昌乐热电5×75t／h锅炉白泥脱硫工艺

采用喷射鼓泡塔湿法工艺对昌乐盛世热电有限责任公司5×75t／h锅炉烟气脱硫，采用生产纯碱产生的碱渣（以下称白泥）作脱硫剂，从而有效替代了传统石灰石-石膏工艺的脱硫剂石灰石。既节约了脱硫运行成本，达到了理想的脱硫效果，也解决了白泥处理的问题。文中结合本项目，重点介绍白泥脱硫工艺。此脱硫方法可以在具备白泥原料电厂中的小规模机组烟气治理工程中大力推广。     

白泥与石灰石粒径差异对脱硫性能的影响

采用能量色散X射线谱(EDS)、X射线荧光光谱(XRF)和扫描电子显微镜(SEM)等表征手段研究白泥和石灰石的理化特性,并分析了颗粒粒径对2种脱硫剂脱硫性能和脱硫产物的影响.以质量传递方程为基础建立脱硫浆液CaCO3消溶数学模型,分析浆液中CaCO3粒径分布、质量分数、温度和颗粒球形度对消溶速率的影响.结果 表明:与石灰石相比,白泥粒径小,粒度分布集中,在相同条件下白泥中CaCO3的消溶速率、浆液反应活性和脱硫效率均更优,但白泥浆液的溶氧能力较低;经过充分预处理后的白泥可以脱硫,其产生的石膏晶型优于石灰石;采用白泥脱硫时产生的石膏具有粒径大、粒度分布集中的特点;将白泥和石灰石混合脱硫时容易造成石膏脱水困难,主要原因是两者产生的石膏粒径差异大,混合浆液中盐分质量分数高,且白泥脱硫产生的石膏会包裹住石灰石,产生"壳效应"等.     

德开发成功烟气脱硫新技术

德国一家公司正在建设一座采用海水进行烟气脱硫的装置。此装置包括两台烟气处理能力为2.1×10~6m~3/h时的设备,脱硫率可达95％。由于是采用海水脱硫,故投资费用比传统的石灰法脱硫低20％。 烟气先经过热交换器后进入喷射塔,在塔内用冷海水喷淋烟气,烟气中的SO_2     

活性炭填料在海水脱硫中催化氧化作用的试验研究

分析了以拉西环和活性炭为填料时海水脱硫效率及排出液中亚硫酸根离子残余率的变化规律;同时研究了入口SO2浓度及填料高度对脱硫效率及排出液中亚硫酸根离子残余率的影响.结果表明:在相同工况下,以活性炭为填料时的脱硫效率明显高于以拉西环为填料时,且排出液中亚硫酸根离子的残余率明显低于以拉西环为填料时,从而证明了活性炭填料在海水脱硫中具有催化氧化SO2为稀硫酸的作用;以拉西环为填料时,入口SO2浓度越高,越不利于SO2的脱除,脱硫效率下降;而以活性炭为填料时,入口SO2浓度为10-3时的脱硫效率比入口SO2浓度为5×10-4时略有提高,说明活性炭催化氧化SO2的作用与海水脱硫作用同时发生,高浓度SO2时的脱硫效率反而较高.     

烟气海水脱硫技术实现重要突破

由东方锅炉厂自主开发并以总承包建设的国产首台配30万kW燃煤机组烟气海水脱硫系统，2006年10月在厦门嵩屿电厂正式投运。 经有关单位测试，机组脱硫率大于95％，各项指标均达到了国际领先水平。该项目的成功研发，突破了中国海水脱硫达标排放这一技术瓶颈，标志着国内大型燃煤机组海水脱硫环保关键技术和设备国产化实现了突破。     

烟气海水脱硫技术实现重要突破

由东方锅炉厂自主开发并以总承包建设的国产首台配30万kW燃煤机组烟气海水脱硫系统，2006年10月在厦门嵩屿电厂正式投运。 经有关单位测试，机组脱硫率大于95％，各项指标均达到了国际领先水平。该项目的成功研发，突破了中国海水脱硫达标排放这一技术瓶颈，标志着国内大型燃煤机组海水脱硫环保关键技术和设备国产化实现了突破。     

石灰石_石膏湿法烟气脱硫过程的试验研究

利用所建立的并流有序降膜式湿法脱硫装置,对石灰石-石膏湿法烟气脱硫过程进行了试验研究。试验结果表明:沿烟气行程上,脱硫率上升趋势逐步减弱,脱硫率较高时,再提高脱硫率,吸收段高度或液气比要大幅增加,火电厂机组在确定脱硫系统脱硫率时,应有适当选择;脱硫浆液pH值下降,且在吸收塔入口至0.5 m范围内,浆液pH值下降迅速,而后下降变缓;浆液中石灰石含量下降趋势逐步增强;同时浆液中Ca2 、六价硫S6 及四价硫S4 浓度均增加,Ca2 、S6 浓度增加使得石膏过饱和度有所增加。     

影响600MW机组湿法烟气脱硫装置厂用电率主要因素分析

针对影响600MW机组湿式石灰石-石膏法脱硫岛厂用电率的主要因素。对煤收到基硫分高低、烟气量大小、采用的不同脱硫设备等对脱硫厂用电率的影响进行了详细分析，国内现设计的600MW机组采用湿法烟气脱硫工艺时，设计煤种为高热值．低硫分（硫分低于0．7％），并且脱硫烟气系统不设GGH或设GGH时，脱硫厂用电率为1.0％～1．1％；当采用低热值．高水分设计煤种，脱硫厂用电率在1．7％以上。当采用高硫分（硫分高于4％）、中等热值的煤种时，脱硫厂用电率最高可达1．98％。应根据工程具体煤种情况核算脱硫系统主要设备（增压风机、浆液循环泵、磨粉机、真空泵、氧化风机等主要设备）的轴功率。在初步设计阶段核算脱硫部分厂用电率后，完成湿式石灰石-石膏法脱硫岛脱硫部分厂用变容量的选择。     

火电厂海水烟气脱硫的探讨

海水烟气脱硫是仅用天然的海水作为烟气中SO2吸收剂的一种湿式烟气脱硫方法。基于国内外海水脱硫的实践，分析了海水脱硫的机理，并对其工艺进行论述，指出其特点和注意的问题。     

铁基添加剂调质石灰石用于O2/CO2燃煤脱硫的实验研究

利用水平高温管式炉实验装置探讨了O2/CO2气氛下铁基添加剂调质石灰石燃烧中脱硫特性。实验结果表明:铁基添加剂能改善石灰石的脱硫性能,950℃时氧化铁与二茂铁分别可以将石灰石的脱硫率由56.57%提高到61.97%和70.46%;铁基调质石灰石的脱硫性能受温度、钙铁摩尔比以及煤的含硫量的影响,850℃至950℃燃烧温度内,石灰石的脱硫率随温度升高而升高,氧化铁与二茂铁调质石灰石均在钙铁摩尔比为20时取得最大脱硫率。铁基添加剂可以改善煤的着火和燃烧性能。     

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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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.     

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%.     

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.     

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.     

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.     

Exergetic evaluation of 5 biowastes-to-biofuels routes via gasification

This paper presents the exergy analysis results for the production of several biofuels, i.e., SNG (synthetic natural gas), methanol, Fischer–Tropsch fuels, hydrogen, as well as heat and electricity, from several biowastes generated in the Dutch province of Friesland, selected as one of the typical European regions. Biowastes have been classified in 5 virtual streams according to their ultimate and proximate analysis. All production chains have been modeled in Aspen Plus in order to analyze their technical performance. The common steps for all the production chains are: pre-treatment, gasification, gas cleaning, water–gas-shift reactions, catalytic reactors, final gas separation and upgrading. Optionally a gas turbine and steam turbines are used to produce heat and electricity from unconverted gas and heat removal, respectively. The results show that, in terms of mass conversion, methanol production seems to be the most efficient process for all the biowastes. SNG synthesis is preferred when exergetic efficiency is the objective parameter, but hydrogen process is more efficient when the performance is analyzed by means of the 1st Law of Thermodynamics. The main exergy losses account for the gasification section, except in the electricity and heat production chain, where the combined cycle is less efficient.     

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.