System and process for resource utilization of coal gasification slag

Abstract

This invention relates to the field of comprehensive utilization technology of coal gasification slag, and particularly to a system and process for the resource utilization of coal gasification slag. The system of this invention includes a microwave gasifier, a spray tower, a heat exchanger, a carbon dioxide storage tank, a water separator, and a separation membrane device. The microwave gasifier is used for the carbon conversion reaction between the coal gasification slag and carbon dioxide; the spray tower is connected to the microwave gasifier; the heat exchanger is connected to both the microwave gasifier and the spray tower; the carbon dioxide storage tank is connected to the heat exchanger; the water separator is connected to both the spray tower and the heat exchanger; and the separation membrane device is connected to both the water separator and the carbon dioxide storage tank. The system of this invention has a compact design, and all components work collaboratively, enabling automated and efficient coal gasification slag treatment. The process for resource utilization of coal gasification slag of this invention converts the carbon components in the coal gasification slag into carbon monoxide, converts the inorganic components into fly ash, and recovers heavy metals from the gasification slag, achieving both volume reduction and resource utilization of the coal gasification slag.

Description

Technical Field

[0001] This invention relates to the field of comprehensive utilization technology of coal gasification slag, and in particular to a system and process for the resource utilization of coal gasification slag. Background Technology

[0002] Coal gasification technology, as the mainstream process for producing syngas, is a key technology in the modern coal chemical industry. However, the coal gasification process generates a large amount of gasification slag, of which 40%-60% is coarse slag from the slag discharge port and 20%-40% is fine slag from the syngas dust removal unit. Both coarse and fine slag are discharged wet, and the water content of the gasification slag retrieved from the slag pool is between 40% and 60%. The difficulty in drying this slag is one of the factors restricting its resource utilization. In addition, the residual carbon in the gasification slag is covered by the molten slag shell and cannot be directly burned, limiting its direct co-firing and reuse.

[0003] In 2023, my country's annual gasification slag production exceeded 70 million tons, with coarse slag accounting for 70% and fine slag for 30%. Currently, landfilling remains the main method of treating gasification slag, and there is still no effective way to achieve resource utilization or large-scale disposal of gasification slag. Landfilling not only causes environmental problems such as land occupation, dust pollution, and water and soil pollution, but also incurs high treatment costs. Therefore, researching lightweight, resource-based, and harmless treatment methods for coal gasification slag is key to achieving a balance between environmental and economic benefits. Summary of the Invention

[0004] This invention provides a system and process for the resource utilization of coal gasification slag, which solves the problems of land occupation, dust pollution, water and soil pollution, and high cost associated with existing landfill treatment of coal gasification slag.

[0005] According to a first aspect of the present invention, the present invention provides a system for the resource utilization of coal gasification slag, the system comprising: Microwave gasifier, used for the carbon conversion reaction of coal gasification slag and carbon dioxide; The spray tower is connected to the top of the microwave gasifier; The heat exchangers are connected to the top of the microwave gasifier and the top of the spray tower, respectively. A carbon dioxide storage tank is connected to the heat exchanger; The water distributor is connected to the spray tower and the heat exchanger respectively; The separation membrane device is connected to the water separator and the carbon dioxide storage tank respectively; the separation membrane device is equipped with a separation membrane assembly.

[0006] The system of this invention includes a microwave gasifier, a spray tower, a heat exchanger, a carbon dioxide storage tank, a water separator, and a separation membrane device. The microwave heating technology of the microwave gasifier can rapidly increase the reaction temperature, shorten the reaction time, and improve production efficiency. The design of the spray tower and water separator reduces pollutant emissions. The separated carbon dioxide can be returned to the system to continue participating in the reaction, reducing the need for external carbon dioxide replenishment. Heat recovery through the heat exchanger improves the system's energy utilization efficiency. The separation membrane device effectively separates CO and CO2 gases. The entire system has a compact design, with all components working collaboratively to achieve automated and efficient coal gasification slag treatment. It can convert inactive carbon components in the coal gasification slag into high-value-added carbon monoxide, convert inorganic components into fly ash, and recover heavy metals from the gasification slag, achieving reduction and resource utilization of coal gasification slag, resulting in significant economic and environmental benefits.

[0007] Furthermore, multiple sets of magnetrons are symmetrically arranged on the top and side walls of the microwave gasifier, and the magnetrons are connected to each other via a ring waveguide and a coaxial converter to form incoherent power combining. Each set of magnetrons is connected to a waveguide slot antenna, and equally spaced rectangular slots are opened on the surface of the antenna to achieve uniform radiation of microwave energy to the reaction cavity of the microwave gasifier. It should be noted that incoherent power combining is a technique that combines multiple independent beams or energy sources together to increase the total power, which can improve the utilization rate of microwave energy.

[0008] The inner wall of the reaction chamber of the microwave gasifier is lined with a stepped Al2O3 ceramic liner and coated with a silver-based reflective coating to reduce energy loss.

[0009] The microwave gasifier's reaction chamber is divided into a preheating zone at the top, a main reaction zone in the middle, and a cooling zone at the bottom by horizontal metal partitions arranged axially. Each metal partition has a central channel for material to fall. The main reaction zone contains vertically arranged hexagonal honeycomb-shaped quartz reaction tubes. Microwave shields are inserted between the quartz reaction tubes to suppress edge field interference. A double-layer sieve plate is installed inside each quartz reaction tube. The lower sieve plate supports the material, while the upper sieve plate vibrates vertically via an eccentric wheel mechanism to prevent material accumulation and promote uniform contact between the material and microwaves. Simultaneously, the entire quartz reaction tube rotates around its axis to prevent material agglomeration. An ultrasonic transducer is placed between the upper and lower sieve plates to assist in particle breakage induced by microwave heating through cavitation. The bottom of the quartz reaction tube is equipped with an annular multi-hole injector, which is arranged in multiple layers. Each layer independently controls the CO2 flow rate to achieve an axial concentration gradient distribution. The top of each quartz reaction tube is equipped with a rupture disc to prevent excessive pressure during the reaction. At the same time, each quartz reaction tube is connected to a gas collecting pipe through an independent pipe to collect the reaction products.

[0010] To rapidly increase reaction temperature, shorten reaction time, and improve production efficiency, this invention employs a microwave gasifier with a specific structural design. The microwave gasifier uses multiple magnetrons to enhance microwave power through incoherent power combining, enabling applications requiring high power output. The microwave gasifier of this invention divides the reaction chamber into a preheating zone, a main reaction zone, and a cooling zone through multi-layered metal partitions and a zoned design. Channels are provided in the metal partitions for material to fall, and this zoned design facilitates precise control of the reaction process. The microwave gasifier of this invention designs the quartz reaction tubes in the main reaction zone with a hexagonal honeycomb distribution and equips them with a vibrating screen, ultrasonic transducer, and rotating mechanism, effectively improving reaction efficiency and preventing material agglomeration. The microwave gasifier of this invention incorporates an annular multi-hole injector at the bottom of the quartz reaction tubes to achieve an axial concentration gradient distribution, which is more conducive to the chemical reaction.

[0011] Preferably, the plurality of magnetrons consists of 3 to 6 magnetrons.

[0012] Preferably, the thickness of the stepped Al2O3 ceramic liner is 5-15 mm.

[0013] Preferably, the microwave reflectivity of the silver-based reflective coating is >95%.

[0014] Preferably, the metal partition is made of 316L stainless steel.

[0015] Preferably, the microwave shield can be made of Inconel 600 metal tubing.

[0016] Preferably, the quartz reaction tube rotates around its axis at 5-15 rpm.

[0017] Preferably, the frequency of the vertical vibration is 5-10Hz and the amplitude is 2-5mm.

[0018] Preferably, the frequency of the ultrasonic transducer is 10-30 kHz, and the power density is 40-60 W / cm². 2 .

[0019] Furthermore, considering that CO synthesis is a gas-solid reaction, there is a risk of pipeline blockage. Therefore, two or more microwave gasifiers are designed in parallel to ensure continuous and stable operation of the process. When the coal gasification slag production is large, two reactors can be started simultaneously to increase the throughput and ensure stable operation of the process under high load.

[0020] Furthermore, the separation membrane module is an inorganic membrane module, preferably a ZIF-8 molecular sieve separation membrane. ZIF-8 molecular sieves possess a regular pore structure and good chemical stability, enabling selective adsorption of CO and CO2. Its pore size and chemical environment give it a higher affinity for CO2, thus achieving efficient CO / CO2 separation. ZIF-8 molecular sieves remain stable over a wide temperature range, capable of withstanding high temperatures and pressures during industrial gas separation while maintaining good separation performance. ZIF-8 molecular sieve membranes exhibit good reusability, maintaining high separation performance even after multiple cycles. This not only reduces separation costs but also improves the economics of industrial applications. The use of ZIF-8 molecular sieve membranes reduces reliance on traditional chemical absorbents, avoiding secondary pollution problems caused by the volatilization of chemical absorbents, and meeting environmental protection requirements.

[0021] Furthermore, the spray tower is filled with metal or ceramic packing material. Filling the spray tower with metal or ceramic packing material can significantly improve gas-liquid mass transfer efficiency, enhance the purification effect, and ensure stable system operation. Specifically, the metal or ceramic packing material can include Pall rings, stepped rings, ceramic honeycomb packing material, etc.

[0022] Furthermore, the system also includes a stirrer connected to the microwave gasifier. The stirrer ensures thorough mixing of the materials, thereby improving the efficiency of subsequent reactions.

[0023] Furthermore, the system also includes a fly ash storage tank, which is connected to the bottom of the microwave gasifier. The fly ash storage tank is used to collect the fly ash recovered by the system for reuse.

[0024] Furthermore, the system also includes a carbon monoxide storage tank, which is connected to the separation membrane device. The carbon monoxide storage tank is used to collect the carbon monoxide generated by the system for reuse.

[0025] Furthermore, the system also includes a metal recovery storage tank, which is connected to the bottom of the spray tower. The metal recovery storage tank is used to collect metals recovered by the system, such as zinc, chromium, nickel, copper, cadmium, and lead.

[0026] According to a second aspect of the present invention, the present invention also provides a process for the resource utilization of coal gasification slag, which is implemented using the above-described system; the process includes the following steps: Coal gasification slag at a temperature of 350-450℃ and CO2 gas at a temperature of 350-450℃ are introduced into a microwave gasifier to carry out a carbon conversion reaction. The gaseous components produced by the carbon conversion reaction are passed into a spray tower for cooling; the solid components obtained after cooling are recovered. The gaseous components obtained after cooling in the spray tower are passed into a heat exchanger to exchange heat with CO2 gas from the carbon dioxide storage tank; the CO2 gas after heat exchange is then passed into the microwave gasifier. The gaseous components from the spray tower after heat exchange are fed into a water separator for water removal and separation; the water obtained from water removal and separation is fed back into the spray tower. The gas phase components obtained after water separation by the water separator are fed into the separation membrane device for CO and CO2 separation; the separated CO2 gas is fed into the carbon dioxide storage tank.

[0027] This invention reduces the volume of coal gasification slag at its source. Unlike previous methods that treated cooled gasification slag, this process treats the high-temperature slag after it exits the furnace, fully utilizing its latent heat to decarbonize it and simultaneously generate high-value carbon monoxide. This process can co-process co-process co-processing of coarse and fine slag, achieving a 10%-50% reduction in emissions, depending on the type of gasifier, the properties of the fuel coal, and the residence time within the furnace. This invention also enables the resource-based and high-value utilization of coal gasification slag. Microwave heating replaces traditional mechanical crushing to activate carbon components, allowing activation and reaction to occur within the same reactor. This saves investment costs, reduces operational complexity, and minimizes potential dust problems. The residual carbon components are converted into CO, and the economic benefits of CO production from coal gasification slag far outweigh the fuel cost reduction from co-combustion. Furthermore, while achieving high-value decarbonization, the generated tailings meet the national Class I fly ash requirements. The collected fly ash can be sold directly as a product or used to prepare other building materials. The overall process of this invention is simple, solving the problem of high moisture content and difficulty in processing coal gasification slag in traditional processes, shortening the coal gasification slag treatment process, and providing a solution to the problem of heavy metal contamination during coal gasification slag landfill, while also realizing metal recovery. It is easy to scale up production and has dual strategic significance for energy and environmental protection.

[0028] Furthermore, the carbon conversion reaction is carried out at a temperature of 1000℃-1300℃ and a space velocity of 200 h⁻¹. -1 -400h -1 The microwave power density is 1×10 5 -10×10 5 W / m 3 The reactor pressure is 0.2-0.3 MPa. Speculating the conditions for the carbon conversion reaction can significantly improve reaction efficiency, optimize energy utilization, reduce catalyst deactivation, lower environmental risks, and bring significant economic benefits.

[0029] Furthermore, before reacting the coal gasification slag at 350-450℃ with CO2 gas at 350-450℃ for carbon conversion, the coal gasification slag is expanded under microwave irradiation for 3-10 minutes. Microwave pretreatment of coal gasification slag can significantly improve its pore structure and reaction performance, increase reaction efficiency and product quality, while reducing energy consumption and environmental risks. It is an efficient and environmentally friendly pretreatment method.

[0030] Furthermore, the coal gasification slag includes fine coal gasification slag with a particle size of <1mm and coarse coal gasification slag with a particle size of 1mm-4mm; preferably, the fine coal gasification slag accounts for 60-80% of the total mass of the coal gasification slag.

[0031] Furthermore, the temperature of the CO2 gas from the carbon dioxide storage tank is 60-110°C.

[0032] Furthermore, the CO product obtained by separating CO and CO2 has a purity greater than 85%.

[0033] The present invention provides a compact system design for the resource utilization of coal gasification slag, with each component working in concert to achieve automated and efficient coal gasification slag treatment.

[0034] The present invention provides a process for the resource utilization of coal gasification slag, which converts the carbon components in the coal gasification slag that have lost their reactivity into carbon monoxide with high added value, converts the inorganic components into fly ash, and recovers heavy metals in the gasification slag, thereby realizing the reduction and resource utilization of coal gasification slag. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of a system for the resource utilization of coal gasification slag provided in Embodiment 1 of the present invention.

[0037] Figure reference numerals: 1: Agitator; 2: Microwave gasifier; 3: Spray tower; 4: Water distributor; 5: Separation membrane device; 6: Heat exchanger; 7: Carbon monoxide storage tank; 8: Carbon dioxide storage tank; 9: Fly ash storage tank; 10: Metal recovery storage tank. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0039] Example 1 This embodiment describes a system for the resource utilization of coal gasification slag, such as... Figure 1 As shown, the system includes a stirrer 1, a microwave gasifier 2, a spray tower 3, a water separator 4, a separation membrane device 5, a heat exchanger 6, a carbon monoxide storage tank 7, a carbon dioxide storage tank 8, a fly ash storage tank 9, and a metal recovery storage tank 10.

[0040] The stirrer 1 is used to mix the fine and coarse coal gasification slag. Stirrer 1 is connected to the microwave gasifier 2. The coal gasification slag mixed by stirrer 1 enters the microwave gasifier 2, which is used for activating the coal gasification slag and for the carbon conversion reaction between the slag and carbon dioxide. Six sets of magnetrons are symmetrically arranged on the top and side walls of the microwave gasifier (the specific number can be flexibly adjusted according to the reactor size and power requirements). The magnetrons are connected to a coaxial converter via a ring waveguide to form incoherent power combining. Each set of magnetrons is connected to a waveguide slot antenna with equally spaced rectangular slots on the antenna surface (slot width is typically 1.5 mm, and spacing is typically 35 ± 0.5 mm), ensuring uniform microwave energy radiation to the reaction chamber of the microwave gasifier. The inner wall of the reaction chamber of the microwave gasifier uses a stepped Al2O3 ceramic liner (10 mm thick) with a silver-based reflective coating, achieving a microwave reflectivity >95% and reducing energy loss. The microwave gasifier's reaction chamber is divided into three horizontal metal partitions (made of 316L stainless steel) arranged axially, forming a preheating zone at the top, a main reaction zone in the middle, and a cooling zone at the bottom. Each partition has a central channel for material to fall. The main reaction zone contains vertically arranged hexagonal honeycomb-shaped quartz reaction tubes. Metal tubes (made of Inconel 600) are inserted between the quartz reaction tubes as microwave shields to suppress edge field interference. A double-layer sieve is installed inside each quartz reaction tube. The lower sieve supports the material, while the upper sieve vibrates vertically at 20Hz with an amplitude of 4mm via an eccentric wheel mechanism. Simultaneously, the entire quartz reaction tube rotates around its axis at 10rpm to prevent material agglomeration. An ultrasonic transducer (20kHz, power density 50W / cm²) is installed between the sieves to assist in particle breakage induced by microwave heating through cavitation. A ring-shaped multi-hole injector, arranged in three layers, is installed at the bottom of the quartz reaction tube. Each layer independently controls the CO2 flow rate, achieving an axial concentration gradient distribution. Each quartz reaction tube is equipped with a rupture disc at the top and is connected to a gas collection pipe.

[0041] The solid phase component obtained from the carbon conversion reaction is decarbonized fly ash, which enters fly ash storage tank 9 for enrichment.

[0042] The spray tower 3 is connected to the top of the microwave gasifier 2 and is used for cooling and separating the gaseous components obtained from the carbon conversion reaction. The spray tower 3 is filled with metal or ceramic packing to assist in gas-solid separation. The temperature of the gaseous components is adjusted by controlling the spray water volume to lower the temperature below the metal boiling point (400-500℃). The spray water volume is controlled by temperature regulation. Temperature detection instruments are installed in the upper, middle, and lower sections of the spray tower 3. When the temperature is below 450℃, the spraying of condensate water is stopped. The bottom of the spray tower 3 is connected to the metal recovery storage tank 10. The metal-rich components collected at the bottom of the tower are sent to the metal recovery tank 10 for further separation.

[0043] The heat exchanger 6 is connected to the top of the microwave gasifier 2 and the top of the spray tower 3. The carbon dioxide storage tank 8 is connected to the heat exchanger 6. The gas phase components separated by the spray tower 3 enter the heat exchanger 6 to exchange heat with the low temperature CO2 (60℃-110℃) from the carbon dioxide storage tank 8. The CO2 after heat exchange enters the microwave gasifier 2 to carry out the CO preparation reaction.

[0044] Water separator 4 is connected to spray tower 3 and heat exchanger 6. The gas phase components separated by spray tower 3 enter water separator 4 after heat exchange in heat exchanger 6 for water removal and separation. The water obtained from water removal and separation is used in spray tower 3. Water separator 4 is also connected to water supply device for water storage and supply to spray tower 3.

[0045] The separation membrane device 5 is connected to the water separator 4 and the carbon dioxide storage tank 8. The gas phase components after water separation by the water separator 4 enter the separation membrane device 5. The separation membrane device 5 is equipped with a separation membrane assembly, which is a ZIF-8 molecular sieve separation membrane, used to separate CO and CO2. The carbon monoxide storage tank 7 is connected to the separation membrane device 5 and is used to store the CO gas obtained after separation. The CO2 gas obtained after separation enters the carbon dioxide storage tank 8 for circulation.

[0046] The system also includes gas conveying equipment, solid conveying equipment, and other sealing materials for conveying gases and solids and sealing the devices.

[0047] Example 2 This embodiment provides a process for the resource utilization of coal gasification slag, implemented using the system of Embodiment 1; the process includes the following steps: Includes the following steps: (1) After the raw coal is pretreated and crushed by a coal mill, it enters the coal gasifier to undergo coal gasification reaction. After the reaction is completed, coarse coal gasification slag with a particle size range of 1mm-4mm is collected at the bottom of the gasifier. The synthesis gas collected from the top of the gasifier is separated into gas and solid phases by a cyclone separator. Fine coal gasification slag with a particle size of <1mm can be collected in the solid phase.

[0048] (2) 7 kg of fine coal gasification slag and 3 kg of coarse coal gasification slag are fed into a mixer 1 and mixed thoroughly. The mixer 1 is heat-treated to maintain the temperature at 400℃. After mixing, the coal gasification slag raw material is fed into a microwave gasifier 2. CO2 gas at 400℃ is also fed into the microwave gasifier 2. The coal gasification slag expands under microwave action for 5 minutes, which activates the encapsulated carbon components. The reactor temperature is controlled within the range of 1200±50℃ and the space velocity is controlled within the range of 300±10h. -1 Within the range, the microwave power density is 3×10 5 W / m 3 Within the range, the reactor pressure is within the range of 0.2 MPa (G). At this time, the reaction C + CO2 → 2CO occurs in the reactor for 5 minutes, converting the carbon components in the coal gasification slag into CO. After the reaction, the solid components are decarbonized and the fly ash enters the fly ash storage tank 9 for enrichment. The amount of fly ash that can be collected is 6.5 kg.

[0049] (3) The gaseous components enter the spray tower 3 for cooling and metal recovery, with a residence time of approximately 1 minute. The temperature of the gaseous components is adjusted by controlling the spray water volume to lower the temperature below the metal boiling point (400-500℃). The spray water volume is controlled by temperature regulation. Temperature detection instruments are installed in the upper, middle, and lower sections of the spray tower 3. When the temperature is below 450℃, the spraying of condensate water is stopped. The metal-rich components collected at the bottom of the spray tower 3 are sent to the metal recovery storage tank 10 for further separation. The metal-rich components mainly include aluminum oxides and iron oxides.

[0050] (4) The gaseous components at the top of spray tower 3 are separated into water by a water separator 4 after waste heat recovery. Silica gel is used as the dehydrating agent in the water separator 4. The dehydrated water is then fed into spray tower 3, and the dehydrated gaseous components are separated into the inorganic molecular sieve membrane of the separation membrane device 5. The separated CO enters the carbon monoxide storage tank 7, and the CO product purity is 86%. CO2, along with the supplemented CO2 feedstock, is exchanged in heat exchanger 6 and then enters the microwave gasifier 2 for syngas preparation. The gasification slag carbon conversion rate is ≥85%.

[0051] Example 3 This embodiment provides a process for the resource utilization of coal gasification slag, as detailed below: Includes the following steps: (1) After the raw coal is pretreated and crushed by a coal mill, it enters the coal gasifier to undergo coal gasification reaction. After the reaction is completed, coarse coal gasification slag with a particle size range of 1mm-4mm is collected at the bottom of the gasifier. The synthesis gas collected from the top of the gasifier is separated into gas and solid phases by a cyclone separator. Fine coal gasification slag with a particle size of <1mm can be collected in the solid phase.

[0052] (2) 8 kg of fine coal gasification slag and 2 kg of coarse coal gasification slag are fed into a mixer 1 and mixed thoroughly. The mixer 1 is heat-treated to maintain the temperature at 450℃. After mixing, the coal gasification slag raw material is fed into a microwave gasifier 2. CO2 gas at 450℃ is also fed into the microwave gasifier 2. The coal gasification slag expands under microwave action for 10 min, which activates the encapsulated carbon components. The reactor temperature is controlled within the range of 1200±50℃ and the space velocity is controlled within the range of 300±10 h⁻¹. -1 Within the range, the microwave power density is 3×10 5 W / m 3 Within the range, the reactor pressure is within the range of 0.2 MPa (G). At this time, the reaction C + CO2 → 2CO occurs in the reactor for 10 minutes, converting the carbon components in the coal gasification slag into CO. After the reaction, the solid components are decarbonized and the fly ash enters the fly ash storage tank 9 for enrichment. The amount of fly ash that can be collected is 3.7 kg.

[0053] (3) The gaseous components enter the spray tower 3 for cooling and metal recovery, with a residence time of approximately 1 minute. The temperature of the gaseous components is adjusted by controlling the spray water volume to lower the temperature below the metal boiling point (400-500℃). The spray water volume is controlled by temperature regulation. Temperature detection instruments are installed in the upper, middle, and lower sections of the spray tower 3. When the temperature is below 450℃, the spraying of condensate water is stopped. The metal-rich components collected at the bottom of the spray tower 3 are sent to the metal recovery storage tank 10 for further separation. The metal-rich components mainly include aluminum oxides and iron oxides.

[0054] (4) The gaseous components at the top of spray tower 3 are separated into water by a water separator 4 after waste heat recovery. Silica gel is used as the dehydrating agent in the water separator 4. The dehydrated water is then fed back into spray tower 3, and the dehydrated gaseous components are separated into the inorganic molecular sieve membrane of the separation membrane device 5. The separated CO enters the carbon monoxide storage tank 7, and the CO product purity is 88.4%. CO2, along with the supplemented CO2 feedstock, is exchanged in the heat exchanger 6 and then enters the microwave gasifier 2 for syngas preparation. The gasification slag carbon conversion rate is ≥85%.

[0055] Comparative Example 1 This comparative example provides a process for the resource utilization of coal gasification slag. The difference between this example and Example 2 is that in step (2), instead of microwave heating, a conventional electric heating reactor is used to replace the microwave gasifier for the reaction.

[0056] The finely ground gasification slag is fed into an electric heating furnace and heated to 1050℃. CO2 diffuses naturally and reacts with the carbon components in the gasification slag. The reaction time is 60 minutes. After the reaction, the CO purity is 72%, and the gasification slag residual carbon conversion rate is only 52%.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for the resource utilization of coal gasification slag, characterized in that, include: Microwave gasifier, used for the carbon conversion reaction of coal gasification slag and carbon dioxide; The spray tower is connected to the top of the microwave gasifier; The heat exchangers are connected to the top of the microwave gasifier and the top of the spray tower, respectively. A carbon dioxide storage tank is connected to the heat exchanger; The water distributor is connected to the spray tower and the heat exchanger respectively; The separation membrane device is connected to the water separator and the carbon dioxide storage tank respectively; the separation membrane device is equipped with a separation membrane assembly.

2. The system according to claim 1, characterized in that, The microwave gasifier has multiple sets of magnetrons symmetrically arranged on its top and side walls, and the magnetrons are connected to a coaxial converter via a ring waveguide to form incoherent power combining; each set of magnetrons is connected to a waveguide slot antenna, and the antenna surface has equally spaced rectangular slots; preferably, the multiple sets of magnetrons are 3-6 sets of magnetrons. The inner wall of the reaction chamber of the microwave gasifier is made of a stepped Al2O3 ceramic liner, and the surface is coated with a silver-based reflective coating; preferably, the thickness of the stepped Al2O3 ceramic liner is 5-15 mm; preferably, the microwave reflectivity of the silver-based reflective coating is >95%; The microwave gasifier's reaction chamber is divided into a preheating zone at the top, a main reaction zone in the middle, and a cooling zone at the bottom by horizontal metal partitions arranged axially. Each metal partition has a pre-reserved channel at its center for material to fall. The main reaction zone contains vertically arranged hexagonal honeycomb-shaped quartz reaction tubes. Microwave shielding is inserted between the quartz reaction tubes. A double-layer sieve plate is installed inside each quartz reaction tube; the lower sieve plate supports the material, while the upper sieve plate vibrates vertically via an eccentric wheel mechanism. The entire quartz reaction tube rotates around its axis. The upper and lower sieve plates... An ultrasonic transducer is arranged between the plates; a ring-shaped multi-hole injector is installed at the bottom of the quartz reaction tube, arranged in multiple layers, with each layer independently controlling the CO2 flow rate to achieve axial concentration gradient distribution; a rupture disc is installed at the top of each quartz reaction tube, and each quartz reaction tube is connected to a gas collecting pipe through an independent pipe; preferably, the entire quartz reaction tube rotates around its axis at 5-15 rpm; preferably, the frequency of the vertical vibration is 5-10 Hz, and the amplitude is 2-5 mm; preferably, the frequency of the ultrasonic transducer is 10-30 kHz, and the power density is 40-60 W / cm². 2 .

3. The system according to claim 1 or 2, characterized in that, The separation membrane assembly is an inorganic membrane assembly, preferably a ZIF-8 molecular sieve separation membrane; And / or, the spray tower is filled with metal or ceramic packing material.

4. The system according to any one of claims 1-3, characterized in that, The system also includes a stirrer, which is connected to the microwave gasifier; And / or, the system further includes a fly ash storage tank, which is connected to the bottom of the microwave gasifier; And / or, the system further includes a carbon monoxide storage tank, which is connected to the separation membrane device; And / or, the system further includes a metal recovery tank connected to the bottom of the spray tower.

5. A process for the resource utilization of coal gasification slag, characterized in that, The system described in claims 1-4 is used for implementation; the process includes the following steps: Coal gasification slag at a temperature of 350-450℃ and CO2 gas at a temperature of 350-450℃ are introduced into a microwave gasifier to carry out a carbon conversion reaction. The gaseous components produced by the carbon conversion reaction are passed into a spray tower for cooling; the solid components obtained after cooling are recovered. The gaseous components obtained after cooling in the spray tower are passed into a heat exchanger to exchange heat with CO2 gas from the carbon dioxide storage tank; the CO2 gas after heat exchange is then passed into the microwave gasifier. The gaseous components from the spray tower after heat exchange are fed into a water separator for water removal and separation; the water obtained from water removal and separation is fed back into the spray tower. The gas phase components obtained after water separation by the water separator are fed into the separation membrane device for CO and CO2 separation; the separated CO2 gas is fed into the carbon dioxide storage tank.

6. The process according to claim 5, characterized in that, The carbon conversion reaction was carried out at a temperature of 1000℃-1300℃ and a space velocity of 200 h⁻¹. -1 -400h -1 The microwave power density is 1×10 5 -10×10 5 W / m 3 The reactor pressure is 0.2-0.3 MPa.

7. The process according to claim 5 or 6, characterized in that, Before the coal gasification slag at a temperature of 350-450℃ undergoes a carbon conversion reaction with CO2 gas at a temperature of 350-450℃, the coal gasification slag is expanded under microwave irradiation for 3-10 minutes.

8. The process according to any one of claims 5-7, characterized in that, The coal gasification slag includes fine coal gasification slag with a particle size of <1mm and coarse coal gasification slag with a particle size of 1mm-4mm; preferably, the fine coal gasification slag accounts for 60-80% of the total mass of the coal gasification slag.

9. The process according to any one of claims 5-8, characterized in that, The temperature of the CO2 gas from the carbon dioxide storage tank is 60-110℃.

10. The process according to any one of claims 5-9, characterized in that, The CO product obtained by separating CO and CO2 has a purity greater than 85%.

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