Research on Bus Type Temperature Measuring Instrument for Pot Calciner using Brightness Temperature Measurement Method

A low-cost, high-precision CAN bus temperature measurement instrument, designed for the harsh on-site conditions of pot-type calciners used in carbon production processes, has been developed. Based on the brightness thermometry method widely used in non-contact temperature measurement, this instrument incorporates online blackbody cavity theory to address practical engineering challenges. Correction methods are proposed for the effects of “non-sealed” and “non-isothermal” blackbody cavities on temperature measurement accuracy. How to model and get the integrated emissivity εcv of a hemispherical-bottom blackbody cavity is argued. On the same time, the calculation method and reference values for the non-isothermal coefficient K t are established. The instrument employs a high-precision AD acquisition chip to achieve high-accuracy sampling of nA-Ievel weak photocurrent signals, power frequency common-mode filtering, fifth-order polynomial fitting of temperature calibration equations, precision calibration, and temperature drift compensation for photodiodes. A highly real-time data communication network is implemented via CAN bus. Laboratory and field tests demonstrate that the instrument achieves $\pm 1\%$, measurement accuracy at 1300°C process points, with a 72-channal data refresh cycle under 200 ms, while maintaining long-term operational stability.