One of the world’s biggest biogas plants when it was commissioned in 2009, the 13-hectare biogas park in Könnern, Saxony-Anhalt, Germany, was built by WELtec BioPower. Through an innovative treatment process, biogas produced at the plant is fed directly into the natural gas grid. Annual output is estimated to provide enough energy to heat about 10,000 homes. At the heart of the process are 16 huge digesters. Each digester tank is 6.30 meters tall and 25 meters in diameter.
Because byproducts of the biogas production process include highly corrosive components like sulfur and ammonia, material used in the tanks (and equipment within those tanks) must be corrosion resistant. If corrosion occurs, damage to equipment is inevitable – and that is a particular problem, as restarting a digester after a breakdown is a long and delicate operation.
The cost-effective solution
For construction of the Könnern plant, Outokumpu provided 1,500 tonnes of stainless steel match to specific needs.
In building the digester tanks themselves, cold-worked 2H surface allowed use of thinner steel with no loss of either strength or stability. Because stainless steel is both thin and easy to work with, use of stainless steel in tank construction reduced construction time and logistics costs. And because it is corrosion resistant, there is less need for maintenance. In considering lifecycle costs, that translates into significant cost savings.
Improving reliability and efficiency
Biogas plants put stainless steel to work in multiple ways with optimal grades used in different parts of the application.
Corrosion resistance remains essential in a process marked by high temperatures, but the fully recyclable material’s other properties are equally important. Excellent formability and gas and water tightness eliminate leakage concerns. And, because stainless steel’s surface is extremely smooth, aggressive substances are unable to attack it. Corrosion is nipped in the bud, an important factor in longevity. In short, stainless steel improves the reliability and efficiency of biogas plants.