Level measurement with guided microwave in a distillation column

The application

Toluoldiisocyanate (TDI) is an important intermediate product in the production of synthetic materials. During the production of toluoldiisocyanate, water in organic phase is generated and gets mixed with the product. Separation is carried out in a distillation column, the water being precipitated in the lower part. Due to the intermediate plates in the distillation column, the required level measurement is possible only through the use of a bypass tube.
In the past this measurement was realized via displacer systems or differential pressure measurements. The movement of a displacer is impaired, however, by a catalytic converter located in the tube. Such a measuring system requires continuous servicing and, what is more, density fluctuations of the medium can cause measurement errors of up to 10%. A differential pressure measurement requires two mounting sockets as well as an extensive thermal insulation. High process temperatures as well as deposits on the isolating diaphragm limit the service life of the measurement. Here also, the density of the medium influences the measuring result.

The process data

The solution

The ideal solution for level measurement is the VEGAFLEX 66 sensor, which operates according to the guided microwave principle. It is used as a direct replacement for the displacer, with no modifications of the bypass tube being necessary. The measurement works without any moving mechanical parts. Thus, it is influenced just as little by process-related buildup in the tube as by intense steam or fluctuating density, temperature or pressure.

The advantages

	Direct mounting on existing bypass tube
	No modifications of the column necessary
	Maintenance-free measurement
	Independent of process conditions
	Process temperature/Process pressure up to 400 °C/ 400 bar