Title of Invention

"WASTE HEAT BOILER."

Abstract

Waste heat boiler, comprising: a multiplicity of heat transfer pipes (3) within a cylindrical jacket (2) and a centrally arranged bypass pipe (4), each of which has an inlet end (5) and an outlet end (6); a device (7) that is attached to the jacket (2) for introducing water (31) to the jacket side of the pipes (3, 4); a device (8) for introducing a hot exhaust gas stream (27) into the inlet end (5) of the pipes (3, 4) and passing the exhaust gas stream (27) through the pipes (3, 4) in an indirect heat exchange with the water (31) at the jacket side of the pipes to produce steam, and to cool the exhaust gas stream (27) that has been introduced; a device (9) for removing the produced water/steam (31) and a device (10) for removing the cooled exhaust gas stream (27); a control device (11) to maintain the waste heat boiler gas exhaust temperature within a particular temperature range, whereby the gas passage velocity and quantity may be controlled in the bypass pipe (4) by an axially displaceable stopper (12) that is arranged at the outlet end (6) of the bypass pipe (4) and that is controlled by a control device (11); characterized in that, the stopper (12) may be cooled by a cooling medium (32) and extends into the outlet end (6) of the bypass pipe (4) and whereat the outlet end (6) is, viewed in the flow direction of the exhaust gas stream (27) cone-shaped expanded and the gas passage cross-section (22) expands uniformly or non-uniformly within the gas passage area (21) that is formed by the mutual overlapping of the inner surface (19) of the outlet end (6) and the outer surface (20) of the stopper (12), and independently of the position of the opened stopper (12), viewed in the flow direction of the exhaust gas stream (27).

Full Text

Specification Waste heat boiler The invention relates to a waste heat boiler that comprises, within a cylindrical jacket, a multiplicity of heat transfer pipes and a centrally arranged bypass pipe, each of which has an inlet end and an outlet end, and that comprises a control device to maintain the waste heat boiler gas exhaust temperature within a certain temperature range. The invention relates, in particular, to a waste heat boiler, the control device of which attaches to the outlet end of the bypass pipe in order to influence the waste heat boiler gas exhaust temperature. Waste heat boilers that are fed on the pipe- and jacket side (channel side) with various gaseous and/or liquid mediums are used in numerous chemical and petrochemical processes. In the process, the hot exhaust gas that develops as a result of a process is fed to the heat transfer pipes, which are arranged as a pipe bundle within the waste heat boiler jacket, as well as to the bypass pipe. While passing through the heat transfer pipes, the hot exhaust gas transfers its heat to the cooling medium, generally water, on the jacket side and is subsequently removed from the waste heat boiler in a cooled state. In order to maintain the waste heat boiler gas exhaust temperature within a certain temperature range, it may be necessary to influence the exhaust temperature with the help of a controlled bypass. This may, for example, be accomplished by using a control damper or a rotating control damper or a control stopper that is arranged at the outlet end of the bypass pipe. Such control devices are known from printed publications DE AS 28 46 455 and EP 0 356 648 A1. Because the exhaust gases in the bypass pipe of the waste heat boiler have a very high temperature and in the large majority of cases flow through at a high velocity, a control element such as a control damper or a control stopper that is arranged at the outlet end of the bypass pipe is subject to high thermal load. The control stoppers currently in use have the disadvantage that exhaust gases that flow out the outlet end of the opened bypass pipe form a powerful plume so that there is a danger of hotspots on the wall of the gas exhaust chamber. One or several of these hotspots cause thermal damage to the wall of the gas exhaust chamber, which in turn leads to undesirably short servicing intervals or to a shorter lifespan of the waste heat boiler. V:\PA\SHG308 A S05-005-0.doc The object of the present invention is to create a control stopper that, on the one hand, is able to withstand the high exhaust gas temperatures, and on the other, to avoid the formation of hot plumes when the exhaust gases exit from the bypass pipe outlet end. The aforementioned object is solved by the totality of the characteristics of patent claim 1. The solution provides that the stopper may be cooled by a cooling medium, and that it extends into the cone-shaped outlet end of the bypass pipe, viewed in the direction of gas flow, and the gas passage cross-section expands uniformly or non-uniformly in the direction of flow of the exhaust gas flow within the gas passage area that is between the inner surface of the outlet end and the outer surface of the stopper and independently of the position of the stopper that is in the opened position. Advantageous embodiments of the invention may be derived from the sub-claims. As a result of the solution, according to the invention, a waste heat boiler is created that has the following advantages: - by avoiding the hot plumes as the exhaust gases exit, the wall of the gas exhaust chamber remains undamaged, and the lifespan of the waste heat boiler is increased. In addition, servicing intervals may be increased; - as a result of the cooling of the stopper, thermal corrosion to the stopper is avoided, and the functionality and lifespan of the control element is significantly improved or increased, as the case may be. Advantageously, the stopper, viewed in the flow direction of the exhaust gas stream, is implemented with a stopper base plate that protrudes radially opposite the center portion of the stopper to deflect the exhaust gas stream in a maximally radial direction. By deflecting the hot exhaust gas stream, it is fed in an approximately orthogonal direction toward the cooled exhaust gas flowing out of the heat transfer pipes and intermingled with it, and potentially present gas plumes are dissipated in the hot exhaust gas stream. In order to achieve reliable deflection of the hot exhaust gas stream of approximately 90°, the external diameter Dt of the stopper base plate must be at least a 1.5 times the external diameter Dk of the stopper head plate. In an advantageous embodiment of the invention, the outer surface of the center portion of the stopper exhibits at least partially a cylindrical area along its length. In connection with the conically expanded outlet end of the bypass pipe, viewed in the direction of the exhaust gas flow, the cylindrical area of the stopper results in a technically, almost maximally advantageous, cross-sectional expansion of the gas passage area, which amounts to a high diffuser effect with a concomitantly large deceleration in gas velocity. Advantageously, the outer surface of the center portion of the stopper exhibits at least partially along its length a conic area, whereby particularly advantageously the taper of this conic area of the center portion of the stopper corresponds to the taper of the cone-shaped outlet end of the bypass pipe. With the quasi-parallel formation of the inner surface of the bypass pipe outlet end and the conic area of the outer surface of the center portion of the stopper, a diffuser effect with deceleration in exhaust gas velocity is achieved by the enlargement of the cross-section of the gas passage in the direction of the gas stream (the radial dimensions of the cross-section of the circular ring increase in the direction of gas flow, and, therefore, also the diameter of the circular ring itself). The diffuser effect and therewith the deceleration in exhaust gas velocity can be increased in that the taper of at least one area of the conic center portion of the stopper deviates in relation to the taper of the cone-shaped outlet end of the bypass pipe, whereby the taper of this area in relation to the taper of the outlet end of the bypass pipe diverges, viewed in the flow direction of the exhaust gas stream. An advantageous embodiment provides that the stopper shaft that is connected with the stopper may be cooled by means of a cooling medium, and that the cooling medium may be fed toward the stopper via the stopper shaft. By this means, it is achieved that the stopper shaft suffers no heat damage, and that the cooling medium is fed toward the stopper in a simple manner in design and structural terms. In the process, the stopper and/or the stopper shaft may be configured so that it cools in one direction such that the cooling medium exits out of the shaft end or the stopper after being fed there through and enters into the exhaust gas stream that is flowing past. This configuration results in a solution that is simple in design and structural terms, whereby the cooling medium that enters the exhaust gas stream further cools the hot exhaust gas stream and is simultaneously removed. In order to avoid overheating and corrosion at the outlet end of the bypass pipe, the conic outlet end of the bypass pipe is advantageously provided with a lining on its interior side. In an advantageous embodiment, the bypass pipe has a larger internal diameter than do the heat transfer pipes in order to bypass a correspondingly high quantity of exhaust gas. An advantageous embodiment of the invention provides that the guiding device that feeds the cooling medium through the stopper and/or the shaft is adapted to the exterior wall of the stopper and/or the stopper shaft such that a gap is created between the exterior wall and the guiding device through which the cooling medium is fed. Embodiments of the invention are explained below on the basis of diagrams and the description. They show: FIG. 1 a longitudinal section through a waste heat boiler; FIG. 2 a longitudinal section through the outlet end of the bypass pipe of a waste heat boiler, the exhaust gas outlet temperature of which is controlled by a stopper arranged at the outlet end of the bypass pipe; FIG. 3 as in FIG. 2, but with an alternate implementation of the stopper; FIG. 4 as in FIG. 2, but with an alternate implementation of the stopper; FIG. 5 as in FIG. 2, but with an alternate implementation of the stopper. FIG. 1 shows a waste heat boiler 1 schematically represented in longitudinal section. Such waste heat boilers 1 are needed for the most varied and chemical and petrochemical processes. The waste heat boiler 1 has an outer jacket 2, which encloses a multiplicity of heat transfer pipes 3, and a centrally arranged bypass pipe 4, whereby pipes 3, 4 are enclosed at their inlet and outlet ends 5, 6 by pipe endplates 28 such that a hollow space for passing the cooling medium 31 for cooling the hot exhaust gas stream 27 is formed between the jacket 2 and the endplates 28. The bypass pipe 4, which preferably has a larger diameter than the heat transfer pipes 3, may be thermally insulated either partially or completely along its length in order to allow hot exhaust gas 27 to flow through the waste heat boiler 1 without dissipating significant heat to the cooling medium 31. Viewed in the direction of the flow of the exhaust gas 27, i.e., parallel to the longitudinal axis of the waste heat boiler 1, a device 8 for introducing the hot exhaust gas stream 27 is provided upstream from the inlet end 5 of pipes 3, 4, and a device 10 for removing the cooled exhaust gas stream 27 is provided downstream from the outlet end 6 of the pipes 3, 4, whereby each of the devices 8, 10 has at least one gas admission and one gas exhaust chamber 29, 30. On the jacket side, the waste heat boiler 1 has devices 7 for introducing a cooling medium 31, preferably water, as well as devices 9 for removing the cooling medium 31, preferably water/steam. Within the area of the jacket, i.e., within the area of the heat transfer pipes 3, there occurs between the exhaust gas 27 which is fed through the heat transfer pipes 3 and the introduced water or cooling medium 31, as the case may be, an indirect heat exchange, whereby the hot exhaust gas 27 dissipates heat to the cooling medium 31. At the outlet end 6 of the bypass pipe 4, an axially adjustable stopper 12 is engaged by a control device 11. The control device 11, which axially adjusts the stoppers 12 by means of a stopper shaft 16 that is connected with the stopper 12, comprises a drive 17 arranged outside the waste heat boiler 1. For the purpose of sealing the gas, the passage of the stopper shaft 16 through the wall of the gas exhaust chamber 30 is sealed with a bushing 18. The stopper 12 at the outlet end 6 of the bypass pipe 4 can be adjusted by means of the control device 11 such that a desired temperature or a desired temperature range of the exhaust gas 27 can be maintained or sustained at the outlet of the waste heat boiler 1. This is always necessary when the heat transfer coefficient is reduced because of dirt on the interior wall of the heat transfer pipes 3, and the exhaust gas temperature increases as a consequence at the outlet. In this case, the bypass pipe 4 and the control stopper 12 that is located at its outlet end 6 engage, and the exhaust gas outlet temperature of the waste heat boiler 1 is influenced by a decrease or increase in the quantity of the exhaust gas stream. Axial displacement of the stopper 12 is associated with a change in gas velocity within the outlet end 6 area and the stopper 12. Because in addition to very high gas exhaust velocities, gas plumes also develop at the outlet end 6 of the bypass pipe 4, which cause hotspots on the walls of the gas exhaust chamber 30, the outlet end 6 of the bypass pipe 4 is formed in an expanding cone shape, viewed in the flow direction of the exhaust gas stream 27. In connection with this measure, the stopper 12 is, according to the invention, implemented to be cooled by a cooling medium 32, and it extends into the cone-shaped expanded outlet end 6 of the bypass pipe 4, whereby the ring-shaped gas passage cross-section 22 that is formed by the inner surface 19 of the outlet end 6 of the bypass pipe 4 and the outer surface 20 of the stopper 12 expands uniformly or non uniformly within the gas passage area 21 viewed in the direction of gas flow. As a result, the expansion of the ring-shaped gas passage cross-section 22 within the gas passage area 21 is independent of the position of the stopper 12, which is in the opened position. The gas passage area 21 that has a gas passage cross-section 22, which, in relation to the bypass pipe 4, extends in an axial direction and the length Ld of which is determined by the position of the stopper 12 within the outlet end 6 of the bypass pipe 4, is defined as the area 21 at which, viewed in the direction of the gas flow, the inner surface 19 of the bypass pipe outlet end 6 and the outer surface 20 of the stopper 12 overlap or intersect, as the case may be. The stopper 12 is arranged such that it must be coaxial to the bypass pipe 4 or its outlet end 6. The conic outlet end 6 of the bypass pipe 4 can, as represented in FIGS. 2 to 5, be implemented with a lining 26 along its internal diameter in order to protect the bypass pipe outlet end 6 from heat corrosion and from erosion. When the bypass pipe 4 is closed (not depicted) the edge of the head plate 13 of the stopper 12 touches the cone of the bypass pipe 4 or its outlet end 6, and in the process the stopper 12 completely closes off the gas passage cross-section 22 of the bypass pipe 4 or its outlet end 6. When the bypass pipe 4 is opened by axially displacing the stopper 12 from the bypass pipe 4 or from its outlet end 6, a gas passage cross-section 22 develops, as is evident in FIG. 5, between the edge of the head plate 13 or the outer surface 20 of the stopper 12, as the case may be, and the cone-shaped inner surface 19 of the outlet end 6 of the bypass pipe 4, through which the hot exhaust gas flows out at a high velocity. The outer surface 20 of the stopper 12 has a conic area 24 at the center portion of the stopper 14, which corresponds to the taper of the cone-shaped outlet end 6 of the bypass pipe 4. Through the conic expansion of the bypass pipe outlet end 6 and the stopper center portion 14, viewed in the direction of gas flow, their radial dimensions increase simultaneously in cross-section, which results in a continuous increase in the gas passage cross-section 22, viewed in the direction of the gas flow. This is synonymous with a diffuser effect -- because of a cross-section that enlarges - in the gas passage area 21 between the bypass pipe outlet end 6 and the stopper 12. This achieves, according to the invention, that the high gas velocity of the exhaust gas 27 that is fed through the gas passage area 21 is reduced and decompressed. In the process, gas plumes that are present are also decompressed and dissipated. FIG. 4 shows a further variant of a stopper 12 implemented according to the invention, the stopper center portion 14 of which is conically implemented. Viewed in the direction of gas flow, the conic area 24 of the upstream stopper center portion 14 here corresponds to the cone of the bypass pipe outlet end 6, and the conic area 25 of the downstream stopper center portion 14 deviates from the cone of the bypass pipe outlet end 6, whereby the taper of the area 25 in relation to the taper of the outlet end 6 of the bypass pipe 4, viewed in the direction of gas flow, runs divergently. In this embodiment, the gas passage cross-section 22 within the gas passage area 21 is non-uniformly expanded because the cross-section 22 expands more strongly in the conic area 25 than in the conic area 24, so that the diffuser action is increased in the conic area 25, and the exhaust gas velocity within the gas passage area 21 can be even more decompressed. Alternatively to the implementation according to FIG. 4, the conic area 25 of the stopper center portion 23 can be arranged upstream in relation to the conic area 24 of the stopper center portion 23. The gas passage cross-sections 22 within the gas passage areas 21 according to FIGS. 2, 3, and 5 have uniform expansions. A further variant of an implemented stopper 12 according to the invention is shown in FIG. 2, in which the stopper center portion 14 has a cylindrical area 23. This variant is characterized by a high diffuser effect within the gas passage area 21, because in the increasing gas passage cross-section 22, viewed in the direction of the gas flow, the gas velocity can be greatly reduced. Any residual gas plumes in the hot exhaust stream that may potentially be present at the outlet of the outlet end 6 of the bypass pipe 4 may be dissipated by deflecting this gas stream by approximately 90° and by largely orthogonal introduction into the cooled exhaust gas stream that exits from the outlet ends 6 of the heat transfer pipes 3. The deflection is accomplished by means of a stopper base plate 15 arranged at the downstream end of the stopper 12, viewed in the direction of gas flow. This accomplishes that the exhaust gas stream that exits between the bypass pipe outlet end 6 and the stopper 12 and is directed toward the base plate 15 is deflected thereby by approximately 90° in a radial direction. By introducing the hot exhaust gas from the bypass pipe 4 into the cooled exhaust gas that exits from the outlet end 6 of the heat transfer pipe 3, intensive mixing of cold and hot exhaust gases occurs, and gas plumes that may potentially be present are dissipated in the process. According to FIGS. 2, 3, and 4, the stopper base plate 15 has an external diameter Dt that is preferably at least 1.5 times the external diameter Dk of the stopper head plate 13. In addition to the stopper 12, the stopper shaft 16 that is connected to the stopper 12 is preferably also cooled by a cooling medium or fluid 32, as the case may be, generally water, whereby the cooling medium 32 fed to the stopper 12 is first directed through the shaft 16 and after flowing through the stopper 12 is again fed out through the shaft 16, as indicated in FIG. 2 by the arrows. By means of a guiding device 33, the cooling medium 32 can, as represented in FIG. 2 for example, be fed centrally, i.e., within the guiding device 33, deflected within the stopper 12, and subsequently removed via the shaft 16 in a concentric ring cross-section that is formed by the guiding device 33 and the external wall of the shaft 16. FIG. 3 shows one-way cooling of stoppers 12 and stopper shaft 16 by a cooling medium 32, whereby one-way means that although the cooling medium 32 is fed to the stopper 12 via the shaft, it is not removed via the shaft 16. Removal is accomplished by exhausting the cooling medium 32, for example at one opening 34 of the head plate 13 of the stopper 12, whereby the cooling medium 32 is introduced into the exhaust gas stream 27 that is flowing past. The guiding device 33 that feeds the cooling medium through the stopper 12 and the shaft 16 can be adapted to the outer surface 20 of the stopper 12 or the external wall of the shaft 16, as the case may be, such that a gap is created between the external wall and the guiding device 33, through which the cooling medium 32, generally water, can flow. Reference numbers: 1 Waste heat boiler 2 Jacket or outer jacket 3 Heat transfer pipe 4 Bypass pipe 5 Inlet end of the pipes 3, 4 6 Outlet end of the pipes 3, 4 7 Device for introducing water 8 Device for introducing a hot exhaust gas stream 9 Device for exhausting water/steam 10 Device for exhausting the cooled exhaust gas stream 11 Control device 12 Stopper 13 Stopper head plate 14 Stopper center portion 15 Stopper base plate 16 Stopper shaft 17 Drive for control device 18 Bushing 19 Inner surface of the outlet end of the bypass pipe 20 Outer surface of the stopper 21 Gas passage area between outlet end of the bypass pipe and the stopper 22 Gas passage cross-section 23 Cylindrical area on the stopper center portion 24 Conical area on the stopper center portion 25 Conical area on the stopper center portion 26 Lining 27 Exhaust gas 28 Pipe endplate 29 Gas admission chamber 30 Gas exhaust chamber 31 Cooling medium in the waste heat boiler 32 Cooling medium in the stopper/shaft 33 Guiding device 34 Opening We claim: 1. Waste heat boiler, comprising: a multiplicity of heat transfer pipes (3) within a cylindrical jacket (2) and a centrally arranged bypass pipe (4), each of which has an inlet end (5) and an outlet end (6); a device (7) that is attached to the jacket (2) for introducing water (31) to the jacket side of the pipes (3,4); a device (8) for introducing a hot exhaust gas stream (27) into the inlet end (5) of the pipes (3, 4) and passing the exhaust gas stream (27) through the pipes (3, 4) in an indirect heat exchange with the water (31) at the jacket side of the pipes to produce steam, and to cool the exhaust gas stream (27) that has been introduced; a device (9) for removing the produced water/steam (31) and a device (10) for removing the cooled exhaust gas stream (27); a control device (11) to maintain the waste heat boiler gas exhaust temperature within a particular temperature range, whereby the gas passage velocity and quantity may be controlled in the bypass pipe (4) by an axially displaceable stopper (12) that is arranged at the outlet end (6) of the bypass pipe (4) and that is controlled by a control device (11); characterized in that, the stopper (12) may be cooled by a cooling medium (32) and extends into the outlet end (6) of the bypass pipe (4) and whereat the outlet end (6) is, viewed in the flow direction of the exhaust gas stream (27) cone-shaped expanded and the gas passage cross-section (22) expands uniformly or non-uniformly within the gas passage area (21) that is formed by the mutual overlapping of the inner surface (19) of the outlet end (6) and the outer surface (20) of the stopper (12), and independently of the position of the opened stopper (12), viewed in the flow direction of the exhaust gas stream (27). 2. Waste heat boiler as claimed in claim 1, wherein said stopper (12), viewed in the flow direction of the exhaust gas stream (27), is implemented at its downstream end with a base plate (15) for deflecting the exhaust gas stream (27) at the stopper (12) in a maximally radial direction. 3. Waste heat boiler as claimed in claim 1, wherein said outer surface (20) of the stopper center portion (14) has at least partially a cylindrical area (23) along its length. 4. Waste heat boiler as claimed in claim 1, wherein said outer surface (20) of the stopper center portion (14) has at least partially a conic area (24, 25) along its length. 5. Waste heat boiler as claimed in claim 4, wherein said taper of the conic area (24) of the stopper center portion (14) corresponds to the taper of the cone-shaped outlet end (6) of the bypass pipe (4). 6. Waste heat boiler as claimed in claim 4, wherein said taper of at least one area (25) of the conic stopper center portion (14) deviates in relation to the taper of the cone-shaped outlet end (6) of the bypass pipe (4), whereby, viewed in the flow direction of the exhaust gas stream (27), the taper of this area (25) in relation to the taper of the outlet end (6) of the bypass pipe (4) diverges. 7. Waste heat boiler as claimed in claim 1, wherein a stopper shaft (16) connected with the stopper (12) may be cooled by a cooling medium (32), and the cooling medium (32) is fed to the stopper (12) via the stopper shaft (16). 8. Waste heat boiler as claimed in claim 1 or 7, wherein said stopper (12) and/or the stopper shaft (16) are implemented only for one-way cooling, and the cooling medium (32) after passing through the shaft (16) and/or the stopper (12) exits therefrom and is introduced into the exhaust gas stream (27). 9. Waste heat boiler as claimed in claim 2, wherein said outer diameter (Dt) of the stopper base plate (15) is at least 1.5 times the outer diameter (Dk) of the stopper head plate (13). 10. Waste heat boiler as claimed in claim 1, wherein said conic outlet end (6) of the bypass pipe (4) is implemented with a lining (26) on its inside. 11. Waste heat boiler as claimed in one of claims 1 to 10, wherein said bypass pipe (4) has a larger internal diameter in relation to the heat transfer pipes (3). 12. Waste heat boiler as claimed in one of claims 1 to 11, wherein a guiding device (33) that feeds the cooling medium (32) through the stopper (12) and/or the shaft (16) is adapted to the outer wall of the stopper (12) and/or the stopper shaft (16) such that a gap is created between the outer wall and the guiding device (33) through which the cooling medium (32) may be fed.

Documents:

2528-del-2006- abstract.pdf

2528-del-2006- claims.pdf

2528-del-2006- description (complete).pdf

2528-del-2006- drawings.pdf

2528-del-2006- form-1.pdf

2528-del-2006- form-18.pdf

2528-del-2006- form-2.pdf

2528-del-2006- form-3.pdf

2528-del-2006- form-5.pdf

2528-del-2006-1-Correspondence Others-(30-09-2013).pdf

2528-del-2006-1-GPA-(30-09-2013).pdf

2528-del-2006-Abstract-(23-04-2014).pdf

2528-DEL-2006-Abstract-(26-06-2012).pdf

2528-del-2006-Claims-(23-04-2014).pdf

2528-DEL-2006-Claims-(26-06-2012).pdf

2528-del-2006-Correspondence Others-(10-05-2013).pdf

2528-del-2006-Correspondence Others-(01-11-2013).pdf

2528-del-2006-Correspondence Others-(14-01-2013).pdf

2528-del-2006-Correspondence Others-(16-01-2014).pdf

2528-del-2006-Correspondence Others-(23-04-2014).pdf

2528-DEL-2006-Correspondence Others-(26-06-2012).pdf

2528-del-2006-Correspondence Others-(30-09-2013).pdf

2528-del-2006-Correspondence-Others-(11-03-2013).pdf

2528-del-2006-correspondence-others.pdf

2528-DEL-2006-Description (Complete)-(26-06-2012).pdf

2528-DEL-2006-Form-1-(26-06-2012).pdf

2528-del-2006-Form-2-(23-04-2014).pdf

2528-DEL-2006-Form-2-(26-06-2012).pdf

2528-DEL-2006-Form-3-(26-06-2012).pdf

2528-DEL-2006-Form-5-(26-06-2012).pdf

2528-DEL-2006-GPA-(26-06-2012).pdf

2528-del-2006-gpa.pdf

2528-del-2006-Petition-137-(23-04-2014).pdf