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Research paper : Innovation in distillation processes (M. Nakaiwa et al.)−60−Synthesiology - English edition Vol.2 No.1 (2009) He called this system Secondary Reflux and Vaporization (SRV) distillation (see Fig. 7). However, only its theoretical possibility was noted in the paper. It was shown that the energy saving can be achieved for the low-temperature systems that have a small difference in BP, such as air separation; but its potential for practical application was not considered in the paper. Professor Mah himself seemed to think that its practical potential was low. In fact, he submitted no patent application for this idea, and therefore what might be called a ‘master patent’ for the HIDiC does not exist. Professor Mah was not an expert in separation via distillation. Rather, he studied on an optimization of process flow using graph theory. After the first oil crisis of the mid-1970s, it seemed that he started investigating on energy saving of the distillation process, the most energy-consumption process in chemical plants. At the time, it was a common practice to wrap the distillation column with insulation materials to try to minimize any heat transfer from/to the outside except for the top and bottom of the column. (This is still a common practice today.) Thus, it was completely beyond the common sense to deliberately allow heat to enter and exit from the column body. According to Professor Kazuyuki Shimizu of Kyushu Institute of Technology, who worked on the SRV under Professor Mah at the beginning of the 1980s, the response to their investigation presented at the meeting of the American Institute of Chemical Engineers (AIChE) was very cold, and it was labelled as “a research just for publishing a paper” and almost ignored. Thereafter, several proposals on the HIDiC like concept were made in the form of research papers and patents in the U.S.A., but all of them suggested ideas or concepts only, and no realization research has been carried out.6 Road to Practical Applications of HIDiCSeveral years after Professor Mah first published the paper mentioned above, the idea of HIDiC had attracted the attention of Professor Takeichiro Takamatsu of Kyoto University. He began to study on the fundamental characteristics of the process. Professor Takamatsu investigated on exergy analysis and thermodynamic analysis of chemical processes at the time, and he seemed to take notice of the high energy efficiency of HIDiC process. In the mid-1980s, the authors uncovered the characteristics of this process theoretically and experimentally at the National Chemical Laboratory for Industry through the collaborative research with Professor Takamatsu. First, we demonstrated theoretically that the column height and number of plates required as well as the heat transfer area, which allows us to prepare the overall column design, can be obtained by specifying the separation conditions and operation pressure. Also we showed that the operation pressure in the high-pressure side should be as low as possible for energy saving; but there is a thermodynamical limit of the value, which can be determined by providing the separation condition. Experimentally, it was proved using the small apparatus that the amount of heat required at the bottom of the column can be reduced via the internal heat-exchange. However, in this experimental apparatus, the size of compressor was larger than the column and its efficiency was low, we were unable to show the overall performance of energy savings considering the electrical power input.The “Super Heat Pump Energy Accumulation System” project was in progress at the Agency of Industrial Science and Technology in those times, and we anticipated that the HIDiC technology would be positioned as an energy-saving industrial process where the heat pump in the wide sense was used. In the 1990s, a few groups of university researchers in U.K., France, and Hungary started investigating experimentally, but no prospect for realization was obtained. In Japan, on the other hand, the “Broad Area Energy Utilization Network System Technology (Eco-Energy City)” project was carried out from 1993 to 2000 in the New Energy and Industrial Technology Development Organization (NEDO). The research and development of HIDiC was conducted within the project by AIST and three companies (Kimura Chemical Plants Co., Ltd.; Maruzen Petrochemical Co., Ltd.; and Kansai Chemical Engineering Co., Ltd.), based on the findings from the collaborative research with Professor Takamatsu and AIST. In December of 1999, a Mah R.S.H., et.al., AIChE Journal, Vol. 23(5), 651-658 (1977)CoolantDistillateFeedBottomsHIDiCVRC Petlyuk〇〇〇〇×Initial costOperation rangeApplicabilityEnergy efficiencyTable 1 Comparison between HIDiC and other energy-saving distillation technologies.Fig. 7 Concept of Secondary Reflux and Vaporization distillation.

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