Institute for Technical Chemistry (ITC), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
Institute for Technical Chemistry (ITC), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
Waste Manag. 2018 Mar;73:487-495. doi: 10.1016/j.wasman.2017.05.049. Epub 2017 Jun 7.
Sewage sludge quantities have grown continuously since the introduction of the European Directive (UWWTD 91/271/EEC) relating to the treatment of urban wastewater. In the present, most of the sewage sludge is combusted in single fuels incineration plants or is co-fired in waste incineration or coal power plants. The combustion of sewage sludge is a proven technology. Other treatments, such as fluidized bed gasification, were successfully adopted to produce suitable syngas for power production. Besides, the number of large wastewater treatment plants is relatively small compared to the local rural ones. Moreover, alternative technologies are arising with the main target of nutrients recovery, with a special focus on phosphorus. The aforementioned issues, i.e. the small scale (below 1MW) and the nutrients recovery, suggest that pyrolysis in screw reactors may become an attractive alternative technology for sewage sludge conversion, recovery and recycling. In this work, about 100kg of dried sewage sludge from a plant in Germany were processed at the newly developed STYX Reactor, at KIT. The reactor combines the advantages of screw reactors with the high temperature filtration, in order to produce particle and ash free vapors and condensates, respectively. Experiments were carried out at temperatures between 350°C and 500°C. The yield of the char decreased from 66.7wt.% to 53.0wt.%. The same trend was obtained for the energy yield, while the maximum pyrolysis oil yield of 13.4wt.% was obtained at 500°C. Besides mercury, the metals and the other minerals were completely retained in the char. Nitrogen and sulfur migrated from the solid to the condensate and to the gas, respectively. Based on the energy balance, a new concept for the decentral production of char as well as heat and power in an externally fired micro gas turbine showed a cogeneration efficiency up to about 40%.
自欧洲指令（UWWTD 91/271/EEC）出台以来，城市污水的处理不断推进，污水污泥的数量持续增加。目前，大部分污水污泥在单一燃料焚烧厂中燃烧，或在废物焚烧厂或燃煤电厂中混烧。污水污泥的燃烧是一种经过验证的成熟技术。其他处理方法，如流化床气化，已成功应用于生产适合发电的合成气。此外，大型污水处理厂的数量相对较少，而农村地区的污水处理厂数量较多。此外，替代技术正在兴起，主要目标是回收营养物质，特别是磷。上述问题，即规模较小（低于 1MW）和营养物质回收，表明螺旋反应器热解可能成为污水污泥转化、回收和再利用的一种有吸引力的替代技术。在这项工作中，大约 100kg 来自德国一家工厂的干燥污水污泥在 KIT 的新型 STYX 反应器中进行了处理。该反应器结合了螺旋反应器的优点和高温过滤，分别生产无颗粒和无灰蒸气和冷凝物。实验在 350°C 至 500°C 之间进行。在 500°C 时，炭的产率从 66.7wt.%下降到 53.0wt.%。能量产率也呈现出相同的趋势，而最大的热解油产率为 13.4wt.%。除汞外，金属和其他矿物质都完全保留在炭中。氮和硫分别从固体迁移到冷凝物和气体中。基于能量平衡，提出了一种在外部燃烧微型燃气轮机中就地生产炭以及热能和电力的新概念，其热电联产效率高达约 40%。
