The pyrolysis of end-of-life wind turbine blades under different atmospheres and their effects on the recovered glass fibers

Abstract

Pyrolysis is a promising technology to reclaim glass fibers from end-of-life wind turbine blades (WTBs), while the pyrolysis atmosphere has significant effects on the depolymerization of WTBs and the mechanical properties of recovered fibers. In this study, the pyrolysis performance of commercial end-of-life WTBs under different atmospheres was investigated as well as their effects on the mechanical properties of recovered fibers. The results showed that the pyrolysis gas in N2 atmosphere mainly consisted of CO2, CH4, and CO, and its calorific value was 22.53 MJ/Nm3. Various phenolic compounds were also recovered in the pyrolysis oil. After the post-oxidation of pyrolysis solid products, clean glass fibers could be reclaimed successfully. H2O was an effective gasifying agent in accelerating the decomposition of epoxy resins at 500 °C, which increased the yields of pyrolysis gas and phenolic products while inhibited the formation of char. Besides, the reactivity of residual char was improved, thereby promoting their oxidization in the post-oxidization process but causing the thermal-oxidative diffusion of surface flaws, which slightly degraded the tensile strength of recovered fibers by 5.97%. CO2 suppressed the cracking of epoxy resins and contributed to the simultaneous accumulation of uncracked resins and pyrolysis char, which then aggravated the diffusion of surface flaws by thermal oxidization and uneven heating in the post-oxidation, thereby degrading the tensile strengths of recovered fibers by 16.02%.