A method for enhancing the chemical chain synergistic gasification of coal char powder using alkali lignin

Abstract

The present invention discloses a method for chemical chain synergistic gasification of coal char powder strengthened by alkali lignin. The method comprises the following steps: chemical chain gasification: subjecting coal char powder, alkali lignin and oxygen carrier to chemical chain synergistic gasification reaction at 700-1000°C; gas-solid separation: separating the reaction product in step S1 at 20-450°C to obtain gas phase product and solid phase product. The present invention realizes the synergistic resource utilization of industrial by-product alkali lignin and coal char powder, which not only solves the problem of harsh reaction conditions and low conversion rate in the conventional thermal conversion process of coal char powder, but also breaks through the alkali metal bottleneck in the resource utilization process of alkali lignin, and realizes the efficient utilization of industrial by-product alkali lignin.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste treatment, and more specifically, relates to a method for alkali lignin-enhanced chemical chain synergistic gasification of coal char powder. Background Art

[0002] my country is a coal-producing country, and its energy structure based on coal is difficult to change in the short term. Coking is one of the main ways to use coal. In 2017, my country's coal coke production was about 431 million tons, and 570 million tons of coking coal were consumed, accounting for 12.7% of the country's total coal consumption. Coal coke powder is a by-product of the production process of coking enterprises. Generally, the powder yield accounts for 3%-5% of the finished coke. Its composition is mainly fixed carbon, volatile matter and ash. Since coal coke powder is generated through complex processes such as high-temperature devolatilization, crushing, and screening, it has low reaction activity and small particle size (less than 5mm), which does not meet the requirements of metallurgy, chemical industry and other industries, and is difficult to be directly recycled, resulting in most of the coal coke powder being cheaply processed or discarded. This not only leads to a large waste of resources, but more seriously, due to the lack of effective management, a large amount of abandoned coal coke powder is piled up in the open air, exposed to wind and sun, causing serious pollution to the environment and endangering human health.

[0003] The main uses of coal char powder are currently recycled coal coking and the preparation of activated carbon. The Chinese invention patent "Preparation method of activated coal char powder for carbon fuel cells" discloses a preparation method of activated coal char powder for carbon fuel cells, which is characterized in that industrial coal char is crushed and ground, and then modified by KOH chemical activation to obtain activated coal char powder. The Chinese invention patent "A combustion method and equipment for coal char powder" discloses a combustion method and equipment for coal char powder, which is characterized in that the coal char powder is burned in a low-speed bed and a high-speed bed in sequence, and the burned particles are mixed with the newly added coal char powder after gas-solid separation, and re-enter the cycle combustion of the above steps to improve the combustion efficiency of the coal char powder.

[0004] The above patents involve the activation of coal char powder and the improvement of combustion efficiency, but do not involve the process of preparing synthesis gas by efficient gasification of coal char powder. In the conventional gasification process of coal char powder, there is not only a bottleneck in reaction kinetics, harsh conversion conditions, and low conversion rate, but also the need to prepare gasification media such as oxygen-rich and water vapor, which is complicated to operate and costly. Direct use of air gasification has the problem of nitrogen dilution.

[0005] Alkali lignin is a by-product of the papermaking industry after separating cellulose from plants. It is rich in lignin and alkali metals. The output of alkali lignin is huge. The global papermaking industry produces 50 million tons of industrial alkali lignin each year, of which only about 10% is made into adhesives, water reducers, dispersants and other products through complex processes such as oxidation and sulfonation. Most of it is directly discarded or used for alkali recovery fuel, which not only causes waste of resources but also poses environmental risks.

[0006] The Chinese invention patent "A demethylated lignin phenolic resin adhesive modified by halogen acid" discloses a demethylated lignin phenolic resin adhesive modified by halogen acid, which is characterized in that the demethylated lignin phenolic resin adhesive is prepared by halogen acid modification, and has the advantages of fast curing speed, good bonding strength, and low formaldehyde emission. The Chinese invention patent "A high-performance lignin-based polyurethane and its preparation method" discloses a high-performance lignin-based polyurethane and its preparation method, which is characterized in that it is prepared by polymerizing lignin-containing polyester polyol, diisocyanate, lignin and organic amine catalyst in a solvent and curing and forming. The Chinese invention patent "A method for preparing a heavy metal adsorbent-lignin microsphere" discloses a method for preparing a heavy metal adsorbent-lignin microsphere, which is characterized in that the lignin microsphere is prepared by using imidazole ionic liquid as a solvent under microwave-assisted dissolution conditions, and the resulting product can efficiently treat heavy metal ion wastewater. The Chinese invention patent "A composite oxygen carrier, preparation method and its application in solid fuel gasification" discloses a composite oxygen carrier, preparation method and method of using the oxygen carrier to gasify carbon-containing solid fuel to produce clean syngas, and uses the oxygen carrier and calcium-based absorbent to design a solid fuel chemical chain gasification process method and device to improve gasification efficiency and remove CO2 to obtain clean syngas. However, the above process is complicated and the conversion efficiency is low.

[0007] In summary, the conventional thermal conversion process of coal char powder has the problems of harsh reaction conditions and low conversion rate, and it also requires the preparation of gasification media such as oxygen-enriched and water vapor. There is an alkali metal restriction bottleneck in the thermal conversion process of alkali lignin. The current treatment method not only wastes resources but also poses environmental risks. Summary of the invention

[0008] In view of the above-mentioned existing technical problems, the purpose of the present invention is to provide a method for alkali lignin enhanced coal tar chemical chain synergistic gasification, which realizes the synergistic resource utilization of industrial by-product alkali lignin and coal tar, and not only solves the problems of harsh reaction conditions and low conversion rate in the conventional coal tar thermal conversion process, but also breaks through the alkali metal bottleneck in the resource utilization of alkali lignin, thereby realizing the efficient utilization of industrial by-product alkali lignin.

[0009] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0010] A method for alkali lignin-enhanced char powder chemical chain synergistic gasification comprises the following steps:

[0011] S1. Chemical chain gasification: Coal char powder, alkali lignin and oxygen carrier are subjected to chemical chain synergistic gasification reaction at 700-1000°C;

[0012] S2. Gas-solid separation: The reaction product in step S1 is separated at 20-450° C. to obtain a gas phase product and a solid phase product.

[0013] The present invention provides a method for alkali lignin-enhanced coal char powder chemical chain synergistic gasification. Compared with the existing method of preparing synthesis gas by coal char powder alone, the present invention greatly improves the yield of synthesis gas and the final fuel carbon conversion rate in the thermal conversion process of coal char powder through the coordinated use of alkali lignin and coal char powder. The synthesis gas yield in the final gas phase product is greater than 2m 3 / kg, and the fuel carbon conversion rate is between 65% and 86%. The present invention realizes the coordinated resource utilization of industrial by-product alkali lignin and coal tar powder, which not only solves the problems of harsh reaction conditions and low conversion rate in the conventional coal tar powder thermal conversion process, but also breaks through the alkali metal bottleneck in the resource utilization process of alkali lignin, and realizes the efficient utilization of industrial by-product alkali lignin. The present invention has the advantages of mild reaction conditions, high resource utilization rate, simple process, low conversion cost, etc., and is of great significance for the coordinated resource treatment of industrial organic waste, improving the efficiency of social resource utilization and improving the ecological environment.

[0014] Specifically, the gases in the gas phase product are mainly H2, CO, CH4, CO2, etc.

[0015] Specifically, the composition of the alkali lignin used in the present invention is: carbon element accounts for 43.99%, nitrogen element accounts for 0.29%, and hydrogen element accounts for 4.77%.

[0016] Further preferably, in step S1, the temperature of the chemical chaining synergistic gasification reaction is 900-1000°C.

[0017] Preferably, in the step S1, the mass ratio of the alkali lignin to the coal char powder is 0.05-0.3:0.4-0.5.

[0018] Preferably, in the step S1, the mass ratio of the oxygen carrier to the coal char powder is 0.3-0.5:0.4-0.5.

[0019] Preferably, in step S1, the reaction time of the chemical chaining synergistic gasification reaction is 35 to 60 minutes.

[0020] Further preferably, in the step S1, the reaction time of the chemical chain synergistic gasification reaction is 45 minutes.

[0021] Preferably, in step S1, in the chemical chaining coordinated gasification reaction, water vapor is introduced to control the ratio of synthesis gas H2 and CO.

[0022] Further preferably, in step S1, the mass ratio of water vapor to oxygen carrier is 0.1-0.2: 1. The inventors have found through research that when the ratio of water vapor to oxygen carrier is within the above range, the ratio of H2 to CO in the gas phase product can be controlled within (1.85-2.15): 1. The gas phase product within this ratio range is beneficial to the subsequent Fischer-Tropsch synthesis, reducing the occurrence of side reactions during the Fischer-Tropsch synthesis process, which is not only efficient but also saves raw materials.

[0023] Preferably, the preparation method of the oxygen carrier is as follows: an oxygen carrier precursor is calcined at 800-1000° C., crushed, and sieved to obtain the oxygen carrier.

[0024] More preferably, the particle size of the oxygen carrier after crushing and screening is controlled in the range of 0.01 to 0.65 mm.

[0025] More preferably, the reaction temperature range of the oxygen carrier is 650-1000°C.

[0026] Further preferably, the oxygen carrier precursor can be prepared by conventional process methods such as mechanical preparation method, chemical self-assembly method or chemical synthesis method.

[0027] Specifically, as an optional implementation, the preparation method of the oxygen carrier is: using pine wood as raw material, pyrolyzing it under a nitrogen atmosphere to obtain biochar; taking a nitrate solution and mixing it evenly, adding the carrier under stirring conditions and mixing it evenly, then adding the biochar, shaking at a constant temperature to make the biochar completely infiltrated, and standing to obtain the oxygen carrier precursor; after calcining the oxygen carrier precursor, the oxygen carrier is obtained.

[0028] Preferably, the pine wood has a mesh size of 20 to 40.

[0029] Preferably, the pyrolysis temperature is 300-400° C. More preferably, the pyrolysis temperature is 350° C.

[0030] Preferably, the pyrolysis time is 1 h.

[0031] Further preferably, the nitrate solution is one or more of Ni(NO3)2 solution, Fe(NO3)3 solution, Al(NO3)3 solution, Mn(NO3)2 solution or Co(NO3)2 solution; and the carrier is dodecylsilane.

[0032] Preferably, the constant temperature oscillation time is 1 to 3 hours. Further preferably, the constant temperature oscillation time is 2 hours.

[0033] Preferably, the standing time is 10 to 12 hours. Further preferably, the standing time is 12 hours.

[0034] Preferably, the calcination temperature is 800-1000°C. More preferably, the calcination temperature is 1000°C.

[0035] Preferably, the calcination time is 4 to 6 hours.

[0036] Preferably, after step S2, the process further comprises calcining the oxygen carrier: calcining the solid phase product separated in step S2 at 800-1000° C., and the calcined oxygen carrier recovers lattice oxygen and returns to step S2 for chemical chain gasification reaction.

[0037] Preferably, the solid phase product is calcined at 800-1000° C. for 30-90 min.

[0038] The present invention has the following beneficial effects: the method for alkali lignin-enhanced coal tar chemical chain synergistic gasification provided by the present invention not only solves the problem of harsh reaction conditions and low conversion rate in the conventional coal tar thermal conversion process, but also breaks through the alkali metal bottleneck in the process of alkali lignin resource utilization, and realizes the efficient utilization of industrial by-product alkali lignin; it avoids the preparation of gasification media such as oxygen-enriched and water vapor in the conventional gasification process. The present invention greatly improves the yield of synthesis gas and the final fuel carbon conversion rate in the process of coal tar thermal conversion, and the yield of synthesis gas in the final gas phase product is greater than 2m 3 / kg, and the fuel carbon conversion rate is between 65% and 86%. The present invention has the advantages of mild reaction conditions, high resource utilization rate, simple process, low conversion cost, etc. It is of great significance for the coordinated resource treatment of industrial organic waste, improving the efficiency of social resource utilization and improving the ecological environment, and the project has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a flow chart of the chemical chain synergistic gasification of coal char powder enhanced by alkali lignin in the present invention. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0041] Example 1

[0042] like Figure 1 As shown, a method for alkali lignin enhanced coal char powder chemical chain synergistic gasification comprises the following steps:

[0043] (1) Preparation of oxygen carrier: The oxygen carrier is prepared by chemical self-assembly method, specifically, 20-40 mesh pine wood is used as raw material, and biochar is prepared by slow pyrolysis at 350°C for 1 hour under N2 atmosphere; Ni(NO3)2 solution, Fe(NO3)3, and Al(NO3)3 solution are mixed uniformly in molar ratio, and dodecylsilane (wherein the atomic ratio of Fe / Ni / Al / Si is 0.5 / 0.3 / 0.1 / 0.1) is added dropwise under stirring conditions, and biochar is added after mixing uniformly; the above mixture is oscillated in a constant temperature oscillator for 2 hours to completely infiltrate the biochar, and then allowed to stand for 12 hours; the mixture is placed in a 105°C oven until the biochar is completely dried to obtain an oxygen carrier precursor; the composite oxygen carrier precursor is calcined at 950°C for 4 hours, crushed, and sieved to obtain a composite oxygen carrier with a particle size range of 0.15-0.25 mm, and the temperature range of the composite oxygen carrier is 650-1000°C.

[0044] (2) Chemical chain gasification: The composite oxygen carrier, coal char powder and alkali lignin prepared in step (1) are subjected to a chemical chain synergistic gasification reaction at 850° C. with a reaction residence time of 45 min. Water vapor is introduced into the chemical chain synergistic gasification reaction to adjust the ratio of syngas H2 / CO to obtain a reaction product; the mass ratio of water vapor to the composite oxygen carrier is 0.1:1, and the mass ratio of alkali lignin, coal char powder and oxygen carrier is 0.1:0.4:0.5.

[0045] (3) Gas-solid separation: The reaction product obtained in step (2) is subjected to gas-solid separation at 150°C, and the particle size range of the solid phase product is 0.25 mm, and a gas phase product and a solid phase product are obtained. The gas phase product is a synthesis gas mainly composed of H2 and CO, which can be used for Fischer-Tropsch synthesis, etc.; the solid phase product contains incompletely reacted coal char powder and alkali lignin semi-coke.

[0046] (4) Calcination of oxygen carrier: The solid phase product after gas-solid separation in step (3) is calcined in air at 900°C for 60 minutes. The calcined oxygen carrier recovers lattice oxygen and returns to step (2) for chemical chain gasification reaction. During the calcination process, the oxygen carrier and the unreacted coal char powder and alkali lignin semi-coke react with air to release heat, which is transferred to the chemical chain gasification process through the circulating oxygen carrier to achieve heat balance of the whole process; the calcination process includes the separation process of combustion exhaust gas and reaction ash, and the ash segmentation particle size is 0.05mm-0.15mm.

[0047] According to the gas chromatography (GC) test, the relative composition of the gas phase product in step (3) is as follows: H2 content is 52.39%, CO2 content is 15.87%, CO content is 26.61%, CH4 content is 4.18%; the fuel conversion rate is 68.73%, and the synthesis gas yield is 2.03 (m 3 / kg), the ratio of H2 / CO is 1.97.

[0048] Embodiments 2 to 6

[0049] The differences between Examples 2 to 6 and Example 1 are shown in Table 1 below.

[0050] Table 1

[0051]

[0052] The relative composition of the gas phase products of Examples 1 to 4 and Comparative Example 1 was tested by gas chromatography (GC), and the test results are shown in Table 2 below:

[0053] Table 2

[0054]

[0055]

[0056] The present invention provides a method for alkali lignin-enhanced synergistic gasification of coal char powder chemical chain, which greatly improves the yield of syngas and the final fuel carbon conversion rate during the thermal conversion of coal char powder. It can be seen from the data in Table 2 above that the syngas yield of the gas phase products prepared in the final embodiments 1 to 4 is greater than 2m 3 / kg, and the fuel carbon conversion rate is between 65% and 86%. The syngas yield and final fuel carbon conversion rate of the gas phase products of Examples 5-6 are similar to those of Example 1. From the data in Table 2 above, it can be seen that Comparative Example 1 is a comparative example without using alkali lignin, and the syngas yield in Comparative Example 1 is 0.82m 3 / kg, and the fuel carbon conversion rate was 46.35%, which was much lower than the fuel carbon conversion rate and syngas yield in Examples 1 to 6. This shows that alkali lignin and coal char powder have synergistic utilization, which can greatly improve the fuel carbon conversion rate and syngas yield of the product.

[0057] The method for alkali lignin-enhanced coal char chemical chain synergistic gasification provided by the present invention not only solves the problems of harsh reaction conditions and low conversion rate in the conventional coal char thermal conversion process, but also breaks through the alkali metal bottleneck in the process of resource utilization of alkali lignin, and realizes the efficient utilization of industrial by-product alkali lignin; it avoids the preparation of gasification media such as oxygen-enriched and water vapor in the conventional gasification process. The present invention greatly improves the yield of synthesis gas and the final fuel carbon conversion rate in the process of coal char thermal conversion, and the yield of synthesis gas in the final gas phase product is greater than 2m 3 / kg, and the fuel carbon conversion rate is between 65% and 86%. The present invention has the advantages of mild reaction conditions, high resource utilization rate, simple process, low conversion cost, etc. It is of great significance for the coordinated resource treatment of industrial organic waste, improving the efficiency of social resource utilization and improving the ecological environment, and the project has broad application prospects.

[0058] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for alkali lignin enhanced coal char chemical chain synergistic gasification, comprising the following steps: S1. Chemical chain gasification: Coal char powder, alkali lignin and oxygen carrier are subjected to chemical chain synergistic gasification reaction at 950°C, and the reaction time of the chemical chain synergistic gasification reaction is 35 to 60 minutes; S2. Gas-solid separation: separating the reaction product in step S1 at 20 to 450° C. to obtain a gas phase product and a solid phase product; The preparation method of the oxygen carrier is as follows: using pine wood as a raw material, pyrolyzing it in a nitrogen atmosphere to obtain biochar; The nitrate solution is mixed evenly, and a carrier is added under stirring, wherein the carrier is dodecylsilane; wherein the atomic ratio of Fe / Cu / Ca / Si is 0.4 / 0.2 / 0.2 / 0.2; after being mixed evenly, the biochar is added, and the mixture is shaken at a constant temperature so that the biochar is completely infiltrated, and the mixture is allowed to stand to obtain an oxygen carrier precursor; After the oxygen carrier precursor is calcined, a composite oxygen carrier is obtained; The mass ratio of the alkali lignin to the coal char powder is 0.05-0.3:0.4-0.5; the mass ratio of the oxygen carrier to the coal char powder is 0.3-0.5:0.4-0.

5.

2. The method according to claim 1, characterized in that: In the step S1, in the chemical chain coordinated gasification reaction, water vapor is introduced to adjust the ratio of synthesis gas H2 and CO, and the mass ratio of water vapor to oxygen carrier is 0.1-0.2:

1.

3. The method according to claim 1, characterized in that: The pyrolysis temperature is 300-400°C.

4. The method according to claim 1, characterized in that: The calcination temperature is 800-1000°C.

5. The method according to claim 1, characterized in that: After step S2, the method further includes calcining the oxygen carrier: calcining the solid phase product separated in step S2 at 800-1000° C., and the calcined oxygen carrier recovers lattice oxygen and returns to step S1 to carry out chemical chain coordinated gasification reaction.

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