Dry ice production device and production method for reducing carbon dioxide loss

Abstract

The present invention relates to a dry ice production device and method for reducing carbon dioxide loss. The device comprises a liquid carbon dioxide production device, a liquid carbon dioxide storage tank connected to the liquid carbon dioxide production device, and a dry ice pelletizer. The liquid carbon dioxide storage tank is connected to the dry ice pelletizer via a pre-cooling separation unit. The gas phase outlets of the pre-cooling separation unit and the dry ice pelletizer are connected to the liquid carbon dioxide storage tank via a gas phase recovery unit. The gas phase recovery unit comprises a liquefaction pre-cooling unit connected to the gas phase outlets of the pre-cooling separation unit and the dry ice pelletizer, and a gas compression unit and a gas liquefaction unit connected in sequence to the liquefaction pre-cooling unit. The dry ice production method has the advantages of simple process, convenient operation, economic reliability, environmental protection and energy saving, easy promotion, and the ability to effectively recover the diffused gaseous carbon dioxide, thereby reducing the consumption of liquid carbon dioxide during dry ice production.

Description

Technical Field

[0001] The present invention relates to the technical field of dry ice production, and in particular to a dry ice production device and method for reducing carbon dioxide loss. Background Art

[0002] Dry ice is a solid form of carbon dioxide. Currently, the main process for producing dry ice involves throttling and reducing the pressure of liquid carbon dioxide to form solid dry ice. During this process, the dry ice equipment and process pipelines cause the finished dry ice to continuously sublime. This production process generates a large amount of low-temperature carbon dioxide gas, which is generally discharged directly. The liquid carbon dioxide consumption during the dry ice production process is as high as 3.2 tons per ton of dry ice. At the same time, the carbon dioxide concentration in and around the production plant is too high, posing a health hazard to production operators. This is inconsistent with the concepts of energy conservation, consumption reduction, and low-carbon environmental protection. Summary of the Invention

[0003] In response to the shortcomings of the existing technology, the present invention provides a dry ice production device and production method that has a simple process, convenient operation, economic reliability, environmental protection and energy saving, is easy to promote, and can effectively recover the released gas carbon dioxide, reduce the consumption of liquid carbon dioxide during dry ice production, and reduce carbon dioxide loss.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A dry ice production device for reducing carbon dioxide loss comprises a liquid carbon dioxide production device, a liquid carbon dioxide storage tank connected to the liquid carbon dioxide production device, and a dry ice pelletizer. The liquid carbon dioxide storage tank is connected to the dry ice pelletizer via a pre-cooling separation unit. The gas phase outlet of the pre-cooling separation unit and the dry ice pelletizer is connected to the liquid carbon dioxide storage tank via a gas phase recovery unit. The gas phase recovery unit comprises a liquefaction pre-cooling unit connected to the gas phase outlet of the pre-cooling separation unit and the dry ice pelletizer, and a gas compression unit and a gas liquefaction unit, which are sequentially connected to the liquefaction pre-cooling unit.

[0006] Preferably, the pre-cooling separation unit includes a subcooler connected to the liquid carbon dioxide storage tank, the hot end channel of the subcooler is connected to the first gas-liquid separator, and the liquid phase outlet of the first gas-liquid separator is connected to the dry ice pelletizer.

[0007] Preferably, the gas phase outlet of the pre-cooling separation unit is the gas phase outlet of the first gas-liquid separator, and the gas phase outlet of the first gas-liquid separator is connected to the liquefaction pre-cooling unit through the cold end channel I of the supercooler; the gas phase outlet of the dry ice granulator is connected to the liquefaction pre-cooling unit through the cold end channel II of the supercooler.

[0008] Preferably, the liquefaction precooling unit is a liquefaction precooler, the cold end channel I of the subcooler is connected to the gas compression unit through the cold end channel I of the liquefaction precooler, and the cold end channel II of the subcooler is connected to the gas compression unit through the cold end channel II of the liquefaction precooler.

[0009] Preferably, the gas compression unit includes a compressor and a buffer, the inlet of the buffer is connected to the outlet of the cold end channel II of the liquefied precooler, the outlet of the buffer is connected to the first-level inlet of the compressor, the outlet of the cold end channel I of the liquefied precooler is connected to the second-level inlet of the compressor, and the outlet of the compressor is connected to the gas liquefaction unit through the hot end channel of the liquefied precooler.

[0010] Preferably, the gas liquefaction unit includes a carbon dioxide liquefier with a built-in coil, the inlet of the coil is connected to the outlet of the hot end channel of the liquefied precooler, the outlet of the coil is connected to the second gas-liquid separator, and the liquid phase outlet of the second gas-liquid separator is connected to the liquid carbon dioxide storage tank; the subcooler and the liquefied precooler are both plate-fin heat exchangers.

[0011] Preferably, the gas phase outlet of the carbon dioxide liquefier is connected to the inlet of the low-temperature working condition ice machine, and the outlet of the low-temperature working condition ice machine is connected to the liquid phase inlet of the carbon dioxide liquefier through a liquid ammonia storage tank.

[0012] Preferably, it also includes a control unit, which includes a single-chip microcomputer, and the signal input end of the single-chip microcomputer is respectively connected to the first pressure transmitter, the second pressure transmitter, the first liquid level sensor, the second liquid level sensor and the third liquid level sensor; the signal output end of the single-chip microcomputer is respectively connected to the first regulating valve, the second regulating valve, the pressure reducing valve, the third regulating valve and the fourth regulating valve.

[0013] Preferably, the first pressure transmitter is arranged between the gas phase outlet of the dry ice granulator and the cold end channel II of the subcooler; the second pressure transmitter is arranged between the gas phase outlet of the first gas-liquid separator and the cold end channel I of the subcooler; the first liquid level sensor is arranged on the first gas-liquid separator, the second liquid level sensor is arranged on the carbon dioxide liquefier, and the third liquid level sensor is arranged on the second gas-liquid separator; the first regulating valve is arranged on the first pressure relief pipe between the cold end channel II of the subcooler and the cold end channel II of the liquefied precooler; the second regulating valve is arranged on the second pressure relief pipe between the cold end channel I of the subcooler and the cold end channel I of the liquefied precooler; the pressure reducing valve is arranged between the hot end channel of the subcooler and the first gas-liquid separator; the third regulating valve is arranged between the liquid ammonia storage tank and the liquid phase inlet of the carbon dioxide liquefier; the fourth regulating valve is arranged between the liquid phase outlet of the second gas-liquid separator and the liquid carbon dioxide storage tank.

[0014] A method for producing a dry ice production device for reducing carbon dioxide loss comprises the following steps:

[0015] Step 1: Liquid carbon dioxide in the carbon dioxide storage tank is transported via a pipeline to the hot end channel of the subcooler to exchange heat with low-temperature carbon dioxide gas from the first gas-liquid separator and the dry ice pelletizer to reduce the temperature of the liquid carbon dioxide to -24.6°C. The pressure of the liquid carbon dioxide in the carbon dioxide storage tank is 1.96 MPa and the temperature is -20°C.

[0016] Step 2: The cooled liquid carbon dioxide is throttled and decompressed to 0.6 MPa through a pressure reducing valve, and the temperature is further reduced to -52°C. The throttled liquid carbon dioxide enters the first gas-liquid separator to separate part of the gas generated during the throttling process, and is then transported to the dry ice pelletizer through a pipeline for pelletization;

[0017] Step 3: The gaseous carbon dioxide generated by the first gas-liquid separator enters the cold end channel I of the subcooler through the gas phase outlet of the first gas-liquid separator, and the gaseous carbon dioxide generated by the dry ice pelletizer enters the cold end channel II of the subcooler through the gas phase outlet of the ice pelletizer. After the two streams of gaseous carbon dioxide cool the liquid phase carbon dioxide in step 1, they themselves reheat. The gaseous carbon dioxide generated by the first gas-liquid separator has a temperature of -52°C and a pressure of 0.6 MPa; the gaseous carbon dioxide generated by the dry ice pelletizer has a temperature of -65°C and a pressure of 0.2 MPa. The temperature of the gaseous carbon dioxide after reheating is -23°C.

[0018] Step 4: The reheated gaseous carbon dioxide at the outlet of the cold end channel I of the subcooler enters the secondary inlet of the compressor through the second pressure relief pipe and the cold end channel I of the liquefied precooler; the reheated gaseous carbon dioxide at the outlet of the cold end channel II of the subcooler enters the primary inlet of the compressor through the first pressure relief pipe, the cold end channel II of the liquefied precooler, and the buffer; the pressure of the gaseous carbon dioxide entering the buffer is 0.2 MPa and the temperature is 35°C; the pressure of the gaseous carbon dioxide entering the secondary inlet of the compressor is 0.6 MPa and the temperature is 35°C; the pressure of the gas after compression by the compressor is 2.3 MPa and the temperature is 40°C;

[0019] Step 5: The gas compressed by the compressor is pre-cooled through the hot end channel of the liquefied pre-cooler and then transported to the built-in coil of the carbon dioxide liquefier for liquefaction. The temperature of the carbon dioxide gas pre-cooled through the hot end channel of the liquefied pre-cooler is -8°C, and the temperature of the carbon dioxide after liquefaction in the built-in coil is -24°C.

[0020] Step 6: The liquefied carbon dioxide enters the second gas-liquid separator for gas-liquid separation, and the liquid phase after gas-liquid separation is connected to the carbon dioxide storage tank;

[0021] Step 7: The liquid carbon dioxide production device is connected to the carbon dioxide storage tank;

[0022] Step 8: The first liquid level sensor is used to monitor the liquid level in the first gas-liquid separator. By maintaining the stability of the liquid level, the dry ice pelletizer can be ensured to be able to stably and continuously feed liquid, thereby improving the pellet yield. When the liquid level in the first gas-liquid separator is too high, the single-chip microcomputer controls the pressure reducing valve to reduce the opening, increase the amount of carbon dioxide vaporization, and reduce the liquid level in the first gas-liquid separator. When the liquid level in the first gas-liquid separator is too low, the single-chip microcomputer controls the pressure reducing valve to increase the opening, reduce the amount of carbon dioxide vaporization, and increase the liquid level in the first gas-liquid separator.

[0023] Step 9: The second pressure transmitter is used to monitor the gas pressure entering the cold end channel I of the subcooler. When the pressure exceeds the given process index, the single chip microcomputer controls the second regulating valve to release the pressure.

[0024] Step 10: The first pressure transmitter is used to monitor the pressure of the gas entering the cold end channel II of the subcooler. When the pressure exceeds the given process index, the single chip microcomputer controls the first regulating valve to release the pressure.

[0025] Step 11: The second liquid level sensor is used to monitor the liquid level of liquid ammonia in the carbon dioxide liquefier. By maintaining the liquid level stable, the gaseous carbon dioxide can be fully liquefied, thereby improving the recovery rate of the released gaseous carbon dioxide. When the liquid level is too low, the single-chip microcomputer controls the opening of the third regulating valve to increase to balance the liquid level of the carbon dioxide liquefier. When the liquid level is too high, the single-chip microcomputer controls the opening of the third regulating valve to decrease to adjust the liquid level of the carbon dioxide liquefier.

[0026] Step 12: The third liquid level sensor is used to monitor the liquid level of liquid carbon dioxide, and the single chip microcomputer adjusts the liquid level in the second gas-liquid separator by controlling the opening of the fourth regulating valve.

[0027] The present invention can effectively recover the diffused carbon dioxide gas to solve the defects of large liquid carbon dioxide usage and high energy consumption in the dry ice production system. While ensuring the normal operation of the dry ice production system, the diffused low-temperature carbon dioxide gas can be effectively recovered according to actual needs, so that the consumption of liquid carbon dioxide in dry ice production is reduced to 1.4 tons per ton of dry ice. The present invention has the advantages of simple process, convenient operation, economic reliability, environmental protection, energy saving and easy promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the present invention.

[0029] Figure 2 This is a control principle diagram of the present invention. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of 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. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] See Figures 1-2 : The present invention is a dry ice production device and production method for reducing carbon dioxide loss, wherein the device includes a liquid carbon dioxide production device 12, a liquid carbon dioxide storage tank 1 connected to the liquid carbon dioxide production device 12, and a dry ice granulator 4, the liquid carbon dioxide storage tank 1 is connected to the dry ice granulator 4 through a pre-cooling separation unit, and the gas phase outlet of the pre-cooling separation unit and the dry ice granulator 4 is connected to the liquid carbon dioxide storage tank 1 through a gas phase recovery part; the gas phase recovery part includes a liquefaction pre-cooling unit connected to the gas phase outlet of the pre-cooling separation unit and the dry ice granulator 4, and a gas compression unit and a gas liquefaction unit connected to the liquefaction pre-cooling unit in sequence. The liquid carbon dioxide production device 12 described in the present invention is used to produce liquid carbon dioxide and transport the liquid carbon dioxide to the liquid carbon dioxide storage tank 1. The liquid carbon dioxide is pre-cooled by the pre-cooling separation unit and the gaseous carbon dioxide is separated in advance, so as to improve the working efficiency of the dry ice granulator 4 and reduce its workload; and the gas phase in the pre-cooling separation unit and the dry ice granulator 4 described in the present invention is recovered by the liquefaction pre-cooling unit, and is converted into liquid carbon dioxide and re-integrated into the liquid carbon dioxide storage tank 1 for reuse; the present invention can effectively reduce the amount of carbon dioxide gas entering or retained in the dry ice granulator 4 by recovering the gas phase in the pre-cooling separation unit and the dry ice granulator 4, which not only improves the recovery rate of the gaseous carbon dioxide and the granulation efficiency of the dry ice granulator 4, but also effectively solves the problem of explosion of the dry ice granulator 4, thereby achieving the purpose of reducing the failure rate of the dry ice granulator 4.

[0032] Furthermore, the pre-cooling and separation unit includes a subcooler 2 connected to a liquid carbon dioxide storage tank 1. The hot end channel of the subcooler 2 is connected to a first gas-liquid separator 3. The liquid phase outlet of the first gas-liquid separator 3 is connected to a dry ice pelletizer 4. The subcooler 2 and pressure reducing valve 17 described in the present invention are used to pre-cool the liquid carbon dioxide and separate the pre-cooled carbon dioxide into gas and liquid through the first gas-liquid separator 3, thereby reducing the workload of the dry ice pelletizer 4.

[0033] Furthermore, the gas phase outlet of the pre-cooling separation unit is the gas phase outlet of the first gas-liquid separator 3, which is connected to the liquefaction pre-cooling unit via the cold end channel I of the subcooler 2. The gas phase outlet of the dry ice pelletizer 4 is connected to the liquefaction pre-cooling unit via the cold end channel II of the subcooler 2. By passing the gas phase through the subcooler 2, pre-cooling of the liquid carbon dioxide and recovery of the cooling energy of the gas phase can be achieved.

[0034] Furthermore, the liquefaction precooling unit is a liquefaction precooler 5. The cold end channel I of the subcooler 2 is connected to the gas compression unit through the cold end channel I of the liquefaction precooler 5, and the cold end channel II of the subcooler 2 is connected to the gas compression unit through the cold end channel II of the liquefaction precooler 5. By allowing the once-reheated carbon dioxide gas phase to enter the liquefaction precooler 5, the compressor outlet carbon dioxide gas is precooled before liquefaction.

[0035] Furthermore, the gas compression unit includes a compressor 6 and a buffer 7. The inlet of the buffer 7 is connected to the outlet of the cold-end channel II of the liquefied precooler 5. The outlet of the buffer 7 is connected to the primary inlet of the compressor 6. The outlet of the cold-end channel I of the liquefied precooler 5 is connected to the secondary inlet of the compressor 6. The outlet of the compressor 6 is connected to the gas liquefaction unit via the hot-end channel of the liquefied precooler 5. The provision of the buffer 7 and the compressor 6 enables effective compression of the gaseous carbon dioxide, laying the foundation for its subsequent liquefaction.

[0036] Furthermore, the gas liquefaction unit includes a carbon dioxide liquefier 8 with a built-in coil 22. The inlet of the coil 22 is connected to the outlet of the hot end channel of the liquefied precooler 5, and the outlet of the coil 22 is connected to the second gas-liquid separator 9. The liquid phase outlet of the second gas-liquid separator 9 is connected to the liquid carbon dioxide storage tank 1. The subcooler 2 and the liquefied precooler 5 are both plate-fin heat exchangers. The present invention liquefies the gaseous carbon dioxide through the carbon dioxide liquefier 8, preferably using an immersion method, so that the coil 22 containing carbon dioxide is immersed in the cooling medium in the carbon dioxide liquefier 8, and the carbon dioxide is liquefied while heat exchange is performed. The liquefied carbon dioxide enters the second gas-liquid separator 9 for gas-liquid separation, and the liquid carbon dioxide in the second gas-liquid separator 9 is re-entered into the liquid carbon dioxide storage tank 1, thereby achieving the purpose of reducing the consumption of liquid carbon dioxide.

[0037] Furthermore, the gas phase outlet of the carbon dioxide liquefier 8 is connected to the inlet of a low-temperature operating ice machine 11, and the outlet of the low-temperature operating ice machine 11 is connected to the liquid phase inlet of the carbon dioxide liquefier 8 via a liquid ammonia storage tank 10. In the present invention, the cooling medium in the carbon dioxide liquefier 8 is liquid ammonia. The liquid ammonia absorbs the heat of the carbon dioxide and evaporates into gaseous ammonia. The gaseous ammonia is then cooled by the low-temperature operating ice machine 11 to become liquid ammonia, which is then stored in the liquid ammonia storage tank 10 for standby use. When the liquid ammonia level in the carbon dioxide liquefier 8 is too low, the liquid ammonia can be replenished from the liquid ammonia storage tank 10.

[0038] Furthermore, it also includes a control unit, which includes a single-chip microcomputer 18. The signal input end of the single-chip microcomputer 18 is respectively connected to the first pressure transmitter 13, the second pressure transmitter 14, the first liquid level sensor 19, the second liquid level sensor 21 and the third liquid level sensor 24; the signal output end of the single-chip microcomputer 18 is respectively connected to the first regulating valve 15, the second regulating valve 16, the pressure reducing valve 17, the third regulating valve 20 and the fourth regulating valve 23. The first pressure transmitter 13 is arranged between the gas phase outlet of the dry ice pelletizer 4 and the cold end channel II of the supercooler 2; the second pressure transmitter 14 is arranged between the gas phase outlet of the first gas-liquid separator 3 and the cold end channel I of the supercooler 2; the third pressure transmitter 18 is arranged between the outlet of the compressor 6 and the hot end channel of the liquefied precooler 5; the first liquid level sensor 19 is arranged on the first gas-liquid separator 3, the second liquid level sensor 21 is arranged on the carbon dioxide liquefier 8, and the third liquid level sensor 24 is arranged on the second gas-liquid separator 9; the first regulating valve 1 5 is provided on the first pressure relief pipe 26 between the cold end channel II of the subcooler 2 and the cold end channel II of the liquefied precooler 5; the second regulating valve 16 is provided on the second pressure relief pipe 27 between the cold end channel I of the subcooler 2 and the cold end channel I of the liquefied precooler 5; the pressure reducing valve 17 is provided between the hot end channel of the subcooler 2 and the first gas-liquid separator 3; the third regulating valve 20 is provided between the liquid ammonia storage tank 10 and the liquid phase inlet of the carbon dioxide liquefier 8; and the fourth regulating valve 23 is provided between the liquid phase outlet of the second gas-liquid separator 9 and the liquid carbon dioxide storage tank 1.

[0039] A method for producing dry ice using a device for reducing carbon dioxide loss comprises the following steps:

[0040] Step 1: Liquid carbon dioxide in the carbon dioxide storage tank 1 is transported via a pipeline to the hot end channel of the subcooler 2 for heat exchange with low-temperature carbon dioxide gas from the first gas-liquid separator 3 and the dry ice pelletizer 4 to reduce the temperature of the liquid carbon dioxide to -24.6°C. The pressure of the liquid carbon dioxide in the carbon dioxide storage tank 1 is 1.96 MPa and the temperature is -20°C.

[0041] Step 2: The cooled liquid carbon dioxide is throttled and decompressed to 0.6 MPa through the pressure reducing valve 17, and the temperature is further reduced to -52°C. The throttled liquid carbon dioxide enters the first gas-liquid separator 3 to separate part of the gas generated during the throttling process, and is then transported to the dry ice pelletizer 4 through a pipeline for pelletization;

[0042] Step 3: The gaseous carbon dioxide generated by the first gas-liquid separator 3 enters the cold end channel I of the subcooler 2 through the gas phase outlet of the first gas-liquid separator 3, and the gaseous carbon dioxide generated by the dry ice pelletizer 4 enters the cold end channel II of the subcooler 2 through the gas phase outlet of the ice pelletizer 4. After the two streams of gaseous carbon dioxide cool the liquid phase carbon dioxide in step 1, they themselves reheat. The gaseous carbon dioxide generated by the first gas-liquid separator 3 has a temperature of -52°C and a pressure of 0.6 MPa. The gaseous carbon dioxide generated by the dry ice pelletizer 4 has a temperature of -65°C and a pressure of 0.2 MPa. The temperature of the gaseous carbon dioxide after reheating is -23°C.

[0043] Step 4: The reheated gaseous carbon dioxide at the outlet of the cold end channel I of the subcooler 2 enters the secondary inlet of the compressor 6 through the second pressure relief pipe 27 and the cold end channel I of the liquefied precooler 5; the reheated gaseous carbon dioxide at the outlet of the cold end channel II of the subcooler 2 enters the primary inlet of the compressor 6 through the first pressure relief pipe 26, the cold end channel II of the liquefied precooler 5 and the buffer 7; the pressure of the gaseous carbon dioxide entering the buffer 7 is 0.2 MPa and the temperature is 35°C; the pressure of the gaseous carbon dioxide entering the secondary inlet of the compressor 6 is 0.6 MPa and the temperature is 35°C; the pressure of the gas after compression by the compressor 6 is 2.3 MPa and the temperature is 40°C;

[0044] Step 5: The gas compressed by the compressor 6 is pre-cooled through the hot end channel of the liquefied pre-cooler 5 and then transported to the built-in coil 22 of the carbon dioxide liquefier 8 for liquefaction. The temperature of the carbon dioxide gas after pre-cooling through the hot end channel of the liquefied pre-cooler 5 is -8°C, and the temperature of the carbon dioxide after liquefaction in the built-in coil 22 is -24°C.

[0045] Step 6: The liquefied carbon dioxide enters the second gas-liquid separator 9 for gas-liquid separation, and the liquid phase after gas-liquid separation is connected to the carbon dioxide storage tank 1;

[0046] Step 7: The liquid carbon dioxide production device 12 is connected to the carbon dioxide storage tank 1;

[0047] Step 8: The first liquid level sensor 19 is used to monitor the liquid level in the first gas-liquid separator 3. By maintaining the liquid level stable, the dry ice pelletizer can be stably and continuously fed with liquid, thereby improving the pellet yield. When the liquid level in the first gas-liquid separator 3 is too high, the single-chip microcomputer 18 controls the pressure reducing valve 17 to reduce its opening, thereby increasing the amount of carbon dioxide gasified and reducing the liquid level in the first gas-liquid separator 3.

[0048] When the liquid level of the first gas-liquid separator 3 is too low, the single chip microcomputer 18 controls the pressure reducing valve 17 to increase its opening, thereby reducing the amount of carbon dioxide gasification and increasing the liquid level of the first gas-liquid separator 3;

[0049] Step 9: The second pressure transmitter 14 is used to monitor the gas pressure entering the cold end channel I of the subcooler 2. When the pressure exceeds a given process index, the single chip microcomputer 18 controls the second regulating valve 16 to release the pressure;

[0050] Step 10: The first pressure transmitter 13 is used to monitor the pressure of the gas entering the cold end channel II of the subcooler 2. When the pressure exceeds a given process index, the single chip microcomputer 18 controls the first regulating valve 15 to release the pressure.

[0051] Step 11: The second liquid level sensor 21 is used to monitor the liquid level of liquid ammonia in the carbon dioxide liquefier 8. By maintaining the liquid level stable, the gaseous carbon dioxide can be fully liquefied, thereby improving the recovery rate of the released gaseous carbon dioxide. When the liquid level is too low, the single-chip microcomputer 18 controls the opening of the third regulating valve 20 to increase to balance the liquid level of the carbon dioxide liquefier 8. When the liquid level is too high, the single-chip microcomputer 18 controls the opening of the third regulating valve 20 to decrease to adjust the liquid level of the carbon dioxide liquefier 8.

[0052] Step 12: The third liquid level sensor 24 is used to monitor the liquid level of the liquid carbon dioxide. The single chip microcomputer 18 adjusts the liquid level in the second gas-liquid separator 9 by controlling the opening of the fourth regulating valve 23 .

[0053] The present invention is mainly used for the production of dry ice. By arranging a supercooler 2 and a pressure reducing valve 17, it is possible to pre-cool the liquid carbon dioxide and separate it into gas and liquid in the first gas-liquid separator 3, so as to achieve the purpose of improving the dry ice preparation efficiency and reducing the workload of the dry ice granulator 4. Furthermore, the present invention recovers the gas in the first gas-liquid separator 3 and the dry ice granulator 4 to reduce the loss of raw materials. After collecting the above-mentioned gas phase, the carbon dioxide gas is reheated and compressed twice and liquefied to achieve the purpose of recycling and reusing the carbon dioxide lost in the production process; further, the above-mentioned two reheatings can achieve pre-cooling of the corresponding raw materials to achieve the purpose of reducing the cooling capacity; at the same time, the present invention preferably adopts a single-chip microcomputer 18 for automatic control to ensure the long-term stable operation of the system.

[0054] In order to explain the present invention in more detail, the present invention will be further described in conjunction with the embodiments. The specific embodiments are as follows:

[0055] Example 1

[0056] A dry ice production device for reducing carbon dioxide loss includes a liquid carbon dioxide production device 12, a liquid carbon dioxide storage tank 1 connected to the liquid carbon dioxide production device 12, and a dry ice pelletizer 4. The liquid carbon dioxide storage tank 1 is connected to the dry ice pelletizer 4 through a pre-cooling separation unit. The gas phase outlet of the pre-cooling separation unit and the dry ice pelletizer 4 is connected to the liquid carbon dioxide storage tank 1 through a gas phase recovery unit; the gas phase recovery unit includes a liquefaction pre-cooling unit connected to the gas phase outlet of the pre-cooling separation unit and the dry ice pelletizer 4, and a gas compression unit connected in turn to the liquefaction pre-cooling unit. element and gas liquefaction unit; the pre-cooling separation unit includes a subcooler 2 connected to the liquid carbon dioxide storage tank 1, the hot end channel of the subcooler 2 is connected to the first gas-liquid separator 3, and the liquid phase outlet of the first gas-liquid separator 3 is connected to the dry ice pelletizer 4; the gas phase outlet of the pre-cooling separation unit is the gas phase outlet of the first gas-liquid separator 3, and the gas phase outlet of the first gas-liquid separator 3 is connected to the liquefaction pre-cooling unit through the cold end channel I of the subcooler 2; the gas phase outlet of the dry ice pelletizer 4 is connected to the liquefaction pre-cooling unit through the cold end channel II of the subcooler 2; the liquefaction pre-cooling unit is the liquefaction pre-cooling unit. The cold end channel I of the subcooler 2 is connected to the gas compression unit through the cold end channel I of the liquefied precooler 5, and the cold end channel II of the subcooler 2 is connected to the gas compression unit through the cold end channel II of the liquefied precooler 5; the gas compression unit includes a compressor 6 and a buffer 7, the inlet of the buffer 7 is connected to the outlet of the cold end channel II of the liquefied precooler 5, the outlet of the buffer 7 is connected to the first-level inlet of the compressor 6, the outlet of the cold end channel I of the liquefied precooler 5 is connected to the second-level inlet of the compressor 6, and the outlet of the compressor 6 is connected to the gas liquefied precooler through the hot end channel of the liquefied precooler 5. The gas liquefaction unit includes a carbon dioxide liquefier 8 with a built-in coil 22, the inlet of the coil 22 is connected to the outlet of the hot end channel of the liquefied precooler 5, the outlet of the coil 22 is connected to the second gas-liquid separator 9, and the liquid phase outlet of the second gas-liquid separator 9 is connected to the liquid carbon dioxide storage tank 1; the subcooler 2 and the liquefied precooler 5 are both plate-fin heat exchangers; the gas phase outlet of the carbon dioxide liquefier 8 is connected to the inlet of the low-temperature working condition ice machine 11, and the outlet of the low-temperature working condition ice machine 11 is connected to the liquid phase inlet of the carbon dioxide liquefier 8 through the liquid ammonia storage tank 10.

[0057] A method for producing dry ice using a device for reducing carbon dioxide loss comprises the following steps:

[0058] Step 1: Liquid carbon dioxide in the carbon dioxide storage tank 1 is transported via a pipeline to the hot end channel of the subcooler 2 for heat exchange with low-temperature carbon dioxide gas from the first gas-liquid separator 3 and the dry ice pelletizer 4 to reduce the temperature of the liquid carbon dioxide to -24.6°C. The pressure of the liquid carbon dioxide in the carbon dioxide storage tank 1 is 1.96 MPa and the temperature is -20°C.

[0059] Step 2: The cooled liquid carbon dioxide is throttled and decompressed to 0.6 MPa through the pressure reducing valve 17, and the temperature is further reduced to -52°C. The throttled liquid carbon dioxide enters the first gas-liquid separator 3 to separate part of the gas generated during the throttling process, and is then transported to the dry ice pelletizer 4 through a pipeline for pelletization;

[0060] Step 3: The gaseous carbon dioxide generated by the first gas-liquid separator 3 enters the cold end channel I of the subcooler 2 through the gas phase outlet of the first gas-liquid separator 3, and the gaseous carbon dioxide generated by the dry ice pelletizer 4 enters the cold end channel II of the subcooler 2 through the gas phase outlet of the ice pelletizer 4. After the two streams of gaseous carbon dioxide cool the liquid phase carbon dioxide in step 1, they themselves reheat. The gaseous carbon dioxide generated by the first gas-liquid separator 3 has a temperature of -52°C and a pressure of 0.6 MPa. The gaseous carbon dioxide generated by the dry ice pelletizer 4 has a temperature of -65°C and a pressure of 0.2 MPa. The temperature of the gaseous carbon dioxide after reheating is -23°C.

[0061] Step 4: The reheated gaseous carbon dioxide at the outlet of the cold end channel I of the subcooler 2 enters the secondary inlet of the compressor 6 through the second pressure relief pipe 27 and the cold end channel I of the liquefied precooler 5; the reheated gaseous carbon dioxide at the outlet of the cold end channel II of the subcooler 2 enters the primary inlet of the compressor 6 through the first pressure relief pipe 26, the cold end channel II of the liquefied precooler 5 and the buffer 7; the pressure of the gaseous carbon dioxide entering the buffer 7 is 0.2 MPa and the temperature is 35°C; the pressure of the gaseous carbon dioxide entering the secondary inlet of the compressor 6 is 0.6 MPa and the temperature is 35°C; the pressure of the gas after compression by the compressor 6 is 2.3 MPa and the temperature is 40°C;

[0062] Step 5: The gas compressed by the compressor 6 is pre-cooled through the hot end channel of the liquefied pre-cooler 5 and then transported to the built-in coil 22 of the carbon dioxide liquefier 8 for liquefaction. The temperature of the carbon dioxide gas after pre-cooling through the hot end channel of the liquefied pre-cooler 5 is -8°C, and the temperature of the carbon dioxide after liquefaction in the built-in coil 22 is -24°C.

[0063] Step 6: The liquefied carbon dioxide enters the second gas-liquid separator 9 for gas-liquid separation, and the liquid phase after gas-liquid separation is connected to the carbon dioxide storage tank 1;

[0064] Step 7: The liquid carbon dioxide production device 12 is connected to the carbon dioxide storage tank 1.

[0065] Example 2

[0066] A dry ice production device for reducing carbon dioxide loss, comprising a liquid carbon dioxide production device 12, a liquid carbon dioxide storage tank 1 connected to the liquid carbon dioxide production device 12, and a dry ice pelletizer 4, wherein the liquid carbon dioxide storage tank 1 is connected to the dry ice pelletizer 4 via a pre-cooling separation unit, and the gas phase outlet of the pre-cooling separation unit and the dry ice pelletizer 4 is connected to the liquid carbon dioxide storage tank 1 via a gas phase recovery unit; the gas phase recovery unit comprises a liquefaction pre-cooling unit connected to the gas phase outlet of the pre-cooling separation unit and the dry ice pelletizer 4, and a gas compression unit and a gas liquefaction unit connected to the liquefaction pre-cooling unit in sequence; the pre-cooling separation unit comprises a supercooling unit connected to the liquid carbon dioxide storage tank 1 2, the hot end channel of the supercooler 2 is connected to the first gas-liquid separator 3, and the liquid phase outlet of the first gas-liquid separator 3 is connected to the dry ice granulator 4; the gas phase outlet of the pre-cooling separation unit is the gas phase outlet of the first gas-liquid separator 3, and the gas phase outlet of the first gas-liquid separator 3 is connected to the liquefaction pre-cooling unit through the cold end channel I of the supercooler 2; the gas phase outlet of the dry ice granulator 4 is connected to the liquefaction pre-cooling unit through the cold end channel II of the supercooler 2; the liquefaction pre-cooling unit is the liquefaction pre-cooling unit 5, the cold end channel I of the supercooler 2 is connected to the gas compression unit through the cold end channel I of the liquefaction pre-cooler 5, and the cold end channel II of the supercooler 2 is connected to the gas compression unit through the cold end channel II of the liquefaction pre-cooler 5 connected; the gas compression unit includes a compressor 6 and a buffer 7, the inlet of the buffer 7 is connected to the outlet of the cold end channel II of the liquefied precooler 5, the outlet of the buffer 7 is connected to the first-level inlet of the compressor 6, the outlet of the cold end channel I of the liquefied precooler 5 is connected to the secondary inlet of the compressor 6, and the outlet of the compressor 6 is connected to the gas liquefaction unit through the hot end channel of the liquefied precooler 5; the gas liquefaction unit includes a carbon dioxide liquefier 8 with a built-in coil 22, the inlet of the coil 22 is connected to the outlet of the hot end channel of the liquefied precooler 5, the outlet of the coil 22 is connected to the second gas-liquid separator 9, and the liquid phase outlet of the second gas-liquid separator 9 is connected to the liquid carbon dioxide storage tank 1; the The subcooler 2 and the liquefaction precooler 5 are both plate-fin heat exchangers; the gas phase outlet of the carbon dioxide liquefier 8 is connected to the inlet of the low-temperature working condition ice machine 11, and the outlet of the low-temperature working condition ice machine 11 is connected to the liquid phase inlet of the carbon dioxide liquefier 8 through the liquid ammonia storage tank 10; it also includes a control unit, which includes a single-chip microcomputer 18, and the signal input end of the single-chip microcomputer 18 is respectively connected to the first pressure transmitter 13, the second pressure transmitter 14, the first liquid level sensor 19, the second liquid level sensor 21 and the third liquid level sensor 24; the signal output end of the single-chip microcomputer 18 is respectively connected to the first regulating valve 15, the second regulating valve 16, the pressure reducing valve 17, the third regulating valve 20 and the fourth regulating valve 23.The first pressure transmitter 13 is arranged between the gas phase outlet of the dry ice pelletizer 4 and the cold end channel II of the supercooler 2; the second pressure transmitter 14 is arranged between the gas phase outlet of the first gas-liquid separator 3 and the cold end channel I of the supercooler 2; the third pressure transmitter 18 is arranged between the outlet of the compressor 6 and the hot end channel of the liquefied precooler 5; the first liquid level sensor 19 is arranged on the first gas-liquid separator 3, the second liquid level sensor 21 is arranged on the carbon dioxide liquefier 8, and the third liquid level sensor 24 is arranged on the second gas-liquid separator 9; the first regulating valve 1 5 is provided on the first pressure relief pipe 26 between the cold end channel II of the subcooler 2 and the cold end channel II of the liquefied precooler 5; the second regulating valve 16 is provided on the second pressure relief pipe 27 between the cold end channel I of the subcooler 2 and the cold end channel I of the liquefied precooler 5; the pressure reducing valve 17 is provided between the hot end channel of the subcooler 2 and the first gas-liquid separator 3; the third regulating valve 20 is provided between the liquid ammonia storage tank 10 and the liquid phase inlet of the carbon dioxide liquefier 8; and the fourth regulating valve 23 is provided between the liquid phase outlet of the second gas-liquid separator 9 and the liquid carbon dioxide storage tank 1.

[0067] A method for producing dry ice using a device for reducing carbon dioxide loss comprises the following steps:

[0068] Step 1: Liquid carbon dioxide in the carbon dioxide storage tank 1 is transported via a pipeline to the hot end channel of the subcooler 2 for heat exchange with low-temperature carbon dioxide gas from the first gas-liquid separator 3 and the dry ice pelletizer 4 to reduce the temperature of the liquid carbon dioxide to -24.6°C. The pressure of the liquid carbon dioxide in the carbon dioxide storage tank 1 is 1.96 MPa and the temperature is -20°C.

[0069] Step 2: The cooled liquid carbon dioxide is throttled and decompressed to 0.6 MPa through the pressure reducing valve 17, and the temperature is further reduced to -52°C. The throttled liquid carbon dioxide enters the first gas-liquid separator 3 to separate part of the gas generated during the throttling process, and is then transported to the dry ice pelletizer 4 through a pipeline for pelletization;

[0070] Step 3: The gaseous carbon dioxide generated by the first gas-liquid separator 3 enters the cold end channel I of the subcooler 2 through the gas phase outlet of the first gas-liquid separator 3, and the gaseous carbon dioxide generated by the dry ice pelletizer 4 enters the cold end channel II of the subcooler 2 through the gas phase outlet of the ice pelletizer 4. After the two streams of gaseous carbon dioxide cool the liquid phase carbon dioxide in step 1, they themselves reheat. The gaseous carbon dioxide generated by the first gas-liquid separator 3 has a temperature of -52°C and a pressure of 0.6 MPa. The gaseous carbon dioxide generated by the dry ice pelletizer 4 has a temperature of -65°C and a pressure of 0.2 MPa. The temperature of the gaseous carbon dioxide after reheating is -23°C.

[0071] Step 4: The reheated gaseous carbon dioxide at the outlet of the cold end channel I of the subcooler 2 enters the secondary inlet of the compressor 6 through the second pressure relief pipe 27 and the cold end channel I of the liquefied precooler 5; the reheated gaseous carbon dioxide at the outlet of the cold end channel II of the subcooler 2 enters the primary inlet of the compressor 6 through the first pressure relief pipe 26, the cold end channel II of the liquefied precooler 5 and the buffer 7; the pressure of the gaseous carbon dioxide entering the buffer 7 is 0.2 MPa and the temperature is 35°C; the pressure of the gaseous carbon dioxide entering the secondary inlet of the compressor 6 is 0.6 MPa and the temperature is 35°C; the pressure of the gas after compression by the compressor 6 is 2.3 MPa and the temperature is 40°C;

[0072] Step 5: The gas compressed by the compressor 6 is pre-cooled through the hot end channel of the liquefied pre-cooler 5 and then transported to the built-in coil 22 of the carbon dioxide liquefier 8 for liquefaction. The temperature of the carbon dioxide gas after pre-cooling through the hot end channel of the liquefied pre-cooler 5 is -8°C, and the temperature of the carbon dioxide after liquefaction in the built-in coil 22 is -24°C.

[0073] Step 6: The liquefied carbon dioxide enters the second gas-liquid separator 9 for gas-liquid separation, and the liquid phase after gas-liquid separation is connected to the carbon dioxide storage tank 1;

[0074] Step 7: The liquid carbon dioxide production device 12 is connected to the carbon dioxide storage tank 1;

[0075] Step 8: The first liquid level sensor 19 is used to monitor the liquid level in the first gas-liquid separator 3. By maintaining the liquid level stable, the dry ice pelletizer can be stably and continuously fed with liquid, thereby improving the pellet yield. When the liquid level in the first gas-liquid separator 3 is too high, the single-chip microcomputer 18 controls the pressure reducing valve 17 to reduce its opening, thereby increasing the amount of carbon dioxide gasified and reducing the liquid level in the first gas-liquid separator 3.

[0076] When the liquid level of the first gas-liquid separator 3 is too low, the single chip microcomputer 18 controls the pressure reducing valve 17 to increase its opening, thereby reducing the amount of carbon dioxide gasification and increasing the liquid level of the first gas-liquid separator 3;

[0077] Step 9: The second pressure transmitter 14 is used to monitor the gas pressure entering the cold end channel I of the subcooler 2. When the pressure exceeds a given process index, the single chip microcomputer 18 controls the second regulating valve 16 to release the pressure;

[0078] Step 10: The first pressure transmitter 13 is used to monitor the pressure of the gas entering the cold end channel II of the subcooler 2. When the pressure exceeds a given process index, the single chip microcomputer 18 controls the first regulating valve 15 to release the pressure.

[0079] Step 11: The second liquid level sensor 21 is used to monitor the liquid level of liquid ammonia in the carbon dioxide liquefier 8. By maintaining the liquid level stable, the gaseous carbon dioxide can be fully liquefied, thereby improving the recovery rate of the released gaseous carbon dioxide. When the liquid level is too low, the single-chip microcomputer 18 controls the opening of the third regulating valve 20 to increase to balance the liquid level of the carbon dioxide liquefier 8. When the liquid level is too high, the single-chip microcomputer 18 controls the opening of the third regulating valve 20 to decrease to adjust the liquid level of the carbon dioxide liquefier 8.

[0080] Step 12: The third liquid level sensor 24 is used to monitor the liquid level of the liquid carbon dioxide. The single chip microcomputer 18 adjusts the liquid level in the second gas-liquid separator 9 by controlling the opening of the fourth regulating valve 23 .

[0081] Taking the above-mentioned embodiment 2 as an example, dry ice is prepared using existing equipment, that is, a liquid carbon dioxide production device 12 connected to a dry ice pelletizer 4, with a liquid carbon dioxide consumption of 3.2 tons per ton of dry ice, and a failure rate of about 30% in the dry ice pelletizer 4 due to carbon dioxide gasification, and a whole-machine working efficiency of 50% (the whole-machine working efficiency means that a dry ice pelletizer 4 with a capacity of 1 ton / h needs to be used for 2 hours to produce 1 ton of dry ice); dry ice is prepared using a liquid carbon dioxide production device 12, a supercooler 2, and a first gas-liquid separator 3 connected to a dry ice pelletizer 4, with a liquid carbon dioxide consumption of 2.6 tons per ton of dry ice (the above-mentioned supercooler 2 is heat exchanged by other devices, and the liquid after heat exchange is 2.6 tons per ton of dry ice). The temperature of the liquid carbon dioxide is the same as the temperature of the liquid carbon dioxide after heat exchange in the embodiment), and the failure rate of the dry ice pelletizer 4 due to carbon dioxide gasification is 20%, and the working efficiency of the whole machine is 75%; by using the process method of the present invention to prepare dry ice, the liquid carbon dioxide consumption is 1.4 tons / ton of dry ice, and the failure rate of the dry ice pelletizer 4 is 5% due to less gasified carbon dioxide, and the working efficiency of the whole machine is 98%; by using the device and process of the present invention, the working efficiency of the equipment can be greatly improved, and the carbon dioxide concentration in and around the production plant can be reduced, thereby protecting the health of production operators and complying with the concepts of energy saving, consumption reduction, low carbon and environmental protection.

[0082] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A dry ice production device for reducing carbon dioxide loss, comprising a liquid carbon dioxide production device (12), a liquid carbon dioxide storage tank (1) connected to the liquid carbon dioxide production device (12), and a dry ice pelletizer (4), characterized in that: The liquid carbon dioxide storage tank (1) is connected to the dry ice pelletizer (4) via a pre-cooling separation unit. The gas phase outlets of the pre-cooling separation unit and the dry ice pelletizer (4) are connected to the liquid carbon dioxide storage tank (1) via a gas phase recovery unit; The gas phase recovery unit includes a liquefaction precooling unit connected to the precooling separation unit and the gas phase outlet of the dry ice pelletizer (4), and a gas compression unit and a gas liquefaction unit connected to the liquefaction precooling unit in sequence; The pre-cooling separation unit comprises a subcooler (2) connected to a liquid carbon dioxide storage tank (1), a hot end channel of the subcooler (2) is connected to a first gas-liquid separator (3), and a liquid phase outlet of the first gas-liquid separator (3) is connected to a dry ice granulator (4); The gas phase outlet of the pre-cooling separation unit is the gas phase outlet of the first gas-liquid separator (3), and the gas phase outlet of the first gas-liquid separator (3) is connected to the liquefaction pre-cooling unit through the cold end channel I of the subcooler (2); The gas phase outlet of the dry ice pelletizer (4) is connected to the liquefaction pre-cooling unit through the cold end channel II of the supercooler (2); The liquefaction precooling unit is a liquefaction precooler (5), the cold end channel I of the subcooler (2) is connected to the gas compression unit through the cold end channel I of the liquefaction precooler (5), and the cold end channel II of the subcooler (2) is connected to the gas compression unit through the cold end channel II of the liquefaction precooler (5); The gas compression unit comprises a compressor (6) and a buffer (7), the inlet of the buffer (7) is connected to the outlet of the cold end channel II of the liquefied precooler (5), the outlet of the buffer (7) is connected to the primary inlet of the compressor (6), the outlet of the cold end channel I of the liquefied precooler (5) is connected to the secondary inlet of the compressor (6), and the outlet of the compressor (6) is connected to the gas liquefaction unit through the hot end channel of the liquefied precooler (5); The gas liquefaction unit comprises a carbon dioxide liquefier (8) with a built-in coil (22), the inlet of the coil (22) is connected to the outlet of the hot end channel of the liquefied precooler (5), the outlet of the coil (22) is connected to the second gas-liquid separator (9), and the liquid phase outlet of the second gas-liquid separator (9) is connected to the liquid carbon dioxide storage tank (1); The control unit also includes a single chip microcomputer (18), wherein the signal input end of the single chip microcomputer (18) is respectively connected to the first pressure transmitter (13), the second pressure transmitter (14), the first liquid level sensor (19), the second liquid level sensor (21), and the third liquid level sensor (24); and the signal output end of the single chip microcomputer (18) is respectively connected to the first regulating valve (15), the second regulating valve (16), the pressure reducing valve (17), the third regulating valve (20), and the fourth regulating valve (23).

2. The dry ice production device for reducing carbon dioxide loss according to claim 1, Its characteristics are: The subcooler (2) and the liquefaction precooler (5) are both plate-fin heat exchangers.

3. The dry ice production device for reducing carbon dioxide loss according to claim 1, Its characteristics are: The gas phase outlet of the carbon dioxide liquefier (8) is connected to the inlet of the low-temperature working condition ice machine (11), and the outlet of the low-temperature working condition ice machine (11) is connected to the liquid phase inlet of the carbon dioxide liquefier (8) through the liquid ammonia storage tank (10).

4. The dry ice production device for reducing carbon dioxide loss according to claim 1, Its characteristics are: The first pressure transmitter (13) is arranged between the gas phase outlet of the dry ice pelletizer (4) and the cold end channel II of the supercooler (2); The second pressure transmitter (14) is arranged between the gas phase outlet of the first gas-liquid separator (3) and the cold end channel I of the subcooler (2); The first liquid level sensor (19) is arranged on the first gas-liquid separator (3), the second liquid level sensor (21) is arranged on the carbon dioxide liquefier (8), and the third liquid level sensor (24) is arranged on the second gas-liquid separator (9); The first regulating valve (15) is arranged on the first pressure relief pipe (26) between the cold end channel II of the subcooler (2) and the cold end channel II of the liquefaction precooler (5); The second regulating valve (16) is arranged on the second pressure relief pipe (27) between the cold end channel I of the subcooler (2) and the cold end channel I of the liquefaction precooler (5); The pressure reducing valve (17) is arranged between the hot end channel of the subcooler (2) and the first gas-liquid separator (3); The third regulating valve (20) is arranged between the liquid ammonia storage tank (10) and the liquid phase inlet of the carbon dioxide liquefier (8); The fourth regulating valve (23) is arranged between the liquid phase outlet of the second gas-liquid separator (9) and the liquid carbon dioxide storage tank (1).

5. A method for producing dry ice using the device for reducing carbon dioxide loss according to any one of claims 1 to 4, characterized in that: The production method comprises the following steps: Step 1: Liquid carbon dioxide in the carbon dioxide storage tank (1) is transported to the hot end channel of the supercooler (2) through a pipeline to exchange heat with low-temperature carbon dioxide gas from the first gas-liquid separator (3) and the dry ice pelletizer (4) to reduce the temperature of the liquid carbon dioxide to -24.6°C; the pressure of the liquid carbon dioxide in the carbon dioxide storage tank (1) is: 1.96MPa, and the temperature is: -20°C; Step 2: The cooled liquid carbon dioxide is throttled and decompressed to 0.6 MPa through a pressure reducing valve (17), and the temperature is further reduced to -52°C. The throttled liquid carbon dioxide enters a first gas-liquid separator (3) to separate part of the gas generated during the throttling process, and is then transported to a dry ice pelletizer (4) through a pipeline for pelletization; Step 3: The gaseous carbon dioxide generated by the first gas-liquid separator (3) enters the cold end channel I of the supercooler (2) through the gas phase outlet of the first gas-liquid separator (3), and the gaseous carbon dioxide generated by the dry ice granulator (4) enters the cold end channel II of the supercooler (2) through the gas phase outlet of the ice granulator (4); after the two streams of gaseous carbon dioxide cool the liquid phase carbon dioxide in step 1, they themselves reheat; the gaseous carbon dioxide generated by the first gas-liquid separator (3) has a temperature of -52°C and a pressure of 0.6 MPa; the gaseous carbon dioxide generated by the dry ice granulator (4) has a temperature of -65°C and a pressure of 0.2 MPa, and the temperature of the gaseous carbon dioxide after reheating is -23°C; Step 4: The gaseous carbon dioxide after reheating at the outlet of the cold end channel I of the subcooler (2) enters the secondary inlet of the compressor (6) through the second pressure relief pipe (27) and the cold end channel I of the liquefied precooler (5); the gaseous carbon dioxide after reheating at the outlet of the cold end channel II of the subcooler (2) enters the primary inlet of the compressor (6) through the first pressure relief pipe (26), the cold end channel II of the liquefied precooler (5) and the buffer (7); the pressure of the gaseous carbon dioxide entering the buffer (7) is 0.2 MPa and the temperature is 35°C; the pressure of the gaseous carbon dioxide entering the secondary inlet of the compressor (6) is 0.6 MPa and the temperature is 35°C; the pressure of the gas after being compressed by the compressor (6) is 2.3 MPa and the temperature is 40°C; Step 5: The gas compressed by the compressor (6) passes through the liquefied precooler (5) After being pre-cooled in the hot end channel, the carbon dioxide is transported to the built-in coil (22) of the carbon dioxide liquefier (8) for liquefaction; the temperature of the carbon dioxide gas after being pre-cooled in the hot end channel of the liquefaction precooler 5 is: -8°C, and the temperature of the carbon dioxide after being liquefied in the built-in coil (22) is: -24°C; Step 6: The liquefied carbon dioxide enters the second gas-liquid separator (9) for gas-liquid separation, and the liquid phase after gas-liquid separation is connected to the carbon dioxide storage tank (1); Step 7: The liquid carbon dioxide production device (12) is connected to the carbon dioxide storage tank (1); Step 8: The first liquid level sensor (19) is used to monitor the liquid level in the first gas-liquid separator (3). By maintaining the stability of the liquid level, the dry ice pelletizer can be ensured to be able to stably and continuously feed liquid, thereby improving the pellet yield. When the liquid level in the first gas-liquid separator (3) is too high, the single chip microcomputer (18) controls the pressure reducing valve (17) to reduce the opening, thereby increasing the amount of carbon dioxide gasification and reducing the liquid level in the first gas-liquid separator (3). When the liquid level of the first gas-liquid separator (3) is too low, the single chip microcomputer (18) controls the pressure reducing valve (17) to increase its opening, thereby reducing the amount of carbon dioxide gasification and increasing the liquid level of the first gas-liquid separator (3); Step 9: The second pressure transmitter (14) is used to monitor the gas pressure entering the cold end channel I of the subcooler (2). When the pressure exceeds a given process index, the single chip microcomputer (18) controls the second regulating valve (16) to release the pressure. Step 10: The first pressure transmitter (13) is used to monitor the pressure of the gas entering the cold end channel II of the subcooler (2). When the pressure exceeds a given process index, the single chip microcomputer (18) controls the first regulating valve (15) to release the pressure. Step 11: The second liquid level sensor (21) is used to monitor the liquid level of liquid ammonia in the carbon dioxide liquefier (8). By maintaining the stability of the liquid level, the gaseous carbon dioxide can be fully liquefied, thereby improving the recovery rate of the expelled gaseous carbon dioxide; when the liquid level is too low, the single chip microcomputer (18) controls the opening of the third regulating valve (20) to increase, so as to balance the liquid level of the carbon dioxide liquefier (8); when the liquid level is too high, the single chip microcomputer (18) controls the opening of the third regulating valve (20) to decrease, so as to adjust the liquid level of the carbon dioxide liquefier (8); Step 12: The third liquid level sensor (24) is used to monitor the liquid level of the liquid carbon dioxide, and the single chip microcomputer (18) adjusts the liquid level in the second gas-liquid separator (9) by controlling the opening of the fourth regulating valve (23).

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