System and method for microwave heating preparation of coal-based activated coke

Abstract

The application discloses a system and method for preparing coal-based activated coke by microwave heating, wherein the system for preparing coal-based activated coke by microwave heating comprises a pre-oxidation device, a microwave carbonization device, a microwave activation device, an activated coke cooling device, a tail gas combustion device and a steam generation device; the feed inlet of the microwave carbonization device is communicated with the discharge outlet of the pre-oxidation device; the feed inlet of the microwave activation device is communicated with the discharge outlet of the microwave carbonization device; the feed inlet of the activated coke cooling device is communicated with the discharge outlet of the microwave activation device; and the inlet of the tail gas combustion device is communicated with the carbonization gas outlet of the microwave carbonization device and the activation gas outlet of the microwave activation device. The system for preparing coal-based activated coke by microwave heating can realize the functions of efficient preparation of coal-based activated coke, recycling of high-temperature waste heat and combustible substances in tail gas and the like, and is favorable for promoting industrialized large-scale production of coal coke and activated coke and energy saving and emission reduction.

Description

Technical Field

[0001] This application belongs to the field of activated coke preparation technology, and in particular relates to a system and method for preparing coal-based activated coke by microwave heating. Background Technology

[0002] Activated coke is an artificial carbon material product with a highly developed pore structure and high specific surface area. Its most significant characteristic is adsorption, which allows it to adsorb various substances from the gas or liquid phase. The technology of using coal as a raw material to manufacture activated coke is gradually being promoted. The carbonization process in activated coke production is essentially the dry distillation of materials under low-temperature conditions. In this process, the material is gradually heated within a certain low-temperature range and in the absence of air. Low-molecular-weight substances in the material first volatilize, and then the coal and coal tar pitch decompose, thereby producing carbonized material and carbonization tail gas. The activation process of activated coke mainly involves modifying the surface morphology and internal structure of the carbonized material at high temperatures using activating agents, thereby improving the performance of the activated coke.

[0003] Traditional activated coke carbonization and activation processes mainly rely on equipment such as Sleip furnaces and moving beds, with heating methods typically including heat conduction, convection, or radiation. These pyrolysis methods suffer from the following problems: temperature gradients exist between the inner and outer layers of the material, leading to uneven reaction; furnace heating and cooling times often last several hours, with time-consuming start-up and shutdown processes wasting significant amounts of heat energy, resulting in low energy utilization; rapid response is not achieved, exhibiting thermal inertia; and the product's added value is low. The heating methods of conventional pyrolysis, to a certain extent, restrict the further development and application of coal pyrolysis technology.

[0004] Microwave pyrolysis technology is an emerging thermal processing technology that has attracted attention in recent years due to its unique heating method and advantages such as ease of control, rapid heating, and uniform heating. Microwave pyrolysis (carbonization) of coal is a thermal decomposition process in which coal is heated as a whole in an electromagnetic field due to dielectric loss, producing coke or semi-coke, coal tar, and coal gas. Compared with traditional pyrolysis, microwave pyrolysis of coal has advantages such as shorter pyrolysis time, higher quality coal tar, and higher content of valuable components in coal gas, making it an important development direction for the clean and graded utilization of coal. Simultaneously, microwave heating can be used to activate carbonized materials, also offering advantages such as shorter activation time and high energy efficiency.

[0005] Currently, microwave heating has also been proposed for use in activated coke (carbon) preparation processes, but it is mainly used for carbonization of coal or biomass, and the resulting coke performance is difficult to meet industrial requirements. Furthermore, the tar in the carbonization gas easily causes blockages and pollution in pipes and microwave heating devices, making cleaning difficult, and the lack of treatment of pollutants in the exhaust gas is detrimental to environmental protection.

[0006] Furthermore, current research on the preparation of activated coke mainly focuses on powdered and columnar activated coke, while there is relatively little research on the systematic preparation of activated coke with large particle size from raw coal. Summary of the Invention

[0007] In view of this, one objective of the present invention is to provide a system for preparing coal-based activated coke using microwave heating. This system utilizes microwave heating to carbonize and activate raw coal particles, and uses a tail gas combustion device to burn the carbonized and activated tail gas to heat feedwater and generate high-temperature steam. Part of the resulting steam is used as an activator in the activated coke activation process, while the other part can be supplied to a power generation unit. This system can achieve efficient preparation of coal-based activated coke, recovery and utilization of high-temperature waste heat and combustibles from tail gas, and is beneficial for promoting the large-scale industrial production of coal-based activated coke and energy conservation and emission reduction.

[0008] The second objective of this invention is to provide a method for preparing coal-based activated coke using microwave heating.

[0009] To achieve the above objectives, a first aspect of the present invention provides a system for preparing coal-based activated coke using microwave heating, comprising:

[0010] Pre-oxidation unit;

[0011] A microwave carbonization device, wherein the inlet of the microwave carbonization device is connected to the outlet of the pre-oxidation device;

[0012] A microwave activation device, wherein the inlet of the microwave activation device is connected to the outlet of the microwave carbonization device;

[0013] An activated coke cooling device, wherein the inlet of the activated coke cooling device is connected to the outlet of the microwave activation device;

[0014] The exhaust gas combustion device has an inlet connected to the carbonization gas outlet of the microwave carbonization device and the activation gas outlet of the microwave activation device.

[0015] The steam generator has a heat medium inlet connected to the outlet of the exhaust gas combustion device and a cold medium inlet connected to the heat exchange medium outlet of the activated coke cooling device. The steam outlet of the steam generator is divided into two paths: one path is connected to the activation gas inlet of the microwave activation device, and the other path is connected to the power generation device.

[0016] In addition, the system for preparing coal-based activated coke by microwave heating according to the above embodiments of the present invention may also have the following additional technical features:

[0017] In some embodiments, the pre-oxidation device is a drying oven or a muffle furnace.

[0018] In some embodiments, both the microwave carbonization device and the microwave activation device are microwave pyrolysis furnaces.

[0019] In some embodiments, the exhaust gas combustion device is an adiabatic combustion furnace.

[0020] In some embodiments, the activated coke cooling device is a shell-and-tube heat exchanger.

[0021] In some embodiments, the steam generating device is a boiler.

[0022] In some embodiments, the power generation device is a steam turbine.

[0023] In some embodiments, the microwave heating system for preparing coal-based activated coke further includes a pretreatment device, which includes a screening device and a drying device connected in sequence, with the outlet of the drying device connected to the inlet of the pre-oxidation device.

[0024] In some embodiments, the screening device is a vibrating screen with a screening particle size of 8-15 mm.

[0025] In some embodiments, the drying device is a dryer or a vacuum drying oven.

[0026] In some embodiments, the power generation device is electrically connected to one or more of the microwave carbonization device, the microwave activation device, the pre-oxidation device, and the pretreatment device.

[0027] In some embodiments, the microwave heating system for preparing coal-based activated coke further includes a tail gas purification device, which includes a dust collector and a desulfurization and denitrification tower connected in sequence, and the inlet of the dust collector is connected to the heat medium inlet of the steam generator.

[0028] In some embodiments, the system for preparing coal-based activated coke by microwave heating further includes a collection device, which is a storage tank.

[0029] To achieve the above objectives, a first aspect of the present invention provides a method for preparing activated coke using a microwave heating system based on the embodiments of this application, comprising:

[0030] Coal particles are exposed to air for pre-oxidation to obtain pre-oxidized coal particles;

[0031] The pre-oxidized coal particles are microwave-heated and carbonized to obtain carbonized material.

[0032] The carbonized material is activated by microwave heating under the action of an activator to obtain activated coke;

[0033] The activated coke is cooled and then discharged.

[0034] In some embodiments, the pre-oxidation temperature is 180-220°C and the pre-oxidation time is 5-15 hours.

[0035] In some embodiments, the carbonization temperature is 500-650℃ and the carbonization time is 1-2h.

[0036] In some embodiments, the activation temperature is 700-850℃ and the activation time is 2-3h.

[0037] In some embodiments, the microwave power during the carbonization and activation process is 2.5-3.5KW, and the microwave frequency is 2-3GHz.

[0038] In some embodiments, the activator is water vapor.

[0039] In some embodiments, the method for preparing coal-based activated coke by microwave heating further includes a step of pre-treating the raw coal to obtain the coal particles before performing the pre-oxidation; the raw coal is low-rank coal; the pre-treatment method is as follows: selecting coal particles with a particle size of 8-15 mm from power plant raw coal and drying them at 105-110℃ for 10-14 h.

[0040] In some embodiments, the method for preparing coal-based activated coke by microwave heating further includes: burning the carbonization tail gas and the activation tail gas and then sending them into a steam generator to heat the water cooled by the activated coke, wherein part of the generated steam is used as an activator in the activation process and the other part is used for steam turbine power generation to supplement the power of at least one of the microwave carbonization device, the microwave activation device, the pre-oxidation device, and the pretreatment device.

[0041] The microwave heating system for preparing coal-based activated coke according to the embodiments of this application can bring the following beneficial effects:

[0042] (1) Because a pre-oxidation device is set up, the coal particles are pre-oxidized before carbonization, which can consume some of the fatty structure in the coal particles, increase the types and quantities of oxygen-containing functional groups, and help regulate the pyrolysis behavior of coal and the physicochemical structure of coal coke.

[0043] (2) No additional pre-oxidant is needed during the pre-oxidation process. For large-diameter coal particles that cannot be directly mixed with the oxidant or uniformly impregnated in the liquid phase, the pre-oxidation time can be extended to achieve long-term and sufficient pre-oxidation using only air, thereby reducing the use of chemical agents and the costs of post-processing and recycling.

[0044] (3) Microwave sources provide energy for the carbonization and activation of coal particles. Taking advantage of the hydrogen-rich characteristics of microwave pyrolysis coal gas, the resulting microwave coking coal gas is rich in hydrogen, which is beneficial to improving the calorific value of the coal gas. Microwave heating is easy to operate and can quickly bring the carbonization and activation zones to the required temperatures. Moreover, the internal temperature of the coal particles rises rapidly, which helps to shorten the start-up time and reaction residence time, and greatly reduces energy consumption.

[0045] (4) The hot water and / or lower temperature steam obtained by heat exchange with activated coke in the activated coke cooling device after carbonization and activation of the exhaust gas after combustion in the exhaust gas combustion device are reheated. Part of the high temperature steam can be used as an activator in the activation process (no need to add chemical activator, reducing the use of chemical agents and the cost of subsequent pollution treatment and recycling), and another part can be provided to the power generation device to generate electricity. The generated electricity can be provided to at least one of the microwave carbonization device, microwave activation device, pre-oxidation device, and pretreatment device as a power supplement, making full use of waste heat and combustibles in the exhaust gas while reducing the power consumption of the system.

[0046] (5) Activated coke can be directly prepared using coal particles with a particle size >8mm from crushed raw coal from power plants. This eliminates the need for crushing, mixing with binders, and briquetting, significantly reducing pretreatment costs. The resulting activated coke is a micro-mesoporous graded activated coke with a specific surface area >500 cm². 2 / g, with large and medium pores accounting for nearly 50%, meeting the requirements for activated coke used in power plant desulfurization and denitrification.

[0047] (6) It is equipped with a tail gas purification device, which can remove dust, desulfurize and denitrate the tail gas generated in the coking process and purify the tail gas.

[0048] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0049] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0050] Figure 1 This is a simplified structural diagram of a system for preparing coal-based activated coke using microwave heating according to an embodiment of this application.

[0051] Figure 2 This is a simplified flowchart of a method for preparing coal-based activated coke using microwave heating according to an embodiment of this application.

[0052] Figure 3 Fourier transform infrared spectra of raw low-rank coal from Fugu, coal particles from Examples 2-6, and coal particles from Comparative Example 1 after pre-oxidation.

[0053] Figure 4 The image shows the pore size distribution curve of the activated coke obtained in Example 6.

[0054] Figure 5 The nitrogen adsorption curve of the activated carbon obtained in Example 6 is shown.

[0055] Figure label:

[0056] 1-Pre-oxidation device; 2-Microwave carbonization device; 3-Microwave activation device; 4-Activated coke cooling device; 5-Tail gas combustion device; 6-Steam generator; 7-Power generation device; 8-Screening device; 9-Drying device; 10-Tail gas purification device; 11-Collection device. Detailed Implementation

[0057] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0058] The system and method for preparing coal-based activated coke by microwave heating according to embodiments of the present invention will be described below with reference to the accompanying drawings.

[0059] Figure 1 This is a simplified structural diagram of a system for preparing coal-based activated coke using microwave heating according to an embodiment of this application.

[0060] like Figure 1 As shown, the system for preparing coal-based activated coke using microwave heating according to an embodiment of this application includes a pre-oxidation device 1, a microwave carbonization device 2, a microwave activation device 3, an activated coke cooling device 4, a tail gas combustion device 5, a steam generator 6, and a power generation device 7. The inlet of the microwave carbonization device 2 is connected to the outlet of the pre-oxidation device 1; the inlet of the microwave activation device 3 is connected to the outlet of the microwave carbonization device 2; the inlet of the activated coke cooling device 4 is connected to the outlet of the microwave activation device 3; the inlet of the tail gas combustion device 5 is connected to the carbonization gas outlet of the microwave carbonization device 2 and the activation gas outlet of the microwave activation device 3; the heat medium inlet of the steam generator 6 is connected to the outlet of the tail gas combustion device 5, and the cold medium inlet of the steam generator 6 is connected to the heat exchange medium outlet of the activated coke cooling device 4; the steam outlet of the steam generator 6 is divided into two paths, one path is connected to the activation gas inlet of the microwave activation device 3, and the other path is connected to the power generation device 7.

[0061] The microwave heating system for preparing coal-based activated coke according to the embodiments of this application can bring the following beneficial effects:

[0062] (1) Because a pre-oxidation device is set up, the coal particles are pre-oxidized before carbonization, which can consume some of the fatty structure in the coal particles, increase the types and quantities of oxygen-containing functional groups, and help regulate the pyrolysis behavior of coal and the physicochemical structure of coal coke.

[0063] (2) No additional pre-oxidant is needed during the pre-oxidation process. For large-diameter coal particles that cannot be directly mixed with the oxidant or uniformly impregnated in the liquid phase, the pre-oxidation time can be extended to achieve long-term and sufficient pre-oxidation using only air, thereby reducing the use of chemical agents and the costs of post-processing and recycling.

[0064] (3) Microwave sources provide energy for the carbonization and activation of coal particles. Taking advantage of the hydrogen-rich characteristics of microwave pyrolysis coal gas, the resulting microwave coking coal gas is rich in hydrogen, which is beneficial to improving the calorific value of the coal gas. Microwave heating is easy to operate and can quickly bring the carbonization and activation zones to the required temperatures. Moreover, the internal temperature of the coal particles rises rapidly, which helps to shorten the start-up time and reaction residence time, and greatly reduces energy consumption.

[0065] (4) The hot water and / or lower temperature steam obtained by exchanging heat with activated coke in the activated coke cooling device after the carbonized and activated tail gas after combustion in the tail gas combustion device are reheated. Part of the high temperature steam can be used as an activator in the activation process (no need to add chemical activators, reducing the use of chemical agents and the cost of subsequent pollution treatment and recycling), and the other part can be provided to the power generation device to generate electricity, making full use of waste heat and combustibles in tail gas and reducing energy consumption.

[0066] In some embodiments, the pre-oxidation device 1 may be a drying box or a muffle furnace for pre-oxidizing coal particles.

[0067] In some embodiments, both the microwave carbonization device 2 and the microwave activation device 3 employ microwave pyrolysis furnaces, used for carbonizing pre-oxidized coal particles and for further activating the carbonized material, respectively. As a non-limiting example, the microwave power of the microwave carbonization device 2 and the microwave activation device 3 is 2.5-3.5 kW, and the microwave frequency is 2-3 GHz. As a possible example, the microwave power of the microwave carbonization device 2 and the microwave activation device 3 is 3 kW, and the microwave frequency is 2.45 GHz.

[0068] In some embodiments, the exhaust gas combustion device 5 may be an adiabatic combustion furnace. In this application, the exhaust gas combustion device is used to burn carbonized exhaust gas and activated exhaust gas, removing tar from the carbonized exhaust gas and water gas, etc., from the activated exhaust gas.

[0069] In some embodiments, the activated coke cooling device 4 may be a shell-and-tube heat exchanger or the like. In this application, the activated coke cooling device is used to cool the activated coke produced by the microwave activation device, and the cooling medium used for heat exchange with the activated coke in the activated coke cooling device may be cold water. In some embodiments, the system for preparing coal-based activated coke by microwave heating further includes a collection device 11 for collecting the cooled activated coke, and the collection device 11 includes, but is not limited to, a storage tank or the like.

[0070] In some embodiments, the steam generating device 6 is a boiler, such as a counter-current indirect heat exchange steam boiler. In this application, the steam generating device is used to produce high-temperature steam. High-temperature exhaust gas from the exhaust gas combustion device is exchanged with hot water and / or lower-temperature steam from the activated coke cooling device via a counter-current indirect heat exchange process to obtain high-temperature steam. Part of the high-temperature steam can be used as an activator for the microwave activation device, and another part can be used for power generation in a subsequent power generation device. In some embodiments, the power generation device 7 is a steam turbine. In some embodiments, the power generation device 7 is electrically connected to one or more of the microwave carbonization device 2, microwave activation device 3, pre-oxidation device 1, and pretreatment device. The power generation device uses high-temperature steam to generate electricity, which can provide supplementary power to one or more of the microwave carbonization device, microwave activation device, pre-oxidation device, and pretreatment device as needed.

[0071] In some embodiments, in order to obtain raw coal particles of the target particle size and remove moisture from the coal particles, the microwave heating system for preparing coal-based activated coke further includes a pretreatment device, which includes a screening device 8 and a drying device 9 connected in sequence. The screening device 8 can be a vibrating screen with a screening particle size >8mm, preferably 8-15mm. The drying device 9 is a dryer or a vacuum drying box used to dry the coal particles and remove moisture. The outlet of the drying device 9 is connected to the inlet of the pre-oxidation device 1.

[0072] In some embodiments, the microwave heating system for preparing coal-based activated coke further includes a tail gas purification device 10 for purifying the tail gas after combustion in the tail gas combustion device. Preferably, the tail gas purification device 10 includes a dust collector and a desulfurization and denitrification tower connected in sequence, with the inlet of the dust collector connected to the heat medium inlet of the steam generator 6. The dust collector may include, but is not limited to, a bag filter, an electrostatic precipitator, etc., and the desulfurization and denitrification tower may be a wet flue gas desulfurization and denitrification tower, etc.

[0073] It should be noted that in the microwave heating system for preparing coal-based activated coke in this application embodiment, the connection between two adjacent components, such as the "pre-oxidation device" and the "microwave carbonization device", or the "microwave carbonization device" and the "microwave activation device", can be through pipeline connection, belt drive, etc.

[0074] When the microwave heating system for preparing coal-based activated coke according to the embodiments of this application is working, such as Figure 1As shown, the screening device 8 screens coal particles with a diameter >8mm from the crushed raw coal of the power plant, and then sends them to the drying device 9 to dry and remove moisture. The dried coal particles first enter the microwave carbonization device 2 for microwave heating and carbonization, and then enter the microwave activation device 3 for microwave heating and activation under the action of an activator. The carbonization tail gas and the activation tail gas are collected and combined and sent to the tail gas combustion device 5 for combustion. The activated coke enters the activated coke cooling device 4 for indirect heat exchange with cold water (such as boiler feedwater) to prepare hot water and / or low-temperature steam. The cooled activated coke is collected and stored in a collection device for later use. The hot water and / or low-temperature steam enters the steam generator 6 and is heated by the tail gas after combustion in the tail gas combustion device 5 to obtain high-temperature steam. Part of the high-temperature steam enters the microwave activation device 3 as an activator to participate in the activation reaction, and the other part can be provided to the power generation device 7 to generate electricity. The generated electricity can be supplied to one or more of the microwave carbonization device, microwave activation device, pre-oxidation device, and pretreatment device as a power supplement. The exhaust gas, after being cooled by heat exchange in the steam generator 6, enters the exhaust gas purification device 10 for dust removal, desulfurization, and denitrification, and is finally discharged into the atmosphere.

[0075] The method for preparing coal-based activated coke by microwave heating according to the embodiments of this application can be applied to the system for preparing coal-based activated coke by microwave heating according to the embodiments of this application. Figure 2 This is a simplified flowchart of a method for preparing coal-based activated coke using microwave heating according to an embodiment of this application. Figure 2 As shown, the preparation method includes:

[0076] S100. Expose coal particles to air for pre-oxidation to obtain pre-oxidized coal particles.

[0077] In some embodiments, the pre-oxidation temperature is 180-220°C, and the pre-oxidation time is 5-15 hours. As non-limiting examples, the pre-oxidation temperature is 180°C, 190°C, 200°C, 210°C, or 220°C, and the pre-oxidation time is 5 hours, 8 hours, 12 hours, or 15 hours, etc.

[0078] It should be noted that pre-oxidizing coal particles before carbonization can consume some of the fatty structures in the coal particles, increase the types and quantities of oxygen-containing functional groups, and is beneficial for controlling coal pyrolysis behavior and the physicochemical structure of coal char. Furthermore, air is used directly as the pre-oxidation component, eliminating the need for additional oxidants. For large-diameter coal particles that cannot be directly mixed with oxidants or uniformly impregnated in the liquid phase, prolonged and thorough pre-oxidation using only air can be achieved by extending the pre-oxidation time, reducing the use of chemical reagents and the costs of subsequent processing and recovery.

[0079] In some embodiments, the method for preparing coal-based activated coke by microwave heating further includes a step of pretreating the raw coal to obtain coal particles before pre-oxidation. Here, the raw coal can be low-rank coal, including but not limited to one or more of non-caking coal, weakly caking coal, long-flame coal, and low-rank lignite. It should be noted that in this application, the raw coal does not need to be crushed; coal particles with a screening diameter of 8-15 mm from power plant raw coal are directly selected for coking. The pretreatment method for the raw coal includes, but is not limited to, drying the coal particles with a screening diameter of 8-15 mm from power plant raw coal at 105-110℃ for 10-14 hours to remove moisture. As a possible example, the drying temperature is 105℃ and the drying time is 12 hours.

[0080] S200: Microwave heating is used to carbonize the pre-oxidized coal particles to obtain carbonized material.

[0081] In some embodiments, the carbonization temperature is 500-650℃, including but not limited to 500℃, 550℃, 600℃ or 650℃; the carbonization time is 1-2h, including but not limited to 1h, 1.5h or 2h.

[0082] In some embodiments, the microwave power during carbonization is 2.5-3.5KW, including but not limited to 2.5KW, 3KW or 3.5KW; the microwave frequency is 2-3Ghz, including but not limited to 2Ghz, 2.45Ghz or 3Ghz.

[0083] S300: The carbonized material is activated by microwave heating under the action of an activator to obtain activated coke.

[0084] In some embodiments, the activation temperature is 700-850℃, including but not limited to 700℃, 750℃, 800℃ or 850℃; the activation time is 2-3h, including but not limited to 2h, 2.5h or 3h.

[0085] In some embodiments, the microwave power during activation is 2.5-3.5KW, including but not limited to 2.5KW, 3KW or 3.5KW; the microwave frequency is 2-3Ghz, including but not limited to 2Ghz, 2.45Ghz or 3Ghz.

[0086] In some embodiments, the activator may be water vapor.

[0087] S400: The activated coke is cooled and then discharged.

[0088] In some embodiments, the method for preparing coal-based activated coke by microwave heating further includes: burning carbonization tail gas and activation tail gas and then sending them into a steam generator 6 to heat the water cooled by the activated coke. Part of the generated steam is used as an activator in the activation process of step S300, and the other part is used for steam turbine power generation to supplement the power of at least one of the microwave carbonization device 2, microwave activation device 3, pre-oxidation device 1, and pretreatment device.

[0089] It should be noted that this application uses steam generated by a steam generator as the activator in the activation process, eliminating the need for additional chemical activators, which can reduce the use of chemical agents and the costs of subsequent pollution treatment and recycling.

[0090] The system and method for preparing coal-based activated coke by microwave heating according to this application are described below with reference to specific embodiments.

[0091] I. Examples and Comparative Examples

[0092] The industrial and elemental analysis results of the low-rank coal from Fugu involved in the examples and comparative examples are shown in Table 1.

[0093] Table 1. Industrial and elemental analysis results of low-rank coal from Fugu.

[0094]

[0095] Note: * in Table 1 indicates that the oxygen content was obtained by subtraction.

[0096] Example 1

[0097] like Figure 1As shown, the microwave heating system for preparing coal-based activated coke in this embodiment includes a screening device 8, a drying device 9, a pre-oxidation device 1, a microwave carbonization device 2, a microwave activation device 3, an activated coke cooling device 4, and a collection device 11 connected in sequence. The screening device 8 is a vibrating screen with a particle size of 8-15 mm; the drying device 9 is a muffle furnace; the activated coke cooling device 4 is a shell-and-tube heat exchanger; and the collection device 11 is a storage tank. Both the microwave carbonization device 2 and the microwave activation device 3 are commercially available microwave pyrolysis furnaces with a microwave power of 3 kW and a microwave frequency of 2.45 GHz. The carbonization gas outlet of the microwave carbonization device 2 and the activation gas outlet of the microwave activation device 3 are... The gas outlet is connected to the inlet of the tail gas combustion device 5; the tail gas combustion device is an adiabatic combustion furnace, and the outlet of the tail gas combustion device 5 is connected to the heat medium inlet of the steam generator 6, which is a steam boiler. The heat medium outlet of the steam generator 6 is connected to the inlet of the tail gas purification device 10, which includes a bag filter and a wet flue gas desulfurization and denitrification tower connected in sequence. The cold medium inlet of the steam generator 6 is connected to the heat exchange medium outlet of the activated coke cooling device 4. The steam outlet of the steam generator 6 is divided into two paths: one path is connected to the activation gas inlet of the microwave activation device 3, and the other path is connected to the power generation device 7, which is a steam turbine. The power generation device 7 is electrically connected to the microwave carbonization device 2, microwave activation device 3, pre-oxidation device 1, screening device 8, and drying device 9 via cables, and each cable is equipped with a switch.

[0098] In this embodiment, the system for preparing coal-based activated coke using microwave heating operates by using a screening device 8 to screen coal particles with a particle size of 8-15mm from the crushed raw coal of the power plant. The particles are then sent to a drying device 9 to remove moisture. After drying, the coal particles first enter a microwave carbonization device 2 for microwave carbonization, and then enter a microwave activation device 3 for microwave activation under the action of an activator. The carbonization tail gas and activation tail gas are collected and combined, and then sent to a tail gas combustion device 5 for combustion. The activated coke then enters an activated coke cooling device 4 for indirect heat exchange with cold water (such as boiler feedwater) to prepare hot water. The cooled activated coke is collected and stored in a collection device for later use. The hot water enters a steam generator 6, where it is heated by the tail gas from combustion in the tail gas combustion device 5 to obtain high-temperature steam at 530-550℃. Part of the high-temperature steam enters the microwave activation device 3 as an activator to participate in the activation reaction, while the other part can be supplied to a power generation device 7 to generate electricity. The generated electricity can be supplied to one or more of the microwave carbonization device, microwave activation device, pre-oxidation device, screening device 8, and drying device 9 as a power supplement, as needed. The exhaust gas, after being cooled by heat exchange in the steam generator 6, enters the exhaust gas purification device 10 for dust removal, desulfurization, and denitrification, and is finally discharged into the atmosphere.

[0099] Example 2

[0100] The method for preparing coal-based activated coke by microwave heating in this embodiment uses the system for preparing coal-based activated coke by microwave heating in Example 1, and includes the following steps:

[0101] (1) Use screening device 8 to screen coal particles with a particle size of 8-15mm from the crushed low-rank coal of the power plant in Fugu.

[0102] (2) Dry the coal particles obtained after screening in step (1) at 105℃ for 12 hours to remove moisture;

[0103] (3) The dried coal particles from step (2) were pre-oxidized in air at 200°C for 1 hour;

[0104] (4) The coal particles pre-oxidized in step (3) are fed into the carbonization zone of the microwave carbonization device for microwave heating and carbonization. The carbonization temperature is 580℃, the carbonization time is 1.5h, the microwave power is 3KW, and the microwave frequency is 2.45Ghz.

[0105] (5) The carbonized material obtained in step (4) is sent to the activation zone of the microwave activation device for microwave heating activation. The activation temperature is 780℃, the activation time is 2.5h, the microwave power is 3KW, and the microwave frequency is 2.45Ghz.

[0106] (6) After the activated coke obtained in step (5) is cooled, it is discharged and collected. After heat exchange, the cooling water at 60-80°C is sent to the steam generator. At the same time, the activated tail gas and carbonized tail gas are collected and sent to the tail gas combustion device for combustion to remove tar and water gas. Then, the high-temperature tail gas at 800-850°C discharged from the tail gas combustion device is sent to the steam generator as a heat medium.

[0107] (7) The cooling water after heat exchange is heated by the high-temperature exhaust gas discharged by the exhaust gas combustion device and converted into 530-550 high-temperature steam. Part of the high-temperature steam enters the microwave activation device 3 as an activator to participate in the activation reaction, and the other part is supplied to the power generation device 7 to generate electricity. The generated electricity can be supplied to one or more of the microwave carbonization device, microwave activation device, pre-oxidation device, screening device 8, and drying device 9 as power supplement as needed.

[0108] (8) The exhaust gas from the combustion device 5, which is cooled by heat exchange in the steam generator 6, enters the exhaust gas purification device 10 for dust removal, desulfurization, denitrification, etc., and is finally discharged into the atmosphere.

[0109] Example 3

[0110] The method for preparing coal-based activated coke by microwave heating in this embodiment uses the system for preparing coal-based activated coke by microwave heating in Example 1, and includes the following steps:

[0111] (1) Use screening device 8 to screen coal particles with a particle size of 8-15mm from the crushed low-rank coal of the power plant in Fugu.

[0112] (2) Dry the coal particles obtained after screening in step (1) at 105℃ for 12 hours to remove moisture;

[0113] (3) Expose the dried coal particles from step (2) to air at 200°C for 3 hours for pre-oxidation;

[0114] (4) The coal particles pre-oxidized in step (3) are fed into the carbonization zone of the microwave carbonization device for microwave heating and carbonization. The carbonization temperature is 500℃, the carbonization time is 2h, the microwave power is 3KW, and the microwave frequency is 2.45Ghz.

[0115] (5) The carbonized material obtained in step (4) is sent to the activation zone of the microwave activation device for microwave heating activation. The activation temperature is 700℃, the activation time is 3h, the microwave power is 3KW, and the microwave frequency is 2.45Ghz.

[0116] (6) After the activated coke obtained in step (5) is cooled, it is discharged and collected. After heat exchange, the cooling water at 60-80°C is sent to the steam generator. At the same time, the activated tail gas and carbonized tail gas are collected and sent to the tail gas combustion device for combustion to remove tar and water gas. Then, the high-temperature tail gas at 800-850°C discharged from the tail gas combustion device is sent to the steam generator as a heat medium.

[0117] (7) The cooling water after heat exchange is heated by the high-temperature exhaust gas discharged by the exhaust gas combustion device and converted into high-temperature steam at 530-550°C. Part of the high-temperature steam enters the microwave activation device 3 as an activator to participate in the activation reaction, and the other part is supplied to the power generation device 7 to generate electricity. The generated electricity can be supplied to one or more of the microwave carbonization device, microwave activation device, pre-oxidation device, screening device 8, and drying device 9 as power supplement as needed.

[0118] (8) The exhaust gas from the combustion device 5, which is cooled by heat exchange in the steam generator 6, enters the exhaust gas purification device 10 for dust removal, desulfurization, denitrification, etc., and is finally discharged into the atmosphere.

[0119] Example 4

[0120] The method for preparing coal-based activated coke by microwave heating in this embodiment uses the system for preparing coal-based activated coke by microwave heating in Example 1, and includes the following steps:

[0121] (1) Use screening device 8 to screen coal particles with a particle size of 8-15mm from the crushed low-rank coal of the power plant in Fugu.

[0122] (2) Dry the coal particles obtained after screening in step (1) at 105℃ for 12 hours to remove moisture;

[0123] (3) Expose the dried coal particles from step (2) to air at 200°C for 5 hours for pre-oxidation;

[0124] (4) The coal particles pre-oxidized in step (3) are fed into the carbonization zone of the microwave carbonization device for microwave heating and carbonization. The carbonization temperature is 650℃, the carbonization time is 1h, the microwave power is 3KW, and the microwave frequency is 2.45Ghz.

[0125] (5) The carbonized material obtained in step (4) is sent to the activation zone of the microwave activation device for microwave heating activation. The activation temperature is 850℃, the activation time is 2h, the microwave power is 3KW, and the microwave frequency is 2.45Ghz.

[0126] (6) After the activated coke obtained in step (5) is cooled, it is discharged and collected. After heat exchange, the cooling water at 60-80°C is sent to the steam generator. At the same time, the activated tail gas and carbonized tail gas are collected and sent to the tail gas combustion device for combustion to remove tar and water gas. Then, the high-temperature tail gas at 800-850°C discharged from the tail gas combustion device is sent to the steam generator as a heat medium.

[0127] (7) The cooling water after heat exchange is heated by the high-temperature exhaust gas discharged by the exhaust gas combustion device and converted into high-temperature steam at 530-550°C. Part of the high-temperature steam enters the microwave activation device 3 as an activator to participate in the activation reaction, and the other part is supplied to the power generation device 7 to generate electricity. The generated electricity can be supplied to one or more of the microwave carbonization device, microwave activation device, pre-oxidation device, screening device 8, and drying device 9 as power supplement as needed.

[0128] (8) The exhaust gas from the combustion device 5, which is cooled by heat exchange in the steam generator 6, enters the exhaust gas purification device 10 for dust removal, desulfurization, denitrification, etc., and is finally discharged into the atmosphere.

[0129] Example 5

[0130] This embodiment is basically the same as embodiment 2, except that the pre-oxidation time in step (3) is 10h.

[0131] Example 6

[0132] This embodiment is basically the same as embodiment 2, except that: the pre-oxidation time in step (3) is 15h; the carbonization temperature in step (4) is 600℃ and the carbonization time is 2h; the activation temperature in step (5) is 800℃ and the activation time is 3h.

[0133] Comparative Example 1

[0134] This comparative example is basically the same as Example 6, except that the pre-oxidation time in step (3) is 30h.

[0135] II. Performance Testing

[0136] 1. Pre-oxidation effect

[0137] 10g of raw low-rank coal from Fugu, coal particles from Examples 2-6 and Comparative Example 1 after pre-oxidation in step (3) were weighed separately, and scanned using a Fourier transform infrared spectrometer. The raw low-rank coal from Fugu, coal particles from Examples 2-6 and Comparative Example 1 after pre-oxidation in step (3) were labeled as raw coal sample, Y1 sample, Y3 sample, Y5 sample, Y10 sample, Y15 sample, and Y30 sample, respectively. The test results are as follows: Figure 3 As shown.

[0138] from Figure 3 It can be seen from the data that the raw coal samples were at 2920, 2850, and 1438 cm⁻¹ -1 Nearby, relatively obvious characteristic peaks appeared, indicating that the raw low-rank coal from Fugu contains abundant aliphatic CH compounds. After 1 hour of high-temperature air pre-oxidation at 200℃, sample Y1 showed peaks at 2920, 2850, and 1438 cm⁻¹. -1 The characteristic peaks in the vicinity did not change significantly, indicating that the 1-hour pre-oxidation treatment had little effect on the structure of the coal. The Y3 sample showed peaks at 2920 and 2850 cm⁻¹. -1 The characteristic peaks nearby are significantly weakened, at 1438 cm⁻¹ -1 The characteristic peaks in the vicinity also weakened, indicating that some of the fatty structures in the coal began to be consumed after a certain period of pre-oxidation treatment. When the oxidation time was extended to 5 hours, the Y5 sample showed peak values ​​at 2920, 2850, and 1438 cm⁻¹. -1 The nearby characteristic peaks have largely disappeared, and at 1709 cm⁻¹... -1 New characteristic peaks appeared nearby, in the CO functional group region (mainly located at 1300-950 cm⁻¹). -1 Significant changes were also observed in the FTIR spectrum (within a certain range), indicating that after a sufficiently long pre-oxidation treatment, the fatty structure in the coal was completely consumed, and different types of oxygen-containing functional groups were generated. Compared with sample Y5, the spectrum of sample Y10 showed slight changes in the oxygen-containing functional group region, possibly due to changes in the types and quantities of oxygen-containing functional groups caused by the extended pre-oxidation time. Comparing the FTIR spectra of Y15 and Y30, the differences between them were no longer significant, indicating that the composition and structure of the coal were basically stable after pre-oxidation for more than 15 hours.

[0139] 2. Activated Coke Performance

[0140] The pore structure and adsorption performance of the activated coke obtained after cooling in Example 6 were tested. The pore structure parameters are shown in Table 2, and the nitrogen adsorption curves are shown in Table 3. Figure 4 As shown, the pore size distribution curve is as follows: Figure 5 As shown.

[0141] Table 2. Pore structure parameters of activated coke in Example 6

[0142]

[0143] Combined with Table 2, Figure 4 , Figure 5 It can be seen that the activated carbon prepared in Example 6 is a micro-mesoporous hierarchical activated carbon with a specific surface area >500 cm². 2 / g, with large and medium pores accounting for nearly 50%.

[0144] In summary, the system and method for preparing coal-based activated coke using microwave heating according to the embodiments of this application address the problems of long preparation time, high energy consumption, and high-temperature waste heat utilization in the existing large-scale activated coke preparation process. It integrates functions such as microwave carbonization, activation, tail gas treatment, and waste heat utilization, and has certain guiding significance for the industrial continuous and efficient preparation of coal-based activated coke.

[0145] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0146] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0147] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0148] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0149] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0150] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing coal-based activated coke using microwave heating, characterized in that, The process involves using a microwave heating system to prepare coal-based activated coke, the system comprising: Pre-oxidation unit; A microwave carbonization device, wherein the feed inlet of the microwave carbonization device is connected to the discharge outlet of the pre-oxidation device, and is used for microwave heating carbonization; A microwave activation device, wherein the inlet of the microwave activation device is connected to the outlet of the microwave carbonization device; An activated coke cooling device, wherein the inlet of the activated coke cooling device is connected to the outlet of the microwave activation device; The exhaust gas combustion device has an inlet connected to the carbonization gas outlet of the microwave carbonization device and the activation gas outlet of the microwave activation device. A steam generator is provided, wherein the heat medium inlet of the steam generator is connected to the outlet of the exhaust gas combustion device, and the cold medium inlet of the steam generator is connected to the heat exchange medium outlet of the activated coke cooling device; the steam outlet of the steam generator is divided into two paths, one of which is connected to the activation gas inlet of the microwave activation device, and the other of which is connected to the power generation device. The system for preparing coal-based activated coke by microwave heating also includes a pretreatment device, which includes a screening device with a screening particle size of 8-15 mm. The method for preparing coal-based activated coke by microwave heating includes: The raw coal is pretreated to obtain coal particles, wherein the raw coal is low-rank coal; Coal particles are exposed to air for pre-oxidation to obtain pre-oxidized coal particles; The pre-oxidized coal particles are microwave-heated and carbonized to obtain carbonized material. The carbonized material is activated by microwave heating under the action of an activator to obtain activated coke; The activated coke is cooled and then discharged. The carbonization temperature is 550-650℃, the activation temperature is 700-800℃, and the activator is water vapor; The microwave power during the carbonization and activation process is 2.5-3.5KW, and the microwave frequency is 2-3Ghz; The pre-oxidation temperature is 180-220℃, and the pre-oxidation time is 5-15h; The carbonization time is 1-2 hours; The activation time is 2-3 hours; The activated carbon is a micro-mesoporous hierarchical activated carbon with a specific surface area >500 cm². 2 / g, with large and medium pores accounting for 51.23%.

2. The method for preparing coal-based activated coke by microwave heating according to claim 1, characterized in that, The pre-oxidation device is a drying oven or a muffle furnace.

3. The method for preparing coal-based activated coke by microwave heating according to claim 1, characterized in that, Both the microwave carbonization device and the microwave activation device are microwave pyrolysis furnaces.

4. The method for preparing coal-based activated coke by microwave heating according to claim 1, characterized in that, The exhaust gas combustion device is an adiabatic combustion furnace.

5. The method for preparing coal-based activated coke by microwave heating according to claim 1, characterized in that, The activated coke cooling device is a shell-and-tube heat exchanger. And / or, the steam generating device is a boiler; And / or, the power generation device is a steam turbine.

6. The method for preparing coal-based activated coke by microwave heating according to claim 1, characterized in that, The pretreatment device further includes a drying device, the inlet of which is connected to the outlet of the screening device; the outlet of the drying device is connected to the inlet of the pre-oxidation device.

7. The method for preparing coal-based activated coke by microwave heating according to claim 6, characterized in that, The screening device is a vibrating screen; And / or, the drying device is a vacuum drying oven.

8. The method for preparing coal-based activated coke by microwave heating according to claim 1 or 6, characterized in that, The microwave heating system for preparing coal-based activated coke also includes a tail gas purification device, which includes a dust collector and a desulfurization and denitrification tower connected in sequence. The inlet of the dust collector is connected to the heat medium outlet of the steam generator. And / or, the microwave heating system for preparing coal-based activated coke further includes a collection device, which is a storage tank.

9. The method for preparing coal-based activated coke by microwave heating according to claim 8, characterized in that, The pretreatment method is as follows: select coal particles with a screening diameter of 8-15mm from raw coal from power plants and dry them at 105-110℃ for 10-14h. And / or, the method for preparing coal-based activated coke by microwave heating further includes: burning carbonization tail gas and activation tail gas and then sending them into a steam generator to heat the water cooled by the activated coke, with part of the generated steam used as an activator in the activation process and the other part used for steam turbine power generation to supplement the power of at least one of the microwave carbonization device, the microwave activation device, the pre-oxidation device, and the pretreatment device.

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