Effects of Processing Temperature of Hot Water Drying on the Properties and Combustion Characteristics of an Indonesian Low Rank Coal

Umar, Datin Fatia; Usui, Hiromoto; Daulay, Bukin

doi:10.1080/07349340500444554

Cited by 21 publications

(16 citation statements)

References 8 publications

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“…The temperature of the superheated steam for tests in the present examination ranged from 110 to 170 o C. It was assumed that below 180 o C volatilization and decomposition of carbon functional groups do not occur (Umar et al, 2005). Therefore, any changes of weight during drying should be assigned only to evaporation of water from the coal.…”

Section: Methodsmentioning

confidence: 99%

Comprehensive study on the kinetics and modelling of superheated steam drying of Belchatow lignite from Poland

Zakrzewski

Komatsu

Ściążko

et al. 2016

Mechanical Engineering Journal

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In the modern fuel mix, the leading positions are occupied by hard coal and crude oil, both accounting for around 35% of annual mined energy content (Andruleit et al., 2012). With a 2% share, lignite does not compete with the former two in the global perspective. However, easy accessibility and low production costs ensure its important role in the energy policies of particular countries worldwide. Utilization of this energy carrier is limited, though, due to the water content often exceeding 50% of raw mass. High moisture content negatively affects calorific value and precludes transportation and storage. So, lignite is less advantageous than hard coal in terms of utilization in the power generation industry. On the other hand, the usage of lignite is also considered for a wide range of applications, including coking or briquetting, and considerable volatile matter content makes it a prospective fuel for gasification purposes. Thus, the efforts made to upgrade its quality seem justified.The removal of water, contributing to increase in thermal efficiency of lignite-fired power plants, can be performed by a variety of methods, separated into evaporative thermal drying, non-evaporative thermal drying and other Marcin ZAKRZEWSKI* , **, Yosuke KOMATSU***, Anna SCIAZKO*, Taro AKIYAMA***, Akira HASHIMOTO***, Naoki SHIKAZONO***, Shozo KANEKO***, Shinji KIMIJIMA** , ***, Janusz S. SZMYD* and Yoshinori KOBAYASHI*** AbstractLow calorific value of lignite, mostly attributed to high moisture content, undermines usability of this low rank coal. Upgrading the quality of this energy carrier, which benefits coal-fired power plant's thermal efficiency, can be effectively realized by means of drying. The kinetics of superheated steam drying was studied for 30 mm spherical samples from Belchatow lignite mine in Poland. The experiment featured simultaneous and continuous measurements of weight and temperature. The drying kinetics, described by curves of moisture content, drying rate and temperature profile, were evaluated using the data acquired. The appearance of the sample throughout the process was video-recorded. Widespread cracking and shrinkage, which differ depending on the conditions, along with series of droplets typical for larger sample, were observed. The examined particles were suitable for predictions of thermodynamically derived drying rate and time, as proposed in the previous study for 5 and 10 mm particles from the same coal deposit. However, in comparison they exhibited more uniform density distribution. On the basis of experimental results and material properties, the numerical model of drying process was applied. Simulated drying behavior was consistent with empirical observations. Extensive investigation, revealing features of variously-sized samples as well as diameter dependence on drying process, is required for purposes of designing industrial drying system dedicated to specific type of coal.

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Section: Methodsmentioning

confidence: 99%

Comprehensive study on the kinetics and modelling of superheated steam drying of Belchatow lignite from Poland

Zakrzewski

Komatsu

Ściążko

et al. 2016

Mechanical Engineering Journal

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“…As the drying temperature is maintained under 180˝C, it is assumed that volatilization and the decomposition of functional groups are not occurring [24,25]. Thus, it can be assumed that the change in the weight is caused by moisture removal.…”

Section: Methodsmentioning

confidence: 99%

Experimental Attempts to Investigate the Influence of Petrographic Properties on Drying Characteristics of Lignite in Superheated Steam Atmosphere

et al. 2016

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A superheated steam fluidized bed dryer (SSFBD) in a self-heat recuperative configuration has a great potential of improving thermal efficiency of a lignite-fired power plant by recovering both of latent heat of vaporization of water kept in the fuel and part of sensible heat during the fuel processing. However, the optimal design of the dryer requires the fundamental knowledge of drying characteristics in respect to the individual properties of the utilized fuel. Experimental investigation to determine the correlation between a specific coal properties originated from geological background and its drying characteristics is thus the major concern in this paper. The investigated lignite is a representative of Turoszow deposit in Poland. Experimental attempts unveiling drying kinetics were carried out for 5 mm and 10 mm diameter spherical samples in the superheated steam atmosphere in the temperature range of 110˝C-170˝C. Simultaneous and continuous measurements of changes in weight, surface and interior temperatures and appearance on each tested sample were carried out for describing drying behavior. Analytical investigation was applied to explain the drying characteristics, which are strongly affected by the individual properties of coal and the inherent ash composition.

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“…The assumptions of water condensation and coal volatilization limited the temperature range from the bottom and top, respectively. The decomposition of lignite structure was not observed [17] below 180°C, hence the water removal is treated as an exclusive reason for the descent of the sample weight.…”

Section: Setup and Proceduresmentioning

confidence: 99%

Numerical analysis of single and multiple particles of Belchatow lignite dried in superheated steam

et al. 2018

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Low production costs have contributed to the important role of lignite in the energy mixes of numerous countries worldwide. High moisture content, though, diminishes the applicability of lignite in power generation. Superheated steam drying is a prospective method of raising the calorific value of this fuel. This study describes the numerical model of superheated steam drying of lignite from the Belchatow mine in Poland in two aspects: single and multi-particle. The experimental investigation preceded the numerical analysis and provided the necessary data for the preparation and verification of the model. Spheres of 2.5 to 30 mm in diameter were exposed to the drying medium at the temperature range of 110 to 170°C. The drying kinetics were described in the form of moisture content, drying rate and temperature profile curves against time. Basic coal properties, such as density or specific heat, as well as the mechanisms of heat and mass transfer in the particular stages of the process laid the foundations for the model construction. The model illustrated the drying behavior of a single particle in the entire range of steam temperature as well as the sample diameter. Furthermore, the numerical analyses of coal batches containing particles of various sizes were conducted to reflect the operating conditions of the dryer. They were followed by deliberation on the calorific value improvement achieved by drying, in terms of coal ingredients, power plant efficiency and dryer input composition. The initial period of drying was found crucial for upgrading the quality of coal. The accuracy of the model is capable of further improvement regarding the process parameters.Keywords Superheated steam drying . Low-rank coal .

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Effects of Processing Temperature of Hot Water Drying on the Properties and Combustion Characteristics of an Indonesian Low Rank Coal

Cited by 21 publications

References 8 publications

Comprehensive study on the kinetics and modelling of superheated steam drying of Belchatow lignite from Poland

Comprehensive study on the kinetics and modelling of superheated steam drying of Belchatow lignite from Poland

Experimental Attempts to Investigate the Influence of Petrographic Properties on Drying Characteristics of Lignite in Superheated Steam Atmosphere

Numerical analysis of single and multiple particles of Belchatow lignite dried in superheated steam

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