Carbon dioxide compressing and drying system

Abstract

The invention relates to the technical field of carbon dioxide drying, and discloses a carbon dioxide compression drying system. The system comprises a compression device, a heat exchanger, a heater, a drying unit, a cooler and a gas-liquid separator, the compression device comprises a third-stage compression module, and the third-stage compression module comprises a third-stage compressor and a third-stage cooler connected with the third-stage compressor; wet carbon dioxide gas output by the third-stage cooler enters the drying unit through a first input end of the drying unit and is output through a first output end of the drying unit; carbon dioxide gas output by the third-stage compressor exchanges heat with purging gas from the drying unit in a heat exchanger; the heat-exchanged purging gas sequentially enters a cooler and a gas-liquid separator, and obtained gas-phase carbon dioxide enters the drying unit through a first input end of the drying unit; and the carbon dioxide gas after heat exchange is heated by the heater, enters the drying unit from the second input end of the drying unit, and is output through the second output end of the drying unit to form purging gas.

Description

Technical Field

[0001] The invention relates to the technical field of carbon dioxide drying, and in particular to a carbon dioxide compression drying system. Background Art

[0002] For CO2 capture, storage and utilization technology, CO2 often needs to be compressed and liquefied for easy transportation and storage. In the traditional process, the high-purity CO2 captured by the carbon dioxide capture system is compressed by the compressor unit 100 and interstage cooled before being pressurized and cooled to 25bar / 25°C. The generated CO2 needs to be further dried and dehydrated, where a portion of the CO2 is heated and used for purging of the drying device, and the liquid phase is separated in the separation tank after cooling, and the gas phase is sent to the drying tower together with the other portion of CO2 for adsorption drying. The drying tower often adopts a multi-tower arrangement, and the source of the stream is cyclically switched to achieve adsorption and desorption of the bed, and maintain continuous operation. The dried CO2 is sent to the refrigeration unit for liquefaction, and finally a liquid CO2 product at 25bar / -25°C is obtained.

[0003] However, the main disadvantage of this process is its high energy consumption. The waste heat during the CO2 compression process is as high as 100-140°C, and the drying system consumes electricity to heat a portion of the CO2 for purging the drying tower. The waste heat of the purge gas after purging can reach more than 200°C, and this waste heat is often directly taken away by cooling water, resulting in a large amount of energy loss. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of high energy consumption and low utilization of the system's own waste heat in the prior art, and to provide a carbon dioxide compression and drying system, which can improve the utilization of the system's own heat while reducing the provision of external cold sources, reducing the overall energy consumption of the system and the consumption of circulating cooling water.

[0005] In order to achieve the above object, the present invention provides a carbon dioxide compression and drying system, which includes a compression device, a heat exchanger, a heater, a drying unit, a cooler and a gas-liquid separator; The compression device comprises a three-stage compression module, wherein the three-stage compression module comprises a three-stage compressor and a three-stage cooler connected to the three-stage compressor; The tertiary cooler is connected to the first input end of the drying unit; The wet carbon dioxide gas outputted by the three-stage cooler enters the drying unit through the first input end of the drying unit to be dried and is outputted through the first output end of the drying unit; The three-stage compressor is connected to the heat exchanger, the heat exchanger is connected to the heater, and the heater is connected to the second input end of the drying unit; The carbon dioxide gas output by the three-stage compressor exchanges heat with the purge gas from the drying unit in the heat exchanger; The purge gas after heat exchange enters the cooler for cooling, and the cooled purge gas enters the gas-liquid separator for gas-liquid separation to obtain gaseous carbon dioxide, and the gaseous carbon dioxide enters the drying unit through the first input end of the drying unit for drying; The carbon dioxide gas after heat exchange enters the heater for heating, and the heated carbon dioxide gas enters the drying unit through the second input end of the drying unit to purge the drying unit and is output through the second output end of the drying unit to form the purge gas.

[0006] Preferably, the carbon dioxide compression drying system further comprises a refrigeration unit connected to the first output end of the drying unit.

[0007] Preferably, the compression device further comprises a primary compression module and a secondary compression module connected to the primary compression module; the secondary compression module is connected to the tertiary compression module.

[0008] Preferably, the primary compression module comprises a primary compressor and a primary cooler connected to the primary compressor.

[0009] Preferably, the secondary compression module comprises a secondary compressor and a secondary cooler connected to the secondary compressor.

[0010] Preferably, the drying unit comprises a first drying tower and a second drying tower.

[0011] Preferably, the top inlet of the first drying tower and the top inlet of the second drying tower are both connected to the tertiary cooler.

[0012] Preferably, the bottom inlet of the first drying tower and the bottom inlet of the second drying tower are both connected to the heater.

[0013] Preferably, the top outlet of the first drying tower and the top outlet of the second drying tower are both connected to the heat exchanger.

[0014] Preferably, the bottom outlet of the first drying tower and the bottom outlet of the second drying tower are both connected to the refrigeration unit.

[0015] Compared with the prior art, the carbon dioxide compression and drying system described in the present invention can improve the utilization of the system's own heat, preheat the compressed carbon dioxide gas through the purge gas generated by the system itself, reduce the supply of external heat, and at the same time, the temperature of the purge gas itself is lowered to reduce the supply of external cold sources, thereby reducing the overall energy consumption of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a structural schematic diagram of a carbon dioxide compression drying system provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of the internal structure of a drying unit provided in an embodiment of the present invention.

[0017] Description of Reference Numerals 2 heat exchanger 3 heater 4 Drying unit 5 Cooler 6Gas-liquid separator 7Refrigeration unit 11 first stage compressor 12 first stage cooler 13 Secondary compressor 14 Secondary cooler 15 three-stage compressor 16 three-stage cooler 41 first drying tower 42 second drying tower 400 first shut-off valve 410 second shut-off valve 420 third shutoff valve 430 fourth shutoff valve 440 fifth shutoff valve 450 sixth shutoff valve 460 seventh shut-off valve 470 eighth shut-off valve DETAILED DESCRIPTION The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0018] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0019] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating relative importance or implicitly indicating the number of technical features indicated. Therefore, unless otherwise specified, features defined as "first" and "second" may explicitly or implicitly include one or more of the features; "plurality" means two or more. The term "including" and any variation thereof means non-exclusive inclusion, and one or more other features, integers, steps, operations, units, components and / or combinations thereof may exist or be added.

[0020] In addition, terms indicating orientation or positional relationships such as "upper", "lower", "inside", and "outside" are described based on the orientation or relative positional relationships shown in the drawings, and are only for the convenience of describing the simplified description of the present application, and do not indicate that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0021] In addition, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internally connected between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0022] The present invention provides a carbon dioxide compression drying system, in combination with Figure 1 , the system includes a compression device, a heat exchanger 2, a heater 3, a drying unit 4, a cooler 5 and a gas-liquid separator 6; The compression device includes a three-stage compression module, and the three-stage compression module includes a three-stage compressor 15 and a three-stage cooler 16 connected to the three-stage compressor 15; The tertiary cooler 16 is connected to the first input end of the drying unit 4; The wet carbon dioxide gas outputted by the tertiary cooler 16 enters the drying unit 4 through the first input end of the drying unit 4 to be dried and is outputted through the first output end of the drying unit 4; The three-stage compressor 15 is connected to the heat exchanger 2, the heat exchanger 2 is connected to the heater 3, and the heater 3 is connected to the second input end of the drying unit 4; The carbon dioxide gas output by the three-stage compressor 15 exchanges heat with the purge gas from the drying unit 4 in the heat exchanger 2; The purge gas after heat exchange enters the cooler 5 for cooling, and the cooled purge gas enters the gas-liquid separator 6 for gas-liquid separation to obtain gaseous carbon dioxide, and the gaseous carbon dioxide enters the drying unit 4 through the first input end of the drying unit 4 for drying; The carbon dioxide gas after heat exchange enters the heater 3 for heating, and the heated carbon dioxide gas enters the drying unit 4 through the second input end of the drying unit 4 to purge the drying unit 4 and is output through the second output end of the drying unit 4 to form the purge gas.

[0023] In the carbon dioxide compression and drying system of the present invention, the carbon dioxide gas to be treated with a temperature of 40°C enters the compression device for compression, the temperature of the wet carbon dioxide gas output by the three-stage cooler 16 is 20-40°C, and the temperature of the carbon dioxide gas output by the three-stage compressor 15 is 100-140°C; The wet carbon dioxide gas outputted from the tertiary cooler 16 enters the drying unit 4 from the first input end of the drying unit 4 and is dried by the adsorbent in the drying unit 4 to form dry carbon dioxide gas, and the dry carbon dioxide gas is outputted from the first output end of the drying unit 4; The carbon dioxide gas outputted by the three-stage compressor 15 exchanges heat with the purge gas with a temperature of 190-240° C. from the drying unit 4 in the heat exchanger 2. The temperature of the carbon dioxide gas after the heat exchange is increased to 180-230° C. The carbon dioxide gas after the heat exchange enters the heater 3 for heating and increases its temperature to 200-240° C. The heated carbon dioxide gas enters the drying unit 4 from the second input end of the drying unit 4 to purge the adsorbent saturated in the drying unit 4 and is outputted through the second output end of the drying unit 4 to form the purge gas, thereby realizing the regeneration of the adsorbent in the drying unit 4; The temperature of the purge gas after heat exchange is reduced to 100-130°C, and the purge gas after heat exchange enters the cooler for cooling. The temperature of the cooled purge gas is reduced to 25-40°C, and the cooled purge gas enters the gas-liquid separator 6 for gas-liquid separation to obtain gaseous carbon dioxide and liquid water. The gaseous carbon dioxide enters the drying unit 4 through the first input end of the drying unit 4 for drying to form dry carbon dioxide, and the dry carbon dioxide gas is output from the first output end of the drying unit 4; the liquid water is output from the liquid phase outlet of the gas-liquid separator for reuse.

[0024] Through the system described in the present invention, the heat of the carbon dioxide gas output by the three-stage compressor 15 and the heat of the purge gas can be utilized, reducing the external heat source required for purging the drying unit 4 with the carbon dioxide gas output by the compression device. At the same time, the external cold source required for cooling the purge gas output from the second output end of the drying unit 4 can also be reduced, thereby reducing the energy consumption required for the entire system.

[0025] In a preferred embodiment, the carbon dioxide compression drying system also includes a refrigeration unit 7 connected to the first output end of the drying unit 4, and the refrigeration unit 7 is used to cool the dry carbon dioxide gas output from the first output end of the drying unit 4 to obtain dry liquid carbon dioxide, which is convenient for storage and transportation.

[0026] In a preferred embodiment, the compression device also includes a primary compression module and a secondary compression module connected to the primary compression module; the secondary compression module is connected to the tertiary compression module; the compression device compresses the carbon dioxide gas to be treated by staged compression, thereby solving the problem in the prior art that the temperature of the carbon dioxide gas is too high due to the entire compression, which has an adverse effect on the compressor.

[0027] In a preferred embodiment, the first-stage compression module includes a first-stage compressor 11 and a first-stage cooler 12 connected to the first-stage compressor 11. The temperature of the carbon dioxide gas output after compression by the first-stage compressor 11 is 100-140°C, and the temperature of the carbon dioxide gas output after cooling by the first-stage cooler 12 is 40-60°C, and the pressure is 3-6bar.

[0028] In a preferred embodiment, the secondary compression module includes a secondary compressor 13 and a secondary cooler 14 connected to the secondary compressor 13. The temperature of the carbon dioxide gas output after compression by the secondary compressor 13 is 100-140°C, and the temperature of the carbon dioxide gas output after cooling by the secondary cooler 14 is 40-60°C, and the pressure is 9-15bar.

[0029] In a preferred embodiment, the three-stage compression module includes a three-stage compressor 15 and a three-stage cooler 16 connected to the three-stage compressor 15. The temperature of the carbon dioxide gas output after compression by the three-stage compressor 15 is 100-140°C, and the temperature of the carbon dioxide gas output after cooling by the three-stage cooler 16 is 40-60°C, and the pressure is 20~26bar.

[0030] In a specific implementation, the primary cooler 12 is connected to the secondary compressor 13 ; the secondary cooler 14 is connected to the tertiary compressor 15 .

[0031] In a preferred embodiment, in conjunction with reference to Figure 2 The drying unit 4 includes a first drying tower 41 and a second drying tower 42; by arranging the first drying tower 41 and the second drying tower 42 in parallel, when one drying tower performs drying treatment, the other drying tower performs purging treatment, thereby realizing continuous operation of the drying unit 4 and improving the operation efficiency of the system.

[0032] In a specific embodiment, the top inlet of the first drying tower 41 and the top inlet of the second drying tower 42 are both connected to the tertiary cooler 16 ; the carbon dioxide gas entering the first drying tower 41 and the second drying tower 42 both comes from the tertiary cooler 16 .

[0033] In a specific embodiment, the bottom inlet of the first drying tower 41 and the bottom inlet of the second drying tower 42 are both connected to the heater 3; the carbon dioxide gas heated by the heater 3 can enter the first drying tower 41 from the bottom inlet of the first drying tower 41 to purge the first drying tower 41, or can enter the second drying tower 42 from the bottom inlet of the second drying tower 42 to purge the second drying tower 42.

[0034] In a specific embodiment, the top outlet of the first drying tower 41 and the top outlet of the second drying tower 42 are both connected to the heat exchanger 2; the purge gas output from the top outlet of the first drying tower 41 or the purge gas output from the top outlet of the second drying tower 42 enters the heat exchanger 2 for heat exchange.

[0035] In a specific embodiment, the bottom outlet of the first drying tower 41 and the bottom outlet of the second drying tower 42 are both connected to the refrigeration unit 7; the dry carbon dioxide gas output from the bottom outlet of the first drying tower 41 or the bottom outlet of the second drying tower 42 enters the refrigeration unit 7 for cooling to form dry liquid carbon dioxide.

[0036] In the carbon dioxide compression drying system of the present invention, the operation path of the logistics in the drying unit 4 can be adjusted according to the specific functions of the first drying tower 41 and the second drying tower 42 in the drying unit 4.

[0037] Combined with reference Figure 2The drying unit 4 further includes a first shut-off valve 400, a second shut-off valve 410, a third shut-off valve 420, a fourth shut-off valve 430, a fifth shut-off valve 440, a sixth shut-off valve 450, a seventh shut-off valve 460 and an eighth shut-off valve 470; specifically, the first shut-off valve 400 is arranged on a pipeline connecting the top inlet of the first drying tower 41 and the tertiary cooler 16; the second shut-off valve 410 is arranged on a pipeline connecting the top outlet of the first drying tower 41 and the heat exchanger 2; the third shut-off valve 420 is arranged on a pipeline connecting the bottom inlet of the first drying tower 41 and the heater 3 ; The fourth shut-off valve 430 is arranged on the pipeline connecting the bottom outlet of the first drying tower 41 and the refrigeration unit 7; the fifth shut-off valve 440 is arranged on the pipeline connecting the top inlet of the second drying tower 42 and the tertiary cooler 16; the sixth shut-off valve 450 is arranged on the pipeline connecting the top outlet of the second drying tower 42 and the heat exchanger 2; the seventh shut-off valve 460 is arranged on the pipeline connecting the bottom inlet of the second drying tower 42 and the heater 3; the eighth shut-off valve 470 is arranged on the pipeline connecting the bottom outlet of the second drying tower 42 and the refrigeration unit 7.

[0038] Specifically, when the first drying tower 41 is used for drying and the second drying tower 42 is used for purging, the second shut-off valve 410, the third shut-off valve 420, the fifth shut-off valve 440 and the eighth shut-off valve 470 are closed, and the wet carbon dioxide gas outputted from the tertiary cooler 16 enters the first drying tower 41 from the top inlet of the first drying tower 41 through the first shut-off valve 400, and is dried by the adsorbent in the first drying tower 41 to obtain dry carbon dioxide gas, and the dry carbon dioxide gas is outputted from the bottom outlet of the first drying tower 41 through the third shut-off valve 400. The fourth shut-off valve 430 enters the refrigeration unit 7 for cooling to form dry liquid carbon dioxide; the carbon dioxide gas output by the three-stage compressor 15 is heat-exchanged by the heat exchanger 2 and heated by the heater 3, and then enters the second drying tower 42 from the bottom inlet of the second drying tower 42 through the seventh shut-off valve 460 to purge the saturated adsorbent in the second drying tower 42 to obtain purge gas and realize the regeneration of the adsorbent. The purge gas is output from the top outlet of the second drying tower 42 and enters the heat exchanger 2 through the sixth shut-off valve 450 for heat exchange.

[0039] Specifically, when the first drying tower 41 is used for purging and the second drying tower 42 is used for drying, the first shut-off valve 400, the fourth shut-off valve 430, the sixth shut-off valve 450 and the seventh shut-off valve 460 are closed, and the wet carbon dioxide gas outputted from the third-stage cooler 16 enters the second drying tower 42 through the fifth shut-off valve 440 from the top inlet of the second drying tower 42 and is dried by the adsorbent in the second drying tower 42 to obtain dry carbon dioxide gas, and the dry carbon dioxide gas is outputted from the bottom outlet of the second drying tower 42 and is discharged through the first shut-off valve 440. The eight shut-off valves 470 enter the refrigeration unit 7 for cooling to form dry liquid carbon dioxide; the carbon dioxide gas output by the three-stage compressor 15 is heat-exchanged by the heat exchanger 2 and heated by the heater 3, and then enters the first drying tower 41 from the bottom inlet of the first drying tower 41 through the third shut-off valve 420 to purge the saturated adsorbent in the first drying tower 41 to obtain purge gas and regenerate the adsorbent. The purge gas is output from the top outlet of the first drying tower 41 and enters the heat exchanger 2 through the second shut-off valve 410 for heat exchange.

[0040] The present invention will be described in detail below through examples, but the protection scope of the present invention is not limited thereto.

[0041] The embodiments are all implemented in the carbon dioxide compression drying system described below, in conjunction with reference to Figure 1 and Figure 2 , the carbon dioxide compression drying system comprises: compression device, heat exchanger 2, heater 3, drying unit 4, cooler 5, gas-liquid separator 6 and refrigeration unit 7; The compression device comprises a primary compressor 11, a primary cooler 12, a secondary compressor 13, a secondary cooler 14, a tertiary compressor 15 and a tertiary cooler 16 which are connected in sequence; The three-stage compressor 15 is connected to the heat exchanger 2, the heat exchanger 2 is connected to the heater 3 and the cooler 5 respectively, and the cooler 5 is connected to the gas-liquid separator 6; The drying unit 4 includes a first drying tower 41 and a second drying tower 42; The top inlet of the first drying tower 41 and the top inlet of the second drying tower 42 are both connected to the tertiary cooler 16; a first shutoff valve 400 is provided on the pipeline connecting the top inlet of the first drying tower 41 and the tertiary cooler 16, and a fifth shutoff valve 440 is provided on the pipeline connecting the top inlet of the second drying tower 42 and the tertiary cooler 16; The top inlet of the first drying tower 41 and the top inlet of the second drying tower 42 are both connected to the gas-liquid separator 6; The bottom inlet of the first drying tower 41 and the bottom inlet of the second drying tower 42 are both connected to the heater 3; a third shutoff valve 420 is provided on the pipeline connecting the bottom inlet of the first drying tower 41 and the heater 3, and a seventh shutoff valve 460 is provided on the pipeline connecting the bottom inlet of the second drying tower 42 and the heater 3; The top outlet of the first drying tower 41 and the top outlet of the second drying tower 42 are both connected to the heat exchanger 2; a second shutoff valve 410 is provided on the pipeline connecting the top outlet of the first drying tower 41 and the heat exchanger 2, and a sixth shutoff valve 450 is provided on the pipeline connecting the top inlet of the second drying tower 42 and the heat exchanger 2; The bottom outlet of the first drying tower 41 and the bottom outlet of the second drying tower 42 are both connected to the refrigeration unit 7; a fourth shut-off valve 430 is provided on the pipeline connecting the bottom outlet of the first drying tower 41 and the refrigeration unit 7, and an eighth shut-off valve 470 is provided on the pipeline connecting the bottom outlet of the second drying tower 42 and the refrigeration unit 7.

[0042] Example 1 The carbon dioxide gas to be treated sequentially enters the primary compressor 11, the primary cooler 12, the secondary compressor 13, the secondary cooler 14, the tertiary compressor 15 and the tertiary cooler 16 for compression and cooling. When the first drying tower 41 is in the drying function and the second drying tower 42 is in the purging function, the second shut-off valve 410, the third shut-off valve 420, the fifth shut-off valve 440 and the eighth shut-off valve 470 are closed. The wet carbon dioxide gas (temperature of 25° C., pressure of 25 bar) outputted from the tertiary cooler 16 enters the first drying tower 41 from the top inlet of the first drying tower 41 through the first shut-off valve 400 and is dried by the adsorbent of the first drying tower 41. The dried carbon dioxide gas is outputted from the bottom outlet of the first drying tower 41 and enters the refrigeration unit 7 through the fourth shut-off valve 430 for cooling to form dry liquid carbon dioxide. The carbon dioxide gas (temperature of 130° C.) output by the three-stage compressor 15 and the purge gas (temperature of 240° C.) from the second drying tower 42 are heat exchanged in the heat exchanger 2; The carbon dioxide gas (temperature is 220° C.) after heat exchange enters the heater 3 and is heated to 240° C. The heated carbon dioxide gas enters the second drying tower 42 from the bottom inlet of the second drying tower 42 through the seventh shut-off valve 460 to purge the adsorbent saturated with adsorption in the second drying tower 42 to obtain purge gas and realize the regeneration of the adsorbent. The purge gas is output from the top outlet of the second drying tower 42 through the sixth shut-off valve 450 to form the purge gas; The purge gas (temperature of 100° C.) after heat exchange enters the cooler 5 for cooling, and the cooled purge gas (temperature of 40° C.) enters the gas-liquid separator 6 for gas-liquid separation to obtain gaseous carbon dioxide and liquid water. The gaseous carbon dioxide enters the first drying tower 41 from the top inlet of the first drying tower 41 through the first shut-off valve 400 and is dried by the adsorbent of the first drying tower 41. The dried carbon dioxide gas is output from the bottom outlet of the first drying tower 41 and enters the refrigeration unit 7 through the fourth shut-off valve 430 for cooling to form dry liquid carbon dioxide; the liquid water is output from the liquid phase outlet of the gas-liquid separator 6 for reuse; When the first drying tower 41 is in the purge function and the second drying tower 42 is in the drying function, the first shutoff valve 400, the fourth shutoff valve 430, the sixth shutoff valve 450 and the seventh shutoff valve 460 are first closed, and then the second shutoff valve 410, the third shutoff valve 420, the fifth shutoff valve 440 and the eighth shutoff valve 470 are opened; At this time, the carbon dioxide gas outputted from the tertiary cooler 16 enters the second drying tower 42 from the top inlet of the second drying tower 42 through the fifth shut-off valve 440 and is dried by the adsorbent of the second drying tower 42. The dried carbon dioxide gas is outputted from the bottom outlet of the second drying tower 42 and enters the refrigeration unit 7 through the eighth shut-off valve 470 to be cooled, thereby forming dry liquid carbon dioxide. The carbon dioxide gas (temperature of 130° C.) output by the three-stage compressor 15 and the purge gas (temperature of 240° C.) from the first drying unit 41 are heat exchanged in the heat exchanger 2; The carbon dioxide gas (temperature is 220° C.) after heat exchange enters the heater 3 and is heated to 240° C. The heated carbon dioxide gas enters the first drying tower 41 from the bottom inlet of the first drying tower 41 through the third shut-off valve 420 to purge the adsorbent saturated with adsorption in the first drying tower 41 to obtain purge gas and realize the regeneration of the adsorbent. The purge gas is output from the top outlet of the first drying tower 41 through the second shut-off valve 410 to form the purge gas; The purge gas (temperature is 100°C) after heat exchange enters the cooler 5 for cooling, and the cooled purge gas (temperature is 40°C) enters the gas-liquid separator 6 for gas-liquid separation to obtain gaseous carbon dioxide and liquid water. The gaseous carbon dioxide enters the second drying tower 42 from the top inlet of the second drying tower 42 through the fifth shut-off valve 440 and is dried by the adsorbent of the second drying tower 42. The dried carbon dioxide gas is output from the bottom outlet of the second drying tower 42 and enters the refrigeration unit 7 through the eighth shut-off valve 470 to be cooled to form dry liquid carbon dioxide; the liquid water is output from the liquid phase outlet of the gas-liquid separator 6 for reuse.

[0043] It can be seen from Example 1 that the carbon dioxide compression drying system described in the present invention can realize the utilization of the heat of the carbon dioxide gas output by the three-stage compressor 15 and the heat of the purge gas from the drying unit 4, thereby reducing the external heat source required for purging the drying unit 4 with the carbon dioxide gas output by the compression device, and at the same time, it can also reduce the external cold source required for cooling the purge gas output from the second output end of the drying unit 4, thereby reducing the energy consumption required for the system as a whole; at the same time, by controlling the states of the first shut-off valve 400, the second shut-off valve 410, the third shut-off valve 420, the fourth shut-off valve 430, the fifth shut-off valve 440, the sixth shut-off valve 450, the seventh shut-off valve 460 and the eighth shut-off valve 470 in the drying unit 4, the specific functions of the first drying tower 41 and the second drying tower 42 in the drying unit 4 are adjusted to realize the circulation operation of the first drying tower 41 and the second drying tower 42.

[0044] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A carbon dioxide compression drying system, characterized in that: The system comprises a compression device, a heat exchanger (2), a heater (3), a drying unit (4), a cooler (5) and a gas-liquid separator (6); The compression device comprises a three-stage compression module, wherein the three-stage compression module comprises a three-stage compressor (15) and a three-stage cooler (16) connected to the three-stage compressor (15); The tertiary cooler (16) is connected to the first input end of the drying unit (4); The wet carbon dioxide gas outputted by the tertiary cooler (16) enters the drying unit (4) through the first input end of the drying unit (4) to be dried and is outputted through the first output end of the drying unit (4); The three-stage compressor (15) is connected to the heat exchanger (2), the heat exchanger (2) is connected to the heater (3), and the heater (3) is connected to the second input end of the drying unit (4); The carbon dioxide gas output by the three-stage compressor (15) exchanges heat with the purge gas from the drying unit (4) in the heat exchanger (2); The purge gas after heat exchange enters the cooler (5) for cooling, and the cooled purge gas enters the gas-liquid separator (6) for gas-liquid separation to obtain gaseous carbon dioxide, and the gaseous carbon dioxide enters the drying unit (4) through the first input end of the drying unit (4) for drying; The carbon dioxide gas after heat exchange enters the heater (3) for heating, and the heated carbon dioxide gas enters the drying unit (4) through the second input end of the drying unit (4) to purge the drying unit (4) and is output through the second output end of the drying unit (4) to form the purge gas.

2. The carbon dioxide compression and drying system according to claim 1, characterized in that: The carbon dioxide compression drying system further comprises a refrigeration unit (7) connected to the first output end of the drying unit (4).

3. The carbon dioxide compression and drying system according to claim 1 or 2, characterized in that: The compression device also includes a primary compression module and a secondary compression module connected to the primary compression module; The secondary compression module is connected to the tertiary compression module.

4. The carbon dioxide compression and drying system according to claim 3, characterized in that: The primary compression module comprises a primary compressor (11) and a primary cooler (12) connected to the primary compressor (11).

5. The carbon dioxide compression and drying system according to claim 4, characterized in that: The secondary compression module comprises a secondary compressor (13) and a secondary cooler (14) connected to the secondary compressor (13).

6. The carbon dioxide compression and drying system according to claim 1 or 2, characterized in that: The drying unit (4) comprises a first drying tower (41) and a second drying tower (42).

7. The carbon dioxide compression and drying system according to claim 6, characterized in that: The top inlet of the first drying tower (41) and the top inlet of the second drying tower (42) are both connected to the tertiary cooler (16).

8. The carbon dioxide compression and drying system according to claim 6 or 7, characterized in that: The bottom inlet of the first drying tower (41) and the bottom inlet of the second drying tower (42) are both connected to the heater (3).

9. The carbon dioxide compression and drying system according to claim 8, characterized in that: The top outlet of the first drying tower (41) and the top outlet of the second drying tower (42) are both connected to the heat exchanger (2).

10. The carbon dioxide compression and drying system according to claim 9, characterized in that: The bottom outlet of the first drying tower (41) and the bottom outlet of the second drying tower (42) are both connected to the refrigeration unit (7).

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