Patent Application
20120102987
The embodiments of the subject matter disclosed herein generally relate to power generation systems and more specifically to advanced adiabatic compressed air energy storage systems.
As population increases, the desire for more electrical power is also generally increasing. Demand for this power typically varies during the course of a day with afternoon and early evening hours generally being the time of peak demand with later night and very early morning hours generally being the time of lowest demand for power. However, power generation systems need to meet both the lowest and highest demand systems for efficiently delivering power at the various demand levels.
One system attempts to solve this problem by storing energy generated during off-peak demand hours for use during peak demand hours. This system is called an Advanced Adiabatic Compressed Air Energy Storage (AA-CAES) system and is shown in
The air flow then goes, in step 3e, from the second radial compressor 10 to an energy storage unit, e.g., a Thermal Energy Store 12. The hot compressed air from the second radial compressor 10 is then cooled by the Thermal Energy Store 12. The heat energy is stored in the Thermal Energy Store 12 for future use and any water that is generated by the cooling process is drained off. The cooled compressed air is then sent to a Safety Cooler 14 in step 3f, where the air is further cooled prior to being sent in step 3g to a storage facility, e.g., cavern 16. This storage of the compressed air in the cavern 16 and the storage of the energy in the Thermal Energy Store 12 typically occurs during non-peak demand operation of the power generation system 2.
When the demand for power from the power generation system 2 increases to a desired point, energy output can be increased by releasing the stored compressed air back into the system to drive an expander 18, e.g., a turbine. For example, the cavern 16 releases some of the stored compressed air, in step 3h, to the Thermal Energy Store 12 for heating. Heat energy is transferred from the Thermal Energy Store 12 to the compressed air and the heated compressed air flows to a particle filter 20 in step 3i. The heated compressed air then flows, in step 3j, to an expansion section of turbine 18. During expansion the air cools and undergoes a pressure drop while producing the work which drives the shaft 26 which in turn spins a portion of a generator 30 for power generation. After expansion the air flows from the turbine 18 to an air outlet 22 in step 3k, typically for release to atmosphere. Power generation system 2 can also include a shaft 24 for the compressors, a gear box 28 and a motor 32.
While the system shown in
Accordingly, systems and methods for improving efficiency in power generation systems are desirable.
According to an exemplary embodiment there is a system for cooling air in a power generation system. The system includes: an air handling unit configured to receive air, to cool the air and to remove moisture from the air; the first compressor fluidly connected to the air handling unit and configured to receive the air from the air handling unit and to exhaust a first compressed, heated air flow; a vapor absorption chiller connected to the first compressor and configured to transfer heat energy between a plurality of mediums and to cool the first compressed, heated air flow; a second compressor connected to the vapor absorption chiller and configured to receive the cooled first compressed, heated air flow and to exhaust a second compressed, heated air flow; an energy storage unit connected to the second compressor and configured to store heat energy from the second compressed, heated air flow; and a storage facility connected to the energy storage unit and configured to store a cooled, compressed air received from the energy storage unit and to selectively release the cooled, compressed air back into the power generation system.
According to another exemplary embodiment there is a system for cooling air in a power generation system. The system includes: an air handling unit configured to receive air, to cool the air and to remove moisture from the air; a first compressor fluidly connected to the air handling unit and configured to receive the air from the air handling unit and to exhaust a first compressed, heated air flow; a vapor absorption chiller connected to the first compressor and configured to transfer heat energy between a plurality of mediums and to cool the first compressed, heated air flow; and a second compressor connected to the vapor absorption chiller and configured to receive the cooled first compressed, heated air flow and to exhaust a second compressed, heated air flow.
According to another exemplary embodiment there is a method for cooling air in a power generation system. The method includes: receiving air at an air handling unit; cooling the air at the air handling unit; removing moisture from the air at the air handling unit; compressing air by a first compressor; exhausting a first compressed, heated air flow from the first compressor; transferring heat energy between a plurality of mediums at an vapor absorption chiller; cooling the first compressed, heated air flow at the vapor absorption chiller; compressing the cooled first compressed, heated air flow; and exhausting a second compressed, heated air flow.
The accompanying drawings illustrate exemplary embodiments, wherein:
The following detailed description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Additionally, the drawings are not necessarily drawn to scale. Also, the following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims.
Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
As described in the Background section, systems and methods for improving efficiency in power generation systems are desirable. Exemplary embodiments described herein provide systems and methods for improving efficiency in power generation systems. According to exemplary embodiments, heat energy typically lost between compressors in a Compressed Air Energy Storage (CAES) system can be recovered for use in a modified adiabatic CAES (AA-CAES) system, an example of which is shown in
According to exemplary embodiments,
The air flow then goes in step 5e from the second radial compressor 210 to an energy storage unit, e.g., a Thermal Energy Store 212. The hot compressed air from the second radial compressor 210 is then cooled by the Thermal Energy Store 212. The heat energy is stored in the Thermal Energy Store 212 for future use and any water that is generated by the cooling process is drained off. The cooled compressed air is then sent to a Safety Cooler 214 in step 5f, where the air is further cooled prior to being sent in step 5g to a storage facility, e.g., cavern 216. This storage of the compressed air in the cavern 216 and the storage of the energy in the Thermal Energy Store 212 typically occurs during non-peak demand operation of the power generation system 202.
When the demand on the power generation system 202 increases to a desired point, energy output can be increased by releasing the stored compressed air back into the system to drive an expander 218, e.g., a turbine. For example, the cavern 216 releases some of the stored compressed air in step 5h which undergoes preheating in an insulated hot oil tank 220. The released compressed air then flows to the Thermal Energy Store 212 for heating in step 5i. Heat energy is transferred from the Thermal Energy Store 212 to the compressed air and the heated compressed air flows (optionally) to a particle filter 222 in step 5j. The heated compressed air then flows in step 5k from the particle filter 222 to an expansion section of turbine 218. During expansion the air cools and undergoes a pressure drop while producing the work which drives the shaft 224, which in turn spins a portion of a generator 226 for generating power. After expansion the air flows from the turbine 218 to an air outlet 228 in step 5j, typically for release to atmosphere. The power generation system 202 can also include a shaft 230 for the compressors, a gear box 234 and a motor 232 for driving the compressor 204.
Returning now to the Intercooler 208 and the closed loop oil system, the flow of the oil which supports the heat energy transfer described above will now be described. According to exemplary embodiments, oil is initially heated in the Intercooler 208 by the exhaust air from the axial compressor 204. Other types of compressors may be used in the power generation system 202. This heated oil is transferred from the Intercooler 208 by, e.g., a hot oil pump 236, to the insulated hot oil tank 220. As previously described, heat is transferred from the hot oil to the compressed air when released from the cavern 216. This cooled oil is then pumped by a cold oil pump 238 to a cold oil tank 240 which is typically not insulated. From there the cooled oil is pumped back to the Intercooler 208 to continue the process again. The oil used for this closed loop heat transfer process can have a high specific heat. The oil may be any di-thermic oil, for example, a Dowtherm fluid that has a specific heat of 2.3 kJ/kg-K at substantially 250° C.
According to an exemplary embodiment, an illustrative example with values of pressures and temperatures of the air and oil at various points of the system shown in
According to another exemplary embodiment, heat energy can be captured and stored for future use in a power generation system 402 as shown in
The air flow then goes in step 7e from the second radial compressor 410 to an energy storage unit, e.g., a Thermal Energy Store 412. The hot compressed air from the second radial compressor 410 is then cooled by the Thermal Energy Store 412. The heat energy is stored in the Thermal Energy Store 412 for future use and any water that is generated by the cooling process is drained off. The cooled compressed air is then sent to a Safety Cooler 414 in step 7f, where the air is further cooled prior to being sent in step 7g to a storage facility, e.g., cavern 416. This storage of the compressed air in the cavern 416 and the storage of the heat energy in the Thermal Energy Store 412 typically occurs during non-peak demand operation of the power generation system 402.
When the demand on the power generation system 402 increases to a desired point, energy output can be increased by releasing the stored compressed air back into the system to drive an expander 418, e.g., a turbine. For example, the cavern 416 releases some of the stored compressed air in step 7h which undergoes preheating at the insulated hot oil tank 406. The released compressed air then flows to the Thermal Energy Store 412 for heating in step 7i. Heat energy is transferred from the Thermal Energy Store 412 to the compressed air and the heated compressed air flows to a particle filter 420 in step 7j. The heated compressed air then flows in step 7k from the particle filter 420 to an expansion section of turbine 418. During expansion the air cools and undergoes a pressure drop while producing the work which drives the shaft 422 which in turn spins a portion of a generator 424 for generating power. After expansion the air flows from the turbine 418 to an air outlet 426 in step 7l, typically for release to atmosphere. Power generation system 402 can also include a shaft 428 for the compressors, a gear box 430 and a motor 432.
According to an exemplary embodiment, an illustrative example with values of the pressures and temperatures of the air and oil at various points of the system shown in
According to another exemplary embodiment, an air handling unit 604 and a vapor absorption chiller 606 can be implemented in the beginning stages of a power generation system 602 as shown in
According to exemplary embodiments, the vapor absorption chiller 606 acts as a heat exchanger which in turn allows the exhaust air from the axial compressor 608 to be cooled to the desired temperature, as well as allowing the air handling unit 604 to cool the air prior to air entering the axial compressor 608 as will now be described with respect to
According to exemplary embodiments, the refrigerant vapor within the vapor absorption chiller 606 is evaporated during the generation stage 704 and flows to a condenser 706. The condenser 706 includes a heat exchanger 708 and outputs a liquid refrigerant which in turn cools the cooling loop 702 as shown in heat exchanger 710. This refrigerant is then cooled by cooling loop 712 and pumped back by pump 714 to the generation stage 704. Additionally, some portion of the refrigerant that remains in a liquid form from the generation stage 704 enters the heat exchanger 710 and is also cooled by the cooling loop 712 prior to being pumped back to the generation stage 704.
According to an exemplary embodiment, an illustrative example with values of the pressures and temperatures of the air and oil at various points of the system shown in
While the above described exemplary embodiments have shown three compressors in series and capturing the heat energy between the axial and the radial compressors, other exemplary variations exist. For example, other quantities and types of compressors could be used, such as one axial and one radial compressor. Additionally, heat energy can be captured for future use from the exhaust of other compressors as desired.
Utilizing the above-described exemplary systems according to exemplary embodiments, a method for capturing heat energy in a power generation system is shown in the flowchart of
Utilizing the above-described exemplary systems according to exemplary embodiments, a method for cooling air in a power generation system is shown in the flowchart of
The above-described exemplary embodiments are intended to be illustrative in all respects, rather than restrictive, of the present invention. Thus the present invention is capable of many variations in detailed implementation that can be derived from the description contained herein by a person skilled in the art. All such variations and modifications are considered to be within the scope and spirit of the present invention as defined by the following claims. No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items.
This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.
