Claims:We claim:
1. A method (500) for formation of boiler spiral wall tube panel in stepped manner, the method (500) comprising:
forming first panel (05);
forming second panel (06);
placing the first panel (05) and the second panel (06) one over the other, wherein the first panel (05) is placed with a offset distance (D1) from vertical line coming from edge of the second panel (06), wherein the second panel (06) is placed an offset distance (D2) from vertical line coming from edge of the first panel (05);
joining the first panel (05) and the second panel (06) with the placement having the offset distance (D1 and D2) by welding for form stepped panel;
marking of taper angle (08, 07) on the formed stepped panel (09+10);
cutting the marked tapper end portion of the stepped panel (09+10) to get trapezium or parallelogram shaped stepped panel.

2. The method (500) as claimed in claim 1, wherein length (L1) and (L2) of the first and second panel (05, 06) is derived based of taper angle in the trapezium or parallelogram shaped stepped panel.

3. The method (500) as claimed in claim 1, wherein the method further comprising introducing number of steps on the first and second panel (05, 06) during formation of the first and second panel (05, 06).

4. The method (500) as claimed in claim 1, wherein the offset distance (D1 and D2) of the first and second panel (05, 06) depends on taper length of the stepped panel.

5. The method (500) as claimed in claim 1, wherein the first panel (05) and the second panel (06) are welded together with the offset distance (D1 and D2).

6. The method (500) as claimed in claim 2, wherein the length (L1) of the first panel (05) is length of the trapezium or parallelogram shaped panel (L) minus the offset distance (D1) (L-D1).

7. The method (500) as claimed in claim 2, wherein the length (L2) of the second panel (06) is length of the trapezium or parallelogram shaped panel (L) minus the offset distance (D2) (L-D2).

8. The method (500) as claimed in claim 1, wherein the wherein the offset distance (D1) is on opposite side of the offset distance (D2).
, Description:FORMATION OF BOILER SPIRAL WALL TUBES OF ALLOY STEEL THROUGH STEPPED FORMATION
FIELD OF INVENTION:
[001] The present subject matter described herein relates to a method of formation of boiler spiral wall tubes. More particularly, the invention relates to formation of boiler spiral wall tubes of parallelogram or trapezium shaped panel in a stepped manner in a panel formation machine.
BACKGROUND AND PRIOR ART:
[002] Panels in boiler are tube aligned beside each other, separated by plates. These plates are called fin flats. The tubes are welded with the fin flats on both sides.
[003] Usually the panels in sub-critical boilers are rectangular in shape. The formation of these panels is done in a 20 torch machine. The output of the machine is a rectangularly formed panel. The boiler spiral wall panels pertaining to high pressure high temperature steam generators usually comes in shape of a parallelogram or trapezium.
[004] Now, even for this case, the tubes are formed by as a rectangular raw panel. Due to its parallelogram or trapezium shape, the rectangularly formed panels have to be cut in the ends to attain the required shape.
[005] Figure 1 shows the conventional method of boiler spiral wall tube parallelogram or trapezium shape panel formation for high pressure high temperature steam generators.
[006] In the figure 1, to make the panel 02 in parallelogram shape the tubes are formed in rectangular manner as shown, after which, the taper angle 04 is marked and end taper portions (i.e., 01 and 03) are cut out to get the required panel. These cute taper end portions 01 and 03 generated are in the end scrapped as waste, which constitutes a huge amount. Hence there is a need to find out a suitable method to get maximum utilization of tubes and avoiding scrap as much as possible. Therefore, there is a requirement for a method for formation of trapezium or parallelogram shaped boiler tubes which amounts to less scrap, less welding consumable, and less cycle time consumption.
OBJECTS OF THE INVENTION:
[007] The principal objective of the present invention is to provide a method for formation of boiler spiral wall tube parallelogram or trapezium shape panel for high pressure high temperature steam generators.
[008] Another object of the present subject matter is to provide a method which is optimum in terms of scrap reduction and ease of panel formation.
SUMMARY OF THE INVENTION:
[009] The subject matter disclosed herein relates to a method for formation of boiler spiral wall panel in steps. In the present method, first panel is formed in the panel formation machine. The length L1 of the first panel is derived based of on taper angle in panel and the number of steps introduced. Next, second panel is formed in the panel formation machine. The length L2 of the second panel is again derived based of taper angle in panel and the number of steps. The two panels, i.e., first panel and the second panel are placed one over the other with an offset distance (D1) that depends on the taper length of panel. The offset distance on the other end (D2) is also maintained. The two panels are welded together in panel formation machine to get stepped panel. After forming the stepped panel, the taper angle is marked and end taper portions are cut out to get the required panel. In the present method, the panel is formed with considerably less scrap material as compared to conventional method of panel formation.
[0010] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0012] Fig. 1 illustrates old method of boiler spiral wall tube formation;
[0013] Fig. 2 illustrates the upper half of panel formed by present method, in accordance with an embodiment of the present subject;
[0014] Fig. 3 illustrates the lower half of panel formed by present method, in accordance with an embodiment of the present subject;
[0015] Fig. 4 illustrates total assembly of stepped panel by the present method, in accordance with an embodiment of the present subject; and
[0016] Fig. 5 illustrates a method for formation of a trapezium shape panel, in accordance with an embodiment of the present subject.
[0017] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0018] The subject matter disclosed herein relates to a method for formation of stepped panel of tubes. In the present method, first panel is formed in the panel formation machine. The length L1 of the first panel is derived based on taper angle in panel and the number of steps introduced for forming the required panel. Next, second panel is formed in the panel formation machine. The length L2 of the second panel is again derived based on taper angle in panel and the number of steps introduced for forming the required panel. The two panels, i.e., first panel and the second panel are placed one over the other with an offset distance (D1) that depends on the taper length of panel. The offset distance on the other end (D2) is also maintained. The two panels are welded together in panel formation machine to get stepped panel. After forming the stepped panel, the taper angle is marked and end taper portions are cut out to get the required panel. In the present method, the panel is formed with considerably less scrap material as compared to conventional method of panel formation.
[0019] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0020] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0021] The boiler spiral wall panels pertaining to high pressure high temperature steam generators usually comes in shape of a parallelogram or trapezium. The formation of which is usually done in a rectangular shape in panel formation machine. The formed rectangle panel is then cut on the edges to get the required shape (i.e. of a parallelogram or trapezium). The waste generated as scrap due to this cutting is directly proportional to the angle of taper given in the panel which is usually 20 deg. The scrap generated constitutes to almost 5% weight of the required panel. It is hence reasoned to minimize the scrap generated due to this process as much as possible.
[0022] For formation of boiler spiral wall panel by this method, the number of tubes involved in a panel is split and the length of tubes is calculated accordingly. In the present subject matter, the tubes are formed in the panel formation machine with an offset distance, which depends on the taper length given at the end of the panel, and no of steps introduced. After formation, the marking is done along the stepped line for cutting the panel to required shape.
[0023] The stepped panel formation is a method where the no of tubes in panel are split into ‘n’ parts and panel formation is done in ‘n-1’ steps. The parts are joined together with an offset distance. The scrap generated by this method is at least half of the scrap that gets generated through conventional panel formation. This decrease in scrap in turn leads to decrease in cycle time involved in panel formation, the material consumption, and the welding consumable for panel formation.
[0024] Figure 2 illustrates formation of one part, i.e., first panel of the stepped panel which is formed in the panel formation machine. The first panel 05 has length (L1) which is derived based on taper angle in panel and the number of steps is introduced for formation of panel.
[0025] Figure 3 illustrates the other part, i.e., second panel of the stepped panel which is formed in the panel formation machine. The second panel 06 has a length L2 which is derived based on taper angle in panel and the number of steps introduced on the second panel 06.
[0026] Figure 4 illustrates the total assembly of stepped panels. The first panel 05 (09) is placed over the second panel 06 (10) with an offset distance D1 and D2. The offset distance D1 and D2 depends on the taper length of the required panel. The length of the panel 05, 06 is based on the taper angle of the final stepped panel.
[0027] Length L1 of the first panel is calculated as
L1 = L - D1
Where L is length of panel.
Where D1 is offset distance of the first panel which depends on taper length of the panel.
[0028] Length L2 of the second panel is calculated as
L2 = L – D2
Where L is length of panel.
Where D2 is offset distance of the second panel which depends on taper length of the panel.
[0029] Next, the placed first panel 05 and the second panel 06 is welded together to form a stepped panel. In the formed stepped panel, end sides of the panel 05 and the panel 06 are not aligned with each other. Once the first panel 05 and the second panel 06 are welded together, a taper angle 04 is marked and end taper portions 07, 08 are also marked. The taper end portions are cut out to get the required trapezium or parallelogram shaped panel 09+10.
[0030] Figure 5 illustrates the method for formation of the trapezium or parallelogram shaped panel, in accordance with the present subject matter. The method 500 illustrates each step for formation of the trapezium or parallelogram shaped panel in the panel formation machine. At step 502, first panel 05 (as shown in figure 2) is formed in the panel formation machine. The first panel has length L1 which is derived based of taper angle in stepped trapezium panel and the number of steps introduced.
[0031] At the step 504, second panel 06 (as shown in figure 3) is formed in the panel formation machine. The first panel has length L2 which is derived based of taper angle in stepped trapezium panel and the number of steps introduced.
[0032] At the step 506, the first panel 05 is placed over the second panel 06 (as shown in figure 4). The first panel 05 is placed over the second panel 06 in such a manner that the Length L of the trapezium or parallelogram of the panel is achieved at upper and lower portion. The first panel 05 is placed with an offset distance (D1) from vertical line coming from edge of the second panel 06. The second panel 06 is placed an offset distance (D2) from vertical line coming from edge of the first panel 05.
[0033] At step 508, joining the first panel 05 and the second panel 06 by welding keeping the offset distance D1 and D2. By welding the first panel 05 with the second panel 06 with offset distance D1 and D2, a stepped panel 09+10 is formed.
[0034] At the step 510, marking the formed stepped panel 09+10 with a taper angle 04.
[0035] At the step 512, cutting out the tapered end portion 08 from the offset D1 side and tapered end portion 07 from the offset D2 side to get trapezium stepped panel from the stepped panel. In the cutting step, only taper end portion 08 from the first and second panel is cut out by leaving the rectangular area of D1 as blank, which saves the material. Similarly for the tapered end portion 7, which save the panel material with rectangular area of D2.
[0036] By placing and joining the first panel and the second panel with offset distance D1 and D2 according to taper angle, generation of scrap material by cutting the tapered end portion is considerably less as compared to the conventional method of panel formation. The present method can be extended to formation of spiral wall panels with ‘n’ no of steps, where n=1, 2, 3, 4…
[0037] Any reduction in scrap pertaining to this method in turn leads to the following:
[0038] Material consumption reduction.
[0039] Cycle time reduction in panel formation.
[0040] Welding consumable reduction for panel formation.
[0041] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.