The calorific value and the total nitrogen oxide content of the supplied fuel in the thermal waste treatment plant can vary widely depending on their composition. Due to the long travel time for the flue gases to reach the measuring point, dosing of the reduction agent in the SNCR process can be adjusted only with a delay. The result: delayed control, under- or over-dosing of reduction agent, non-stoichiometric conversion.

With NOx-Calc, a specific extension of the well-known online balancing method, Opti-Link continuously calculates the total nitrogen content of the supplied waste and balances insufficiently measurable parameters, such as the NOx raw gas value.

For this purpose, the relevant data of all measuring devices is sent via a data interface to Opti-Link through the process control system. Opti-Link balances the entire thermal process by analysing the sub-processes. These sub-processes include the air supply, the fuel supply (to the extent possible), the combustion process, the steam end, the feed water system and the flue gas post-treatment process. The available data is used to create and analyse mass and energy balances, to enable calculation of the values and parameters that cannot be measured directly. They are then immediately available for controlling the SNCR and optimising the overall process.