Catalytic effect of the plasma spraying coatings on the increase of combustion of the gas fuels

In the first part of the paper researches on temperature distribution and Co and CO2 content in a pipe furnace are presented. The walls of combustion chamber were sprayed with catalytic coatings produced from cerium, manganese and copper oxides. The furnace was city gas-fired and combustion was performed at different values of excess air number. It was observed that depending on the type of the sprayed coating the increase of combustion gas temperature ranging from several to over a dozen per cent and distinct decrease of CO content in combustion gases were obtained. The values of those parameters strongly depend on excess air number which value cannot be lower than 0.9. The second part of the paper deals with the measurement of temperature distributions and CO and CO2 concentrations in combustion gases flowing through pipe recuperator which surface was covered with coatings produced of the oxides. In the recuperator city gas was burned at excess air number within range 0.8-1.1. the coatings plasma sprayed on the surfaces of recuperator pipes, resulted in considerable decrease of CO concentration in combustion gases (by several times) and 10% increase of combustion gas temperature, especially in the central part of recuperator as well as increase of temperature of air heated in it by several per cent. Finally investigation were carried in gas furnace type PG-11 for heating water in flats and houses. The effect type of coatings for increase of temperature of heated water was determined in that stage of research. Above mentioned three stages of research allowed for the choice of the best plasma sprayed coating which was obtained with the mixture 43% CeO2+57%Al2O3. (author)