Xenon recovery from natural gas by multiple gas hydrate crystallization: a theory and simulation

ABSTRACT

For efficient xenon (Xe) recovery from natural gas (NG), multiple gas hydrate crystallization was considered. The optimal stages’ number for effective Xe recovery from model gas mixtures with close composition to NG one was determined. Gas hydrate distribution’s coefficients are defined for these gases at each stage, and each iterations of the multiple gas hydrate crystallization. In CH₄+ H₂S+CO₂+ Xe gas mixture that is closest to NG composition, the maximum average Xe concentration in the gas hydrate phase was observed at the second stage of the multiple gas hydrate crystallization.     

Simulations of primary and secondary gas penetration for a gas-assisted injection-molded thin part with gas channel

Numerical simulations and experimental studies concerning melt flow and primary as well as secondary gas penetration during the filling and the postfilling stages in gas-assisted injection molding of a thin plate with a semicircular gas channel design were conducted. Distribution of the skin melt thickness along the gas-penetration direction was measured to identify primary and secondary gas penetration. Melt and gas flow within the gas channel of a semicircular cross section is approximated by a model which uses a circular pipe of an equivalent hydraulic diameter superimposed on the thin part. An algorithm based on the control-volume/finite-element method combined with a dual-filling parameter technique suitable for the tracing of two-component flow-front advancements is utilized and numerically implemented to predict both melt- and gas-front advancements during the melt-filling and the gas-assisted filling processes. A flow model of the isotropic melt-shrinkage origin combined with a gapwise layer tracing algorithm was implemented to assist the prediction of secondary gas penetration and melt flow in the post-filling stage. Simulated results on the gas front locations at the end of both primary and secondary penetration phases show reasonably good coincidence with experimental observations. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1553–1564, 1998     

Surfactant effects on gas absorption in a coke-oven gas treatment process

The effect of organic impurities in industrial stripped coal water (SCW) on the absorption of CO₂ was measured experimentally. Removal of these impurities via activated carbon showed a marked improvement in interphase mass transfer of a vertical wetted-wall column absorber. However, this benefit was not found in a stirred-cell absorber, in which a different flow pattern from that in wetted-wall column absorber is expected. An ad hoc systematic study on the effects of three deliberately added surfactants on gas absorption by pure water in three different absorbers with different flow patterns was thereafter conducted. The experimental results reveal that absorption deterioration also prevails only in a vertical, wetted-wall column absorber and the reduction in liquid phase mass transfer by the addition of surfactant can be satisfactorily correlated with surface pressure of solutions. This indicates that the effect of the industrial impurities in SCW on gas absorption may successfully be simulated under the same flow pattern by a surfactant solution with the same surface pressure. A possible modification of the existing coke-oven gas (COG) treatment process for the benefit of absorption enhancement was finally proposed.     

焦炉煤气配加转炉煤气生产甲醇工艺介绍

介绍了焦炉煤气配加转炉煤气生产甲醇的工艺流程及主要技术特点。该工艺开辟了利用转炉煤气的新方法,可充分利用新鲜气的有用成分,具有增产甲醇和降低消耗等优点。     

氯气尾气处理系统的改造

介绍离子膜法烧碱生产工艺中氯气尾气处理系统的改造方案,并指出将尾气处理系统与事故氯气处理系统合二为一的可行性。     

天然气转化制备合成气工艺进展

综述了天然气转化制备合成气的国内外工艺技术进展，提出了一些看法和观点。     

可燃气体和有毒气体检测报警装置的设计标准化研究

针对可燃气体和有毒气体的检测报警装置,有不同的设计规范,主要分析对比了若干不同规范间的异同,希望对相关从业人员有所帮助。     

Transient analysis of a gas manifold system

In the present work, a numerical study has been carried out to predict transient gas flow and pressure behaviour in a gas manifold system. The start‐up and shutdown of the system, varying demands at the consumer ends, malfunctioning of compressors and valves are a few examples of common causes of transience in a gas delivery system. In particular, the sensitivity of oscillations in pressure and mass flux to variation in pipe dimensions, supply pressure and gas flow rate are ascertained under the aforementioned conditions of transience. The present results show that large pipe dimensions, high gas flow rate and high upstream pressure in the branch in which the disturbance is introduced, all cause greater amplitude in mass flux and pressure oscillations in the neighboring branches. The duration of oscillations is also found to be longer. The present study has practical importance in designing as well as in operating, a gas delivery system.     

A new process for synthesis gas by co-gasifying coal and natural gas

Production of synthesis gas with coal and natural gas co-gasification is a new process based on coupling of methane steam-reforming and coal gasification. The process concept is discussed in this paper. Experiments are carried out in a laboratory fixed-bed gasifying reactor to investigate the effect of feedstock on composition, ratio of hydrogen to carbon monoxide, concentrations of hydrogen and carbon monoxide in the produced raw synthesis gas. Preliminary experimental results indicate that the effect of steam flow rate on component, ratio of hydrogen to carbon monoxide and concentrations of hydrogen and carbon monoxide of the raw synthesis gas is slight, while the effect of oxygen flow rate is pronounced. When the ratio of oxygen to methane in feedstock is below 1, the ratio of hydrogen to carbon monoxide is greater than 1 and the total concentration of hydrogen and carbon monoxide is above 90%. Comparison of experimental results with calculated results shows that the composition of raw synthesis gas is near equilibrium.     

Fractional gas hold-up in gas inducing type of mechanically agitated contactors

Fractional gas hold up was measured in gas inducing type of mechanically agitated contactors (GIMAC) with single and multiple impellers. Three vessels of 0.57, 1.0 and 1.5 m i.d. were used. For the multiple impeller system, six different impeller designs were employed. The impeller speed was varied in the range of 0.30 to 15.45 s^?1. The ratio of impeller diameter to tank diameter (D/T), the submergence (S) of the upper impeller, the clearance of the lower impeller from the tank bottom (C₁) and the impeller spacing (C₃) were varied over a wide range. The design of the lower impeller was optimized in terms of diameter (D), blade width (W), blade angle (Bø), number of blades (n_b) and the blade thickness (t_b). An optimum design has been proposed for the multiple impeller system. Rational correlations have been proposed.     

一种烟气脱硫絮凝剂的改进方案与效果评价

烟气脱硫废水温度高、颗粒物重,烟气脱硫适用絮凝剂很少,本文改进了聚丙烯酰胺的常用浓度,大大提高了絮凝效果,降低了脱硫废水的吨处理费,为烟气脱硫装置提供了新的絮凝方式。     

液相微萃取-气相色谱法测定水中芥子气的研究

本文研究了液相微萃取-气相色谱法在检测水中芥子气方面的应用。考查了萃取溶剂、萃取时间、盐效应对萃取的影响。优化了萃取条件:萃取溶剂为1μL甲苯,萃取时间25min,搅拌速度170r.min-1。方法的线性范围0.07~3.70mg.L-1,最小检出限0.06mg.L-1,方法精密度6.6%。富集倍数为44~54;回收率在1.45%~1.8%之间。实验表明,该方法简便、灵敏、消耗有机溶剂少,可以用于水中芥子气的富集检测。     

Fuel gas from a wood waste carbonization reactor

The production of fuel gas from wood wastes in a full scale carbonization reactor of simple design was studied. The production of methane and the approach to equilibrium to the water-gas shift reaction were experimentally correlated with the operating conditions. The heating value of the gas produced is comparable to that of typical air blown coal and biomass gasifiers, and may be improved by pre-drying the solid feed and by operating the reactor at lower temperatures.     

移动床煤与天然气共气化制备合成气的工艺技术

煤与天然气共气化是基于天然气蒸汽转化和煤气化工艺耦合的一种新工艺.阐述了煤与天然气共气化制合成气的技术原理.实验研究表明合成气最佳出口温度为1000 ℃,氧气、水蒸气和天然气在同一位置进入反应器能有效降低火焰区温度;理论计算得到的合成气有效气体浓度（CO+H₂）大于95%.实验研究和理论计算结果都表明,煤与天然气共气化可以直接得到H₂/CO在1.0～1.5之间可以调节的合成气.     

天然气部分氧化制合成气的研究和实践

叙述了天然气部分氧化法制合成气的原理、国内外的开发和生产情况。并用模拟法进行了部分氧化工艺优化条件的研究，提出了这一方法的使用范围。     

中国焦炉煤气制天然气技术进展及经济性分析

简要分析了中国天然气产业发展现状以及面临的严峻形势。提出了利用焦炉煤气生产天然气的必要性和紧迫性。分析了这一技术的研究进展。运用技术经济的分析方法,对发展液化天然气（LNG）和合成天然气（SNG）进行了定量分析。结果表明,生产LNG产品的效益要高于SNG产品。前者较后者的投资利税率提高了18．9％,投资利润率提高了7．9％。     

电解氯气和氢气除湿过程的节能措施

介绍了冬夏两季的电解氯气和氢气除湿过程的工艺改进和节能情况,分析了冬季用循环水代替5℃水冷却电解氯气和氢气的可行性。     

氯乙烯精馏尾气中氢气分离提纯系统运行总结

简要介绍了氯乙烯精馏尾气中氢气吸附分离的原理,详细介绍了氢气分离提纯装置的工艺流程及其在实际操作中的注意事项。     

天然气催化燃烧在燃气轮机和锅炉中的应用

综述了天然气催化燃烧技术在燃气轮机和热水锅炉中的应用和研究现状及其发展方向,介绍了几种不同形式的催化燃烧器和一些典型的设计实例,指出催化燃烧技术仍存在的问题。     

Analysis of gas absorption accompanied by a zero-order chemical reaction in a liquid-foam film surrounded by limited gas pockets

Gas absorption accompanied by a zero-order chemical reaction in a finite liquid-foam film has been analysed to obtain expressions for the amount of gas absorbed and for fractional absorption in such a film. These equations may be readily incorporated into a single-stage model of a foam-bed reactor to extend it to chemisorption with zero-order kinetics. The equations for physical absorption result naturally from a special case.