Woody Biomass Fuels Research Articles

C203005 被災地での活用が期待されているスターリングエンジン

The Great East Japan Earthquake occurred on March 11,2011,and the huge tsunami brought with it great suffering in the coast of Tohoku region.The tsunami swept away people,cars,houses and whole communities.In this report,the outline of the challenge using Stirling cycle machine in the disaster area is concretely introduced.In the community of the disaster area,the system which utilizes renewable energies such as solar,wind energy and woody biomass fuels is also expected.

Sensitivity analysis of woody-biomass burning facilities on cost of facility and fuel comparing scale of the facilities and form of the woody biomass fuels

Sensitivity analysis of woody-biomass burning facilities on cost of facility and fuel comparing scale of the facilities and form of the woody biomass fuels

Study on waste heat recovery from exhaust smoke in cogeneration system using woody biomass fuels

In recent years, fossil fuels such as petroleum, coal, and natural gas have become limited resources. In addition, bad effects caused by excessive carbon dioxide (CO2) emissions have now begun destroying our global environment seriously. Since current living and economical standards depend strongly on the fossil fuels, it is necessary to realize a new society that utilizes biomass as one of major sources of energy. In this background, we manufactured a practical Stirling engine using woody biomass fuels for the first time in Japan in 2005. Further we proposed a unique cogeneration system with the Stirling engine that uses woody biomass fuels such as sawdust, firewood, and wood pellets. In this cogeneration system, 43% of the input energy is wasted as heat loss from the exhaust smoke into the atmosphere. Therefore we tried to recover the waste heat by using a thermoelectric conversion module in this study. In this report, the results of basic performance test and demonstration experiment as a cogeneration system combined the waste heat recovery with a power generating system are reported. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.20390

Biomass gasification in a 100 kWth steam-oxygen blown circulating fluidized bed gasifier: Effects of operational conditions on product gas distribution and tar formation

Biomass gasification is one of the most promising technologies for converting biomass, a renewable source, into an easily transportable and usable fuel. Two woody biomass fuels Agrol and willow, and one agriculture residue Dry Distiller’s Grains with Solubles (DDGS), have been tested using an atmospheric pressure 100 kWth steam-oxygen blown circulating fluidized bed gasifier (CFB). The effects of operational conditions (e.g. steam to biomass ratio (SBR), oxygen to biomass stoichiometric ratio (ER) and gasification temperature) and bed materials on the composition distribution of the product gas and tar formation from these fuels were investigated. Experimental results show that there is a significant variation in the composition of the product gas produced. Among all the experiments, the averaged concentration of H2 obtained from Agrol, willow and DDGS over the temperature range from 800 to 820 °C was around 24 vol.%, 28 vol.% and 20 vol.% on a N2 free basis, respectively. A fairly high amount of H2S (∼2300 ppmv), COS (∼200 ppmv) and trace amounts of methyl mercaptan (<3 ppmv) on a N2 free basis were obtained from DDGS. Due to a relatively high content of K and Cl in DDGS fuel, an alkali-getter (e.g. kaolin) was added to avoid agglomeration during gasification. Higher temperatures and SBR values were favorable for increasing the mole ratio of H2 to CO and the tar decomposition but less advantageous for the formation of CH4. Meanwhile, higher temperatures and SBR values also led to higher gas yields, whereas a higher SBR caused a lower carbon conversion efficiency (CCE%), cold gas efficiency (CGE%) and heating values of the product gas due to a high steam content in the product gas. From solid phase adsorption (SPA) results, the total tar content obtained from Agrol was the highest at around 12.4 g/Nm3, followed by that from DDGS and willow gasification. The lowest tar content produced from Agrol, willow and DDGS using Austrian olivine (Bed 1) as bed materials was 5.7, 4.4 and 7.3 g/Nm3, values which were obtained at a temperature of 730, 820 and 730 °C, SBR of 1.52, 1.14 and 1.10, and ER of 0.36, 0.39 and 0.37, respectively.

Study on Waste Heat Recovery from Exhaust Smoke in Co-Generation System Using Woody Biomass Fuels

In recent years, fossil fuels such as petroleum, coal, and natural gas have become limited resources. In addition, bad effects caused by excessive carbon dioxide (CO2) emissions have now begun destroying our global environment seriously. Since current living and economical standards depend strongly on the fossil fuels, it is necessary to realize a new society that utilizes biomass as one of major sources of energy. In this background, we manufactured a practical Stirling engine using woody biomass fuels for the first time in Japan in 2005. Further we proposed a unique co-generation system with the Stirling engine that uses woody biomass fuels such as sawdust, firewood, and wood pellets. In this co-generation system, 43% of the input energy is wasted as heat loss from the exhaust smoke into the atmosphere. Therefore we tried to recover the waste heat by using a thermoelectric conversion module in this study. In this report, the results of basic performance test and demonstration experiment as a co-generation system combined the waste heat recovery with a power generating system are reported.

Chemical forms of ash-forming elements in woody biomass fuels

Advanced fuel characterization helps to predict ash fouling and slagging. Chemical fractionation analysis, i.e. sequential leaching in H 2O, NH 4Ac( aq), and HCl( aq), was applied to the biomass of spruce, pine, birch, and aspen. All of the Cl in the samples and most of the K, Na, and P were water-soluble; most of the Mg and Mn, and some of the Ca were leached in NH 4Ac; most of the Ca was leached in HCl; and most of the Si and S remained insoluble in the biomass. Ion Chromatography found the water-soluble Cl, P, and S present as Cl −, PO 4 3 - , and SO 4 2 - , respectively, and equimolar concentrations of C 2 O 4 2 - as leached Ca in the acid fraction. The biomass solids were determined for anionic groups by methylene blue sorption. The contents were lowest in the wood samples (22–118 mmol/kg D.S.) and highest in the bark samples (130–453 mmol/kg D.S.). The closing of the ion charge balance led to a quantitative model for the ash-forming matter: water-soluble salts (KCl, K 2HPO 4, and K 2SO 4), acid-soluble minerals (CaC 2O 4), non-soluble minerals (SiO 2), and organically associated ash-forming elements (ionically bonded Ca 2+, Mg 2+, Mn 2+, and K +, and covalently bonded P and S).

Ash Transformations in Fluidized-bed Combustion of Rapeseed Meal

The global production of rapeoil is increasing. A byproduct is rapeseed meal that is a result of the oil extraction process. Presently the rapeseed meal mainly is utilized as animal feed. An interesting alternative use is, however, energy conversion by combustion. This study was undertaken to determine the combustion properties of rapeseed meal and bark mixtures in a bubbling fluidized bed, with emphasis on gas emissions, ash formation, -fractionation and -interaction with the bed material. Due to the high content of phosphorus in rapeseed meal the fuel ash is dominated by phosphates, in contrast to most woody biomass where the ash is dominated by silicates. From a fluidized bed combustion (FBC) point of view, rapeseed meal could be a suitable fuel. Considering FBC agglomeration effects, pure rapeseed meal is in level with the most suitable fuels, as earlier tested by the methods utilized in the present investigation. The SO2 emission, however, is higher than most woody biomass fuels as a direct consequen...

414 木質バイオマスエネルギーを活用した冷・温熱/電気の併給システム(新エネルギー(4))

A time has come to reflect on civilization blessed with convenient fossil fuels for the past 100years. Fossil fuels such as petroleum, coal, and natural gas have become limited resources. In addition, bad effects caused by excessive carbon dioxide (CO_2) have now begun destroying our global environment seriously. Since current living and economical standards depend strongly on fossil energy sources, it is necessary to realize a new society that utilizes biomass as a source of energy. In such background, we manufactured the practical Stirling engine using biomass fuels in 2005. And we proposed a unique co-generation system by the engine that uses woody biomass fuels. The co-generation system provided about 3kW of electricity and the heat from the system can be recovered and used in a number of ways for space and domestic water heating. The co-generation system is utilizes up to 45% of the system input energy in the form of electricity or heat. In this study, we tried to recover the waste heat of 43% by using a thermoelectric conversion module. And the Stirling cooler using electric power based woody biomass energy is tested in performance.

Fluidized Bed Combustion of Some Woody Biomass Fuels

In this study, the experiments of comparing cedar pellet, cypress pellet, and cypress sawdust combustion in a bubbling fluidized bed combustor (BFBC) was carried out. To improve the combustion efficiency and avoid the agglomeration, the porous alumina sand was used as bed material instead of conventional silica sand. Experimental results indicated that pellet can be sufficiently burned in the BFBC, and the CO emission was only 50–188 ppm. Meanwhile, the unburned carbon in fly ash was considerably limited even neglected; both the unburned carbon in fly ash and CO emission (3,700 ppm) was significantly high during sawdust combustion. Moreover, it was difficult to operate the BFBC above 650°C with the sawdust. Therefore, direct combustion was not a good utilization method for sawdust. It was also observed that volatile matter released from pellet volatilized and mostly burned in the dense zone due to the porous alumina. The effect of operation parameters like temperature and fluidized velocity on the pollution emission and combustion characteristic was also evaluated. High temperatures can promote the combustion efficiency, while SO2 and NOx emission is independent to temperature. As for fluidized velocity, the optimum fluidized velocity in the tests is about 0.07 m/s.

Influence of Sand Contamination on Slag Formation during Combustion of Wood Derived Fuels

Previous investigations have suggested that sand contamination to woody biomass fuels enhances slag formation in residential combustion appliances. The objectives were therefore to observe the effect of soil contamination in different forestry assortments on the extent of slagging and to gain increased understanding in the ash and slag forming chemical processes. This was accomplished by studying the bottom ash and the slag compositions after 19 ± 2 h of combustion in a residential pellet burner. Melted ash reacted with the admixed sand particles resulting in an increased amount of melt with an increased content of silicon. The results confirm earlier experiences that melted bottom ash from combustion of woody biomass, upon cooling, forms silicate phases. In the corresponding melted ash, sand minerals as quartz, plagioclase, and microcline are not thermodynamically stable but will react and form a more silica rich melt. This melt has presumably lower liquidus temperature, explaining the increased amount of melt observed in the combustion experiments of soil contaminated fuels.

Experimental investigation of nitrogen species release from different solid biomass fuels as a basis for release models

Experimental data on the release of NO x precursors from solid biomass fuels during thermal conversion are necessary to study N release in general and to supply reliable data for the purpose of packed bed and gas phase conversion model development and validation. In this work the release of NO x precursors was studied at a lab-scale pot furnace (batch reactor) by taking measurements during the conversion process of solid biomass in a packed bed. The investigations were carried out with relevant woody biomass fuels, which cover a broad range of fuel N contents: sawdust, bark, waste wood and MDF board. The most important NO x precursor detected above the fuel bed under fuel rich conditions was NH 3, while HCN was almost insignificant with the exception of sawdust. NO was detected mainly under air rich conditions. Furthermore, the experimental data were utilised to derive release functions for the relevant NO x precursors NO, NH 3 and HCN. The release functions were implemented in an in-house empirical packed bed combustion model, which serves as a basis for a subsequent CFD N species gas phase calculation.

404 木質バイオマス燃料によるスターリングエンジン/ヒートポンプ複合コージェネレーションシステムのエネルギーバランス(機械力学・計測制御I,環境工学,計測制御・機械力学,流体工学,熱工学,環境工学)

404 木質バイオマス燃料によるスターリングエンジン/ヒートポンプ複合コージェネレーションシステムのエネルギーバランス(機械力学・計測制御I,環境工学,計測制御・機械力学,流体工学,熱工学,環境工学)

Modeling of Aerosol Formation during Biomass Combustion in Grate Furnaces and Comparison with Measurements

Results from mathematical modeling of aerosol formation during combustion of woody biomass fuels were compared with results from particle size distribution (PSD) measurements at a pilot-scale biomass combustion unit with moving grate and flame tube boiler. The mathematical model is a plug flow model considering coagulation, nucleation, condensation, and particle deposition mechanisms (thermophoresis, particle diffusion, turbophoresis, and gravitational settling) of spherical particles as well as condensation of vapors on cooled boiler walls and a changing flue gas composition determined by equilibrium calculations. Additionally, the influence of kinetically limited homogeneous and heterogeneous reactions was taken into account in the case of sulfation reactions. To check the modeling results, investigations regarding PSDs and total aerosol mass loadings of the flue gas resulting from biomass combustion (beech chips, waste wood) were performed by measurements at a fixed bed biomass combustion unit (nominal boiler capacity: 440 kW). Furthermore, the composition of the aerosols sampled was determined. The comparison of calculated and measured particle size distributions and aerosol compositions agreed well, which permits the conclusion to be drawn that the model is applicable to the estimation of amount and chemical composition of aerosol emissions from fixed-bed biomass combustion

Modeling NH 3 and HCN emissions from biomass circulating fluidized bed gasifiers ☆

A circulating fluidized bed biomass gasification model is developed in the present study. The model consists of sub-models for devolatilization, tar cracking and a chemical reaction network of main gasification reactions and nitrogen chemistry. A total of forty global chemical reactions are included in the model, of which twenty-eight reactions belong to fuel-nitrogen reaction network. Individual reaction rates are selected from the literature, wherever possible, based on studies of woody biomass fuels. Volatile nitrogen is assumed to consist of NH 3, HCN and N 2 with the distribution between three species as input parameters to the model. Modeling of the hydrodynamics of the riser is simplified by using solids concentration profile along the riser as an input to the model. Both gaseous phase and solids phase are assumed to be in plug flow. Modeling results are compared with the experimental results published in the literature. Predicted effects of bed temperature, equivalence ratio and fuel moisture content on main gaseous composition, tar and NH 3 emissions generally agree with the literature data. A sensitivity analysis of some reaction rates included in the model on NH 3 emissions has also been carried out. It has been revealed that the catalytic activity of bed materials towards the oxidation of NH 3 has the greatest influence on the predicted NH 3 emissions. In addition, the predicted NH 3 emissions are also affected by the catalytic activity of bed materials towards the decomposition of NH 3 and the homogenous reaction rates of NH 3 decomposition and the reduction of NO by NH 3 in the presence of oxygen.

Modelling of NO and N 2O emissions from biomass-fired circulating fluidized bed combustors

A model for NO and N 2O emissions from biomass-fired circulating fluidized bed (CFB) combustors has been developed and evaluated in this study. All the model parameters were chosen for a typical woody biomass–pinewood chips. Both drying and devolatilization of biomass particles were modelled with limited rates, which were selected from the literature based on woody biomass fuels. The partition of fuel-nitrogen between volatiles and char was also specifically chosen for pinewood based on available experimental data from the literature. Volatile nitrogen was assumed to consist of NH 3, HCN and N 2 with the distribution between three species as input parameters to the model. Twenty-five homogenous and heterogeneous global chemical reactions were included in the model, of which 20 reactions represents the global fuel-nitrogen reactions. Both gaseous and solid phase were assumed to be in plug flow. The model has been applied to the modelling of a 12 MW th CFB boiler. The predicted N 2O emissions were always less than 5 ppmv for pinewood combustion, which was consistent with the experimental results. The predicted NO emissions increased with the total excess air of the riser and the fuel-N content while the predicted percentage conversion of fuel-N to NO decreased with increasing fuel-N content. The NO emissions were also predicted to decrease with increasing primary zone stoichiometry. These predictions agree with the experimental results. The predicted NO emissions decreased slightly with increasing bed temperature, whereas experiments showed that NO emissions slightly increased with bed temperature for birch chips combustion and did not change with bed temperature for fir chips combustion. Sensitivity analyses reveal that the reaction between NO and char is the key reaction to determine the NO emissions.

The recent European biofuel debate as a case study in the politics of renewable energy

This study outlines a number of issues of a political nature, associated with the implementation of renewables, with the primary emphasis on the recent European push for the production of liquid biofuels. In recent years biofuels have been gaining increasing attention as a potential alternative to conventional automotive fuels. This potential has recently become an issue in the European Union (EU) with surplus agricultural land being considered for the production of energy crops. In this paper political issues at stake in the promotion of biofuel crops in the EU are examined. A critical analysis is made of the environmental claims put forward in defence of the promotion of these fuel crops and comparisons made with alternate woody biomass fuels. Contrasts are drawn between this case study and other examples of the implementation of renewables including the development of PV in the US and wind power in the UK. Conclusions are made regarding the impact of the issues thrown up on the future development of renewables.

Electricty generation from woody biomass fuels compared with other renewable energy options

The future New Zealand biomass resource from exotic plantation forest arisings could supply 970 GWh/year by the year 2002. Associated wood processing residues could supply 280 GWh/year. Purpose grown fuelwood plantations could supply 2060 GWh/year with potential to rise to 10,000 GWh/year by 2012. Currently the annual electricity demand is around 30,000 GWh 70% of which is generated by hydro power. Natural gas, a resource with estimated reserves of only approximately 14 years currently supplies 25% of generating capacity. This paper describes how part replacement of gas by biomass could be a feasible proposition for the future. Life cycle cost analyses showed electricity could be generated from arisings for (US)4.8–6 c/kWh; from residues for (US)2.4–4.8 c/kWh; and from plantations for (US)4.8–7.2 c/kWh. For comparison the current retail electricity price is around (US)4–5.5 c/kWh and estimates for wind power generation range from (US)5–10 c/kWh. Future hydropower schemes will generate power between (US)4–9 c/kWh depending on site suitability.