first section has an inlet chamber and first tubes connected to the inlet chamber, and an outlet chamber and second tubes connected to the outlet chamber. The first tubes are each closed at the ends facing away from the inlet chamber and each second tube is at least partly arranged inside one of the first tubes, and the end of the second tube that faces away from the outlet chamber is open to the interior of the respective first tube. The second section has an inlet means and an outlet means.

Abstract: An industrial production plant including at least one reactor for producing a flue gas and including a heat exchanger system having a first heat exchanger section for heat exchange between the flue gas and a fluid and a second heat exchanger section for heat exchange between the flue gas and reaction air for the reactor, which can be preheated by the second heat exchanger section. The first heat exchanger section is configured as a double-tube heat exchanger with first tubes each arranged one-way in a respective first jacket tube, and the second heat exchanger section is configured as a tube bundle heat exchanger with a tube bundle of second tubes arranged in a second jacket tube and each arranged one-way in the jacket tube.

Abstract: A method for welding two or more conduits includes aligning end portions thereof in an abutting relationship to define a gap. The method includes performing a spatter free root weld along the gap to configure a root layer while the inner circumferential surface side is unobstructed. After the root weld is complete, an outward thrust is applied along the inner circumferential surfaces of the conduits. During the application of the outward thrust, a filler weld is performed along the gap to fill the gap and to facilitate shrinkage of the filler and root weld materials longitudinally and radially outward while preventing pressing out of the filler and root weld materials radially inward of the inner circumferential surface.

Abstract: A heat exchanger having a first section, through which a first medium can flow, and a second section, through which a second medium can flow. During operation a heat exchange takes place between the first and the second medium. The first section has an inlet chamber and first tubes connected to the inlet chamber, and an outlet chamber and second tubes connected to the outlet chamber. The first tubes are each closed at the ends facing away from the inlet chamber and each second tube is at least partly arranged inside one of the first tubes, and the end of the second tube that faces away from the outlet chamber is open to the interior of the respective first tube. The second section has an inlet means and an outlet means.

Abstract: A method for welding two or more conduits includes aligning end portions thereof in an abutting relationship to define a gap. The method includes performing a spatter free root weld along the gap to configure a root layer while the inner circumferential surface side is unobstructed. After the root weld is complete, an outward thrust is applied along the inner circumferential surfaces of the conduits. During the application of the outward thrust, a filler weld is performed along the gap to fill the gap and to facilitate shrinkage of the filler and root weld materials longitudinally and radially outward while preventing pressing out of the filler and root weld materials radially inward of the inner circumferential surface.

Abstract: A tube bundle heat exchanger has tubes which are held at each side in tube plates or oval-tube collecting-tube plates and are connected to these in each case by means of a weld seam. The connection of the tubes to the inlet-side tube plate or oval-tube collecting-tube plate is formed in each case by means of a conical and/or trumpet-shaped transition piece. The cross section of the transition piece reduces as viewed in the gas flow direction in such a way that the inlet-side end, as viewed in the gas flow direction, of the transition piece is connected in a buttjoint to the tube plate or oval-tube collecting-tube plate. The inner and outer contours of the transition piece and of the welded connection region are formed without gaps and corners to the tube plate or oval tube collecting-tube plate and so as to be straight and/or with a radius, measured from the outer contour, of at least 5 mm.