Multi-stage adsorption configurations with equality and Inequality constraints are optimized and comparisons are made between their relative effectiveness. For a given number of stages countercurrent flow is always superior, as expected. Although crossflow is generally second best, it becomes inferior to certain alternative networks for certain ranges of the magnitude of the adsorption isotherm exponent. Generally, the order of the effectiveness of various networks is believed to be according to how much the networks resemble countercurrent flow. An algorithm is derived and used to solve the N-stage crossflow network. All other configurations had to be treated as problems in constrained optimization. For this purpose, a theorem of Courant and a method of Carroll for equality and inequality constraints respectively are used to formulate the problem. Three different optimization methods were considered with the deflected gradient method of Fletcher and Powell proving to be the superior for this particular class of optimization problems. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

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Thesis (Masters Diploma (Mechanical engineering)--Cape Technikon, Cape Town, 1993 / The main objective of the work outlined in tills project is to create an awareness of Pressure Swing Adsorption (PSA) Processes, their application to oxygen production systems in the RSA and the construction and testing of a pilot plant, built to assess an overseas design. Available oxygen PSA technology was examined from a theoretical approach, right through to practical applications. The aim was not to re-invent the technology, but to review what technology is available and to assess its suitability for the South African Industrial Sectors. This was undertaken by investigating all PSA processes that are available to market the product to industry. The technology review includes an investigation of overseas PSA technologies and compares these modes of technology with the technology that is readily available to Afrox Limited, a major gas supplier in South Africa. This resulted in the technology from the British Oxygen Company being thoroughly reviewed, examined and compared to various other modes of technology. The basic principals of adsorption are discussed to give the reader an understanding of the factors that influence efficient adsorption and adsorbent regeneration. The parameters that defme when adsorption separation processes are applicable to the separation of atmospheric gases are also discussed. The different types of PSA plant layout are discussed in great detail and it is explained when each plant layout type would be used.

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A three dimensional integral equation is developed in order to compute water adsorption onto aggregates of spherical aerosol nano particles. The integral equation is derived from molecular density functional theory, with a weighted density approximation and a direct correlation function interpolation rule. Only required inputs are the direct correlation functions of the uniform fluid or gas at both high-density and low-density limits. The equation has been tested on argon adsorption onto a graphite planer substrate; the result corresponds well with previous simulation work. Adsorption of both noble gas and water onto a single spherical nano particle and aggregates of spherical nano particles has been computed with the developed equation. For the adsorption of a single spherical substrate, layer structure has been found, the adsorption shows a transition property when substrate size increases and when the substrate size is over 100?? the adsorption is nearly the same as that of a planer substrate. For adsorption of aggregates of spherical nano particles, not only much strong adsorption appears but also adsorption property changes with different configurations of spherical nano particles.

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