乳化燃油技术在稠油油田注汽锅炉运行中的应用

热采注汽锅炉是稠油开采中的主要耗能设备。单台SG-50型注汽锅炉日燃烧稀原油达26吨多。注汽锅炉燃料渣油替代技术的研究从一定程度上缓解了由于燃烧稀油造成的能耗问题，相继在井楼油田四个注汽站推广应用。但是渣油、稀油混配比例偏低的难题一直未能解决，制约了稠油开采的节能水平。燃油乳化技术的应用，提高了渣油、稀油的混配比例，大大减少了稀油的用量，同时减少了燃烧过程中硫化物的排放量，有一定降低污染的作用。     

国产注汽锅炉用于多佛油田开发的适应性分析

为满足中石油加拿大多佛油田稠油开采需求,通过对国内应用较好的注汽锅炉炉型从锅炉布置、锅炉用水水质、工艺适应性、环保适应性等方面分析论证,发现国产燃气直流注汽锅炉在多佛油田应用尚需进行技术升级;而基于分段蒸发技术的汽包注汽锅炉具有成本低、适应性强、环保、节能等优点,现场试验成功后在多佛油田具有较为广阔的应用前景.     

燃气汽包注汽锅炉的低氮燃烧与模块设计优化研究

注汽锅炉是用于稠油注蒸汽热采的专用设备。文中以计划用于加拿大的国产燃气汽包注汽锅炉为例,基于加拿大稠油开发的技术需求,介绍了注汽锅炉的低氮燃烧和模块设计优化研究。锅炉采用天然气低氮燃烧器,配合燃气和空气预混、分级配风、炉内再循环和炉外烟气再循环等多种先进燃烧技术,可以实现低氮排放。结合运输要求,锅炉受热面采用成熟的模块化设计,降低了现场安装量。     

提高注汽锅炉热效率配套技术研究及应用

1概述稠油开采过程中,锅炉燃料消耗占生产总成本的48%以上,因此降低锅炉能耗,提高锅炉热效率,是降低稠油开采成本的主要方向。新疆油田公司重油公司现有注汽锅炉78台,平均热效率为80.84%,通过82台次注汽锅炉的测试,注汽锅炉热损失主要有三项:排烟热损失占总热损失的90.5%～97.5     

稠油热采注汽锅炉弱爆炸除灰技术应用研究

本文针对稠油热力开发在用23t／h工业注汽锅炉燃烧渣油过程中出现的炉管结渣和积灰严重、导致热效率下降的状况，通过技术调研，根据弱爆炸吹灰原理，经过优化设计，首次在稠油油田注蒸汽锅炉上应用弱爆吹灰技术，确保注汽锅炉的高效运行，有明显的节能效果。     

提高注汽锅炉排量研究

注汽锅炉是稠油热注开采的主要设备,也是热注工艺过程的能耗大户。基于某采油厂燃油注汽锅炉将燃料改为天然气,锅炉的运行蒸汽排量均较低,性能得不到充分发挥。为了提高注汽锅炉的效率,在当前运行基础上将排量提高10%,同时应用注汽锅炉蒸汽干度在线监测装置对锅炉的蒸汽干度等运行参数进行监控,提高锅炉效率,保证锅炉安全运行,降低锅炉运行成本。     

国内油田注汽锅炉发展现状与分析

随着国内外稠油热采技术的应用以及油田注汽作业环境的变化,注汽锅炉也朝着大容量的车载和撬装化方向发展。介绍了国内几种典型的注汽锅炉和辅助技术的性能和特点,包括车载注汽锅炉、撬装注汽锅炉、超(超)临界压力注汽锅炉等。结合注汽锅炉的应用特点,分析了车载、撬装注汽锅炉需解决的关键技术难点,对超临界注汽锅炉的研制具有一定的借鉴意义。     

浅谈燃用细颗粒燃料内循环流化床锅炉的设计实践

近年来，工业锅炉及小容量电站锅炉大量采用了水冷旋涡内循环流化床的形式。这种锅炉有结构紧凑、启停速度快、负荷调节能力强、燃烧效率和热效率高、燃料适应性广(尤其能燃用其它炉型无法燃烧的造气炉渣等劣质燃料)、脱硫效率高、节能环保等特点。     

燃油注汽锅炉燃烧SO_2和NOx生成与排放特征研究

为了研究燃油注汽锅炉SO_2和NOx生成和排放特征,对41个油田燃油样品进行检测,发现大部分原油含硫量大于0.07%,含氮量主要集中在0.5%～1%;燃烧试验发现,低硫低氮的纯梁HGX101油直接燃烧后的烟气排放能满足排放要求,在完全燃烧条件下,降低燃烧空气量可有效降低NOx排放;测量炉内的温度场发现最高温度在1500℃左右,生成的NOx中既含有燃料型NOx,也有热力型NOx。     

燃煤注汽锅炉“烟尘超净”排放工艺设想

针对国内燃煤注汽锅炉高硫、高灰、烟气量大等特点,通过烟气净化技术实现多种污染物协同减排是适合我国国情的可行的技术路线。针对燃煤注汽锅炉污染物排放特点,提出"炉内喷钙+炉后半干法脱硫除尘一体化+SNCR"烟尘处理工艺,为燃煤注汽锅炉烟尘"超净排放"技术提供参考,实现燃煤注汽锅炉烟尘、SO_2和NO_X同时超低排放。     

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.