Carbon dioxide rectification and purification device

Abstract

The utility model provides a carbon dioxide rectification and purification device and relates to the technical field of carbon dioxide purification. A carbon dioxide rectification purification device comprises a precooling mechanism and a rectification mechanism, the rectification mechanism comprises a first rectification tower, a reflux condensation tank, a first reflux tank, a second rectification tower, a second reflux tank and a subcooler, the lower portion of the first rectification tower is connected with the precooling mechanism, and the upper portion of the first rectification tower is connected with the first reflux tank; the upper part of the second rectifying tower is respectively connected with a first reflux tank and a second reflux tank; the top ends of the first rectifying tower and the second rectifying tower are connected with reflux condensation tanks, and the bottom ends of the first rectifying tower and the second rectifying tower are connected with subcoolers; the reflux condensation tank is respectively connected with the first reflux tank and the second reflux tank, and reboilers are arranged at the bottoms of the first rectifying tower and the second rectifying tower. The purification precision and the resource utilization rate of carbon dioxide can be improved, and environmental protection is facilitated.

Description

TECHNICAL FIELD

[0001] The utility model relates to carbon dioxide purification technical field, specifically, relate to a carbon dioxide rectification purification device. BACKGROUND

[0002] Natural gas, coke and heavy oil and other fuels and their combustion, ammonia synthesis, hydrogen production, petroleum chemical industry production process needs to discharge a large amount of carbon dioxide. The large amount of carbon dioxide emission, cause the influence to the environment, lead to the formation of greenhouse effect, lead to global temperature rise. And CO2 has extremely extensive application in industry, agriculture, food, medicine, fine chemical industry etc. domain, from the byproduct gas source of various industrial processes recovers CO2, can utilize carbon resources comprehensively, also can manage the environmental pollution caused by industrial waste gas emission.

[0003] At present, the raw material gas of hydrogen production decarburization device contains CO2, and also contains CO, H2, CH4, N2, H2O, methanol, organic sulfur, C4 above hydrocarbon and other impurities. Generally, there are two methods to separate these impurities, one is through physical or chemical adsorption, and then through oxidation combustion, so that organic hydrocarbons are converted into H2O and CO2, wherein, the adsorbent is used for several times and is filled as a dangerous solid waste, and the catalyst for oxidation and decarburization is also filled after refining after long time use. The second is through rectification process, using the difference of relative volatility, the components are discharged from the heavy tower bottom, and are collected and treated.

[0004] However, in the existing carbon dioxide rectification separation process, the purification precision is not high when purifying carbon dioxide, which cannot meet the existing demand, and when purifying carbon dioxide, there is a problem of low resource utilization rate. Utility model content

[0005] The utility model aims at providing a carbon dioxide rectification purification device, which can improve the purification precision and resource utilization rate of carbon dioxide, and is beneficial to environmental protection.

[0006] The utility model realizes the following technical scheme:

[0007] A carbon dioxide distillation purification apparatus includes a precooling mechanism and a distillation mechanism. The distillation mechanism includes a first distillation column, a reflux condenser, a first reflux tank, a second distillation column, a second reflux tank, and a subcooler. The lower part of the first distillation column is connected to the precooling mechanism, the upper part of the first distillation column is connected to the first reflux tank, and the upper part of the second distillation column is connected to both the first reflux tank and the second reflux tank. The top of both the first and second distillation columns is connected to the reflux condenser, and the bottom of both the first and second distillation columns is connected to the subcooler. The reflux condenser is connected to both the first reflux tank and the second reflux tank, and a reboiler is provided at the bottom of both the first and second distillation columns.

[0008] Furthermore, the precooling mechanism includes a primary precooler, a buffer tank, a compressor, a secondary precooler, an adsorption tower, and a tertiary precooler connected in sequence, wherein the tertiary precooler is connected to the first distillation tower.

[0009] Furthermore, the adsorption tower is equipped with an adsorbent.

[0010] Furthermore, the carbon dioxide distillation purification apparatus also includes a refrigerant separator, which is connected to the reboiler and is used to provide a heat source to the reboiler.

[0011] Furthermore, both the first reflux tank and the second reflux tank are equipped with pressure regulating valves and flow regulating valves, and both the first distillation column and the second distillation column are equipped with liquid level control regulating valves.

[0012] Furthermore, a pressure transmitter is installed at the top and bottom of each of the first and second distillation columns.

[0013] Furthermore, the subcooler is also connected to a storage tank.

[0014] The technical solution of this utility model has at least the following advantages and beneficial effects:

[0015] In this invention, the feed gas, pre-cooled by the pre-cooling mechanism, enters from the bottom of the first distillation column. The liquid phase, refluxed through the reflux condenser and the first reflux tank, enters from the top of the first distillation column. The gas and liquid phases flow alternately in the packing, causing the light components (CO, H2, etc.) in the liquid phase to transfer to the gas phase, while the heavy components (H2O, methanol, organic sulfur, C4 and above hydrocarbons, etc.) in the gas phase are transferred to the liquid phase and concentrated to the bottom of the column. The carbon dioxide, heated by the reboiler, flows out from the bottom of the column and enters the subcooler, while the gas phase flows out from the top of the column and enters the reflux condenser, thus achieving the preliminary distillation of carbon dioxide gas.

[0016] The vapor phase from the first distillation column, liquefied in the reflux condenser, enters the second distillation column from the top through the first reflux condenser. The vapor phase from the second distillation column, liquefied in the reflux condenser, enters from the top through the second reflux condenser. These two liquid streams, along with the rising gas heated by the reboiler at the bottom of the second distillation column, flow alternately through the packing. This causes the lighter components (H2, N2, etc.) in the liquid phase to transfer to the vapor phase, while the heavier components (CO2) in the vapor phase transfer to the liquid phase. The liquid phase, after passing through the packing, enters the bottom of the column. The product, 6N-grade CO2, obtained after heating in the reboiler, flows out from the bottom and enters the subcooler. The vapor phase flows out from the top of the second distillation column and enters the reflux condenser, achieving secondary distillation of carbon dioxide gas.

[0017] The gases exiting from the tops of both the first and second distillation columns enter the reflux condenser for liquefaction. The liquefied gas from the first distillation column then enters the first reflux tank, and the liquefied gas from the second distillation column enters the second reflux tank. During the distillation process, the gases re-enter both the first and second distillation columns. Repeated distillation improves the utilization rate and purification accuracy of carbon dioxide. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the carbon dioxide distillation and purification apparatus provided in Embodiment 1 of this utility model.

[0020] Icons: 1-First stage precooler, 2-Buffer tank, 3-Compressor, 4-Second stage precooler, 5-Adsorption tower, 6-Third stage precooler, 7-First distillation column, 8-Reboiler, 9-Second distillation column, 10-Reflux condenser, 11-First reflux tank, 12-Second reflux tank, 13-Subcooler, 14-Refrigerant separator, 15-Storage tank, 16-Pressure regulating valve, 17-Flow regulating valve, 18-Level control regulating valve, 19-Pressure transmitter. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this utility model, it should be noted that if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" appear to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0025] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0026] Example 1

[0027] like Figure 1As shown, this embodiment provides a carbon dioxide distillation purification apparatus, including a precooling mechanism and a distillation mechanism. The distillation mechanism includes a first distillation column 7, a reflux condenser 10, a first reflux tank 11, a second distillation column 9, a second reflux tank 12, and a subcooler 13. The lower part of the first distillation column 7 is connected to the precooling mechanism, and the upper part of the first distillation column 7 is connected to the first reflux tank 11. The upper part of the second distillation column 9 is connected to the first reflux tank 11 and the second reflux tank 12, respectively. The top of both the first distillation column 7 and the second distillation column 9 is connected to the reflux condenser 10, and the bottom of both the first distillation column 7 and the second distillation column 9 is connected to the subcooler 13. The reflux condenser 10 is connected to the first reflux tank 11 and the second reflux tank 12, respectively. A reboiler 8 is provided at the bottom of both the first distillation column 7 and the second distillation column 9.

[0028] The feed stream of the first distillation column 7 consists of two streams: a pre-cooled raw gas and a liquid phase refluxed through the reflux condenser 10 and the first reflux tank 11. The gas phase enters from the bottom of the first distillation column 7, while the liquid phase enters from the top. The gas and liquid phases flow alternately within the packing, causing lighter components (CO, H2, etc.) in the liquid phase to transfer to the gas phase, while heavier components (H2O, methanol, organic sulfur, C4+ hydrocarbons, etc.) in the gas phase are transferred to the liquid phase, concentrating to the bottom of the column. The carbon dioxide, heated by the reboiler 8, flows out from the bottom of the column into the subcooler 13, while the gas phase flows out from the top of the column into the reflux condenser 10, thus achieving preliminary distillation of the carbon dioxide gas.

[0029] The feed stream of the second distillation column 9 consists of two streams: the vapor phase from the first distillation column 7, liquefied by the reflux condenser 10, and the vapor phase from the second distillation column 9, liquefied by the reflux condenser 10. The liquefied vapor phase from the first distillation column 7 enters the second distillation column 9 from the top via the first reflux condenser 11, and the liquefied vapor phase from the second distillation column 9 enters from the top via the second reflux condenser 12. These two liquid streams, along with the rising gas heated by the reboiler 8 at the bottom of the second distillation column 9, flow alternately within the packing material. This causes the lighter components (H2, N2, etc.) in the liquid phase to transfer to the vapor phase, while the heavier components (CO2) in the vapor phase transfer to the liquid phase. The liquid phase, after passing through the packing material, enters the bottom of the column. The product 6N-grade CO2, obtained after heating by the reboiler 8, flows out from the bottom of the column and enters the subcooler 13. The vapor phase flows out from the top of the second distillation column 9 and enters the reflux condenser 10, achieving secondary distillation of carbon dioxide gas.

[0030] The gases flowing out from the top of the first distillation column 7 and the second distillation column 9 both enter the reflux condenser 10 for liquefaction. The liquefied gas from the first distillation column 7 then enters the first reflux tank 11, and the liquefied gas from the second distillation column 9 enters the second reflux tank 12. During the distillation process, the gases re-enter the first distillation column 7 and the second distillation column 9. Repeated distillation improves the utilization rate and purification accuracy of carbon dioxide.

[0031] In this embodiment, the precooling mechanism includes a primary precooler 1, a buffer tank 2, a compressor 3, a secondary precooler 4, an adsorption tower 5, and a tertiary precooler 6 connected in sequence. The tertiary precooler 6 is connected to the first distillation tower 7. The feed gas has a pressure of 0.02 MPa and a temperature of 25 degrees Celsius. After being precooled to 3°C by the primary precooler 1, it passes through the buffer tank 2 for buffering and water separation before entering the compressor 3. The compressor 3, using an oil-free reciprocating compressor, pressurizes the gas to 2.45 MPa (30°C). It then passes through the secondary precooler 4 again for precooling to 3°C and water separation before entering the adsorption tower 5. The adsorbent is used to initially remove heavy components such as methanol from the feed gas, while simultaneously drying the feed gas to a moisture content below 3 ppm. After passing through the tertiary precooler 6, the gas enters the first distillation tower 7 for distillation and purification of the gaseous feed gas.

[0032] In this embodiment, an adsorbent is provided inside the adsorption tower 5. The adsorbent removes heavy components such as methanol from the raw material gas, thereby reducing the impurity content of the gaseous raw material entering the first distillation tower 7.

[0033] In this embodiment, the carbon dioxide distillation purification apparatus further includes a refrigerant separator 14, which is connected to the reboiler 8 and provides a heat source for the reboiler 8. The refrigerant separated from the refrigerant separator 14 goes to the first distillation column 7 and the second distillation column 9, respectively, to provide a heat source for the reboiler 8 within the columns. The refrigerant after passing through the reboiler 8 is divided into two streams: one stream is throttled and enters the subcooler 13 to provide cooling, and the other stream is throttled and enters the reflux condenser 10 to provide cooling.

[0034] In this embodiment, both the first reflux tank 11 and the second reflux tank 12 are equipped with a pressure regulating valve 16 and a flow regulating valve 17, and both the first distillation column 7 and the second distillation column 9 are equipped with a liquid level control regulating valve 18. The pressure regulating valve 16 allows the first reflux tank 11 and the second reflux tank 12 to vent, discharging the non-condensable gas (main components CO2: 72.19%, CO: 0.945%, H2: 23.85%, CH4: 0.088%) entering the first reflux tank 11 from the first distillation column 7, and discharging the non-condensable gas (main components CO2: 86.07%, CO: 1.16%, H2: 8.31%, CH4: 0.251%, N2: 3.120%) entering the second reflux tank 12 from the second distillation column 9. In this system, the non-condensable gas discharged from the first reflux tank 11 is combined with the vent gas from the first distillation column 7 and sent to the third-stage precooler 6 to recover cooling capacity. Similarly, the non-condensable gas discharged from the second reflux tank 12 is combined with the vent gas from the second distillation column 9 and sent to the third-stage precooler 6 to recover cooling capacity, thus achieving resource utilization of the non-condensable gas and vent gas. A portion of the liquid from the first reflux tank 11 is regulated by the flow control valve 17 and enters the second distillation column 9 as feed, while the remaining liquid is controlled by the liquid level and enters the first distillation column 7 as reflux. The liquid from the second reflux tank 12 is controlled by the liquid level and enters the second distillation column 9 as reflux. High-purity carbon dioxide with a purity ≥99.999% is obtained from the bottom of the second distillation column 9.

[0035] In this embodiment, a pressure transmitter 19 is installed at the top and bottom of the first distillation column 7 and the second distillation column 9. Using two pressure transmitters 19 can prevent a large static pressure difference from occurring after the capillary is filled with liquid, thus avoiding the differential pressure transmitter being unable to shift to zero and affecting its normal operation.

[0036] In this embodiment, the subcooler 13 is also connected to a storage tank 14. The carbon dioxide cooled by the subcooler 13 is stored in the storage tank 14 for easy transportation.

[0037] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A carbon dioxide distillation and purification apparatus, characterized in that: The system includes a precooling mechanism and a distillation mechanism. The distillation mechanism includes a first distillation column, a reflux condenser, a first reflux tank, a second distillation column, a second reflux tank, and a subcooler. The lower part of the first distillation column is connected to the precooling mechanism, the upper part of the first distillation column is connected to the first reflux tank, and the upper part of the second distillation column is connected to both the first reflux tank and the second reflux tank. The top of both the first and second distillation columns is connected to the reflux condenser, and the bottom of both the first and second distillation columns is connected to the subcooler. The reflux condenser is connected to both the first reflux tank and the second reflux tank, and a reboiler is provided at the bottom of both the first and second distillation columns.

2. The carbon dioxide distillation and purification apparatus according to claim 1, characterized in that, The precooling mechanism includes a primary precooler, a buffer tank, a compressor, a secondary precooler, an adsorption tower, and a tertiary precooler connected in sequence, with the tertiary precooler connected to the first distillation tower.

3. The carbon dioxide distillation and purification apparatus according to claim 2, characterized in that, The adsorption tower is equipped with an adsorbent.

4. The carbon dioxide distillation and purification apparatus according to claim 1, characterized in that, The carbon dioxide distillation and purification apparatus also includes a refrigerant separator, which is connected to the reboiler and is used to provide a heat source to the reboiler.

5. The carbon dioxide distillation and purification apparatus according to claim 1, characterized in that, Both the first reflux tank and the second reflux tank are equipped with pressure regulating valves and flow regulating valves, and both the first distillation column and the second distillation column are equipped with liquid level control regulating valves.

6. The carbon dioxide distillation and purification apparatus according to claim 1, characterized in that, Each of the first and second distillation columns has a pressure transmitter installed at its top and bottom.

7. The carbon dioxide distillation and purification apparatus according to claim 1, characterized in that, The subcooler is also connected to a storage tank.

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