Prevention of Boiler Cold End Corrosion Using Water-fuel Emulsions

The objective of this study is to enhance the energy efficiency and environmental safety of boiler plants and engines equipped with waste heat recovery boilers. This objective is achieved by utilizing water-fuel emulsions as fuel for these boilers and engines. Using an experimental setup configured for the preparation and combustion of both standard fuels and water-fuel emulsions, the influence of the quality and composition of these emulsions on corrosion processes affecting heat exchange surfaces was investigated. The studies were conducted using emulsions with a water content ranging from 2% to 30%, fuels with a sulfur content of 0.98% to 2%, and an excess air ratio of 1.01 to 1.5, covering a tube wall temperature range of 70°C to 150°C. The most significant outcome of this study is the data demonstrating the absence of a corrosion peak and a substantial reduction in the corrosion penetration rate to acceptable levels (0.2...0.3 mm/year) when using emulsions with a 30% water content across a broad range of excess air ratios (1.01–1.15). Under these operating conditions, a passivation effect was also observed on the surfaces of the carbon steel boiler tubes. The significance of this research lies in the fact that the technology prevents or mitigates low-temperature corrosion on heat exchange surfaces, thereby enabling increased heat recovery from flue gases in boiler systems. For waste heat boilers in marine diesel engines, the heat recovery efficiency increases by 10–15%, as the exhaust gas temperature decreases from the design range of 160–180°C to values of 130–150°C.