A novel cyclic process using CaSO<Subscript>4</Subscript>/CaS pellets for converting sulfur dioxide to elemental sulfur without generating secondary pollutants: Part I. Feasibility and kinetics of the reduction of sulfur dioxide with calcium-sulfide pellets

Certain new sulfide-smelting processes and coal-gasification processes generate high-strength sulfur dioxide streams, for which a new process for converting sulfur dioxide to elemental sulfur needs to be developed because no process exists that is generally and economically applicable to the treatment of such streams. A thermodynamic and experimental investigation to develop a new process for converting sulfur dioxide to elemental sulfur by a cyclic process involving calcium sulfide and calcium sulfate without generating secondary pollutants was carried out. In this process, the starting raw material, calcium sulfate, is reduced by a suitable reducing agent, such as hydrogen, to produce calcium sulfide, which is used to reduce sulfur dioxide to elemental sulfur vapor and calcium sulfate. The latter is, in turn, reduced to regenerate calcium sulfide. In this Part I, detailed experimental results are presented on the kinetics of the reaction between sulfur dioxide and calcium-sulfide pellets, which produces elemental sulfur and calcium sulfate. The experiments were carried out at temperatures between 1023 and 1088 K and sulfur-dioxide partial pressures between 9 and 60 kPa by the use of a thermogravimetric analysis (TGA) technique. The rate of this reaction was demonstrated by the conversion of 40 pct calcium-sulfide pellets obtained from the hydrogen reduction of fresh calcium sulfate in 10 minutes at 1073 K under a sulfur-dioxide partial pressure of 43 kPa. The reactivity decreased somewhat during the first three cycles but remained largely unchanged thereafter up to the tenth cycle. This characteristic of the pellets is important because the solids must be reusable for repeated cycles to avoid generating secondary pollutants. A pore-blocking model was found to fit the reaction rate. The reaction is first order with respect to sulfur-dioxide partial pressure and has an activation energy of 101 to 134 kJ/mol (24 to 32 kcal/mol) for calcium-sulfide pellets reacted and regenerated several different times. Sulfur dioxide-containing streams from certain sources, such as the regenerator off-gas from an integrated-gasification, combined-cycle, desulfurization unit and new sulfide-smelting plants, contain much higher partial pressures of SO₂. In these cases, the rate of the first reaction is expected to be proportionally higher than in the test conditions reported in this article. The reduction kinetics of calcium-sulfate pellets with hydrogen gas is reported in the accompanying Part II.     

HA型粘结剂性能评判的研究

冷固结球团直接还原工艺成功的关键因素之一是成型粘结剂的选用。粘结剂性能评判 ,传统的方法是通过考查球团矿的机械强度来说明粘结剂性能的优劣 ,步骤繁锁。经过试验研究 ,本文提出了用粘度大小来评判粘结剂性能的直接方法并从理论上进行了论证。对于 HA型复合粘结剂 ,在六速旋转粘度计上测量 ,50 g复合粘结剂的粘度若大于或等于 6.5× 1 0 -3 Pa·s,表示粘结剂性能较好 ,能满足铁精矿冷固球团直接还原工艺的要求 ;若小于或等于 3.0× 1 0 -3 Pa· s,则表示该粘结剂性能较差。     

聚合物降解产物伤害与糖甙键特异酶破胶技术

综述了钻井，完井，尤其是水力压裂作业中产生的多糖类聚合物伤害和应用糖甙键特异酶破胶，解除多糖类聚合物伤害的技术。第一节报道了聚合物降解产物造成的伤害，指出冻胶破胶液粘度低并不代表压裂液已从充填裂缝中充分返排，氧化破胶剂和普通酶破胶剂不能使多糖类聚合物充分降解，产生的大分子量，水不溶的降解产物可对地层造成伤害，消除伤害的办法是采用对糖甙键有特异性的各种水解酶作压裂液破胶剂或伤害地层处理剂。第二节报道了各种聚合物（纤维素，瓜尔胶，淀粉）糖甙键特异酶降解聚合物的机理。第三节报道了糖甙键特异酶（主要针对瓜尔胶）的应用性能测试及结果，包括岩心流动实验，含糖量和分子量测定，传导性测试。第四节介绍了糖甙键特异酶消除聚合物伤害和用作压裂液破胶剂的现场应用，包括选井原则，实施工艺要点及3个典型井例。     

TPS分散型控制系统在骤冷风空调装置中的应用

主要介绍了Honeywell公司TPS系统在直纺涤纶长丝用骤冷风空调装置中的应用。重点说明了该系统的硬件配置和一些复杂控制回路的实施和组态。     

国内外乙丙橡胶市场供需状况

介绍了国内外乙丙橡胶市场的供需状况，并对我国乙丙橡胶的产业发展提出了建议。     

定向棱镜腔平顶高斯激光束特性的研究

在XeCl准分子激光器中,采用定向棱镜作为端反射镜与平面输出镜构成激光器谐振腔,获得了近场能量分布均匀、远场能量分布高度集中的相干平顶高斯激光束输出,并具有腔镜高抗失调能力,改善了激光束质量。     

1/f Noise separated from white noise with wavelet denoising

The low-frequency noise in the devices often appears to be a superposition of 1/f noise and white noise, which are induced by different physical mechanisms or microscopic defects. The separation of the two noises is necessary especially in the characterization of quality and reliability by means of noise measurement. The traditional separation method is usually used in frequency domain with limited frequency range, and the estimated value of exponent index γ for 1/f^γ noise has considerable error when the ratio of 1/f noise and white noise is smaller than 20 dB. In this paper, based on wavelet denoising theory, a new method is proposed to separate 1/f^γ noise from white noise in time domain and can be used to estimate γ values with much better accuracy even if the ratio of 1/f noise to white noise in low enough.     

胃肠道激光内镜应用技术

本文结合作者的体验和文献，详细介绍了激光光导纤维检查与准备，激光内镜在胃肠道疾病应用的技巧、方法和注意事项等，可为临床医生和相关技术人员提供帮助。     

绿色食品与绿色包装

介绍了食品绿色包装与环境保护的关系，探讨了食品绿色包装材料的选择及应用，食品绿色包装设计及市场价值等方面的内容。     

全IP移动通信网网络层移动性管理

首先介绍了全IP移动通信网网络层移动性管理的概念、框架和最经典的移动IP（Mobile IP）协议，然后讨论了基于Mobile IP的四种主要扩展方案：蜂窝IP、切换敏感无线接入Internet结构（HAWAII)、电信增强移动IP（TeleMIP）和边缘移动性体系结构（EMA）方案，最后结合第三代移动通信发展的状况得出了一些结论。