VERFAHREN UND VORRICHTUNG ZUM MESSEN DER BRENNSTOFF- UND SAUERSTOFFANTEILE EINES GASES

摘要

1393396 Electro-chemical analysis WESTINGHOUSE ELECTRIC CORP 25 July 1972 [20 Aug 1971] 34666/72 Heading G1N [Also in Division G3] Both the combustibles and oxygen constituents of a gas are measured. A sample of gas from a flue F of a burner is applied in a counter flow pattern to a combustion sensor 10 including a catalytic thermopile sensing element 12 and heater element 14, Fig. 3 (not shown). The element 12 generates an e.m.f. indicative of the total content of the minority constituent of the sample gas, and which is completely reacted in the chamber 10 and is oxygen in an oxygen rich sample or combustibles in a fuel rich sample. After reaction the gas flows through a solid electrolyte oxygen titration cell 20 and a solid electrolyte oxygen monitoring cell 40 the outside of which is surrounded by a reference gas such as air. In the event of an oxygen rich sample the output from 40 will be in the range 0-200 mv whereas in the event of a fuel rich sample when the oxygen has been depleted in the chambers 10 and 13 the output of cell 40 is in excess of 800 mv. If the e.m.f. generated by the cell 40 exceeds a predetermined set point value between 200 mv and 800 mv indicative of a combustibles rich condition a feedback signal FB is transmitted to a D.C. voltage excitation circuit 50 which applies a D.C. potential across inner and outer electrodes 22, 24 of cell 20 proportional to the difference between the e.m.f. generated by cell 40 and the set point value. This potential establishes a flow of oxygen from the oxygen reference outside the cell into the sample gas flow. This pumping action continues until the oxygen content of the sample gas as measured by assembly 40 is sufficient to establish a predetermined relationship between combustibles and oxygen. Thus the current measured by ammeter A is a direct measure of the excess combustibles in the gas. Electrical output signals from the combustion sensor 10, the output signal of assembly 40 indicative of excess oxygen and indicated on voltmeter 60 and the current measurement from ammeter A indicative of excess fuel are fed to computer circuit 70 to provide measurements of the total oxygen and combustibles content of the sample gas and which are used to control a fuel-oxygen supply system 80 in order to obtain the desired fuel-oxygen ratio in a burner B of furnace F.