Utilization of used textiles for solid recovered fuel production.

One of the current important issues is the management of used textiles. One method is recycling, but the processes are characterized by a high environmental burden and the products obtained are of lower quality. Used textiles can be successfully used to produce SRF (solid recovered fuels). This type of fuel is standardized by ISO 21640:2021. In the paper, an analysis of used textiles made from fibers of different origins was performed. These were acrylic, cotton, linen, polyester, wool, and viscose. A proximate and ultimate analysis of the investigated samples was performed, including mercury and chlorine content. The alternative fuel produced from used textiles will be characterized by acceptable parameters for consumers: a lower heating value at 20 MJ/kg (class 1-3 SRF), mercury content below 0.9 µg Hg/MJ (class 1 SRF), and a chlorine content below 0.2% (class 1 SRF). However, the very high sulfur content in wool (3.0-3.6%) and the high nitrogen content in acrylic may limit its use for power generation. The use of alternative fuel derived from used textiles may allow 3% of the coal consumed to be substituted in 2030. The reduction in carbon dioxide emissions from the substitution of coal with an alternative fuel derived from used textiles will depend on their composition. For natural and man-made cellulosic fibers, the emission factor can be assumed as for plant biomass, making their use for SRF production preferable. For synthetic fibers, the emission factor was estimated at the level of 102 and 82 gCO2/MJ for polyester and acrylic, respectively.

Possibility of using alternative fuels in Polish power plants in the context of mercury emissions.

The progressive decarbonisation of industry is leading to a reduction in coal consumption and the substitution for coal with other types of fuels, including waste-derived alternative fuels. These fuels are characterised by high variation in the content of highly toxic mercury. Co-combustion with coal can cause significant emissions, exceeding mercury emission limits. Various alternative fuels (refuse-derived fuel (RDF), waste paper, textiles, plastics, film, tires and their char, and sewage sludge) were examined for mercury content. The mercury content in analysed alternative fuels ranged from 0.4 to 92.0 µg Hg/MJ, with an average of 17.7 µg Hg/MJ. The fuels with the highest mercury content were RDFs (2.0-79.3 µg Hg/MJ) and sewage sludge (42.3-92.0 µg Hg/MJ). An acceptable amount of RDF added to hard coal which would remain within the emission limits was estimated to be 9-24% of the chemical energy in the blend. For sewage sludge, this amount was estimated to be 5-13%. For brown coal, with a much higher mercury content than hard coal, co-combustion with alternative fuels has a positive effect on reducing mercury emissions. It is possible to meet the mercury emission limits with a 95% contribution of the chemical energy coming from RDF. The blending of various types of waste supported by mild pyrolysis of high-mercury waste allows alternative fuels with relatively low mercury content to be produced. Such fuels may contribute a reduction in mercury emissions from coal-fired power plants in Poland.