变压吸附技术的应用研究进展1

变压吸附(PSA)技术是近几十年来在工业上新崛起的气体分离技术,是物理化学渗流理论在工业上的具体应用。自上世纪70年代以来,变压吸附技术因其优势明显,在化工分离中占有重要地位,受到关注和发展。文章简要综述了变压吸附技术的发展里程、理论基础及其研究进展、分离过程的计算机模拟和在国内外工业领域中的应用情况,并对其应用前景进行了展望。     

Effect of Operation Symmetry on Pressure Swing Adsorption Process

In a multi-bed pressure swing adsorption (PSA) process, cycle steps with gas flow transferring from one bed to another such as equalization, purge, etc. are generally practiced to enhance the product recovery. However, if the flows for the connected beds in these steps are not balanced, the PSA process may not operate in a symmetrical manner. In the modeling of the PSA process, most of the simulations consider only one bed and assume that the rest of the beds would behave in a same way. In order to assess the impact of bed symmetry on the PSA performance, a new PSA model capable of studying bed symmetry in a two-bed system is developed. Experimental results from this paper show that uneven equalization flow can result in a lower product purity and a peculiar purity curve at different equalization levels. This phenomenon can be successfully predicted by this model. Simulation results also show that in large-scale PSA units, asymmetrical operation can cause drastically different temperature profiles in different adsorbers and hence a much lower performance. This paper demonstrates the importance of maintaining operation symmetry in PSA processes.     

摇摆状态下捷联惯导系统初始对准技术的研究

研究了摇摆状态下捷联惯导系统的初始对准技术,提出了一种新的对准方案:将初始对准作为一种工作状态嵌入到导航解算中,利用姿态解算构建的“数学平台”来隔离基座的摇摆运动,同时采用二阶调平、方位误差估算方法完成初始对准。通过计算机仿真和三轴转台摇摆实验证明该方案可以有效实现摇摆状态下的对准。     

Exercising flexible load contracts: Two simple strategies

A flexible load contract is a type of swing option where the holder has the right to receive a given quantity of electricity within a specified period, at a fixed maximum effect (delivery rate). The contract is flexible, in the sense that delivery (the take hours) is called one day in advance. We investigate two simple strategies for exercising flexible load contracts, where both use price information from the forward market. For 10 contracts traded in the period 1997–2001, we calculate the performance of the two strategies and compare with the reported performance of one complex dynamic programming approach as well as the actual results obtained by three anonymous market participants. The comparison indicates that our simple computer‐efficient strategies perform better on average and produce more stable results. Copyright © 2007 John Wiley & Sons, Ltd.     

Adsorptive separation in the enhancement of butene dehydrogenation

Fixed-bed columns containing solid catalysts and adsorbents were employed for simultaneous reaction and separation. The models developed for butene dehydrogenation reaction were validated with experimental data. The model was then employed for variable bed configurations with and without the effect of pressure and vacuum swing reaction (PSR and VSR). The models for the mass and momentum transfer in the catalyst bed and adsorber were solved using orthogonal collocation within the method of lines. The reactor/separator performances were tested for beds with varying numbers of layers of catalysts and adsorbents arranged sequentially. The reaction columns behaved as reactor/separators in series. As the number of layers increased, a homogeneous distribution of the catalyst and adsorbent was approached in the limit. These configurations with variable catalyst/adsorbent distributions were investigated in terms of product purity, selectivity, conversion, recovery and yield. Improved reactor performance was observed with pressure and vacuum swing separation systems and in particular with close to well-mixed reactor/separator configurations.     

Graphical approach for complex PSA cycle scheduling

A simple graphical approach for complex pressure swing adsorption (PSA) cycle scheduling has been developed. This new methodology involves a priori specifying the cycle steps, their sequence, and the number of beds, and then following a systematic procedure that requires filling in a 2-D grid based on a few simple rules, some heuristics and some experience. The outcome or solution is a grid comprised of columns that represent the total cycle time, rows that represent the total number of beds, and cells that represent the duration of each cycle step, i.e., the complete cycle schedule. This new approach has been tested successfully against several cycle schedules taken from the literature, including a two-bed four-step Skarstrom cycle, a four-bed nine-step process with two equalization steps, a nine-bed eleven-step process with three pressure equalization steps, and a six-bed thirteen-step process with four pressure equalization steps and four idle steps. This approach also revealed the existence of numerous cycle schedules for each bed and cycle step combination examined. Although it cannot identify the total number of permutations or which one is better, it does provide a very straightforward way to determine some of the possible cycle schedules of virtually any PSA process that can be conceived.     

摆动刻蚀法制作高衍射效率凸面闪耀光栅

通过摆动离子束刻蚀方法,制作了用于短波红外高光谱成像光谱仪的凸面闪耀光栅。该方法通过在光栅子午方向上进行摆动刻蚀,解决了凸面光栅子午方向的闪耀角一致性问题。建立了摆动刻蚀模型来分析摆动速度、束缝宽度等工艺参数对槽型演化的影响,并计算了优化的刻蚀工艺参数。制备了基底尺寸为67 mm,曲率半径为156.88 mm,刻线密度为45.5 gr/mm,闪耀角为2.2°的凸面闪耀光栅,并对其表面形貌及衍射效率进行了测量。实验结果表明,摆动刻蚀法能够制作出闪耀角一致性好、衍射效率高的小闪耀角凸面光栅,满足成像光谱仪对光谱分辨率和便携性的使用要求。     

腔QED技术实现最优非对称经济型1到3的相位协变克隆方案

本文提出一个在腔QED中实现最优非对称经济型1到3相位协变克隆的可行性方案,这种克隆不需要辅助粒子.在这个方案中,三个原子中的两个同时与腔场发生作用,并且受经典场的作用.此方案不受腔场的态和腔衰变的影响,因此,在实验上是可能实现的.     

Direct Phosphorylation of Benzothiazoles and 4-Methyltthiazole

Simple procedures for preparation of 2-(4-methylthiazolyl) dichlorophosphine and wide variety of 2-phosphorylated benzothiazoles are reported. Efficient promoters and catalysts were found for the key transformation, direct phosphorylation of the heterocyclic compounds by PCl₃ (PB_r3 as a promoter) or by P(V) acid chlorides (HgCl₂ as a catalyst).     

Kinetic Separation of Oxygen and Argon Using Molecular Sieve Carbon

A pressure-swing adsorption (PSA) simulation study was performed for the separation of a mixture of 95% O₂ and 5% Ar using a molecular sieve carbon (MSC) as the adsorbent. Two PSA cycles have been outlined to maximize the recovery of either argon or oxygen as a high purity product. The effect of cycle parameters such as cocurrent depressurization pressure, purge/feed ratio, pressure ratio and adsorption pressure on the separation of O₂/Ar has been studied. It was found that it is feasible to obtain an argon product of purity in excess of 80% with reasonably high recovery using one of the cycles. The other cycle is capable of producing high purity oxygen (>99%) at high recovery (>50%) with reasonably high product throughputs. The PSA process can be conducted at room temperature and hence has an advantage over conventional processes like cryogenic distillation and cryogenic adsorption.