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News No. 10, 2003

Application Portrait

4-stage Vacuum Distillation Plant for Novartis, Schweizerhalle / Switzerland

by Dr. Hartwig Althaus, Chemist at Novartis Services AG

Our 4-stage, totally automated vacuum distillation plant (SPD plant, see Fig. 1) was purchased from UIC as a turnkey plant some 3 years ago. Since that time the plant is very successfully used for the distillation of light protection agents for the varnish industry. The light protection agents types Tinuvin 384, Tinuvin 400, and CGL 1545 are produced by the Swiss company CSC (Ciba Spezialitätenchemie AG) in its facilities in Schweizerhalle, and are distilled by Novartis Services for CSC as a toll distillation job. Presently three different products are being distilled on this plant. Some five changes of product are being done each year, and in case of each product change the plant is completely cleaned with Xylol and subsequently dried. As solvents, the fire point of which is below the operation temperature of the Short Path Distillation unit, are distilled in a plant very close to the SPD plant, the SPD plant was completed housed in order to guarantee that it is absolutely explosion proof. Except for the cold traps, we have refrained from any sight glasses. In order not to negatively influence the product properties, the complete plant does not have any sealing or oil containing silicon. As all the products are very viscous respectively might crystallize, all pipes and containers are trace-heated.

In the first stage of the plant light volatiles are stripped off. This is made in a Falling Film Evaporator at a pressure of 10 mbar. Our Falling Film Evaporator having an evaporation surface of 5 m2 is being operated in a "single pass" mode without recirculation. The numerous test distillations, which we had made at UIC before ordering the plant, had revealed that this version is technologically comparable, but more economical compared to a Thin Film Evaporator with roller wiper system. The amount of investment was lower and there is almost no wear. The second stage is a degasser column. In this stage any traces of residues of light volatiles are reliably and completely separated at a pressure which is 10 times lower than the pressure in the Falling Film Evaporator. The third stage consisting of a Short Path Distillator (KD 150) is used to slightly cut into the product. The distillate thereof, which still contains components of the starting materials of the synthesis, is disposed. The residue is again distilled in the second Short Path Distillator (KD 150, forth stage). In a static mixer the distillate of the forth stage is continuously diluted with solvent in a certain percentage, so that the result is our product for sale. The viscous residue of the forth distillation step is mixed with the distillate of the first SPD unit and disposed. Depending on the feed material, the evaporation

Fig. 1: Partial View of the Novartis Distillation Plant

UIC GmbH, Am Neuen Berg 4 · D 63755 Alzenau-Hörstein · Tel.: ++49-(0)6023/950-0 · Fax: ++49-(0)6023/950-250 e-mail: [email protected] ·


News No. 10, 2003

temperature of the second Short Path Distillation unit is adjustable up to 350 °C. The vacuum is generated by means of a central vacuum system consisting of one liquid ring pump as pre-vacuum pump, four identical roots pumps and one oil diffusion pump evacuating the second Short Path Distillator. Lateral inlets connect the individual distillation stages. Thus the number of the required aggregates is reduced to a minimum and the reliability respectively the availability of the complete plant is increased. This concept is especially interesting from the financial point of view. Due to the fact that the vacuum pumps are built in line, any vacuum problem at one of the first stages (Falling Film Evaporator, Degasser) would also affect the vacuum of both Short Path Distillation stages. In order to exclude such problems during distillation process, a leak check is made after each cleaning of the plant. The heating of the Falling Film Evaporator as well as of both Short Path Distillators is made by means of thermal oil. The primary and all secondary heating circuits have been installed in the basement of the building due to ex-proof reasons. The plant is PLC-controlled and operated via a PC which is located in a separate control room. The visualization is made through FIX software by Intellution which enables a very intuitive operation the plant. All process parameters are saved for the last 100 days

Partial View of the Novartis Distillation Plant

on the hard disc of the PC. Via an integrated CD-writer the parameters are saved for each quarter of a calendar year, so that ­ as required according to our quality assurance system ­ a continuous documentation is guaranteed for years. All parameters of the plant can be displayed as trend charts. This is very helpful for optimization and trouble-shooting in case of any problem. An especially useful tool is the so-called "hold mode", in which a number of important process parameters are continuously controlled. Deviations which exceed the tolerance ranges cause an alarm so that the personnel does not need to supervise the plant permanently. According to our request, UIC has also integrated the control of the feed and discharge tanks (2 x 10 m3 for raw material and distillate, 2 x 1 m3 for waste and thinning agent). In order to increase profitability,

the residue of the first SPDunit and the distillate and residue of the second SPD-unit are recycled to the raw material tank when starting and switching off the plant. Only after the plant is running at optimal conditions and the product has reached the required quality, the plant is turned to "production mode". The distillate of the first SPDunit and the residues of the second SPD-unit are then led into the waste container together with the condensate of the Falling Film Evaporator, and all this material is fed to an incinerator. In the very beginning the plant was engineered for the distillation of the products Tinuvin 400 and CGL 1545 which have higher boiling points, and the plant meets our expectations to 100 %. After minor adjustments the plant can now also be used for the distillation of Tinuvin 384. Due to the lower boiling point of Tinuvin 384,

we can reach throughputs which are by approx. 30 % higher than specified for the plant. The cooperation with UIC was an excellent one during the entire realization period of the plant. In particular the professional support during the commissioning phase of the plant, which was rather difficult due to very tense time reasons, was a major aspect for the success of the whole project. Even today UIC supports us from time to time in order to perform adjustments of the plant to new requirements or in case of optimizations, and it is always a pleasure to work with the UIC staff. After a number of trial distillations at UIC GmbH, we next intend the application of the new wiper rollers of UIC for our KD 150.

UIC GmbH, Am Neuen Berg 4 · D 63755 Alzenau-Hörstein · Tel.: ++49-(0)6023/950-0 · Fax: ++49-(0)6023/950-250 e-mail: [email protected] ·




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