35t.h^—1煤泥流化床锅炉对流管束泄漏原因探讨与对策

介绍了兴隆庄热电厂采用的NG－35／3．82－M5型燃用高水份劣质煤泥流化床蒸汽锅炉的基本情况,并针地锅炉运动中出现的对流管束泄漏现象进行了研究和分析,提出了使用异型耐堆砌炉墙的改进方案,该措施成功地用于改善了对流管束的工作状况,防止了管束的泄问题,取得的成果为该类型锅炉的技术改进提供了切实可行的措施。     

催化余热锅炉对流管束胀口泄漏的原因及处理

文章对洛阳分公司一催化余热锅炉对流管束严重泄漏的原因从实际和理论两方面进行了认真分析,认定对流管束泄漏是由于下汽包膨胀受阻引起,据此作出了相应的处理措施;处理后的运行实践证明：分析和处理结果完全正确;文章最后对锅炉的施工改造提出了自己的建议。     

隧道式余热锅炉对流管束角焊缝漏水原因分析及对策

隧道式余热锅炉的对流管束角焊缝漏水原因复杂,对角焊缝漏水机理分析,通过一定的措施控制隧道式余热锅炉对流管束角焊缝的焊接质量,并对其进行热处理,可以解决对流管束角焊缝漏水的问题。     

船用增压锅炉对流管束热力计算研究

对流管束的热力计算是船用增压锅炉国产化的关键技术之一。利用热工基本理论研究在一定压力下高质量流速烟气与对流管束的换热强化机理,探讨适合增压锅炉对流管束热力计算的方法。通过选择合理的相关计算参数,应用所选择的计算公式对某型增压锅炉对流管束进行热力计算,计算结果与实际运行数据相吻合。     

SHW4.2—0.7／95／70—AⅡ型锅炉对流管束变形的原因分析及处理

对SHW4.2 - 0 .7/95 /70 -AⅡ型锅炉在运行期间对流管束变形的原因进行了分析 ,并提出了改进方案 ,经 4年多的实际运行 ,证明该方案可行。     

大容量燃气热水锅炉对流管束的振动分析和预防措施

针对一台58 MW燃气热水锅炉部分对流管束产生的开裂现象进行了深入的原因分析.对断口部分进行了宏观检查、金相组织分析和扫描电镜分析,对烟气冲刷对流管束时气柱的固有(驻波)频率、卡门涡流频率和水管固有振动频率分别进行了计算,并对该锅炉的对流管束进行了振动测试,得出了对流管束产生管子的共振会引发部分对流管脆性断裂的结论.并据此提出了一系列具体的预防和控制措施及建议,通过改变管子的固有频率解决此类问题的发生,为锅炉的安全稳定运行提供保障.     

余热锅炉对流管束制造工艺浅析

文章针对余热锅炉中的对流管束在制造过程中存在的主要问题，采用了一些工艺措施，大量减少了焊接变形。     

SZL锅炉放灰装置改进

SZL链条锅炉具有结构紧凑、占地面积小、施工周期短、燃烧效率高等特点。但是,目前链条炉排锅炉也还有值得改进的地方,特别是对流管束中的四个放灰孔,当锅炉运行一段时间后,很容易堵塞。笔者所在的公司有4台10t/h快装锅炉,4台锅炉都不同程度地存在着放灰口的堵塞问题。由于放灰口的堵塞,对流管束的烟灰不能及时排出去,导致积灰越积越多,最后把部分对流管埋住了,严重影响了锅炉传热,导致了锅炉热效率的降低。为此,笔者所在的公司在放灰装置上作了如下改进。开设扒灰门:在锅炉落灰斗的两侧面开设扒灰门(如图所示) ,这样当积灰堵塞较多,难以…     

锅炉爆管原因分析及对策

通过对发生爆管的蒸汽锅炉炉管中的水垢进行分析,查明了对流管束发生爆管的原因,并提出了保证锅炉继续平稳运行的措施。     

角管式燃氢气锅炉的开发设计

介绍了一台4 t/h燃用纯氢气锅炉的开发与设计。该型锅炉采用角管式锅炉结构,烟气流程为水平直通式,炉膛部分为全膜式壁结构,对流管束为光管与螺旋肋片管,布置有螺旋肋片管的省煤器,水循环安全可靠,防爆措施完善。该锅炉运行安全可靠,有助于氯碱化工行业对其副产品氢气的合理利用,有着巨大的经济效益和社会效益。     

Effect of capacity matchup in the LiNi0.5Mn1.5O4/Li4Ti5O12 cells

The effect of the capacity matchup between cathode and anode in the LiNi_0.5Mn_1.5O₄/Li₄Ti₅O₁₂ cell system on cycling property, choice of electrolyte, high voltage and overcharge tolerances was investigated by comparing the cells with Li₄Ti₅O₁₂ limiting capacity with the cells with LiNi_0.5Mn_1.5O₄ limiting capacity. The former exhibits better cycling performance and less limitation of electrolyte choice than the latter. Furthermore, the Li₄Ti₅O₁₂-limited cell exhibits better tolerance to high voltage and overcharge than the LiNi_0.5Mn_1.5O₄-limited cell, owing to taking advantage of the extra capacity of Li₄Ti₅O₁₂ below 1 V. It is thus recommended that the LiNi_0.5Mn_1.5O₄/Li₄Ti₅O₁₂ cell whose capacity is limited by Li₄Ti₅O₁₂ anode should be used to extend the application of the state-of-the-art lithium-ion batteries.     

Electrochemical properties of the LaNi3.55Mn0.4Al0.3Co0.4Fe0.35 hydrogen storage alloy

The electrochemical properties of LaNi_3.55Mn_0.4Al_0.3Co_0.4Fe_0.35 hydrogen storage alloy have been studied through chronopotentiometric, chronoamperometric and cyclic voltammogram measurements. The maximum capacity value obtained was 265 mAh g⁻¹ at rate C/6 and the capacity decrease was recorded by 1.5% after 30 cycles. The values of the hydrogen diffusion coefficient D_H obtained through cyclic volammogram and chronoamperometric techniques were, respectively, 7.01 × 10⁻⁸ cm² s⁻¹ and 4.23 × 10⁻¹¹ cm² s⁻¹.     

Comparative analysis of the hydriding kinetics of LaNi5, La0.8Nd0.2Ni5 and La0.7Ce0.3Ni5 compounds

In two-phase domains, the plateau pressure of hydride forming materials (such as intermetallic compounds or IMCs) depends markedly on the operating temperature (Van’t Hoff relationships). Therefore, for practical applications, it is necessary to select hydrogen storage materials by considering the thermal environment of the hydride tank. The thermodynamic properties (absorption and desorption pressure plateaux) of IMCs can be adjusted to some extend by chemical alloying with foreign metals and substitution on different crystallographic sites. In this paper, we report on the hydriding kinetics of substituted AB₅ compounds. Isotherms have been measured at different temperatures on La_xNd_1−xNi₅ (x ≈ 0.2) and La_xCe_1−xNi₅ (x ≈ 0.3) compounds. Pneumato-chemical impedance spectroscopy has been used to analyze the hydriding kinetics and to determine microscopic rate parameters associated with surface dissociation of molecular hydrogen, diffusion-controlled transport of atomic hydrogen to bulk regions and hydride formation. Results have been compared to those measured on LaNi₅ and the interest of using such substituted compounds for application in auxiliary power units is discussed.     

Effect of TiO2-coating on the electrochemical performances of LiCo1/3Ni1/3Mn1/3O2

A novel method to improve the cycling performance of LiCo_1/3Ni_1/3Mn_1/3O₂ in lithium-ion batteries by TiO₂-coating with an in situ dipping and hydrolyzing method was presented in this work. The microstructure of the TiO₂-coated LiCo_1/3Ni_1/3Mn_1/3O₂ was characterized by XRD, SEM and TEM, and their electrochemical performances were evaluated by EIS and galvonostatic charge-discharge test. SEM and TEM images show that the TiO₂ are pasted on the surface of the LiCo_1/3Ni_1/3Mn_1/3O₂ with nano-size. The XRD patterns indicate that the crystal structure of the TiO₂-coated LiCo_1/3Ni_1/3Mn_1/3O₂ shows no obvious change compares with the bare material. The TiO₂-coated LiCo_1/3Ni_1/3Mn_1/3O₂ possesses improved cycle performance and rate capability. The capacity retention of 1.0 wt.% TiO₂-coated material is more than 99.0% after 12 cycles at 3.0 C while that of the bare sample is only 86.6%. The capacity of coated material at 5.0 C remains 66.0% of the capacity at 0.2 C, while that of the bare LiCo_1/3Ni_1/3Mn_1/3O₂ is only 31.5%.     

Electrochemical properties of the Mm0.3Ml0.7Ni3.55Co0.75Mn0.4Al0.3 alloy mixed with Ni powder

Composites of Mm_0.3Ml_0.7Ni_3.55Co_0.75Mn_0.4Al_0.3 alloy and Ni powders were mechanically synthesized and electrochemically tested in 6 M KOH electrolyte. In this work, the electrochemical properties of the alloys were greatly improved by mixing them with Ni, which plays a corrosion-resistance role in the alkali electrolyte and helps electron conduction. It has been shown that the numbers of activation cycles decreased compared with the alloys without Ni powder. All the alloys were activated after the second cycle. Improvements of the maximum discharge capacities were also found in this work. A maximum discharge capacity of 358 mAh g⁻¹ was measured in the Mm_0.3Ml_0.7Ni_3.55Co_0.75Mn_0.4Al_0.3 + 250 wt.% Ni composite. In addition to that, adding Ni was found to enhance the high-rate discharge ability of the alloys, which appear to be good candidates for the realization of MH battery electrodes.     

Transition metal-catalyzed dehydrogenation of hydrazine borane N2H4BH3via the hydrolysis of BH3 and the decomposition of N2H4

Hydrazine borane N₂H₄BH₃ (denoted HB) is a novel candidate in hydrogen generation by catalytic hydrolysis. The challenge with this material is the dehydrogenation of the N₂H₄ moiety, which occurs after the hydrolysis of the BH₃ group. This challenge requires the utilization of a reactive and selective metal-based catalyst. In this work, we considered various transition metal salts as precursors of in situ forming catalysts by reduction in the presence of HB. According to their reactivity, the metals studied can be classified into 3 groups: (1) Fe- and Re-based catalysts, showing a limited reactivity in the hydrolysis of the BH₃ group; (2) Co-, Ni-, Cu-, Pd-, Pt- and Au-based catalysts, only active in the hydrolysis of BH₃ (3 mol H₂ per mol HB generated); (3) Ru-, Rh, and Ir-based catalysts, being also active in the decomposition of N₂H₄. With the Rh-based catalyst, characterized as agglomerated Rh⁰ nanorods (10 × 4 nm) by XRD, TEM, SAED and XPS, 4.1 mol H₂ + N₂ per mol HB can be produced at 50 °C. Rhodium is thus a possible candidate for synthesizing nanosized particles and bimetallic nanoalloys in order to tune its reactivity and increase its selectivity up to the targeted conversion of 100%. Our main results are reported herein and the behavior of the metals is discussed.     

The effect of annealing on the electrochemical properties of Zr0.5Ti0.5Mn0.5V0.3Co0.2Ni1.1 alloy electrodes

The annealing treatment was found to result in the improvement in the cyclic stability but the degradation of discharge capacity, activation and high-rate dischargeability for Zr_0.5Ti_0.5Mn_0.5V_0.3Co_0.2Ni_1.1 alloy electrode. A lower discharge potential in the annealed alloy electrode was found owing to a more homogeneous alloy, which is consistent with the pressure–composition isotherms (P–C–T) measurement. We found that the annealed alloy also had lower and flatter pressure plateaus, and larger pressure hysteresis. At high discharge rates, the hydrogen diffusion in the bulk of the alloy was the rate-determining step. The diffusion coefficients for hydrogen in the annealed and as-cast alloys were calculated to be 1.4×10⁻¹² cm² s⁻¹ and 4.3×10⁻¹² cm² s⁻¹, respectively. The lowering of high-rate discharge capacity can be ascribed to the reason that the hydrogen diffusion coefficient is lower due to homogeneous microstructure in the annealed alloy.     

Solar water-splitting with the defect pyrochlore type of oxides KFe0.33W1.67O6 and Sn0.5Fe0.33W1.67O6·xH2O

Defect pyrochlore of composition KFe_0.33W_1.67O₆ (KFeW) was synthesized by ethylene glycol assisted sol–gel method. The divalent tin doped KFeW (SnFeW) was prepared by ion exchange process using acidified SnCl₂. Structural, morphological and optical properties of both materials were characterized by XRD, TGA, SEM-EDS, BET surface analyses and UV–visible diffuse reflectance techniques. The composition of tin-doped KFeW was obtained from EDS and TGA profiles. The cubic lattice parameter 'a' was obtained from Rietveld refinement program, Fullprof.2k, by refining the d- lines of the KFeW. The optical properties of Fe³⁺ were investigated. Substitution of K⁺ by Sn²⁺ led to an absorption shift onset to longer wavelengths. The photocatalytic activities of both samples were evaluated by photodegradation of methylene blue, photooxidation of cyclohexene and solar water-splitting reactions. The mechanistic degradation pathway of methylene blue (MB) was studied in the presence of both photocatalysts.     

Microstructural improvements of the gradient composite material Pr0.6Sr0.4Fe0.8Co0.2O3/Ce0.8Sm0.2O1.9 by employing vertically aligned carbon nanotubes

Ionic–electronic conductor composite materials are widely employed to improve the ionic conductivity of solid oxide fuel cell electrodes, making them more compatible with the solid oxide fuel cell materials. The addition of an ionic conductor implies, however, a decrease of the cathode active area for the oxygen reduction reactions. In addition, the ionic conductor particles are usually dispersed and isolated, limiting the enhanced properties to certain areas. In order to avoid this drawback and improve the ionic conductivity of the electrode, vertically aligned carbon nanotubes (VACNTs) have been synthesized and employed as template for the deposition of Sm_0.2Ce_0.8O₂ (SDC) particles. Subsequently, these SDC-VACNTs have been coated with a Pr_0.6Sr_0.4Fe_0.8Co_0.2O₃ (PSFC) perovskite phase, leading to the formation of the desired composite material. Attending to the obtained results, it is proved that the new composite material exhibits a significantly better electrochemical performance, due to a better distribution of the ionic conductor and the burning of the carbon nanotubes (CNTs), which result in the improvement of the microstructure.     

On the LiNi0.2Mn0.2Co0.6O2 positive electrode material

Layered LiNi_0.2Mn_0.2Co_0.6O₂ phase, belonging to a solid solution between LiNi_1/2Mn_1/2O₂ and LiCoO₂ most commercialized cathodes, was prepared via the combustion method at 900 °C for a short time (1 h). Structural, electrochemical and magnetic properties of this material were investigated. Rietveld analysis of the XRD pattern shows this compound as having the α-NaFeO₂ type structure (S.G. R-3m; a = 2.8399(2) ?; c = 14.165(1) ?) with almost none of the well-known Li/Ni cation disorder. SQUID measurements clearly indicate that the studied compound consists of Ni²⁺, Co³⁺ and Mn⁴⁺ ions in the crystal structure. X-ray analysis of the chemically delithiated Li_xNi_0.2Mn_0.2Co_0.6O₂ phases reveals that the rhombohedral symmetry was maintained during Li-extraction, confirmed by the monotonous variation of the potential-composition curve of the Li//Li_xNi_0.2Mn_0.2Co_0.6O₂ cell. LiNi_0.2Mn_0.2Co_0.6O₂ cathode has a discharge capacity of ∼160 mAh g⁻¹ in the voltage range 2.7-4.3 V corresponding to the extraction/insertion of 0.6 lithium ion with very low polarization. It exhibits a stable capacity on cycling and good rate capability in the rate range 0.2-2 C. The almost 2D structure of this cathode material, its good electrochemical performances and its relatively low cost comparing to LiCoO₂, make this material very promising for applications.