Performance Evaluation of Low-Carbon and Clean Transformation of China’s Coal Economy

In China,the oversupply of coal occurred in 2009,and from that year onwards,China’s coal economy began a low-carbon and clean transformation.Evaluating transformation performance is the research goal of this paper.The data collection for this paper includes data on deep processing of Chinese coal products from 2009 to 2020,as well as data on asset structure evolution and financial performance of 34 listed companies in the Chinese coal mining.Entropy value method is used to calculate the entropy value of low-carbon transformation,and the regression analysis is used to study the performance of cleaner transformation,the conclusion is as follows:(1)From 2009 to 2020,in China’s total energy consumption,coal consumption accounted for 71.6%in 2009 and 56.8%in 2020,the goals set by the state have been achieved.(2)The national goal of reducing the proportion of coal consumption and reducing carbon emissions has forced the transformation of deep processing of coal products.The transformation of coal enterprises towards low-carbon and clean production has achieved remarkable results.(3)From 2009 to 2020,the non coal industry income of 34 listed companies in China’s coal mining industry increased by 8.21%annually.At the same time,the asset structure was adjusted,and nearly 80%of the asset structure evolution showed an orderly development trend.(4)The regression analysis results show that the entropy value of coal deep processing products and the entropy value of asset structure adjustment are significantly related to transformation performance.The paper proposes to summarize the successful experience of China’s coal energy economic transformation,lay a foundation for achieving the carbon peak and carbon neutral goals in the future,further increase the intensity of coal deep processing,increase the proportion of clean energy in total energy consumption,and strive to control asset operation towards the goal of increasing the proportion of non coal industry income.

Gasification of lignite from Polish coal mine to hydrogen-rich gas

The efforts of the world research activities involved in clean coal technologies development focus to a considerable extent on integrated hydrogen and power generation technologies based on coal gasification.As an alternative to combustion pro-cesses,gasification offers increased efficiency,lower negative environmental impact as well as wider application range of the main product—synthesis gas—in power generation and chemical syntheses.In order to select the most optimal lignite for the purpose of gasification,it is necessary to determine coal reactivity,the key parameter characterizing how fast the fuel reacts with the gasifying medium and controlling its process ability in thermochemical conversion to energy and/or energy carriers.This paper presents the experimental results of oxygen/steam gasification of lignite coal char in a fixed bed reactor under atmospheric pressure and at the temperature of 700,800 and 900℃;the samples come from an open pit lignite mine in the southwest of Poland.The effectiveness of the gasification process was tested in terms of the total gas and hydrogen yields,gas composition,carbon conversion rate and chars reactivity.

Environmental issues from coal mining and their solutions

The environmental challenges from coal mining include coal mine accidents,land subsidence,damage to the water environment,mining waste disposal and air pollution.These are either environmental pollution or landscape change.A conceptual framework for solving mine environmental issues is proposed.Clean processes,or remediation measures,are designed to address environmental pollution.Restoration measures are proposed to handle landscape change.The total methane drainage from 56 Chinese high methane concentration coal mines is about 101.94 million cubic meters.Of this methane,19.32 million,35.58 million and 6.97 million cubic meters are utilized for electricity generation,civil fuel supplies and other industrial purposes,respectively.About 39% of the methane is emitted into the atmosphere.The production of coal mining wastes can be decreased 10% by reuse of mining wastes as underground fills,or by using the waste as fuel for power plants or for raw material to make bricks or other infrastructure materials.The proper use of mined land must be decided in terms of local physical and socio-economical conditions.In European countries more than 50% of previously mined lands are reclaimed as forest or grass lands.However,in China more than 70% of the mined lands are reclaimed for agricultural purposes because the large population and a shortage of farmlands make this necessary.Reconstruction of rural communities or native residential improvement is one environmental problem arising from mining.We suggest two ways to reconstruct a farmer's house in China.

A New Parameter of Cleanability to Determine the Clean Potential of Coal Resources

Objective This work is based on analysis on large numbers of coal data such as the latest national coal potential evaluation data and previous data published by REN Deyi, TANG Xiuyi and LU Xukun, and the evaluation methods of clean potential of coal resources proposed by predecessors. It is found that previous method rank coal is only in accordance with raw coal or washed coal, which fail to take full account of the changes in elements before and after coal washing. Some elements can be removed by washing or other methods, and others may be even enriched after the coal is washed. For this reason, this work defined a new parameter of cleanability and developed its calculation formula to determine the clean potential of coal resources. Cleanability is a comprehensive indicator based on the removal rate of each indicator harmful element in coal. The clean potential of coal is proportional to the value of cleanability. The higher the cleanability value is, the better the clean potential is, and vice versa.

Insights from principal component analysis applied to Py-GCMS study of Indian coals and their solvent extracted clean coal products

The present work aims at studying five Indian coals and their solvent extracted clean coal products using Py-GCMS analysis and correlating the characterization data using theoretical principal component analysis.The pyrolysis products of the original coals and the super clean coals were classified as mono-,di-and tri-aromatics,while other prominent products that were obtained included cycloalkanes,n-alkanes,and alkenes ranging from C_(10)-C_(29).The principal component analysis is a dimensionality reduction technique that reduced the number of input variables in the characterization dataset and gave inferences on the relative composition of constituent compounds and functional groups and structural insights based on scores and loading plots which were consistent with the experimental observations.ATR-FTIR studies confirmed the reduced concentration of ash in the super clean coals and the presence of aromatics.The Py-GCMS data and the ATR-FTIR spectra led to the conclusion that the super clean coals behaved similarly for both coking and noncoking coals with high aromatic concentrations as compared to the raw coal.Neyveli lignite super clean coal was found to show some structural similarity with the original coals,whereas the other super clean coals showed structural similarity within themselves but not with their original coal samples confirming the selective action of the e,N solvent in solubilizing the polycondensed aromatic structures in the coal samples.

Physical properties and filter cake structure of fine clean coal from flotation

In order to improve the dewatering rate and the effect of fine clean coal(FCC), the advanced method offine coal( 0.5 mm) dewatering and the correlated basic theory were investigated in this study. It was found that the dewatering by sleeve type press filter was an efficient way of FCC dewatering. On the other hand, the results also proved that particle size distribution, volatile matter, ash content, pore size distribution and specific surface area of coal particles of FCC samples, as well as viscosity and density of FCC slurry, were important parameters in determining the process of efficient dewatering. Especially, wet mass to dry mass, specific resistance of average mass, compressibility factor and microstructure of filter cake explained the reasons and mechanisms of fine clean coal efficient dewatering.

Study on characteristics of pipeline transportation and sulfur fixing of cleaned coal logs

As special cylindrical briquettes of coal for long distance pipeline transportation and directly cleaned combustion the cleaned coal logs should possess two characteristics of transportation in pipeline and cleaned combustion. In order to make cleaned coal logs a rational technology for manufacturing, cleaned coal logs was designed and compound sulfur fixing binders with high effects of binding and sulfur-fixing was selected and combined. In addition, by means of characteristic experiments of strength, wear, waterproof and sulfur-fixing five different cleaned coal logs made with different compound sulfur fixing binders in different compaction conditions was tested and measured. Experimental results indicated that the manufacturing technology of cleaned coal logs was reasonable and the combination of compound sulfur fixing binders was scientific. Cleaned coal logs made up with the fourth group of coal mixture had high strength, good waterproof property, efficient sulfur-fixing, good characteristic of transportation, and achieved the performance requirement for pipeline transportation and sulfur fixing.

Combined Removal of Surface Moisture and Dust from Feed Coal for Coal Dry Cleaning with an Air-solid Fluidized Bed

A demonstration plant and a commercial plant employing coal dry cleaning technology with an air-solid fluidized bed were built in China. The operation practice of these two plants shows that the surface moisture and the fines or dust of feed coal must be well controlled as low as possible. For this purpose, a new process of combined removal of surface moisture and dust from feed coal using a vibrated fluidized bed dryer was investigated in a batch test apparatus and a pilot test system. A mathematical model on drying kinetics of coal surface moisture was developed and three empirical formulas of the model coefficient involving the main operating variables were determined based on the test results from the batch test apparatus. The mathematical model shows that the surface moisture retained in coal during drying decreases exponentially with drying time. According to this model, a new divisional heat supply mode, in which the inlet gas of higher temperature was introduced into the fore part of the dryer and the inlet gas of lower temperature into the rear part of the dryer, was employed in the pilot test system. The pilot tests show that 1） the new divisional heat supply mode is effective for lowering down the average temperature and reducing the total heat loss of the outlet gas off the dryer, 2） the moist coal of about 60 g/kg surface moisture contentcan be dried to about 10 g/kg, and simultaneously the fines （〈1mm in diameter） adhering to the surface of coarse coal particles are completely washed off by the gas flow.

Ultra-Supercritical——A Preferential Choice for China to Develop Clean Coal Technology

The ultra-supercritical pressure coal-fired power-generation technology (USCT) isa mature, advanced and efficient power generation technology in the world. Comparisonsamong several principal clean coal power-generation technologies show that USCT withpollutant-emission control equipment is superior to others in efficiency, capacity, reliability,investment and environment protection etc. Analyzing the main problems existing in thermalpower industry, it is concluded that the USCT is the preferential choice for China to developclean coal power-generation technology at present. Considering the foundation of thepower industry, the manufacturing industry for power generating equipment and otherrelated industries, it is concluded that China has satisfied the qualifications to develop USCT.

Intelligent and ecological coal mining as well as clean utilization technology in China: Review and prospects

Coal is an essential fossil fuel in China; however, coal mining and its utilization are being under the increasing pressure from ecological and environmental protection. Therefore, the consulting project "Technical Revolution in Ecological and Efficient Coal Mining and Utilization & Intelligence and Diverse Coordination of Coal-based Energy System," initiated by Chinese Academy of Engineering, puts forward three stages(3.0, 4.0 and 5.0) of China's coal industry development strategy. Aimed at "reduced staff,ultra-low ecological damage, and emission level near to natural gas," breakthroughs should be achieved in the following three key technologies during the China Coal Industry 3.0 stage(2016–2025): including intelligent coal mining, ecological mining, ultra-low emission and environmental protection. This paper focuses on the development trends of the China Coal Industry 3.0 and its support for China Coal Industry 4.0 and 5.0 is analyzed and prospected as well, which may offer technical assistance and strategy orientation for realizing the transformation from traditional coal energy to clean energy.

Clean coal technologies in Japan： A review

Coal is the primary fossil fuel most used in the world for the electricity generation, iron making, and cement/concrete and chemical production. However, utilization of coal also results in emissions of CO_2, SO_x, NO_x and other noxious compounds. The development of clean coal technology(CCT) is a main issue to maintain a clean environment. CCT in Japan is considered the highest level in the world. In this review, the developing CCTs in Japan including high efficiency combustion technologies, advanced gasification technologies, CO_2 recovery and utilization technologies, and flue gas cleaning technologies are introduced and discussed. It is expected to provide some new view-of-points for CCT development.

Clean Coal Technologies in China： Current Status and Future Perspectives

Coal is the dominant primary energy source in China and the major source of greenhouse gases and air pollutants. To facilitate the use of coal in an environmentally satisfactory and economically viable way, clean coal technologies （CCTs） are necessary. This paper presents a review of recent research and development of four kinds of CCTs： coal power generation; coal conversion; pollution control; and carbon capture, utilization, and storage. It also outlines future perspectives on directions for technology re search and development （R＆D）. This review shows that China has made remarkable progress in the R＆D of CCTs, and that a number of CCTs have now entered into the commercialization stage.

The view of technological innovation in coal industry under the vision of carbon neutralization

This paper analyzed the current situation and development trends of energy consumption and carbon emissions,and the current situation and development trend of coal consumption in China.In the context of recently established carbon peak and carbon neutralization targets,this paper put forward the main problems associated with the green and low-carbon development and utilization of coal.Five key technological innovation directions in mining were proposed,including green coal development,intelligent and efficient mining,low-carbon utilization and conversion of coal,energy conservation and emission reduction,carbon capture,utilization and storage(CCUS).Focusing on the above technological innovation directions,it is suggested to carry out three basic theories,including the theory of green efficient intelligent mining,clean and low-carbon utilization and transformation of coal,and CCUS.Meanwhile,it is proposed to develop 12 key technologies,including green coal mining and ecological environment protection,efficient coal mining and intelligent mine construction,key technologies and equipment for efficient coal processing,underground coal gasification and mining,ultra-high parameter and ultra-supercritical power generation technology,intelligent and flexible coal-fired power generation technology,new power cycle coal-fired power generation technology,the development of coal-based special fuels,coal-based bulk and specialty chemicals,energy conservation and consumption reduction,large-scale and low-cost carbon capture,CO_(2) utilization and storage.Finally,necessary measures from the governmental perspective were also proposed.

Co-gasification of coal and biomass an emerging clean energy technology: Status and prospects of development in Indian context

Co-gasification of coal and biomass is emerging as potential clean fuel technology to achieve high thermodynamic efficiency with relatively low CO2 emission. The coal and biomass have been exclusively gasified more than a century to obtain gas–liquid fuels and the production of chemicals. Co-gasification has higher efficiency than the solitary coal gasification because the cellulose, hemicellulose and lignin content of biomass help to ignite and enhance the rate of gasification. It is suggested that the extensive research on carbon reactivity pattern, heat release, reaction kinetics, etc. may support to reduce the uncertainties in the co-gasification performance of coal and biomass blends, particularly in India. The prospects of co-gasification technology in Indian context have been discussed considering the abundance of varieties of coal and biomass. The suitability of existing gasifier procedures and their limitations with operating parameters like temperature, residence time, density optimisation, feed rate, agglomeration intensity, the tar formation and techno-economics involved are described. Also, this paper reviews the research highlights of the history of co-gasification and the advancement in upcoming challenges like a design of gasifier, access and preparation of biomass, disposal of residue, environmental concerns and reassurance to the operators for execution of large and small-scale projects.

Progress of the technique of coal microwave desulfurization

With the advantages of its fast speed,effective and moderate controllable conditions,desulfurization of coal by microwave has become research focus in the field of clean coal technology.Coal is a homogeneous mixture which consists of various components with different dielectric properties,so their abilities to absorb microwaves are different,and the sulfur-containing components are better absorbers of microwave,which makes them can be selectively heated and reacted under microwave irradiation.There still remain controversies on the principle of microwave desulfurization at present,thermal effects or non-thermal effects.The point of thermal effects of microwave is mainly base on its characters of rapidly and selectly heating.While,in view of non-thermal effect,direct interactions between the microwave electromagnetic field and sulfur containing components are proposed.It is a fundamental problem to determine the dielectric properties of coal and the sulfur-containing components to reveal the interaction of microwave and sulfur-containing compounds.However,the test of dielectric property of coal is affected by many factors,which makes it difficult to measure dielectric properties accurately.In order to achieve better desulfurization effect,the researchers employ methods of adding chemical additives such as acid,alkali,oxidant,reductant,or changing the reaction atmosphere,or combining with other methods such as magnetic separation,ultrasonic and microorganism.Researchers in this field have also put forward several processes,and have obtained a number of patents.Obscurity of microwave desulfurization mechanism,uncertainties in qualitative and quantitative analysis of sulfur-containing functional groups in coal,and the lack of special microwave equipment have limited further development of microwave desulfurization technology.

Reviews of clean coal conversion technology in China:Situations & challenges

It is important to develop the advanced coal to chemicals industry(ACCI)against a backdrop of coal-based energy structures,excessive imported oil and natural gas,and strict environmental constraints in China.In this study,the technology and industry of China’s ACCI are reviewed to explain the effect of using coal to replace oil and natural gas,and the corresponding resource and environmental burdens that this will create.Development trends in technology and industry are also proposed to explore future scenarios.The review shows that although excellent progress has been made on an industrial scale,demonstrative level,and in terms of technology and equipment,the lack of strategic understanding,severe external constraints,partly underdeveloped technologies,and weak foundations must be immediately addressed.Therefore,it is necessary to clarify the importance that the ACCI has on the energy revolution and energy system.Based on technological innovation,a variety of external factors should be considered as a whole with emphasis on filling the knowledge gap of theoretical foundations and industry standards to support high-quality development for ACCI.

Clean coal geology in China:Research advance and its future

In China,the connection between coal utilization and environmental pollution has been increasingly evident due to the rapid growth in energy consumption.Clean coal technology(CCT)is one of the effective methods to address coal-associated pollution.However,CCT needs the practical and theoretical support of clean coal geology(CCG).In this paper,a new definition of CCG is proposed,based on the definitions of coal,coal geology,and CCT,combined with the development of national CCG.CCG is the discipline comprehensively researching the genesis,nature,distribution,cleaning potential,clean utilization and environmental effects of resources(coal,coal bed methane,and other coal-associated resources)that can be cleaned by CCT.The research content of CCG is discussed from different aspects,such as cleaning potential evaluation,geological guarantee for coal mining,ash yields and sulfur contents,trace elements,pollution caused by coal,and mine reclamation.The progress of CCG in China is also briefly divided into four stages and delineated.Finally,scientific problems in CCG are summarized and an outlook for CCG is given.

Clean Processing and Utilization of Coal Energy

The dominant status of coal on the energy production and consumption structure of China will not be changed in the middle period of this century. To realize highly efficient utilization of coal,low pollution and low cost are great and impendent tasks. These difficult problems can be almost resolved through establishing large-scale pithead power stations using two-stage highly efficient dry coal-cleaning system before coal burning,which is a highly efficient,clean and economical strategy considering the current energy and environmental status of China. All these will be discussed in detail in this paper.

Damage and deterioration mechanism and curing technique of concrete structure in main coal cleaning plants

Concrete structures in main coal cleaning plants have been rebuilt and reinforced in the coal mines of the Shanghai Datun Energy Sources Co. Ltd., the first colliery of the Pingdingshan Coal Co. Ltd. and the Sanhejian mine of the Xuzhou Mining Group Co. Ltd. In these projects, the operating environment and reliability of concrete structures in the main plants of the three companies were investigated and the safety of the structures inspected. Qualitative and quantitative analyses were made on the special natural, technological and mechanical environments around the structures. On the basis of these analyses, we discuss the long-term, combined actions of the harsh natural (corrosive gases, liquids and solids) and mechanical environments on concrete structures and further investigated the damage and deteriorating mechanisms and curing techniques of concrete structures in the main coal cleaning plants. Our study can provide a theoretical basis for ensuring the reliability of concrete structures in main coal cleaning plants.

Effect of a starch-based filter aid on the dewatering of fine clean coal

The dewatering of fine, flotation cleaned coals from Huaibei and Xuzhou (bituminous) and Yongcheng (anthracite) were studied. The supernatant and filter cake were examined to determine the rate and extent of flocculation and dewatering. A starch-based filter aid was used to increase flocculation and dewatering rates. The filtration constant, K, and compression index, s, of the Yongcheng slurry were measured under various conditions. A designed experiment was performed to determine optimum conditions for dewatering. The results showed that the filter aid enhanced flocculation and coagulation of the fine cleaned coal slurry, enhanced the structure of the filter cake and promoted dewatering of the cake. Moisture content in the cake was reduced to 17% after vacuum filtration.