Influence of moisture contents on the fast pyrolysis of trommel fines in a bubbling fluidized bed reactor

In this study, the effect of moisture contents [2.69 wt% (bone-dry), 5 wt% and 10 wt%] on product yields and process conversion efficiency during fast pyrolysis of a pre-treated trommel fines feedstock was investigated at 500 °C. Experiments were carried out using a 300 g h −1 bubbling fluidised bed rig. Yields of organic liquids ranged from 15.2 to 19.6 wt% of feedstock, which decreased with increasing moisture content. Hence, the bone-dry feedstock gave the maximum yield and consequently the highest process conversion efficiency of 43%. Increased moisture content also led to increase formation of unidentified gas products, indicating increased conversion of organic liquids. Due to the high ash content of the feedstocks, about 52 wt% solid residues, containing around 82% ash was recovered in the char pot in each case. Hence, to maximize oil yields during fast pyrolysis, trommel fines would require extensive drying to remove the original 46 wt% moisture as well as reducing the ash content considerably. XRF analysis of the ash in the feedstock and solid residues showed that the main elements present included Ca, Si, Fe, Pb, K, Cl and Al. Apart from the presence of Pb (which may be from the glass contents of the feedstock), the solid residues could be used for land reclamation or co-incinerated at cement kilns for cement manufacture

Biomass thermal treatment: energy recovery, environmentalcompatibility and determination of external costs

Climate change is the primary worldwide issue of the twenty-first century, as it threatens not only natural ecosystems but many national economies as well. Since the major contributor to climate change is the emission of greenhouse gases, switching to renewable and clean sources of energy production would result in the most immediate benefit. And one of the main energy sources in this category is biomass. In this work some preliminary evaluations are reported concerning the environmental effects, as well as the related external costs, from both local and global points of view, of a proposed biomass plant to be constructed in Piedmont (northern Italy). The obtained results indicate that, from the local point of view, the environmental effectiveness of the plant is related to the percentage of the thermal energy that can be transferred from the district heating network to the local domestic boilers (with subsequent replacement of the related emissions). From a global point of view, and in particular concerning greenhouse gases (GHG), the carbon dioxide produced from biomass combustion would be balanced by the quantity that is absorbed by the plants during their lifetimes. Hence by operating a biomass plant capable of producing 20 thermal MW, we can remove carbon dioxide emissions equal to about 38.368 ton/year, and avoid external costs of 728.992 €/year, if at least 30% of the produced heat can be transferred to the district heating networ

Evaluation of Environmental Compatibility for a Biomass Plant

The aim of this work was to determine the local compatibility of a biomass plant to be constructed in a small town located in Piedmont, northern Italy, to produce both electricity and heat. In order to study both the local critical impacts (on air quality) and the overall environmental benefits (decrease of GHG generation), we performed an evaluation of the emissive flow modification for the hypothesis of activating the biomass plant in the municipal area, by considering introduced and eliminated pollutant loads. The evaluation was conducted using the tools of mass and energy balances, evaluating the pollution fluxes with an external costs methodology and pollutant dispersion models. These conclusions, numerically defined for the specific situation studied, can be considered to be fairly representative as a methodological approach to studying the effects of biomass energy plant