The development of the industrial systems for the year 2050 has been well defined in the recent Research Agenda with many strategic sectors, such as water, energy, food, health, etc. The drive towards greater sustainability has prompted process industries to search for opportunities to decrease their production costs, energy consumption, equipment size, and environment impact as well as improve the raw material yields, remote control, and process flexibility. Distillation process as a dominant player among all separation technologies are typically energy and cost intensive. One of the major challenges in distillation process industry is thus to improve the energy efficiency of existing and/or new processes through economic and ecological strategies. Integration, intensification and hybrid approach of distillation have become the main trend to achieve green and sustainable chemical process. Process integration and intensification is defined as a set of innovative principles applied to the design of processes and equipment to satisfy those concerns about energy and ecology impact of the process. The energy efficiency of a distillation process could be maximum by optimizing the design and operational parameters. However, as distillation processes become more complex in structure and operation through integration, intensification and hybrid, to find their optimal design and operation conditions drawing out its full potential is also becoming more challenging. This presentation will review briefly applications and trend of integration, intensification, and hybrid of distillation processes with their optimization. The potential and reliability of these technologies are addressed briefly, which will enable distillation process to achieve higher efficiency and high capacity. The recent developments in current research are summarized to highlight the importance as well as the effects, challenges, and future prospects of distillation process integration, intensification, and hybridization.
Orthogonal model of interphase mass transfer in a packed column distillation process
Kunio Kataoka, Goro Nishimura, Hideo Noda and Hiroshi Yamaji
Kansai Chemical Engineering Co., Ltd
2-9-7 Minami-nanamatsu-cho, Amagasaki, Hyogo 660-0053., Japan
Mass transfer model was investigated for a distillation column which consisted of three packed beds of wire-mesh structured packing stacked in series. Thirteen thermocouples for local liquid temperature observation were embedded at an equal interval on the centerline of the packed beds. The distillation experiment was conducted with a binary solution of methanol and ethanol under total-reflux conditions. The F-factor was varied as the control parameter by changing the heat duty of the reboiler. The shell balance model was based on a cylindrical control volume having a local HETP as the shell height. The process simulation analysis was done by using a simulator package in the same condition as the experiment. Local variation of HETP, HTU, and volumetric overall mass transfer coefficient were analyzed by comparing the experimental data with the process simulation results,
In order to analyze interphase mass transfer based on the two-film theory, an orthogonal relation between the tie-line and the vapor-liquid equilibrium curve was assumed, so that the vapor and liquid compositions can be evaluated at the vapor-liquid contacting interface. This orthogonal assumption definitely determined vapor-phase and liquid-phase volumetric film coefficients of mass transfer. By means of dimensional analysis, the vapor-phase and liquid-phase mass transfer coefficients defined in the form of j-factor data were well correlated with the corresponding Reynolds number.
In the middle bed where the accuracy of local HETP observation is the best, a set of correlation functions were obtained by least square.
By virtue of the orthogonal assumption. the Reynolds number dependency of the mass transfer model in the form of j-factor was improved, especially in the liquid-phase j-factor correlation.
These days, many chemical engineers pay much attention to apply heat pump system for improving the energy efficiency of industrial separation processes. In distillation process, heat pump system can save energy significantly by upgrading the low-temperature waste heat to high temperature and utilizing it instead of steam for supplying heat to the reboiler. In this study, a blower based heat pump system was proposed to improve the energy efficiency of separation and purification processes in chemical industry. This paper showed the advantages and disadvantages of a blower based heat pump system and figured out when it can be applied. Blower based heat pump system is mainly used when there is only a small temperature difference between the hot and cold streams, where small pressure ratio and consequently smaller blower duty are needed. Several important industrial cases have been investigated to demonstrate the proposed configuration. By applying blower based heat pump systems, the latent heat can be circulated during the process, leading to a substantial improvement in energy efficiency. Notably, the operating costs can be reduced by up to 78%, 64% and 82% for the C3 splitter, C4 splitter and refrigerant separation processes, respectively.
Acknowledgement
This project is supported by the R&D Center for Reduction of Non-CO2 Greenhouse Gases (201700240008) funded by the Ministry of Environment as a ‘Global Top Environment R&D Program' and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2018R1A2B6001566) and by Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2014R1A6A1031189).
In order to improve the economics of the ETBE production, binary and ternary VLE data for ETBE(1)+Ethanol(2)+TBA(3) system are measured and correlated using NRTL-RK model. According to the obtained thermodynamic model, pressure dependence of the azeotropic point between ETBE(1)+Ethanol(2) system is evaluated using the Residue Curve Map. The separation feasible flow sheets are derived from the Residue curve maps and modeled using Aspen Plus. The process economics and performance are evaluated with those of the existing Uhde Process.
