关于炭素厂阴极焙烧车间设计的探讨

根据近年来对国内炭素厂阴极焙烧车间设计中所作的优化和改进,提出了几个以增产、节能、节约投资和便于操作维修为目的的有效措施。     

石油焦煅烧综合技术的开发与应用

介绍了石油焦煅烧新工艺和Φ2.84×55m回转窑的技术特点以及利用其烟气进行余热发电,可满足炭素厂全厂用电需求。     

成型烟气净化自控系统的设计与开发

介绍炭素厂成型烟气净化自控系统的设计与技术要点,利用RockWell自动化的NetLinx网络架构和Control-Logix控制系统,配合实用的PID控制算法,实现控制要求并且与其它工段联网。     

铝电解槽烟气焙烧时阴极及扎固糊的氧化特性

烟气焙烧启动方法可以有效地控制阴极的加热速度及温度分布 ,能方便地按要求焙烧好阴极 ,同时使侧部扎固糊取得很好的焙烧效果。但焙烧过程中的氧化问题一直为人们所关心 ,用电阻炉加热试样、向炉膛内通入燃烧烟气来模拟烟气焙烧过程的方法测定阴极及扎固糊的氧化特性。实验表明 ,在正常的空气配比下 ,炭阴极及扎固糊在烟气中的氧化速度约为在空气中的 8%左右 ,并且炭阴极及扎固糊在烟气中的氧化速度随温度的变化较小     

阳极焙烧炉烟气联合式干法净化技术的研发和应用

论述了焙烧炉烟气净化系统广泛采用电捕焦油器净化技术和氧化铝吸附净化技术在国内铝用阳极炭素厂实际生产中暴露的问题,提出了联合式干法净化技术的开发理念和运行效果,说明了联合式干法净化技术的成功应用为焙烧炉烟气治理提供了高效可靠的净化方法.     

铝用炭素生产过程余热利用技术及工程实例

本文实际调研了某炭素厂的能量流向,考核其热平衡,结果表明:生产过程的主要热支出项为煅烧过程的冷却循环水带走的热量与煅烧烟气带走的热量,分别占总能量支出的14.37%和25.28%,焙烧过程的高温固体带走热占总能量支出的28.27%。该炭素厂已对高温煅烧烟气余热进行了利用,其中采取余热发电方式回收的余热每天可发电70,000 kWh,另外采用高温烟气加热导热油方式回收的余热用于车间生产、员工生活供热并生产蒸汽售卖。根据厂区余热特点,进一步提出利用煅烧冷却水冬季直接供暖、夏季采用通过溴化锂吸收式制冷的直接利用方式,以及利用焙烧过程余热继续加热煅烧冷却水到65℃左右,用于供暖的复合利用方式。     

整体成型阴极实验排烟分析及控制

以200 kA电解槽整体成型阴极研究试验作为案例,以阴极材料分析测试小试试验测试结果为依据,分析确定电解槽阴极材料挥发分产生量及烟气产生量,并提供了一整套烟气收集控制措施。通过对电解槽运行情况监控,确定试验槽烟气进入铝电解烟气净化系统对电解槽运行没有影响,对净化系统运行及氧化铝输送没有影响,该烟气进入原有净化系统进行净化处理方式可行,解决了烟气量确定、烟气收集方法及处理方法关键技术问题。     

炭素回转窑烟气余热梯级利用技术研究与应用

高温烟气经过余热锅炉后,温度降低到260℃,仍是可利用的能源,为了回收这部分热量,在中铝贵州分公司开展炭素回转窑烟气余热梯级利用新技术的研究与应用,将炭素厂回转窑烟气余热进行"梯级利用"改造,利用烟气余热替代原燃油热媒锅炉,提供炭素阴、阳极成型热媒油系统所需热能,年节约重油4365吨,减少蒸汽消耗5519吨,节约能源6494吨标准煤,减少约16190吨CO2的排放。     

泰兴市晨光高新技术开发有限公司

正在青海铝业炭素厂机加车间内,安放着两条铝用阴极炭块加工设备:一条是欧洲某国制造、故障频出、干干停停的炭块自动加工线,另一条是江苏省泰兴市晨光高新技术开发有限公司(简称"晨光公司")新建的CGK·RZ·04数控炭块自动加工线(简称"泰兴线"),这已是晨光公司建造的第二条阴极炭块自动加工线。     

江苏晨光数控机床有限公司(原泰兴市晨光高新技术开发有限公司)

正在青海铝业炭素厂机加车间内,安放着两条铝用阴极炭块加工设备:一条是欧洲某国制造、故障频出、干干停停的炭块自动加工线,另一条是江苏省泰兴市晨光高新技术开发有限公司(简称"晨光公司")新建的     

Carburization of Cr-based ODS alloys in SOFC relevant environments

Chromium based ODS alloys are being discussed as interconnector materials in solid oxide fuel cells (SOFC's). One of the major requirements for the interconnect material is sufficient corrosion resistance in the anode and cathode side gases at the operating temperature of around 950°C. In the present study the corrosion behaviour of a number of chromium based ODS alloys has been investigated in carbon containing simulated anode gas of an SOFC. Under these experimental conditions all alloys studied are prone to carburization. The carbon uptake, which mainly occurs in the early stages of exposure, leads to the formation of a mixed carbide/oxide layer beneath the external chromia scale. The carburization resistance of the alloys depends on the type and concentration of the oxide dispersion but even to a larger extent on its distribution. Therefore the careful control of the alloy manufacturing process is of great significance for obtaining sufficient carburization resistance under SOFC conditions.     

Porous graphene/carbon nanotube composite cathode for proton exchange membrane fuel cell

Porous Pt-graphene/multiwalled carbon nanotube (MWCNT) composite cathodes were fabricated for proton exchange membrane fuel cells and their electro-chemical performances were examined. Rod-like MWCNTs with a high aspect ratio induced a porous network structure and Pt-graphene was bound homogeneously to the porous network structure of MWCNTs in the form of a very rough surface, which facilitated simultaneous access between the Pt electro-catalyst and reactant. In addition, the porous MWCNT network enabled the Pt-graphene electrode to overcome the deficiency induced by high electrical resistance by providing an electrical pathway for the oxygen reduction reaction (ORR). Therefore, the ORR charge transfer resistance of the Pt-graphene/MWCNT composite cathode was much smaller than that of the Pt-graphene cathode, and the maximum power density of the Pt-graphene/MWCNT composite cathode was four times higher than that of the Pt-graphene cathode.     

Improved properties of carbon fiber paper as electrode for fuel cell by coating pyrocarbon via CVD method

The fabrication of a pyrocarbon coated carbon paper and its application to the gas diffusion lay (GDL) of proton exchange membrane (PEM) fuel cell were described. This carbon paper was fabricated by using conventional carbon paper as the precursor, and coating it with pyrocarbon by pyrolyzing propylene via the chemical vapor deposition (CVD) method. For comparison, conventional carbon paper composites were also prepared by using PAN-based carbon fiber felt as the precursor followed by impregnation with resin, molding and heat-treatment. SEM characterization indicates that pyrocarbon is uniformly deposited on the surface of the fiber in the pyrocarbon coated carbon paper and made the fibers of carbon felt bind more tightly. In contrast, there are cracks in matrix and debonding of fibers due to carbonization shrinkage in the conventional carbon paper. Property measurements show that the former has much better conductivity and gas permeability than the latter. In addition, current density-voltage performance tests also reveal that the pyrocarbon coating can improve the properties of carbon paper used for electrode materials of fuel cell.     

Conductivity study of porous yttria-doped zirconia and strontia-doped lanthanum manganite bilayer film by glancing angle deposition

Porous bilayer films of yttria-doped zirconia and strontia-doped lanthanum manganite are deposited by using electron beam evaporation. For practical use in solid oxide fuel cells, fully-stabilized zirconia is a candidate for the solid electrolyte due to its high oxygen diffusion rate. Longer triple phase boundary, which consists of catalyst, reacting gas and solid electrolyte in the cathode, is helpful for the exchange of oxygen gas and ions. By glancing angle deposition, higher density of triple phase boundary is achieved in the form of catalyst and electrolyte bilayer structure. This kind of triple phase boundary can be estimated from SEM images and it is rather easier than from conventional composite cathode which can only be analyzed with assistance of mathematic simulation. The resistance of this bilayer at 600 °C is ten times lower than porous catalyst single layer.     

Fabrication and performance of La0.8Sr0.2MnO3/YSZ graded composite cathodes for SOFC

The performance of multi-layer (1-x)La0.8Sr0.2MnO3/xYSZ graded composite cathodes was studied as electrode materials for intermediate solid oxide fuel cells (SOFC). The thermal expansion coefficient, electrical conductivity, and electrochemical performance of multi-layer composite cathodes were investigated. The thermal expansion coefficient and electrical conductivity decreased with the increase in YSZ content. The (1-x)La0.8Sr0.2MnO3/xYSZ composite cathode greatly increased the length of the active triple phase boundary line (TPBL) among electrode, electrolyte, and gas phase, leading to a decrease in polarization resistance and an increase in polarization current density. The polarization current density of the triple-layer graded composite cathode (0.77 A/cm2) was the highest and that of the monolayer cathode (0.13 A/cm2) was the lowest. The polarization resistance (Rp) of the triple-layer graded composite cathode was only 0.182Ω·cm2 and that of the monolayer composite cathode was 0.323Ω·cm2. The power density of the triple-layer graded composite cathode was the highest and that of the monolayer composite cathode was the lowest. The triple-layer graded composite cathode had superior performance.     

乏燃料水池转运舱氦质谱检漏技术的应用

乏燃料水池转运舱是核电站乏燃料水池的组成部分,用于存放燃料组件倒料设备和水。监测乏燃料水池转运舱的水的泄漏率,通过气体和水的泄漏率转换,分析和计算出氦气检漏的泄漏率范围,并建立检测区域模型,优化检测范围和流程,通过范围查找和精确查找的结合,快速和准确地找到泄漏位置,以为乏燃料水池的查漏工作提供经验。     

乌石化公司三聚氰胺废渣处理实验研究

对常压法三聚氰胺生产过程中产生的废渣进行理化性能、可燃烧性试验室检测,并对燃烧后的尾气进行测试,最终在乌石化热电厂锅炉进行了掺烧试验,结果表明,掺烧少量的三胺废渣,对热电厂锅炉操作无任何影响,产生的烟气及除渣废水中均没有检测到有害物质,烟气中的粉尘含量也无明显变化,该废渣与原煤掺混能够作为电厂锅炉的燃料使用.     

我国阴极炭素材料发展中的若干问题

对我国阴极炭素材料市场进行了综合评述，指出数量增加快、质量进步慢。呼声高、行动少，急功近利、工作不扎实等是我国在优质阴极炭素材料开发和应用中存在的主要问题。建议有关领导部门应高度重视，在深入细致调研的基础上制定出相应的政策，指导和协调高档阴极炭素材料的开发和应用。铝业界应充分认识我们的差距和开发高档阴极炭块的难度，更新观念，制定切实有效的措施；应坚持优胜劣汰、优质优价的原则。鼓励炭素企业开发和生产优质阴极炭素材料，扎扎实实地提高我国阴极炭素材料的质量。     

Transfer and deposition of carbon-and nitrogen-containing radicals and ions produced by glow discharge in hydrogen/methane/nitrogen mixtures

Transfer and deposition of the decomposition products of a dc glow discharge with hollow cathode in a hydrogen/methane flow are discussed. Hydrocarbon (a-C:H) films were deposited at inner surfaces of the hollow cathode and quartz tube bounded the discharge. The carbon deposition rate in the hollow cathode was 3–10 times higher than in the positive column and in afterglow range. Acetylene, ethylene, and ethane prevailed in the plasma-reaction gaseous products. When molecular nitrogen was introduced to the near-cathode plasma at a flow rate equal to or higher than that of methane, the carbon deposition rate at the cathode inner surfaces dropped down by 1.5 to 2 orders of magnitude. The carbon that has been consumed in the a-C:H films formation in the cathode is now transformed mainly to hydrogen cyanide (HCN). The carbon deposition rate in the positive column and in afterglow range (T = 300 K) were comparable with those in the H₂/CH₄ mixture. In the a-C/N:H deposits, the nitrogen concentration was 15 to 25 at %. The experiments showed that nitrogen can be used as a component of the gas flow specially introduced near the mirror in protecting the optical surfaces in diagnostic channels of the ITER tokamak against a-C:H film deposition. Original Russian Text ? A.E. Gorodetskii, R.Kh. Zalavutdinov, V.L. Bukhovets, A.P. Zakharov, G.T. Razdobarin, E.E. Mukhin, V.V. Semenov, 2008, published in Fizikokhimiya Poverkhnosti i Zashchita Materialov, 2008, Vol. 44, No. 6, pp. 581–586.     

Corrosion experience with carbon steel in spray absorption FGD plant

Carbon steel is the traditional material for boiler flue gas ducts and stacks. The introduction of flue gas desulphurisation systems in existing power plant units requires major changes in the flue gas system from boilers to the flue stack. In the semidry spray absorption plant at Studstrupværk power plant carbon steel has been used. This concept was chosen to utilize part of the existing carbon steel ducting and avoid the use of expensive high alloyed materials and coating systems. During the first year of operation emission of fine flakes of rust from the ducting and the stack become a major problem. To overcome this, corrosion testings were performed in laboratory and in the plant. The corrosion problems were found to be related to an atmospheric corrosion with hygroscopic chloride containing deposits. The aim of the tests was to establish the critical humidity for corrosion of carbon steel in FGD plant products and deposits. The examinations cover products and deposits from different operational conditions and parts of the Studstrupværk power plant. The laboratory tests were followed by corrosion probe tests in the plant and full scale operation tests with the plant. The results of this programme showed that carbon steel can be used and corrosion can be kept at a very low level by controlling the humidity of the flue gas below 40% RH with fresh water as process water and down to 30% RH with salt water as process water. In practice this has to be controlled by the temperature difference between the flue gas and the adiabatic saturation temperature of the flue gas. Effective insulation of the ducting has been found to be of outmost importance as the humidity should be measured relative to the surface temperature. Experience from the plant shows that the most severe corrosion is found in cold spots.