the mouth of the singe slit is beveled in all cases on the inner edge side the bevel amounts to about 45 u00b0 also in all other embodiments the mouth is so widened in funnel shape in cross section also in cases in which the ramp stones are developed protruding different distances in the region of the singe slit 2 with due consideration of the direction of travel of the goods arrow y the second ramp stone 12 is developed protruding backward in accordance with the first and third embodiments in accordance with the fifth embodiment the ramp stones 11 12 and 13 terminate practically at the same distance from the vertical extent of the flat textile structure 3 the same development is selected also with respect to the same variant of the fifth embodiment only that in that case the initial portion of the combustion chamber 10 has a saw tooth like wall structure designated 48 which produces an eddying of the foot of the flame in this region the profiling shown extends over the entire width of the burner unit in accordance with the third embodiment the ramp stone 11 protrudes forward and the third ramp stone 13 present between it and the ramp stone 12 does so also they protrude to the same extent from the showing of the fourth embodiment it is clear that the intermediate ramp stone 13 which acts in flame jet diverging manner alone assumes an exposed position with respect to the two adjacent ramp stones 11 12 which themselves protrude in the same vertical plane the ramp stones forming the front surface 15 of the burner unit 1 are drawn inward in trough like manner at a distance from.