Fluidized bed apparatus and method of making porous carbon and carbon materials using a fluidized bed apparatus

Abstract

The present application relates to a kind of fluidized bed device and the method for preparing porous carbon and carbon material using fluidized bed device.The fluidized bed device includes primary fluidized bed device and at least one secondary fluidized bed device;Primary fluidized bed device is preheated to carbon raw material and particle size screening, including primary fluidized bed main body, primary feeding system, primary discharge system and primary gas outlet system;Secondary fluidized bed device is activated to carbon raw material after being processed by primary fluidized bed device, including heating device, secondary fluidized bed main body, secondary feeding system, secondary discharge system, gas inlet system and secondary gas outlet system;Primary discharge system is connected by material pipeline with secondary feeding system, and carbon raw material after being preheated and particle size screening is transported to secondary fluidized bed device;Secondary gas outlet system is connected by return gas pipeline with primary fluidized bed device, and at least part of tail gas generated by secondary fluidized bed device is introduced into primary fluidized bed device, and carbon raw material in primary fluidized bed device is preheated and particle size screening.

Description

Technical Field

[0001] This invention relates to the field of porous carbon material preparation technology, and in particular to a fluidized bed apparatus and a method for preparing porous carbon and carbon materials using the fluidized bed apparatus. Background Technology

[0002] Porous carbon materials possess high specific surface area and abundant pore structures, making them widely applicable in fields such as electrochemical energy storage and adsorption separation. Existing porous carbon materials are typically prepared through activation in a fluidized bed apparatus. During fluidized bed activation, the carbon raw material is fluidized under the action of a fluidizing gas and reacts at a specific temperature and activation atmosphere to form the desired pore structure.

[0003] In existing fluidized bed activation devices, an enlarged section is typically installed at the top of the fluidized bed to reduce material carryover from the main fluidized bed. The cross-sectional area of ​​the enlarged section is usually 2 to 4 times that of the main section. By increasing the flow cross-sectional area, the apparent gas velocity is reduced, allowing particles carried into the upper region to settle and return to the main fluidized bed, thereby reducing material loss and increasing product yield. However, as fluidized bed devices become larger, the size of the enlarged section also increases accordingly, increasing equipment manufacturing costs and placing higher demands on the selection of metal materials used under high-temperature conditions and the processing and manufacturing of equipment. Simultaneously, some materials may remain in the enlarged section for a longer period, causing differences in the activation reaction process of different material particles, thus affecting the activation degree of porous carbon materials and the consistency of product performance.

[0004] On the other hand, existing fluidized bed activation processes typically involve directly adding charcoal feedstock from the feed tank to the fluidized bed device. Upon entering the fluidized bed, the charcoal feedstock is usually at room temperature or a low temperature. For activation fluidized beds operating at higher temperatures, the addition of room-temperature charcoal feedstock requires a lengthy heating process, which not only affects production efficiency but also increases energy consumption during heating. Furthermore, the introduction of low-temperature charcoal feedstock into a high-temperature fluidized bed can cause significant localized temperature changes within the furnace, negatively impacting the long-term stable operation of the equipment.

[0005] Furthermore, charcoal raw materials typically require particle size control before entering a fluidized bed for activation. Current technologies generally pre-treat charcoal raw materials using independent equipment such as crushing and classifying processes. However, due to limitations in the classifying equipment and process conditions, the treated charcoal raw materials may still exhibit a wide particle size distribution. Especially when the raw material contains a large number of small-diameter particles, if the operating gas velocity of the fluidized bed is set according to the fluidization and activation requirements for larger-diameter particles, these small-diameter particles are more likely to escape from the dense phase region with the gas flow. Therefore, it is usually still necessary to reduce the gas velocity in the upper region using the aforementioned expansion section. On the other hand, the particle size distribution obtained from independent crushing and classification is usually controlled based on the raw material itself, making it difficult to specifically match it according to the specific fluidized bed structure and actual operating gas velocity.

[0006] Therefore, existing porous carbon fluidized bed activation technology still suffers from problems such as low carbon feed temperature, long heating time, high energy consumption, insufficient matching degree between carbon feed particle size distribution and actual fluidized bed operating conditions, and complex equipment structure, high manufacturing cost and difficulty in large-scale production due to the enlargement section set up to reduce particle carry-out. It is necessary to further improve the existing fluidized bed device and porous carbon preparation process. Summary of the Invention

[0007] The purpose of this invention is to address the deficiencies of existing technologies by providing a fluidized bed apparatus and a method for preparing porous carbon and carbon materials using a fluidized bed apparatus. Through the coordinated arrangement of a primary and a secondary fluidized bed apparatus, the carbon raw material is preheated and particle size-screened before entering the secondary fluidized bed apparatus for activation. At least a portion of the exhaust gas from the secondary fluidized bed apparatus is used as a heat source and fluidizing gas for the primary fluidized bed apparatus, thereby achieving heat recovery and utilization, improving the uniformity of the carbon raw material particle size distribution and the consistency of the porous carbon material product. Simultaneously, it helps to shorten the heating time, reduce energy consumption, and simplify the structure of the activation fluidized bed.

[0008] To achieve the above objectives, in a first aspect, the present invention provides a fluidized bed apparatus, comprising: a primary fluidized bed apparatus and at least one secondary fluidized bed apparatus; The primary fluidized bed device includes: a primary fluidized bed body, a primary feeding system, a primary discharging system, and a primary gas discharge system. The primary fluidized bed device is used for preheating and particle size screening of carbon raw materials. The secondary fluidized bed device includes: a heating device, a secondary fluidized bed body, a secondary feeding system, a secondary discharging system, an air inlet system, and a secondary air outlet system. The secondary fluidized bed device is used to activate the carbon raw material processed by the primary fluidized bed device. The primary discharge system and the secondary feed system are connected by a material pipeline, through which the preheated and particle size-screened carbon raw material is transported to the secondary fluidized bed device. The secondary gas outlet system is connected to the primary fluidized bed device via a return gas pipeline, and at least part of the tail gas generated by the secondary fluidized bed device is introduced into the primary fluidized bed device. The hot gas flow generated by the tail gas is used to preheat and screen the carbon raw material in the primary fluidized bed device.

[0009] Preferably, the primary exhaust system includes a first filter, which is disposed on the exhaust path of the primary fluidized bed body. The first filter is used to intercept primary particles in the exhaust gas discharged from the primary fluidized bed body, so that the primary intercepted particles return to the primary fluidized bed body, and the dust-laden gas passes through the first filter and is discharged from the primary fluidized bed body. The dust-laden gas includes primary filtered particles.

[0010] More preferably, the primary exhaust system is also connected to a collection tank, which is equipped with a second filter. The primary filter particles that pass through the first filter enter the collection tank with the airflow and are subjected to gas-solid separation by the second filter, so that the separated secondary filter particles are collected in the collection tank, and the separated gas carrying the secondary filter particles passes through the second filter and is discharged to the exhaust gas treatment system.

[0011] More preferably, the primary exhaust system further includes a bypass pipeline; One end of the bypass pipeline is connected to the pipeline between the air outlet of the primary fluidized bed body and the first filter, and the other end of the bypass pipeline is connected to the pipeline between the first filter and the collection tank to form a bypass channel that bypasses the first filter. A first valve is installed on the pipeline at the inlet of the first filter, and a second valve is installed on the bypass pipeline. The dust-laden gas discharged from the primary fluidized bed body is controlled to pass through the first filter or enter the collection tank through the bypass channel by the first valve and the second valve.

[0012] Preferably, the secondary gas outlet system includes a third filter, which is disposed on the gas outlet path of the secondary fluidized bed body and is used to filter the exhaust gas generated during the activation process of the secondary fluidized bed device; At least a portion of the exhaust gas filtered by the third filter is introduced into the primary fluidized bed device via the return gas pipeline, and / or discharged to the exhaust gas treatment system via the secondary exhaust gas emission pipeline.

[0013] Preferably, both the primary fluidized bed body and the secondary fluidized bed body include a dense phase zone and a settling zone located above the dense phase zone; The dense phase region and the settling region of the secondary fluidized bed body have the same cross-sectional dimensions, and the secondary fluidized bed body does not have an enlarged section relative to the diameter expansion of the dense phase region.

[0014] Preferably, one primary fluidized bed device is connected to 1 to 10 secondary fluidized bed devices; The material pipeline and the return gas pipeline are respectively provided between the primary fluidized bed device and each of the secondary fluidized bed devices. At least one of the secondary fluidized bed devices can pass at least a portion of the tail gas generated during its activation process into the primary fluidized bed device.

[0015] Secondly, embodiments of the present invention provide a method for preparing porous carbon using the fluidized bed apparatus described in the first aspect above, wherein carbon raw material is added to the primary fluidized bed apparatus; The tail gas discharged during the operation of at least one of the secondary fluidized bed devices is introduced into the primary fluidized bed device. The tail gas is used to preheat the carbon raw material and to fluidize and screen the carbon raw material under the action of the airflow formed by the tail gas. The primary filtered particles pass through the first filter and are discharged with the airflow. The first filter retains the primary retained particles and returns them to the primary fluidized bed body. The preheated and particle size-screened carbon raw material is conveyed from the primary fluidized bed device to the secondary fluidized bed device, which is in the feeding state. A gasifying agent containing water vapor and / or carbon dioxide is introduced into the secondary fluidized bed device to activate the carbon raw material and obtain porous carbon material. The exhaust gas generated during the activation process of the secondary fluidized bed device is filtered by the third filter and at least part of it is introduced into the primary fluidized bed device through the return gas pipeline for preheating and particle size screening of the carbon raw material subsequently added to the primary fluidized bed device.

[0016] Preferably, the temperature of the exhaust gas introduced into the primary fluidized bed device is 500–800°C; The primary fluidized bed device processes the carbon raw material for 1 to 30 hours, and the secondary fluidized bed device activates the carbon raw material for 5 to 50 hours. The processing time of the primary fluidized bed device for the carbon raw material is less than or equal to the activation time of the secondary fluidized bed device for the carbon raw material.

[0017] Thirdly, embodiments of the present invention provide a porous carbon prepared by the method described in the second aspect above, wherein the volume distribution particle size Dv10 of the porous carbon material is greater than 5.0 μm and the particle size distribution SPAN value is less than or equal to 0.8.

[0018] The fluidized bed device provided in this embodiment of the invention includes a primary fluidized bed device and at least one secondary fluidized bed device. The primary fluidized bed device is used to preheat and screen the carbon raw material, and the secondary fluidized bed device is used to activate the carbon raw material processed by the primary fluidized bed device. A material conveying path and a tail gas return path are formed between the primary fluidized bed device and the secondary fluidized bed device, respectively, so that the preheated and screened carbon raw material is conveyed from the primary fluidized bed device to the secondary fluidized bed device, while at least a portion of the tail gas generated by the secondary fluidized bed device is returned to the primary fluidized bed device. Therefore, on the one hand, the heat carried by the exhaust gas from the secondary fluidized bed device can be used to preheat the carbon raw material, reducing the temperature difference between the carbon raw material and the furnace environment when it enters the secondary fluidized bed device, shortening the subsequent heating process and reducing the corresponding energy consumption. At the same time, it reduces the temperature shock to the equipment caused by the direct entry of the lower-temperature carbon raw material into the high-temperature fluidized bed. On the other hand, the carbon raw material can be pre-screened in the primary fluidized bed device to ensure that the carbon raw material entering the secondary fluidized bed device has a more concentrated particle size distribution. This is beneficial for the carbon raw material to adapt to the fluidization and activation conditions of the secondary fluidized bed device, improving the consistency of the activation process and the properties of the resulting porous carbon material, and providing conditions for simplifying the structure of the secondary fluidized bed device.

[0019] In summary, this invention achieves synergy between the preheating, particle size screening, and activation processes of carbon raw materials through the coupling of a primary fluidized bed device and a secondary fluidized bed device. This is beneficial for improving the production efficiency and product consistency of porous carbon preparation, reducing equipment operation and manufacturing costs, and improving the operational stability and service life of the fluidized bed device. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a fluidized bed device provided in an embodiment of the present invention. Detailed Implementation

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0022] In this invention, Dv10, Dv50, and Dv90 are all characteristic particle sizes determined based on particle volume distribution. Specifically, Dv10 is the particle size corresponding to a cumulative particle volume distribution of 10%; Dv50 is the particle size corresponding to a cumulative particle volume distribution of 50%; and Dv90 is the particle size corresponding to a cumulative particle volume distribution of 90%.

[0023] The SPAN value is used to characterize the width of the particle size distribution. The formula is: SPAN = (Dv90 - Dv10) / Dv50. The smaller the SPAN value, the more concentrated the particle size distribution; the larger the SPAN value, the wider the particle size distribution.

[0024] This invention provides a fluidized bed apparatus, comprising: a primary fluidized bed apparatus and at least one secondary fluidized bed apparatus. Figure 1 This is a schematic diagram of a fluidized bed device provided in an embodiment of the present invention, showing a two-stage fluidized bed. The following is in conjunction with... Figure 1 The technical solution of the present invention will be described below.

[0025] The primary fluidized bed device includes: a primary fluidized bed body, a primary feed system, a primary discharge system, and a primary gas discharge system. The primary fluidized bed device is used for preheating and particle size screening of carbon raw materials.

[0026] The primary fluidized bed consists of a dense phase zone and a settling zone above it. The dense phase zone contains the carbon feedstock and keeps it in a fluidized state under the action of the gas introduced into the primary fluidized bed for preheating and particle size screening. The settling zone is used to allow particles that have been carried away from the dense phase zone by bed fluctuations or bubble bursts but have not been discharged with the gas to settle and return to the dense phase zone, thereby reducing the unintended carry-out of particles.

[0027] The primary feed system is connected to the primary fluidized bed body and is used to add the carbon raw material to be processed into the primary fluidized bed body. Figure 1 In the illustrated embodiment, the primary feed system is located above the primary fluidized bed body, and the carbon raw material is added from the top of the primary fluidized bed body. After the carbon raw material is added, it undergoes preheating and particle size screening under the action of gas returned from the secondary fluidized bed device.

[0028] The primary discharge system is connected to the primary fluidized bed body and is used to discharge the preheated and particle size-screened carbon raw material from the primary fluidized bed body. Figure 1 In the illustrated embodiment, the primary discharge system is located at the lower part of the primary fluidized bed body and is connected to the secondary feed system of the secondary fluidized bed unit via a material pipeline, enabling the carbon raw material processed by the primary fluidized bed unit to be transported from the primary fluidized bed unit to the secondary fluidized bed unit. In specific implementation, the material can be transported through the material pipeline under the positive pressure within the primary fluidized bed body. Ball valves can be installed on the material pipeline to control the material transport.

[0029] The primary exhaust system includes a first filter, labeled Filter 1 in the figure. The first filter is located in the exhaust path of the primary fluidized bed body and is used to intercept primary particles in the exhaust gas discharged from the primary fluidized bed body, returning the intercepted particles to the primary fluidized bed body, while allowing the dust-laden gas, including primary filtered particles, to pass through the first filter and exit the primary fluidized bed body. Thus, the first filter selectively intercepts particles discharged with the airflow, returning the intercepted particles to the primary fluidized bed body, while allowing the primary filtered particles to exit with the airflow, thereby achieving particle size screening of the carbon raw material within the primary fluidized bed body.

[0030] The first filter can be a metal filter element, a ceramic filter element, or other filter elements suitable for filtering high-temperature dusty gases. The filtration accuracy of the first filter can be selected according to the target particle size distribution, for example, it can be less than 1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 10 μm, 20 μm, or 50 μm. By matching the gas flow rate in the primary fluidized bed to the filtration accuracy of the first filter, the particle size range and discharge rate per unit time of the particles discharged from the primary fluidized bed can be adjusted, thereby adjusting the particle size distribution of the carbon raw material after treatment by the primary fluidized bed device.

[0031] The primary exhaust system is also connected to a collection tank, which is equipped with a second filter, shown as filter 2 in the figure. The primary filter particles that pass through the first filter enter the collection tank with the airflow and are separated into gas and solid by the second filter. The separated secondary filter particles are collected in the collection tank, and the separated gas carrying the secondary filter particles passes through the second filter and is discharged to the exhaust gas treatment system.

[0032] The second filter can be a metal filter element, a ceramic filter element, or other filter elements suitable for filtering dusty gases. The filtration accuracy of the second filter can be selected as needed, for example, less than 1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 10 μm, 20 μm, or 50 μm. The second filter achieves further gas-solid separation of the dusty gas discharged from the primary fluidized bed. The secondary particles, i.e., fine powder, intercepted by the second filter are deposited in the collection tank and can be discharged from the collection tank for further treatment; the gas filtered by the second filter is discharged to the tail gas treatment system.

[0033] The outlet of the second filter can be connected to the exhaust gas treatment system via the primary exhaust gas emission pipeline to discharge the gas treated by the second filter to the exhaust gas treatment system. A pressure regulating valve can be installed on the primary exhaust gas emission pipeline to regulate the operating pressure within the primary fluidized bed body.

[0034] Furthermore, the primary exhaust system also includes a bypass pipeline (not shown in the figure). One end of the bypass pipeline is connected to the pipeline between the exhaust port of the primary fluidized bed body and the first filter, and the other end of the bypass pipeline is connected to the pipeline between the first filter and the collection tank, forming a bypass channel that bypasses the first filter. A first valve (not shown in the figure) can be installed on the pipeline upstream of the first filter inlet, and a second valve (not shown in the figure) can be installed on the bypass pipeline. The first and second valves control whether the dust-laden gas discharged from the primary fluidized bed body passes through the first filter or enters the collection tank via the bypass channel.

[0035] In one operating mode, the pipeline containing the first filter is opened and the bypass pipeline is closed, allowing the dust-laden gas discharged from the primary fluidized bed to be filtered by the first filter, which then screens the particles. In another operating mode, when further adjustments are needed to the particle quantity discharged from the primary fluidized bed and the particle size distribution of the carbon raw material, the pipeline containing the first filter can be closed and the bypass pipeline opened, allowing the dust-laden gas to bypass the first filter and directly enter the collection tank, where it undergoes gas-solid separation by the second filter. By switching between the different gas flow paths, the appropriate screening method can be selected based on the required particle size distribution of the carbon raw material. The manual further states that when there are higher control requirements for the content of small-diameter particles, filter 1 can be closed, the bypass valve opened, and filter 2 can be used for filtration and particle collection.

[0036] In addition, during the operation of the primary fluidized bed device, the particle size distribution of the carbon raw material that has been screened by the primary fluidized bed device and sent to the secondary fluidized bed device can be adjusted by regulating the gas flow rate and the corresponding gas velocity in the bed, and by combining the filtration accuracy of the first filter.

[0037] The secondary fluidized bed device includes: a heating device, a secondary fluidized bed body, a secondary feeding system, a secondary discharging system, an air inlet system, and a secondary air outlet system. The secondary fluidized bed device is used to activate the carbon raw material after it has been processed by the primary fluidized bed device.

[0038] The secondary fluidized bed consists of a dense phase zone and a settling zone above it. The dense phase zone contains the carbon feedstock supplied by the primary fluidized bed unit and fluidizes and activates the carbon feedstock under the action of fluidizing gas and gasifying agent. The settling zone is used to allow particles that have been carried away from the dense phase zone by bed fluctuations or bubble bursts but have not been discharged with the exhaust gas to settle and return to the dense phase zone, thereby reducing the amount of particles discharged with the exhaust gas.

[0039] The dense phase zone and settling zone of the secondary fluidized bed have the same cross-sectional dimensions, and the secondary fluidized bed does not have an enlarged section relative to the dense phase zone. In this embodiment, the secondary fluidized bed adopts a basically constant diameter structure, without the enlarged section found in traditional fluidized beds where the cross-sectional area is significantly larger than that of the main body. Traditional enlarged sections typically reduce the apparent gas velocity by increasing the flow cross-sectional area, causing particles carried out by the gas flow to re-settle into the dense phase zone. Since this invention uses a primary fluidized bed to screen the carbon feedstock before it enters the secondary fluidized bed, reducing the number of smaller particles entering the secondary fluidized bed and making the particle size distribution of the carbon feedstock more concentrated, the escape of particles from the dense phase zone can be reduced when the secondary fluidized bed uses an operating gas velocity that meets the requirements of the fluidization and activation processes. This provides the conditions for eliminating the traditional enlarged section. Although the secondary fluidized bed does not have an enlarged section, a settling zone is still retained above the dense phase zone to allow some particles carried out by bed fluctuations or bubble bursts to settle back into the dense phase zone. Therefore, while meeting the requirements of fluidization and activation processes, the structure of the secondary fluidized bed can be simplified, reducing the manufacturing cost and material selection difficulty of high-temperature, large-size fluidized bed devices.

[0040] The heating device can specifically be an electric furnace or other device capable of heating the fluidized bed body. Figure 1 In the illustrated embodiment, the heating device is located outside the secondary fluidized bed body and is used to heat the secondary fluidized bed body and the carbon raw material therein, so that the carbon raw material reaches the required activation temperature. Since the carbon raw material transported from the primary fluidized bed device to the secondary fluidized bed device has already been preheated, the temperature rise and heating time of the carbon raw material after entering the secondary fluidized bed device can be reduced.

[0041] The secondary feed system is located on and connected to the main body of the secondary fluidized bed, and is used to receive the preheated and particle size-screened char raw material from the primary fluidized bed unit. The primary discharge system is connected to the secondary feed system by a material pipeline, through which the preheated and particle size-screened char raw material is transported to the secondary fluidized bed unit.

[0042] The secondary fluidized bed unit is also equipped with an air inlet system for introducing a gasifying agent into the secondary fluidized bed body. The gasifying agent may include water vapor and / or carbon dioxide. At the activation temperature provided by the heating device, the gasifying agent undergoes a physical activation reaction with the carbon raw material to form a porous structure inside the carbon material.

[0043] Optionally, the secondary exhaust system includes a third filter, shown as filter 3 in the figure. The third filter is located on the exhaust path of the secondary fluidized bed and is used to filter the exhaust gas generated during the activation process of the secondary fluidized bed device. This ensures that particles trapped by the third filter remain within the secondary fluidized bed device, and the filtered exhaust gas is discharged from the secondary fluidized bed device. The third filter can be a metal filter element, a ceramic filter element, or other filter elements suitable for filtering high-temperature dusty exhaust gas, such as 316L, 310S, Inconel nickel-based alloy series, Hastelloy series, or ceramic series materials. The filtration accuracy of the third filter can be selected as needed, for example, less than 1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 10 μm, 20 μm, or 50 μm. By selecting a third filter with the appropriate filtration accuracy, particles discharged with the exhaust gas during the activation process of the secondary fluidized bed device can be filtered, ensuring that these particles are trapped and retained within the secondary fluidized bed device, thereby reducing the amount of particles discharged with the exhaust gas.

[0044] A pressure regulating valve can be installed on the secondary exhaust gas emission line to adjust the operating pressure within the secondary fluidized bed. At least a portion of the exhaust gas filtered by the third filter is fed into the primary fluidized bed unit via a return gas pipeline, and / or discharged to the exhaust gas treatment system via the secondary exhaust gas emission line. A ball valve can also be installed on the return gas pipeline to control the flow rate of exhaust gas returning to the primary fluidized bed unit or to control the opening and closing of the return gas pipeline.

[0045] Specifically, the secondary exhaust system is connected to the primary fluidized bed unit via a return gas pipeline, allowing at least a portion of the exhaust gas generated by the secondary fluidized bed unit to be introduced into the primary fluidized bed unit. The resulting hot gas flow from the exhaust gas is used to preheat and screen the carbon feedstock in the primary fluidized bed unit. The return gas pipeline can be insulated to reduce heat loss during the transport of the exhaust gas from the secondary to the primary fluidized bed unit. The exhaust gas discharged from the secondary fluidized bed unit may include unreacted gasifying agent and gases produced by the activation reaction, such as water vapor, carbon dioxide, hydrogen, and carbon monoxide. By returning at least a portion of the exhaust gas to the primary fluidized bed unit, the heat carried by the exhaust gas can be recovered and utilized. Simultaneously, the returned gas is used to form the gas flow required for the primary fluidized bed unit, achieving preheating and particle size screening of the carbon feedstock.

[0046] In this application, the first, second, and third filters can all be selected with filter elements of appropriate filtration precision according to actual filtration requirements. The filtration precision mentioned in this application refers to a nominal particle size parameter used to characterize the filter's ability to retain particles and allow particles to pass through. In this example, under the same test and evaluation conditions, the smaller the filtration precision value, the smaller the particle size the filter can retain; the larger the filtration precision value, the larger the particle size range that can pass through the filter. The filtration precision of the first filter is N, the filtration precision of the second filter is K, and the filtration precision of the third filter is M, satisfying K≤N≤M. The filtration precision K of the second filter is less than or equal to the filtration precision N of the first filter, enabling the second filter to further separate the gas and solid components of particles that have passed through the first filter and entered the collection tank with the airflow, thereby collecting the fine powder. The filtration precision M of the third filter is greater than or equal to the filtration precision N of the first filter, so that the exhaust gas from the secondary fluidized bed device is returned to the primary fluidized bed device after being filtered by the third filter, and works with the first filter in the primary fluidized bed device for particle filtration and particle size screening. For example, the filtration precision of the first filter, the second filter, and the third filter can be selected from less than 1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 10 μm, 20 μm, or 50 μm, respectively, as needed, and should satisfy K≤N≤M.

[0047] The secondary discharge system of the fluidized bed unit is connected to the main body of the secondary fluidized bed and is used to discharge the porous carbon material obtained after activation from the main body of the secondary fluidized bed. Figure 1 In the embodiment shown, the secondary discharge system is located at the bottom of the secondary fluidized bed body, and the porous carbon material is discharged through the secondary discharge system.

[0048] In this invention, the carbon raw material, after being preheated by the primary fluidized bed device, enters the secondary fluidized bed device, which can achieve the feeding of carbon raw material at a higher temperature. Combined with the secondary discharge system, the porous carbon material is discharged, thereby improving the production connection efficiency between different batches.

[0049] In some implementations, a primary fluidized bed unit can be connected to multiple secondary fluidized bed units. For example, one primary fluidized bed unit can correspond to 1 to 10 secondary fluidized bed units, preferably 1 to 6. Material pipelines and return gas pipelines can be installed between the primary fluidized bed unit and each secondary fluidized bed unit. When multiple secondary fluidized bed units operate alternately, at least one operating secondary fluidized bed unit can return part or all of its exhaust gas to the primary fluidized bed unit to preheat and screen the carbon feedstock in the primary fluidized bed unit. When another secondary fluidized bed unit is ready to feed, the preheated and screened carbon feedstock from the primary fluidized bed unit is then transported to that secondary fluidized bed unit, thereby achieving coordinated operation between the primary fluidized bed unit and multiple secondary fluidized bed units.

[0050] When using the fluidized bed apparatus of this invention to prepare porous carbon, the carbon raw material is first added to the primary fluidized bed apparatus, and the exhaust gas from at least one operating secondary fluidized bed apparatus is introduced into the primary fluidized bed apparatus via a return gas pipeline. The temperature of the returned exhaust gas is preferably 500–800°C. The heat carried by the returned exhaust gas is used to preheat the carbon raw material, while simultaneously causing the carbon raw material to undergo fluidization and particle size screening under the action of the airflow brought by the exhaust gas. The gas discharged from the primary fluidized bed body passes through a first filter, wherein the primary retained particles are retained by the first filter and returned to the primary fluidized bed body, while the primary filtered particles pass through the first filter and are discharged with the airflow. The processing time of the carbon raw material in the primary fluidized bed apparatus can be 1–30 hours, preferably 3–10 hours. The preheated and particle size-screened carbon raw material is then transported to the secondary fluidized bed apparatus in the feeding state via a material pipeline.

[0051] After the carbon raw material enters the secondary fluidized bed device, a gasifying agent containing water vapor and / or carbon dioxide is introduced into the device, and the carbon raw material is activated under the temperature conditions provided by the heating device to obtain porous carbon material. The heating activation temperature can be 700-1000℃, preferably 800-900℃. The activation time of the carbon raw material in the secondary fluidized bed device can be 5-50 h, preferably 10-40 h.

[0052] The processing time of the primary fluidized bed unit for the char feedstock is less than or equal to the activation time of the secondary fluidized bed unit. This time relationship allows the preheating and particle size screening processes of the primary fluidized bed unit to match the activation process of the secondary fluidized bed unit. This enables the primary fluidized bed unit to complete the pretreatment of subsequent batches of char feedstock while the secondary fluidized bed unit completes the activation of the current batch, thereby reducing the waiting time for the secondary fluidized bed unit to receive feed and improving the operational efficiency between the fluidized bed units and the overall production efficiency.

[0053] The exhaust gas generated during the activation process of the secondary fluidized bed device is filtered by the third filter and at least part of it is reintroduced into the primary fluidized bed device through the return gas pipeline. This is used to preheat and screen the carbon raw materials subsequently added to the primary fluidized bed device, thus forming a cyclical operation process of primary preheating and screening, secondary activation, and secondary exhaust gas return to the primary device.

[0054] The porous carbon material prepared by the fluidized bed apparatus of this invention has a particle size distribution characteristic of Dv10 greater than 5.0 μm and SPAN value less than or equal to 0.8.

[0055] The fluidized bed device provided in this embodiment of the invention includes a primary fluidized bed device and at least one secondary fluidized bed device. The primary fluidized bed device is used to preheat and screen the carbon raw material, and the secondary fluidized bed device is used to activate the carbon raw material processed by the primary fluidized bed device. A material conveying path and a tail gas return path are formed between the primary fluidized bed device and the secondary fluidized bed device, respectively, so that the preheated and screened carbon raw material is conveyed from the primary fluidized bed device to the secondary fluidized bed device, while at least a portion of the tail gas generated by the secondary fluidized bed device is returned to the primary fluidized bed device. Therefore, on the one hand, the heat carried by the exhaust gas from the secondary fluidized bed device can be used to preheat the carbon raw material, reducing the temperature difference between the carbon raw material and the furnace environment when it enters the secondary fluidized bed device, shortening the subsequent heating process and reducing the corresponding energy consumption. At the same time, it reduces the temperature shock to the equipment caused by the direct entry of the lower-temperature carbon raw material into the high-temperature fluidized bed. On the other hand, the carbon raw material can be pre-screened in the primary fluidized bed device to ensure that the carbon raw material entering the secondary fluidized bed device has a more concentrated particle size distribution. This is beneficial for the carbon raw material to adapt to the fluidization and activation conditions of the secondary fluidized bed device, improving the consistency of the activation process and the properties of the resulting porous carbon material, and providing conditions for simplifying the structure of the secondary fluidized bed device.

[0056] In summary, this invention achieves synergy between the preheating, particle size screening, and activation processes of carbon raw materials through the coupling of a primary fluidized bed device and a secondary fluidized bed device. This is beneficial for improving the production efficiency and product consistency of porous carbon preparation, reducing equipment operation and manufacturing costs, and improving the operational stability and service life of the fluidized bed device.

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0058] Example 1 This embodiment provides a method for preparing porous carbon using a two-stage fluidized bed device.

[0059] In the fluidized bed device, the first filter uses a 316 sintered metal filter element with a filtration accuracy of 5 μm, the second filter uses a 316 sintered metal filter element with a filtration accuracy of 1 μm, and the third filter uses a high-temperature resistant filter element with a filtration accuracy of 5 μm.

[0060] Coal-based carbon materials were selected as the carbon raw materials. The particle size of the coal-based carbon materials was tested using a laser particle size analyzer. The Dv10, Dv50, and Dv90 of the resin-based carbon materials were 3.2 μm, 7.9 μm, and 11.7 μm, respectively, with a SPAN value of 1.08.

[0061] Coal-based carbon materials are added to the primary fluidized bed device. The exhaust gas from the operating secondary fluidized bed device is filtered through a third filter and then introduced into the primary fluidized bed device via a return gas pipeline. In this embodiment, the exhaust gas temperature entering the primary fluidized bed device is 800℃, and the apparent gas velocity within the primary fluidized bed body is 0.15 m / s. Apparent gas velocity refers to the ratio of gas volumetric flow rate to the cross-sectional area of ​​the fluidized bed body, i.e., the average gas velocity calculated based on the empty bed cross-sectional area; it is obtained by calculating the ratio of the gas volumetric flow rate through the fluidized bed per unit time to the cross-sectional area of ​​the fluidized bed body.

[0062] Open the valve on the pipeline containing the first filter to allow the dust-laden gas discharged from the primary fluidized bed to pass through it. Particles trapped by the first filter return to the primary fluidized bed, while particles passing through are discharged with the airflow and enter the collection tank. The dust-laden gas entering the collection tank further undergoes gas-solid separation via a second filter. Fine powder trapped by the second filter settles in the collection tank and is then discharged. The returned exhaust gas is used to simultaneously preheat and screen the carbon feedstock. The primary fluidized bed device processes the carbon feedstock for 6 hours, maintaining a stable temperature of approximately 610℃ throughout the process.

[0063] After processing in a primary fluidized bed apparatus, the Dv10, Dv50, and Dv90 of the char feedstock were 5.4 μm, 8.7 μm, and 12.2 μm, respectively, with a SPAN value of 0.78. Compared to before treatment, the Dv10 of the char feedstock increased from 3.2 μm to 5.4 μm, and the SPAN value decreased from 1.08 to 0.78, indicating that the content of small-diameter particles decreased and the particle size distribution became more concentrated after screening in the primary fluidized bed apparatus. A total of 254 kg of fine powder was collected during the particle size screening process, which accounted for approximately 16.2% of the original char feedstock mass.

[0064] After the secondary fluidized bed unit, which is in the feeding state, completes the activation and discharge of the previous batch of material, the preheated and particle size-screened char raw material is transported to the secondary fluidized bed unit through the material pipeline using the positive pressure within the primary fluidized bed unit. During the material transportation process, exhaust gas is returned to the primary fluidized bed unit from another operating secondary fluidized bed unit to continue the operation of the primary fluidized bed unit.

[0065] In this embodiment, the secondary fluidized bed body adopts a constant diameter structure, with a settling zone above the dense phase zone, and no enlarged section relative to the dense phase zone. After the char feedstock enters the secondary fluidized bed device, the heating device is turned on and a gasifying agent containing water vapor and carbon dioxide is introduced into the secondary fluidized bed device to raise the temperature of the char feedstock to 850°C for 2.5 hours. The apparent gas velocity in the secondary fluidized bed body is controlled at 0.12 m / s, and the char feedstock is physically activated at 850°C for 30 hours.

[0066] The exhaust gas generated during the activation process is filtered by the third filter and at least part of it is returned to the primary fluidized bed unit through the return gas pipeline for preheating and particle size screening of subsequent batches of char raw materials. This achieves the recovery and utilization of heat from the activation exhaust gas of the secondary fluidized bed unit and connects the preheating, particle size screening, and activation processes of different batches of char raw materials.

[0067] After activation, the obtained porous carbon material was discharged through a secondary discharge system. Testing revealed that the Dv10, Dv50, and Dv90 of the obtained porous carbon material were 5.3 μm, 8.8 μm, and 12.1 μm, respectively, with a SPAN value of 0.77. This indicates that the relatively concentrated particle size distribution formed after screening in the primary fluidized bed device was largely maintained during subsequent activation, with the Dv10 of the obtained porous carbon material exceeding 5.0 μm and the SPAN value less than 0.8.

[0068] The yield of the porous carbon material obtained in this embodiment is approximately 39%, where the yield is calculated as the ratio of the mass of the obtained porous carbon product to the mass of the original carbon raw material. Further testing of the pore structure of the obtained porous carbon material revealed a specific surface area of ​​1970 m². 2 / g, pore volume 0.83 cm³ 3 / g, with an average pore size of 1.87 nm.

[0069] Comparative Example 1 This comparative example uses a method that does not involve a primary fluidized bed device to prepare porous carbon materials. That is, the carbon raw material is directly fed into a secondary fluidized bed device for activation without preheating and particle size screening in a primary fluidized bed device. Unless otherwise specified, the raw materials, process temperatures, and times used are the same as in Example 1.

[0070] Coal-based char materials are directly added to a secondary fluidized bed reactor. The heating device is activated, and a gasifying agent containing steam and / or carbon dioxide is introduced into the secondary fluidized bed reactor to physically activate the char raw materials. Because a primary fluidized bed reactor is not installed, the char raw materials are not preheated or subjected to particle size screening using the tail gas of the secondary fluidized bed reactor before entering the secondary fluidized bed reactor.

[0071] After activation, the obtained porous carbon material is directly discharged through a two-stage discharge system.

[0072] The Dv10, Dv50 and Dv90 of the obtained porous carbon material were measured to be 3.3 μm, 8.2 μm and 12.6 μm, respectively, and the SPAN value was 1.13.

[0073] Compared with the porous carbon material obtained in Example 1, the porous carbon material obtained in Comparative Example 1 has a smaller Dv10 and a larger SPAN value, resulting in a relatively larger number of small-diameter particles and a relatively wider particle size distribution in the final porous carbon material.

[0074] Furthermore, since this comparative example does not utilize the tail gas generated by the secondary fluidized bed device to preheat the char feedstock, the char feedstock enters the secondary fluidized bed device at a relatively low temperature, requiring a larger heating process within the secondary fluidized bed device. Therefore, compared to the high-temperature feeding method using a primary fluidized bed device for preheating in Example 1, the secondary fluidized bed device in this comparative example requires a longer heating time and consumes more heating energy and inert fluidizing medium.

[0075] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fluidized bed apparatus, characterized in that, The fluidized bed device includes: a primary fluidized bed device and at least one secondary fluidized bed device; The primary fluidized bed device includes: a primary fluidized bed body, a primary feeding system, a primary discharging system, and a primary gas discharge system. The primary fluidized bed device is used for preheating and particle size screening of carbon raw materials. The secondary fluidized bed device includes: a heating device, a secondary fluidized bed body, a secondary feeding system, a secondary discharging system, an air inlet system, and a secondary air outlet system. The secondary fluidized bed device is used to activate the carbon raw material processed by the primary fluidized bed device. The primary discharge system and the secondary feed system are connected by a material pipeline, through which the preheated and particle size-screened carbon raw material is transported to the secondary fluidized bed device. The secondary gas outlet system is connected to the primary fluidized bed device via a return gas pipeline, and at least part of the tail gas generated by the secondary fluidized bed device is introduced into the primary fluidized bed device. The hot gas flow generated by the tail gas is used to preheat and screen the carbon raw material in the primary fluidized bed device.

2. The fluidized bed apparatus according to claim 1, characterized in that, The primary exhaust system includes a first filter, which is disposed on the exhaust path of the primary fluidized bed body. The first filter is used to intercept primary particles in the exhaust gas discharged from the primary fluidized bed body, so that the primary intercepted particles return to the primary fluidized bed body, and the dust-laden gas passes through the first filter and is discharged from the primary fluidized bed body. The dust-laden gas includes primary filtered particles.

3. The fluidized bed apparatus according to claim 2, characterized in that, The primary exhaust system is also connected to a collection tank, which is equipped with a second filter. The primary filter particles that pass through the first filter enter the collection tank with the airflow and are separated into gas and solid by the second filter. The separated secondary filter particles are collected in the collection tank, and the separated gas carries the secondary filter particles through the second filter and is discharged to the exhaust gas treatment system.

4. The fluidized bed apparatus according to claim 3, characterized in that, The primary exhaust system also includes a bypass pipeline; One end of the bypass pipeline is connected to the pipeline between the air outlet of the primary fluidized bed body and the first filter, and the other end of the bypass pipeline is connected to the pipeline between the first filter and the collection tank to form a bypass channel that bypasses the first filter. A first valve is installed on the pipeline at the inlet of the first filter, and a second valve is installed on the bypass pipeline. The dust-laden gas discharged from the primary fluidized bed body is controlled to pass through the first filter or enter the collection tank through the bypass channel by the first valve and the second valve.

5. The fluidized bed apparatus according to claim 1, characterized in that, The secondary gas outlet system includes a third filter, which is disposed on the gas outlet path of the secondary fluidized bed body and is used to filter the exhaust gas generated during the activation process of the secondary fluidized bed device. At least a portion of the exhaust gas filtered by the third filter is introduced into the primary fluidized bed device via the return gas pipeline, and / or discharged to the exhaust gas treatment system via the secondary exhaust gas emission pipeline.

6. The fluidized bed apparatus according to claim 1, characterized in that, Both the primary fluidized bed body and the secondary fluidized bed body include a dense phase zone and a settling zone located above the dense phase zone; The dense phase region and the settling region of the secondary fluidized bed body have the same cross-sectional dimensions, and the secondary fluidized bed body does not have an enlarged section relative to the diameter expansion of the dense phase region.

7. The fluidized bed apparatus according to claim 1, characterized in that, One primary fluidized bed device is connected to 1 to 10 secondary fluidized bed devices; The material pipeline and the return gas pipeline are respectively provided between the primary fluidized bed device and each of the secondary fluidized bed devices. At least one of the secondary fluidized bed devices can pass at least a portion of the tail gas generated during its activation process into the primary fluidized bed device.

8. A method for preparing porous carbon using the fluidized bed apparatus according to any one of claims 1-7, characterized in that, The method includes: The carbon raw material is added to the primary fluidized bed device; The tail gas discharged during the operation of at least one of the secondary fluidized bed devices is introduced into the primary fluidized bed device. The tail gas is used to preheat the carbon raw material and to fluidize and screen the carbon raw material under the action of the airflow formed by the tail gas. The primary filtered particles pass through the first filter and are discharged with the airflow. The first filter retains the primary retained particles and returns them to the primary fluidized bed body. The preheated and particle size-screened carbon raw material is conveyed from the primary fluidized bed device to the secondary fluidized bed device, which is in the feeding state. A gasifying agent containing water vapor and / or carbon dioxide is introduced into the secondary fluidized bed device to activate the carbon raw material and obtain porous carbon material. The exhaust gas generated during the activation process of the secondary fluidized bed device is filtered by the third filter and at least part of it is introduced into the primary fluidized bed device through the return gas pipeline for preheating and particle size screening of the carbon raw material subsequently added to the primary fluidized bed device.

9. The method for preparing porous carbon according to claim 8, characterized in that, The temperature of the exhaust gas introduced into the primary fluidized bed device is 500–800°C; The primary fluidized bed device processes the carbon raw material for 1 to 30 hours, and the secondary fluidized bed device activates the carbon raw material for 5 to 50 hours. The processing time of the primary fluidized bed device for the carbon raw material is less than or equal to the activation time of the secondary fluidized bed device for the carbon raw material.

10. A porous carbon prepared by the method of claim 8 or 9, characterized in that, The porous carbon material has a volume distribution particle size Dv10 greater than 5.0 μm and a particle size distribution SPAN value less than or equal to 0.8.

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