Question 19Steam Plants - Assistant Engineer

The correct answer is B) no CO, low O2, and high CO2. When the excess air is adjusted to achieve a light brown haze, it indicates that the combustion is operating at or near the stoichiometric air-to-fuel ratio, which is the ideal ratio for complete combustion. Under these conditions, the flue gas analyzer should show no CO (carbon monoxide), low O2 (oxygen), and high CO2 (carbon dioxide). This is because the combustion is efficient, and the fuel is being completely burned, resulting in minimal incomplete combustion products (CO) and high levels of the complete combustion product (CO2). The other options are incorrect because they do not accurately reflect the expected flue gas composition under the described combustion conditions. For example, option A indicates low CO2, which would not be the case in an efficient combustion process, and option D shows high CO, which is the opposite of what is expected when the excess air is properly adjusted.