阳极焙烧炉烟气净化系统着火原因及解决办法

从焙烧烟气净化系统几个着火要素出发,分析着火的原因;从炉型设计、生产操作、工艺参数等几个方面提出解决办法,为设计选型、系统改造、安全生产提供技术支持。     

秦家屯油田分层注水技术应用效果分析

秦家屯油田位于松辽盆地南部,梨树断陷东部斜坡区,属于非均质断块层状油藏。经过10余年开发,油藏在不同方向的物性差异、层间矛盾、层内矛盾十分突出,为了解决这些矛盾,有效的改善吸水剖面,使油田稳产,2010年在秦家屯油田进行了分层注水措施,油藏吸水状况良好,水驱控制、动用程度有所提高,有效地改善了剖面的吸水差异,同时使油藏对应油层得到了充分的能量补充,油田采收率有所提高,自然递减同比下降,极大地改善了开发效果,达到了油田稳产的目的,具有重要的意义。     

濮城油田预交联凝胶驱油技术

濮城油田经过多年的注水开发,注水开发效果在逐渐变差.近年来虽然开展了多次调剖,但由于调剖技术的局限性,提高波及系数有限,随着调剖次数的增多,效果逐渐变差.为了进一步提高采收率,开展了预交联凝胶驱油技术.在室内试验研究的基础上,通过现场实施取得了较好的增油效果.     

Porous ZnO nanosheets grown on copper substrates as anodes for lithium ion batteries

Porous ZnO nanosheets are grown directly on copper substrates by a chemical bath deposition technique followed by a heat treatment. The materials are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Their electrochemical properties as anodes of lithium ion batteries are examined by cyclic voltammetry (CV) and galvanostatic discharge–charge tests. The results show that porous ZnO nanosheets exhibit higher reversible capacities and better cyclabilities than those of commercial ZnO powders. When cycled at 0.05 A g⁻¹, these nanosheets deliver initial discharge and charge capacities of 1120 and 750 mAh g⁻¹, and at 0.5 A g⁻¹, they keeps stable capacities of 400 mAh g⁻¹ up to 100 cycles, in addition, they also exhibit good rate capabilities. It is believed that the porous sheet nanostructure plays an important role in the electrochemical performance.     

Bivalent tin ion assisted reduction for preparing graphene/SnO2 composite with good cyclic performance and lithium storage capacity

Co-precipitation method of SnCl₂·2H₂O and graphene oxide (GO) solution was performed to fleetly prepare graphene/SnO₂ composite. The structure and composition of the nanocomposite were detected by means of XRD, SEM, TEM and FT-IR. The GO was reduced by bivalent tin ions to graphene nanosheet (GNS) via solution reaction and SnO₂ nano-crystals with size of 4–6 nm were homogeneously distributed on the matrix of GNS. It was found that the disorder degree of graphene in GNS/SnO₂ composite prepared by the bivalent tin ion assisted reduction method was much lower than that of GNS obtained via pyrolysis reduction. The possible mechanism for this phenomenon was discussed in detail. The N₂ adsorption tests showed an ink-bottle-like pore structure of GNS/SnO₂ and the SnO₂ nanoparticles were confined in the interlayer of GNS without agglomeration. These structural features were desirable and enabled GNS/SnO₂ an excellent anode material in lithium ion battery. The electrochemical tests showed that the composite could deliver a reversible capacity of 775.3 mAh/g and capacity retention of 98% after 50 cycles.     

Systematic study of back pressure and anode stoichiometry effects on spatial PEMFC performance distribution

A segmented cell system was applied to investigate the effects of the anode and cathode back pressure and hydrogen stoichiometry on fuel cell performance in terms of overpotential distributions along the flow field. The segmented cell system was designed with closed loop Hall sensors and a data acquisition system allowing simultaneous spatial electrochemical impedance spectra (EIS) measurements. It was determined that an increase in back pressure for the tested serpentine flow field design results in an improvement of the cell performance and uneven improvement of individual segments’ performance. In general, the performance and the overpotentials become more uniform downstream with an increase in the back pressure due to a decrease in activation and mass transfer losses. Spatial EIS data for the PEMFC operated at different back pressures support the overpotential analysis. Hydrogen stoichiometry variations do not affect the performance of the cell or the individual segments at low current density because there is no significant hydrogen concentration gradient in the flow field. However, at high current densities a reduction in hydrogen stoichiometry produces a slight decrease in performance for inlet segments while outlet segments showed a noticeable performance loss. The decrease in performance is attributed to an increase in mass transfer losses due to nitrogen diffusion from the cathode to the anode. This effect becomes more pronounced for the outlet segments due to a downstream nitrogen accumulation. Under high current density conditions, the cell is locally fuel starved even with a high fuel stoichiometry creating conditions leading to cell degradation by carbon corrosion. More importantly, this local degradation is masked by the overall cell performance which remains largely unaffected.     

Bismuth sulfide and its carbon nanocomposite for rechargeable lithium-ion batteries

Bi₂S₃ and Bi₂S₃/C nanocomposites prepared by high-energy mechanical milling were evaluated as electrode materials in lithium secondary batteries. For a Bi₂S₃/C nanocomposite, Bi₂S₃ nanocrystallites were well distributed in an amorphous carbon matrix. The reaction mechanism of the Bi₂S₃/C electrode was also examined during the first cycle. The Bi₂S₃/C nanocomposite anode showed superior electrochemical performance (ca. 500 mAh g⁻¹ and 85% of the capacity retention over 100 cycles).     

Electrodeposition of porous Co layers and their conversion to electrocatalysts for methanol oxidation by spontaneous deposition of Pd

Electrocatalysts for methanol oxidation were prepared through a two stage deposition process: porous cobalt layers were deposited, by cathodic reduction of Co²⁺ ions, and then modified by spontaneous deposition of Pd. A basic sulphate solution and a mildly acid chloride solution were compared as media for the electrodeposition of Co. Deposits with the highest surface roughness were obtained in the chloride solution, at large current densities. Pd was deposited onto the Co porous layers by immersing them in acid deaerated PdCl₂ solutions, at open circuit. The Pd loading and the Pd surface area were estimated by UV–visible spectroscopy and by cyclic voltammetry, respectively. The Pd-modified Co electrodes were tested as anodes for methanol oxidation and compared to the similarly prepared Pd-modified Ni electrodes. The former exhibited better stability of performance and higher methanol oxidation peak currents per unit Pd mass, ca. 200 A g⁻¹.     

Amorphous silicon–carbon based nano-scale thin film anode materials for lithium ion batteries

The buffering effect of carbon on the structural stability of amorphous silicon films, used as an anode for lithium ion rechargeable batteries, has been studied during long term discharge/charge cycles. To this extent, the electrochemical performance of a prototype material consisting of amorphous Si thin film (∼250 nm) deposited by radio frequency magnetron sputtering on amorphous carbon (∼50 nm) thin films, denoted as a-C/Si, has been investigated. In comparison to pure amorphous Si thin film (a-Si) which shows a rapid fade in capacity after 30 cycles, the a-C/Si exhibits excellent capacity retention displaying ∼0.03% fade in capacity up to 50 cycles and ∼0.2% after 50 cycles when cycled at a rate of 100 μA/cm² (∼C/2) suggesting that the presence of thin amorphous C layer deposited between the Cu substrate and a-Si acts as a buffer layer facilitating the release of the volume induced stresses exhibited by pure a-Si during the charge/discharge cycles. This structural integrity combined with microstructural stability of the a-C/Si thin film during the alloying/dealloying process with lithium has been confirmed by scanning electron microscopy (SEM) analysis. The buffering capacity of the thin amorphous carbon layer lends credence to its use as the likely compliant matrix to curtail the volume expansion related cracking of silicon validating its choice as the matrix for bulk and thin film battery systems.     

High reversible capacity of SnO2/graphene nanocomposite as an anode material for lithium-ion batteries

A gas–liquid interfacial synthesis approach has been developed to prepare SnO₂/graphene nanocomposite. The as-prepared nanocomposite was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller measurements. Field emission scanning electron microscopy and transmission electron microscopy observation revealed the homogeneous distribution of SnO₂ nanoparticles (2–6 nm in size) on graphene matrix. The electrochemical performances were evaluated by using coin-type cells versus metallic lithium. The SnO₂/graphene nanocomposite prepared by the gas–liquid interface reaction exhibits a high reversible specific capacity of 1304 mAh g⁻¹ at a current density of 100 mA g⁻¹ and excellent rate capability, even at a high current density of 1000 mA g⁻¹, the reversible capacity was still as high as 748 mAh g⁻¹. The electrochemical test results show that the SnO₂/graphene nanocomposite prepared by the gas–liquid interfacial synthesis approach is a promising anode material for lithium-ion batteries.