煤炭利用清洁化是最现实之选——访全国人大代表、山西煤炭运销集团董事长刘建中

今年以来，中国多地频现雾霾污染，引发了人们对空气质量极大关切，“厚德载雾，自强不吸”等调侃词汇迅速成为热词。中国现实的国情是煤炭一枝独大，而面对“霾锁中国”，煤炭企业又该如何做？就此，《能源评论》记者在两会期间专访了山西煤炭运销集团董事长刘建中，他认为在很长一段时期内，煤炭仍将是中国能源利用的主要方式，那就要认真研究煤炭利用的清洁化和低碳化，这是改善大气环境最现实的选择。     

第二届中国煤炭博览会1908年9月16-19日在太原举办

2008年9月16～19日在中国太原举办第二届中国（太原）煤炭与能源新产业博览会。拟重点邀请世界500强有关煤炭与能源新产业的企业、商界精英、科技院所和行业协会等参会。 煤炭与能源博览会的宗旨是：推进国家以煤炭为基础的能源发展战略的贯彻实施;促进国际煤炭与能源新产业交流合作;实现国际煤炭与能源新产业科工贸互利共赢;引领我国煤炭与能源新产业的发展方向。     

煤基分布式能源技术研究与经济性分析

本文针对我国煤炭应用现状,提出实施能量供给侧结构改革,探索发展基于煤基分布式的多能互补能源系统,以大幅降低污染物排放,并有效提高能量利用水平的可行性.本文分析了分布式能源以及煤基分布式能源的发展现状,对煤基分布式能源节能与环保排放的效果进行了研究,分析表明煤基分布式能源既能明显提升能源利用效率,又能有效降低污染物排放,发展煤基分布式是实施大气污染治理的重要途径之一.     

分布式能源是未来发展重要趋势

<正>8月9日,第十三届中国分布式能源国际论坛在京召开,论坛以"建言新区规划,智慧绿色布局"为主题,重点关注光伏、天然气、地热三个领域在分布式发展中面临的挑战和机遇,旨在为各能源单位交流分布式能源新技术、新装备、新项目等的相关经验提供平台,推动中国分布式能源健康发展、规模发展。     

能源体制改革开创能源互联网时代

中国当前进入能源体制深化改革时期,业内对未来能源格局、“互联网＋能源”等纷纷解读、莫衷一是。回顾了国内外从智慧能源系统到能源互联网的发展历程,阐述了对能源互联网的认识以及能源体制改革对发展能源互联网的意义。未来能源体系由基础能源互联网及更高层级的能源互联网构成,具有开放、平等、互动、共享的特点;以人为本是能源互联网的基本出发点,互联网使得能源系统诸多环节趋于最优化,最终能为每个人提供“最佳”能源服务;能源互联网有望容纳更多可再生能源,天然气分布式能源在其中的备用、调节作用增强;能源互联网代表着先进生产力,有望解决当前能源问题,并催生新型能源服务行业,助力中国社会经济转型。     

中国煤炭工业面临的机遇与挑战

叙述了中国煤炭工业在产量、技术、安全以及控制污染等方面取得的显著成效,指出,上述诸多方面仍面临严峻挑战,根据煤炭在未来较长时期仍将是中国主要能源的格局,提出促进中国煤炭工业健康发展的对策。     

天然气分布式能源在浙江的发展前景分析

进入21世纪以来,浙江省的大气环境质量逐年下降。同时,作为东部沿海经济发达省份,浙江省的能源需求不断增长,2012年底全省电力总装机容量达到6170×104kW,其中火电比例比世界平均水平高出很多,而天然气发电、核电及可再生能源等清洁能源所占比例明显偏少。同时浙江省的煤炭自给率不到0.1%,一旦煤炭供应紧张,将会对电力供应产生很大影响,优化能源结构成为当务之急。分布式能源是解决能源与环境问题的一个重要举措,但当前浙江省还没有真正意义上的天然气分布式能源系统投入商业运行。从严峻的环保形势和能源安全供应的角度考虑,浙江省有发展天然气分布式能源的必要性;而从气源供应、市场需求、政策导向以及管理经验和人才优势来看,浙江省已具备发展天然气分布式能源的可行性。建议要转变观念,做好规划布局,简化审批程序,健全行业立法,充分考虑天然气分布式能源的环境效益,给予装机补贴、天然气差别供应价格及税收减免等优惠政策,通过示范工程的带动效应,有序推进浙江省的天然气分布式能源建设。同时,要做好天然气资源的拓展和储备工作。     

《北京市分布式光伏发电奖励资金管理办法》解读

<正>为进一步加快北京市分布式光伏发电产业发展,优化能源结构,促进首都空气质量改善,今年8月,市财政局、市发展改革委联合印发了《北京市分布式光伏发电奖励资金管理办法》,明确提出,对北京市分布式光伏发电项目予以奖励。《奖励办法》出台以来,受到业内广泛关注。为做好《奖励办法》的解读工作,推进政策落实,10月14日,北京市发展改革委、北京市财政局     

天然气分布式渐行渐近

PM2．5倒逼煤炭消费转型。环境保护压力下,长期依赖的煤炭的能源结构转型迫在眉睫．促进天然气分布式能源发展。     

论绿色建筑与分布式能源

叙述了分布式能源基本概念,分析了分布式能源发展及现状,以及目前国内对于分布式能源产业发展政策及规划,着重分析了分布式能源在绿色建筑评价体系中作用以及分布式能源对绿色建筑项目优势.得出了在中国天然气供应日趋增加,智能电网建设步伐加快,专业化服务公司方兴未艾的大背景下,经过国内10多年的分布式能源研究及示范,天然气分布式能源在中国已具备大规模发展的条件.这为绿色建筑设计提供了1个新的模式,具有广泛的开发及应用前景.     

Ash-forming elements in four Scandinavian wood species. Part 1: Summer harvest

Woody biomass in Finland and Sweden comprises mainly four wood species: spruce, pine, birch and aspen. To study the ash, which may cause problems for the combustion device, one tree of each species were cut down and prepared for comparisons with fuel samples. Well-defined samples of wood, bark and foliage were analyzed on 11 ash-forming elements: Si, Al, Fe, Ca, Mg, Mn, Na, K, P, S and Cl. The ash content in the wood tissues (0.2–0.7%) was low compared to the ash content in the bark tissues (1.9–6.4%) and the foliage (2.4–7.7%). The woods’ content of ash-forming elements was consequently low; the highest contents were of Ca (410–1340 ppm) and K (200–1310), followed by Mg (70–290), Mn (15–240) and P (0–350). Present in the wood was also Si (50–190), S (50–200) and Cl (30–110). The bark tissues showed much higher element contents; Ca (4800–19,100 ppm) and K (1600–6400) were the dominating elements, followed by Mg (210–2400), P (210–1200), Mn (110–1100) and S (310–750), but the Cl contents (40–330) were only moderately higher in the bark than in the wood. The young foliage (shoots and deciduous leaves) had the highest K (7100–25,000 ppm), P (1600–5300) and S (1100–2600) contents of all tissues, while the shoots of spruce had the highest Cl contents (820–1360) and its needles the highest Si content (5000–11,300). This paper presented a new approach in fuel characterization: the method excludes the presence of impurities, and focus on different categories of plant tissues. This made it possible to discuss the contents of ash element in a wide spectrum of fuel-types, which are of large importance for the energy production in Finland and Sweden.     

Contents in Volume 23,2014

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NEXT GENERATION ENGINEERED MATERIALS FOR ULTRA SUPERCRITICAL STEAM TURBINES

正1 ABSTRACT To reduce the effect of global warming on our climate,the levels of CO2emissions should be reduced.One way to do this is to increase the efficiency of electricity production from fossil fuels.This will in turn reduce the amount of CO2emissions for a given power output.Using US practice for efficiency calculations,then a move from a typical US plant running at 37%efficiency to a 760℃/38.5 MPa(1 400/5 580 psi)plant running at 48%efficiency would reduce CO2emissions by 170kg/MW.hr or 25%.     

Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions

Natural gas is a fossil fuel that has been used and investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. Compared with conventional gasoline engines, SI engines using natural gas can run at higher compression ratios, thus producing higher thermal efficiencies but also increased nitrogen oxide (NO_x) emissions, while producing lower emissions of carbon dioxide (CO₂), unburned hydrocarbons (HC) and carbon monoxide (CO). These engines also produce relatively less power than gasoline-fueled engines because of the convergence of one or more of three factors: a reduction in volumetric efficiency due to natural-gas injection in the intake manifold; the lower stoichiometric fuel/air ratio of natural gas compared to gasoline; and the lower equivalence ratio at which these engines may be run in order to reduce NO_x emissions. High NO_x emissions, especially at high loads, reduce with exhaust gas recirculation (EGR). However, EGR rates above a maximum value result in misfire and erratic engine operation. Hydrogen gas addition increases this EGR threshold significantly. In addition, hydrogen increases the flame speed of the natural gas-hydrogen mixture. Power levels can be increased with supercharging or turbocharging and intercooling. Natural gas is used to power CI engines via the dual-fuel mode, where a high-cetane fuel is injected along with the natural gas in order to provide a source of ignition for the charge. Thermal efficiency levels compared with normal diesel-fueled CI-engine operation are generally maintained with dual-fuel operation, and smoke levels are reduced significantly. At the same time, lower NO_x and CO₂ emissions, as well as higher HC and CO emissions compared with normal CI-engine operation at low and intermediate loads are recorded. These trends are caused by the low charge temperature and increased ignition delay, resulting in low combustion temperatures. Another factor is insufficient penetration and distribution of the pilot fuel in the charge, resulting in a lack of ignition centers. EGR admission at low and intermediate loads increases combustion temperatures, lowering unburned HC and CO emissions. Larger pilot fuel quantities at these load levels and hydrogen gas addition can also help increase combustion efficiency. Power output is lower at certain conditions than diesel-fueled engines, for reasons similar to those affecting power output of SI engines. In both cases the power output can be maintained with direct injection. Overall, natural gas can be used in both engine types; however further refinement and optimization of engines and fuel-injection systems is needed.     

Controls on the Karaha–Telaga Bodas geothermal reservoir,Indonesia

Karaha–Telaga Bodas is a partially vapor-dominated, fracture-controlled geothermal system located adjacent to Galunggung Volcano in western Java, Indonesia. The geothermal system consists of: (1) a caprock, ranging from several hundred to 1600 m in thickness, and characterized by a steep, conductive temperature gradient and low permeability; (2) an underlying vapor-dominated zone that extends below sea level; and (3) a deep liquid-dominated zone with measured temperatures up to 353 °C. Heat is provided by a tabular granodiorite stock encountered at about 3 km depth. A structural analysis of the geothermal system shows that the effective base of the reservoir is controlled either by the boundary between brittle and ductile deformational regimes or by the closure and collapse of fractures within volcanic rocks located above the brittle/ductile transition. The base of the caprock is determined by the distribution of initially low-permeability lithologies above the reservoir; the extent of pervasive clay alteration that has significantly reduced primary rock permeabilities; the distribution of secondary minerals deposited by descending waters; and, locally, by a downward change from a strike-slip to an extensional stress regime. Fluid-producing zones are controlled by both matrix and fracture permeabilities. High matrix permeabilities are associated with lacustrine, pyroclastic, and epiclastic deposits. Productive fractures are those showing the greatest tendency to slip and dilate under the present-day stress conditions. Although the reservoir appears to be in pressure communication across its length, fluid, and gas chemistries vary laterally, suggesting the presence of isolated convection cells.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

Assessment methods of material ageing using Sdobyrev''s creep rupture model

The physical aspects of the activation energy, in higher and high temperatures, of the metal creep process were examined. The research results of creep-rupture in a uniaxial stress state and the criterion of creep-rupture in biaxial stress states, at two temperatures, are then presented. For these studies creep-rupture, taking case iron as an example the energy and pseudoenergy activation was determined. For complex stress states the criterion of creep-rupture was taken to be Sdobyrev's, i.e. σ_red = σ₁ β + (1 − β)σ_i, where: σ₁-maximal principal stress, σ_i-stress intensity, β-material constant (at variable temperature β = β(T)). The methods of assessment of the material ageing grade are given in percentages of ageing of new material in the following mechanical properties: 1) creep strength in uniaxial stress state, 2) activation energy in uniaxial stress state, 3) criterion creep strength in complex stress states, 4) activation pseudoenergy in complex stress states. The methods 1) and 3) are the relatively simplest because they result from experimental investigations only at nominal temperature of the structure work, however, for methods 2) and 4) it is necessary to perform the experimental investigations at least at two temperatures.