Evaluation of the Low Temperature Heat Exchanger Fouling Problem. Results of Studies on Soot Production and Condensing System Fouling

摘要

The development of condensing heat exchangers for oil-fired heating equipment would yield a significant improvement in thermal efficiency. Soot production by oil burners, however, could lead to serious fouling problems in these systems. The objectives of this study were to investigate the causes of fouling in oil-fired condensing systems and to evaluate the need for the development of advanced oil burners. Tests were done to evaluate the effect of operating conditions on start-up and shutdown smoke production in both noncondensing and condensing furnaces. Modern retention head burners which are commonly used in the US were included as well as one European burner with some different design features. These features included the head design, a fuel shut-off in the nozzle tip, and nozzle heating. This burner was found to produce less smoke on start-up and shutdown than the common US burner. Fouling studies were done on both types of burners under cyclic conditions with relatively low excess air (10% CO sub 2 ) and continuous induced draft. Soot deposition did not cause any change in system thermal performance although soot deposition was heavier than would be expected with a noncondensing system. Tests were also done on the effects of fuel quality on soot production. Measurement techniques for soot included the common Bacharach smoke spot test, optical opacity, and filtration (EPA method 5). 27 refs., 69 figs., 18 tabs. (ERA citation 11:006957)