In the underground coal gasification(UCG)process,different operating parameters and coal properties can cause the UCG system to exhibit different gasification processes,and the calorific value of the product gas will also show a decreasing trend after a certain time of stable output.Two coaxial coal underground gasification models are constructed in an artificial coal seam to study the effects of coaxial gasification channels on the gas composition and calorific value of the generated gasification products,and the effects of pressure,gasifier flow rate,and gas components on the calorific value are comparatively analyzed.The Informer calorific value prediction model is proposed,using ERMS,EMA and R2 as evaluation indexes,and the results are compared with four machine learning models(LSTM,MLP,RNN,and ARIMA)to comparatively analyze the actual and predicted values and errors of the calorific value of the product gas under different prediction time lengths.The results show that different coaxial gasification channels can affect the gasification effect,and changing the extended length of gasification channels can change the proportion of combustible gas components in the product gas.In coaxial model 1,the volume fraction of effective gas components(CO,H2 and CH4)in the product gas was 33.45％,and the average calorific value was 4.68 MJ/Nm3;in coaxial model 2,the volume fraction of effective gas com-ponents in the product gas was 35.09％,and the average calorific value was 4.75 MJ/Nm3.Compared with the coaxial model 1,the volume fraction of H2 in the coaxial model 2 increased from 6.17％to 8.10％,while the volume fraction of CH4 decreases from 1.19％to 0.61％.Adjusting the gasifier flow rate changes the gasifier equilibrium,which transiently increases changes the calorific value of the product gas.Compared with other reference models,the EMA decreased by 22.42％-42.78％,and the ERMS decreased by 15.38％-30.49％.The Informer calorific value prediction model performed outstandingly with high prediction accuracy.The model has high prediction accuracy across different datasets,prediction lengths,and sampling frequencies.The average error for the coaxial model 1 dataset is in the range of 8％-18％,and the average error for the coaxial model 2 dataset is in the range of 5％-12％.The Informer model is able to effectively predict the different trends of thermal value changes when predicting thermal value curves in different time periods,and it can also predict the performance of the system after parameter adjustment.

Rigid polyurethane foam (RPUF) is widely used in insulation but remains highly flammable and smoke-producing. Existing flame-retardant systems often require high additive loadings or rely on environmentally problematic components, which limit their practical applicability. A bio-based composite coating of chitosan and graphitic carbon nitride (CS/g-C3N4) was designed to enhance the fire safety of RPUF through a simple surface modification strategy. The coated RPUF exhibited enhanced flame retardancy and smoke suppression, with the limiting oxygen index increasing from 19.4% to 26.3%. Cone calorimetry revealed reduced heat release and smoke production, including a 26.8% decrease in total smoke release and a 23.9% reduction in peak smoke production rate. Residual char analysis and TG-IR results demonstrated a combined gas-phase and condensed-phase flame-retardant mechanism, involving nonflammable gas release and the formation of a compact char layer. This study presents an efficient and environmentally friendly coating strategy to mitigate fire hazards in polymer foams.

Metakaolin-based geopolymer (MKG), as a green cementitious material that can replace ordinary Portland cement (OPC), often has application limition due to pronounced drying shrinkage and cracking. To enhance shrinkage reduction effect and clarify the underlying mechanisms, this study selected two alcohol- and ether-based shrinkage-reducing admixtures (SRAs), namely 2-methyl-2,4-pentanediol (MPD) and diethylene glycol monobutyl ether (DB), and systematically investigated the effects of different SRA blending ratios on the drying shrinkage, mechanical properties, geopolymerization reaction, and pore structure of MKG. The results indicated that SRA effectively mitigated the drying shrinkage of MKG. The MKG-M3D1 specimen exhibited the most significant reduction in shrinkage during the early curing age. At 28 d, the drying shrinkage of the MKG-M1D3 specimen reduced by 28.86% compared with the control specimen. Although SRA can effectively reduce drying shrinkage, the incorporation of SRA inevitably had an adverse effect on the mechanical properties of MKG. In addition, the incorporation of SRAs did not alter the types of geopolymerization reaction products, the main reaction product was N-A-S-H gel. Both SRAs significantly reduced the volume fraction of capillary pores (5-100 nm) in MKG, from 43.94% in the control specimen to 41.42% and 42.74% in the MKG-M3D1 and MKG-M1D3 specimens, respectively. The resulting refinement of the pore size distribution contributed to the mitigation of drying shrinkage. Moreover, although the composite SRA exhibites a relatively weak ability to reduce surface tension of solution, its excellent resistance to volatilization enables it to maintain lower surface tension in pore solutions and more effectively retard the evaporation of solution. Due to the synergistic interaction between MPD and DB, the hydrogen bonds formed between hydroxyl and ether groups significantly enhance the shrinkage reduction effect.

Shrinkage-reducing admixtures (SRAs) can effectively mitigate the drying shrinkage of cement-based materials, but the influence of SRA structures with varying configurations on drying shrinkage remains unclear. This study mainly synthesized two types of SRA by using different shrinkage-reducing monomers and investigated the impact of SRA with distinct branch chain structures on the surface tension, contact angle, and viscosity of solution. Then, the drying shrinkage, mechanical properties, and microstructure of cement-based materials with SRA were further discussed. The findings indicated that Type II SRA with a complex branched-chain structure presents a greater steric hindrance effect, leading to a more significant decrease of surface tension and increase of solution viscosity and contact angle than that of Type I SRA. Meanwhile, samples with Type I SRA presented a smaller drying shrinkage, whereas Type II SRA showed a stronger reduction in surface tension, indicating the mechanism of SRA inhibiting the drying shrinkage is not limited to the reduction of surface tension. Pores below 50 nm are conducive to reducing drying shrinkage, and the pore volume of sample with Type I SRA was significantly reduced by 20.3%, which showed an excellent drying shrinkage inhibition effect.

Underground coal gasification (UCG) constitutes an essential pathway for clean fossil energy utilization. However, the traditional carbon conversion efficiency index fails to discriminate the energy efficiency contributions between CO and CO2, thereby impeding advanced gasification control strategies. This study introduces the Oxygen-specific energy yield (eta O-2) metric, which excludes the interference of CO2 in the syngas and directly quantifies the chemical exergy output per unit oxygen consumption. To elucidate the influence of CO2 concentration on underground coal gasification process, we conducted gradient-controlled experiments comparing O-2-enriched CO2 (O-2-CO2 = 70-30 to 40-60 vol %) versus O-2-enriched air (O-2-N-2 = 50-50 vol%), and the evolution of syngas components, oxygen-specific energy yields and carbon utilization efficiency were quantitatively characterized. Results demonstrate that at 40 vol% CO2 concentration, eta O-2 peaks at 339 MJ/kmol with syngas calorific value of 7.63 MJ/Nm(3), attributed to the oxidation reaction and the reduction reaction reach the optimal balance. Exceeding the CO2 concentration threshold (>40 vol%) triggers a 25.9 % decline in eta O-2 (339-250 MJ/kmol), confirming the existence of a critical point in CO2-mediated oxidation-reduction equilibrium. At 60 vol% CO2 concentration, net CO2 consumption reaches 0.067 Nm(3)/kg, while syngas calorific value declines to 4.46 MJ/Nm(3). This study provides dual-mode optimization strategies for UCG, namely "Energy Efficiency Priority Mode (40 vol% CO2)" and "Carbon-Negative Optimization Mode (60 vol% CO2)", respectively focus on maximizing of energy recovery and net CO2 consumption

The introduction of water vapor as a gasification agent in the study of Underground Coal Gasification (UCG) is conducive to the improvement of combustible gas generation, which is of greatsignificance in promoting the advancement of coal clean utilization technology. The effect of the change of vapor-oxygen ratio on the generated gas components during underground coal gasification was investigated, and the effect of the change of vapor-oxygen ratio on the calorific value of coal gas and gasification efficiency (the ratio of calorific value of coal gas to the heat of combustion of carbon) was analyzed through the evaluation of energy recovery. On this basis, the gasification process was divided into an ideal gasification stage and a secondary conversion stage, and the effects of oxygen excess and deviation (the deviation between the actual reaction occurring in the gasification process and the ideal gasification reaction) on the generated gases and calorific values were investigated. The results indicate that changes in the air-to-oxygen ratio significantly affect the volume fraction content of the main combustible components (CO+H2) in the generated gas. When the steam-to-oxygen ratio increases from 1.5∶1.0 to 2.0∶1.0, the volume fraction of (CO+H2) in the generated gas increases with the increase in the steam-to-oxygen ratio, reaching a maximum of 62.39% at a steam-to-oxygen ratio of 2.0∶1.0, with the H2 volume fraction stabilizing at approximately 30%. The gasification efficiency and gas calorific value both reach their maximum values. However, when the steam-to-oxygen ratio exceeds 2.0∶1.0, the volume fraction of the main combustible gases begins to decrease. Through staged analysis, it was found that when the oxygen supply exceeds the amount required for the ideal gasification reaction, the combustible gases produced by the reaction undergo a secondary reaction with excess oxygen, generating low-calorific CO2, thereby reducing the calorific value of the gas. As the deviation increases, the water gas reaction and water gas shift reaction become more intense, leading to an increase in the volume fraction of (CO+H2), thereby increasing the calorific value. However, when the supply of steam is excessive, the excess steam lowers the reaction temperature, inhibits the water gas reaction, reduces the deviation, and consequently decreases the volume fraction of CO and H2 in the generated gas, leading to a decrease in calorific value. Therefore, in the experiment, the oxygen excess should be moderately reduced to minimize CO2 production, while the steam supply should be appropriately increased to enhance the deviation, promote the water gas reaction, and improve gasification efficiency and gas calorific value.

Underground Coal Gasification (UCG) is a technology that enables the extraction of coal energy by converting coal seams into syngas, which mainly consists of H2, CO, and CH4. During UCG, the temperature in the reaction zone can exceed 1300 degrees C, raising concerns regarding the potential melting of the steel pipes used for oxidant injection. To mitigate this issue, this study investigated the use of water as an injection agent. Water injection serves two key purposes: cooling the injection pipe and enhancing H2 production. To examine the effects of water injection on temperature in gasification zone and product gas composition, a UCG model experiment was conducted. The results show that water injection effectively inhibit melting pipe by decreasing the temperature in the gasification zone without compromising H2 production, although the CO concentration decreases and the CO2 concentration increases. Additionally, the energy recovery loss due to water injection can be estimated based on the amount of water injected, as the heat loss from water evaporation is the dominant factor. These findings demonstrate that water injection is a viable strategy for preventing pipe melting while enhancing H2 production in UCG processes.

Diatomaceous earth (DE) possesses a unique pore structure, making it a promising candidate for microorganism immobilization. However, systematic research on the use of DE with varying mesh sizes in cement-based materials remains limited, particularly concerning its potential applications in microbial systems. This study investigates the effect of DE with varying mesh sizes, immobilized with microorganisms, on the mechanical properties and microstructure of cement-based materials. The focus is on the changes in DE's pore structure and pozzolanic activity under optimal immobilization conditions. The results show that cement-based systems with DE of different mesh sizes exhibit a reduction in early strength when compared to the control group. However, as curing progresses, performance gradually improves, with the system containing 800 mesh DE demonstrating a significant increase in long-term strength enhancement. Following microbial immobilization, DE shows a considerable reduction in porosity and a substantial increase in its pozzolanic activity. Further analysis reveals that the 800 mesh DE improves mechanical properties, hydration products, and pore structure, demonstrating significant modification effects. These findings provide valuable insights for optimizing cement-based materials.

The low strength of hemihydrate phosphogypsum (HPG) limits its wider applications in construction, and the use of alkali-activated mineral admixtures to improve HPG’s mechanical properties has enormous environmental benefits. In this paper, slag and fly ash were added to HPG, which was then activated by NaOH. The effects of alkali activation on the mechanical properties of HPG were investigated, and the hydration mechanism of modified and enhanced HPG was investigated by X-ray diffractometer (XRD), Thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR), and Low-field nuclear magnetic resonance (LNMR). The results showed that alkali-activated mineral admixtures can improve the compressive strength of HPG up to 40 MPa with the optimal mix ratio: HPG:(GGBS+FA) = 60:40 by weight, where the ratio of GGBS to FA is 4:1 by weight, and NaOH accounts for 1% by mass of the binder. When NaOH was added at 1wt% of binder, it could effectively activate slag and fly ash to enhance the mechanical properties of HPG. With the increase of the dosage of NaOH, settings of HPG were prolonged and its strength was reduced. The hydration products such as ettringite (AFt) and C-S-H gel generated by NaOH-activated slag and fly ash can effectively fill the pores of HPG paste and thus improve its mechanical properties. When hydrated for 28d, the decrease in strength due to the increase in NaOH dosage can be attributed to the decrease in AFt generated from hydration. The findings of this study pave the theoretical and technical foundations for greater and wider utilization of phosphogypsum for a sustainable future.

Underground coal gasification (UCG) is a promising technology, but the groundwater pollution caused by UCG is a potential risk to the environment. The measured results of the stratum in the combustion cavity resulting from UCG had proved that the combustion cavity would be filled with some UCG residues and caving rocks when UCG was finished. The pollutants in underground water around the combustion cavity include organic pollutants, inorganic pollutants, and ammonia nitrogen, and one of primary organic pollutants is phenol. The migration and diffusion characteristics of organic pollutant (taking phenol as representative) in the groundwater of the combustion cavity was investigated by breakthrough experiments and numerical simulations. The results show that the hydraulic conductivity of the coarse UCG residues is much than that of fine residues, and the hydraulic conductivity of the UCG residues with the size of -0.15 mm and 0.15–0.3 mm are 4.68×10− 6 m/s and 1.91×10− 4 m/s respectively. The dispersivity λ for the migration of organic pollutants will be influenced significantly by the size of UCG residues in fractures of the combustion cavity, while the distribution coefficient Kd will not. The dispersivity of organic pollutants in the fine UCG residues is more significant than that in the coarse residues, and the λ for the two kinds of residues are 3.868 and 1.765 cm, respectively. The shape of the migration path slightly affects the pollutant concentration distribution along the path, but the width of a path has a more pronounced influence on the concentration distribution. In this research, the influence was formulated by a new technical term, MPWIT related to transverse dispersion. Specifically, while the transverse dispersion values account for 20 and 10% of the longitudinal dispersion respectively the corresponding MPWIT values are 39.48 and 33.96 mm.

Microbially induced carbonate precipitation (MICP), an emerging technique recently, has been investigated in extensive studies for its ability to improve or enhance the properties of materials. This paper mainly explored the effect of MICP on the early strength and hydration products in fly ash blended cement paste (FABC) under different MICP treatment measures. Firstly, the influence of different environment on the growth of microorganism and three calcium source (CaCl2, Ca(CH3COO)2 and Ca(NO3)2) on the production of calcium carbonate precipitation were investigated. The experimental results presented that the efficiency of CaCO3 precipitation in the Ca(NO3)2 sample by adding bacterial solution is higher than other groups. Compared to untreated specimens, the mechanical properties of FABC paste are adversely affected by direct mixing with bacterial solution (MICP1) due to the fact that the hydration reactions of C3S and Ca(OH)2(CH) in FABC system were negatively affected as indicated by the hydration heat measurement. In contrast, the early performance of drying-immersing sample in bacterial solution (MICP2) was improved, with a maximum efficacy of 52.03%. The hydration process was facilitated in FABC paste treated with MICP2 treatment, further leading to increased formation of CH, C-S-H and AFt. Furthermore, Nanoindentation showed the HD C-S-H gel and CH were the dominant phases in MICP2 samples, and the matrix became denser with more hydration products, which also confirmed the increase in macroscopic compressive strength. The findings of this work can provide a guidance for the application of FA based on MICP method for enhancing the early strength in cementitious materials.

Groundwater pollution induced by Underground Coal Gasification(UCG)seriously hinders its development.Permeable Reactive Barrier(PRB)remediation therefore stands out as a major research focus for in-situ groundwater remediation, where the characteristics of PRB material is crucial to their effective operation.This study thus examines the adsorption properties of sand, organic bentonite, and activated carbon on phenol, a characteristic organic pollutant associated with UCG.A self-constructed permeation experimental system is employed to study the adsorption and permeation characteristics of sand, organic bentonite, activated carbon, mixtures of sand and organic bentonite, as well as sand and activated carbon to investigate their comprehensive impact in purifying contaminated water.The results indicate that: ①Organic bentonite exhibits a rapid adsorption rate for phenol in solution, reaching adsorption equilibrium within 10 minutes, despite a relatively low adsorption capacity(1.98 mg/g). Activated carbon, on the other hand, demonstrates a slower adsorption rate yet a higher adsorption capacity(2.22 mg/g).②The adsorption of phenol by organic bentonite conforms to the Freundlich isotherm model, with parameters kF = 0.040 and n = 1.207.Activated carbon follows the Langmuir isotherm model, with parameters Smax = 2.44 mg/g and kL= 0.125 L/mg.③The permeability coefficients of sand and activated carbon are 1.006×10-3 m/s and 4.761×10-2 m/s, respectively.The mixture of sand with activated carbon or organic bentonite could effectively moderate the permeability of the mixed material.When the mass ratio of sand to organic bentonite increases from 1∶1 to 3∶1, the permeability coefficient of the mixed material increases from 2.624×10-6 to 3.468×10-5 m/s.Conversely, when the ratio of sand to activated carbon increases from 1∶1 to 3∶1, the permeability coefficient of the mixed material decreases from 1.379×10-3 to 1.301×10-4 m/s.

In this paper, the effects of changing the injection position of a gasification agent on temperature fields and gas compositions are investigated through an experimental model of the underground gasification of coaxial coal. A 3D model of the temperature field is constructed based on the experimental temperature parameters using kriging interpolation; the 900 C isothermal surface is used as the reference plane to define the oxidation zone, and its plane and volume expansion rate are analyzed. The underground coal gasification experiment is divided into five stages according to the injection location. The average expansion rates of the oxidation zone in each stage are 2.04 cm/h, 1.93 cm/h, 3.44 cm/h, 3.68 cm/h, and 3 cm/h along the X-direction and 0.69 cm/h, 0.09 cm/h, 0.56 cm/h, 1.69 cm/h, and 1.01 cm/h along the Z-direction; the expansion rate along the X-direction is greater than that along the Z-direction. The expansion volumes of the oxidation zone after the five stages increase from 0.0097 m3 to 0.0168 m(3), 0.0321 m(3), 0.0521 m(3) and 0.0657 m(3). An analysis of the expanded volume of the oxidation zone compared with the volume of the cavity shows that both features are similar in shape and that the final volume of the cavity is smaller than the final expanded volume of the oxidation zone; the volume of the cavity is approximately 77.3 % of the expanded volume of the oxidation zone. The formation of a cavity requires the temperature to reach the conditions for the oxidation reaction of the coal and the rupture and flaking of the ash layer that accumulates after the reaction by the actions of certain stresses, such as thermal. The composition of the product gas and the strength of the chemical reactions involved are evaluated based on stoichiometric conservation. A short period after a shift in the injection position of the gasifier greatly impacts the chemical equilibrium of the UCG process with a large change in the strength of the chemical reaction, followed by a relatively small change when the gasification process stabilizes.

Underground Coal Gasification (UCG) is a promising process for recovering energy from potential underground coal resources as combustible gases such as hydrogen and carbon monoxide. The gasification process that occurs underground is an invisible phenomenon, and the temperature in the underground gasification reaction zone can be over 1,000 °C. Therefore, the visualization/monitoring of the gasification area of UCG plays an important role in the development of a highly efficient, safe , and low environmental impact UCG system. This article reviews the possibility of monitoring high-temperature gasification reaction zones in UCG using Acoustic Emission (AE) technique. AE monitoring can be used as a real time monitoring technique because AE can be detected at the same time when the cracks occur due to the gasification, indicating that it gives an advance warning immediately if the extensive damage occurs. The challenges and future prospects for estimating the gasification reaction area by AE technique are also addressed at the end of article.

The high shrinkage of metakaolin-based geopolymers (MKGs) dramatically limits their application as high-performance green cementitious materials. In this study, microscopic tests and microstructure analysis of the polymerization reaction products are employed to examine the drying shrinkage properties of MKG under different alkali equivalents. The results indicate an enhancement in the strength of MKG mortar with increasing alkali equivalent; however, it undergoes shrinkage in the later stages. Notably, the drying shrinkage increases with the alkali equivalent, mainly attributed to the fact that the increase in alkali equivalent does not change the types of hydration products in MKG. Instead, it promotes the dissolution of active silicon oxide and alumina in metakaolin (MK) particles, accelerating the hydration reaction process and, resulting in a higher amount of sodium aluminosilicate hydrated gel (N & horbar; A & horbar; S & horbar; H) gel. Furthermore, the alkali equivalents modify the pore size distribution, leading to an increase in the 10-50-nm pore volume and capillary negative pressure, ultimately causing an increase in drying shrinkage.

Geopolymers, environmentally friendly materials, face application limitations due to their high drying shrinkage and propensity for cracking. The shrinkage reducing admixture (SRA) has shown promise in mitigating drying shrinkage in cement-based materials, yet its impact and mechanism in geopolymers remain uncertain. This study examines the influence of the small molecule polyol SRA-2-methyl-2,4-pentanediol on metakaolin-based geopolymer (MKG) properties and its multiscale structural development, aiming to understand the drying shrinkage behavior. The findings reveal that SRA significantly curbs the drying shrinkage of MKG while also reducing its mechanical properties. Analyses of macroscopic and microscopic properties indicate that while SRA does not alter the hydration products of MKG, it can impede the hydration process, particularly in the early stages. Specifically, SRA inhibits the formation of N-A-S-H gel, thereby reducing shrinkage caused by late-stage polycondensation. Furthermore, the alkaline environment in MKG aids SRA in lowering pore solution surface tension and increasing its contact angle, reducing drying shrinkage forces. Additionally, SRA modifies MKG's micro-structure, decreasing pore volume, particularly in the 10–50 nm range, further mitigating shrinkage due to surface tension.

Underground coal gasification (UCG) is process of directly recovering energy as combustible gases such as hydrogen and carbon monoxide by combusting unmined coal resources in situ. During UCG process, the temperature in the gasification zone can exceed 1,300 degrees C, raising concerns about the potential melting of the steel pipe for oxidant injection. To control the temperature in the gasification zone, the use of water injection as an injection agent can be an option. Injecting water during UCG process serves two purposes: it decreases the temperature in the reaction zone by the endothermic effect of water, and it enhances the production of H2 by the reduction reaction of water. However, injecting excessive amounts of water may lead to a significant decrease in the temperature in the reaction zone, consequently cannot maintain the temperature range required for the UCG reaction. This study discusses the effects of water injection on the temperature of the gasification zone and the product gas by developing a chemical reaction model of UCG using COMSOL Multiphysics (R) software. The model was developed based on the temperature and produced gas results obtained from laboratory-scale artificial coal seam UCG experiments. Our findings reveal that water injection significantly influences the gasification process, controlling temperature in the reaction zone and promoting H2 production through steam gasification and water-gas shift reactions. Moreover, under the experiment and analysis conditions of this study, it is revealed that water injection up to an H2O/O2 molar ratio of 3.9 can effectively control the temperature of the gasification zone with enhancing H2 production.

The study of energy recovery from underground coal gasification(UCG)with different gas injection methods is conducive to the development of a more efficient UCG process.Various UCG modeling experiments were designed and implemented for fixed and mobile gas injection points,the total gasification coal consumption and rate were calculated based on stoichiometry and carbon balance method,and the effects of the two gas injection processes on the composition and calorific value of the gas were compared and analyzed.On this basis,the changes in gas production per unit of coal and effective gas composition under different gas injection methods were analyzed,and the energy recovery rates of the two gas injection process experiments were evaluated.The results show that increasing the net O2 injection flow rate can improve the gas calorific value decay in the fixed injection point experiment,but the promotion effect of increasing the net O2 injection flow rate on the gasification reaction decreased with the expansion of the gasification cavity.By increasing the net O2 injection flow rate three times,the calorific value of gas was increased by 2.01,1.27 and 1.10 MJ/m3,respect-ively,and the gasification efficiency(the ratio of the calorific value of the gas to the heat of combustion of carbon)was in-creased by 14.64％,9.45％and 7.73％,respectively.Moving the position of the gas injection point can achieve a short-time rapid recovery of the calorific value of the gas and the gasification efficiency.Moving the position of the gas injection point four times,each time the moving distance was 300 mm,the calorific value of the gas was increased by 2.95,3.32,3.37 and 2.54 MJ/m3,respectively,and the gasification efficiency was increased by 17.99％,21.04％,27.88％,and 13.92％.The two gas injection process experiments respectively gasified 72.49 kg and 91.47 kg of coal,and the average coal consumption rate was 0.97 and 1.27 kg/h.The gasification efficiency and coal consumption rate showed a synchron-ous mutation,and this phenomenon was more obvious after changing the injection conditions of the gasifier and moving the position of the gas injection point,which indicated that there was a certain relationship between the gasification effi-ciency and the coal consumption rate.Compared with the fixed gas injection point experiment,moving the location of the gas injection point can effectively improve the gasification effect,and the effective gas composition and gasification effi-ciency was increased by 12.5％and 23.23％,respectively,under the same gasifier injection conditions.