High efficiency power production method, assembly and system

Abstract

To provide a method, assembly, and system for power production that can allow for increased efficiency and lower cost components arising from the control, reduction, or elimination of turbine blade mechanical erosion by particulates or chemical erosion by gas in a combustion product flow.SOLUTION: The method, assembly and system can include the use of a turbine blade that operate with a blade velocity that is significantly reduced in relation to conventional turbines used in a typical power production system. The method and system also can make use of a recycled circulating fluid for transpiration protection of the turbine and / or other components. Further, recycled circulating fluid may be employed to provide cleaning materials to the turbine.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure provides turbine components and combustor components that may be used in power generation methods and systems. The present disclosure also provides methods of using such turbine and combustor components for power generation.

Background Art

[0002] Gas turbines are commonly used in power generation systems and methods for extracting energy from the flow of combustion gases that is induced across the blades present in the turbine to rotate the turbine shaft. The energy may be extracted from the shaft that is being rotated by a generator to provide power in the form of electricity. Due to the extreme conditions (e.g., high temperatures and the presence of erosive and / or corrosive materials) under which gas turbines operate in a typical power plant (e.g., a coal-fired power plant), gas turbine components are typically formed of high-performance materials. Thus, gas turbines are often high-cost components of power generation facilities.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Existing turbines can operate at inlet temperatures from about 1200°C to about 1400°C when the blade temperature is from about 900°C to about 1000°C. Thus, gas turbines operating in power generation facilities typically require the use of superalloy materials to withstand high temperatures. Further, for the most advanced applications, blade cooling is also required in conjunction with the use of advanced manufacturing techniques such as directionally solidified materials and even single crystal blade technology. Blade cooling is used as an aid to improve the turbine temperature tolerance and thus efficiency, but this process is limited by the fact that only air, or in some cases steam, is available for cooling. The quality of air available for cooling is limited by the amount of energy available to compress and pump air and sometimes steam through the turbine blades. Further, air is typically provided at a limited pressure, for example, a pressure close to atmospheric pressure, and thus has a limited heat transfer capacity even at high flow rates. Further, air contains a large amount of highly reactive oxygen at high temperatures, which is another factor that tends to require turbine blade metallurgy to be restricted to highly oxidation-resistant materials such as superalloys. Thus, despite the use of advanced materials and cooling, gas turbine blades are still plagued by oxidation degradation and in some cases steam degradation.

[0004] Fossil fuel sources are depleting, and while there remains a vast amount of coal that could potentially be used for power generation, the combustion of such solid fuels results in not only pollution but also particulates that can cause damage to the components of the power generation system, particularly the turbine blades. Such damage is caused, in particular, by particles in the flow of combustion products that impact the turbine blades at high speeds, for example, speeds reaching and exceeding 600 mph (268 m / sec). Previous attempts to mitigate such damage have included filtration systems for removing particulates from the flow of combustion products prior to passing through the turbine, as well as requirements regarding the use of high-performance materials in the construction of the blades. However, such requirements increase the cost of the power generation system. Furthermore, such requirements can increase the complexity of the power generation system and may decrease the efficiency of the power generation method. Accordingly, there is a need for improved gas turbine blade technology that at least overcomes the above limitations in the art.

Means for Solving the Problem

[0005] The present disclosure provides methods, assemblies, and systems for power generation that are capable of providing increased efficiency and lower cost components by controlling, reducing, or eliminating chemical degradation of turbine blades by air and steam and mechanical erosion by particulates in the flow of combustion products. The methods, assemblies, and systems can include the use of higher pressure fluid flows and / or turbine blades with increased total blade area that enable power generation with substantially reduced blade speeds and blade temperatures. The present disclosure provides, in particular, turbines having blades that are significantly smaller and cooler in at least one dimension compared to turbines used in conventional power generation systems. Such turbines can be incorporated, in particular, into a power generation method or system. For example, the method or system can incorporate the use of a high pressure, high recycle ratio circulating or working fluid such as a CO2 circulating fluid. Further, blade cooling technology can be combined with blade design, operating pressure, and operating speed to enable customization of turbine operation within the temperature, pressure, and speed ranges that control, reduce, or eliminate erosion or chemical degradation resulting from particle impingement on the turbine blades. In particular, the turbine blades can incorporate transpiration protection by passing a transpiration fluid (e.g., recycled working fluid) through the turbine blades. Such transpiration protection can include blade cooling depending on the temperature of the transpiration fluid used. Since the turbine blades can operate at significantly reduced speeds compared to turbine blades in conventional power generation systems, the present disclosure has the potential to provide reduced erosion, increased blade life, and reduced blade strength requirements. Further, the inventive turbines can operate with higher efficiency and at lower temperatures, which enables lower operating costs, longer run times, and lower fuel usage.

[0006] In one particular embodiment, a power generation method is provided. The method includes introducing fuel, O2, and a circulating fluid into a combustor, burning the fuel in the combustor to provide a combustion product stream that includes the circulating fluid and particulate components and that flows at a defined velocity, the combustion product stream expanding across a turbine having a plurality of turbine blades to generate power and output a turbine exhaust stream, the turbine being rotated such that the turbine blades rotate at a blade velocity of less than about 500 mph.

[0007] The method may further include passing the turbine exhaust stream through a filter configured to remove substantially all of the particulates included in the turbine exhaust stream to produce a filtered turbine exhaust stream. The method may also include passing the filtered turbine exhaust stream through a heat exchanger to provide a cooled turbine exhaust stream, processing the cooled turbine exhaust stream to remove one or more components of the turbine exhaust stream, and passing the processed turbine exhaust stream back through the heat exchanger to provide a heated and recirculated circulating fluid stream. The method may further include inducing at least a portion of the heated and recirculated circulating fluid stream into the combustor. Additionally, the method may include inducing at least a portion of the heated and recirculated circulating fluid stream into the turbine. Also, the method may include inducing at least a portion of the heated and recirculated circulating fluid stream into a cleaning substance unit, the heated and recirculated circulating fluid stream being combined with a cleaning substance to produce a cleaning substance stream, the cleaning substance in the cleaning substance stream being configured to remove deposits on the turbine blades resulting from particulate components present in the combustion product stream.

[0008] The cleaning substance stream may be introduced directly into the turbine. Further, the cleaning substance stream may be combined with the combustion product stream to produce a combined combustion product and cleaning substance stream that is induced into the turbine. The circulating fluid may contain CO2, which may be provided in a supercritical state. Further, the method may include combining the filtered turbine exhaust stream with particulate solid fuel to produce additional fuel in the form of a slurry, and introducing the additional fuel into a combustor. Also, the method may include using at least a portion of the recycled circulating fluid as a transpiration fluid. Using the recycled circulating fluid as a transpiration fluid may include diverging the transpiration fluid onto the outer surface of the turbine blades. Diverging the transpiration fluid onto the outer surface of the turbine blades may include diverging the transpiration fluid through a porous sintered material.

[0009] In another embodiment, a power generation system is provided. The power generation system includes a combustor configured to receive fuel, O2, and a circulating fluid, and to provide a combustion product stream including the fuel combustion and the circulating fluid and particulate components, and a turbine in fluid communication with the combustor, the turbine having an inlet for receiving the combustion product stream, an outlet for discharging a turbine exhaust stream, and a plurality of turbine blades sized to operate the turbine at a blade speed of less than about 500 mph, and a filter in fluid communication with the outlet of the turbine and configured to provide a filtered turbine exhaust stream.

[0010] The power generation system may further include a heat exchanger in fluid communication with the filter and configured to receive the filtered turbine exhaust stream. The power generation system may also include a cleaning substance unit in fluid communication with the heat exchanger, the cleaning substance unit being configured to combine a cleaning substance with a fluid stream received from the heat exchanger to produce a cleaning substance stream. The power generation system may further include a flow combiner switch configured to combine the cleaning substance stream with the combustion product stream to produce a combined combustion product and cleaning substance stream and to direct the combined combustion product and cleaning substance stream to the turbine.

[0011] The blade may include a porous sintered material, and the porous sintered material may be configured to direct a transpiration fluid to the outer surface of the blade. The porous sintered material may define the entire outer surface of the blade. Further, the turbine may include a rotor, the rotor may include a porous sintered material, and the porous sintered material may be configured to direct a transpiration fluid to the outer surface of the rotor.

[0012] In another embodiment, a power generation method is provided. The method may include introducing a fuel, O2, and a CO2 circulation fluid into a combustor, combusting the fuel to provide a combustion product stream including CO2, expanding the combustion product stream across a turbine to generate power and output a turbine exhaust stream, treating the turbine exhaust stream to recycle at least a portion of the CO2 circulation fluid into the combustor, removing a portion of the recycled CO2 circulation fluid, and using the recycled CO2 circulation fluid as a transpiration fluid.

[0013] Using the recycled CO2 circulation fluid as the transpiration fluid may include diverging the recycled CO2 circulation fluid into the turbine. Using the recycled CO2 circulation fluid as the transpiration fluid may include diverging the recycled CO2 circulation fluid into the combustor. The method may further include guiding the combustion product stream from the combustor through a conduit to the turbine, and using the recycled CO2 circulation fluid as the transpiration fluid may include diverging the recycled CO2 circulation fluid into the conduit. The method may also include adjusting the recycled CO2 circulation fluid to a temperature lower than the temperature of the combustion product stream. The method may further include adjusting the recycled CO2 circulation fluid to a temperature substantially equal to the temperature of the combustion product stream. Also, the method may include adjusting the recycled CO2 circulation fluid to a temperature higher than the temperature of the combustion product stream.

[0014] In another embodiment, a power generation system is provided. The system includes a combustor configured to receive a fuel, O2, and a CO2 circulation fluid stream and combust the fuel to provide a combustion product stream containing CO2 in the presence of the CO2 circulation fluid stream, a turbine in fluid communication with the combustor, having an inlet for receiving the combustion product stream, an outlet for discharging a turbine exhaust stream containing CO2, and a plurality of turbine blades, the combustion product stream acting on the turbine blades to rotate the turbine and generate power, and one or more components configured to process the turbine exhaust stream to produce a recycled CO2 circulation fluid stream, and one or more components of the system are configured to use a portion of the recycled CO2 circulation fluid stream as the transpiration fluid.

[0015] One or more components configured to process a turbine exhaust stream to produce a recycled CO2 circulation fluid stream may include a filter, a heat exchanger, a separator, and / or a compressor. One or more components configured to use a portion of the recycled CO2 circulation fluid stream as a transpiration fluid may include a porous sintered material configured to receive the transpiration fluid therethrough, and the turbine blades may have a blade height of less than about 0.275 m. The turbine may comprise less than 2000 turbine blades. The ratio of the length of the turbine to the average diameter of the blades may be greater than 4.

[0016] In another embodiment, a turbine assembly is provided. The assembly may comprise a plurality of components including a casing defining an inlet and an outlet configured to receive a combustion product stream. The components may further include a rotor disposed within the casing and a plurality of blades extending from the rotor, and one or more of the components may include a porous sintered material configured to direct a transpiration fluid therethrough.

[0017] The porous sintered material may define the entire outer surface of the blade. The casing may include the porous sintered material, and the porous sintered material may be configured to direct the transpiration fluid to the inner surface of the casing. The rotor may include the porous sintered material, and the porous sintered material may be configured to direct the transpiration fluid to the outer surface of the rotor. The rotor may include an annular diverter configured to divert the combustion product stream around the rotor. The assembly may further include an inlet conduit coupled to the inlet of the casing, configured to connect to and receive the combustion product stream from the outlet of the combustor assembly, and the inlet conduit may include the porous sintered material, and the porous sintered material may be configured to direct the transpiration fluid to the inner surface of the inlet conduit. The inlet of the casing may be configured to connect directly to the outlet of the combustor assembly. The inlet of the casing may be configured to receive the combustion product stream from a plurality of combustors arranged radially with respect to the spindle defined by the rotor.

[0018] The blade may include a porous sintered material, and the porous sintered material may be configured to direct the transpiration fluid to the outer surface of the blade. Each blade may further include at least one reinforcing member. The reinforcing member may include a rod extending through the porous sintered material in each blade. The reinforcing member may include a core, and the porous sintered material may extend around the core. The core may define one or more channels configured to receive the transpiration fluid and direct the transpiration fluid into the porous sintered material. One or more channels may be defined in the blade, and the channels may be configured to receive the transpiration fluid and direct the transpiration fluid into the porous sintered material. Each blade may extend from a leading edge to a trailing edge, and the blade may be configured to define a transpiration fluid flow at the leading edge that is greater than the transpiration fluid flow at the trailing edge. Each blade may define a transpiration fluid inlet area at the leading edge that is greater than the transpiration fluid inlet area at the trailing edge. Each blade may define a greater wall thickness at the trailing edge than at the leading edge. Each blade may extend from the root to the tip of the rotor, and the porous sintered material may define a porosity that varies between the root and the tip. The porosity of the porous sintered material may be configured to define a transpiration fluid flow at the tip that is greater than the transpiration fluid flow at the root. The porosity of the porous sintered material may be configured to define a transpiration fluid flow at the tip that is substantially equal to the transpiration fluid flow at the root. The porous sintered material may define a plurality of layers, and the porosity of the layers increases from the root to the tip. Each blade may respectively define a one-piece structure including a plurality of internal ribs.

[0019] The components of the turbine assembly may further include a plurality of stators, the stators include a porous sintered material, and the porous sintered material may be configured to guide the transpiration fluid to the outer surface of the stator. The turbine assembly may further include one or more seals, and one or more of the components are configured to guide the transpiration fluid to the seal. The seal may include a porous sintered material.

[0020] In another embodiment, a turbine assembly is provided. The turbine assembly may include a casing defining an inlet and an outlet configured to receive a combustion product stream. The assembly may further include a rotor disposed within the casing and a plurality of blades extending from the rotor, and the ratio of the length of the turbine assembly to the average diameter of the plurality of blades is greater than 4.

[0021] The turbine blades may have a blade height of less than about 0.275 m. The turbine assembly may include less than 2000 blades. The blades may be transpiration protected. Further, the blades include a porous sintered material configured to guide the transpiration fluid to the outer surface of the blade.

[0022] Other aspects and advantages of the present invention will become apparent from the following.

[0023] Having described the present disclosure in general terms, reference is now made to the accompanying drawings.

Brief Description of the Drawings

[0024]

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DETAILED DESCRIPTION OF THE INVENTION

[0025] The present disclosure will be described in more detail below with reference to various embodiments. These embodiments are provided so that this disclosure will be complete and full, and will fully convey the scope of this disclosure to those skilled in the art. In fact, the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will meet the applicable legal requirements. As used in this specification and the appended claims, the singular articles (''a'', ''an'', ''the'') include plural referents unless the context clearly dictates otherwise.

[0026] In one embodiment, the present disclosure relates to a turbine blade design and method of use that can reduce or even eliminate turbine blade erosion resulting from chemical degradation by air or steam or by particle impingement. The present disclosure also provides a power generation method and system that can provide high-efficiency operation while reducing or eliminating turbine blade erosion caused by particulate matter in the flow of combustion products without the need for filtration prior to passing through the turbine. The reduction and / or elimination of blade erosion simplifies the power generation system and can increase the possible feedstocks because it enables the turbine to handle flows of combustion products with higher total particulate concentrations, and is thus particularly beneficial in combustion processes using feedstocks such as coal that contain relatively high concentrations of particulate matter in the combustion products.

[0027] The terms "particulate" and "particle" (including such terms in the singular) when used with respect to the components of a combustion product stream are typically understood to specifically refer to the characteristics of particles in relation to the total volume of the combustion product stream, and specifically include solid and liquid substances present in the combustion product stream in relatively small unit sizes. In some embodiments, the particle or particulate may include any non-gaseous substance in the combustion product stream. Liquid particulates may specifically include substances that are liquid at the temperature of the combustion product stream but are solid at a temperature lower than the temperature of the combustion product stream, for example, at least 10 °C, at least 15 °C, at least 20 °C, at least 30 °C, at least 50 °C, or at least 100 °C lower than the temperature of the combustion product stream. Such liquid particulates may have a freezing point of at least ambient temperature, at least about 40 °C, at least about 50 °C, at least about 60 °C, at least about 80 °C, at least about 100 °C, or at least about 200 °C. In specific embodiments, the liquid particles may have a freezing point within the range of any combination of the temperatures listed above (e.g., within the range of at least 10 °C lower than the temperature of the combustion product stream and at least ambient temperature).

[0028] In certain embodiments, the present disclosure shows that particle impact damage on turbine blades is related to blade speed. In particular, the damage rate resulting from particle impacts can vary as approximately the cube of the blade speed relative to the particle speed. In this regard, the standard alternating current frequency adopted in the United States is 60 Hz. Further, power generation systems in the United States typically drive synchronous AC generators operating at either 1,800 rpm (30×60 Hz) or 3,600 rpm (60×60 Hz), but it should be understood that the turbines may rotate within other rpm ranges. In this regard, other countries may adopt different standard alternating current frequencies. For example, the United Kingdom operates at a frequency of 50 Hz. Further, the generator system may use a permanent magnet DC generator that is driven at any speed such that DC is converted to AC having the desired frequency. Accordingly, it should be understood that the frequencies described herein are provided as merely examples.

[0029] However, known gas turbines used in power generation systems and methods including synchronous AC generators typically operate at blade speeds of 600 mph (268 m / sec) or greater. Even the presence of very small particulate matter in the flow of combustion products can cause blade erosion at typical blade speeds in existing steam and gas turbines. The present disclosure, however, has recognized that blade erosion can be overcome through blade structure and operational modifications that enable reduced blade speeds. In a specific embodiment, the blade speed according to the present disclosure may be from about 20 m / sec to about 340 m / sec at the blade tip. More specifically, the blade speed may be less than 200 m / sec, less than 100 m / sec, or from about 50 m / sec to about 75 m / sec. In one embodiment, the present disclosure can provide turbine operation at a low blade speed (i.e., 200 mph (89 m / sec)), which is about one-third of a typical speed, which can consequently reduce the blade erosion rate to 1 / 27 or less thereof. In one embodiment, a reduction in blade speed to 150 mph (67 m / sec), i.e., one-fourth of a typical blade speed, can reduce the blade damage rate to approximately 1 / 64.

[0030] The ability of a turbine in a power generation system to operate at a lower speed can arise from various factors that can be embodied either singly or in multiple combinations. For example, the turbine blades can be designed to have dimensions such that the blade speed can be reduced to a speed at which particle collisions no longer cause erosion of the turbine blades. More specifically, the blade operating speed can be reduced below the critical speed at which erosion occurs. In this regard, the blade speed at any given point on the blade is provided by the following equation. v=(rpm / 60) * 2 * π * r (Equation 1) Wherein, v = blade speed (m / s), rpm = number of revolutions of the blade per minute, π = pi, and r = distance (m) (e.g., radius) between the center of the rotor and the point on the blade at which the blade speed is to be determined.

[0031] It should be noted that the blade speed at the tip of the blade is provided by the following equation. v t =(rpm / 60) * 2 * π * (a + b) (Equation 2) Wherein, v t = blade speed at the tip of the blade (m / s) rpm = number of revolutions of the blade per minute, π = pi, a = radius of the rotor in the blade (m), and b = blade height (m).

[0032] Accordingly, the maximum blade speed for each blade can be reduced by decreasing the distance that the blade extends from the center of the rotor. As described below, the use of a turbine having blades that extend to a relatively smaller radius will likely be made possible by using a supercritical fluid having a relatively high fluid density and high pressure at a suitable flow rate in the turbines of the present disclosure. Further, using a high density working fluid in the turbine can provide a significantly reduced turbine blade temperature by improving the ability of transpiration to cool the blades.

[0033] The blade height (i.e., the distance from the root to the blade tip at the outer surface of the turbine shaft (e.g., rotor)) is preferably less than about 0.275 m. In a specific embodiment, the average blade height can be from about 0.05 m to about 0.25 m, from about 0.075 m to about 0.225 m, from about 0.1 m to about 0.2 m, or from about 0.125 m to about 0.175 m. In a specific embodiment, the actual blade height can vary from the turbine inlet to the turbine outlet. For example, the blade height at the inlet can be lower than the average and can increase towards the outlet such that the blade height at the outlet is higher than the average. The average blade width can be from about 0.025 m to about 0.125 m, from about 0.04 m to about 0.11 m, from about 0.05 m to about 0.1 m, or from about 0.06 m to about 0.09 m. In other embodiments, the blade height and width can be additional dimensions that allow operation at the speeds described herein.

[0034] The inventive turbine and operating method can also be characterized by the overall turbine dimensions. For example, the turbine according to the present disclosure can have an overall length of less than about 11 m, less than about 10 m, or less than about 9 m. In further embodiments, the overall turbine length can be from about 6 m to about 10 m, from about 6.5 m to about 9.5 m, from about 7 m to about 9 m, or from about 7.5 m to about 8.5 m. The turbine according to the present disclosure can have an average diameter of less than about 3.5 m, less than about 3 m, or less than about 2.5 m. In further embodiments, the average turbine diameter can be from about 0.25 m to about 3 m, from about 0.5 m to about 2 m, or from about 0.5 m to about 1.5 m. The ratio of the turbine length to the average turbine diameter (i.e., the diameter of the turbine blades) can be a value greater than about 3.5, greater than about 4, greater than about 4.5, or greater than about 5. In a specific embodiment, the ratio of the turbine length to the average turbine diameter can be from about 3.5 to about 7.5, from about 4 to about 7, from about 4.5 to about 6.5, or from about 5 to about 6. The above ratio can specifically be related to the overall length of the turbine. In some embodiments, the overall length may refer to the length of the casing from the inlet to the outlet. In one embodiment, the overall length may refer to the distance within the casing from the turbine blade adjacent immediately next to the inlet to the turbine blade adjacent immediately next to the outlet.

[0035] The inventive turbine and operating method can be similarly characterized by the average blade radius (from the center of the rotor to the tip of the turbine blade). Preferably, the turbine operates at an average blade radius of less than about 1.2 m, less than about 1.1 m, less than about 1 m, less than about 0.9 m, less than about 0.8 m, less than about 0.7 m, or less than about 0.6 m. The turbine blade radius can specifically be from about 0.25 m to about 1 m, from about 0.275 m to about 0.8 m, from about 0.3 m to about 0.7 m, from about 0.325 m to about 0.6 m, from about 0.35 m to about 0.5 m, or from about 0.375 m to about 0.475 m.

[0036] In some embodiments, turbines useful according to the present disclosure can have a significantly lower total number of turbine blades than are present in typical gas turbine systems. Specifically, inventive turbines may have fewer than about 3,000 blades, fewer than about 2,500 blades, or fewer than about 2,000 blades. In further embodiments, the number of blades in a turbine can be between about 500 and about 2,500, between about 750 and about 2,250, between about 1,000 and about 2,000, or between about 1,250 and about 1,750.

[0037] In some embodiments, turbines according to the present disclosure may provide highly efficient power generation with reduced blade speeds, particularly through operation at significantly increased inlet pressures and / or significantly increased outlet pressures and / or significantly increased pressure drops from inlet to outlet relative to typical gas turbine power generation systems. In specific embodiments, the turbines may operate at inlet pressures of at least about 25 bar (2.5 MPa), at least about 50 bar (5 MPa), at least about 100 bar (10 MPa), at least about 150 bar (15 MPa), at least about 200 bar (20 MPa), or at least about 250 bar (25 MPa). In further embodiments, the inlet pressure can be from about 50 bar (5 MPa) to about 500 bar (50 MPa), from about 100 bar (10 MPa) to about 450 bar (45 MPa), from about 150 bar (15 MPa) to about 400 bar (40 MPa), from about 200 bar (20 MPa) to about 400 bar (40 MPa), or from about 250 bar (25 MPa) to about 350 bar (35 MPa).

[0038] In a further embodiment, the turbine can operate at an outlet pressure of at least about 5 bar (0.5 MPa), at least about 10 bar (1 MPa), at least about 15 bar (1.5 MPa), at least about 20 bar (2 MPa), or at least about 25 bar (2.5 MPa). The outlet pressure can in particular be from about 10 bar (1 MPa) to about 50 bar (5 MPa), from about 15 bar (1.5 MPa) to about 45 bar (4.5 MPa), from about 20 bar (2 MPa) to about 40 bar (4 MPa), or from about 25 bar (2.5 MPa) to about 35 bar (3.5 MPa).

[0039] In other embodiments, the ratio of the turbine inlet pressure to the turbine outlet pressure can be at least about 6, at least about 7, at least about 8, at least about 9, or at least about 10. In a specific embodiment, the ratio of the turbine inlet pressure to the turbine outlet pressure can be from about 6 to about 15, from about 7 to about 14, from about 8 to about 12, or from about 9 to about 11.

[0040] In still further embodiments, the turbines according to the present disclosure can operate in a power generation system at a significantly increased flow density relative to the operation of turbines in typical power generation systems. For example, the inventive turbines can operate at a flow density of at least about 20 kg / m 3 , at least about 50 kg / m 3 , at least about 100 kg / m 3 , at least about 150 kg / m 3 , at least about 200 kg / m 3 , or at least about 300 kg / m 3 , at least about 400 kg / m 3 , at least about 500 kg / m 3 , or at least about 600 kg / m 3 .

[0041] In contrast to the turbines according to the present disclosure, existing gas turbine compressors have a gas density in the compressor section of from 1 kg / m 3 to about 15 kg / m 3It may operate at outlet pressures ranging from about 1 bar (0.1 MPa) to about 15 bar (1.5 MPa) when adiabatic compression heating is assumed. Erosion and other problems may not be serious in the compressor due to the relatively low temperatures therein. However, in the hot zone, gas temperatures may vary from a peak of approximately 1727°C to about 527°C. The density of the gas in the hot zone may be as high as about 5 kg / m 3 From low to about 0.5 kg / m 3 Thus, conditions inside existing turbines may vary significantly from the conditions in a turbine according to the present disclosure.

[0042] The use of higher pressures at lower flow rates and higher temperatures can increase torque on the turbine blades. Therefore, the turbine may include features configured to reduce the torque exerted on the blades. In particular, the turbine may include a greater number of blades, disks, and / or stages than conventional turbines, which distributes the torque therebetween and reduces the torque exerted on each individual blade. Furthermore, the blades may define angles of attack configured to reduce the forces and torque exerted on the blades. In particular, the blades may define a reduced angle relative to the flow through the turbine, which induces less drag and increases the lift-to-drag ratio. Therefore, these features may reduce the torque exerted on each of the blades, such that they may be formed from relatively less strong and relatively less expensive materials.

[0043] In some embodiments, blade erosion may also be controlled, reduced, or eliminated by combining any of the features described above with one or more blade cooling methods. Any turbine blade cooling method may be combined with the present disclosure, including transpiration blade cooling, as more fully described below. In this regard, transpiration cooling may be used to cool any of the various components of the turbines, combustors, and related devices disclosed herein. Particularly with respect to turbines, for example, the case, stators (e.g., stator blades), seals, blades (e.g., turbine blades), rotors, and various other internal components may be transpiration cooled through the use of porous materials disclosed herein. In this regard, the stator may include a porous sintered material, which may be configured to direct the transpiration fluid to the outer surface of the stator. Further, one or more of the components of the turbine assembly may be configured to direct the transpiration fluid to the seal. The seal may include a porous sintered material in some embodiments. Embodiments that are examples of seals and stators that may be transpiration cooled in accordance with some embodiments of the present disclosure are described in U.S. Patent Application Publication No. 2009 / 0142187, which is incorporated herein by reference in its entirety. However, various other embodiments of the components of turbines, combustors, and related devices may also be transpiration cooled in accordance with the present disclosure.

[0044] Furthermore, the transpiration cooling technology disclosed herein may provide improved cooling over existing transpiration cooling technologies. Current blade cooling is typically performed with bleed air from the compressor of the turbine. This air has its relatively low density (e.g., 0.5 - 5 kg / m 3has a limited heat capacity due to . This limits the heat transfer rate. In contrast, as described below, the present disclosure provides transpiration cooling through the use of CO2, which may provide improved heat transfer.

[0045] The heat transfer rate for existing embodiments of the turbine is also limited by the relatively large stresses that occur on the turbine blades due to the long length of the blades that result in high centrifugal forces during its rotation. The cooling passages of existing turbines must therefore be kept relatively small and should not be defined to be larger than a relatively small portion of the total blade cross-sectional area in order to limit the reduction in the longitudinal strength of the blade caused by the cooling passages.

[0046] The inventive turbine is particularly useful in systems and methods for power generation in that the turbine can provide not only reduced blade erosion but also a significantly reduced total turbine cost. In a specific embodiment, the total turbine cost can be reduced by at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, or at least 75% with no significant loss of power output (i.e., a loss of less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, or less than 0.8%) relative to a turbine used in a typical power generation system. The cost reduction can occur, for example, by avoiding the need for superalloys and / or other expensive materials in the blades due to the reduction in the centrifugal forces acting thereon. Further, by using a high inlet temperature and a high operating pressure in the turbine relative to existing embodiments of the turbine, the reduction in power output can be minimized despite the reduction in the rotational speed.

[0047] In a specific embodiment, the present disclosure can include systems and methods for power generation that can incorporate the turbine blade designs and operating modes of the present invention. For example, the inventive systems and methods enable power generation through the use of a high-efficiency fuel combustor (such as a transpiration-cooled combustor) optionally with an associated circulating fluid (such as a CO2 circulating fluid). Specifically, the use of a high-pressure circulating fluid (or working fluid) with a high CO2 recycle ratio provides the ability to direct a portion of the CO2 circulating fluid to the turbine blades for transpiration cooling.

[0048] The combination of transpiration cooling of the present disclosure with blade design and operating modes can be particularly useful because erosion can be made a function of turbine blade temperature and blade material composition. The combination of turbine blade design and operation with blade operating temperature can provide a wide range of possible blade operating speeds and blade operating temperatures at which blade erosion can be controlled, reduced, or eliminated. At lower blade temperatures, erosion is lower and the blade speed at which erosion begins may be higher. The ability to select operating conditions is beneficial in that it allows the use of metal alloys that can withstand erosion at higher blade speeds but would not otherwise be available for use at higher operating temperatures. In this regard, at lower temperatures, high-strength steel is relatively resistant to impact damage. As an example, homogeneous rolled steel armor used on military vehicles is not damaged by solid steel projectiles moving at speeds up to 400 mph (179 m / sec).

[0049] In other embodiments, however, as will be more fully explained below, transpiration can provide blade protection by preventing the solidification of combustion product stream components (e.g., liquid ash). In such embodiments, transpiration cooling may be defined as cooling of the blade (and / or other components) to a temperature below the temperature of the combustion product stream. More specifically, such cooling may be configured to have a lower limit higher than the temperature at which components of the combustion product stream (e.g., liquid ash) would freeze (or solidify) and thus be deposited on the turbine blades. For example, ash softening may begin at 590 °C and melting may occur at 870 °C. Without transpiration cooling, the turbine would need to operate well below 590 °C to avoid ash accumulation on the blades, which may be too low for efficient operation. With transpiration protection, the turbine can operate above 870 °C where the ash is liquid but the droplets do not touch or adhere to the surface, by means of a transpiration vapor layer that covers substantially all surfaces that are subject to contact with components of the stream flowing through the turbine (e.g., the inner surface of the turbine housing, the outer surface of the turbine blades within the turbine, etc.). Thus, transpiration protection can reduce or eliminate not only degradation due to mechanical erosion by particle impingement, but also chemical degradation by keeping the blades cooler and by exchanging air or air / vapor as a coolant for CO2 as a coolant in the form of a transpiration fluid.

[0050] In some embodiments, it may be useful for the turbine to operate at a blade speed relative to the speed of the flow of combustion products. In such embodiments, it may be particularly beneficial for the flow speed to be significantly lower than the flow speed in a typical combustion process. For example, the flow speed according to the present disclosure can be less than about 400 mph (179 m / s), less than about 350 mph (156 m / s), less than about 300 mph (134 m / s), less than about 250 mph (112 m / s), less than about 200 mph (89 m / s), less than about 150 mph (67 m / s), or less than about 100 mph (45 m / s). The ratio of the blade tip speed to the flow speed is preferably greater than 1, greater than 1.5, greater than 2, greater than 2.5, or greater than 3. Specifically, the ratio of the blade tip speed to the flow speed can be from about 1 to about 5, from about 1.5 to about 4.75, from about 1.75 to about 4.5, from about 2 to about 4.25, or from about 2.5 to about 4.

[0051] As a result of erosion, the turbine may experience a degradation in performance over time (e.g., through decreased efficiency and / or power output). For example, a conventional turbine may experience an operational degradation of 10% power loss over a period of 2 - 3 years. An overhaul to repair the turbine can cost approximately 50% of the purchase price of the turbine. Thus, over a 20-year lifespan, an existing turbine may need to be overhauled a total of 8 times, which can cost a total of 4 times the initial purchase price of the turbine.

[0052] This deterioration can be attributed to erosion caused by residual dust particles passing through an air filtration system located between the combustor and the turbine. Increasing the particulate removal effectiveness of the filter may not be a viable option because it can restrict airflow and reduce turbine efficiency. Therefore, the disclosed turbine may offer significant cost savings by minimizing or eliminating the need for overhauls by minimizing or eliminating damage from erosion. In this regard, the rate of dissipation of impact energy associated with a collision between a particle and a blade is approximately proportional to the cube of the relative velocity between them. In this regard, turbine blade erosion tends to be approximately proportional to the impact energy dissipation rate ("impact power"), as exemplified below. IP=kV 3 / X (formula 3) During the ceremony, IP = collision power, k=variation factor based on particle material, blade material, ambient temperature, and impact angle; v = relative velocity between the turbine blade and the particle, and X = characteristic length of the collision interaction.

[0053] By reducing blade speed and providing transpiration protection, impacts may be minimized or reduced below the threshold at which erosion occurs, and chemical damage may also be reduced or eliminated. Therefore, expenses associated with overhauls due to erosion may be reduced or eliminated, and thus some embodiments of the turbines provided herein may offer significant cost savings. Furthermore, as noted above, by eliminating the need for the use of expensive superalloys, turbines according to the present disclosure may be relatively less expensive than existing turbines.

[0054] In various known embodiments of power plants, efficiency depends critically on the turbine inlet temperature. For example, significant research has been done at great cost to achieve turbine technologies that enable inlet temperatures as high as about 1,350 °C. The higher the turbine inlet temperature, the higher the plant efficiency, but the more expensive the turbine becomes and potentially the shorter its lifespan. Due to the relatively high temperature of the combustion product stream, it may be beneficial for the turbine to be formed of materials that can withstand such temperatures. It may also be useful for the turbine to include materials that provide good chemical resistance to types of secondary materials that may be present in the combustion product stream.

[0055] In one embodiment, the present disclosure can provide, among other things, the use of a coolant with turbine components. As will be more fully described below, for example, the inventive systems and methods enable power generation through the use of a high-efficiency fuel combustor (e.g., a transpiration-cooled combustor) and an associated circulating fluid (such as a CO2 circulating fluid). Specifically, a portion of the circulating fluid to be used for turbine cooling, such as through transpiration cooling, can be directed to turbine components, particularly turbine blades.

[0056] For example, in some embodiments, a portion of the CO circulating fluid can be removed from the cycle (e.g., from a portion of the cycle where the circulating fluid is under conditions useful for transpiration coolant) and directed to the turbine for cooling components, particularly the turbine blades. Blade coolant can be exhausted through holes (or perforations) in the turbine blades and injected directly into the turbine flow. Thus, rather than using air as a transpiration coolant (whose cooling capacity is limited as discussed above and hindered by safety concerns), the disclosed methods and systems provide for the use of very large quantities of high-pressure CO, supercritical CO, or even liquid CO as the turbine blade coolant. This is highly useful because it increases the cooling capacity available for the turbine blades by a large factor over known blade cooling methods. The present disclosure is also particularly useful because the CO circulating fluid can be present in very large quantities in the system, allowing very large volumes of coolant to be moved through the turbine blades. This high volume and / or high mass flow rate of CO2 coolant through the turbine blades not only protects the blades from extreme heat, which is useful for high-efficiency power generation methods, but also helps protect the blades from the corrosive and erosive effects of hot gases and unfiltered particulate matter flowing through the turbine due to the transpiration of CO2 coolant across the entire surface of the blades. In one embodiment, transpiration cooling may provide operating blade temperatures of about 200°C to about 700°C despite the significantly higher turbine inlet temperatures (e.g., 1350°C) described above, which may therefore enable the use of turbine blades comprising relatively less expensive materials than currently used, and / or higher turbine inlet temperatures may be used, which may lead to greater efficiency. The above-described transpiration-cooled turbine components may be used in any power generation method and system where high-pressure CO2 (or other fluids less corrosive than steam, such as air or N2) may be available as a circulating fluid with a high recirculation ratio.

[0057] In a specific embodiment, the use of a CO2 refrigerant enables the turbine blade to be made of materials that are much lower in cost than known turbine blades used in high-efficiency power generation methods, because the use of the CO2 refrigerant prevents the blade in the present disclosure from being heated to extreme temperatures of the surrounding combustion product flow and reduces the corrosive and erosive effects of the combustion product flow. For example, according to the present disclosure, the turbine blade may be made of various high-strength steels or even relatively low-cost steels. Similarly, the blade may be made of a carbon composite or even a low-temperature material such as aluminum. For gas turbine components used under low-temperature conditions and / or low-erosion or low-corrosion conditions, and further for turbines, any material recognized as useful in the art may be used to fabricate the turbine components according to the present disclosure.

[0058] The transpiration cooling of the turbine blade with a portion of the CO2 circulating fluid according to the present disclosure is also useful because it can facilitate the safe passage of combustion gases containing ash (or other particulate matter and / or incombustibles) through the turbine without the need for intervening filtration steps and components. This can greatly simplify the design of the power generation facility and increase the types of materials that may be used as fuel sources for combustion.

[0059] The use of the CO2 circulating fluid in the transpiration cooling of the turbine components according to the present disclosure is also advantageous for the thermodynamics of the power generation cycle. Due to the greatly improved cooling ability of the CO2 circulating fluid compared to known transpiration media for turbine blades, the combustor can be operated at elevated temperatures without limitations on the thermal tolerance of the turbine. Thus, the combustion product flow can pass through a CO2-cooled turbine without damage to the turbine components, so a combustor (e.g., a transpiration-cooled combustor) that can operate at extremely high temperatures can operate at temperatures close to the maximum according to the present disclosure. This increases the potential thermodynamic efficiency of the power generation cycle to near 100%.

[0060] Any combination of turbine blade design, overall turbine design, and transpiration cooling of the turbine blade can be used in any power generation method in which the life of the turbine blade, such as a method and system in which combustion results in particle generation, is desirably extended. In some embodiments, the method and system can be such that a circulating fluid can be used. For example, high-pressure CO2 may be available for use as a circulating fluid with a high recirculation ratio.

[0061] For example, the turbines as described herein may be used in methods and systems in which a CO2 circulating fluid is provided in a combustor along with a suitable fuel, any necessary oxidant, and any associated materials that may be useful for efficient combustion. Such systems and methods can include a combustor that operates at very high temperatures (e.g., within a range of about 1,600 °C to about 3,300 °C or even higher temperatures), and the presence of the circulating fluid can function to adjust the temperature of the fluid stream exiting the combustor so that the fluid stream can be used for energy transfer for power generation. Specifically, the combustion product stream can expand across at least one turbine to generate power. The expanded gas stream can be cooled to remove various components such as water from the stream, and the heat removed from the expanded gas stream can be used to heat the CO2 circulating fluid. The purified circulating fluid stream can then be pressurized and heated for recirculation through the combustor. Exemplary power generation systems and methods that may incorporate the turbine blade designs (with or without associated blade transpiration cooling) of the present disclosure are described in U.S. Patent Application Publication No. 2011 / 0179799, which is hereby incorporated by reference in its entirety.

[0062] The incorporation of the turbine according to the present disclosure in a combustion power cycle is particularly useful for the combustion of fuels that result in particulate components. Various types of coal, for example, can be burned in a power generation cycle to produce a combustion stream having ash and / or other particulate components. Advantageously, when the turbine according to the present disclosure is incorporated into the combustion cycle, the entire combustion product stream (i.e., including all components of the particulate matter) can be introduced into the turbine without the need for a preliminary filtering step. This allows for the use of higher turbine inlet temperatures, which in turn increases the combustion efficiency for processes that require filtration of the combustion products before passing through the turbine. This is possible according to the present disclosure because the inventive turbine can withstand particle impingement without significant erosion. The particulate matter can then be filtered from the stream exiting the turbine.

[0063] One embodiment of a combustion cycle provided in accordance with the present disclosure is illustrated in the flowchart of FIG. 1. In the illustrated embodiment, an air separation unit 100 is provided to take in ambient air 10 and output an oxygen-enriched stream 120. The oxygen stream 120 may contain oxygen having a molar purity of at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 85%, at least about 90%, or at least about 95%. The oxygen stream 120 may be supplied by any air separation system / technique known in the art, such as, for example, a cryogenic air separation process or a high-temperature ion transport membrane oxygen separation process (from air) that may be implementable. In a specific embodiment, the oxygen-enriched stream may be provided by the operation of a cryogenic air separation process, and oxygen is pressurized in the process by pumping liquid oxygen that is efficiently heated to ambient temperature while maintaining refrigeration. Such a cryogenic pumped oxygen plant can have two air compressors, both of which can operate adiabatically without intermediate stage cooling. In a specific embodiment, it may be useful to include components useful for recovering heat generated by the air separation unit and transferring heat to components of the presently described system where heat input may be desirable.

[0064] The cycle illustrated in FIG. 1 may be useful for the combustion of any fuel source that includes particulate matter (e.g., ash) as a constituent of the combustion products. Non-limiting examples of useful fuels according to the present disclosure include various grades and types of coal, wood, oil, tar from tar sands, bitumen, biomass, algae, graded combustible solid waste refuse, asphalt, and used tires. In particular, any solid fuel material may be used in the present disclosure, and such fuels may be pulverized, shredded, or otherwise processed, particularly to reduce the particle size as appropriate. A fluidizing or slurrying medium may be added as needed to achieve an appropriate form and to meet the flow requirements for high-pressure pumping. For example, referring to FIG. 1, solid fuel 15 may pass through a mill device 200 to provide a pulverized fuel. In other embodiments, solid fuel 15 may be provided in a pre-particleized state prior to the need for on-site milling. In a specific embodiment, solid fuel 15 may have an average particle size of from about 10 μm to about 500 μm, from about 25 μm to about 400 μm, or from about 50 μm to about 200 μm. In other embodiments, solid fuel 15 may be described by having 50%, 60%, 70%, 80%, 90%, 95%, or 99% or more of the solid fuel particles having an average particle size of less than about 500 μm, 400 μm, 300 μm, 200 μm, or 100 μm.

[0065] The solid fuel 15 can be appropriately processed to enable injection into the combustion device at a sufficient rate and at a pressure above the pressure within the combustion chamber. To provide such characteristics, the solid fuel 15 may be in the form of a liquid, slurry, gel, or paste having appropriate fluidity and viscosity at ambient temperature or elevated temperature. For example, the solid fuel 15 may be provided at a temperature of about 30°C to about 500°C, about 40°C to about 450°C, about 50°C to about 425°C, or about 75°C to about 400°C. When the solid fuel 15 is in a state where its particle size is appropriately reduced by being powdered, shredded, or otherwise processed, a fluidizing or slurrying medium can be added as necessary to achieve an appropriate form and meet the flow requirements for high-pressure pumping. As illustrated in the embodiment of FIG. 1, the particulate solid fuel 220 resulting from the solid fuel 15 by the mill device 200 can be mixed with a fluidizing substance to provide coal in the form of a slurry. In particular, the particulate solid fuel 220 is combined in the mixer 250 with a CO2 sidestream 562 from the recirculated CO2 circulation fluid stream 561. The CO2 sidestream 562 may be provided in a supercritical, high-density state. In a specific embodiment, the CO2 used to generate the slurry can have a density of about 450 kg / m 3 ~ about 1,100 kg / m 3 . More specifically, the CO2 sidestream 562 may cooperate with the particulate solid fuel 220 to produce a slurry 255 having, for example, from about 10 wt% to about 75 wt% or from about 25 wt% to about 55 wt% particulate coal. Further, the CO2 from the sidestream 562 used to generate the slurry 255 may be at a temperature of less than about 0°C, less than about -10°C, less than about -20°C, or less than about -30°C. In a further embodiment, the CO2 from the sidestream 562 used to generate the slurry may be at a temperature of about 0°C to about -60°C, about -10°C to about -50°C, or about -18°C to about -40°C. Although the slurrying step is described with respect to using CO2 as the slurrying medium, it is understood that other slurrying media may be possible.

[0066] Slurry 255 can be transferred from mixer 250 to combustion device 300 via pump 270. In a specific embodiment, combustion device 300 can be a high-efficiency combustor that can provide substantially complete combustion of fuel at a relatively high combustion temperature. High-temperature combustion can provide substantially complete combustion of all combustible components of the fuel and may thus be particularly useful for maximizing efficiency. In various embodiments, high-temperature combustion can mean combustion at a temperature of at least about 1,000 °C, at least about 1,200 °C, at least about 1,500 °C, at least about 2,000 °C, or at least about 3,000 °C. In further embodiments, high-temperature combustion can mean combustion at a temperature of about 1,000 °C to about 5,000 °C or about 1,200 °C to about 3,000 °C.

[0067] In one embodiment, combustion device 300 may be a transpiration-cooled combustor. An example of a transpiration-cooled combustor that may be used in the present disclosure is described in U.S. Patent Application Publication Nos. 2010 / 0300063 and 2011 / 0083435, the entire disclosures of which are incorporated herein by reference. In some embodiments, useful transpiration-cooled combustors according to the present disclosure may include one or more heat exchange zones, one or more coolants, and one or more transpiration fluids.

[0068] The use of a transpiration-cooled combustor according to the present disclosure is particularly advantageous over known techniques for fuel combustion for power generation. For example, the use of transpiration cooling may be useful for preventing corrosion, fouling, and erosion in the combustor. This further enables the combustor to function within a temperature range high enough to result in complete or at least substantially complete combustion of the fuel used. These and further advantages are further described herein.

[0069] In one particular aspect, a useful transpiration-cooled combustor according to the present disclosure can include a combustion chamber at least partially defined by a transpiration member, the transpiration member being at least partially surrounded by a pressure containment member. The combustion chamber can have an inlet portion and an opposite outlet portion. The inlet portion of the combustion chamber can be configured to receive a carbon-containing fuel to be combusted within the combustion chamber at a combustion temperature to produce combustion products. The combustion chamber can further be configured to direct the combustion products toward the outlet portion. The transpiration member can be configured to direct a transpiration material toward the combustion chamber therethrough to mitigate interaction between the combustion products and the transpiration member. Furthermore, the transpiration material can be introduced into the combustion chamber to achieve a desired exit temperature of the combustion products. In certain embodiments, the transpiration material can at least partially comprise a circulating fluid. The walls of the combustion chamber can be lined with a layer of porous material through which the transpiration material, such as CO2 and / or HO, is directed and flows.

[0070] The flow of transpiration material through this porous transpiration layer, and optionally through additional equipment, can be configured to achieve a desired total outlet fluid stream exit temperature from the combustion device 300. In some embodiments, as further described herein, such temperatures can be in the range of about 500°C to about 2,000°C. This flow can also help cool the transpiration element to a temperature below the maximum allowable operating temperature of the material forming the transpiration element. The transpiration material can also help prevent the impingement of any liquid or solid ash material or other contaminants in the fuel that could corrode, foul, or otherwise damage the walls. In such situations, it may be desirable to use a material for the transpiration element with reasonable thermal conductivity so that incident radiant heat is conducted radially outward through the porous transpiration element and then intercepted by convective heat transfer from the surface of the porous layer structure radially inward through the transpiration layer to the passing fluid. Such a configuration may allow the subsequent portion of the stream directed through the transpiration element to be heated to a temperature within a desired range, such as about 500°C to about 1,000°C or about 200°C to about 700°C, while simultaneously maintaining the temperature of the porous transpiration element within the design range of the material used therefor. Suitable materials for the porous transpiration element may include, for example, porous ceramics, refractory metal fiber mats, drilled cylindrical sections, and / or sintered metal layers or powders. A secondary function of the transpiration element may be to ensure substantially uniform radially inward and longitudinal flow of transpiration fluid through the combustor to achieve good mixing between the transpiration fluid stream and the combustion products while promoting uniform axial flow along the length of the combustion chamber.A third function of the transpiration element may be to achieve a radially inward diluent fluid velocity that provides mitigation or otherwise prevents solid and / or liquid particles of ash or other contaminants in the combustion products from impinging on the surface of the transpiration layer and causing blockage, erosion, corrosion, or other damage. Such a factor may be important only when burning fuels such as coal that have residual inert non-combustible residues, for example. The interior walls of the combustor pressure vessel surrounding the transpiration element may also be insulated to isolate the hot transpiration fluid stream within the combustor.

[0071] In some embodiments, a mixing facility (not illustrated) may be provided to combine materials to be introduced into the combustion device 300 prior to such introduction. Specifically, any combination of two or all three of fuel, O2, and circulating fluid (e.g., CO2 circulating fluid) may be combined in the optional mixing facility prior to introduction into the combustion device 300.

[0072] Fuel 15, along with O2 120 and recycled circulating fluid 503 (as slurry stream 255), is introduced into combustor 300 and combusted to provide combustion product stream 320. In a specific embodiment, combustor 300 is a transpiration-cooled combustor as described above. The combustion temperature can vary depending on specific process parameters, such as the type of fuel used, the molar ratio of circulating fluid to carbon in the fuel as introduced into the combustor, and / or the molar ratio of CO2 to O2 introduced into the combustor. In a specific embodiment, the combustion temperature is as described above in connection with the description of a transpiration-cooled combustor. In particularly preferred embodiments, combustion temperatures above about 1,000°C may be advantageous as described herein.

[0073] It may also be useful to control the combustion temperature so that the combustion product stream exiting the combustor has a desired temperature. For example, it may be useful for the combustion product stream exiting the combustor to have a temperature of at least about 700°C, at least about 900°C, at least about 1,200°C, or at least about 1,600°C. In some embodiments, the combustion product stream may have a temperature of from about 700°C to about 1,600°C or from about 1,000°C to about 1,500°C.

[0074] Specifically, the pressure of the combustion product stream 320 can be related to the pressure of the circulating fluid introduced into the combustion device 300. In a specific embodiment, the pressure of the combustion product stream 320 can be at least about 90% of the pressure of the circulating fluid introduced into the combustion device 300.

[0075] The chemical composition of the combustion product stream 320 exiting the combustion device 300 can vary depending on the type of fuel used. Importantly, the combustion product stream will include the main component (e.g., CO2) of the circulating fluid that will be recycled or reintroduced into the combustion device 300 or a further cycle. In a further embodiment, the combustion product stream 320 may include one or more of water vapor, SO2, SO3, HCl, NO, NO2, Hg, excess O2, N2, Ar, incombustibles, and / or other particulate matter, and other contaminants that may potentially be present in the fuel being burned. These substances present in the combustion product stream may continue to be present in the CO2 circulating fluid stream unless removed by a process such as that described herein.

[0076] Advantageously, according to the present disclosure, the combustion product stream 320 can be directed to the turbine 400 without first removing any particulate matter in the combustion product stream 320 with a filter. In the turbine 400, the combustion product stream 320 expands to generate power (e.g., generates electricity via generator 400a). The turbine 400 can have an inlet for receiving the combustion product stream 320 and an outlet for discharging the turbine exhaust stream 410. Although a single turbine 400 is shown in FIG. 1, it is understood that more than one turbine may be used, and multiple turbines may be coupled in series or optionally separated by one or more additional components such as additional combustion components, compression components, separator components, etc.

[0077] The turbine 400 can specifically be a turbine having a blade design and / or an overall design as separately described herein. Further, the turbine may incorporate transpiration cooling or other cooling techniques as described herein. In particular, the turbine design can have a low blade speed and ash particle impact velocity such that the turbine can withstand collisions without significant erosion. The transpiration cooling of the turbine can further protect against particle erosion by providing a continuous flow barrier layer of the transpiration fluid between the blade surface and the particulate matter passing through the turbine.

[0078] Returning to FIG. 1, the exemplary system and cycle further includes a filter 5 downstream from the turbine 400. The turbine exhaust stream 410 can pass through the filter 5 to remove particulate matter therefrom. The location of the filter 5 downstream of the turbine 400 rather than upstream of the turbine is an advantageous feature of the present disclosure because the combustion product stream 320 can expand across the turbine at a higher temperature and pressure as soon as it exits the combustor device 300, and thus power generation can be maximized. The lower pressure and lower temperature turbine exhaust stream 410 can then be filtered by the filter 5 to remove particulate matter therefrom as a particulate stream 7. Thus, a filtered turbine exhaust stream 420 substantially free of particulate matter is provided for further processing in the combustion cycle.

[0079] In specific embodiments, the filter 5 may preferably include a configuration effective to remove substantially all of the particulate matter present in the combustion product stream 320. The filter 5 may include a cyclone filter and / or a candle filter in some embodiments, and filtration may occur at temperatures from about 300°C to about 775°C in some embodiments. In particular embodiments, removal of substantially all particulates may include removal of at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, or at least 99.8% of the volume of particulates present in the combustion product stream. The particulate removal efficiency of such filters may be related to particle size. For example, the recited percentage of particles removed may be related to the filter's ability to retain particles having a diameter of at least about 0.1 μm, at least about 0.5 μm, at least about 1 μm, at least about 5 μm, at least about 10 μm, at least about 25 μm, at least about 50 μm, at least about 100 μm, or at least about 500 μm. In one embodiment, particles produced by combustion may be in the range of about 0.1 μm to about 100 μm, and the filter removes substantially all particles greater than about 1 μm, greater than about 5 μm, greater than about 10 μm, greater than about 15 μm, or greater than about 20 μm, and maintains a total particulate level of about 10 mg / m 3 Less than about 5 mg / m 3 Less than about 1 mg / m 3 Less than or about 0.5 mg / m 3 It may be configured to reduce the

[0080] In certain embodiments (i.e., where CO2 is used as the circulating fluid), the filtered turbine exhaust stream 420 can pass through a heat exchanger unit 500 (which may be a series of heat exchangers) to produce an untreated recycle stream 501. This untreated recycle stream 501 can pass through a cold water heat exchanger 520 to produce a stream 521, which passes through a separator 540 as stream 542 for the removal of secondary components (e.g., H2O, SO2, SO4, NO2, NO3, and Hg). In a specific embodiment, the separator 540 can include a reactor that provides a contactor with sufficient residence time such that impurities can react with water to produce a substance (e.g., an acid) that is easily removed. The purified circulating fluid stream 541 from the separator 540 can pass through a compressor 550 to produce a stream 551, which can be further cooled in a cold water heat exchanger 560 to provide a supercritical high density CO2 circulating fluid 561. In some embodiments, the purified CO2 circulating fluid 541 can be compressed to a pressure of at least about 7.5 MPa or at least about 8 MPa. A portion of stream 561 can be withdrawn as stream 562 and used as a fluidizing medium in mixer 250 to produce a slurry stream 255. Another portion of the supercritical high density CO2 circulating fluid stream 561 is further pressurized in compressor 570 to produce a pressurized supercritical high density CO2 circulating fluid stream 571. A portion of the CO2 in stream 571 may be withdrawn as stream 572 to a CO2 pipeline or other sequestration means. The remaining portion of the CO2 can proceed as a pressurized supercritical high density CO2 circulating fluid stream 573, which can be returned and passed through a heat exchanger 500 (or a series of heat exchangers) to heat the stream. In a specific embodiment, the CO2 circulating fluid is at least about 200 kg / m 3 , at least about 300 kg / m 3 , at least about 500 kg / m 3 , at least about 750 kg / m 3 , or at least about 1,000 kg / m3 It can be provided at a density of. In a further embodiment, the density is about 150 kg / m 3 ~ about 1,100 kg / m 3 It may be. The passage of stream 551 through the cold water heat exchanger 560 can cool the CO2 circulation fluid to a temperature of less than about 60 °C, less than about 50 °C, or less than about 30 °C. The CO2 circulation fluid in stream 561 entering the second compressor 570 can be provided at a pressure of at least about 12 MPa. In some embodiments, the stream can be pressurized to a pressure of about 15 MPa to about 50 MPa. Any type of compressor, such as a high-pressure multistage pump, can be used that can operate at the temperatures mentioned and achieve the pressures described.

[0081] The heated and pressurized supercritical high-density CO2 circulating fluid can exit the heat exchanger 500 as a first stream 503 to be provided as the recirculating fluid. In some embodiments, the heated and pressurized supercritical high-density CO2 circulating fluid can exit the heat exchanger 500 as a second recirculated circulating fluid stream 504 to be provided as the transpiration fluid for the turbine blades. Preferably, the second recirculated circulating fluid stream 504 can be controllable such that it can increase or decrease the total weight or volume of the circulating fluid in the stream as desired to increase or decrease the protection provided by the transpiration fluid. Specifically, the system according to the present disclosure can include flow control means such that the second recirculated circulating fluid stream 504 can be completely stopped when desired. It should be noted that in some embodiments, the recirculated circulating fluid (e.g., CO2) provided to the turbine 400 may bypass the heat exchanger 500 before being provided to the turbine. In this regard, the recirculated CO2 may be compressed by the compressor 570, and then a portion of the circulating fluid stream 571 may bypass the heat exchanger 500 and enter the turbine 400. Thereby, the CO2 (or other recirculated circulating fluid) may be introduced into the turbine 400 without being warmed by the heat exchanger 500. Thus, the CO2 (or other recirculated circulating fluid) may be introduced into the turbine at a temperature lower than the temperature of the fluid warmed by the heat exchanger. In this regard, the CO2 (or other recirculated circulating fluid) may be introduced into the turbine at a temperature of less than about 300 °C, less than about 200 °C, less than about 100 °C, less than about 55 °C, or less than about 25 °C, and thus, the CO2 (or other recirculated circulating fluid) may be used to cool the turbine 400. To compensate for adding a relatively lower temperature circulating fluid to the turbine 400, O2 may be moved through the heat exchanger 500 to warm the O2, and then the O2 may be combined with the recirculated circulating fluid 503 induced into the combustor 300 to compensate for the efficiency losses that might otherwise occur.In some embodiments, the circulating fluid exiting the low temperature end of the heat exchanger (or the last heat exchanger in a row when two or more heat exchangers are used) can have a temperature of less than about 200°C, less than about 100°C, less than about 75°C, or less than about 40°C.

[0082] In some embodiments, therefore, it may be useful for the heat exchanger that receives the turbine exhaust stream to be formed from high performance materials designed to withstand extreme conditions. For example, the heat exchanger may include an INCONEL® alloy or similar materials. Preferably, the heat exchanger includes materials that can withstand a consistent operating temperature of at least about 700°C, at least about 900°C, or at least about 1,200°C. It may also be useful for one or more of the heat exchangers to include materials that provide good chemical resistance to secondary materials of the type that may be present in the combustion product stream. INCONEL® alloys are available from Special Metals Corporation, and some embodiments can include austenitic nickel-chromium-based alloys. Suitable heat exchangers can include heat exchangers available under the trademark HEATRIC® (available from Meggitt USA, Houston, Texas).

[0083] As described above, in addition to water, the CO2 circulation fluid may contain other secondary components such as fuel-derived, combustion-derived, and oxygen-derived impurities. These secondary components of the CO2 circulation fluid (often recognized as impurities or contaminants) can be removed entirely from the CO2 circulation fluid being cooled using appropriate methods (e.g., the methods defined in U.S. Patent Application Publication No. 2008 / 0226515, European Patent Application Nos. EP1952874 and EP1953486, which are hereby incorporated by reference in their entirety). For example, SO2 and SO3 can be converted to sulfuric acid at 100%, while >95% of NO and NO2 can be converted to nitric acid. Any excess O2 present in the CO2 circulation fluid can be separated as an enrichment stream for optional recirculation to the combustor. Any inert gases present (e.g., N2 and Ar) can be vented to the atmosphere at low pressure.

[0084] As described above, a power generation cycle incorporating a turbine configured in accordance with the present disclosure can operate with a certain degree of efficiency because the combustion product stream (e.g., resulting from the combustion of a solid fuel such as coal) can be directly introduced into the turbine without first removing particulate matter present in the combustion product stream with a filter. In particular, the inventive turbine configuration eliminates or greatly reduces blade erosion resulting from the impact of unburned material. Despite providing such valuable protection of the turbine materials, there may still be a chance of turbine failure resulting from the interaction between the turbine components and the particulate components of the combustion product stream.

[0085] For example, liquid ash deposition and freezing (or solidification) on turbine blades can cause slugging, loss of efficiency, and / or loss of rotor balance. Thus, in some embodiments, the present disclosure provides for the incorporation of specific components into the combustion cycle to reduce and / or at least partially remove deposits or chemical depositions from turbine components, particularly turbine blades. Although ash deposition is exemplified herein, it is understood that the cleaning provided by some embodiments of the present disclosure will be effective to at least partially remove or completely remove any type of deposition on turbine components resulting from substances present in the combustion product stream, particularly particulate matter. Thus, various types of ash, ash-derived substances, and carbon may be removed by the cleaning provided herein.

[0086] Accumulation of chemical deposits on turbine components such as turbine blades may be prevented by using transpiration protection techniques. For example, as seen in FIG. 1, a hot recycled working fluid (e.g., CO2) can be withdrawn as stream 504 from the hot end of heat exchanger 500 and delivered to turbine 400. For example, a hot recycled working fluid can be delivered to the turbine rotor and then through the turbine blades to provide transpiration protection of the turbine blades. In such embodiments, the turbine blades can be perforated as needed such that the hot recycled working fluid exits the blade along at least the front face of the blade where the hot recycled working fluid is substantially within the direct path of the combustion product stream entering the turbine across the entire surface of the blade. In a specific embodiment, the greatest flow of transpiration fluid out of the blade will be at the leading edge of the blade.

[0087] The transpiration fluid may be provided at various temperatures. In some embodiments, the transpiration fluid for the turbine may be at a temperature within about 10%, within about 8%, within about 5%, or within about 2% of the temperature of the combustion product stream entering the turbine. In such embodiments, the temperature of the transpiration fluid for the turbine may be characterized as being substantially similar to the temperature of the combustion product stream entering the turbine. In other embodiments, the transpiration fluid introduced into the turbine for transpiration protection may be at a temperature of from 15% to less than about 90%, from 15% to less than about 60%, from 15% to less than about 50%, or from about 20% to less than about 40% of the temperature of the combustion product stream entering the turbine. In such embodiments, the temperature of the transpiration fluid for the turbine may be characterized as being substantially lower than the temperature of the combustion product stream entering the turbine.

[0088] In some embodiments, the use of the transpiration fluid in conjunction with the turbine blades can serve multiple functions. For example, the transpiration fluid can be effective in protecting the turbine blades because it can essentially prevent particulate matter in the combustion product stream from actually contacting the blade surfaces. Rather, the protective barrier formed by the transpiration fluid can deflect or otherwise re-direct particulate matter around the turbine blades. The hot recirculated working fluid can also function to heat the blades, particularly the blade surfaces on the exit side of the turbine. This additional heating can prevent the exit side and / or the inlet side blade surfaces from cooling to the temperature at which liquid ash (or other substances that are liquid at the temperature of the combustion product stream and have a freezing (or solidification) point that is lower than the temperature of the combustion product stream but higher than ambient temperature) will solidify. This prevents liquid particles that actually contact the surface of the turbine blades from freezing (or solidifying) and thus depositing on the blade surfaces.

[0089] In some embodiments, transpiration protection can eliminate the freezing (or solidification) of particles. In this regard, all ash may remain molten in some embodiments at temperatures above approximately 870°C to 980°C. In other embodiments, the freezing of particles can be reduced for the same cycles and systems that do not incorporate transpiration protection. Periodic cleaning of turbine components may be necessary to the extent that the freezing of particles is reduced but not eliminated. In specific embodiments, the cleaning of turbine components such as turbine blades may be effected through the incorporation of cleaning components into the combustion cycle or system.

[0090] The cycle shown in FIG. 2 illustrates a system that can direct a turbine blade cleaning substance through a turbine to effect cleaning of the turbine blades. Advantageously, the cleaning substance may be directed through the turbine in parallel with the combustion product stream. Thus, cleaning can be effected without interrupting the power generation combustion cycle. In some embodiments, it may be desirable to change one or more of the cycle parameters described herein to facilitate the cleaning process (e.g., to change the temperature of the combustion product stream, to increase the ratio of recirculated fluid to fuel, etc.). In some embodiments where the turbine blades are transpiration protected, it may be desirable to stop the flow of the transpiration fluid to facilitate contact between the cleaning substance and the turbine blades. However, combustion and power generation may continue during the cleaning process. With respect to FIG. 1. In this embodiment, however, a third recirculated cycle fluid stream 506 can exit the heat exchanger 500 and pass through a cleaning substance confluence 600, where the cleaning substance is combined with the third recirculated cycle fluid stream 506 to produce a cleaning substance stream 610. The cleaning substance confluence 600 can include any structure, unit, or device suitable for combining the third recirculated cycle fluid stream 506 with the cleaning substance, and the cleaning substance can be provided in a continuous flow or in a batch mode. Preferably, the cleaning substance confluence is configured such that the cleaning substance combines with and flows with the third recirculated cycle fluid stream 506. As also described above with respect to the second recirculated cycle fluid stream 504, the third recirculated cycle fluid stream 506 can be controlled to have a flow rate of zero or to have any flow rate necessary to effectively transport the cleaning substance to the turbine.

[0091] The cleaning substance can be any substance that contacts the surface of the turbine blade and is effective in physically or chemically removing solid deposits therefrom. Preferably, the cleaning substance includes a substance effective in removing deposits without erosion or with minimal erosion of the blade surface itself. The solid cleaning substance may include carbon particles, alumina particles, or other hard particles configured not to dissolve at the temperature of the flow. Since ash may define a lower fracture stress than the blade, ash erosion rather than blade erosion may occur at low impact velocities. The liquid cleaning substance may include a potassium compound such as potassium oxide, potassium carbonate, or potassium hydroxide. The potassium compound may act as a flux to lower the melting point of the ash since the ash may be capable of melting the blade. The gaseous cleaning substance may include oxygen capable of oxidizing deposits such as carbon. The solid or liquid cleaning substance combined with the third recirculated circulating fluid stream 506 at the cleaning substance junction 600 may define less than about 0.5%, less than about 0.1%, or less than about 0.01% of the total mass flow rate of the cleaning substance stream 610, and from about 0.001% to about 0.1%, from about 0.1% to about 1%, or from about 0.0001% to about 0.01% of the total mass flow rate of the cleaning substance stream. The gaseous cleaning substance combined with the third recirculated circulating fluid stream 506 at the cleaning substance junction 600 may define less than about 5%, less than about 2%, or less than about 1% of the total mass flow rate of the cleaning substance stream 610, and from about 0.1% to about 2%, from about 0.01% to about 1%, or from about 0.01% to about 5% of the total mass flow rate of the cleaning substance stream. In one embodiment, the cleaning cycle may be initiated at any time when the power output by the generator 400a drops to about 2% - about 5%, about 5% - about 10%, or about 1% - about 2%. For example, the cleaning operation may be performed about once a week to once every three years. The cleaning cycle may last from about 5 minutes to about 1 hour in some embodiments.

[0092] The cleaning substance stream 610 may flow directly into the turbine 400. In such embodiments, the cleaning substance stream may be mixed with the combustion product stream 320 at a common inlet to the turbine 400, or the cleaning substance stream 610 and the combustion product stream 320 may have individual inlets to the turbine such that the streams are mixed at a point inside the turbine 400. In the illustrated embodiment, the cleaning substance stream 610 is first mixed with the combustion product stream 320 at the flow combiner switch 650. Thus, in the cleaning cycle, the combined combustion product and cleaning substance stream 326 exits the flow combiner switch 650 and enters the turbine 400.

[0093] In some embodiments, continuous cleaning may be used, in which case some minimal flow of the third recirculated circulating fluid stream 506 can be maintained so that an amount of cleaning substance is continuously introduced into the turbine. The flow of the third recirculated circulating fluid stream 506 may be periodically adjusted up or down to increase or decrease the cleaning ability of the cycle. In other embodiments, the third recirculated circulating fluid stream 506 can be closed so that there is no passage of cleaning substance from the cleaning substance confluence 600 to the flow combiner switch 650. In this mode of operation, the combustion product stream 320 may bypass the flow combiner switch 650 and flow directly to the turbine, as illustrated in FIG. 1. Alternatively, the combustion product stream 320 may continue to flow through the combiner switch 650, but in the absence of the incoming cleaning substance stream 610, the stream exiting the combiner switch 650 will be essentially the combustion product stream 320 rather than the combined combustion product and cleaning substance stream 326.

[0094] In some embodiments where the cleaning cycle is active, deposits or residues from the turbine blades can be removed from the cycle through filter 5 in the manner described in relation to FIG. 1. Similarly, when solid cleaning substances are used, the solid cleaning substances can be removed from the cycle through filter 5. In some embodiments, filter 5 may be a multi-unit filter, where the first filter medium or unit is used during the normal course of the combustion cycle, and the second filter medium or unit can be used during the cleaning cycle to collect the cleaning substances and the removed blade deposits without unduly fouling the filters used in the normal combustion cycle. The inventive system may be able to incorporate suitable devices to facilitate such switching between filters.

[0095] Exemplary embodiments Here, without intending to limit the present disclosure, rather provided to illustrate exemplary embodiments, the present disclosure will be described with specific reference to the following examples.

[0096] Figure 3 illustrates an exemplary embodiment of a combustor 1000 that may be used in accordance with the systems and methods disclosed herein. The combustor 1000 may define a combustion chamber 1002 into which fuel and O2 are induced through a fuel inlet 1004 and an O2 inlet 1006. Thus, the fuel may combust to produce a combustion product stream 1008. The combustor 1000 may include a casing that includes an outer casing 1010 and an inner casing 1012. The inner casing 1012 may receive a transpiration fluid 1014 and include a transpiration material, such as a porous sintered material (e.g., a porous sintered metal material), configured to emit the fluid therethrough to define a transpiration layer 1016 configured to reduce heat incident on the casing. The transpiration fluid 1014 may, in some embodiments, be received through an inlet 1026, although in some embodiments the transpiration fluid may be received from a turbine attached to the combustor, as described below. Thus, the combustor 1000 may be configured to withstand the heat generated within the combustion chamber 1002 without using expensive heat-resistant materials such as superalloys, and / or the combustor may operate at increased combustion temperatures.

[0097] As described above, the combustion product stream generated by the combustor may be used to drive a turbine. In this regard, FIG. 4 illustrates an exemplary embodiment of a turbine 2000. In one embodiment, the turbine 2000 may include an inlet duct 2002 configured to connect to the outlet of a combustor (e.g., combustor 1000) and direct a combustion product stream (e.g., combustion product stream 1008) to the inlet of the turbine casing 2004. The turbine 2000 may include a rotor 2006 to which a plurality of blades 2008 are attached. The rotor 2006 may include an annular diverter 2010 configured to divert the combustion product stream around the rotor. Thus, the combustion product stream 1008 expands as it moves through the turbine 2000, rotating the blades 2008, the rotor 2006, and the power shaft 2011 (which may be integral with or coupled to the rotor) before the turbine exhaust stream 2012 is exhausted through one or more outlets 2014. Thus, the turbine 2000 may drive a generator or other device.

[0098] 4, the inlet conduit 2002 may comprise an inner casing 2016 and an outer casing 2018. Additionally, the casing 2004 of the turbine 2000 may comprise an inner casing 2020 and an outer casing 2022. A transpiration fluid 2024 may be directed from an inlet 2026 through the inlet conduit 2002 and between the inner casings 2016, 2020 and the outer casings 2018, 2022 of the turbine 2000. The inner casings 2016, 2020 may include a transpiration material, such as a porous sintered material (e.g., a porous sintered metal material) configured to receive the transpiration fluid 2024 and transpire the fluid therethrough. This may define a transpiration layer 2028 between the combustion product stream 1008 and the inner surface of the inlet conduit 2002, and a transpiration layer 2030 between the blades 2008 and the inner surface of the inner casing 2020, which may be cooled or otherwise protected by the transpiration fluid 2024. In some embodiments, the transpiration fluid provided to the turbine may also be provided to the combustor for transpiration cooling. In this regard, for example, the inlet conduit may be mated to the combustor such that transpiration fluid is provided thereto in some embodiments. However, the transpiration fluid provided to the combustor may additionally or alternatively be provided from a separate inlet 1026 in some embodiments.

[0099] Furthermore, the transpiration fluid 2024 may also be introduced into the turbine 2000 through a second inlet 2032 that may be defined within the power shaft 2011 in some embodiments. Thus, the transpiration fluid 2024 may move through the power shaft 2011 and into the rotor 2006. The rotor 2006 and / or the blade 2008 may include a transpiration material such as a porous sintered material (e.g., a porous sintered metal material) configured to receive the transpiration fluid 2024 and dissipate fluid through its outer surface. Thus, the rotor 2006 and / or the blade 2008 may be cooled by the transpiration fluid 2024 or otherwise protected from the combustion product stream 1008 and particulates therein.

[0100] Figures 5 and 6 illustrate alternative embodiments of the turbine 2000'. As illustrated, a plurality of combustors 1000' may be configured to drive the turbine 2000'. In particular, the combustors 2000' may be arranged radially with respect to a spindle defined by the rotor 2006' as illustrated in FIG. 6. As shown in FIG. 5, the turbine 2000' may be substantially similar to the embodiment of the turbine 2000 illustrated in FIG. 4 except that the combustors 1000' may supply the combustion product stream 1008' around the periphery of the rotor 2006'. Thus, an annular diverter may not be required to divert the combustion product stream 1008' around the rotor 2006'. Each of the combustors 1000' may be substantially similar to the combustor 1000 described above except for the position of the combustor around the rotor 2006'.

[0101] FIG. 7 illustrates a transverse cross-sectional view of one embodiment of a turbine blade 2008A that may be used in the turbine disclosed herein. The turbine blade 2008A may include an outer layer 3002 and a core 3004. The core 3004 may define a relatively strong metal or other material configured as a reinforcing member. As used herein, a strong metal refers to a metal that has a strength of greater than about 10,000 PSI, greater than about 20,000 PSI, or greater than about 30,000 PSI at an appropriate high temperature and is chemically durable at an appropriate temperature. Examples include stainless steel alloys and high-nickel alloys, such as Inconel. Thus, the present disclosure allows for lower-cost alloys, such as stainless steels (e.g., 316 stainless steel) or other alloys with lower nickel and cobalt contents, to be used in place of typical superalloys, which have relatively high nickel and cobalt contents and are therefore very expensive. In this regard, polycrystalline 316 stainless steel can be as much as 20 times cheaper per pound than polycrystalline superalloys and 2000 times cheaper per pound than single crystal superalloy blades.

[0102] Furthermore, the core 3004 may define one or more channels 3006. The channels 3006 may be configured to receive a transpiration fluid and direct the transpiration fluid into the outer layer 3002. The outer layer 3002 may, in some embodiments, define a part or all of the outer surface 3008 of the blade 2008A. Further, the outer layer 3002 may include a porous material such as a porous sintered metal material. Thus, the channels 3006 in the core 3004 may be configured to receive a transpiration fluid and direct the transpiration fluid into the outer layer 3002. Thus, the transpiration fluid may flow through the outer layer 3002 of the turbine blade 2008A to provide a transpiration layer around the outer surface 3008 of the turbine blade that may protect the turbine blade from collisions with heat and / or particulates. In this regard, the turbine blades and / or other components of the systems disclosed herein may be transpiration protected, which is to be understood to mean that a transpiration fluid is directed to at least a part of its surface regardless of whether the transpiration cools the component. For example, the component may be transpiration protected by a transpiration fluid that protects the surface of the component from collisions with particulates or other substances regardless of the temperature of the transpiration fluid. Conversely, the component may be additionally or alternatively transpiration protected by a transpiration fluid that acts as a barrier to cool the component or reduce heating of the component.

[0103] As described above, the transpiration fluid may be used additionally or alternatively in connection with other components associated with the systems and assemblies described herein. In this regard, FIG. 8 illustrates a partial cross-sectional view of an inlet conduit 2002A configured to deliver a combustion product stream from a combustor to a turbine. The inlet conduit 2002A may include an inner layer 4002 and an outer layer 4004. The outer layer 4004 may include a shell, which may include a strong metal as described above configured to provide strength to the inlet conduit 2002A. Further, the outer layer 4004 may define one or more channels 4006. The channels 4006 may be configured to receive a transpiration fluid and to direct the transpiration fluid into the inner layer 4002. The inner layer 4002 may, in some embodiments, define a portion or all of the inner surface 4008 of the inlet conduit 2002A. Further, the inner layer 4002 may include a porous material such as a porous sintered metal material. Thus, the channels 4006 in the outer layer 4004 may be configured to receive a transpiration fluid and to direct the transpiration fluid into the inner layer 4002. Thus, the transpiration fluid may flow through the inner layer 4002 of the inlet conduit 2002A, providing a transpiration layer to protect the inlet conduit from collisions with heat and / or particulates at the inner surface 4008 of the inlet conduit.

[0104] As illustrated in FIG. 9, in one embodiment of the inlet conduit 2002B, a thermal insulation layer 4010 and a second outer layer 4012 may be additionally provided. The thermal insulation layer 4010 and the second outer layer 4012 may, in some embodiments, surround the inner layer 4002 and the outer layer 4004. The thermal insulation layer 4010 may insulate the inlet conduit 2002B to retain more heat therein, which may increase the efficiency of the system being used. Further, the second outer layer 4012 may provide additional strength to the inlet conduit 2002B. However, the various material layers and functional portions described above may be used additionally or alternatively in connection with other components of the systems and assemblies described herein, such as a combustor.

[0105] 10 illustrates a longitudinal cross-sectional view of a turbine blade 2008B according to an alternative embodiment. The turbine blade 2008B may include one or more reinforcing members, such as one or more rods 5014. The rods 5014 may comprise a metallic or other material configured to provide strength to the turbine blade 2008B.

[0106] The blade 2008B may further define one or more channels 5006. The channels 5006 may be configured to receive and direct a transpiration fluid through the material defining the blade 2008B. In this regard, the blade 2008B may include a porous material, such as a porous sintered metal material. Accordingly, the channels 5006 in the blade 2008B may be configured to receive and direct a transpiration fluid through the blade to provide a transpiration layer on the outer surface 5008 of the blade that may protect the blade from heat and / or particulate impingement.

[0107] In some embodiments, the blade 2008B may be configured to define a greater flow of transpiration fluid at the leading edge 5016 of the blade than at the trailing edge 5018 of the blade. This may provide greater protection for the leading edge, which may be desirable because the leading edge may otherwise be more prone to particle impact than the remainder of the blade. In this regard, one or more channels 5006 in the blade 2008B may define a greater transpiration fluid inlet area at the leading edge 5016 (e.g., see channel 5006A) than the transpiration fluid inlet area of one or more channels at the trailing edge 5018 (e.g., see channel 5006B). Alternatively, a greater number of channels may be defined at the leading edge than at the trailing edge.

[0108] Figures 11 to 13 illustrate alternative embodiments of the turbine blade 2008C. As illustrated, the turbine blade 2008C may define a one-piece structure with one or more internal ribs 6020. The internal ribs 6020 may function as reinforcing members configured to provide strength to the turbine blade 2008C. The internal ribs 6020 may be integrally formed with the outer layer 6002 and / or the base member 6022 of the turbine blade 2008C.

[0109] The turbine blade 2008C may include one or more channels 6006 that may be separated by the internal ribs 6020. The channels 6006 may be configured to receive transpiration fluid (e.g., from a rotor to which the base member 6022 is attached) and to direct the transpiration fluid through the outer layer 6002. In this regard, the turbine blade 2008C may include a porous material such as a porous sintered metal material. Thus, the channels 6006 in the turbine blade 2008C may be configured to receive transpiration fluid and to direct the transpiration fluid through the outer layer 6002 of the turbine blade to provide a transpiration layer that may protect the turbine blade from collisions with heat and / or particulates. As further illustrated, the channels 6006 in the turbine blade 2008C may define a transpiration fluid inlet area at the leading edge 6016 (e.g., see channel 6006A) that is larger than the transpiration fluid inlet area of one or more channels at the trailing edge 6018 (e.g., see channel 6006B). Thus, in some embodiments, the turbine blade 2008C may be configured to define a flow of transpiration fluid at the leading edge 6016 of the turbine blade that is greater than the flow of transpiration fluid at the trailing edge 6018 of the turbine blade.

[0110] FIG. 14 illustrates a cross-sectional view in the lateral direction of an additional embodiment of the turbine blade 2008D. As illustrated, the turbine blade 2008D may include an outer layer 7002 that defines a wall thickness at the trailing edge 7018 that is greater than the wall thickness at the leading edge 7016. In this regard, the turbine blade 2008D may include a porous material such as a porous sintered metal material. Thus, the transpiration fluid may be induced through the turbine blade 2008D to move through the outer layer 7002 to provide a transpiration layer on the outer surface 7008 of the turbine blade that may protect the turbine blade from collisions with heat and / or particulates. Since the wall thickness of the outer layer 7002 is greater at the trailing edge 7018 than at the leading edge 7016, the turbine blade 2008D may define a flow of transpiration fluid at the leading edge that is greater than the flow of transpiration fluid at the trailing edge.

[0111] Furthermore, the turbine blades according to the various embodiments disclosed herein may define a porosity that varies between the root and the tip of the turbine blade (e.g., see the root 6026 and the tip 6028 of the turbine blade 2008C illustrated in FIG. 13). In this regard, in some embodiments, the turbine blades disclosed herein may be configured to define a flow of transpiration fluid at the tip of the turbine blade that is greater than the flow of transpiration fluid at the root of the turbine blade. This may provide additional protection to the turbine blade, which may be desirable since the tip of the turbine blade moves at a higher velocity than any other point on the turbine blade.

[0112] For example, FIG. 15A schematically illustrates a longitudinal cross-section of a turbine blade 2008E. As illustrated, the turbine blade 2008E defines different porosities between a root 8026 and a tip 8028. In particular, the turbine blade 2008E is more porous at the tip 8028 than at the root 8026 such that a relatively greater amount of transpiration fluid may flow out of the tip of the turbine blade rather than the root of the turbine blade. In this regard, the turbine blade 2008E may include a porous material such as a porous sintered metal material configured to dissipate transpiration fluid therethrough as described above. As illustrated, in some embodiments, the porous material may define a plurality of layers 8030A-D, in which case the porosity of the layers increases from the root to the tip. The layers 8030A-D may be defined by different materials or the same material sintered to varying degrees, and thus, their porosity varies. In some embodiments, the layers may be laminated together, but the layers may be attached in various other ways.

[0113] In another embodiment, as illustrated in FIG. 15B, the turbine blade 2008E' defines different porosities between a root 8026' and a tip 8028' as described above with respect to FIG. 15B. However, as illustrated, in some embodiments, the porous material may define a porosity gradient, for example, the porosity of the material increases from 8026' to the tip 8028'. In this regard, the porosity of the material may vary at various locations in some embodiments without the presence of separate layers defining different porosities.

[0114] Various other configurations regarding the turbine blade may be used. For example, in some embodiments, the turbine blade may be configured to define a transpiration fluid flow at the leading edge that is substantially equal to or less than the transpiration fluid flow at the trailing edge of the turbine blade. Further, in some embodiments, the turbine blade may be configured to define a transpiration fluid flow at the tip that is substantially equal to or less than the transpiration fluid flow at the root of the turbine blade. Further, the change in porosity between the leading edge and the trailing edge may also be used to control the flow of transpiration fluid out of the blade in a manner similar to that described for controlling the transpiration flow between the root and the tip.

[0115] Thus, for example, the porosity of the material defining the turbine blade (or other component) may increase between the root and the tip, decrease between the root and the tip, be relatively higher or lower centrally with respect to the outer portion of the blade, increase or decrease from the leading edge to the trailing edge, and so on. The porosity gradient or porosity layer may increase or decrease from about 10% porosity to about 90% porosity, from about 25% porosity to about 75% porosity, or from about 1% porosity to about 25% porosity.

[0116] Accordingly, the transpiration fluid may be configured to cool and / or otherwise protect the various components of the systems and assemblies disclosed herein. In this regard, FIG. 16 illustrates a calculated trajectory 900 for 100 μm ash particles 902 relative to the outer surface 904 of turbine blade 906. The ash particle trajectory 900 is modeled based on ash particles 902 that initially move at 75 m / sec towards turbine blade 906 along with a flow 908 of CO2 transpiration fluid that diverges at 2 m / sec from the outer surface 904 of the turbine blade. The circulating fluid within the turbine may be at 300 bar (30 MPa) and 700° C. As illustrated, the transpiration fluid 908 prevents the ash particles 902 from contacting the turbine blade 906. In particular, the ash particles 902 are calculated to come to within about 0.2 mm of the outer surface 904 of the turbine blade. Accordingly, erosion of the turbine blade 906 may be avoided.

[0117] Similarly, FIG. 17 illustrates an example according to the present disclosure of a calculated particle trajectory 1000 for 50 μm ash particles 1002 relative to the inner surface 1004 of combustor 1006. The ash particle trajectory 1000 is modeled based on ash particles 1002 that initially move at 50 m / sec perpendicular to the inner surface 1004 of combustor 1006 at an axial flow velocity of combustion gas of about 3 meters per second, a combustion gas composition of CO2 in excess of about 90%, a combustion gas temperature of about 1,500° C., a pressure of about 300 bar (30 MPa), and a radial transpiration flow rate of transpiration fluid 1008 of about 1 meter per second in the radial direction (e.g., perpendicular to the axial flow of combustion gas). As illustrated, the transpiration fluid 1008 prevents the ash particles 1002 from contacting the inner surface 1004 of the combustor 1006. The ash particles 1002 are calculated to come to within about 0.2 mm of the inner surface 1004 of the combustor 1006. Accordingly, erosion of the inner surface 1004 of the combustor 1006 may be avoided.

[0118] Table 1 below provides various parameters regarding the operation of a conventional power plant natural gas turbine. A cross-section of such a typical turbine 1100 is shown in FIG. 18. For comparison, Table 2 below provides the same parameters regarding the operation of the high-pressure low-speed turbine according to the present disclosure. A cross-section of an exemplary turbine 1200 according to the present disclosure is shown in FIG. 19. As can perhaps be seen by comparing the conventional turbine 1100 with the turbine 1200 of the present disclosure, the turbine of the present disclosure may define a relatively smaller diameter in some embodiments due to the use of relatively shorter turbine blades 2008F compared to the turbine blades 1108 of the conventional turbine. In this regard, as shown in the tables below, the turbine blades 2008F of the turbine 1200 of the present disclosure may define a relatively smaller average inner radius (i.e., from the center 2006F of the rotor to the root of the turbine blade), average outer radius (i.e., from the center of the rotor to the tip of the turbine blade), and average radius (the average of the inner and outer radii) compared to the turbine blades 1108 of the conventional turbine 1100 in some embodiments. Also, the turbine 1200 of the present disclosure may define a relatively larger length-to-diameter ratio compared to the conventional turbine 1100. Further, the turbine 1200 of the present disclosure may include a relatively larger number of turbine blades 2008F than the conventional turbine 1100. Additionally, the diameter of the rotor 2006F of the turbine 1200 of the present disclosure may be smaller than the diameter of the rotor 1106 of the conventional turbine 1100. [Table 1] [Table 2]

[0119] Those skilled in the art to which the present disclosure pertains, having the benefit of the teachings presented in the foregoing description, will readily conceive of many modifications and other embodiments of the present disclosure described herein. Accordingly, it is to be understood that the present disclosure is not limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A turbine assembly, comprising: a casing that is in fluid communication with a combustor and defines an inlet configured to receive a combustion product stream; a plurality of blades each extending radially outward from a root to a tip; The turbine assembly, wherein the flow velocity of the combustion product stream is measured downstream of the combustor and proximate to the inlet of the turbine assembly.

2. The turbine assembly according to claim 1, wherein the blade height of the plurality of blades is less than 0.275 m.

3. The turbine assembly according to claim 1, wherein the turbine assembly comprises less than 2,000 of the plurality of blades.

4. The turbine assembly according to claim 1, having an overall length of less than 11 m.

5. The turbine assembly according to claim 4, wherein the overall length is in the range of 6 m to 10 m.

6. The turbine assembly according to claim 1, wherein the average turbine diameter is in the range of 0.25 m to 3 m.

7. The turbine assembly according to claim 1, wherein the average blade radius is less than 1.2 m.

8. The turbine assembly according to claim 1, wherein the flow velocity of the combustion product stream is less than 400 mph.

9. The flow density of the combustion product stream is at least 100 kg / m ３ The turbine assembly according to claim 1, wherein the flow density is at least 100 kg / m

10. The turbine assembly according to claim 1, further comprising an outlet of the casing for discharging a turbine exhaust stream and a rotor disposed within the casing.

11. The turbine assembly according to claim 1, wherein the blade speed at the tip is in the range of 20 m / s to 340 m / s.

12. The turbine assembly according to claim 1, wherein the turbine inlet pressure is at least 100 bar.

13. The turbine assembly according to claim 12, wherein the turbine inlet pressure is in the range of 100 bar to 450 bar.

14. The turbine assembly according to claim 1, wherein the turbine outlet pressure is at least 10 bar.

15. The turbine assembly according to claim 14, wherein the turbine outlet pressure is in the range of 10 bar to 50 bar.

16. The turbine assembly according to claim 1, wherein the ratio of the turbine inlet pressure to the turbine outlet pressure is at least 6.

17. The turbine assembly according to claim 16, wherein the ratio is in the range of 6 to 15.

18. The high temperature for high-temperature combustion related to the combustor is at least 1,000 °C, and the turbine assembly according to claim 1.

19. The high temperature is in the range from 1,200 °C to 3,000 °C, and the turbine assembly according to claim 18.

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