Gas Separation & Purification最新文献

Extending the adsorption simulation model ADLIN® to chemical reactions with catalysts we have designed a favourable modification to the Linde Clinsulf® process which converts H₂S and COS to sulfur. Using a detailed precooling treatment before switching the hot and cold reactors we were able to reduce the typical lack in conversion to merely 0.5% which guarantees an overall sulfur recovery above 99.7% during the entire cycle time. The model calculations reveal the complex interaction of chemical reaction, adsorption, condensation and heat transfer for designing actual plants.

Liquid desiccant-based dehumidification systems have been widely used to remove water vapour from air in a packed column using different liquid desiccants. The liquid desiccants are usually grouped into two categories: aqueous solutions of inorganic salts and aqueous solutions of organic compounds. In order to design such a desiccant—dehumidification system, correlations of the column performance parameters are necessary. A correlation of column efficiency for different packings and desiccant solutions was developed in this study using lithium chloride (LiCl) as the inorganic salt and triethylene glycol (TEG) as the organic compound. This correlation involves the air and liquid flow rates, air and liquid inlet temperatures, column and packing dimensions, and the equilibrium properties of the desiccant solutions. The correlation was tested for polypropylene Flexi rings, ceramic Berl saddles, glass Raschig rings and polypropylene Pall rings. The average value of the errors between predicted values and experimental data was about 7%.

Binary desorption and displacement kinetics of ethane and propane in Ajax activated carbon are studied in this paper to further understand the multicomponent adsorption of light hydrocarbons onto activated carbon. The experimental data are collected using a differential adsorption bed over a range of temperatures, bulk concentration combinations, particle sizes and shapes. A macropore, surface and micropore diffusion (MSMD) model recently proposed by Hu and Do (Chem Eng Sci (1993) 48 1317) is used in the analysis of experimental data. This model takes into account the concentration dependency of the surface diffusivity. Both diffusions of free and adsorbed species are allowed for in the theory. The adsorbed species are assumed to diffuse in the particle as well as in the microparticle (grain) coordinates. An imaginary gas-phase concentration concept is used to calculate the local diffusion flux of the adsorbed species inside the microparticle. The local multicomponent adsorption equilibrium at any point within the particle is calculated using the ideal adsorbed solution theory (IAST), with the single-component adsorption equilibrium data described by a Unilan equation.

The reaction in aqueous solution between carbonyl sulfide (COS) and the polyamines ethylenediamine and diethylenetriamine has been studied experimentally using a conductimetric stopped-flow technique. The experimental results indicate that this reaction follows a zwitterion intermediate mechanism leading to: $\text{k}{}_{\mathrm{obs}}\text{=}\text{[Am]}\text{1}\text{k}{}_2\text{+}\text{1}\text{k}{}_{\mathrm{Am}}\text{[Am] +}\text{k}{}_{\mathrm{w}}\text{[H}{}_2\text{O]}$ Values of the rate constants k₂, k_Am and k_w at 298 K are reported for both ethylenediamine and diethylenetriamine. Activation energies for k₂, k_Am and k_w are also reported for diethylenetriamine.

A practical view of the equilibrium partial pressure of CO₂ over aqueous alkanolamine is presented here to facilitate process design. The entire equilibrium is divided into two parts, namely first equilibrium and final equilibrium. The non-ideality of the amine solutions used in industrial practice could be accounted for by using final equilibrium data available or generated. The same factor can be used to predict the equilibrium partial pressure of CO₂ for a real situation using the ‘first equilibrium concept’. The expressions developed are very simple and can be handled easily on a programmable calculator. The method is illustrated with the help of published data.

Ternary adsorption kinetic experiments of ethane (light species), propane (intermediate species) and n-butane in activated carbon are collected under various concentration combinations, temperatures and particle sizes. The effects of these parameters on the ternary adsorption dynamics are investigated. All the experimental data are compared with the predictions by a multicomponent heterogeneous macropore, surface and micropore diffusion (HMSMD) model recently proposed by Hu and Do (AIChE J (1993) 39 1628) using only single-component equilibrium and mass transfer parameters. The model can accurately predict the adsorption rates of ethane, propane and n-butane, but a small error in the calculation of the adsorbed amount of propane at ternary equilibrium is observed.

Experimental adsorption isotherms of binary, ternary and quaternary mixtures of ethylene, propane, propylene and CO₂ on 13X zeolite have been obtained at 293 K. Experimental data of mixtures were fitted to three theoretical models, the ideal adsorbed solution (IAS), real adsorbed solution (RAS) and spreading pressure dependence (SPD) models to reproduce and predict equilibrium data. With the SPD model, two other temperatures were also studied, 279 and 308 K, in order to calculate the model parameters. The best models for binary and multicomponent mixtures showing the highest deviation from ideality were RAS and SPD, with RAS better than SPD for ternary mixtures.