NOVELTY - The apparatus has a pressure-tight, closed container shell (1) including a lower shell ring (1.3), which receives a lower conical taper (2.3) of a heat exchanger. A bell-shaped container upper part includes a lid (1.5) and a cylindrical section (1.4), which is welded with the lid. The shell ring contains a support ring for the exchanger, a manhole (4), a connecting piece (5.1) for a cooling medium-supply, and another connecting piece (5.2) for a cooling medium-discharge through the exchanger. The upper part is welded with the shell ring by a closure weld (1.6) after assembly of the exchanger.    USE - Thermal apparatus for processes in a pressure-tight closed cylindrical container i.e. entrained-flow gasifier, which is used for partial oxidation of carbon for production of synthesis gas from carbonaceous fuel such as coal dust and torrefied biomass, in a chemical industry.    ADVANTAGE - The container upper part is welded with the lower shell ring by the closure weld after assembly of the heat exchanger, thus enabling future access to the heat exchanger for inspection or repair purposes via an opened cover flange without problems. The apparatus enables better assembly and verifiability of assembly welds at the heat exchangers for the pressure-tight thermal apparatus by a cooling shield for the entrained-flow gasifier. The apparatus avoids the need for an expensive shell flange in an upper part of the cylindrical section, and hindering of assembly of the apparatus by medium guides of the heat exchanger in the container upper part. The apparatus enables complete assembly and testing of pipes of the heat exchanger before end assembly of the upper pressure shell.    DESCRIPTION OF DRAWING(S) - The drawing shows a top sectional view of an entrained-flow gasifier with a cooling shield-vent.    Container shell (1)    Lower shell ring (1.3)    Cylindrical section (1.4)    Lid (1.5)    Closure weld (1.6)    Lower conical taper (2.3)    Manhole (4)    Connecting piece for a cooling medium-supply (5.1)    Connecting piece for a cooling medium-discharge (5.2)