Power circulation system utilizing exhaust waste heat of gas turbine and LNG (liquefied natural gas) cold energy

Abstract

The invention provides a power circulation system utilizing gas turbine exhaust waste heat and LNG cold energy. The power circulation system comprises a gas turbine, a supercritical carbon dioxide circulation system, a Kalina circulation system, a transcritical carbon dioxide circulation system and liquefied natural gas. The supercritical carbon dioxide circulating system comprises a first heater, the Kalina circulating system comprises a second heater and a first condenser, and the transcritical carbon dioxide circulating system comprises a third heater and a second condenser; the gas turbine, the first heater, the second heater and the third heater are connected in sequence, so that exhaust gas of the gas turbine provides heat sources for the three circulating systems respectively; the second condenser is connected with the first condenser, and liquefied natural gas sequentially enters the second condenser and the first condenser to condense corresponding working media. The requirements of different power cycles for the heat source temperature are reasonably utilized, and efficient gradient utilization of the exhaust heat energy of the gas turbine is achieved. And meanwhile, the cold energy of LNG gasification is efficiently and reasonably utilized.

Description

Technical Field

[0001] This invention belongs to the field of power cycle system technology, specifically relating to a power cycle system that utilizes waste heat from gas turbine exhaust and cold energy from LNG. Background Technology

[0002] Gas turbines have seen significant development in recent years due to their flexible start-up, clean operation, and high efficiency. The high exhaust temperature of gas turbines means that efficient and rational utilization of exhaust waste heat can effectively improve the efficiency of the gas turbine cycle system. Supercritical carbon dioxide cycles, where the working fluid is always above the critical point, offer advantages such as compact structure and high efficiency due to the unique properties of carbon dioxide, enabling efficient utilization of medium- and high-temperature waste heat. The Karina cycle, with its variable-temperature evaporation characteristics, effectively reduces irreversible losses during evaporation, making it highly efficient in utilizing medium- and low-temperature waste heat. Transcritical carbon dioxide cycles, with their low boiling point, can effectively utilize low-temperature heat sources, but require high-temperature cold sources. When LNG temperature rises from -162℃ to 25℃, approximately 830 kJ / kg of cold energy is released. However, most LNG regasification terminals currently release this cold energy into seawater or air, resulting in significant waste and environmental pollution. Therefore, efficient and rational utilization of LNG regasification cold energy has significant economic and environmental value.

[0003] To address the aforementioned issues, it is necessary to propose a power cycle system that utilizes waste heat from gas turbine exhaust and cold energy from LNG, which is rationally designed and effectively solves these problems. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide a power cycle system that utilizes the waste heat of gas turbine exhaust and the cold energy of LNG.

[0005] This invention provides a power cycle system utilizing waste heat from gas turbine exhaust and cold energy from LNG, comprising a gas turbine, a supercritical carbon dioxide cycle system, a Karina cycle system, a transcritical carbon dioxide cycle system, and liquefied natural gas; the supercritical carbon dioxide cycle system includes a first heater, the Karina cycle system includes a second heater and a first condenser, and the transcritical carbon dioxide cycle system includes a third heater and a second condenser. The gas turbine, the first heater, the second heater, and the third heater are connected in sequence, so that the exhaust gas from the gas turbine provides heat sources for the supercritical carbon dioxide cycle system, the Karina cycle system, and the transcritical carbon dioxide cycle system, respectively. The second condenser is connected to the first condenser, and the liquefied natural gas enters the second condenser and the first condenser in sequence to condense the corresponding working fluid.

[0006] Optionally, the first condenser is connected to the gas turbine, wherein the liquefied natural gas condenses the working fluid in the second condenser and the first condenser, absorbs heat, vaporizes, and heats up to room temperature, and enters the gas turbine as fuel.

[0007] Optionally, the supercritical carbon dioxide cycle system further includes a supercritical carbon dioxide cycle turbine, a high-temperature regenerator, a low-temperature regenerator, and a first heat exchanger. The inlet of the supercritical carbon dioxide circulating turbine is connected to the outlet of the first heater, and the outlet of the supercritical carbon dioxide circulating turbine is connected to the first inlet of the high-temperature regenerator. The first inlet of the low-temperature regenerator is connected to the first outlet of the high-temperature regenerator, and the first outlet of the low-temperature regenerator is connected to the first inlet of the first heat exchanger.

[0008] Optionally, the supercritical carbon dioxide cycle system further includes a main compressor; The inlet of the main compressor is connected to the first outlet of the first heat exchanger, and the outlet of the main compressor is connected to the second inlet of the low-temperature regenerator. Optionally, the supercritical carbon dioxide cycle system further includes a recompressor; The inlet of the recompressor is connected to the first outlet of the low-temperature regenerator, and the outlet of the recompressor is connected to the second outlet of the low-temperature regenerator. After merging, they are connected to the second inlet of the high-temperature regenerator.

[0009] Optionally, the second outlet of the high-temperature regenerator is connected to the inlet of the first heater.

[0010] Optionally, the Karina circulation system further includes a first working fluid pump; The inlet and outlet of the first working fluid pump are connected to the outlet of the first condenser and the inlet of the first heat exchanger, respectively.

[0011] Optionally, the Karina circulation system further includes a gas-liquid separator, a Karina circulation turbine, and a mixer; The inlet of the gas-liquid separator is connected to the second outlet of the first heat exchanger, and the gas outlet of the gas-liquid separator is connected to the inlet of the second heater. The inlet of the Karina circulating turbine is connected to the outlet of the second heater, and the outlet of the Karina circulating turbine is connected to the first inlet of the mixer. The outlet of the mixer is connected to the inlet of the first condenser.

[0012] Optionally, the transcritical carbon dioxide cycle system further includes a second working fluid pump and a second heat exchanger; The inlet of the second working fluid pump is connected to the outlet of the second condenser, and the outlet of the second working fluid pump is connected to the first inlet of the second heat exchanger. The second inlet of the second heat exchanger is connected to the liquid outlet of the gas-liquid separator, the first outlet of the second heat exchanger is connected to the second inlet of the mixer, and the second outlet of the second heat exchanger is connected to the inlet of the third heater.

[0013] Optionally, the transcritical carbon dioxide cycle system further includes a transcritical carbon dioxide turbine; The inlet of the transcritical carbon dioxide turbine is connected to the outlet of the third heater, and the outlet of the transcritical carbon dioxide turbine is connected to the inlet of the second condenser.

[0014] This invention relates to a power cycle system utilizing waste heat from gas turbine exhaust and cold energy from LNG. The system comprises a gas turbine, a supercritical carbon dioxide cycle system, a Kalina cycle system, a transcritical carbon dioxide cycle system, and liquefied natural gas (LNG). Based on the different heat source temperature requirements of each power cycle, the gas turbine exhaust sequentially provides heat to the supercritical, Kalina, and transcritical carbon dioxide cycles, enabling efficient cascade utilization of the gas turbine exhaust heat. Simultaneously, this invention utilizes the cold energy from LNG vaporization to achieve the condensation of the working fluid in the transcritical and Kalina cycles, realizing the efficient and rational utilization of LNG regasification cold energy. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a power cycle system that utilizes waste heat from gas turbine exhaust and cold energy from LNG, according to an embodiment of the present invention. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] like Figure 1 As shown, the present invention provides a power cycle system that utilizes the waste heat of gas turbine exhaust and the cold energy of LNG, including a gas turbine 01, a supercritical carbon dioxide cycle system, a Karina cycle system, a transcritical carbon dioxide cycle system, and liquefied natural gas (LNG).

[0018] like Figure 1 As shown, the supercritical carbon dioxide cycle system includes a first heater 14, a supercritical carbon dioxide cycle turbine 15, a high-temperature regenerator 13, a low-temperature regenerator 12, a first heat exchanger 16, a main compressor 11, and a re-compressor 17.

[0019] The Karina circulation system includes a second heater 23, a first condenser 26, a first working fluid pump 21, a gas-liquid separator 22, a Karina circulation turbine 24, and a mixer 25.

[0020] The transcritical carbon dioxide cycle system includes a third heater 33, a second condenser 35, a second working fluid pump 31, a second heat exchanger 32, and a transcritical carbon dioxide turbine 34.

[0021] Among them, the gas turbine 01, the first heater 14, the second heater 23 and the third heater 33 are connected in sequence, so that the exhaust gas of the gas turbine 01 enters the supercritical carbon dioxide cycle system, the Karina cycle system and the transcritical carbon dioxide cycle system in turn, providing heat sources for the supercritical carbon dioxide cycle system, the Karina cycle system and the transcritical carbon dioxide cycle system respectively, realizing the efficient cascade utilization of the exhaust heat of the gas turbine 01.

[0022] The second condenser 35 is connected to the first condenser 26. Liquefied natural gas enters the second condenser 35 and the first condenser 26 in sequence. The cold energy of the liquefied natural gas condenses the corresponding working fluids in the second condenser 35 and the first condenser 26, realizing the efficient and rational utilization of the cold energy of liquefied natural gas regasification.

[0023] This invention relates to a power cycle system utilizing waste heat from gas turbine exhaust and cold energy from LNG. The system comprises a gas turbine, a supercritical carbon dioxide cycle system, a Kalina cycle system, a transcritical carbon dioxide cycle system, and liquefied natural gas (LNG). Based on the different heat source temperature requirements of each power cycle, the gas turbine exhaust sequentially provides heat to the supercritical, Kalina, and transcritical carbon dioxide cycles, enabling efficient cascade utilization of the gas turbine exhaust heat. Simultaneously, this invention utilizes the cold energy from LNG vaporization to achieve the condensation of the working fluid in the transcritical and Kalina cycles, realizing the efficient and rational utilization of LNG regasification cold energy.

[0024] For example, the first condenser 26 is connected to the gas turbine 01. While liquefied natural gas condenses the working fluid in the second condenser 35 and the first condenser 26, it absorbs heat, vaporizes, and heats up to room temperature. Then, it enters the gas turbine 01 as fuel, thereby increasing the temperature of the fuel entering the gas turbine and improving the efficiency of the gas turbine.

[0025] For example, as shown in the figure, in a supercritical carbon dioxide cycle system, the inlet of the supercritical carbon dioxide cycle turbine 15 is connected to the outlet of the first heater 14, and the outlet of the supercritical carbon dioxide cycle turbine 15 is connected to the first inlet of the high-temperature regenerator 13. The first inlet of the low-temperature regenerator 12 is connected to the first outlet of the high-temperature regenerator 13, and the first outlet of the low-temperature regenerator 12 is connected to the first inlet of the first heat exchanger 16.

[0026] Specifically, the carbon dioxide working medium is heated by the exhaust gas from the gas turbine 01 in the first heater 14. The heated carbon dioxide working medium then enters the supercritical carbon dioxide cycle turbine 15 to perform work, converting its internal energy into mechanical energy. The exhaust carbon dioxide gas that has performed work in the supercritical carbon dioxide cycle turbine 15 still has a high temperature. It then enters the high-temperature regenerator 13 and the low-temperature regenerator 12 for reheating, transferring its heat energy to the carbon dioxide working medium that re-enters the cycle to improve the cycle's thermal efficiency.

[0027] For example, such as Figure 1 As shown, in the supercritical carbon dioxide cycle system, the inlet of the main compressor 11 is connected to the first outlet of the first heat exchanger 16, and the outlet of the main compressor 11 is connected to the second inlet of the low-temperature regenerator 12. The inlet of the recompressor 17 is connected to the first outlet of the low-temperature regenerator 12, and the outlet of the recompressor 17 is connected to the second outlet of the low-temperature regenerator 12, which then merges and connects to the second inlet of the high-temperature regenerator 13. The second outlet of the high-temperature regenerator 13 is connected to the inlet of the first heater 14.

[0028] Specifically, the carbon dioxide exhaust gas that completes the reheating process in the low-temperature regenerator 12 is divided into two parts: one part enters the recompressor 17 for compression, and the other part enters the first heat exchanger 16 to be cooled by the ammonia solution of the Karina cycle system. Subsequently, the cooled carbon dioxide enters the main compressor 11 for compression, and the compressed carbon dioxide enters the low-temperature regenerator 12 to be heated to the same temperature as the carbon dioxide at the outlet of the recompressor 17. Then, the two carbon dioxide working fluids are mixed and enter the high-temperature regenerator 13 to be heated by the carbon dioxide turbine exhaust gas, and then enter the first heater 14 to be heated by the exhaust gas from the gas turbine 01. The heated carbon dioxide working fluid enters the supercritical carbon dioxide cycle turbine 15 to perform work, outputting mechanical energy. This completes the supercritical carbon dioxide cycle.

[0029] like Figure 1 As shown, in the Karina circulation system, the inlet and outlet of the first working fluid pump 21 are connected to the outlet of the first condenser 26 and the inlet of the first heat exchanger 16, respectively. The inlet of the gas-liquid separator 22 is connected to the second outlet of the first heat exchanger 16, and the gas outlet of the gas-liquid separator 22 is connected to the inlet of the second heater 23. The inlet of the Karina circulation turbine 24 is connected to the outlet of the second heater 23, and the outlet of the Karina circulation turbine 24 is connected to the first inlet of the mixer 25. The outlet of the mixer 25 is connected to the inlet of the first condenser 26.

[0030] Specifically, the ammonia solution, under the action of the first working fluid pump 21, enters the first heat exchanger 16 of the supercritical carbon dioxide cycle, where it is heated and evaporated by carbon dioxide into a gas-liquid two-phase fluid. The gas-liquid two-phase fluid then enters the gas-liquid separator 22 for gas-liquid separation, separating into ammonia-rich vapor and ammonia-lean solution. Subsequently, the ammonia-rich saturated vapor separated by the gas-liquid separator 22 enters the second heater 23 and is heated by the gas turbine exhaust 01 to become ammonia-rich superheated vapor. This heated ammonia-rich superheated vapor then enters the Kalina cycle turbine 24 to perform work, outputting mechanical energy. The ammonia-lean saturated liquid separated by the gas-liquid separator 22 enters the second heat exchanger 32 of the transcritical carbon dioxide cycle system, transferring its heat to the transcritical carbon dioxide cycle. The ammonia-rich vapor that has performed work in the Kalina cycle turbine 24, along with the ammonia-lean solution that has released its heat, enters the mixer 25 for mixing. The resulting gas-liquid two-phase mixture then enters the first condenser 26 where it is condensed into a liquid state by liquefied natural gas, becoming the ammonia solution. This completes the Kalina cycle.

[0031] For example, such as Figure 1 As shown, in the transcritical carbon dioxide cycle system, the inlet of the second working fluid pump 31 is connected to the outlet of the second condenser 35, and the outlet of the second working fluid pump 31 is connected to the first inlet of the second heat exchanger 32. The second inlet of the second heat exchanger 32 is connected to the liquid outlet of the gas-liquid separator 22, the first outlet of the second heat exchanger 32 is connected to the second inlet of the mixer 25, and the second outlet of the second heat exchanger 32 is connected to the inlet of the third heater 33. The inlet of the transcritical carbon dioxide turbine 34 is connected to the outlet of the third heater 33, and the outlet of the transcritical carbon dioxide turbine 34 is connected to the inlet of the second condenser 35.

[0032] Specifically, liquid carbon dioxide enters the second heat exchanger 32 under the action of the second working fluid pump 31, where it is heated by the lean ammonia saturated liquid of the Karina cycle to become gaseous carbon dioxide with a certain degree of superheat. The carbon dioxide working fluid then enters the third heater 33 and is further heated by the exhaust gas from the gas turbine 01. The heated carbon dioxide working fluid enters the transcritical carbon dioxide turbine 34 to perform work, outputting mechanical energy. The exhaust gas from the transcritical carbon dioxide turbine, having completed its work, enters the second condenser 35 and is condensed into liquid by liquefied natural gas. This completes the transcritical carbon dioxide cycle.

[0033] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A power cycle system utilizing waste heat from gas turbine exhaust and cold energy from LNG, characterized in that, It includes a gas turbine, a supercritical carbon dioxide cycle system, a Karina cycle system, a transcritical carbon dioxide cycle system, and liquefied natural gas; the supercritical carbon dioxide cycle system includes a first heater, the Karina cycle system includes a second heater and a first condenser, and the transcritical carbon dioxide cycle system includes a third heater and a second condenser. The gas turbine, the first heater, the second heater, and the third heater are connected in sequence, so that the exhaust gas from the gas turbine provides heat sources for the supercritical carbon dioxide cycle system, the Karina cycle system, and the transcritical carbon dioxide cycle system, respectively. The second condenser is connected to the first condenser, and the liquefied natural gas enters the second condenser and the first condenser in sequence to condense the corresponding working fluid.

2. The system according to claim 1, characterized in that, The first condenser is connected to the gas turbine. While the liquefied natural gas condenses the working fluid in the second condenser and the first condenser, it absorbs heat, vaporizes, and heats up to room temperature, and then enters the gas turbine as fuel.

3. The system according to claim 1, characterized in that, The supercritical carbon dioxide cycle system also includes a supercritical carbon dioxide cycle turbine, a high-temperature regenerator, a low-temperature regenerator, and a first heat exchanger. The inlet of the supercritical carbon dioxide circulating turbine is connected to the outlet of the first heater, and the outlet of the supercritical carbon dioxide circulating turbine is connected to the first inlet of the high-temperature regenerator. The first inlet of the low-temperature regenerator is connected to the first outlet of the high-temperature regenerator, and the first outlet of the low-temperature regenerator is connected to the first inlet of the first heat exchanger.

4. The system according to claim 3, characterized in that, The supercritical carbon dioxide cycle system also includes a main compressor; The inlet of the main compressor is connected to the first outlet of the first heat exchanger, and the outlet of the main compressor is connected to the second inlet of the low-temperature regenerator.

5. The system according to claim 4, characterized in that, The supercritical carbon dioxide cycle system also includes a recompressor; The inlet of the recompressor is connected to the first outlet of the low-temperature regenerator, and the outlet of the recompressor is connected to the second outlet of the low-temperature regenerator. After merging, they are connected to the second inlet of the high-temperature regenerator.

6. The system according to claim 5, characterized in that, The second outlet of the high-temperature regenerator is connected to the inlet of the first heater.

7. The system according to claim 3, characterized in that, The Karina circulation system also includes a first working fluid pump; The inlet and outlet of the first working fluid pump are connected to the outlet of the first condenser and the inlet of the first heat exchanger, respectively.

8. The system according to claim 7, characterized in that, The Karina circulation system also includes a gas-liquid separator, a Karina circulation turbine, and a mixer; The inlet of the gas-liquid separator is connected to the second outlet of the first heat exchanger, and the gas outlet of the gas-liquid separator is connected to the inlet of the second heater. The inlet of the Karina circulating turbine is connected to the outlet of the second heater, and the outlet of the Karina circulating turbine is connected to the first inlet of the mixer. The outlet of the mixer is connected to the inlet of the first condenser.

9. The system according to claim 8, characterized in that, The transcritical carbon dioxide cycle system also includes a second working fluid pump and a second heat exchanger. The inlet of the second working fluid pump is connected to the outlet of the second condenser, and the outlet of the second working fluid pump is connected to the first inlet of the second heat exchanger. The second inlet of the second heat exchanger is connected to the liquid outlet of the gas-liquid separator, the first outlet of the second heat exchanger is connected to the second inlet of the mixer, and the second outlet of the second heat exchanger is connected to the inlet of the third heater.

10. The system according to any one of claims 1 to 9, characterized in that, The transcritical carbon dioxide cycle system also includes a transcritical carbon dioxide turbine; The inlet of the transcritical carbon dioxide turbine is connected to the outlet of the third heater, and the outlet of the transcritical carbon dioxide turbine is connected to the inlet of the second condenser.

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