关于GB××××─××《锅壳锅炉受压元件强度计算》标准若干情况的介绍（一）

关于ＧＢ××××─××《锅壳锅炉受压元件强度计算》标准若干情况的介绍（一）刘复田（上海工业锅炉研究所）ＧＢ××××─××《锅壳锅炉受压元件强度计算》标准终放于１９９４年７月正式上报了，这是工业锅炉行业中的一件颇受大家关心的大事。很多厂来函来电河问该标...     

关于GB××××－××《锅壳锅炉受压元件强度计算》标准若干情况的介绍（二）

关于ＧＢ××××－××《锅壳锅炉受压元件强度计算》标准若干情况的介绍（二）刘复田（上海工业锅炉研究所）９矩形集箱的计算９．１符号说明本章所用符号的意义和单位如下：ｔｍｉｎ—最小需要厚度，ｍｍｓ″—斜向相邻两孔的节距，ｍｍｔ—取用厚度、实际测量厚度，ｍ...     

太阳能测试中的误差与有效数字

在太阳能的利用中,不免要出现许多测量量,包括直接测量量和间接测量量。但这些测量量的表示并不是随心所欲的,而是要受到一定规律制约的。这些规律就是误差理论和有效数字,一个正确表示的测量量,可以告诉我们该量所能达到的精确程度,甚至可以由此判断出测量仪器的精度。因此,在测量量的表示中,正确地运用误差理论和有效数字是十分重要的,但目前在太阳能的工程测试中,还存在着许多无视这一点的现象。如用同一个测温仪测出的温度,有的表示为××℃,有的写成×××℃,还有写成××××℃的;太阳热水器日效率写成×××%、××××%和×××××…     

浅谈本钢锅炉节煤的有效途径

浅谈本钢锅炉节煤的有效途径本溪钢铁公司兆春民，杨仲志１前言本钢是一个拥有１５×１０￣４职工，年产２５０×１０￣４钢，３００×１０￣４ｔ铁的全国特大型钢铁联合企业。每年耗原煤在５００×１０￣４ｔ以上，是辽宁省和本溪市的耗能大户，其中仅工业燃煤锅炉一项每...     

发展热电 促进节能

发展热电促进节能浙江省经委江家林浙江省能源资源贫乏，１９９２年全省消耗３２９０×１０￣４ｔ标煤，９０％是靠外省调运的，耗煤炭３１５０×１０￣４ｔ，自产１４３×１０￣４ｔ，自给率仅４．５％，所以节约能源应是我省发展国民经济的长远战略方针。这几年我省除抓...     

我国天然气发电规划概况

新疆和田天然气电站工程已开建，首期５０MW于２００１年投运。陕西靖边电厂总容量２×３００MW。兰州燃气电厂开建，首期总容量６００MW。湖北武昌热电厂、沙市热电厂等７台机组将“煤电”或“油电”改为“气电”，总容量约６５０MW。福建拟建一、二套１２００～２４００MW液化天然气电厂。广西钦州使用南海天然气计划建１４００MW电厂。广东新建惠州电厂一期３×３３０MW；前湾电厂３×３５０MW电厂。深圳东部进行“大代小”改造，装机容量１×３００MW。香港计划扩建南丫岛电厂，２０１２年前新装２×３００MW联合循环机组，并将…     

感应电热设备的设计(17)

４．５　有色金属（非磁性炉料）工频加热炉计算举例通过此例题，一是要说明有色金属，非磁性钢和磁性炉料热态计算公式的应用；二是说明本套计算公式适用于不同频率（包括工频）加热炉的计算。已知紫铜炉料，尺寸为１９５ｍｍ×５００ｍｍ，由室温加热至９００℃，要求ΔＴ≤３０℃，生产率为３０根／ｈ。（１）估算设备功率炉料质量ｍ＝π４Ｄ２２ｌ２ｒ＝π４×１９．５２×５０×８．９×１０－３＝１３３ｋｇ。按３０根／ｈ，即２ｍｉｎ出一根，有色金属工频加热一般均采用停电出料，故去除辅助时间１５ｓ，实际加热时间为ｔ＝１０５…     

大型全耐火纤维炉衬燃油热处理炉

某厂安装了一台１０ｍ×１０ｍ×２０ｍ　全耐火纤维炉衬燃油热处理炉。该炉装有两台燃烧能力为６．２８×１０￣６ｋＪ／ｈ燃油高速燃烧器，用Ｄｃｐ２１１数字程控器和电动调节阀实现升、降温速度自动程序控制和温度自动控制。用１６支热电偶测温，炉温均匀性和控温精度均在±１０℃范围内。     

开展电炉钢节电竞赛 促进行业节能

开展电炉钢节电竞赛促进行业节能浙江省冶金总公司夏晓林，李永伟１９９４年我省共产钢１３５×１０￣４ｔ，其中电炉钢６３．×１０￣４ｔ，其中７家钢厂３９．３×１０￣４ｔ，占总产量的６２％左右。这７家企业现有１．５～５ｔ小电炉共计１７座，其中５ｔ占１５座，１...     

常见能量单位换算

GJ( 10 9焦耳 )kWh(千瓦时 )kcal(大卡 )Btu(英热单位 )GJ 12 77.77 2 .389× 10 694 7.8× 10 3kWh 3.6× 10 -3 186 0 3412kcal 4 .183× 10 -61.17× 10 -3 13.96 8Btu 1.0 5 5× 10 -62 .93× 10 -40 .2 5 2 1　注 :kcal和Btu为非标单位 ,已废弃。常见能量单位换算     

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.     

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.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.     

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.     

Decomposition of limestone in a solar reactor

The thermal decomposition of limestone has been selected as a model reaction for developing and testing an atmospheric open solar reactor. The reactor consists of a cyclone gas/particle separator which has been modified to let the concentrated solar energy enter through a windowless aperture. The reacting particles are directly exposed to the solar irradiation. Experimentation with a 60 kW reactor prototype was conducted at PSI's 90m² parabolic solar concentrator, in a continuous mode of operation. A counter-current flow heat exchanger was employed to preheat the reactants. Eighty five percent degree of calcination was obtained for cement raw material and 15% of the solar input was converted into chemical energy (enthalpy).The technical feasibility of the solar thermal decomposition of limestone was experimentally demonstrated. The use of solar energy as a source for high-temperature process heat offers the potential of reducing significantly the CO₂ emissions from lime producing plants. Such a solar thermochemical process can find application in sunny rural areas for avoiding deforestation.