A New Stripping Column Process and Optimization of Its Operation

Abstract

In view of a kind of stripping column used widely in chemical industry, being in operation of total cold reflux and without top light product, a new stripping process is suggested in this paper. It takes dual feeds of the hot plus the cold by replacing partial cold reflux with a part of cold feed, resulting in significant reduction of energy consumption and simplification of the overhead vapor route. Due to no any change on the column's body and only a pipe needed, this new process can be promoted conveniently in retrofitted projects. Further an optimization study is developed for choosing proper flow rate of cold feed and column's running pressure. An application in a stripper of pre-hydrotreating resultant of oil catalytic reformer shows that the new process is valid. Keywords: Catalytic reformer; Energy consumption; Process optimization; Simulation; Stripper IntroductionDistillation is one of the most common operation units in chemistry industry, and also is an energy intensive process. It assumes about 40% of the total energy used in chemical and petroleum refining industries [1], and hence stimulating the development of energy-efficient separation technology greatly. On distillation column, there are four categories of main energy-saving measures: adjusting operation parameters, upgrading internals, creating new column structure and rearranging route of feed or/and draw-offs.Adjusting operation parameters, due to no need of changing structure and route of distillation column, is daily utilized in practical production, including decreasing column pressure, reducing reflux ratio, increasing feed temperature, changing feed-tray location, decreasing over vaporization rate, adjusting parameters of pump-around circuits and their heat duties distribution, and so on [2,21,25]. However restricted by various conditions, it is only available to benefit from a limited energy-saving.Column internals, such as tray, packing, liquid dispatcher, drawn canal of side products, have played a very important role in determining level of energy consumption of distillation column. Usually highefficient tray requires lower reflux ratio, namely less consumptions of hot and cold utilities; large flux packing means lower pressure drop, namely higher feed vaporization rate when the column pressure and feed temperature keep unchanged, naturally less heat requirement from the bottom reboiler

Model Predictive Control of a High‐Purity Internal Thermally Coupled Distillation Column

“…Hence, tremendous research progress has been made to ensure considerable energy is saved while improving the energy efficiency of the ASU. The internal thermally coupled air separation column (ITCASC) is a new version of the distillation column that integrates the internal heat of the rectifying section with that of the stripping section of the column 8, 9. In this way, the wastage of energy in the heat sink and the source in a traditional distillation column was eliminated 10.…”