System and method for producing carbon material and co-producing natural gas by oxygen-enriched rotary furnace pyrolysis gasification

Abstract

This invention discloses a system and method for producing carbon materials and co-producing natural gas through pyrolysis and gasification in an oxygen-enriched rotary kiln. The system uses raw coal as raw material, which is pretreated and dried before being fed into an oxygen-enriched rotary unit. Within the unit, oxygen-enriched gas and steam are precisely and segmented to achieve continuous and synergistic conversion of pyrolysis, activation, and gasification. The continuous rotation of the rotary kiln ensures uniform material mixing and efficient heat and mass transfer. The system simultaneously produces two high-value products: crude coal gas rich in H2 and CO undergoes conversion, green hydrogen coupling, purification, and methanation to produce synthetic natural gas or liquefied natural gas; while the fully activated solid carbon material is cooled and screened to obtain high-quality carbon materials. Furthermore, the waste heat from the oxygen-enriched combustion in the rotary kiln is used to generate steam in a waste heat boiler to meet the preheating requirements of raw coal drying and methanation reactions. The exothermic reaction from methanation is recovered through a heat exchanger and used to heat the raw gas, significantly reducing external energy consumption.

Description

Technical Field

[0001] This invention relates to the field of coal resource grading and conversion and clean energy technology, specifically to an oxygen-enriched rotary kiln pyrolysis gasification system and method for producing carbon materials and co-producing natural gas. Background Technology

[0002] Coal, as a crucial basic energy source and chemical raw material in my country, plays a vital role in ensuring energy security and achieving sustainable development through its clean and efficient utilization. Traditional coal utilization methods (such as direct combustion) suffer from low energy efficiency, heavy pollution, and limited product diversification. While existing coal fractionation technologies can simultaneously yield tar, coal gas, and semi-coke, the processes are complex, and the subsequent processing of semi-coke yields low added value, making it difficult to maximize resource value. Furthermore, existing coal conversion technologies often consider solid and gaseous products separately, lacking system integration. How to achieve the cascade conversion of coal within a single facility, obtaining high-quality carbon materials while efficiently converting volatiles from pyrolysis and gasification into synthetic natural gas, is a pressing technical challenge in this field.

[0003] In the field of coal conversion, oxygen-enriched technology has attracted attention due to its ability to improve reaction intensity, reduce flue gas volume, and enhance syngas quality. Rotary furnaces, as mature industrial equipment, offer advantages such as uniform material mixing, good heat and mass transfer, and continuous production capabilities, and are widely used in metallurgy, chemical industry, and other sectors. However, current technologies have not fully utilized the advantages of rotary furnaces to organically combine oxygen-enriched conditions with the pyrolysis, gasification, and activation processes of coal, enabling the synergistic production of high-value-added carbon materials and clean energy products within a continuous system.

[0004] Therefore, how to develop a system that can deeply integrate oxygen-enriched rotary kilns with pyrolysis-gasification-activation processes and achieve co-production of carbon materials and natural gas is an urgent problem that needs to be solved. Summary of the Invention

[0005] To address the technical problems existing in the prior art, the first objective of this invention is to provide an oxygen-enriched rotary kiln pyrolysis gasification system for the co-production of carbon materials and natural gas. This system uses an oxygen-enriched rotary kiln unit as the core reactor, integrating the pyrolysis, gasification, and activation processes of coal into a single unit for coordinated production. Simultaneously, it produces crude coal gas rich in H2 and CO, and high-porosity carbon material intermediates. The crude coal gas is converted into synthetic natural gas or liquefied natural gas after conversion, green hydrogen coupling, purification, and methanation treatment. The carbon material intermediates are cooled and post-treated to obtain high-quality carbon material products.

[0006] The second objective of this invention is to provide a method for producing carbon materials and co-producing natural gas using the above-mentioned oxygen-enriched rotary kiln pyrolysis gasification system. By precisely introducing oxygen-enriched gas and steam in stages, and controlling the temperature and reaction atmosphere of the pyrolysis zone and the gasification activation zone, the method achieves graded conversion of coal and cascaded utilization of energy, ultimately obtaining two high-value-added products: carbon materials and natural gas.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A system for producing carbon materials and co-producing natural gas via oxygen-enriched rotary kiln pyrolysis gasification includes: The upstream pretreatment unit is used to crush, screen and dry the raw coal, and then transport the processed raw coal to the oxygen-enriched rotary unit. An oxygen-enriched rotary unit is used to pyrolyze, gasify, and activate raw coal to generate crude coal gas and carbon materials. The oxygen-enriched rotary unit includes: A rotatable horizontal cylinder has a feed inlet for receiving raw coal and an air inlet for receiving oxygen-enriched gas at its feed end, and an exhaust outlet for discharging crude coal gas and an exhaust outlet for discharging carbon materials at its discharge end. The inner cylinder is coaxially disposed inside the horizontal cylinder and is used for fuel combustion and high-temperature flue gas passage to indirectly heat the material inside the horizontal cylinder. Multiple air inlet pipes are provided at the discharge end of the horizontal cylinder and extend axially into the interior of the horizontal cylinder for introducing water vapor into the horizontal cylinder. The area near the feed end is defined as the pyrolysis zone, and the area near the discharge end is defined as the gasification activation zone. The air inlet pipe is located within the gasification activation zone. The downstream gas processing unit is connected to the exhaust port of the oxygen-enriched rotary unit and is used to convert crude coal gas into natural gas after conversion, purification and methanation. The downstream post-processing unit is connected to the discharge port of the oxygen-enriched rotary unit and is used to post-process the carbon material to obtain carbon material products.

[0008] According to one example, the preprocessing unit includes: Feeding device, used for storing raw coal; A crushing and screening device, which is connected to the feeding device, is used to crush and screen raw coal; A drying device, which is connected to the crushing and screening device, is used to dry raw coal to a predetermined moisture content.

[0009] According to one example, the gas processing unit includes: A medium-temperature conversion device, which is connected to the exhaust port of the oxygen-enriched rotary unit, is used to perform medium-temperature conversion on the crude gas to adjust the hydrogen-to-carbon ratio. An electrolysis water hydrogen production device, used to produce green hydrogen; A mixing device, which is connected to the intermediate temperature conversion device and the water electrolysis hydrogen production device respectively, is used to mix the gas after intermediate temperature conversion with green hydrogen. A deep purification device, connected to the mixing device, is used to remove tar, sulfur and carbon dioxide impurities from the mixed gas; A methanation reactor connected to the deep purification device is used to methanate the purified gas to produce natural gas. A natural gas separation unit, connected to the methanation reactor, is used to separate natural gas into synthetic natural gas and liquefied natural gas; A natural gas pipeline, connected to the natural gas production unit, is used to transport synthetic natural gas; A liquefied natural gas storage device, connected to the natural gas production unit, for storing liquefied natural gas.

[0010] According to one example, the reaction temperature of the intermediate temperature conversion device is 300-400°C, and it is internally equipped with an iron-chromium catalyst; The methanation reaction apparatus includes a main methanation section and a supplementary methanation section. The temperature of the main methanation section is 350-675℃, and the temperature of the supplementary methanation section is 250-350℃.

[0011] According to one example, the post-processing unit includes: A cooling device, which is connected to the outlet of the oxygen-enriched rotary unit, is used to cool carbon materials; A deep processing device, which is connected to the cooling device, is used to crush, screen, shape and activate and enhance the cooling carbon material. The discharge device, which is connected to the deep processing device, is used to discharge carbon material products.

[0012] According to one example, the oxygen-enriched rotary unit further includes: Base; Multiple rollers are disposed on the base and abut against the outer wall of the horizontal cylinder to support the horizontal cylinder and enable it to rotate; A first cover plate is disposed at the feed end of the horizontal cylinder and fixed on the base, and the feed port and the air inlet are formed on the first cover plate. The second cover plate is disposed at the discharge end of the horizontal cylinder and fixed on the base, and the exhaust port and the discharge port are formed on the second cover plate.

[0013] According to one example, the circumferential wall of the intake pipe is provided with a plurality of through holes spaced apart.

[0014] According to one example, the temperature of the pyrolysis zone is 600-800℃, the temperature of the gasification activation zone is 850-1000℃, the oxygen concentration is 35%-90%, and the steam consumption is 1.2-1.5 kg / kg of raw coal.

[0015] According to one example, a waste heat recovery unit is also included, the waste heat recovery unit comprising: A waste heat boiler is connected to the flue gas outlet of the oxygen-enriched rotary unit to recover the waste heat of the oxygen-enriched rotary unit and generate steam. A heat exchanger, which is connected to the methanation reactor, is used to recover the heat released by the methanation reaction and heat the feed gas entering the methanation reactor. The steam generated by the waste heat boiler is sent to the drying device of the pretreatment unit and / or the methanation reaction device of the gas treatment unit for preheating.

[0016] A method for producing carbon materials and co-producing natural gas using the above-mentioned oxygen-enriched rotary kiln pyrolysis gasification system includes the following steps: After being crushed, screened and dried, the raw coal is transported to the oxygen-enriched rotary unit. In the oxygen-enriched rotary unit, raw coal passes through the pyrolysis zone and the gasification activation zone in sequence, and undergoes synergistic treatment of pyrolysis, gasification and activation under an oxygen-enriched and water vapor atmosphere to generate crude coal gas and carbon materials. The generated crude coal gas is successively converted into natural gas through medium-temperature shift conversion, mixing and proportioning with green hydrogen, deep purification and methanation treatment; The generated carbon material is then post-processed to obtain carbon material products.

[0017] The present invention has the following advantages: This invention, through an integrated design of "one furnace, multiple stages, and dual production," achieves the synergistic transformation of coal pyrolysis, gasification, and activation within a single oxygen-enriched rotary unit. It simultaneously produces crude coal gas rich in H2 and CO, and high-porosity carbon material intermediates, which are subsequently processed into synthetic natural gas or liquefied natural gas, and high-quality carbon materials, respectively. Compared to existing coal fractionation technologies, this invention integrates processes that traditionally require multiple reactors into a single unit, offering significant advantages such as a compact process, low equipment investment, and continuous and stable operation.

[0018] In terms of energy utilization, this invention recovers waste heat from the flue gas of the oxygen-enriched rotary kiln using a waste heat boiler to generate steam for raw coal drying and preheating of the methanation reaction. Simultaneously, it recovers the exothermic heat from the methanation reaction through a heat exchanger to heat the feed gas entering the methanation reactor, achieving cascaded energy utilization and self-consistent balance within the system and significantly reducing external energy consumption. Furthermore, this invention introduces green hydrogen for precise proportioning of the crude coal gas, improving the conversion efficiency of the methanation reaction and the natural gas yield, while reducing carbon emissions, embodying a low-carbon design concept. Testing shows that the system's thermal efficiency can reach over 75%, carbon utilization rate reaches 86%, and pollutant emissions are reduced by 60%, demonstrating good economic and environmental benefits and providing an innovative technical solution for the clean and high-value utilization of coal resources. Attached Figure Description

[0019] Figure 1 This is a process system diagram of the oxygen-enriched rotary kiln pyrolysis gasification system for producing carbon materials and co-producing natural gas according to the present invention.

[0020] Among them, 1 is a feeding device, 2 is a crushing and screening device, 3 is a drying device, 4 is an oxygen-enriched rotary unit, 5 is a waste heat boiler, 6 is a medium-temperature conversion device, 7 is an electrolysis water hydrogen production device, 8 is a mixing device, 9 is a deep purification device, 10 is a methanation reaction device, 11 is a heat exchanger, 12 is a natural gas production device, 13 is a natural gas pipeline network, 14 is a liquefied natural gas storage device, 15 is a cooling device, 16 is a deep processing device, and 17 is a discharge device. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field. Test methods in the following embodiments that do not specify specific experimental conditions are generally performed under conventional experimental conditions. Unless otherwise specified, the reagents and raw materials used in the present invention are commercially available.

[0022] Reference Figure 1This invention illustrates a preferred embodiment of an oxygen-enriched rotary kiln pyrolysis and gasification system for producing carbon materials and co-producing natural gas. The system generally includes a pretreatment unit, an oxygen-enriched rotary kiln unit 4, a gas treatment unit, and a post-treatment unit. Raw coal, after being processed in the pretreatment unit, is fed into the oxygen-enriched rotary kiln unit 4. Within the oxygen-enriched rotary kiln unit 4, the pyrolysis, gasification, and activation processes of the coal are carried out synergistically. Volatile matter in the coal is converted into crude coal gas rich in H2 and CO, while solid residual carbon is activated into high-porosity carbon material intermediates. The crude coal gas is further converted into synthetic natural gas or liquefied natural gas by the gas treatment unit. The carbon material intermediates are then processed by the post-treatment unit to obtain high-quality carbon material products. This invention, through integrated design, achieves efficient and differentiated utilization of coal within a single system, offering advantages such as a compact process, high energy utilization, and high product added value.

[0023] Continue to refer to Figure 1 The pretreatment unit is located upstream of the system and is used to crush, screen, and dry the raw coal, and then transport the qualified material to the oxygen-enriched rotary unit 4. The pretreatment unit includes a feeding device 1, a crushing and screening device 2, and a drying device 3.

[0024] Feeding device 1 is used to store raw coal, and its outlet is connected to the inlet of crushing and screening device 2. Feeding device 1 includes a hopper and a frequency converter to achieve uniform and continuous conveying of raw coal. Crushing and screening device 2 is connected to feeding device 1 and is used to crush and screen the raw coal. Through crushing, the size of the raw coal is reduced to a suitable particle size range for subsequent pyrolysis and gasification reactions. Through screening, excessively large particles and impurities in the raw coal are removed to ensure the uniformity of particle size of the material entering the furnace. Drying device 3 is connected to crushing and screening device 2 and is used to dry the crushed and screened raw coal. In this embodiment, drying device 3 reduces the moisture content of the raw coal to below 12%. The reduction of raw coal moisture can significantly reduce the pyrolysis energy consumption in oxygen-enriched rotary unit 4, while avoiding severe pulverization or agglomeration of high-moisture materials at high temperatures.

[0025] In some embodiments, the drying device 3 adopts an indirect heating dryer, whose heat source comes from the steam generated by the waste heat boiler 5 at the back end of the system. The drying temperature is 120-150℃ and the drying time is 2-3 hours. The external moisture and some internal moisture in the raw coal are effectively removed, while the volatile matter and fixed carbon content of the raw coal are basically unaffected, thereby providing high-quality raw materials for subsequent pyrolysis, gasification and activation reactions.

[0026] Continue to refer to Figure 1 The oxygen-enriched rotary unit 4 is located downstream of the pretreatment unit and is used to synergistically process the pretreated raw coal through pyrolysis, gasification and activation to generate crude coal gas rich in CH4, H2 and CO, as well as carbon material intermediates with high porosity.

[0027] In some embodiments, the oxygen-enriched rotary unit 4 includes a rotatable horizontal cylinder, an inner cylinder coaxially disposed inside the horizontal cylinder, and a plurality of axially extending air inlet pipes. The oxygen-enriched rotary unit 4 also includes a base and a plurality of rollers. The rollers are disposed on the base and abut against the outer wall of the horizontal cylinder, supporting the horizontal cylinder and enabling it to rotate. The horizontal cylinder rotates continuously around its axis under the drive of a driving device, thereby causing the material inside the cylinder to continuously tumble and mix, achieving uniform heating and sufficient gas-solid contact, and improving heat and mass transfer efficiency.

[0028] The feed end of the horizontal cylinder is equipped with a first cover plate, which is fixed to the base and does not rotate with the cylinder. Both the feed inlet and the oxygen-enriched gas inlet are formed on the first cover plate. Raw coal enters the horizontal cylinder through the feed inlet, and oxygen-enriched gas is fed in from the feed end through the inlet. The discharge end of the horizontal cylinder is equipped with a second cover plate, which is fixed to the base and does not rotate with the cylinder. Both the crude coal gas exhaust port and the carbon material discharge port are formed on the second cover plate.

[0029] The inner cylinder is coaxially arranged inside the horizontal cylinder and runs through the horizontal cylinder axially. The inner cylinder is used for fuel combustion and the passage of high-temperature flue gas to indirectly heat the material inside the horizontal cylinder. The fuel burns inside the inner cylinder to generate high-temperature flue gas, and the heat is transferred to the coal material inside the horizontal cylinder through the inner cylinder wall. The combustion flue gas and the material are isolated by the inner cylinder wall and do not come into direct contact.

[0030] The horizontal cylinder is divided into two functional zones along the axial direction. The area near the feed end is defined as the pyrolysis zone, and the area near the discharge end is defined as the gasification activation zone. This division is mainly defined by the arrangement range of the air inlet pipe. The air inlet pipe is set in the gasification activation zone, and no air inlet pipe is set in the pyrolysis zone.

[0031] Multiple air inlet pipes are inserted from the discharge end of the horizontal cylinder and extend along the axial direction of the horizontal cylinder into the gasification and activation zone. The air inlet pipes are stationary relative to the horizontal cylinder and do not rotate with the horizontal cylinder. Multiple through holes are provided at intervals on their circumferential walls to distribute water vapor evenly into the material layer.

[0032] In the pyrolysis zone, only oxygen-enriched gas is introduced. The raw coal undergoes pyrolysis in this zone due to the combined effects of indirect heating from the inner cylinder and partial oxidation by the oxygen-enriched gas, releasing volatiles such as CH4, H2, and CO, while simultaneously forming the initial carbon skeleton. In the gasification activation zone, both oxygen-enriched gas and water vapor are introduced. The carbon from the pyrolysis zone reacts with CO2 and H2O in this zone to further generate crude coal gas. At the same time, the water vapor activates and pores the carbon skeleton, forming a well-developed porous structure for the subsequent preparation of high-quality carbon materials.

[0033] In this embodiment, the temperature of the pyrolysis zone is controlled at 600-800℃, the temperature of the gasification activation zone is controlled at 850-1000℃, the volume concentration of oxygen in the oxygen-enriched gas is 35%-90%, and the steam injection rate is 1.2-1.5 kg / kg of raw coal.

[0034] Raw coal passes through the pyrolysis zone and the gasification activation zone in the oxygen-enriched rotary unit 4 in sequence, realizing the synergistic transformation of pyrolysis, gasification and activation. The crude coal gas generated by the reaction is discharged from the exhaust port on the second cover plate and sent to the gas treatment unit for further processing. The fully activated carbon material intermediate is discharged from the discharge port on the second cover plate and sent to the post-processing unit. The high-temperature flue gas generated by combustion in the oxygen-enriched rotary unit 4 is sent to the waste heat boiler 5 for waste heat recovery.

[0035] Continue to refer to Figure 1 The gas processing unit is located downstream of the oxygen-enriched rotary unit 4 and connected to the exhaust port of the oxygen-enriched rotary unit 4. It is used to convert crude coal gas into natural gas through processes such as conversion, purification, and methanation. The gas processing unit includes a medium-temperature conversion unit 6, an electrolysis water hydrogen production unit 7, a mixing unit 8, a deep purification unit 9, a methanation reaction unit 10, a natural gas production unit 12, a natural gas pipeline, and a liquefied natural gas storage unit 14.

[0036] The intermediate-temperature shift converter 6 is connected to the exhaust port of the oxygen-enriched rotary unit 4 and is used to perform an intermediate-temperature shift reaction on the crude coal gas to adjust its hydrogen-to-carbon ratio. The crude coal gas mainly contains H2, CO, CH4, CO2, and small amounts of impurities. CO can be converted to H2 through a water-gas shift reaction, thereby increasing the H2 / CO ratio. In this embodiment, the reaction temperature of the intermediate-temperature shift converter 6 is controlled at 300-400℃, and it is internally equipped with an iron-chromium catalyst.

[0037] The water electrolysis hydrogen production unit 7 is used to produce green hydrogen. The mixing unit 8 is connected to both the intermediate-temperature shift converter 6 and the water electrolysis hydrogen production unit 7, and is used to fully mix the gas produced by the intermediate-temperature shift converter with the green hydrogen. By introducing the water electrolysis hydrogen production unit 7 to supplement the system with green hydrogen, and by mixing the intermediate-temperature shift gas with the green hydrogen through the mixing unit 8, the hydrogen-to-carbon ratio of the mixed gas is precisely adjusted to 3.0-3.5.

[0038] The deep purification device 9 is connected to the mixing device 8 and is used to remove impurities such as tar, sulfur and carbon dioxide from the mixed gas. The deep purification device 9 includes multi-stage purification equipment such as an electrostatic precipitator, a desulfurization tower and a decarbonization tower. Tar and sulfides can poison the methanation catalyst, and CO2 can dilute the reaction gas and affect the methanation reaction balance. After deep purification, the content of impurities in the gas is reduced to within the acceptable range for the methanation catalyst.

[0039] The methanation reactor 10 is connected to the deep purification unit 9 and is used to perform a methanation reaction on the purified gas to generate natural gas. The methanation reactor 10 is divided into two stages, including a main methanation stage and a supplementary methanation stage. The temperature of the main methanation stage is controlled at 350-675℃, and most of the CO and CO2 are converted into CH4. The reaction releases a large amount of heat. The temperature of the supplementary methanation stage is controlled at 250-350℃ and is used to further convert the remaining CO and CO2, ensuring that the CO+CO2 content in the outlet gas is ≤10ppm and the methane purity is ≥95%.

[0040] The natural gas production unit 12 is connected to the methanation reactor 10 and is used to separate the natural gas produced by the methanation reaction into synthetic natural gas and liquefied natural gas. The synthetic natural gas is sent to the natural gas pipeline network 13 through the natural gas pipeline for industrial and residential use, while the liquefied natural gas is sent to the liquefied natural gas storage unit 14 for storage, which facilitates transportation and peak-shaving.

[0041] Continue to refer to Figure 1 The post-processing unit is located downstream of the oxygen-enriched rotary unit 4 and is connected to the outlet of the oxygen-enriched rotary unit 4. It is used to post-process the carbon materials to finally obtain carbon material products.

[0042] The post-processing unit includes a cooling device 15, a deep processing device 16, and a discharge device 17. The cooling device 15 is connected to the discharge port of the oxygen-enriched rotary unit 4 and is used to receive the high-temperature carbon material intermediate discharged from the oxygen-enriched rotary unit 4 and rapidly cool it. In this embodiment, the cooling device 15 can be a rotary cooling drum, which can reduce the temperature of the carbon material to near room temperature through indirect water cooling or air cooling, while avoiding direct contact between the carbon material and the cooling medium to prevent the introduction of impurities.

[0043] The deep processing unit 16 is connected to the cooling unit 15 and is used to crush, screen, shape, and activate the cooled carbon material. The crushing process breaks large pieces of carbon material into suitable particle sizes; the screening process removes fine powder and non-standard particles to ensure uniform particle size; the shaping process can process the carbon material into specific shapes such as columnar or spherical shapes according to market demand; and the activation and enhancement process further regulates the pore structure of the carbon material through physical or chemical methods to improve its iodine value, specific surface area, and adsorption performance. After deep processing, the carbon material product can achieve an iodine value of over 950 mg / g, a strength ≥90%, and an ash content ≤10%.

[0044] The discharge device 17 is connected to the deep processing device 16 and is used to discharge the processed carbon material products and send them to the packaging process or finished product silo. The discharge device 17 can be a closed conveying equipment to avoid the escape of carbon material dust and meet the requirements of environmental protection production.

[0045] In some embodiments, the oxygen-enriched rotary kiln pyrolysis gasification system for producing carbon materials and co-producing natural gas also includes a waste heat recovery unit, which mainly includes a waste heat boiler 5 and a heat exchanger 11. The waste heat boiler 5 is connected to the flue gas outlet of the oxygen-enriched rotary kiln 4 and is used to recover the waste heat from the oxygen-enriched rotary kiln 4 and generate steam. The flue gas temperature discharged from the inner cylinder of the oxygen-enriched rotary kiln 4 is typically 800-1000℃, possessing a high calorific value. The waste heat boiler 5 utilizes this portion of the flue gas waste heat to heat water into saturated steam or superheated steam. The generated steam can be sent to the drying unit 3 of the pretreatment unit for raw coal drying, and / or to the methanation reaction unit 10 of the gas treatment unit for preheating.

[0046] The heat exchanger 11 is connected to the methanation reactor 10 and is used to recover the heat released by the methanation reaction and heat the feed gas entering the methanation reactor 10. By setting up the heat exchanger 11, the heat released by the methanation reaction is used to preheat the feed gas that is about to enter the methanation reactor 10, so that the feed gas reaches a suitable temperature before entering the reactor, reducing the external heating energy consumption, and at the same time alleviating the sudden temperature rise in the reactor, which helps to extend the catalyst life.

[0047] This application also provides a method for producing carbon materials and co-producing natural gas using the above-mentioned oxygen-enriched rotary kiln pyrolysis gasification system, comprising the following steps: (1) Raw material pretreatment After being crushed, screened, and dried, the raw coal is conveyed to the oxygen-enriched rotary unit 4. The raw coal is crushed to a suitable particle size by the crushing and screening device 2, and then dried to a moisture content of ≤12% by the drying device 3. The drying temperature is 120-150℃ and the drying time is 2-3 hours. The dried raw coal is then sent to the oxygen-enriched rotary unit 4.

[0048] (2) Synergistic transformation of pyrolysis, gasification and activation In the oxygen-enriched rotary unit 4, raw coal passes sequentially through the pyrolysis zone and the gasification activation zone, undergoing synergistic pyrolysis, gasification, and activation under an oxygen-enriched and steam atmosphere to generate crude coal gas and carbon material intermediates. The pyrolysis zone is only vented with oxygen-enriched gas, and the temperature is controlled at 600-800℃. The gasification activation zone is vented with both oxygen-enriched gas and steam, and the temperature is controlled at 850-1000℃. The oxygen concentration is controlled at 35%-90%, and the steam consumption is 1.2-1.5 kg / kg of raw coal. The waste heat generated by the oxygen-enriched rotary unit 4 is recovered through the waste heat boiler 5 to generate steam for raw coal drying and preheating of the methanation reaction.

[0049] (3) Crude gas conversion and waste heat recovery The generated crude coal gas is sequentially processed through a medium-temperature shift converter, mixed with green hydrogen for proportioning, deep purification, and methanation to convert it into natural gas. First, the crude coal gas enters the medium-temperature shift converter 6, where, under the action of an iron-chromium catalyst, the reaction temperature is controlled at 300-400℃ to perform a medium-temperature shift reaction to adjust the hydrogen-to-carbon ratio of the crude coal gas. The shifted gas is then sent to a mixing unit 8, while green hydrogen is prepared by an electrolytic water production unit 7 and fed into the mixing unit 8. The shifted gas and green hydrogen are mixed evenly in the mixing unit 8, precisely adjusting the hydrogen-to-carbon ratio to 3.0-3.5. The evenly mixed gas then enters the deep purification unit 9, where tar is removed by an electrostatic precipitator, sulfides are removed by a desulfurization tower, carbon dioxide is removed by a decarbonization tower, and dust and other impurities are removed by a pulse dust collector. After multiple purification processes, the gas is sent to the methanation reactor 10.

[0050] The methanation reaction unit 10 operates in two stages. The temperature of the main methanation stage is controlled at 350-675℃, and the temperature of the supplementary methanation stage is controlled at 250-350℃, ensuring that the CO+CO2 content in the outlet gas is ≤10ppm and the methane purity of the natural gas is ≥95%. The natural gas produced by the methanation reaction is sent to the natural gas production unit 12. At the same time, the waste heat released by the methanation reaction is recovered through heat exchanger 11 and used to heat the feed gas entering the methanation reaction unit 10.

[0051] (4) Natural gas production and carbon material post-processing The natural gas separation unit 12 separates natural gas into synthetic natural gas and liquefied natural gas. The synthetic natural gas conforms to the Class II gas standard of GB 17820-2018 and is sent to the natural gas pipeline network 13. The liquefied natural gas conforms to the conventional gas standard of GB / T 38753-2020 and is sent to the liquefied natural gas storage unit 14.

[0052] On the other hand, the carbon material intermediate discharged from the oxygen-enriched rotary unit 4 is cooled by the cooling device 15 and sent to the deep processing device 16 for crushing, screening, molding and activation enhancement treatment. Finally, the carbon material product is discharged through the discharge device 17. The carbon material product meets the requirement of iodine value of 950 mg / g or higher in the American Society for Testing and Materials (ASTM) D4607 standard.

[0053] Example 1

[0054] This embodiment uses, as follows: Figure 1The system shown is used for production. The raw coal has the following properties: moisture 16.5%, ash 6.9%, volatile matter 31.1%, and fixed carbon 45.5%. After crushing and screening, the raw coal is fed into drying unit 3 and dried at 120℃ for 2 hours to reduce the moisture content to below 12%. The dried raw coal is then continuously fed into oxygen-enriched rotary unit 4. The temperature of the pyrolysis zone in oxygen-enriched rotary unit 4 is controlled at 700℃, the temperature of the gasification activation zone is controlled at 850℃, the oxygen concentration is controlled at 40%, and the steam consumption is 1.3 kg / kg of raw coal. The reaction temperature of the intermediate temperature shift converter 6 is controlled at 300℃, using an iron-chromium catalyst. In the methanation reactor 10, the temperature of the main methanation section is controlled at 400℃, and the temperature of the supplementary methanation section is controlled at 300℃. After the above process, the product properties are shown in Table 1 below.

[0055] Table 1 shows the operating conditions and product properties of Example 1.

[0056]

[0057] The above-mentioned liquefied natural gas products meet the GB / T 38753-2020 standard for conventional liquefied natural gas (methane molar fraction 86.0~97.5%, higher volumetric calorific value 38.0~42.4 MJ / m³). 3 Synthetic natural gas products meet the Class II gas standard of GB 17820-2018 (high calorific value ≥ 31.4 MJ / m³). 3 Total sulfur ≤100 mg / m³ 3 Hydrogen sulfide ≤20 mg / m³ 3 The carbon materials produced meet the American Society for Testing and Materials (ASTM) iodine value 950 standard (iodine value ≥950 mg / g, hardness ≥90%, ash content ≤10%), with a carbon dioxide molar fraction ≤4%. Each ton of carbon materials consumes 1.3-1.5 tons of raw coal, achieving a crude coal gas conversion rate ≥95%, a carbon recovery rate ≥90% in the methanation stage, a system thermal efficiency ≥75%, a carbon utilization rate of 86%, and a 60% reduction in pollutant emissions. The power cost is approximately 120 million RMB / year. The market price of ASTM 950 iodine value carbon materials is 7000 RMB / ton, generating annual sales revenue of approximately 560 million RMB. The comprehensive selling price of natural gas is 3 RMB / cubic meter, generating annual sales revenue of approximately 300 million RMB. The static investment payback period is approximately 2.8-3.2 years.

[0058] Example 2

[0059] This embodiment is basically the same as that of embodiment 1, except that the activation zone temperature is 900 ℃. The other operating conditions are the same as those of embodiment 1. The specific operating conditions and product properties are shown in Table 2 below.

[0060] Table 2 shows the operating conditions and product properties of Example 2.

[0061]

[0062] The above-mentioned liquefied natural gas products meet the GB / T 38753-2020 standard for conventional liquefied natural gas (methane molar fraction 86.0~97.5%, higher volumetric calorific value 38.0~42.4 MJ / m³). 3 Synthetic natural gas products meet the Class II gas standard of GB 17820-2018 (high calorific value ≥ 31.4 MJ / m³). 3 Total sulfur ≤100 mg / m³ 3 Hydrogen sulfide ≤20 mg / m³ 3 The carbon materials produced meet the American Society for Testing and Materials (ASTM) iodine value 950 standard (iodine value ≥950 mg / g, hardness ≥90%, ash content ≤10%), with a carbon dioxide molar fraction ≤4%. Each ton of carbon materials consumes 1.3-1.5 tons of raw coal, achieving a crude coal gas conversion rate ≥95%, a carbon recovery rate ≥90% in the methanation stage, a system thermal efficiency ≥75%, a carbon utilization rate of 86%, and a 60% reduction in pollutant emissions. The power cost is approximately 120 million RMB / year. The market price of ASTM 950 iodine value carbon materials is 7000 RMB / ton, generating annual sales revenue of approximately 560 million RMB. The comprehensive selling price of natural gas is 3 RMB / cubic meter, generating annual sales revenue of approximately 300 million RMB. The static investment payback period is approximately 2.8-3.2 years.

[0063] Example 3

[0064] This embodiment is basically the same as Embodiment 1, except that the steam consumption is 1.5 kg / kg of raw coal. The other operating conditions are the same as in Embodiment 1. The specific operating conditions and product properties are shown in Table 3 below.

[0065] Table 3 shows the operating conditions and product properties of Example 3.

[0066]

[0067] The above-mentioned liquefied natural gas products meet the GB / T 38753-2020 standard for conventional liquefied natural gas (methane molar fraction 86.0~97.5%, higher volumetric calorific value 38.0~42.4 MJ / m³). 3 Synthetic natural gas products meet the Class II gas standard of GB 17820-2018 (high calorific value ≥ 31.4 MJ / m³). 3 Total sulfur ≤100 mg / m³ 3 Hydrogen sulfide ≤20 mg / m³ 3The carbon materials produced meet the American Society for Testing and Materials (ASTM) iodine value 950 standard (iodine value ≥950 mg / g, hardness ≥90%, ash content ≤10%), with a carbon dioxide molar fraction ≤4%. Each ton of carbon materials consumes 1.3-1.5 tons of raw coal, with a crude gas conversion rate ≥95%, a carbon recovery rate ≥90% in the methanation stage, a system thermal efficiency ≥75%, a carbon utilization rate of 86%, and a 60% reduction in pollutant emissions. The power cost is approximately 120 million RMB / year. The market price of ASTM 950 iodine value carbon materials is 7000 RMB / ton, generating annual sales revenue of approximately 560 million RMB. The comprehensive selling price of natural gas is 3 RMB / cubic meter, generating annual sales revenue of approximately 300 million RMB. The static investment payback period is approximately 2.8-3.2 years.

[0068] Comparative Example 1 This comparative example is basically the same as Example 1, except that the oxygen-enriched gas is replaced with air. The other operating conditions are the same as those in Example 1. The specific operating conditions and product properties are shown in Table 4 below.

[0069] Table 4 shows the operating conditions and product properties for Comparative Example 1.

[0070]

[0071] The above-mentioned liquefied natural gas products meet the GB / T 38753-2020 standard for conventional liquefied natural gas (methane molar fraction 86.0~97.5%, higher volumetric calorific value 38.0~42.4 MJ / m³). 3 Synthetic natural gas products meet the Class II gas standard of GB 17820-2018 (high calorific value ≥ 31.4 MJ / m³). 3 Total sulfur ≤100 mg / m³ 3 Hydrogen sulfide ≤20 mg / m³ 3 The carbon materials produced meet the American Society for Testing and Materials (ASTM) iodine value 950 standard (iodine value ≥950 mg / g, hardness ≥90%, ash content ≤10%), with a carbon dioxide molar fraction ≤4%. In general, due to the regulation effect of the rotary kiln's downstream intermediate-temperature conversion system and green hydrogen replenishment, the indicators of the proportional liquefied natural gas and synthetic natural gas products still meet the corresponding standards, but the indicators of the carbon materials do not. System thermal efficiency and carbon utilization decrease by approximately 5%, pollutant emissions increase, and power costs nearly double.

[0072] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. The embodiments described in this disclosure are intended as non-limiting examples, and other embodiments may take various and alternative forms. Furthermore, the drawings are not necessarily to scale and may present simplified expressions of various features of the present disclosure, including, for example, specific dimensions, orientations, positions, and shapes. Details associated with such features will be determined in part by the intended application and usage environment of the described embodiments.

[0073] The detailed description and accompanying drawings are supporting and descriptive of this teaching, but the scope of this teaching is defined only by the claims. While the best mode and some other embodiments for carrying out this teaching have been described in detail, various alternative designs and embodiments exist for practicing the teaching as defined in the appended claims. Furthermore, this disclosure expressly includes combinations and sub-combinations of the elements and features set forth above and below.

Claims

1. A system for producing carbon materials and co-producing natural gas through oxygen-enriched rotary kiln pyrolysis and gasification, characterized in that, include: The upstream pretreatment unit is used to crush, screen and dry the raw coal, and then transport the processed raw coal to the oxygen-enriched rotary unit. An oxygen-enriched rotary unit is used to pyrolyze, gasify, and activate raw coal to generate crude coal gas and carbon materials. The oxygen-enriched rotary unit includes: A rotatable horizontal cylinder has a feed inlet for receiving raw coal and an air inlet for receiving oxygen-enriched gas at its feed end, and an exhaust outlet for discharging crude coal gas and an exhaust outlet for discharging carbon materials at its discharge end. The inner cylinder is coaxially disposed inside the horizontal cylinder and is used for fuel combustion and high-temperature flue gas passage to indirectly heat the material inside the horizontal cylinder. Multiple air inlet pipes are provided at the discharge end of the horizontal cylinder and extend axially into the interior of the horizontal cylinder for introducing water vapor into the horizontal cylinder. The area near the feed end is defined as the pyrolysis zone, and the area near the discharge end is defined as the gasification activation zone. The air inlet pipe is located within the gasification activation zone. The downstream gas processing unit is connected to the exhaust port of the oxygen-enriched rotary unit and is used to convert crude coal gas into natural gas after conversion, purification and methanation. The downstream post-processing unit is connected to the discharge port of the oxygen-enriched rotary unit and is used to post-process the carbon material to obtain carbon material products.

2. The system according to claim 1, characterized in that, The preprocessing unit includes: Feeding device, used for storing raw coal; A crushing and screening device, which is connected to the feeding device, is used to crush and screen raw coal; A drying device, which is connected to the crushing and screening device, is used to dry raw coal to a predetermined moisture content.

3. The system according to claim 1, characterized in that, The gas processing unit includes: A medium-temperature conversion device, which is connected to the exhaust port of the oxygen-enriched rotary unit, is used to perform medium-temperature conversion on the crude gas to adjust the hydrogen-to-carbon ratio. An electrolysis water hydrogen production device, used to produce green hydrogen; A mixing device, which is connected to the intermediate temperature conversion device and the water electrolysis hydrogen production device respectively, is used to mix the gas after intermediate temperature conversion with green hydrogen. A deep purification device, connected to the mixing device, is used to remove tar, sulfur and carbon dioxide impurities from the mixed gas; A methanation reactor connected to the deep purification device is used to methanate the purified gas to produce natural gas. A natural gas separation unit, connected to the methanation reactor, is used to separate natural gas into synthetic natural gas and liquefied natural gas; A natural gas pipeline, connected to the natural gas production unit, is used to transport synthetic natural gas; A liquefied natural gas storage device, connected to the natural gas production unit, for storing liquefied natural gas.

4. The system according to claim 3, characterized in that, The reaction temperature of the medium-temperature conversion device is 300-400℃, and it is equipped with an iron-chromium catalyst. The methanation reaction apparatus includes a main methanation section and a supplementary methanation section. The temperature of the main methanation section is 350-675℃, and the temperature of the supplementary methanation section is 250-350℃.

5. The system according to claim 1, characterized in that, The post-processing unit includes: A cooling device, which is connected to the outlet of the oxygen-enriched rotary unit, is used to cool carbon materials; A deep processing device, which is connected to the cooling device, is used to crush, screen, shape and activate and enhance the cooling carbon material. The discharge device, which is connected to the deep processing device, is used to discharge carbon material products.

6. The system according to claim 1, characterized in that, The oxygen-enriched rotary unit also includes: Base; Multiple rollers are disposed on the base and abut against the outer wall of the horizontal cylinder to support the horizontal cylinder and enable it to rotate; A first cover plate is disposed at the feed end of the horizontal cylinder and fixed on the base, and the feed port and the air inlet are formed on the first cover plate. The second cover plate is disposed at the discharge end of the horizontal cylinder and fixed on the base, and the exhaust port and the discharge port are formed on the second cover plate.

7. The system according to claim 1, characterized in that, The circumferential wall of the air intake pipe is provided with multiple through holes at intervals.

8. The system according to claim 1, characterized in that, The temperature of the pyrolysis zone is 600-800℃, the temperature of the gasification activation zone is 850-1000℃, the oxygen concentration is 35%-90%, and the steam consumption is 1.2-1.5 kg / kg of raw coal.

9. The system according to claim 1, characterized in that, It also includes a waste heat recovery unit, which comprises: A waste heat boiler is connected to the flue gas outlet of the oxygen-enriched rotary unit to recover the waste heat of the oxygen-enriched rotary unit and generate steam. A heat exchanger, which is connected to the methanation reactor, is used to recover the heat released by the methanation reaction and heat the feed gas entering the methanation reactor. The steam generated by the waste heat boiler is sent to the drying device of the pretreatment unit and / or the methanation reaction device of the gas treatment unit for preheating.

10. A method for producing carbon materials and co-producing natural gas using an oxygen-enriched rotary kiln pyrolysis gasification system as described in any one of claims 1-9, characterized in that, Includes the following steps: After being crushed, screened and dried, the raw coal is transported to the oxygen-enriched rotary unit. In the oxygen-enriched rotary unit, raw coal passes through the pyrolysis zone and the gasification activation zone in sequence, and undergoes synergistic treatment of pyrolysis, gasification and activation under an oxygen-enriched and water vapor atmosphere to generate crude coal gas and carbon materials. The generated crude coal gas is successively converted into natural gas through medium-temperature shift conversion, mixing and proportioning with green hydrogen, deep purification and methanation treatment; The generated carbon material is then post-processed to obtain carbon material products.

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