A method and an apparatus for contactlessly determining the temperature of a stream of conveyed material and granulation device having such a contactless temperature determination apparatus

A method comprising:

• contactlessly sensing, with infrared sensors, a stream of conveyed material flowing past a background;
• varying, with a temperature control apparatus, a temperature of the background in terms of time and/or location;
• determining, by an evaluation device, degrees of fluctuation of the temperature of the background from a measurement signal from the infrared sensors for different background temperatures;
• subjected the measurement signal to a regression analysis by a regression analysis module of the evaluation device;
• determining by the regression analysis module, a functional relationship between a change in the degrees of fluctuation and a change in the background temperature in terms of time and/or location;
• determining, by the evaluation device, the time and/or location at which a minimum fluctuation occurs by means of the determined functional relationship;
• and
• determining an object temperature for each of one or more objects in the stream of conveyed material from the value of the measurement signal at the time and/or location of the minimum fluctuation determined from the functional relationship.

An apparatus for non-contact temperature measurement of strand-shaped or granule-shaped objects of a stream of conveyed material comprising:

• infrared sensors for capturing the radiation field of the stream of conveyed material flowing past against a background;
• a temperature control apparatus for controlling the temperature of the background wherein, conditions for measurement under specular inclusion can be produced through an environment;
• and
• an evaluation device for evaluating the measurement signal from the infrared sensors and determining the object temperature from the measurement signal;
• wherein the temperature control apparatus is configured to vary the temperature of the background in terms of time and/or location;
• and
• wherein, in the measurement signal from the infrared sensors captured at a varying background temperature, the evaluation device is configured to evaluate a degree of fluctuation of signal fluctuations and to determine the time and/or location of a fluctuation minimum and to determine the determined object temperature from the value of the measurement signal at the time/location of the fluctuation minimum.