Fives presented a new temperature measurement method for glass at GPC

Fives - GPC 6-9 November 2017-FIVES

Hosted November 6-9, 2017 at the Greater Columbus Convention Center, the 78th Conference on Glass Problems (GPC) is the largest glass manufacturing conference in North America, attracting glass manufacturers and suppliers worldwide to exchange innovations and solutions.

"A New Radiometric Measurement Device for the Temperature of Ribbon Zones in Tin Bath and Lehrs", a presentation presented at GPC by Dr. Wolf Kuhn, Senior Process & Development Expert, Fives Stein.

This Fives case study addresses one of the glassmaker’s biggest concern when trying to achieve a precise annealing curve in float glass lines. The purpose is to eliminate the considerable reading errors of the glass ribbon temperatures by the conventional thermocouple rods. A novel radiation measurement device has been developed by Fives that is based on the capture of the hemispherical ribbon radiation by a device with an absorption surface. The new measurement method allows cheap reliable mapping of ribbon temperatures in annealing lehrs. Moreover, the new radiometric measurement sensor can also be applied in the tin bath opening the gate for ribbon temperature mapping in this environment inaccessible for scanners. The case study captured the audience and sparked a lively discussion.

 

Abstract

The conventional thermocouple rods used to adjust the ribbon temperature in annealing lehrs are significantly disturbed by the cooling system. This leads to reading errors of up to 80°C compared to the real temperature of the glass ribbon.

A novel radiation measurement device has been developed that is based on the capture of the hemispherical ribbon radiation by a device with an absorption surface. This radiometric device is installed at distances of about 100 - 300 mm from the glass ribbon. The temperature of the absorption surface is detected by simple rugged sensors like TCs or PTCs. A detailed analysis of the radiation field allowed attributing a sensitivity width bands on the running glass ribbon to each radiation sensor. The sensitivity bandwidth depends on the distance of the sensor from the glass surface. This way, the implementation of the sensors is adapted to the width of the cooling zones of the lehr. Moreover, the impact of the coolers on the measured temperature is largely reduced. Tests with different configurations revealed the reliability and precision of the new method. The measurement precision of the new method is of the same order of magnitude as pyrometers. An annealing lehr has been equipped with the new ribbon temperature sensors and even tiny fluctuations of the ribbon temperature are measured correctly. The intrinsic precision of the sensors is better that 5°C and the measured ribbon temperatures compared to pyrometer values lay within 10°C.

The new measurement method allows cheap reliable mapping of ribbon temperatures in annealing lehrs. Moreover, the new radiometric measurement sensor can also be applied in the tin bath opening the gate for ribbon temperature mapping in this environment inaccessible for scanners.

More information