BigPatents India

A once-through steam generator with a vertical gas pass, which is formed by gas-tight tube walls whose tubes are arranged helically or spirally at a lower part of the gas pass, at which burners for fossil fuels are located, and vertically at an upper part of the gas pass, and the lower part of which is bounded at the lower end by a bottom of the gas pass and the upper part of which is bounded at the upper end by a transverse wall of the gas pass, by a convergent cross section of the gas pass formed by the tube walls or by a lower edge of heating surfaces arranged inside the gas pass, whereby the total height ( Hges) of the lower part of the gas pass ( 4 ) is designed according to the relationship that the tube walls ( 3 ) of the lower part ( 4 ) of the gas pass ( 2 ) are divided into a lower and at least one further tube-wall section (8, 9) and the tubes (11) of the lower tube-wall section (8) are internally plain and the tubes (12) of the tube-wall section (9) directly adjacent to the lower tube-wall section (8) are internally multiple lead ribbed in a screw- thread fashion, whereby the height (Hof the lower tube-wall section (8) with respect to the total height (Hges) of the lower part ( 4 ) of the gas pass ( 2 ) is designed according to the relationshipand the height ( H2 ) of the tube-wall section (9) directly adjacent to the lower tube-wall section (8) with respect to the total height (Hgas) of the lower part ( 4 ) of the gas pass ( 2 ) is designed according to the relationship y:\PA\APB_259_S04-006-0_Translation engl_korrigi"erte Fassung.docV! \PA\APB_259_S04-006-0_Trono I at ion engl_Korrckturfaooung.docand the tube internal cross-section ( AQ, A1, A2) of the tubes ( 10, 11, 12 ) of the bottom ( 6 , of the lower tube-wall section ( 8 ) and of the tube-wall section (9) directly adjacent to the lower tube-wall section (8) are designed according to the relationship 1 wherebyH the total height of the lower part of the gass pass in metres, H! the height of the lower tube-wall section in metres, H2 the height of the tube-wall section directly adjacent to the lower tube-wall section in metres, B the width of the gas pass in metres, T the depth of the gas pass in metres, a the gradient angle of the helically inclined ascending tube-wall tubes with respect to the horizontal, AQ the tube internal cross-section of the tubes of the bottom in m2, A1 the tube internal cross-section of the tubes of the lower tube-wall section in m2 and A2 the tube internal cross-section of the tubes of the tube-wall section directly adjacent to the lower tube-wall section in m2 (fig. 1).y:\PA\APB_259_S04-006-0_Translation engl_kprrigierte Fassung.docV!\PA\APB_259_S04-006-0_TranLotion ongl_Korrokturfas5ung.doc