A heat exchanger for cooling a hot gas that contains solid particles,
comprising heat exchanger tubes through which the hot gas flows, with the
tubes being surrounded by a casing, and with ends of the tubes being
welded, via weld seams, into bores of respective tube plates disposed at
the ends of the casing. A protective layer coats the end face of the gas
inlet side tube plate, an inner wall of the bores, the weld seams, and an
inlet region of the heat exchanger tubes. The protective layer comprises
a metallic adhesive layer, a high temperature and erosion resistant
ceramic layer, and a high temperature and erosion resistant metal layer
disposed between the adhesive layer and the ceramic layer.