Improvements of zinc roaster waste heat boiler.

Outokumpu Zinc has two separate roasting lines with fluidised bed furnaces and waste heat boilers for calcine collection and heat recovery. Over the last 30 years, zinc production at the Kokkola plant in Finland has increased continuously and at the same time the raw materials have changed. The waste heat boiler plays a significant role in the process and consequently the reliability and efficiency of the device is important for the effectiveness of the entire process. The latest improvement to the boilers was the installation of a baffle wall, located in the middle of the radiation section roof in the first boiler, and of baffle plates in the lower part of the convection section in the second boiler. Boiler design and optimisation were carried out with the aid of water and air-dust modelling as well as computational fluid dynamics. Modelling results are in good agreement with experiences in practice and the latest developments have increased the operating hours per year and the effectiveness of the waste heat boiler.
Outokumpu Zinc has two separate roasting lines with fluidised bed furnaces and waste heat boilers for calcine collection and heat recovery. Over the last 30 years, zinc production at the Kokkola plant in Finland has increased continuously and at the same time the raw materials have changed. The waste heat boiler plays a significant role in the process and consequently the reliability and efficiency of the device is important for the effectiveness of the entire process. The latest improvement to the boilers was the installation of a baffle wall, located in the middle of the radiation section roof in the first boiler, and of baffle plates in the lower part of the convection section in the second boiler. Boiler design and optimisation were carried out with the aid of water and air-dust modelling as well as computational fluid dynamics. Modelling results are in good agreement with experiences in practice and the latest developments have increased the operating hours per year and the effectiveness of the waste heat boiler.