Biomass Syngas Research Articles

Effects of Hydrogen Addition on the Thermal Performance and Emissions of Biomass Syngas Combustion in a Horizontal Boiler

Effects of Hydrogen Addition on the Thermal Performance and Emissions of Biomass Syngas Combustion in a Horizontal Boiler

The impact of H2 and O2 enrichment on the laminar combustion characteristics of biomass syngas flame

This article investigates the impact of H2 and O2 enrichment on the laminar burning velocity (SL) of syngas in a constant-volume combustion chamber. By analyzing changes in both chemical and thermal effects, it examines the impact of variations in H2 and O2 content on the SL independently. Furthermore, this article investigates the pressure variations of spherical expanding flames, flame instability, and the formation of mixed fuel NO. Results show increased H2 and O2 content enhance SL, with O2 addition leading to a linear increase. H2 affects thermal-diffusive instability differently in lean and rich fuel regions, while increasing O2 content mitigates it. The synergistic influence of flame thickness and thermal expansion ratio amplifies fluid dynamic instability with higher H2 and O2 content. O2 addition is more effective in promoting the rate of production for thermal NO and H2 addition is more effective in promoting the rate of production for non-thermal NO.

Thermodynamic and kinetic analysis on the biomass syngas fueled chemical looping hydrogen generation process in fixed bed reactor

Because of its simple structure and easy operation, the fixed bed reactor is widely used in the chemical looping process to assess the performance of oxygen carriers (OC) or to evaluate new chemical looping technologies. However, the systematic investigation of the redox behavior and temperature evolution during the chemical looping hydrogen generation (CLHG) process in the fixed bed reactor under different conditions, which is crucial for process optimization and reactor design, has received less attention. In the present work, the redox characteristics of the CLHG process with biomass syngas as the fuel in a fixed bed reactor were investigated and analyzed from a perspective of thermodynamics and kinetics. Results showed that high redox temperature (>800 °C) favors the fuel conversion due to the improved reaction kinetics and favorable thermodynamics. A space velocity in the range of 0.12–0.5 s−1 and superficial velocity of 0.008–0.075 m/s can provide enough reaction time meanwhile enhance the external diffusion of fuel gas, achieving high reduction degree of OC and further high H2 yield (3.4 mmol/g Fe2O3) and high H2 energy efficiency (45 %). Moreover, a violent OC bed temperature rise (100 °C) was observed in the air oxidization stage, which can be mitigated by diluting the Fe2O3 content and decreasing the air flow rate. Finally, the reaction front and flow front moving behavior were discussed in detail for a better understanding of the CLHG process.

Evaluation of a novel nickel ceramic filter prepared by urea precipitation method for removal of tars from biomass syngas using naphthalene as tar model compound

Gasification has been shown to be an effective thermal conversion process for waste biomass in order to create fuel, specialty chemicals, and hydrogen. Gasification is likely to take on a major role in the near future in the burgeoning hydrogen economy. In order to improve the commercial viability of gasification, catalytic tar reforming has come to the forefront as one of the most promising methods of reducing the tar content that has been detrimental to downstream equipment in the process. The use of catalytic ceramic filters has presented promising potential for this application that can serve dual role of tar and particulate removal. In this study, a nickel-based ceramic filter has been prepared using urea vacuum impregnation technique and evaluated for tar removal efficiencies. The urea technique was more effective than traditional impregnation techniques at uniformly dispersing nickel across the surface of the ceramic filter, driving the nickel particles to penetrate the pores of the support, thus aiding in improved tar removal capabilities. Through steam reforming studies using a naphthalene simulant tar molecule, the 15 wt% nickel filter was able to reduce the naphthalene content by 97% at temperature of 750 °C over 2 h. An activation energy of 126.4 kJmol was achieved for steam reforming using the urea vacuum impregnated catalytic filter compared to 136.4 kJmol using the incipient wetness impregnated filter.

The Influence of Co-Firing Coal with Biomass Syngas on the Thermodynamic Parameters of a Boiler

Biomass syngas can be considered as a supplementary fuel to partially substitute coal, which is beneficial to CO2 emission reduction. For the case study, the influences of co-firing typical biomass syngas (gasification from palm, straw, and wood) with coal on the thermodynamic parameters of a 300 MW tangentially fired boiler are evaluated through a thermal calculation based on the principles of mass conservation, heat conservation, and heat transfer. The effects of boiler loads, biomass syngas species, and consumption rates are discussed. The results show that the introduction of biomass syngas weakens the radiative characteristics of the flame and reduces the furnace exit flue-gas temperature. As 3 × 104 m3 h−1 of wood syngas is introduced, the decrement of thermal efficiency reaches 0.4%, while that of the coal consumption rate is 5.1%. The retrofitting of the boiler was not necessary and the corrosion of the low-temperature heating surface did not appear. The CO2 annual emission reduction could achieve 0.001 to 0.095 million tons for palm syngas, 0.005 to 0.069 million tons for straw syngas, and 0.013 to 0.107 million tons for wood syngas with increasing biomass syngas consumption rates under the full load. Moreover, the main thermodynamic parameters changed more significantly under the low loads.

Experimental study on effect of temperature and equivalence ratio on biomass syngas generation for fluidized bed gasifier techniques

ABSTRACT This paper presents a comparative study of selected woody biomass for the potential of fuel gas generation that can be used for heat and power generation using a Fluidized Bed Gasifier (FBG). The characteristics of produced energy gas using the thermochemical Bubbling Fluidized Gasification Technique for selected woody biomass feedstock materials were studied for selected temperatures. Initially, the CFD analysis has been implemented to determine the feasible equivalence ratio (ER) for the selected biomasses. Using CFD ANSYS solver studied gas-solid interaction and gasification process inside a fluidized bed biomass gasifier. Experimental investigations were conducted on the FBG reactor for a feeding rate of 10 kg/hr of biomass materials. Experimental investigations were conducted on the FBG reactor for a feeding rate of 10 kg/hr of biomass materials. The work characteristics of produced gas were investigated by the experimental process for bagasse, groundnut shell, and wooden shavings as feedstock biomass materials for the gasification bed temperature at 500ºC, 550ºC, and 600ºC and Equivalence Ratio (ER) ratio of 0.30. Air was employed as a gasifying agent, and sand with limestone was used as the fluidized bed material. The results show that the fluidized bed has higher temperatures of 600ºC and above, generating higher Calorific Value (CV) syngas. Among all three feedstocks, groundnut shells produced gas HHV of 4.21 MJ/m3. The lowest HHV for bagasse at 500ºC of 3.01 MJ/m3. The effect of bed temperature on Carbon Conversion Efficiency (CCE) shows maximum CCE for bagasse is 60.86%, noted at 550ºC, and the minimum for wooden shaving at 550ºC is 57.69%.

Review of Porous Ceramics for Hot Gas Cleanup of Biomass Syngas Using Catalytic Ceramic Filters to Produce Green Hydrogen/Fuels/Chemicals

Biomass gasification is one of the most promising routes to produce green hydrogen, power, fuels, and chemicals, which has drawn much attention as the world moves away from fossil fuels. Syngas produced from gasification needs to go through an essential gas cleanup step for the removal of tars and particulates for further processing, which is one of the cost-inducing steps. Existing hot gas cleanup strategies involve the particulate removal step followed by catalytic tar reforming, which could be integrated into a single unit operation using porous ceramics owing to their advantages including high-temperature resistance, high corrosion resistance, flexibility, and robust mechanical integrity. Ceramic filters have proven to be effective at filtering particulates from hot gas streams in various applications including combustion, incineration, gasification, and pyrolysis. These materials have also been evaluated and used to an extent as catalyst support to remove contaminants such as nitrogen oxides (NOx), volatile organic compounds (VOC), and in particular, tars, however, the use of these ceramic materials to remove both tars and particulates in one unit has not received much attention, although it has a promising potential to be a cost-effective hot gas cleanup strategy. Thus, this review presents the ability of catalytic ceramic filters to boost energy efficiency by converting unwanted byproducts while simultaneously eliminating PM in a single unit and is shown to be valuable in industrial processes across the board. This article presents a comprehensive and systematic overview and current state of knowledge of the use of porous ceramics for catalytic hot gas filtration applications with an emphasis on biomass syngas cleanup. In addition, a similar strategy for other applications such as combustion exhaust streams is presented. Prospects and challenges of taking this approach, and the necessary research and development to advance the novel use of reactive ceramic filters within biomass-fed thermal systems are presented. Major challenges include the low surface area of the ceramic filter media and high-pressure drop across the filter media, which can be overcome by wash coating or dip coating mechanisms and porosity tailored to meet the requirements. Owing to limited R&D efforts in this area, a systematic approach toward developing these integrated hot gas filtration systems is much needed, which will ultimately contribute to cost-effective green hydrogen production.

Second stage porous media burner for syngas enrichment

The syngas production from hydrocarbons by porous media combustion (or conventional gasification) processes has been intensively and extensively studied due its calorific value and its applications in the energy sector. However, the syngas produced in a first stage gasifier can still have concentrations of light hydrocarbons (e.g., methane) which can be post-processing for further enrichment of hydrogen and carbon monoxide. The present work numerically investigates the performance of a second stage porous media burner to enrich the syngas content, mainly hydrogen and carbon monoxide. A one-dimensional model based on a two-temperature approximation is implemented, based on the PREMIX code, and supported by CHEMKIN and GRI-MECH 3.0 database and routines. From hybrid porous bed reactor experiments, five types of mixtures in the equivalence ratio range between 0.4 and 2.4 are tested: pure methane as baseline, pure Eucalyptus nitens syngas, pure Pinus radiata syngas, and two mixtures of methane with each of the biomass syngas in equal volume quantities, as transition points. The results obtained show that in the enriched syngas, in comparison to the first content after the first stage reactor, the concentrations of hydrogen and carbon monoxide increase, due to the partial oxidation of methane, however part of the hydrogen is consumed in the process. The intermediate species present in methane processing for pure syngas mixtures have broader reaction zones and in lower concentrations compared to the use of pure methane. For equivalence ratios greater than 1.9, pure syngas mixtures show higher conversion efficiencies compared to the baseline. At the equivalence ratio of 2.4, the pure syngas from Eucalyptus nitens and Pinus radiata has an energy return over energy invested (EROI) of 58.27% and 53.95%, respectively, and a maximum hydrogen and carbon monoxide yields of 31.66% and 48.40%, respectively. In the case of the Pinus radiata, the outlet syngas concentrations of the hydrogen and carbon monoxide on dry basis expose an increment about two times in comparison to the initial concentrations.

Production of Substitute Natural Gas Integrated with Allam Cycle for Power Generation

The accumulation of energy from non-programmable renewable sources is a crucial aspect for the energy transition. Using surplus electricity from renewable energy sources, power-to-gas plants allow to produce a substitute natural gas (SNG) that can be injected in the existing infrastructure for large-scale and long-term energy storage, contributing to gas grid decarbonisation. The plant layout, the method used for carbon dioxide capture and the possible cogeneration of electricity can increase the efficiency and convenience of SNG synthesis plants. In this work, a system for the simultaneous production of SNG and electricity starting from biomass and fluctuating electricity from renewables is proposed, using a plant based on the Allam thermodynamic cycle as the power unit. The Allam power cycle uses supercritical CO2 as evolving fluid and is based on the oxycombustion of gaseous fuels, thus greatly simplifying CO2 capture. In the proposed system, oxycombustion is performed using biomass syngas and electrolytic oxygen. The CO2 generated by means of oxycombustion is captured, and it is subsequently used together with renewable hydrogen for the production of SNG through thermochemical methanation. The system is also coupled with a solid oxide electrolyser and a biomass gasifier. The whole plant was analysed from an energy-related point of view. The results show overall plant efficiency of 67.6% on an LHV basis (71.6% on an HHV basis) and the simultaneous production of significant amounts of electricity and of high-calorific-value SNG, whose composition could be compatible with the existing natural gas network.

Thermodynamic and economic performance study of SOFC combined cycle system using biomass and LNG coupled with CO2 recovery

The search for more efficient, energy-saving and cleaner methods of energy utilization is a current research focus. In this study, a novel solid oxide fuel cell (SOFC) combined cycle system fueled by biomass syngas and natural gas is studied, with carbon capture by using liquefied natural gas (LNG) cold energy. In the proposed system, the exhaust from the cathode and anode outlets of SOFC is split to do work instead of the traditional approach of exhaust mixing, thus achieving CO2 capture using LNG cold energy more efficiently. The system is simulated by Aspen Plus software with embedded Fortran. The energy analysis and exergy analysis of the system are performed. The results indicate that under design conditions, the thermal efficiency, electrical efficiency and exergy efficiency of the system are 60.28 %, 66.20 % and 55.59 %, respectively. The amount of carbon capture purity and the mass flow rate of liquid CO2 are 99.35 % and 54.50 kg/h. The largest exergy loss occurs in heat exchangers, which accounts for 35.63 %. In addition, sensitivity analysis of the system is performed and the variation law of thermodynamic and economic performance with parameters is obtained based on the simulation results. This study not only provides a theoretical basis for subsequent research on the way to improve the efficiency of SOFC combined cycle system, but also provides new ideas for the efficient utilization of biomass combined with natural gas.

Experimental and numerical study of the effects of N2 dilution and CH4 addition on the laminar burning characteristics of syngas

The study of combustion characteristics of complex biomass syngas under changing conditions is helpful for its practical utilization. In this paper, the effects of N2 dilution (dilution rates from 0% to 60%) and CH4 addition (mixing ratios from 0% to 20%) on the laminar flame properties of H2/CO/N2 syngas were researched. The laminar burning velocities (LBVs) were obtained by constant volume combustion chamber system. Five common mechanisms were used for numerical simulation using the CHEMKIN software package and the results were compared with the measurement data. The Li mechanism that was well matched with the experimental data was selected for kinetic analysis. The results indicate that the LBVs of H2/CO/N2/air mixtures decrease due to the dilution of N2. The addition of CH4 decreases the LBVs of H2/CO/N2/CH4/air mixtures and the LBVs of fuel-rich mixtures decrease faster. Sensitivity analysis illustrates that R29 is the most important branching reaction affecting LBV in H2/CO/N2/air premixed flame, the net reaction rate of all branched reactions and the mole fraction of H and OH in the mixture decrease due to the increase of N2 content. After adding CH4, the dominant branching reaction becomes R1. Due to the increase of CH4 addition ratio, the concentrations of H and O decrease, but the concentrations of OH and CH3 increase slightly. The chemical effect of adding CH4 increases LBV, but the physical effect decreases LBV. The reduction in the proportion of chemical effect is the reason for the faster reduction of LBV in the fuel-rich region. Finally, the formation of NO was analyzed in detail using the GRI 3.0 mechanism. The results show that N2 dilution reduces the mole fraction of NO, but CH4 addition increases the mole fraction of NO. Pathway analysis shows that N2 dilution and CH4 addition decrease and increase the effect of thermal mechanism on NO generation, respectively.

Ni coarsening and performance attenuation prediction of biomass syngas fueled SOFC by combining multi-physics field modeling and artificial neural network

Ni particle coarsening is an important factor in deteriorating the durability of solid oxide fuel cell (SOFC) operations. In order to investigate the influence of Ni coarsening on SOFC performance, the transient multi-physical field model of SOFC was developed in this paper. The high operating temperature accelerates Ni particle growth and increases the attenuation rate of SOFC current density from 0.23%/kh at 650 °C to 2.6%/kh at 800 °C. The increase in the ratio of steam to carbon also intensifies the Ni particle coarsening process and deteriorates the transient performance of SOFC. Increasing YSZ particle diameter could hinder the growth of Ni particles and slowing down the increase rate of Ni particle diameter. Within the range of preset YSZ diameter dYSZ, increasing dYSZ reduces the attenuation rate and increases the average current density. Improving Ni phase fraction helps to reduce the attenuation rate of current density. Since multi-physical field (MPF) simulation needs long calculation time and it is difficult to achieve fast prediction, artificial neural network (ANN) is trained by the database generated by MPF. The mapping relationship between operating parameters, structural parameters and attenuation indexes is obtained. Finally, the attenuation performance of SOFC is optimized by genetic algorithm (GA) through data-driven method. The absolute average relative errors of all parameters in predicting attenuation rate and average current density are as low as 0.767% and 0.248%, which indicates the reliability of the ANN prediction. After optimization, the maximum current density is 5848 A·m−2 under operating voltage at 0.6 V when the attenuation rate requirement not exceeding 1% is satisfied. The combination of MPF simulation, ANN and GA provides a framework for fast performance prediction and optimization of strong nonlinear system.

Fluidized bed gasification of biomass from plant-assisted bioremediation: Fate of contaminants

Fluidized-bed gasification (FBG) of Phyto-assisted Bioremediation (PABR) biomass is analyzed focusing on the contaminants’ dispersion. Poplar pruning coming from an area contaminated by polychlorinated biphenyls (PCBs) and heavy metals (HM) are considered. The biomass analysis showed relevant contents in HMs, especially Cd and Cr, and no significant PCB content. FBG process was analyzed to: a) track pollutants, b) detect contaminants in the FBG and c) investigate the HMs concentration in the produced streams. The results showed that most of the metals are concentrated in the ashes collected in the bottom of the reactor (Pb, Cd, Cu, Cr), or in the cyclone (B, Na, Mg, Al, K and Fe). Interestingly, metals are also released by the olivine bed (Mg, Fe, Ni and Al) and transported downstream. Consistent fractions of Zn and Fe (also Cu) were detected in the fugitive ashes. As for the Volatile Organic Compounds (VOC) concentration, we noted similarities between PABR and virgin biomass syngas streams. A reduced-scale process was carried out in TGA-DTA to investigate the potential of such technique in reproducing the main features of the FBG process. Comparable results were obtained, thus suggesting its possible application for small-scale preliminary assessment of FBG process.

Numerical Investigation on Cofiring Characteristics of Biomass Syngas and Coal in a 660-MW Tower Boiler

Numerical Investigation on Cofiring Characteristics of Biomass Syngas and Coal in a 660-MW Tower Boiler

Experimental and numerical simulation of effects of CO2/N2 concentration and initial temperature on combustion characteristics of biomass syngas

Biomass syngas is a form of renewable energy with very broad application prospects, and it has different combustion characteristics according to the fuel composition and processing technology of biomass syngas. The influence of combustion composition, diluent and temperature variation on combustion characteristics were studied in this paper. The FFCM-1 mechanism was used to investigate the combustion characteristics of CO/CH4/H2 under varied diluents CO2/N2 and temperature by using spherical expansion flame method and ANSYS CHEMKIN-PRO. The experimental laminar burning velocity was compared with the simulation results of FFCM-1 mechanism. The results reveal that the experimental data are in good agreement with the simulation results, which are somewhat different under the condition of rich fuel. The laminar burning velocity decreases significantly with the increase of diluent CO2/N2, with the effect of diluent CO2 being more significant. The laminar burning velocity increase dramatically with the increase of initial temperature, and the adiabatic flame temperature also decreases with the increase of diluent. The reduction caused by diluent CO2 is much larger than that caused by diluent N2. The change of initial temperature also affects the adiabatic flame temperature, but the range of variation is not as pronounced as that of diluent. Not only was the interaction between the combustion characteristics of CO/CH4/H2 under different diluents and temperature changes explored in this paper, but the influence mechanism was also revealed in depth.

Techno-economic evaluation of a combined biomass gasification-solid oxide fuel cell system for ethanol production via syngas fermentation

Bioethanol is regarded as a high-quality and clean liquid fuel with a renewable production process through bioconversion and chemical synthesis technology. Syngas fermentation route has received increasing attention due to mild reaction conditions and the elimination of expensive pretreatment and enzyme. To improve the economy and energy efficiency of the bioethanol production, a novel combined biomass gasification-syngas fermentation-solid oxide fuel cell system is proposed in this work. The techno-economic assessment is performed by the parametric analysis of the gasification and fermentation process. The sensitivity analysis shows that the dual fluidized bed with woodchips has the highest CO and H2 content, and the ethanol yield can be enhanced by improving the substrate conversion rate. A tentative economic assessment is performed with a total production cost of 430.1 €/t ethanol, revealing the economy of the hybrid gasification-syngas fermentation process. Besides, the problem of syngas distribution and fermenter exhaust recycling is further explored by introducing the SOFC system to realize the cascade utilization of energy. The trade-off between the combined system efficiency, total annual cost, and product price is conducted by multi-objective optimization with the technique for order of preference by similarity to ideal solution (TOPSIS) method. The optimized system can reach the system efficiency of 55%, the minimum total annual cost of 19.9 M€, and the total product price of 64.5 M€. The proposed system could demonstrate the feasibility of bioethanol production via biomass syngas fermentation with a high-efficiency and cost-competitive pathway.

Construction of a transient multi-physics model of solid oxide fuel cell fed by biomass syngas considering the carbon deposition and temperature effect

Carbon deposition is a thorny issue for the SOFC fueled by low carbon hydrocarbons such as biomass syngas. Moreover, long-term large temperature gradients would reduce SOFC durability. Regarding these two issues, a two dimensional transient multi-physical model considering carbon deposition and temperature effect is developed for SOFC in this work. Typically due to the carbon deposition, the SOFC anode porosity decreases from 0.5 to 0.267, and the reaction activity decreases from 1.0 to about 0.45 after running 140 day. Accordingly, the current density decreases by 1.6 % at t = 42 d and 6% at t = 140 d, which indicates the damage of SOFC durability compared to the durability target (1%/1000 h) of commercial SOFC. The maximum temperature difference of the cell is predicted to be about 106 °C. It was found that the carbon deposition and large temperature gradient are closely related to the operating parameters. With the increase of operating voltage from 0.4 V to 0.8 V, the porosity and reaction activity respectively increase by 50% and 55%, and the maximum temperature difference is reduced from 150 °C to 16 °C after running 140 day. The increase of the inlet temperature could improve the overall temperature and decrease the porosity. Besides, the reduction in the ratio of CH4 to H2O helps to suppress carbon deposition, thus to improving the performance.

Numerical Simulation of Flash Reduction of Iron Ore Particles with Biomass Syngas

Numerical Simulation of Flash Reduction of Iron Ore Particles with Biomass Syngas

Multi-physics field modeling of biomass gasification syngas fueled solid oxide fuel cell

In order to uncover the inner working mechanism and performance of solid oxide fuel cell (SOFC) with biomass gasification syngas as fuel, a two dimensional SOFC multi-physical field model is established. This study makes up for the deficiency that the previous studies of coupling biomass gasification unit and SOFC stack mostly stay at the system level. The results show that the SOFC fueled by the syngas produced from gasification of biomass with steam as the agent has the best performance. The peak power density could achieve approximately 10240 W m−2. With the improvement of operating temperature, the peak power density of SOFC will be increased. At the temperature of 1123 K, the peak power density could achieve about 15128 W m−2. The average reaction rate of water gas shift (WGS) reaction is −29.73 mol m−3 s−1 when the operating temperature is 1123 K. This indicates that the WGS reaction will proceed in reverse direction at high temperatures, thereby reducing the hydrogen concentration. In addition, increase in the anode flux and decrease in the cell length lead to the increase of SOFC current density. In general, this work could provide guidance for the optimization and practical application of SOFC using biomass syngas as fuel.

Bi-Functional Catalyst/Sorbent for a H2-Rich Gas from Biomass Gasification

The aim of this work is to identify the effect of the CaO phase as a CO2 sorbent and mayenite (Ca12Al14O33) as a stabilizing phase in a bi-functional material for CO2 capture in biomass syngas conditioning and cleaning at high temperature. The effect of different CaO weight contents is studied (0, 56, 85, 100 wt%) in sorbents synthesized by the wet mixing method. These high temperature solid sorbents are upgraded to bi-functional compounds by the addition of 3 or 6 wt% of nickel chosen as the metal active phase. N2 adsorption, X-ray diffraction, scanning electronic microscopy, temperature-programmed reduction analyses and CO2 sorption study were performed to characterize structural, textural, reducibility and sorption properties of bi-functional materials. Finally, sorption-enhanced reforming of toluene (chosen as tar model), of methane then of methane and toluene with bi-functional compounds were performed to study the best material to improve H2 content in a syngas, provided by steam biomass gasification. If the catalytic activity on the sorption enhanced reforming of methane exhibits a fast fall-down after 10–15 min of experimental test, the reforming of toluene reaches a constant conversion of 99.9% by using bi-functional materials.