FIELD OF INVENTION
[001] The present invention disclosure generally relates to blades for waste heat recovery turbine. The invention, in particular, relates to a three-dimensional blades of axial turbine for excess pressure recovery from blast furnace.
BACKGROUND OF THE INVENTION
[002] Generally described, power recovery from waste heat of flue gases through multiple stages of top pressure recovery turbine. Flue gas passes through pressure recovery turbine consists of inlet duct, turbine blade passage and exhaust duct to recover the power. Exhaust duct converts the kinetic energy of the flow of flue gas leaving the last stage into potential energy in the form of increased static pressure.
[003] Apart from inlet and exhaust duct, there are many parameters having impacts on overall turbine performance. Turbine blades are important component, which determines the overall power output and efficiency of the power generation system. Blades for waste heat recovery turbines are generally working in wet environment, hence it is important to reduce the wetness along with various other aerodynamic losses to improve the performance of the turbine. The last stage blade height is an influencing parameter for determining the aerodynamic performance of pressure recovery turbine because, it imposes high centrifugal stresses and more mechanical related difficulties. These blades, has to meet wide range of operating conditions, aero-mechanical loads and strong dynamic forces.
[004] Rotating blades are mounted on a rotor in an axial groove projected outward whereas stationary blades are mounted in the casing within circumferential groove projected inward into the flow path. The inlet guide / stationary and rotating blades are

arranged in alternating rows so that the flow of working fluid guided by previous blade row enters the rotating row of blades at the correct angle. Thus, working fluid properties such as temperature, pressure, velocity and moisture content changes as it expands through the blade path. It converts the thermal energy to mechanical energy and rotates the rotor. Energy conversion through blades determines the turbine efficiency and consequently overall heat rate of the power plant. These blades suffer from corrosion and erosion problems as working environment always consists of dust particles and mist coming from cleaning system of flue gas installed in the downstream of the blast furnace.
[005] These blades are more susceptible to damage due to the increased blade lengths which results in increased stress levels and allowing for a multitude of possible resonance. The centrifugal stress is the mean stress at the operating speed of the turbine, and the alternating stress in the blades is the result of unsteady forces that exist in the turbine. Typically, flow within the blade passage for waste heat recovery turbine suffers from high order of unsteadiness, when operated under off-design conditions which makes the vibration behaviour more difficult and may results into an unstable vibration that occurs predominantly at fundamental frequency mode of blade. This high alternating stresses of the blade, when subjected to severe centrifugal load is responsible for fatigue failures in many cases.
[006] The blade height, mean diameter, operating speed, pitch by chord ratio, gauging angle and stagger angle and aerodynamic conditions are the important factors that affects the blade design in both subsonic and transonic flow conditions. Damping and proper stimulus ratio are the factors which must also be considered in the mechanical design of blade. These mechanical and dynamic behaviour of the blades, as well as others, such as aero-thermodynamic properties or material selection influences the optimum blade design. The inlet guide / stationary and rotating blade

for waste heat recovery application, therefore, requires a precisely defined blade for optimal performance with minimal losses over a wide operating range.
[007] No prior art found for blades of pressure recovery turbine, however few prior art merely discloses for pressure recovery turbine system for blast furnace application and blade configuration and optimization of the pressure recovery turbine is not disclosed. Few pressure recovery turbine system prior arts are listed below.
[008] US4461142A titled “Method of recovery of excess gas energy of blast furnace gas” discusses a method of recovery of furnace gas energy for use to recover excess gas energy from a single or a plurality of furnace gas energy recovering plants each including an expansion turbine mounted in each exhaust system of each blast furnace. In one embodiment, excess gas beyond the power of the respective expansion turbine to recover is removed from each exhaust system of each blast furnace concerned through a branch line, and the removed excess gas is introduced into another expansion turbine through a pressure control valve, to thereby recover the energy possessed by the excess gas. In another embodiment, excess gas is removed through a branch line from each exhaust system of each plant having excess gas beyond the power of the respective expansion turbine to recover mounted in each blast furnace, and the removed excess gas is introduced through a pressure control valve and a flow distribution valve into at least one plant having reserve in the furnace gas energy recovering capacity to thereby recover the energy possessed by the excess gas. However, said patent utilizes pressure control to control the top pressure of blast furnace.
[009] US4184323A titled “Method and apparatus for recovering energy possessed by exhaust gas from blast furnace by turbine”. Herein exhaust gas is supplied to a septum valve and then into a turbine to recover the energy. Method of controlling top

pressure of the blast furnace through the septum valve and the governor valve is described.
[0010] WO2011026940A1 titled “Recovery of energy from blast furnace gas in an expansion turbine” discussed about a TRT process and system for recovering energy from blast furnace top gas in an expansion turbine are disclosed. The over-pressurized blast furnace top gas stream released by a blast furnace is subsequently passed through a top gas cleaning plant, a preheating unit and an expansion turbine coupled to a load. The top gas stream is warmed-up in a heat-exchanger located in-between the top gas cleaning plant and the pre-heating unit. The top gas flow, after expansion in the turbine, is fed through the heat-giving side of the heat-exchanger. Herein gas stream of blast furnace is passed through a top gas cleaning plant, a preheating unit and an expansion turbine coupled to a load. The top gas stream is warmed-up in a heat-exchanger located in-between the top gas cleaning plant and the pre-heating unit. The top gas flow, after expansion in the turbine, is fed through the heat-giving side of the heat-exchanger is described.
[0011] US7175393B2 titled “Transonic blade profiles” discusses about aerodynamic design of moving blades, pertaining to later stages of axial steam turbines where the inlet flow is non-uniform over the blade height. The claim made herein is a set of six invented transonic blade profiles which can be used to develop various type of 3D twisted blades for axial steam turbine. The aerodynamic characteristics of these 6 base profiles are evaluated herein as a function of stagger angle and pitch/chord ratios. Herein a set of six transonic blade profiles for axial steam turbine as reported for conventional low-pressure turbine application is described.
[0012] The flow in the waste heat recovery turbine is extremely complex due to presence of near transonic flow, interaction of rotating and non-rotating blades with

upstream wakes, boundary layer and shock interaction, development of secondary vortices and inherently unsteady flow.
[0013] The present invention is directed to overcoming one or more problems set forth above and/or other problems associated with known waste heat recovery turbine. The present invention relates to a top pressure recovery turbine’s inlet duct, inlet guide blade, stationary blade, rotating blade and exhaust duct.
OBJECTS OF THE INVENTION
[0014] It is therefore a principal object of the present invention is to provide a top pressure recovery turbine for waste heat recovery application.
[0015] Another object of the present invention is to provide top pressure recovery turbine’s inlet duct, exhaust duct, inlet guide blade, stationary blade, and rotating blades.
[0016] Another object of the present invention is to provide an inlet guide blade which comprises of a set of curve profile with suction curve, pressure curve, leading edge curve and trailing edge curve which is used to develop various types of 3D (three dimensional) blades for axial turbine for waste heat recovery turbine.
[0017] Another object of the present invention is to propose a rotating blade having the set of curve profile with suction curve, pressure curve, leading edge curve and trailing edge curve which is used to develop various types of 3D (three dimensional) blades for axial turbine for waste heat recovery turbine.
[0018] Yet another object of the present invention is to propose a stationary blade having the set of curve profile with suction curve, pressure curve, leading edge curve

and trailing edge curve which is used to develop various types of 3D (three dimensional) blades for axial turbine for waste heat recovery turbine.
[0019] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
SUMMARY OF THE INVENTION
[0020] This summary is provided to introduce concepts related to a pressure recovery turbine. The pressure recovery turbine comprises an inlet duct stationed upstream of a turbine and an exhaust duct positioned downstream of turbine.
[0021] The present disclosure relates to a pressure recovery turbine. The turbine having an inlet duct, an exhaust duct and one or more rows with each row having at least one inlet guide blade, at least one stationary blade, at least one rotating blades. Each of the blades comprises a set of curve profile with a suction curve, a pressure curve, a leading edge curve and a trailing edge curve. The blade shape is determined by smooth surface passing through a curve profile at radial location “H” defined by the suction curve, the pressure curve, the leading edge curve and the trailing edge curve based on the calculated values. The each row of the at least one inlet guide blade, the at least one stationary blade, and the at least one rotating blades defines a pitch by chord, a stagger angle and a gauging angle.
[0022] In an aspect, the curve profile at “H” distances are joined smoothly with one another to form a complete stationary or rotating blade of the waste heat recovery

turbine. The at least one inlet guide blade, the at least one stationary blade and the at least one rotating blades arranged alternatively in a turbine rotor and casing.
[0023] In an aspect, the at least one stationary blade and the at least one rotating blades are improved from structural and aerodynamics for waste heat recovery application by asserting various properties of the at least one stationary blade and the at least one rotating blades profile such as the maximum & minimum moments of inertia, the area at each section, the twist, torsional stiffness, shear centre and axial & tangential chord.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0024] 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, 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 or structure 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:
[0025] FIG. 1 is a schematic illustration of meridional view of top pressure recovery turbine in an embodiment of the present invention;
[0026] FIG. 2 is a schematic illustration of blade profile for waste heat recovery turbine in an embodiment of the present invention;

[0027] FIG. 3 is a schematic illustration of three-dimensional rotating blade in an embodiment of the present invention;
[0028] FIG. 4 is a schematic illustration of three-dimensional inlet guide/stationary blade geometry in an embodiment of the present invention;
[0029] FIG. 5 is a graph showing Mach number distribution across inlet guide/stationary blade channel at hub section in an embodiment of the present invention;
[0030] FIG. 6 is a graph showing Mach number distribution across inlet guide/stationary blade channel at tip section in an embodiment of the present invention;
[0031] FIG. 7 is a graph showing Mach number distribution across rotating blade channel at hub section in an embodiment of the present invention;
[0032] FIG. 8 is a graph showing Mach number distribution across rotating blade channel at tip section in an embodiment of the present invention;
[0033] FIG. 9 is a graph showing the relation between local lean and profile offset for rotating blade in an embodiment of the present invention;
[0034] FIG. 10 is an illustration of an exemplary campbell diagram for rotating blade 2 in an embodiment of the present invention, and
[0035] FIG. 11 is an illustration of an exemplary campbell diagram for rotating blade 4 in an embodiment of the present invention.

[0036] 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.
DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
[0037] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[0038] The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, system, assembly that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
[0039] The present invention relates to a top pressure recovery turbine for waste heat recovery application. In a preferred embodiment the top pressure recovery turbine comprises a turbine (10) having an inlet duct (I), an exhaust duct (E) and one or more

rows with each row having at least one inlet guide blade (1), at least one stationary blade (3), at least one rotating blades (2, 4). Each of the blades (1,2,3, 4) comprises a set of curve profile with a suction curve, a pressure curve, a leading edge curve and a trailing edge curve. In a preferred embodiment wide range of pressure drop across turbine (10) in the order of 9.0 to 2.4 bar ensure the good off-design performance.
[0040] FIG. 1 is a schematic illustration of meridional view of top pressure recovery turbine in an embodiment of the present invention. In a preferred embodiment the 1st stage guiding blade (A), the 1st stage moving blade (B), 2nd stage guiding blade (C), the 2nd stage moving blade (D), the exhaust duct (E), 1st stage moving blade root (F), 1st stage guide blade spindle (H), 2nd stage guide blade spindle (J), 2nd stage moving blade root (G), and the inlet duct (I) are circumferentially arranged. In one embodiment a stage consists of group of the one or more rows with each row having the at least one inlet guide blade (1), the at least one stationary blade (3), and the at least one rotating blades (2, 4) (as shown in FIG. 1).
[0041] Referring to FIG.1, the inlet duct (I), the exhaust duct (E), the at least one rotating blades (2, 4) are circumferentially mounted in dovetail groove and the at least one stationary blade (3) are mounted in the casing through spindle (8) arranged in alternative rows. The at least one rotating blades (2, 4) are mounted in the rotor axial groove which are mechanically coupled at the axial root (7) and axially positioned between adjacent blade rows. The at least one stationary blade (3) are mounted in the casing holes via. Spindles (8) (as shown in FIG.4). The spindles (8) is used to rotate the each of the blades (1, 2, 3, 4) within each row with a pre-determined value derived from the flow requirement. The passage between at least one stationary blade (3) row and the at least one rotating blades (2, 4) row defines the portion of flow path.
[0042] FIG. 2 is a schematic illustration of blade profile for waste heat recovery turbine in an embodiment of the present invention. The curve profile section is defined

as the cross section view of the blade (1, 2, 3, 4) as shown in FIG. 2. The each row of the at least one inlet guide blade (1), the at least one stationary blade (3), and the at least one rotating blades (2, 4) defines the pitch by chord, the stagger angle and a gauging angle. In a preferred embodiment the pitch by chord, the stagger angle and the gauging angle of the blade rows (shown in Fig. 2) are defined by Table 5. In one embodiment the shape of blade determines the aerodynamic characteristics of the blade (1, 2, 3, 4). Aerodynamic characteristics such as degree of reaction on the hub side is greater than about 23 % to maintain reasonable loading about the hub. Degree of reaction is defined as the heat drop across rotating blade row to the heat drop across the stage.
[0043] FIG. 3 is a schematic illustration of three-dimensional rotating blade in an embodiment of the present invention. In one embodiment FIG. 3 shows the prospective view of the at least one rotating blades (2, 4) which is used with top pressure recovery turbine. The at least one rotating blades (2, 4) includes a leading edge (11) and a trailing edge (12). The steam flows from the leading edge (11) to the trailing edge (12), which also includes a first concave surface (13) and a second convex surface (14). The first concave surface (13) and the second convex surface (14) are connected axially at the trailing edge (12), and the leading edge (11) and extend radially between a rotor blade root platform (6) and a rotor blade tip (5). The at least one rotating blades (2, 4) is connected to the rotor via. axial root (7). In a preferred embodiment a blade chord distance “L” is a distance measured from the leading edge (11) to trailing edge (12) at any point along a radial length “H” of the at least one rotating blades (2, 4).
[0044] FIG. 4 is a schematic illustration of three-dimensional inlet guide/stationary blade geometry in an embodiment of the present invention. In a preferred embodiment FIG. 4 shows the prospective view of at least one inlet guide blade (1), at least one stationary blade (3), which is used with top pressure recovery turbine for waste heat recovery application. The at least one inlet guide blade (1), at least one stationary blade

(3) includes a leading edge (11) and a trailing edge (12). The steam flows from the leading edge (11) to the trailing edge (12), which also includes a first concave surface (13) and a second convex surface (14). The first concave surface (13) and the second convex surface (14) are connected axially at the trailing edge (12) and the leading edge (11), and extend radially between the at least one inlet guide blade (1) / at least one stationary blade (3) spindle inner surface (17) and the at least one inlet guide blade (1) / at least one stationary blade (3) tip profile (16). In a preferred embodiment the at least one stationary blade (3) is mechanically coupled to the casing with the spindle (8). In one embodiment the blade chord distance “L” is a distance measured from the leading edge (11) to a trailing edge (12A) at any point along a radial length “H” of at least one rotating blades (2, 4).
[0045] In the exemplary embodiment, the approximate leading-edge height of the at least one rotating blades (2,4) of FIG. 1 is 228 & 301 mm respectively and approximate trailing edge height is 236 & 319 mm respectively. In a preferred embodiment the leading-edge height is 228 & 301mm respectively and trailing edge height is 236 & 319 mm respectively. In one embodiment any suitable length depending on the desired application is preferred accordingly. In the exemplary embodiment as shown in FIG.1, the dovetail root (F) & (G) is a straight entry which engages with the rotor via an axial entry groove.
[0046] In the exemplary embodiment, the approximate leading-edge height of at least one inlet guide blade (1) and the at least one stationary blade (3) (FIG. 1) is 221.8 & 249.6 mm respectively and approximate trailing edge height is 222.5 & 282.3 mm respectively. The leading-edge height is 221.8 & 249.6 mm respectively and trailing edge height is 222.5 & 282.3 mm respectively. In one embodiment any suitable length depending on the desired application is preferred. In the exemplary embodiment, the spindle (8) as shown in (FIG. 4) engages with the turbine casing via a radial entry hole.

[0047] In one embodiment all the curve profile sections are optimised for profile and secondary losses. Smooth pressure, Mach number distribution and channel width are maintained for all the curve profile with the suction curve, the pressure curve, the leading edge curve and the trailing edge curve. Stresses for the at least one rotating blades (2, 4) are under the acceptable limit.
[0048] In a preferred embodiment nine optimized curve profile sections for the at least one inlet guide blade (1), at least one stationary blade (3), at least one rotating blades (2, 4) is represented by Table1 to Table 4 respectively. The actual at least one rotating blades (2, 4) at root section includes the smooth fillet which connects the blade with root.
[0049] In an embodiment the suction surface, leading surface, pressure surface and trailing surface of the at least one inlet guide blade (1) are determined by curve set forth by Table 1, by smoothly joining curve section from 1 to 9 along the radial length H (as shown in FIG. 4).
[0050] In an embodiment the suction surface, leading surface, pressure surface and trailing surface of the at least one rotating blade (2) are determined by curve set forth by Table 2, by smoothly joining curve section from 1 to 9 along the radial length H (as shown in FIG. 3).
[0051] In a preferred embodiment the suction surface, leading surface, pressure surface and trailing surface of the at least one stationary blade (3) are determined by curve set forth by Table 3, by smoothly joining curve section from 1 to 9 along the radial length H as shown in FIG. 4.
[0052] In a preferred embodiment the suction surface, leading surface, pressure surface and trailing surface of the at least one rotating blade (4) are determined by

curve set forth by Table 4, by smoothly joining curve section from 1 to 9 along the radial length H (as shown in FIG. 3).

Table 4 contd..(Rotating Blade 4)
SECTION 1 SECTION 2 SECTION 3 SECTION 4 SECTION 5 SECTION 6 SECTION 7 SECTION 8 SECTION 9
Section Ht =0 Section Ht =36.111 Section Ht =72.222 Section Ht =108.333 Section Ht =144.444 Section Ht =180.555 Section Ht =216.667 Section Ht =252.778 Section Ht =288.889
Pressure Side Pressure Side Pressure Side Pressure Side Pressure Side Pressure Side Pressure Side Pressure Side Pressure Side
U A U A U A U A U A U A U A U A U A
1 -5.138 74.5775 1.6143 73.6305 6.557 71.2541 12.6467 69.1697 19.1645 66.3613 25.9958 63.0181 32.9814 59.0711 39.5843 53.7859 46.5085 47.9732
2 -4.127 68.5593 1.5563 67.5796 5.6356 65.3071 10.7776 63.4979 16.354 61.1371 22.1883 58.4995 28.3995 55.3578 34.2612 51.2419 40.7223 46.6746
3 -3.3617 62.505 1.3476 61.5321 4.7877 59.3491 9.1268 57.7579 13.8452 55.7602 18.8305 53.6342 24.3769 51.0376 29.4927 47.755 35.3615 44.1165
4 -2.8329 56.4254 0.9823 55.492 3.8646 53.4023 7.4925 52.0132 11.429 50.3406 15.6746 48.6343 20.6282 46.4746 25.0916 43.8083 30.3738 40.8797
5 -2.535 50.3301 0.4554 49.4639 2.8019 47.479 5.7452 46.3019 8.9593 44.9453 12.525 43.6303 16.8812 41.91 20.8198 39.7209 25.5849 37.3529
6 -2.4649 44.2279 -0.2374 43.4526 1.5804 41.5863 3.8615 40.6342 6.3971 39.5933 9.3431 38.6468 13.1171 37.3595 16.6034 35.5763 20.9062 33.6808
7 -2.6219 38.1273 -1.0997 37.4632 0.1927 35.7307 1.8472 35.0115 3.7497 34.283 6.1225 33.6883 9.351 32.8107 12.4199 31.3984 16.2981 29.9204
8 -3.0063 32.0369 -2.1348 31.5014 -1.3629 29.9173 -0.299 29.4379 1.0131 29.0181 2.8533 28.7617 5.5631 28.28 8.2437 27.2132 11.7296 26.112
9 -3.6186 25.9651 -3.3454 25.5726 -3.0866 24.1516 -2.5809 23.9184 -1.8199 23.8044 -0.4749 23.8747 1.744 23.7755 4.0563 23.0393 7.1763 22.2852
10 -4.4592 19.9207 -4.7341 19.6831 -4.9791 18.4391 -5.0019 18.4585 -4.7545 18.6472 -3.8703 19.0342 -2.1127 19.3033 -0.1545 18.889 2.6206 18.4614
11 -5.5275 13.9124 -6.3033 13.839 -7.0417 12.7857 -7.5644 13.0636 -7.7942 13.5513 -7.3382 14.2454 -6.0129 14.8689 -4.3963 14.7703 -1.9499 14.6552
12 -6.8223 7.9487 -8.0552 8.0471 -9.2758 7.1979 -10.2697 7.739 -10.9414 8.5211 -10.8824 9.5128 -9.9611 10.4772 -8.6741 10.6891 -6.5432 10.8768
13 -8.3414 2.0383 -9.9918 2.3144 -11.6825 1.6823 -13.1182 2.4894 -14.1975 3.5606 -14.5057 4.8405 -13.9608 6.1324 -12.9916 6.6499 -11.1646 7.1325
14 -10.0825 -3.8107 -12.1149 -3.352 -14.2625 -3.7544 -16.1091 -2.6803 -17.5631 -1.3261 -18.2107 0.2327 -18.015 1.8384 -17.3517 2.6568 -15.8173 3.4273
15 -12.0426 -9.5899 -14.4255 -8.9445 -17.0153 -9.1057 -19.2417 -7.7653 -21.0388 -6.1352 -21.9993 -4.3066 -22.1264 -2.4009 -21.7566 -1.2869 -20.5039 -0.2348
16 -14.2186 -15.2913 -16.9246 -14.4553 -19.9397 -14.3651 -22.5152 -12.7608 -24.6246 -10.8628 -25.8725 -8.7739 -26.297 -6.5819 -26.2081 -5.1779 -25.2266 -3.8503
17 -16.6072 -20.907 -19.6125 -19.8765 -23.0334 -19.5268 -25.9289 -17.6616 -28.3203 -15.5049 -29.8313 -13.1656 -30.5285 -10.7013 -30.7073 -9.0137 -29.9868 -7.4163
18 -19.2048 -26.4291 -22.4887 -25.2002 -26.2938 -24.5849 -29.4813 -22.4628 -32.1253 -20.0579 -33.876 -17.4782 -34.8225 -14.7555 -35.255 -12.7918 -34.7855 -10.9303
19 -22.0081 -31.8497 -25.5523 -30.4184 -29.7175 -29.5339 -33.1701 -27.16 -36.0388 -24.518 -38.0068 -21.7084 -39.18 -18.7414 -39.8517 -16.5101 -39.6234 -14.3902
20 -25.0137 -37.1608 -28.8016 -35.5229 -33.3012 -34.3682 -36.9917 -31.7498 -40.0597 -28.8815 -42.2236 -25.853 -43.6018 -22.6557 -44.4977 -20.1667 -44.5004 -17.7947
21 -28.2181 -42.3544 -32.2343 -40.5059 -37.0412 -39.0827 -40.9423 -36.2291 -44.1864 -33.145 -46.5256 -29.909 -48.0885 -26.4955 -49.1932 -23.7595 -49.4163 -21.1427
22 -31.6183 -47.4219 -35.8473 -45.3598 -40.9336 -43.6722 -45.0182 -40.5946 -48.4172 -37.3053 -50.9121 -33.8735 -52.6404 -30.2578 -53.9381 -27.2867 -54.3706 -24.4337
23 -35.2107 -52.355 -39.6366 -50.0774 -44.9741 -48.1318 -49.2167 -44.8424 -52.7498 -41.3594 -55.3821 -37.7435 -57.2575 -33.9398 -58.7324 -30.7466 -59.3622 -27.6678
24 -38.9913 -57.1455 -43.5972 -54.652 -49.1574 -52.4578 -53.5349 -48.9683 -57.1818 -45.3047 -59.9341 -41.5168 -61.9396 -37.5387 -63.5757 -34.1374 -64.39 -30.8455
25 -42.9544 -61.786 -47.7225 -59.0788 -53.477 -56.6477 -57.9688 -52.9698 -61.71 -49.1392 -64.5664 -45.1911 -66.6863 -41.0521 -68.4676 -37.4578 -69.4525 -33.9675
26 -47.0923 -66.2715 -52.0038 -63.3548 -57.9252 -60.7009 -62.5119 -56.8468 -66.3307 -52.8615 -69.2775 -48.7637 -71.4967 -44.4776 -73.4074 -40.7065 -74.5483 -37.0348
27 -51.396 -70.5981 -56.4318 -67.4789 -62.493 -64.6187 -67.1564 -60.6019 -71.0401 -56.4712 -74.0651 -52.2331 -76.3702 -47.8129 -78.3941 -43.8827 -79.6762 -40.0481
28 -55.8578 -74.7615 -60.9982 -71.4491 -67.1725 -68.4025 -71.8958 -64.2364 -75.8338 -59.9681 -78.9252 -55.6003 -81.3049 -51.0568 -83.427 -46.9852 -84.8353 -43.0078
29 -60.4746 -78.7523 -65.6983 -75.26 -71.9597 -72.0491 -76.728 -67.7465 -80.708 -63.3519 -83.8554 -58.864 -86.2993 -54.208 -88.5054 -50.0125 -90.025 -45.9134
30 -65.2484 -82.5537 -70.5318 -78.9003 -76.8564 -75.5471 -81.6565 -71.12 -85.6648 -66.6134 -88.8572 -62.0167 -91.3537 -57.2621 -93.6297 -52.9617 -95.2454 -48.7635
31 -70.1843 -86.142 -75.5021 -82.3513 -81.8687 -78.8774 -86.6887 -74.3366 -90.7176 -69.7238 -93.9341 -65.0472 -96.4688 -60.2135 -98.801 -55.8276 -100.497 -51.5552
Trailing Edge Trailing Edge Trailing Edge Trailing Edge Trailing Edge Trailing Edge Trailing Edge Trailing Edge Trailing Edge
1 -70.1843 -86.142 -75.5021 -82.3513 -81.8687 -78.8774 -86.6887 -74.3366 -90.7176 -69.7238 -93.9341 -65.0472 -96.4688 -60.2135 -98.801 -55.8276 -100.497 -51.5552
2 -70.6706 -86.7895 -75.9854 -82.9689 -82.3427 -79.4638 -87.1518 -74.8921 -91.1701 -70.2495 -94.3747 -65.5441 -96.8972 -60.6826 -99.2163 -56.2693 -100.899 -51.9702
3 -70.7037 -87.5995 -76.0303 -83.7525 -82.3987 -80.2166 -87.2188 -75.6133 -91.2469 -70.94 -94.4601 -66.204 -96.9896 -61.3126 -99.3144 -56.869 -101.004 -52.54
4 -70.2784 -88.29 -75.6249 -84.4252 -82.0227 -80.8717 -86.874 -76.2507 -90.9292 -71.5582 -94.1692 -66.8028 -96.7228 -61.8909 -99.0697 -57.4254 -100.786 -53.0765
5 -69.5429 -88.6325 -74.9154 -84.7633 -81.3486 -81.2138 -86.2369 -76.5969 -90.3256 -71.9035 -93.5994 -67.1473 -96.1848 -62.2319 -98.5623 -57.7602 -100.311 -53.4092
6 -68.7416 -88.5115 -74.1371 -84.6586 -80.5982 -81.1314 -85.5156 -76.536 -89.6328 -71.8597 -92.9355 -67.1199 -95.5493 -62.2187 -97.9558 -57.7588 -99.7336 -53.4219

Table 5
Pitch by Chord Stagger Angle (deg) Gauging Angle (deg)
Inlet guide blade 1 0.65 to 0.676 39.5 to 43.3 24.33 to 28.56
Rotating blade 2 0.59 to 0.85 22.58 to 56 23.0 to 32.267
Stationary blade 3 0.56 to 0.6 38.6 to 43.5 24.6 to 29.84
Rotating blade 4 0.53 to 0.86 21.8 to 58.44 22.76 to 31.64
[0053] FIG. 5 is a graph showing Mach number distribution across the at least one inlet guide blade (1), the at least one stationary blade (3) of channel at hub section in an embodiment of the present invention. In a preferred embodiment the two dimensional and three-dimensional aero foils are analysed for aerodynamic performance using streamline curvature code and computational fluid dynamics (CFD). The aerodynamic performance parameters such as profile loss, profile loss coefficient, flow deflection, surface Mach number distribution are evaluated during 2D cascade analysis. In one embodiment FIG. 5 shows the optimized Mach number distribution for the at least one inlet guide blade (1), the at least one stationary blade (3) (FIG. 1) for the hub section. Maximum loading is maintained near 55-65 % of the normalized chord length.
[0054] FIG. 6 is a graph showing Mach number distribution across the at least one inlet guide blade (1), the at least one stationary blade (3) channel at tip section in an embodiment of the present invention. In a preferred embodiment the two dimensional and three-dimensional aero foils are analysed for aerodynamic performance using streamline curvature code and computational fluid dynamics (CFD). The aerodynamic performance parameters such as profile loss, profile loss coefficient, flow deflection, surface Mach number distribution are evaluated during 2D cascade analysis. In one embodiment FIG. 6 shows the optimized Mach number distribution for the at least

one inlet guide blade (1), the at least one stationary blade (3) (Fig. 1) for the tip section. Maximum loading is maintained near 55-65 % of the normalized chord length.
[0055] FIG. 7 is a graph showing Mach number distribution across the at least one rotating blade (2) channel at hub section in an embodiment of the present invention. In a preferred embodiment the two dimensional and three-dimensional aero foils are analysed for aerodynamic performance using streamline curvature code and computational fluid dynamics (CFD). The aerodynamic performance parameters such as profile loss, profile loss coefficient, flow deflection, surface Mach number distribution are evaluated during 2D cascade analysis. In one embodiment FIG. 7 shows the optimized Mach number distribution for the at least one rotating blade (2) for the hub section.
[0056] FIG. 8 is a graph showing Mach number distribution across the at least one rotating blade (4) channel at tip section in an embodiment of the present invention. In a preferred embodiment the two dimensional and three-dimensional aero foils are analysed for aerodynamic performance using streamline curvature code and computational fluid dynamics (CFD). The aerodynamic performance parameters such as profile loss, profile loss coefficient, flow deflection, surface Mach number distribution are evaluated during 2D cascade analysis. In one embodiment FIG. 8 shows the optimized Mach number distribution for the at least one rotating blade (4) for the tip section.
[0057] FIG. 9 is a graph showing he relation between local lean and profile offset for rotating blade in an embodiment of the present invention. In a preferred embodiment FIG. 9 shows the applied local lean for the at least one rotating blade (2, 4), which eliminates secondary losses in the hub area and also decreases the pressure gradient in radial direction. Local lean is the local angle made by the line passing through centre of gravity of two adjacent profile with the radial line passing through the centre of

gravity of the hub profile and angle placement of profiles centre of gravity in radial direction. The local lean, with an additional “U” and “A” shift in centre of gravity of profile located from section 2 to section 9 with respect to profile located at section 1 is provided to take static and dynamic stress induced during the operation. The local lean and shift in profile centre of gravity defines the 3D shape of the blade.
[0058] FIG. 10 is an illustration of an exemplary campbell diagram for rotating blade (2) in an embodiment of the present invention. In a preferred embodiment the strength and vibration characteristics of the at least one rotating blade (2) for the top pressure recovery turbine is analysed and the at least one rotating blade (2) is used in wide range of operational requirements. The blades (1, 2, 3, 4) are thicker than the blades of the steam turbine. Thicker blade shifts the natural frequency of the blade to higher side, which is ensured through vibration analysis and dynamic stress evaluation. The dynamic stresses of the at least one rotating blade (2) is characterized by the Campbell diagram as shown in FIG. 10.
[0059] FIG. 11 is an illustration of an exemplary campbell diagram for rotating blade (4) in an embodiment of the present invention. In a preferred embodiment after the blade (1, 2, 3, 4) is manufactured, the vibration characteristics are fixed. Profile chord is fixed properly to ensure structural integrity during operation. The at least one rotating blade (2, 4) for top pressure recovery staged having optimized chord for wide range of operation. To maintain the intended performance of blade, shape of blade is modified and subjected to determine the modified behaviour through computer analysis. The analysis determines the optimum amount of mass required to achieve level of dynamic stresses. Modifying the blade (1, 2, 3, 4) by removing the mass increases the natural frequency of blade (1, 2, 3, 4) and adding mass increases the natural frequency of blade (1, 2, 3, 4). Change in profile shape alter the dynamic response of the blade (1, 2, 3, 4). The dynamic stresses of the at least one rotating blade (4) is characterized by the Campbell diagram as shown in FIG. 11.

[0060] In one embodiment re-stagger angle of the at least one inlet guide blade (1) varies from -20 to 15 deg. and re-stagger angle of the at least one stationary blade (3) varies from -15 to 10 deg from a base stagger angle. In an exemplary embodiment the turbine (10) is configured to result in a pressure ratio in the range of 9 to 2.4 bar. The turbine (10) is configured to have hub reaction of equal or greater than 23 %.
[0061] In an exemplary embodiment the each row having the at least one inlet guide blade (1) is circumferentially spaced about the axis of the turbine wheel and gauging of the at least one inlet guide blade (1) decreases from hub side to tip side in the range of 28.56 to 24.33, the stagger angle of the at least one inlet guide blade (1) increases from the hub side to the tip side in the range of 39.5 to 43.3 and the pitch by chord of the at least one inlet guide blade (1) decreases from the hub side to the tip side in the range of 0.676 to 0.65.
[0062] In one embodiment the each row having the at least one rotating blade (2) circumferentially spaced about the axis of a turbine wheel, gauging of the at least one rotating blade (2) decreases from the hub side to the tip side in the range of 32.267 to 23.0, stagger angle of the at least one rotating blade (2) increases from the hub side to the tip side in the range of 22.58 to 56.0 and the pitch by chord of the at least one rotating blade (2) increases from the hub side to the tip side in the range of 0.59 to 0.85.
[0063] In an exemplary embodiment the each row having the at least one stationary blade (3) circumferentially spaced about the axis of the turbine wheel, gauging of the at least one stationary blade (3) decreases from the hub side to the tip side in the range of 29.84 to 24.6, the stagger angle of the at least one stationary blade (3) increases from the hub side to the tip side in the range of 38.6 to 43.5 and pitch by chord of the

at least one stationary blade (3) decreases from the hub side to the tip side in the range of 0.6 to 0.56.
[0064] In one embodiment the each row having the at least one rotating blade (4) circumferentially spaced about the axis of a turbine wheel, gauging of the at least one rotating blade (4) decreases from the hub side to the tip side in the range of 31.64 to 22.76, stagger angle of the at least one rotating blade (4) increases from the hub side to the tip side in the range of 21.8 to 58.44 and the pitch by chord of the at least one rotating blade (4) increases from the hub side to the tip side in the range of 0.86 to 0.53.
[0065] In one embodiment each of the blades (1, 2, 3, 4) having the set of curve profile section with the suction curve, the pressure curve, the leading edge curve and the trailing edge curve set forth by Table 1, Table 2, Table 3, and Table 4, which is used to develop various types of 3D (three dimensional) blades for axial turbine used for waste heat recovery turbine. The subsonic and transonic is defined as the blade profile exit, Mach number in the range of 0.6 - 0.93 and 0.94 - 1.10 respectively.
[0066] In one embodiment the blades (1, 2, 3, 4) are three-dimensional blades of axial turbine for excess pressure recovery from blast furnace where pressure energy is converted into mechanical energy with optimum efficiency suitable for subsonic and transonic flows. Each of the blades (1, 2, 3, 4) withstand the dynamic stresses caused by the rotation of blades and pressure fluctuations. Each of the blades (1, 2, 3, 4) are capable of meeting mechanical strength requirements arising out of energy conversion of low enthalpy working medium. The blades (1, 2, 3, 4) are efficient and adequate to withstand the dynamic stresses arising due to operating pressure change. Various properties of the at least one stationary blade (3) and the at least one rotating blades (2,4) profile such as the maximum & minimum moments of inertia, the area at each

section, the twist, torsional stiffness, shear centre and axial & tangential chord are optimized.
[0067] 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. 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.
[0068] 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. The present invention will now be described more specifically with reference to the following specification.
[0069] 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.
[0070] Although embodiments for the present subject matter have been described in language specific to package 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/device 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.
[0071] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,”

etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to

contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0072] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0073] 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.

WE CLAIM:
1. A top pressure recovery turbine for waste heat recovery comprising:
a turbine (10), having an inlet duct (I), an exhaust duct (E) and one or more rows with each row having at least one inlet guide blade (1), at least one stationary blade (3), at least one rotating blades (2, 4), wherein each of the blades (1, 2, 3, 4) comprises a set of curve profile with a suction curve, a pressure curve, a leading edge curve and a trailing edge curve, wherein
the at least one stationary blade (3) is mounted in a casing through a spindle (8) arranged in alternative rows and the spindle (8) rotates the one or more stationary blade (3) with a pre-determined value, wherein the at least one rotating blade (2, 4) is circumferentially mounted in a dovetail groove having a leading edge (11) and a trailing edge (12), wherein steam flows from the leading edge (11) to the trailing edge (12), which further includes a first concave surface (13) and a second convex surface (14) and the at least one rotating blades (2, 4) connected to a rotor through a axial root (7).
2. A top pressure recovery turbine as claimed in claim 1, wherein the first concave surface (13) and a second convex surface (14) passing through the set of curve profile with the suction curve, the pressure curve, the leading edge curve and the trailing edge curve at a radial distance “H” defines a blade shape.
3. A top pressure recovery turbine as claimed in claim 1, wherein re-stagger angle of the at least one inlet guide blade (1) varies from -20 to 15 deg. and re-stagger angle of the at least one stationary blade (3) varies from -15 to 10 deg from a base stagger angle.

4. A top pressure recovery turbine as claimed in claim 1, wherein the each row of the at least one inlet guide blade (1), the at least one stationary blade (3), and the at least one rotating blades (2, 4) defines by pitch by chord, a stagger angle and a gauging angle.
5. A top pressure recovery turbine as claimed in claim 1, wherein the each row having the at least one inlet guide blade (1) is circumferentially spaced about the axis of the turbine wheel and gauging of the at least one inlet guide blade (1) decreases from hub side to tip side in the range of 28.56 to 24.33, the stagger angle of the at least one inlet guide blade (1) increases from the hub side to the tip side in the range of 39.5 to 43.3 and wherein the pitch by chord of the at least one inlet guide blade (1) decreases from the hub side to the tip side in the range of 0.676 to 0.65.
6. A top pressure recovery turbine as claimed in claim 1, wherein the each row having the at least one rotating blade (2) circumferentially spaced about the axis of a turbine wheel, gauging of the at least one rotating blade (2) decreases from the hub side to the tip side in the range of 32.267 to 23.0, stagger angle of the at least one rotating blade (2) increases from the hub side to the tip side in the range of 22.58 to 56.0 and wherein the pitch by chord of the at least one rotating blade (2) increases from the hub side to the tip side in the range of 0.59 to 0.85.
7. A top pressure recovery turbine as claimed in claim 1, wherein the each row having the at least one stationary blade (3) circumferentially spaced about the axis of the turbine wheel, gauging of the at least one stationary blade (3) decreases from the hub side to the tip side in the range of 29.84 to 24.6, the stagger angle of the at least one stationary blade (3) increases from the hub side to the tip side in the range of 38.6 to 43.5 and wherein pitch by chord of the at least one stationary blade (3) decreases from the hub side to the tip side in the range of 0.6 to 0.56.

8. A top pressure recovery turbine as claimed in claim 1, wherein the each row having the at least one rotating blade (4) circumferentially spaced about the axis of a turbine wheel, gauging of the at least one rotating blade (4) decreases from the hub side to the tip side in the range of 31.64 to 22.76, stagger angle of the at least one rotating blade (4) increases from the hub side to the tip side in the range of 21.8 to 58.44 and wherein the pitch by chord of the at least one rotating blade (4) increases from the hub side to the tip side in the range of 0.86 to 0.53.