Refractory tube, into which refractory tube a sleeve shaft (1, 1', 1", 1′′′) with at least one inlay (3, 3', 3", 3′′′) for collecting particles (31") originating from the material of the sleeve shaft (1, 1', 1", 1′′′) at least in part, is inserted, wherein at least one fluid can flow through the sleeve shaft (1, 1', 1", 1′′′) along an axial direction (R, R', R", R"') which is parallel to the main extension of the sleeve shaft (1, 1', 1", 1′′′), wherein the inlay (3, 3', 3", 3"') comprises at least one first wall section (5, 5', 5", 5"'), wherein the inlay (3, 3', 3", 3"') is or can be inserted at least in part into the sleeve shaft (1, 1', 1", 1′′′) such that at least one part of the first wall section (5, 5', 5", 5′′′) has a radial distance from at least one first area (7, 7', 7", 7′′′) of the inner surface (9, 9', 9", 9′′′) of the sleeve shaft (1, 1', 1", 1′′′), and, hence, that the inlay (3, 3', 3", 3′′′) together with the first area (7, 7', 7", 7′′′) of the inner surface (9, 9', 9", 9′′′) of the sleeve shaft (1, 1', 1", 1′′′) encloses at least one volume domain (11, 11', 11", 11′′′), which volume domain (11, 11', 11", 11′′′) is limited in the axial direction (R, R', R", R′′′) by a limiting element (13, 13', 13", 13"') comprised by the inlay (3, 3', 3", 3′′′), wherein the inlay (3, 3', 3", 3′′′) comprises at least one zone (17, 17', 17", 17′′′) of cylindrical form, and the first shell (19, 19', 19", 19′′′) of at least one first section (21, 21', 21", 21′′′) of the cylindrical zone (17, 17', 17", 17′′′) comprises the first wall section (5, 5', 5", 5′′′), wherein the first section (21, 21', 21", 21"') comprises at least one first end section (23, 23', 23", 23′′′) of the inlay (3, 3', 3", 3"'). wherein at least one fluid can flow through the sleeve shaft (1, 1', 1", 1′′′) along an axial direction (R, R', R", R"') which is parallel to the main extension of the sleeve shaft (1, 1', 1", 1′′′), wherein the inlay (3, 3', 3", 3"') comprises at least one first wall section (5, 5', 5", 5"'), wherein the inlay (3, 3', 3", 3"') is or can be inserted at least in part into the sleeve shaft (1, 1', 1", 1′′′) such that at least one part of the first wall section (5, 5', 5", 5′′′) has a radial distance from at least one first area (7, 7', 7", 7′′′) of the inner surface (9, 9', 9", 9′′′) of the sleeve shaft (1, 1', 1", 1′′′), and, hence, that the inlay (3, 3', 3", 3′′′) together with the first area (7, 7', 7", 7′′′) of the inner surface (9, 9', 9", 9′′′) of the sleeve shaft (1, 1', 1", 1′′′) encloses at least one volume domain (11, 11', 11", 11′′′), which volume domain (11, 11', 11", 11′′′) is limited in the axial direction (R, R', R", R′′′) by a limiting element (13, 13', 13", 13"') comprised by the inlay (3, 3', 3", 3′′′), wherein the inlay (3, 3', 3", 3′′′) comprises at least one zone (17, 17', 17", 17′′′) of cylindrical form, and the first shell (19, 19', 19", 19′′′) of at least one first section (21, 21', 21", 21′′′) of the cylindrical zone (17, 17', 17", 17′′′) comprises the first wall section (5, 5', 5", 5′′′), wherein the first section (21, 21', 21", 21"') comprises at least one first end section (23, 23', 23", 23′′′) of the inlay (3, 3', 3", 3"'). <EOS>