For the community of Swindon in England, an investment in a state-of-the-art municipal solid waste plant was a major commitment for the future.
Swindon commercial sales appointed Machinex for a turnkey solution that separates and processes material to produce refuse-derived fuel (RDF) and solid recovered fuel (SRF). This facility represents a major step forward from the unsustainable landfill waste disposal methods of the past. The goals for the new municipal waste plant were ambitious:
- Process 48,000 tons per year of municipal solid waste, as well as commercial and industrial waste.
- Separate materials to produce RDF and SRF for sale and use in industrial applications.
A key part of this challenge was to find the right drying solution for RDF—one that is capable of handling light materials with widely varying moisture content and bulk density and producing fuel products consistently according to strict standards.
Solution
Based on its special features and several market references, an Andritz Vandenbroek drum dryer was selected as the optimal drying solution. The main benefit is the Vandenbroek’s proven ability to achieve SRF standards of 15% to 20% moisture con- tent while creating a low amount of exhaust gas. The pre-dried materials can fluctuate between 50% and 20% moisture content, so careful process and equipment selection is needed to achieve consistent results. Due to the special drum internals (the MPS multi-pass system), controlled product moisture content is achieved continuously. A regenerative thermal oxidizer (RTO) was added to ensure efficient exhaust gas treatment in order to remove contaminants from discharged gases. The installed solution, completed in May 2014, is able to achieve 12 tons/hr of throughput thanks to the drying system that ensures the flexible drying time needed for the fluctuating input materials.
Results
Following the performance tests, the drying plant has successfully achieved all its objectives, including SRF standards of less than 20% moisture content with more than 95% dryer plant availability. Additionally, drying of RDF results in a high calorific value, which makes the product an attractive alternative to several fossil fuels. For the community of Swindon, the result is now a consistent stream of high-quality RDF products, along with air pollution control due to efficient off-gas treatment methods. In addition to reducing massive quantities of local waste, the end fuel products will provide valuable revenues to offset the costs of their investment. Currently, the plan is to export these products for sale in Germany until other industries in the U.K. are able to follow the community’s lead towards the future of renewable fuels.