Value Of Lignite Research Articles

Effect of low-temperature oxidation of coal with different metamorphic degrees on coal quality characteristics and outburst comprehensive index

Outburst prevention and control measures such as protective seam mining and coal seam gas pre-drainage can cause low-temperature oxidation of coal seam, and there is a lack of research on the changes in coal quality characteristics and outburst comprehensive index during low-temperature oxidation. In this paper, the changes of coal quality characteristic indexes during oxidation of coals with different metamorphic degrees, the initial gas emission velocity and the firmness coefficient were measured, the influence of coal quality characteristics on outburst comprehensive index is studied, and the change of outburst comprehensive index K=Δpf in the low-temperature oxidation process was analyzed. The results show that for coal with different metamorphic degrees, the coal with a lower metamorphic degree enters the stage of inherent moisture evaporation later and is more likely to undergo decomposition and volatilization of volatile matters. In the midterm of low-temperature oxidation (120–160°C), the growth rates of △p values and the decline rates of f values of coal samples with higher metamorphic degrees tend to decrease. It can be known that the K value of bituminous coal and anthracite are more than 25 during the whole oxidation heating stage, which shows a serious outburst risk. For these coals, effective outburst prevention measures must be taken to prevent outburst risk and inhibit coal spontaneous combustion. In contrast, for lignite coal, the growth rate of △p value and the decline rate of f value keep increasing in the midterm of low-temperature oxidation, due to the joint action of moisture evaporation and volatile decomposition and volatilization. The K value of Lignite is more than 15 when oxidation temperature rises to 150 °C, which shows a general outburst danger. According to the analysis results in the midterm, appropriate measures must be taken to inhibit coal oxidation when local or overall temperature of coal seam reaches 130 °C.

External Costs of Opencast Brown Coal Mining in Agriculture and Agri-Food Industry (on the Example of Wielkopolska)

Abstract The aim of the work was to analyse the external costs for agriculture and agri-food industry related to the possible launch of lignite deposits in Wielkopolska, that is, on the Ościsłowo, Dęby Szlacheckie and Oczkowice deposits. The duration of the mine’s impact on the environment includes the period of drainage of the deposit, its exploitation and the time necessary for the reconstruction of water relations around the open pit. The level of losses in agricultural production was estimated based on the production results achieved by agriculture threatened by the occurrence of external costs based on the Central Statistical Office (CSO) data. The studies adopted two variants of the impact of open pitches on agriculture, including: the area of the estimated depression hopper, that is, the area in which the water table lowered by at least one meter and the entire impact area of the outcrop. In total, the external costs in agricultural production and processing, which may arise as a result of the launch of extraction from the three analysed deposits, were estimated at PLN 7.7–32.3 bn, losses in non-produced agricultural production at PLN 31.8–113.0 bn, while when the value of lignite is PLN 83.7–111.6 bn. Such high costs mean that the opening of new lignite deposits in Wielkopolska raises economic doubts. This also applies to each deposit separately.

The preparation of composite solid fuels in the roll press

Directive 2009/28/EC of the European Parliament and of the Council of 23 April 2009 on the promotion of the use of energy from renewable sources and amending and subsequently repealing Directives 2001/77/EC and 2003/30/EC, and the annex to resolution 202/2009 of the Council of Ministers of 10 November 2009 on the energy policy of Poland until up to 2030 indicate the necessity of increasing the contribution of renewable fuels in the energy balance of Poland. This increase is supposed to strengthen Polish energy security. The undertakings of the Polish government indicate the increase in utilisation of various renewable energy sources such as biomass. Due to that, new technologies connected with the management of the traditional energy sources, such as lignite, have to be developed. Due to its high moisture, lignite is perceived as a lowefficiency fuel. The calorific value of lignite can be improved upon by mixing it with biomass, e.g. sawdust, and briquetting it in roll presses equipped with asymmetrical layout compacting system. Such technology can be used only if the mixed ingredients are adequately prepared beforehand. Research in this field has been conducted in the Department of Manufacturing Systems AGH University of Science and Technology in Cracow. Based on this research, PW 500 roll press design was prepared. PW 500 roll press is prepared for briquetting composite solid fuels based on a mixture of lignite extracted in Szczerców and two types of biomass: oat straws and spruce sawdust. The results of the aforementioned briquetting are presented in this article.

저품위 석탄의 원지반에서의 생물학적 메탄가스 생산에 관한 기초연구

In the present work, a basic study on the in-situ biogenic methane generation from low grade coal bed was conducted. Lignite from Indonesia was used as a sample feedstock. A series of BMP (Biochemical Methane Potential) tests were carried out under the different experimental conditions. Although nutrients and anaerobic digester sludge were added to the coal, the produced amount of methane was limited. Both temperature control and particle size reduction showed little effect on the increase of methane potential. When rice straw was added to lignite as an external carbon source, methane yield of 94.4~110.4 mL/g VS was obtained after 60 days of BMP test. The calorific value of lignite after BMP test decreased (4.5~12.1 %) as increasing the content of rice straw (12.5~50 wt % of lignite), implying that anaerobic digestion of rice straw led to partial degradation of lignite. Therefore, rice straw could be used as an external carbon source for the start-up of in-situ biogas generation from low grade coal bed.

Evaluation of changes in macerals and geochemical properties during hydrocarbon generation based on pyrolysis of lignite from Mainland China

In this study, we adopted thermal simulation to explore the changes of macerals compositions and trace elements in the coal oil processing. Using lignite for the thermal simulation, the changes of various parameters and trace elements in the thermal evolution were explored. The experimental results showed that the content of vitrinite decreased gradually with increasing thermal maturity, where both types of macerals components were developing into inertinite, mainly fusinite and semifusinite. The Pr/Ph value of lignite has decreasing trend under the thermal maturation process. Trace elements that have catalytic effect are Cr, Cu, and Zn; the relative contents of the three trace elements all have increasing trend with rising thermal maturation evolution. Lignite at simulated temperature of 350 °C has the highest yield of oil and gas. When Ro% is approaching nearly 1.37, there is better yield of oil and gas. From the simulations, it is known that the critical temperature of the lignite is near 350 °C and its corresponding Ro% is 1.37. The changes in the relative contents of the catalytic trace elements (Zn, Cu, Cr) and yield performance of oil and gas, approaching 350 °C temperature will be a turning point of thermal maturation.

Measuring Dependence between Calorific Values of Lignite and Spatial Positions by Rank Correlation Method: A Case Study

This article presents an investigation for evaluating the relationship between calorific value of lignite and its spatial position using non parametric statistics. Measuring dependence between calorific values and spatial positions is important for production planning and making decisions. For this purpose, a three dimensional data set (easting-x, northing-y, and elevation-z) obtained from Afsin-Elbistan lignite deposit is employed. Rank correlation measurements have been carried out between spatial dimensions and calorific values. In addition, the significances of rank correlation coefficients have been appraised using hypothesis tests. As a result of the study, a strong rank correlation between y and calorific values and a weak rank correlation between z and calorific values are observed, respectively. On the other hand, very low-rank correlation between coordinate x and calorific values is measured for the deposit.

Appraising Lignite Quality Parameters by Linguistic Fuzzy Identification

Lignite quality parameters have had central importance for power plants. This article addresses a comparative study on fuzzy and regression modeling for estimating the calorific value of lignite, which is one of the quality parameters from the other parameters: moisture, ash, volatile matter, and sulphur content. For the estimations, data driven models were designed based on linguistic fuzzy modeling structures. In addition, estimations of the fuzzy models were compared with linear regression estimations. The great majority of performance evaluations showed that the fuzzy estimations are very satisfactory in estimating calorific value of lignite.