An energy-saving carbon extraction and dry ice making system

Abstract

The present invention discloses an energy-saving carbon extraction and dry ice making system, which relates to the technical field of carbon capture, utilization and storage. In the dry ice making system, the refrigerant channels of the primary, secondary and tertiary main heat exchangers are connected in series in sequence through a liquid cooling pipeline, and the external cold source passes through the refrigerant channels of the primary, secondary and tertiary main heat exchangers in sequence; the feed pipeline is used to receive raw materials including CO2 gas; the feed pipeline includes a front pipeline, a middle pipeline and a tail pipeline in sequence along the flow direction of the raw material, and the dry ice machine is connected to the first discharge port of the tail pipeline. The raw material in the front pipeline exchanges heat with the external cold source through the three-stage main heat exchanger, and the raw material in the tail pipeline exchanges heat with the external cold source through the primary main heat exchanger. The dehydration device is connected in series to the front pipeline to reduce the moisture in the raw material. This system can realize the gradient utilization of cold energy by the feed system, and can dehydrate the front pipeline part close to the feed port of the feed pipeline, which has a good energy-saving effect.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon capture, utilization and storage, and in particular to an energy-saving carbon extraction and dry ice making system. Background Art

[0002] In the existing dry ice preparation process, including the liquefaction process of gas raw materials, the refrigeration equipment used is usually more complicated. It may be necessary to provide different cold sources for cooling different positions, and the energy consumption is relatively large. For example, when there is a lot of water in the raw materials, there is a regeneration energy consumption due to the freezing problem of water under cooling, and when water is liquefied at low temperature, it will form hydrates with carbon dioxide, which appear as white ice crystal-like solids, causing blockage hazards to equipment and pipelines.

[0003] Therefore, how to provide a dry ice preparation system with better energy-saving effect is a technical problem that technical personnel in this field currently need to solve. Summary of the invention

[0004] In view of this, an object of the present invention is to provide an energy-saving carbon extraction and dry ice making system with better energy-saving effect.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An energy-saving carbon extraction and dry ice making system, comprising: a liquid cooling system, comprising a primary main heat exchanger, a secondary main heat exchanger and a tertiary main heat exchanger, wherein the refrigerant channels of the primary main heat exchanger, the secondary main heat exchanger and the tertiary main heat exchanger are sequentially connected in series through a liquid cooling pipeline, wherein the liquid cooling system is used to receive an external cold source, and the external cold source can sequentially pass through the refrigerant channels of the primary main heat exchanger, the secondary main heat exchanger and the tertiary main heat exchanger; a feeding system, comprising a feeding pipeline, a water removal device and a dry ice machine, wherein the feeding pipeline is used to receive a CO 2 The feed pipeline includes a front pipeline, a middle pipeline and a tail pipeline in sequence along the flow direction of the raw materials, and the dry ice machine is connected to the first discharge port of the tail pipeline, wherein the raw materials in the front pipeline can exchange heat with the external cold source through the three-stage main heat exchanger, and the raw materials in the tail pipeline can exchange heat with the external cold source through the first-stage main heat exchanger, and the dehydration device is connected in series to the front pipeline to reduce the moisture in the raw materials.

[0007] Preferably, the liquid cooling pipeline between the secondary main heat exchanger and the tertiary main heat exchanger is further connected in series with a rewarming vaporizer.

[0008] Preferably, the dehydration device comprises a water separator and a moisture adsorber which are sequentially connected in series to the front pipeline along the flow direction of the raw material; wherein, after the moisture adsorber adsorbs the moisture of the raw material, the normal pressure dew point of the raw material can be made not higher than the set temperature.

[0009] Preferably, the feeding system also includes a three-stage loop heat exchanger; the refrigerant channel of the three-stage loop heat exchanger is connected in series with the heat medium channel of the three-stage main heat exchanger to form a cooling circuit, and the cooling circuit has a three-stage refrigerant; the front pipeline is connected to the heat medium channel of the three-stage loop heat exchanger on the feed side of the water separator; the front pipeline is also connected in series with a raw material compressor, and the discharge side of the raw material compressor is connected to the feed port of the heat medium channel of the three-stage loop heat exchanger.

[0010] Preferably, the feeding system also includes a three-stage cooling circuit and multiple three-stage circuit heat exchangers, and the three-stage cooling circuit has a three-stage refrigerant; the heat medium channel of the three-stage main heat exchanger and the refrigerant channel of the three-stage circuit heat exchanger are connected in series in the three-stage cooling circuit, and the refrigerant channels of each three-stage circuit heat exchanger are connected in parallel; wherein, some of the three-stage circuit heat exchangers are front coolers, and the rest of the three-stage circuit heat exchangers are middle coolers; the heat medium channel of the front cooler is connected in series in the front pipeline, and the heat medium channel of the middle cooler is connected in series in the middle pipeline; the middle pipeline is also connected in series with a supercharger, and the discharge port of the supercharger is connected to the feed port of the heat medium channel of the middle cooler.

[0011] Preferably, the secondary main heat exchanger includes a first secondary main heat exchanger and a second secondary main heat exchanger, and the refrigerant channel of the first secondary main heat exchanger and the refrigerant channel of the second secondary main heat exchanger are connected in parallel; the middle pipeline includes a first branch, a second branch and a third branch arranged in sequence along the flow direction of the raw materials; the heat medium channel of the first secondary main heat exchanger is connected in series in the first branch; the heat medium channels of the booster and the middle cooler are connected in series in the second branch; the heat medium channel of the second secondary main heat exchanger is connected in series in the third branch.

[0012] Preferably, the feeding system also includes a separation tower and a primary cooling circuit; the separation tower has a top condenser; the primary cooling circuit has a primary refrigerant, and the heat medium channel of the primary main heat exchanger and the refrigerant channel of the top condenser are connected in series to the primary cooling circuit; the separation tower has a bottom reboiler; the tail pipeline is connected in series with the heat medium channel of the bottom reboiler and the feed port of the separation tower in sequence, so that the raw material enters the feed port of the separation tower after serving as the heat source of the bottom reboiler.

[0013] Preferably, the separation tower includes a weight removal tower and a light removal tower, and the tail pipeline is connected in series in sequence to the feed port of the weight removal tower, the top discharge port of the weight removal tower, the feed port of the light removal tower, and the bottom discharge port of the light removal tower; the bottom discharge port of the weight removal tower is connected to a residual liquid gasifier; and the top discharge port of the light removal tower is connected to a tail gas gasifier.

[0014] Preferably, the feeding system also includes a subcooler and a reflux pipeline; the tail pipeline is connected in series with the heat medium channel of the subcooler and the feed port of the dry ice machine in sequence; the feed port of the reflux pipeline is connected to the return port of the dry ice machine; the refrigerant channel of the subcooler is connected in series with the reflux pipeline, and the outlet of the reflux pipeline is connected to the middle pipeline.

[0015] Preferably, the tail pipeline also has a second outlet, and the second outlet is used to provide liquid CO 2 .

[0016] The energy-saving carbon extraction and dry ice making system provided by the present invention comprises: a liquid cooling system, comprising a primary main heat exchanger, a secondary main heat exchanger and a tertiary main heat exchanger, the refrigerant channels of the primary main heat exchanger, the secondary main heat exchanger and the tertiary main heat exchanger are sequentially connected in series through a liquid cooling pipeline, the liquid cooling system is used to receive an external cold source, and the external cold source can sequentially pass through the refrigerant channels of the primary main heat exchanger, the secondary main heat exchanger and the tertiary main heat exchanger; a feeding system, comprising a feeding pipeline, a water removal device and a dry ice machine, the feeding pipeline is used to receive a CO 2 The raw material of the gas is a gas; the feed pipeline includes a front pipeline, a middle pipeline and a tail pipeline in sequence along the flow direction of the raw material, and the dry ice machine is connected to the first discharge port of the tail pipeline, wherein the raw material in the front pipeline can exchange heat with the external cold source through the three-stage main heat exchanger, and the raw material in the tail pipeline can exchange heat with the external cold source through the first-stage main heat exchanger, and the dehydration device is connected in series with the front pipeline to reduce the moisture in the raw material.

[0017] By using the above-mentioned energy-saving carbon extraction and dry ice making system, only the cold energy provided by the external cold source in one liquid cooling pipeline is needed to meet the cooling requirements of the raw materials at different stages. At this time, the external cold source that can be used for cold energy passes through the first-stage main heat exchanger, the second-stage main heat exchanger, and the third-stage main heat exchanger in the entire dry ice preparation process. The cold energy is divided into three temperature ranges and is used for the cooling of different equipment in the system, respectively. The first-stage, second-stage, and third-stage utilization of cold energy is performed, so that the cold energy can be fully utilized in the entire temperature level, and the gradient utilization of cold energy by the feeding system is realized. It can better match the cooling amount required by the feeding system at each stage in the dry ice preparation process, and the dehydration device removes water in the front pipeline part close to the feed port of the feeding pipeline to minimize the moisture in the raw materials, reduce the influence of moisture in dry ice preparation, and reduce the regeneration energy consumption, so that this energy-saving carbon extraction and dry ice making system has a better energy-saving effect, and the system has a clear framework with gradient setting, which optimizes the process organization of the system and reduces the difficulty of assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0019] Figure 1 A schematic diagram of a specific embodiment 1 of the system provided by the present invention;

[0020] Figure 2 for Figure 1 Schematic diagram of the three-stage utilization of cold energy from medium- and high-temperature external cold sources;

[0021] Figure 3 for Figure 1 Schematic diagram of the secondary utilization part of the cold energy of the external cold source at medium and medium temperature;

[0022] Figure 4 for Figure 1 Schematic diagram of the primary utilization part of the cold energy of a medium to low temperature external cold source.

[0023] Reference numerals:

[0024] The first cooler E1, the second cooler E2, the third cooler E3, the fourth cooler E4, the first and second main heat exchangers E5, the second and second main heat exchangers E6, the subcooler E9, the first main heat exchanger E10, the third main heat exchanger E12, the second main heat exchanger E13, the third loop heat exchanger E14;

[0025] Residue gasifier E7, tail gas gasifier E8, re-warming gasifier E11;

[0026] Raw material compressor K1, first-stage booster K2, second-stage booster K3;

[0027] Separation tower C, heavy removal tower C1, light removal tower C2;

[0028] The third-stage refrigerant tank is T1, and the first-stage refrigerant tank is T2;

[0029] Water separator S, first water separator S1, second water separator S2;

[0030] The third-stage coolant pump P1, the first-stage coolant pump P2;

[0031] Exhaust gas pressure relief valve V1, tail gas pressure relief valve V2, dry ice making valve V3;

[0032] Moisture adsorber A1;

[0033] Dry ice machine M;

[0034] Liquid cooling pipeline 1;

[0035] Feed pipeline 2, front pipeline 21, middle pipeline 22, first branch 221, second branch 222, third branch 223, tail pipeline 23, first discharge port 231, second discharge port 232;

[0036] Return line 3;

[0037] Primary cooling circuit 4;

[0038] Tertiary cooling circuit 5. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The core of the present invention is to provide an energy-saving carbon extraction and dry ice making system with good energy-saving effect.

[0041] For a specific example 1 of the energy-saving carbon extraction and dry ice making system provided by the present invention, please refer to Figures 1 to 4 , including liquid cooling system and feeding system.

[0042] The liquid cooling system includes a primary main heat exchanger E10, a secondary main heat exchanger E13, and a tertiary main heat exchanger E12. The refrigerant channel of the primary main heat exchanger E10, the refrigerant channel of the secondary main heat exchanger E13, and the refrigerant channel of the tertiary main heat exchanger E12 are sequentially connected in series through a liquid cooling pipeline 1. The liquid cooling system is used to receive an external cold source, and the primary main heat exchanger E10 is located on the inlet side. Figure 1 In the figure, the solid arrow indicates the flow direction of the external cold source. At this time, the external cold source (usually a low-temperature liquid when entering) flows through the refrigerant channels of the primary main heat exchanger E10, the secondary main heat exchanger E13 and the tertiary main heat exchanger E12 in sequence. According to the temperature change of the external cold source, the primary main heat exchanger E10, the secondary main heat exchanger E13 and the tertiary main heat exchanger E12 are low-temperature heat exchangers, medium-temperature heat exchangers and high-temperature heat exchangers in sequence.

[0043] When the external cold source enters the liquid cooling pipeline 1, it is usually a cryogenic liquid, for example, liquefied natural gas, liquid oxygen, liquid nitrogen, liquid argon, ethylene, ethane, propane and other cryogenic liquids.

[0044] It should be noted that, in the present application, in each heat exchanger, the medium in the refrigerant channel exchanges heat with the medium in the heat medium channel to cool the medium in the heat medium channel.

[0045] The feeding system includes a feeding pipeline 2, a water removal device and a dry ice machine M.

[0046] Feed line 2 is used to receive CO 2 The feed pipeline 2 includes a front pipeline 21 (reference Figure 1 and 2 The pipeline between point a and point b in the middle of the pipeline 22 (reference Figure 1 and 3 The pipeline between point b and point d in the figure) and the tail pipeline 23 (reference Figure 1 and 3 The pipeline between point d and point f in the figure). Among them, Figure 1 In the figure, the solid small arrow indicates the flow direction of the raw material. During the flow of the raw material in the feed pipeline 2, the physical state and composition may change adaptively under the action of the equipment in the path. In addition, the raw materials selected in this embodiment are considered to contain no large content of sulfur-containing substances, or the large content of sulfur-containing substances has been removed before the raw materials enter the system.

[0047] The dry ice machine M is connected to the discharge port of the tail pipeline 23, wherein the raw materials in the front pipeline 21 can exchange heat with the external cold source through the third-stage main heat exchanger E12, and the raw materials in the tail pipeline 23 can exchange heat with the external cold source through the first-stage main heat exchanger E10.

[0048] The dewatering device is connected in series to the front pipeline 21 to reduce the moisture in the raw material.

[0049] In this embodiment, only the cold energy provided by the external cold source in one liquid cooling pipeline 1 is needed to meet the cooling requirements of the raw materials at different stages. At this time, the external cold source that can be used for cold energy can pass through the first-stage main heat exchanger E10, the second-stage main heat exchanger E13, and the third-stage main heat exchanger E12 in the entire dry ice preparation process. The cold energy is divided into three temperature ranges and is used for the cooling of different equipment in the system, respectively. The first-stage, second-stage, and third-stage cold energy utilization is performed, so that the cold energy can be fully utilized in the entire temperature level, and the gradient utilization of the cold energy by the feeding system can be realized, which can better match the cooling amount required by the feeding system at each stage in the dry ice preparation process. The dehydration device removes water in the front pipeline 21 near the feed port of the feeding pipeline to minimize the moisture content of the raw materials, reduce the influence of moisture in dry ice preparation, and reduce the regeneration energy consumption, so that this energy-saving carbon extraction and dry ice making system has a better energy-saving effect, and the system has a clear gradient setting framework, which optimizes the process organization of the system and reduces the difficulty of assembly.

[0050] In the cooling system, the liquid cooling pipeline 1 between the secondary main heat exchanger E13 and the tertiary main heat exchanger E12 is also connected in series with a rewarming vaporizer E11. The rewarming vaporizer E11 is specifically an air bath type vaporizer. At this time, an air bath type vaporizer is added before the last stage of cold energy utilization to consume the excess cold, so that the gas after the last stage of cold energy utilization (the third stage main heat exchanger E12) can be rewarmed to above 0°C or even room temperature, and the external cold source can be discharged from the liquid cooling system in a gaseous state, which is convenient for discharge or collection.

[0051] In the feeding system, such as Figure 2 As shown, the water removal device includes a water separator S and a moisture adsorber A1 which are sequentially connected in series to the front pipeline 21 along the flow direction of the raw material. At this time, the raw material in the front pipeline 21 passes through the water separator S and the moisture adsorber A1 sequentially.

[0052] There are multiple water separators S, for example, two water separators S are sequentially arranged along the flow direction of the raw material, namely a first water separator S1 and a second water separator S2.

[0053] The moisture adsorber A1 is a dryer. After the moisture adsorber A1 absorbs the moisture of the raw material, the normal pressure dew point of the raw material can be made not higher than the set temperature (such as -80°C).

[0054] At this time, the water removal device is located on the front pipeline 21 of the feed pipeline 2 close to the raw material inlet, and performs water separation and adsorption in sequence to remove as much water as possible from the raw material. The pre-separation by the water separator S can reduce the processing load of the moisture adsorber A1, thereby more effectively reducing the regeneration energy consumption.

[0055] To further improve the drainage effect, the feeding system also includes a tertiary loop heat exchanger E14 and a raw material compressor K1.

[0056] Specifically, Figure 2 As shown, the refrigerant channel of the tertiary loop heat exchanger E14 is connected in series with the heat medium channel of the tertiary main heat exchanger E12 to form a cooling loop, in which there is a tertiary refrigerant. The tertiary refrigerant can obtain cold energy from the tertiary main heat exchanger E12, and then cool the raw materials, realizing the tertiary utilization of cold energy from the external cold source.

[0057] The front pipeline 21 is connected to the heat medium channel of the tertiary loop heat exchanger E14 on the feed side of the water separator S, that is, on the front pipeline 21, the raw material first passes through the heat medium channel of the tertiary loop heat exchanger E14 and is condensed by the tertiary refrigerant before entering the water separator S.

[0058] The front pipeline 21 is connected in series with a raw material compressor K1, and the discharge side of the raw material compressor K1 is connected to the feed port of the heat medium channel of the tertiary loop heat exchanger E14, that is, on the front pipeline 21, after the raw material is compressed by the raw material compressor K1, it enters the corresponding tertiary loop heat exchanger E14 and is cooled by the tertiary refrigerant.

[0059] At this time, before the water separator S separates the condensed water from the raw material, it is cooled and / or compressed, which can further increase the water discharge volume and reduce the load of the water adsorber A1, ensuring that the water adsorber A1 directly absorbs the water and makes the raw material reach the set atmospheric pressure dew point.

[0060] More specifically, please refer to Figure 2 The tertiary loop heat exchanger E14 includes a first cooler E1 and a second cooler E2. Along the raw material flow direction, the heat medium channel of the first cooler E1, the first water separator S1, the raw material compressor K1, the heat medium channel of the second cooler E2, the second water separator S2, and the moisture adsorber A1 are connected in series in sequence through the front channel.

[0061] In the front pipeline 21, in a specific application, the raw material (carbon dioxide raw gas) after the preliminary treatment is used in the first cooler E1 to be cooled to a temperature above the freezing point of 0°C by the third-stage refrigerant for recycling cold energy, and the condensed water is separated and discharged in the first water separator S1; the raw material leaving the first water separator S1 is compressed to a certain pressure by the raw material compressor K1, and then cooled again to a temperature above 0°C by another third-stage refrigerant in the second cooler E2, and then continues to go to the second water separator S2 to separate and discharge the condensed water; the raw material leaving the second water separator S2 enters the moisture adsorber A1, and the moisture in the raw material is adsorbed to below the atmospheric dew point of -80°C. After the moisture is removed from the raw material, it enters the middle pipeline 22 for further cooling. At this time, the temperature of the raw material before and after the raw material compressor K1 is reduced to above 0°C, and as much water as possible can be discharged to reduce the load of the moisture adsorber A1 behind.

[0062] In the tertiary cooling circuit 5, if Figure 2 As shown, it also includes a three-stage coolant tank T1 and a three-stage coolant pump P1. The three-stage coolant tank T1 is a storage tank, and the three-stage coolant pump P1 is a liquid pump. The flow direction of the three-stage coolant is referenced Figure 2 The solid hollow arrows in the figure. Specifically, after the tertiary coolant is cooled by the external cold source in the tertiary main heat exchanger E12, it enters the tertiary coolant tank T1 for buffering. After the liquid out of the tank is pressurized to a certain pressure by the tertiary coolant pump P1, it is respectively transported to each tertiary loop heat exchanger E14 as a cooling medium. After the coldness is recovered by the raw material in the feed pipeline 2, the tertiary coolant is recombined into one stream and sent back to the tertiary main heat exchanger E12 for continuous circulation.

[0063] In the three-stage utilization of cold energy, the three-stage cooling circuit 5 and the different heat exchangers connected thereto can be used to flexibly meet the cooling requirements of different positions on the feed pipeline 2, such as matching the raw material refrigeration requirements on the feed side of different compressors.

[0064] like Figure 2 As shown, the three-stage loop heat exchanger E14 in the feeding system is provided in multiple numbers, for example, four, namely the first cooler E1, the second cooler E2, the third cooler E3, and the fourth cooler E4.

[0065] Among them, the heat medium channel of the tertiary main heat exchanger E12 and the refrigerant channel of the tertiary loop heat exchanger E14 are connected in series in the tertiary cooling loop 5, and the refrigerant channels of each tertiary loop heat exchanger E14 are connected in parallel, which can ensure the cooling capacity of each tertiary loop heat exchanger E14.

[0066] Among them, some of the three-stage loop heat exchangers E14 are front coolers, such as the first cooler E1 and the second cooler E2, and the remaining three-stage loop heat exchangers E14 are middle coolers, such as the third cooler E3 and the fourth cooler E4. The heat medium channel of the front cooler is connected in series in the front pipeline 21, and the heat medium channel of the middle cooler is connected in series in the middle pipeline 22.

[0067] The middle pipeline 22 is also connected in series with a supercharger, and the discharge port of the supercharger is connected to the feed port of the heat medium channel of the middle cooler (the third cooler E3 or the fourth cooler E4). At this time, on the middle pipeline 22, the raw material flows through the supercharger and then enters the corresponding middle cooler (the third cooler E3 or the fourth cooler E4) for cooling.

[0068] Specifically, the booster includes a primary booster K2 and a secondary booster K3 which are sequentially arranged along the flow direction of the raw material to adjust the carbon dioxide purification pressure (specifically, the outlet gas pressure of the secondary booster K3).

[0069] It should be noted that the raw material compressor K1, the first-stage booster K2, and the second-stage booster K3 can select suitable compressors according to needs, and each compressor can reduce the pressure of the raw material gas as much as possible, which can reduce the total energy consumption of the system. Of course, the raw material compressor K1 and each booster can also be selected in other quantities or canceled. In addition, in this embodiment, the raw material entering the booster is cooled by the three-stage cold energy of the three-stage main heat exchanger E12, which can be adapted to the existing models on the market. In other embodiments, the raw material entering the booster can also be cooled by the second-stage cold energy of the second-stage main heat exchanger E13 (down to -40°C).

[0070] In the secondary utilization of cold energy, such as Figure 3As shown, the secondary main heat exchanger E13 includes a first secondary main heat exchanger E5 and a second secondary main heat exchanger E6. The refrigerant channels of the first secondary main heat exchanger E5 and the refrigerant channels of the second secondary main heat exchanger E6 are connected in parallel to respectively meet the refrigeration requirements of raw materials at different positions on the middle pipeline 22.

[0071] Among them, the middle pipeline 22 includes a first branch 221, a second branch 222 and a third branch 223 which are arranged in sequence along the flow direction of the raw materials. The heat medium channels of the first and second main heat exchangers E5 are connected in series in the first branch 221; the heat medium channels of the supercharger and the middle cooler are connected in series in the second branch 222; the heat medium channels of the second and second main heat exchangers E6 are connected in series in the third branch 223. At this time, the raw materials flow out of the moisture adsorber A1 of the front pipeline 21 and enter the first branch 221, are cooled by the first and second main heat exchangers E5, then enter the second branch 222, are cooled by the tertiary loop heat exchanger E14 and compressed by the supercharger, and then enter the third branch 223 for cooling. In addition, by cooling the raw materials by sequentially entering different secondary main heat exchangers E13, the cooling capacity of the external cold source can be more fully utilized.

[0072] Of course, in other embodiments, the number of the first-stage main heat exchanger E10, the second-stage main heat exchanger E13, and the third-stage main heat exchanger E12 can also be set as needed. For example, only one second-stage main heat exchanger E13 is set.

[0073] In the middle pipeline 22, in a specific application: the raw material flows out of the front pipeline 21 and enters the middle pipeline 22, first goes to the first and second main heat exchangers E5 to exchange heat with a cold source for secondary utilization of cold energy (external cold source), is cooled to -40°C, goes to the first booster compressor K2 for pressurization, and then continues to be cooled to a certain temperature above 0°C by the third-stage refrigerant in the third cooler E3, and then continues to be compressed by the second-stage booster K3, and continues to be cooled to a certain temperature above 0°C by the third-stage refrigerant in the fourth cooler E4, and then goes to the second and second main heat exchangers E6 to exchange heat with another cold source for secondary utilization of cold energy (external cold source), is cooled to -40°C, and then flows to the tail pipeline 23.

[0074] In the primary utilization of cold energy, it can be mainly used to cool the raw materials at the top of the separation tower C, and the separation tower C can purify the raw materials. Of course, in other embodiments, when the raw materials do not have the need to remove impurities, the separation tower C may not be set, and the raw materials in the tail pipeline 23 can be directly cooled by the primary main heat exchanger E10.

[0075] like Figure 4 As shown, the feeding system also includes a separation tower C and a primary cooling circuit 4. At this time, through the heat exchange connection of the primary cooling circuit 4, the separator, the primary main heat exchanger E10 and the tail pipeline 23, the cooling requirements of the separator and the tail pipeline 23 before and after purification can be met respectively.

[0076] Specifically, the separation tower C has a tower top condenser. The primary cooling circuit 4 has a primary refrigerant, and the heat medium channel of the primary main heat exchanger E10 and the refrigerant channel of the tower top condenser are connected in series to the primary cooling circuit 4.

[0077] Among them, in the primary cooling circuit 4, as Figure 4 As shown, a primary coolant tank T2 (storage tank) and a primary coolant pump P2 may also be provided. The primary coolant tank T2 is a storage tank, and the primary coolant pump P2 is a liquid pump. Figure 4 The hollow arrow in the middle dashed line indicates the flow direction of the primary refrigerant. The primary main heat exchanger E10 transfers the cold energy to the primary refrigerant. After the primary refrigerant absorbs the primary cold energy of the external cold source at the primary main heat exchanger E10, it enters the primary refrigerant tank T2 for buffering. After the liquid out of the tank is pressurized to a certain pressure by the primary refrigerant pump P2, it is divided into two paths and transported to the de-weighting tower C1 and the de-lighting tower C2 as the tower top cold source. After being heated by the gas in the tower, they are respectively out of the tower top, reunited as one stream and sent back to the primary main heat exchanger E10 for continuous circulation.

[0078] Specifically, the separation tower C has a tower bottom reboiler. The tail pipe 23 sequentially connects the heat medium channel of the tower bottom reboiler and the feed port of the separation tower C in series, so that the raw material enters the feed port of the separation tower C after serving as the heat source of the tower bottom reboiler. In addition, in comparison, the first-stage refrigerant is a low-temperature refrigerant, and the third-stage refrigerant is a high-temperature refrigerant.

[0079] To improve the effect of impurity removal, Figure 4 As shown, the separation tower C includes a de-weighting tower C1 and a lightness-removing tower C2, and the tail pipeline 23 is connected in series with the feed port of the de-weighting tower C1, the top discharge port of the de-weighting tower C1, the feed port of the lightness-removing tower C2, and the bottom discharge port of the lightness-removing tower C2. The bottom discharge port of the de-weighting tower C1 is connected to a residual liquid vaporizer E7. The top discharge port of the lightness-removing tower C2 is connected to a tail gas vaporizer E8. Among them, the residual liquid vaporizer E7, the tail gas vaporizer E8, and the re-temperature vaporizer E11 are all air bath type vaporizers.

[0080] At this time, since the deheaving tower C1 and the lightness tower C2 are set up at the same time, the heavy component impurities and light component impurities of the raw materials can be removed at the same time, and the product reaches 99.99% high-purity or food-grade carbon dioxide, and the simultaneous production of liquid carbon dioxide products and dry ice products can be achieved.

[0081] In the tail pipeline 23, a specific application is as follows: the pressurized raw gas entering the tail pipeline 23 is divided into two streams, which are used as the heat sources of the bottoms of the deweighting tower C1 and the lightness removing tower C2 respectively. After being cooled to a temperature close to the dew point, the two streams of gas are reunited and enter the feed port of the deweighting tower C1 for distillation; a small amount of heavy component impurities are separated in the deweighting tower C1, discharged from the bottom outlet of the tower, vaporized and reheated by the residual liquid vaporizer E7, and then throttled and reduced in pressure by the waste gas pressure reducing valve V1 before being discharged.

[0082] A small part of the gas in the de-weighting tower C1 is condensed and refluxed by a first-level refrigerant used for the first-level utilization of cold energy at the top of the tower, and most of the uncondensed gas leaves the de-weighting tower C1 and enters the lightness removal tower C2; the gas at the top of the lightness removal tower C2 is mostly condensed by another first-level refrigerant used for the first-level utilization of cold energy, and a small amount of uncondensed light component impurities are discharged from the discharge port at the top of the tower.

[0083] The impurity gas discharged from the top outlet of the light-removal tower C2 is reheated by the tail gasifier E8, and then throttled and depressurized by the tail gas pressure reducing valve V2 before being discharged. The liquid discharged from the bottom outlet of the light-removal tower C2 is a food-grade carbon dioxide liquid product with a purity of 99.99% after the water, heavy component impurities and light component impurities are removed, and enters the tail pipeline 23 again.

[0084] In addition, in the final preparation of dry ice, Figure 1 and Figure 4 As shown, the feeding system also includes a subcooler E9 and a return line 3. The subcooler E9 is a heat exchanger. The tail line 23 is connected in series with the heat medium channel of the subcooler E9 and the feed port of the dry ice machine M. The feed port of the return line 3 is connected to the return port of the dry ice machine M. The refrigerant channel of the subcooler E9 is connected in series with the return line 3, and the discharge port of the return line 3 is connected to the middle line 22, for example, connected to the feed port of the second branch 222.

[0085] At this time, the liquid discharged from the light tower C2 is supercooled by the supercooler E9, and a part of it is throttled and depressurized by the dry ice making valve V3 before going to the dry ice machine M; the dry ice machine M produces dry ice and discharges it, and the generated gasified carbon dioxide gas is discharged through the return port into the return pipeline 3, which is used as the cold source of the supercooler E9. After part of the cold capacity is recovered, it is mixed with the -40°C carbon dioxide cold gas from the first and second main heat exchangers E5, and then goes to the first-stage booster K2 for compression and circulation. Among them, the exhaust gas pressure reducing valve V1, the tail gas pressure reducing valve V2, and the dry ice making valve V3 are all pressure reducing valves.

[0086] In addition, the tail pipe 23 has two outlets, namely, a second outlet 232 and a first outlet 231 connected to the dry ice machine M. The second outlet 232 is used to provide liquid CO 2That is to say, this part of the raw liquid product discharged from the light tower C2 is directly output as a carbon dioxide liquid product, and can be directly pressurized and transported to a pressurized storage tank area or a tank truck.

[0087] In the energy-saving carbon extraction and dry ice making system of this embodiment, in the liquid cooling system, the application process of the external cold source includes:

[0088] The external cold source of the utilized cold energy is a cryogenic liquid when it enters the liquid cooling system. In the entire purification and liquefaction process, it undergoes the primary utilization, secondary utilization, and tertiary utilization of cold energy. The primary utilization of cold energy is achieved through the primary main heat exchanger E10, the secondary utilization of cold energy is achieved through the first and second main heat exchangers E5 and the second and second main heat exchangers E6, and the tertiary utilization of cold energy is achieved through the tertiary main heat exchanger E12.

[0089] The external cold source transfers the cold to the primary refrigerant through the primary main heat exchanger E10. After the primary refrigerant absorbs the primary cold energy of the external cold source at the primary main heat exchanger E10, it is divided into two paths and transported to the deweighting tower C1 and the lightness removing tower C2 as the tower top cold source. After being heated by the gas in the tower, they are respectively discharged from the tower top, reunited as one stream and sent back to the primary main heat exchanger E10 to continue circulation.

[0090] After the first-level utilization of cold energy, most or all of the external cold source has been vaporized into gas, which is divided into two streams and goes to the first-level main heat exchanger E5 and the second-level main heat exchanger E6 for the second-level utilization of cold energy respectively. After heat exchange with the carbon dioxide gas at the outlet of the two compressors (raw material compressor K1, second-level booster K3), it is reheated to a certain temperature and then merged into a third-level cold gas to complete the second-level utilization of cold energy.

[0091] After the secondary utilization of cold energy, the external cold source (cold gas at this time) is removed and reheated by the vaporizer E11 to transfer part of the excess cold to the air, and then the tertiary main heat exchanger E12 for tertiary utilization of cold energy transfers the remaining cold to the tertiary refrigerant, and reheats to above 0°C or even room temperature before output. After the tertiary refrigerant is cooled, it is divided into multiple streams and respectively transported to the coolers (first cooler E1, second cooler E2, third cooler E3, fourth cooler E4) connected to the front pipeline 21 and the middle pipeline 22 as cooling medium. After the cold is recovered by the raw gas, the four streams of tertiary refrigerants are reunited into one stream and sent back to the tertiary main heat exchanger E12 for further circulation.

[0092] The energy-saving carbon extraction and dry ice making system provided in this embodiment is an energy-saving and efficient carbon dioxide purification and liquefaction process that realizes the cascade utilization of cold energy, and a complete process system for converting part of the carbon dioxide liquid product into dry ice, which has the following advantages: the cascade utilization of cold energy in the process better matches the cold capacity required by each device in the process; the gas inlet temperature of each level of the raw material compressor K1 is cooled as much as possible, and the pressure of the raw material compressor K1 and the booster is reduced as much as possible, so as to achieve the purpose of reducing the total energy consumption of the system; before the raw material enters the moisture adsorber A1 for preliminary treatment, the water in the raw material is removed as much as possible, thereby reducing the water gas treatment load of the adsorber and reducing the regeneration energy consumption; the water, light components and heavy components impurities in the raw gas can be removed at the same time to achieve the production of high-purity carbon dioxide, and the production of two products, carbon dioxide liquid and dry ice, can be achieved at the same time; the cold energy utilization efficiency is higher, which saves more than 60% energy than the traditional carbon dioxide purification and liquefaction system without cold energy utilization; the gas after cold energy utilization is reheated to above 0°C or even room temperature, reducing the cold pollution that may be caused to the environment by the gasification of low-temperature liquid, the system consideration is more complete, the cold energy utilization is more complete, and power consumption can be saved.

[0093] The energy-saving carbon extraction and dry ice making system provided by the present invention has a specific example as follows to illustrate the overall application process:

[0094] The composition (molar percentage) of the raw gas is CO 2 95%、H 2 O 4.5%, CH 4 0.12%、N 2 0.15%、O 2 0.11%、H 2 S 0.05%, alcohol ammonia 0.07%, temperature 50℃, pressure 10kPa (G).

[0095] The cryogenic liquid (i.e., the external cold source entering the liquid cooling system) is liquefied natural gas (LNG), and its composition (molar percentage) is CH 4 99.84%, N 2 0.15%, C2H6 0.01%, temperature -155℃, pressure 24bar(G).

[0096] CO 2The raw gas is cooled to 5°C by the tertiary coolant in the first cooler E1, and the condensed water is separated and discharged in the first water separator S1. The gas leaving the first water separator S1 is compressed to 1.5 to 2.2 bar (G) by the raw compressor K1, and then cooled to 5°C again by another tertiary coolant in the second cooler E2, and the condensed water is separated and discharged in the second water separator S2. The gas from the second water separator S2 enters the moisture adsorber A1, where the gas moisture is adsorbed to a dew point below -80°C at normal pressure. After the moisture is removed, the gas goes to the first and second main heat exchangers E5 to exchange heat with a cold source for secondary utilization of cold energy, and is cooled to -40°C. After that, it is mixed with the carbon dioxide gas returned from the subcooler E9, and then goes to the first booster K2 to be pressurized to 2.5 to 3.5 bar (G). Then, it is further cooled to 5°C by the third-stage refrigerant in the third cooler E3, and then further compressed to 7 to 8 bar (G) by the second-stage booster K3. It is further cooled to 5°C by the third-stage refrigerant in the fourth cooler E4, and then goes to the second and second main heat exchangers E6 to exchange heat with another cold source for secondary utilization of cold energy, and is cooled to -40°C. Then, the pressurized gas is divided into two streams, which are used as the heat sources of the bottoms of the de-weighting tower C1 and the de-lighting tower C2 respectively. The two streams of gas cooled to a temperature close to the dew point temperature are reunited and enter the de-weighting tower C1 for distillation. In the deweighting tower C1, trace H 2 S and alcohol ammonia and other component impurities, the residual liquid at the bottom of the tower is vaporized by the residual liquid vaporizer E7 and reheated to above -20℃ (above -40℃ is acceptable here, this step is to consider the problem of dry ice blocking the discharge pipe due to the easy cooling of carbon dioxide gas to the freezing point during depressurization and discharge), and is throttled and depressurized by the exhaust gas pressure reducing valve V1 to a pressure slightly higher than normal pressure and discharged. A small part of the gas in the tower is condensed and refluxed by a first-level refrigerant used in the first stage of cold energy at the top of the tower, and most of the uncondensed gas leaves the deheaving tower C1 and enters the light-removing tower C2. The gas at the top of the light-removing tower C2 is mostly condensed by another first-level refrigerant used in the first stage of cold energy, and a small amount of uncondensed light component impurities CH 4 、N 2 , O 2 and CO 2It is discharged from the top of the tower, and reheated to above -20℃ (same as E7) through the tail gas vaporizer E8, and throttled and depressurized to a pressure slightly higher than normal pressure by the tail gas depressurization valve V2 to be discharged. The liquid at the bottom of the tower is a food grade carbon dioxide liquid product with a purity of 99.99% after removing water, heavy component impurities, and light component impurities. Considering the process of producing dry ice from some liquids, this liquid is supercooled by 3 to 4℃ through the supercooler E9, and 30% of the flow is directly output as a carbon dioxide liquid product, and the other 70% is throttled and depressurized to 1 bar (G) through the dry ice valve V3 to go to the dry ice machine M. The dry ice machine M produces 45% of the liquid dry ice product, and another 55% of the carbon dioxide gas is generated. Considering recycling, it is first used as the cold source of the supercooler E9. After part of the cold capacity is recovered, it is mixed with the -40℃ carbon dioxide cold gas from the first and second main heat exchangers E5, and then sent to the first-stage booster for compression and circulation.

[0097] The cryogenic liquid (external cold source) transfers the cold to the primary refrigerant through the primary main heat exchanger E10. After the refrigerant absorbs the primary cold energy, it enters the primary refrigerant tank T2 for buffering. The liquid out of the tank is pressurized to 2 to 3 bar (G) by the primary refrigerant pump P2, and then transported to the deweighting tower C1 and the lightness tower C2 as the top cold source. After being heated by the gas in the tower at the top of the tower, it is reunited into one stream and sent back to the primary main heat exchanger E10 for further circulation.

[0098] After the first-level utilization of cold energy, most or all of the cryogenic liquid (external cold source) has been vaporized into gas, and is divided into two streams, which are respectively sent to the first and second-level heat exchangers for the second-level utilization of cold energy and the second-level main heat exchanger E6. After heat exchange with the two streams of carbon dioxide gas at the outlet of the compressor, they are reheated to a certain temperature and then merged into a cold gas, completing the second-level utilization of cold energy. After the low-temperature cold gas reheating vaporizer E11 for the second-level utilization of cold energy transfers part of the excess cold to the air, and then transfers the remaining cold to the third-level refrigerant to the third-level main heat exchanger E12 for the third-level utilization of cold energy, and reheats to 5℃ for output. The tertiary refrigerant is cooled to 0 to 3°C and enters the tertiary refrigerant tank T1 for buffering. After the liquid out of the tank is pressurized to 2 to 3 bar (G) by the tertiary refrigerant pump P1, it is divided into four streams and respectively transported to the first cooler E1, the second cooler E2, the third cooler E3, and the fourth cooler E4 as cooling medium. After the cold energy is recovered, the four streams are reunited into one stream and sent back to the tertiary main heat exchanger E12 for continued circulation.

[0099] The tertiary coolant can be water, ethylene glycol aqueous solution, silicone oil, oil, refrigerant and other substances; the primary coolant can be refrigerant, hydrocarbons and other substances.

[0100] Through this example, 2t / h, 6bar (G) CO is produced simultaneously 2Liquid products and 2t / h dry ice products, the energy consumption of the raw material compressor K1 and the booster is only 300kW, compared with the conventional CO2 2 The purification and liquefaction process reduces energy consumption by 65%, with significant energy-saving benefits.

[0101] It should be noted that when an element is referred to as "fixed" to another element, it may be directly on the other element or there may be an element in the middle. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an element in the middle. In addition, in the description of the present invention, unless otherwise specified, "multiple", "multiple roots", "multiple groups" mean two or more.

[0102] The terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0103] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0104] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0105] The energy-saving carbon extraction and dry ice making system provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. An energy-saving carbon extraction and dry ice making system, characterized in that: include: A liquid cooling system comprises a primary main heat exchanger (E10), a secondary main heat exchanger (E13) and a tertiary main heat exchanger (E12), wherein the refrigerant channels of the primary main heat exchanger (E10), the secondary main heat exchanger (E13) and the tertiary main heat exchanger (E12) are sequentially connected in series through a liquid cooling pipeline (1), and the liquid cooling system is used to receive an external cold source, and the external cold source can sequentially pass through the primary main heat exchanger (E10), the secondary main heat exchanger (E13) and the tertiary main heat exchanger (E12). The cold energy of the external cold source is divided into three temperature ranges through the first-stage main heat exchanger (E10), the second-stage main heat exchanger (E13) and the third-stage main heat exchanger (E12), and is utilized in the entire dry ice preparation process. The liquid cooling pipeline (1) between the second-stage main heat exchanger (E13) and the third-stage main heat exchanger (E12) is also connected in series with a reheating vaporizer (E11); A feed system, comprising a feed pipeline (2), a water removal device and a dry ice machine (M), wherein the feed pipeline (2) is used to receive a raw material including a gas of CO2; The feed pipeline (2) includes a front pipeline (21), a middle pipeline (22) and a rear pipeline (23) in sequence along the flow direction of the raw materials, and the dry ice machine (M) is connected to a first discharge port (231) of the rear pipeline (23), wherein the raw materials in the front pipeline (21) can exchange heat with the external cold source through the third-stage main heat exchanger (E12), and the raw materials in the rear pipeline (23) can exchange heat with the external cold source through the first-stage main heat exchanger (E10), and the dehydration device is connected in series to the front pipeline (21) to reduce the moisture in the raw materials, so that the normal pressure dew point of the raw materials is not higher than the set temperature; The feeding system further comprises a tertiary cooling circuit (5) and a plurality of tertiary circuit heat exchangers (E14), wherein the tertiary cooling circuit (5) comprises a tertiary coolant; the heat medium channel of the tertiary main heat exchanger (E12) and the refrigerant channel of the tertiary circuit heat exchanger (E14) are connected in series in the tertiary cooling circuit (5), and the refrigerant channels of each tertiary circuit heat exchanger (E14) are connected in parallel; wherein some of the tertiary circuit heat exchangers (E14) are front coolers, and the rest of the tertiary circuit heat exchangers (E14) are middle coolers; the heat medium channel of the front cooler is connected in series in the front pipeline (21), and the heat medium channel of the middle cooler is connected in series in the middle pipeline (22); the middle pipeline (22) is also connected in series with a supercharger, and the discharge port of the supercharger is connected to the discharge port of the supercharger; The feed port of the heat medium channel of the middle cooler; the secondary main heat exchanger (E13) includes a first secondary main heat exchanger (E5) and a second secondary main heat exchanger (E6), and the refrigerant channel of the first secondary main heat exchanger (E5) and the refrigerant channel of the second secondary main heat exchanger (E6) are connected in parallel; the middle pipeline (22) includes a first branch (221), a second branch (222) and a third branch (223) arranged in sequence along the flow direction of the raw material; the heat medium channel of the first secondary main heat exchanger (E5) is connected in series to the first branch (221); the heat medium channels of the booster and the middle cooler are connected in series to the second branch (222); the heat medium channel of the second secondary main heat exchanger (E6) is connected in series to the third branch (223); The front pipeline (21) is also connected in series with a raw material compressor (K1), and the discharge side of the raw material compressor (K1) is connected to the feed port of the heat medium channel of the tertiary loop heat exchanger (E14); The feed system further comprises a separation tower (C) and a primary cooling circuit (4); the separation tower (C) is used to purify the raw material; the separation tower (C) has a top condenser; the primary cooling circuit (4) has a primary refrigerant, and the heat medium channel of the primary main heat exchanger (E10) and the refrigerant channel of the top condenser are connected in series to the primary cooling circuit (4); the separation tower (C) has a bottom reboiler; the tail pipeline (23) is connected in series with the heat medium channel of the bottom reboiler and the feed port of the separation tower (C), so that the raw material enters the feed port of the separation tower (C) after serving as a heat source for the bottom reboiler.

2. The energy-saving carbon extraction and dry ice making system according to claim 1 is characterized in that: The dewatering device comprises a water separator (S) and a moisture adsorber (A1) which are sequentially connected in series to the front pipeline (21) along the flow direction of the raw material; Wherein, after the moisture adsorber (A1) adsorbs the moisture of the raw material, the atmospheric pressure dew point of the raw material can be made not higher than the set temperature.

3. The energy-saving carbon extraction and dry ice making system according to claim 2 is characterized in that: The front pipeline (21) is connected to the heat medium channel of the tertiary loop heat exchanger (E14) at the feed side of the water separator (S).

4. The energy-saving carbon extraction and dry ice making system according to claim 1 is characterized in that: The separation tower (C) comprises a weight removal tower (C1) and a lightness removal tower (C2), and the tail pipeline (23) sequentially connects the feed inlet of the weight removal tower (C1), the top discharge port of the weight removal tower (C1), the feed inlet of the lightness removal tower (C2), and the bottom discharge port of the lightness removal tower (C2) in series; The bottom outlet of the deweighting tower (C1) is connected to a residual liquid gasifier (E7); The top outlet of the lightness removal tower (C2) is connected to a tail gas gasifier (E8).

5. The energy-saving carbon extraction and dry ice making system according to claim 1 is characterized in that: The feed system further comprises a subcooler (E9) and a return line (3); The tail pipeline (23) is sequentially connected in series with the heat medium channel of the subcooler (E9) and the feed port of the dry ice machine (M); The feed port of the reflux pipeline (3) is connected to the return port of the dry ice machine (M); The refrigerant channel of the subcooler (E9) is connected in series to the return pipeline (3), and the outlet of the return pipeline (3) is connected to the middle pipeline (22).

6. The energy-saving carbon extraction and dry ice making system according to claim 1 is characterized in that: The tail pipeline (23) also has a second discharge port (232), and the second discharge port (232) is used to provide liquid CO2.

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