JPH0343521B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the peripheral wall ("tube") of a furnace, such as a boiler, which is constructed by welding a number of tubes through which water passes in order to produce steam side-by-side in a membrane-like manner. (also referred to as "wall" or "wall of enclosing tube"), the lower part of which is composed of a tube extending obliquely in a spiral shape,
The upper part consists of a load-bearing vertical tube and relates to the enclosure tube wall of a furnace adapted to suspend the lower part, and in particular to the transition from a helical tube to a vertical tube circuit. In the following description, the spirally extending oblique tubes will be simply referred to as "oblique tubes", and the load-bearing vertical tubes in the upper part of the furnace will be simply referred to as "vertical tubes".
The invention is particularly applicable to supercritical or subcritical once-through steam generators (boilers) with welded membrane tube walls. BACKGROUND OF THE INVENTION The main problem with this type of steam generator lies in the support structure and in the tube configuration of the transition from skew to vertical tubes. The diagonal tube winds multiple times in a spiral around the furnace at an angle of up to approximately 30° from the horizontal, terminates in a header below the arch of the furnace, and transitions to a vertical tube in the upper part of the furnace. There is. The near-horizontal skew pipe has less ability to carry vertical static loads and requires external support structures to transfer the load to the standpipe.

U.S. Pat. No. 3,027,882 discloses a vertical support bar that connects the diagonal tubes of a furnace to the vertical tubes. U.S. Pat. No. 3,400,689 discloses the provision of a vertical tension member whose lower end is connected to the furnace wall and whose upper end is supported by a spring for suspending support of the furnace tube. US Pat. No. 4,116,168 discloses a configuration in which a diagonal tube provided in the middle section of the furnace is connected to vertical tubes in the upper and lower sections of the furnace via a forked tube. SUMMARY OF THE INVENTION The present invention relates to an enclosure tube wall for a once-through steam generator furnace with a lower section consisting of diagonal tubes fed in parallel from a ring header provided at the bottom of the furnace. The diagonal tube extends helically upward at an angle of up to about 30 degrees from the horizontal to wrap around the furnace at least once and terminates in vertical manifold headers spaced around the furnace. The upper section of the furnace is constituted by load-bearing vertical tubes in fluid communication with the lower section consisting of diagonal tubes. Both the diagonal pipes and the vertical pipes are welded to each other via fins or membrane plates extending over the entire length on both sides of each pipe to form an airtight enclosure. In order to eliminate eccentric loads at the transition between the lower part (oblique pipes) and the upper part (vertical pipes) of the furnace and to simplify the pipe configuration, the pipes of the upper part and the lower part are overlapped. let DESCRIPTION OF THE EMBODIMENTS Referring to FIG. 1, a once-through steam generator 10
A schematic side view, partially in section, is shown. The lower furnace section 12 of the device 10 is formed into a number of diagonal sections 12 connected to each other by membrane plates in the form of panels and extending spirally upwards to a transition section 16 below the arch section 18 of the oven. It is structured accordingly. In the transition section 16, the diagonal tube 13 is in fluid communication with a vertical tube 15, which is also connected in panel form to form an upper furnace section 14, the upper end of the vertical tube 15 communicating with an outlet header 20. There is.

As shown in FIG. 2, the diagonal tubes 13 are connected by membrane plates 26 interposed therebetween and are in the form of panels or tube walls, constituting the lower part of the furnace. A plurality of vertical support strips 22 are suitably spaced laterally around the outer circumference of the lower furnace section 12 to carry the static load of the diagonal tube 13 and transfer the load to the vertical tube 15 of the upper furnace section. It is arranged so as to extend so as to be in contact with the outer surface of the diagonal pipe. A plurality of support bars 24 extending across the entire width of each support strip 22
are arranged at intervals in the vertical direction, and the membrane plate 26 of the oblique tube is coupled to the support strip 22 by welding or the like. The upper end of each support strip 22 (FIGS. 5 and 8)
As will be described later, the load is transferred to a larger number of vertical pipes 1
It is enlarged in a way that it spreads towards the end in order to transmit data to 5.

FIG. 3A shows a conventional construction of a transition section for transferring loads from support strip 22 to vertical tube 15 via fingers 30. As shown in the figure, the longitudinal centerline of the vertical tube 15 coincides with the centerline of the oblique tube 13. Since the static load of the lower furnace section 12 is carried by the support strip 22, a rotational moment is generated due to the eccentric load. In order to eliminate this rotational moment, a complex and expensive pinned linkage 28 is provided between the support strip 22 and the vertical backrest 32. In FIG. 3A, 27 is a membrane plate between the vertical tubes 15.

An improved configuration according to the present invention is shown in FIG. 3B. As shown in FIG. 3B, in accordance with the present invention, vertical tube 15 overlaps diagonal tube 13. The longitudinal centerline of the vertical tube 15 is connected to the support strip 2
2, thereby eliminating rotational moments due to eccentric loads, and therefore
The vertical backrest 32 and linkage 28 required in the prior art configuration shown in Figure A are eliminated. A seal 34 is interposed between the uppermost oblique pipe 13 and the membrane plate 27 of the vertical pipe 15 to ensure airtightness of the furnace wall. In FIG. 3B, 26 is a membrane plate of the oblique tube 13, and 30 is a finger plate.

FIG. 4 is a side view of the transition section of a conventional furnace as seen from inside the furnace. Each diagonal tube 13 extends outwardly from the furnace in the same horizontal plane and terminates in a horizontal outlet header (not shown) located outside the furnace. Since the longitudinal centerline of each vertical tube 15 coincides with the centerline of the oblique tube 13 (see also FIG. 3A),
Each vertical tube 15 must be bent and extended outwardly from the furnace wall at different heights in accordance with the slope of the oblique tube 13. Therefore, the vertical tube 15
The lower ends of each membrane plate 27 are also located at different heights. Therefore, in order to airtightly seal the wall of the furnace enclosure tube, each membrane plate 27 and the uppermost diagonal tube 1 must be
Closing plates 36 of various shapes are required to seal the gap between 3 and 3. As is apparent from FIG. 4, this is an expensive arrangement requiring extensive manual fitting and welding operations in the field during its assembly. In addition, each vertical tube 15
Each vertical tube must be individually manually bent because it must extend outwardly from the furnace wall and connect to an external header (not shown) at a different height.

On the other hand, according to the configuration of the present invention, the fifth to
As shown in FIG. 7, the diagonal tubes 13 are extended outward from the tube wall of the furnace in groups of several (five in the illustrated example). Even if the number of tubes in each group is more than 5,
It may be less. The oblique pipes 13 of each group are connected to the vertical pipes 1
5 and 15 to the exterior of the furnace, terminating in a vertical outlet manifold 38 spaced appropriately around the furnace. Each manifold 38 connects to a horizontal inlet header 40.
The fluid rises from the inlet header 40 through the vertical tube 15 connected to it and passes through the outlet header 20 (first
Flows to Figure). The vertical pipe 15 overlaps several oblique pipes 13 in the upper part of the lower furnace section 12,
It bends outward in a horizontal plane below the outlet group of the diagonal tube and terminates in a horizontal header 40 (FIG. 7). With this configuration, the present invention eliminates the use of the conventional expensive closure plate 36 (FIG. 4) and reduces manual welding operations in the field. In addition, since the vertical tubes 15 can be mechanically bent all at once into a panel, there is no need to manually bend each tube individually as in the conventional case.

Figures 8 and 9 are views similar to Figures 5 and 7, but from the outside of the furnace. As seen in FIG. 8, the lower ends of ten finger plates 30 in the illustrated example are welded to the widened end portion of one support strip, and the upper ends of these finger plates are each welded to a pair of finger plates 30. It is welded to an adjacent vertical tube 15, thereby transferring the load of the lower furnace section 12 to the upper furnace section 14. The number of finger plates 30 can be increased or decreased depending on the magnitude of the static load on the lower furnace section 12 and the width of the widened end portion of the support strip 22.

[Brief explanation of drawings]

Fig. 1 is a partially sectional side view of a once-through steam generator having diagonal tubes and vertical tubes, Fig. 2 is a perspective view of a portion of the lower furnace section consisting of diagonal tubes, and Fig. 3A is a view of the transition section. FIG. 3B is a side view with a partial cross section of a conventional support structure; FIG. 3B is a view similar to FIG. 3A of the support structure of the present invention; FIG. a side view of a tube configuration of a transition section according to the present invention; FIG. 6 is a cut-away top plan view of FIG. 5; FIG. 7 is a cross-sectional view taken along line 7--7 of FIG. 5; FIG. 8 is a side view of the support structure of the present invention as seen from outside the furnace, and FIG. 9 is a cross-sectional view taken along line 9--9 in FIG. 12: Lower furnace section, 13: Oblique tube, 14: Upper furnace section, 15: Vertical tube, 16: Transition section, 22: Support strip, 24: Support bar, 26, 27: Membrane plate, 30:
Finger plate, 34: seal (sealing member).

Claims (1)

[Scope of Claims] 1. A lower furnace section composed of a plurality of diagonal tubes spirally extending upward to a transition section in an enclosing tube wall constituting a furnace for a once-through steam generator;
an upper furnace section configured of a plurality of vertical tubes having a load-bearing capacity and extending upward from the lower furnace section in fluid communication with the diagonal tubes of the lower furnace section; and a lower furnace section for supporting the lower furnace section. a plurality of vertical support strips spaced laterally around the outer periphery of the tube and connected by welding to the diagonal tube; and a plurality of vertical support strips for transferring the static load of the lower furnace section from the support strips to the vertical tube of the upper furnace section. and a vertical tube of the upper furnace section extending downwardly from said transition section so as to overlap a portion of the lower furnace section. 2. The support strip is attached so as to be located in the same plane as the outermost surface of the diagonal tube, and the diagonal tube and the support strip are welded together via a bar interposed between them. An enclosure pipe wall according to claim 1. 3. The enclosing pipe wall according to claim 2, wherein the upper end of each of the support strips is widened in a shape that widens toward the end. 4. The load transfer means comprises a plurality of vertical fingers welded at their lower ends to the widened upper ends of the support strips and each at their upper ends to a pair of adjacent vertical tubes. The enclosing pipe wall as described in paragraph 1. 5. The wall of claim 1, wherein the central longitudinal axis of each vertical tube substantially coincides with the centerline of each support strip. 6. The wall of claim 1, wherein each diagonal tube makes at least one complete wrap around the furnace. 7 The diagonal tubes are grouped into a plurality of tube groups each consisting of a plurality of diagonal tubes arranged vertically in parallel, and each tube group penetrates between the corresponding vertical tubes at the transition portion. 2. The wall of claim 1, wherein the wall extends out of the furnace and terminates in a vertical manifold spaced around the furnace. 8. Each of the vertical tubes is bent outwardly at the transition section in a horizontal plane below each group of skewed tubes and terminates in a horizontal header in fluid communication with the vertical manifold. Enclosure pipe wall according to range 7. 9. The enclosure pipe wall according to claim 1, wherein the diagonal pipe of the lower furnace part and the vertical pipe of the upper furnace part are connected to each other via a membrane plate so as to constitute an airtight panel. 10. The enclosing tube wall according to claim 1, wherein the diagonal tube of the lower furnace section extends upwardly in a helical manner at an angle of at most about 30 degrees from the horizontal.