Non-invasive temperature measurement in fixed bed reactors using RFID technology

Measuring axial temperature profiles in fixed bed reactors is essential for an optimal and safe operation. Typically, thermocouples are used which influence the bed structure – especially in arrangements with a low ratio between tube and particle diameter – and thus local transport phenomena and reaction rates. In this publication, Radio-Frequency Identification (RFID) tags are used for temperature measurement in fixed beds without disturbing the bed structure. Therefore, the temperature is compared in a tubular fixed bed (D=25.4mm) of ceramic rings measured with RFID tags and thermocouples at similar axial positions at different temperature levels 20<T<140<°C By integrating an RFID tag into a particle using 3D printing, the disturbance of the fixed bed by the measurement device can be even completely avoided. It is shown that the overall values of temperature and the dynamic measurement with RFID tags is comparable to measurements using thermocouples. However, significant measurement gaps can occur, especially with unfavorable antenna-tag alignment or small antenna spacing. As a summary, it is possible to measure temperature in fixed bed reactors using RFID technology without requiring direct access and thus disturbing the bed structure. Finally, current shortcomings of RFID are discussed, and research needs presented.