Partitioning of Mercury and Other Trace Elements From Coal and Waste-Derived Fuels During Fluidised Bed Pyrolysis

Abstract

The potential releases of toxic trace elements such as mercury, lead and arsenic call for emission control during fluidised bed (FB) combustion, pyrolysis or gasification of waste-derived fuels and fossil fuels. Control measures for sulphur oxides, nitrogen oxides and particulates effectively remove many other pollutants from the exhaust gases as well, but mercury and several other trace elements are already problematic and this situation will only worsen with time. Besides the effect of temperature, gas atmosphere and halogens, the presence of other species, for example metal oxides, have an effect on under which conditions and in what form trace elements are released from fuels. Understanding the events of trace elements release from solid fuels during the pyrolysis or char combustion stage will provide a key to manipulating their partitioning and controlling their emissions. Pyrolysis experiments were made with coal, sewage sludge and automotive shredder residue (ASR) in a two-stage fluidised bed combustion (FBC) facility. An Ontario Hydro measurement train plus an additional sampling system were used to measure mercury and around fifteen other trace elements in the gases, and also char samples were taken and analysed. Results from these experiments are presented. An issue that is addressed explicitely is the bed material, which may be contaminated with significant amounts of toxic trace elements.

Conversion of waste to sustainable aviation fuel via Fischer–Tropsch synthesis: Front‐end design decisions

“…Non‐CHNSO element concentrations in biomass, 150 biomass ash, 151,152 sewage sludges, 153,154 and MSW‐based products 155–157 and ashes 158 are available. However, a part of these components is separated during liquefaction in the gas phase, in the pyrolysis or HTL char or in the HTL aqueous phase 159–162 . To determine which elements need to be considered in gas cleaning after gasification of oils produced from biomass waste and other organic waste, a literature survey was conducted to compile literature available information on the contained non‐CHNSO elements and their concentration.…”

“…However, a part of these components is separated during liquefaction in the gas phase, in the pyrolysis or HTL char or in the HTL aqueous phase. [159][160][161][162] To determine which elements need to be considered in gas cleaning after gasification of oils produced from biomass waste and other organic waste, a literature survey was conducted to compile literature available information on the contained non-CHNSO elements and their concentration. The literature on non-CHNSO element concentration in bio-and waste oils is quite scattered and most references conducted only analyses for specific elements instead of a full characterization of all non-CHNSO element concentrations.…”