Coal Upgrading Research Articles

Evaluation of a hot oil immersion drying method for the upgrading of crushed low-rank coal

Coal is the most abundant fuel on earth, and low-rank coal (LRC) such as sub-bituminous coal and lignite makes up about half of all coal deposits. LRC is inconvenient to use due to its low caloric value and high content of moisture together with the strong tendency of spontaneous combustion due to these oxygen rich coals, etc. Solving these problems would substantially improve the efficiency of LRC usage. In this study, we describe a drying technique utilizing hot oil immersion. This upgrading process may be executed easily under relatively low temperature condition due to the difference of heat capacity and thereby pressure gradient between coal and heating oil. This results in greatly reducing its energy cost. Drying tests of Indonesian lignite were performed with refined waste oil and B-C heavy oil, which were heated to 120°C, 130°C or 140°C. Following 10 min of treatment, the moisture content of the upgraded coal was improved from 32% to 2.0–3.2%, and its high heating value from 3,000 kcal/kg to 6,000 kcal/kg.

Technological processes of increasing the efficiency of calorific value of coal as the energy resource of the Gacko deposit

This paper describes the conceptual technological processes of coal preparation and processing from the deposit Gacko (Republic Srpska) to the aim of increasing the efficiency of calorific value of fuel for the needs of Thermal Power Plant Gacko.The excavated coal from the coal deposit Gacko is supplied as the energy fuel for the needs od Thermal Power Plant Gacko as well as for commercial consumption. From total output of coal from from the open pit, which annually amounts on average to 2.2 Mt, and 97% is supplied for the needs of Thermal Power Plant Gacko and 3% forcommercial consumption. During previous mining (1983-2012), some deviations were recorded regarded to the results of calorific value of coal, obtained by detailed geological explorations and the results obtained from laboratory analyses on dosers in the Thermal Power Plant Gacko The average calorific value of coal in the deposit Gacko, obtained by geological explorations is 10.2 MJ/kg. The coal deposit Gacko has a complex geological structure and the carbon layers are stratified by substantial numbers of interbeds, thickness of 0.2 to 0.5 m. The selective mining is used for excavation the interbeds of interlayer waste, thickness greater than 0.2 m, and all minor interbeds are mined together with the coal. This technological solution of selective mining does not achieve the optimum economic effects of utilization the carbon material from deposit. The energy fuel of caloricif value from 8 to 8.5 MJ/kg is supplied for the needs of Thermal Power Plant Gacko and and it is lower than the designed parameters for the boiler plant in the Thermal Power Plant Gacko (9.2 MJ kg). Technological methods of coal upgrading and classification would increase the calorific value of coal in relation to the mining conditions.

Reaction Network Elucidation: Interpreting Delplots for Mixed Generation Products

The upgrading and conversion reactions of coal and biomass can involve complex reaction networks involving products formed in several generations from the reactants. The appearance of these “mixed rank” products in the Delplot method for reaction network analysis is examined. Guidelines are developed for the interpretation of network-oriented experimental results intended to resolve such reaction networks.

UJI PENINGKATAN MUTU BATUBARA PERINGKAT RENDAH SUMATERA SELATAN

A study of coal upgrading by way of evaporative method using coal from SouthSumatra is conducted. Preliminary inestigation on Upgrading of Brown Coal(UBC) process using Central and South Banko coals suggests that the processcan be applied to both coals (called S-BK and C-BK) without any operationalproblem. It produces high quality-stable coals in the briquette form with a calorificvalue of more than 6,500kcal/kg. Moreover, its spontaneous combustioncharacteristic is also suppressed comparing to that conventional drying method.This is due to the addition of aspal (heavy oil) in the solution of kerosene, wherethe aspal then soaked in the micropore of to prevent reabsorption of water whenput in the air.Kata Kunci: upgrading brown coal, Banko coal, briket batubara, spontaneouscombustion

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 N 2 or H 2 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 N 2 or H 2 atmospheres. This improves coal caking properties to a certain extent. The upgrading effect under a H 2 atmosphere is remarkably better than the effect observed after upgrading under N 2. Compared to coke obtained from raw coal, the compressive- and micro-strength of the cokes obtained from upgraded coal are greatly improved. The effect on coke reactivity with CO 2 is not significant. The best upgrading temperature for Yi’an gas coal under either a N 2 or H 2 atmosphere is 250 or 275 °C respectively.

Upgrading of low rank coal and woody biomass mixture by hydrothermal treatment

Attempts to produce high-grade fuel from biomass and low rank coal are important from the viewpoint of renewable energy and the utilization of unused resources. In this paper, the authors reported on the hydrothermal treatment of biomass and low rank coal at 300°C using a bench scale continuous apparatus and a batch autoclave. The results show that coalification takes place during the hydrothermal treatment of both the low rank coal and biomass, and the upgraded solid products show similar chemical compositions, gross calorific value and effective calorific value, independent of the mixing ratio. The solid product also becomes hydrophobic and unable to re-adsorb the lost moisture. The characteristics of the solid produced by the bench scale continuous apparatus can be predicted by the results of the batch process. Thermogravimetric analysis shows that the solid product has a wide-range of molecular weight but the thermally stable heavy molecules are found more in the treated coal as opposite to the thermally unstable light molecules, more of which are found in the treated biomass. This may correlate with that the solid product of higher biomass mixing ratio has a higher volatile matter content. Polymerization is synergistically promoted during mixed hydrothermal treatment of low rank coal and biomass.

1-4-3 Upgrading of Low Rank Coals Using Degradative Solvent Extraction at around 350°C

1-4-3 Upgrading of Low Rank Coals Using Degradative Solvent Extraction at around 350°C

Conversion of a Wide Range of Low-Rank Coals into Upgraded Coals and Thermoplastic Extracts Having Similar Chemical and Physical Properties Using Degradative Hydrothermal Extraction

We have recently presented a method that converts low-rank coal into upgraded coal and thermoplastic extract through the hydrothermal degradative extraction in a flow of hot water at less than 350 °C. To examine the validity of the presented method and to characterize the upgraded coals and the thermoplastic extracts obtained in more detail, seven kinds of low-rank coals, a biomass, an O-methylated brown coal, an oil rock, and a bituminous coal were subjected to the hydrothermal degradative extraction at either 300 or 350 °C. The elemental compositions of the upgraded coals were found to be rather close to each other, and their carbon and oxygen contents were larger than 71% and less than 23%, respectively, meaning that the heating values are well over 30 MJ/kg on a dry ash-free (daf) sample basis. The solid extracts (deposits) obtained at 350 °C from the variety of samples were very close to each other in elemental composition, molecular-weight distributions, pyrolysis behavior, and softening/melting beh...

Development of Upgrading Method of Low Rank Coal for its Utilization in Cokemaking Process

Japanese steel industries, which are importing all coal resources required, are facing the necessity of increasing usable coal resources. They are to increase the kinds and amounts of usable coal and to develop the technologies for upgrading low rank coals such as subbituminous coal and brown coal as substitutes. In this work we have developed methods for upgrading brown coal. The methods involve the fractionation of brown coal using sequential thermal solvent extraction, dewatering and upgrading of brown coal using hydrothermal treatment, and co-pyrolysis of upgraded brown coal and plastic derived wax. The fractionation method successfully fractionated an Australian brown coal into six fractions, some of which are expected as binders for cokemaking because of their thermal plasticity. The hydrothermal upgrading/extraction method can not only removes water from brown coal but also separates the coal into extract of low molecular mass compounds and upgraded coal having lower hydrophilicity and spontaneous combustibility and higher calorific value than the raw coal. Addition of the upgraded coal to the coking coals was found to enhance the gasification reactivity of the resulting coke. Co-pyrolysis of the upgraded coal and waxes formed from waste plastics was also investigated as one of the methods for further upgrading the hydrothermally upgraded coal. It was found that the waxes effectively removed oxygen atoms from the upgraded coal and tended to be retained as a solid carbon in the coke through co-pyrolysis. It is shown that these methods enable to produce binders for cokemaking and substitute of slightly/noncaking coal.

Discussion of the indexes of nonoutburst coal seam upgrade and its corresponding critical value

In view of the measurement difficulties of indexes recommended by the 50 Items Experience of Coal Mine Gas Prevention in the process of the nonoutburst coal seam upgrade, this paper took the No.8 coal seam of Huainan Mining Group as research object. Discussed the suitability of indexes and corresponding critical values, put forward method in determining the indexes and its critical values by analysis and investigation of the gas geological condition and the-spot tracking near position where an outburst occurred combined with laboratory experiment, and established the indexes and its critical values of nonoutburst coal seam upgrade in No.8 coal seam of Huainan Mining Group. The results show that it is suitable to take gas content and tectonic soft coal thickness easily to gain in routine production as primary upgrade indexes that its critical values are 7.5 m3/t and 0.8 m, respectively. In addition, take f value and Δp value as auxiliary indexes.

Low Rank Coal Upgrading in a Flow of Hot Water

Simultaneous hydrothermal degradation and extraction at around 350{sup o}C using flowing solvent as a reaction/extraction medium were proposed for upgrading brown coal, more specifically, for converting brown coal into several fractions having different molecular weight and chemical structure under mild conditions. When an Australian brown coal, Loy Yang coal, was treated by water at 350{sup o}C under 18 MPa, the coal was separated into four fractions: gaseous product by 8% yield, water-soluble extract at room temperature (soluble) by 23% yield, extract precipitates as solid at room temperature (deposit) by 23% yield, and residual coal (upgraded coal) by 46% yield on daf basis. The separation was found to be realized by in situ extraction of low-molecular-weight substances released from coal macromolecular structure and/or those generated by hydrothermal decomposition reactions at 350{sup o}C. The solid products obtained, deposit and upgraded coal, were characterized in detail to examine the possibility of their effective utilization as solid fuel and chemical feed stock. The upgraded coal showed higher heating value and higher gasification reactivity than the parent coal, indicating that the upgraded coal can be a better solid fuel than the parent coal. The solid extract, deposit, was found to show thermoplasticity at less thanmore » 200{sup o}C, suggesting the possibility of utilizing the deposit as a raw material of high performance carbon materials. Several variables affecting the performance of the proposed method are also examined in detail in this paper. 12 refs., 8 figs., 3 tabs.« less

1-6-3 ガス化反応性向上のための低品位炭の改質(1-6 ガス化・改質,Session 1 石炭・重質油等,研究発表)

1-6-3 ガス化反応性向上のための低品位炭の改質(1-6 ガス化・改質,Session 1 石炭・重質油等,研究発表)

1-6-4 穏和な溶剤処理を利用した低品位炭の改質(1-6 ガス化・改質,Session 1 石炭・重質油等,研究発表)

1-6-4 穏和な溶剤処理を利用した低品位炭の改質(1-6 ガス化・改質,Session 1 石炭・重質油等,研究発表)

Emission Control of Mercury and Sulfur by Mild Thermal Upgrading of Coal

Mercury and sulfur emissions from power plants is becoming increasingly an environmental concern. In this study, two Chinese coals from the Guizhou province and one Canadian coal from Alberta were selected to study the potential of thermal upgrading as mercury and sulfur emission control strategy prior to coal use. A low-temperature asher (LTA) and X-ray diffractometer (XRD) were used to characterize the occurrence of mercury and sulfur in coal. An experiment of mild thermal upgrading at different atmospheres was performed to explore the removal efficiencies of mercury before combustion. Our study shows that mercury is associated with different minerals in these coal samples. The correlation between mercury and sulfur is also investigated. Mercury was found to be removed effectively by mild thermal upgrading at 400 °C under a 4% O2−N2 atmosphere. An oxidizing atmosphere increased the removal of pyritic sulfur significantly at low temperatures. The mercury release rate was found to be higher under an oxidizing atmosphere than under a nitrogen atmosphere between 300 and 400 °C during mild thermal upgrading.

Effect of dispersing and stabilizing additives on rheological characteristics of the upgraded brown coal water mixture

Upgraded brown coal water mixture (UBCWM) preparation by using an Indonesian upgraded coal produced by upgraded brown coal (UBC) process, was carried out to study the effect of dispersing and stabilizing additives on rheological behavior of the UBCWM. Three kinds of anionic dispersing additives, naphthalene sulfonic formaldehyde condensate (NSF), poly (meth) acrylate (PMA) and poly styrene sulfonic acid (PSS) and three kinds of stabilizing additives, carboxyl methyl cellulose (CMC), rhansam gum (S-194) and gellan gum (S-60) were used in this study. Results indicate that the addition of NSF 0.3 wt.% together with S-194 0.01 wt.% is effective in preparing UBCWM with good slurryability and stability, based on its rheological characteristics with the apparent viscosity at shear rate of 100 s − 1 and yield stress at zero point of shear rate. The rheological behavior of all of the UBCWM that prepared, exhibits non-Newtonian Bingham plastic. From the economical point of view, the price of S-194 is expensive. On the other hand, CMC is cheap and abundant. Therefore, the addition of CMC 0.01 wt.% together with NSF 0.3 wt.% is also effective in preparing UBCWM with good fluidity and stability.

9 溶剤中での熱処理を利用した低品位炭の改質(改質・処理・クリーン化(1))

9 溶剤中での熱処理を利用した低品位炭の改質(改質・処理・クリーン化(1))

Hydrothermal upgrading of Loy Yang Brown coal — Effect of upgrading conditions on the characteristics of the products

Hydrothermal treatment of the high-moisture containing (59%) Loy Yang brown coal was conducted in a 20 ml stainless steel autoclave at 200 to 350 °C for 30 and 180 min. Three treatment methods were employed: 1) conventional method (i.e., extra water was added before treatment); 2) as-received method (i.e., treatment without addition of extra water); and 3) separation method (i.e., treatment with physical separation of water and solid). Treatment using the as-received method revealed that hydrothermal conditions can be maintained in the autoclave without addition of extra water. Upgrading using the separation method yielded more effective drying especially during treatment at 350 °C, where the water content was reduced to 6%. Treatment above 250 °C led to progressive lower water content, increasing carbon and decreasing oxygen content. Calculations of the calorific values of the upgraded coals showed that hydrothermal treatment at 300 and 350 °C led to a net increase in the calorific value compared to the raw coal. Reductions in the volatile content and the changes in the physical properties of the upgraded coals significantly reduced self-ignition tendencies of the coal treated above 300 °C.

Slurry Dewatering Process to Improve Quality of Low Grade Coal

The upgrading Kalimantan low rank coal is performed using slurry dewatering process in a stirred batch autoclave (inner volume of 5 liters) equipped with a condenser, a pressure control valve (PCV), and a receiver. The experiment is carried out at 3.5 kg/cm2G nitrogen pressure, 250oC heater temperature and 150 rpm agitator speed. Kerosene and low sulfur waxy residue (LSWR) are used as oil solvents. The fluidity of slurry is studied with the ratio of oil to coal (O/C) at 1.5 to 2 wt/wt and the concentration of LSWR at 0.5 to 2% in oil. The temperature profile during operation is evaluated to investigate the process performance. Moreover, pH, TSS and TDS contents in water product is also analyzed. A centrifuge separator (cap. 200 gram, 1000 rpm) is used to remove oil in coal slurry, and it is found that almost all added oil can be recovered. The study suggests that calorific value of upgraded coal (as received basis) increases sharply from 5,178 kcal/kg to 7342 kcal/kg, following drastic reduction in total moisture, from 25,5% to 4,97%. The contents of ash, volatile matter and elements do not change very much from that of raw coal. This phenomenon shows that no chemical reaction occurs in the process. The wastewater from the process is clean enough thereby a simple wastewater treatment is required in commercial plant. Re-absorption test shows that stable moisture content in coal is achieved at 7.5 wt% for 13 days. The temperature profile suggests that the slurry dewatering process can be applied effectively to Kalimantan low rank coals producing excellent upgraded coal characteristics.

Mercury Removal Characteristics during Thermal Upgrading of Fractionated Alberta Subbituminous Coal

In response to mercury emission control from coal combustion flue gases, coal cleaning and thermal upgrading are being considered as precombustion mercury emission control options. In our previous study, dry coal cleaning using an air dense medium fluidized bed (ADMFB) was shown to reject a substantial fraction of mercury in original coal while retaining acceptable combustible recovery. In this study, mercury removal characteristics by thermal upgrading were studied using Alberta subbituminous coals fractionated by a air dense medium fluidized bed (ADMFB). It was found that the bottom 28% of the run-of-mine coal cleaned by ADMFB separator contained over 57% ash-forming mineral matters and 46% mercury. Mercury removal from this fraction of coal increased rapidly at temperatures over 206–329 °C. During thermal upgrading, the mass of coal decreased and the calorific values increased with increasing upgrading temperature. The observed weight loss and increase in the calorific value of upgraded coal at temperatures between 106 and 329 °C were attributed mainly to the evaporation of moisture which does not contribute to calorific value, with a small amount to the loss of combustible volatiles.

Hydrothermal extraction and hydrothermal gasification process for brown coal conversion

A novel coal conversion process was proposed: the method combines “a hydrothermal extraction of brown coal (HT-Extraction)” and “a catalytic hydrothermal gasification of the extract (CHT-Gasification)” both of which are performed under the exactly same conditions of less than 350 °C and less than 20 MPa. Organic compounds in the aqueous phase, extracted from brown coal, was gasified using a novel Ni-supported carbon catalyst developed by the authors, producing combustible gas rich in CH 4 and H 2. Through this process performed at 350 °C and 18 MPa, an Australian brown coal was almost perfectly converted into 53% of upgraded coal, 23% of methane, and 24% of carbon dioxide on carbon basis. Simultaneously, 4.4 mol of hydrogen was generated from 100 mol of carbon of the coal. This process transferred 97% of energy involved in the raw coal to the products, indicating its effectiveness.