Cleaning of Pakistani low-grade coal by agglomeration

This study was carried out for the beneficiation of Dukki (Pakistani) coal using agglomeration technique. The effect of six parameters, particle size, solid to liquid ratio, xylene concentration, agitation speed, agitation time, and pH, was investigated to improve the quality of coal in terms of reduced ash and sulfur content. The clean coal obtained at optimum parameters was found to have 69.25 and 26.6% reduction in ash and sulfur, respectively. The gross calorific value (GCV) increased to 6,377 kcal/kg compared with 5,300 kcal/kg in the original sample. A maximum reduction in ash and sulfur contents was achieved by the following input parameters: particle size, 100 mesh (150 µm); solid to liquid ratio, 20:80 (w/v); xylene dose, 6.8 mL; agitation time, 10 min; pH 7; and stirring speed, 2,520 rpm. Significant reduction in ash (%) and sulfur (%) showed the effectiveness for agglomeration of Dukki coal using xylene as agglomerant. The final product thus obtained may be used efficiently in various energy recovery schemes.     

Agglomeration of Pakistani coal (Lakhra) using diesel oil

The upgradation of a low quality coal enables it suitable for wider applications. The Lakhra coal (Pakistan) belongs to the lignite coal category. This study investigates the agglomeration technique for beneficiation of Lakhra coal using diesel oil as an agglomerant. Three parameters were investigated such as the solid–liquid ratio, residence time, and shear velocity. Characterization of the Lakhra coal before and after agglomeration was carried out in order to determine its volatile matter, fixed carbon, ash and sulfur contents, and gross calorific value. According to the results, agglomerates contained fixed carbon 35.63%, volatile matter 42.21%, gross calorific value (GCV) 5570.6 kcal/kg, ash 17.07%, and sulfur 4.03%. The ash and sulfur reductions were 42.3% and 58.4%, respectively, suggesting significant reduction in ash and sulfur compared to the original coal. The clean coal, resulting from this cleaning process, is a good grade product which may be valued as a good fuel source for any coal fired utility.     

Refuse-derived fuels as a renewable energy source in comparison to coal,rice husk,and sugarcane bagasse

The calorific potential of refuse-derived fuels (RDFs) was investigated with different coals, rice husk, and sugarcane bagasse. Carbon-sulfur analysis, gross calorific value (kJ/kg), and proximate analysis (%) were carried out. Total carbon of coal samples was found to be in the range from 62.65 to 79.19%, while RDF samples were ranged from 40.21 to 57.34% which were almost similar to rice husk (49.13%) and sugarcane bagasse (46.13%). Comparison of the total sulfur content of the coal (Duki) (10.52%) was very high as compared to RDF samples ranged from 0.17 to 0.46% and almost similar to rice husk (0.34%) and sugarcane bagasse (0.187%), while other coal samples ranged from 2.1 to 4.5%. The gross calorific value of the coal (Duki) (6,163 kJ/kg) was higher to other coal samples ranged from 4,935 to 4,972 kJ/kg, while found to be almost double to rise husk (3,518 kJ/kg), sugarcane bagasse (3,285 kJ/kg), and RDF samples (3,125–4,689 kJ/kg). The moisture content, volatile matter, and ash content were found higher in RDF 1 (42.14%), RFD 2 (66.55%), and coal (stone) (33.14%), respectively. Appropriate gross calorific value and very low sulfur content of the RDFs, especially RDF 2, appeared adequate to be used as a fuel with a lesser pollution potential and as an alternative fuel in mega cement industry of Pakistan.     

Movable injection point–based syngas production in the context of underground coal gasification

Underground coal gasification (UCG) has been proven as a viable technology for the generation of high calorific value syngas using deep mine coal seams. The use of multiple injection points/movable injection point method could be an alternate technique for efficient gasification of high ash Indian coals. In this context, the present study is focused on evaluating the heating value of syngas using a variety of gasifying agents such as pure O₂, air, humidified O₂, and CO₂-O₂ dual-stage gasification under movable injection method for high ash coals. It is found that the use of movable injection point method had significantly increased the heating value of the product gas, compared with the fixed point injection method. For high and low ash coal under pure O₂ gasification, the calorific value of syngas obtained using movable injection point is 123.2 and 153.9 kJ/mol, which are 33.5% and 24.3% higher than the syngas calorific value obtained using fixed injection point, respectively. Further, the air as a gasification agent for high ash coals had increased the gross calorific value of the syngas by 24%, using this technology. The results of high ash coal gasification using humidified oxygen at optimum conditions (0.027-kg moisture/kg dry O₂) and CO₂-O₂ gas had enhanced the syngas calorific value by 12.6% and 5%, respectively. Humidified O₂ and CO₂-O₂ gasifying agents produced a high-quality syngas with the calorific value of 190 kJ/mol, among the gasifying agents used. The experimental results had shown that the movable injection point method is found to be a better alternative for the generation of calorific value-enriched syngas using high ash-based Indian coals.     

Factors Affecting the Oil Agglomeration of Sivas-Divriği Uluçayır Lignite

Abstract

In the coal industry, the coal particles need to be decreased to a very fine size because of the need of removing inorganic materials from coal. Oil agglomeration is a kind of coal cleaning technique that is used for separation of organic and inorganic parts of fine sized coal. In this study, the oil agglomeration of Sivas-Divri?i (S-D) Uluçay?r lignite was carried out by using kerosene, diesel oil, fuel oil, poppy oil, and sunflower oil. The amount of bridging oil was varied from 5% to 25% of the amount of lignite. The effect of oil amount, oil type, solid content, agitation rate and time, pH on agglomeration performance was investigated. Maximum recovery value of 98.18% was observed by using poppy oil. In order to investigate the effect of pH on agglomeration NaOH and HCl is added to the slurry in various amounts. It is decided that the best agglomeration condition is obtained at low pH values. The effect of nonionic surface active agent (Igepal-CA 630) on agglomeration is investigated by adding to the slurry and it is observed that the grade is increased with the amount of surface active agent.     

Effect of oil type on the recovery of coal fines from coal waste slurry by the oil agglomeration process

The coal fines from slurry waste discarded from the Jamadoba coal preparation plant were used for the recovery of significant energy value coal fines. The effect of oil type was investigated using different oils (edible oil and nonedible oil) at constant pulp density (PD) and agglomeration time (AT) and varying oil dosages. (ODs) The results were evaluated based on % organic matter recovery (% OMR) and % ash rejection (% AR).     

Recovery of coal fines from coal waste slurry by oil agglomeration process using linseed oil

The coal fines from Jamadoba Coal Preparation Plant was used for coal oil agglomeration, and the effect of pulp density (PD), oil dosage (OD), agglomeration time (AT), and particle size (PS) were investigated using linseed oil as bridging liquid. The results were evaluated based on % ash rejection (% AR) and % organic matter recovery (% OMR). The maximum % AR and % OMR were achieved at low PD (3%), high OD (15%), high AT (15 min), and low PS (75 µm).     

Characteristics of coal quality and their relationship with coal-forming environment: A case study from the Zhuji exploration area,Huainan coalfield,Anhui, China

The comprehensive information of coal quality and its relationship with coal-forming environment in Zhuji exploration area, Huainan coalfield Anhui, China, have been studied. The data of coal quality including proximate and ultimate analysis, calorific values, sulfur forms, petrography and selected trace elements (Ga, Ge, V, U, Th, Cl and As) are based on 614 samples of 13 minable coal seams from 88 drilling holes collected during exploration periods. These data were designed to provide information on the technological performance of coal. Characteristics of coal quality deposited in three different sedimentary environments, namely in coal-bearing strata of the Shanxi Formation, Lower Shihezi Formation and Upper Shihezi Formation, were analyzed. Results show that moisture, volatile matter, and ash yield all increase stratigraphically upward, which is opposite to the variation of calorific values. The correlation between ash yield and calorific value shows negatively higher relevance that than of moisture and ash yield. The coal quality parameters of the boreholes along the divided faults were rarely controlled by geological setting. It was suggested that other factors such as magmatic activity and underground water cycling may modify the parameters of coal quality to some extent and cause their redistribution.     

Effect of Prussian Blue on Organic Sulfur of Coal in Aqueous Medium

Abstract

This study is an attempt to desulfurize organic sulfur from coal samples with ferric hexacyanoferrate (II), Fe₄ [Fe(CN)₆], as the desulfurization agent. Effect of temperature, particle size and concentration of ferrocyanide ion on desulfurization from the coal samples has been investigated. The temperature and stirring time are the most important parameters for the level of desulfurization of organic sulfur. Removal of organic sulfur content increased continuously with increasing temperature from 298 to 368 K. The organic sulfur removal rate sharply increases from 10 min to 30 min stirring time. After 30 min, it reaches a value of plateau. Particle size between ?100 mesh and ?200 mesh slightly affects the amount of organic sulfur removal. Gradual increase in the concentration of ferric hexacyanoferrate (II) raised the magnitude of desulfurization, but at higher concentration, the variation is not significant.     

旋转锥式反应器催化大豆油裂解制备可再生燃料油

采用自制的转锥式催化裂解反应器,研究了以大豆油为原料制备可再生液体燃料油的技术.考察了催化剂的种类、裂解温度、加料速度等反应工艺条件对裂解产物性能的影响.研究结果表明:催化裂解反应的优选工艺条件为氢氧化钾作为催化剂,反应温度为450-500℃,滴加速度为50g/h,液体燃料收率为78.3%.气质联用和红外光谱分析表明,...     

Cleaning of high sulfur Indian coal by oil agglomeration and leaching

The present paper reports an attempt for cleaning of high sulfur Indian coal with two consecutive steps of oil agglomeration at ambient temperature followed by leaching at various conditions. The physico-chemical characterizations of the raw and treated coal samples were carried out by using Fourier transform infrared (FTIR), FESEM, Thermogravimetric analysis and Differential Thermal Analysis (TGA-DTA), and petrographic techniques to assess the product quality. The petrographic and FTIR spectral analyses reveal reduction in different forms of sulfur contents in coals by the use of oil agglomeration and leaching. Scanning electron microscope morphology of the treated coal samples are attributed to the occurrence of the cavitations in the coal structure.     

Combustion behavior of KOH desulphurized coals assessed by TGA-DTG

This work presents the results obtained from the experimental study on the effects of KOH treatment and its combustion behavior of high sulfur Indian coal. Coal was treated with 5–20% KOH (v/v) concentration for 6–24 h reaction time to identify the effects of KOH treatment on coal properties. Experimental results showed that upto 36.79% of total sulfur can be removed from coal with 20% KOH concentration and 24 h contact time at atmospheric condition. However, gross calorific value of coal decreased from 6800 to 6084 kcal/kg due to removal of combustibles from coal. Combustion characteristics of treated coal were assessed by Thermo-gravimetric analysis/ Differential thermo-gravimetric (TGA/DTG analysis). Further various combustion kinetic parameters like ignition temperature, peak temperature, burnout temperature, activation energy (E), and pre-exponential factor (A) are estimated. Experimental results show that the ignition temperature of coal decreased from 321°C to 252°C, peak temperature decreased from 459°C to 409°C due to changes in the coal matrix after desulfurization. The activation energy of coal calculated decreased from 79 to 45 kJ/mol due to desulfurization using 20% KOH concentration and 24 h reaction time.     

大型电站煤粉炉燃用高钙煤的自身固硫效果

1025t h煤粉炉在满负荷下燃用高钙低硫的神木煤时,其自身固硫率高达27%～33%。在入炉的矿物灰和钙成分中,60%左右形成飞灰,只有不到10%形成炉底渣。在入炉硫分中,70%左右以气态SO2形式随烟气排放,只有不到10%以固态形式富集于飞灰中,不到1%固定于炉底渣中。XRD定性分析表明:飞灰中因高温熔融形成的玻璃状非晶相含量比底渣中高出许多,并含有自身固硫产物CaSO4和未反应的CaO晶相。在炉底渣中并未发现CaSO4或CaO晶相,但新生成了大量的钠长石晶相。图2表7参4     

Determination of Coal Rank by Fuzzy Logic: A Case Study of Coal from Central Anatolia,Turkey

Koyunagili coalfield in the Beypazari basin of the Central Anatolia was investigated and coal ranks were determined using fuzzy Mamdani model based on ASTM coal rank classification. This is a pilot study to investigate the applicability of the fuzzy model to determine the ranking of any coal seam. The Koyunagili coalfield, which is located at the southern part of the Beypazari basin, consists of the late Miocene coal seam within the tuffaceous rocks. The mineable coal seam is split by a 0.5–0.55 m thick clayey limestone into the upper (1.2–1.3 m thick) and lower (0.4 m thick) benches. A total of 28 profile coal samples from underground mines were collected. The samples have an average of 30.9% moisture (as-received), 23% ash yield, and 2.9% total sulphur and 4167 kcal/kg gross calorific value on an air-dried basis. Mean random reflectance values of huminite have an average of 0.34%, and show no differences across the coalfield. Coal ranking has been determined by the fuzzy Mamdani model. During processing, fixed carbon content (FCC), volatile matter values (VMV), calorific value (CV), and vitrinite/huminite reflectance (Ro %) parameters are inputs, and a total of 10 rules are used for the model. Modeling results are consistent with the previous studies.     

Production of fuel by co‐pyrolysis of Makarwal coal and waste polypropylene through a hybrid heating system of convection and microwaves

The bituminous coal of the Makarwal range of Pakistan and waste polypropylene were converted into gaseous and liquid fuel using a hybrid heating process based on microwave metal interactions. The mixture of coal and polypropylene was heated by the volumetric heating generated by absorption of the microwaves and the conventional heating produced by the sparking of copper under microwave power in a domestic microwave oven. The heat generation capacity and range of sparking of copper were increased by the use of tightly coiled copper antenna. The heat generation efficiency of copper antenna was found to vary with variation in the shape of the copper antenna. Four types of antenna were used in the pyrolysis process, i.e. the antenna made of tightly coiled copper, copper mesh antenna, copper strips antenna and copper cylinder antenna. It was observed that copper coil and copper mesh antenna were more efficient and responsible for higher percent conversions while the multi‐strip antenna was next and the least percent conversion was observed for single strip cylinder of copper. The amount of products and the relative concentrations of the oil, wax and gases were observed to vary with variations in the relative amount of coal and polymers. Both the gaseous product and aqueous fraction were analysed for sulphides using lead acetate reagent. The gases were also analysed for the presence of alkynes and alkenes using aqueous solutions of copper‐I chloride and potassium permanganate respectively. The oily product which was composed of oil and wax was analysed by GC‐FID and GC‐MS analyses. Copyright © 2016 John Wiley & Sons, Ltd.     

Evaluation of feasibility of pelletized wood co-firing with high ash Indian coals

To reduce anthropogenic CO₂ emissions from power plants, biomass is an immediate alternative fuel which has similar properties as coal. In this regard, the present study discusses about pelletized wood (PW) co-firing with high ash Indian coal by conducting co-milling and co-firing trials in a 1000 kg/hr of pilot scale test facility. Indian coals are typically high ash content and low calorific value fuels, therefore, its interaction with coal during combustion and ash deposition have studied in detail. Based on co-milling trails of PW and coal, it was observed that as PW proportion in coal increases, the quantity of particles of size below 50 μm and as well above 500 μm were increased. From co-firing studies, it was observed that higher volatile content in PW helping in stabilizing flames while co-firing. At lower proportions, up to 10% weight PW co-firing with coal, the flame temperature and heat flux values are very close to base test of 100% coal firing. However, beyond 10% by weight of PW co-firing with coal, the flame temperature and heat flux values were increased significantly from 100% coal tests. This is because of higher calorific value of PW than coal. The CO emission was decreased with increase in PW proportion in coal but at 30% of PW in coal, CO emission was increased suddenly. However, NO and SO₂ concentrations were decreased up to 8% and 16% respectively with increase in PW proportion in coal due to lower fuel nitrogen and sulphur content in PW than coal. Analytical analysis of slagging indices suggest that the slagging potential for PW co-firing with coal is increasing as the PW proportion in coal increases.     

Ficus elastica - The Indian rubber tree - An underutilized promising multi-use species

Ficus elastica known as the Indian rubber tree has a white, milky latex that is a source of natural rubber was analyzed for its phytochemicals as an intermediate energy source. The tree produces a high quantity of protein and oil (24.5 and 6.1% respectively). The polyphenol content was 4.2%, and hydrocarbon content was 2%. The gross calorific value of the plant sample was 28.7 MJ kg⁻¹, much higher than that of methanol (22.4 MJ kg⁻¹), but comparable to anthracite coal (29.7 MJ kg⁻¹). The gross calorific value of the oil fraction was 32.8 MJ kg⁻¹. This species also contains high levels of ortho-dihydroxy phenols which may be related to disease resistance to some pathogens. It also possesses compounds with antimicrobial activity and a range of pharmacological activities. F. elastica has several chemical constituents, other than rubber, which have potential uses and warrant further study.     

Purifying hazardous elements in Yiluo fine coal by dry high-gradient magnetic separation

Dry magnetic separation of different sizes of Yiluo fine coal was carried out to purify deleterious elements. It was found that dry magnetic separation can effectively reduce a variety of harmful trace elements in raw coal. Regardless of coal particle size, the rejection efficiency of Cd, Hg, As, and Mn is 39.07%–57.16%, 33.89%–49.94%, 30.49%–47.52%, and 27.10%–52.28%, respectively. Relatively high removal efficiency of Pb, Cu, and Se is obtained, which is 26.23%–35.32%, 27.25%–39.41%, and 25.05%–32.84%, respectively. Moreover, the results show that sulfur rejection of 33.87% and reductions in ash of 41.19% are obtained with particle size of 80–120 mesh, while the combustible recovery reaches 83.68%.     

不同采矿深度准东煤物化特性和燃烧性能研究

选取天池能源浅层和深层煤样进行研究,以大同烟煤作为对比,了解采矿深度对煤质及燃烧特性的影响,为准东煤的勘探和燃烧提供必要的理论依据。研究发现,随着采矿深度的增加,煤中水分减少、灰分降低、发热量增加、含硫量减少,煤质更加接近烟煤;煤灰中Fe2O3明显减少,煤的结渣趋势减轻;煤的着火温度略有降低,燃烧速率提高,燃烧特性变好。与大同烟煤相比,准东煤高水分、低发热量、低氮含量,燃烧时着火温度显著降低且燃烧速率低。     

Effects of coal properties on the production rate of combustion solid residue

The production rates of furnace bottom ash in a pulverized coal-fired power plant were monitored for a two-year period and its variations with respect to coal properties were analyzed. The power plant was originally designed to fire the coal sludge generated from a washing process; however, the coal sludge and its mixture with low-rank bituminous coal have been started to be used as the main fuel with time. The results of the hardgrove grindability measurements have shown that the grinding properties of sludge or its mixtures could not be predicted based on proximate analysis (moisture, ash, carbon and volatile contents); it could only be determined by experiments. The production rate of bottom ash in this particular power plant remained relatively insensitive to the high ash and moisture contents and could be estimated almost only by knowing the calorific value of the source coal. The evaluated dependency was linear.