An apparatus for air expansion refrigeration liquefaction of carbon dioxide

Abstract

The utility model belongs to carbon dioxide liquefaction device field discloses a kind of air expansion refrigeration liquefied carbon dioxide's device.The device includes including carbon dioxide passage and air passage, specifically including raw material gas buffer tank (1), compressor (2), adsorber (3), expander (4), rectifying column (5), reboiler (6), condenser (7), after-cooler (8), plate heat exchanger (9) and liquefier (10);The air passage and carbon dioxide passage complete heat exchange and air regeneration utilization by plate heat exchanger (5).This device greatly reduces energy loss, method simple and safe.

Description

Technical Field

[0001] This utility model belongs to the field of carbon dioxide liquefaction devices, specifically relating to a device for liquefying carbon dioxide by air expansion and refrigeration. Background Technology

[0002] With the increasing urgency of global carbon emission reduction, carbon dioxide (CO2) capture, liquefaction, and comprehensive utilization technologies have received widespread attention. Liquid CO2 has significant application value in food preservation, industrial welding, supercritical extraction, refrigeration, and carbon sequestration. However, traditional CO2 liquefaction processes generally suffer from high energy consumption and system complexity, severely restricting their economic viability and widespread application.

[0003] Currently, the main industrial liquefaction processes used are compression refrigeration cycles or external refrigerant refrigeration. These technologies have the following technical bottlenecks: First, multi-stage compression refrigeration systems consume huge amounts of energy, with the compressor accounting for more than 60% of the total energy consumption of the liquefaction system. Second, relying on external refrigerants such as ammonia and Freon not only increases the complexity of the system but also poses environmental risks. Third, existing processes have low efficiency in separating light components (such as N2 and O2) from the raw gas, often requiring additional purification equipment, which further increases equipment investment and operating costs.

[0004] In recent years, air expansion refrigeration technology has been applied in the low-temperature field due to its environmentally friendly and efficient characteristics. Chinese patent CN201510023456.7 discloses a CO2 liquefaction device using expansion refrigeration, but it fails to effectively solve the problem of cascaded utilization of cooling capacity, resulting in a low system energy efficiency ratio. US patent US20170254421A1 proposes a refrigeration system combining compression and expansion, but it still relies on external refrigerant for auxiliary refrigeration. These existing technologies generally suffer from insufficient cooling capacity utilization and low equipment integration, making it difficult to meet the modern industrial demand for efficient and compact CO2 liquefaction devices. Utility Model Content

[0005] To address the problems of high energy consumption, low cooling capacity utilization, and poor environmental adaptability in existing technologies, there is an urgent need to develop a carbon dioxide liquefaction device that is simple to operate, safe, energy-efficient, and highly adaptable to the environment. The purpose of this invention is to provide a device for liquefying carbon dioxide using air expansion refrigeration.

[0006] To achieve the above objectives, the specific technical solution of this invention is as follows:

[0007] This invention discloses a device for air expansion refrigeration and liquefaction of carbon dioxide, the device comprising a carbon dioxide passage and an air passage.

[0008] The carbon dioxide passage includes a feed gas buffer tank (1), a compressor (2), an adsorber (3), an expander (4), a staged cooling unit, and a distillation column (5) connected in sequence; the bottom of the distillation column (5) is connected to a reboiler (6) for heating the bottom liquid to purify carbon dioxide; the top of the distillation column (5) is connected to a condenser (7) for condensing the top gas and controlling reflux.

[0009] The staged cooling unit includes an aftercooler (8), a plate heat exchanger (9), and a liquefier (10) connected in sequence.

[0010] An expander (4), a condenser (7), a plate heat exchanger (9), a reboiler (6), and a non-condensable gas pipeline (11) are provided on the air passage (12);

[0011] The air passage and the carbon dioxide passage achieve heat exchange and cascade utilization of cooling capacity through a plate heat exchanger (9).

[0012] Specifically, the expansion end of the expander (4) is supplied with low-pressure air from outside the boundary, and the gauge pressure of the low-pressure air from outside the boundary is 0.115-0.477 MPa.

[0013] Specifically, the first flow channel of the plate heat exchanger (9) is connected to the aftercooler (8) and the liquefier (10) respectively, and is used to precool the high-pressure carbon dioxide to the liquefaction temperature;

[0014] The second flow channel of the plate heat exchanger (9) is connected to the condenser (7) and the reboiler (6) respectively, and the condenser (7) is used as a cold source to cool the heat source of the reboiler.

[0015] The third flow channel of the plate heat exchanger (9) is connected to the condenser (7) and the non-condensable gas pipeline (11) respectively, and the residual CO2 is recovered from the light component gas.

[0016] The fourth flow channel of the plate heat exchanger (9) is connected to the reboiler (6) and the air pipe (12) respectively, and the waste heat is discharged through the air cooling reboiler.

[0017] Specifically, the cold source of the condenser (7) is the temperature of the low-pressure air outside the boundary after it is expanded by the expander (4), and the heat source of the reboiler is the expanded air of the plate heat exchanger (9).

[0018] Specifically, the air temperature in the first flow channel is -44°C to 20°C, and / or the carbon dioxide temperature in the second flow channel is 40°C to -4°C, and / or the non-condensable gas temperature in the third flow channel is -50°C to 20°C, and / or the air temperature in the fourth flow channel is -2°C to 20°C.

[0019] Specifically, the expander (4) is selected from any one of the following: piston expander, turbine expander, or volumetric expander, preferably turbine expander.

[0020] Specifically, the condenser (7) is selected from any one of the following: a kettle condenser, a tubular condenser, or a spiral condenser, preferably a kettle condenser.

[0021] Specifically, the refrigerant of the liquefier (10) is chilled water, and the temperature of the chilled water is -15°C to -10°C.

[0022] Specifically, the adsorber (3) is filled with molecular sieves or activated alumina for selective adsorption of moisture and sulfides.

[0023] Specifically, the liquid carbon dioxide discharged from the bottom of the distillation column (5) has a purity of ≥99.9%, and the non-condensable gas discharged from the top of the column contains nitrogen and oxygen.

[0024] In this invention, carbon dioxide feed gas is connected to a feed gas buffer tank, the outlet pipe of which is connected to a compressor. After being compressed by the compressor, the feed gas is sent to an adsorber to remove impurities, and then to the booster end of an expander for further pressurization. The pressurized feed gas is cooled by an aftercooler and then sent to a plate heat exchanger. After exchanging heat with the residual stream of the plate heat exchanger, the feed gas is sent to a liquefier where carbon dioxide is liquefied through heat exchange with chilled water. The liquid carbon dioxide is then sent to a distillation column for further distillation. Low-pressure air from outside the system is connected to the expansion section of the expander, and the gas passes through... After expansion, the temperature decreases, serving as the cold source for the condenser at the top of the distillation column. The vapor phase at the top of the distillation column condenses and returns to the distillation column as reflux. The non-condensable gas in the condenser is connected to a plate heat exchanger to recover the cooling capacity before being sent out of the boundary area. The expanded air exiting the distillation column condenser is sent to a plate heat exchanger for further cooling capacity recovery. The expanded air from the plate heat exchanger enters the reboiler at the bottom of the column as the heat source for the reboiler, while simultaneously recovering the cooling capacity at the bottom of the column. The expanded air exiting the reboiler is connected to a plate heat exchanger for reheating before being vented or used as regeneration gas for the adsorber. The liquid carbon dioxide product produced at the bottom of the distillation column is sent out of the boundary area.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) This device adopts a combined air passage and carbon dioxide passage refrigeration cycle, uses an air expander to generate low-temperature cooling capacity, and works in synergy with CO2 to reduce compression power consumption.

[0027] (2) This device uses a plate heat exchanger to achieve pre-cooling, liquefaction, distillation cold energy recovery and non-condensable gas treatment functions, and realizes the distribution of cold energy on demand;

[0028] (3) This device simplifies the system structure and dynamically adjusts the temperature gradient inside the tower by using the cold and heat coupling between the reboiler and the condenser, without the need for an external heat source.

[0029] (4) This device is suitable for mobile or distributed CO2 liquefaction scenarios, and its energy consumption is reduced by more than 30% compared with traditional systems. Attached Figure Description

[0030] Figure 1 A device for liquefying carbon dioxide by expanding and cooling air. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments:

[0032] like Figure 1 As shown, 1-raw material gas buffer tank, 2-compressor, 3-adsorber, 4-expander, 5-distillation column, 6-reboiler, 7-condenser, 8-aftercooler, 9-plate heat exchanger, 10-liquefier, 11-non-condensable gas pipeline, 12-air passage.

[0033] This invention discloses an air expansion refrigeration liquefaction device for carbon dioxide, comprising a carbon dioxide passage and an air passage. The carbon dioxide passage includes a raw material gas buffer tank (1), a compressor (2), an adsorber (3), an expander (4), a staged cooling unit, and a distillation column (5) connected in sequence. The bottom of the distillation column (5) is connected to a reboiler (6) for heating the liquid at the bottom of the column to purify carbon dioxide. The top of the distillation column (5) is connected to a condenser (7) for condensing the gas at the top of the column and controlling the reflux. The staged cooling unit includes an aftercooler (8), a plate heat exchanger (9), and a liquefaction unit connected in sequence. The air passage (12) is equipped with an expander (4), a condenser (7), a plate heat exchanger (9), a reboiler (6), and a non-condensable gas pipeline (11).

[0034] The air passage and the carbon dioxide passage exchange heat and utilize cold energy through a plate heat exchanger (9).

[0035] Among them, the expansion end of the expander (4) is supplied with low-pressure air from outside the boundary, and the gauge pressure of the low-pressure air from outside the boundary is 0.115-0.477Mpa.

[0036] The first flow channel of the plate heat exchanger (9) is connected to the aftercooler (8) and the liquefier (10) respectively, and is used to precool the high-pressure carbon dioxide to the liquefaction temperature; the second flow channel of the plate heat exchanger (9) is connected to the condenser (7) and the reboiler (6) respectively, and uses the cold source of the condenser (7) to cool the heat source of the reboiler; the third flow channel of the plate heat exchanger (9) is connected to the condenser (7) and the non-condensable gas pipeline (11) respectively, and recovers residual CO2 from the light component gas; the fourth flow channel of the plate heat exchanger (9) is connected to the reboiler (6) and the air pipeline (12) respectively, and exhausts waste heat by cooling the reboiler with air. Among them, the air temperature in the first flow channel is -44℃ to 20℃, the carbon dioxide temperature in the second flow channel is 40℃ to -4℃, the non-condensable gas temperature in the third flow channel is -50℃ to 20℃, and the air temperature in the fourth flow channel is -2℃ to 20℃.

[0037] The condenser (7) has a cold source that is the temperature of the low-pressure air outside the boundary after it is expanded by the expander (4), and the reboiler has a heat source that is the expanded air of the plate heat exchanger (5).

[0038] The refrigerant of the liquefier (10) is chilled water, and the temperature of the chilled water is -15°C to -10°C.

[0039] The purity of the liquid carbon dioxide discharged from the bottom of the distillation column (5) is ≥99.9%, and the non-condensable gas discharged from the top of the column contains nitrogen and oxygen.

[0040] The above descriptions are merely embodiments of this utility model. Commonly known technical solutions or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solution of this utility model. These modifications and improvements should also be considered within the scope of protection of this utility model, and will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. An apparatus for air expansion refrigeration liquefaction of carbon dioxide, characterized by, The device includes a carbon dioxide passage and an air passage. The carbon dioxide passage includes a feed gas buffer tank (1), a compressor (2), an adsorber (3), an expander (4), a staged cooling unit, and a distillation column (5) connected in sequence; the bottom of the distillation column (5) is connected to a reboiler (6) for heating the liquid at the bottom of the column to purify carbon dioxide; the top of the distillation column (5) is connected to a condenser (7) for condensing the gas at the top of the column and controlling the reflux. The staged cooling unit includes an aftercooler (8), a plate heat exchanger (9), and a liquefier (10) connected in sequence. An expander (4), a condenser (7), a plate heat exchanger (9), a reboiler (6), and a non-condensable gas pipe (11) are provided on the air passage (12). The air passage and the carbon dioxide passage achieve heat exchange and cascade utilization of cooling capacity through a plate heat exchanger (9).

2. The apparatus according to claim 1, characterized in that, The expansion end of the expander (4) is supplied with low-pressure air from outside the boundary, and the gauge pressure of the low-pressure air from outside the boundary is 0.115-0.477 MPa.

3. The apparatus according to claim 1, characterized in that, The first flow channel of the plate heat exchanger (9) is connected to the aftercooler (8) and the liquefier (10) respectively, and is used to precool the high-pressure carbon dioxide to the liquefaction temperature. The second flow channel of the plate heat exchanger (9) is connected to the condenser (7) and the reboiler (6) respectively, and the condenser (7) is used as a cold source to cool the heat source of the reboiler. The third flow channel of the plate heat exchanger (9) is connected to the condenser (7) and the non-condensable gas pipeline (11) respectively, and the residual CO2 is recovered from the light component gas. The fourth flow channel of the plate heat exchanger (9) is connected to the reboiler (6) and the air passage (12) respectively, and the waste heat is discharged through the air cooling reboiler.

4. The apparatus according to claim 3, characterized in that, The condenser (7) has a cold source that is the temperature of the low-pressure air outside the boundary after it is expanded by the expander (4), and the reboiler has a heat source that is the expanded air of the plate heat exchanger (9).

5. The apparatus according to claim 3, characterized in that, The air temperature in the first flow channel ranges from -44°C to 20°C. And / or, the carbon dioxide temperature in the second flow channel is from 40°C to -4°C. And / or, the temperature of the non-condensable gas in the third flow channel is -50°C to 20°C. And / or, the air temperature in the fourth flow channel is -2°C to 20°C.

6. The apparatus according to claim 1, characterized in that, The expander (4) is selected from any one of the following: piston expander, turbine expander, or volumetric expander.

7. The apparatus according to claim 6, characterized in that, The expander (4) is a turbine expander.

8. The apparatus according to claim 1, characterized in that, The condenser (7) is selected from any one of the following: a kettle condenser, a tubular condenser, or a spiral condenser.

9. The apparatus according to claim 8, characterized in that, The condenser (7) is a kettle condenser.

10. The apparatus according to claim 1, characterized in that, The refrigerant in the liquefier (10) is chilled water, and the temperature of the chilled water is -15°C to -10°C.

11. The apparatus according to claim 1, characterized in that, The adsorber (3) is filled with molecular sieves or activated alumina for selective adsorption of moisture and sulfides.

12. The apparatus according to claim 1, characterized in that, The purity of the liquid carbon dioxide discharged from the bottom of the distillation column (5) is ≥99.9%, and the non-condensable gas discharged from the top of the column contains nitrogen and oxygen.

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