A combined power generation system of a hot ammonia turbine and a gas turbine for decomposing ammonia using waste heat

Abstract

The present invention provides a combined power generation system of a thermal ammonia turbine and a gas turbine for decomposing ammonia with waste heat, belonging to the field of waste heat recovery from gas turbine exhaust gas. It solves the problems of single waste heat recovery path of existing gas turbines, low utilization degree, and strong pollution generated by exhaust gas. It includes a low-pressure compressor, an intercooler, a high-pressure compressor, a mixing chamber, a combustion chamber, a gas turbine, a first generator, a thermal ammonia turbine, a second generator, and an ammonia pipeline. The outlet of the low-pressure compressor is connected to the inlet of the heat flow side of the intercooler, the outlet of the heat flow side of the intercooler is connected to the inlet of the high-pressure compressor, the outlet of the high-pressure compressor is connected to the first inlet of the mixing chamber, the outlet of the mixing chamber is connected to the inlet of the combustion chamber, the outlet of the combustion chamber is connected to the inlet of the gas turbine, and the driving end of the gas turbine is connected to the first generator. It is mainly used for waste heat recovery from gas turbine exhaust gas and power generation.

Description

Technical Field

[0001] The present invention belongs to the field of waste heat recovery of gas turbine exhaust gas, and particularly relates to a combined power generation system of a thermal ammonia turbine for decomposing ammonia with waste heat and a gas turbine. Background Art

[0002] To improve the thermal efficiency of a gas turbine, corresponding measures are usually taken for simple cycles and advanced cycles respectively. For simple cycles, the main measures are to increase the cycle pressure ratio, temperature ratio, and reduce the cooling air volume. For advanced cycles, methods such as intercooling, reheating, waste heat utilization, and wet compression can be adopted.

[0003] The temperature of the gas turbine exhaust gas is usually higher than that of the compressed air at the compressor outlet. The existing gas turbine exhaust gas temperature is generally between 450 - 600 °C. Directly discharging this part of the high-temperature exhaust gas into the atmosphere will not only cause serious environmental pollution but also waste the available energy in the exhaust gas heat. Common gas turbine exhaust gas recovery technologies include directly heating water with the exhaust gas, regenerative cycle, etc.

[0004] The best state for the decomposition reaction of ammonia is under normal pressure and high temperature. It has a good decomposition rate above 400 °C under the action of a nickel-based catalyst. The ratio of nitrogen to hydrogen in the decomposed nitrogen-hydrogen synthesis gas is about 1:3, and there is also a small amount of ammonia that is not decomposed.

[0005] For the common waste heat recovery method of directly heating water with the gas turbine exhaust gas, the exhaust gas recovery path is single, the utilization degree is not high, and the pollution generated by the exhaust gas is strong. Summary of the Invention

[0006] In view of this, the present invention aims to provide a combined power generation system of a thermal ammonia turbine for decomposing ammonia with waste heat and a gas turbine to solve the problems of single exhaust gas recovery path, low utilization degree, and strong exhaust gas pollution of the existing gas turbine.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A combined power generation system of a thermal ammonia turbine and a gas turbine for decomposing ammonia with waste heat, which includes a low-pressure compressor, an intercooler, a high-pressure compressor, a mixing chamber, a combustion chamber, a gas turbine, a first generator, a thermal ammonia turbine, a second generator, and a liquid ammonia pipeline. The outlet of the low-pressure compressor is connected to the inlet of the hot flow side of the intercooler. The outlet of the hot flow side of the intercooler is connected to the inlet of the high-pressure compressor. The outlet of the high-pressure compressor is connected to the first inlet of the mixing chamber. The outlet of the mixing chamber is connected to the inlet of the combustion chamber. The outlet of the combustion chamber is connected to the inlet of the gas turbine. The driving end of the gas turbine is connected to the first generator. The outlet of the gas turbine is connected to the inlet of the hot flow side of the chemical recuperator. The liquid ammonia pipeline is connected to the inlet of the cold flow side of the intercooler. The outlet of the cold flow side of the intercooler is connected to the inlet of the cold flow side of the chemical recuperator. The outlet of the cold flow side of the chemical recuperator is connected to the inlet of the thermal ammonia turbine. The outlet of the thermal ammonia turbine is connected to the second inlet of the mixing chamber. The driving end of the thermal ammonia turbine is connected to the second generator.

[0008] Furthermore, a regulating valve is provided on the liquid ammonia pipeline, and liquid nitrogen enters the cold flow side of the intercooler after passing through the regulating valve.

[0009] Furthermore, a booster pump is also provided on the liquid ammonia pipeline, and the booster pump is located between the regulating valve and the intercooler.

[0010] Furthermore, the outlet of the hot flow side of the chemical recuperator is communicated with the atmospheric environment.

[0011] Furthermore, air is introduced into the inlet of the low-pressure compressor.

[0012] Furthermore, liquid nitrogen is introduced into the liquid ammonia pipeline.

[0013] Furthermore, the low-pressure compressor, the high-pressure compressor, and the gas turbine are connected by shafts.

[0014] Furthermore, the gas turbine is coaxially connected to the first generator.

[0015] Furthermore, the thermal ammonia turbine is coaxially connected to the second generator.

[0016] Furthermore, syngas is output from the outlet of the cold flow side of the chemical recuperator.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: By combining the properties of liquid ammonia and the phenomena of ammonia decomposition reaction, based on the existing intercooled cycle and regenerative cycle of gas turbines, a combined power generation system of a thermal ammonia turbine using waste heat to decompose ammonia and a gas turbine is established, which solves the disadvantages of slightly poor waste heat utilization and large pollution in the traditional gas turbine exhaust gas recovery system. The power generation system described in the present invention has a large output power, reduces the fuel consumption required, and has the characteristics of high energy utilization rate, large thermal efficiency, and small exhaust pollution.

[0018] The present invention uses the waste heat of the exhaust gas to heat the ammonia decomposition synthesis gas. The high-temperature gas turbine exhaust gas is sufficient to meet the demand for a high decomposition rate of ammonia under corresponding conditions, and the synthesis gas has a strong work capacity under the same conditions. Different from the gas turbine power generation system that only uses intercooling, the thermal efficiency and power of the entire power generation system are improved. Compared with the conventional intercooled and regenerative cycle gas turbine system, the power generation system described in the present invention has the characteristics of a larger output power and lower exhaust pollution.

[0019] In the present invention, the electric energy generated by the expansion work of ammonia and synthesis gas in the thermal ammonia turbine to drive the generator belongs to high-quality energy, which is superior to the recovery method of directly using the thermal energy of the exhaust gas.

[0020] In the ammonia decomposition synthesis gas power generation process described in the present invention, the pressurized liquid ammonia first serves as the cold source of the intermediate cooler to absorb the temperature of the air compressed by the low-pressure compressor, reducing the cycle compression work. Then, the decomposed synthesis gas and ammonia will expand and do work in the thermal ammonia turbine, and after mixing with the compressed air, enter the combustion chamber to burn, achieving the purpose of using one raw material to simultaneously provide the cold source of the intermediate cooler and the fuel of the combustion chamber, and the energy utilization rate of the entire power generation system is high.

[0021] In the present invention, the mixture of ammonia and synthesis gas after expanding and doing work in the thermal ammonia turbine still has a certain amount of heat. Introducing it into the mixing chamber will provide heat for the compressed air. The higher-temperature mixed gas obtained by pre-mixing ammonia, synthesis gas, and air burns in the combustion chamber, which can improve the thermal efficiency of the entire power generation system and effectively reduce the fuel consumption and exhaust pollution generated by the gas turbine power generation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0023] Figure 1 It is a schematic structural diagram of a combined power generation system of a thermal ammonia turbine using waste heat to decompose ammonia and a gas turbine described in the present invention.

[0024] 1 - Low-pressure compressor, 2 - Intercooler, 3 - High-pressure compressor, 4 - Mixing chamber, 5 - Combustion chamber, 6 - Gas turbine, 7 - First generator, 8 - Control valve, 9 - Booster pump, 10 - Chemical recuperator, 11 - Hot ammonia turbine, 12 - Second generator. Detailed implementation mode

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention may be combined with each other. The described embodiments are only some of the embodiments of the present invention, rather than all of the embodiments.

[0026] See Figure 1 To illustrate this embodiment, a combined power generation system of a hot ammonia turbine and a gas turbine for decomposing ammonia with waste heat includes a low-pressure compressor 1, an intercooler 2, a high-pressure compressor 3, a mixing chamber 4, a combustion chamber 5, a gas turbine 6, a first generator 7, a hot ammonia turbine 11, a second generator 12 and a liquid ammonia pipeline. The outlet of the low-pressure compressor 1 is connected to the inlet of the hot flow side of the intercooler 2. The outlet of the hot flow side of the intercooler 2 is connected to the inlet of the high-pressure compressor 3. The outlet of the high-pressure compressor 3 is connected to the first inlet of the mixing chamber 4. The outlet of the mixing chamber 4 is connected to the inlet of the combustion chamber 5. The outlet of the combustion chamber 5 is connected to the inlet of the gas turbine 6. The driving end of the gas turbine 6 is connected to the first generator 7. The outlet of the gas turbine 6 is connected to the inlet of the hot flow side of the chemical recuperator 10. The liquid ammonia pipeline is connected to the inlet of the cold flow side of the intercooler 2. The outlet of the cold flow side of the intercooler 2 is connected to the inlet of the cold flow side of the chemical recuperator 10. The outlet of the cold flow side of the chemical recuperator 10 is connected to the inlet of the hot ammonia turbine 11. The outlet of the hot ammonia turbine 11 is connected to the second inlet of the mixing chamber 4. The driving end of the hot ammonia turbine 11 is connected to the second generator 12.

[0027] A control valve 8 and a booster pump 9 are provided on the liquid ammonia pipeline. Liquid nitrogen enters the cold flow side of the intercooler 2 after passing through the control valve 8. The booster pump 9 is located between the control valve 8 and the intercooler 2. The outlet of the hot flow side of the chemical recuperator 10 is communicated with the atmospheric environment. Air is introduced into the inlet of the low-pressure compressor 1. Liquid nitrogen is introduced into the liquid ammonia pipeline. The low-pressure compressor 1, the high-pressure compressor 3 and the gas turbine 6 are connected by a shaft. The gas turbine 6 is coaxially connected to the first generator 7. The hot ammonia turbine 11 is coaxially connected to the second generator 12. The outlet of the cold flow side of the chemical recuperator 10 outputs syngas.

[0028] Ambient air enters the compressor through the inlet of the low-pressure compressor 1 for compression. The outlet of the low-pressure compressor 1 is connected to the inlet of the hot fluid side of the intercooler 2. The compressed air enters the intercooler 2 to cool down. The outlet of the hot fluid side of the intercooler 2 is connected to the inlet of the high-pressure compressor 3. The outlet of the high-pressure compressor 3 is connected to the first inlet of the mixing chamber 4. The outlet of the mixing chamber 4 is connected to the inlet of the combustion chamber 5. The outlet of the combustion chamber 5 is connected to the gas turbine 6. The low-pressure compressor 1, high-pressure compressor 3, and gas turbine 6 are connected by a shaft. The gas turbine 6 will drive the coaxial first generator 7 to work for power generation. The outlet of the gas turbine 6 is connected to the inlet of the hot fluid side of the chemical recuperator 10. The outlet of the hot fluid side of the chemical recuperator 10 discharges the exhaust gas into the external environment. Liquid ammonia enters the inlet of the booster pump 9 after passing through the regulating valve 8. The outlet of the booster pump 9 is connected to the inlet of the cold fluid side of the intercooler 2. The outlet of the cold fluid side of the intercooler 2 is connected to the inlet of the cold fluid side of the chemical recuperator 10. Ammonia absorbs heat and decomposes in the chemical recuperator 10 to obtain syngas. The syngas and ammonia then flow into the inlet of the hot ammonia turbine 11. The hot ammonia turbine 11 drives the coaxial second generator 12 to work for power generation. The outlet of the hot ammonia turbine 11 is connected to the second inlet of the mixing chamber 4. The outlet of the mixing chamber 4 is connected to the inlet of the combustion chamber 5.

[0029] Utilize the endothermic decomposition reaction of ammonia in the chemical recuperator 10 to recover the waste heat of the exhaust gas discharged from the gas turbine power generation system, so that the obtained high-temperature ammonia gas and syngas enter the hot ammonia turbine 11 to do work and generate electricity, thereby improving the efficiency and energy utilization rate of the power generation system.

[0030] The regulating valve 8 is used to control the flow rate when liquid ammonia flows in, and can indirectly control the mixing of ammonia gas, syngas with higher temperature and compressed air in the mixing chamber 4. The booster pump 9 is located between the regulating valve 8 and the intercooler 2. The compression work consumed by using the booster pump 9 to boost the pressure of liquid ammonia is less than the work consumed when directly compressing ammonia gas. The intercooler 2 is located between the low-pressure compressor 1 and the high-pressure compressor 3. Using the boosted liquid ammonia as the cold source of the intercooler 2 to cool the air compressed by the low-pressure compressor 1. The chemical recuperator 10 is located between the intercooler 2, gas turbine 6, and hot ammonia turbine 11, and will serve as a place to recover the waste heat of the gas turbine exhaust gas and carry out the ammonia decomposition reaction, producing a mixture of high-temperature ammonia gas and nitrogen-hydrogen syngas. The ammonia gas heated by the intercooler 2 is still the cold source in the chemical recuperator 10. The high-temperature exhaust gas of the gas turbine serves as the heat source of the recuperator to provide heat for ammonia decomposition. The hot ammonia turbine 11 is impacted by high-temperature and high-pressure ammonia gas and syngas, converts the kinetic energy and internal energy of the gas into mechanical energy, drives the coaxial generator to work, and then converts the mechanical energy into electrical energy for output. The outlet of the hot ammonia turbine 11 is connected to the mixing chamber 4. The ammonia gas and syngas with higher temperature in the mixing chamber 4 will mix with the compressed air, raise the temperature of the air, and then be introduced into the combustion chamber 5 for combustion.

[0031] After passing through the regulating valve 8, liquid ammonia first enters the booster pump 9 for boosting pressure. This can increase the pressure of liquid ammonia in the system, and the compression work consumed is less than that consumed when directly compressing ammonia gas, which is beneficial to improving the efficiency of the power generation system. In the intermediate cooler 2, liquid ammonia is used as the cold source to absorb the heat of the air compressed by the low-pressure compressor 1, reducing the compression work required by the power generation system and being beneficial to improving the cycle efficiency.

[0032] Different from the existing gas turbine intercooled regenerative cycle power generation system, the chemical regenerator 10 involved in this embodiment mainly uses the waste heat of the tail gas to provide heat for the ammonia decomposition reaction. Although it cannot directly improve the cycle thermal efficiency like the regenerative cycle and has a significant effect of reducing fuel consumption, it can output more electric energy by the expansion work of high-temperature ammonia gas and syngas in the hot ammonia turbine 11, and the gas after passing through the hot ammonia turbine 11 still has a relatively high temperature, reducing the heating amount required by the combustion chamber 5.

[0033] In the combustion chamber 5, the combustion reaction occurs with ammonia gas, nitrogen-hydrogen syngas and air as reactants. The main products of combustion are water and various nitrogen oxides. The mixing of air and the gas after passing through the hot ammonia turbine 11 in the mixing chamber 4 will cause premixed combustion in the combustion chamber 5. Combining with the regulating valve 8 to indirectly control the mixing degree of ammonia gas, syngas and air helps to reduce the generation of nitrogen oxides, thereby reducing the exhaust pollution generated.

[0034] When the entire gas turbine tail gas waste heat recovery ammonia endothermic decomposition syngas power generation system operates normally, its process is as follows: After being preliminarily compressed, air exchanges heat with the boosted liquid ammonia. After the air cools down, it enters the high-pressure compressor 3 for further compression, and then enters the mixing chamber 4 to be pre-mixed with the relatively high-temperature ammonia gas and syngas. Then combustion occurs in the combustion chamber 5. The generated high-temperature tail gas is mainly composed of water and nitrogen oxides. This high-temperature tail gas will provide heat for ammonia decomposition in the chemical regenerator 10 and then be discharged into the atmospheric environment. The high-temperature syngas and un-decomposed ammonia gas obtained by ammonia decomposition will expand and do work in the hot ammonia turbine 11. The relatively high-temperature ammonia gas and syngas after the hot ammonia turbine 11 will enter the mixing chamber 4 to be mixed with air in a certain proportion.

[0035] It should be noted that for the gas turbine tail gas waste heat recovery ammonia endothermic decomposition power generation system described in this embodiment, when starting for the first time, a certain amount of syngas or ammonia gas needs to be input from outside the system into the mixing chamber 4 to be mixed with air. The obtained mixed gas burns in the combustion chamber 5, and after the entire power generation system operates normally according to the working process, the externally input syngas or ammonia gas can be cut off.

[0036] Combining the properties of liquid ammonia with the phenomena of ammonia decomposition reaction, on the basis of the existing intercooled cycle and regenerative cycle of gas turbines, a combined power generation system of a thermal ammonia turbine and a gas turbine that decomposes ammonia with waste heat is established, solving the disadvantages of slightly poor waste heat utilization and large pollution in the traditional gas turbine exhaust gas recovery system. The power generation system described in the present invention has a large output power, reduces the required fuel consumption, and has the characteristics of high energy utilization rate, large thermal efficiency, and small exhaust pollution.

[0037] The waste heat of the exhaust gas is used to heat the ammonia decomposition synthesis gas. The high-temperature gas turbine exhaust gas is sufficient to meet the demand for a high decomposition rate of ammonia under corresponding conditions, and the synthesis gas has a strong work capacity under the same conditions. Different from the gas turbine power generation system that only uses intercooling, the thermal efficiency and power of the entire power generation system are improved. Compared with the conventional intercooled and regenerative cycle gas turbine system, the power generation system described in the present invention has the characteristics of a larger output power and lower exhaust pollution. The electric energy generated by the expansion work of ammonia and synthesis gas in the thermal ammonia turbine to drive the generator belongs to high-quality energy, which is superior to the recovery method of directly using the waste heat of the exhaust gas.

[0038] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. All details are not described in detail in the embodiments, nor is the invention limited to the specific embodiments described. According to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can understand and utilize the present invention well.

Claims

1. A combined power generation system of a thermal ammonia turbine and a gas turbine for decomposing ammonia using waste heat, characterized in that: It includes a low-pressure compressor (1), an intercooler (2), a high-pressure compressor (3), a mixing chamber (4), a combustion chamber (5), a gas turbine (6), a first generator (7), a thermal ammonia turbine (11), a second generator (12) and an ammonia pipeline. The outlet of the low-pressure compressor (1) is connected to the inlet of the hot fluid side of the intercooler (2). The outlet of the hot fluid side of the intercooler (2) is connected to the inlet of the high-pressure compressor (3). The outlet of the high-pressure compressor (3) is connected to the first inlet of the mixing chamber (4). The outlet of the mixing chamber (4) is connected to the inlet of the combustion chamber (5). The outlet of the combustion chamber (5) is connected to the inlet of the gas turbine (6). The driving end of the gas turbine (6) is connected to the first generator (7). The outlet of the gas turbine (6) is connected to the inlet of the hot fluid side of the chemical recuperator (10). The ammonia pipeline is connected to the inlet of the cold fluid side of the intercooler (2). The outlet of the cold fluid side of the intercooler (2) is connected to the inlet of the cold fluid side of the chemical recuperator (10). The outlet of the cold fluid side of the chemical recuperator (10) is connected to the inlet of the thermal ammonia turbine (11). The outlet of the thermal ammonia turbine (11) is connected to the second inlet of the mixing chamber (4). The driving end of the thermal ammonia turbine (11) is connected to the second generator (12). A regulating valve (8) is provided on the ammonia pipeline. Liquid nitrogen enters the cold fluid side of the intercooler (2) after passing through the regulating valve (8). A booster pump (9) is also provided on the ammonia pipeline, and the booster pump (9) is located between the regulating valve (8) and the intercooler (2).

2. The combined power generation system of a thermal ammonia turbine and a gas turbine for decomposing ammonia using waste heat according to claim 1, characterized in that: The outlet of the hot fluid side of the chemical recuperator (10) communicates with the atmospheric environment.

3. The combined power generation system of a thermal ammonia turbine and a gas turbine for decomposing ammonia using waste heat according to claim 1, characterized in that: Air is introduced into the inlet of the low-pressure compressor (1).

4. The combined power generation system of a thermal ammonia turbine and a gas turbine for decomposing ammonia using waste heat according to claim 1, characterized in that: Liquid ammonia is introduced into the ammonia pipeline.

5. The combined power generation system of a thermal ammonia turbine and a gas turbine for decomposing ammonia using waste heat according to claim 1, characterized in that: The low-pressure compressor (1), the high-pressure compressor (3) and the gas turbine (6) are connected by shafts.

6. The combined power generation system of a thermal ammonia turbine and a gas turbine for decomposing ammonia using waste heat according to claim 5, characterized in that: The gas turbine (6) is coaxially connected to the first generator (7).

7. The combined power generation system of a thermal ammonia turbine and a gas turbine for decomposing ammonia using waste heat according to claim 1, characterized in that: The thermal ammonia turbine (11) is coaxially connected to the second generator (12).

8. The combined power generation system of a thermal ammonia turbine and a gas turbine for decomposing ammonia using waste heat according to claim 1, characterized in that: Synthesis gas is output from the outlet of the cold fluid side of the chemical recuperator (10).

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