Biomass gasification via fast pyrolysis

Fast pyrolysis is the thermal degradation of biomass, by rapid heating of small particles in the absence of oxygen. The products obtained are permanent gas, condensable vapours and char. Experiments for 16 different biomass materials have shown that over 95% of the inorganic elements originally present in the biomass, are retained in the char. The absence of minerals in the gases and vapour, and also in the pyrolysis-oil that is obtained upon condensation, makes these product streams attractive as fuel for gasification. Three systems for biomass gasification via fast pyrolysis have been evaluated. The first system is a directly coupled system, where the pyrolysis gases and vapours are partially oxidized (gasified) immediately after they are generated. By applying a dedicated catalyst, a virtually tar free gas suitable for heat and/or power generation can be produced. In a second system pyrolysis oil has been gasified in an autothermal catalytic reformer (7 kW). The third system considered was a pilot scale entrained flow gasifier (400 kW). Both systems were used to demonstrate the production of syngas, suitable for subsequent production of fuels and chemicals, from pyrolysis oil. Theoretical modelling of all three systems has been carried out as well, in order to estimate the optimal product yields for each of them, and to show that high overall efficiencies can be achieved

Valorization of Eucalyptus, Giant Reed Arundo, Fiber Sorghum, and Sugarcane Bagasse via Fast Pyrolysis and Subsequent Bio-Oil Gasification

[Image: see text] Fast pyrolysis of giant reed Arundo (Arundo donax), fiber sorghum (Sorghum bicolor L.Moench), eucalyptus (Eucalyptus spp.), and sugarcane bagasse (Saccharum officinarum) was studied in bench-scale bubbling fluidized bed reactor. Product yields were determined, and detailed physicochemical characterization for produced fast pyrolysis bio-oils (FPBOs) was carried out. The highest organic liquid yield (dry basis) was observed with sugarcane bagasse (59–62 wt %), followed by eucalyptus (49–53 wt %), giant reed Arundo (39 wt %), and fiber sorghum (34–42 wt %). After the pyrolysis experiments, produced FPBOs were gasified in an oxygen-blown autothermal catalytic reforming system for the produced synthesis gas. The gasifier consists of a partial oxidation zone where the FPBO is gasified, and the raw syngas is then reformed over a fixed bed steam-reforming catalyst in the reforming zone. The gas production (∼1.7 Nm(3)/kg FPBO) and composition (H(2) ∼ 50 vol %, CO 20–25 vol %, and CO(2) 25–30 vol %) were similar for all FPBOs tested. These results show that the combination of fast pyrolysis with subsequent gasification provides a technically feasible and feedstock flexible solution for the production of synthesis gas

Evaluation of Analysis Methods for Formaldehyde, Acetaldehyde, and Furfural from Fast Pyrolysis Bio-oil

Fast pyrolysis bio-oil (FPBO), a second-generation liquid bioenergy carrier, is currently entering the market. FPBO is produced from biomass through the fast pyrolysis process and contains a large number of constituents, of which a significant part is still unknown. Various analytical methods have been systematically developed and validated for FPBO in the past; however, reliable methods for characterization of acetaldehyde, formaldehyde, and furfural are still lacking. In this work, different analysis methods with (HS-GC/ECD, HPLC, UV/Vis) and without derivatization (GC/MSD, HPLC) for the characterization of these components were evaluated. Five FPBO samples were used, covering a range of biomass materials (pine wood, miscanthus, and bark), storage conditions (freezer and room temperature), and after treatments (none, filtration, and vacuum evaporation). There was no difference among the methods for the acetaldehyde analysis. A significant difference among the methods for the determination of formaldehyde and furfural was observed. Thus, more data on the accuracy of the methods are required. The precision of all methods was below 10% with the exception of the HPLC analysis of acetaldehyde with an RSD of 14%. The concentration of acetaldehyde in the FPBO produced from the three different biomasses and stored in a freezer after production ranged from 0.24 to 0.60 wt %. Storage at room temperature and vacuum evaporation both decreased significantly the acetaldehyde concentration. Furfural concentrations ranged from 0.11 to 0.36 wt % for the five samples. Storage and after treatment affected the furfural concentration but to a lesser extent than for acetaldehyde. Storage at room temperature decreased formaldehyde similarly to acetaldehyde; however, after vacuum-evaporation the concentration of formaldehyde did not change. Thus, the analysis results indicated that in FPBO the equilibrium of formaldehyde and methylene glycol is almost completely on the methylene glycol side, as in aqueous solutions. All three methods employed here actually measure the sum of free formaldehyde and methylene glycol (FAMG)

Fate of minerals in the fast pyrolysis process

The distribution of minerals between the products of biomass fast pyrolysis is important with respect to the sustainability of the chain as well as for downstream applications. In case biomass residues from agricultural origin are for example used for renewable energy production, it is important the nutritional value of the minerals can be recovered and recycled to the original environment. For most pyrolysis oil applications it is disadvantageous if high mineral concentrations are present in the product. This work investigates the influence of the biomass composition and the pyrolysis process conditions on the distribution of minerals between the products using three pyrolysis setups. Two existing plants, at 5 and 200 kg/h are representative of a full scale pyrolysis plant, while a small, 0.5 kg/h setup has been built specifically to recover all product from the process for analysis. Preliminary results with the 5 and 200 kg/h setup show the non-metal elements (S, P) are transferred to a large extent to the liquid product. The concentration of alkali (Na, K) and earth alkali metals (Ca, Mg) is on average 3% of the concentration found in the original biomass

Techno-economic feasibility of a sunflower husk fast pyrolysis value chain for the production of advanced biofuels

Biofuels are required to reach the target set out by the European Commission’s Transport mandate in the RED II (Renewable Energy Directive) for 2020 – 2030. To avoid indirect land use change, waste biomass resources such as sunflower husks can be used for advanced biofuel production. A process simulation and technoeconomic assessment of three fast pyrolysis plant scenarios were conducted. The nature of the waste feedstock has an effect on the value chain configuration, fast pyrolysis, and upgrading process design. Considering the difficulties with the transport and storage of biogenic waste due to low bulk density or hazardous and pathogenic content in case of transporting untreated sunflower husks, it is recommended to use a hub-and-spoke type of decentralized value chain configuration. The fast pyrolysis plants are located close to the feedstock, and the fast pyrolysis bio-oil (FPBO) is transported to a single upgrading facility, colocated at an existing refinery. The upgraded FPBO is then cofed into an FCC (fluidized catalyst cracker), where partially green biofuels such as gasoline and diesel are produced. For the fast pyrolysis process design, Scenario 2, treating 10 t/h of dry biomass with electricity and steam as coproducts, has the most favorable economic results with a total capital investment (TCI) of 78 million Euro and operating expenses (OPEX) of 6 million Euro

Autothermal catalytic reforming of pine-wood-derived fast pyrolysis oil in a 1.5 kg/h pilot installation: performance of monolithic catalysts

The autothermal catalytic reforming of pyrolysis oil for the production of syngas has been studied in a 1.5 kg/h pilot unit. The influence of the feed ratio's air-fuel-steam and the catalyst amount on the product gas quality were determined. While using a combination of nickel and platinum group metal (PGM) catalysts in monolithic form, a nearly tar- and methane-free product gas could be produced. The maximum syngas yield was obtained at an equivalence ratio of 0.36 and a space time of 1.3 s. These conditions resulted in the production of 47 mol syngas per kg of pyrolysis oil, which corresponds to 97% of the theoretical maximum. The total syngas production decreased at lower equivalence ratios primarily due to increased formation of carbonaceous solids. Incomplete conversion of methane at lower equivalence ratios had a smaller impact on the syngas production. Decreasing the space time to 0.7 s increased both the methane and tar concentrations in the product gas. Tar concentrations remained below 6 mg/Nm(3) in all experiments, showing the tar conversion activity of the catalyst combination to be very good. The progress of the methane steam reforming over the individual catalysts was followed by gas sampling upstream from, in-between, and downstream from the catalysts. It appeared that, in the lower temperature range (780-880 degrees C), the methane reforming activity of the PGM catalyst is higher than that of the nickel catalysts. Above 880 degrees C, however, the reforming activity is quite similar. In conclusion, the route from pyrolysis oil to syngas via autothermal catalytic reforming, and without using any external energy sources, seems attractive

Staged biomass gasification by autothermal catalytic reforming of fast pyrolysis vapors

A novel staged gasification process aiming to produce heat and power from biomass residue materials has been investigated. The process comprises a fast pyrolysis reactor, coupled with an autothermal catalytic reformer to convert the pyrolysis vapors into a clean fuel gas. Because of the relatively low temperature in the first stage, inorganic contaminants are retained in the fast pyrolysis char byproduct, enabling the use of catalysts in the second stage to produce a virtual tar free product gas. The char byproduct is combusted in the pyrolysis system at moderate temperature, thus preventing potential ash-melt problems. The influence of the air-fuel ratio and mixing behavior, the catalyst composition, and the biomass composition on the process performance were determined using a 1−5 kg/h experimental setup. Six biomass materials ranging from clean wood to sewage sludge were converted without any operational problems. Tar concentrations below 10 mg/Nm3 could be obtained, which is sufficiently low for direct utilization in a gas engine. The hydrocarbon reforming efficiency appeared uniform, irrespective of the biomass type. However, the overall cold gas efficiency did depend on biomass type, with a maximum of 65% for clean wood, and 55% for the residual biomass materials. The overall energetic efficiency is determined primarily by the degree of char production in the pyrolysis stage