Dry ice tail gas recovery device and dry ice manufacturing machine

Abstract

The utility model provides a dry ice tail gas recovery device and a dry ice making machine. The dry ice tail gas recovery device comprises a heat exchanger, a dryer, a first compressor, a first cooler, a second compressor, a second cooler, a mixer, a third compressor, a third cooler, a heat exchanger, a throttle valve, a separation device and a pressure pump, the heat exchanger is used for introducing dry ice tail gas, and the pressure pump is used for conveying the separated liquid carbon dioxide into the liquid carbon dioxide storage tank; and two ends of the first return pipeline are respectively connected with the separation device and the mixer. The recovery device can reduce cold loss, improve liquefaction proportion, increase liquefied carbon dioxide production efficiency and reduce backflow gas flow so as to reduce power consumption of the compressor, and is more energy-saving.

Description

Technical Field

[0001] The utility model relates to the technical field of carbon treatment, in particular to a dry ice tail gas recovery device and a dry ice making machine. Background Art

[0002] Dry ice is solid carbon dioxide, and its raw material is liquid carbon dioxide. During the production of dry ice by a dry ice machine, about 40% of the liquid carbon dioxide is converted into solid dry ice, and the remaining 60% is converted into carbon dioxide gas to form dry ice tail gas. The concentration of this part of gas is 99%, and the temperature is close to -70°C. This part of tail gas can be recycled by re-liquefying this part of gas. At present, there are two main schemes for liquefying dry ice tail gas: one is to cool the carbon dioxide gas with a pressure of about 2Mpa to below -20°C through an external refrigeration unit to achieve liquefaction; but the external refrigeration unit has a complex structure and requires regular addition of refrigerant. The other is to throttle and cool down the supercritical high-pressure (10-15Mpa) carbon dioxide for liquefaction; but the pressure resistance and overpressure protection requirements of the equipment are very high, and the temperature of the high-pressure carbon dioxide gas before throttling is limited by the cooling water temperature (generally above 20°C), resulting in a low liquefaction ratio after throttling, and a large amount of carbon dioxide gas that cannot be liquefied after throttling, thereby increasing the power consumption of the compressor. Utility Model Content

[0003] In view of this, the purpose of the present invention is to provide a dry ice tail gas recovery device and a dry ice making machine to solve the above problems.

[0004] The utility model adopts the following scheme:

[0005] The present application provides a dry ice tail gas recovery device, comprising a heat exchanger, a dryer, a first compressor, a first cooler, a second compressor, a second cooler, a mixer, a third compressor, a third cooler, the heat exchanger, a throttle valve, a separation device, and a pressure pump connected in sequence; the heat exchanger is used to receive the dry ice tail gas, and the pressure pump is used to transfer the separated liquid carbon dioxide to a liquid carbon dioxide storage tank; and also includes a first reflux pipeline, the two ends of which are respectively connected to the separation device and the mixer.

[0006] Furthermore, it also includes a first buffer bag and a second buffer bag connected to the first buffer bag; a second return pipeline, a third return pipeline, and a fourth return pipeline; the first buffer bag is connected between the dryer and the first compressor; one end of the second return pipeline, the third return pipeline, and the fourth return pipeline is connected to the second buffer bag, and the other ends are respectively connected between the first compressor and the first cooler, between the second compressor and the second cooler, and between the third compressor and the third cooler.

[0007] Furthermore, the first cooler, the second cooler and the third cooler are all water coolers.

[0008] Furthermore, a first one-way solenoid valve and a fan are provided between the first buffer bag and the second buffer bag; the first one-way solenoid valve is used to allow gas to flow to the second buffer bag; and the fan is used to allow gas to flow to the first buffer bag.

[0009] Furthermore, the second return pipeline is provided with a second one-way solenoid valve; the third return pipeline is provided with a third one-way solenoid valve; the fourth return pipeline is provided with a fourth one-way solenoid valve; pressure sensors are provided between the compressor and the second one-way solenoid valve, the third one-way solenoid valve, and the fourth one-way solenoid valve; the second one-way solenoid valve, the third one-way solenoid valve, and the fourth one-way solenoid valve are used to allow gas to flow to the second buffer bag.

[0010] Furthermore, the second buffer bag is provided with a pressure relief valve.

[0011] The present application also provides a dry ice making machine, including a liquid carbon dioxide storage tank and a dry ice machine connected to the liquid carbon dioxide storage tank, and also includes the dry ice tail gas recovery device; the heat exchanger is used to connect to the tail gas output end of the dry ice and the pressure pump is used to transfer the separated liquid carbon dioxide to the liquid carbon dioxide storage tank

[0012] By adopting the above technical solution, the utility model can achieve the following technical effects:

[0013] 1. The entire system only needs to operate in a subcritical state (7Mpa). Compared with existing technologies, this solution has lower requirements for system equipment and pipeline pressure, thereby reducing equipment costs.

[0014] 2. The low-temperature exhaust gas directly exchanges heat with the high-temperature carbon dioxide gas before throttling and enters the buffer bag for temporary storage. On the one hand, it can reduce the loss of cooling capacity; on the other hand, it can effectively improve the liquefaction ratio, increase the production efficiency of liquefied carbon dioxide, reduce the reflux gas flow, thereby reducing the power consumption of the compressor and saving more energy.

[0015] 3. A one-way solenoid valve is installed at the outlet of each compressor and a double buffer bag system is used. While controlling the pipeline pressure, the overflowed gas can be recycled to reduce waste. The double buffer bag structure can greatly avoid the buffer bag from rupturing due to pressure problems, and at the same time, it can ensure the continuous stability of the air supply to the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the implementation mode of the utility model, the drawings required for use in the implementation mode will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a schematic diagram of the structure of a dry ice making machine according to an embodiment of the utility model;

[0018] Icons: liquid carbon dioxide storage tank 1, dry ice machine 2, dryer 3, first buffer bag 4, second buffer bag 5, first one-way solenoid valve 6, pressure relief valve 7, fan 8, first compressor 9, second one-way solenoid valve 10, first cooler 11, second compressor 12, third one-way solenoid valve 13, second cooler 14, mixer 15, third compressor 16, fourth one-way solenoid valve 17, third cooler 18, heat exchanger 19, throttle valve 20, separation device 21, pressure pump 22. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the utility model clearer, the technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model. Therefore, the following detailed description of the embodiments of the utility model provided in the drawings is not intended to limit the scope of the utility model for which protection is sought, but merely represents the selected embodiments of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0020] Example

[0021] Combination Figure 1As shown, this embodiment provides a dry ice exhaust gas recovery device, including a heat exchanger 19, a dryer 3, a first compressor 9, a first cooler 11, a second compressor 12, a second cooler 14, a mixer 15, a third compressor 16, a third cooler 18, the heat exchanger 19, a throttle valve 20, a separation device 21, and a pressure pump 22 connected in sequence; the heat exchanger 19 is used to connect the dry ice exhaust gas, and the pressure pump 22 is used to transfer the separated liquid carbon dioxide to the liquid carbon dioxide storage tank 1; it also includes a first reflux pipeline, and the two ends of the first reflux pipeline are respectively connected to the separation device 21 and the mixer 15.

[0022] Specifically, in this embodiment, a dry ice making machine is taken as an example, which includes a liquid carbon dioxide storage tank 1 and a dry ice machine 2 connected to the liquid carbon dioxide storage tank 1, and also includes the dry ice tail gas recovery device; the heat exchanger 19 is used to access the tail gas output end of the dry ice and, the pressure pump 22 is used to transfer the separated liquid carbon dioxide to the liquid carbon dioxide storage tank 1; the cooler adopts a water cooler, and the first cooler 11, the second cooler 14 and the third cooler 18 correspond to the first water cooler, the second water cooler and the third water cooler respectively;

[0023] The liquid carbon dioxide storage tank 1 delivers liquid carbon dioxide to the dry ice machine 2. The dry ice machine 2 generates low-temperature tail gas at normal pressure (0.1Mpa, about -70°C) in the process of generating dry ice. This part of the low-temperature tail gas first exchanges heat with the high-pressure carbon dioxide gas (7Mpa, about 25°C) on the hot side of the heat exchanger 19 on the cold side. The tail gas temperature rises to about 20°C, and then passes through the dryer 3 to remove a small amount of moisture and enters the first buffer bag 4.

[0024] When the carbon dioxide gas in the first buffer bag 4 reaches a certain volume, it is sucked and compressed by the first compressor 9, and the temperature and pressure are increased. After being cooled to about 25°C by the first water cooler, it enters the second compressor 12 to further increase the pressure. The second water cooler cools the carbon dioxide gas to about 25°C again, and then mixes with part of the low-temperature carbon dioxide gas (2Mpa, about -19°C) separated by the separation device 21. The temperature of the mixed carbon dioxide gas is about 12°C, and then enters the third compressor 16 for compression, raising the pressure of the carbon dioxide gas to a subcritical state (about 7Mpa), and then is cooled to about 25°C by the third water cooler. , and then the low-temperature tail gas on the hot side and the cold side of the heat exchanger 19 is heat exchanged to further cool down (about 11°C). The subcritical carbon dioxide gas enters the throttle valve 20 for throttling. The pressure and temperature of the mixed stream after throttling are reduced (2Mpa, about -19.3°C). About 3 / 4 of the gas is liquefied, and 1 / 4 remains in the gas state. The gas-liquid separation is carried out through the separation device 21. The separated gas is mixed with the previous gas to reduce its temperature and reduce the power consumption of the compressor. The liquid carbon dioxide is again pressurized to 2.2Mpa (supercooled state) by the pressure pump 22 and enters the liquid carbon dioxide storage tank 1 for recycling.

[0025] In this embodiment, a first buffer bag and a second buffer bag connected to the first buffer bag 4 are also included; a pressure relief valve 7 is arranged on the second buffer bag 5; a second return pipeline, a third return pipeline, and a fourth return pipeline; the first buffer bag is connected between the dryer 3 and the first compressor 9; one end of the second return pipeline, the third return pipeline, and the fourth return pipeline are connected to the second buffer bag 5, and the other ends are respectively connected between the first compressor 9 and the first cooler 11, between the second compressor 12 and the second cooler 14, and between the third compressor 16 and the third cooler 18. A first one-way solenoid valve 6 and a fan 8 are arranged between the first buffer bag and the second buffer bag; the first one-way solenoid valve 6 is used to allow gas to flow to the second buffer bag; and the fan 8 is used to allow gas to flow to the first buffer bag 4. The second return pipeline is provided with a second one-way solenoid valve 10; the third return pipeline is provided with a third one-way solenoid valve 13; the fourth return pipeline is provided with a fourth one-way solenoid valve 17; pressure sensors are provided between the compressor and the second one-way solenoid valve 10, the third one-way solenoid valve 13, and the fourth one-way solenoid valve 17; the second one-way solenoid valve 10, the third one-way solenoid valve 13, and the fourth one-way solenoid valve 17 are used to allow gas to flow to the second buffer bag 5.

[0026] When the pressure in the pipeline exceeds the set value, the corresponding second one-way solenoid valve 10 opens to exhaust and release pressure, and the gas flows back into the second buffer bag 5. If the pressure in the first buffer bag 4 exceeds the safety value, the first one-way solenoid valve 6 opens and the fan 8 stops, and part of the gas is released to the second buffer bag 5 to keep the pressure level in the first buffer bag 4 stable. When the internal pressure of the first buffer bag 4 does not reach the safety point, the gas collected in the second buffer bag 5 can be transported to the first buffer bag 4 by the fan 8 and re-enter the recycling process without causing waste. When the pressure levels of the first buffer bag 4 and the second buffer bag 5 exceed the safety value, the pressure relief valve 7 at the top of the second buffer bag 5 opens to discharge gas to the outside to maintain the pressure safety and stability of the system.

[0027] The utility model provides a dry ice tail gas recovery device and a dry ice making machine. The dry ice tail gas recovery device is provided with multiple compressors, and the whole system only needs to operate in a subcritical state (7Mpa). Compared with the existing technology, the solution has lower requirements on system equipment and pipeline pressure, thereby reducing equipment cost; through the provision of double buffer bags, low-temperature tail gas directly exchanges heat with high-temperature carbon dioxide gas before throttling and then enters the buffer bag for temporary storage, which can reduce cooling loss on the one hand; on the other hand, it can effectively improve the liquefaction ratio, increase the production efficiency of liquefied carbon dioxide, reduce the reflux gas flow rate, thereby reducing the power consumption of the compressor, and is more energy-efficient; while controlling the pipeline pressure, the overflowed gas can be recycled to reduce waste; the structure of the double buffer bag can greatly avoid the rupture of the buffer bag due to pressure problems, and at the same time, can ensure the continuous stability of gas supply to the compressor.

[0028] The above are only preferred implementations of the present utility model. The protection scope of the present utility model is not limited to the above embodiments. All technical solutions under the concept of the present utility model belong to the protection scope of the present utility model.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0031] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

Claims

1. A dry ice tail gas recovery device, characterized in that: It includes a heat exchanger, a dryer, a first compressor, a first cooler, a second compressor, a second cooler, a mixer, a third compressor, a third cooler, the heat exchanger, a throttle valve, a separation device, and a pressure pump which are connected in sequence; the heat exchanger is used to receive dry ice tail gas, and the pressure pump is used to transfer the separated liquid carbon dioxide to a liquid carbon dioxide storage tank; it also includes a first reflux pipeline, and both ends of the first reflux pipeline are respectively connected to the separation device and the mixer.

2. The dry ice tail gas recovery device according to claim 1, characterized in that: It also includes a first buffer bag and a second buffer bag connected to the first buffer bag; a second return pipeline, a third return pipeline, and a fourth return pipeline; the first buffer bag is connected between the dryer and the first compressor; one end of the second return pipeline, the third return pipeline, and the fourth return pipeline is connected to the second buffer bag, and the other ends are respectively connected between the first compressor and the first cooler, between the second compressor and the second cooler, and between the third compressor and the third cooler.

3. The dry ice tail gas recovery device according to claim 1, characterized in that: The first cooler, the second cooler and the third cooler are all water coolers.

4. The dry ice tail gas recovery device according to claim 2, characterized in that: A first one-way solenoid valve and a fan are arranged between the first buffer bag and the second buffer bag; the first one-way solenoid valve is used to allow gas to flow to the second buffer bag; and the fan is used to allow gas to flow to the first buffer bag.

5. The dry ice tail gas recovery device according to claim 2, characterized in that: The second return pipeline is provided with a second one-way solenoid valve; the third return pipeline is provided with a third one-way solenoid valve; the fourth return pipeline is provided with a fourth one-way solenoid valve; pressure sensors are provided between the compressor and the second one-way solenoid valve, the third one-way solenoid valve, and the fourth one-way solenoid valve; the second one-way solenoid valve, the third one-way solenoid valve, and the fourth one-way solenoid valve are used to allow gas to flow to the second buffer bag.

6. The dry ice tail gas recovery device according to claim 2, characterized in that: The second buffer bag is provided with a pressure relief valve.

7. A dry ice making machine, comprising a liquid carbon dioxide storage tank and a dry ice machine connected to the liquid carbon dioxide storage tank, characterized in that: It also includes the dry ice exhaust gas recovery device according to any one of claims 1 to 6; the heat exchanger is used to connect to the exhaust gas output end of the dry ice, and the pressure pump is used to transfer the separated liquid carbon dioxide to the liquid carbon dioxide storage tank.

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