Holzwerke Weinzierl GmbH is responsible for an excellent case study for retrofitting existing plants: at its Vilshofen premises in Germany, it operates a saw mill as well as a biomass power plant using an ORC plant. Here, generated heat is used for drying sawn timber. To tap into the potential that this facility offers, last year the company invested in not only a pelletising plant with a capacity of 80,000 t/year, but also additional drying chambers.
To ensure that sufficient heat from the existing biomass power station could be applied to pellet production, Scheuch retrofitted the existing boiler with an ERCS heat recovery plant for heat extraction purposes. The company also installed a flue gas condenser. Additionally, the patented tower construction allows for a plant configuration that is both space-saving and energy-saving.
"The ability to combine chip drying and condensation heat is ideal for us – particularly in winter, the Scheuch system offers some key advantages", said Managing Director Hans Weinzierl. "With a fuel moisture content of 55%, during the colder months we can recover more than 4 MW of heat from exhaust gas that would otherwise go unused. That equates to 40% of the boiler output. We feed the heat that is recovered to the pelletising plant's belt dryer."
Thanks to the compact structure of ERCS plants, it is easy to retrofit Scheuch heat recovery systems in existing boiler plants. Evidence of this benefit is found in the positive experiences that operators have gained from several plants operating in biomass heating and heating/power plants working with output ranges between 1 MW and over 50 MW – and an increasing number of operators are getting on board.