A method for preparing combustible gas using coal gasification slag
By screening the coal gasification slag by particle size and mixing it with an inert medium, and using a mixture of oxygen and carbon dioxide for smoldering reaction, the problems of coal gasification slag melting and slagging and low gasification efficiency were solved, thus achieving stable and efficient production of combustible gas and effective utilization of carbon resources.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING HUANENG CHANGJIANG ENVIRONMENTAL PROTECTION TECH RES INST CO LTD
- Filing Date
- 2026-02-04
- Publication Date
- 2026-06-02
AI Technical Summary
Existing technologies for treating coal gasification slag using smoldering have problems such as melting and slagging, low gasification efficiency, and poor reaction uniformity. In particular, the coal gasification slag is rich in components such as SiO2, Al2O3, CaO, and Fe2O3, which are prone to forming low eutectic substances at high temperatures, leading to unstable equipment operation. Furthermore, the mixture of ash and residual carbon affects the reaction effect.
By screening the coal gasification slag by particle size, coal gasification slag with a particle size ≤2mm is mixed with an inert heat storage medium to form a stable porous structure. A mixture of oxygen and carbon dioxide is used as the gasification agent for smoldering reaction. The reaction temperature is controlled at 800-1200℃ to avoid melting and agglomeration and to improve the uniform distribution of the gasification agent.
It significantly alleviated the problem of molten slag formation, improved the yield and quality of combustible gas, achieved stable smoldering of coal gasification slag and safe operation of equipment, and enhanced the resource utilization efficiency of carbon resources.
Smart Images
Figure CN122128016A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of solid waste resource utilization technology, specifically relating to a method for preparing combustible gas using coal gasification slag. Background Technology
[0002] Coal gasification slag is a large amount of solid waste generated by the coal chemical industry, with a huge annual output. Its characteristics of high ash content, low calorific value and high moisture content lead to problems such as low efficiency, high energy consumption, easy slagging and high risk of secondary pollution in traditional disposal methods (such as landfill, building material utilization, and circulating fluidized bed co-firing).
[0003] Smoldering technology, as a thermal treatment technology suitable for organic solid waste with high water content and low calorific value, has advantages such as no need for pre-drying, self-sustaining combustion, and low energy consumption. However, applying smoldering technology directly to coal gasification slag faces the following prominent challenges: Coal gasification slag is rich in components such as SiO2, Al2O3, CaO, and Fe2O3, which easily form low-melting-point substances in the high-temperature smoldering zone (often above 1000℃), leading to ash melting, agglomeration, and caking. This severely hinders the continuous propagation of the smoldering reaction and the normal flow of materials, affecting the long-term stable operation of the equipment. Furthermore, the ash and residual carbon in the coal gasification slag are mixed, and the high ash content dilutes the effective carbon concentration in the reaction system and hinders the full contact between the gasifying agent (such as O2 and CO2) and the residual carbon, resulting in low yield of combustible gas (such as CO) and failure to maximize resource value. In addition, the coal gasification slag has a wide particle size distribution, with significant differences in physicochemical properties between coarse particles (such as glassy slag >1mm) and fine particles, leading to inconsistent reaction behavior during smoldering and affecting the stability and controllability of the overall treatment effect. Summary of the Invention
[0004] This application provides a method for preparing combustible gas using coal gasification slag, aiming to solve the problems of melting and slagging, low gasification efficiency, and poor reaction uniformity in existing methods for treating coal gasification slag by smoldering.
[0005] This application provides a method for preparing combustible gas using coal gasification slag, comprising the following steps:
[0006] (1) Mix coal gasification slag with a particle size ≤2mm with an inert heat storage medium to obtain a mixture; (2) The mixture is subjected to a smoldering reaction under the action of a gasifying agent to obtain combustible gas.
[0007] The method for preparing combustible gas using coal gasification slag described in this application improves the ash melting point of the mixture by screening the coal gasification slag, avoiding the problems of melting, agglomeration, and caking of the coal gasification slag at high temperatures, thus ensuring the continuity of the smoldering process and the safe operation of the equipment. Furthermore, the method for preparing combustible gas using coal gasification slag in this application screens the particle size of the coal gasification slag, allowing for more thorough mixing with the inert medium. The resulting mixture has a more stable porous structure, which is beneficial for the uniform distribution of the gasifying agent and heat transfer, making the smoldering reaction more stable and its propagation more controllable, and achieving the oxidation / gasification of residual carbon in the coal gasification slag.
[0008] According to some embodiments of the method for preparing combustible gas using coal gasification slag described in this application, the mass ratio of the coal gasification slag to the inert heat storage medium is (2-4):1.
[0009] According to some embodiments of the method for preparing combustible gas using coal gasification slag described in this application, the inert heat storage medium includes quartz sand and / or alumina.
[0010] According to some embodiments of the method for preparing combustible gas using coal gasification slag described in this application, the gasifying agent includes a mixture of oxygen and carbon dioxide, and / or air.
[0011] According to some embodiments of the method for preparing combustible gas using coal gasification slag described in this application, in step (2), a preheated gasifying agent is introduced into the mixture to carry out a smoldering reaction.
[0012] According to some embodiments of the method for preparing combustible gas using coal gasification slag described in this application, the flow rate of the gasifying agent is 15-35 L / min.
[0013] According to some embodiments of the method for preparing combustible gas using coal gasification slag described in this application, when the gasifying agent is a mixture of oxygen and carbon dioxide, the volume content of oxygen in the gasifying agent is 20%-40%.
[0014] According to some embodiments of the method for preparing combustible gas using coal gasification slag described in this application, the temperature at which the gasifying agent is introduced into the mixture is 200-400°C.
[0015] According to some embodiments of the method for preparing combustible gas using coal gasification slag described in this application, the smoldering temperature is 800-1200℃, and the average peak temperature of the reaction zone is preferably 1000-1100℃.
[0016] According to some embodiments of the method for preparing combustible gas using coal gasification slag described in this application, the combustible gas includes carbon monoxide (CO), hydrogen (H2), hydrocarbon compounds, and carbon dioxide (CO2).
[0017] The beneficial effects of this application include: the method for preparing combustible gas using coal gasification slag described in this application can significantly alleviate the melting and slagging problem during the smoldering process of coal gasification slag by screening the particle size of the coal gasification slag, while improving the yield and quality of combustible gas obtained from the smoldering of coal gasification slag, and initially achieving the enrichment of carbon resources. Attached Figure Description
[0018] Figure 1 This is a structural diagram of the ash residue obtained after smoldering of coal gasification slag, as described in Embodiment 1 of this application, using the method for preparing combustible gas from coal gasification slag. Figure 2 The diagram shows the structure of the ash residue obtained after the smoldering of the coal gasification slag, which is the method for preparing combustible gas using coal gasification slag as described in Comparative Example 1 of this application. Detailed Implementation
[0019] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0020] 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.
[0021] This application provides a method for preparing combustible gas using coal gasification slag, including the following steps: (1) Mix coal gasification slag with a particle size ≤2mm with an inert heat storage medium to obtain a mixture; (2) The mixture is subjected to a smoldering reaction under the action of a gasifying agent to obtain combustible gas.
[0022] The method for preparing combustible gas using coal gasification slag described in this application improves the ash melting point of the mixture by screening the coal gasification slag, avoiding the problems of melting, agglomeration, and caking of the coal gasification slag at high temperatures, thus ensuring the continuity of the smoldering process and the safe operation of the equipment.
[0023] Furthermore, the method for preparing combustible gas using coal gasification slag described in this application screens the particle size of the coal gasification slag, making it mix more thoroughly with the inert medium. The porous structure of the mixture formed by mixing with the inert medium is more stable, which is conducive to the uniform distribution of the gasifying agent and heat transfer, making the smoldering reaction more stable and its propagation more controllable, and realizing the oxidation / gasification of residual carbon in the coal gasification slag.
[0024] The method for preparing combustible gas using coal gasification slag described in this application only requires conventional screening equipment and does not require the addition of chemical reagents or complex drying and grinding processes. It has low investment and operating costs and is easy to promote and apply in industrial settings. The oversize material (coarse particles) separated by screening has extremely high ash content and extremely low carbon content, and can be directly used for low-value applications such as building materials and roadbeds, achieving "graded disposal and full utilization" of coal gasification slag.
[0025] In some embodiments of this application, the mass ratio of the coal gasification slag to the inert heat storage medium is (2-4):1, for example 2:1, 3:1, 4:1, etc.
[0026] In some embodiments of this application, the inert heat storage medium includes quartz sand and / or alumina. The inert medium (such as quartz sand) mixes with the material to form a stable porous framework, ensuring uniform distribution and penetration of the gasifying agent. Its high heat capacity allows it to store reaction heat and be used to preheat upstream materials, achieving internal heat circulation, which is crucial for self-sustaining smoldering. Simultaneously, it acts as a physical barrier to effectively prevent ash melting and caking, maintaining bed stability.
[0027] In some embodiments of this application, the vaporizing agent comprises a mixture of oxygen and carbon dioxide, and / or air. The vaporizing agent provides the necessary oxygen (O2) for smoldering, driving an exothermic oxidation reaction to maintain process self-sustainability. More importantly, when using a mixture of O2 and CO2, CO2 undergoes a Bourdon reaction with residual carbon in the high-temperature zone (C + CO2 → 2CO), efficiently converting fixed carbon into combustible gas CO, significantly improving gas quality and yield, and allowing for adjustment of the reaction temperature and atmosphere through proportional control.
[0028] In some embodiments of this application, in step (2), a preheated gasifying agent is introduced into the mixture to carry out a smoldering reaction.
[0029] In some embodiments of this application, the flow rate of the vaporizing agent is 15-35 L / min; for example, 15 L / min, 18 L / min, 25 L / min, 28 L / min, 32 L / min, 35 L / min, etc.
[0030] In some embodiments of this application, when the vaporizing agent is a mixture of oxygen and carbon dioxide, the volume content of oxygen in the vaporizing agent is 20%-40%, such as 20%, 25%, 30%, 38%, 40%, etc.
[0031] In some embodiments of this application, the temperature of the vaporizing agent introduced into the mixture is 200-400°C, such as 200°C, 220°C, 250°C, 280°C, 320°C, 380°C, 400°C, etc.
[0032] In some embodiments of this application, the smoldering temperature is 800-1200℃; for example, 800℃, 900℃, 1000℃, 1050℃, 1100℃, 1200℃, etc.
[0033] In some embodiments of this application, the combustible gas includes carbon monoxide (CO), hydrogen (H2), hydrocarbon compounds, and carbon dioxide (CO2), with relatively small amounts of hydrogen and hydrocarbon compounds, and mainly CO gas.
[0034] The technical solution of this application will be further described below with reference to specific embodiments.
[0035] Example 1 A method for preparing combustible gas using coal gasification slag includes the following steps: An original sample of coal gasification slag from Jingmen, Hubei Province, was analyzed for its ash content of 77.17% and fixed carbon content of 17.53%. Sieving was performed using a 1mm standard sieve, yielding approximately 61.3% of the sieved material (coal gasification slag with a particle size less than or equal to 1mm) by mass, with its carbon content increasing to approximately 35.10%. The sieved material was then uniformly mixed with quartz sand with a particle size of 0.8-1.2mm at a mass ratio of 3:1 (sand-material ratio).
[0036] The mixture is filled into a 15cm inner diameter, kilogram-level smoldering reactor to a height of 45cm. Preheated air at 300°C is introduced from the bottom for ignition. After the bottom is stably burning, external heating is stopped, and air is continuously introduced at a flow rate of 25L / min to allow the smoldering wave to propagate from bottom to top.
[0037] Thermocouple temperature monitoring showed that the smoldering process of the coal gasification slag in this embodiment was stable, with an average peak temperature of approximately 1050℃, and no severe melting and slagging phenomenon was observed. After the reaction, the average volume concentration of CO in the outlet flue gas was measured to be 7.5%, and the decarbonization rate of the coal gasification slag remained above 98%.
[0038] Example 2 A method for preparing combustible gas using coal gasification slag includes the following steps: An original sample of coal gasification slag from Jingmen, Hubei Province, was analyzed for its ash content of 77.17% and fixed carbon content of 17.53%. Sieving was performed using a 1mm standard sieve, yielding approximately 61.3% of the sieved material (coal gasification slag with a particle size less than or equal to 1mm) by mass, with its carbon content increasing to approximately 35.10%. The sieved material was then uniformly mixed with quartz sand with a particle size of 0.8-1.2mm at a mass ratio of 3:1 (sand-material ratio).
[0039] The mixture is filled into a 15cm inner diameter, kilogram-level smoldering reactor to a height of 45cm. A mixture of oxygen and carbon dioxide preheated to 300℃ is introduced from the bottom for ignition (the volume ratio of oxygen to carbon dioxide is 3:7). After the bottom is stably burning, external heating is stopped, and the mixture of oxygen and carbon dioxide is continuously introduced at a flow rate of 25 L / min to allow the smoldering wave to propagate from bottom to top.
[0040] Thermocouple temperature monitoring showed that the smoldering process of the coal gasification slag in this embodiment was stable, with an average peak temperature of approximately 1050℃, and no severe melting and slagging was observed. After the reaction, the average volume concentration of CO in the outlet flue gas was measured to be 20%, and the decarbonization rate of the coal gasification slag remained above 98%.
[0041] Example 3 The method for preparing combustible gas using coal gasification slag described in Example 3 differs from that in Example 1 only in that a 2mm standard sieve is used for sieving during the preparation of combustible gas using coal gasification slag in Example 3 to obtain coal gasification slag with a particle size of less than or equal to 2mm. The remaining operation steps are the same as in Example 1.
[0042] Thermocouple temperature monitoring showed that the smoldering process of the coal gasification slag in this embodiment was stable, with an average peak temperature of approximately 1020℃, and no severe melting and slag formation was observed. After the reaction, the average volume concentration of CO in the outlet flue gas was measured to be 6.8%, and the decarbonization rate of the coal gasification slag remained above 97%.
[0043] Comparative Example 1 The only difference between the method for preparing combustible gas using coal gasification slag described in Comparative Example 1 and Example 1 is that a 4mm standard sieve is used for sieving during the process of preparing combustible gas using coal gasification slag in Comparative Example 1 to obtain coal gasification slag with a particle size of less than or equal to 4mm. The remaining operation steps are the same as in Example 1.
[0044] Thermocouple temperature monitoring showed that localized melting and slagging were observed during the smoldering process, indicating poor reaction propagation stability. After the reaction, the average volume concentration of CO in the outlet flue gas was measured to be only about 4.5%, with a decarbonization rate of approximately 90%.
[0045] Comparative Example 2 The only difference between the method for preparing combustible gas using coal gasification slag described in Comparative Example 2 and Example 1 is that the coal gasification slag is directly mixed with quartz sand in the process of preparing combustible gas using coal gasification slag in Comparative Example 2, while the other operation steps are the same as in Example 1.
[0046] Thermocouple temperature monitoring showed that severe ash melting and agglomeration occurred during the smoldering process, causing the reaction to be interrupted at one point. After the reaction ended, the average volume concentration of CO in the outlet flue gas was measured to be only about 4.6%, and the decarbonization rate was about 92%.
[0047] The method for preparing combustible gas using coal gasification slag described in Example 1 of this application, and the ash structure diagrams of the coal gasification slag after smoldering and the original coal gasification slag after smoldering described in Comparative Example 2 are respectively shown in the figures below. Figure 1 and Figure 2 As shown.
[0048] from Figure 1 and Figure 2 As can be seen from the above, the ash obtained by the method described in Example 1 of this application does not form slag, while the ash obtained by the method described in Comparative Example 2 does form slag.
[0049] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.
Claims
1. A method for preparing combustible gas using coal gasification slag, characterized in that, Includes the following steps: (1) Mix coal gasification slag with a particle size ≤2mm with an inert heat storage medium to obtain a mixture; (2) The mixture is subjected to a smoldering reaction under the action of a gasifying agent to obtain combustible gas.
2. The method for preparing combustible gas using coal gasification slag according to claim 1, characterized in that, The mass ratio of the coal gasification slag to the inert heat storage medium is (2-4):
1.
3. The method for preparing combustible gas using coal gasification slag according to claim 1, characterized in that, The inert heat storage medium includes quartz sand and / or alumina.
4. The method for preparing combustible gas using coal gasification slag according to claim 1, characterized in that, The vaporizing agent includes a mixture of oxygen and carbon dioxide, and / or air.
5. The method for preparing combustible gas using coal gasification slag according to claim 1, characterized in that, In step (2), a preheated gasifying agent is introduced into the mixture to carry out a smoldering reaction.
6. The method for preparing combustible gas using coal gasification slag according to claim 5, characterized in that, The flow rate of the gasifying agent is 15-35 L / min.
7. The method for preparing combustible gas using coal gasification slag according to claim 4, characterized in that, When the gasifying agent is a mixture of oxygen and carbon dioxide, the volume content of oxygen in the gasifying agent is 20%-40%.
8. The method for preparing combustible gas using coal gasification slag according to claim 5, characterized in that, The temperature at which the gasifying agent is introduced into the mixture is 200-400℃.
9. The method for preparing combustible gas using coal gasification slag according to claim 1, characterized in that, The smoldering temperature is 800-1200℃.
10. The method for preparing combustible gas using coal gasification slag according to claim 1, characterized in that, The combustible gas includes carbon monoxide (CO), hydrogen (H2), hydrocarbon compounds, and carbon dioxide (CO2).