The co-firing of woody biomass in pulverized coal fired plants is effective for CO_2 reduction. It is necessary to improve the grindability of woody biomass for the high co-firing rate use of woody biomass. In this study, the grindability of carbonized woody biomass was evaluated with a test roller mill. The grinding power for mixture of coal and woody biomass was able to largely decrease by a slight carbonization of woody biomass. The difference of grindability caused by the degree of carbonization was correlated with the content of fixed carbon. In combustion tests, the reduction effect of NOx emission by co-firing of carbonized woody biomass was less than that by co-firing of raw woody biomass.

View full abstract

Investigated into the quality of PKS (Perm Kernel Shell) charcoal which was manufactured in Malaysia. The results of proximate analysis of PKS charcoal were not stable at a point for the volatile matter and ash. After modifying by re-carbonization and air sorting apparatus, PKS charcoal improved and could be treated as a consistent and homogeneous product.

View full abstract

In this study, the system for the production of bamboo antimicrobial by steam treating was investigated. The cutting machine for making bamboo surface skin powder was successfully manufactured. The extracted bamboo antimicrobial constitution by steam treating under the conditions at 180℃, at 0.95MPa indicates antimicrobial performance for MRSA and Escherichia coli O157. The commercial devise with continuously extraction system was suggested. It concluded that the system of production of bamboo antimicrobial confirmed.

View full abstract

In Fukushima prefecture, the full of temporal space for scrap wood, gathered deciduous leaf and wood contaminated with radioactive materials makes debris disposal not proceed now. It is considered that debris should be downsized and be stored safety until incinerator plants are constracted. It is known that bio-coke has high density and poor reactivity, so we think bio-coke technology is suitable to store the debris stably. In this study, the reduction rate of volume, the strength after immerion, leach of radioactive cesium, and the property of heat generation are investigated in order to apply the bio-coke technology for storing debris for long time.

View full abstract

At system of radioactive cesium(Cs) decontamination in the forest, there are 3 bottlenecks. (1) Entry: Without concentrating Cs, the system fall into unsustainable: (2) Pathway: Transporting and/or storing the Cs contaminants is important. (3) Exit: Extreme reduction of volume of final Cs contaminants is required. Conventional process of decontamination, is a separation and transport the polluted soil. This is not a decontamination but migration. Further, temporary storage of the soil is full already. Here is the proposal to overcome each barrier, as follows: (1) The suction of the forestal Cs, by using Cs- enriched leaves.: (2) volume reduction (→1/3) of the leaf litter by the semi-carbonizing, in order to facilitate the storage and transport. (3) Mild combustion of the carbon leads control of Cs volatilization, and the Cs is concentrated onto residual ash.

View full abstract

This report discussed issues for the power plants whose main fuel is forest biomass, focusing on biomass demand for each facility, collectable quantity from forest around, mechanization of forestry and road network of the forest. The issues pointed out were as follows: (1) Many facilities demand was exceeded their biomass quantity from around. (2) Many facilities whose biomass quantity exceeded the facility demand had overlap forests for other facilities. (3) Mechanization of forestry was behind on Chubu and Kinki region. (4) Length of forest road was behind on Kyushu region.

View full abstract

We estimated greenhouse gas (GHG) emissions based on life cycle assessment of electric generation and cogeneration by forest residues in order to analyze quantitatively the environmental superiority. The following 2 scenarios were schemed. Scenario 1: Electricity is generated with 100,000 m^3 of forest residues. Scenario 2: Electricity and heat were cogenerated with 50,000 m^3 of forest residues. The heat was derived from extraction turbine under the condition of 0.5 MPa steam pressure and 7 t/h steam flow. When the generator outputs in the scenario 1 and 2 were respectively 5,760 and 1,400 kW, electrical and overall efficiency were estimated at 19.3% and 47.4%. The GHG emissions reduction ratio per functional unit in the scenario 1 and 2 were respectively 75% and 91% compared with the energy system depending on fossil fuel. It was shown that the utilization of waste heat derived from the electric generation was more effective way to reduce GHG emissions.

View full abstract

A smart community is a community that seeks to develop "smart" solutions for the community as a whole, by using information and communications technology (ICT). A smart community also promotes the use of renewable energies, integrated management, and optimized controls for infrastructure. This paper reports an application of cogeneration system (Electricity & Heat) using wood resource as a fuel.

View full abstract

This study aims to design a biomass utilization system considering residential energy demand. Biomass utilization system consists of 5 processes such as Resource, Preprocessing, Energy conversion, Energy consumption, and Waste treatment. In each process without Energy consumption, energy balance, CO_2 emission, and cost are evaluated. On the other hand, Energy consumption process plays a role of constraint. Especially, not only energy quantity but also energy quality is important for heat demand. In this study, biomass utilization system is modeled quantitatively and qualitatively.

View full abstract

It was estimated whether the wood biomass could provide heat demand in the region of Higashihiroshima. And it was shown that if it is possible to use as firewood all growth in forests, heat utilization of the same amount as the current can be achieved in the calculation in a sustained manner for almost all houses in the city. However, actually available quantity will be a one-severalth. Therefore, in order to increase the contribution of wood biomass, reducing the amount of the total energy used by the energy saving is also important. Combustion equipment using firewood has been great progress recently. Then I thought it appropriate to examine the following demand end first; wood-burning stove, some Italian restaurant-bakery of stone oven, farmers who make the plastic greenhouse heating, social welfare facilities. In order to raise the ratio of renewable energy further, it is thought that it is necessary also perform energy saving and to make a change of a system.

View full abstract

Heat and mass transfer have been investigated during fast pyrolysis of biomass powder packed bed. For cellulose powder, temperature at the center of the bed, T_c, increased monotonously with time due to thermal conduction for T_c<500K. The temperature increased slowly with time due to heat of endothermic cellulose decomposition for 500 K<T_c<600 K. On the other hand, the exothermic behavior was observed at T_c>600 K. For lignin powder, only exothermic behavior was observed at T_c>600K. Therefore, it was found that the exothermic behavior could be occurred by the tar cracking. Furthermore, the relationship between heat flow rate and temperature was studied in order to investigate the heat of reactions. The endothermic and exothermic behaviors could occur for woody biomass because the heat flow rate had the minimum value at T_c=600 K and the maximum value at T_c=650K for both powders.

View full abstract

For estimation of pyrolysis reaction of guaiacylglycerol-β-coniferyl ether, cinnamyl alcohol, coniferyl alcohol, guaiacylglycerol-β-guaiacyl ether, Guaiacylglycerol-β-coniferyl ether were pyrolyzed with Py-GC/MS method, and major pyrolysis products were identified by GC/RT, MS library and fragmentation. From the comparison of pyrolytic results of cinnamyl alcohol and coniferyl alcohol, it was shown that the thermal reaction on the side chain proceeds without via quinone methide intermediate pathway. Major products from guaiacylglycerol-β-coniferyl ether were coniferyl alcohol, coniferyl aldehyde and isoeugenol as well as guaiacol and vinylguaiacol. The formation mechanisms of these compounds were proposed without quinone methide pathway. However, methyl guaiacol and rearrangement products such as isoconiferyl alcohol and eugenol should be formed via quinone methide intermediate.

View full abstract

In recent years, desolation of the forest is a problem at various places in Japan due to the fall in its price cased by cheap timbers from over the sea. Recently, thinning of the forest has come to be carried out from the environmental point of view. Because of the low price and the low energy density, we cannot use effectively timbers obtained by thinning. For the utilization of such timbers, we proposed liquefaction of wood by means of rapid pyrolysis in the Auger typed movable device. The reason is that cost of transport improved by liquefying wood. And contribute to the reduction of carbon dioxide as a further alternative fuel oil. In this study, we investigated the effectiveness of rapid pyrolysis in bench scale Auger typed pyrolyzer, experimentally.

View full abstract

Slow pyrolysis oil of wood (woody tar, WT) was partially hydrodeoxygenated using a continuous-flow slurry-bed reactor. The oxygen content of WT was reduced from 27% to around 10%. The hydrodeoxygenated oil (HWT) was separated into light, middle distillates and bottom (>360℃). The bottom and catalyst recycle and the addition of vanillin and glucose in the feedstock were also tested. The middle distillate (HWT-MD, 240〜360℃) was co-hydrotreated with petroleum LGO and VGO using a continuous-flow fixed bed reactor. The HDS reaction of LGO mixture was inhibited significantly, while that of VGO mixture was promoted by the addition of HWT-MD.

View full abstract

Simplified estimation method for thermodynamic properties, especially heating value and heat capacity, of biomass-derived oil is proposed in this research. Heating value was estimated with arranged Dulong's formula. The proposed formula well estimates reported heating value of hydrocarbons in NIST database with the errors less than ±8%. Heat capacity was estimated according to the kinetic theory of gas. Heat capacity of one mole of atom was obtained, which enabled to calculate the heat capacity of bio-oil.

View full abstract

[in Japanese]

View full abstract

For the commercialization of SCWG technology, it is necessary to achieve long-time stable continuous operation with a large-scale device. The key technologies of SCWG operation should be found by analyzing the result of these tests. This study was conducted to enhance the improvement of system, structure and condition with the analysis of the changes in the long-time continuous tests. The test run was carried out with a pilot scale flow type SCWG plant of 1 t-wet/d processing scale. The nearly 18 h continuous testing was succeeded by barley shochu residue with suspended activated carbon as gasification catalyst. The effluent TOC which was related with tar generation was stable with time. Furthermore, the stable gas composition with time indicated the stable reaction condition in the pilot plant.

View full abstract

The effective production of chemical feedstock from biomass is one of the important issues for building of a sustainable society. Hydroxy methyl furfural (HMF) is one of the key compounds for biorefinary chemical processes. In this report, effective HMF synthesis method was developed. HMF was synthesized by the dehydration reaction from glucose directly with metal and acid catalysts. The reaction conditions were optimized and the reaction with the bilayer system of water and organic solvent showed the high yield performance. It is expected that effective and environment-friendly HMF manufacturing process should be able to be constructed by this reaction system.

View full abstract

As a potential source of biofuel, the freshwater green colonial microalga Botryococcus braunii produces large amounts of hydrocarbons. Generally, pretreatment such as drying or heating of wet algae is needed for sufficient recoveries of hydrocarbons from B. braunii using organic solvents though the most part of its hydrocarbons are accumulated in not inside of cells but the extracellular matrix. However, it was found that the hydrocarbons were extracted more readily from B. braunii cultured in medium prepared with diluted artificial seawater compared with those cultured in a freshwater medium. Algal colonies grew larger in saline media compared with the modified Chu13.

View full abstract

To develop a genetic transformation system for M. thermoacetica ATCC39073, the uracil auxotrophic strain dpyrF was constructed by disrupting pyrF for orotate monophosphate (OMP) decarboxylase. To test heterologous gene expression in dpyrF, the lactate dehydrogenase (LDH) gene (T-ldh) from Thermoanaerobacter pseudethanolicus ATCC33223 was electroporated into dpyrF with a promoter of the glyceraldehyde-3-phosphate dehydrogenase (G3PD) gene of M. thermoacetica ATCC39073. The resulting transformant successfully produced 6.8 mM of lactate from fructose. To develop a transformation system without auxotrophy, a thermostable kanamycin resistant gene (kan^r) derived from the plasmid that Streptococcus faecalis harbored was introduced into M. thermoacetica ATCC39073. By using kan^r with promoter of endogenous G3PD gene as a selection marker, we succeeded at the transformation. Using the developed system, we successfully constructed acetate-deficient, lactate producing mutant by deleting phosphotransacylase gene candidates and introducing T-ldh.

View full abstract

Glucose production of moso-bamboo by enzymatic hydrolysis combined with hot-compressed water (HCW) treatment was investigated. Cellulose in moso-bamboo was treated with percolator type reactor at 280℃. The obtained solubilized products were easily converted to mono-saccharides by the enzymatic treatment. The yield was 65% on cellulose base.

View full abstract

We developed a lignin-derived adsorbent for fermentation inhibitors and one-pot SSCF (Simultaneous Saccharification and Co-fermentation) process using the adsorbent. The adsorbent was made by optimized thermal treatment of the residual lignin obtained by microwave (MW) pretreatment of Eucalyptus globulus wood and subsequent enzymatic hydrolysis or SSCF processes. The soluble fraction separated by the MW pretreatments contained furfural, 5-HMF and lignin degradation products, but the treatments with the adsorbent intensively decreased concentration of the inhibitors without loss of monosaccharide concentration. To establish in situ detoxified SSCF process, the pretreated biomass was hydrolyzed with cellulolytic enzymes in the presence of the lignin-derived adsorbent. It was found that concentration of the inhibitors intensively decreased but the reducing sugar yields was not affected by the presence of the adsorbent. Therefore, one-pot SSCF process with Zymomonas mobilis and the adsorbent was examined, and bioethanol was successfully produced at the ethanol concentration over 5 wt%. The new process produces no wastes and needs no purchase materials. The adsorbent is recyclable and the process relieves load of waste water treatments because the organic compounds in the soluble fraction is removed and converted to energy.

View full abstract

Recycling of cellulase is an important process for decreasing enzyme cost. Cellulase adsorbed onto saccharification residues of lignocellulose, especially onto lignin, is unproductive and can be a significant problem for recycling enzyme. Therefore, a reliable determination of lignocellulose-adsorbed cellulases is necessary. Typically, the amount of adsorbed cellulase has been indirectly calculated by quantifying the cellulase in saccharification liquor using colorimetric methods such as Lowry and bicinchoninic acid (BCA), however, these methods have potential problems of false positive or negative. In this study, the nitrogen contents in the residue based on elemental analysis were applied for the determination of cellulase amount adsorbed onto the residue. It was estimated that approximately 72% of loading cellulase is adsorbed on the residues after 72 h enzymatic hydrolysis of ball-milled Japanese cypress based on the colorimetric method; meanwhile, 31〜36% is adsorbed onto the residues based on nitrogen content. Significant difference was observed between both methods.

View full abstract

Hydrolysis of the lignocellulosic biomass is the rate-limiting step in biogas production. In this study, rapeseed stems were used as a model of plant biomass, and were pretreated with rumen fluid. Rapeseed was solubilised by rumen-fluid treatment, resulting in production of volatile fatty acids. Methane fermentation of 6-h-treated rapeseed was performed; higher methane yield was obtained compared with untreated rapeseed, showing a significant pretreatment effect. Rumen fluid has higher endo- and exo-glucanase activities and non-phenolic lignin unit oxidising capacity, compared to methane sludge. Therefore, lignocellulose components were effectively degraded by rumen-fluid treatment, resulting in increased methane production.

View full abstract

Wood biomass is promising resource to obtain energy and various chemical products through its degradation. We have developed several elementary techniques to study wood biomass with solution NMR. First, we develop a new way of sample preparation. Second, Transverse relaxation optimized spectroscopy (TROSY) gave high resolution signals of the key structures contained in the whole wood, branched or conjugated form of lignin. Finally, we develop the method to accurately quantify the components of wood biomass. We used this method to monitor the biodegradation of wood biomass by fungi. Selective degradation of either cellulose or lignin depending on a kind of fungi used was successfully detected. A key metabolite for a selective degradation has also been detected with the assist of ^<13>C labeling. Thus, our NMR method has a wide range of application to identify various components of wood biomass and to monitor their conversion.

View full abstract

Pyrolysis of biomass is one of the effective methods to give additional value to biomass. In this study, Japanese ceder (Cryptomeria japonica) and Moso bamboo (Phyllostachys heterocycle f. pubescens) were used as typical resources in Japan. Pyrolysis of the biomass was conducted with laboratory pyrolyser under various pyrolysis conditions to estimate the effects of pyrolysis temperature on the bio-oil composition. The results shown that the major pyrolysis products were Levoglucosan, Furans and Guaiacol derivatives. Those compounds were known as valuable products, and the yield of those products was higher at 480 ℃ pyrolysis. It is known that increasing the pyrolysis temperature accelerates the demethylation and demethoxylation. Thus, the production yield of the phenol and catechol were increased as raising temperature. Yield of flammable gas (H_2, CO, CH_4) was increased with increasing pyrolysis temperature, and char yield was decreased (39.3-22.6 wt%).

View full abstract

Recently, biomass has been attractive as one of the renewable energy resources. Bio-oil produced by fast pyrolysis of biomass is considered to be a new resource as a substitute fuel oil. The bio-oil includes more than 100 kinds organic matter, and consisted of low molecule compounds from Lignin and polysaccharides. The formation mechanism of oil components, which derived from pyrolysis of polysaccharides is less well known. Therefore, the mechanism of Levoglucosan (LGA), Furfural (FF) and 5-hydoxymethylfurfural (HMF) was estimated in this study. The result shows that the yields of LGA was decreased by mixing pyrolysis of α-Cellulose with compounds derived from hemicellulose (ex. Glucronic acid or Xylan). On the other hand, it was revealed the yield of LGA less was decreased by mixing pyrolysis of α-Cellulose with compound derived from lignin (ex. Coniferyl alcohol).

View full abstract

The effect of metal-modified zeolite catalysts on the pyrolysis behaviors of jatropha waste was examined. At 600 ℃, ca.72 % of aromatic hydrocarbons with other by-products was produced in the presence of PtPd/H-ZSM-5(30) catalyst. The aromatic selectivity is dependent on the zeolite-type and the order was H-ZSM-5(30) > Beta(22.5) > USY(20). Catalyst regeneration behaviors depend on the pore structure and solid acidity. The ZSM-type with 10 membered-ring (MR) favors reaction outer surface, while the USY and Beta-types favor the reaction inside pore. Efforts have been made to improve bio-oil yield and to try oil up-grading.

View full abstract

The crude bio-oil contains a high proportion of oxygen and for their effective use hydrodeoxygenation (HDO) is required. Base metal phosphides such as Ni_2P and CoP exhibited remarkable activity for HDO of pyrolysis model compounds, 2-methyltetrahydrofuran (2MTHF) and guaicol. Ni_2P/SiO_2 catalyst could deoxygenate 2MTHF and guaiacol into corresponding compounds, n-pentane and benzene. Kinetics indicate 2MTHF and hydrogen are competitively adsorbed on surface via Langmuir-Hinshelwood mechanism. The presence of water vapor did not affect the performance of the catalyst. Furthermore, the 2MTHF HDO activity of Ni_2P/SiO_2 remained unchanged for 30 h reaction.

View full abstract

The iron making process, especially pig iron making process discharges the huge amount of CO_2 because coke made from coal is used as a reductant. For this reason, steel industry discharges the largest amount of CO_2 and it occupies about 13% in Japanese emission. This paper focused the woody biomass substitute for coke in pig iron making process and studied reduction characteristics of iron oxide when heated iron oxide and woody biomass mixed sample in N_2 atmosphere. In addition, we aim to clarify the reduction characteristics of iron oxide by volatile matters in woody biomass.

View full abstract

Lignin as a model compound of fermentation residue derived from bio-ethanol production would increase with the expanded use of unused rice straw in the future. In the previous study, we concluded bio-hydrogen production through gasification is highly feasible biomass energy conversion system. Hence, the production of bio-hydrogen through gasification using the residue is a key technology to improve energy efficiency of biomass energy utilization. In addition, desulfurization of bio-hydrogen is absolutely essential to utilize bio-hydrogen as alternative energy. In this study, we conducted an experiment of gasification of lignin with high moisture for the hydrogen production and we determined the quantity of the sulfur compounds absorbed in the NiO/Al_2O_3 catalyst from the product gas by SEM-EDX. As a result, 31 % sulfur compounds in the product gas was captured on the surface of the catalyst. This experimental data would be available for design a hydrogen production process with sulfur removal effect due to poisoning catalyst.

View full abstract

The woody biomass is attracted attention as an oil alternate energy. The direct liquefaction of woody biomass to produce liquid fuel has been carried out by using a small size autoclave. The waste plastics were co-liquefied with woody biomass and a part of liquid oil could re-used as solvent of wood carrier. The effect of additive plastics gave to the liquefaction properties and the solvent property was considered.

View full abstract

This study analyzes the representative chemical compounds in bio-oil derived from pyrolysis of palm kernel shell with three particle sizes of 0.15-0.50, 0.50-1.00 and 1.00-2.00 mm. Fast pyrolysis was carried out in our newly designed fluidized bed reactor of 108 mm in internal diameter operated at 450 ℃ with nitrogen gas with flow rate of 21-25 L(NTP)/min. Vapor products from the pyrolyzer were collected by six successive condensers maintained at three temperatures; 28 (1st), 5 (2^<nd>) and -10 ℃ (the rest). The bio-oil yields in an ascending order of particle size were 19.2, 36.0 and 26.5 %, respectively. The compounds quantitatively analyzed in the bio-oils were acetic acid, phenol, furfural, 2-methylphenol, 4-methylphenol and 4-methylnaphthalene. Predominant effects to affect the bio-oil yield are discussed.

View full abstract

In this study, Palm Kernel Shell (PKS) was gasified in a fixed-bed gasifier, using air as the gasifying agent. Whole apparatus including gasifier, material hopper, feeder, etc. were put inside a pressure vessel. Experiments were conducted at 0.1MPa, 0.3MPa, 0.5MPa, 0.7MPa. As a results, produced CO & tar amount showed to decreasing tendency with pressure increasing. Conversion rate to products within high heating value was also discussed.

View full abstract

Chemical-looping process is a prospective energy conversion system with cost-effective CO_2 separation and efficient H_2 production. To accomplish this process and make this process more efficient, oxygen carrier with high-speed oxygen exchange has to be invented. Specifically, to achieve high-efficiency H_2 production, the reaction rate and the reaction ratio of oxidation of the oxygen carrier are significant. Therefore, the reaction rate and the reaction ratio of redox reactions of various oxygen carriers were investigated, and the reaction ratio of oxidation under the condition with various temperatures and partial pressure of H_2/H_2O was also investigated.

View full abstract

To increase the energy conversion performance of Direct Chemical Looping Process, new oxygen carriers was developed. In this study, reduction performances of ten different types of oxygen carriers were evaluated with TG analyzer. Fe-calcium base oxygen carrier containing nickel showed better reduction performance than the others.

View full abstract

Molybdenum carbide has been prepared by in-situ solid state reaction. In this work, we investigated molybdenum carbide formation from precursors deposited on solid carbon supports (dried cedar) and their catalytic activity in steam reforming of tar. Molybdenum carbide was successfully prepared at carburization temperature of 800 ℃. The as-prepared Mo_2C catalysts showed a good catalytic activity for tar reforming. When 20wt% of Mo was in-situ deposited on dried cedar support, the hydrogen yield increased about 5 times. The effects of reaction temperatures on the gas production yield were also investigated.

View full abstract

Ashes from various kinds of biomasses were added and mixed with low-rank coal in order to investigate its catalytic effect on coal gasification. Gasification was performed in a fixed bed downdraft reactor at relatively low temperature under argon atmosphere using steam as gasifying agent. The effect of ash variation and its amount were tested in term of gas production and carbon conversion. Seaweed ash from brown seaweed showed the highest catalytic activity among the tested ashes. Char production decreased and gas production increased when ash was added to the coal sample. The catalytic effect of the ash was attributed to the high content of alkali metal in the seaweed ash. Even though decreasing gasification temperature could decrease the activity, the effect of ash addition was still found at low temperature. Therefore, biomass ash could be considered as an attractive option for a low cost and environmentally friendly coal gasification catalyst.

View full abstract

This work studied a three reactors circulating fluidized bed biomass and coal co-gasification process. The three reactors circulating fluidized bed is constructed by a tar reforming reactor, a gasifier and a combustor. The circulating material is CaO made from limestone. The CaO works like heat transfer material, tar reforming catalyst, CO_2 sorbent, and sulfur sorbent.

View full abstract

Three tower (3-T) CFB biomass-coal co-gasification process by using CaO particles as circulating material was investigated with Aspen plus. The 3-TCFB co-gasification model was developed for expecting high efficiency. Process analysis results show that with coal/biomass supply ratio increased from 0 to 0.2, gasification cold gas efficiency was increased from 52% to 71%. A model combined gasification and FT synthesis was also produced to investigate the effect of FT off-gas recycle. With off-gas recycle from FT synthesis to the reformer of the 3-T CFB, cold gas efficiency can be up to 78% as well as liquid fuel product efficiency up to 53.9%.

View full abstract

Biomass is energy sources important because of its carbon neutrality. Because of high gathering cost of biomass, the small scale biomass gasification system is required to utilize biomass at local area. In this study, the small scale gasification system has been developed using molten carbonate as a thermal and chemical catalyst. As a result of gasification test using pine pellets, high calorific syngas over 13MJ/Nm^3 (HHV basis) can be produced.

View full abstract

Effect of tomyamkun on hydrothermal pretreatment of rice and cellulose for ethanol production was investigated. Tomyamkun soup was added to the cellulose or rice slurry in the batch reactor, which was heated to the target temperature. Increase in glucose yield was observed by adding tomyamkun.

View full abstract

Hot compressed water was delivered to the packed bed of cellulose powder so that cellulose was dissolved into hot compressed water. Total organic carbon in the effluent was determined so that information on cellulose dissolution under hydrothermal condition could be obtained. The effluent was also analyzed by high-performance liquid chromatography. 2.5 g/L of total organic carbon was achieved at 300 ℃.

View full abstract

For supercritical water gasification of various compounds, it is expected that organic acid is an important intermediate, and thus its decomposition characteristics are of importance. We conducted supercritical water gasification of acetic acid using a continuous reactor, at 350, 400, 430 ℃, 25 MPa. The liquid and gas products were analyzed by TOC, HPLC and GC. The reaction rate parameters of acetic acid was thus determined.

View full abstract

Supercritical water gasification (SCWG) was conducted for the mixture of guaiacol and formic acid to investigate whether there is some interaction between these compounds. The experiments were conducted by using a tubular flow continuous SCWG reactor apparatus. Reaction temperature, pressure, and residence time were, 390 ℃, 25 MPa, and 9.6 s, respectively. The carbon gasification efficiency decreased with the concentration of guaiacol in the feedstock, the mixture of formic acid and guaiacol. Gas composition was not affected by the guaiacol concentration. No interaction between guaiacol and formic acid was observed under the condition studied here.

View full abstract

In supercritical water gasification of biomass, lignin retards gasification of biomass. In this study, we investigated the decomposition of glucose with guaiacol, model compound of lignin, in supercritical water. The pressure was kept constant at 25 MPa. Interactive effect made char production from glucose at subcritical temperature and that from guaiacol at supercritical temperature suppressed.

View full abstract

It is important to determine the heat of reaction for subcritical water chemical processes. However, measurement of heat of reaction has not been conducted under hydrothermal condition. The purpose of this study is to measure the heat of chemical reaction under hydrothermal condition with residence time. The reactor is an insulated tubular reactor of stainless steel. Glucose was decomposed in subcritical water, and temperatures on flow are measured so that the heats of reaction along the flow are determined. The reaction is conducted at 350 ℃ and 23 MPa for the glucose concentration of 0.014-0.085 M.

View full abstract