Ammonia gas turbine and self-condensation transcritical CO2 Rankine cycle combined system and operation method thereof

Abstract

The invention provides an ammonia gas turbine and self-condensation transcritical CO2 Rankine cycle combined system and an operation method thereof, and the system comprises a mixed fuel supply device which is suitable for preheating mixed fuel of air and ammonia gas to a combustible temperature and conveying the mixed fuel to a combustion chamber for combustion, the generated heat acts on the ammonia turbine to output high-temperature flue gas; the first heat exchange device is suitable for heating the carbon dioxide before entering the carbon dioxide turbine by using the high-temperature flue gas; the second heat exchange device is suitable for heating the carbon dioxide entering the first heat exchange device by using the carbon dioxide from the carbon dioxide turbine; the critical phase state conversion device is suitable for converting the carbon dioxide output by the second heat exchange device into liquid carbon dioxide and gaseous carbon dioxide, and condensing the gaseous carbon dioxide into the liquid carbon dioxide by using cold energy released by liquid ammonia vaporization; and the carbon dioxide pump is suitable for pumping the mixed liquid carbon dioxide into the first heat exchange device and the second heat exchange device for circulation.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of energy comprehensive utilization, in particular to a combined system of ammonia gas gas turbine and self-condensation transcritical CO2 Rankine cycle and a running method thereof. BACKGROUND

[0002] Ammonia gas has excellent thermodynamic and physical properties (such as latent heat of vaporization of 1370 KJ / kg) as a refrigerant, and is also friendly to the earth's atmosphere. As a fuel, ammonia gas contains a high proportion of hydrogen and can be liquefied at normal pressure and-33℃ or at normal temperature and 0.9 MPa, which is an excellent carbon-free fuel and can be used as a power system for large ships on long voyages. It is also an important technical direction for carbon emission reduction of thermal power generation. However, due to the relatively high ignition point of ammonia gas, it needs to be fully preheated before entering the combustion chamber. In addition, ammonia combustion mainly generates water and nitrogen, making it difficult to utilize the latent heat of water vapor in the flue gas. Therefore, the recovery of cold energy during liquid ammonia transportation and the comprehensive utilization of gas turbine flue gas energy are the key to improving the utilization efficiency of ammonia gas.

[0003] Carbon dioxide (CO2) has the characteristics of strong chemical stability and good thermodynamic performance, with a critical pressure of 7.38 MPa and a critical temperature of 30.8℃, which is easy to achieve. Organic Rankine cycle is a simple structure, high thermal efficiency transcritical closed cycle, which has low temperature requirement for heat extraction and is often used for low temperature heat source recovery or as a bottom cycle in combined cycle. In the Rankine cycle with CO2 as the working medium, liquid CO2 is compressed by a pump, heated by an evaporator, expanded by a turbine to do work, and then cooled to below the critical temperature of CO2 to return to the pump, forming a closed cycle. On the basis of this cycle, a regenerator is arranged between the pump and the turbine to improve the system efficiency. Before CO2 enters the pump, the working medium temperature needs to be reduced to below the critical temperature by refrigeration technology to ensure that CO2 is in liquid state, so as to ensure the effective work of the pump and the normal operation of the cycle. The critical temperature of CO2 is not much different from room temperature, and it is difficult for conventional heat exchange cooling to efficiently and stably cool the working medium to below 30℃, so refrigeration cycle or other cooling technology needs to be introduced.

[0004] Due to the change of the density of CO2 near the critical point with temperature, the supercritical gas-liquid coexistence phenomenon is converted from the liquid state, resulting in a sharp change in density and specific heat. The cross-critical CO2 Rankine cycle and closed supercritical Brayton cycle have the same problem in the arrangement of the regenerator, i.e., the regenerator is prone to produce a pinch point, affecting the heat exchange efficiency. To solve this problem, the closed supercritical Brayton cycle proposes a split recompression arrangement, which divides the regenerator into high-temperature and low-temperature parts without producing a pinch point. The working medium at the outlet of the low-temperature regenerator is split into two parts, one of which enters the recompressor and then merges into the high-temperature and low-temperature regenerators, thereby improving the overall thermal efficiency of the cycle. However, this arrangement adds a recompressor, and the recompression position is far from the critical point of CO2, which increases the compression power consumption and improves the system complexity. SUMMARY

[0005] Therefore, the present disclosure provides a combined system of ammonia gas gas turbine and self-condensation cross-critical CO2 Rankine cycle and an operation method thereof, which can effectively capture and utilize cold and heat energy, improve energy cycle efficiency, and reduce energy loss.

[0006] Specifically, as one aspect of the present disclosure, a combined system of ammonia gas gas turbine and self-condensation cross-critical CO2 Rankine cycle is provided, which comprises:

[0007] A mixed fuel supply device adapted to preheat a mixed fuel comprising air and ammonia to a combustible temperature;

[0008] A combustion chamber adapted to combust the mixed fuel preheated to a combustible temperature;

[0009] An ammonia turbine adapted to utilize the heat generated by the combustion of the combustion chamber to do work and output high-temperature flue gas;

[0010] A carbon dioxide turbine adapted to do work based on a self-condensation cross-critical CO2 Rankine cycle;

[0011] A first heat exchange device adapted to heat supercritical carbon dioxide entering the carbon dioxide turbine using high-temperature flue gas from the ammonia turbine;

[0012] A second heat exchange device adapted to heat supercritical carbon dioxide entering the first heat exchange device using supercritical carbon dioxide from the carbon dioxide turbine;

[0013] A critical phase conversion device adapted to convert the supercritical carbon dioxide output by the second heat exchange device into liquid carbon dioxide and gaseous carbon dioxide, and to condense the gaseous carbon dioxide into liquid carbon dioxide using the cold released by the vaporization of liquid ammonia; and

[0014] A carbon dioxide pump is adapted to pump mixed liquid carbon dioxide to the first heat exchange device and the second heat exchange device for heating to form supercritical carbon dioxide entering the carbon dioxide turbine.

[0015] According to an embodiment of the present disclosure, the mixed fuel supply device comprises:

[0016] A liquid ammonia pump is adapted to pump liquid ammonia.

[0017] A first cooler is adapted to vaporize the liquid ammonia into ammonia gas using the gaseous carbon dioxide.

[0018] An air compressor is adapted to compress the introduced air and preliminarily increase the temperature of the air.

[0019] A preheater is adapted to preheat the ammonia gas output by the first cooler and the air output by the air compressor using high-temperature flue gas from the ammonia turbine and to perform secondary cooling on the high-temperature flue gas, and to deliver the preheated ammonia gas and air to the combustor for combustion.

[0020] According to an embodiment of the present disclosure, the first heat exchange device comprises:

[0021] A heat extractor is adapted to perform tertiary preheating on the supercritical carbon dioxide entering the carbon dioxide turbine using high-temperature flue gas from the ammonia turbine and to perform primary cooling on the high-temperature flue gas; a flue gas low-temperature regenerator is adapted to perform primary preheating on part of the liquid carbon dioxide from the carbon dioxide pump using the secondary cooled high-temperature flue gas, to vaporize the liquid carbon dioxide into supercritical carbon dioxide, and to perform tertiary cooling on the secondary cooled flue gas to reduce the temperature of the flue gas to the dew point.

[0022] According to an embodiment of the present disclosure, the second heat exchange device comprises:

[0023] A high-temperature regenerator is adapted to perform secondary preheating on the primary preheated supercritical carbon dioxide using supercritical carbon dioxide from the carbon dioxide turbine and to perform primary regeneration on the supercritical carbon dioxide from the carbon dioxide turbine; a carbon dioxide low-temperature regenerator is adapted to perform primary preheating on another part of the liquid carbon dioxide from the carbon dioxide pump using the primary regenerated supercritical carbon dioxide and to perform secondary regeneration on the primary regenerated supercritical carbon dioxide; and a first mixer is adapted to combine the supercritical carbon dioxide preheated by the flue gas low-temperature regenerator and the carbon dioxide low-temperature regenerator; wherein the liquid carbon dioxide from the carbon dioxide pump is split to be preheated by the flue gas low-temperature regenerator and the carbon dioxide low-temperature regenerator to match the temperature gradient between the two ends of the flue gas low-temperature regenerator.

[0024] According to an embodiment of the present disclosure, the critical phase state conversion device comprises:

[0025] An expander adapted to expand supercritical carbon dioxide from the second heat exchange device into gaseous carbon dioxide and liquid carbon dioxide; and a gas-liquid separator adapted to separate the liquid carbon dioxide and the gaseous carbon dioxide.

[0026] According to an embodiment of the present disclosure, the critical phase transition device comprises:

[0027] A vortex tube adapted to condense gaseous carbon dioxide from the second heat exchange device into liquid carbon dioxide and gaseous carbon dioxide.

[0028] According to an embodiment of the present disclosure, the mixed fuel supply device further comprises:

[0029] A second mixer adapted to mix the ammonia gas output from the first cooler and the air output from the air compressor to form a mixed gas of ammonia gas and air; and a mixed gas compressor adapted to compress the mixed gas of ammonia gas and air, and then input the compressed mixed gas into the preheater for preheating.

[0030] According to an embodiment of the present disclosure, the preheater comprises:

[0031] An air preheater adapted to preheat the air output from the air compressor using the high-temperature flue gas after the first-stage temperature reduction; and an ammonia gas preheater adapted to preheat the ammonia gas output from the first cooler using the high-temperature flue gas after the first-stage temperature reduction.

[0032] As another aspect of the present disclosure, a method for operating a combined system of the ammonia gas turbine and the self-condensation transcritical CO2 Rankine cycle is disclosed, comprising:

[0033] The mixed fuel of ammonia gas and air is delivered from the mixed fuel supply device to the combined system, and the mixed fuel is preheated to a combustible temperature and then delivered to the combustion chamber for combustion, and the heat generated by the combustion is used to do work in the ammonia turbine and output high-temperature flue gas;

[0034] The high-temperature flue gas output from the ammonia turbine is received by the first heat exchange device, and the supercritical carbon dioxide before entering the carbon dioxide turbine is heated using the high-temperature flue gas, the heated supercritical carbon dioxide enters the carbon dioxide turbine to do work and is delivered to the second heat exchange device, and the supercritical carbon dioxide from the carbon dioxide turbine is used by the second heat exchange device to heat the supercritical carbon dioxide entering the first heat exchange device;

[0035] The supercritical carbon dioxide output after being exchanged by the second heat exchange device is delivered to the critical phase transition device, and is converted into liquid carbon dioxide and gaseous carbon dioxide by the critical phase transition device, and the gaseous carbon dioxide is condensed into liquid carbon dioxide using the cold released by the vaporization of liquid ammonia in the mixed fuel supply device;

[0036] The liquid carbon dioxide is mixed and then sent to the carbon dioxide pump, and the liquid carbon dioxide is pumped by the carbon dioxide pump to the first heat exchange device and the second heat exchange device for heating and circulating in the self-condensation transcritical CO2 Rankine cycle module.

[0037] According to the embodiment of the present disclosure, in the mixed fuel supply device, liquid ammonia is pumped by a liquid ammonia pump, the liquid ammonia is vaporized by gaseous carbon dioxide in the first cooler to release cold energy and become ammonia gas, air is compressed by an air compressor, and the ammonia gas and the air are preheated in a preheater and then sent into a combustion chamber for combustion to release heat and generate high-temperature flue gas;

[0038] In the first heat exchange device, the high-temperature flue gas from the ammonia turbine enters a heat extractor, a preheater and a flue gas low-temperature regenerator in sequence to be gradually cooled by the liquid carbon dioxide pumped by the carbon dioxide pump, and the liquid carbon dioxide is gradually preheated to form supercritical carbon dioxide that is input into the carbon dioxide turbine;

[0039] In the second heat exchange device, the supercritical carbon dioxide from the carbon dioxide turbine enters a high-temperature regenerator and a carbon dioxide low-temperature regenerator in sequence to be gradually cooled, the supercritical carbon dioxide that is input into the carbon dioxide turbine is preheated, and the supercritical carbon dioxide that is gradually cooled is sent to a critical phase conversion device;

[0040] In the critical phase conversion device, the supercritical carbon dioxide from the second heat exchange device is condensed into liquid carbon dioxide and gaseous carbon dioxide, and the gaseous carbon dioxide is sent to the first cooler;

[0041] The gaseous carbon dioxide is cooled to a temperature below the critical point by the cold energy released by the vaporization of the liquid ammonia, and is condensed into liquid carbon dioxide, and the liquid carbon dioxide is mixed and then sent back to the carbon dioxide pump for circulation.

[0042] Based on the above technical solution, the combined system of the ammonia gas gas turbine and the self-condensation transcritical CO2 Rankine cycle provided by the present disclosure converts the gaseous carbon dioxide output by the second heat exchange device into liquid carbon dioxide and gaseous carbon dioxide through the critical phase conversion device, further condenses the remaining gaseous carbon dioxide into liquid carbon dioxide by the cold energy released by the vaporization of the liquid nitrogen, so as to realize the effective capture and utilization of cold and heat energy. The formed liquid carbon dioxide is sent into the first heat exchange device and the second heat exchange device for circulation, which can enhance the energy circulation efficiency of the whole system and reduce energy loss. At the same time, based on this structure, the introduction of a refrigeration cycle can be avoided, the structure of the cycle is simplified, and the number of components is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1Structure schematic diagram of combined system of ammonia gas turbine and self-condensation transcritical CO2 Rankine cycle in one embodiment of the present disclosure;

[0044] Figure 2 Structure schematic diagram of combined system of ammonia gas turbine and self-condensation transcritical CO2 Rankine cycle in another embodiment of the present disclosure;

[0045] Figure 3 Structure schematic diagram of combined system of ammonia gas turbine and self-condensation transcritical CO2 Rankine cycle with staged compression in one embodiment of the present disclosure;

[0046] Figure 4 Structure schematic diagram of combined system of ammonia gas turbine and self-condensation transcritical CO2 Rankine cycle with staged compression in another embodiment of the present disclosure.

[0047]

Explanation of reference numerals

[0048] 1-liquid ammonia pump;

[0049] 2-first cooler;

[0050] 3-air compressor;

[0051] 4-air preheater;

[0052] 5-combustion chamber;

[0053] 6-ammonia turbine;

[0054] 7-heat extractor;

[0055] 8-ammonia preheater;

[0056] 9-flue gas low-temperature regenerator;

[0057] 10-carbon dioxide pump;

[0058] 11-first mixer;

[0059] 12-carbon dioxide turbine;

[0060] 13-high-temperature regenerator;

[0061] 14-carbon dioxide low-temperature regenerator;

[0062] 15-second cooler;

[0063] 16-expander;

[0064] 17-liquid carbon dioxide mixer;

[0065] 18-gas-liquid separator;

[0066] 19-vortex tube;

[0067] 20 - mixed gas compressor;

[0068] 21 - second mixer. DETAILED DESCRIPTION

[0069] For the purposes of the present disclosure, technical solutions and advantages, the following will be described in conjunction with specific embodiments and with reference to the accompanying drawings.

[0070] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. However, it will be apparent to one skilled in the art that one or more embodiments can be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques have been omitted to avoid unnecessarily obscuring the concept of the present disclosure.

[0071] The terms used herein are merely used to describe specific embodiments and are not intended to limit the present disclosure. The terms "include", "comprise" and the like used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0072] All terms used herein, including technical and scientific terms, have meanings commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of the present specification, and should not be interpreted in an idealized or overly formal manner.

[0073] In the case of using expressions similar to "at least one of A, B, and C, etc.", in general, it should be interpreted to include one or more of the same as the meaning commonly understood by one of ordinary skill in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, a system having B alone, a system having C alone, a system having both A and B, a system having both A and C, a system having both B and C, and / or a system having A, B, and C, etc.).

[0074] The test materials and reagents used in the following examples, etc. can be obtained from commercial sources unless otherwise specified. If the specific techniques or conditions are not specified in the examples, they are conventional methods, which can be performed according to the techniques or conditions described in the literature in the art or according to the product manual.

[0075] In the process of implementing the present disclosure, it is found that the related art adopts a recycled ammonia gas cold energy gas turbine combined with a CO2 Rankine cycle to solve the problems of ammonia gas turbine waste heat utilization, liquid ammonia vaporization latent heat waste, and CO2 difficult to condense in the transcritical CO2 Rankine cycle, but still faces some challenges, including complex cycle system structure, especially when a refrigeration cycle is used to achieve partial carbon dioxide condensation, the complexity is further increased, which can lead to increased maintenance difficulty, cost and system stability. In addition, the compressor of the direct compression air consumes a lot of energy, which can lead to a decrease in the energy efficiency of the entire system and an increase in operating costs.

[0076] Therefore, the present disclosure provides an ammonia gas turbine combined with a self-condensation transcritical CO2 Rankine cycle system and an operating method thereof.

[0077] Specifically, as one aspect of the present disclosure, an ammonia gas turbine combined with a self-condensation transcritical CO2 Rankine cycle system is provided.

[0078] Figure 1 For the structure diagram of the ammonia gas turbine combined with a self-condensation transcritical CO2 Rankine cycle system in an embodiment of the present disclosure, the following is combined with Figure 1 The combined system in the present disclosure is described in detail.

[0079] Specifically, as Figure 1 indicated, the combined system mainly includes a top cycle module of the ammonia gas turbine and a bottom cycle module of the self-condensation transcritical CO2 Rankine cycle, which are coupled with each other to form the ammonia gas turbine combined with the self-condensation transcritical CO2 Rankine cycle system, including a mixed fuel supply device, a combustor (C) 5, an ammonia turbine (T-AM) 6, a carbon dioxide turbine (T-C) 12, a first heat exchange device, a second heat exchange device, a critical phase state conversion device, and a carbon dioxide pump (P-C) 10.

[0080] The mixed fuel supply device is suitable for preheating the mixed fuel including air and ammonia gas to a combustible temperature; the combustion chamber 5 is suitable for burning the mixed fuel preheated to the combustible temperature; the ammonia turbine 6 is suitable for working by using the heat generated by the combustion of the combustion chamber and outputting high-temperature flue gas; the carbon dioxide turbine 12 is suitable for working based on the self-condensation transcritical CO2 Rankine cycle; the first heat exchange device is suitable for heating the supercritical carbon dioxide before entering the carbon dioxide turbine 12 by using the high-temperature flue gas from the ammonia turbine 6; the second heat exchange device is suitable for heating the supercritical carbon dioxide entering the first heat exchange device by using the supercritical carbon dioxide from the carbon dioxide turbine 12; the critical phase state conversion device is suitable for converting the supercritical carbon dioxide output by the second heat exchange device into liquid carbon dioxide and gaseous carbon dioxide, and condensing the gaseous carbon dioxide into liquid carbon dioxide by using the cold energy released by the vaporization of liquid ammonia; and the carbon dioxide pump 10 is suitable for pumping the mixed liquid carbon dioxide to the first heat exchange device and the second heat exchange device for heating, so as to form the supercritical carbon dioxide entering the carbon dioxide turbine 12.

[0081] According to the embodiments of the present disclosure, the mixed fuel supply device includes a liquid ammonia pump (AP) 1, a first cooler (cool 1, C1) 2, an air compressor (C-A) 3, and a preheater. Figure 1 As shown in the figure, the mixed fuel supply device includes a liquid ammonia pump (AP) 1, a first cooler (cool 1, C1) 2, an air compressor (C-A) 3, and a preheater.

[0082] The liquid ammonia pump 1 is suitable for pumping liquid ammonia; the first cooler 2 is suitable for vaporizing the liquid ammonia by using the gaseous carbon dioxide and converting it into ammonia gas; the air compressor 3 is suitable for compressing the introduced air and preliminarily increasing the temperature of the air; and the preheater is suitable for preheating the ammonia gas output by the first cooler 2 and the air output by the air compressor 3 by using the high-temperature flue gas from the ammonia turbine 6 and performing secondary cooling on the high-temperature flue gas, and the preheated air is used as an oxidant and is introduced into the combustion chamber 5 together with the ammonia gas to catalyze the combustion of the ammonia gas.

[0083] According to the embodiments of the present disclosure, the liquid ammonia has good physical properties and a large latent heat of phase change, so that the natural refrigerant is often transported in a liquid state during transportation. Therefore, the liquid ammonia pump 1 is arranged to pump the liquid ammonia into the first cooler 2 for the ammonia gas turbine, the liquid ammonia at about -34°C is vaporized to release a large amount of cold energy to form ammonia gas, and the condensation demand of the gaseous carbon dioxide in the self-condensation transcritical carbon dioxide Rankine cycle is matched in the first cooler 2. The cold energy released by the vaporization of the liquid ammonia is used to reduce the temperature of the first cooler 2 to below the critical temperature (30.8°C) at which the gaseous carbon dioxide is converted into liquid, so that the gaseous carbon dioxide is condensed into liquid carbon dioxide.

[0084] According to an embodiment of the present disclosure, the air compressor 3 can also be connected to the ammonia turbine 6 to transport part of the air to the ammonia turbine 6, or to mix part of the air with the flue gas before flowing into the ammonia turbine 6, so as to adjust the temperature of the fuel gas entering the ammonia turbine 6 and improve the net efficiency of the ammonia gas turbine. The remaining small amount of air can also be used as cooling air for the turbine blades to reduce the temperature of the turbine and prevent turbine failure.

[0085] According to an embodiment of the present disclosure, the preheater includes: an air preheater (PH-A) 4 and an ammonia preheater (PH-AM) 8 .

[0086] Among them, the air preheater 4 is suitable for preheating the air output by the air compressor 3 using the high-temperature flue gas after the first stage of cooling; the ammonia preheater 8 is suitable for preheating the ammonia output by the first cooler 2 using the high-temperature flue gas after the first stage of cooling.

[0087] According to an embodiment of the present disclosure, in the ammonia gas turbine of the top cycle module, according to the flow direction of ammonia, the liquid ammonia pump 1 is connected to the cold side inlet of the first cooler 2, the cold side outlet of the first cooler 2 is connected to the cold side inlet of the ammonia preheater 8, and the cold side outlet of the ammonia preheater 8 is connected to the combustion chamber 5. According to the flow direction of air, the air compressor 3 is connected to the cold side inlet of the air preheater 4, and the cold side outlet of the air preheater 4 is connected to the combustion chamber 5. Ammonia and air are mixed in the burner 5 and then burned, generating heat and flue gas that enter the ammonia turbine to perform work, and the ammonia turbine 6 outputs high-temperature flue gas that enters the first heat exchange device.

[0088] According to the embodiments of the present disclosure, based on the characteristics of ammonia being easy to produce and low in cost, and pure ammonia not corroding metal parts, preheated ammonia and air are introduced into the combustion chamber for combustion, and the generated flue gas enters the ammonia turbine to expand and perform work, outputting electrical energy and discharging high-temperature flue gas. The heat of the high-temperature flue gas is used to preheat the ammonia and air. Under the condition of preheating, ammonia is more likely to be fully burned, while reducing NOx during the ammonia combustion process. x The production of.

[0089] According to an embodiment of the present disclosure, the first heat exchange device includes: a heat extractor (heater, H) 7 and a low temperature regenerator for flue gas (Low temperature regenerator for flue gas, LTR-F) 9.

[0090] The heat extractor 7 is adapted to use the high-temperature flue gas from the ammonia turbine 6 to preheat the supercritical carbon dioxide entering the carbon dioxide turbine 12 in three stages, and to cool the high-temperature flue gas in one stage; and the flue gas low-temperature regenerator 9 is adapted to use the high-temperature flue gas after the second-stage cooling to preheat part of the liquid carbon dioxide from the carbon dioxide pump 10 in one stage, so that the liquid carbon dioxide is vaporized to form supercritical carbon dioxide, and the flue gas after the second-stage cooling is cooled in three stages, so that the temperature of the flue gas is reduced to the dew point.

[0091] According to an embodiment of the present disclosure, in the flow direction of the high-temperature flue gas, the combustion chamber 5 is connected to the ammonia turbine 6, the outlet of the ammonia turbine 6 enters the hot-side inlet of the heat extractor 7, the hot-side outlet of the heat extractor 7 is connected to the hot-side inlet of the air preheater 4 and the hot-side inlet of the ammonia preheater 8, and the hot-side outlet of the air preheater 4 and the hot-side outlet of the ammonia preheater 8 are connected to the hot-side inlet of the flue gas low-temperature regenerator 9.

[0092] According to an embodiment of the present disclosure, the first cooler 2, the heat extractor 7, and the coupled part of the flue gas low-temperature regenerator 9 form a part of the ammonia gas turbine and a self-condensation transcritical CO2 Rankine cycle.

[0093] According to an embodiment of the present disclosure, the second heat exchange device includes a high-temperature regenerator (HTR) 13, a low-temperature regenerator for CO2 (LTR-C) 14, and a first mixer (Mixer 1, M1) 11.

[0094] The high-temperature regenerator 13 is adapted to use the supercritical carbon dioxide from the carbon dioxide turbine 12 to preheat the supercritical carbon dioxide after the first-stage preheating in two stages, and to use the supercritical carbon dioxide from the carbon dioxide turbine 12 to heat in one stage; the low-temperature regenerator for CO2 14 is adapted to use the supercritical carbon dioxide after the first-stage heating to preheat another part of the liquid carbon dioxide from the carbon dioxide pump 10 in one stage, and to use the supercritical carbon dioxide after the first-stage heating to heat in two stages; and the first mixer 11 is adapted to combine the supercritical carbon dioxide after the first-stage preheating by the flue gas low-temperature regenerator 9 and the low-temperature regenerator for CO2 14; wherein the liquid carbon dioxide from the carbon dioxide pump 10 is branched to be preheated in one stage by the flue gas low-temperature regenerator 9 and the low-temperature regenerator for CO2 14, so as to match the temperature gradient at both ends of the flue gas low-temperature regenerator 9.

[0095] According to the embodiment of the present disclosure, in the self-condensation transcritical CO2 Rankine cycle of the bottoming cycle module, the carbon dioxide pump 10 is connected to the cold side inlet of the carbon dioxide low-temperature regenerator 14 and the cold side inlet of the flue gas low-temperature regenerator 9, the cold side outlet of the carbon dioxide low-temperature regenerator 14 and the cold side outlet of the flue gas low-temperature regenerator 9 are connected to the first mixer 11, and the first mixer 11 is connected to the cold side inlet of the high-temperature regenerator 13 and the carbon dioxide turbine 12 of the heat extractor 7 in turn.

[0096] It should be noted that the specific heat of carbon dioxide near the critical point will change abruptly, and as the temperature rises, the specific heat will first increase and then decrease, which will make the temperature gradient on both sides of the low-temperature regenerator not well matched, and the pinch point problem is prone to occur.

[0097] According to the embodiment of the present disclosure, the liquid carbon dioxide is divided into the carbon dioxide low-temperature regenerator 14 and the flue gas low-temperature regenerator 9 by the carbon dioxide pump 10, which balances the problem of too rapid temperature change on the hot side, and based on the flue gas low-temperature regenerator 9, the waste heat of the high-temperature flue gas is introduced to match the energy of the regenerator, the carbon dioxide before entering the carbon dioxide turbine 12 is preheated, the temperature of the preheated CO2 is 40-60°C, the power consumption of the compressor does not need to be introduced again, the pinch point problem of the regenerator can be avoided, the flue gas exhaust temperature is effectively reduced, and the thermal pollution to the environment is reduced.

[0098] According to the embodiment of the present disclosure, the energy of each part of the ammonia gas turbine is comprehensively utilized, the cold energy generated by the latent heat of liquid ammonia vaporization condenses the gaseous carbon dioxide, and the gaseous carbon dioxide vaporizes the liquid ammonia into ammonia gas. The ammonia gas is preheated and mixed with air and then introduced into the combustion chamber for combustion, or the ammonia gas is mixed with air and then preheated and introduced into the combustion chamber for combustion. The flue gas generated by combustion outputs electric energy in the ammonia gas turbine, and the high-temperature flue gas is discharged in the heat extractor, the preheater and the flue gas low-temperature regenerator for three-stage heat recovery to release heat. Finally, the flue gas temperature can be reduced to the dew point, and the cycle net efficiency can be effectively improved.

[0099] According to the embodiment of the present disclosure, combined with Figure 1 As shown in FIG. 1, the critical phase conversion device can include an expander (E) 16 and a vapor-liquid separator (VLS) 18. The expander 16 is adapted to expand the supercritical carbon dioxide from the second heat exchange device into gaseous carbon dioxide and liquid carbon dioxide. The vapor-liquid separator 18 is adapted to separate the liquid carbon dioxide and the gaseous carbon dioxide.

[0100] Figure 2 FIG. 2 is a structural schematic diagram of an ammonia gas turbine combined with a self-condensation transcritical CO2 Rankine cycle according to another embodiment of the present disclosure.

[0101] According to the embodiments of the present disclosure, the critical phase transition device can be a vortex tube 19, and the vortex tube condenses the gaseous carbon dioxide from the second heat exchange device into liquid carbon dioxide and gaseous carbon dioxide. Figure 2 As shown, the critical phase transition device can also be a vortex tube 19, and the vortex tube condenses the gaseous carbon dioxide from the second heat exchange device into liquid carbon dioxide and gaseous carbon dioxide.

[0102] According to the embodiments of the present disclosure, the supercritical carbon dioxide after the step-by-step preheating enters the carbon dioxide turbine 12 to do work and outputs high-temperature supercritical carbon dioxide. According to the carbon dioxide flow meter on the high-temperature side, the carbon dioxide turbine 12, the high-temperature regenerator 13, and the carbon dioxide low-temperature regenerator 14 are sequentially connected. The carbon dioxide low-temperature regenerator 14 is sequentially connected with the expander 16 and the gas-liquid separator 18. The gas outlet of the gas-liquid separator 18 is connected with the first cooler 2. The gaseous carbon dioxide is condensed into liquid carbon dioxide in the first cooler 2 through heat exchange with liquid ammonia. The liquid carbon dioxide output from the liquid outlet of the gas-liquid separator 18 is combined with the liquid carbon dioxide to enter the carbon dioxide pump 10, thereby forming a closed loop for circulation.

[0103] According to the embodiments of the present disclosure, the carbon dioxide enters the two-phase state through the expander 16, and then the liquid and gaseous carbon dioxide are separated through the gas-liquid separator 18, so as to realize the condensation of part of the carbon dioxide. The remaining gaseous carbon dioxide is condensed by using the cold energy released by the latent heat of vaporization of the liquid ammonia in the first cooler 2. The condensation of the carbon dioxide can be realized without the aid of a traditional cooling tower or a refrigeration cycle.

[0104] According to the embodiments of the present disclosure, the carbon dioxide low-temperature regenerator 14 can also be selectively connected with the vortex tube 19 to condense and gas-liquid separate the supercritical carbon dioxide. The carbon dioxide low-temperature regenerator 14 and the critical phase transition device can also be connected with the second cooler 15 to further cool the supercritical carbon dioxide. The liquid carbon dioxide mixer 17 can be arranged after the gas-liquid separator 18 and the first cooler 2 or the vortex tube 19 and the first cooler 2 according to the needs, so that the liquid carbon dioxide is mixed and then combined into the carbon dioxide pump 10.

[0105] According to the embodiments of the present disclosure, the characteristics of the carbon dioxide being in a liquid state below the critical temperature are comprehensively utilized. The pump has a high isentropic efficiency. The supercritical fluid state has a small overall land occupation area, a high heat release efficiency, and a small loss. The utilization of the expander 16 and the gas-liquid separator 18 or the utilization of the vortex tube 19 realizes the condensation of the supercritical carbon dioxide in the self-condensation transcritical carbon dioxide cycle. The combination of the first cooler 2 makes the gaseous carbon dioxide all condensed into liquid carbon dioxide, avoids the introduction of a refrigeration cycle, can simplify the structure of the cycle, reduces the number of structural components, and improves the cycle efficiency. The replacement of the expander 16 and the gas-liquid separator 18 with the vortex tube 19 can realize the same condensation effect, can avoid the relatively easy failure of the expander device, increases the reliability of the system, and reduces the complexity of the system.

[0106] Figure 3 Structure diagram of the combined system of ammonia gas turbine and self-condensation transcritical CO2 Rankine cycle with staged compression in an embodiment of the present disclosure.

[0107] According to an embodiment of the present disclosure, the combined system combines the improvements of the mixed fuel supply device and the critical phase state conversion device, further increases the reliability of the system, reduces the complexity of the system, and reduces the temperature difference of the inter-stage air and the power consumption of the compressed air, thereby effectively improving the cycle efficiency. Figure 3 As shown in the figure, the mixed fuel supply device can further include a second mixer 21 and a mixed gas compressor 20, wherein the second mixer 21 is suitable for mixing the ammonia gas output by the first cooler 2 and the air output by the air compressor 3 to form a mixed gas of ammonia and air; and the mixed gas compressor 20 is suitable for compressing the mixed gas of ammonia and air, and then feeding the compressed mixed gas into the preheater for preheating.

[0108] According to an embodiment of the present disclosure, the air is introduced by the air compressor 3, and the temperature of the air is initially increased by compression. The compressed air is mixed with the ammonia gas from the first cooler 2 in the second mixer 21, and then enters the mixed gas compressor 20 for further compression, so as to realize the staged compression of the air. Compared with the prior art, the staged compression can reduce the temperature difference of the air between the two stages of compression, reduce the power consumption of the compressed air, and improve the cycle efficiency. Figure 1 In the prior art, the air and the ammonia gas are compressed and preheated separately, and then mixed in the combustion chamber, Figure 3 In the prior art, the air and the ammonia gas are compressed and preheated separately, and then mixed in the combustion chamber,

[0109] Figure 4 Structure diagram of the combined system of ammonia gas turbine and self-condensation transcritical CO2 Rankine cycle with staged compression in another embodiment of the present disclosure.

[0110] According to an embodiment of the present disclosure, the combined system combines the improvements of the mixed fuel supply device and the critical phase state conversion device, further increases the reliability of the system, reduces the complexity of the system, and reduces the temperature difference of the inter-stage air and the power consumption of the compressed air, thereby effectively improving the cycle efficiency. Figure 4 As shown in the figure, the combined system combines the improvements of the mixed fuel supply device and the critical phase state conversion device, further increases the reliability of the system, reduces the complexity of the system, and reduces the temperature difference of the inter-stage air and the power consumption of the compressed air, thereby effectively improving the cycle efficiency.

[0111] As another aspect of the present disclosure, a method for operating the combined system of ammonia gas turbine and self-condensation transcritical CO2 Rankine cycle is disclosed, which comprises the following steps:

[0112] The mixed fuel supply device delivers the mixed fuel of ammonia and air to the combined system, and preheats the mixed fuel to a combustible temperature before delivering it to the combustion chamber 5 for combustion. The heat generated by the combustion does work in the ammonia turbine 6, and outputs high-temperature flue gas.

[0113] The high-temperature flue gas output by the ammonia gas turbine 6 is received by the first heat exchange device, and the supercritical carbon dioxide before entering the carbon dioxide turbine 12 is heated by using the high-temperature flue gas. The heated supercritical carbon dioxide enters the carbon dioxide turbine 12 to expand and do work and is transported to the second heat exchange device. The supercritical carbon dioxide from the carbon dioxide turbine 12 is used by the second heat exchange device to heat the supercritical carbon dioxide entering the first heat exchange device.

[0114] The supercritical carbon dioxide output after heat exchange by the second heat exchange device is transported to the critical phase state conversion device, and is converted into liquid carbon dioxide and gaseous carbon dioxide by using the critical phase state conversion device. The gaseous carbon dioxide is condensed into liquid carbon dioxide by using the cold energy released by the vaporization of liquid ammonia in the mixed fuel supply device.

[0115] The liquid carbon dioxide is transported to the carbon dioxide pump 10 after being merged, and the liquid carbon dioxide is pumped by the carbon dioxide pump 10 to the first heat exchange device and the second heat exchange device for heating, and circulates in the self-condensation transcritical CO2 Rankine cycle module.

[0116] According to the embodiments of the present disclosure, in the mixed fuel supply device, the liquid ammonia is pumped by the liquid ammonia pump 1, the liquid ammonia is vaporized by using the gaseous carbon dioxide in the first cooler 2 to release cold energy and convert into ammonia gas, the air is compressed by using the air compressor 3, and the ammonia gas and the air are preheated in the preheater and then transported into the combustion chamber 5 for combustion to release heat and generate high-temperature flue gas.

[0117] According to the embodiments of the present disclosure, in the first heat exchange device, the high-temperature flue gas from the ammonia gas turbine 6 enters the heat extractor 7, the preheater, and the flue gas low-temperature regenerator 9 in sequence to be gradually cooled by using the liquid carbon dioxide pumped from the carbon dioxide pump 10, while realizing the gradual preheating of the liquid carbon dioxide, forming the supercritical carbon dioxide entering the carbon dioxide turbine 12.

[0118] According to the embodiments of the present disclosure, in the second heat exchange device, the supercritical carbon dioxide from the carbon dioxide turbine 12 enters the high-temperature regenerator 13 and the carbon dioxide low-temperature regenerator 14 in sequence to be gradually cooled, while realizing the preheating of the supercritical carbon dioxide transported to the carbon dioxide turbine 12, and the gradually cooled supercritical carbon dioxide is transported to the critical phase state conversion device.

[0119] According to the embodiments of the present disclosure, in the critical phase state conversion device, the supercritical carbon dioxide from the second heat exchange device is condensed into liquid carbon dioxide and gaseous carbon dioxide, and the gaseous carbon dioxide is transported to the first cooler 2.

[0120] According to the embodiment of the present disclosure, the cold energy released by the vaporization of liquid ammonia is utilized to cool the gaseous carbon dioxide to a temperature below the critical point, condense the gaseous carbon dioxide into liquid carbon dioxide, and mix the liquid carbon dioxide and then send it back to the carbon dioxide pump 10 for circulation.

[0121] The following will be described in detail Figure 1 The operation method of the combined system of the ammonia gas turbine and the self-condensation transcritical CO2 Rankine cycle will be described in detail.

[0122] In the ammonia gas turbine of the top cycle module, the liquid ammonia is pumped to the first cooler 2 after being pressurized by the liquid ammonia pump 1 for heat exchange, a large amount of cold energy is released by the vaporization of the liquid ammonia to convert into ammonia gas, and the cold energy is utilized to condense the gaseous carbon dioxide in the self-condensation transcritical CO2 Rankine cycle into liquid carbon dioxide. The ammonia gas enters the ammonia preheater 8, and is heated to a combustible temperature by using the high-temperature flue gas output from the ammonia turbine 6. At the same time, the air is introduced and compressed by the air compressor 3, the temperature of the air is preliminarily raised, and then the air is heated by using the heat of the high-temperature flue gas in the air preheater 4. The heated air is mixed with the ammonia gas in the combustion chamber 5 as an oxidizer to combust and release heat. In the flue gas generated by the combustion, part of the air can be mixed to adjust the flue gas temperature and improve the efficiency of the ammonia gas turbine cycle, and a small amount of air can be utilized as the cooling gas of the ammonia turbine blade.

[0123] The flue gas expands to do work in the ammonia turbine 6 to output electric energy to the outside, and the high-temperature flue gas is discharged. The high-temperature flue gas is heated to the supercritical carbon dioxide in the heat extractor 7 to perform first-stage cooling; is further heated to the air and the ammonia gas in the air preheater 4 and the ammonia preheater 8 to perform second-stage cooling; and then enters the flue gas low-temperature regenerator 9 to heat the liquid carbon dioxide pumped by the carbon dioxide pump 10 to perform third-stage cooling, so as to adjust the heat distribution on both sides of the flue gas low-temperature regenerator and avoid the occurrence of pinch point. The temperature of the flue gas after the third-stage cooling is reduced to the vicinity of the dew point, and the energy contained in the flue gas is efficiently converted.

[0124] In the self-condensation transcritical CO2 Rankine cycle of the bottom cycle module, the liquid carbon dioxide is pressurized from the carbon dioxide pump 10, and is divided to perform first-stage preheating of the carbon dioxide in the flue gas low-temperature regenerator 9 and the carbon dioxide low-temperature regenerator 14; the supercritical carbon dioxide formed after the first-stage preheating is mixed in the first mixer 11 and then enters the high-temperature regenerator 13 to perform second-stage preheating; and then enters the heat extractor 7 to perform third-stage preheating. The supercritical carbon dioxide after the third-stage preheating enters the carbon dioxide turbine 12, expands to do work in the carbon dioxide turbine 12 to output electric energy to the outside, and outputs high-temperature supercritical carbon dioxide.

[0125] The supercritical carbon dioxide output by the carbon dioxide turbine 12 enters the high-temperature regenerator 13 for one-stage heat recovery, enters the carbon dioxide low-temperature regenerator 14 for two-stage heat recovery, and the supercritical carbon dioxide cooled by the step-by-step heat recovery can be cooled again in the second cooler 15. The cooled supercritical carbon dioxide enters the expander 16 to be converted into liquid carbon dioxide and gaseous carbon dioxide, and then the gaseous carbon dioxide is delivered to the first cooler 2 by the gas-liquid separator 18, and condensed into liquid carbon dioxide by using the cold energy generated by the vaporization of liquid ammonia. The liquid carbon dioxide is mixed by the liquid carbon dioxide mixer 17 and sent back to the carbon dioxide pump 10 to complete a cycle.

[0126] Based on the above technical solution, through energy comprehensive utilization, the temperature gradient is designed to be matched, based on the comprehensive utilization of flue gas in the ammonia gas turbine unit, the effective utilization of liquid ammonia cold energy, and the coupling utilization of energy in the combined cycle of the Rankine cycle with carbon dioxide as the working medium, the gaseous flow in the gas-liquid separation process (i.e. self-condensation process) of the self-condensation transcritical CO2 Rankine cycle is matched with the liquid ammonia cold energy (i.e. latent heat of vaporization), and the three-stage cooling and split-flow heat recovery technology of the high-temperature flue gas discharged by the ammonia gas turbine is adopted, the structure is more simple, not only can realize higher cycle efficiency, but also can realize zero carbon emission, and in the ideal state, environmental pollution can be avoided.

[0127] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present disclosure, and it should be understood that the above are only specific embodiments of the present disclosure and are not used to limit the present disclosure, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A combined system of ammonia gas turbine and self-condensing transcritical CO2 Rankine cycle, comprising: a mixed fuel supply device adapted to preheat a mixed fuel comprising air and ammonia to a combustible temperature; a combustion chamber (5) adapted to combust the mixed fuel preheated to the combustible temperature; an ammonia turbine (6) adapted to work using heat generated by combustion in the combustion chamber and output high-temperature flue gas; a carbon dioxide turbine (12) adapted to work based on a self-condensing transcritical CO2 Rankine cycle; a first heat exchange device adapted to heat supercritical carbon dioxide before entering the carbon dioxide turbine (12) using high-temperature flue gas from the ammonia turbine (6); a second heat exchange device adapted to heat supercritical carbon dioxide entering the first heat exchange device using supercritical carbon dioxide from the carbon dioxide turbine (12); a critical phase transition device adapted to convert supercritical carbon dioxide output by the second heat exchange device into liquid carbon dioxide and gaseous carbon dioxide, and condense gaseous carbon dioxide into liquid carbon dioxide using cold released by ammonia vaporization; and a carbon dioxide pump (10) adapted to pump liquid carbon dioxide mixed to the first heat exchange device and the second heat exchange device for heating to form supercritical carbon dioxide entering the carbon dioxide turbine (12).

2. The combined system according to claim 1, wherein the mixed fuel supply device comprises: a liquid ammonia pump (1) adapted to pump liquid ammonia; a first cooler (2) adapted to vaporize the liquid ammonia using gaseous carbon dioxide and convert into ammonia gas; an air compressor (3) adapted to compress introduced air and preliminarily increase temperature of the air; a preheater adapted to preheat ammonia gas output by the first cooler (2) and air output by the air compressor (3) using high-temperature flue gas from the ammonia turbine (6) and perform secondary cooling of the high-temperature flue gas, and deliver the preheated ammonia gas and air to the combustor (5) for combustion.

3. The combined system according to claim 2, wherein the first heat exchange device comprises: a heat extractor (7) adapted to perform tertiary preheating of supercritical carbon dioxide entering the carbon dioxide turbine (12) using high-temperature flue gas from the ammonia turbine (6) and perform primary cooling of the high-temperature flue gas; a flue gas low-temperature recuperator (9) adapted to perform primary preheating of part of liquid carbon dioxide from the carbon dioxide pump (10) using the high-temperature flue gas after secondary cooling, vaporize the liquid carbon dioxide to form supercritical carbon dioxide, and perform tertiary cooling of the flue gas after secondary cooling to reduce temperature of the flue gas to dew point.

4. The combined system according to claim 3, wherein the second heat exchange device comprises: a high-temperature recuperator (13) adapted to perform secondary preheating of supercritical carbon dioxide after primary preheating using supercritical carbon dioxide from the carbon dioxide turbine (12), and perform primary recuperation of supercritical carbon dioxide from the carbon dioxide turbine (12). a carbon dioxide low temperature recuperator (14) adapted to preheat another portion of the liquid carbon dioxide from the carbon dioxide pump (10) using supercritical carbon dioxide after the first stage of preheating and to preheat the supercritical carbon dioxide after the first stage of preheating; and a first mixer (11) adapted to mix the supercritical carbon dioxide after the first stage of preheating by the flue gas low temperature recuperator and the carbon dioxide low temperature recuperator; wherein the liquid carbon dioxide from the carbon dioxide pump (10) is divided into two portions and preheated by the flue gas low temperature recuperator (9) and the carbon dioxide low temperature recuperator (14) to match the temperature gradient at both ends of the flue gas low temperature recuperator (9).

5. The combined system according to any one of claims 1-4, wherein the critical phase transition device comprises: an expander (16) adapted to expand the supercritical carbon dioxide from the second heat exchange device into gaseous carbon dioxide and liquid carbon dioxide; and a gas-liquid separator (18) adapted to separate the liquid carbon dioxide and the gaseous carbon dioxide.

6. The combined system according to any one of claims 1-4, wherein the critical phase transition device comprises: a vortex tube (19) adapted to condense the supercritical carbon dioxide from the second heat exchange device into liquid carbon dioxide and gaseous carbon dioxide.

7. The combined system according to claim 2, wherein the mixed fuel supply device further comprises: a second mixer (21) adapted to mix the ammonia gas outputted from the first cooler (2) and the air outputted from the air compressor (3) to form a mixed gas of ammonia gas and air; a mixed gas compressor (20) adapted to compress the mixed gas of ammonia gas and air and to input the compressed mixed gas into the preheater for preheating.

8. The combined system according to claim 3, wherein the preheater comprises: an air preheater (4) adapted to preheat the air outputted from the air compressor (3) using the high temperature flue gas after the first stage of cooling; and an ammonia gas preheater (8) adapted to preheat the ammonia gas outputted from the first cooler (2) using the high temperature flue gas after the first stage of cooling.

9. A method for operating the combined system according to any one of claims 1-8, comprising: supplying a mixed fuel of ammonia gas and air into the combined system by the mixed fuel supply device and preheating the mixed fuel to a combustible temperature and then inputting the preheated mixed fuel into the combustion chamber (5) for combustion, the heat generated by the combustion is used to drive the ammonia turbine (6) and output high temperature flue gas; receiving the high temperature flue gas outputted from the ammonia turbine (6) by the first heat exchange device, using the high temperature flue gas to heat the supercritical carbon dioxide before entering the carbon dioxide turbine (12), the heated supercritical carbon dioxide enters the carbon dioxide turbine (12) to expand and drive and is then inputted into the second heat exchange device, using the supercritical carbon dioxide from the carbon dioxide turbine (12) to heat the supercritical carbon dioxide entering the first heat exchange device by the second heat exchange device. The supercritical carbon dioxide outputted after heat exchange by the second heat exchange device is transported to a critical phase conversion device, and is converted into liquid carbon dioxide and gaseous carbon dioxide by the critical phase conversion device, and the gaseous carbon dioxide is condensed into liquid carbon dioxide by the cold energy released by vaporization of the liquid ammonia in the mixed fuel supply device; The liquid carbon dioxide is mixed and then transported to a carbon dioxide pump (10), and the liquid carbon dioxide is pumped by the carbon dioxide pump (10) to the first heat exchange device and the second heat exchange device for heating and circulating in the self-condensation transcritical CO2 Rankine cycle module.

10. The operation method according to claim 9, wherein, In the mixed fuel supply device, the liquid ammonia is pumped by a liquid ammonia pump (1), the liquid ammonia is vaporized by gaseous carbon dioxide in a first cooler (2) to release cold energy to be converted into ammonia gas, air is compressed by an air compressor (3), and the ammonia gas and the air are preheated in a preheater and then transported into a combustion chamber (5) for combustion to release heat and generate high-temperature flue gas; In the first heat exchange device, the high-temperature flue gas from the ammonia gas turbine (6) enters a heat extractor (7), a preheater and a flue gas low-temperature regenerator (9) in sequence to be gradually cooled by the liquid carbon dioxide pumped by a carbon dioxide pump (10), and the liquid carbon dioxide is gradually preheated to form supercritical carbon dioxide which is inputted into a carbon dioxide turbine (12); In the second heat exchange device, the supercritical carbon dioxide from the carbon dioxide turbine (12) enters a high-temperature regenerator (13) and a carbon dioxide low-temperature regenerator (14) in sequence to be gradually cooled, the supercritical carbon dioxide transported into the carbon dioxide turbine (12) is preheated, and the supercritical carbon dioxide after gradual cooling is transported to the critical phase conversion device; In the critical phase conversion device, the supercritical carbon dioxide from the second heat exchange device is condensed into liquid carbon dioxide and gaseous carbon dioxide, and the gaseous carbon dioxide is transported to the first cooler (2); The gaseous carbon dioxide is cooled to a temperature below the critical point by the cold energy released by vaporization of the liquid ammonia, is condensed into liquid carbon dioxide, and the liquid carbon dioxide is mixed and then returned to the carbon dioxide pump (10) for circulation.

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