JPH0419441B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a furnace wall structure that constitutes a furnace such as a boiler and a peripheral wall of a flue.

The surrounding wall of a furnace such as a power generation boiler is formed into a panel shape by welding a cooling pipe 1 and a flat plate 2 as shown in Figs. 1 and 2, or by welding a cooling pipe 4 with fins as shown in Figs. It is well known that the fin portion 5 and the fin portion 5' are integrated by welding to form a gas seal wall as a so-called weld wall (numerals 3 and 6 indicate welded portions).

However, in some boilers and the like, it is practically impossible to form the entire furnace wall into the above-mentioned welded wall structure, and as shown in FIGS. 5 and 6, a structure in which intermittent fins are welded is used in some parts.

As shown in FIG. 6, in a conventionally known method, the weld wall 11 and the interrupted fin portion 12 are simply separated linearly.

In such a conventionally known structure, at the boundary between the weld wall and the intermittent fin portion, the panel edge of the weld wall (section A in Figure 6) changes as the rigid cross section of the furnace wall panel changes. Vertical and horizontal forces due to its own weight and external forces, as well as thermal stress generated in the panel, concentrate, resulting in excessive stress.

For this reason, there have been drawbacks such as cracks occurring in the portion, or cracks extending to the inner surface of the cooling pipe, resulting in a blowout or leakage accident.

In recent power generation boilers, etc., startup and shutdown and load fluctuations are frequently repeated due to energy conservation and changes in power demand.Thermal stress generated on the furnace wall is also excessive, and the number of repetitions is large, resulting in a long working life. Due to the extremely harsh conditions, it is conceivable that the conventionally known structure would be in an extremely dangerous situation.

In view of the above, the present invention installs the ends of the weld wall panel at the boundary between the weld wall and the intermittent fin pipe or the bare pipe by shifting the fin weld end position in an arc shape or step shape.
When reducing stress concentration at the end of the welded wall panel and connecting two welded walls of different sizes, at the part where the two connecting parts change at right angles, The welded fins are installed by shifting the welded ends in an arc or step shape to alleviate stress concentration in the area, and is a weld formed by welding multiple pipes together via fins or molten metal. The present invention provides a furnace wall structure consisting of a panel, characterized in that the terminal ends of the fins or molten metal are arranged in an arc shape or a step shape in the tube axis direction at the end of the welded panel.

According to the present invention, the end portions of the fins or molten metal are arranged in an arc shape or step shape in the direction of the tube axis at the end portion of the panel, so that stress concentration in this portion is significantly alleviated, and even under severe operating conditions. It is possible to obtain a furnace wall structure that is sufficiently durable.

An embodiment of the present invention will be described below based on the drawings.

Figure 1 shows a so-called Uylded panel made by alternately welding cooling pipes and flat plates that form the furnace wall of a power generation boiler, etc., and Figure 2 shows the -
A cross-sectional view, FIG. 3, shows a welded panel manufactured by welding the fins of a cooling pipe with fins, and FIG. 4 shows a cross-sectional view taken from FIG. 3. Fifth
The figure shows an example of a floor plan of a furnace wall of a power generation boiler or the like. FIG. 6 shows details of part A in FIG. 5 using conventionally known means. FIGS. 7 and 8 are detailed structural diagrams of section A in FIG. 5 when the means of the present invention is used. FIGS. 9 and 10 show one embodiment of the detailed shape of the fin end. FIG. 11 is a comparative explanatory diagram of the stress distribution situation at the panel boundary between the conventionally known means and the present invention means.

1 is a cooling pipe, 2 is a fin or molten metal, 3 is a welded part between cooling pipe 1 and fin 2, 4 is a cooling pipe with fins, 5 is a fin part of cooling pipe 4 with fins, 6 is a fin part 5 and shows the welded portion of the fin portion 5'. Reference numeral 7 indicates a fin or fusion weld panel on the front wall of the furnace, 8, 9, and 10 also indicate side wall panels, 11, 12, and 13 each indicate a ceiling cooling wall, and 11 indicates a fin or fusion weld panel. The tube panel 12 indicates a bare tube section or a tube section with interrupted fins. Reference numeral 18 indicates a bare tube or a finned tube at the lower end of the cooling wall 9. Section A indicates the end of the ceiling cooling panel, and sections B and C similarly indicate stepped portions within the panel plane caused by differences in the shape of the heat exchanger or the size of the panel in the side wall panel.

Recent boilers for power generation, etc., have become higher in temperature and pressure due to energy conservation and changes in electricity demand.
Furthermore, rapid start-stops and load fluctuations are becoming more frequent, and the thermal stress generated in the cooling pipe panels forming the furnace walls is also becoming excessive. In particular, the conditions at the boundary where the shape of the cooling pipe panel changes are extremely severe, and conventional methods are extremely dangerous. The present invention was developed to enable safe operation even under such severe conditions.

That is, in the conventionally known means, as shown in FIG.
2, all parts including the panel end portion A are divided into approximately straight lines.

However, in the welded panel portion 11, the cooling pipe 1 and the fins 2 are formed into a single plate shape by welding 3, and the rigidity within the plate surface of the panel 11 is extremely large. . On the other hand, the intermittent fin tube portions 12 have the rigidity of individual tubes, and are extremely fine compared to the rigidity of the panel 11.

Therefore, if thermal stress occurs at the boundary between panels with different degrees of rigidity, the stress will be concentrated at the end of the panel, causing excessive stress and causing frequent startup and stoppages. It is not safe as there is a risk of repeated stress, cracks, and explosion accidents. FIG. 11D shows the stress distribution situation in this part.

The present invention is characterized in that it has a structure that is sufficiently safe even under such frequent startup and stoppages, load fluctuations, etc.

That is, as shown in FIG. 7 or FIG. 8, at the boundary between panels of different rigidity, the end of the fin or molten metal is divided into a substantially straight line at the center of the panel, and at the edge A of the panel. By shifting it in a substantially arc shape or step shape, stress concentration at the end A in the conventionally known means is alleviated as shown in Figure 11E, and by reducing the local stress, it is possible to reduce the stress concentration at the end A. It is possible to provide a heat exchanger furnace wall that can be operated sufficiently safely even during startup, shutdown, load fluctuations, etc.

By using the arcuate or stepped welded panel edges of the present invention in sections B and C in FIG. 3, it is completely safe as described above.

Furthermore, the shape of the terminal end of the fins 2 between each cooling pipe 1 can be arbitrarily set to suit its function, as shown in FIGS. 9 and 10.

[Brief explanation of drawings]

Figures 1 and 3 are front views of the welded panel, Figure 2 is a - arrow view in Figure 1, Figure 4 is a - arrow view in Figure 3, and Figure 5 is a perspective view of the boiler furnace wall; 6 is an enlarged view of the end of a conventional welded panel, FIGS. 7 and 8 are enlarged views of the end of a welded panel according to an embodiment of the present invention, and FIGS. 9 and 10 are enlarged views of the end of the fin or molten metal.
FIG. 11 is a stress distribution diagram at the boundary of the welded panel. 11... Welded panel, 12... Intermittent fin pipe section, A... Welded panel end.

Claims (1)

[Claims] 1. In a furnace wall structure consisting of a welded panel formed by welding a plurality of tubes through fins or molten metal, the terminal end of the fin or molten metal is attached at the end of the welded panel in the direction of the tube axis. A furnace wall structure characterized by being arranged in an arc shape or a step shape.