Clean Coal Technology Research Articles

Effect of the main components in gasification wastewater on the surface properties of coal water slurry

AbstractCoal water slurry is an advanced and efficient clean coal technology; using gasification wastewater to prepare coal water slurry can recycle wastewater and improve energy utilization efficiency. As the complex substances in wastewater have a great influence on the slurry properties, the effects of organic matter, metal ions, and ammonia nitrogen in gasification wastewater on the surface properties of coal water slurry are studied in this paper in order to provide new ideas for slurry mechanism of coal water slurry prepared from wastewater. Results show the following: (a) Compared with ordinary coal water slurry, the concentration of coal water slurry prepared from wastewater with high organic content increased by 2.9%, while the concentration of coal water slurry prepared from wastewater with high ammonia nitrogen content decreased by 2.1%. (b) The contact angles of coal water slurry prepared with phenols, alcohols, and urethane are reduced by 2.8°, 6.3°, and 1.5°, respectively, so organic matter can change the hydrophilicity of coal particles and affect slurryability. (c) Mg2+ and Ca2+ have basically no effect on slurry. Fe3+ reduces the absolute value of Zeta potential by 33.1, and Cu3+ increases that by 22.8, as they affect the slurryability by changing the surface potential of coal particles and the absorption of additives. (d) Ammonia nitrogen influences the slurryability by changing the pH value of the slurry. The conclusion of the influence mechanism of organic matter, metal ions, and ammonia nitrogen in wastewater on slurryability can provide a technical reference for the selection of suitable wastewater to prepare coal water slurry.

Ripple effects of coal phaseout on employment in China: From mining to coal consumption sectors

China's stringent decarbonisation, marked by an uncompromising coal phaseout, has induced significant ripple effects across the coal industry chain's employment structure. By utilising a composite methodology that integrates the Global Change Assessment Model and Input‒Output Model, this study systematically quantifies the impact on employment, revealing a loss of 1.6 million jobs in mining and 8.2 million in the entire chain. Concurrently, a labour shift to the renewable sector has resulted in an 18.5% increase in employment, equivalent to creating 508,000 new positions from 2017 to 2020. Projections suggest that renewable energy initiatives could address 25% of the employment gap for precision by 2060 under carbon neutrality scenarios. Nonetheless, the coal sector is expected to lose more than 20 million jobs, indicating the need for a 2.3 trillion-yuan compensation fund. This study highlights the need for policy interventions to facilitate labour transitions through comprehensive retraining programs and strategic investments. Promoting economic diversification and clean coal technologies can improve resource utilization and create new jobs. Additionally, repurposing abandoned coal mines into energy storage facilities or renewable energy sites can prevent stranded assets and generate employment. These findings provide a robust framework for addressing the socioeconomic challenges of energy transitions, offering critical insights for other coal-dependent countries aiming for sustainable development.

Research on the Optimization and Application of New Energy Technologies in Clean Coal Conversion

With the continuous growth of global energy demand and increasingly severe environmental issues, clean coal technology has garnered significant attention as a crucial means to mitigate the negative environmental impacts of coal utilization. However, traditional clean coal conversion technologies often suffer from low energy utilization efficiency and insufficient environmental pollution control. In recent years, the application of new energy technologies in the clean coal conversion process has shown tremendous potential, significantly optimizing energy conversion efficiency, reducing emissions, and enhancing economic benefits. This paper systematically explores the application of solar energy, wind energy, and biomass energy in clean coal conversion, analyzes the mechanisms and methods through which new energy technologies optimize the clean coal conversion process, and proposes future research directions and policy recommendations.

Key SDG7 Factors Shaping the Future of Clean Coal Technologies: Analysis of Trends and Prospects in Poland

This article presents the results of an analysis aimed at verifying the relationship between the implementation of SDG Goal 7 and the use of clean coal technologies in Poland. Clean coal technologies in the United Nations plans will constitute a crucial element of the strategy for sustainable development in the energy context. They are intended to be one of the tools for building an energy system based on renewable energy sources, constituting a bridge that enables the transition of Poland’s energy system from coal to renewable energy sources. To identify whether this relationship exists, the Autoregressive Moving Average with Exogenous Input (ARMAX) model was used. The structure of the model, its correctness, and its accuracy were confirmed using information criteria; statistical tests such as Dickey-Fuller, Doornik-Hansen, Durbin-Watson, and Breusch-Pagan; and measures of prediction accuracy such as MAPE, MAE, and RMSE. The explanatory variables were the Objective 7 indicators adopted by Eurostat. Before being introduced to the ARMAX model, they were standardized using the Compound Annual Growth Rate (CAGR) indicator. The analysis made it possible to indicate which of the explanatory variables has the greatest impact on the development of clean coal technologies in Poland, to determine a synthetic CAGR measure for all the explanatory variables, and to compare the results obtained with the indicator determined by the United Nations.

Thermal reactivity and gas–solid product evolution during coal catalytic combustion: An experimental study

To achieve efficient and clean coal combustion, catalytic combustion technology has received widespread attention. This paper systematically studied the influence of calcium-based compounds on the thermal reactivity and gas–solid two-phase product evolution behavior of different coal using TG-MS and FTIR analysis, combining kinetics and thermodynamics methods, the catalytic coal mechanism was discussed. Results demonstrated that both catalysts improved the combustion reactivity, the burnout temperatures of lignite, bituminous coal and anthracite were reduced by 30.75 °C, 53 °C and 25.5 °C respectively with CaO, as well as decreased by 24.75 °C, 55.5 °C and 29 °C respectively with CaCl2. Meanwhile, it was worth noting that the activation energy of three coals was also reduced. CaCl2 was more likely to bind with the C = O functional group on the surface of coal, forming CO-Ca2+ complexes, resulting in a decrease in the content of C = O and C-O. While CaO tended to absorb volatile matter, causing local overheating and promoting the breakage of side chains and bridge bonds. Besides, the calcium-based compounds advanced the gas evolution peak of combustion and the emissions of CO2, NO2 and SO2 were effectively controlled. These results aimed at providing a new reference direction for further industrial development of clean coal combustion technology.

The Role of Clean Coal Technologies in the Development of Renewable Energy Sources

The Role of Clean Coal Technologies in the Development of Renewable Energy Sources

Research on the underground ignition mechanism of ignition fuel and ground simulation experiments

Abstract In the increasingly severe environment of the “dual carbon” situation and the urgent objective demand for national energy transformation and upgrading, the development and use of clean energy have become a new research field and direction. Underground coal gasification technology (UCG) is a clean coal technology that completely bypasses the traditional coal combustion process by converting coal underground into gas and then classifying and recycling it. This method removes sulfur before fuel combustion Nitrogen compounds and particles make it clean like natural gas. The most commonly used ignition method in this technology is chemical ignition. A certain proportion of ignition fuel and main fuel is injected into the underground through pipelines, and then combustion supporting gas is introduced to cause a chemical reaction and generate an open flame to ignite the coal. However, due to the complex internal environment of the pipeline, uneven bending of the pipeline column, and the length of the pipeline exceeding one kilometer, the concentration threshold of the ignition fuel when it reaches the underground igniter cannot be accurately controlled, resulting in ignition failure. In response to the above difficulties, this article has conducted research on the ignition mechanism of ignition fuel, and developed a dedicated ground simulation test bench to conduct ground simulation experiments. The research has strong support for the on-site pilot testing and engineering services of underground coal gasification technology.

Numerical modeling of hydrodynamics of spouted bed in solid fuel boiler

The issues of numerical modeling of hydrodynamics of a spouted fuel bed in the furnace of a solid-fuel boiler are considered. At present, solid-fuel boilers are widely used in the power industry of the Russian Federation, with the share of coal-fired generation to remain significant in the projected terms. Therefore, the study of the efficiency of thermal and hydrodynamic processes that ensure the implementation of clean coal technologies is a relevant task both today and in the long term. The article presents the following main stages of numerical modelling of the hydrodynamics of the spouted bed: problem formulation with selection of boundary and initial conditions, methods of solving the Navier-Stokes and continuity equations for the air flow, Newton's equations and diffusion equations for particles. The k-omega turbulence model was used in the calculations that is described by means of two partial differential equations for the variables k (kinetic energy of turbulence) and omega (specific dissipation rate). A comparative analysis of environmental advantages and disadvantages of existing methods of combustion of low-grade coal in schemes with in-cycle gasification (ICG) is carried out. Advantages and difficulties of switching to structures with CFB in the spouted bed mode are shown. Numerical modeling of the cold spouted bed created by means of particle injection is performed, a set of initial settings and boundary conditions is presented, the adequacy of the obtained results is verified by hydrodynamic characteristics of the isothermal process. The obtained results allow us to proceed to the next stages with non-isothermal models, with heat exchange and combustion reactions in the spouted bed of coal taken into account. The following refinement of the physical model will allow to achieve more accurate and reliable results and to ensure their correct scaling.

Effect of Equivalent Ratio and Hydrocarbon Ratio on Explosive Characteristics of Synthetic Gas

With the development of society, the importance of energy is increasing day by day, and more and more people realize the importance of energy for social development.Therefore, people began to explore energy utilization, energy exploitation, clean energy and other fields.Therefore, in order to use coal resources cleanly and efficiently and reduce the damage to the environment, the development of clean coal technology is particularly important.As a kind of clean energy, syngas has been paid more and more attention, so people pay more and more attention to the safety application of syngas. This paper explores its influence on syngas explosion by changing the equivalent ratio of syngas and the ratio of hydrogen and hydrogen.The results show that the maximum explosion pressure of syngas occurs near the equivalent ratio 1.2, the maximum explosion pressure rise rate reaches the maximum near the equivalent ratio 1.5, and the maximum explosion pressure time reaches the minimum near the equivalent ratio 1.5.The change of hydrocarbon ratio does not shift the equivalent ratio of the above result, but only changes its value. The prediction equations for predicting the maximum explosion pressure under different equivalent ratios are obtained

Dependence and sustainability: a disaggregated analysis of electricity generation in ASEAN countries

PurposeThis study aims to explore the diverse sources of electricity generation (coal, natural gas, oil and hydroelectricity) and their respective associations with economic growth and environmental quality.Design/methodology/approachThis study uses static panel data analysis with a random effects model for six selected ASEAN countries (Indonesia, Malaysia, Filipina, Thailand, Vietnam and Myanmar) from 1994 to 2014.FindingsThis study reveals that economic growth in six selected ASEAN countries is enhanced by electricity generation from all sources, while the contribution of electricity production from hydroelectricity remains the largest and strongest. There is no environmental impact of electricity production from hydroelectric, whereas fossil fuel-based electricity production emits carbon dioxide, with coal sources being the largest contributor, followed by natural gas and oil.Practical implicationsBased on the results, these six ASEAN countries should invest more in hydropower projects, reduce the coal mix in power generation and promote clean coal technology to improve economic efficiency and environmental sustainability.Originality/valueTo the best of the authors’ knowledge, no research has examined the relationship between electricity production, environmental quality and economic growth in Southeast Asian nations. Therefore, the outcome of this study is expected to provide insightful results to supplement the framing and implementation of national and collective regional strategies for sustainable electricity generation in ASEAN countries.

A detection method for densely distributed coal and gangue with uneven particle based on DeepLabV3+

Separating mixed gangue in raw coal is one of the most critical processes in clean coal technology. However, the dense distribution of raw coal makes the visual image have adhesive, occluded, and tiny materials, which are not conducive to effectively detecting gangue. To solve these problems, we optimized the backbone, necknet, and decoder structure of DeepLabV3+, and constructed a target segmentation network for dense coal and gangue (TSNet_DCG) suitable for raw coal sample characteristics. Then, the verification and test experiments were carried out based on the self-collected multi-condition coal and gangue data set. The experimental results show that the average F1_score of the model is 0.983, and the detection speed is 32.5 FPS on our personal computer. This model can be adapted to the poor working environment in coal mines and realizes the low-cost and high-efficiency identification and localization of coal and gangue.

Analysis of the Impact of Clean Coal Technologies on the Share of Coal in Poland’s Energy Mix

This article presents research results on the share of coal in the energy mix and the impact of clean coal technologies on Poland’s energy mix. Two mathematical models were utilised: the Boltzmann sigmoidal curve and a supervised machine learning model that employs multiple regressions. Eight explanatory variables were incorporated into the model, the influence of which on the explained variable was confirmed by Student’s t-test. The constructed models were verified using ex post errors and the Durbin–Watson and Shapiro–Wilk statistical tests. It was observed that the share of coal in the mix decreased more dynamically after 2015 compared to previous years. Furthermore, a simulation was conducted using the machine learning model, which confirmed the hypothesis on the influence of clean coal technologies on the level of coal share in the Poland energy production structure. As shown by the analysis and simulation, coal could be maintained in the energy mixes of EU countries, and even if the negative aspects of using this fuel were limited—primarily the emission of harmful substances—its share could even increase. It was noted that this share could be higher by 22% assuming a return to the interest in CCT levels from before 2015 and the reduction in CO2 emissions using membrane techniques proposed by the authors. Clean coal technologies would enable diversification of the energy mix, which is an important aspect of energy security. They would also enable the gradual introduction of renewable energy sources or other energy sources, which would facilitate the transition stage on the way to a sustainable energy mix.

Experimental and ReaxFF MD study on the release characteristics of gaseous nitrogen during pressurized bituminous coal gasification

Coal gasification is the leading technology of clean coal technology such as Integrated Gasification Combined Cycle (IGCC). The release pattern of gaseous nitrogen during coal gasification is crucial for clean coal technology. This paper investigated the gaseous nitrogen emission characteristics of pressurized gasification through experiments and molecular dynamics studies. The experimental results show that the elevated temperatures promoted the release of NO and accelerated the conversion of nitrogen-containing precursors (HCN, NH3). However, high pressure weakened the effect of temperature and resulted in the decreased emissions of HCN, NH3, and NO. Because high pressure facilitated the conversion of fuel nitrogen to nitrogen. The emissions of HCN and NH3 decreased as the CO2 blending ratio increased, while NO emissions increased. The observed difference was primarily attributed to the amounts of free radicals and was also related to gas-phase reactions involving H2O and CO2. Furthermore, as the primary nitrogen-containing structure in bituminous coal, the pyrrole was used in Reactive force field molecular dynamics (ReaxFF MD) to study the release of gas-phase nitrogen during gasification process. The simulation results show that both temperature and pressure promote the migration of pyrrole nitrogen and also provided the main nitrogen migration paths during gasification which can be used to (indirectly) confirm the experimental analysis. The O2/N2/CO2 gasification system supplied additional O and OH radicals to enhance NO emissions, while H2O directly participated in reaction paths such as CN, NCO → NHi or provided H radicals to increase NH3 emissions.

Supply security and the reliability of the Spanish generator system in the next two decades based on the costs of fossil fuels and nuclear option.

The supply security of the primary energy sources (coal, natural gas, enriched uranium…) and the reliability of the system in terms of the oscillations of the frequency and voltage are two aspects to assess in the Generation Expansion Planning. In this article, for the first criterion, the evolution of vulnerability and degree of independence of the generator system with respect to primary energy sources has been assessed by the indexes of Shannon-Weiner and energy independence, respectively. For the second approach, the evolution of the reserve margin by means the coverage index and the progression of the inertia and regulation capacity by means of its percentage regarding the total installed capacity. These four indexes have been applied on the obtained results of a stochastic lineal model developed with the software GAMS. In this model the nuclear technology has been considered as generation option in several scenarios of costs of the fossil fuels, coal and natural gas. Also, two of clean coal technologies with greater possibility of putting into service have been taken into account. The final conclusion would be that each technology carries out several functions in the generator system but not all them. That is, a generator system should have the greatest possible number of types of generation to be reliable and have supply security.

Clean coal technologies with carbon capture, utilization and storage in China’s coal industry

Clean coal technologies with carbon capture, utilization and storage in China’s coal industry

Reform and Exploration of Clean Coal Technology Curriculum under the Background of Dual Carbon Strategy

Reform and Exploration of Clean Coal Technology Curriculum under the Background of Dual Carbon Strategy

Research on the underground gasification of lignite through an oxygen enrichment process: insights from experimental study and Aspen Plus process model.

Underground coal gasification (UCG) can convert coal resources to high-calorific value syngas, which is important for the exploration of resources and the application of clean coal technology. This study investigated the gasification process of lignite in Heilongjiang Province through an oxygen enrichment approach and examined the impact of the oxygen concentration on the gasification efficiency. Furthermore, a high-fidelity Aspen Plus process model was designed to predict the gasification products of lignite. These findings indicate that the abrupt increase in the gasification temperature and pressure is governed by the concentration of oxygen in the gasification agent. An increased concentration of oxygen results in a higher gasification temperature, thereby influencing the thermodynamic reaction processes within the gasifier. The combustion reaction of lignite transitions into a coke reaction when the oxygen concentration is elevated to 90%. At this time, the relative concentration of CO2 generated from lignite combustion progressively diminished from 78.33%, while the relative concentrations of H2 and CO produced through coke reactions gradually increased from 3% and 2.07%, respectively. When the oxygen concentration reaches 100%, the relative contents of H2 and CO generated through gasification reach their respective maxima, measuring 18.90% and 23.91%. The calorific value attained a peak of 6.65 MJ N-1 m-3 simultaneously. Furthermore, the ash yield of lignite may be a critical factor influencing the process of underground coal gasification. The gasification efficiency of lignite near T 6 is suboptimal when the oxygen concentration falls below 100%, potentially attributable to the influence of ash. In summary, lignite in Heilongjiang Province can be effectively developed through underground gasification technology via an oxygen enrichment process. Furthermore, the Aspen Plus model we developed can effectively assist in predicting the products of lignite gasification in Heilongjiang Province.

Efficient coal-based power generation via optimized supercritical water gasification with chemical recuperation

Supercritical water gasification (SCWG) is promising as a clean coal technology and is an emerging topic of interest in sustainable energy. Here, we introduce a clean and efficient power generation system that optimizes SCWG of coal through chemical recuperation. Central to our approach is the innovative utilization of both exhaust and a portion of the syngas as dual heat sources for gasification, simultaneously producing the requisite supercritical water. This chemical recuperation strategy effectively enhances the transformation of coal chemical energy into syngas. The introduced system achieves power generation and exergy efficiencies of 56.64 and 55.30%, respectively, outperforming those of a baseline system by 8.43 and 8.23%, respectively. This gain is primarily attributed to the irreversible losses in the gasification, air separation, and heat-exchange processes of the introduced system, which were reduced by 8.75, 2.47, and 4.17%, respectively, compared with the corresponding values of the baseline system. In order to elucidate and validate the reduced irreversible losses in the introduced system compared with those in the baseline system, we incorporated the energy utilization diagram methodology into our analysis. In summary, the introduced system represents a pivotal advancement in clean and efficient coal-based power generation and underscores the need for continuous innovation in this sector.

Modelling underground coal gasification: What to start with

Underground coal gasification (UCG) is widely regarded as a clean coal technology that holds enormous potential to decarbonize the world's coal industry. It converts coal underground into combustible syngas through a set of complex physiochemical events. Experimental and numerical efforts over the past century have contributed to the development of UCG around the world; however, tapping the world's deep-situated coal resources with UCG requires substantial contributions from numerous high-quality researchers. To facilitate effective engagement, this paper will provide a background on where to start if one wishes to undertake UCG modelling. First, a brief description of the fundamental phenomena involved in UCG is given. Then, a succinct introduction of the widely used modelling software is rendered, followed by a description of UCG studies to provide insight how to tune the various software packages for modelling UCG and where their strengths lie. This paper shall serve as guidance to new UCG modellers.

Coal efficiency, carbon reduction, and future policy perspective in Pakistan’s economic growth: a decomposition and decoupling approach

Pakistan is moving toward the large-scale use of coal. Coal plays a dominant role in Pakistan’s energy mix and is estimated to reach 30% by 2030. The purpose of this study is to analyze coal imports and indigenous reserves in relation to CO2 emissions. In particular, this study constructs the logarithmic mean Divisia index (LMDI) method to see the impact of the factors, decoupling index for the economic relationship, and pollution from coal-fired power plants from 1986 to 2019. The empirical results show that 1) coal consumption and imports are interrelated, while coal production has had the lowest production level since 1986; 2) the energy intensity impact plays a medium role in decreasing coal utilization, followed by the coal share effect; however, the aggregated impact accounts for 0.023% of the total coal use; 3) the economic and population activity effects progressively increase with coal consumption by 0.25% and 0.35%, respectively, with the annual average growth; 4) only “three” decoupling states were observed: expansive coupling, expansive negative decoupling, and weak decoupling. Expansive negative decoupling occurred due to high energy share and energy intensity. Expansive coupling occurred only in 2001 due to rapid growth in coal proportion and a sluggish decrease in energy intensity, and weak decoupling showed a decoupling association between economic growth and coal utilization; and 5) the various coal compositions, such as moisture, volatile matter, fixed carbon, ash, and sulfur, can be evaded by 1.82, 4.83, 5.16, 1.43, and 0.39 Mt currently. Finally, environmental analysis recognized that implementing clean coal technologies significantly saves fuel and, consequently, reduces emissions. This study also discusses further policies.