A CCUS carbon capture system and method

Abstract

The present invention relates to a CCUS carbon capture system and method, which can realize energy storage power generation and combined heat and cold power generation of the carbon capture system, including a gas compression cooling unit, a carbon dioxide separation unit and a turbine power generation unit; a first indirect heat exchanger is arranged after each compressor; the carbon dioxide separation unit includes an indirect condenser, the indirect condenser is connected to the last first indirect heat exchanger, and the air outlet of the indirect condenser is connected to a gas storage tank; the air outlet of each turbine is connected in series with a second indirect heat exchanger, and the gas storage tank is connected to the first turbine; the condensing medium inlet of the indirect condenser is connected to each second indirect heat exchanger, the condensing medium outlet of the indirect condenser is connected to each first indirect heat exchanger or the fourth indirect heat exchanger, and the cold source outlet of each first indirect heat exchanger is connected to each second indirect heat exchanger or the fourth indirect heat exchanger. The present invention has lower energy consumption and operating costs, which helps to improve the benefits of CCUS.

Description

Technical Field

[0001] The present invention relates to a CCUS carbon capture system and method using a boiling point separation method. Background Art

[0002] It has become a consensus in the whole society that greenhouse gas (especially carbon dioxide, CO2) emissions lead to global temperature rise. Therefore, it is necessary to reduce the emissions of greenhouse gases such as carbon dioxide, achieve positive and negative offset, and achieve relative "zero emissions".

[0003] Among various technical measures, carbon dioxide capture, utilization and storage (CCUS) is an irreplaceable and important carbon emission reduction technical measure. CCUS technology can achieve near-zero carbon emissions from fossil energy utilization and promote deep and near-zero carbon emission reduction in difficult-to-reduce industries such as thermal power, steel, cement, and petrochemicals.

[0004] However, CCUS projects face the difficulties of high cost and high energy consumption, which makes them difficult to promote. The main key difficulty lies in the high cost and high energy consumption in the carbon dioxide capture stage. Even considering the benefits brought by carbon emission rights trading and carbon dioxide utilization, the entire CCUS project faces the risk of losses.

[0005] It is reported that the different capture costs in various industries are caused by the different concentrations of carbon dioxide in the flue gas or exhaust gas emitted by various industries. The lower the concentration, the higher the capture cost; conversely, the higher the concentration, the lower the capture cost. In order to increase the concentration of carbon dioxide, people use oxygen-enriched or chemical chain combustion technology, but this generates new costs, and the cost is still high.

[0006] The energy consumption of carbon dioxide capture accounts for about 60%-80% of the total energy consumption of the entire CCUS process. Therefore, how to reduce the energy consumption and cost of capture is the key to the industrialization of CCUS. Whether before or after combustion, commonly used capture technologies can be divided into two categories: chemical capture and physical capture. Chemical capture technology includes chemical solvent or ionic liquid absorption method and chemical adsorption method. Physical capture technology is divided into three categories. Among them, the first category is physical absorption method, which uses the different solubility / adsorption degree of CO2 in the absorbent / adsorbent at different temperatures or pressures to achieve separation, such as low-temperature methanol washing method, polyethylene glycol dimethyl ether method, pressure swing adsorption method, etc.; the second category is permeation separation method, that is, a method of separation using different permeabilities of different gases when they pass through a certain substance, such as membrane separation method; the third category is boiling point separation method, that is, separation using the difference in boiling points of different gases, such as low-temperature distillation method.

[0007] The costs of the above existing technologies are still relatively high, and it is impossible to achieve profitable operation of CCUS projects. How to significantly reduce the energy consumption and cost of carbon capture is a major problem that needs to be urgently solved in the CCUS field.

[0008] For the boiling point separation method, the condensation temperature (boiling point) of carbon dioxide is related to its pressure (partial pressure). The higher the pressure, the higher the boiling point. The relationship is shown in Table 1.

[0009] Table 1

[0010]

[0011] Chinese invention patent CN114777419B discloses a flue gas compression energy storage coupled carbon capture system, the system comprising a gas compression unit, a carbon dioxide separation unit and a turbine power generation unit connected in sequence, the gas compression unit comprising a three-stage compressor, a heat exchanger is arranged behind each stage compressor, a gas purification device is arranged between the first compressor and the second compressor, the device is located behind the heat exchanger and is directly connected to the secondary compressor; the carbon dioxide separation unit comprises a carbon dioxide separator and a liquid carbon dioxide storage tank, a refrigeration device is arranged in front of the carbon dioxide separator, the liquid phase outlet of the carbon dioxide separator is connected to the liquid carbon dioxide storage tank, the gas phase outlet of the carbon dioxide separator is connected to the turbine power generation unit, and a compressed gas storage tank or a carbon dioxide separator is arranged between the carbon dioxide separator and the turbine power generation unit. A gas liquefaction unit is also provided between the turbine power generation unit. The gas liquefaction unit includes a cryogenic device, an expansion device, a gas-liquid separation device and a boosting device connected in sequence. The boosting device is then connected to the heat exchanger of the turbine power generation unit. The gas phase outlet of the gas-liquid separation device is returned and connected to the cryogenic device as a cold source. The liquid phase outlet of the gas-liquid separation device is also connected to a liquid gas storage tank and then connected to the boosting device. The turbine power generation unit includes a three-stage expansion machine, and a heat exchanger is connected in series before the inlet of each stage of the expansion machine; the heat source of the heat exchanger connected after the boosting device and the cold source of the cryogenic device form a circulation system; the system also includes a flue gas pretreatment unit, and the outlet of the flue gas pretreatment unit is connected to the inlet of the gas compression unit through an induced draft fan; the flue gas pretreatment unit includes a flue gas condenser, a demister, an alkali washing tower and a dust collector connected in sequence.

[0012] Although the technical solution of CN114777419B has the benefits of energy storage and power generation, in order to achieve the purpose of carbon capture, the compressed gas must be refrigerated and cooled (to about minus 50°C) so that the gaseous carbon dioxide is condensed into liquid or solid. This technical solution uses a refrigeration device for cooling, which increases the refrigeration energy consumption and cost. Summary of the invention

[0013] In view of the deficiencies of the prior art, one of the objects of the present invention is to provide a CCUS carbon capture system with lower energy consumption; a second object of the present invention is to provide a CCUS method.

[0014] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0015] A CCUS carbon capture system comprises a gas compression cooling unit, a carbon dioxide separation unit and a turbine power generation unit connected in sequence; the gas compression cooling unit comprises at least two compressors connected in sequence, and a first indirect heat exchanger is arranged after each compressor; the carbon dioxide separation unit comprises an indirect condenser, the air inlet of the indirect condenser is connected to the first indirect heat exchanger after the last compressor (i.e., the last compressor viewed along the gas flow direction), the condensate outlet of the indirect condenser is connected to a carbon dioxide storage tank, and the air outlet of the indirect condenser is connected to an air storage tank; the turbine power generation unit comprises a generator and at least two turbines connected in sequence, the turbine is connected to the generator in a transmission manner, the air outlet of each turbine is connected to a second indirect heat exchanger, and the air storage tank is connected to the air inlet of the first turbine (i.e., the first turbine viewed along the gas flow direction); the condensing medium inlet of the indirect condenser is connected to the heat source outlet of each second indirect heat exchanger; the condensing medium outlet of the indirect condenser is connected to the heat source inlet of each second indirect heat exchanger.

[0016] Optionally, the condensing medium inlet of the indirect condenser is connected to the heat source outlet of each second indirect heat exchanger, the condensing medium outlet of the indirect condenser is connected to the cold source inlet of each first indirect heat exchanger, and the cold source outlet of each first indirect heat exchanger is connected to the heat source inlet of each second indirect heat exchanger; or, it also includes a fourth indirect heat exchanger, the fourth indirect heat exchanger includes a first medium inlet and a first medium outlet that are connected to each other, a second medium inlet and a second medium outlet that are connected to each other, the cold source inlet of each first indirect heat exchanger is connected to the first medium outlet, the cold source outlet of each first indirect heat exchanger is connected to the first medium inlet, the condensing medium outlet of the indirect condenser is connected to the second medium inlet, and the second medium outlet is connected to the heat source inlet of each second indirect heat exchanger.

[0017] Thus, the gas containing carbon dioxide to be treated is compressed and cooled in multiple stages by the gas compression and cooling unit, and then enters the carbon dioxide separation unit for condensation. Most of the carbon dioxide is liquefied and / or solidified to achieve carbon capture, and the remaining compressed gas can enter the gas storage tank for storage; the remaining compressed gas in the gas storage tank can be partially or completely input into the turbine power generation unit for power generation as needed. More specifically, the gas outlet of each stage of the turbine of the present invention is connected to a second indirect heat exchanger. After the remaining compressed gas enters the turbine power generation unit, it participates in the first expansion power generation and cooling without being heated, and then undergoes the first indirect heating, and then undergoes at least one round of expansion power generation and heating, and finally the gas pressure is reduced to normal pressure, and can be directly discharged. In this way, the remaining compressed gas participates in expansion and power generation without being heated, and then is heated again. The temperature T1 of the remaining compressed gas before expansion entering the turbine is lower than that of the existing technology (generally heated first, then expanded to generate electricity). The gas temperature T2 of the remaining compressed gas after expansion can be easily reduced to below the condensation temperature of carbon dioxide. Subsequently, after the expanded remaining compressed gas exchanges heat with the heating medium in the second indirect heat exchanger, the temperature of the heating medium can also be reduced to a very low temperature (even below the condensation temperature of carbon dioxide). The low-temperature heating medium enters the indirect condenser and can be used as a cold source for the condensation of carbon dioxide to play a refrigeration role, thereby solving the problem of the prior art that special refrigeration equipment needs to be set up, which helps to simplify the CCUS equipment structure, reduce refrigeration energy consumption and costs, and increase profits.

[0018] In the stage of compressed gas expansion and power generation, the present invention is different from the prior art. The compressed gas in the prior art is first heated and then expanded to generate electricity. Its temperature is always above room temperature and has no refrigeration effect. For example, the compressed gas in the prior art CN114777419B is heated to 177-300°C before expansion, and the gas temperature is reduced to 33-67°C after expansion, which cannot reduce the temperature of the cooling medium to below the condensation temperature of carbon dioxide. However, the compressed gas of the present invention is not heated or heated less first, and is directly used for expansion and power generation, and then heated. The gas temperature T1 before expansion is lower than that of the prior art, and the gas temperature T2 after expansion can be reduced to below the condensation temperature of carbon dioxide. The low-temperature heating medium generated after further heat exchange can be used as a cold source for carbon dioxide condensation refrigeration, which helps to reduce refrigeration energy consumption and costs and increase profits.

[0019] Therefore, the CCUS carbon capture system of the present invention is of great significance for solving the major problems of high energy consumption and high cost in the field of CCUS carbon capture, and has good prospects for successful commercial application and promotion.

[0020] By means of the above structure, the cooling medium can circulate in the indirect condenser, the first indirect heat exchanger, the second indirect heat exchanger, or the indirect condenser, the fourth indirect heat exchanger and the second indirect heat exchanger in sequence, and be circulated and used as a cold source and a heat source in the above functional units respectively.

[0021] The use of a compressor and a first indirect heat exchanger to perform multi-stage compression and cooling of the gas helps to reduce the energy consumption of the compressor.

[0022] The use of a turbine and a second indirect heat exchanger to expand and heat the gas in multiple stages helps to improve power generation efficiency, allowing the generator to generate more electricity.

[0023] Furthermore, it also includes a pre-processing unit connected to the first-stage compressor.

[0024] Furthermore, the pre-treatment unit includes a dust collector and a dehumidifier which are connected in sequence, and the gas outlet of the dehumidifier is connected to the first-stage compressor, thereby reducing the temperature of the gas to be treated, and removing dust and moisture, so as to prepare for subsequent treatment.

[0025] Further, the number of compressors is 3-6, and furthermore, 4-5.

[0026] Furthermore, the condensing medium outlet of the indirect condenser is connected to a cooling device; the outlet of the cooling device is connected to the cold source inlet of each first indirect heat exchanger, or the outlet of the cooling device is connected to the second medium inlet. Thus, the condensing medium can further provide cooling to the outside through the cooling device to obtain cooling benefits.

[0027] Further, the heat source outlet of each second indirect heat exchanger is connected to the condensing medium inlet of the indirect condenser; optionally, the cold source inlet of each first indirect heat exchanger is connected to the condensing medium outlet of the indirect condenser.

[0028] Furthermore, the condensing medium inlet of the indirect condenser is connected to a cold storage tank, and the inlet of the cold storage tank is connected to the heat source outlet of each second indirect heat exchanger. In addition to being used for carbon dioxide condensation, the excess cold in the cold storage tank can be used for external cooling.

[0029] Furthermore, a third indirect heat exchanger is included, and the third indirect heat exchanger includes a first gas inlet and a first gas outlet that are interconnected, and a second gas inlet and a second gas outlet that are interconnected, the first gas inlet is connected to the first indirect heat exchanger, and the first gas outlet is connected to the indirect condenser; the second gas inlet is connected to the gas outlet of the indirect condenser, and the second gas outlet is connected to the gas storage tank. In this way, the temperature of the compressed gas entering the condenser can be further reduced.

[0030] Furthermore, a heat storage tank is included, the inlet of the heat storage tank is connected to the cold source outlet of each first indirect heat exchanger, the outlet of the heat storage tank is connected to the heat source inlet of each second indirect heat exchanger, or the outlet of the heat storage tank is connected to the first medium inlet. In addition to being used to heat the expanded gas, the excess heat in the heat storage tank can be used to supply heat to the outside.

[0031] Furthermore, a heat supplier is provided between the heat storage tank and the second indirect heat exchanger, or a heat supplier is provided between the heat storage tank and the first medium inlet, thereby providing heat to the outside and obtaining heat supply benefits.

[0032] Based on the same inventive concept, the present invention provides a CCUS method, comprising the following steps:

[0033] S1. performing at least two rounds of compression and indirect cooling on the gas containing carbon dioxide to obtain compressed gas;

[0034] S2. Performing indirect condensation treatment on the compressed gas to obtain residual compressed gas and carbon dioxide liquid and / or solid;

[0035] S3. Input at least part of the remaining compressed gas into the turbine power generation unit, so that the remaining compressed gas undergoes at least two rounds of expansion treatment and heating treatment in sequence to obtain expanded gas and electric energy; wherein, the cooling medium used for the indirect cooling treatment in S1 is the condensing medium produced by the indirect condensation treatment in S2, or the cooling medium used for the indirect cooling treatment in S1 is the cooling medium after indirect heat exchange with the condensing medium produced by the indirect condensation treatment in S2; the condensing medium used in the indirect condensation treatment in S2 is the heating medium produced by the heating treatment in S3; the heating medium used in the heating treatment in S3 is the cooling medium produced by the indirect cooling treatment in S1, or the heating medium used in the heating treatment in S3 is the condensing medium produced by the indirect condensation treatment in S2 and after indirect heat exchange with the cooling medium produced by the indirect cooling treatment in S1.

[0036] As a result, the temperature of the expanded gas can be reduced to below the condensation temperature of carbon dioxide, and the temperature of the heating medium generated by the heating treatment in S3 can be further reduced to below the condensation temperature of carbon dioxide, and used as the condensation medium in the condensation treatment process of S2, thereby realizing the condensation and separation of carbon dioxide. No additional refrigeration equipment is required, which helps to reduce energy consumption and increase profits.

[0037] Optionally, the cooling medium is a liquid medium such as pressurized ethanol, pressurized n-pentane, heat transfer oil, pressurized water, etc. The use of a pressurized medium can increase its boiling point, and it will not boil and vaporize even if its temperature is as high as 160°C.

[0038] Furthermore, the temperature of the expanded gas is lower than the condensation temperature (boiling point) of carbon dioxide.

[0039] Furthermore, the temperature of the expanded gas is higher than the condensation temperature (boiling point) of nitrogen and / or oxygen to avoid liquefaction of nitrogen and oxygen during the condensation process. Example 6 of CN114777419B discloses a cryogenic scheme for completely liquefying compressed gas, which generates a low temperature of minus 176°C by gas expansion, so that all gases including nitrogen and oxygen are liquefied. This cryogenic scheme slightly increases the capture rate of carbon dioxide, but greatly reduces the expansion power generation efficiency, which is not worth the loss. To avoid this cryogenic scheme, the present invention preferably requires that the temperature of the expanded gas is lower than the condensation temperature of carbon dioxide and higher than the condensation temperature of nitrogen and / or oxygen.

[0040] Furthermore, in order to control the temperature of the gas after expansion, the gas pressure before expansion and the gas pressure after expansion can be controlled. The greater the pressure difference before and after expansion, the greater the temperature difference before and after expansion.

[0041] Furthermore, in order to control the temperature of the expanded gas, the thermal insulation effect of the turbine expansion process and the surrounding environment can be controlled. The better the thermal insulation effect, the smaller the heat dissipation, and the greater the temperature difference before and after expansion.

[0042] Furthermore, in S1, the temperature of the compressed gas after cooling is 15-30°C.

[0043] Optionally, in S1, the gas containing carbon dioxide is subjected to three rounds of compression treatment and indirect cooling treatment in sequence to obtain compressed gas;

[0044] In the first round, the pressure of the gas after compression treatment increases from normal pressure to 0.8-1.2MPa, and the temperature increases from normal temperature to 150-190°C; the temperature of the gas after cooling treatment is 15-30°C;

[0045] In the second round, the pressure of the gas after compression treatment increases to 7.8-8.2MPa, and the temperature increases from room temperature to 140-180°C; the temperature of the gas after cooling treatment is 15-30°C;

[0046] In the third round, the pressure of the gas after compression treatment increases to 38-42MPa, and the temperature increases from room temperature to 140-180°C; the temperature of the gas after cooling treatment is 15-30°C.

[0047] Furthermore, in S2, the temperature of the remaining compressed gas is -60-12°C.

[0048] Further, in S3, the remaining compressed gas is subjected to three rounds of expansion treatment and heating treatment in sequence;

[0049] In the first round, after the expansion treatment, the pressure of the remaining compressed gas is reduced to 7.8-8.2MPa, and the temperature is reduced to -140~-100℃; the temperature of the gas after the heating treatment is increased to 5-15℃;

[0050] In the second round, after the expansion treatment, the pressure of the remaining compressed gas is reduced to 0.8-1.2MPa, and the temperature is reduced to -140~-100℃; the temperature of the gas after the heating treatment is increased to 5-15℃;

[0051] In the third round, after the expansion treatment, the pressure of the remaining compressed gas is reduced to normal pressure, and the temperature is reduced to -140~-100℃; the temperature of the gas after the heating treatment is increased to 15-25℃.

[0052] Furthermore, the temperature of the condensation medium generated by the indirect condensation treatment in S2 is -70~-50°C.

[0053] Furthermore, the condensing medium generated by the indirect condensation treatment in S2 is used to supply cold air to the outside, so that the temperature of the condensing medium is increased to 0-12°C.

[0054] Furthermore, the temperature of the cooling medium generated by the indirect cooling process in S1 is 140-160°C.

[0055] Furthermore, the cooling medium generated by the indirect cooling process in S1 is used to supply heat to the outside, so that the temperature of the cooling medium is reduced to 40-60°C.

[0056] Furthermore, the temperature of the heating medium generated by the heating process in S3 is -120 to -90° C. Therefore, the heating medium can be used as a refrigerant for condensation without relying on additional refrigeration equipment.

[0057] Optionally, cooling, heating and electricity can be supplied to external parties during peak electricity price periods, and external off-peak electricity can be used during off-peak electricity price periods to increase the benefits of the CCUS carbon capture system and reduce costs.

[0058] Furthermore, a comprehensive comparison between the method of the present invention and CN114777419B is shown in Table 2.

[0059] Table 2

[0060]

[0061] The present invention adopts a method of greatly reducing T1 and T2 and making T2 lower than the condensation temperature of carbon dioxide, which can achieve low-energy condensation, increase cooling and heating benefits, and realize combined supply of cooling, heat and electricity.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] (1) The CCUS carbon capture system and method of the present invention does not require additional refrigeration equipment, has lower energy consumption and operating costs, and helps to increase the benefits of CCUS.

[0064] (2) The CCUS carbon capture system and method of the present invention does not require additional refrigeration equipment and has a simpler and more compact structure, which helps to reduce equipment footprint and investment costs.

[0065] (3) The CCUS carbon capture system of the present invention can be equipped with a cooling device and a heating device by directly expanding the compressed gas to generate electricity and then heating the compressed gas, thereby realizing the combined supply of cooling, heating and electricity.

[0066] (4) As long as the difference ΔT between the temperature T1 of the compressed gas before expansion and the temperature T2 after expansion remains unchanged (ΔT=T1-T2), the power generation efficiency will increase as T2 decreases. Therefore, compared with the prior art, under the same ΔT, the power generation efficiency of the present invention is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 1 is a simplified structural diagram of a CCUS carbon capture system according to Example 1 of the present invention.

[0068] Figure 2 1 is a simplified structural diagram of a CCUS carbon capture system according to Example 2 of the present invention.

[0069] In the figure, 1 is a pretreatment unit, 2 is a compressor, 3 is a first indirect heat exchanger, 4 is a gas storage tank, 5 is a turbine, 6 is a generator, 7 is a second indirect heat exchanger, 8 is a chimney, 9 is a heat storage tank, 10 is a heater, 11 is a cold storage tank, 12 is a carbon dioxide storage tank, 13 is a cooler, 14 is a condenser, 15 is a third indirect heat exchanger, and 16 is a fourth indirect heat exchanger. DETAILED DESCRIPTION

[0070] The present invention will be described in detail below in conjunction with the embodiments. It should be noted that the embodiments and features of the embodiments of the present invention can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear in the following, they only indicate that the upper, lower, left and right directions are consistent with the drawings themselves, and do not limit the structure.

[0071] Example 1

[0072] See also Figure 1A CCUS carbon capture system comprises a pretreatment unit, a gas compression and cooling unit, a carbon dioxide separation unit, a turbine power generation unit, and a chimney 8 which are connected in sequence; the gas compression and cooling unit comprises three compressors 2 which are connected in sequence, and a first indirect heat exchanger 3 is arranged after each compressor 2; the carbon dioxide separation unit comprises an indirect condenser 14 and a third indirect heat exchanger 15, the air inlet of the indirect condenser 14 is connected to the first indirect heat exchanger 3 after the last compressor 2, the condensate outlet of the indirect condenser 14 is connected to a carbon dioxide storage tank 12, and the air outlet of the indirect condenser 14 is connected to two gas storage tanks 4; the turbine power generation unit comprises a generator 6 and a third indirect heat exchanger 15; ... and the indirect condenser 14 is connected to the second indirect heat exchanger 15; the indirect condenser 14 is connected to the second indirect heat exchanger 15; the indirect condenser 14 is connected to the second indirect heat exchanger 15; the indirect condenser 14 is connected to the second indirect heat exchanger 15; the indirect condenser 14 is connected to the second indirect heat exchanger 15; the indirect condenser 14 is connected to the second indirect heat exchanger 15; the indirect condenser 14 is connected to the second indirect heat exchanger 15; the indirect condens The three-stage turbine 5 is connected in series, the turbine 5 is arranged on the turbine shaft and distributed in sequence along the length direction of the turbine shaft, one end of the turbine shaft is drivingly connected to the generator 6, and the air outlet of each stage of the turbine 5 is connected in series with a second indirect heat exchanger 7 (the first stage turbine 5, the first stage second indirect heat exchanger, the second stage turbine 5, the second stage second indirect heat exchanger, the third stage turbine 5, the third stage second indirect heat exchanger, and the chimney 8 are connected in series in sequence), and the air storage tank 4 is connected to the air inlet of the first stage turbine 5; the heat source outlet of each second indirect heat exchanger 7 is connected to the condensing medium inlet of the indirect condenser 14, and the cold source inlet of each first indirect heat exchanger 3 is connected to the condensing medium outlet of the indirect condenser 14. The third indirect heat exchanger 15 includes a first gas inlet and a first gas outlet that are interconnected, and a second gas inlet and a second gas outlet that are interconnected. The first gas inlet is connected to the first indirect heat exchanger, and the first gas outlet is connected to the indirect condenser; the second gas inlet is connected to the gas outlet of the indirect condenser, and the second gas outlet is connected to the gas storage tank.

[0073] The condensing medium inlet of the indirect condenser 14 is connected to the cold storage tank 11, and the inlet of the cold storage tank 11 is connected to the heat source outlet of each second indirect heat exchanger 7. The condensing medium outlet of the indirect condenser 14 is connected to the cooling device 13, and the outlet of the cooling device 13 is connected to the cold source inlet of each first indirect heat exchanger 3.

[0074] It also includes a heat storage tank 9 , the inlet of which is connected to the cold source outlet of each first indirect heat exchanger 3 , and the outlet of which is connected to the hot source inlet of each second indirect heat exchanger 7 .

[0075] The cold source outlet of each first indirect heat exchanger 3 is connected in parallel with the inlet of the heat storage tank, and the hot source inlet of each second indirect heat exchanger 7 is connected in parallel with the outlet of the heat storage tank. A heat supply 10 is provided between the heat storage tank 9 and the second indirect heat exchanger 7.

[0076] The pre-treatment unit 1 comprises a dust collector and a dehumidification device which are connected in sequence, and the air outlet of the dehumidification device is connected to the first-stage compressor 2 .

[0077] The CCUS carbon capture system is used to capture carbon from flue gas containing 10 vol% carbon dioxide. The specific process is as follows:

[0078] The flue gas is input into the pretreatment unit 1 so that the temperature of the flue gas is reduced to a normal temperature of 20°C.

[0079] The pretreated flue gas is input into the first-stage compressor 2, so that the flue gas pressure after compression increases from normal pressure to 1MPa, and the temperature increases from normal temperature 20°C to 170°C, and then enters the first-stage first indirect heat exchanger 3, where the flue gas is cooled and the flue gas temperature drops to 20°C.

[0080] Then, the flue gas enters the second-stage compressor 2, causing the flue gas pressure to increase from 1MPa to 8MPa and the temperature to increase from 20°C to 160°C, and then enters the second-stage first indirect heat exchanger 3, causing the flue gas temperature to drop to 20°C.

[0081] Subsequently, the flue gas enters the third-stage compressor 2, causing the flue gas pressure to increase from 8MPa to 40MPa and the temperature to increase from 20°C to 160°C, and then enters the third-stage first indirect heat exchanger 3, causing the flue gas temperature to drop to 20°C.

[0082] Then, the flue gas at 20°C enters the third indirect heat exchanger 15 to be cooled, and then enters the indirect condenser 14, so that the flue gas temperature is further reduced to -50°C, and the carbon dioxide is condensed into liquid and flows from the indirect condenser 14 to the carbon dioxide storage tank 12. In addition to CO2, most of the SO2 and NO2 in the flue gas can also be condensed and liquefied and separated.

[0083] Finally, the compressed flue gas with a carbon dioxide content of less than 2%, a pressure of 40 MPa and a temperature of -50°C enters the third indirect heat exchanger 15 to be heated, and the temperature rises to 10°C, enters the gas storage tank 4, and then enters the first-stage turbine 5. The flue gas expansion drives the impeller to rotate, thereby driving the generator 6 to generate electricity. After expansion, the flue gas temperature drops to -120°C, and the pressure drops from 40 MPa to 8 MPa. Then the flue gas enters the first-stage second indirect heat exchanger 7, causing the flue gas temperature to rise to 10°C.

[0084] Then, the flue gas enters the second-stage turbine 5, and the expansion of the flue gas drives the impeller to rotate, thereby driving the generator 6 to generate electricity, so that the temperature of the expanded flue gas drops to -120°C, and the pressure drops from 8MPa to 1MPa. Then the flue gas enters the second-stage second indirect heat exchanger 7, and the temperature rises to 10°C.

[0085] Then, the flue gas enters the third-stage turbine 5, and the expansion of the flue gas drives the impeller to rotate, thereby driving the generator 6 to generate electricity, so that the temperature of the expanded flue gas drops to -120°C, and the pressure drops from 1MPa to normal pressure. Then the flue gas enters the third-stage second indirect heat exchanger 7, and the temperature rises to 20°C.

[0086] Finally, the flue gas is conveyed to the chimney 8 and discharged into the atmosphere.

[0087] The liquid (cooling medium) at -110°C in the cold storage tank 11 enters the condenser 14, and after cooling and condensing the compressed gas, the liquid temperature rises to -60°C, and then enters the cold supply device 13 to supply cold to the outside, and the liquid temperature rises to 10°C, and then enters the first, second, and third stage first indirect heat exchangers 3 respectively, and after cooling the compressed gas, the liquid temperature rises to 150°C, and then enters the heat storage tank 9, and then enters the heater 10 to supply heat to the outside, and the liquid temperature drops to 50°C, and then enters the first, second, and third stage second indirect heat exchangers 7 respectively, and heats the gas after expansion work, and the liquid temperature drops to -110°C, and then enters the cold storage tank 11, and repeats the cycle, so that the condensation process of carbon dioxide can be completed without relying on additional refrigeration equipment, effectively utilizing the capacity of compressed gas, helping to save energy consumption, simplifying the structure of the CCUS carbon capture system, and reducing the overall cost.

[0088] Example 2

[0089] See also Figure 2A CCUS carbon capture system comprises a pretreatment unit, a gas compression and cooling unit, a carbon dioxide separation unit, a turbine power generation unit, and a chimney 8 connected in sequence; the gas compression and cooling unit comprises three compressors 2 connected in sequence, and a first indirect heat exchanger 3 is arranged after each compressor 2; the carbon dioxide separation unit comprises an indirect condenser 14 and a third indirect heat exchanger 15, the air inlet of the indirect condenser 14 is connected to the first indirect heat exchanger 3 after the last compressor 2, the condensate outlet of the indirect condenser 14 is connected to a carbon dioxide storage tank 12, and the air outlet of the indirect condenser 14 is connected to two gas storage tanks 4; the turbine power generation unit comprises a generator 6 and three stages of turbines connected in sequence The turbine 5 is arranged on the turbine shaft and is sequentially distributed along the length direction of the turbine shaft. One end of the turbine shaft is drivingly connected to the generator 6. The outlet of each stage of the turbine 5 is connected in series with a second indirect heat exchanger 7. The gas storage tank 4 is connected to the air inlet of the first stage turbine 5. The heat source outlet of each second indirect heat exchanger 7 is connected to the condensing medium inlet of the indirect condenser 14. The fourth indirect heat exchanger 16 is also included. The fourth indirect heat exchanger 16 includes a first medium inlet and a first medium outlet that are interconnected, a second medium inlet and a second medium outlet that are interconnected, and a cold source inlet (using heat transfer oil as the cold source medium) of each first indirect heat exchanger 3 is connected to the first medium outlet of the fourth indirect heat exchanger 16. The third indirect heat exchanger includes a first gas inlet and a first gas outlet that are interconnected, a second gas inlet and a second gas outlet that are interconnected, the first gas inlet is connected to the first indirect heat exchanger, and the first gas outlet is connected to the indirect condenser; the second gas inlet is connected to the gas outlet of the indirect condenser, and the second gas outlet is connected to the gas storage tank.

[0090] The condensing medium inlet of the indirect condenser 14 is connected to the cold storage tank 11 (the medium is ethanol), and the inlet of the cold storage tank 11 is connected to the heat source outlet of each second indirect heat exchanger 7. The condensing medium outlet of the indirect condenser 14 is connected to the cooler 13, and the outlet of the cooler 13 is connected to the second medium inlet of the fourth indirect heat exchanger 16.

[0091] It also includes a heat storage tank 9 , the inlet of which is connected to the cold source outlet of each first indirect heat exchanger 3 , and the outlet of which is connected to the first medium inlet of the fourth indirect heat exchanger 16 .

[0092] The cold source outlet of each first indirect heat exchanger 3 is connected in parallel to the inlet of the heat storage tank, and the heat source inlet of each second indirect heat exchanger 7 is connected in parallel to the second medium outlet of the fourth indirect heat exchanger 16. A heat supply 10 is provided between the heat storage tank 9 and the fourth indirect heat exchanger 16.

[0093] The pre-treatment unit 1 comprises a dust collector and a dehumidification device which are connected in sequence, and the air outlet of the dehumidification device is connected to the first-stage compressor 2 .

[0094] The CCUS carbon capture system is used to capture carbon from flue gas containing 10 vol% carbon dioxide. The specific process is as follows:

[0095] The flue gas is input into the pretreatment unit 1 so that the temperature of the flue gas is reduced to a normal temperature of 20°C.

[0096] The pretreated flue gas is input into the first-stage compressor 2, so that the flue gas pressure after compression increases from normal pressure to 1MPa, and the temperature increases from normal temperature 20°C to 170°C, and then enters the first-stage first indirect heat exchanger 3, where the flue gas is cooled and the flue gas temperature drops to 20°C.

[0097] Then, the flue gas enters the second-stage compressor 2, causing the flue gas pressure to increase from 1MPa to 8MPa and the temperature to increase from 20°C to 160°C, and then enters the second-stage first indirect heat exchanger 3, causing the flue gas temperature to drop to 20°C.

[0098] Subsequently, the flue gas enters the third-stage compressor 2, causing the flue gas pressure to increase from 8MPa to 40MPa and the temperature to increase from 20°C to 160°C, and then enters the third-stage first indirect heat exchanger 3, causing the flue gas temperature to drop to 20°C.

[0099] Then, the flue gas at 20°C enters the third indirect heat exchanger 15 to be cooled, and then enters the indirect condenser 14, so that the flue gas temperature is further reduced to -50°C, and the carbon dioxide is condensed into liquid and flows from the indirect condenser 14 to the carbon dioxide storage tank 12. In addition to CO2, most of the SO2 and NO2 in the flue gas can also be condensed and liquefied and separated.

[0100] Finally, the compressed flue gas with a carbon dioxide content of less than 2%, a pressure of 40 MPa and a temperature of -50°C enters the third indirect heat exchanger 15 to be heated, and the temperature rises to 10°C, enters the gas storage tank 4, and then enters the first-stage turbine 5. The flue gas expansion drives the impeller to rotate, thereby driving the generator 6 to generate electricity. After expansion, the flue gas temperature drops to -120°C, and the pressure drops from 40 MPa to 8 MPa. Then the flue gas enters the first-stage second indirect heat exchanger 7, causing the flue gas temperature to rise to 10°C.

[0101] Then, the flue gas enters the second-stage turbine 5, and the expansion of the flue gas drives the impeller to rotate, thereby driving the generator 6 to generate electricity, so that the temperature of the expanded flue gas drops to -120°C, and the pressure drops from 8MPa to 1MPa. Then the flue gas enters the second-stage second indirect heat exchanger 7, and the temperature rises to 10°C.

[0102] Then, the flue gas enters the third-stage turbine 5, and the expansion of the flue gas drives the impeller to rotate, thereby driving the generator 6 to generate electricity, so that the temperature of the expanded flue gas drops to -120°C, and the pressure drops from 1MPa to normal pressure. Then the flue gas enters the third-stage second indirect heat exchanger 7, and the temperature rises to 20°C.

[0103] Finally, the flue gas is conveyed to the chimney 8 and discharged into the atmosphere.

[0104] The heat transfer oil (heat exchange medium) at 150°C in the heat storage tank 9 enters the heater 9 to supply heat to the outside, and the temperature of the heat transfer oil drops to 50°C, and then enters the fourth indirect heat exchanger 16. After the heat transfer oil exchanges heat with ethanol, the temperature drops to 10°C, and then enters the first, second, and third level first indirect heat exchangers 3 respectively to cool the compressed gas. The temperature of the heat transfer oil rises to 150°C, and then enters the heat storage tank 9, and the cycle is repeated.

[0105] The ethanol (heat exchange medium) at -110°C in the cold storage tank 11 enters the condenser 14, and after condensing the compressed gas, the temperature of the ethanol rises to -60°C, and then enters the refrigerator 13 to supply cold to the outside, and the temperature of the ethanol rises to 0°C, and then enters the fourth indirect heat exchanger 16. After the ethanol exchanges heat with the heat transfer oil, the temperature rises to 40°C, and then enters the first, second, and third second indirect heat exchangers 7 respectively, to heat the gas after expansion work, and the temperature of the ethanol drops to -110°C, and then enters the cold storage tank 11. This cycle is repeated, so that the condensation process of carbon dioxide can be completed without relying on additional refrigeration equipment, effectively utilizing the capacity of compressed gas, helping to save energy consumption, simplifying the structure of the CCUS carbon capture system, and reducing the overall cost.

[0106] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A CCUS carbon capture system, comprising a gas compression cooling unit, a carbon dioxide separation unit and a turbine power generation unit connected in sequence; the gas compression cooling unit comprises at least two compressors (2) connected in sequence, and a first indirect heat exchanger (3) is provided after each stage of the compressor (2); the carbon dioxide separation unit comprises an indirect condenser (14), an air inlet of the indirect condenser (14) is connected to the first indirect heat exchanger (3) after the last stage of the compressor (2), a condensate outlet of the indirect condenser (14) is connected to a carbon dioxide storage tank (12), and an air outlet of the indirect condenser (14) is connected to a gas storage tank (4); the characteristic is that: The turbine power generation unit comprises a generator (6) and at least two stages of turbines (5) connected in sequence, the turbine (5) being transmission-connected to the generator (6), the air outlet of each stage of the turbine (5) being connected to a second indirect heat exchanger (7), the air storage tank (4) being connected to the air inlet of the first stage of the turbine (5); the condensing medium inlet of the indirect condenser (14) being connected to the heat source outlet of each second indirect heat exchanger (7); The condensing medium outlet of the indirect condenser (14) is connected to the cold source inlet of each first indirect heat exchanger (3), and the cold source outlet of each first indirect heat exchanger (3) is connected to the heat source inlet of each second indirect heat exchanger (7); or, further comprising a fourth indirect heat exchanger (16), the fourth indirect heat exchanger (16) comprising a first medium inlet and a first medium outlet which are connected to each other, and a second medium inlet and a second medium outlet which are connected to each other, the cold source inlet of each first indirect heat exchanger (3) is connected to the first medium outlet, and the cold source outlet of each first indirect heat exchanger (3) is connected to the first medium inlet, the condensing medium outlet of the indirect condenser (14) is connected to the second medium inlet, and the second medium outlet is connected to the heat source inlet of each second indirect heat exchanger (7).

2. The CCUS carbon capture system according to claim 1, characterized in that: The number of compressors (2) is 3-6.

3. The CCUS carbon capture system according to claim 1, characterized in that: The condensing medium outlet of the indirect condenser (14) is connected to a cooling device (13); the outlet of the cooling device (13) is connected to the cold source inlet of each first indirect heat exchanger (3), or the outlet of the cooling device (13) is connected to the second medium inlet.

4. The CCUS carbon capture system according to claim 1, characterized in that: The heat source outlet of each second indirect heat exchanger (7) is connected to the condensing medium inlet of the indirect condenser (14).

5. The CCUS carbon capture system according to claim 1, characterized in that: The condensing medium inlet of the indirect condenser (14) is connected to a cold storage tank (11), and the inlet of the cold storage tank (11) is connected to the heat source outlet of each second indirect heat exchanger (7).

6. The CCUS carbon capture system according to claim 1, characterized in that: The CCUS carbon capture system further comprises a heat storage tank (9); an inlet of the heat storage tank (9) is connected to a cold source outlet of each first indirect heat exchanger (3); an outlet of the heat storage tank (9) is connected to a heat source inlet of each second indirect heat exchanger (7), or the outlet of the heat storage tank (9) is connected to a first medium inlet.

7. The CCUS carbon capture system according to claim 6, characterized in that: A heat supplier (10) is provided between the heat storage tank (9) and the second indirect heat exchanger (7), or a heat supplier (10) is provided between the heat storage tank (9) and the first medium inlet.

8. A CCUS method, characterized in that: The CCUS carbon capture system according to any one of claims 1 to 7 is used, and the CCUS method comprises the following steps: S1. performing at least two rounds of compression and indirect cooling on the gas containing carbon dioxide to obtain compressed gas; S2. Performing indirect condensation treatment on the compressed gas to obtain residual compressed gas and carbon dioxide liquid and / or solid; S3, inputting at least part of the remaining compressed gas into a turbine power generation unit, so that the remaining compressed gas undergoes at least two rounds of expansion and heating treatments in sequence to obtain expanded gas and electrical energy; Among them, the cooling medium used in the indirect cooling treatment in S1 is the condensing medium generated by the indirect condensation treatment in S2, or the cooling medium used in the indirect cooling treatment in S1 is the cooling medium after indirect heat exchange with the condensing medium generated by the indirect condensation treatment in S2; the condensing medium used in the indirect condensation treatment in S2 is the heating medium generated by the heating treatment in S3; the heating medium used in the heating treatment in S3 is the cooling medium generated by the indirect cooling treatment in S1, or the heating medium used in the heating treatment in S3 is the condensing medium generated by the indirect condensation treatment in S2 and after indirect heat exchange with the cooling medium generated by the indirect cooling treatment in S1.

9. The CCUS method according to claim 8, characterized in that: The temperature of the expanded gas is below the condensation temperature of carbon dioxide and above the condensation temperature of nitrogen and / or oxygen.

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