An Allam power cycle system and method for low-pressure liquid carbon dioxide storage

Abstract

This invention relates to the field of carbon dioxide sequestration technology, and in particular to an Allam power cycle system and method for low-pressure liquid carbon dioxide sequestration. The Allam power cycle system for low-pressure liquid carbon dioxide sequestration includes a combustion chamber, a turbine, a regenerator, a cooler, a gas-liquid separator, a carbon dioxide compressor, a condenser, a liquid separator, a flash tank, and a carbon dioxide sequestration tank. This invention utilizes a compressor to compress cooled and dehydrated carbon dioxide, increasing its pressure so that it can be condensed into a liquid state using water. Subsequently, a flash tank is used to flash-evaporate a portion of the higher-pressure liquid carbon dioxide into low-pressure liquid carbon dioxide and low-pressure gaseous carbon dioxide. The low-pressure liquid carbon dioxide is then sent to the sequestration tank for storage, achieving low-pressure liquid carbon dioxide sequestration. Compared to existing technologies, this effectively reduces the cost of carbon dioxide sequestration and the risk of leakage.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide sequestration technology, and in particular to an Allam power cycle system and method for low-pressure liquid carbon dioxide sequestration. Background Technology

[0002] With the increasing severity of global warming caused by excessive emissions of greenhouse gases such as carbon dioxide, reducing carbon dioxide emissions from production processes is of great practical significance. As a major source of carbon emissions, the power generation industry relies on advanced low-carbon power generation technologies as the future direction of power generation technology development.

[0003] The Allam power cycle system is an oxygen-enriched combustion power cycle system that uses carbon dioxide as the working fluid. Because it uses pure oxygen instead of air as the oxidant in the combustion reaction, the concentration of carbon dioxide in the combustion products is high, effectively reducing the cost of carbon dioxide capture and storage. Furthermore, since no nitrogen is present, no NOx harmful gases are produced.

[0004] Because carbon dioxide has a low condensation temperature, only 5.3°C at 4 MPa pressure, it is difficult to condense carbon dioxide at low pressure into a liquid state using water as a cold source. Therefore, in existing technologies, the carbon dioxide captured and stored in the Allam power cycle system cannot be stored in liquid form. Systems that do use liquid storage suffer from high storage pressure or reliance on cold sources such as LNG. Storing the captured carbon dioxide in gaseous form results in a large footprint and high storage costs. High storage pressure leads to high tank costs and risks of leakage. Reliance on cold sources such as LNG for condensation results in low system flexibility and is not easily promoted. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems of large footprint, high storage cost, and easy leakage of carbon dioxide gaseous storage, the present invention is proposed.

[0007] Therefore, the object of the present invention is to provide an Allam power cycle system with low-pressure liquid carbon dioxide storage.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an Allam power cycle system with low-pressure liquid carbon dioxide storage, comprising a combustion chamber, a turbine, a regenerator, a cooler, a gas-liquid separator, a carbon dioxide compressor, a condenser, a liquid separator, a flash tank, and a carbon dioxide storage tank. The combustion chamber is connected to the turbine, the turbine is connected to the regenerator, the regenerator is connected to the cooler, the cooler is connected to the gas-liquid separator, the gas-liquid separator is connected to the carbon dioxide compressor, the carbon dioxide compressor is connected to the condenser, the condenser is connected to the liquid separator, the liquid separator is simultaneously connected to both the flash tank and the regenerator, and the flash tank is simultaneously connected to both the gas-liquid separator and the flash tank. The carbon dioxide compressor and the carbon dioxide storage tank are connected. The carbon dioxide compressor is used to pressurize the carbon dioxide gas flowing out of the gas-liquid separator and the carbon dioxide gas flowing out of the flash tank. The condenser is used to condense the compressed carbon dioxide gas into liquid carbon dioxide. The liquid separator is used to send the liquid carbon dioxide into the flash tank and the regenerator respectively. The carbon dioxide sent into the regenerator rejoins the power cycle. The flash tank depressurizes the liquid carbon dioxide and flashes it into low-pressure liquid carbon dioxide and low-pressure gaseous carbon dioxide. The low-pressure gaseous carbon dioxide mixes with the gaseous carbon dioxide flowing out of the gas-liquid separator and then enters the carbon dioxide compressor. The carbon dioxide storage tank is used to store the low-pressure liquid carbon dioxide.

[0009] As a preferred embodiment of the Allam power cycle system with low-pressure liquid carbon dioxide storage described in this invention, the cooler is used to cool the turbine exhaust to a certain temperature, the water in the turbine exhaust is cooled into a liquid state, the gas-liquid separator separates the liquid water and discharges it from the system, the turbine exhaust becomes pure carbon dioxide gas, the combustion chamber is used to burn fuel to provide working fluid for the turbine, and the regenerator is used to absorb energy in the turbine exhaust to improve the system cycle efficiency.

[0010] As a preferred embodiment of the Allam power cycle system with low-pressure liquid carbon dioxide storage described in this invention, wherein: an oxygen compressor is provided at the front end of the combustion chamber, the oxygen compressor is used to provide pure oxygen to the combustion chamber, and the regenerator is divided into a high-temperature regenerator and a low-temperature regenerator.

[0011] As a preferred embodiment of the Allam power cycle system with low-pressure liquid carbon dioxide storage described in this invention, the low-temperature regenerator receives turbine exhaust gas discharged from the high-temperature regenerator and low-temperature carbon dioxide discharged from the liquid separator. The low-temperature carbon dioxide is heated by the turbine exhaust gas, and after cooling, the turbine exhaust gas is sent to a cooler for further cooling. The heated low-temperature carbon dioxide is then sent to the high-temperature regenerator and the turbine, where it is further heated by the turbine exhaust gas and used as a cooling gas to cool the turbine rotor and blades within the turbine.

[0012] As a preferred embodiment of the Allam power cycle system for low-pressure liquid storage of carbon dioxide described in this invention, the high-temperature regenerator receives turbine exhaust and low-temperature carbon dioxide fed into the low-temperature regenerator, heats the low-temperature carbon dioxide with turbine exhaust, sends the cooled turbine exhaust into the low-temperature regenerator, and sends the heated low-temperature carbon dioxide into the combustion chamber to mix with the combustion products before entering the turbine to expand and do work.

[0013] As a preferred embodiment of the Allam power cycle system for low-pressure liquid carbon dioxide storage described in this invention, a carbon dioxide working fluid pump is provided between the liquid separator and the low-temperature regenerator, and the carbon dioxide working fluid pump is used to pressurize the low-pressure liquid carbon dioxide separated by the liquid separator.

[0014] As a preferred embodiment of the Allam power cycle system with low-pressure liquid carbon dioxide storage described in this invention, the combustion chamber is simultaneously supplied with oxygen, natural gas and carbon dioxide, and the combustion products of the combustion chamber are sent into the turbine to perform work.

[0015] The beneficial effects of the Allam power cycle system for low-pressure liquid carbon dioxide storage described in this invention are as follows: This invention utilizes a compressor to compress cooled and dehydrated carbon dioxide, increasing its pressure so that it can be condensed into a liquid state using water. Subsequently, a flash evaporator is used to flash-evaporate a portion of the higher-pressure liquid carbon dioxide into low-pressure liquid carbon dioxide and low-pressure gaseous carbon dioxide. The low-pressure liquid carbon dioxide is then sent to a storage tank for storage, achieving low-pressure liquid carbon dioxide storage. Compared to existing technologies, this effectively reduces the cost of carbon dioxide storage and the risk of leakage.

[0016] This invention also provides the following technical solution: a method for low-pressure liquid carbon dioxide storage, used in the Allam power cycle system for the aforementioned low-pressure liquid carbon dioxide storage, further comprising the following steps:

[0017] S1, the combustion chamber produces combustion products by burning pure oxygen and natural gas, and the combustion products are mixed with carbon dioxide and then fed into the turbine;

[0018] S2, the turbine expands and does work through the mixed combustion products, outputting energy to the outside. The turbine exhaust generated after the turbine does work is discharged and input to the high-temperature regenerator.

[0019] S3, turbine exhaust enters the high-temperature regenerator from the hot side, heating the carbon dioxide on the cold side of the high-temperature regenerator;

[0020] S4, the cooled turbine exhaust flows from the hot side into the low-temperature regenerator to heat the carbon dioxide on the cold side of the low-temperature regenerator. The cooled turbine exhaust flows into the cooler to cool the water in the turbine exhaust into a liquid state.

[0021] S5, after the turbine exhaust is cooled, gas-liquid separation is performed. The water in it is separated out of the system in liquid form, and the turbine exhaust becomes pure carbon dioxide gas. The pure carbon dioxide gas is then compressed and condensed into liquid carbon dioxide.

[0022] S6, liquid carbon dioxide is separated into two parts, a small part is flashed, and the other part is pressurized and sent back to the cold side of the low-temperature regenerator to rejoin the power cycle;

[0023] S7, after flash evaporation, liquid carbon dioxide is converted into low-pressure liquid carbon dioxide and low-pressure gaseous carbon dioxide. The low-pressure liquid carbon dioxide enters the carbon dioxide storage tank for storage, and the low-pressure gaseous carbon dioxide flows back to the inlet of the carbon dioxide compressor and mixes with the pure carbon dioxide gas separated by the gas-liquid separator. This is a preferred embodiment of the low-pressure liquid carbon dioxide storage method of the present invention. In S4, after the carbon dioxide on the cold side of the low-temperature regenerator is heated, it is sent to the cold side of the high-temperature regenerator for further heating by turbine exhaust and sent to the cooling gas inlet of the turbine to cool the blades inside the turbine.

[0024] As a preferred embodiment of the low-pressure liquid carbon dioxide storage method of the present invention, the liquid carbon dioxide in S7 is heated by the low-temperature regenerator and then turns back into gaseous carbon dioxide. The gaseous carbon dioxide enters the high-temperature regenerator and is further heated by the turbine exhaust and enters the turbine to cool the blades and rotor. The gaseous carbon dioxide heated by the high-temperature regenerator enters the combustion chamber and mixes with the combustion products to serve as the working fluid for turbine expansion and work.

[0025] The beneficial effects of the carbon dioxide low-pressure liquid storage method described in this invention are as follows: This invention enables low-pressure liquid storage of carbon dioxide during the operation of the Allam power cycle system, reducing the footprint, lowering storage costs, and reducing leakage due to the lower storage pressure. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0027] Figure 1 A schematic diagram of the Allam power cycle system for low-pressure liquid storage of carbon dioxide.

[0028] Figure 2 A schematic diagram of the high-temperature regenerator of the Allam power cycle system, which stores carbon dioxide in a low-pressure liquid state.

[0029] Figure 3 This is a flowchart of a low-pressure liquid carbon dioxide storage method. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0033] Example 1

[0034] Reference Figures 1-2This is the first embodiment of the present invention, which provides an Allam power cycle system with low-pressure liquid carbon dioxide storage, including a combustion chamber 2, a turbine 3, a regenerator, a cooler 6, a gas-liquid separator 7, a carbon dioxide compressor 8, a condenser 9, a liquid separator 10, a flash tank 12, and a carbon dioxide storage tank 13. The combustion chamber 2 is connected to the turbine 3, the turbine 3 is connected to the regenerator, the regenerator is connected to the cooler 6, the cooler 6 is connected to the gas-liquid separator 7, the gas-liquid separator 7 is connected to the carbon dioxide compressor 8, the carbon dioxide compressor 8 is connected to the condenser 9, the condenser 9 is connected to the liquid separator 10, the liquid separator 10 is simultaneously connected to the flash tank 12 and the regenerator, and the flash tank 12 is simultaneously connected to the carbon dioxide compressor 8 and the carbon dioxide storage tank 13. The cooler 6 is used to dissipate the exhaust gas from the turbine. The gas is cooled to a certain temperature, which cools the water in the turbine exhaust into a liquid state. The gas-liquid separator 7 separates the liquid water and discharges it from the system. The turbine exhaust becomes pure carbon dioxide gas. The carbon dioxide compressor 8 is used to pressurize the carbon dioxide gas flowing out of the gas-liquid separator 7 and the carbon dioxide gas flowing out of the flash tank 12. The condenser 9 is used to condense the compressed carbon dioxide gas into liquid carbon dioxide. The liquid separator 10 is used to send the liquid carbon dioxide into the flash tank 12 and the regenerator respectively. The carbon dioxide sent into the regenerator rejoins the power cycle. The flash tank 12 depressurizes the liquid carbon dioxide and flashes it into low-pressure liquid carbon dioxide and low-pressure gaseous carbon dioxide. The low-pressure gaseous carbon dioxide mixes with the gaseous carbon dioxide flowing out of the gas-liquid separator 7 and then enters the carbon dioxide compressor 8. The carbon dioxide storage tank 13 is used to store the low-pressure liquid carbon dioxide.

[0035] Specifically, combustion chamber 2 releases heat by burning natural gas. The combustion products mixed with carbon dioxide entering combustion chamber 2 flow into turbine 3 to expand and do work. Turbine 3 outputs energy. The exhaust gas produced by turbine 3 is cooled by the regenerator and then enters cooler 6 for further cooling. The water in the turbine exhaust gas is cooled into a liquid state. After being separated by gas-liquid separator 7, the liquid water in the turbine exhaust gas is discharged. The remaining gaseous carbon dioxide is compressed by carbon dioxide compressor 8 and then enters condenser 9 for condensation into liquid carbon dioxide. Subsequently, the liquid carbon dioxide is separated into two parts by liquid separator 10. One part enters flash tank 12 for flash depressurization. During the flash process, the liquid carbon dioxide becomes low-pressure liquid carbon dioxide and low-pressure gaseous carbon dioxide. The low-pressure liquid carbon dioxide is sent to carbon dioxide storage tank 13 for storage, and the low-pressure gaseous carbon dioxide is sent back to carbon dioxide compressor 8 for recompression and condensation. The other part directly returns to the regenerator for heating and re-participates in the power cycle.

[0036] Furthermore, the combustion chamber 2 is used to burn fuel to provide working fluid for the turbine 3 to expand and do work, and the regenerator is used to recover energy from the turbine exhaust to improve system efficiency.

[0037] Furthermore, an oxygen compressor 1 is provided at the front end of the combustion chamber 2. The oxygen compressor 1 is used to supply pure oxygen to the combustion chamber 2. The regenerator is divided into a high-temperature regenerator 4 and a low-temperature regenerator 5.

[0038] Specifically, the oxygen compressor 1 has a gas supply port and a gas delivery port, and the combustion chamber 2 has an oxygen inlet 21, a natural gas inlet 22, a carbon dioxide inlet 23, and a combustion product outlet 24. The oxygen compressor 1 compresses pure oxygen and sends it to the oxygen inlet 21 of the combustion chamber 2 through the gas delivery port 12. The natural gas inlet 22 is used to connect to the external natural gas supply. After the pure oxygen and natural gas are burned, the combustion products mix with the carbon dioxide entering the combustion chamber 2 through the carbon dioxide inlet 23 and then enter the turbine 3 as the working fluid from the combustion product outlet 24 to expand and do work. The turbine 3 has a working fluid inlet, a cooling gas inlet 32, and a working fluid outlet. The working fluid inlet is connected to the combustion outlet of the combustion chamber 2, and the exhaust gas after the turbine 3 has done work is discharged through the working fluid outlet.

[0039] Example 2

[0040] Reference Figures 1-2 This is the second embodiment of the present invention. Unlike the previous embodiment, the low-temperature regenerator 5 receives the turbine exhaust gas discharged from the high-temperature regenerator 4 and the low-temperature carbon dioxide discharged from the liquid separator 10. The low-temperature carbon dioxide is heated by the turbine exhaust gas, and after cooling, the turbine exhaust gas is sent to the cooler 6 for cooling. The heated low-temperature carbon dioxide is sent to the high-temperature regenerator 4 and the turbine 3 respectively. In the high-temperature regenerator 4, it is further heated by the turbine exhaust gas. In the turbine 3, it is used as a cooling gas to cool the turbine 3 rotor and blades.

[0041] Specifically, turbine 3 is provided with a gas inlet 31, a cooling gas inlet 32, and a gas outlet 33. The gas inlet 31 is connected to the combustion product outlet 24. The cooling gas inlet 32 ​​is connected to the low-temperature cold fluid outlet 54 of the low-temperature regenerator 5. The gas outlet 33 is connected to the high-temperature hot fluid inlet 41 of the high-temperature regenerator 4. Both the high-temperature regenerator 4 and the low-temperature regenerator 5 are indirect heat exchangers with similar structures. Taking the high-temperature regenerator 4 as an example, it includes a hot fluid side 401, a cold fluid side 402, and a heat exchange wall 403. The hot fluid side 401 is provided with a high-temperature hot fluid inlet 41 and a high-temperature hot fluid outlet 42. The cold fluid side 402 is provided with a high-temperature cold fluid inlet 43 and a high-temperature cold fluid outlet 44. The heat exchange wall 403 is located between the hot fluid side 401 and the cold fluid side 402. The low-temperature regenerator 5 is provided with a low-temperature hot fluid inlet 51, a low-temperature hot fluid outlet 52, a low-temperature cold fluid inlet 53, and a low-temperature cold fluid outlet 54.

[0042] The high-temperature hot fluid inlet 41 of the high-temperature regenerator 4 is connected to the working fluid outlet of the turbine 3. The high-temperature hot fluid outlet 42 of the high-temperature regenerator 4 is connected to the low-temperature hot fluid inlet 51 of the low-temperature regenerator 5. The high-temperature cold fluid inlet 43 of the high-temperature regenerator 4 is connected to the low-temperature cold fluid outlet 54 of the low-temperature regenerator 5. The carbon dioxide in the low-temperature regenerator 5, which is at a lower temperature than that in the high-temperature regenerator 4, enters the high-temperature regenerator 4 through the low-temperature cold fluid outlet 54. After being heated by the turbine exhaust, it enters the carbon dioxide inlet 23 of the combustion chamber 2 through the high-temperature cold fluid outlet 44 of the high-temperature regenerator 4. After mixing with the combustion products, it is used as the working fluid for the turbine 3 to expand and do work. The low-temperature cold fluid outlet 54 of the low-temperature regenerator 5 is also connected to the cooling gas inlet 32 ​​of the turbine 3 to cool the rotor and blades of the turbine 3 and protect the rotor and blades from being burned out.

[0043] The low-temperature hot fluid outlet 52 of the low-temperature regenerator 5 is connected to the inlet of the cooler 6. The turbine exhaust after the low-temperature regenerator 5 is cooled enters the cooler 6. The low-temperature cold fluid inlet 53 is connected to the high-pressure outlet 112 of the carbon dioxide working fluid pump 11. The cooler 6 is provided with a cooler inlet 61 and a cooler outlet 62. The cooler inlet 61 is connected to the low-temperature hot fluid outlet 52, and the cooler outlet 62 is connected to the separator inlet 71.

[0044] Furthermore, the high-temperature regenerator 4 receives turbine exhaust and low-temperature carbon dioxide fed into the low-temperature regenerator 5, heats the low-temperature carbon dioxide with turbine exhaust, and sends the cooled turbine exhaust into the low-temperature regenerator 5 for heating. The heated low-temperature carbon dioxide is then sent into the combustion chamber 2.

[0045] Furthermore, a carbon dioxide working fluid pump 11 is provided between the liquid separator 10 and the low-temperature regenerator 5. The carbon dioxide working fluid pump 11 is used to pressurize the low-pressure liquid carbon dioxide separated by the liquid separator 10.

[0046] Furthermore, the combustion chamber 2 is simultaneously connected to the oxygen compressor 1, natural gas, and carbon dioxide. The combustion products of the combustion chamber 2 are mixed with carbon dioxide and then sent into the turbine 3 to expand and do work.

[0047] Specifically, cooler 6 cools the turbine exhaust gas and discharges it from cooler 6 outlet. Cooler 6 outlet is connected to separator inlet 71 of gas-liquid separator 7. Gas-liquid separator 7 separates liquid water and gaseous carbon dioxide in the turbine exhaust gas. Liquid water is discharged from drain outlet 72 of gas-liquid separator 7, and gaseous carbon dioxide is discharged from exhaust outlet 73 of gas-liquid separator 7. Carbon dioxide compressor 8 is provided with compressor inlet 81 and compressor outlet 82. Compressor inlet 81 is connected to exhaust outlet 73 of gas-liquid separator 7. Condenser 9 is provided with... It has a condenser inlet 91 and a condenser outlet 92. The compressor outlet 82 is connected to the condenser inlet 9. The compressed gaseous carbon dioxide is condensed into liquid carbon dioxide in the condenser 9. The liquid separator 10 is provided with a liquid inlet 101, a main liquid outlet 102 and a secondary liquid outlet 103. The condenser outlet 92 is connected to the liquid inlet 101 of the liquid separator 10. The liquid carbon dioxide enters the liquid separator 10 and is separated. Most of the liquid carbon dioxide enters the carbon dioxide working fluid pump 11 from the main liquid outlet 102 of the liquid separator 10.

[0048] Specifically, the flash tank 12 is provided with a flash inlet 121, a gas outlet 122 and a liquid outlet 123. A small portion of liquid carbon dioxide enters the flash inlet 121 from the secondary drain port 103 of the liquid separator 10. After flashing in the flash tank 12, the liquid carbon dioxide becomes low-pressure gaseous carbon dioxide and low-pressure liquid carbon dioxide. The low-pressure gaseous carbon dioxide flows from the gas outlet 122 into the compressor inlet 81, and is compressed, condensed and separated again. The low-pressure liquid carbon dioxide enters the storage inlet 131 of the carbon dioxide storage tank 13 from the liquid outlet 123 for storage. The carbon dioxide working fluid pump 11 is provided with a low-pressure inlet 111 and a high-pressure outlet 112. The liquid carbon dioxide discharged from the main discharge port 102 of the liquid separator 10 enters from the low-pressure inlet 111, and after being pressurized by the carbon dioxide working fluid pump 11, it is discharged from the high-pressure outlet 112. The high-pressure outlet 112 is connected to the low-temperature cold fluid inlet 53 of the low-temperature regenerator 5, so that it enters the low-temperature regenerator 5 and is heated by the turbine exhaust. After being heated, it enters the high-temperature regenerator 4 from the low-temperature cold fluid outlet 54 for further heating and enters the cooling gas inlet 32 ​​of the turbine 3 to cool the turbine blades and rotor.

[0049] The rest of the structure is the same as in Example 1.

[0050] Example 3

[0051] Reference Figure 3 This is the third embodiment of the present invention. Unlike the previous embodiments, this embodiment provides a method for low-pressure liquid carbon dioxide storage. For the Allam power cycle system used in the aforementioned low-pressure liquid carbon dioxide storage, it further includes the following steps:

[0052] S1, Combustion chamber 2 produces combustion products by burning pure oxygen and natural gas. The combustion products are mixed with carbon dioxide and then fed into turbine 3.

[0053] S2, Turbine 3 expands and does work through the mixed combustion products to output energy to the outside. The turbine exhaust generated after turbine 3 does work is discharged and input to high-temperature regenerator 4.

[0054] S3, turbine exhaust enters high-temperature regenerator 4 from the hot side to heat carbon dioxide on the cold side of high-temperature regenerator 4;

[0055] S4, the cooled turbine exhaust flows from the hot side into the low-temperature regenerator 5 to heat the carbon dioxide on the cold side of the low-temperature regenerator 5. The cooled turbine exhaust flows into the cooler 6 to cool the water in it into a liquid state.

[0056] S5, after the turbine exhaust is cooled, gas-liquid separation is performed. The water in it is separated into liquid form and sent outside the system. The turbine exhaust becomes pure carbon dioxide gas, which is then compressed and condensed into liquid carbon dioxide.

[0057] S6, liquid carbon dioxide is separated into two parts, a small part is flashed, and the other part is pressurized and sent back to the cold side of the low-temperature regenerator 5 to rejoin the power cycle;

[0058] S7, after flash evaporation, liquid carbon dioxide is converted into low-pressure liquid carbon dioxide and low-pressure gaseous carbon dioxide. The low-pressure liquid carbon dioxide enters the carbon dioxide storage tank 13 for storage, while the low-pressure gaseous carbon dioxide flows back to the inlet of the carbon dioxide compressor 8 and mixes with the pure carbon dioxide gas separated by the gas-liquid separator 7 before entering the carbon dioxide compressor 8 for compression.

[0059] Specifically, compressed pure oxygen is introduced into combustion chamber 2 in S1. The pressure of the compressed pure oxygen is the same as the pressure inside combustion chamber 2. Natural gas and pure oxygen burn in combustion chamber 2 to release heat. The combustion products are mixed with carbon dioxide entering combustion chamber 2 and used as the working fluid for turbine 3.

[0060] In S2, when the turbine 3 uses the combustion products of the combustion chamber 2 to expand and do work, the temperature of the combustion products is too high, exceeding the tolerance range of the turbine 3 blade material. Therefore, carbon dioxide flowing out of the cold fluid outlet of the low-temperature regenerator 5 needs to be introduced into the turbine 3 to cool the rotor and blades. The cooling method is to form a gas film covering the surface of the turbine 3 blades to block the blades from the high-temperature gas.

[0061] In S3, the turbine exhaust generated by the turbine 3 is directly discharged into the high-temperature regenerator 4, where it can exchange heat with the low-temperature carbon dioxide in the high-temperature regenerator 4, thereby heating the carbon dioxide and cooling the turbine exhaust. The heated carbon dioxide is sent into the combustion chamber 2, and the cooled turbine exhaust begins in S4.

[0062] Furthermore, in S4, after the carbon dioxide on the cold side of the low-temperature regenerator 5 is heated, it is sent to the cold side of the high-temperature regenerator 4 and the cooling inlet of the turbine 3 to cool the blades and rotor inside the turbine 3. Since the turbine exhaust sent from the high-temperature regenerator 4 to the low-temperature regenerator 5 is at a higher temperature than the carbon dioxide on the cold side of the low-temperature regenerator 5, the turbine exhaust is heat-exchanged again, heating the carbon dioxide on the cold side and cooling the turbine exhaust again. After the carbon dioxide on the cold side is heated, it is sent to the high-temperature regenerator 4 to be further heated by the turbine exhaust and sent into the turbine 3 as cooling air for the turbine 3 to protect the blades and rotor. The low-temperature regenerator 5 and the high-temperature regenerator 4 heat the carbon dioxide at constant pressure.

[0063] Specifically, in S5, the turbine exhaust is cooled to a liquid state by cooling the water in the exhaust. Then, the liquid water is separated from the gaseous carbon dioxide by the gas-liquid separator 7, so that the water in the turbine exhaust can be discharged and pure carbon dioxide gas is obtained, which facilitates the storage and recycling of carbon dioxide.

[0064] In S6, the flash evaporation process reduces carbon dioxide pressure from 7 MPa to 2 MPa.

[0065] Furthermore, the liquid carbon dioxide in S7 is heated by the low-temperature regenerator 5 and then turns back into gaseous carbon dioxide. It enters the high-temperature regenerator 4 for further heating and the turbine 3 to cool the blades. The gaseous carbon dioxide heated by the high-temperature regenerator 4 enters the combustion chamber 2 and mixes with the combustion products to serve as the working fluid for the expansion of the turbine 3. The low-pressure liquid carbon dioxide enters the carbon dioxide storage tank 13 for storage. The pressure of both the low-pressure liquid carbon dioxide and the low-pressure gaseous carbon dioxide is 2 MPa.

[0066] The rest of the structure is the same as in Example 2.

[0067] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0068] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the best mode of carrying out the invention as currently considered, or those features that are not relevant to implementing the invention) may be omitted.

[0069] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0070] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An Allam power cycle system with low-pressure liquid carbon dioxide storage, characterized in that: It includes a combustion chamber (2), a turbine (3), a regenerator, a cooler (6), a gas-liquid separator (7), a carbon dioxide compressor (8), a condenser (9), a liquid separator (10), a flash tank (12), and a carbon dioxide storage tank (13). The combustion chamber (2) is connected to the turbine (3), the turbine (3) is connected to the regenerator, the regenerator is connected to the cooler (6), the cooler (6) is connected to the gas-liquid separator (7), the gas-liquid separator (7) is connected to the carbon dioxide compressor (8), the carbon dioxide compressor (8) is connected to the condenser (9), the condenser (9) is connected to the liquid separator (10), the liquid separator (10) is connected to both the flash tank (12) and the regenerator, and the flash tank (12) is connected to both the carbon dioxide compressor (8) and the carbon dioxide storage tank (13). The carbon dioxide compressor (8) is used to pressurize the carbon dioxide gas flowing out of the gas-liquid separator (7) and the carbon dioxide gas flowing out of the flash tank (12). The condenser (9) is used to condense the compressed carbon dioxide gas into liquid carbon dioxide. The liquid separator (10) is used to send the liquid carbon dioxide into the flash tank (12) and the regenerator respectively. The carbon dioxide sent into the regenerator rejoins the power cycle. The flash tank (12) depressurizes the liquid carbon dioxide and flashes it into low-pressure liquid carbon dioxide and low-pressure gaseous carbon dioxide. The low-pressure gaseous carbon dioxide is mixed with the gaseous carbon dioxide flowing out of the gas-liquid separator (7) and then enters the carbon dioxide compressor (8). The carbon dioxide storage tank (13) is used to store the low-pressure liquid carbon dioxide. The cooler (6) is used to cool the turbine exhaust to a certain temperature. The water in the turbine exhaust is cooled into a liquid state. The gas-liquid separator (7) separates the liquid water in the turbine exhaust and discharges it from the system. The turbine exhaust becomes pure carbon dioxide gas. The combustion chamber (2) is equipped with an oxygen compressor (1) at the front end. The oxygen compressor (1) is used to supply pure oxygen to the combustion chamber (2). The regenerator is divided into a high-temperature regenerator (4) and a low-temperature regenerator (5). The low-temperature regenerator (5) receives turbine exhaust gas discharged from the high-temperature regenerator (4) and low-temperature carbon dioxide discharged from the liquid separator (10). It heats the low-temperature carbon dioxide with turbine exhaust gas, and after cooling, it sends the turbine exhaust gas into the cooler (6) for cooling. The heated low-temperature carbon dioxide is sent into the high-temperature regenerator (4) and the turbine (3) respectively. It is further heated by the turbine exhaust gas in the high-temperature regenerator (4) and used as cooling gas in the turbine (3) to cool the rotor and blades of the turbine (3).

2. The Allam power cycle system with low-pressure liquid carbon dioxide storage as described in claim 1, characterized in that: The high-temperature regenerator (4) receives turbine exhaust and low-temperature carbon dioxide sent by the low-temperature regenerator (5), heats the low-temperature carbon dioxide with turbine exhaust, and sends the cooled turbine exhaust into the low-temperature regenerator (5) to heat the low-temperature carbon dioxide in the low-temperature regenerator (5). The heated low-temperature carbon dioxide is sent into the combustion chamber (2) and mixed with the combustion products to serve as the working fluid for the turbine (3).

3. The Allam power cycle system with low-pressure liquid carbon dioxide storage as described in claim 2, characterized in that: A carbon dioxide working fluid pump (11) is provided between the liquid separator (10) and the low-temperature regenerator (5). The carbon dioxide working fluid pump (11) is used to pressurize the low-pressure liquid carbon dioxide separated by the liquid separator (10).

4. The Allam power cycle system with low-pressure liquid carbon dioxide storage as described in claim 3, characterized in that: The combustion chamber (2) is simultaneously connected to the oxygen compressor (1), natural gas and carbon dioxide, and the combustion products of the combustion chamber (2) are sent into the turbine (3) to do work.

5. A method for low-pressure liquid carbon dioxide storage, used in the Allam power cycle system for low-pressure liquid carbon dioxide storage as described in claim 1, characterized in that: It also includes the following steps, S1, the combustion chamber (2) produces combustion products by burning pure oxygen and natural gas. The combustion products are mixed with carbon dioxide and then fed into the turbine (3). S2, the turbine (3) expands and does work to output energy to the outside through the expansion of the mixed combustion products. The turbine exhaust generated after the turbine (3) does work is discharged and input to the high temperature regenerator (4). S3, turbine exhaust enters the high-temperature regenerator (4) from the hot side, heating the carbon dioxide on the cold side of the high-temperature regenerator (4); S4, the turbine exhaust after cooling flows from the hot side into the low-temperature regenerator (5) to heat the carbon dioxide on the cold side of the low-temperature regenerator (5), and the turbine exhaust after cooling again flows into the cooler (6). S5, after the turbine exhaust is cooled, gas-liquid separation is performed. The water in the turbine exhaust is discharged from the system in liquid form, and the turbine exhaust becomes pure carbon dioxide gas. The pure carbon dioxide gas is then compressed and condensed into liquid carbon dioxide. S6, liquid carbon dioxide is separated into two parts, a small part is flashed, and the other part is pressurized and sent back to the cold side of the low-temperature regenerator (5) to rejoin the power cycle; S7, after flash evaporation, liquid carbon dioxide becomes low-pressure liquid carbon dioxide and low-pressure gaseous carbon dioxide. The low-pressure liquid carbon dioxide enters the carbon dioxide storage tank (13) for storage, and the low-pressure gaseous carbon dioxide flows back to the inlet of the carbon dioxide compressor (8) and mixes with the pure carbon dioxide gas separated by the gas-liquid separator (7).

6. The method for low-pressure liquid storage of carbon dioxide as described in claim 5, characterized in that: In S4, the carbon dioxide on the cold side of the low-temperature regenerator (5) is heated and then sent to the cold side of the high-temperature regenerator (4) for further heating by turbine exhaust, and the cooling gas inlet (32) sent into the turbine (3) cools the blades and rotor inside the turbine (3).

7. The method for low-pressure liquid storage of carbon dioxide as described in claim 6, characterized in that: The liquid carbon dioxide in S7 is heated by the low-temperature regenerator (5) and then turns back into gaseous carbon dioxide. It enters the high-temperature regenerator (4) to be further heated by the turbine exhaust and enters the turbine (3) as cooling gas to cool the turbine blades and rotor. The gaseous carbon dioxide heated by the high-temperature regenerator (4) enters the combustion chamber (2) and mixes with the combustion products before entering the turbine (3) to expand and do work.

Images