Method for preparing co-rich fuel gas on basis of gasification slag smoldering technique

Abstract

The present invention belongs to the technical field of the treatment of solid waste. Disclosed is a method for preparing a CO-rich fuel gas on the basis of a gasification slag smoldering technique. The method is carried out in a smoldering reaction device. By combining a smoldering treatment technique with the processes of drying, dehydration, pyrolysis, gasification, oxidation, etc., of gasification slag and controlling corresponding reaction conditions, a CO-rich fuel gas with a low oxygen concentration can be ultimately prepared, thereby achieving the efficient utilization and harmless treatment of gasification slag. In the method for preparing a CO-rich fuel gas on the basis of a gasification slag smoldering technique in the present invention, the steps are simple, and the control involved therein is convenient and fast; by means of fully combining the smoldering treatment technique with the processes of drying, dehydration, pyrolysis, gasification, oxidation, etc., of the gasification slag, the efficient treatment of the gasification slag can be achieved, the CO-rich fuel gas with a low oxygen concentration is obtained, and combustible components in the gasification slag are fully recycled, thereby achieving the recycling of resources and adequately ensuring the availability of the recycled resources; and the method has very high economic value.

Description

A method for preparing CO-rich fuel gas based on gasification slag smoldering technology [Technical Field]

[0001] This invention belongs to the field of solid waste treatment technology, specifically relating to a method for preparing CO-rich fuel gas based on gasification slag smoldering technology. [Background Technology]

[0002] my country's energy structure, characterized by "abundant coal, scarce oil, and limited gas," dictates that coal remains the primary energy source. Coal gasification, a core technology for the clean and efficient utilization of coal, is hailed as the leading technology in the modern coal chemical industry and is widely used in fields such as steel, machinery, chemicals, and building materials.

[0003] In the coal gasification process, coarse gasification ash is usually discharged directly from the bottom of the furnace. Its composition is similar to that of boiler ash, with a low carbon content, and it is mostly used as a blending material for road construction or for backfilling. Fine gasification ash, however, has a high carbon content and high loss on ignition, failing to meet national and industry standards for building admixtures. It is difficult to use directly in construction and road projects, and there is a lack of effective large-scale disposal methods; it is mostly disposed of through stockpiling or landfilling. However, the landfilling or stockpiling of high-carbon fine gasification ash causes serious resource waste, occupies a large amount of land, generates dust causing air pollution, and leachate from prolonged stockpiling or landfilling pollutes soil and water bodies.

[0004] Therefore, effectively utilizing gasification slag has become a key focus for researchers. Large-scale, rational, and effective methods for consuming gasification slag can not only mitigate its environmental impact but also recover its energy, thus ensuring the sustainable development of coal chemical enterprises. Currently, the energy recovery method for gasification slag is combustion. While this method can utilize the energy of gasification slag, it requires low-ratio co-firing to maintain stable operation of the combustion equipment. Furthermore, its high water content often leads to unstable combustion, hindering large-scale utilization. Large-scale co-firing necessitates additional dehydration and drying treatment, resulting in high energy consumption, complex equipment systems, and poor economic efficiency. [Summary of the Invention]

[0005] In response to one or more of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a method for preparing CO-rich fuel gas based on the smoldering technology of gasification slag. This method can realize the gasification of gasification slag and produce high-concentration CO fuel gas based on the principle of smoldering, realize the full utilization of combustible substances in gasification slag, and solve the environmental problems caused by the inability to dispose of and utilize gasification slag on a large scale.

[0006] To achieve the above objectives, the present invention provides a method for preparing CO-rich fuel gas based on gasification slag smoldering technology. This method is carried out in a smoldering reactor and includes the following steps:

[0007] (1) Prepare a mixture with porous properties by mixing gasification slag with an inert medium;

[0008] The moisture content of the gasification slag is controlled between 10% and 90%; the particle size of the inert medium is between 1 and 3 mm, and the mass ratio of the gasification slag to the inert medium is between 1:1 and 1:6.

[0009] (2) Fill the mixture into the smoldering reaction device, start the bottom heating component of the smoldering reaction device to preheat the bottom layer of material until the temperature of the bottom layer of material reaches the ignition temperature and then stop heating.

[0010] (3) The reaction gas is introduced from the bottom of the smoldering reaction device and ignited to start the smoldering reaction of the mixture. A high-temperature high-oxygen oxidation zone, a high-temperature low-oxygen oxidation zone, a low-oxygen pyrolysis zone and a low-temperature low-oxygen drying zone are formed from bottom to top in the smoldering reaction device to complete the high-temperature oxidation process, high-temperature gasification process, pyrolysis process and drying process of the gasified slag at different locations of the smoldering reaction device respectively.

[0011] The Darcy velocity of the reactant gas is controlled at 1 cm / s to 15 cm / s, and the oxygen concentration is 10% to 30%, ensuring that the core reaction temperature in the high-temperature and high-oxygen oxidation zone is not lower than 900°C, and the oxygen concentration at the end of the high-temperature and high-oxygen oxidation zone is controlled at 2% to 6%; the gasification reaction temperature in the high-temperature and low-oxygen oxidation zone is controlled above 800°C, and the oxygen concentration at the end of the high-temperature and low-oxygen oxidation zone is controlled below 1%.

[0012] (4) The flue gas is discharged from the exhaust port from the top of the smoldering reaction device to obtain CO-rich low-oxygen fuel gas.

[0013] As a further improvement of the present invention, the gasification slag is a gasification coarse slag with a moisture content of less than 30%, and its mass ratio with the inert medium is between 1:1 and 1:3.

[0014] or

[0015] The gasification slag is a fine gasification slag with a moisture content of more than 30%, and its mass ratio with the inert medium is between 1:2 and 1:5.

[0016] As a further improvement of the present invention, the inert medium is quartz sand or sand.

[0017] As a further improvement of the present invention, the low-oxygen pyrolysis zone includes a high-temperature low-oxygen pyrolysis zone, a medium-temperature low-oxygen pyrolysis zone, and a low-temperature low-oxygen pyrolysis zone formed sequentially from bottom to top, with the temperature ranges of the three zones being no less than 800℃, 500~800℃, and 200~500℃, respectively.

[0018] As a further improvement of the present invention, the CO-rich low-oxygen fuel gas obtained has a CO concentration of not less than 10% and an oxygen concentration of less than 1%.

[0019] As a further improvement of the present invention, the reaction gas fed into the smoldering reaction device is mixed with CO2 in a concentration range of 0 to 85%.

[0020] As a further improvement of the present invention, a residue zone is provided at the bottom of the smoldering reaction device, which is located below the high temperature and high oxygen oxidation zone, for discharging the gasification residue after the oxidation reaction.

[0021] As a further improvement of the present invention, the core reaction temperature in the high-temperature and high-oxygen oxidation zone is controlled at 900-1100°C.

[0022] As a further improvement of the present invention, the initial reaction temperature of the high-temperature low-oxygenation zone is controlled above 850°C, and the final reaction temperature of the high-temperature low-oxygenation zone is controlled above 800°C.

[0023] As a further improvement of the present invention, the monitoring of the temperature of each reaction zone in the smoldering reaction device is achieved by arranging multiple thermocouples at intervals from bottom to top inside the device.

[0024] The aforementioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0025] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include:

[0026] (1) The method for preparing CO-rich gas based on the smoldering technology of gasification slag in this invention is carried out in a smoldering reaction device. By combining the smoldering treatment technology with the processes of drying, dehydration, pyrolysis, gasification, and oxidation of gasification slag, and controlling the corresponding reaction conditions, CO-rich gas with low oxygen concentration can be obtained in the end. This achieves efficient utilization and harmless treatment of gasification slag, effectively improves the efficiency of coal resource development and utilization, and avoids waste of resources.

[0027] (2) The method for preparing CO-rich fuel gas based on gasification slag smoldering technology in this invention is carried out in a low-oxygen, strong reducing atmosphere for most of the processing. This can effectively inhibit the generation of nitrogen oxides, effectively ensure the cleanliness of the fuel, and avoid environmental pollution when the fuel is used.

[0028] (3) The method for preparing CO-rich gas based on the smoldering technology of gasification slag in this invention further enhances the gasification reaction of carbon in gasification slag by mixing a certain concentration of CO2 gas into the gas introduced into the smoldering reaction device, thereby further improving the gasification effect and the CO concentration in the outlet flue gas, and improving the quality of the gas produced.

[0029] (4) The method for preparing CO-rich gas based on the smoldering technology of gasification slag in this invention has simple steps and convenient control. By fully combining the smoldering treatment technology with the processes of drying, dehydration, pyrolysis, gasification and oxidation of gasification slag, the gasification slag can be efficiently treated and CO-rich gas with low oxygen concentration can be obtained. The combustible components in the gasification slag are fully recovered, the resource is recycled and utilized, and the usability of the recycled resources is fully guaranteed, which has extremely high economic value. [Attached Image Description]

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 is a schematic diagram of a system for preparing CO-rich fuel gas using gasification slag in an embodiment of the present invention.

Detailed Implementation Methods

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0037] Example:

[0038] Please refer to Figure 1. The preferred embodiment of the present invention describes a method for preparing CO-rich fuel gas based on gasification slag smoldering technology. This method utilizes smoldering technology and employs a synergistic process of gasification slag drying and dehydration, and gasification / oxidation decarbonization to prepare CO-rich fuel gas. This integrated method for preparing CO fuel gas includes the following steps:

[0039] (1) Preparation of the mixture;

[0040] In actual operation, it is preferable to mix the gasification slag with an inert medium in a certain proportion to form a mixture with porous characteristics.

[0041] In a preferred embodiment, the gasification slag is preferably fine gasification slag or coarse gasification slag, with its moisture content preferably controlled between 10% and 80%. Coarse gasification slag is the water-containing slag discharged from the bottom slag hopper of the gasifier after the slurry coal particles have undergone melting, quenching, and condensation processes under high temperature and pressure conditions in the gasifier. Its residual carbon content varies considerably depending on the coal type, gasifier type, and gasifier operating conditions, generally ranging from 10% to 30%, with particle sizes concentrated between 16 mesh and 4 mesh. Fine gasification slag is generally the water-containing slag carried out from the top of the gasifier by the flow of coarse coal gas, and obtained after preliminary washing, purification, and sedimentation. It has a higher residual carbon content, generally exceeding 30%, and a particle size of less than 16 mesh, with approximately one-third being less than 200 mesh.

[0042] Meanwhile, in the preferred embodiment, the inert medium is preferably quartz sand or sand with a particle size between 1 and 3 mm, and its moisture content is preferably controlled below 20% when used in combination.

[0043] More specifically, in a preferred embodiment, the mass ratio of gasification slag to inert medium is preferably between 1:1 and 1:6, and the specific ratio is preferably determined by the particle size characteristics of the gasification slag (mainly by the moisture content and calorific value).

[0044] When the gasification slag is fine gasification slag, its moisture content is usually above 30%. In this case, the mass ratio between the fine gasification slag and the inert medium is preferably controlled between 1:2 and 1:5.

[0045] Accordingly, when the gasification slag is coarse gasification slag, its moisture content is below 30%. At this time, the optimal mass ratio of coarse gasification slag to inert medium is preferably controlled between 1:1 and 1:3.

[0046] (2) Feed the mixed fuel into the corresponding smoldering reaction device, start the bottom heating component of the smoldering reaction device to preheat the material at the bottom of the reaction device until the temperature of the material at the bottom reaches the ignition temperature and then stop heating.

[0047] In a preferred embodiment, the preheating temperature (ignition temperature) of the mixture is preferably 250°C to 400°C, and more preferably 300°C.

[0048] (3) The reaction gas is introduced from the bottom of the smoldering reaction device and ignited to start the smoldering reaction of the porous mixture. The smoldering reaction device is formed from bottom to top in the following order: high temperature and high oxygen oxidation zone, high temperature and low oxygen oxidation zone, low oxygen pyrolysis zone (high temperature and low oxygen pyrolysis zone, medium temperature and low oxygen pyrolysis zone, low temperature and low oxygen pyrolysis zone), low temperature and low oxygen drying zone and fresh mixture replenishment zone.

[0049] Specifically, during the smoldering reaction process, the mixture located in the lower layer of the smoldering reaction device undergoes an oxidation reaction in a high-oxygen environment with a core reaction temperature of not less than 900°C, forming a high-temperature, high-oxygen oxidation zone, which produces high-temperature, low-oxygen, high-concentration CO2 flue gas, referred to as the first flue gas. The temperature of the first flue gas is not less than 850°C, and the oxygen concentration in it is between 4% and 6%.

[0050] In the high-temperature, high-oxygen oxidation zone, the oxidation reaction of the mixture is as follows: C + O2 → CO2 (1)

[0051] To ensure the accuracy of the oxidation reaction in the high-temperature, high-oxygen oxidation zone, the oxygen concentration in the initial stage of the zone is controlled at above 15%, and the oxygen concentration in the final stage is controlled at 2%–6%. More preferably, the oxygen concentration in the initial stage is controlled between 10% and 30%. Simultaneously, the highest temperature in the core reaction zone within the high-temperature, high-oxygen oxidation zone is preferably controlled at above 900°C.

[0052] For the above control conditions, if the oxygen concentration in the initial stage is too low, the intensity of the exothermic oxidation reaction in reaction (1) will be relatively weak, and the exothermic reaction temperature will not be sufficient to generate a high-temperature environment above 900°C, resulting in a relatively weak subsequent gasification reaction and a low CO concentration, thus failing to achieve the purpose of producing CO-rich fuel gas. At the same time, if the oxygen concentration in the final stage is too high, the carbon in the gasification slag in the high-temperature and low-oxygen gasification zone will undergo a rapid combustion reaction, and the combustion reaction (i.e., the aforementioned oxidation reaction (1)) will be significantly stronger than the expected gasification reaction, resulting in a relatively low CO concentration in the flue gas, thus failing to achieve the purpose of producing CO-rich fuel gas.

[0053] To achieve the above objectives, in actual operation, it is preferable to control the oxygen content of the gas fed into the smoldering reactor to be between 10% and 30%, and the Darcy velocity of the gas to be between 1 cm / s and 15 cm / s; correspondingly, the reaction temperature in the high-temperature, high-oxygen oxidation zone is maintained at 900–1100°C. The adjustment of this reaction temperature can be achieved by changing the oxygen concentration in the supplied gas, which will not be elaborated upon here.

[0054] Furthermore, when the first flue gas flows upward to the adjacent dry material in the upper layer after it is generated, the CO2 in the flue gas and the carbon in the gasification slag undergo a gasification reaction in a high temperature and low oxygen environment. The temperature of this gasification reaction is above 800°C, generating high temperature and low oxygen flue gas rich in CO.

[0055] In the high-temperature, low-oxygenation zone, the gasification reaction between the mixture and the first flue gas is as follows: C + CO2 → 2CO (2)

[0056] In the high-temperature, low-oxygen gasification zone, the core reaction temperature is above 800℃. In the initial section of the high-temperature, low-oxygen gasification zone (the side closest to the high-temperature, high-oxygen oxidation zone), the oxygen concentration is relatively high, ranging from 2% to 6%; at this point, the initial reaction temperature in this zone is preferably controlled above 850℃. Correspondingly, after the gasification reaction in the gasification zone, the oxygen in the flue gas is further consumed. In the CO-rich high-temperature, low-oxygen flue gas formed in the final section of the high-temperature, low-oxygen gasification zone, the oxygen concentration is below 1%, and this flue gas is referred to as the second flue gas.

[0057] In the high-temperature low-oxygen oxidation zone, the competition between the above-mentioned reaction (1) and reaction (2) will take place. If the oxygen concentration in this zone is too high and the temperature is lower than the gasification reaction temperature, the oxidation reaction (1) will be significantly stronger than the gasification reaction (2), resulting in a low CO concentration in the second flue gas at the end of the high-temperature low-oxygen oxidation zone, which will not achieve the purpose of producing CO-rich fuel gas. In addition, if the oxygen concentration at the end of the high-temperature low-oxygen oxidation zone is too high, some of the volatile gases generated in the next stage of the pyrolysis zone will react with oxygen rapidly, thereby reducing the concentration of combustible gas in the flue gas and causing some of the carbon in the gasification slag to be consumed in this stage, thereby reducing the carbon content participating in the reaction in the high-temperature high-oxygen oxidation zone and the high-temperature low-oxygen oxidation zone, affecting the heat release in the oxidation zone and the gasification effect in the gasification zone.

[0058] After passing through the high-temperature, low-oxygenation zone, the oxygen concentration in the flue gas (second flue gas) further decreases, but the flue gas temperature remains in a relatively high range (not lower than 800℃). Subsequently, as the flue gas flows further upward in the smoldering reaction equipment, a high-temperature, low-oxygen pyrolysis zone, a medium-temperature, low-oxygen pyrolysis zone, and a low-temperature, low-oxygen pyrolysis zone are formed sequentially above the high-temperature, low-oxygenation zone. The temperature ranges in the three zones are not lower than 800℃, 500–800℃, and 200–500℃, respectively. By utilizing the mutual contact and interaction between the flue gas and the mixture in each pyrolysis zone, some of the volatiles in the gasification slag are released successively and enter the flue gas, resulting in a third flue gas with a further increased combustible gas content. At this point, the temperature of the third flue gas has dropped below 200℃.

[0059] In actual operation, because the flue gas is in a state of high CO and low oxygen, the concentration of pollutants such as nitrogen oxides in the flue gas can always be kept at a relatively low level.

[0060] Furthermore, after passing through the three pyrolysis zones, the third flue gas flows upward and comes into contact with the fresh mixture fed from above. The residual heat of the third flue gas is used to dry the fresh mixture, forming a low-temperature, low-oxygen drying zone of a certain thickness inside the smoldering reactor, and finally obtaining a moist flue gas rich in CO.

[0061] (4) After utilizing the residual heat in the third flue gas, the final humid flue gas is sent out from the exhaust port of the smoldering reactor. After subsequent condensation and dehydration, a low-oxygen fuel gas rich in CO can be obtained.

[0062] In a preferred embodiment, the CO concentration in the final combustible flue gas is not less than 10%, and the oxygen concentration therein is less than 1%.

[0063] In the preferred embodiment, by adjusting the mixing ratio between the gasification slag and the inert medium, as well as the Darcy flow rate of the gas supplied to the smoldering reactor and the oxygen concentration in the gas, the core reaction temperature in the high-temperature and high-oxygen oxidation zone can be effectively controlled to be no less than 900°C, and the CO concentration in the obtained flue gas can be guaranteed to be no less than 10%.

[0064] More specifically, in order to improve the gasification effect in the high-temperature and low-oxygen gasification zone and increase the CO concentration in the outlet flue gas, it is preferable to mix a certain concentration of CO2 gas into the gas fed into the smoldering reaction device, wherein the mixing concentration is preferably 0-85%, and more preferably 30%.

[0065] Furthermore, a residue zone is formed at the bottom of the smoldering reaction device, which is located below the high-temperature and high-oxygen oxidation zone. The residue after the oxidation reaction is discharged through the discharge port set in the residue zone.

[0066] For existing gasification slag treatment methods, since the gasification slag contains water, its thermal treatment process (such as incineration) requires a large amount of energy to dry it. At the same time, the calorific value of the gasification slag is relatively low and its combustion stability is poor, resulting in very low resource utilization efficiency.

[0067] In contrast, the technical solution of the aforementioned preferred embodiment combines the drying, dehydration, pyrolysis, gasification, and oxidation processes of the gasification slag with smoldering treatment technology. It utilizes the heat generated by the smoldering reaction of the gasification slag itself as a heat source to remove moisture from the slag and dry it. This achieves a self-sustaining reaction without the need for external auxiliary energy, resulting in low energy consumption. Furthermore, through optimized design of the corresponding control conditions, the formation of the appropriate region within the smoldering reaction device can be completed, producing high-concentration CO from the gasification slag to obtain high-quality fuel gas, thus fully realizing the harmless treatment and energy recovery of the gasification slag.

[0068] To further illustrate the advantages and technical effects of the preferred embodiments of the present invention, the following two specific embodiments are provided for supplementary explanation.

[0069] Specific Implementation Example 1:

[0070] In this embodiment, the raw materials used in the preparation of the mixture in process (1) include gasification coarse slag with a moisture content of 36% and quartz sand with a particle size of 1 to 1.5 mm. The gasification coarse slag and quartz sand are mixed in a mass ratio of 1:2 to obtain a mixture with porous characteristics.

[0071] Next, the mixed materials are filled into a laboratory-scale smoldering furnace reactor. The reactor has an inner diameter of 15 cm and a height of 20 cm. Thermocouples are arranged at 3 cm intervals along the height of the reactor to collect temperature data. After the mixture is filled (the material is full), the bottom electric heating device is turned on for preheating.

[0072] Subsequently, when the temperature of the thermocouple at the bottom of the material reaches 350°C, the electric heating device is turned off, the air supply system is turned on to supply gas and ignite; in this embodiment, the composition of the gas intake is controlled to be 21% O2 and 79% N2, the Darcy flow rate of the gas is 5 cm / s, and the reaction begins.

[0073] As the smoldering reaction propagates upwards, each thermocouple along the height of the material monitors the temperature inside the material, with the thermocouple at the bottom having the highest temperature, which is 1050℃.

[0074] Accordingly, by analyzing the composition of the flue gas discharged from the reactor tail end, it was found that the main components of the dried flue gas were: 0.98% O2, 70.72% N2, 8.12% CO2, 20.09% CO, and 80 ppm NO. x .

[0075] Specific Implementation Example 2:

[0076] In this embodiment, the raw materials used in the preparation of the mixture in process (1) include gasification fine slag with a moisture content of 56% and quartz sand with a particle size of 1 to 1.5 mm. The gasification fine slag and quartz sand are mixed in a mass ratio of 1:4 to obtain a mixture with porous characteristics.

[0077] Next, the mixed materials are filled into a laboratory-scale smoldering furnace reactor. The reactor has an inner diameter of 15 cm and a height of 20 cm. Thermocouples are arranged at 3 cm intervals along the height of the reactor to collect temperature data. After filling the mixture, the bottom electric heating device is turned on for preheating.

[0078] Subsequently, when the temperature of the thermocouple at the bottom of the material reaches 350°C, the electric heating device is turned off, the air supply system is turned on to supply gas and ignite; in this embodiment, the composition of the gas intake is controlled to be 21% O2 and 79% N2, the gas Darcy flow rate is 5 cm / s, and the reaction begins.

[0079] As the smoldering reaction propagates upwards, each thermocouple along the height of the material monitors the material temperature at its respective location, with the lowest thermocouple having the highest temperature at 1200℃.

[0080] Accordingly, by analyzing the composition of the flue gas discharged from the reactor tail end, it was found that the main components of the dried flue gas were: 0.73% O2, 67.13% N2, 9.92% CO2, 22.06% CO, and 82 ppm NO. x .

[0081] Clearly, in both specific embodiments, the method in the preferred embodiment can produce CO-rich gas with low oxygen concentration, effectively control the nitrogen oxide content in the final flue gas, increase the calorific value of the produced gas, and achieve efficient treatment of gasification slag.

[0082] The method for preparing CO-rich fuel gas based on the smoldering technology of gasification slag in this invention is simple in steps and convenient to control. By fully combining the smoldering treatment technology with the drying, dehydration, pyrolysis, gasification, and oxidation processes of gasification slag, it is possible to achieve efficient treatment of gasification slag and obtain CO-rich fuel gas with low oxygen concentration. It fully recovers the combustible components in the gasification slag, realizes resource recycling, and fully ensures the usability of the recovered resources, thus having extremely high economic value.

[0083] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing CO-rich fuel gas based on gasification slag smoldering technology, characterized in that, This method is carried out in a smoldering reactor and includes the following processes: (1) Prepare a mixture with porous properties by mixing gasification slag with an inert medium; The moisture content of the gasification slag is controlled between 10% and 90%; the particle size of the inert medium is between 1 and 3 mm, and the mass ratio of the gasification slag to the inert medium is between 1:1 and 1:

6. (2) Fill the mixture into the smoldering reaction device, start the bottom heating component of the smoldering reaction device to preheat the bottom layer of material until the temperature of the bottom layer of material reaches the ignition temperature and then stop heating. (3) The reaction gas is introduced from the bottom of the smoldering reaction device and ignited to start the smoldering reaction of the mixture. A high-temperature high-oxygen oxidation zone, a high-temperature low-oxygen oxidation zone, a low-oxygen pyrolysis zone and a low-temperature low-oxygen drying zone are formed from bottom to top in the smoldering reaction device to complete the high-temperature oxidation process, high-temperature gasification process, pyrolysis process and drying process of the gasified slag at different locations of the smoldering reaction device respectively. The Darcy velocity of the reactant gas is controlled at 1 cm / s to 15 cm / s, and the oxygen concentration is 10% to 30%, ensuring that the core reaction temperature in the high-temperature and high-oxygen oxidation zone is not lower than 900°C, and the oxygen concentration at the end of the high-temperature and high-oxygen oxidation zone is controlled at 2% to 6%; the gasification reaction temperature in the high-temperature and low-oxygen oxidation zone is controlled above 800°C, and the oxygen concentration at the end of the high-temperature and low-oxygen oxidation zone is controlled below 1%. (4) The flue gas is discharged from the exhaust port from the top of the smoldering reaction device to obtain CO-rich low-oxygen fuel gas.

2. The method for preparing CO-rich fuel gas based on gasification slag smoldering technology according to claim 1, characterized in that, The gasification slag is a coarse gasification slag with a moisture content of less than 30%, and its mass ratio with the inert medium is between 1:1 and 1:

3. or The gasification slag is a fine gasification slag with a moisture content of more than 30%, and its mass ratio with the inert medium is between 1:2 and 1:

5.

3. The method for preparing CO-rich fuel gas based on gasification slag smoldering technology according to claim 2, characterized in that, The inert medium is quartz sand or sand.

4. The method for preparing CO-rich fuel gas based on gasification slag smoldering technology according to any one of claims 1 to 3, characterized in that, The low-oxygen pyrolysis zone includes a high-temperature low-oxygen pyrolysis zone, a medium-temperature low-oxygen pyrolysis zone, and a low-temperature low-oxygen pyrolysis zone, which are formed sequentially from bottom to top. The temperature ranges in the three zones are not lower than 800℃, 500~800℃, and 200~500℃, respectively.

5. The method for preparing CO-rich fuel gas based on gasification slag smoldering technology according to any one of claims 1 to 3, characterized in that, The resulting CO-rich low-oxygen fuel gas has a CO concentration of not less than 10% and an oxygen concentration of less than 1%.

6. The method for preparing CO-rich fuel gas based on gasification slag smoldering technology according to any one of claims 1 to 3, characterized in that, The reaction gas fed into the smoldering reactor contains CO2 with a concentration range of 0–85%.

7. The method for preparing CO-rich fuel gas based on gasification slag smoldering technology according to any one of claims 1 to 3, characterized in that, A residue zone is provided at the bottom of the smoldering reaction device, located below the high-temperature and high-oxygen oxidation zone, for discharging the gasification residue after the oxidation reaction.

8. The method for preparing CO-rich fuel gas based on gasification slag smoldering technology according to any one of claims 1 to 3, characterized in that, The core reaction temperature in the high-temperature, high-oxygen oxidation zone is controlled at 900–1100°C.

9. The method for preparing CO-rich fuel gas based on gasification slag smoldering technology according to any one of claims 1 to 3, characterized in that, The initial reaction temperature of the high-temperature low-oxygenation zone is controlled above 850°C, and the final reaction temperature of the high-temperature low-oxygenation zone is controlled above 800°C.

10. The method for preparing CO-rich fuel gas based on gasification slag smoldering technology according to any one of claims 1 to 3, characterized in that, The temperature monitoring of each reaction zone in the smoldering reaction device is achieved by arranging multiple thermocouples at intervals from bottom to top inside the device.

Images