Patent Application
20160281604
The present application relates generally to gas turbine engines and more particularly relates to a turbine engine with an integrated heat recovery and cooling cycle system for electric power production and efficient operation of the turbine engine in increased ambient temperature environments.
The overall efficiency and the power output of a gas turbine engine typically suffer during operation in increased ambient temperature environments. As an example, the LMS100 gas turbine engine offered by General Electric Company of Schenectady, N.Y. is one of the most efficient gas turbine engines on the market and is often installed in a simple-cycle configuration without a bottoming cycle. The high efficiency of the LMS 100 is due to a compressor intercooler and a high turbine pressure ratio with low exhaust temperature. As with all gas turbine engines, performance of the LMS100 in increased ambient temperature environments may suffer without use of a cooling cycle, such as one providing inlet chilling and sufficiently low intercooler temperature. To provide such cooling, individual, non-integrated (electrically-driven vapor compression or absorption cycle inlet chillers and cooling towers may be included. The addition of these cooling components often results in a periphery of the engine that is large, costly and consumes parasitic power and vast quantities of water.
Alternative combined cycle gas turbine engines may include thermodynamic bottoming cycles to generate electricity from waste heat, such as steam or duel-reheat CO2 bottoming cycles. Similar to the simple-cycle configuration of the LMS 100, CO2 bottoming cycles may also suffer in performance in increased ambient temperature environments. CO2 bottoming cycles may not have efficient provisions for compression and low-side pressure control in hot ambient conditions. Bottoming cycles typically do not integrate intercooling or inlet chilling. Adding individual, non-integrated standard (steam) bottoming cycles with (electric) inlet chilling does not take advantage of synergies or remove inlet chiller auxiliaries, and results in added cost and overall system complexity.
There is thus a desire for an improved heat recovery and cooling cycle system for use with a gas turbine engine. Preferably such an improved heat recovery and cooling cycle system may provide multiple functions and advantages in an integrated system that is able to be efficiently operated in increased ambient temperature environments.
These and other shortcomings of the prior art are addressed by the present disclosure, which provides a power generation system.
In accordance with an embodiment shown or described herein, provided is a power generation system comprising an integrated waste heat recovery and cooling cycle system, a condenser and a working fluid accumulator. The integrated waste heat recovery and cooling cycle system comprising a heat-to-power portion and an inlet cooling portion in fluid communication with the heat-to-power portion. The heat-to-power portion comprising a two-stage intercooled pump/compressor, one or more recuperators configured to receive a portion of a flow of working fluid, an exhaust heat recovery unit configured to receive the flow of working fluid and an expander disposed downstream of the exhaust heat recovery unit. The inlet cooling portion comprising a chiller expander, a chiller compressor coupled to the chiller expander, a motor coupled to the chiller compressor and an inlet air heat exchanger in fluid communication with, and intermediately positioned therebetween, the chiller expander and the chiller compressor. The inlet cooling portion is configured to receive a portion of the flow of working fluid. The condenser is in fluid communication with the heat-to-power portion and the inlet cooling portion. The working fluid accumulator is in fluid communication with the heat-to-power portion and the inlet cooling portion and configured to maintain a desired volume and pressure of the flow of working fluid in the integrated heat recovery and cooling cycle system.
In accordance with another embodiment shown or described herein, provided is a power generation system. The power generation system comprising a heat-to-power portion defining a first portion of a working fluid circulation loop and an inlet cooling portion defining a second portion of a working fluid circulation loop. The heat-to-power portion comprising a two-stage intercooled pump/compressor, a low temperature heat source, one or more recuperators, an exhaust heat recovery unit, and an expander. The low temperature heat source is configured to receive a first portion of a flow of working fluid from the two-stage intercooled pump/compressor. The working fluid comprises CO2. The one or more recuperators are configured in parallel with the low temperature heat source to receive a second portion of the flow of working fluid. The exhaust heat recovery unit is disposed downstream of the low-temperature heat source and the one or more recuperators and configured to receive a combined flow of working fluid. The expander is disposed downstream of the exhaust heat recovery unit and configured to receive the combined flow of working fluid. The inlet cooling portion comprising a chiller, a chiller compressor, a motor and an inlet air heat exchanger. The chiller compressor is coupled to the chiller expander. The motor is coupled to the chiller compressor. The inlet air heat exchanger is in fluid communication with, and intermediately positioned therebetween, the chiller expander and the chiller compressor. The inlet cooling portion is configured to receive a portion of the flow of working fluid. The system further including a working fluid condenser in fluid communication with the heat-to-power portion and the inlet cooling portion and a working fluid accumulator coupled to the two-stage intercooled pump/compressor and configured to maintain a desired volume and pressure of the working fluid in the system.
In accordance with yet another embodiment shown or described herein, provided is an integrated heat recovery and cooling cycle system for use with a gas turbine engine. The integrated heat recovery and cooling cycle system comprising flow of working fluid, an inlet cooling portion, a heat-to-power portion, a working fluid condenser and an accumulator. The inlet cooling portion comprising a chiller expander, a chiller compressor coupled to the chiller expander, a motor coupled to the chiller compressor and an inlet air heat exchanger in fluid communication with, and intermediately positioned therebetween, the chiller expander and the chiller compressor. The inlet cooling cycle is configured for the passage therethrough of the flow of working fluid. The heat-to-power portion comprising a two-stage intercooled pump/compressor, a low temperature heat source comprising a gas turbine intercooler configured to receive a first portion of the flow of working fluid and one or more recuperators configured in parallel with the low temperature heat source to receive a second portion of the flow of working fluid. The working fluid condenser is in fluid communication with the heat-to-power portion and the inlet cooling portion. The heat-to-power portion and the inlet cooling portion are integrated at the working fluid condenser. The accumulator is in fluid communication with the heat-to-power portion and the inlet cooling portion and configured to maintain a volume and pressure of the flow of working fluid in the integrated heat recovery and cooling cycle system.
In accordance with yet another embodiment shown or described herein, provided is a method of operating an integrated heat recovery and cooling cycle system. The method comprising diverting a portion of a working fluid flow to a heat-to-power portion of the system, compressing/pressurizing the working fluid flow in the heat-to-power portion of the system, and heating the working fluid flow in an exhaust heat recovery unit and one or more recuperators in the heat-to-power portion of the system to provide a heated working fluid flow. The method further comprising driving a load by expanding the heated working fluid flow in the heat-to-power portion of the system, expanding the working fluid flow in the heat-to-power portion of the system, diverting a portion of the working fluid flow to an inlet cooling portion of the system, cooling an inlet air flow by heating the working fluid flow and compressing the working fluid flow.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term such as “about” is not to be limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Similarly, “free” may be used in combination with a term, and may include an insubstantial number, or trace amounts, while still being considered free of the modified term.
As used herein, the terms “may” and “may be” indicate a possibility of an occurrence within a set of circumstances; a possession of a specified property, characteristic or function. These terms may also qualify another verb by expressing one or more of an ability, capability, or possibility associated with the qualified verb. Accordingly, usage of “may” and “may be” indicates that a modified term is apparently appropriate, capable, or suitable for an indicated capacity, function, or usage, while taking into account that in some circumstances the modified term may sometimes not be appropriate, capable, or suitable. For example, in some circumstances, an event or capacity can be expected, while in other circumstances the event or capacity cannot occur—this distinction is captured by the terms “may” and “may be”.
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present invention, the articles “a,” “an,” and “the,” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive, and mean that there may be additional elements other than the listed elements. Furthermore, the terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.
All ranges disclosed herein are inclusive of the endpoints, and the endpoints are combinable with each other. The terms “first,” “second,” and the like as used herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or contradicted by context.
Embodiments of the invention described herein address the noted shortcomings of the state of the art. In accordance with the embodiments discussed herein, an improved turbine engine including an integrated heat recovery and cooling cycle system is described. The system improves increased ambient environment power output and efficiency of the turbine engine through inlet chilling, while providing the generation of additional power. The integration of the heat recovery and cooling cycle system eliminates the need for an intercooler cooling water system, as well as any inlet chiller condenser or absorption cycle. The integrated heat recovery and cooling cycle system uses CO2 as the working fluid for inlet chilling, intercooling and exhaust heat recovery. In an embodiment, the heat recovery and cooling cycle may provide up to 14 MW of net power at 40° C. condenser/cooler temperature, while reducing the inlet temperature from 30° C. to 15° C. and the intercooler-high pressure compressor inlet to ˜45° C. The integrated heat recovery and cooling cycle system, provides cooling and thus increased power in increased ambient temperature environments, and more particularly in an ambient environment of greater than 0° C. During operation at ambient temperatures above 20° C., the heat recovery and cooling cycle system may operate as a Brayton cycle, enabled efficiently through a novel intercooled compression system with low pressure control and accumulator.
The exemplary integrated heat recovery and cooling cycle system as disclosed includes a combined heat-to-power and inlet cooling cycle with CO2 as the working fluid. The system uses waste heat from a turbine engine intercooler, as well as from the exhaust, to generate power in a dual- or triple-expansion configuration with recuperators for preheating. Refrigeration for inlet cooling is provided by a split flow from a condenser/cooler going through an expander, an inlet air heat exchanger (evaporator) and a compressor that can be driven in part by the expander, before returning to the condenser. As used herein, the term “integrated” refers to certain elements of a power generation system that are combined or common to both the heat-to-power cycle and the inlet cooling cycle. As described herein both cycles use a common cooler/condenser, accumulator and control system.
In accordance with the exemplary embodiments of the present disclosure, the cooling, or refrigeration cycle is integrated with the heat-to-power cycle to allow higher efficient operation in increased ambient temperature environments with fewer components and reduced complexity compared to typical bottoming cycles and inlet chilling systems. The heat sources for power generation may include combustion engines, gas turbines, geothermal, solar thermal, industrial heat sources, or the like.
Referring now to the drawings, in which like numerals refer to like elements throughout the several views,
In an embodiment the gas turbine engine 10 may be any number of different gas turbine engines offered by General Electric Company of Schenectady, New York, including, but not limited to, the LMS100, LM 2500, LM6000 aero-derivative gas turbines, E and F-class heavy duty gas turbine engines, and the like. However, the present disclosure is not limited thereto and can be applied to any suitable gas turbine, multiple gas turbine plants and other types of power generation equipment, such as internal combustion engines and/or industrial process equipment. In an embodiment, the gas turbine engine 10 may use natural gas, liquid fuels, various types of syngas, and/or other types of fuel. The gas turbine engine 10 may have different configurations and may use other types of components.
Referring to
As illustrated in
The heat-to-power portion 54 may further include additional heat exchangers, and more particularly an aftercooler 80, a gas turbine intercooler 82 (for the LMS100 for instance), the exhaust heat recovery unit 84 and a high temperature recuperator 86, in addition to a high temperature turbo-expander 88. Prior to reaching the exhaust heat recovery unit 84, a first portion 57 of the flow of working fluid 56 is received by the intercooler 82 and a second portion 58 of the flow of working fluid 56 is received in parallel by the low-temperature recuperator 70. The gas turbine intercooler 82, the exhaust heat recovery unit 84 and the low-temperature recuperator 70 heat the working fluid therein and provide for a heated flow of working fluid 59. The cooling heat exchangers, and more particularly the intercooler 66 and aftercooler 80, may be cooled with air or water in the same manner as the cooler/condenser 78. During operation as a Brayton cycle, the volume and pressure of the working fluid 56 in the system is maintained actively with an accumulator 72 that is connected to an intermediate pressure flow 74 of the two-stage intercooled pump/compressor/motor 62 via a valve 76 and to an outlet of the cooler/condenser 78.
Under increased ambient temperatures no condensation takes place in the cooler/condenser 78 and the heat-to-power portion 54 operates as a Brayton cycle with significantly higher optimum low-side pressure (e.g. from 70 bar at 15° C. to 90 bar at 30° C.).
As previously indicated, the integrated heat recovery and cooling cycle system 50 includes one or more recuperators, and more particularly, the low temperature recuperator 70 and the high temperature recuperator 86. The recuperators 70, 86 may be used to pre-cool the flow of working fluid (CO2) 56 before the cooler/condenser 78 and recycle the heat. The recuperators 70, 86 may be in communication with the flow of pressurized working fluid 56 from the high-pressure pump/compressor 68 and the turbo-expanders 60 and 88. The turbo-expanders 60 and 88 may be radial inflow and/or axial turbines, or the like. The turbo-expanders 60 and 88 may drive an expander shaft 90. The expander shaft 90 may drive a load, such as an additional generator 92, and the like. Although the low-temperature turbo-expander 60 and high-temperature turbo-expander 88 are shown on the same shaft 90 with the additional generator 92, individual shafts and generators are anticipated by this disclosure. Other components and other configurations also may be used herein.
For gas turbine inlet cooling, an inlet air heat exchanger (evaporator), 94 is included. The inlet air heat exchanger (evaporator) 94 may be intermediately positioned between a chiller expander 96 and a chiller compressor 98 coupled to a motor 100. Refrigeration for inlet cooling is provided by a portion of the flow of the working fluid 56 from the cooler/condenser 78 going through the chiller expander 96, the inlet air heat exchanger (evaporator) 94 and the chiller compressor 98 that is driven in part by the chiller expander 96, before returning to the cooler/condenser 78. In alternate embodiments, individual compressor, motor, expander and generator units are anticipated for the chiller cycle in lieu of the combined unit shown.
Operation of the integrated heat recovery and cooling cycle system 50 may be controlled by a controller 100. The heat recovery and cooling cycle system controller 100 may be in communication with the overall controller of the gas turbine engine 10 and the like. The heat recovery and cooling cycle system controller 100 may be a rules based controller that controls the flow rate of the working fluid 56 through the inlet cooling heat exchanger 94 by diverting a portion of the flow of working fluid (CO2) 56 from the cooler/condenser 78 as long as net power or efficiency increment for the overall system is positive The heat recovery and cooling cycle system controller 100 integrates the performance of all of the equipment including the gas turbine engine and the operational parameters for efficient use of the fuel and/or for maximum total power output through inlet chilling for operation in increased ambient temperature environments. Other types of rules and operational parameters may be used herein.
Other heat sources such as industrial waste heat, solar and/or geothermal heating of the flow of working fluid (CO2) 56 may also be incorporated herein. Other types of heating and/or cooling also may be performed herein.
The overall integration of the integrated heat recovery and cooling cycle system 50 and the turbine components herein provides a more cost effective approach in maximizing output in increased ambient temperature environments as compared to separate bottoming cycle systems and heating and/or chilling systems. The rules based controller 100 may optimize the various heating and cooling flows for any given set of ambient conditions, load demands, fuel costs, water costs, and overall equipment configurations and operational parameters for efficient and economical use of the waste heat produced herein.
It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.
Although, the above embodiments are discussed with reference to carbon dioxide as the working fluid, in certain other embodiments, other low critical temperature working fluids suitable for use are also envisaged. In accordance with the exemplary embodiment, Rankine cycles employing carbon dioxide as the working fluid may have a compact footprint, small turbomachinery, low inventory and consequently faster ramp-up time than Rankine cycles employing steam as the working fluid.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
