| 摘要 |
PURPOSE:To improve the accuracy of measurement, by arranging a measuring tube in such a way that the tube is set up so as to penetrate the duct intersecting perpendicularly to the direction of flow of material to be tested, and equipped with openings that introduce the air of out-door and exhaust the air respectively. CONSTITUTION:A measureing tube 11 is arranged to penetrate a flue 10, and a projector 12 is equipped at the end of the tube and a receptor 13 is at the other end, respectively. In addition, the tube 11 is equipped with air inlet nozzles 161, 162 and air exhaust valve 17, respectively. The air is injected from the air inlet nozzles 161, 162 to a certain extent that the gas enters the section covered with outer tubes 141, 142. Accordingly, the amount of dust relating to absorption and scattering of light projected into the measuring tube is diminished to permit density measurement with high accuracy, even if a larger amount of dust exist in the flue. |
