国产化复极槽使用注意事项浅谈

详细叙述了国产化复极槽在使用时要注意的几个问题,阐述了问题发生的原因及解决的办法。     

复极式自然循环电解槽运行总结

我公司年产2万t复极式自然循环电解槽于1998年4月1日一次试车成功投产,至今已稳定运行了26个月,现将该装置2年多来的生产运行以及经济技术指标完成情况总结如下,并将该装置开停车过程需特别注意的问题介绍给大家。     

旭化成和国产化强制循环复极电解槽压差波动原因及对策

国内使用旭化成和国产化强制循环复极电解槽的厂家电槽压差时有波动(0.001～0.002 MPa),有的波动较严重(0.003～0.006 MPa),影响膜的性能及寿命,这是离子膜法生产烧碱中的棘手问题。笔者经十几年生产实践,有些经验和教训,现将影响电槽压差的原因及对策作一介绍,供同行参考。     

BiTAC复极槽运行过程中的问题与改进

介绍了36万t／a离子膜电解装置运行中出现的一些问题,提出了解决办法,指出要保证盐水质量和加强巡检与监控。     

日本旭化成公司对复极式离子膜电解槽阳极室的改进

1995年9月4日至9月28日,我厂对北京化工二厂2万吨标准型复极式离子膜电解槽进行了全面整体检修。这种电解槽是用我厂引进日本旭化成公司的技术制造的。检修过程中发现了不少设计上的问题。其中之一,是阳极室上部复合板钛层因过烧而引起的大面积氧化彩色图纹。 1995年《氯碱工业》第八期中,《离子膜电解槽设计及最佳化》一文介绍了日本旭化成公司对复极式离子膜电解槽的气泡产生、气泡影响及消除这种影响的机理和措施。它可以很好地解释上述彩色氧化图纹现象,并消除造成这种现象的根源。     

国产化复极槽的发展过程

叙述了国产化复极槽的六个发展阶段,并结合发展中遇到的问题及相应的解决办法叙述了一些内部结构的演变过程。     

复极式离子膜电解槽结构性能评述

本文从设备结构设计与性能方面对世界四家公司复极式离子膜电解槽进行了列表比较和综合评述。     

ZMBCH -2.7型复极式离子膜电解槽运行总结

介绍ZMBCH - 2.7型复极式离子膜电解槽的基本结构和基本性能参数.通过与30 - DD350离子膜电解槽对比,说明ZMBCH - 2.7电解槽具有电流密度高、运行阴阳极压力高、内部循环、压滤机式密封的特点.给出运行初期电解槽发生的异常情况及处理措施.     

现代复极式离子膜电槽的结构特点及技术性能评价

本文根据我厂与国外专利技术公司就5万t/a离子膜烧碱项目的技术交流,通过对现代较典型的复极式离子膜电槽的结构及技术特点比较,对其进行综合的技术性能评价,供国内技术引进参考。     

复极离子膜电槽电压数据分析

通过使用化工数据处理方法对天津化工厂复极电槽进行电压数据分析,得出电压最低的组合是:阳极液流量低于14.9m3/h;入侧酸度≥0.09mol/L;阳极液质量浓度≥210g/L;阴极液质量分数低于32%;阴极液流量≥21.1m3/h;槽温<85℃。     

国产单极式离子膜电解槽结构与性能介绍

BMCA-2.5型单极式离子膜电解槽由3组相同的反应室框组成,组与组之间由导电体串联连接,电槽上部设置气液分离器;反应室组件外部设置有阴、阳极液循环下降管路。还介绍了装置的支架、紧固部件等,以及各部件为防止电化学腐蚀选用的材料和措施。该槽型结构合理,性能优良,运行稳定,直流电耗低,寿命长,性能指标可达国际同类装置的先进水平。     

MBC—2．7型复极式离子膜电解槽改进点及运行中有关问题的探讨

从第1台MBC－2．7型复极式离子膜电解槽1993年7月23日在沧化投入运行以来,我厂已为国内用户提供了年产35t烧碱的离子膜电解装置,到目前已推出了第6代产品,这期间MBC－2．7型复极槽走过了一条不断改进,完善,提高之路。第1代产品由于对阴极盘材质认识不够,阴极盘板采用了316L不锈钢板,单元槽框渗漏的较多;第2代产品主要表现在阳极接缝采用对接,而出现扎膜问题;第2,4,5代产品主要在阴极盘板的选材,阴阳极接缝的形式,密封面的结构形式以及电极与筋板的焊接上有所改进,使MBC－2．7型电解槽逐步走向完善,近1年来推出的第6代产品,在前5代不断改进完善的基础上,向更高的层次进行了改进和提高。     

Relationship between the structure of carbon nanocoils and their electrical property

The electrical property of carbon nanocoils (CNCs) annealed from 300 to 2900 K has been studied by a four-probe technique. It was shown that the resistivity of the CNCs decreased with the increase of the annealing temperature owing to the improvement of crystallinity and the most notable change of resistivity occurred at the initial structure change of the CNCs. Besides the measurement of room-temperature resistivity of the annealed CNCs, temperature-dependent resistance of the annealed CNCs was also measured. According to the nearest neighboring hopping mechanism, the average activation energy for electron hopping in the annealed CNCs was calculated, which indicated that the average activation energy reduced with the structural improvement of CNCs. It was also found that the variation of average activation energy was also sensitive to the initial structural change of CNCs. Finally, through studying the electrical property of the CNCs under expansion, it was found that the resistance of the CNC was not changed with elongation.     

Influence of Mn-substitution on the structure and low-temperature electrical conduction properties of PrCoO3

Rare earth cobalt perovskite oxide (LnCoO₃) is one kind of complex metal oxides and has a wide variety of applications. The performance of LnCoO₃ is controlled by its electrical conduction, and therefore it is essential to study the behaviour of electrical conduction in LnCoO₃ and elucidate the corresponding conduction mechanism. In this work, a series of PrCo_1−xMn_xO₃(x = 0, 0.05, 0.1, 0.15, 0.2) were prepared by sol-gel method. The structures and low-temperature electrical conduction properties of these samples were investigated using x-ray diffraction, infrared spectra and alternating current impedance spectroscopy. All samples crystallized in an orthorhombic perovskite structure. Structural refinements reveal that the lattice parameters increased, while the orthorhombility decreased with Mn substitution. Further investigation of infrared spectrum indicates that the stretching vibration bands of Co-O bonds shifted towards lower wavenumbers followed by an increase of the population of Co³⁺ ions with intermediate spin state. These variations led to a reduced bandwidth of e_g band which could be the dominant reason for the abrupt decrease of bulk semi-conduction and the increase of activation energies for small polaron hopping conduction in PrCo_1−xMn_xO₃.     

Thermal and electrical conduction in the compaction direction of exfoliated graphite and their relation to the structure

The effects of the compaction and graphite layer preferred orientation on the thermal and electrical conductions in the compaction direction of graphite-flake-based exfoliated graphite have been decoupled. The compact’s electrical and thermal conductivities decrease with increasing compaction (density increasing from 0.047 to 0.67 g/cm³, solid content increasing from 2.1 to 30 vol.%) and preferred orientation. The essentially linear correlation between electrical and thermal conductivities (Wiedemann–Franz Law) is because both conductions are governed by the preferred orientation. With increasing compaction, the fraction (f) of conduction path that is the graphite a-axis decreases from 0.997 to 0.937 and from 0.994 to 0.798 for thermal and electrical conductions respectively. For the solid-part thermal and electrical conductivities to exceed 140 W/(m K) and 60 kS/m respectively, f must exceed 0.95; the highest solid-part conductivities are 550 W/(m K) and 230 kS/m. The compaction-related variation in the solid-part conductivities is large [21–550 W/(m K) and 10–230 kS/m], due to the preferred orientation variation. The through-thickness Lorentz number (7.3 × 10⁻⁶ W Ω/K²) is similar to the in-plane value, being independent of the preferred orientation. At 2–7 vol.% solid, conductivities of 7 W/(m K) and 3 kS/m are obtained for the compact – toward the targets for fuel cell biopolar plates.     

石灰窑结构和性能改进设计

石灰窑是钢铁工业、电石工业、氧化铝工业和耐火材料工业中的重要设备。本文论述了对机械化程度较高的石灰窑窑底出灰螺锥中心定位机构所作的改进,设计出了一种新结构装置,这种新装置对石灰窑稳定运行、延长齿轮使用寿命和保证使用可靠性均有益处。     

Investigation of electrical conduction mechanism in double‐layered polymeric system

The electrical conduction in solution‐grown polymethylmethacrylate (PMMA), polyvinylidenefluoride (PVDF) and PMMA‐PVDF double‐layered samples in the sandwich configuration (metal‐polymer‐metal) was investigated at different fields in the range 100–120 kV/cm as a function of temperature in the range 293–423 K for samples of constant thickness of about 50 μm. Certain effects which lead to a large burst of current immediately after the application of field were observed in double‐layered samples. An attempt was made to identify the nature of the current by comparing the observed dependence on electric field, electrode material and temperature with the respective characteristic features of the existing theories on electrical conduction. The observed linear I‐V characteristics show that the electrical conduction follows Pool‐Frenkel mechanism in PMMA and PVDF samples. Whereas, the non‐linear behavior of current‐voltage measurements in PMMA‐PVDF double‐layered samples have been interpreted on the basis of space charge limited conduction (SCLC) mechanism. The conductivity of the polymer films increased on formation of their double‐layer laminates. The polymer‐polymer interface act as charge carrier trapping centres and provides links between the polymer molecules in the amorphous region. The interfacial phenomenon in polymer‐polymer heterogeneous system has been interpreted in terms of Maxwell‐Wagner model. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Deposition-temperature dependence of structure,ferroelectric property and conduction mechanism of BCZT epitaxial films

Ba_0·85Ca_0·15Zr_0·1Ti_0·9O₃ (BCZT) epitaxial films were successfully deposited on (001) Nb-doped SrTiO₃ substrate, and the effects of deposition temperatures on the structure, ferroelectric property, and conduction mechanism were studied. The results of XRD and AFM verified the well epitaxial structure with smooth surfaces of the deposited BCZT epitaxial films. BCZT epitaxial films deposited at 650 °C exhibited the best ferroelectric property (2P_r = 22.91 μC/cm², 2E_C = 1702.11 kV/cm) and relatively low leakage current density (7.91 × 10³ A/cm²). The conduction mechanism of BCZT films corresponds to the space-charge-limited current (SCLC) mechanism and the Fowler-Nordheim (F–N) tunneling mechanism in the low and high electric field range, respectively.     

The change of structure and electrochemical property in the synthesis process of spherical NiOOH

The present paper reports the synthesis of the high capacity NiOOH through oxidization of spherical Ni(OH)₂ by utilizing high-density NaClO-NaOH solution. The relationship between the structure and the change in electrochemical behavior during the synthesis process of NiOOH was investigated by means of the tests of FSEM, XRD, CV and galvanostatic discharge method. During most oxidizing time, the increment of NiOOH capacity is in linear relationship with the reaction time and is restrained by surface area and the diffusion of protons in solid phase. The optimal reaction time to synthesize ideal spherical NiOOH is 3 h. The appearance of a small platform at 1.2 V in discharging process and the cracks detected by FSEM of NiOOH during reaction process are the evidence of complete oxidization of spherical Ni(OH)₂.     

水泥粉磨系统除尘工艺的改进及计算

我公司３号水泥粉磨系统原采用Φ２．２m×７．０m球磨机与Φ４．０m高效螺桨离心式选粉机组成闭路粉磨工艺。配料库底采用正压布袋除尘器，磨尾采用SZD１６００／２旋风静电组合式除尘器收尘。１原系统存在问题及分析１）风机风叶和壳体直接受到含尘气体的冲刷，磨损十分严重。平均每个月更换１次风机风叶，２个月更换１次风机外壳，维修费用极大。２）当物料综合水分稍大时风机风叶极易积灰，破坏风叶平衡，风机剧烈震动，收尘效果急剧下降，必须停机人工清理（每班８h至少要清理２次），除尘器的有效运转率极低，且维护劳动强度高。３…