Question 325Steam Plants - Assistant Engineer

The correct answer is C) Turndown ratio. The turndown ratio represents the ratio between the highest and lowest fuel oil pressure at which the burners will remain ignited. This is a key specification for boiler burners, as it indicates the range of firing rates over which the burner can operate effectively. A higher turndown ratio allows the burner to operate efficiently at a wider range of firing rates. The other options are not directly related to the specific ratio of fuel oil pressures. The modulating band ratio refers to the range of control over the fuel/air mixture, the firing range ratio is a broader term for the operating range of the burner, and the air/fuel ratio is the specific proportion of air to fuel in the combustion process.