Wet scrubbing is the most common method to clean the flue-gas. Metrohm Applikon Process Analyzers are used to measure the calcium and sulfate content in several stages of the scrubbing process.
Flue-gas desulfurisation (FGD)
The flue-gas desulfurisation (FGD) is used during the incineration process of waste materials. It is one of the steps in the process to remove components that can harm the environment. FGD is a well-established process technology in fossil-fuel power plant operations.
The flue gas has to pass several cleaning steps before it can be released. Several types of scrubbers are used. Most common is wet scrubbing. First step is burning of the waste followed by quenching of the gas to overcome that the hot gas will evaporate the scrubbing liquor. In the quencher most of the chloride and ammonium is captured. The next step is scrubbing of the gas with an alkali reagent to enhance the absorption of sulfurdioxide and other acid gases. The pH must be kept within a certain range to ensure high solubility of SO2. The SO2 is in this step converted to SO42-. The used water for this step should not contain Ca and Mg to overcome the formation of CaSO4 which can lead to blockages in the scrubber. Modern incineration plants collect the sulfate from the scrubber in a next step by adding lime/limestone. The formed CaSO4 (gypsum) can be separated and sold to make other products.
Metrohm Process Analyzers are used to measure the calcium and sulfate content in several stages of the scrubbing process. In this way the efficiency of the scrubber can be optimised for process improvement and problems with the formation of scale prevented thus reducing operation and maintenance costs.
