GB797835A - Improvements relating to gas-detecting apparatus - Google Patents

Abstract

<PICT:0797835/III/1> Apparatus for detecting and estimating a gas in a gaseous mixture comprises a vessel 1, Fig. 1, containing a liquid which is ionisable by dissolving the gas therein, and provided with electrodes 2 connected to means measuring the electrical resistance of the solution, and a second vessel 12 containing a de-ionizing medium in circuit with the first vessel. The top of the vessel 1 is connected through a tube 6 with a chamber 7, surmounting the de-ionizing chamber 12, and having a port 8 to which suction may be applied. In operation, the apparatus is filled with water to the level of the overflow 9, which is then closed. Suction is then applied to port 8, which draws water from the vessel 1 through pipe 6, and then downwards through chamber 12 containing an ion exchanging resin. Gases under test enter a pipe 4 through a filter 5 and pass as a stream of bubbles, assisted by an agitator, through the de-ionized water to the exit pipe 6. The level of the liquid fluctuates about the bottom of the pipe 6, and a steady state is attained when a constant rate of flow of water through the circuit and of gas entering pipe 4 is achieved. Carbon dioxide dissolves in the water, providing a steady deflection of the galvanometer or other indicator G. Any increase or decrease in the CO2 content of the inflowing gas, alters the resistance between the two electrodes and thus the galvanometer reading. In a modification (not shown) the gas and water is circulated by a rotary pump and the circuit includes valves controlling the flow of gas/water mixture to the de-ionising column and of de-ionized water from it, whereby the relative proportions of gas and water circulated may be varied. In this form gases containing a high proportion of carbon dioxide, e.g. flue gas, may be analysed. In a further modification two electrode cells are used, before one of which is mounted a catalytic chamber, by which gases such as methane or carbon monoxide are converted to carbon dioxide. The apparatus is first adjusted to form a balanced circuit, and the catalytic chamber is then activated; a change in galvanometer deflection indicates the presence of additional carbon dioxide formed in the catalytic chambers.