Biomass Syngas Research Articles

Study on the Methanol Catalytic Synthesis from Biomass Syngas

In order to provide the scientific and practical basis to the industrial test of methanol catalytic synthesis from cornstalk syngas, the systemic research about the reaction conditions of methanol catalytic synthesis over a domestic Cu-based catalyst C301 was carried out in a tubular-flow integral and isothermal reactor. The reaction temperature, the cornstalk syngas proportion and the entrance syngas flow rate were optimized under the reaction pressure of 5MPa and the credible results were obtained.

An experimental and kinetic modeling study of n-octane and 2-methylheptane in an opposed-flow diffusion flame

Fischer–Tropsch (FT) fuels derived from biomass syngas are renewable fuels that can replace conventional petroleum fuels in jet engine and diesel engine applications. FT fuels typically contain a high concentration of lightly methylated iso-alkanes, whereas petroleum derived jet and diesel fuels contain large fractions of n-alkanes, cycloalkanes, and aromatics plus some lightly methylated iso-alkanes. In order to better understand the combustion characteristics of FT and petroleum fuels, this study presents new experimental data for 2-methylheptane and n-octane in an opposed-flow diffusion flame. The high temperature oxidation of 2 -methylheptane and n-octane has been modeled using an extended transport database and a reaction mechanism consisting of 3401 reactions involving 714 species. The proposed model shows good qualitative and quantitative agreement with the experimental data. The measured and predicted concentrations of 1-alkenes and ethylene are higher in the n-octane flame, while the concentrations of iso-alkenes (especially iso-butene) and propene are higher in the 2-methylheptane flame. The proposed chemical kinetic model is used to delineate the reactions pathways leading to these observed differences in product species concentrations. An uncertainty analysis was conducted to assess experimental and modeling uncertainties. The results indicate that the simulations are sensitive to the transport parameters used to calculate fuel diffusion.

Regeneration of Sulfur Deactivated Ni-Based Biomass Syngas Cleaning Catalysts

Nickel-based catalysts have been widely tested for reforming undesired tar and methane from hot biomass-derived syngas. However, nickel catalysts readily deactivate through the adsorption of sulfur compounds in the syngas. We report a new regeneration process that can effectively regenerate sulfur-poisoned Ni reforming catalysts. This process consists of four sequential treatments: (1) controlled oxidation at 750 °C in 1% O2, (2) decomposition at 900 °C in inert gas, (3) reduction at 900 °C in 2% H2, and (4) reaction at 900 °C under reforming condition. This 4-step regeneration process might have advantages over the conventional steam regeneration process.

Experimental and kinetic study of the NO-reduction by tar formed from biomass gasification, using benzene as a tar model component

The present work studies the combustion of biomass syngas to characterize the NO-reduction by tar, benzene being selected as the representative model tar component. Experiments were carried out in a tubular flow reactor at atmospheric pressure and at different operating conditions i.e. an equivalence ratio of 0.5 to 2.5, temperatures between 1173 K and 1673 K and a reaction residence time of 50 to 100 ms. Kinetic parameters were determined from the experimental results. A simplified scheme of NO-reduction by benzene was presented and the effects of operating variables were concluded. The NO conversion is favored by an oxygen-rich condition, and the reduction efficiency falls with the rise of equivalence ratio, especially in the range of 0.5–1.0. Although high temperature enhances the reduction reactions, soot formation at high temperatures (1573 K, 1673 K) will seriously hinder the reduction of NO, which should be prevented. The ideal temperature is about 1473 K. 50 ms is found to be an insufficient residence time for the reduction. An increased contact time is of higher benefit at 1673 K where the heterogeneous reactions between NO and graphitized heavy hydrocarbons have a lower reaction rate. High pre-exponential factors and low activation energies are achieved under oxygen-rich conditions.

Computer simulation of a biomass gasification-solid oxide fuel cell power system using Aspen Plus

Abstract The operation and performance of a SOFC (solid oxide fuel cell) stack on biomass syn-gas from a biomass gasification CHP (combined heat and power) plant is investigated. The objective of this work is to develop a model of a biomass-SOFC system capable of predicting performance under diverse operating conditions. The tubular SOFC technology is selected. The SOFC stack model, equilibrium type based on Gibbs free energy minimisation, is developed using Aspen Plus. The model performs heat and mass balances and considers ohmic, activation and concentration losses for the voltage calculation. The model is validated against data available in the literature for operation on natural gas. Operating parameters are varied; parameters such as fuel utilisation factor ( U f ), current density ( j ) and STCR (steam to carbon ratio) have significant influence. The results indicate that there must be a trade-off between voltage, efficiency and power with respect to j and the stack should be operated at low STCR and high U f . Operation on biomass syn-gas is compared to natural gas operation and as expected performance degrades. The realistic design operating conditions with regard to performance are identified. High efficiencies are predicted making these systems very attractive.

Simulation of a Tubular Solid Oxide Fuel Cell Stack Operating on Biomass Syngas Using Aspen Plus

A tubular solid oxide fuel cell stack was modeled, and its operation on biomass syngas was investigated. The objective of this work was to develop a computer simulation model of a biomass gasification–solid oxide fuel cell system capable of predicting performance under various operating conditions and using diverse fuels. The stack was modeled using Aspen Plus and considers ohmic, activation, and concentration losses. It was validated against published data for operation on natural gas. Operating parameters such as fuel and air utilization factor ( and , respectively), current density , and steam to carbon ratio (STCR) were varied and had significant influence. The model was run on wood and miscanthus syngas. The results indicated that there must be a trade-off between voltage, efficiency, and power with respect to and that the stack should be operated at a low STCR and a high . Also, the stack should be operated at a of . Operation on biomass syngas was compared to natural gas operation and, as expected, performance degraded. Better stack performance was observed for wood syngas compared to miscanthus syngas. High efficiencies were predicted making these systems very promising.

Simulation of a Tubular Solid Oxide Fuel Cell Stack Operating on Biomass Syn-gas using Aspen Plus

A tubular solid oxide fuel cell (SOFC) stack is modelled and its operation on biomass syn-gas is investigated. The objective of this work is to develop a computer simulation model of a biomass gasification-SOFC (BG-SOFC) system capable of predicting performance under various operating conditions and using diverse fuels. The stack is modelled using Aspen Plus and considers ohmic, activation and concentration losses. It is validated against published data for operation on natural gas. Operating parameters such as fuel and air utilisation factor (Uf and Ua), current density (j) and steam to carbon ratio (STCR) are varied and have significant influence. The model is run on wood and miscanthus syn-gas. The results indicate that there must be a trade-off between voltage, efficiency and power with respect to j and the stack should be operated at low STCR and high Uf. High efficiencies are predicted making these systems very promising.

Performance of a Ni/Al 2O 3 cermet-supported tubular solid oxide fuel cell operating with biomass-based syngas through supercritical water

Thermochemical gasification of biomass through the supercritical water gasification (SCWG) has high gasification efficiency at lower temperatures and can deal directly with wet biomass without drying. Besides, solid oxide fuel cells (SOFCs) appear to be an important technology in the future as they can operate at a high efficiency. Therefore, the combination of biomass gasification through supercritical water with SOFC represents one of the most potential applications for highly efficient utilization of biomass. In this paper, the composition of syngas was adopted for SOFC operation based on the thermochemical gasification of biomass through the supercritical water. The volume fraction of hydrogen, carbon monoxide, methane, and carbon dioxide was 42%, 1%, 13%, 44% respectively. A Ni/Al 2O 3 cermet-supported tubular SOFC single cell assembled by thermal spray was adopted in this study. The influence of biomass syngas on the performance of single cell was investigated.

The use of biomass syngas in IC engines and CCGT plants: A comparative analysis

This paper studies the use of biomass syngas, obtained from pyrolysis or gasification, in traditional energy-production systems, specifically internal combustion (IC) engines and combined cycle gas turbine (CCGT) plants. The biomass conversion stage has been simulated by means of a gas–solid thermodynamic model. The IC and CCGT plant configurations were optimised to maximise heat and power production. Several types of biomass feedstock were studied to assess their potential for energy production and their effect on the environment. This system was also compared with the coupling between biomass gasification and fuel cells.

Simulation of Methanol Production from Biomass Gasification in Interconnected Fluidized Beds

Simulation of methanol synthesis via H2-rich biomass-derived syngas from biomass gasification in interconnected fluidized beds is carried out, using Aspen Plus software to establish this model. In the case of CaCO3 catalysis, the effects of operating parameters, including gasification temperature and pressure, steam /biomass ratio (S/B), and liquefaction temperature and pressure, on the methanol yield are analyzed. The results are as follows: In the case of CaCO3 catalysis, biomass steam gasification can obtain 82.13% hydrogen-rich gas and when the Cu-based catalyst in China which is composed of 58.1% CuO + 30.06% Al2O3 + 31.7% ZnO + 4.0% H2O is adopted as the methanol synthesis catalyst; the gasification temperature is suggested to be controlled at about 750 °C in the interconnected fluidized beds biomass gasification system with the purpose of methanol production. Furthermore, the gasification pressure is proposed to approach to the ambient pressure and the S/B ratio of 0.4−0.5 operates better. On the optimal operating condition, the maximum of 12.19 mol/(kg biomass (daf)) of methanol yield may be obtained. The research provides useful results for the further study of biomass gasification and methanol synthesis from biomass syngas.

Effect of micropores diffusion on kinetics of CH 4 decomposition over a wood-derived carbon catalyst

In order to optimise hydrogen production from biomass gasification, catalytic conversion of methane contained in a surrogate biomass syngas (CH 4 14%; CO 19%; CO 2 14%; H 2 16%; H 2O 30%; N 2 7%) is investigated over a fixed bed of porous wood char as a function of temperature (800–1000 °C) and space time (1.6–6.2 min g L −1). Determination of Thiele modulus evidences a change of kinetic regime from chemically- to diffusion-controlled when the temperature increases; this finding is particularly relevant when porous chars having an average pore width of 1 nm are used as catalysts. Mass diffusion transfers are accounted for by a model introducing an internal effectiveness factor. Knudsen diffusion in micropores is shown to limit the conversion rate of methane per unit mass of catalyst, and explains why such a rate is not proportional to the BET surface area, especially when the latter is higher than typically 300 m 2/g. It is concluded that diffusion limitations in micropores should be taken into account, otherwise underestimated activation energy and intrinsic kinetic constant are obtained in some experimental conditions.

Analytical modeling of polarizations in a solid oxide fuel cell using biomass syngas product as fuel

An analytical model is developed to study fuel type effect on polarizations and performance of SOFC. We consider especially two types of fuel: pure hydrogen and syngas (mixture of H 2 and CO) produced by biomass gasification. The proposed model is based on simultaneous direct oxidation of H 2 and CO at the anode side and uses the dusty-gas model with appropriate diffusion coefficient (binary or mixture coefficient in porous material) to evaluate the concentration polarization and the Butler–Volmer equation to calculate the activation polarization when ohmic polarization is expressed by the well known Ohm’s law. Results analysis show that a fraction of CO of about 24% in syngas improves the performance of SOFC by 23% compared to that obtained by pure H 2.

Process analysis of a molten carbonate fuel cell power plant fed with a biomass syngas

The coupling of renewable energy sources and innovative power generation technologies is of topical interest to meet demands for increased power generation and cleaner environmental performance. Accordingly, biomass is receiving considerable attention as a partial substitute for fossil fuels, as it is more environmentally friendly and provides a profitable way of disposing of waste. In addition, fuel cells are perceived as most promising electrical power generation systems. Today, many plants combining these two concepts are under study; they differ in terms of biomass type and/or power plant configuration. Even if the general feasibility of such applications has been demonstrated, there are still many associated problems to be resolved. This study examines a plant configuration based on a molten carbonate fuel cell (MCFC) and a recirculated fluidized-bed reactor which has been applied to the thermal conversion of many types of biomass. Process analysis is conducted by simulating the entire plant using a commercial code. In particular, an energy assessment is studied by taking account of the energy requirements of auxiliary equipment and the possibility of utilizing the exhaust gases for cogeneration.

Conversion of Biomass Syngas to DME Using a Microchannel Reactor

The capability of a microchannel reactor for direct synthesis of dimethyl ether (DME) from biomass syngas was explored. The reactor was operated in conjunction with a hybrid catalyst system consisting of methanol synthesis and dehydration catalysts, and the influence of reaction parameters on syngas conversion was investigated. The activities of different dehydration catalysts were compared under DME synthesis conditions. Reaction temperature and pressure exhibited similar positive effects on DME formation. A catalytic stability test of the hybrid catalyst system was performed for 880 h, during which CO conversion only decreased from 88% to 81%. In the microchannel reactor, the catalyst deactivation rate appeared to be much slower than in a tubular fixed-bed reactor tested for comparison. Test results also indicated that the dehydration reaction rate and the water depletion rate via a water-gas-shift reaction should be compatible to achieve high selectivity to DME. Using the microchannel reactor, it was p...