Method for modifying and drying lignite by adopting biomass pyrolysis gas
By modifying dried lignite with biomass pyrolysis gas, a water-blocking layer and passivated hydrophilic groups are formed, which solves the problem of moisture reabsorption in dried lignite, improves the hydrophobicity and combustion reactivity of lignite, and reduces energy input and cost.
Patent Information
- Application Number
- CN202511323813.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-17
- Publication Date
- 2025-12-05
AI Technical Summary
Existing technologies are insufficient to effectively reduce the moisture reabsorption capacity of dry lignite, and traditional modification methods are costly and cannot improve the hydrophobicity and combustion reactivity of lignite while ensuring the integrity of the active structure.
The modification of dry lignite using biomass pyrolysis gas involves the formation of a water-blocking layer on the surface of the lignite by the aromatic components in the biomass pyrolysis gas, which passivates hydrophilic groups and, combined with physical adsorption, blocks the pore size, thereby improving the hydrophobicity and combustion reactivity of the lignite.
Simultaneously, it achieved moisture removal, increased combustible components, and reduced hydrophilicity in lignite, thereby improving the energy density and combustion reactivity of dried lignite, reducing its moisture reabsorption capacity, and lowering its energy input requirements.
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Figure CN121064897A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of lignite upgrading and modification, and particularly relates to a method for modifying dried lignite by using biomass pyrolysis gas. BACKGROUND
[0002] The global proven lignite resource reserves are about 8 billion tons, accounting for about 45% of the total coal reserves; the rich lignite resources endow it with significant economic advantages, so in the current power production capacity, lignite combustion for power generation occupies an important position. However, lignite has the characteristics of high water content (25-65wt%), low energy density, strong self-ignition tendency, etc., which seriously limits its clean and efficient use and safe transportation and storage. And the polar oxygen-containing functional groups on the surface of lignite and the developed pore structure are the key factors affecting the water reabsorption capacity of dried lignite. How to reduce the water reabsorption capacity of dried lignite is one of the difficult problems to be solved in the technology of drying lignite.
[0003] At present, the traditional method is still used in the process of upgrading lignite with high water content. This method lacks the strengthening of the hydrophobicity of dried lignite, and the dried lignite is prone to water reabsorption, which weakens the upgrading effect. Although the physicochemical structure of the particle surface can be regulated to effectively improve the hydrophobicity of dried lignite and enhance the durability of the drying effect. However, the synchronous strengthening of lignite moisture removal and hydrophobicity will face the following problems: the efficient removal of moisture in lignite requires severe drying conditions, which requires a large amount of energy input; deep dehydration will lead to the growth of the pore structure on the surface of lignite, enhancing the water retention of dried particles; effective stripping of hydrophilic groups usually requires a higher drying temperature, which is difficult to greatly improve the hydrophobicity of lignite while ensuring the integrity of its active structure.
[0004] The existing method for weakening the water reabsorption capacity of dried lignite, such as using additives to modify the surface structure of dried lignite. However, the price and doping temperature of the modifier are relatively high, and if it is used as a continuous consumption modifier, it will inevitably cause a substantial increase in the cost of lignite upgrading. SUMMARY
[0005] Based on the above, the present application provides a method for modifying dried lignite by using biomass pyrolysis gas. To achieve the above purpose, the present application provides the following scheme:
[0006] The present application provides a method for modifying dried lignite by using biomass pyrolysis gas, comprising the following steps:
[0007] The lignite is heat treated under an inert atmosphere to obtain dried lignite;
[0008] The biomass is pyrolyzed, and the obtained pyrolysis gas is subjected to heat mass exchange with the dried lignite to obtain modified lignite.
[0009] In a preferred embodiment of the present application, the lignite is further broken to a particle size of <0.79 μm before the heat treatment under inert atmosphere.
[0010] In a preferred embodiment of the present application, the temperature of the heat treatment is 200℃ and the time is 20 min.
[0011] In a preferred embodiment of the present application, the biomass is corn cob.
[0012] In a preferred embodiment of the present application, the pyrolysis is specifically under argon atmosphere at 300℃.
[0013] In a preferred embodiment of the present application, the temperature of the heat mass exchange is 190-210℃ (preferably 210℃) and the time is 0.5 h (the time of the heat mass exchange refers to the time from the start of the pyrolysis of the biomass to the end of the heat mass exchange of the pyrolysis gas and the dried lignite).
[0014] In a preferred embodiment of the present application, the mass ratio of the biomass to the dried lignite is (5-7) : 1.
[0015] The present application also provides a modified lignite prepared by the method of modifying the dried lignite with the pyrolysis gas of the biomass.
[0016] The present application discloses the following technical effects:
[0017] The biomass is widely available and low in price, and the aromatic hydrocarbon components are macro-generated "useless" products in the modification process of the biomass. The water-resistant organic matters such as benzene, toluene, styrene, phenol and naphthalene are the main pyrolysis products of the biomass tar. In the process of upgrading and modifying the lignite, in view of the problem that the dried lignite is easy to reabsorb water, the present application forms a water-resistant layer or passivates the hydrophilic groups on the surface of the lignite particles by the tar and its pyrolysis products in the tail gas of the biomass, and the aromatic hydrocarbon components can be replaced by the water in the lignite, so that the effect of modifying the dried lignite with high water content is achieved. The present application can simultaneously realize the water removal, the increment of the combustible components, the weakening of the hydrophilicity and the strengthening of the reactivity of the lignite, and by improving the energy density and the combustion reactivity of the dried lignite, the fuel quality of the dried lignite is further improved, and the waste heat of the tail gas of the biomass is recycled. BRIEF DESCRIPTION OF DRAWINGS
[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.
[0019] Figure 1A schematic diagram of the mechanism of the method for modifying and drying lignite using biomass pyrolysis gas according to the present application.
[0020] Figure 2 A fixed bed lignite drying system used in the method for modifying and drying lignite using biomass pyrolysis gas according to the present application. DETAILED DESCRIPTION
[0021] Various exemplary embodiments of the present application will now be described in detail, with reference to the drawings, which are not intended to limit the present application or the scope thereof but to explain the present application in more detail. The detailed description of the present application is made with reference to the accompanying drawings.
[0022] It is to be understood that the terms used in the present application are merely used to describe particular embodiments and are not intended to limit the present application. In addition, for numerical ranges in the present application, it is to be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range within any stated range or within any stated intermediate value, and any other stated value or intermediate value within the stated range is also encompassed within the present application. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.
[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. Any and all
[0024] Many modifications and variations of this application description will be apparent to those of ordinary skill in the art without departing from the scope or spirit of the application. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the application. The specification and examples are illustrative only.
[0025] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended terms that are intended to mean including, but not limited to.
[0026] The present application dries lignite in a physical-chemical combined manner to prevent lignite moisture re-adsorption. Physical adsorption is achieved by plugging the lignite pore diameter with volatile gases generated after biomass roasting, and the volatile gases form tar and are adsorbed on the pore diameter after temperature reduction. Chemical adsorption is achieved by the single-ring aromatic hydrocarbons in the tar combining with the hydrophilic groups on the lignite surface, weakening the hydrophilicity of the lignite surface.
[0027] The present application provides a method for modifying and drying lignite using biomass pyrolysis gas, the steps of which are as follows:
[0028] 1) The raw lignite is crushed into particles with a particle size of <0.79 μm, and 10 g of the lignite (particle size <0.79 μm) is weighed and placed in a fixed bed reactor, and is treated in an argon atmosphere at 200°C for 20 min to prepare dry lignite;
[0029] 2) As shown in Figure 2 , the black ellipse represents lignite, and the yellow ellipse represents biomass. The biomass is pyrolyzed in a fixed bed reactor, and the pyrolysis gas stream is cooled by a water cooling system and then contacts the dry lignite prepared in step 1) at 190-210°C (preferably 210°C) to exchange heat and mass, the mass ratio of the biomass to the dry lignite is controlled to be (5-7):1, the pyrolysis gas stream contacts the surface of the dry lignite particles, the temperature of the surface of the dry lignite particles is lower than the temperature of the pyrolysis gas stream, so that the tar cracking products are gradually condensed on the surface of the dry lignite particles, and finally the modified lignite is prepared. Further, the reaction process of step 2) is as follows: the biomass is pyrolyzed in a fixed bed reactor, and the pyrolysis gas stream is cooled by a water cooling system and then contacts the dry lignite to exchange heat and mass; the pyrolysis gas stream generated when the biomass starts to pyrolyze is cooled by a water cooling system and then contacts the dry lignite to exchange heat and mass; the time from the start of the pyrolysis of the biomass to the end of the heat and mass exchange between the pyrolysis gas and the dry lignite is 0.5 h.
[0030] The technical solutions described in the present application are conventional solutions in the art, and the reagents or raw materials used are commercially available or have been disclosed, unless otherwise specified.
[0031] The lignite used in the embodiments of the present application is from Inner Mongolia Autonomous Region; and the biomass used in the embodiments of the present application is corn cob.
[0032] The fixed bed dry lignite system used in the embodiments of the present application is as shown in Figure 2 , and is composed of a gas distribution system, a reaction device, and a component analysis system; wherein the gas distribution system selects a gas to push the pyrolysis gas according to experimental requirements, the reaction device is used to pyrolyze the biomass, and the pyrolysis gas is used to further dry and exchange heat and mass with the dry lignite, and the component analysis system is used to analyze the composition of the pyrolysis gas.
[0033] The technical solutions provided by the present application will be described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present application.
[0034] Example 1
[0035] The present embodiment provides a method for modifying dry lignite by using biomass pyrolysis gas, and the steps are as follows:
[0036] 1) The raw lignite was crushed into lignite particles with a particle size of <0.79 μm, and the lignite (particle size <0.79 μm) was weighed and placed in a fixed bed reactor, treated under an argon atmosphere at 200°C for 20 min, and dried lignite was prepared. The moisture content of the dried lignite was 19.73 wt%, and the volatile matter content was 36.62 wt%.
[0037] 2) The biomass was pyrolyzed in a fixed bed reactor under an argon atmosphere at a pyrolysis temperature of 300°C, and the pyrolysis gas stream was controlled by a water cooling system to exchange heat and mass with 10 g of dried lignite prepared in step 1) at 210°C for 0.5 h. The mass ratio of biomass to dried lignite was 5, and after the heat and mass exchange was completed, the modified lignite was obtained.
[0038] 3) The reabsorbed water content of the coal sample was measured every 2 h at a relative humidity of 95%, until the weight approached a constant value (the change in mass between two measurements was less than 0.1% of the initial mass), at which point the reabsorbed water content of the coal sample was determined.
[0039] The modified lignite of this example had a maximum internal moisture content of 12.82 wt%, which was 35% lower than that of the dried lignite. The volatile matter content of the modified lignite of this example was 56.03 wt%, which was 53% higher than that of the dried lignite.
[0040] Example 2
[0041] The only difference between this example and Example 1 was that in step 2), the mass ratio of biomass to dried lignite was 6.
[0042] The modified lignite of this example had a maximum internal moisture content of 11.84 wt%, which was 40% lower than that of the dried lignite. The volatile matter content of the modified lignite of this example was 57.49 wt%, which was 57% higher than that of the dried lignite.
[0043] Example 3
[0044] The only difference between this example and Example 1 was that in step 2), the mass ratio of biomass to dried lignite was 7.
[0045] The modified lignite of this example had a maximum internal moisture content of 12.23 wt%, which was 38% lower than that of the dried lignite. The volatile matter content of the modified lignite of this example was 57.86 wt%, which was 58% higher than that of the dried lignite.
[0046] Example 4
[0047] The only difference between this example and Example 1 was that in step 2), the heat and mass exchange temperature was 190°C.
[0048] The modified lignite in the example has the highest internal moisture content of 14.60wt%, which is reduced by 26% compared with the dry lignite; the modified lignite in the example has the volatile content of 51.27wt%, which is increased by 40% compared with the dry lignite.
[0049] Example 5
[0050] The difference between the example and example 4 is that in step 2), the mass ratio of biomass to dry lignite is 6.
[0051] The modified lignite in the example has the highest internal moisture content of 14.20wt%, which is reduced by 28% compared with the dry lignite; the modified lignite in the example has the volatile content of 52.00wt%, which is increased by 42% compared with the dry lignite.
[0052] Example 6
[0053] The difference between the example and example 4 is that in step 2), the mass ratio of biomass to dry lignite is 7.
[0054] The modified lignite in the example has the highest internal moisture content of 14.40wt%, which is reduced by 27% compared with the dry lignite; the modified lignite in the example has the volatile content of 52.37wt%, which is increased by 43% compared with the dry lignite.
[0055] Compared with the conventional dry lignite method (i.e. the method for preparing dry lignite in step 1 of example 1), the aromatics in the biomass pyrolysis gas can be adsorbed to form a coating to reduce the direct contact area of the lignite particles with the water molecules, induce the combination of the single-ring aromatics with the hydrophilic groups to passivate the hydrophilicity of the dry lignite, the increase of the volatile content of the dry lignite indicates the adsorption of the active aromatic components in the lignite, and the combustion reactivity of the modified lignite is enhanced.
[0056] Comparative Example 1
[0057] The difference between the example and example 2 is that in step 2), the biomass is pine.
[0058] The modified lignite in the example has the highest internal moisture content of 13.61wt%, which is reduced by 31% compared with the dry lignite; the modified lignite in the example has the volatile content of 53.47wt%, which is increased by 46% compared with the dry lignite.
[0059] The above-described examples only describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.
Claims
1. A method for modifying drying of lignite with biomass pyrolysis gas, characterized by, The method comprises the following steps: heat treating lignite under inert atmosphere to obtain dried lignite; pyrolyzing biomass, and performing heat mass exchange between the obtained pyrolysis gas and the dried lignite to obtain modified lignite.
2. The method for drying lignite with biomass pyrolysis gas according to claim 1, characterized in that, The method further comprises the step of crushing the lignite to a particle size of less than 0.79 μm before the heat treatment of the lignite under inert atmosphere.
3. The method for drying lignite with biomass pyrolysis gas according to claim 1, characterized in that, The temperature of the heat treatment is 200 ℃, and the time is 20 min.
4. The method for drying lignite with biomass pyrolysis gas according to claim 1, characterized in that, The biomass is corn cob.
5. The method for drying lignite with biomass pyrolysis gas according to claim 1, characterized in that, The pyrolysis is specifically performed under argon atmosphere at 300 ℃.
6. The method for drying lignite with biomass pyrolysis gas according to claim 1, characterized in that, The temperature of the heat mass exchange is 190-210 ℃, and the time is 0.5 h.
7. The method for drying lignite with biomass pyrolysis gas according to claim 1, characterized in that, The mass ratio of the biomass to the dried lignite is (5-7) :
1.
8. Modified lignite prepared by the method of modifying dried lignite with biomass pyrolysis gas according to any one of claims 1-7.