| 摘要 |
PURPOSE:To make it possible to calibrate a moisture measuring device on line, by measuring three kinds of calibrating materials of autozero, zero, and span. CONSTITUTION:A radiation source 1 is enclosed in the tip of a radiation source rod 21. The radiation source rod 21 is inserted at the rear side of a radiation source container 2. In a rotary shutter 22, the following five positions are provided: shutter open (c); closed (d); autozero (e); zero (f) and span (g). At the shutter open, a through hole is provided, and neutrons and gamma rays are inputted through a radiation port 26. The shutter closed is filled with a shielding material so that the radiation is not outputted to the outside. In the autozero, zero, and span, a neutron absorbing material 27 and a gamma ray absorbing material 28 are combined and embedded. The moisture and density values of the calibrating materials are obtained by the actual measurement. Namely, absorption coefficients are determined by using simulated hoppers. Then, the moisture and density values of the three kinds of the calibrating materials are measured by using the absorption coefficients. It is necessary to use the calibrating materials whose quality is stable and constitution of elements is close to actual coke. As the neutron absorbing material, polyethylene is used and graphite is used as the gamma ray absorbing material. |
