Fouling of heat-transfer surfaces in oil-fired boilers for domestic heating

Abstract

Domestic-heating boilers fired with distillate oil are subject to fouling of the convective section gas-side surfaces, and this fouling leads to a reduction in efficiency and to increased maintenance requirements. A rapid test to enable the composition of fouling deposits and the rates of fouling to be studied has been developed and used at two laboratory sites. It involves special fouling surfaces which can be removed for deposit analysis. Fouling rates are shown to be directly related to the sulphur content of the fuel. Also, operation with reduced excess air in these boilers can lessen fouling rates by reducing the conversion of fuel sulphur to sulphuric acid. Results are compared with those from tests on full-size boilers.