Research progress and prospects of coal petrology and coal quality in China

Clean utilization of coal depends on the quality of raw coal,which depends on the coal-forming parent materials(petrology and chemical composition of coal),the multiple media of the coal-forming environment,and some epigenetic conditions,such as thermal evolution(coalification),magmatic hydrothermal fluid,groundwater.Based on the research results of predecessors and prediction studies of coal resources since the founding of China,the present status of research on coal petrology,coal quality,coal metamorphism,and coal geochemistry in China is discussed in detail,with emphasis on research progress and the general situation of highly efficient and clean utilization of coal in the technical fields of coking,pyrolysis,combustion,gasification,and liquefaction,and the development prospects of coal petrology and coal quality in China are prospected.

COAL QUALITY CONTROL

Coal storing and loading have much more influence on coal quality. In the paper, a goal programming model has been constructed to determine the ideal quantity extracting from stockpile and silos and a quality control model is inferred under the guidance of maximum theory of dispersed number and practice methods are given to meet production demand, with which a coal mine has achieved a better tech-economic result.

THE OPTIMUM MODEL AND ITS DECISION SUPPORT SYSTEM OF COAL QUALITY BALANCE

The meaning and significance of coal quality balance are summaized in this paper.Practical steps concerning constructing the synthetic tech-economic model and its decision support system of coal quality balance using the optimization techology of inverse recurrence of established initializing parameters are also introduced. The principles and methods as being applied in the model system development and procedure construction are discussed accordingly.

Recent progress on laser-induced breakdown spectroscopy for the monitoring of coal quality and unburned carbon in fly ash

Our recent progress on developments of laser-induced breakdown spectroscopy （L[BS） based equipments for on-line monitoring of pulverized coal and unburned carbon （UC） level of fly ash are reviewed. A fully software-controlled LIBS equipment comprising a self-cleaning device for on-line coal quality monitoring in power plants is developed. The system features an automated sampling device, which is capable of elemental （C, Ca, Mg, Ti, Si, H, Al, Fe, S, and organic oxygen） and proximate analysis （Qad and Aad） through optimal data processing methods. An automated prototype LIBS apparatus has been developed for possible application to power plants for on-line analysis of UC level in fly ash. New data processing methods are proposed to correct spectral interference and matrix effects, with the accuracy for UC level analysis estimated to be 0.26%.

The Optimum Model and Its Decision Support System of Coal Quality Balance

The meaningfulness and significance of coal quality balance have been summarized in this paper and practical steps concerning constructing the synthetic tech\|economic model and its decision support system of coal quality balance using the optimization technique of inverse recurrence of established initializing parameters have also been introduced. The principles and methods as applied in the model system development and procedure construction have been discussed accordingly.

RESEARCH ON THE QUALITY PRICE RATIO OF COKING COAL

If assortment priee parity of Clase coking coal and its qtalty price danrcnee is nonreasonable, it deren't gulde in Anprotrig tbe quallry metaliurgical coking coal and may be influence theeconomic benefit of metallurgical enterprises. This paper propose the principles and mathematicmodel for determination aseortment party of clean cokingcoal and its quality difference of ash content in clean coking coal in order to urge wasbenes into producing superior clean coking cleal whichis under condition of consideration both interest waskeries and interest metallurgicai industry. It canbe used as a method in theory to make price strategies under condition of socialism maket economicfor washeries of clean coking coal

Prediction on adsorption ratio of carbon dioxide to methane on coals with multiple linear regression

The multiple linear regression equations for adsorption ratio of CO2/CH4 and its coal quality indexes were built with SPSS software on basis of existing coal quality data and its adsorption amount of CO2 and OH4. The regression equations built were tested with data collected from some s, and the influences of coal quality indexes on adsorption ratio of CO2/CH4 were studied with investigation of regression equations. The study results show that the regression equation for adsorption ratio of CO2/CH4 and volatile matter, ash and moisture in coal can be obtained with multiple linear regression analysis, that the influence of same coal quality index with the degree of metamorphosis or influence of coal quality indexes for same coal rank on adsorption ratio is not consistent.

Correlation between coal characteristics and methane adsorption on China＇s coals

It is highly important to investigate relationship between coal characteristics and methane adsorption on coal in the fields of coalbed methane recovery. Based on data examination of coal quality indexes collected from the literatures, regression equations for Langmuir adsorption constants, VL or VLIPL, and coal quality indexes for selected coal samples were developed with multiple linear regression of SPSS software according to the degree of coal metamorphosis. The regression equations built were tested with data collected from some literatures, and the influences of coal quality indexes on CH4 adsorption on coals were studied with investigation of regression equations, and the reasons of low accuracy to Langmuir constants calculated with regression equation for a few coal samples were investigated. The results show that the regression equations can be employed to predict Langmuir constants for methane adsorption isotherms on coals obtained using volumetric gas adsorption experiments, which are conducted at 30 ℃ on a wet or dried coal samples with less than 30% ash content in coal. The influence of same coal quality index with various coal rank or influence of various coal quality indexes for same coal rank on CH4 adsorption is not consistent. The regression equations have different accuracy to different coal rank, in which the VL equations supply better prediction accuracy for anthracite and higher prediction error for lower metamorphosis coal, and the PL prediction error with VL and VL/PL equations is lower to bituminous coal and higher to anthracite.

Comparative Experimental Analysis on Coal Spontaneous Combustion

The goal of this study was to investigate coal quality features and their relationship to coal spontaneous combustion characteristics in multi-seam coal mines to better predict when coal spontaneous combustion is likely to occur.To that end,coal samples of various particle sizes were obtained from five coal seams(Nos.6,8,9,12 and 20)in the Shuangyashan City Xin’an Coal Mine.The samples were then respectively heated using a temperature programming system to observe and compare similarities and differences in the sponta-neous combustion process of different particle sizes in response to rising temperature.The experimental results show,that in all five coal seams,the concentration of CO,C_(2)H_(4),and C_(2)H_(6) increased with a certain degree of regularity as a function of rising temperature.However,of these three gasses,only CO and C_(2)H_(4) can be used as indicators to predict coal mine spontaneous combustion.The critical temperature for samples from all five coal seams ranged from 50–85℃,while the dry cracking temperature of coal seams 8 and 12(80–100℃)were lower than those of 6,9,and 20(100–120℃).Furthermore,the production rate of CO,C_(2)H_(4),and C_(2)H_(6) is related to both coal particle size and temperature.The smaller the particle size,the faster the production rate;and the higher the temperature,the more gas that gets produced.All five coal seems are mainly com-posed of long flame coal.However,they differ in that the No.12 coal seam contains weak cohesive coal;the No.8 coal seam contains lean and gas coal;and the Nos.6,9,and 20 coal seams contain a certain amount of anthracite.During the programmed coal heating,the CO,C_(2)H_(4),and C_(2)H_(6) release trend for the coal seams was No.12>No.8>Nos.6,9,and 20.These results demonstrate that the presence of weak cohesive coal and anthracite highly influence the concentration of CO,C_(2)H_(4),and C_(2)H_(6) released during coal spontaneous combustion.

Upgrading of Yi'an gas coal by low temperature pyrolysis under different atmospheres

The quality of Yi＇an gas coal before and after low temperature upgrading under either a N2 or H2 atmosphere was examined by thermogravimetric and infrared analyses. The effect of upgrading on the prepared coke quality was analyzed. The results show that the carboxyl and phenolic hydroxyls in the coal molecular structure are removed after upgrading by low temperature pyrolysis under either N2 or Hz atmospheres. This improves coal caking properties to a certain extent. The upgrading effect under a Hz atmosphere is remarkably better than the effect observed after upgrading under N2. Compared to coke obtained from raw coal, the compressiveand micro-strength of the cokes obtained from upgraded coal are greatly improved. The effect on coke reactivity with CO2 is not significant. The best upgrading temperature for Yi＇an gas coal under either a N2 or H2 atmosphere is 250 or 275 ℃ respectively.

山东省单县煤田张集井田3煤层煤质特征及工业利用方向

山东省单县煤田张集井田主采煤层为3煤,该煤层结构简单,煤质优良,为低灰、低硫、强黏结性、成焦率较高的焦煤(JM25),次为肥煤(FM26)和1/3焦煤(1/3JM35),是山东省稀缺的优质炼焦用煤。煤质的综合研究表明,为达到珍惜和合理利用资源,并使其效益最大化,该煤层应以冶金和铸造用焦为主要加工利用方向。

Review of methodological and experimental LIBStechniques for coal analysis and their application in power plants in China

Laser-induced breakdown spectroscopy (LIBS) is an emerging analytical spectroscopy technique. This review presents the main recent developments in China regarding the implementation of LIBS for coal analysis. The paper mainly focuses on the progress of the past few years in the fundamentals, data pretreatment, calibration model, and experimental issues of LIBS and its application to coal analysis. Many important domestic studies focusing on coal quality analysis have been conducted. For example, a proposed novel hybrid quantification model can provide more reproducible quantitative analytical results; the model obtained the average absolute errors (AREs) of 0.42%, 0.05%, 0.07%, and 0.17% for carbon, hydrogen, volatiles, and ash, respectively, and a heat value of 0.07 MJ/kg. Atomic/ionic emission lines and molecular bands, such as CN and C-2, have been employed to generate more accurate analysis results, achieving an ARE of 0.26% and a 0.16% limit of detection (LOD) for the prediction of unburned carbon in fly ashes. Both laboratory and on-line LIBS apparatuses have been developed for field application in coal-fired power plants. We consider that both the accuracy and the repeatability of the elemental and proximate analysis of coal have increased significantly and further efforts will be devoted to realizing large-scale commercialization of coal quality analyzer in China.