Trace elements in brown coal and its products of combustion

Concentrations of 38 elements in brown coal, bottom ash and size fractionated ESP coal ash from the Belchatów I Power Plant were determined by INAA. Based on enrichment factors calculated relatively to iron and average crustal rock composition as a function of particle size the elements are grouped into three classes: Group I, elements that show little or no enrichment in the small particles /Na, Mg, Al, K, Sc, Ti, Mn, Co, Rb, Cs, Ba, La, Ce, Sm, Eu, Lu, and Th/; Group II, elements whose enrichment increases greatly with decreasing particle size /Cl, Zn, As, Se, Br, Cd, Sb, and I/; and Group III, elements whose behaviour is intermediate to that of elements in Group I and II /Ca, V, Cr, Ni, Cu, Ga, Sr, Mo, In, W, and Au/.     

Calorimetry in the science of building materials

A new conceptual approach is proposed for evaluation of the most important properties of cement-containing composites on the basis of the rate and degree off completeness of hardening processes and study of the porous structure during material formation, within the limits of the system “composition-structure-process-property”.     

煤与混合废塑料共热解固体产物中氯的赋存形态及在燃烧时的释放特性

通过红外光谱、热重 质谱及燃烧 水解实验,研究了煤与废塑料共热解固体产物中氯的赋存形态及在燃烧过程中氯的释放特性。结果表明,温度低于600℃热解的半焦中存在有机氯化合物;600℃以上热解的半焦（或焦炭）中氯主要以无机盐类存在。燃烧过程中氯的释放率与燃烧温度,煤与废塑料共热解的温度以及共热解时废塑料的加入量有关。燃烧温度越高,氯的释放率越大,900℃燃烧时,氯的释放率都在94%以上;在同一温度燃烧时,热解温度越高,氯的释放率越低。400℃热解的半焦最高释放率达99.86%,而1000℃热解的焦炭的最高释放率为94.35%。     

Speciation of the inorganic components in brown coal

Brown coal samples from different deposits have been analyzed for the bonding forms of their inorganic components. Besides the analysis of the dried coals, ashing techniques (high and low temperature ashing) and extraction procedures with different solvents (acids, bases, complexation agents, organic solvents with different polarity) have also been investigated. ESCA, PIXE, INAA, ICP-Atomic Emission Spectroscopy, NMR and Ionchromatography have been applied to the analysis of coals, ashes, wet ashing and extraction products. The bonding behavior of more than 40 elements could be characterized. Conclusions about geological and geochemical processes during and after coalification could be drawn.     

Formation of belite-based binder from waste materials

Journal of Thermal Analysis and Calorimetry - The present work deals with the preparation of belite-based binders using a mixture of sludge waste from mining and washing of limestone (source of...     

Adsorption properties of carbon materials produced by thermolysis of brown coal in the presence of alkali metal hydroxides

Activated carbons produced by thermolysis of brown coal impregnated with an alkali metal hydroxide MOH (M = Li, Na, K) at an MOH/coal ratio R _MOH ≤ 80 mol kg^?1 were studied. Dependences of the adsorption capacities for iodine and Methylene Blue dye, specific surface area, and yield of activated carbons on the ratio R _MOH were obtained.     

Probing the combustion and pyrolysis behaviors of polyurethane foam from waste refrigerators

Journal of Thermal Analysis and Calorimetry - Polyurethane foam (PUR) from waste refrigerators has long been recognized as a difficult-to-treat electronic waste, due to its bulkiness, low weight...     

Carbon-mineral adsorbents from waste materials: case study

Waste bleaching earth from the food industry obtained in the process of fruit juice purification was utilized for preparation of carbon-mineral adsorbents. The waste material, containing 25.8 wt% C, was subjected to three kinds of treatment: (1) direct pyrolysis at 400 degrees C with a suitable temperature program; (2) preliminary hydrothermal modification (200 degrees C, 8 h, 15.3 atm) and then pyrolysis as in method 1; (3) preliminary thermal treatment (400 degrees C) and then chemical treatment (boiling in 3% solution Na(2)CO(3)), followed by heating at 400 degrees C (10 min). Moreover, the materials obtained by these methods were subjected to additional thermal treatment at 700 degrees C with a suitable temperature program. Both the morphology and the topography of carbon deposits and, in consequence, the porous structure of the obtained adsorbents depend on the method of their preparation. The additional thermal treatment of these samples at 700 degrees C makes it possible to obtain adsorbents of more thermally stable carbon deposits possessing better parameters of the porous structure. Carbon-mineral adsorbents of different specific surface areas (S(BET) from 17.6 to 153 m(2)/g) and pore volumes (from 0.035 to 0.093 cm(3)/g) were prepared. The mechanism of phenol and p-nitrophenol adsorption on the obtained adsorbents was discussed and their properties were compared with the suitable literature data.     

Preparation of oxygen-containing organic products from bed-oxidized brown coal by ozonation

The possibility of modifying the functional composition of humic acids by gas-phase ozonation of bed-oxidized brown coal was examined. About 90% of the organic matter of brown coal was converted to low-molecular-weight soluble oxygen-containing products by stepwise liquid-phase ozonation (in chloroform and acetic acid).     

Sulfur evolution from coal combustion in O2/CO2 mixture

O₂/CO₂ coal combustion technology is considered as one of the most promising technologies for CO₂ sequestration due to its economical advantages and technical feasibility. It is significant to study the sulfur transfer behavior of coal in O₂/CO₂ atmosphere for organizing combustion properly and controlling SO₂ emission effectively. To clarify the effect of atmosphere on the sulfur transfer behavior, thermogravimetry coupled with Fourier Transform Infrared (TG-FTIR) system was employed to study the formation behavior of sulfur-containing gas species from Xuzhou bituminous coal pyrolysis in CO₂ atmosphere compared with that in N₂ atmosphere. Also the SO₂ formation behaviors during Xuzhou bituminous coal combustion in O₂/N₂ and O₂/CO₂ atmospheres were investigated. Results show that COS is preferentially formed during the coal pyrolysis process in CO₂ atmosphere rather than in N₂ atmosphere. When temperature is above 1000 K, sulfate in the CO₂ atmosphere begins to decompose due to the reduction effect of CO, which comes from the CO₂ gasification. During coal combustion process, replacing N₂ with CO₂ enhances the SO₂ releasing rate. SO₂ emission increases first and then decreases as O₂ fraction increases in the O₂/CO₂ mixture. XPS result of the ash after combustion indicates that higher O₂ concentration elevates the sulfur retention ability of the mineral matter in the coal.     

褐煤热解过程中半焦重整催化剂性质的变化

为降低焦油产率,提高褐煤气化效率,采用胜利褐煤热解所得的半焦作为催化剂,在二阶石英反应器中对煤热解的焦油进行原位催化重整,分析和讨论了反应前后半焦催化剂的性质变化。结果表明,反应后半焦质量较反应前普遍有所下降,半焦是一种消耗性催化剂;反应后半焦的比表面积由422 m~2/g降到231.8 m~2/g;Raman分析结果表明,反应后半焦含氧官能团、小环(3-5个缩合芳环)与大环(大于5个缩合芳环)体系之比均有所降低。在半焦-挥发分作用过程中,快速热解制得半焦主要将挥发分裂解为小分子气体,慢速热解制得的半焦则主要使挥发分缩聚结焦脱除。     

Factors affecting the combustion toxicity of polymeric materials

Fire gas toxicity is an essential component of any fire hazard analysis. However, fire toxicity, like flammability, is both scenario and material dependent. A number of different methods exist to assess the fire toxicity, but many of them fail to relate this to a particular fire scenario. Sample thickness alone, in a closed box test such as the NBS Smoke Chamber, is shown to change the fire scenario from well-ventilated to under-ventilated. Data from two flow-through tests, the static tube furnace (NF X 70-100) and the steady state tube furnace (the Purser furnace, BS 7990 and ISO TS 19700) show that there are different patterns of behaviour for different polymers (LDPE, polystyrene, rigid PVC and Nylon 6.6). The predicted toxicities show variation of up to two orders of magnitude with change in fire scenario. They also show change of at least one order of magnitude for different materials in the same fire scenario. Finally, they show that in many cases CO, which is often assumed to be the most, or even the only toxicologically significant fire gas, is of less importance than either HCl, or HCN, when present, and in some cases less important than organo-irritants. Nylon 6.6 shows the highest predicted toxicity, the greatest scenario dependence, and the least sensitivity to different apparatuses, while polystyrene shows the highest sensitivity to the different apparatuses, but the lowest to different fire scenarios. PVC shows high toxicity, mostly due to HCl in the fire effluent, under all fire conditions, and LDPE shows a more progressive increase in toxicity from well-ventilated flaming to both smouldering and under-ventilated flaming.     

Vacuum microbalance studies on the combustion of Saraji coal

Samples of Saraji coal have been oxidised in air at various temperatures and for different times. Products have been examined by a gravimetric gas sorption technique. Results are presented for changes in surface area and porosity with carbon burn-off and discussed in relation to kinetics of the oxidation.There is considerable development of surface and porosity as the oxidation proceeds, especially during the first half of the burn-off. However, oxidation of the coal is only slightly accelerated, since most of the new surface is located in micro- or meso-pores where access to atmospheric oxygen is restricted by slow diffusion.     

Factors affecting the extraction of uranyl ions from radioactive waste using natural materials

Uranium is considered to be one of the most important elements used in nuclear technology. Different authors have worked deeply with developing the methods and materials used for uranium separation, concentration, and refining. In this work, uptake and release behavior of uranyl ions by wood powder from nitrate medium was studied. The factors affecting both processes were discussed.     

Recycling of waste from polymer materials: An overview of the recent works

Polymer recycling is a way to reduce environmental problems caused by polymeric waste accumulation generated from day-to-day applications of polymer materials such packaging and construction. The recycling of polymeric waste helps to conserve natural resource because the most of polymer materials are made from oil and gas. This paper reviews the recent progress on recycling of polymeric waste form some traditional polymers and their systems (blends and composites) such as polyethylene (PE), polypropylene (PP), and polystyrene (PS), and introduces the mechanical and chemical recycling concepts. In addition, the effect of mechanical recycling on properties including the mechanical, thermal, rheological and processing properties of the recycled materials is highlighted in the present paper.     

Oxide catalyst for the combustion of organic compounds in industrial waste gases

An oxide catalyst for combustion of organic compounds in exhaust gases from plastics plants has been developed. As the active catalyst phase, cupric cobaltate is supported on -Al₂O₃ carrier. Its catalytic activity in the test reaction of propylene oxidation was compared with that of the platinum catalyst used so far. The results show that the new catalyst can replace platinum in the above process.

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. (II) -Al₂O₃. . , .

     

A thermal analysis study of the combustion characteristics of Victorian brown coals

Simultaneous TG, DTA techniques have been applied to investigate the combustion characteristics of Victorian brown coal derived from different coal fields and including various lithotypes. TG and DTA profiles of the entire combustion process were obtained to provide a set of parameters which characterize the oxidation potential of these coal samples. These parameters can also be used to predict the combustion performance of pulverized coal in industrial furnaces. The area of the major DTA combustion peak is closely related to the heat released during the combustion process and therefore provides a means of determining the specific energy of the coal. Different lithotypes are also characterized by their corresponding TG and DTA burning profiles.     

不同煤燃烧方式降低NOx排放比较及解耦燃烧应用

采用两段反应器研究了三种煤在不同燃烧方式下抑制NO_x生成的效果。结果表明,煤的热解气和部分气化生成气再燃均能较好的抑制NO_x生成,抑制效果优于空气分级燃烧,解耦燃烧方式抑制NO_x生成的效果最显著,相对于传统燃烧其NO_x排放降低了32%以上。煤种对各种燃烧方式降低NO_x的程度有明显影响,煤中单位氮含量的燃料比(固定碳/挥发分)越小,煤的热解气和部分气化生成气再燃以及解耦燃烧方式下NO_x的排放量越低。在煤部分气化生成气再燃烧方式中,部分氧化气化段通氧量不同,降低NO_x排放的效果也不同,在氧气体积分数为8%~10%时的NO_x生成量最低。基于解耦燃烧技术原理,研制了1.4 MW解耦燃烧工业锅炉,在燃烧同一煤种时,解耦燃烧锅炉和传统立式锅炉相比,烟气中NO_x排放量降低了32.9%。