抽油机井一体化节能技术在油田中应用

抽油机是目前采油生产中的主要抽油设备,同时也是油田耗能的主要设备。将抽油机一有杆泵抽油系统分为地面及井下两部分,根据抽油机井光杆功率及电网向抽油机系统输入的总电能,分析得出抽油机井地面能耗约占总能耗的30%,地下能耗约占总能耗的70%,地下能耗节能潜力较大。地下损失能量主要包括黏滞损失功率和滑动损失功率,滑动损失功率与冲程和冲次成正比,黏滞损失功率与冲程和冲次的平方成正比。在抽油机井能耗影响因素中,运行参数是易于控制的主要影响因素。因此,确定了"大泵径、长冲程、低冲次"的地面及地下一体化优化节能思路。累计实施1152井次,系统效率由优化前的26.17%提高到30.81%,节电率达15.09%,年节电1216.86×104kW.h,节约电费776.48万元,加上节约作业费用和维护费用,年获经济效益1420.28万元。     

运用高转矩节能电机优化抽油机运行效率

抽油机是油田使用最普及的设备,提高其运行效率是抽油机井节能挖潜增效的有效途径。根据不同抽油机电机运行状态下参数的变化情况,论述了抽油机运行过程中的主要动力设备电动机的运行规律、工作特性,阐述了在抽油机的设计和改造过程中,应以降低抽油机的载荷波动参数为目标,使电机适应于抽油机交变载荷变化的要求,提高功率利用率。同时,对拖动抽油机的异步电动机、同步电动机的机械载荷特性的合理匹配提出建议,用以指导今后抽油机井节能技术的推广应用。     

油田机采系统整体节能潜力分析及优化

大庆油田第八采油厂为了实现"十一五"期间将机采系统单井日耗电降低在80kW.h/d以下的目标,对全厂新投产井和老油田生产井的机采系统进行了理论计算和现场情况分析,制定并实施了有针对性的节能措施。对于新投产井,利用最佳冲程和冲次校核载荷、扭矩,优选机型及装机功率,对抽油机、电机进行优化匹配。对20个新区块采油工程方案中2272口井采取优选节能措施后,平均设计载荷和装机功率分别降低了28kN、9.8kW,平均单井日耗电由措施前的85.7kW.h/d降低至65kW.h/d,累计节电5600×104kW.h。对于老油田生产井,通过采取优化抽汲参数、加强盘根盒管理、进行抽油机节能改造等措施,并试点应用了间歇采油技术、往复式潜油泵采油技术、智能抽油装置采油技术,使全厂机采系统平均单井日耗电、吨油电耗降低到了78.3kW.h/d、58.6kW.h/t,实现了节能目标。     

电潜柱塞泵在低渗透油田的应用

肇州油田为低渗透油田,单井产量低,自投产以来一直采用抽油机—深井泵举升系统进行开采,存在理论排量过大、泵效低,杆系统断、脱、偏磨现象严重,机械结构复杂,系统效率低等问题。往复式电潜柱塞泵系统主要由直线电机、配套抽油泵、变频控制系统三大部分组成,举升工艺驱动方式由地面转向地下,地面无可动设备,减少设备管理工作量的同时降低了工人劳动强度;无杆举升克服了杆系统故障造成的检泵作业,消除了举升杆柱所需能耗。在肇413区块的现场应用试验结果表明:电潜柱塞泵举升可以满足油井的排量需求,平均泵效达到83.1%。电潜柱塞泵举升与抽油机举升相比,理论排量下降75%以上,平均节电65%,斜井节电可达85%;单井节省投资4.4万元,单井每年可降低维护运行费用1.1万元。建议今后在低渗透油田低产井加大电潜柱塞泵应用规模。     

RS抽油机节能减速器在A油田的应用

A油田部分油井存在供液不足、泵效低、耗电高等问题。要提高油井泵效和节能效果,就需要降冲次。在成本、改造技术难度等方面对比了各种降冲次方法的优缺点,最终确定采用安装节能减速器的方法来降低冲次。在抽油机的电机和减速箱之间增加一套辅助减速装置即为节能减速器。减速器可大幅降低抽油机的惯性负荷,因此能起到一定的节能作用。介绍了节能减速器安装尺寸的确定方法。A油田在126口井安装、应用了节能减速器。安装节能减速器后,126口井平均消耗功率由3.526kW下降到3.000kW,综合节电率达到14.08%;系统效率由5.943%上升到7.116%;平均单井日节电13.2kW.h,预计可实现年节电60.7×104kW.h;抽油机运转较平稳,减小了惯性载荷,从而减少了抽油机的机械故障;优化了油井运行参数,提高了泵效,减少了杆管磨损。     

游梁式抽油机SURF系统过程优化与柔性运行技术应用

抽油机作为机械举升的主要方式之一,其能耗的合理控制一直是困扰采油工程技术人员的难题。依据"非匀速最佳举升逻辑技术",研发的SURF抽油机系统过程优化与柔性运行设备,利用各类传感器来完成动态参数的采集,由单片机来完成中央处理与控制,利用矢量变频器来完成电机运行速度的调整。该设备可在不对抽油机四连杆结构进行任何改动的情况下,达到提高井下效率,确保系统按需运行,降低单产设备损耗率和能耗水平的综合目的。将该设备应用于现场22口井,对比17口井(未对比5口井均为注水受效井,产液量变化较大),平均冲次降低0.84min-1,平均产液增加3.36t/d;平均沉没度基本稳定,平均有功功率降低2.53k W,平均折算当量功率降低3.09k W,平均吨液百米耗电降低1.00k W·h,平均系统效率上升10.25个百分点。该设备可为油田节能管理提供有力的技术支持。     

降低抽油机井地面能耗技术在安塞油田的应用

针对安塞油田抽油机井地面能耗高的生产现状,以节能降耗为目标,分析了机采井地面能耗高的影响因素,阐述了降低地面能耗的途径及措施.通过抽油机平衡优化、合理匹配电机、加强抽油机井生产管理等综合治理措施及无功补偿装置、节能型变压器、抽油机节电箱、集中控制节能装置、高效电机、节能抽油机等节能设备的应用,提高抽油机井配电质量、提高电机效率及提高抽油机效率,从而降低了安塞油田抽油机地面能耗.     

低转速电机节能效果分析

大庆外围油田举升工艺主要采用抽油机深井泵作业,随着开采时间的延长,油井产量逐年降低,部分油井存在"大马拉小车"现象。而目前采用的几种降低冲次的方法,节能效果均不理想。为改善杆管的受力状况,提高泵效,降低能耗,开展了低转速电机现场试验。探讨了外围油田应用低转速电机的工作原理,现场试验应用36口井,试验前后对比,平均冲次下降1.23次/min,平均动液面上升59.91m,平均泵效提高4个百分点,平均单井日节电36kW.h,单井全年可节电11826kW.h,平均系统效率提高2.0个百分点。采用低转速电机后,油井的产量稳定,说明更换低转速电机可以满足生产需要,且达到了"三提一降"的良好试验效果。更换低转速电机后,示功图比较饱满,闭合面积大,说明抽油机大部分时间都在做有用功,且降低了抽油机的动载荷,改善了抽油机的运转性能。应用低转速电机,降低了电机的输入功率和油井的吨液耗电;降低了抽油泵的容积损失,改善了泵的充满程度,提高了泵效;减少了杆管的磨损次数,改善了杆管的受力状态,延长了杆管寿命。     

十屋采油厂机采系统效率优化及发展方向

抽油机井采油是油田主要的机械采油方式,抽油机也是油田主要耗能设备之一。抽油机采井系统效率是抽油机在提液过程中其有效功与系统输入能量的比值,反映抽油机井采油的能耗水平,是机械采油经济技术指标之一。介绍机采井系统效率的计算方法、影响因素,并对提高机采井系统效率的措施进行探讨。提高机采井系统效率,是降本增效的有效途径。     

异步电机矢量控制技术在抽油机井的应用

针对大庆油田杏北开发区部分抽油机井机井能耗高、系统效率低等问题,试验应用异步电动机矢量控制装置,以降低抽油机井能耗,提高系统效率.矢量控制技术是通过理论算法将定子电流等效为励磁电流和转矩电流,使异步电机具有和直流电机相似的性能.该技术克服了普通变频器低速负载性差的不足,具有低速大转矩特征,实现了抽油机井软启动、负载跟踪、功率自动匹配和抽油杆运行轨迹优化.将矢量控制技术应用于不同产液、不同供液状况的抽油机井.现场应用结果表明:5口试验井均达到了节电、提效的目标,平均单井功率因数提高0.47,吨液百米节电率达19.5％,泵效提高4.1个百分点,系统效率提高6.7％;供液不足的井泵效大幅提高,低系统效率井系统效率明显提高.异步电机矢量控制技术的应用,为高含水后期油田的高效举升提供了技术支撑.     

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.     

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.     

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.     

Production of hydrogen from sewage biosolids in a continuously fed bioreactor: Effect of hydraulic retention time and sparging

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H₂ kg⁻¹ VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min⁻¹ successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H₂ kg⁻¹ VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production.     

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。