Wood Gasification Research Articles

Cross-interaction during Co-gasification of wood, weed, plastic, tire and carton

This study investigated the gasification of wood, weed, plastic, tire, carton and their mixtures using zeolite (A4 type) as a catalyst, with the purpose of investigating the potential interactions of the various feedstocks during gasification. The co-gasification of the mixed feedstock led to the occurrences of the cross-interactions, which substantially impacted the distribution of the products in gasification. During the co-gasification, the pyrolysis/gasification of the different feedstocks produced the reaction intermediates with varied structures that interacted with each other and with the char formed from the different feedstock. The interaction could promote the gasification of the tarry compounds into gaseous products, which could also promote the gasification of the char to lower the char yields. Further to this, the cross-polymerisation or cracking of the varied reaction intermediates also took place during the co-gasification, leading to the formation of more coke deposits on catalyst. The co-gasification of the mixed feedstocks significantly impacted the reaction network, impacting the formation of gases, tar, char and the coke on catalysts, originating from the cross-interaction among the reaction intermediates derived from the pyrolysis/gasification of the various feedstocks.

ПРОБЛЕМИ ВИКОРИСТАННЯ ГЕНЕРАТОРНОГО ГАЗУ ЯК ДЖЕРЕЛА ЕНЕРГІЇ

It was noted that the use of alternative fuels for the production of thermal and electric energy in the face of energy scarcity is an urgent task of the present. The paper states that combustion of gas from low-grade solid fuels has several advantages. At the same time, it is noted that during gasification of wood, agricultural crops, peat, brown coal, as well as some types of coal, a considerable amount of resinous substances, which condense during the cooling of gas, is released. The analysis of literary information on methods of gasification of alternative types of fuels, on requirements to the content of resins in the generator gas, as well as on the properties of resins. It is shown that among the known methods of gasification, the most effective in terms of obtaining a non-slag gas is the step-by-step gasification. The information on the content of resins in the generator gas during the gasification of various types of fuels is systematized. It is noted that the pollution of the generator gas resins leads to the need to use expensive gas cleaning systems and makes it necessary to look for new ways to control the gasification process. It is shown that most of the most common technologies of biomass gasification do not meet the requirements of Diesel engine manufacturers for the content of resins in generator gas (5 - 100 mg/m3). Therefore, the most expedient way to get the generator gas for combustion in the internal combustion engine is stepped gasification. The composition of the resin has been analyzed and it is shown that among the five classes of resins the most widespread during the gasification of wood are classes 2 and 4, the temperature of the dew point of resin for them ranges from 40 to 135 ° C in the range of concentration of resin in gas from 5 mg/m3 to 10 g/m3 It is noted that information on the admissible content of resins in flue gases, which will exclude their condensation, in the direct burning of wood and other alternative types of fuel in open access.

The New Method for Determining the Composition of Wood Gas Produced in Gas Generators of the Inverted Gasification Process

The article presents a new method for determining the composition of wood generator gas produced in gas generators of the inverted gasification process. The shortcomings of the existing calculation methods are analyzed, the main of which is the insufficient harmonization of the calculation results with the experimental data. The authors substantiate the priority of the main chemical reactions occurring during gasification of wood fuel. There are three active zones of gasification, viz.: a redox zone, a reduction zone and a zone of interaction of gasification products with each other and with the carbon of the fuel. In general, a redox zone consists of two subzones: in the first one reactions of water gas formation occur, and the second one appears when excess air is supplied to the gas generator. The proposed method for calculating the components of the generator gas is a set of a modified balance method and an added method for calculating the concentrations of chemical reaction products by the equilibrium constants of these reactions in the active gasification zones with different temperatures. The modified balance method considers the primary processes of wood and moist air transformation into components of the generator gas in the first subzone of the redox zone. The modified balance method is based on the equations of material balance of carbon, hydrogen, oxygen, moisture, nitrogen and thermal balance of the system. The added method determines the concentrations of the components of the generator gas in the second subzone of the redox zone, as well as in the reduction zone and the zone of interaction of the gasification products with each other and with the fuel carbon. The combination of these two methods makes it possible to calculate with greater accuracy the output of the generator gas, the concentration of its components, fuel and air consumption, as well as a number of other characteristics of the gas generator.

Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 2. Na-Feldspar

Selecting a suitable bed material for the thermochemical conversion of a specific feedstock in a fluidized bed system requires identification of the characteristics of potential bed materials. An essential part of these characteristics is the interaction of the bed material with feedstock ash in a fluidized bed, which leads to layer formation and morphology changes. For this purpose, the interaction of feldspar bed material with the main ash-forming elements in wood ash (Ca, K, Mg, Si) in an indirect gasification system was analyzed using SEM-EDS, XRD, and thermodynamic modeling. In part 1 of this work (DOI: 10.1021/acs.energyfuels.9b01291), the layer formation on K-feldspar dominated by Ca reaction and ash deposition was investigated. The aim of this second part of the work was to determine the time-dependent layer formation on Na-feldspar and compare the results with the findings for K-feldspar. Interaction of Na-feldspar with ash-derived elements resulted in different layers on Na-feldspar: K reaction layers, where K replaced Na and Si shares decreased; Ca reaction layers, where Ca enriched and reacted with the Na-feldspar; and ash deposition layers, where wood ash elements accumulated on the surface. Ca reaction layers were formed first and became continuous on the surface before K reaction layers and ash deposition layers were detected. Cracks and crack layer formation in the Na-feldspar particles were found after several days of operation. The layer compositions and growth rates indicate that the diffusion of Ca and K plays an essential role in the formation of Ca reaction and K reaction layers. The reaction with Ca and the crack formation coincide with the interaction previously found for quartz and K-feldspar. In contrast to K-feldspar, Na-feldspar showed high potential for reaction with K. The findings indicate that the reaction of Na- feldspar with ash-derived K makes Na-feldspar a less stable bed material than K-feldspar during the thermochemical conversion of K-rich feedstocks in a fluidized bed system.

Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 1. K-Feldspar

Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 1. K-Feldspar

Operation of an SOFC CHP System with Wood Gas from a Fixed-Bed Updraft Gasifier

This paper will show the results of operating an SOFC system with the product gas from a biomass gasifier for more than 200 hours under constant and dynamic operation. The SOFC system was operated at different load cases, 50 % and 100 % load, and achieved a gross electrical efficiency of 42 %. It shows a high dynamic behavior, so that electric load changes could be performed within a few seconds from full load to part load. Furthermore, AVL developed a simulation software by which a SOFC stack model can be simulated dynamically. A comparison of the measured and simulated values of the stack module will be presented. By using the results of the test runs the software could be validated successfully.

Conversion of Products Formed in Gasification of Organic Fuels in a Flow-Through Filtration Converter with Packing

Results are presented of experimental studies of the conversion of products formed in gasification of wood, peat, coal-wastes, and shale rock via the partial oxidation by air in a flow-through filtration converter filled with various kinds of porous packing. Charcoal ZPS zeolite and Raschig porcelain rings served as a packing. It was possible to experimentally select for all kinds of packing the modes in which the combustion heat of the conversion products is not lower than that of the starting gaseous products. The conversion of pyrolysis tars was 60–85% and depended insignificantly of the type of a packing. The experimental results were compared for products formed in gasification of wood and coal waste with the data calculated in terms of the thermodynamic conversion model. The satisfactory correspondence between the results of a thermodynamic calculation and experimental data was obtained for products formed in gasification of wood, in which the content of pyrolysis tars is rather high.

Experimental investigation on energy-efficient twin-mode biomass improved cookstove

This study deals with the design and development of a gasification-based wood gas stove for energy demand of a six-member family. The novelty of the designed cookstove is that it works in the natural draft as well as in forced draft air supply mode efficiently. The performance of the developed stove was examined as per the Bureau of Indian Standard (IS: 13152; Part-I) test protocol. The stove was tested with babul (Acacia nilotica) wood and groundnut (Arachis hypogaea) shell pellet in dual draft air supply mode. In the forced draft air supply mode with A. nilotica wood, the average thermal efficiency, power rating, CO and CO2 emissions and total particulate matter were estimated at around 36.56%, 3.15 kW, 0.2 ppm and 10.4 ppm, and 134.1 × 10−6 g kJ−1, respectively. The economic assessment was carried out as per the supply and market rates in India, which may vary from country to country. The capital cost of the cookstove is around 11 US$, which makes it economically viable for the people residing in rural areas with the payback period of 20–29 days.

Effect of benzene doping on soot precursors formation in non-premixed flames of producer gas (PG)

The study of soot precursors formation in the combustion of model Producer Gas (PG) from wood gasifiers with benzene as tar surrogate is presented. Experimental temperature and concentration profiles of 4 non-premixed flames—1 neat PG and 3 benzene-doped flames (0.2, 1 and 2%vol)—collected in a counterflow burner were compared with CHEMKIN simulations using 3 kinetic mechanisms of PAHs formation: ABF coupled with GRI3, and two mechanisms developed by the Institute of Combustion Technology of the German Aerospace Center labeled here as DLR2012 and DLR2018, the latter being a partial upgrade of the prior version mainly including C1-C4 oxidation optimization. The neat-PG flame did not yield detectable aromatics while only toluene is produced in the flame with 0.2%vol of benzene, suggesting a minor contribution of pathways leading to the larger aromatics. DLR2018 reproduces the correct order of magnitude for most of the compounds, but notable quantitative and qualitative deviations were observed for naphthalene (A2) in the richer-benzene flames (1 and 2%vol). This discrepancy is a consequence of DLR2018 considering the reaction between i-C4H5 and benzene as the most influential A2 formation pathway in the examined flames. DLR2018 reaction-path and sensitivity analyses were used to gain insights in the mechanism performance and the benzene influence. It was found that addition of H to phenyl producing benzene is one of the reactions chiefly affecting the concentration profiles of the measured species. Lower rates taken from literature for this reaction yielded some improvements for most of the species in both flames, including the reduction of the initial naphthalene underestimation. Additional modifications of A2 reaction rates were tested, identifying changes leading to a better agreement between experiment and simulations. This analysis aims at recognizing the factors underlying the observed disagreements in predicting some species concentration in the studied flames. The obtained insights should be included in the next iteration of PAH reaction model development.

Molecular-level understanding of support effects on the regenerability of Ru-based catalysts in the sulfur-poisoned methanation reaction

The production of synthetic natural gas—SNG—from dry biomass currently involves a costly and energy-inefficient low-temperature gas cleaning step, needed to remove various sulfur-containing poisons from syngas generated from wood gasification before the sulfur-sensitive methanation step. Here we explore the use of Ru-based methanation catalysts in an alternative process, where the low-temperature gas cleaning step is omitted and the syngas from the gasifier is used directly for methanation. In this process, methanation is carried out in the presence of organic and inorganic sulfur species and is followed by periodic oxidative regeneration of the poisoned catalyst. In situ diffuse reflectance infrared Fourier transform spectroscopy and Ru K-edge X-ray absorption spectroscopy were employed to understand the mechanism of deactivation of Ru nanoparticles on two different supports: Al2O3 and SiO2. The efficiency of the regeneration is higher when Ru nanoparticles are supported on SiO2, on which only a small amount of unstable sulfate species is formed and Ru nanoparticles are more stable against sintering during oxidative regeneration due to a “passivation” effect of the adsorbed sulfur species.

Investigation on the influence of non-thermal plasma on reaction degree of wood gasification in a drop tube reactor

The influence of non-thermal plasma (NTP) on entrained-flow wood gasification at atmospheric pressure was investigated in experiments performed at a drop tube reactor with an inner diameter of 0.1 m. Three particle size categories covering diameters between 125 and 700 µm were used for testing. NTP and thermal gasification were compared applying similar experimental conditions in order to study the contribution of radicals, excited species, and charged particles to the gasification reaction. In case of NTP gasification about 1 kW of electric power was supplied to the preheated steam, whereas in case of thermal gasification the preheated steam was superheated applying about the same heat rate. Due to thermalization the temperature flow-down of the NTP zone approached the temperature after thermal superheating. The syngas-based carbon conversion degree was calculated from the ratio of the carbon content of the gaseous products (CO, CO2 and CH4) to that one of the original feedstock. Results show that NTP enhances syngas production for at least 20% and carbon conversion for 27% compared to thermal gasification. Kinetic rate coefficients for syngas formation as a function of temperature were obtained by fitting the syngas based carbon conversion degree assuming a first order reaction and temperature dependency described by the Arrhenius equation. For NTP gasification reaction rate coefficients increased by 33% as compared to thermal gasification were achieved.

Life cycle and decision analysis of electricity production from biomass – Portugal case study

The present study aims to endow decision-makers with an evaluation of the different ways to produce electricity from biomass considering their life cycle impact and energy efficiency, in order to highlight the most sustainable options. A model was developed based on a life cycle approach complemented by a sensitivity analysis, and supported by a posterior decision analysis, having the criteria of used energy per 1 MJ of electricity produced and as well as emissions of carbon dioxide, methane, nitrous oxide and solid particles. The decision analysis methods on LCA studies show to be useful in selecting the best solutions in multiple criteria decision, demonstrating particular importance in complementing the sensitivity analysis within an overall comparison between pathways. The considered technologies include wood gasification, Rankine's cycle, co-firing, black liquor gasification, biogas engine and combined cycle gas turbine, using as feedstock farmed wood, forest residues, black liquor, manure and municipal waste, in a total of eleven ways were studied. The results show that no solution have better results in all criteria comparatively, yet the proposed decision methods suggested that the best “global” pathways were the ones using manure, combined cycle using municipal waste as feedstock and forest residues gasification. The pathway that consumes less energy to produce 1 MJ of electrical energy is the cofiring using forest residues. The emissions of PM10 and PM2.5 are minimized in the pathways of Rankine cycle and IGCC with forest residue as feedstock, respectively. The sensibility analysis indicates that input values chosen can affect considerably the final results, together with the quality of the biomass.

Studies for removal of tar from producer gas in small scale biomass gasifiers using biodiesel

Biomass gasification based electricity generation systems are emerging as an important component of the decentralised energy supply systems in rural India. Each type of gasifier has different reaction conditions, temperature, residence time, pressure, feedstock, reactor design, and therefore the tar and particulate matter (PM) compositions and concentrations are found to vary. A field study was conducted on a 35 kWe downdraft gasifier to measure and characterize the tar in producer gas using GC-MS, for rice husk and pine needles as the two biomass feeds. Use of water-based scrubbers for removal of tar and PM is prevalent, however it is often the case that such clean-up is not adequate for meeting the engine manufacturers’ requirements for the quality of intake gas. Limited attempts have been reported for the use of organic solvent based gas cleaning in small scale downdraft gasifiers in the range 15–50 kWe. In the present work, toluene, naphthalene and phenol were selected as representative compounds of tar, and methyl oleate was selected to represent biodiesel as an organic solvent. A bench scale packed bed scrubber was designed for 95% removal of toluene. An 86–97% removal of toluene from the gas stream was achieved, and similar results were obtained for phenol and naphthalene. Further experiments were carried out with actual producer gas from a 1 kWe downdraft wood gasifier. Pongamia pinnata based biodiesel was used as the solvent, and 88–92% of the tar removal from the producer gas stream was achievable.

Розроблення методу розрахунку процесу газифікації низькосортного палива у суцільному шарі на основі експериментальних досліджень

Розроблено метод розрахунку процесу газифікації низькосортного палива, який дає змогу провести розрахунок параметрів робочого процесу в газифікаторі зі суцільним шаром, який є найбільш технологічно та конструктивно простим. Проаналізовано фізичні моделі процесу газифікації твердого палива, які дають змогу побудувати методику розрахунку параметрів робочого процесу у газифікаторі, засновану на рівняннях теплового і матеріального балансів, вигорання і газифікації вуглецю, що сприяє підвищенню екологічних показників та модернізації наявних інженерних методів розрахунку. Використано стандартизовані методи проведення досліджень процесу газифікації низькосортного палива. У процесі розроблення газогенераторної установки, що дає змогу виробляти синтез-газ, застосовано сучасні методи використання відповідних контрольно-вимірювальних пристроїв. Використано математичне планування експериментальних досліджень. Розроблено метод розрахунку процесу газифікації деревини, який дає змогу провести розрахунок параметрів робочого процесу в газифікаторі зі суцільним шаром, засновану на рівняннях теплового і матеріального балансів. На основі експериментальних досліджень складено матеріальний і тепловий баланси процесу газифікації деревини породи сосна (Pinus sylvestris). Показано, що під час газифікації соснової деревини невеликі втрати тепла виходять внаслідок винесення пилу і втрат вуглецю із золою і шлаком.

Options for using solid oxide fuel cell technology in complex integrated biomass gasification cogeneration plants

The aim of this paper is to draw readers' attention to potential new technological solutions for effective utilisation of dispersed biomass resources in distributed community-scale applications. In the paper conceptual system, that consists of allothermal wood gasifier, solid oxide fuel cell (SOFC), internal combustion piston engine (ICE) and Organic Rankine Cycle (ORC) for waste heat recovery, is proposed. Configuration of such systems is nowadays possible due to availability individual small-scale energy conversion technologies that can be integrated into complex structures. In the studied case the anode exhaust gas of the syngas fired SOFC module, that still contains combustible gases, is considered a secondary fuel for a bottoming ICE. The ORC cycle module is driven by the heat recovered from process gas coolers as well as from SOFC cathode and ICE exhaust gases. The system has been theoretically evaluated in terms of energy conversion efficiency and profitability using thermodynamic and economic analysis. Relevant robust mathematical models of key components have been developed. Through the modelling the most important performance parameters are addressed. Electric power of the sample system is below 1 MW what makes it suitable for utilisation of locally available biomass. Simulations revealed potentially high value of the net biomass energy to electricity conversion efficiency of 37%–40% depending on the ORC cycle configuration. Financial analysis revealed positive values of profitability indices at current level of market prices. The results are compared with a real biomass-fired ORC cogeneration project. The system also addresses issues related to external effects of the project, such as global emission reduction and primary energy savings.

Effect of Biochar on Soil Greenhouse Gas Emissions at the Laboratory and Field Scales

Biochar application to soil has been proposed as a means for reducing soil greenhouse gas emissions and mitigating climate change. The effects, however, of interactions between biochar, moisture and temperature on soil CO2 and N2O emissions, remain poorly understood. Furthermore, the applicability of lab-scale observations to field conditions in diverse agroecosystems remains uncertain. Here we investigate the impact of a mixed wood gasification biochar on CO2 and N2O emissions from loess-derived soils using: (1) controlled laboratory incubations at three moisture (27, 31 and 35%) and three temperature (10, 20 and 30 °C) levels and (2) a field study with four cropping systems (continuous corn, switchgrass, low diversity grass mix and high diversity grass-forb mix). Biochar reduced N2O emissions under specific temperatures and moistures in the laboratory and in the continuous corn cropping system in the field. However, the effect of biochar on N2O emissions was only significant in the field and no effect on cumulative CO2 emissions was observed. Cropping system also had a significant effect in the field study, with soils in grass and grass-forb cropping systems emitting more CO2 and less N2O than corn cropping systems. Observed biochar effects were consistent with previous studies showing that biochar amendments can reduce soil N2O emissions under specific but not all, conditions. The disparity in N2O emission responses at the lab and field scales suggests that laboratory incubation experiments may not reliably predict the impact of biochar at the field scale.

4-1 森林除染を目途とした木質ガス化におけるCs2CO3添加効果

4-1 森林除染を目途とした木質ガス化におけるCs2CO3添加効果

Changes in the Biochar Chemical Structure during the Low-Temperature Gasification of Mallee Biochar in Air as Revealed with Fourier Transform Infrared/Raman and X-ray Photoelectron Spectroscopies

Structural changes in partially gasified char during low-temperature gasification in air were investigated using Fourier transform infrared/Raman and X-ray photoelectron spectroscopies. Two kinds of chars prepared from the gasification of mallee wood in 15% H2O–Ar at 600 and 900 °C were gasified in air at 375 °C in a thermogravimetric analyzer, separately. The breakage of large aromatic ring systems, the consumption of cross-linking structures, and the formation of dangling structures indicated the destruction of the aromatic ring systems of char with the progress of gasification in air. In addition, the oxidation of char was very significant at the initial stage (char conversion of <10%) of gasification in air, which was mainly due to the newly formed aromatic C–O structures. The newly formed aromatic C–O structure was also mainly responsible for the continuously increased total oxygen content, the total Raman intensity, and the total infrared (IR) intensity of char with the progress of gasification in a...

Catalytic and noncatalytic gasification of wood–coconut shell blend under different operating conditions

The formation of tar during biomass gasification is a main barrier to establishing reliable gasification technologies. Different catalysts are being used for tar abatement from the biomass gasification. In this study, catalytic and noncatalytic cogasification of wood‐coconut shell blends was carried out in a downdraft gasifier. The effect of the operating parameters on syngas quality, performance of cogasification, and tar reduction was investigated. The biomass blending ratio (BR) was varied as W20:CS80, W50:CS50, and W80:CS20, equivalence ratio (ER) was varied from 0.19 to 0.35, gasification temperature from 700 to 900 °C and catalyst loading (CL) from 5 to 30%. Dolomite, limestone, and Portland cement were used as a catalyst. The results revealed that under noncatalytic conditions, the blend with higher proportion of coconut shells produces better syngas composition with higher HHV and lower tar content. The high ER reduced H2, tar formation, cold gas efficiency and gas yield. It also improved the carbonaceous gas species and carbon conversion efficiency. Increasing gasification temperature significantly improved the syngas quality, cogasification performance and reduced the tar content. The 30% CL significantly improved the gas composition content, gas yield, cold gas efficiency and reduced the tar content up to 52%. Better syngas quality and cogasification performance was possible with calcined cement catalyst whereas a reduction in tar content was observed in the presence of limestone. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 688–698, 2019

Perennial biomass crop establishment, community characteristics, and productivity in the upper US Midwest: Effects of cropping systems seed mixtures and biochar applications

Abstract Native perennial plants have potential as bioenergy feedstocks, but their use is currently limited by relatively long establishment times and low biomass yields. Some research suggests that incorporating plant species diversity and applying biochar as a soil amendment might alleviate these limitations by creating a more resilient crop and soil system. The objective of this research was to investigate how 1) seeded plant diversity and 2) biochar soil amendments interact to affect the establishment, yield, and plant species composition of biomass cropping systems during the first four years of growth on productive soils. We measured species emergence, cover, peak and post-frost biomass, and biomass composition for three biomass cropping systems seed mixtures – a switchgrass monoculture, a three-species grass mixture, and a highly diverse mixture of grasses and forbs – either with or without application of a mixed wood gasification biochar (9.3 Mg ha−1). We found that seed mixture had significant effects on nearly every variable measured, with switchgrass monocultures outperforming the two more diverse mixtures by the third year of the experiment (12.0 Mg ha−1 in switchgrass, 8.7 Mg ha−1 in low diversity plots, and 3.9 Mg ha−1 in high diversity plots), despite an initial switchgrass establishment failure. The high diversity plots exhibited poor sown species establishment in the first year due to high weed pressure in a drought year, but continued to improve over time. Biochar application had no consistent effect on plant biomass or community traits, and significantly affected only two community traits, light transmittance and leaf area index. Our results suggest that on productive soils perennial bioenergy productivity may be achieved through selection of one or a few high-yielding grass species, with little or no effect of biochar applications on perennial biomass crop establishment, diversity, or productivity.