Title of Invention

DUAL FIXTURE FOR FABRICATING AND DRILLING OF CONNECTING PLATE ASSEMBLY OF A ROTARY AIR PREHEATER

Abstract

A dual fixture (C) for fabrication and drilling of a connecting plate assembly (D and E) of an air preheater consists of rolled fixture beams (2) joined together to form a fixture (C) of an inverted U shaped structure. The dual fixture (C) is adapted by laying the fixture beams (2) for center section and one side of CPA on the layout of required air preheater size marked on the grouted fitter"s bars (1) and firmly secured by clamp (3) with T-bolt (4) and nut 5 for fabricating and drilling air side CPA (D) and gas side CPA (E) of an air preheater in two stages separately.

Full Text

FIELD OF INVENTION The invention relates to fabrication and drilling of connecting plate assembly (CPA) for rotary regenerative air preheaters (APH) in general and to a fixture for fabricating and drilling the connecting plate assembly in shop floor in particular. BACKGROUND OF THE INVENTION A rotary regenerative air preheater is a boiler auxiliary used in power plants. The Regenerative Air Preheater absorbs waste heat from flue gas, and then transfers this heat to incoming cold air by means of continuously rotating heat transfer elements of specially formed metal plates through air and gas streams. Air preheater mainly consists of rotor assembly connected to central rotor post with support & guide bearings, octagonal shaped rotor housing connected to connecting plate assemblies at both the ends, sealing and drive arrangement. The housing surrounding the rotor is provided with bolting connections at both the ends and is adequately sealed by radial and axial sealing members forming an air passage through one half of the preheater and the gas passage through the other. As the rotor slowly revolves the mass of the elements alternatively pass through the air and gas passages, heat is absorbed by the element surfaces passing through the hot gas stream, then as the same surfaces are carried through the air steam, they release the stored up heat thus increasing the temperature of the incoming combustion or process air. Connecting plate assemblies (CPA) are used to house both ends of on rotorhousing. This consists of a main center section, primary center section, corner and center ducts with channel and pipe bracings. Based on the engineering requirement this CPA will be of BI-SECTOR or TRI-SECTOR. In Bi Sector design air side and gas side duct connections will be there, but in case of tri-sector air slide will have primary center section, which will form a separate duct connections for primary air and secondary air. These ducts connections are independent of each other but located primarily with respect to APH center. The CPA has octagonal flanged holes at one end to connect rotor-housing panels and at the other end rectangular flanged holes to connect gas side and air side ducts. Fixtures are needed for the manufacture of the CPA on the shop floor. The size of an APH depends on the rating of the boiler of which the APH would form an auxiliary. Therefore there are many sizes of APH and consequently, the CPA sizes are also several. SO, depending upon the requirement of APH different sizes of CPA are to be fabricated. In the prior art every CPA must be fabricated with the help of a octagonal fixture formed by rolled beams lying on the leveled fitter's bar, which is dimensioned to suit the fabricational requirement of the particular size of the CPA (Refer Figure- A). The fixture beams (2) are placed on the grouted and leveled fitter's bars (1) and firmly secured by clamp (3) with T-bolt (4) & nut (5) on the preset layout of required APH size. Trial assemblies of CPA made on this octagonal fixture (1) (Refer Figure-B), over which the bottom flanges are laid and the rotor-housing panels bolting holes are marked and drilled with respect to APH center. The Center section (7), corner and center ducts (8) are built over this bottom flanges in stages with the split assemblies (9) at both the ends of each components with unique match marks, which will aid the reassembly at site to form the full assembly of CPA as made in shop. After completion of entire assembly, the top duct flange holes are marked and drilled with respect to APH center (2). That is, fabrication and drilling of both top and bottom flange holes are done taking the APH center (2) as prime reference. In the prior art, the CPA is made as full assembly once at a time, which consists of GAS SIDE and AIR SIDE (PRIMARY AIR SIDE/SECONDARY AIR SIDE) as per the assembly drawing. After confirming all the design/Quality requirements the assembly is dismantled and each component of the assembly is taken up for further manufacturing process. Present practice needs a complete full fixture for the full assembly and larger floor space for higher size APH. In prior art both gas side and air side assemblies were fabricated by two separate groups and progress simultaneously in which, the air side (in case of tri sector) will take extra cycle time, because of assembly complexity. This trial assembly process needs full time crane availability for the fitting of ducts and bracings. Because of the CPA size constraints, this crane facility shall be made available for only one group at a time and this leads to idling of another group. Further if we complete the entire assembly once at a time and dismantle, the components are ready for further manufacturing process and occupy the floor space at once. The present invention of half assembly on dual fixture seeks to overcome some of the major shortcomings of the prior art described above. OBJECTS OF THE INVENTION It: is therefore, an object of the invention to propose a dual fixture which eliminates the disadvantages of prior art. Another object of the invention is to propose a dual fixture which reduces the c/cle time and human resource for an assembly of a connecting plate. A still another object of the invention is to propose a dual fixture for assembling large size connecting plate in available shop floor area. A further object of the invention is to propose a dual fixture which allows more number of fixtures for use with available floor space. SUMMARY OF THE INVENTION Accordingly, there is provided a dual fixture for fabricating and drilling a connecting plate assembly (CPA) of an air preheater (APH). Fixture is needed for the manufacture of the CPA on the shop floor. In the present invention, the dual fixture is adapted to fabricate and drill the air side CPA and gas side CPA separately in two stages. This saves cycle time, manhours and shop floor spaces. The fixture is formed by rolled beams which has a U shaped structure. Rolled beams are put over the leveled fitter's bar which is dimensioned to suit the requirement of the particular size of the CPA. The fixture beams are placed on the grouted and leveled fitter's bars and firmly secured by clamp, T-bolt and nut on the preset layout of required air preheater size. By this invention, it proposes to manufacture air side and gas side of CPA in two stages over the above dual fixture. In the first stage CPA air side is fabricated and bottom flanges for center section and air side is laid over the dual fixture and drilling of housing panel bolting holes is carried out with respect to APH center. Then the center section is mounted with respect to APH center and alignment is ensured. The ducts and bracing for air side alone are then assembled and welded. Next top flange holes are marked and drilled with reference to APH center. After inspecting the quality requirement the assembly is dismantled. In second stage, CPA gas side is fabricated and bottom flanges for gas side is laid over the dual fixture and drilling of housing panel bolting holes are carried out with reference to APH center. Then the center section is rotated by 180 degrees and alignment is ensured. The ducts and bracings for gas side are assembled and welded and then top flange holes are marked and drilled with reference to APH center. Thus the CPA assembly is made in two stages on the same fixture by keeping the same center section and APH center as prime reference. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig.A shows the line diagram of the Octagonal fixture presently in practice. Fig.B shows the line diagram of the connecting plate assembly (CPA) Fabricated over the existing full fixture. Fig.C shows the line diagram of proposed DUAL FIXTURE (C) Fig.D shows the line diagram of the connecting plate assembly (CPA) (D) AIR SIDE (STAGE-I) fabricated in accordance with the invention Fig.E shows the line diagram of the connecting plate assembly (CPA) (E) DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION This present invention describes manufacture of connecting plate assembly (CPA) in which air side and gas side are manufactured in two stages over a dual fixture (C) which can accommodate center section and one side of CPA at a time. This dual fixture (C) is arranged by laying the fixture beams (2) for center section and one side of CPA on the preset layout of required APH size marked on the grouted fitter's bar (1) and firmly secured by clamp (3) with T-bolt (4) & nut (5). By this invention, it proposes to manufacture air side and gas side in two stages over the above dual fixture (6). In stage-I (Refer Fig-D) CPA air side is fabricated and bottom flanges for center section and air side alone is laid over the dual fixture and drilling of housing panel bolting holes is done with respect to APH center (6). Center section (7) is mounted with respect to APH centre (6) and alignment is done. The ducts & bracings (8) for AIR SIDE alone are assembled and welded. Top flange holes are marked and drilled with respect to APH center (6). After confirming all the design/Quality requirements the assembly is dismantled. Then in stage II (Refer Fig-E) CPA (E) gas side is fabricated and bottom flanges for gas side alone is laid over the dual fixture (C) and drilling of housing panel bolting is done with respect to APH center (6). Then the center section (7) is rotated by 180° degrees and alignment is done. The ducts & bracings (8) for GAS SIDE alone are assembled and welded. Top flange holes are marked and drilled with respect to APH center (6). To manufacture the CPA in accordance with the invention, the CPA assembly is made in two stages on the same fixture by keeping the same centre section (7) and the APH centre (6) as prime reference. In the prior art, the CPA was made as a single assembly and a labour-intensive and time-consuming procedure of laying a full fixture, waiting for handling cranes, occupying large floor space etc. This feature of the present invention results in saving of considerable manpower and time, which directly leads to cost saving and cycle time reduction. The fixture in accordance with the invention has the following has the following main advantages over the prior art. 1. Fabrication time for a full mixture is reduced very appreciably for new dual fixture according to the invention. 2. As the fixture is laid for one half the CPA, larger size CPA may be accommodated in available shop floor. 3. The fixture according to the invention eliminates full fixture resulting in material saving. 4. No. of fixtures can be increased with the available floor space. 5. Storage of Fixture beams take up less storage area. 6. The shop-floor area can be made available for some other job, since fixture occupies less space. WE CLAIM 1. A dual fixture (C) for fabrication and drilling of a connecting plate assembly (D and E) of an air pre heater comprises; A plurality of rolled fixture beams (2) joined together to form a fixture (C) of an inverted U shaped structure, said fixture being placed on the preset layout of Air preheater marked on a plurality of grouted and leveled fitter's bars (1) characterized in that said fixture is adapted for fabricating and drilling air side connecting plate assembly (D) and gas side connecting plate assembly (E) of an air preheater in two stages separately. 2. A dual fixture (C) as claimed in claim 1, wherein the fixture (C) is laid for center section (7) and air side connecting plate assembly (D) on the layout of the air preheater marked on a plurality of grouted fitter's bars (1) firmly secured by clamp (3), T-bolt (4) and nut (5) for fabrication of CPA (D) and drilling of housing panel bolting holes with respect to air preheater center (6). 3. A dual fixture as claimed in claim 1, wherein the fixture (C) is adapted for making the alignment of the center section (7) mounted with respect to air preheater center (6) for assembling and welding of a plurality of air side ducts and bracings (8) and for making and drilling top flange holes with respect to air preheater center (6). 4. A dual fixture as claimed in claim 1, wherein the fixture (C) is adapted for a plurality of bottom flanges for gas side connecting plate assembly (E) to lie over the fixture (C) for fabrication of CPA (E) and drilling of housing panel bolting holes with respect to air preheater center (6). 5. A dual fixture as claimed in claim l, wherein said fixture (C) is adapted for a plurality of bottom flanges of gas side to lie over the fixture (C) for drilling of housing panel bolting holes with respect to air preheater center (6). 6. A dual fixture (C) as claimed in claim 1, wherein said fixture is adapted for rotating the center section (7) of gas side connecting plate assembly (E) for 180 degrees, for making the alignment and for assembling and welding of a plurality of ducts and bracings (8) for gas side and for drilling top flange holes with respect to air preheater center (6). A dual fixture (C) for fabrication and drilling of a connecting plate assembly (D and E) of an air preheater consists of rolled fixture beams (2) joined together to form a fixture (C) of an inverted U shaped structure. The dual fixture (C) is adapted by laying the fixture beams (2) for center section and one side of CPA on the layout of required air preheater size marked on the grouted fitter's bars (1) and firmly secured by clamp (3) with T-bolt (4) and nut 5 for fabricating and drilling air side CPA (D) and gas side CPA (E) of an air preheater in two stages separately.

Documents:

1571-KOL-2008-(22-07-2014)-ABSTRACT.pdf

1571-KOL-2008-(22-07-2014)-CLAIMS.pdf

1571-KOL-2008-(22-07-2014)-CORRESPONDENCE.pdf

1571-KOL-2008-(22-07-2014)-DESCRIPTION (COMPLETE).pdf

1571-KOL-2008-(22-07-2014)-DRAWINGS.pdf

1571-KOL-2008-(22-07-2014)-FORM-1.pdf

1571-KOL-2008-(22-07-2014)-FORM-2.pdf

1571-KOL-2008-(22-07-2014)-OTHERS.pdf

1571-kol-2008-abstract.pdf

1571-kol-2008-claims.pdf

1571-kol-2008-correspondence.pdf

1571-kol-2008-description (complete).pdf

1571-kol-2008-drawings.pdf

1571-kol-2008-form 1.pdf

1571-kol-2008-form 18.pdf

1571-kol-2008-form 2.pdf

1571-kol-2008-form 3.pdf

1571-kol-2008-gpa.pdf

1571-kol-2008-specification.pdf