Decentralized temperature control of a pilot dividing wall column

The technology of dividing wall columns offers to save high amounts of operating and investment cost compared to conventional distillation columns and their configurations. The practical application is still limited due to a lack of experience and high interactions among the process variables.The present work deals with the development and test of a control system for a pilot dividing wall column. Within this, decentralized temperature control systems are designed by a systematic approach. Furthermore, these systems are evaluated concerning the process stability, the providing of defined product purities and the respective requirement of energy in case of disturbances. The focus is on simulative and experimental investigations in order to assure the practicability of the developments. The presented results show the effectiveness of the applied methods.     

Designing four-product dividing wall columns for separation of a multicomponent aromatics mixture

Preliminary evaluations using a simple but reliable short-cut method indicated that a 15 component aromatics mixture can be separated very efficiently into four fractions according to the given product specifications employing either a single or a multiple partition wall dividing wall column (DWC). The obtained results have been used to initiate rigorous simulations, to determine the number of stages required in different sections, as well as to obtain internal flows of vapour and liquid necessary for dimensioning and adequate cost estimation for two design alternatives. Based on the comparison of total annualised costs it appears that a multi-partition wall configuration that maximizes energy efficiency is a more attractive option for implementation in aromatics processing plants than more practical single partition wall configuration.     

Experimental study on pressure drops in a dividing wall distillation column

Previous studies in the fields of process design and process control [1] have shown the potential benefits that can be achieved through the implementation of thermally coupled distillation sequences, in particular, the dividing wall distillation column. The dividing wall distillation column meets important goals of process intensification, including energy savings, reduction in carbon dioxide emissions and miniaturization. In this paper, an experimental study on the hydrodynamic behavior of a dividing wall distillation column is presented. Several different values for gas and liquid velocities were tested in order to measure pressure drops and identify operational regions; the air/water system was used as the basis for the experimental setup. Results regarding pressure drops (fitted to the model of Stichlmair et al.) provide operational limits for the operation of the packed dividing wall distillation column. According to the results, the experimental dividing wall column can be operated at turbulent regime that is associated to proper mass transfer.     

乙烯装置降低能耗的技术措施及实施效果评估

从实际出发介绍了吉化乙烯装置开车几年来特别是近一两年来，在降低装置能耗方面所采取的措施。     

Internal configurations for a multi-product dividing wall column

This paper addresses possibilities and peculiarities associated with establishing the most beneficial internal configuration of a complex dividing wall column (DWC), using as a base case the separation of a multicomponent aromatics mixture into four or five product streams. As expected, the V_min-diagram method proved to be an appropriate tool in such a study, as a means for identifying and assessing promising configurations and at the same time to provide the necessary inputs and reliable initial guesses for detailed simulation-based determination of energy and stage requirements. A new, energy efficient two-top product configuration is introduced that appears to be an interesting option for a four-product DWC.     

An Evaluation of Factors Influencing the Energy-Efficient Operation of Well-Mixed Fluidized Bed Dryers

This article describes the results of calculations of specific energy consumption, E_s, performed on a well-mixed fluidized bed dryer simulator. Exhaust air temperature-humidity loci required to yield a specified outlet moisture content were also determined. Most of the calculations related to solids whose drying rate was gas-film controlled. Six model drying curves were employed to examine the effects of drying rate and hygroscopicity in addition to the normal operating parameters. The results indicated that E_s was highest for slow-drying hygroscopic solids and lowest for fast-drying, non-hygroscopic solids. Specific energy consumption increased with decreasing bed temperature and outlet moisture content and with increasing heat loss but was independent of solids loading and airflow rate. For both the aforementioned solids and a much slower drying material (wheat), there was close agreement between the zero heat loss data and a single theoretical curve approximating the performance of an ideal adiabatic dryer. Distinct differences between the behavior of well-mixed and plug flow fluidized bed dryers are reported.