| 摘要 |
<p>Methods and apparatus (1) for measuring the mass flow rate of solids suspended in a gas stream (2) flowing along a pipe (3). Two ultrasonic transducers (4, 5) are mounted in short side arms (6, 7) extending from the pipe. The transducers are arranged such that signals are transmitted from one to the other through the gas stream at an angle Υ, usually about 45°. The received signals in both transducers are received by apparatus (8) and amplified. The invention allows determination of: the mean times for the ultrasonic pulses to travel from one transducer (4) to another (5) and vice-versa; the mean peak amplitude of received pulses; and, the standard deviation or spread of these parameters. The mean times taken for the ultrasonic signals to travel between the transducers are used to determine the gas flow velocity, and the mean peak amplitudes for calculating the solids loading. From these the mass flow rate is derived. The invention is applicable to determining mass flow rates of pulverised coal contained in an air flow in a large power station.</p> |
