Boilers with state-of-the-art flue gas treatment systems

A consortium consisting of Primetals and YARA Environmental Technologies has been awarded by Acciaierie d’Italia a contract for a new flue-gas treating (FGT) systems for the three 160 MW boilers at its power plant No.2 in Taranto, Italy. Within this consortium, Yara will deliver the new economizer and SCR (selective catalytic reduction) DeNOx elements and Primetals Technologies will cover the DeSOx- and dedusting part. The startup of the first FGT unit is scheduled for the fourth quarter of 2022 with the other two units following in short succession.

Built in the early 1970s, power plant No.2 (CET 2) is a conventional thermo-electric power plant which will now undergo a major environmental upgrade through the installation of state-of-the-art flue gas treatment technologies, including SCR DeNOx system (integrated in a new economizer) for reduction of NOx emissions by 80%, Meros DeSOx technology for reduction of SOx emissions to less than 130 mg/Nm³ and high-end fabric filters for removal of fine dust emission to less than 2 mg/Nm³.

In order to utilize the existing power plant configuration and the limited available space, several special considerations had been incorporated in the design of the new FGT systems already during the development phase of the project.

The high temperature of the flue gas coming from the boilers will be utilized for the SCR DeNOx process which requires temperatures of more than 300°C. The SCR catalyst will be integrated into the boiler economizer. Due to its condition, the existing, original economizer will be replaced by a new state-of-the-art version. SOX in the flue gas will be controlled by applying Primetals Technologies’ proprietary Meros technology.

Based on the favorable process conditions and the limited available space, sodium bicarbonate (SBC) will be used as DeSOx agent which ensures high DeSOx efficiency but does not require any water injection as it is a completely dry technology. This technology has been invented by Primetals Technologies and has already been successfully applied in numerous plants.

The FGT systems will also be designed to cover all the changing load- and flue gas conditions of power plant No.2. As the boilers are fired with the typical by-product gases from steel mill operation (coke oven-, blast furnace- and converter gas) the quantity and mix of those gases may vary depending on their availability and the FGT system will cover all those different load cases accordingly while still maintaining the required environmental performance. The project kicked off in June 2021 and will run on a fast-track schedule in order to reach compliance with the environmental requirements by the end of 2022.

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