Coal gasification fine slag-charcoal porous composite fuel as well as preparation method and application thereof

Abstract

The invention provides a coal gasification fine slag-biochar porous composite fuel and a preparation method and application thereof, and belongs to the technical field of composite fuels, the porous composite fuel uses biochar prepared from industrial by-product coal gasification fine slag and agricultural waste as a base material, and a foaming agent composed of a foaming agent A and a foaming agent B is matched to prepare the porous composite fuel. Forming a porous structure through a foaming process; the base material raw material is a core framework of the porous composite fuel, the foaming agent is used for constructing a porous form of the porous composite fuel, and the base material raw material and the foaming agent have a synergistic effect, so that the porous composite fuel meets the raw material requirement of a liquid oxygen fracturing scene. The problems that in the prior art, the liquid oxygen adsorption amount is low, the ignition point temperature is high, combustion is incomplete and the blasting power is insufficient are solved, recycling of the coal gasification fine slag and agricultural waste is achieved, only CO2 and H2O are produced through thermal decomposition of the prepared porous composite fuel, and toxic emission is avoided; and the requirements of green blasting and rock crushing in the field of liquid oxygen fracturing can be efficiently met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite fuel, in particular to a coal gasification fine slag-biochar porous composite fuel and a preparation method and application thereof. BACKGROUND

[0002] Currently, blasting technology is widely used in rock breaking, building demolition and other engineering fields. With the improvement of environmental protection and safety requirements, low-dust, low-noise and low-environmental impact liquid oxygen fracturing technology has become an important alternative to traditional blasting. The core of the technology relies on fuel adsorbing liquid oxygen to release energy. In the existing liquid oxygen fracturing system, wood pulp paper is the mainstream adsorbing fuel. At the same time, a large amount of coal gasification fine slag (as a byproduct of coal gasification process, with high residual carbon content but low utilization rate, mostly stored or discarded) is generated in the industrial field every year, and a large amount of corn cob and other biomass waste (traditional treatment methods can easily cause resource waste and environmental burden) is generated in the agricultural field. The resource utilization of the two types of solid waste has become the focus of the industry.

[0003] The industry development trend presents two directions: on the one hand, the liquid oxygen fracturing technology is continuously deepened in terms of reaction mechanism, fuel performance optimization and other aspects due to its environmental friendliness, and the application scenarios of non-explosive green breaking technology are continuously expanded; on the other hand, the high-value recycling of industrial and agricultural solid waste has become the mainstream, such as the preparation of biochar from biomass through carbonization for adsorption, combustion and other fields, and the resource regeneration of coal gasification fine slag through residual carbon recovery and porous material preparation, but the existing researches mainly focus on the independent utilization of single solid waste, and the two types of solid waste have not been combined for the development of liquid oxygen fracturing fuel.

[0004] However, the existing technology still has the following defects that cannot be ignored: first, the performance of traditional wood pulp paper fuel has obvious limitations, the liquid oxygen adsorption capacity per unit volume is only 0.304 g·cm -3 , the ignition temperature is as high as 264.8℃, the heating rate is only 3.54℃·ms -1 , and the fuel is prone to leaving residues after combustion and has insufficient blasting power, which cannot meet the demand of liquid oxygen fracturing for high efficient energy release; second, the resource utilization of coal gasification fine slag and corn cob biomass lacks synergy, and the utilization path of the two types of solid waste is single, and an integrated scheme of solid waste synergistic preparation of fuel adapting to liquid oxygen fracturing has not been formed; third, the existing porous fuel preparation process is not designed for the liquid oxygen fracturing scene, and there is a lack of technical scheme for constructing high liquid oxygen adsorption capacity and adaptive porous structure based on coal gasification fine slag and biochar as base material through foaming process.

[0005] Therefore, there is an urgent need for a porous composite fuel prepared by foaming process based on coal gasification fine slag and corn cob biochar as base material. SUMMARY

[0006] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a coal gasification fine slag-biochar porous composite fuel and a preparation method and application, which not only solves the problems of low liquid oxygen adsorption, high ignition point temperature, incomplete combustion and insufficient blasting power in the prior art, but also realizes the recycling of coal gasification fine slag and agricultural waste, and the prepared porous composite fuel only produces CO2 and H2O without toxic emissions during thermal decomposition, which can efficiently meet the needs of green blasting and rock breaking in the field of liquid oxygen induced cracking.

[0007] In order to achieve the above-mentioned purpose, the present application provides the following solutions: One of the purposes of the present application is to provide a coal gasification fine slag-biochar porous composite fuel, which is prepared by taking industrial by-product coal gasification fine slag and biochar prepared from agricultural waste as base material, and adding foaming agent composed of foaming agent A and foaming agent B, and then forming a porous structure through foaming process; the base material is the core skeleton of the porous composite fuel, the foaming agent is used to construct the porous morphology of the porous composite fuel, and the base material and the foaming agent synergistically act to make the porous composite fuel meet the raw material requirements of the liquid oxygen induced cracking scene.

[0008] Preferably, the biochar is prepared by hydrothermal carbonization treatment of biomass in agricultural waste after grinding and sieving, and the biomass includes corn cobs.

[0009] Preferably, the main component of the foaming agent A is isocyanate; the foaming agent B is a mixture of polyether polyol, amine catalyst, cyclopentane and silicone oil, and the mass ratio of the foaming agent A to the foaming agent B is 1:1.

[0010] Preferably, in the base material, the mass ratio of the biochar to the coal gasification fine slag is 1:9~9:1.

[0011] Preferably, the mass ratio of the biochar to the coal gasification fine slag is 7:3.

[0012] The second purpose of the present application is to provide a preparation method of the above-mentioned coal gasification fine slag-biochar porous composite fuel, which comprises the following steps: S1, corn cobs are ground and sieved, and then subjected to hydrothermal carbonization treatment to obtain biochar, then coal gasification fine slag is ground and sieved, and then dried for standby, and foaming agent A and foaming agent B are respectively subjected to constant temperature and static treatment; S2, biochar and coal gasification fine slag are weighed according to a predetermined mass ratio, and then put into a stirring device for stirring until uniform to obtain a composite base material; S3, foaming agent A and foaming agent B are added to the composite base material according to a predetermined mass ratio, and then stirred until the system is exothermic and expanded, and then the mixture is poured into a mold for static foaming; S4, the foamed material in the mold is trimmed to remove the irregular parts on the surface, and then demolded to obtain the porous composite fuel.

[0013] Preferably, in S1, the corncob and the coal gasification fine slag are both ground through a 200-mesh sieve; the constant-temperature standing environment temperature of the foaming agent A and the foaming agent B is 20-30 DEG C, and the standing time is 20-40 min; the drying temperature of the coal gasification fine slag is 100-110 DEG C, and the drying time is 1.5-2.5 h.

[0014] Preferably, in S2, the rotating speed of the stirring device is 200-400 r / min, and the stirring time is 10-20 min.

[0015] Preferably, in S3, the rotating speed of the stirring is 400-600 r / min, the stirring time is 2-4 min, and the standing foaming time is 8-12 min.

[0016] The third object of the present application is to provide an application of the coal gasification fine slag-biochar porous composite fuel.

[0017] According to the specific embodiments of the present application, the following technical effects are disclosed: (1) The application can greatly optimize the application performance of liquid oxygen fracturing fuel. Compared with the traditional liquid oxygen fracturing fuel of wood pulp paper, the coal gasification fine slag-biochar porous composite fuel (optimal ratio 7:3) used in the present application has high unit volume liquid oxygen adsorption capacity, low ignition temperature, fast heating rate, strong blasting power, and better liquid oxygen retention capacity and combustion completeness. This fundamentally solves the problem of the unit volume liquid oxygen adsorption capacity of wood pulp paper being only 0.304 g·cm -3 due to the compact structure and limited adsorption capacity, avoids the defects of the traditional fuel ignition temperature being as high as 264.8 DEG C and the heating rate being only 3.54 DEG C·ms -1 , and can realize efficient energy release and stable blasting operation in the liquid oxygen fracturing scene.

[0018] (2) The application can also realize high-value utilization of industrial and agricultural solid wastes. Compared with the traditional methods of storing and discarding coal gasification fine slag and inefficiently treating agricultural wastes such as corncob, the present application uses the biochar prepared from the industrial by-product coal gasification fine slag and the agricultural waste corncob as the base material, and forms a porous composite fuel by foaming process with specific foaming agents. This feature completely solves the problem of single resource utilization path and unexplored comprehensive value of the two types of solid wastes, avoids the environmental burden and resource waste caused by solid waste storage, and can convert low-value waste into high-value fuel suitable for liquid oxygen fracturing, which is consistent with the current development direction and forms a resource recycling system.

[0019] (3) This invention further ensures the environmental safety of the liquid oxygen blasting process. Compared with the risks of residual residue and potential toxic gas emissions from traditional fuel combustion, the porous composite fuel prepared by this invention has been verified by TG-DSC and TG-FTIR analysis to have the characteristics of complete combustion and clean thermal decomposition products. This process fundamentally solves the problem of residue left after the combustion of wood pulp and paper, avoids the hidden dangers of toxic gases such as H2S and volatile organic compounds generated during thermal decomposition, and only releases CO2 and H2O, which can meet the application requirements of green blasting and low environmental impact in the field of liquid oxygen blasting. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the 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.

[0021] Figure 1 A physical image of the porous composite fuel of coal gasification fine slag-biochar provided in an embodiment of the present invention; Figure 2 This is a fitting diagram of the liquid oxygen desorption curve of the porous composite fuel of coal gasification fine slag-biochar and virgin wood pulp paper provided in an embodiment of the present invention; wherein, Figure 2 (a) in the figure is the fitting result of the composite fuel with a biochar content of 70%; Figure 2 (b) in the figure is the fitting result of the virgin pulp paper; Figure 3 These are scanning electron microscope (SEM) images of porous composite fuel consisting of log pulp paper and coal gasification fine slag-biochar, provided in an embodiment of the present invention; wherein, Figure 3 Image (a) in the image is a SEM image of virgin wood pulp paper. Figure 3 (b) is a SEM image of porous composite fuel consisting of coal gasification fine slag and biochar. Figure 4 The ignition energy-power-time curve of coal gasification fine slag-biochar porous composite fuel and virgin wood pulp paper provided in the embodiments of the present invention; Figure 4 (a) in the figure is the ignition energy-power-time curve of the composite fuel with a biochar content of 70%. Figure 4 (b) in the figure is the ignition energy-power-time curve of virgin wood pulp paper; Figure 5 Infrared thermography images of porous composite fuel made from coal gasification fine slag-biochar and wood pulp paper at the moment of ignition, provided in embodiments of the present invention; wherein, Figure 5 Image (a) is an infrared thermogram taken at the moment of ignition of the raw wood pulp paper. Figure 5(b) is an infrared thermogram of the moment of ignition of the porous composite fuel of coal gasification fine slag-biochar; Figure 6 This is a real-time temperature change curve of combustion of coal gasification fine slag-biochar porous composite fuel and virgin wood pulp paper provided in an embodiment of the present invention; wherein, Figure 6 (a) in the figure is a curve showing the real-time temperature change during combustion of porous composite fuel consisting of coal gasification fine slag and biochar. Figure 6 (b) in the figure is a curve showing the real-time temperature change during the combustion of virgin wood pulp paper; Figure 7 Thermogravimetric-differential scanning calorimetry (TG-DSC) curve of porous composite fuel of coal gasification fine slag-biochar provided in the embodiments of the present invention; Figure 8 Three-dimensional Fourier transform infrared (FTIR) spectrum of the thermal decomposition process of coal gasification fine slag-biochar porous composite fuel provided in the embodiments of the present invention; Figure 9 The flowchart illustrates the principle of the preparation method of porous composite fuel of coal gasification fine slag-biochar provided in this embodiment of the invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Example This invention provides a porous composite fuel of coal gasification fine slag and biochar. The porous composite fuel uses coal gasification fine slag, an industrial by-product, and biochar prepared from agricultural waste as base materials, combined with a foaming agent composed of foaming agent A and foaming agent B, to form a porous structure through a foaming process. The base materials form the core framework of the porous composite fuel, and the foaming agent is used to construct the porous morphology of the porous composite fuel. The base materials and the foaming agent work synergistically to make the porous composite fuel suitable for the raw material requirements of liquid oxygen-induced cracking scenarios.

[0025] In this embodiment, the biochar is prepared by hydrothermal carbonization of biomass from agricultural waste through grinding and sieving, and the biomass includes corn cobs. The main component of the foaming agent A is isocyanate; the foaming agent B is a mixture of polyether polyol, amine catalyst, cyclopentane, and silicone oil, and the mass ratio of foaming agent A to foaming agent B is 1:1. In the base material, the mass ratio of biochar to coal gasification slag is 1:9 to 9:1. Specifically, the mass ratio of biochar to coal gasification slag is 7:3.

[0026] In addition, such as Figure 9 As shown, the present invention also provides a method for preparing the above-mentioned porous composite fuel of coal gasification fine slag-biochar, comprising the following steps: S1. After grinding and sieving the corn cobs, biochar is obtained by hydrothermal carbonization. Then, the fine coal gasification residue is ground, sieved, and dried for later use. Foaming agent A and foaming agent B are respectively subjected to constant temperature static treatment.

[0027] In the above steps, both the corn cob and the coal gasification slag are ground through a 200-mesh sieve; the constant temperature environment for foaming agent A and foaming agent B is 20~30℃, and the settling time is 20~40min; the drying temperature for the coal gasification slag is 100~110℃, and the drying time is 1.5~2.5h.

[0028] S2. Weigh out biochar and coal gasification slag according to the preset mass ratio, put them into a mixing device and stir until uniform to obtain composite substrate.

[0029] In the above steps, the stirring equipment rotates at a speed of 200~400 r / min and the stirring time is 10~20 min.

[0030] S3. Add foaming agent A and foaming agent B to the composite substrate according to a preset mass ratio, and then stir until the system expands due to heat. Pour the mixture into a mold and let it stand to foam.

[0031] In the above steps, the stirring speed is 400~600 r / min, the stirring time is 2~4 min, and the standing foaming time is 8~12 min.

[0032] S4. Trim the foamed material in the mold, remove the irregular parts on its surface, and demold to obtain the porous composite fuel.

[0033] Among them, such as Figure 1 As shown, the porous composite fuel has densely and uniformly distributed pores in its internal structure. Subsequently, the prepared porous composite fuel was subjected to thermogravimetric-differential scanning calorimetry (TG-DSC), thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR), and scanning electron microscopy (SEM) analyses. The data results of the liquid oxygen adsorption experiment are shown in Table 1.

[0034] Table 1 Comparison of experimental parameters for liquid oxygen adsorption ;

[0035] Table 1 shows that the sample with 70% biochar content had an adsorption capacity of 4.420 g / g; the liquid oxygen adsorption capacity of the virgin wood pulp paper was 5.2 g / g. In terms of adsorption capacity per unit volume, the sample with 70% biochar content reached 0.531 g / cm³. 3 The liquid oxygen adsorption capacity per unit volume of virgin wood pulp paper is 0.304 g / cm³. 3 This is lower than the aforementioned composite fuel with a biochar content of 70%.

[0036] Based on the liquid oxygen desorption data provided in Table 1 above and the existing HS fractional desorption model, the kinetic parameters of the liquid oxygen desorption model were obtained by fitting ordinary differential equations, and the calculation results are shown in Table 2.

[0037] Table 2 Kinetic parameters of the liquid oxygen desorption model ;

[0038] Table 2 shows that the desorption rate constant of the composite fuel with 70% biochar content is lower, at 1.568 × 10⁻⁶. -9 The desorption rate constant of the virgin wood pulp paper is 2.780 × 10⁻⁶. -9 Furthermore, the results shown in Table 2 above indicate that the composite fuel with a biochar content of 70% has a stronger ability to retain liquid oxygen.

[0039] Reference Figure 2 , Figure 2 (a) in the figure shows the fitting results for the composite fuel with a biochar content of 70%. Figure 2 Figure (b) shows the fitting results for the virgin pulp paper. Comparison reveals that the entire desorption cycle for the virgin pulp paper is 4300 s. The desorption efficiency initially accelerates and then gradually decreases over time: In the initial stage (0~1517 s), the desorption rate linearly increases from 0.01646 to a peak of 0.03099, accounting for 37% of the total liquid oxygen desorption; subsequently, it enters a brief stable stage (1517~1534 s), during which only 1% of the liquid oxygen is desorbed at the maximum desorption rate; after 1534 s, the desorption rate begins to decrease significantly, and this downward trend continues until the end of the experiment (4300 s). It is noteworthy that in the initial stage of the decrease, the desorption rate remains relatively high, with 82% of the liquid oxygen desorbed by 3300 s; however, due to the continuous decrease in rate, the remaining 18% of the liquid oxygen requires approximately 1000 s to complete desorption, finally achieving complete desorption at 4300 s.

[0040] The porous composite fuel of coal gasification fine slag-biochar with 70% biochar content exhibits typical three-stage kinetic characteristics: the desorption rate rises rapidly in the initial stage (approximately linear), then enters a brief stable stage (the rate is basically constant), and finally the desorption rate gradually decreases until desorption is completed.

[0041] In this embodiment, scanning electron microscopy (SEM) was also used to characterize the microstructure of the liquid oxygen adsorbent, and the results are as follows: Figure 3 As shown. By Figure 3 As shown in (a), virgin wood pulp paper exhibits a hierarchical porous structure with high pore density and overall large porosity, but relatively small pore size; for example... Figure 3 As shown in (b) of this embodiment, the porous composite fuel exhibits a significantly more open porous structure with pore sizes considerably larger than those of virgin wood pulp paper. This allows the composite fuel to adsorb more liquid oxygen within the same volume and promotes faster liquid oxygen penetration; furthermore, the larger pore size is beneficial for enhancing oxygen diffusion and flame propagation, thereby achieving stable combustion.

[0042] Furthermore, based on the above, the composite fuel with 70% biochar content has the lowest desorption rate constant, indicating its strongest ability to retain liquid oxygen. Therefore, this composite fuel was selected for comparison with virgin wood pulp paper to further evaluate the performance differences between the two. This embodiment also uses a controllable ignition triggering system combined with infrared thermal imaging technology to study the ignition characteristics of the two materials, focusing on analyzing ignition temperature, ignition delay time, ignition energy-power-time curve, and infrared thermal imaging characteristics.

[0043] Among them, reference Figure 4 As shown in (a) and (b), the porous composite fuel of coal gasification fine slag-biochar with a biochar content of 70% exhibits a higher peak ignition power, more concentrated and faster energy release, and a smaller half-width at half maximum (WHM) of its power-time curve (only 1.57724 s), indicating a rapid ignition response. In contrast, the peak ignition power of the virgin wood pulp paper is lower, and the energy release duration is longer (WHM is 3.43313 s). This demonstrates that the porous composite fuel of the present invention has superior ignition performance, is easier to ignite, and has more efficient energy release.

[0044] like Figure 5 As shown in (a) and (b), the ignition point of the virgin wood pulp paper is 264.8℃, while the maximum instantaneous ignition temperature of the porous composite fuel of coal gasification fine slag-biochar reaches 207.6℃, which is closer to the ignition point. Therefore, it is easier to ignite, has better ignition performance, and is conducive to the subsequent combustion reaction.

[0045] Through the Figure 4The ignition energy of the composite fuel and the virgin wood pulp paper was obtained by integrating the area under the ignition energy-power-time curve. The ignition energy of the composite fuel was approximately 362.06 J / g, while that of the virgin wood pulp paper was approximately 593.53 J / g. This indicates that the composite fuel is easier to ignite and has a faster ignition response. This phenomenon is closely related to the porous structure of the composite fuel—it has more pores and larger pore sizes, which facilitates the transfer of oxygen and heat during combustion.

[0046] In this embodiment, an ignition test system was also used to systematically study the combustion characteristics of virgin pulp paper and composite fuel. The experimental data (as shown in Table 3) showed significant differences in their combustion performance: in terms of ignition temperature, virgin pulp paper had a higher ignition temperature (264.8℃), while the composite fuel had an ignition temperature of only 207.6℃. This is because virgin pulp paper has a high cellulose content and a dense structure, resulting in a higher pyrolysis activation energy and requiring more energy to ignite; conversely, the composite fuel has a highly porous three-dimensional network structure, which improves oxygen diffusion and heat conduction, allowing it to reach ignition conditions at a lower temperature of 207.6℃, thus exhibiting superior ignition performance.

[0047] Ignition experiments further showed that the composite fuel achieved a combustion efficiency of 100% after ignition, indicating that its carbon structure was completely oxidized at high temperatures; while the wood pulp paper left residue after combustion, which may be due to the presence of silicate additives in the fiber bundles. These additives form a molten silicon layer during combustion, which hinders oxygen penetration and leads to incomplete oxidation.

[0048] The ignition delay time test results showed that the virgin wood pulp paper had the longest delay time (1.522s), mainly due to its high specific heat capacity and low thermal conductivity, resulting in a significantly slower heat accumulation process; while the composite fuel had a shorter delay time (0.760s), which is consistent with its high specific surface area and porous structure, which is conducive to the rapid release of volatile components.

[0049] In terms of combustion performance, composite fuels show significant advantages in advanced materials applications, including lower ignition temperature, higher combustion efficiency, and shorter ignition delay time.

[0050] Table 3 Comparison of Combustion Experiment Parameters

[0051] in addition, Figure 6 The real-time temperature curves of the composite fuel and the virgin wood pulp paper were compared, and their combustion behaviors differed significantly. Table 1 shows that the same volume of composite fuel and virgin wood pulp paper adsorbed approximately 1.063 g and 0.557 g of liquid oxygen, respectively. Figure 6As shown in (a), the temperature of the composite fuel rises rapidly after fully adsorbing liquid oxygen, reaching a peak of 953°C within approximately 0.127 s, with a total temperature rise of 928°C, indicating its high reactivity. This phenomenon is attributed to the unique porous three-dimensional structure of the composite fuel, which promotes rapid thermal decomposition and oxidation reactions, enabling it to achieve a high temperature rise rate in a short time.

[0052] On the contrary, such as Figure 6 As shown in (b), the virgin wood pulp paper reached its peak temperature of 821.6℃ at approximately 0.255s, with a total temperature rise of 796.6℃, indicating that its pyrolysis and combustion processes were slower. This is mainly because virgin wood pulp paper has a high cellulose content and a dense fiber structure, resulting in a higher thermal decomposition activation energy, requiring more energy input to initiate combustion.

[0053] In this embodiment, a heating rate test was also conducted. The temperature change curve during the ignition process was monitored in real time using an infrared thermometer. The thermal behavior of the composite fuel and the wood pulp paper was compared and analyzed to provide a quantitative basis for evaluating the ignition performance and thermal reactivity of the two materials in a liquid oxygen environment. The results are shown in Table 4.

[0054] Table 4 Data on the combustion of adsorbent in liquid oxygen

[0055] Table 4 quantitatively compares the heating rates: the heating rate of the composite fuel is 7.3℃ / ms, almost twice that of virgin wood pulp paper (3.54℃ / ms). This further indicates that, in the presence of liquid oxygen, the composite fuel, due to its structural characteristics and the strong oxidizing properties of liquid oxygen, can achieve a faster heating rate; while virgin wood pulp paper has a lower heating rate under the same conditions and leaves residue after combustion, indicating incomplete combustion.

[0056] Based on the above, this embodiment also performed thermogravimetric-differential scanning calorimetry (TG-DSC) analysis on the porous composite fuel of coal gasification fine slag-biochar, and the results are as follows. Figure 7 As shown in the figure, the TG curve reveals that the porous composite fuel experiences concentrated mass loss within a certain temperature range, corresponding to its thermal decomposition and combustion processes, indicating relatively sufficient mass loss. The DSC curve shows that this process is accompanied by significant exothermic behavior, demonstrating the fuel's good heat release capacity. Furthermore, to further investigate the thermal decomposition products, Fourier transform infrared spectroscopy (FTIR) was conducted, with results shown in the figure. Figure 8 :from Figure 8The FTIR three-dimensional spectra of the thermal decomposition process can intuitively show the changes in functional group response at different stages of thermal decomposition. In the initial stage of thermal decomposition (0~2 min), the absorbance across the entire wavenumber range is close to the baseline, with no obvious characteristic peaks appearing, corresponding to the low-temperature evaporation process of adsorbed water on the fuel surface. There is no substantial decomposition of organic components in this stage. In the middle stage of thermal decomposition (2~8 min), the absorbance at 2200~2300 cm⁻¹... -1 (CO2 characteristic wavenumber range) and 3400~3800cm -1 A significant absorbance peak appeared in the characteristic wavenumber range of the -OH functional group of H2O, and the peak value first increased rapidly over time (reaching its maximum value at 4 min) and then slowly decreased, indicating that this stage is the main decomposition period of the fuel, during which a large amount of CO2 and H2O generated by the reaction of carbonaceous components with oxygen are released, and the product concentration changes dynamically with the reaction process. In the later stage of thermal decomposition (after 8 min), the absorbance in the above characteristic wavenumber range gradually returned to the baseline level, and no new characteristic peaks were generated, proving that the fuel thermal decomposition reaction was complete and no residual components were released. At the same time, the absorbance of this spectrum was within the entire wavenumber range (400~4000 cm⁻¹). -1 H2S was not observed (characteristic wavenumber 2500~2600cm). -1 ), volatile organic compounds (VOCs, characteristic wavenumbers 1000~1800 cm⁻¹) -1 NO x (Characteristic wavenumber 1300~1400cm) -1 The absorbance signals of toxic and harmful gases such as CO2 and H2O, combined with the characteristic that the Z-axis absorbance only responds in the wavenumber range corresponding to CO2 and H2O, further corroborate that the composite fuel pyrolysis products provided in this embodiment are only CO2 and H2O, with no toxic gas emissions.

[0057] In addition, this embodiment mainly focuses on testing and analyzing the practical application performance of the porous composite fuel of coal gasification fine slag-biochar in liquid oxygen fracturing. Using traditional log pulp paper as a control, under a simulated liquid oxygen fracturing scenario (sand layer burial depth 30cm, sand particle size 2~5mm), an experimental procedure was adopted: customized stainless steel cartridge loading – liquid oxygen adsorption for 10 minutes to saturate – KL-500 Igniter ignition. The focus was on testing the explosive power and combustion residue of the fuel. The experimental results show that the explosive funnel volume of the composite fuel of this invention (biochar to coal gasification fine slag mass ratio 7:3) reaches 0.03m³. 3 Compared to virgin wood pulp paper (0.02m), 3The composite fuel exhibits a 50% increase in blasting performance and a blasting effect index of 1.24 (compared to 1.12 for virgin wood pulp paper), classifying it as an enhanced throwing blasting type with more complete energy release. Furthermore, post-blast residue analysis revealed that the composite fuel combustion residue accounted for less than 1% (compared to 8% for virgin wood pulp paper), and the residue was a biodegradable grayish-white powder without any toxic or harmful components, demonstrating its complete combustion and environmental friendliness. Ultimately, this verifies that the composite fuel outperforms traditional fuels in both blasting performance and environmental friendliness in the liquid oxygen fracturing field, meeting the practical application requirements for green blasting and rock breaking.

[0058] In summary, the composite fuel of this invention, with an optimal mass ratio of biochar to coal gasification slag of 7:3, exhibits excellent liquid oxygen adsorption performance (adsorption capacity per unit volume of 0.531 g·cm³). -3 (75% improvement over virgin wood pulp paper), ignition performance (ignition temperature 207.6℃, 21.6% lower than virgin wood pulp paper), and combustion performance (heating rate 7.3℃·ms). -1 Compared to virgin wood pulp paper, 3.54℃·ms -1 (Improved by approximately 106%) and blasting performance (blasting funnel volume 0.03m³). 3 It is significantly superior to traditional liquid oxygen-induced cracking fuel in terms of efficiency (50% higher than that of virgin wood pulp paper); and the thermal decomposition products are only CO2 and H2O, with combustion residue accounting for less than 1%, which combines environmental friendliness and complete combustion; at the same time, the fuel uses industrial by-product coal gasification slag and agricultural waste corn cobs as raw materials to achieve high-value synergistic utilization of industrial and agricultural solid waste.

[0059] Therefore, the above-mentioned porous composite fuel of coal gasification fine slag-biochar, its preparation method and application not only solves the problems of low liquid oxygen adsorption, high ignition temperature, incomplete combustion and insufficient blasting power of existing technologies, but also realizes the recycling and reuse of coal gasification fine slag and agricultural waste. The prepared porous composite fuel produces only CO2 and H2O through thermal decomposition with no toxic emissions, and can be efficiently adapted to the green blasting and rock breaking needs in the field of liquid oxygen fracturing.

[0060] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A porous coal gasification fine slag-biochar composite fuel, characterized in that, The porous composite fuel is prepared by taking biochar prepared from coal gasification fine slag and agricultural waste as a substrate raw material, and by taking a foaming agent composed of foaming agent A and foaming agent B as a foaming agent, and by forming a porous structure through a foaming process; the substrate raw material is the core skeleton of the porous composite fuel, the foaming agent is used to construct the porous morphology of the porous composite fuel, and the substrate raw material and the foaming agent synergistically act to make the porous composite fuel adapt to the raw material requirements of the liquid oxygen fracturing scene.

2. The porous composite fuel of fine coal gasification slag-biochar according to claim 1, characterized in that, The biochar is prepared by hydrothermal carbonization treatment of biomass in agricultural waste after grinding and sieving, and the biomass includes corn cobs.

3. The porous composite fuel of fine coal gasification slag and biochar according to claim 1, characterized in that, The main component of the foaming agent A is isocyanate; the foaming agent B is a mixture of polyether polyol, amine catalyst, cyclopentane and silicone oil, and the mass ratio of the foaming agent A to the foaming agent B is 1:

1.

4. The porous composite fuel of fine coal gasification slag and biochar according to claim 1, characterized in that, In the substrate raw material, the mass ratio of the biochar to the coal gasification fine slag is 1:9 to 9:

1.

5. The porous composite fuel of fine coal gasification slag-biochar according to claim 4, characterized in that, The mass ratio of the biochar to the coal gasification fine slag is 7:

3.

6. A method for preparing the porous coal gasification fine slag-biochar composite fuel according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: S1, obtaining biochar by hydrothermal carbonization treatment of corn cobs after grinding and sieving, then grinding and sieving coal gasification fine slag for drying, and treating foaming agent A and foaming agent B at constant temperature respectively; S2, taking biochar and coal gasification fine slag according to a preset mass ratio, stirring in a stirring device until uniform to obtain a composite substrate; S3, adding foaming agent A and foaming agent B to the composite substrate according to a preset mass ratio, then stirring until the system expands by heat, and then pouring the mixture into a mold for foaming; S4, trimming the foamed material in the mold to remove irregular parts on the surface, and demolding to obtain the porous composite fuel.

7. The method for preparing a porous composite fuel of coal gasification fine slag-biochar according to claim 6, characterized in that, In S1, the corn cobs and the coal gasification fine slag are both ground through a 200-mesh sieve; the constant-temperature standing environment temperature of the foaming agent A and the foaming agent B is 20-30°C, and the standing time is 20-40 min; the drying temperature of the coal gasification fine slag is 100-110°C, and the drying time is 1.5-2.5 h.

8. The method for preparing a porous composite fuel of coal gasification fine slag-biochar according to claim 6, characterized in that, In S2, the stirring speed of the stirring device is 200-400 r / min, and the stirring time is 10-20 min.

9. The method for preparing a porous composite fuel of coal gasification fine slag-biochar according to claim 6, characterized in that, In S3, the stirring speed is 400-600 r / min, the stirring time is 2-4 min, and the foaming time is 8-12 min.

10. Use of the porous coal gasification fine slag-biochar composite fuel according to any one of claims 1 to 5, characterized in that, The porous composite fuel is applied to the field of liquid oxygen fracturing.

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