TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: An additional group of heat exchange tubes are arranged between the solid series of heat exchange tubes. The additional group of heat exchange tubes forms the shorter intermediate series. The heat exchange tubes are present between the perforated central pipe and the solid series of the heat exchange tubes and/or between the perforated outer wall and the solid series in annular spaced adiabatic reaction zone, and/or the complete- or intermediate series are interrupted by at least one annular spaced adiabatic reaction zone. The heat exchange tube has a continuous circular cross-sectional or a circular cross-section at their ends and an elongated cross-section in the central region. At least one heat exchange tube of one group is double cranked on at least one tube end and at least one side is mounted in a tube base. The heat exchange tubes exhibit varying cross-sections within the group. The distance between the outer contours of the adjacent complete series or adjacent series and intermediate series increases outwardly or remains the same from the central pipe. The axes of the heat exchange tubes of at least one complete- or intermediate series lies on a radially outward facing straight line. The axes of the heat exchange tubes of at least one complete- or intermediate series forms a wavy line. A distributor or a collector for the heat transfer medium is arranged at least one end, preferably at both ends of the heat exchange tubes. A heat transfer medium inlet and/or a heat transfer medium discharge line are connected with the reactor casing or the upper or the bottom reactor head via a compensator. The perforation of the central pipe and/or the outer wall of the reaction chamber vary in the axial direction of the reactor. A catalyst in the form of a granular packed bed is filled between the heat exchange tubes in the reaction chamber. The ratio of the heat exchange surface of the heat exchange tubes decreases or is constant to the catalyst volume in the radial flow direction and is 10-200 m2/m3, preferably 50-110 m2/m3. The catalyst, which is to be filled, has a particle size of 1-2 mm, a diameter, a length of 3-15 mm, preferably 3-6 mm, or spherical particles with diameter 1-3 mm, preferably 1.5-2 mm. A filling device in the reactor for filling the reaction chamber with the catalyst bed is arranged above the reaction chamber. The filling device comprises at least one catalyst distributor, which is arranged outside the bundle of heat exchange tubes, and many filling tubes. The filling tubes open at their upper pipe ends in at least one catalyst distributor and extends into a dead space formed through the uppermost portion of the reaction chamber. The filling tubes open at their lower pipe end. The curve of all the filling tubes is coordinated in the dead space such that the totality of their lower pipe ends is distributed over the entire cross section of the catalyst chamber.