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Show Introduction A great deal has been written about the need for greater efficiency when burning fossil fuels and this has been complemented over recent years by the need to minimise atmospheric pollution especially NOx and particulates. Millions of dollars have been spent on devising a whole multitude of combustion devices, all claiming higher efficiency and some of them reduced pollutant levels. Unfortunately in 99.99% of cases where fossil fuel is burnt a supply of air is required to provide the oxygen to react with the fuel. On any fossil fuel burner it is of paramount importance to ensure that air is supplied to the burner in the way that the burner is designed to accept it. It is even more important in a multi-burner installation that equal air distribution to all burners is achieved as well as the correct presentation. Fuel distribution is of course equally important but due to the higher pressures, relatively small pipes utilised and the fact that the fuel distribution device is invariably immediately upstream of the flame, fuel distribution and presentation are not usually a problem. The use of sensible velocities, ring mains and complementary piping layouts to multiple burners plus attention to correction of hydraulic head on a tall combustion chamber plus precision machining of fuel nozzles normally allows for a fuel distribution of within ± 1% between burners. Unfortunately due to the size of air ducting and windboxes the correct and even flow of air cannot be guaranteed even when sensible velocities and duct sizes are employed. - 4 - |