Controlled condensation step by step
- Cooling. The flue gas is cooled to a temperature between the water dew point and the sulphuric acid dew point, about 60–90 °C, so that the SO3 condenses.
- Collection. The condensed sulphuric acid mist is deposited on the walls of the condenser and in a fine sintered glass filter.
- Analysis. After the sampling, the collected sulphuric acid is analysed and the amount of SO3 is calculated.
The method keeps the flue gas in a temperature range where SO3 condenses but the water vapour does not. So no SO3 is lost during the sampling, and the risk of interference from other gases is small.
Where is SO3 measured?
- Power plants and heating plants that burn sulphur-containing fuels
- Metallurgical processes and steelworks
- Sulphuric acid production and other chemical processes
How the measurement is done in detail, with the standard, the measuring range and what you need to prepare, is on the page about SO3 measurement. The equipment for your own measurements is under gas sampling.