Pilot plant | EPFL Graph Search

A pilot plant is a pre-commercial production system that employs new production technology and/or produces small volumes of new technology-based products, mainly for the purpose of learning about the new technology. The knowledge obtained is then used for design of full-scale production systems and commercial products, as well as for identification of further research objectives and support of investment decisions. Other (non-technical) purposes include gaining public support for new technologies and questioning government regulations. Pilot plant is a relative term in the sense that pilot plants are typically smaller than full-scale production plants, but are built in a range of sizes. Also, as pilot plants are intended for learning, they typically are more flexible, possibly at the expense of economy. Some pilot plants are built in laboratories using stock lab equipment, while others require substantial engineering efforts, cost millions of dollars, and are custom-assembled and fab

High-temperature radical polymerization of methyl methacrylate in a continuous pilot scale process

Philip Nising

The present PhD thesis deals with the high temperature polymerization of methyl methacrylate in a continuous pilot scale process. The major aim is to investigate the feasibility of a polymerization process for the production of PMMA molding compound at temperatures in the range from 140 °C to 170 °C. Increasing the process temperature has the advantage of decreasing molecular weight and viscosity of the reaction mixture, thus allowing to reduce the addition of chain transfer agent and to increase the polymer content in the reactor. At the same time, the reaction rates are higher and the devolatilization is facilitated compared to low conversion polymerizations. Altogether, it leads to an improved space time yield of the process. However, increasing the process temperature also has an important impact on both, polymerization kinetics and polymer properties. The first two parts of this work are, therefore, dedicated to the self-initiation respectively the high temperature gel effect observed for the polymerization of MMA at the given temperature range. The self-initiation of MMA is mostly caused by polymeric peroxides that form from physically dissolved oxygen and the monomer, itself. The formation, decomposition and constitution of these peroxides are intensively studied and a formal kinetic is proposed for the formation and decomposition reaction. The polymerization of MMA is subject to a rather strong auto-acceleration, called gel effect, the intensity of which depends on process conditions and solvent content. There are several models proposed in the specialized literature to describe this phenomenon by modifying the termination rate constant as a function of conversion and temperature. The second part of this study contains the evaluation of these models with regards to their applicability to high temperature MMA polymerization as well as the development of a new variant of an existing model, which correctly describes the gel effect in the temperature range of interest as a function of polymer content, temperature and molecular weight. The advantage of this new variant is that it includes all other factors influencing the gel effect, i.e. chain transfer agent, initiator load, comonomer and solvent content, and that it is suitable for the description of batch and continuous processes. A complete kinetic model for the description of the high temperature copolymerization of MMA and MA, containing the results from the first two parts of this work, is established within the software package PREDICI® and validated by means of several series of batch polymerizations. In the third part of this work, a complete pilot plant installation for the continuous polymerization of MMA is designed and constructed in order to study the impact of increasing the reaction temperature on process properties and product quality under conditions similar to those of an industrial-scale polymerization. The pilot plant is based on a combination of recycle loop and consecutive tube reactor, equipped with SULZER SMXL® / SMX® static mixing technology. Furthermore, it is equipped with a static one-step flash devolatilization and a pelletizer for polymer granulation. At the same time, a refined method for inline conversion monitoring by speed of sound measurement is developed and tested in the pilot plant. By means of this technique it is possible to follow the dynamic behavior of the reactor and to measure directly the monomer conversion without taking a sample. The results of several pilot plant polymerizations carried out under different conditions are presented and the impact of temperature, comonomer and chain transfer agent on the thermal stability of the product is analyzed. From these results, the r-parameters for the copolymerization of MMA and MA at 160 °C as well as the chain transfer constant for n-dodecanethiol at 140 °C are determined. Finally, the pilot plant experiments are used to validate the kinetic model established beforehand in PREDICI® for the continuous copolymerization.

EPFL2006

Continuous high-temperature polymerisation of methyl methacrylate

Thierry Meyer, Philip Nising

As the need for lower mol. wt. acrylates for specialty and molding applications increases, industry is looking for substitute prodn. processes. An alternative to the increasing of initiator and chain transfer agent concn. is working at higher temps. However, the high temp. polymn. of acrylates is a rather complex process with various new aspects to investigate, among others depropagation and thermal initiation. Addnl., all equipment has to be designed for this temp. range. In the scope of this work, the radical polymn. of Me methacrylate (MMA) is investigated for temps. between 140 DegC and 180 DegC in a continuous pilot scale tubular reactor. The reaction kinetics were detd. in batch expts. and implemented in a PREDICI model for the simulation of the continuous process. This model includes the initiation by MMA peroxides, which can form in the monomer from dissolved mol. oxygen, as well as a high temp. gel effect model and the depolymn. of the living chains. The pilot plant consist of Sulzer SMXL equipped DN20 tubes and has a max. throughput of 10kg/h. The first part is a loop reactor with a recycle ratio of approx. 45:1, which is followed by a tubular part. Both reaction zones contain high temp. ultrasound probes for inline conversion measurement. A micro-dosing pump allows further addn. of initiator or stabilizers into the process between the two reaction zones. For devolatilization of the polymer, a one-step flash chamber with a two-phase preheater is employed. The process is evaluated with respect to final monomer conversion, mol. wt. distribution and residual volatiles' concn. (VOC) of the produced polymer. First runs with the pilot plant have led to satisfying results, which show the feasibility of the high temp. polymn. and the agreement with the modeling. Final monomer conversion was limited to 60% by the choice of an appropriate initiator and mol. wts. between 150.000 and 200.000 g/mol were obtained.

2005

Development of a continuously operated reactor for the limited hydrolysis of whey protein by trypsin

Antoine Margot, Albert Renken

A continuously operated reactor was developed for the limited hydrolysis of whey protein using sol. trypsin. It consisted of a stirred tank followed by a tubular device. A stirred tank was used because it allows pH control to be achieved more easily. The tubular reactor was applied to achieve a high level of conversion without pH control. The tubular reactor was equipped with static mixers for approximating plug-flow behavior. The behavior of the reaction system under floating pH in both parts of the reactor was evaluated sep. prior to verification of the results in a pilot-plant which consisted of the combination reactor. The operating temp. and pH in the stirred tank were investigated as the main variables of the process. [on SciFinder (R)]

1998