| 摘要 |
<p>A gas injection or aeration device, adapted to be immersed in a liquid and supplied with gas under pressure so that the gas emerges through diffusion nozzles of the device as a large quantity of small bubbles to form a liquid-gas mixture. The device includes a substantially vertically disposed riser tube which can be an open-ended conduit or can be defined, in use of the device, by a curtain of the rising bubbles. A sleeve, in which the nozzles are formed as apertures, expands under pressure of the gas supplied to admit the gas into the liquid and then contracts to partially or wholly close the nozzles when the gas supply is subsequently turned off. The nozzle aperture may comprise an elongate slit of generally corrugative form. An undertube may extend, in use of the device, below the nozzles to entrain liquid to rise towards the nozzles.</p> |
