Carbon Monoxide (CO)

1. SPECIFCATIONS colourless , tasteless, odourless

1.1. is product of incomplete combustion of fossil fuels & atmospheric oxidation of methane & other biogenic hydrocarbons

2. HOW IT INFLUENCE

2.1. CO is produced in large quantities at all fuel/air ratios

2.2. At low fuel/air ratios (say fpz < 0.5), temperatures are usually too low for CO to burn to carbon monoxide

2.3. At high primary-zone fuel/air ratios (say fpz > 0.5), CO burns quickly to equilibrium condition, which is higher than emission standards permit

3. HOW TO REDUCE

3.1. i. Improved atomization. The effects of improved atomization are to promote fuel evaporation and to enhance the level of mixing so that a more homogeneous state is achieved

3.2. Redistribution of the airflow to bring the primary-zone equivalence ratio closer to the optimal value (about 0.7)

3.3. Increase in the primary zone volume or residence time

3.4. Reduction of film-cooling air. The air issuing from primary zone normally contains high concentrations of CO & UHC

3.5. Fuel staging. This technique is based on cutting off supply of fuel to some nozzles & diverting it to the remainder.

4. HUMAN EFFECTNESS. it has a strong affinity towards hemoglobin of the bloodstream & is a dangerous asphyxiant

4.1. COHb lowers oxygen-carrying capacity of blood & has potential to starve brain & other tissues of oxygen

4.2. At high concentrations, death can result, as in the case of people committing suicide by inhaling vehicle exhaust fumes

5. HOW IT HAPPENS

5.1. In fossil fuel combustion, carbon monoxide is formed when oxygen is scarce & fuel does not burn properly

5.2. It can be seen that equilibrium CO is a function of air inlet temperature, as the temperature increases, CO increases

5.3. Besides air inlet temperature, equilibrium CO is also a function of equivalence ratio, pressure, residence time and mixing

5.4. This minimum CO equivalence ratio depends on burner design (fuel/air mixing) and on the residence time

5.5. Real well mixed burners will follow these equilibrium CO curves if there is sufficient residence time