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Distillation Columns 50 % Energy Saving for Refineries: First Use of Distillation Technology in Japan

| Editor: Dominik Stephan

A new, especially efficient distillation system helps to cut the energy bill of a Japanese methyl ethyl ketone (MEK) production in half. The new two stage distillation column marks the world’s first practical use of a revolutionary concept that as long haunted researchers. We took a closer look at the technology behind the energy wonder.

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Energy saving: If the energy consumption of an ordinary distillation column for a reboiler equals 100, the energy consumption of Superhidic is 40 for the compressor (converted to primary energy) and 10 for the reboiler, totaling approx. 50.
Energy saving: If the energy consumption of an ordinary distillation column for a reboiler equals 100, the energy consumption of Superhidic is 40 for the compressor (converted to primary energy) and 10 for the reboiler, totaling approx. 50.
(Picture: Toyo Engineering)

Distillation columns are typical standard assets of refineries and petrochemical plants, where they are used to separate mixtures of oils and petrochemicals. Although the technology is a widely used unit operation in all branches of chemical engineering, the columns are real energy guzzlers. Typically, the bottom of distillation towers is heated by a reboiler while at the same time, overhead gas is cooled using a condenser.

The duals energy demand for both heating and cooling at the same unit has long been a thorn in the side of process engineers and chemical researchers alike. Already in the 1970s, the concept of Heat Integrated Distillation Column (HIDiC) was announced as a process promising ultimate energy-saving performance. In this concept, overheat head is fed back into the reboiler, cutting some of its energy demand. For decades, HIDiC has been studied worldwide; however, practical application of the process has not yet taken place.

Breakthrough after a Decade of Research?

Now Japanese engineering technology specialists Toyo claim to have achieved a breakthrough development: Advancing the concept of HIDiC and applying proven distillation and heat-transfer technologies, the company has developed SuperHIDiC, a distillation system that promises high economic efficiency while retaining the maintainability of normal distillation columns.

SuperHIDiC enables 40 %-60 % energy savings in many cases within the distillation process by providing optimal internal heat exchange. With this technology, Toyo could reduce energy usage in oil refineries and petrochemical plants by retrofitting existing separation trains, the company believes.

From Research to Industrial Use

The concept behind the energy wonder is seemingly simple: The distillation column is separated into a two separate sections, one for stripping and one for rectifying, between which a compressor is set up. The temperature of the rectifying section is increased while its pressure is increased slightly, and heat is transferred from here to the stripping section to significantly reduce the additional thermal energy for the reboiler.

In the 1990s, industrial trials with the HIDiC concept used concentrically arranged rectifying and stripping sections. Yet this setup faced sime serious setback, including difficulty in carrying out maintenance and a lack of flexibility in terms of the heat-exchanger locations.

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