Weltec Biopower is currently building an ultramodern biogas plant in Szeged with stainless steel from ThyssenKrupp Nirosta. The 1MW facility, made up of two combined heat and power plants with an output of 600 kW/h each, will go into operation at the end of 2011. Local farmers will supply the organic waste substrate and use the digestate left over from the biogas production process as fertilizer on their fields. The generated heat will be used to heat offices in Szeged. Two stainless steel digesters lie at the heart of the plant. In addition, an external stainless steel gas storage tank with a capacity of 650 cubic meters will be installed on the site. The goal is to take advantage of electricity prices, which are twice as high during the daytime. Therefore, the biogas will be collected in the digester tank and the external gas tank at night and the two CHP modules will run under full load in the day time. The two 3000 cubic meter digesters are sealed with a double membrane roof, so each digester also has an additional gas buffer capacity of 1016 cubic meters. During biogas production, waste products such as sulfur and ammonia are also formed; as these are highly corrosive substances, stainless steel is used exclusively for these plants. Over the past ten years, ThyssenKrupp Nirosta has supplied approximately 1500tons of material for various projects carried out by Weltec Biopower. Martin Stöckl, part of the ThyssenKrupp Nirosta sales team had this to say: “The majority of our deliveries have been our standard sheet steel Nirosta 4301 specially optimized for these applications. What’s particularly important for us is the cold-worked condition, 2H. This means thinner steel can be used to build the digesters without any loss of stability. It also means a significant cost saving”. The dense surface of Nirosta 4301 2H gives aggressive substances no chance to attack the material; the bacteria has no opportunity to take hold.
