A gas turbine ammonia combined cycle power generation system based on multi-expander waste heat recovery

Abstract

This invention provides a gas turbine ammonia combined cycle power generation system based on multi-expander waste heat recovery. It integrates a liquid ammonia storage tank and pump, a liquid ammonia vaporizer, an ammonia cracker, a flue gas-ammonia heat exchanger, several expanders, and a gas turbine into a single cycle. The liquid ammonia, after exiting the storage tank, sequentially passes through a pressurization pump, a liquid ammonia vaporizer unit, a first expander unit (expanding to generate power while depressurizing and cooling), a first flue gas-ammonia heat exchanger unit (heating), a second or more expander units (expanding to generate power while depressurizing and cooling), a second or more flue gas-ammonia heat exchanger units (heating again), and an ammonia cracker unit, transforming the ammonia into a mixture of ammonia, hydrogen, and nitrogen. This mixture then passes through another expander power generation unit (expanding to generate power while depressurizing and cooling) before entering the gas turbine combustion chamber to mix and burn with air. The advantages of this invention are: integrating ammonia cracking hydrogen production technology, multi-expander technology, and a gas turbine cycle to achieve highly efficient zero-carbon power generation.

Description

Technical Field

[0001] This invention relates to the field of energy and power engineering technology, specifically to a gas turbine ammonia combined cycle power generation system based on waste heat recovery from multiple expanders. Background Technology

[0002] As the cornerstone of efficient energy conversion and clean utilization infrastructure, gas turbines play a crucial role in modern power generation. They have become key equipment supporting flexible peak shaving and low-carbon transformation in new power systems. Marine gas turbines are thermodynamic engines that use continuously flowing gas as the working fluid. Through a cyclical process of air compression by a compressor, combustion in a combustion chamber, and expansion and work by a gas turbine, they convert the chemical energy of fuel into mechanical work. Their core advantages are: ① Power density and lightweight: At the same power output, their volume is only 1 / 3 to 1 / 5 that of a diesel engine, resulting in significantly reduced weight. This makes them particularly suitable for space-constrained ship designs, improving the ship's maneuverability and carrying capacity. ② Rapid response and flexibility: Excellent low-temperature start-up performance, reaching full load within 1-2 minutes, and short switching time from cold standby to full load, suitable for emergency peak shaving or high-dynamic scenarios. ③ Environmental protection and low emissions: Using gaseous or liquid fuels, combustion is complete and ash-free. Exhaust gas can be purified to meet increasingly stringent ship emission standards. ④ Compact structure and automation: The simplified transmission mechanism facilitates monitoring, remote control, and full automation, significantly improving the engine room working environment and supporting the integration of intelligent technologies such as digital twins. ⑤ Low vibration and low noise: Smooth operation with minimal low-frequency noise components, making it particularly suitable for ships sensitive to acoustic performance.

[0003] Despite their significant advantages, marine gas turbines currently face the following challenges: ① Insufficient fuel economy: High fuel consumption, especially with a significant drop in efficiency at low loads, leading to increased operating costs, and requiring the use of high-quality, low-viscosity fuels. ② Torque and drive limitations: High operating speed but low output torque, making direct propeller driving unsuitable; gearbox reduction is necessary, increasing system complexity. ③ Low level of electrification. Summary of the Invention

[0004] To overcome the limitations of current marine gas turbines in terms of fuel economy and low electrification, this invention proposes a gas turbine ammonia combined cycle power generation system based on multi-expander waste heat recovery. Its core lies in integrating ammonia cracking hydrogen production technology, multi-expander technology and gas turbine cycle to achieve efficient zero-carbon power generation.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: A gas turbine ammonia combined cycle power generation system based on waste heat recovery from multiple expanders integrates a liquid ammonia storage tank and pump, a liquid ammonia vaporizer, an ammonia cracker, a flue gas-ammonia heat exchanger, several expanders, and a gas turbine into a single cycle to achieve efficient zero-carbon power generation. The system includes a liquid ammonia storage tank and pump unit, a liquid ammonia vaporizer unit, an ammonia cracker unit, a flue gas-ammonia heat exchanger unit, several expander power generation units, and a gas turbine power generation unit. The exhaust gas from the gas turbine passes through an ammonia cracker unit, a flue gas-ammonia heat exchanger unit, and a liquid ammonia vaporizer unit for heat exchange and cooling before entering the exhaust system. After liquid ammonia comes out of the liquid ammonia storage tank, it passes through a pressurization pump, a liquid ammonia vaporizer unit, a first expander unit to expand and generate electricity while depressurizing and cooling, a first flue gas-ammonia heat exchanger unit to heat up, a second expander unit to expand and generate electricity while depressurizing and cooling, a second flue gas-ammonia heat exchanger unit to heat up again, and an ammonia cracker unit to transform it into a mixture of ammonia, hydrogen and nitrogen. After passing through a third expander power generation unit to expand and generate electricity while depressurizing and cooling, it enters the gas turbine combustion chamber to mix and burn with air. After passing through the intake system, the air enters the gas turbine compressor for compression, and then enters the gas turbine combustion chamber to mix and burn with the ammonia, hydrogen and nitrogen generated by the thermal cracking of ammonia. The high-temperature and high-pressure flue gas then enters the gas turbine for expansion and does work. The total power generation of the system is the sum of the power generation of several expander power generation units and gas turbine power generation units.

[0006] Furthermore, "compound" refers to the simultaneous combined work of several expander power generation units and gas turbine power generation units; "cycle" refers to the circulation mode formed by the liquid ammonia fuel flow path and the gas turbine-side working fluid flow path, with the liquid ammonia fuel flow path and the gas turbine-side working fluid flow path occurring simultaneously.

[0007] Furthermore, before entering the ammonia cracker unit, ammonia can be expanded and worked by several expander power generation units and heated by several flue gas-ammonia heat exchanger units before entering the ammonia cracker unit; as long as the energy of the gas turbine exhaust is utilized in stages and the temperature and pressure of ammonia are above reasonable limits (temperature not lower than the critical temperature of ammonia, and pressure not lower than the higher value of the combustion chamber design pressure).

[0008] It should be noted that the installation of several expanders is predicated on the premise that the exhaust gas has sufficient heat.

[0009] Furthermore, several expanders can all be coaxial with the gas turbine and share the same generator to generate electricity; several expanders can also be partially coaxial with the gas turbine and share the same generator to generate electricity, with the remaining parts being separate from the gas turbine; several expanders can also be completely separate from the gas turbine.

[0010] Furthermore, the temperature of the mixture containing ammonia, hydrogen, and nitrogen after the last expander power generation unit expands and performs work is maintained below 200°C, which is determined by the temperature resistance level of the existing gas turbine fuel control valve. The pressure of the mixture is maintained at a relatively high value that is not lower than the design pressure of the combustion chamber.

[0011] Furthermore, the high-temperature, high-pressure flue gas enters the gas turbine and expands, doing work for the gas turbine compressor to compress the gas, while the remainder is used to generate electricity for the generator.

[0012] Furthermore, the waste heat from the gas turbine exhaust is mainly used for the thermal cracking and sensible heat absorption of fuel in the ammonia cracker unit, the sensible heat absorption of fuel in the flue gas-ammonia heat exchanger unit, and the latent heat of vaporization and sensible heat absorption of fuel in the liquid ammonia vaporizer unit. Afterward, the remaining waste heat from the gas turbine exhaust can be used for heat exchange in the heat exchanger before entering the exhaust system for exhaust, or it can be directly entered into the exhaust system for exhaust.

[0013] Compared with the prior art, the present invention has the following advantages: This invention discloses a gas turbine ammonia combined cycle power generation system based on multi-expander waste heat recovery, which integrates ammonia cracking hydrogen production technology, multi-expander technology and gas turbine cycle to achieve efficient zero-carbon power generation; it integrates multi-expander auxiliary power generation to further improve power generation efficiency and save more fuel consumption; by setting the multi-expander and gas turbine coaxially, they can share the same generator to generate power, making the overall system structure more compact and reducing the number of generators.

[0014] Specifically, this invention aims to address the limitations of existing marine gas turbines, such as insufficient fuel economy and low electrification. It proposes a gas turbine ammonia combined cycle power generation system based on waste heat recovery from multiple expanders. "Combined" refers to the simultaneous combined work of several expander power generation units and gas turbine power generation units. "Cycle" refers to the circulation mode jointly formed by the liquid ammonia fuel flow path and the gas turbine-side working fluid flow path, with the liquid ammonia fuel flow path and the gas turbine-side working fluid flow path occurring simultaneously. First, by utilizing the waste heat from turbine exhaust for thermal cracking and fuel sensible heat absorption in the ammonia cracker unit, the fuel sensible heat absorption in the flue gas-ammonia heat exchanger unit, and the latent heat of vaporization and fuel sensible heat absorption in the liquid ammonia vaporizer unit, liquid ammonia fuel is converted into a mixture of ammonia / hydrogen / nitrogen gas with higher calorific value and greater sensible heat. This allows for more complete recovery and utilization of turbine exhaust waste heat, reducing NOx emissions and unburned ammonia emissions. Furthermore, the hydrogen and nitrogen mixture produced after ammonia cracking mixes better with air, forming a more uniform fuel gas, thus improving combustion uniformity and efficiency. In addition, by simultaneously generating electricity through several expander power generation units and the gas turbine power generation unit, the entire system can save more fuel consumption for the same output power requirement. Under the limitations of current gas turbine technology, the overall system power generation efficiency reaches over 57.6%, far exceeding the power generation efficiency of other gas turbines of the same power class, demonstrating significant potential for widespread application. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the system module framework of the present invention.

[0016] Figure 2 This is a schematic diagram of the power generation efficiency of Embodiment 1 of the present invention. Detailed Implementation

[0017] The embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0018] like Figure 1As shown, a gas turbine-ammonia combined cycle power generation system based on multi-expander waste heat recovery integrates a liquid ammonia storage tank and pump, a liquid ammonia vaporizer, an ammonia cracker, a flue gas-ammonia heat exchanger, several expanders, and a gas turbine into a single cycle, achieving efficient zero-carbon power generation. The system includes a liquid ammonia storage tank and pump unit, a liquid ammonia vaporizer unit, an ammonia cracker unit, a flue gas-ammonia heat exchanger unit, several expander power generation units, and a gas turbine power generation unit. The gas turbine exhaust gas sequentially passes through the ammonia cracker unit, the flue gas-ammonia heat exchanger unit, and the liquid ammonia vaporizer unit for heat exchange and cooling before entering the exhaust system. After exiting the liquid ammonia storage tank, the liquid ammonia sequentially passes through a pressurization pump for pressurization, the liquid ammonia vaporizer unit, and the first expander unit for expansion, power generation, and depressurization and cooling. The first flue gas-ammonia heat exchanger unit heats up the gas; the second expander unit expands the gas to generate electricity and reduces pressure and temperature; the second flue gas-ammonia heat exchanger unit heats up the gas again; after passing through the ammonia cracker unit, the gas is converted into a mixture of ammonia, hydrogen, and nitrogen. This mixture then passes through the third expander power generation unit to generate electricity and reduces pressure and temperature before entering the gas turbine combustion chamber to mix and burn with air. The air passes through the intake system and enters the gas turbine compressor for compression. It then enters the gas turbine combustion chamber to mix and burn with the mixture of ammonia, hydrogen, and nitrogen generated from the thermal cracking of ammonia. The high-temperature, high-pressure flue gas then enters the gas turbine for expansion and work. The total power output of the entire system is the sum of the power outputs of the several expander power generation units and the gas turbine power generation unit. Example 1

[0019] To test the effectiveness of the gas turbine-ammonia combined cycle power generation system based on multi-expander waste heat recovery proposed in this invention, a gas turbine-ammonia combined cycle power generation system with a total power output of 2.424 MW based on multi-expander waste heat recovery was designed, as follows: Figure 2 As shown.

[0020] The gas turbine compressor is a 10-stage axial-flow compressor with a design pressure ratio of 15.56 and an isentropic thermal efficiency of 88%. The turbine is a 2-stage axial-flow turbine with a design isentropic thermal efficiency of 90%. The combustion chamber has a design combustion efficiency of 99.8%. The turbine exhaust (temperature 575.2℃, pressure 1.05259 bar) passes sequentially through an ammonia cracker unit (using a Ru-based catalyst, the ammonia cracking conversion rate can reach over 75%), a flue gas-ammonia heat exchanger, and a liquid ammonia vaporizer unit for heat exchange and cooling before entering the exhaust system. The waste heat from the gas turbine exhaust is mainly used for the thermal cracking and fuel sensible heat absorption of the ammonia cracker unit, the fuel sensible heat absorption of the flue gas-ammonia heat exchanger unit, and the latent heat of vaporization and fuel sensible heat absorption of the liquid ammonia vaporizer unit. The remaining waste heat from the gas turbine exhaust can be used for further heat exchange in the heat exchanger before entering the exhaust system, or it can be directly discharged into the exhaust system. After liquid ammonia exits the liquid ammonia storage tank (liquid ammonia mass flow rate 0.2263 kg / s), it sequentially passes through a pressurization pump (temperature 20℃, pressure 300 bar), a liquid ammonia vaporizer unit, the first expander power generation unit for expansion and power generation while depressurizing and cooling, the first flue gas-ammonia heat exchanger unit for heating, the second expander power generation unit for expansion and power generation while depressurizing and cooling, the second flue gas-ammonia heat exchanger unit for further heating, and finally the ammonia cracker unit, where it is transformed into a mixture of ammonia, hydrogen, and nitrogen (temperature 557.2℃, pressure approximately 50 bar). After passing through the third expander power generation unit for expansion and depressurization and cooling (temperature 200℃, pressure approximately 20 bar), it enters the gas turbine combustion chamber to mix and burn with air. After passing through the intake system (temperature 15℃, mass flow rate 4.27 kg / s, pressure 1.013 bar), atmospheric air enters the gas turbine compressor for compression (compressed air temperature 392.9℃, pressure 15.609792 bar). Then, it enters the gas turbine combustion chamber and is mixed with and combusted with ammonia, hydrogen, and nitrogen produced by the thermal decomposition of ammonia. The high-temperature, high-pressure flue gas (temperature 1200℃, pressure 15.12877 bar) then enters the gas turbine for expansion and work. The turbine expansion work (output power 3572.2 kW) is used for compression in the gas turbine compressor (power consumption 1679.2 kW), with the remainder used for power generation by the gas turbine generator. The total power output of the entire system is 2.424 MW, consisting of the power output of the three expander generator units (expander efficiency of 85%) and the gas turbine generator unit (gas turbine generator efficiency of 0.982 and mechanical transmission efficiency of 0.995). At this point, the overall system power generation efficiency reaches 57.6%, which is calculated as follows: Overall system power generation efficiency = (expander power generation + gas turbine power generation) / (fuel mass flow rate × fuel lower heating value) = 2.424 MW / (0.2263 kg / s × 18.6 MJ / kg) = 57.6%, which is far higher than the power generation efficiency of other gas turbines of the same power class currently available.

[0021] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the concept of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A gas turbine-ammonia combined cycle power generation system based on multi-expander waste heat recovery, characterized in that: The liquid ammonia storage tank and pump, liquid ammonia vaporizer, ammonia cracker, flue gas-ammonia heat exchanger, several expanders and gas turbine are integrated into a single cycle. The system includes a liquid ammonia storage tank and pump unit, a liquid ammonia vaporizer unit, an ammonia cracker unit, a flue gas-ammonia heat exchanger unit, several expander power generation units and a gas turbine power generation unit. The exhaust gas from the gas turbine passes through an ammonia cracker unit, a flue gas-ammonia heat exchanger unit, and a liquid ammonia vaporizer unit for heat exchange and cooling before entering the exhaust system. After liquid ammonia comes out of the liquid ammonia storage tank, it passes through a pressurization pump, a liquid ammonia vaporizer unit, a first expander unit to expand and generate electricity while depressurizing and cooling, a first flue gas-ammonia heat exchanger unit to heat up, a second expander unit to expand and generate electricity while depressurizing and cooling, a second flue gas-ammonia heat exchanger unit to heat up again, and an ammonia cracker unit to transform it into a mixture of ammonia, hydrogen and nitrogen. After passing through a third expander power generation unit to expand and generate electricity while depressurizing and cooling, it enters the gas turbine combustion chamber to mix and burn with air. After passing through the intake system, the air enters the gas turbine compressor for compression, and then enters the gas turbine combustion chamber to mix and burn with the ammonia, hydrogen and nitrogen generated by the thermal cracking of ammonia. The high-temperature and high-pressure flue gas then enters the gas turbine for expansion and does work. The total power generation of the system is the sum of the power generation of several expander power generation units and gas turbine power generation units.

2. The gas turbine-ammonia combined cycle power generation system based on multi-expander waste heat recovery according to claim 1, characterized in that: Before entering the ammonia cracker unit, ammonia gas can be expanded and do work through several expander power generation units and heated by several flue gas-ammonia heat exchanger units before entering the ammonia cracker unit.

3. A gas turbine-ammonia combined cycle power generation system based on multi-expander waste heat recovery according to claim 1 or 2, characterized in that: Several expanders can all be coaxial with the gas turbine and share the same generator to generate electricity; several expanders can also be partially coaxial with the gas turbine and share the same generator to generate electricity, with the remaining parts being separate from the gas turbine; several expanders can also be completely separate from the gas turbine.

4. The gas turbine-ammonia combined cycle power generation system based on multi-expander waste heat recovery according to claim 1, characterized in that: The temperature of the mixture of ammonia, hydrogen, and nitrogen after the last expander power generation unit expands and does work is maintained below 200°C.

5. A gas turbine-ammonia combined cycle power generation system based on multi-expander waste heat recovery according to claim 1, characterized in that: The high-temperature, high-pressure flue gas enters the gas turbine and expands, doing work for the gas turbine compressor. The remaining power is used to generate electricity for the generator.

6. The gas turbine-ammonia combined cycle power generation system based on multi-expander waste heat recovery according to claim 1, characterized in that: The waste heat from the gas turbine exhaust is mainly used for the thermal cracking and sensible heat absorption of fuel in the ammonia cracker unit, the sensible heat absorption of fuel in the flue gas-ammonia heat exchanger unit, and the latent heat of vaporization and sensible heat absorption of fuel in the liquid ammonia vaporizer unit. The remaining waste heat from the gas turbine exhaust can be used for heat exchange in the heat exchanger before entering the exhaust system for exhaust, or it can be directly entered into the exhaust system for exhaust.

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