CS252373B1 - Use of a slurry mixer for continuous viscosity sensing of high viscosity media - Google Patents

Abstract

Precise continuous measurement of the viscosity of processed melts of synthetic polymers, especially in fiber production, is ensured by using a static mixer built into the pipe. The static mixer is thus used not only as a means for continuous homogenization but also for measuring the viscosity of a flowing high-viscosity medium by evaluating the pressure drop.

Description

It is an object of the invention to use a static mixer for sensing the viscosity of high viscosity liquids such as polymer melts.

Until now, methods and devices for continuously viscositing viscosities of high viscosity liquids, such as polymer melts of 150 to 500%, have not been satisfactorily solved, particularly in manufacturing conditions.

For these purposes, capillary viscosimeters have been used in which the pressure difference was measured before and after the capillary placed on the bypass of the production line, as reported by CS AO 188 489. The disadvantage of such a meram is that the capillary flow profile narrowed in a short time and thus changed and the pressure drop, so in fact the wrong values were measured. Another possibility was provided by rotational viscosimeters in which the load of the rotating measuring element drive was measured, which is proportional to the viscosity of the measured medium. Their disadvantage is that it is not suitable for high pressures and temperatures due to damping and also for depositing media on rotating elements.

The above mentioned drawbacks are solved by the use of a static mixer as a means of continuously sensing the viscosity flowing through the high viscosity medium, wherein the measurement in production conditions does not alter the melt conditions of the polymer by the static mixer and consequently changes the pressure drop of the medium before and after the static mixer.

When using static mixers, we have found that during long-term use of these, there is no formation of deposits on its surface, so that flow properties change to such an extent that the measurement under operating conditions is not. reprodukovateliné. In addition, the flow profile of the static mixer is much larger than it is with capillary viscometers, which need to be solved by the bypass of the production line, as in CS AO 188 489, where only a portion of the medium flows due to the small cross section of the capillary. From this reason, the measurement is impaired. Despite the static mixer, the entire amount of medium to be coupled is preferred, with the most desirable homogeneity and hence its static mixing - hypogemisation.

A major problem is at high pressures around 20 MPa and temperatures up to 350 ° C measured. the medium is sealing and mounting the shaft of the rotary sensor so that this does not affect the resistance of the medium being measured to it. rotating element. Additional energy is needed for both the notation and capillary viscosity scanners for the function. No additional energy is required for the proposed use.

An example is the use of a static mixer consisting of a tube in which various molding partitions are installed to mix the flowing medium. By sensing the pressure drop on a static mixer, the viscosity of the flowing medium can be continuously evaluated.

Using a static mixer as a means of continually sensing the flow viscosity. of the high-viscosity medium of the present invention by a simple and reliable method solves the problem of sensing viscosity changes in a thermoplastic polymer processing process, wherein the melt viscosity is an important technological parameter. In automating the processing processes of thermoplastic polymers by plastic but most notably fiber processing, it is important to obtain reliable melt viscosity data for computer inputs and to adjust the entire technological process accordingly.

Claims (1)

SUBJECT The use of a static mixer incorporated into the trunk as a means for continuously sensing the viscosity of the high viscosity medium of the invention in the evaluation of the pressure drop.