CS252373B1 - Use of static mixer for fflowing high-viscous mediums' viscosity continuous scanning - Google Patents

Abstract

Accurate continuous viscosity sensing processed polymers of synthetic polymers, especially in the production of fibers, it ensures using a static built-in mixer db * 1 2pipe. Static mixer thus utilizing not only the means for continuous homogenization as well as for sensing viscosity flowing high viscosity media by pressure compression drop.

Description

(54) Use of a slurry mixer for continuously sensing viscosities flowing through high viscosity media

2

Precision continuously sensing the viscosity of the melt processing synthetic polymers, especially in the production of fibers, sia ensure the use of built-in static mixer ^{'* 1 2} db pipe. Thus, the static mixer is used not only as a means for continuous homogenization but also for sensing the viscosity of the flowing high viscosity medium by evaluating the pressure drop.

51 3 7 3

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

To date, methods and devices for continuously sensing the viscosity of highly viscous liquids, such as melt polymers at temperatures of 150 to 500 ° C, have not been satisfactorily solved, in particular under production conditions.

For this purpose, capillary viscometers have been used which have sensed the pressure difference before and after the capillary located on the bypass of the production line, as reported by CS AO 188 489. The disadvantage of such a measurement is that in a short time the flow profile of the capillary has narrowed and pressure drop and so in fact n-amerali wrong values.

Another possibility was provided by rotary viscometers in which the load of the rotating measuring element drive was proportional to the viscosity of the measured medium. Their disadvantage is that it is not suitable for high pressures and temperatures due to sealing and also for the settling of the medium on other rotating elements.

The aforementioned drawbacks are solved by the use of a static mixer as a means for continuously sensing the viscosity of a flowing high viscosity medium, in which the measurement at least under production conditions does not change the t-eye conditions of the polymer melt by the static mixer.

Using static mixers, especially obstacle mixers, we have found that during long-term use of these, deposits do not form on its surface so that the flow properties change to such an extent that measurement under operational conditions is not reproducible. In addition, the flow profile of the static mixer is many times greater than that of capillary viscometers, which need to be solved in 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. For this reason, the measurement is impaired. Advantageously, the entire treated quantity of the medium passes through the static mixer, with the desired homogeneity and hence its static mixing - htomogenization.

A major problem, especially at high pressures of about 20 MPa and temperatures up to 350 ° C of the measured medium, is the sealing and bearing of the rotary encoder shaft so that this does not affect the resistance of the measured medium to its rotating element. For rotary as well as capillary viscosity sensors for the function, additional energy is required. For the proposed use, additional energy is not needed.

An example is the use of a static mixer consisting of an oven in which various baffles of various shapes are incorporated to ensure that the flowing medium is mixed. By sensing the pressure drop on the static mixer, the viscosity of the flowing medium can be continuously evaluated.

By using a static mixer as a means for continuously measuring the viscosity of the flowing high viscosity medium according to the invention, it solves in a simple and reliable manner the problem of sensing viscosity changes in the process of processing thermoplastic polymers where melt viscosity is an important technological parameter. In automating the processing of thermoplastic polymers by plastic, but especially fiber, processes, it is important to obtain reliable melt viscosity data for computer inputs and adjust the entire 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.