| 摘要 |
<p>Appts. for automatically cleaning a gas sampling probe incorporates a gas container, a source of compressed gas three electrically operated valves and a control system. The container is connected to the suction pipe leading from the sampling probe to the analyser, between the probe and the analyser. The control system brings about cyclical opening and closing of the valves. The cycle brings the press. in the container to the press. of the compressed gas source, isolates the analyser from the probe, produces a shock wave by opening the container suddenly and then re-establishes the normal suction circuit. An ejector is connected to the source of compressed gas and by fourth and fifth valves to the probe and to the container so as to purge them before re-establishing the normal suction. A sixth valve in the line between the compressed air source and the ejector is closed during the increase in press. of the container and the production of the shock wave. Used partic. of installations in which gas contg. large quantities of dust are analysed e.g. gas from furnaces, cement kilns, where water condensed from the gas being analysed or condensation of some vapours in the solid phase can block the sampling probe. The process is automatic abd avoids the shutting down and removal of some parts of the appts. to obtain access to the sampling circuit for cleaning, necessary in existing installations.</p> |
