LIST Direct Devolatilization

The Elastomer synthesis requires the separation of the solvents from the polymer after the polymerization step.
Hereto, LIST offers the Direct Devolatilization Technology DDT, characterized by

Few process steps
Continuous processing & close polymer temperature control
Low energy consumption
Direct solvent recovery
Minimized water consumption
Low space requirement

These features lead to a high and constant elastomer quality, while simultaneous saving energy and reducing the environmental impact.
Nevertheless, LIST is constantly working to further increase the DDT's efficiency.
LIST’s latest DDT generation, DDT Gen-3, succeeds to significantly reduce the complexity of the machinery set-up and thus to greatly simplify the process itself.
Learn more about DDT-Gen 3 and its improvements compared to the preceding generations DDT Gen-2 and DDT Gen-1. All of them replacing the traditional steam-stripping and enabling specialty rubber grades without noticeable restrictions.

DDT Gen-3 - Striking simplicity
DDT Gen 3 stands out by its great simplicity of just two process steps: a continuous main evaporator (CME) and a subsequent devolatilizer (Finisher).
This simple structure means a groundbreaking advance. The preceding generations Gen-1 and Gen-2 depended on a preconcentration step using a static flash-pot, and thus, required significant build space and capital.
Further, DDT Gen-3 stands out by electro-mechanical drives, requiring less space and less maintenance work.

The proven devolatilization platform for:

Synthetic rubbers
Thermoplastic elastomers
Plastics

Removal of VOC:

Solvents
Monomers

MORE INFORMATION

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Contact the author:

Dieter Mayer
Product Manager
dieter.mayer@list.ch
T +41 61 815 31 54

DDT Gen-3

Your sustainable future through striking simplicity

Two stage process

Continuous Main Evaporator CME

Concentration of the polymer solution
up to 98 wt-%
directly from the reactor
even at low TSC concentration

Single shaft Finisher

providing high quality rubber
at low VOC content

LIST Direct Devolatilization

Gen-1 replaced steam stripping
The big break-thru of DDT Gen-1 in the early 2000-ies was the complete avoidance of the water and energy intensive steam-stripping. The steam-stripping process exposes the polymer solution to a steam-beam and generates a polymer-water suspension which has subsequently to be dried. As the DDT Gen-1 process avoided the intermediate step involving steam and water, it was called direct-devolatilization. The term “DDT” was born.

The Gen-1 process targeted crumbs as final product which exit the LIST devolatilizer to meet the product's shape of the conventional synthetic rubber process. However, final volatiles values were multi digit percentages and did not meet market expectations. This was resolved by DDT Gen-2.

Gen-2 reduced the final volatiles
The big progress of DDT Gen-2 are the very low final volatile values. This was achieved in the year 2008 by keeping the polymer in the Finisher in a pasty phase, i.e. avoiding crumb formation, and thus enabling surface renewal.

By the aid of small amounts of water in the Finisher,
(a) the final volatile content could be reduced down to two-digit ppm values, and
(b) the polymer temperature could be kept under close control.

Thanks to the higher product density and higher devolatilization efficiency, the Finisher became smaller in size and could be built as a single-shaft unit, thus reducing complexity.
However, the DDT-Gen-2 still required a preconcentration step, which used a lot of space and caused high investment- and operating-costs. This disadvantage was lastly resolved by the DDT Gen-3.

DDT Gen-1

DDT Gen-2

Steam stripping

DDT Gen-3

Two stage process

Gen-3 eliminates the preconcentration

The DDT Gen-3 technology avoids a separate equipment set-up for the preconcentration. The flash is integrated in the CME. Thus, the equipment set-up is reduced from three (3) to two (2) process steps - a groundbreaking advance.

Solvent Recovery is an integrated part of the process.

The reduced complexity saves enormous capital and operating costs.

Specialty rubber grades are feasible without noticeable restrictions.

Reducing complexity to a minimum and increasing process efficiency to a maximum – a true LIST innovation.