A recovery device and recovery method for carbon dioxide generated by lithium bicarbonate pyrolysis

Abstract

The application provides a recovery device and recovery method for carbon dioxide generated by lithium bicarbonate pyrolysis, the recovery device comprises a lithium bicarbonate pyrolysis kettle, a gas-liquid separator, a condenser, a first buffer tank, a carbon dioxide compressor and a second buffer tank are sequentially connected to the top of the lithium bicarbonate pyrolysis kettle, the outlet of the second buffer tank is connected to a lithium carbonate carbonization device, and the condenser is a demisting condenser. The recovery device is an integrated continuous system, carbon dioxide can be directly recycled to a lithium carbonate carbonization process after purification and compression, carbon resource closed loop circulation is realized, direct emission of carbon dioxide is avoided, external purchase of carbon dioxide is reduced, and efficient recycling of carbon resources is realized.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling technology and relates to a device and method for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. Background Technology

[0002] Lithium carbonate is a commonly used industrial inorganic compound used in ceramics, pharmaceuticals, and chemical catalysts. It is also a raw material for preparing cathode materials for lithium-ion batteries, possessing advantages such as high energy density, long lifespan, and good stability, and enjoys significant application prospects and market demand. Lithium bicarbonate pyrolysis is a common method for producing lithium carbonate. However, in existing lithium bicarbonate pyrolysis processes, the generated carbon dioxide and water vapor gas are directly emitted through exhaust fans. This carbon dioxide cannot be recovered, wasting resources and increasing carbon emissions. The lack of an efficient, continuous, and stable carbon dioxide recovery system fails to meet the requirements of green production. Summary of the Invention

[0003] The purpose of this invention is to provide a device and method for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. The recovery device is an integrated continuous system. After purification and compression, the carbon dioxide can be directly reused in the lithium carbonate carbonization process, realizing a closed-loop carbon resource cycle, avoiding direct emissions of carbon dioxide, reducing the purchase of carbon dioxide, and achieving efficient recycling of carbon resources.

[0004] To achieve this objective, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a device for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. The recovery device includes a lithium bicarbonate pyrolysis vessel, and the top of the lithium bicarbonate pyrolysis vessel is sequentially connected to a gas-liquid separator, a condenser, a first buffer tank, a carbon dioxide compressor, and a second buffer tank.

[0006] The outlet of the second buffer tank is connected to a lithium carbonate carbonization device;

[0007] The condenser is a demisting condenser.

[0008] In the recovery device described in this invention, a gas-liquid separator is connected to the top of the lithium bicarbonate pyrolysis reactor. The gas-liquid separator can remove lithium mist and droplets from carbon dioxide, thereby improving the purity of carbon dioxide. The carbon dioxide gas passing through the gas-liquid separator is then condensed and dehydrated by a condenser. The condenser is also a demisting condenser, which can further demist and increase the purity of carbon dioxide. After being compressed and pressurized by a compressor, high-purity carbon dioxide that can be directly used for lithium carbonate carbonization can be obtained, which greatly reduces the purchase of carbon dioxide. The recovery rate of the obtained carbon dioxide is ≥95%, and the purity is ≥99.5%.

[0009] Preferably, the demister condenser is a wire mesh demister condenser.

[0010] The demisting method described in this invention is wire mesh demisting. Compared to other demisting methods, wire mesh demisting can efficiently capture fine droplets ≥3~5μm in the gas, achieving a demisting efficiency of 98%~99.8%. It prevents droplets from being carried into the compressor and condenser, avoiding liquid hammer, corrosion, and scaling, thus extending equipment life and reducing maintenance frequency. Specifically, wire mesh demisting can prevent equipment vibration caused by the intake of droplets in the downstream compressor, extending equipment life, efficiently separating water mist, preventing liquid phase from mixing into the gas phase, which is beneficial for improving carbon dioxide purity. Furthermore, it has a simple structure and is easy to install.

[0011] Preferably, a dryer is also provided between the carbon dioxide compressor and the second buffer tank.

[0012] The dryer of this invention can further remove impurities from carbon dioxide and improve the purity of carbon dioxide.

[0013] Preferably, the dryer is a molecular sieve dryer.

[0014] Because CO2 is highly susceptible to hydrate formation and ice blockage under high pressure and low temperature, the dryer of this invention is a molecular sieve dryer. Molecular sieves can lower the dew point to below -60°C and firmly adsorb moisture. If moisture is not removed, it can easily generate carbonic acid, which corrodes equipment and shortens its lifespan. Compared with other types of dryers (such as silica gel dryers), the dynamic adsorption capacity of molecular sieves (up to 18%-22% of their own weight) is much greater than that of silica gel. It can withstand a greater moisture load and has a lower regeneration frequency, thereby reducing switching energy consumption. Therefore, molecular sieve dryers can deeply remove moisture from gases, simultaneously adsorb trace amounts of polar impurities, provide a dry gas source with extremely low dew point, protect equipment, and ensure production processes and product quality.

[0015] The carbon dioxide filter described in this invention can filter out dust, moisture, oil mist, and organic impurities in the gas, purify the CO2 gas source, protect equipment pipelines, ensure high purity of recovered carbon dioxide, and prevent raw material contamination. In addition, since the production of electronic-grade ultrapure lithium fluoride has extremely high requirements for impurity ions such as silicon and sulfate, the carbon dioxide filter can purify the recovered gas source and improve the purity of carbon dioxide.

[0016] Preferably, the gas-liquid separator includes a spray scrubbing tower, a spray water tank, and a spray water cooler.

[0017] This invention removes lithium mist and droplets through a spray scrubbing tower. The bottom condensate generated by the spray scrubbing tower, spray water tank, and spray water cooler is recycled back to the lithium bicarbonate pyrolysis kettle, thereby achieving lithium mist recovery, reducing lithium loss, and improving raw material utilization.

[0018] Preferably, the bottom of the spray scrubbing tower is connected to a spray water tank, and one side is connected to a spray water cooler.

[0019] Preferably, the outer wall of the lithium bicarbonate pyrolysis reactor is provided with a heating jacket, and the interior is provided with a stirring mechanism.

[0020] The lithium bicarbonate pyrolysis reactor of the present invention is provided with a heating jacket on the outer wall to ensure continuous operation of the pyrolysis reactor, and the stirring mechanism can prevent materials from sticking to the wall and ensure stable and efficient reaction.

[0021] Preferably, the bottom of the lithium bicarbonate pyrolysis reactor is provided with a slurry outlet.

[0022] Preferably, the slurry outlet is connected to a centrifuge.

[0023] The slurry outlet of the lithium bicarbonate pyrolysis reactor of the present invention is connected to a centrifuge for solid-liquid separation and material discharge.

[0024] Preferably, the condensate at the bottom of the gas-liquid separator is returned to the lithium bicarbonate pyrolysis reactor.

[0025] Preferably, the condensate at the bottom of the condenser is returned to the lithium bicarbonate pyrolysis reactor.

[0026] The gas-liquid separator and the condensate at the bottom of the condenser described in this invention are returned to the pyrolysis kettle, which can realize lithium mist recovery, reduce lithium loss, and improve raw material utilization.

[0027] Secondly, the present invention provides a method for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate, the recovery method comprising the following steps:

[0028] In the recovery apparatus as described in the first aspect, the carbon dioxide generated from the pyrolysis of lithium bicarbonate is sequentially subjected to gas-liquid separation, condensation, demisting, and compression before being fed into a lithium carbonate carbonation apparatus to prepare lithium carbonate.

[0029] Preferably, the defogging method is wire mesh defogging.

[0030] Preferably, the material is dried after compression.

[0031] Preferably, the drying method is molecular sieve drying.

[0032] Preferably, the product is further filtered after drying.

[0033] Preferably, the temperature for the lithium bicarbonate pyrolysis is 90℃-96℃, for example, 90℃, 92℃, 94℃ or 96℃, and the pressure is 0.1MPa-0.3MPa, for example, 0.1MPa, 0.15MPa, 0.2MPa, 0.25MPa or 0.3MPa, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] In the recovery device of the present invention, a gas-liquid separator is connected to the top of the lithium bicarbonate pyrolysis kettle. The gas-liquid separator can remove lithium mist and droplets from carbon dioxide, thereby improving the purity of carbon dioxide. The carbon dioxide gas after passing through the gas-liquid separator is then condensed and dehydrated by a condenser. The condenser is also a demisting condenser, which can further increase the purity of carbon dioxide by demisting. After being compressed by a compressor, high-purity carbon dioxide that can be directly used for lithium carbonate carbonization can be obtained, which greatly reduces the purchase of carbon dioxide. The recovery rate of the obtained carbon dioxide is ≥95%, and the purity is ≥99.5%. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the carbon dioxide recovery device generated by lithium bicarbonate pyrolysis as described in Embodiments 1-2 of the present invention.

[0037] Among them, V01 is the lithium bicarbonate pyrolysis reactor, F01 is the spray scrubbing tower, V02 is the spray water tank, E01 is the spray water cooler, E02 is the condenser, V03 is the first buffer tank, C01 is the compressor, V04 is the second buffer tank, and F02 is the carbon dioxide filter. Detailed Implementation

[0038] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0039] Example 1

[0040] This embodiment provides a device for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. A schematic diagram of the recovery device is shown below. Figure 1 As shown, it includes a lithium bicarbonate pyrolysis reactor V01, and the top of the lithium bicarbonate pyrolysis reactor V01 is sequentially connected to a gas-liquid separator, a condenser E02, a first buffer tank V03, a carbon dioxide compressor C01, a dryer, a second buffer tank V04, and a carbon dioxide filter F02.

[0041] The condenser E02 is a wire mesh demister condenser E02, and the dryer is a molecular sieve dryer;

[0042] The gas-liquid separator includes a spray scrubbing tower F01, a spray water tank V02, and a spray water cooler E01. The bottom of the spray scrubbing tower F01 is connected to the spray water tank V02, and one side is connected to the spray water cooler E01.

[0043] The outer wall of the lithium bicarbonate pyrolysis reactor V01 is equipped with a heating jacket, the interior is equipped with a stirring mechanism, and the bottom is provided with a slurry outlet, which is connected to a centrifuge.

[0044] The bottom condensate of the gas-liquid separator is returned to the lithium bicarbonate pyrolysis reactor V01; the bottom condensate of the condenser E02 is returned to the lithium bicarbonate pyrolysis reactor V01.

[0045] This embodiment also provides a method for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate, the recovery method comprising the following steps:

[0046] In the recovery device described in this embodiment, the carbon dioxide generated from the pyrolysis of lithium bicarbonate is sequentially subjected to gas-liquid separation, condensation, wire mesh demisting, compression, molecular sieve drying and filtration, and then fed into the lithium carbonate carbonation device to prepare lithium carbonate.

[0047] The lithium bicarbonate pyrolysis temperature is 90°C and the pressure is 0.1 MPa.

[0048] Example 2

[0049] This embodiment provides a device for recovering carbon dioxide generated from lithium bicarbonate pyrolysis. The recovery device includes a lithium bicarbonate pyrolysis reactor V01. The top of the lithium bicarbonate pyrolysis reactor V01 is sequentially connected to a gas-liquid separator, a condenser E02, a first buffer tank V03, a carbon dioxide compressor C01, a dryer, a second buffer tank V04, and a carbon dioxide filter F02.

[0050] The condenser E02 is a wire mesh demister condenser E02, and the dryer is a molecular sieve dryer;

[0051] The gas-liquid separator includes a spray scrubbing tower F01, a spray water tank V02, and a spray water cooler E01. The bottom of the spray scrubbing tower F01 is connected to the spray water tank V02, and one side is connected to the spray water cooler E01.

[0052] The outer wall of the lithium bicarbonate pyrolysis reactor V01 is equipped with a heating jacket, the interior is equipped with a stirring mechanism, and the bottom is provided with a slurry outlet, which is connected to a centrifuge.

[0053] The bottom condensate of the gas-liquid separator is returned to the lithium bicarbonate pyrolysis reactor V01; the bottom condensate of the condenser E02 is returned to the lithium bicarbonate pyrolysis reactor V01.

[0054] This embodiment also provides a method for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate, the recovery method comprising the following steps:

[0055] In the recovery device described in this embodiment, the carbon dioxide generated from the pyrolysis of lithium bicarbonate is sequentially subjected to gas-liquid separation, condensation, wire mesh demisting, compression, molecular sieve drying and filtration, and then fed into the lithium carbonate carbonation device to prepare lithium carbonate.

[0056] The lithium bicarbonate pyrolysis temperature is 96°C and the pressure is 0.3 MPa.

[0057] Example 3

[0058] This embodiment provides a device for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. Except for the dryer being a silica gel dryer, the recovery device is the same as that in Embodiment 1.

[0059] This embodiment also provides a method for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. Except for the recovery device described in this embodiment, the recovery method is the same as that in Embodiment 1.

[0060] Example 4

[0061] This embodiment provides a device for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. The recovery device is the same as that in Embodiment 1 except that it does not contain a dryer.

[0062] This embodiment also provides a method for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. The recovery method is the same as that in Embodiment 1, except that it uses the recovery device described in this embodiment and does not involve drying.

[0063] Example 5

[0064] This embodiment provides a device for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. The recovery device is the same as that in Embodiment 1 except that it does not contain a carbon dioxide filter.

[0065] This embodiment also provides a method for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. The recovery method is the same as that in Embodiment 1, except that it uses the recovery device described in this embodiment and does not involve filtration.

[0066] Comparative Example 1

[0067] This comparative example provides a device for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. Except for the fact that the condenser does not have a demisting function, the recovery device is the same as that in Example 1.

[0068] This comparative example also provides a method for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. The recovery method is the same as that in Example 1, except that it uses the recovery device described in this comparative example and does not perform demisting.

[0069] Comparative Example 2

[0070] This comparative example provides a device for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. The recovery device is identical to that of Example 1 except that it does not contain a gas-liquid separator.

[0071] This comparative example also provides a method for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate. The recovery method is the same as that in Example 1, except that it uses the recovery device described in this comparative example and does not perform gas-liquid separation.

[0072] The purity and recovery rate of carbon dioxide recovered by the recovery devices described in the above embodiments and comparative examples are shown in Table 1:

[0073] Table 1

[0074]

[0075] As can be seen from Table 1 above:

[0076] As shown in Examples 1-2 and Comparative Example 1, the condenser of the present invention has a demisting function, which can further improve the purity of carbon dioxide; as shown in Examples 1-2 and Comparative Example 2, the gas-liquid separator in the recovery device of the present invention can remove lithium mist and droplets from carbon dioxide, thereby improving the recovery rate and purity of carbon dioxide; as shown in Examples 1-2 and Example 3, the dryer of the present invention is a molecular sieve dryer, which can further improve the purity of the recovered carbon dioxide compared with other types of dryers; as shown in Examples 1-2 and Examples 4-5, both the dryer and the carbon dioxide filter of the present invention can further remove impurities from carbon dioxide, thereby improving the recovery purity.

[0077] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A device for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate, characterized in that, The recovery device includes a lithium bicarbonate pyrolysis reactor, and the top of the lithium bicarbonate pyrolysis reactor is sequentially connected to a gas-liquid separator, a condenser, a first buffer tank, a carbon dioxide compressor, and a second buffer tank. The outlet of the second buffer tank is connected to a lithium carbonate carbonization device; The condenser is a demisting condenser.

2. The carbon dioxide recovery device generated from lithium bicarbonate pyrolysis according to claim 1, characterized in that, The demister condenser is a wire mesh demister condenser.

3. The apparatus for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate according to claim 1 or 2, characterized in that, A dryer is also provided between the carbon dioxide compressor and the second buffer tank. Preferably, the dryer is a molecular sieve dryer.

4. The apparatus for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate according to claim 1 or 2, characterized in that, The recycling device also includes a carbon dioxide filter, and the outlet of the second buffer tank is first connected to the carbon dioxide filter and then to the lithium carbonate carbonization device.

5. The apparatus for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate according to claim 1 or 2, characterized in that, The gas-liquid separator includes a spray scrubbing tower, a spray water tank, and a spray water cooler. Preferably, the bottom of the spray scrubbing tower is connected to a spray water tank, and one side is connected to a spray water cooler.

6. The apparatus for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate according to claim 1 or 2, characterized in that, The outer wall of the lithium bicarbonate pyrolysis reactor is equipped with a heating jacket, and the interior is equipped with a stirring mechanism.

7. The apparatus for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate according to claim 1 or 2, characterized in that, The bottom of the lithium bicarbonate pyrolysis reactor is provided with a slurry outlet; Preferably, the slurry outlet is connected to a centrifuge.

8. The apparatus for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate according to claim 1 or 2, characterized in that, The condensate at the bottom of the gas-liquid separator is returned to the lithium bicarbonate pyrolysis reactor. Preferably, the condensate at the bottom of the condenser is returned to the lithium bicarbonate pyrolysis reactor.

9. A method for recovering carbon dioxide generated from the pyrolysis of lithium bicarbonate, characterized in that, The recycling method includes the following steps: In the recovery apparatus as described in any one of claims 1-8, the carbon dioxide generated from the pyrolysis of lithium bicarbonate is sequentially subjected to gas-liquid separation, condensation, demisting, and compression, and then fed into a lithium carbonate carbonation apparatus to prepare lithium carbonate.

10. The recycling method according to claim 9, characterized in that, The defogging method is wire mesh defogging; Preferably, the material is dried after compression; Preferably, the drying method is molecular sieve drying; Preferably, the product is further filtered after drying; Preferably, the temperature of the lithium bicarbonate pyrolysis is 90℃-96℃, and the pressure is 0.1MPa-0.3MPa.

Images