JP2582255B

A method and an apparatus for continuously monitoring the concentration of gaseous constituents, except O2, in gas mixtures, for example in off gases from large furnaces. The method is intended to obtain the desired concentration values directly for the individual gas constituents in an undisturbed manner and with comparatively high accuracy simultaneously and separately. This is achieved by continuously measuring the concentration of the gaseous constituent using at least one electrochemical cell containing at least one solid-state subcell. The subcell contains a material which conducts oxygen ions and an electrode which contains a metal oxide and generates electrical signals which depend on the concentration of the constituent. The test signals are automatically evaluated electronically in a computer and converted into concentration values, the calculated values being compared with corresponding design values previously fed into the computer.