浅谈一台25MW燃煤泥、煤矸石的循环流化床锅炉的设计

阐述了25MW燃煤泥、煤矸石CFB锅炉的设计特点，介绍了该锅炉通过“差速床”技术、高大炉膛、中温分离器、泵送系统等方法实现了煤泥、煤矸石的有效利用。     

工业固废物CFB处理技术浅述

环境问题以及由煤、石油、天然气等化石燃料逐年递减所引起的能源替代问题使循环流化床燃烧技术逐渐在工业固体废弃物的回收和利用方面扮演越来越重要的角色。综述了采用循环流化床锅炉燃烧石油焦、油页岩、煤矸石、煤泥、水煤浆、污泥、纸厂废弃物、皮革加工废弃物和废轮胎等工业固废物的国内外研究和应用现状,指出了目前存在的问题及努力的方向。     

准东煤掺烧煤矸石安全性与经济性分析

高岭土与低钠煤可以有效抑制燃用准东煤时炉内的沾污结渣问题,但由于其价格升高,为降低电厂燃煤成本,因此提出将煤灰成分相似的煤矸石作为准东煤防结渣添加剂.分析煤矸石作为添加剂抑制炉内沾污结渣的可行性,根据入炉煤灰中折算Na2O含量低于3.0％,确定掺烧比例,并在某150 MW机组上进行实炉掺烧试验.通过掺烧试验分析可见,煤...     

Pyrolysis of blends of different types of sewage sludge with one bituminous coal

Pyrolysis of sewage sludge samples from three Asturian urban wastewater treatment plants was carried out. One high volatile bituminous coal and its blends with 10 and 50 wt% of sludge were studied by thermogravimetry. The same operational conditions (a constant heating rate of 10 °C/min in the temperature range 25–800 °C and a N₂ flow of 200 cm³/min) were maintained throughout. The results indicate that sludge is formed by two organic fractions with different reactivity, whose devolatilisation processes partially overlap. Both fractions are more reactive than coal, since they decompose and devolatilise at temperatures lower than coal. Under oxidizing conditions, the action of oxygen during pyrolysis depends on the conditioning of sludge. If sludge is treated with FeCl₃, oxidative pyrolysis takes place. The behaviour of sludge–coal blends is intermediate between those of the coal and the corresponding sludge, without interactions between both blend components. In addition, a kinetic analysis was performed to fit thermogravimetric data, the global processes being considered as a series of consecutive first order reactions. A reasonable fit to the experimental data was obtained for all materials and their blends.     

煤矸石成分及其再利用技术研究

针对当前煤矸石利用率低造成资源浪费和环境污染的问题,在分析煤矸石矿物、化学成分的基础上,通过浸泡试验分析影响其中所含有毒元素浸出浓度的因素,为煤矸石的再利用提供指导,最终提升煤矸石的利用率,减小煤矸石对环境的污染。     

Development and technical progress in large-scale circulating fluidized bed boiler in China

Circulating fluidized bed (CFB) boilers has realized the clean and efficient utilization of inferior coal like gangue and coal slime, high sulfur coal, anthracite, petroleum coke, oil shale and other resources. As a country with the largest amount of CFB boilers and the largest installed capacity in the world, China has 440 100–600 MW_e CFB boilers with a total capacity of 82.29 GW_e, including 227 units of 135 MW_e, 95 units of 300 MW_e, and 24 supercritical units. The statistics of typical 100–300 MW_e CFB boilers showed that the average number of unplanned shut-down was only 0.37 times per year, among which the 135 MW_e was 0.26 times per year and 300 MW_e was 0.46 times per year. The auxiliary power ratio of some 300 MW_e CFB boilers based on flow-pattern reconstruction can be reduced to about 4%, which is closed to the same level of pulverized coal (PC) boilers. This paper summarizes the development process and application status of China’s large-scale CFB boilers, analyzes the characteristics and technical performance of the iconic units, and introduces solutions to the problems such as water wall wear and bottom ash cooling.     

The effect of coarse gangue particles during the coal flotation process

It is well known that fine gangue particles play an important role in contaminating the concentrate during coal flotation process. However, the contamination behavior of coarse gangue particles in the concentrate has been neglected in the past. In this paper, the contamination behavior of coarse gangue particles in the concentrate during coal flotation process was investigated using a mixture of coarse gangue particles and low ash coal particles at a proportion of 1:1. The size fraction of coarse gangue particles was 0.5–0.25 mm. The size fraction of low ash coal particles was 0.5–0.25, 0.25–0.074, and ?0.074 mm, respectively. The results of XRD showed that coarse gangue particles were composed of quartz, pearl clay, kaolin, mica, and dickite. The results of contact angle measurements showed that the contact angle of coal particles was about 89° while that of gangue particles was only 30°. The results of flotation tests indicated that the contamination behavior of coarse gangue particles in the concentrate during the coal flotation process cannot be neglected.     

Study on Al<Subscript>2</Subscript>O<Subscript>3</Subscript> extraction from activated coal gangue under different calcination atmospheres

Coal gangue was calcinated under air, nitrogen, carbon dioxide, air–hydrogen, and hydrogen atmospheres. The effects of different calcination temperatures and atmospheres on the mineral composition of activated coal gangue were investigated by X-ray diffraction. Moreover, the acid leaching kinetics of aluminum oxide from coal gangue was investigated with sulfuric acid. It showed that the air atmosphere promoted kaolinite decomposition during coal gangue calcination. The hydrogen atmosphere promoted the activation and decomposition of kaolinite at reaction temperatures exceeding 650°C. The carbon dioxide atmosphere eliminated the influence of residual carbon on coal gangue. When the ratio of acid/coal gangue was 1.5 and reaction temperature was 650°C, the sulfuric acid leaching rate under air, air-hydrogen, carbon dioxide, hydrogen and nitrogen atmospheres were 93.66%, 90.90%, 84.06%, 81.91% and 77.54% respectively. The acid leaching reaction process conformed to unreacted shrinking core model of particle unchanged, and was controlled by the interfacial chemical reaction. The reaction kinetic equation for the leaching process was 1-(1-x)1/3=kt with an apparent activation energy of 48.97 kJ/mol.     

Application of advanced correlative approaches to modeling hydrogen solubility in hydrocarbon fuels

In petroleum and petrochemical refineries, having precise knowledge regarding H₂ solubility in hydrocarbon fuels and feedstocks is critical. In this study, the hydrogen solubility in hydrocarbon fuels was estimated using genetic programming (GP) and group method of data handling (GMDH), two exemplary robust advanced models for generating correlation. To do this, 445 observations derived from labratory findings on hydrogen solubility in 17 different hydrocarbon fuels such as bitumen, atmospheric residue, heavy coking gas oil, heavy virgin gas oil, light virgin gas oil, straight run gas oil, shale fuel oil, dephenolated shale fuel oil, diesel, hydrogenated coal liquid, coal liquid, and coal oil, over a large interval of P- operating pressures and T-temperatures were collected. Temperature, pressure, as well as density at 20 °C, molecular weight, and weight percentage of carbon (C) and hydrogen (H) in hydrocarbon fuels, were used as input parameters in developing robust correlations. The outcomes showed the GMDH approach is more precise compared to the GP, with a root mean square error (RMSE) of 0.053302 and a determination coefficient (R²) of 0.9641. Additionally, sensitivity analysis showed that pressure, followed by temperature and H (wt%) of hydrocarbon fuels, has the greatest impact on hydrogen solubility in hydrocarbon fuels. Ultimately, the Leverage method's results suggested that the GMDH model could be relied on to predict hydrogen solubility in hydrocarbon fuels.     

改性煤矸石的药剂选择及改性机理的研究

以七台河地区煤矸石为原料,选择多种表面改性处理剂,对煤矸石进行表面处理,并测定其润湿接触角、粒度、微热、红外光谱等指标,对改性机理进行深入探讨。将改性后的煤矸石样品填充于橡胶制品中,测试填料对橡胶的补强作用。试验表明:表面改性剂的种类选择对橡胶的补强性能有很大的影响,经过CT-136处理后的煤矸石对橡胶具有较好的补强作用,可部分替代炭黑,减少炭黑的用量,降低橡胶的成本,并减少煤矸石对环境的污染。     

Preparation of high-activity coal char-based catalysts from high metals containing coal gangue and lignite for catalytic decomposition of biomass tar

The potential of using high metals containing coal gangue and lignite to prepare high-activity coal char-based catalysts is investigated for effective biomass tar decomposition. Loose structure and rough surface are formed for these char-based catalysts with heterogeneous distribution of a large number of inorganic particles. In the biomass tar decomposition, the performance of the coal char-based catalysts is significantly influenced by the content of the metals in the raw materials and coal gangue char (GC) with the ash content as high as 50.80% exhibits the highest activity in this work. A high biomass tar conversion efficiency of 93.5% is achieved at 800 °C along with a significant increase in the fuel gas product. During the five-time consecutive tests, the catalytic performance of GC increases a little at the second or third times reuse and remains relatively stable, showing the remarkable stability of the catalyst in biomass tar decomposition applications.     

Co-gasification of coal gangue and pine sawdust on a self-made two-stage fixed bed: Effect of mixing ratio

In this paper, the synergistic effect of co-gasification for coal gangue and pine sawdust was studied on a self-made two-stage gasification fixed bed experimental device. The results indicated that there was synergistic effect between coal gangue and pine sawdust. With the gasification temperature was 850 °C, the catalytic reforming temperature was 900 °C, the steam flow was 2 ml/min and the mixing ratio of coal gangue and pine sawdust was 1:1. The co-gasification synergistic effect yields the best results, the H₂ volume fraction reached its highest value of 37.2%, with a synergistic coefficient of 0.22. Under this condition, the number of mesopores in co-gasification char was the largest and the absorbance of the hydroxyl (-OH) functional group was the smallest. The alkali metal (K, Ca) content reached a maximum of 22.18%, which was conducive to the formation of hydrogen.     

山西省煤矸石资源化利用现状及发展建议

山西省长期的煤炭生产造成煤矸石的大量堆放,占用了大量的土地资源,造成严重的环境污染和能源浪费。介绍国内外煤矸石资源化综合利用现状,以及山西省煤矸石资源化综合利用途径,分析了山西省煤矸石综合利用面临的形势与存在问题,提出了促进山西省煤矸石综合利用的对策。     

Reducing the greenhouse gas footprint of shale gas

Shale gas is viewed by many as a global energy game-changer. However, serious concerns exist that shale gas generates more greenhouse gas emissions than does coal. In this work the related published data are reviewed and a reassessment is made. It is shown that the greenhouse gas effect of shale gas is less than that of coal over long term if the higher power generation efficiency of shale gas is taken into account. In short term, the greenhouse gas effect of shale gas can be lowered to the level of that of coal if methane emissions are kept low using existing technologies. Further reducing the greenhouse gas effect of shale gas by storing CO₂ in depleted shale gas reservoirs is also discussed, with the conclusion that more CO₂ than the equivalent CO₂ emitted by the extracted shale gas could be stored in the reservoirs at significantly reduced cost.     

Shale gas vs. coal: Policy implications from environmental impact comparisons of shale gas,conventional gas,and coal on air,water, and land in the United States

The aim of this paper is to examine the major environmental impacts of shale gas, conventional gas and coal on air, water, and land in the United States. These factors decisively affect the quality of life (public health and safety) as well as local and global environmental protection. Comparing various lifecycle assessments, this paper will suggest that a shift from coal to shale gas would benefit public health, the safety of workers, local environmental protection, water consumption, and the land surface. Most likely, shale gas also comes with a smaller GHG footprint than coal. However, shale gas extraction can affect water safety. This paper also discusses related aspects that exemplify how shale gas can be more beneficial in the short and long term. First, there are technical solutions readily available to fix the most crucial problems of shale gas extraction, such as methane leakages and other geo-hazards. Second, shale gas is best equipped to smoothen the transition to an age of renewable energy. Finally, this paper will recommend hybrid policy regulations.     

Underground in situ coal thermal treatment for synthetic fuels production

Underground coal thermal treatment (UCTT) is a promising concept that was recently proposed for extracting high-value hydrocarbon fuels from deep coal seams, which are economically unattractive for mining. UCTT is essentially an in situ pyrolysis process that converts underground coals into synthetic liquid and gaseous fuels, while leaving most of the carbon underground as a char matrix. The produced synthetic fuels have higher H/C ratios than coals. The remaining char matrix is an ideal reservoir for CO₂ sequestration because pyrolysis significantly increases the surface area of the char. The UCTT concept is relatively new, and there is little research in this area. However, underground oil shale retorting, which is also an in-situ hydrocarbon fuels conversion process, shares key features with UCTT and has gained momentum in demonstration and commercial development. As such, there is a large body of literature available in this area. A review of the studies on underground oil shale retorting that are closely related to UCTT will shed light on the UCTT process. This paper presents a review of the recent literature on underground oil shale retorting that are most relevant to UCTT process. The review provides a background to the reader by comparing the properties of coal with oil shale, with an emphasis on the feasibility of applying oil shale retorting techniques to UCTT process. The review further discusses the coal and oil shale conversion issues and uses the knowledge of the latter as guidance for the development of UCTT. Published data on pyrolysis of large coal blocks at conditions relevant to UCTT process is scarce. Therefore, literature on conventional coal pyrolysis is reviewed for optimization of the UCTT process. Despite the abundant studies on pulverized coal pyrolysis, there are still many open questions on whether they can be directly applied to UCTT. A comparison of the unique environment of UCTT with conditions of conventional pulverized coal pyrolysis clearly shows there are knowledge gaps. Future research needs are then proposed to close these gaps.     

我国利用煤层气、煤矸石、煤泥发电现状、问题与建议

本文对我国利用煤层气、煤矸石、煤泥发电现状及存在的问题进行了研究与分析,并提出了其建议,包括煤层气、煤矸石、煤泥发电普遍存在并网难,应出台更为可行和现实的激励政策予以解决;应重新调整煤层气发电上网电价的补贴政策;提高煤矸石发电燃料应用基低位发热量标准;加强技术攻关,解决存在的技术障碍等。     

我国粉煤灰、煤矸石综合利用技术经济政策分析

粉煤灰、煤矸石是典型的工业固体废弃物,积极开展粉煤灰和煤矸石综合利用对于环境保护和资源节约具有重要意义,技术经济政策在推进粉煤灰和煤矸石综合利用中发挥重要作用。本文梳理了改革开放以来关于粉煤灰和煤矸石综合利用的政策法规,在对政策发展特点和实施效果进行分析的基础上,结合现实调查,指出粉煤灰和煤矸石综合利用技术经济政策中所存在的问题,并提出了相关建议。     

Thermogravimetric analysis of the co-combustion of coal and paper mill sludge

The thermal behavior of semi-anthracite coal, paper sludge and their blends during pyrolysis and combustion processes was investigated in this study. The experiments were conducted in a differential thermogravimetric analyzer at different heating rates (10 K/min, 20 K/min and 30 K/min) and at temperatures ranging from 310 K to 1300 K. The results revealed that de-volatilization of paper sludge occurred earlier with a higher rate, and that the process was further accelerated under oxygen-enriched conditions. The blends had integrative thermal profiles that reflected both paper sludge and coal. In addition, the blends showed different ignition and combustion behavior depending on the percentage of sludge. Two types of non-isothermal kinetic analysis methods were applied to evaluate the combustion processes. The kinetic parameters of the blends confirmed the improved ignition characteristics. In addition, both the TG profiles and activation energy indicated that the combustion of their blends with low percentages of sludge, such as 10 wt.%, were similar to that of coal. These experimental results help explain and predict the behavior of coal and paper sludge blends in practical applications.     

Mineralogical characterization and washability of Indian coal from Jamadoba

Coal characterization becomes a prelude for designing of washing circuits and also utilization of washed products. In the present paper, an attempt has been made to characterize coal obtained from an operating washery (Jamadoba, Jharia) as a case study. Two approaches, viz., physical and chemical characterization approaches, have been attempted after crushing the coal to finer size (?3.0 mm) for improved liberation. In the first approach, physical characterization of feed coal was done by density fractionation (float and sink test) using mixtures of organic liquids, besides determination of Hardgrove Grindability Index to estimate the friability nature of the coal. In the second approach, mineralogical characterization of coal has been done by modern analytical methods such as X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Fourier-Transform Infrared Spectroscopy (FTIR), thermogravimetric, and differential thermal analyses.

The results of the float–sink test indicated coal to possess difficult washing characteristics having its near-gravity material content of 31.5 at 1.52 g/cc washing density and is of ‘formidable type’ as per Bird's Scale of Classification. The results of Hardgrove Grindability Index (HGI) indicated that the coal to be medium hard. Further, the difficulty washing has been established by estimating the values of Washability Number and Washability Index. The results of mineralogical analysis on the inorganic mineral matter composition indicated that the coal to contain quartz as the major gangue mineral and kaolinite, illite, montmorillonite, rutile, calcite, siderite, and pyrite as minor gangue components. The present paper enumerates that for development of a beneficiation strategy, physical characterization studies (such as Washability Index and Washability Number), etc., are important. However, mineralogical and chemical characterizations place a vital role from the end utilization point of view.