A two-stage optimal design procedure is suggested for alkane pyrolysis processes and is applied to propane pyrolysis. The first stage considers only hydrocarbon decomposition, the primary reaction in the process. A mathematical model consisting of an overall stoichiometric, an empirical rate, and a heat-balance and hydrodynamic equation is constructed. This model is analyzed for a varied tube diameter and a fixed propane conversion to optimize the design parameters of the propane pyrolysis reactor. At the second stage, the main reaction is considered together with secondary and tertiary reactions and a complete model taking into account recycling of the unreacted raw material is constructed. The optimum inlet temperature and recycle ratio are determined as a function of the total feed rate. An economic optimality criterion is suggested, and final process optimization is carried out.
This study is a fragment of the information chronicle of the evolution of the Aral Sea, captured on the sites of ancient shores and paleorusels, in the discovered archaeological artifacts and traces of ancient structures (settlements) on the exposed bottom of the Kazakh part of the Southern (Big) water area The Aral Sea. It is shown that fluctuations in the water cycle, including migration (meandering) Both the Amudarya and the Syrdarya rivers were an important prerequisite for the emergence of a unique settlement culture in the oasis areas of the arid zone. The analysis of paleorousels reveals that the duration of regressive periods in the evolution of the Aral Sea lasted longer than transgressive processes. Throughout the transgressive-regressive processes, the Syrdarya River had a more or less stable flow with significant migration (change) of the channel, but always with a directional flow into the Aral Sea, while the Amudarya radically changed its course. The studied materials are the most valuable source for a wide range of researchers, as well as the key tounderstanding the large-scale processes of the evolution of the Aral Sea.
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