TEMPERATURE DETECTING APPARATUS FOR CONTAINER OF GRANULAR MATERIAL

PURPOSE: To detect the temperature of a granular material in a silo by installing transmitting and receiving antennas set on the opposite to each other in the container of the granular material and a plurality of dipole antennas which are mixed with the granular material and of which middle parts are joined with a heat sensitive combination to be electrically communicated at a prescribed temperature. CONSTITUTION: Together with coal 3, dipole antennas 10 are mixed in a silo main body 1 (a container for granular bodies). A transmitting antenna 9 and a receiving antenna 8 are installed in both side walls of the main body 1 and on the opposite to each other and connected to a monitoring apparatus. The antennas 10 are produced by joining linear conductors 11A and 11B with a heat sensitive combinations 13. The length of the conductors 11A, 11B and the total length are set to be LA, LB and L, respectively. When the temperature of the coal becomes a prescribe temperature or higher, the combinations 13 are electrically communicated and the antennas 10 becomes an antenna with element length L and having long reflecting wavelength. The reflecting characteristic of the antennas 10 becomes the maximum when L=λ/2 wherein λ stands for wavelength of the electric power source. Consequently, the transmission of electric waves transmitted from the antenna 9 and received by the antenna 8 through the coal 3 remarkably fluctuates at the prescribed temperature or higher due to the remarkable reflecting characteristic change of the antennas 10 and thus temperature can be detected.