From an Idea to a Production Plant

1 To realize an idea from paper, it has to be clarified whether it is techni- cally feasible and economically worthwhile. Sulzer Chemtech gives customers every assistance thereby, e.g. with test runs in pilot plants.

It makes no difference whether plastic drinking cups are made of ERICH HUGI polystyrene or chewing gum masses from polyvinyl acetate – every STEFAN KISLIG plastic is associated with a complex process, which converts the SULZER CHEMTECH monomer into a polymer with characteristics that are suitable for the intended application. In the field of Static Mixing and Reaction Technology, Sulzer Chemtech has a profound knowledge of the processes and technical apparatus employed in polymer production.

There is an idea at the start progress in the field of numerical which permits the efficient piloting of every process (Fig. 1). process simulation, the close rela- of processes and process stages at The chances that it will be accept- tionship of process kinetics and customer’s order (see also box). ed in the practice are good, if the fluid dynamics still poses immense Every pilot plant is designed for costs are less than those of the difficulties in polymer production. the individual questions formulat- already established processes. One In the end, the risk is too great to ed by the customer. Thanks to the important step on the way from the convert a process idea on paper modular design of the pilot plants, idea to the production plant is the directly into a production plant. they can be modified flexibly and demonstration of the new process Sulzer Chemtech has the infra- quickly during the piloting phase. in pilot scale. Despite the great structure of a technical laboratory, If necessary, parts of apparatus

4000 SULZER TECHNICAL REVIEW 1/2001 9 initiator), the mixing as a unit operation plays an important role for polymerization reactions. Fur- thermore, these reactions are ex- tremely exothermic in the majori- ty of cases and can only be mas- tered safely if the resultant heat is extracted with only slight differences in temperature. The progressive polymerization of the monomer to polymer causes a marked increase in the viscosity, necessary properties for the fur- namely from the watery viscosity ther processing. Static mixing sys- 0699 2709-1 of the monomer to a viscous poly- tems from Sulzer Chemtech are 2 The process requirements of customers can be mer melt, like a molasses spread. characterized by their low con- tested on a small scale in the Sulzer Chemtech pilot In the case of higher viscosities, sumption of energy and minimum plant for polystyrene in Winterthur. where the heat transfer to the maintenance. Thanks to their com- reactor walls is effected exclusive- pact design, they are also especial- ly by laminar flow, there is a great ly suitable where space is limited, that are not readily available can demand for mixing and reaction a difficulty which is frequently the be manufactured immediately in systems from Sulzer Chemtech. case with retrofits. the company’s own workshop. Quite frequently, the product of a After all, the object of this work is polymerization is not a pure poly- PLANT FOR THE PRODUCTION to establish a reliable data basis mer, but a mixture with residual OF POLYSTYRENE for the construction of an opti- monomer, solvent and diverse pol- The production of polystyrene is a mized, process-engineering pro- lutants. These constituents are well-known example of the reac- duction plant. removed by means of the static tions of polymerization. Sulzer devolatilization process developed Chemtech has the know-how to STATIC MIXING AND REACTION by Sulzer Chemtech and the puri- design, build and commission com- TECHNOLOGY ty of the polymer thus increased to plete production plants. And for Since the reactor performance is 99.99%. This technology is also customers who wish to build a new dependent on the respective con- very suitable for the devolatiliza- plant, for example, there is a pilot stituents (monomer, catalyst, and tion of thermal-sensitive polymers plant in Winterthur with which it and, in comparison with conven- is possible to clarify how cost-effec- tional processes, requires less tive production and with high energy. The polymer resulting quality can be realized with the after the devolatilization has to be process from Sulzer Chemtech frequently upgraded with diverse (Fig. 2). The polymerization of additives in order to obtain the styrene is not conducted until the monomer is spent completely, which would be unprofitable. With the polymerization technology from Sulzer Chemtech, however, it is possible to polymerize 80–85%

0601 2701-1 as against the 60–75% with con- ventional processes. The advan- 3 The polystyrene product EPS tage here, for example, is that less (expandable polystyrene) is employed monomer has to be separated off as a source material for objects such and so a smaller devolatilization as packing boxes. Sulzer Chemtech unit can be planned and operated has developed a continuous with less energy, which, in turn, process for the production of these enhances the rentability of the 0601 2700-1 microgranulates. complete plant.

10 SULZER TECHNICAL REVIEW 1/2001 ECOLOGICAL MANUFACTURE OF POLYSTYRENE BEADS nomically. For example, there is no A further process developed by further need for the abundant Sulzer Chemtech is designed for quantities of water that are the manufacture of expandable required and have to be cleaned for polystyrene microgranulates EPS batch processes. (Fig. 3). This contains a foaming agent, e.g. Pentan, which is used to AT SULZER CHEMTECH expand the microgranulates in the OR BY THE CUSTOMER further course of processing. The Depending on the questions posed resultant components are em- and the boundary conditions, pilot ployed on a wide scale for thermal tests are also carried out in a pilot insulation purposes in the build- plant at the customer’s works or ing, transport and packing indus- directly in the actual plant. For tries. example, polymerization tests With the process from Sulzer were made on-site on an existing Chemtech, the foaming agent is polystyrene plant for a customer in added continuously to the poly- Great Britain. Among other things, styrene from the mass polymeriza- the customer wanted to increase 0696 2701-4 tion. And simultaneously with the the production output of the plant successful demonstration of the from 2850 kg/h to 4000 kg/h. A com- 4 After successful on-site pilot tests on an existing impregnation of the polystyrene plete polymerization system was polystyrene plant, Sulzer Chemtech designed and melt and microgranulation in pilot erected and supplied with a part supplied the additional reactor volume with which scale, it can be shown that the EPS flow from the full-scale plant. In the capacity increase required by the customer could granulates manufactured in this this way, it was possible to demon- be realized. manner can be processed further strate the operating conditions to in industrially operated pre- and the customer under which the sta- With these tests, it was also possi- form-foaming apparatus. In com- tic polymerization reactors would ble to determine the data neces- parison with conventional equip- have to be operated in order to sary for the scale-up of the reac- ment, this process is not only much obtain his required product char- tors. After a successful demonstra- better ecologically, but also eco- acteristics. tion, the additional reactor volume was integrated in the plant during a production stop in 1995 (Fig. 4); since then, the plant has been oper- KNOW-HOW FOR POLYMER PRODUCTION ating productively to the complete satisfaction of the customer. Ω Sulzer Chemtech provides problem solutions for the production of the most diverse polymers. All these processes operate over three stages:

Polymerization Degasification Upgrading FOR MORE DETAILS Polystyrene (GPPS, HIPS) Polystyrene (GPPS, HIPS) Admixture of: Sulzer Chemtech AG Styrene-Copolymers (ABS/SAN) Styrene-Copolymers (ABS/SAN) – Low-viscosity Erich Hugi Polymethylacrylate Polyethylene (HDPE, LLDPE) additives Polyethylene (PE) Polyvinyl acetate (PVA) – High-viscosity Postfach 65 Silicone polymers Polycarbonate (PC) masterbatches CH-8404 Winterthur Polyamide 6 (PA6) Polyether glycol – Other polymers Switzerland Terpene resins Polyoxymethylene (POM) Telephone +41 (0)52-262 61 78 Polyoxymethylene (POM) Polyisobutylene (PIB) Elastomer (EPM, EODM) Fax +41 (0)52-262 00 76 E-mail [email protected]

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