催化裂化重汽油临氢脱砷剂的研究与开发

针对催化汽油砷化物脱除需要,开发一种以大孔γ-Al_2O_3为载体的双金属催化裂化重汽油临氢脱砷剂,并采用XRD和全自动比表面积及孔隙度分析仪对脱砷剂进行表征。考察脱砷剂活性、原料适应性及反应温度、体积空速等工艺条件对脱砷性能的影响。结果表明,该临氢脱砷剂具有较高的脱砷活性(≮85%)和脱砷选择性(≮95%),烯烃基本不饱和;提高反应温度和降低空速有助于提高脱砷剂脱砷活性,烯烃饱和活性基本不受影响。     

A parametric study of polymer membrane electrolyser performance,energy and exergy analyses

In this paper, a mathematical model is developed to study the performance of a polymer membrane electrolyser (PEM) and the effect of different parameters including operating temperature, cathode pressure, membrane thickness, the width and height of channel and current density on the performance and energy and exergy efficiency of PEM electrolyser are investigated. In addition to the resistance overvoltage of components, the concentration overvoltage is modeled using an accurate equation. The model is validated against experimental data. The results indicate that by increasing current density, the voltage of the electrolyser increases, and energy and exergy efficiencies reduce. Increase of temperature from 313 K to 353 K, and decrease of cathode pressure from 40 bar to 1 bar lead to decrease of voltage of the PEM electrolyser by 8.3% and 4.8%, respectively. Moreover, energy and exergy efficiencies increase between 2% and 6% in the range of working temperature and pressure. It is concluded that decrease of membrane thickness, height and width of channel, and increase of exchange current density of the anode and cathode electrodes lead to decrease of voltage of the electrolyser and increase of energy and exergy efficiencies. However, the effect of temperature and cathode pressure and the exchange current densities is greater than the effect of geometric parameters.     

Initialization of DFIG wind turbines with a phasor‐based approach

The objective of this paper is to propose a simple approach to solve the steady state of a wind turbine (WT) equipped with a doubly fed induction generator (DFIG), which can be used to initialize dynamic studies of the machine. The idea is to model the rotor‐side converter (RSC) as a constant current source connected to the rotor of the DFIG. The resulting equivalent circuit consists of a voltage source in series with a reactance, which makes it possible to obtain simple phasor expressions that can be used to obtain the Park components of the variables. The proposed method is compared with the traditional Newton–Raphson algorithm, showing that it is easier and faster to implement, as it makes use of the phasor expressions and it does not require an iterative process to obtain the final solution. Finally, the results of the proposed method are used to simulate a 2‐MW DFIG‐based WT under three‐phase faults, considering three different WT‐operating points. In these simulations, the idea of constant rotor current is extrapolated to the entire event. The simulated results show that both current at torque peaks are reduced. The analytical study and the simulations have been carried out in Matlab ?.     

Effects of fuel inlet boundary condition on aromatic species formation in coflow diffusion flames

In a number of previous numerical studies, the fuel inlet velocity boundary conditions (BC) of coflow diffusion flames were specified at the exit of the fuel nozzle with a parabolic velocity profile. Such choices were based on the assumption that the flow inside the vertical fuel tube is fully developed and the buoyancy has negligible impact on the fuel flow at the nozzle exit. These assumptions, however, might not hold in practical experiments. This study demonstrates it is necessary to account for the effect of inlet BC location to accurately predict the nozzle exit velocity profile as well as the velocity, temperature profiles downstream, which are prerequisites for meaningful polycyclic aromatic hydrocarbon (PAH) and soot prediction in coflow diffusion flames. In particular, laboratory-scale laminar coflow diffusion flames at atmospheric pressure have been studied computationally with a focus on the effects of the fuel inlet velocity profile on PAH formation. Two sets of simulations were conducted which differ in the location specified for the fuel inlet boundary. In the first case, the fuel inlet boundary was specified at the nozzle exit while in the second case it was specified at a distance of 7 cm upstream of the nozzle exit. Parabolic velocity profiles were specified for both cases. In each set of simulations, flames with three different fuels (methane, ethylene and propane) were tested. Detailed high-temperature reaction mechanisms accounting for the formation of aromatic species were employed. The results showed that the fuel inlet BC location notably influence the predicted flow/temperature field and the resultant PAH concentration. Moreover, the effects become more notable with lower fuel stream velocities. It was also found that for propane with a density larger than air, recirculation zones were formed near the nozzle exit which exerted an additional influence on the flow development and temperature field as well as PAH formation. In addition, the effects of nozzle heating on flow development and PAH formation were also investigated.     

北部湾盆地流沙港组湖相烃源岩的差异

北部湾盆地是中国近海重要的富油盆地,油气发现主要集中于涠西南凹陷、乌石凹陷和福山凹陷,探明原油地质储量约为4.05×10⁸t,但各个主要凹陷的探明油气地质储量存在显著差异。北部湾盆地各凹陷的油气富集程度与其湖相烃源岩的差异密切相关,从涠西南凹陷到乌石凹陷,再到迈陈凹陷和福山凹陷,古近系流沙港组烃源岩的品质总体下降,烃源岩的有机质丰度降低,有机质类型从以腐泥型为主变成以混合型占优势,烃源岩的生烃潜力下降。分析表明,尽管北部湾盆地流沙港组烃源岩在形成期各凹陷普遍具有较高的古湖泊有机质生产力,但各凹陷的有机质来源仍然存在差异,有机质保存条件也存在差异,从涠西南凹陷到乌石凹陷,再到迈陈凹陷、福山凹陷和海中凹陷,湖相藻类来源的有机质减少,陆生高等植物来源的有机质增加,有机质保存条件具有变差的趋势。     

温度效应及环空条件对井口抬升影响规律研究

为预测深水高温井生产过程中的井口抬升量,基于套管热膨胀效应及热力学基本原理,建立了不同温升条件下单层自由套管及多层套管耦合井口系统抬升量预测模型,设计了3层同心钢管柱为主体的试验装置,开展了不同工况下井口抬升模拟试验,得到了温度效应、环空上端部约束状态和环空压力等因素对井口抬升量的影响规律,提出了解决深水水下井口抬升的主要工程措施。研究结果表明:以试验模型为例,当最内层管柱温度从45℃升高至150℃的过程中,在模拟传热条件下,3层管柱环空上端部敞开时,各层管柱抬升量与其温升呈线性增长规律;环空上端部焊接为整体时,73.0和114.3 mm管柱最终抬升量相对上端部敞开状态分别减小26.50%和21.80%,177.8 mm管柱最终抬升量增加4.06%;环空密闭并加压20 MPa时,73.0、114.3和177.8 mm管柱最终抬升量相对无压力时分别增加了23.84%、26.79%和25.36%;温度及环空条件对井口抬升量影响显著,理论预测值与试验值误差为1.59%~8.93%。研究结果可为深水高温井井口抬升控制措施的制定提供技术支持。     

汽车差速器锥齿轮差速工况下的润滑特性研究

为了研究差速器锥齿轮摩擦和磨损机制,基于弹性流体动力润滑理论,建立直齿锥齿轮无限长时变弹性流体动力润滑模型,研究行星齿轮分别与左右半轴齿轮啮合时的润滑状况,计算差速工况行星齿轮时变效应下的油膜压力和油膜厚度;研究差速工况下左右半轴齿轮的润滑状况,分别比较左右半轴齿轮同行星齿轮啮合时的润滑特性;研究曲线行驶路段复杂变工况下行星齿轮的润滑状况。结果表明:差速工况下行星齿轮啮合周期内的膜厚变小,且行星齿轮与半轴齿轮的相对滑动加剧;行星齿轮同左右半轴齿轮啮合时的润滑特性不同,左转弯工况时,左半轴齿轮同行星齿轮啮合时的最大压力较大,右半轴齿轮同行星齿轮啮合时的最小油膜厚度较大;曲线行驶变工况下行星齿轮润滑特性也不同,左转弯工况向右转弯工况过渡时的压力减小,膜厚增大。     

Drying of industrial sludge waste in a conical spouted bed dryer. Effect of air temperature and air velocity

To determine the performance of a conical spouted bed dryer for the drying of sludge waste, an experimental study of drying in a spouted bed regime was performed under different experimental conditions. The drying performance was determined based on the time evolution of solid moisture content, and the influence of operating conditions (inlet air temperature, air flow rate, and bed mass) on the drying rate of sludge waste in spouted beds of a conical geometry was analyzed.     

Good thermal stability,giant permittivity,and low dielectric loss for X9R-type (Ag1/4Nb3/4)0.005Ti0.995O2 ceramics

With the intense demand of the developing microelectronics market, the study of giant permittivity dielectric materials is being promoted. However, it is difficult to obtain suitable dielectric materials for such applications, especially due to high dielectric loss at low frequencies. In this work, Ag+Nb codoped TiO₂ ceramics were designed and fabricated in a conventional solid reaction by sintering at 1290-1340°C for 5-10 hours. The issue of how the microstructure and dielectric properties of (Ag_1/4Nb_3/4)_0.005Ti_0.995O₂ ceramics are affected by the sintering conditions was discussed. By optimizing sintering conditions, a dense microstructure, a high dielectric constant (ε_r ≈ 9410), and a low dielectric loss (tanδ ≈ 0.037) at 1 kHz were achieved. Most importantly, the temperature coefficient value of ε_r at different frequencies remained stable between −14.3% and 13.7% within the temperature range from −190 to 200°C, which has potential applications in X9R capacitor.