Method and apparatus for purifying industrial off-gas liquid carbon dioxide

Abstract

A method and device for purifying liquefied carbon dioxide from industrial tail gas, which can be applied in the field of compressed air energy storage, etc. The specific method comprises the following steps: S1, the original gas is compressed and dehydrated, and is cooled to normal temperature liquid carbon dioxide; the heat energy generated in the above process is stored; S2, the liquid carbon dioxide product is pressurized to high-pressure liquid carbon dioxide product, and is stored in a high-pressure storage chamber; S3, the high-pressure carbon dioxide in the high-pressure storage chamber is expanded through a first heat exchanger, and is heated to high-temperature high-pressure supercritical carbon dioxide product; the high-pressure storage chamber supplies heat for the first heat exchanger; the supercritical carbon dioxide product is introduced into an expander to expand and do work; S4, high-pressure liquid carbon dioxide product is obtained. Through the above structure, the problems of low energy utilization rate and the fact that the compression heat cannot be effectively utilized in the existing industrial tail gas carbon dioxide purification process are solved.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide recovery and utilization technology, specifically to a method and apparatus for purifying and liquefying carbon dioxide from industrial exhaust gas. Background Technology

[0002] Chemical industry exhaust gases typically contain large amounts of carbon dioxide. Recycling and utilizing this carbon dioxide can protect the environment and bring economic benefits to enterprises. Currently, carbon dioxide is generally processed into liquid or solid products for easier transportation and use.

[0003] Efficiently recovering and utilizing carbon dioxide from industrial waste gas, and leveraging the heat of compression in the carbon dioxide recovery system to improve energy efficiency, are pressing technical problems that urgently need to be solved by those skilled in the art. For example, in the coal-to-hydrogen process, the produced carbon dioxide can achieve a purity of over 98%, saving on the cost of carbon capture technology. However, the aforementioned carbon dioxide purification and liquefaction process in industrial waste gas is simple, resulting in a large amount of unutilized heat of compression and a significant waste of energy resources. Therefore, those skilled in the art urgently need an open-loop compressed carbon dioxide energy storage system coupled with an industrial waste gas carbon dioxide purification and liquefaction system to efficiently recover the heat of compression in the system, thereby improving energy efficiency. Simultaneously, it should enable flexible multi-grade output of liquid carbon dioxide products, utilizing the high energy density and high efficiency of supercritical carbon dioxide energy storage technology to absorb a high proportion of renewable energy. Summary of the Invention

[0004] This invention aims to provide a method and apparatus for purifying and liquefying carbon dioxide from industrial exhaust gas, which can solve the problems of ineffective utilization of compression heat and low energy efficiency in existing technologies. Therefore, this invention provides a method for purifying and liquefying carbon dioxide from industrial exhaust gas, comprising the following steps:

[0005] S1, the original gas is compressed and dehydrated through a compression mechanism and a gas-liquid separation mechanism to obtain liquid carbon dioxide product;

[0006] A first intercooler is also provided between the compression mechanism and the gas-liquid separation mechanism. The first intercooler is used to cool high-temperature gaseous carbon dioxide into room-temperature liquid carbon dioxide. Furthermore, the first intercooler is connected to a heat storage tank to store thermal energy in the heat storage tank.

[0007] S2, the liquid carbon dioxide product passing through the compression mechanism is driven into the pressure pump, pressurized to high pressure liquid carbon dioxide product and stored in the high pressure storage chamber;

[0008] S3, the high-pressure carbon dioxide in the high-pressure storage chamber expands and is heated to a high-temperature and high-pressure supercritical carbon dioxide product via the first heat exchanger; the heat storage tank supplies heat to the first heat exchanger.

[0009] Afterwards, the supercritical carbon dioxide product is fed into an expander to expand and do work, causing the pressure to drop;

[0010] S4, the carbon dioxide working medium passing through the expander is purified and liquefied in the industrial exhaust gas by a high-pressure method to obtain a high-pressure liquid carbon dioxide product.

[0011] Optionally, in step S1, the compression mechanism is a multi-stage compression structure including at least two compressors; and each compressor is provided with a first intercooler and a gas-liquid separator at its outlet position in sequence.

[0012] Optionally, in step S1, the raw gas is converted into liquid carbon dioxide at 7 MPa and 20°C by the compression mechanism;

[0013] In step S2, the pressure pump pressurizes liquid carbon dioxide at 7 MPa and 20°C, converting it into liquid carbon dioxide at at least 30 MPa.

[0014] In step S3, the pressure of the carbon dioxide produced by the expander is reduced to 7 MPa.

[0015] Optionally, in step S3, there are at least two expanders, and each expander inlet is provided with a first heat exchanger.

[0016] Optionally, in step S3, a second heat exchanger is also provided at the outlet of the expander. The second heat exchanger is used to cool the carbon dioxide working fluid passing through the expander. After that, the cooled carbon dioxide working fluid enters step S4.

[0017] Optionally, in step S3, the second heat exchanger cools the carbon dioxide working fluid passing through the expander to 23°C.

[0018] An apparatus for purifying liquefied carbon dioxide, comprising:

[0019] The compression mechanism includes: at least two compressors for increasing the pressure of the raw gas; the outlet of the compressor is connected to a gas-liquid separator for increasing the pressure of the raw gas and dehydrating the raw gas;

[0020] The first cooler is located between the compressor and the gas-liquid separator, and is used to cool high-temperature gaseous carbon dioxide into room-temperature liquid carbon dioxide.

[0021] A heat storage tank, connected to the first intercooler, is used to store the heat energy absorbed by the first intercooler from the high-temperature gaseous carbon dioxide.

[0022] A pressure pump is connected to the outlet of the compression mechanism to pressurize the liquid carbon dioxide product that has passed through the compression mechanism;

[0023] A high-pressure storage chamber, connected to the outlet of the pressure pump, is used to store carbon dioxide products pressurized by the pressure pump;

[0024] The first heat exchanger is located in the outlet direction of the high-pressure storage chamber and is used to heat the high-pressure carbon dioxide to a supercritical carbon dioxide product.

[0025] The expander is connected to the outlet of the first heat exchanger and performs work by expanding supercritical carbon dioxide under high temperature and high pressure.

[0026] A second heat exchanger is located at the outlet of the expander, and the second heat exchanger is used to cool down the carbon dioxide working fluid passing through the expander.

[0027] High-pressure carbon dioxide purification equipment is used to prepare high-pressure liquid carbon dioxide products.

[0028] Optionally, the high-pressure carbon dioxide purification equipment includes:

[0029] The carbon dioxide working medium, cooled by the second heat exchanger, enters the distillation column; the distillation column is used to distill the raw gas, and the non-condensable gas is separated from the top of the distillation column, while the high-purity carbon dioxide product is released from the bottom of the column.

[0030] A reboiler is connected to the bottom of the distillation column, allowing the liquid raw gas at the bottom of the distillation column to be vaporized again.

[0031] The third heat exchanger is located at the outlet of the distillation column and is used to cool the high-temperature carbon dioxide product discharged from the reboiler to output liquid carbon dioxide product at 7MPa and 20℃.

[0032] Optionally, the high-pressure carbon dioxide purification equipment further includes: a refrigeration compressor unit for providing cooling energy to the second heat exchanger and the third heat exchanger;

[0033] The refrigeration compressor unit is connected to the cold source pipeline of the second heat exchanger and / or the third heat exchanger, and is used to cool the refrigerant in the cold source pipeline. The refrigeration compressor unit includes:

[0034] A refrigeration compressor is used to compress low-pressure gaseous refrigerant to high pressure.

[0035] The compressor heat exchanger is connected to the outlet of the refrigeration compressor. The compressor heat exchanger is used to dissipate heat from the high-temperature, high-pressure gaseous refrigerant to the environment, so as to convert it into a high-pressure, room-temperature gaseous refrigerant.

[0036] The compressor unit throttling valve is connected to the outlet of the compressor unit heat exchanger and to the second heat exchanger and / or the third heat exchanger, and is used to convert high-pressure, room-temperature gaseous refrigerant into low-pressure, low-temperature liquid refrigerant through throttling.

[0037] The technical solution of this invention has the following advantages:

[0038] 1. The method for purifying and liquefying carbon dioxide from industrial exhaust gas provided by the present invention includes the following steps:

[0039] S1, the original gas is compressed and dehydrated through a compression mechanism and a gas-liquid separation mechanism to obtain liquid carbon dioxide product;

[0040] A first intercooler is also provided between the compression mechanism and the gas-liquid separation mechanism. The first intercooler is used to cool high-temperature gaseous carbon dioxide into room-temperature liquid carbon dioxide. Furthermore, the first intercooler is connected to a heat storage tank to store thermal energy in the heat storage tank.

[0041] S2, the liquid carbon dioxide product passing through the compression mechanism is driven into the pressure pump, pressurized to high pressure liquid carbon dioxide product and stored in the high pressure storage chamber;

[0042] S3, the high-pressure carbon dioxide in the high-pressure storage chamber expands and is heated to a high-temperature and high-pressure supercritical carbon dioxide product via the first heat exchanger; the heat storage tank supplies heat to the first heat exchanger.

[0043] Afterwards, the supercritical carbon dioxide product is fed into an expander to expand and do work, causing the pressure to drop;

[0044] S4, the carbon dioxide working medium passing through the expander is purified and liquefied in the industrial exhaust gas by a high-pressure method to obtain a high-pressure liquid carbon dioxide product.

[0045] In this invention, the method for purifying and liquefying carbon dioxide from industrial waste gas can yield liquid carbon dioxide at 7 MPa and 20°C, thereby reducing the transportation cost of liquid carbon dioxide. Furthermore, this invention includes a first cooler and a heat storage tank to collect the heat of compression. In conjunction with the high-pressure storage chamber and pressure pump, the pressure is increased, enabling the use of the heat of compression and expansion to perform work, achieving energy conservation and improving product economic efficiency. In this invention, by utilizing the heat of compression during the purification and liquefaction process through the first cooler and heat storage tank, and using carbon dioxide as the working fluid, an open-loop compressed carbon dioxide energy storage system is formed, thus solving the problems of wasted heat of compression and low system energy efficiency. This system can also be used for storing electricity, regulating grid load, and addressing peak-valley electricity price differences, providing an effective solution for energy transition and renewable energy development.

[0046] 2. The method for purifying and liquefying carbon dioxide from industrial exhaust gas provided by the present invention, in step S1, the compression mechanism is a multi-stage compression structure including at least two compressors; and each compressor outlet position is sequentially provided with a first intercooler and a gas-liquid separator.

[0047] In this invention, the compression effect of the raw gas in step S1 can be effectively improved by using the multi-stage compression structure, the first intercooler, and the gas-liquid separator, thereby improving the product conversion rate of industrial exhaust gas and obtaining carbon dioxide products that meet the requirements.

[0048] 3. In the method for purifying and liquefying carbon dioxide from industrial exhaust gas provided by the present invention, in step S3, there are at least two expanders, and each expander is provided with a first heat exchanger at its inlet position.

[0049] In this invention, by setting up a multi-stage expander and supplying heat to multiple first heat exchangers through a heat storage tank, the expansion effect of the expander can be effectively improved and energy consumption can be saved, thereby enhancing the economic benefits of the product.

[0050] 4. The apparatus for purifying and liquefying carbon dioxide provided by the present invention comprises:

[0051] The compression mechanism includes: at least two compressors for increasing the pressure of the raw gas; the outlet of the compressor is connected to a gas-liquid separator for increasing the pressure of the raw gas and dehydrating the raw gas;

[0052] The first cooler is located between the compressor and the gas-liquid separator, and is used to cool high-temperature gaseous carbon dioxide into room-temperature liquid carbon dioxide.

[0053] A heat storage tank, connected to the first intercooler, is used to store the heat energy absorbed by the first intercooler from the high-temperature gaseous carbon dioxide.

[0054] A pressure pump is connected to the outlet of the compression mechanism to pressurize the liquid carbon dioxide product that has passed through the compression mechanism;

[0055] A high-pressure storage chamber, connected to the outlet of the pressure pump, is used to store carbon dioxide products pressurized by the pressure pump;

[0056] The first heat exchanger is located in the outlet direction of the high-pressure storage chamber and is used to heat the high-pressure carbon dioxide to a supercritical carbon dioxide product.

[0057] The expander is connected to the outlet of the first heat exchanger and performs work by expanding supercritical carbon dioxide under high temperature and high pressure.

[0058] A second heat exchanger is located at the outlet of the expander, and the second heat exchanger is used to cool down the carbon dioxide working fluid passing through the expander.

[0059] High-pressure carbon dioxide purification equipment is used to prepare high-pressure liquid carbon dioxide products.

[0060] The device described above in this invention can produce liquid carbon dioxide at 7 MPa and 20°C. Furthermore, the heat storage tank can store the heat energy absorbed by the first intercooler from the high-temperature gaseous carbon dioxide, thereby powering the first heat exchanger. The pressure is then increased through a high-pressure storage chamber and a pressure pump, utilizing the heat of compression and expansion to achieve energy savings.

[0061] 5. The liquefied carbon dioxide purification apparatus provided by the present invention, wherein the high-pressure carbon dioxide purification equipment comprises:

[0062] The carbon dioxide working medium, cooled by the second heat exchanger, enters the distillation column; the distillation column is used to distill the raw gas, and the non-condensable gas is separated from the top of the distillation column, while the high-purity carbon dioxide product is released from the bottom of the column.

[0063] A reboiler is connected to the bottom of the distillation column, allowing the liquid raw gas at the bottom of the distillation column to be vaporized again.

[0064] The third heat exchanger is located at the outlet of the distillation column and is used to cool the high-temperature carbon dioxide product discharged from the reboiler to output liquid carbon dioxide product at 7MPa and 20℃.

[0065] In this invention, liquid carbon dioxide products at 7MPa and 20°C can be effectively produced using the high-pressure carbon dioxide purification equipment described above.

[0066] 6. The liquefied carbon dioxide purification device provided by the present invention further includes: a refrigeration compressor unit for providing cooling energy to the second heat exchanger and the third heat exchanger; the refrigeration compressor unit is connected to the cold source pipelines of the second heat exchanger and the third heat exchanger, and is used to cool the refrigerant in the cold source pipelines.

[0067] The refrigeration compressor unit includes:

[0068] A refrigeration compressor is used to compress low-pressure gaseous refrigerant to high pressure.

[0069] The compressor heat exchanger is connected to the outlet of the refrigeration compressor. The compressor heat exchanger is used to dissipate heat from the high-temperature, high-pressure gaseous refrigerant to the environment, so as to convert it into a high-pressure, room-temperature gaseous refrigerant.

[0070] The compressor unit throttling valve is connected to the outlet of the compressor unit heat exchanger and to the second heat exchanger and / or the third heat exchanger, and is used to convert high-pressure, room-temperature gaseous refrigerant into low-pressure, low-temperature liquid refrigerant through throttling.

[0071] In this invention, the refrigeration compressor unit described above can cool the refrigerant in both the second heat exchanger and the third heat exchanger, thereby ensuring the normal heat exchange and cooling effect of the second heat exchanger and the third heat exchanger. Attached Figure Description

[0072] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0073] Figure 1 This invention provides a schematic diagram of the structure of an industrial exhaust gas purification and liquefaction carbon dioxide equipment.

[0074] Explanation of reference numerals in the attached figures:

[0075] 1-Compressor; 2-Gas-liquid separator; 3-First intercooler; 4-Heat storage tank; 5-Pressure pump; 6-High-pressure storage chamber; 7-First heat exchanger; 8-Expander; 9-Second heat exchanger; 10-Distillation column; 11-Reboiler; 12-Third heat exchanger; 13-Refrigeration compressor; 14-Compressor unit heat exchanger; 15-Compressor unit throttle valve. Detailed Implementation

[0076] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0077] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0078] Example 1

[0079] A method for purifying and liquefying carbon dioxide from industrial exhaust gas is described, such as... Figure 1 As shown, it includes the following steps:

[0080] S1, the original gas is compressed and dehydrated through a compression mechanism and a gas-liquid separation mechanism, and converted into liquid carbon dioxide at 7MPa and 20℃; in this embodiment, in order to improve the compression mechanism, in step S1, the compression mechanism is a multi-stage compression structure including 6 compressors 1; and each compressor 1 is provided with a first intercooler 3 and a gas-liquid separator 2 at its outlet position in sequence.

[0081] A first intercooler 3 is also provided between the compression mechanism and the gas-liquid separation mechanism. The first intercooler 3 is used to cool high-temperature gaseous carbon dioxide into room-temperature liquid carbon dioxide. Furthermore, the first intercooler 3 is connected to the heat storage tank 4 to store thermal energy in the heat storage tank 4.

[0082] S2, the liquid carbon dioxide product passed through the compression mechanism is driven into the pressure pump 5, which pressurizes the liquid carbon dioxide at 7 MPa and 20°C to convert it into liquid carbon dioxide at at least 30 MPa; then, the above-mentioned pressurized liquid carbon dioxide product is stored in the high-pressure storage chamber 6.

[0083] S3, the high-pressure carbon dioxide in the high-pressure storage chamber 6 expands and is heated to a high-temperature and high-pressure supercritical carbon dioxide product via the first heat exchanger 7; the heat storage tank 4 supplies heat to the first heat exchanger 7.

[0084] Afterwards, the supercritical carbon dioxide product is fed into the expander 8 to expand and do work, and the pressure drops to 7MPa; in this step S3, there are two expanders 8, and each expander 8 is provided with a first heat exchanger 7 at its inlet position;

[0085] In addition, a second heat exchanger 9 is provided at the outlet of the expander 8. The second heat exchanger 9 is used to cool down the carbon dioxide working medium passing through the expander 8. After that, the cooled carbon dioxide working medium enters the step S4. The second heat exchanger 9 cools the carbon dioxide working medium passing through the expander 8 to 23°C.

[0086] S4, the carbon dioxide working medium passing through the expander 8 is purified and liquefied in the industrial exhaust gas by a high-pressure method to obtain a high-pressure liquid carbon dioxide product.

[0087] A carbon dioxide purification and liquefaction apparatus using a method for purifying and liquefying carbon dioxide from industrial waste gas, such as... Figure 1 As shown, it includes:

[0088] The compression mechanism includes: six compressors 1 for increasing the pressure of the raw gas; the outlet of each compressor 1 is connected to a gas-liquid separator 2 for increasing the pressure of the raw gas and dehydrating the raw gas;

[0089] The first cooler 3 is disposed between the compressor 1 and the gas-liquid separator 2, and is used to cool high-temperature gaseous carbon dioxide into room-temperature liquid carbon dioxide.

[0090] The heat storage tank 4 is connected to the first intercooler 3 and is used to store the heat energy absorbed by the first intercooler 3 from the high-temperature gaseous carbon dioxide.

[0091] Pressure pump 5 is connected to the outlet of the compression mechanism to pressurize the liquid carbon dioxide product that has passed through the compression mechanism;

[0092] The high-pressure storage chamber 6 is connected to the outlet of the pressure pump 5 and is used to store carbon dioxide products pressurized by the pressure pump 5.

[0093] The first heat exchanger 7 is located in the outlet direction of the high-pressure storage chamber 6 and is used to heat the high-pressure carbon dioxide to a supercritical carbon dioxide product.

[0094] Expander 8 is connected to the outlet of the first heat exchanger 7 and performs work through the expansion of supercritical carbon dioxide under high temperature and high pressure.

[0095] The second heat exchanger 9 is located at the outlet of the expander 8 and is used to cool down the carbon dioxide working fluid passing through the expander 8.

[0096] High-pressure carbon dioxide purification equipment is used to prepare high-pressure liquid carbon dioxide products.

[0097] In this embodiment, as Figure 1 The high-pressure carbon dioxide purification equipment shown includes:

[0098] Carbon dioxide working medium cooled by the second heat exchanger 9 enters the distillation column 10; the distillation column 10 is used to distill the raw gas, non-condensable gas is separated from the top of the distillation column 10, and high-purity carbon dioxide product is released from the bottom of the column.

[0099] The reboiler 11 is connected to the bottom of the distillation column 10, so that the liquid raw gas at the bottom of the distillation column 10 is vaporized again.

[0100] The third heat exchanger 12 is located at the outlet of the distillation column 10 and is used to cool the high-temperature carbon dioxide product discharged from the reboiler 11 to output liquid carbon dioxide product at 7MPa and 20℃.

[0101] In addition, to provide cooling energy to the second heat exchanger 9 and the third heat exchanger 12, the high-pressure carbon dioxide purification equipment also includes a refrigeration compressor unit.

[0102] The refrigeration compressor unit is connected to the cold source pipelines of the second heat exchanger 9 and the third heat exchanger 12, and is used to cool the refrigerant in the cold source pipelines. The refrigeration compressor unit includes:

[0103] Refrigeration compressor 13 is used to compress low-pressure gaseous refrigerant to high pressure;

[0104] The compressor heat exchanger 14 is connected to the outlet of the refrigeration compressor 13. The compressor heat exchanger 14 is used to dissipate heat from the high-temperature, high-pressure gaseous refrigerant to the environment, so as to convert it into a high-pressure, room-temperature gaseous refrigerant.

[0105] The compressor unit throttling valve 15 is connected to the outlet of the compressor unit heat exchanger 14, and to the second heat exchanger 9 and the third heat exchanger 12, for converting high-pressure, room-temperature gaseous refrigerant into low-pressure, low-temperature liquid refrigerant through throttling.

[0106] Of course, in this embodiment, there is no specific limitation on the pressure and temperature of the original gas being compressed and dehydrated by the compression mechanism and the gas-liquid separation mechanism to convert it into liquid carbon dioxide; and there is no specific limitation on the pressure value to which the pressure pump 5 pressurizes the liquid carbon dioxide; in addition, there is no specific limitation on the pressure value to which the supercritical carbon dioxide product is introduced into the expander 8 to expand and do work. In other embodiments, the operator can adjust the temperature and pressure of the carbon dioxide according to actual needs.

[0107] Of course, in this embodiment, the number of compressors 1 in the compression mechanism is not specifically limited. In other embodiments, the compression mechanism may include other numbers of compressors 1.

[0108] Of course, in this embodiment, the number of expanders 8 is not specifically limited. In other embodiments, there may be 3 expanders or other numbers.

[0109] Of course, in this embodiment, the target of the refrigeration compressor unit is not specifically limited. In other embodiments, the refrigeration compressor unit is only connected to the cold source pipeline of one of the second heat exchanger 9 and the third heat exchanger 12, and is used to cool the refrigerant in the cold source pipeline connected to it.

[0110] Of course, in this embodiment, the pressure and temperature of the liquid carbon dioxide produced by the compression mechanism and the gas-liquid separation mechanism compressing and dehydrating the original gas are not specifically limited. In other embodiments, the compression mechanism and the gas-liquid separation mechanism compress and dehydrate the original gas to produce liquid carbon dioxide at 6 MPa and 21°C, or other pressure and temperature values.

[0111] Of course, in this embodiment, the specific temperature value at which the second heat exchanger 9 cools the carbon dioxide working medium is not specifically limited. In other embodiments, the second heat exchanger 9 cools the carbon dioxide working medium that has passed through the expander 8 to 22°C or other temperatures.

[0112] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A device for purifying liquefied carbon dioxide, characterized by comprising: include: The compression mechanism includes: at least two compressors (1) for increasing the pressure of the raw gas; the outlet of the compressors (1) is connected to a gas-liquid separator (2) for increasing the pressure of the raw gas and dehydrating the raw gas; The first cooler (3) is located between the compressor (1) and the gas-liquid separator (2) and is used to cool high-temperature gaseous carbon dioxide into room-temperature liquid carbon dioxide. A heat storage tank (4) is connected to the first intercooler (3) and is used to store the heat energy absorbed by the first intercooler (3) from the high-temperature gaseous carbon dioxide. A pressure pump (5) is connected to the outlet of the compression mechanism to pressurize the liquid carbon dioxide product that has passed through the compression mechanism; The high-pressure storage chamber (6) is connected to the outlet of the pressure pump (5) and is used to store carbon dioxide products pressurized by the pressure pump (5); The first heat exchanger (7) is located in the outlet direction of the high-pressure storage chamber (6) and is used to heat the high-pressure carbon dioxide to a supercritical carbon dioxide product. The expander (8) is connected to the outlet of the first heat exchanger (7) and performs work by expanding supercritical carbon dioxide under high temperature and high pressure. The second heat exchanger (9) is located at the outlet of the expander (8) and is used to cool the carbon dioxide working fluid passing through the expander (8). High-pressure carbon dioxide purification equipment is used to prepare high-pressure liquid carbon dioxide products; The high-pressure carbon dioxide purification equipment includes: The carbon dioxide working medium, cooled by the second heat exchanger (9), enters the distillation column (10); the distillation column (10) is used to distill the raw gas, the non-condensable gas is separated from the top of the distillation column (10), and the high-purity carbon dioxide product is released from the bottom of the column; The reboiler (11) is connected to the bottom of the distillation column (10) so that the liquid original gas at the bottom of the distillation column (10) is vaporized again. The third heat exchanger (12) is located at the outlet of the distillation column (10) to cool down the high-temperature carbon dioxide product discharged from the reboiler (11) so as to output liquid carbon dioxide product at 7MPa and 20℃. A refrigeration compressor unit for providing cooling energy to the second heat exchanger (9) and the third heat exchanger (12); the refrigeration compressor unit is connected to the cold source pipeline of the second heat exchanger (9) and / or the third heat exchanger (12) for cooling the refrigerant in the cold source pipeline, the refrigeration compressor unit comprising: A refrigeration compressor (13) is used to compress a low-pressure gaseous refrigerant to a high-pressure state; The compressor heat exchanger (14) is connected to the outlet of the refrigeration compressor (13). The compressor heat exchanger (14) is used to dissipate heat from the high-temperature, high-pressure gaseous refrigerant to the environment, so as to convert it into a high-pressure, room-temperature gaseous refrigerant. The compressor unit throttle valve (15) is connected to the outlet of the compressor unit heat exchanger (14) and to the second heat exchanger (9) and / or the third heat exchanger (12), and is used to convert high-pressure, room-temperature gaseous refrigerant into low-pressure, low-temperature liquid refrigerant through throttling.

2. A method of purifying industrial off-gas liquid carbon dioxide, characterized by, The method, applied to the purification and liquefaction carbon dioxide apparatus of claim 1, comprises the following steps: S1, the original gas is compressed and dehydrated through a compression mechanism and a gas-liquid separation mechanism to obtain liquid carbon dioxide product; A first intercooler (3) is provided between the compression mechanism and the gas-liquid separation mechanism. The first intercooler (3) is used to cool high-temperature gaseous carbon dioxide into room-temperature liquid carbon dioxide. The first intercooler (3) is connected to the heat storage tank (4) to store thermal energy in the heat storage tank (4). S2, the liquid carbon dioxide product passing through the compression mechanism is driven into the pressure pump (5), pressurized to high pressure liquid carbon dioxide product and stored in the high pressure storage chamber (6); S3, the high-pressure carbon dioxide in the high-pressure storage chamber (6) expands and is heated to a high-temperature and high-pressure supercritical carbon dioxide product through the first heat exchanger (7); the heat storage tank (4) supplies heat to the first heat exchanger (7). Afterwards, the supercritical carbon dioxide product is fed into the expander (8) to expand and do work, and the pressure drops. The outlet of the expander (8) is also provided with a second heat exchanger (9), which is used to cool the carbon dioxide working medium that has passed through the expander (8). Afterwards, the cooled carbon dioxide working medium enters the step S4. S4, the carbon dioxide working medium passed through the expander (8) is purified and liquefied in the industrial tail gas by high pressure method to obtain high pressure liquid carbon dioxide product.

3. The method of purifying industrial off-gas liquefied carbon dioxide according to claim 2, characterized by, In step S1, the compression mechanism is a multi-stage compression structure including at least two compressors (1); and each compressor (1) is provided with a first intercooler (3) and a gas-liquid separator (2) at its outlet position.

4. The method of purifying industrial off-gas liquefied carbon dioxide according to claim 2, characterized by, In step S1, the raw gas is converted into liquid carbon dioxide at 7 MPa and 20°C by the compression mechanism; In step S2, the pressure pump (5) pressurizes liquid carbon dioxide at 7 MPa and 20°C, converting it into liquid carbon dioxide at at least 30 MPa. In step S3, the pressure of carbon dioxide reduced to 7 MPa after work is performed by the expander (8).

5. The method of purifying industrial off-gas liquefied carbon dioxide according to claim 2, characterized by, In step S3, there are at least two expanders (8), and each expander (8) is provided with a first heat exchanger (7) at its inlet position.

6. The method of purifying industrial off-gas liquefied carbon dioxide according to claim 2, characterized by, In step S3, the second heat exchanger (9) cools the carbon dioxide working fluid passing through the expander (8) to 23°C.

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