[ Renewables ]
[ Renewables ]
Two rows of bolts join the prefabricated stainless steel segments vertically . Once an enormous ring is completed , jacks lift it so that the next ring can be assembled at the bottom of the tank . The rings are horizontally connected with special profiles that enhance the stability of the tank wall . All vertical and horizontal joints are sealed . Photo © Erich Stallkamp ESTA GmbH
that allows for cost-effective material choices . By selecting an appropriate corrosion resistant grade , it is possible to mitigate the negative effects of corrosive compounds . This ensures trouble-free operation throughout the lifespan of digestion and storage tanks , as well as other components like pumps , valves , agitators , pipes , fittings , and purification equipment . A digester tank for example , can be divided into two zones , the lower part which is filled with liquid and solid biomass and the gaseous zone above . The splash or tidal zone at the interface is particularly susceptible to corrosion , as corrosive substances can concentrate on the tank walls during wetting and drying cycles . To address this , it is common to use a more highly alloyed grade such as 2205 duplex stainless steel , for the upper part . For the permanently submerged bottom part a lower alloyed stainless steel can be used , such as 2101 duplex . These molybdenum-containing stainless steels provide sufficient corrosion resistance and durability for each particular
Agitators inside the digester help to mix different feedstock components , homogenize the temperature of the biomass and reduce crust formation . The internal heating system ensures constant temperature of the biomass . Flexible , corrugated stainless steel tubes with up to 50 % more surface area allow for continuous optimal heat transfer . Photo © Weltec Biopower
Near Belfast , Northern Ireland , a food logistics company implemented an innovative approach to fuel its trucking fleet with food waste from the grocery stores it serves . A total of 17,500 tonnes of organic material sourced from over 40 supermarkets is converted to RNG on an annual basis . The food leftovers undergo a process of pasteurization , shredding and homogenization , followed by anaerobic digestion in two stainless steel digesters with a capacity of 2,625 cubic meters each . To use it as a truck fuel , 450 cubic meters of biogas are upgraded into RNG every hour . The company ’ s fleet of trucks , which run on this biofuel , emit an impressive 93 % fewer carbon emissions compared to traditional diesel trucks .
Photo © McCulla Transport
32 Stainless Steel World December 2023 www . stainless-steel-world . net