气流磨超细粉碎循环流化床锅炉脱硫灰的试验研究

为提高循环流化床燃煤锅炉脱硫灰在工程上的利用率,利用气流磨对循环流化床脱硫灰进行超细粉碎,通过调节分级机频率大小进行分组实验。结果表明:CaO和SO3组分含量在循环流化床脱硫灰中所占比例大,质量分数分别达26.84%和12.25%;采用气流磨粉碎循环流化床脱硫灰,有效地增大了CaO的比表面积,通过调节分级机的频率可获得窄粒度段分布的超细脱硫灰,获得的超细脱硫灰颗粒表面粗糙,凹凸不平,呈不规则形状。     

浅析循环流化床锅炉脱硫

就循环流化床锅炉二氧化硫析出方式、脱硫机理、脱硫效率影响因素等方面分析循环流化床锅炉脱硫。     

循环流化床锅炉炉内脱硫的研究

循环流化床锅炉作为一种洁净煤技术,通过炉内喷石灰石粉脱硫能够达到较高的脱硫效率,SO2排放完全能够满足国家及地方环保部门要求。本文对循环流化床锅炉炉内脱硫技术原理,循环流化床锅炉脱硫的影响因素等作了简要探讨。     

基于混烧循环流化床锅炉炉内优化脱硫技术的研究

通过对混烧循环流化床锅炉炉内喷钙系统脱硫机理研究,分析了影响脱硫效果的主要因素,提出循环流化床锅炉实际脱硫过程中存在的诸多问题,通过对存在的问题提出控制优化方案,能达到循环流化床锅炉烟气达标排放,减少污染,利于环保。     

烧结机循环流化床烟气脱硫技术的分析研究

本文根据某钢铁集团有限公司烧结机的实际情况和要求,分析提出了采用循环流化床烟气脱硫技术来进行烧结烟气脱硫。文中介绍了循环流化床烟气脱硫技术的工艺原理、特点、设备、主要性能参数对脱硫效率的影响等。     

循环流化床锅炉脱硫技术

介绍了我国循环流化床锅炉脱硫现状,重点讨论了循环流化床锅炉炉内喷钙脱硫技术、炉内喷钙烟气半干法脱硫技术和炉内喷钙烟气湿法脱硫技术。结合现有的环保政策和脱硫成本,炉内喷钙脱硫技术难以满足现有环保要求;对燃用低硫煤循环流化床锅炉,建议采用炉内喷钙烟气半干法脱硫技术,该技术可以满足环保要求,且脱硫成本较低;对燃用高硫煤循环流化床锅炉,建议采用炉内喷钙烟气湿法脱硫技术,该技术能满足环保要求,但脱硫成本较高。     

循环流化床锅炉如何降低石灰石消耗

流化床锅炉是一种国际公认的洁净煤燃烧技术,以其燃料适应性广、脱硫效果好、NOx排放量低、负荷调节性能好等优点在我国燃煤电站中方兴未艾。随着国家对环保的日益重视,具有循环流化床锅炉的企业不得不重新对脱硫设施进行完善,本文通过对循环流化床锅炉石灰石脱硫工艺进行探讨,从而对循环流化床锅炉在运行中炉内脱硫如何减少石灰石用量起到一定的借鉴意义。     

连州发电厂通过对石灰石系统优化改造提高炉内脱硫效果

根据生产实际经验对连州发电厂135MW循环流化床锅炉的脱硫方法进行介绍，并通过实际运用对循环流化床石灰石系统优化改造后的效果说明连州发电厂在节能减排上所做的努力和成果。     

循环流化床锅炉运行调整及炉内脱硫

本文简要介绍循环流化床锅炉燃烧原理、运行调整及炉内脱硫，可供运行人员参考。     

循环流化床炉内喷钙和石灰石/石膏湿法脱硫的技术分析

循环流化床锅炉具有燃烧效率高、适应范围广的特点,在现代工业中得到了普遍的应用,而且在实施的过程中又得到了不断地改进和优化。本文主要对循环流化床锅炉炉内的脱硫原理和影响因素进行了分析,并对提高流化床炉喷钙和石灰石的脱硫效率提出了一些参考建议。     

Investigation of Near-Critical States of Molybdenum by Method of Isentropic Expansion

In this work release isentropes of shocked porous molybdenum were investigated. Samples with an initial porosity m = ρ₀/ρ = 1.4 and 3.1 were studied to achieve near-critical entropy states of metal after shock compression. Compressed samples were expanded into helium with different initial pressures. The brightness temperature of the metal and the helium shock wave velocity were measured with a fast multichannel pyrometer. The helium shock wave velocity was used to determine the final pressure (P_S) of expansion of the metal and the velocity of metal expansion (W_S). Location of peculiarities on the P_S–W_S and P_S–T_P curves of the isentropes gives the location of their entrance into the two-phase region. Estimation of the molybdenum critical temperature and pressure was carried out on the basis of the experimental data. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

Some New Aspects of Chlorination of Fullerenes

Abstract

The effect of the reagent ratio, reaction time and power of the reagent on the product composition in chlorination of [60]fullerene was studied. Chlorofullerenes C₆₀Cl₆, C₆₀Cl₈, C₆₀Cl₁₀, C₆₀Cl₁₂, C₆₀Cl₁₄, and C₆₀Cl₂₆ were synthesized and characterized by chemical analysis, FTIR, ¹³C NMR, and MALDI TOF mass spectrometry. The experimental data supported the coexistence of several isomers of C₆₀Cl _n (n = 8, 10, 12, 14, 26); the mixtures were not separated so far. Semiempirical calculations (AM1, PM3) were used to analyze the addition patterns and resulted in the most favorable structures of C₆₀Cl_8–26. Chlorination of C₇₀ under various conditions invariably yielded C₇₀Cl₁₀.     

Viscosity of Some Binary Mixtures of Arenes

The viscosity of 12 binary mixtures of benzene+toluene, +ethylbenzene, +isopropylbenzene, +tert-butylbenzene; toluene+ethylbenzene, +isopro- pylbenzene, +tert-butylbenzene; ethylbenzene+isopropylbenzene; isopropylbenzene+tert-butylbenzene; o-xylene+m-xylene; m-xylene+p-xylene; and p-xylene+o-xylene has been measured over the entire range of composition. The viscosity deviations and excess Gibbs energy of activation G ^*E of viscous flow based on Eyring's theory have been calculated. The results have been analyzed in terms of the change in the structure of pure component molecules. The viscosity data have been correlated with the equations of Grunberg and Nissan; Hind, McLaughlin, and Ubbelohde; Tamura and Kurata; Katti and Chaudhri; McAllister; and Heric and Brewer. The Prigogine–Flory–Patterson– Bloomfield–Dewan (PFPBD) theory has been applied to analyze the excess viscosity of the present binary mixtures.     

Review of Applications of High-Temperature Superconductors

Since the discovery of high-T _c superconductor oxides in 1986, much research and development have been carried out, and much progress has been made. In the last ten years our efforts have been devoted to the development of materials technologies for these difficult materials, and remarkable progress has been made. This is a great contribution not only for application but also for fundamental research on high-T _c superconductors. In this paper, we will present a review of applications of high-T _c superconductors discovered in the last ten years. At present, it can be said that we are in the transition period from the period of growth to the period of specialization, looking for future applications of high-T _c superconductivity.     

Molecular dynamics calculation of thermal expansion coefficient of a series of rare-earth zirconates

To develop more reliable and stable thermal barrier coatings, low thermal conductivity materials with higher thermal expansion coefficients (TECs), like rare-earth zirconates (A₂Zr₂O₇, A = La, Nd, Sm, Eu, Gd, Er, Yb and Lu), have been the focus of a great deal of attention in recent years. But the mechanisms underlying the values of TECs are still poorly understood. In this paper, the TECs of a series of rare-earth zirconates are calculated using molecular dynamics. Two typical crystal structures, pyrochlore and fluorite, are considered. By investigating the potential functions and the equilibrium-location deviations between the atoms, it is found that the Zr–O bond is the most important factor that determines the overall TECs, and the A–O bond plays a secondary role. However, O–O has little effect on the TECs. In addition, the fluorite structure has a relatively higher TEC due to a weaker Zr–O bond. Calculated values are consistent with the experimental observations. Using the method presented in this study, two doped zirconates (Gd_0.4Sm_0.5Yb_0.1)₂Zr₂O₇ and Sm₂(Ce_0.3Zr_0.7)₂O₇ are designed and compared. As expected, both of them have higher TECs than undoped Sm₂Zr₂O₇, and doping at the A-site is more efficient than doping at the Zr-site.     

Improvement of yield strength of LM24 alloy

In this study, Al₂O₃ particles were employed to improve the microstructure of LM24 and therefore, to increase the yield strength and tensile strength of this kind of alloy. In situ Al₂O₃ particles were obtained by direct reaction between oxygen and Al melt at 750–800 °C. Microstructure examination shows that the size of in situ formed Al₂O₃ particles was about 1–2 μm, and interestingly, with addition of in situ Al₂O₃ particles, the coarse primary Si phase was disappeared completely. More important, the yield strength and the tensile strength of Al₂O₃/LM24 are increased by 52 MPa, 16 MPa than that of LM24 alloy with 0.1% Sb addition. The value of 181 MPa and 315 MPa is for yield strength and tensile strength of Al₂O₃/LM24 respectively. Besides, the yield strength and tensile strength are 180 MPa and 314 MPa respectively for Al₂O₃/LM24 alloy after remelting and casting. This verifies that the improvement of mechanical properties of such kind of material possesses stability and reliability.     

Experimental Study of the Critical Behavior of the Isochoric Heat Capacity of Aqueous Ammonia Mixture

The isochoric heat capacity of a NH₃ + H₂O (0.2607 mole fraction of ammonia) mixture has been measured in the near- and supercritical regions. Measurements were made in the single- and two-phase regions including the coexistence curve using a high-temperature, high-pressure, nearly constant-volume adiabatic calorimeter. Measurements were made along 38 liquid and vapor isochores in the range from 120.03 kg · m⁻³ to 671.23 kg · m⁻³ and at temperatures from 478 K to 634 K and at pressures up to 28 MPa. Temperatures at the liquid–gas phase transition curve, T _S(ρ), for each measured density (isochore) and the critical parameters (T _C and ρ _C) for the 0.2607 NH₃ + 0.7393  H₂O mixture were obtained using the quasi-static thermograms technique. The expanded uncertainty of the heat-capacity measurements at the 95 % confidence level with a coverage factor of k = 2 is estimated to be 2 % to 3 % in the near-critical and supercritical regions, 1.0 % to 1.5 % in the liquid phase, and 3 % to 4 % in the vapor phase. Uncertainties of the density, temperature, and concentration measurements are estimated to be 0.06 %, 15mK, and 5×10⁻⁵ mole fraction, respectively. An unusual behavior of the isochoric heat capacity of the mixture was found near the maxcondetherm point (in the retrograde region). The value of the Krichevskii parameter was calculated using the critical properties data for the mixture and vapor-pressure data for the pure solvent (H₂O). The derived value of the Krichevskii parameter was used to analyze the critical behavior of the strong (C _P , K _T ) and weakly (C _V ) singular properties in terms of the principle of isomorphism of critical phenomena in binary mixtures. The values of the characteristic parameters (K ₁, K ₂), temperatures (τ ₁, τ ₂), and the characteristic density differences (Δρ ₁, Δρ ₂) were calculated for the NH₃ + H₂O mixture by using the critical-curve data.     

Determination of the Critical Point of Gold

Wire-shaped gold specimens are placed in a new, improved high-pressure vessel, which is part of a fast capacitor-discharge circuit and in which static pressures above 600 MPa can be reached with distilled water as the pressure-transmitting medium. The specimens are self-heated resistively by a current pulse. The current through the specimen, the voltage drop across it, and its temperature are recorded as a function of time with submicrosecond resolution. The radial expansion of the specimen is determined with a CCD camera, Experiments are performed at different pressures. When the critical pressure is exceeded, there is no liquid–gas phase transition; hence, no sudden change in the thermal expansion rate is observed. The results for temperature, pressure, and specific volume at the critical point of gold are as follows: T _c =7400±1100 K, p _c=530±20 MPa, and v _c=0.13±0.03 × 10^–3m³·kg^–1.     

Computational evaluation of flexural toughness of FRC and fracture properties of plain concrete

In this paper, a computational tool concerning the computation of flexural and fracture toughness of cement based composites is presented. Firstly, RILEM’s (Réunion Internationale des Laboratoires d’Essais de Matériaux) recommendations related to the analysis of FRC in three-point bend tests are discussed in their relevant aspects regarding the computational implementations. The determination of other mechanical properties such as the Young modulus has been added to the program. Taking this into account, a new formulation based on displacements is used. In the second part of the paper, the determination of fracture properties of concrete, such as the fracture energy, G _F , and the fracture toughness, K _IC ^S , is discussed regarding the computational strategies used in the implementations. Several features whereby anterior data can be reanalyzed, obtained from other standards and recommendations, have been incorporated into the program, therefore allowing comparative studies and back analysis activities.     

The Distribution of the Maximum Sum of Rank

In this paper a c-sample slippage analogue of the Wilcoxon [11] test is considered. Given a sample of size n for each of c populations, the test rejects the hypothesis that the c populations are identical when max_1≤i≤c σ _k r _ik > λ, where r _i1, …, r _in are the ranks of the observations from the i-th population in the combined sample of size cn. The small and large sample distributions of the test statistic are derived. Tables of the exact distribution are given for c = 2(1)5, n = 2(1)5. Tables of critical values are given for c = 2(1)6, n = 2(1)8 for values of α = 0.001, 0.005, 0.01, 0.025, 0.05, 0.10, and 0.20.