One kilogram of sulphur in a fuel results in two kilograms of sulphur dioxide in the exhaust. Sulphur dioxide is produced by the combustion of sulphur in the fuel. Further complex chemical reactions in the atmosphere can result in the production of acidic compounds such as sulphuric acid (H2SO4). These compounds are a major cause of ‘acid rain’ which can have damaging effects on the ecology of the earth’s surface as well as causing corrosion damage to surfaces on which condensation occurs. Typical sulphur content and sulphur dioxide emissions are shown in the following table.
Sulphur content in fuels and typical SO2 emissions
|Fuel||Typical % sulphur in fuel||Kilograms of sulphur dioxide produced per tonne of fuel||Sulphur dioxide content (kg) per GJ 'available' energy (GCV)†||Sulphur dioxide content (kg) per MWh thermal input|
| Heavy fuel oil||2.0||40||1.16||3.33|
| Natural gas||nil||nil||nil||nil|
|†Assumes 80% of total energy is 'available' from combustion.|
The most effective way of reducing sulphur dioxide emissions is to reduce the amount of sulphur burned in combustion processes; the maximum permitted sulphur content of commercial fuels has been reduced in recent years, and further reductions are scheduled. Pollution abatement techniques are available, and a process known as flue gas desulphurisation (FGD) can extract sulphur dioxide from combustion process exhaust.
Previous: Carbon dioxide
Next: Carbon monoxide