In the present study, the behavior of nitrogen compounds in the coal gasification was investigated. Nitrogen conversion ratios from the pulverized coal particle to char, soot, and gas in the gasification with CO2, H2O, and O2 were obtained using a pressurized drop tube furnace. The results show that ratios of the nitrogen released from the coal had a correlation to ratios of the released carbon. In the H2O gasification, the nitrogen conversion ratio to NH3 increased with the increase of the carbon released ratio. In the O2 gasification, the nitrogen compounds were mainly converted into N2.
In this study, a novel biomass IGFC system with exergy recuperation for power generation was studied by Aspen Plus commercial software. A circulating fluidized bed gasifier system including a f ast pyro ly sis process and a heat-exchangeable-type bio-oil reformer with nickel-based catalyst s was designed. The small amount of char produced from the fast pyroly sis was completely combusted to provide the heat for the pyrolyzer Meanwhile t he large amount of volatile was assigned to two parts, one (69.2%) was reformed to syngas and the other (30.8%) was combusted to supply heat for the catalytic steam reforming process. The generated gas fuel s were converted to electr ic power via SOFC, gas and steam turbine s . The results demonstrate that the exergy efficiency is about 62.91% and the power generation efficiency can reach as hig h as 56. 77 % which was the twice higher than conventional biomass-fueled power plants.
In slagging gasifiers, the ash flow down the gasifier walls and dra ine the gasifier as a molten slag . The b ehavior of the molten slag depend e on coal type . Coals choosed for slagging gasifiers should thus have an ash fusion temperature below the operating temperature of the gasifier ; thus evaluation of t he ash fusion temperature is important to operate stable the gasifier The estimation of the ash fusion temperature was performed by using Factsage 7.2 that is the thermodynamic equilibrium calculation software. And more the ash viscosity was estimated by Modified Urbain Model or Viscosity Module o f Factsage 7.2 . The equilibrium ash fusion temperatures w ere cal c ulated con s ider ing the equilibrium gas composition for 4 coals. The estimated ash fusion temepratures were different from JIS measurement results. Viscosity Module was good agreement with the ash viscosity measurement results u sing high temperature furnace.
Dust particles exist oftenin the high-temperature furnaces and influence the radiative heat transfer or temperature measurement accuracy of radiation thermometer. In this study, radiation properties of cement clinker dust particle cloud was measured spectroscopically in cold and hot models as an example of dust suspending in the furnaces. The properties were evaluated in the term of extinction efficiency to ignore the effect of particle concentration. The extinction efficiencies were not almost influenced by temperature in the range of the room temperature to 740°C. They were also well correlated to the result analyzed based on Mie’s theory using complex refractive index determined from the reflection measured on cut surface of particles fixed with resin.
In coal-fired power generation, De NOx catalysts are known to deteriorate over time, but its mechanism has not been clarified yet. According to the previous research, it has been found that amorphous silica forms a thin layer on the catalyst surface, which composition are much different from those of coal ash. It implies that coal ash itself does not adhere on the surface of the catalyst, but Si compounds in the gas deposits to the catalyst. In order to confirm this consideration, deposition behaviors of vapor Si compounds to the catalyst surface were examined, and its effect on the catalyst performance was investig ated. High volatile siloxane was selected to simulate vapor Si compounds in exhaust gas. Two kinds of experiments are conducted, such as exposure and immersion tests. In the former, test pieces of the catalyst were exposed to siloxane vapor. In the latter, test pieces were immersed in liquid siloxane and calcined afterward. The amount of silica deposition on the surface of the catalyst was analyzed by SEM / EDX. In the catalyst performance evaluation test, dete rioration of the catalyst by silica adhesion wa s confirmed.
In a series studies on development of an advanced desulfurizatio n and denit r o gen ation process of heavy hydrocarbon resources under mild conditions effect of coal type on removal behavior of sulfur and nitrogen was investigated for coal extracts by using imi dazolium type ionic liquid. Sulfur and nit rogen in the coal extracts were simultaneously removed during extraction by the ionic liquid. Nitrogen removal depends on the coal type and nitrogen in the coal extracts prepared from high rank coal was easily removed.
We tried to make a good mixed solvent for an asphaltene using poor solvents of hexane and benzyl benzoate, which are suggested by Hansen solubility parameter (HSP). The solubilities of asphaltene were measured in the mixed solvents at various mixing ratios. As a result, the solubility showed the maximum at the mixing ratio with δd, δp, and δh of 19.1, 4.2, and 4.3 MPa0.5, respectively, which are almost the same as the HSPs of asphaltene. At the best mixing ratio, the small-angle X-ray scattering intensity at scattering parameters of >1 nm–1 disappeared, meaning that the amounts of asphaltene nanoaggregates drastically decreased in the solvent system. All the results indicated that the HSP concept can propose the best mixing ratio of solvents even using poor solvents, which enabled us to control asphaltene aggregation behavior. It is surprising that the addition of poor solvent (hexane) enhances the asphaltene solubility and dispersibility. These interesting phenomena may give us important information to understand asphaltene molecules and their aggregation behavior.
Coal fly ash with a high degree of heavy metal elution was produced by a laboratory scale pulverized coal combustion furnace. As the melting point of ash decreased, the elution volume of the boron increased. The relationship between heat treatment conditions for detoxification and elution was investigated. The heat treatment temperature increased along with the increasing elution volume of the boron. The detoxification condition was formulated successfully according to the amount of elution.
Mercury form analysis was carried out by using temperature programed desorption and cold vapor atomic absorption spectrometry. Model samples of mercury-adsorbed carbon were prepared using activated carbon and unburned carbon separated from coal fly ash. The mercury of adsorbed by unburned carbon (UC-Hg) and activated carbon (AC-Hg) showed different desorption temperature. The TPD curves of UC-Hg and AC-Hg were changed with concentration of mercury in the liquid during adsorption. Considering both forms of UC-Hg and AC-Hg, the quantitative analysis of various mercury forms in desulfurization gypsum can be achieved.
Chemical forms of mercury in fly ash produced from the coal-fired power plant were analyzed. A combination of temperature programmed desorption (TPD) and cold vaper atomic absorption spectrometry (CVAAS) was applied to clarify the chemical forms of mercury. The mercury forms were determined by comparing to the peak temperature and linear combination of TPD curves of model mercury compounds. The results showed that abundance ratio of mercury forms differed depending on the fly ash. Even if the amount of mercury in fly ash was less than few ppm, the combination of TPD and CVAAS could be applied for qualitative and quantitative analysis of mercury in fly ash.
Coal ash contains hazardous elements such as arsenic, boron, chromium, and selenium. These hazardous elements easily leach into the environment. In order to control their leaching, the aging of coal ash were developed, recently. In this study, the effect s of ash composition, such as calcium content in original coal ash, onto the immobilization ability of arsenic, boron, chromium, and selenium in the aged coal ash was investigated using simulated coal ash samples which have various calcium contents. When high calcium containing simulated coal ash samples were aged for a week, the leaching amount of arsenic, boron, and selenium from the simulated ash samples was effectively reduced and the formation of ettringite was observed on the surface of aged ash samples. From the results, the contribution of ettringite formation to the immobilization of hazardous elements was suggested.
This paper reports a numerical study for a singl e shell and tube rea ctor of CO2 methanation with a 1.5 m long reaction zone. A new conjugate heat transfer solver is developed based on the open-source OpenFOAM code. The newly developed solver solves the heat transfer problem as well as the reactions happen in the gas phase. The reactor is meshed with fully resolved gas, solid, and coolant regions , Two-temperature model is considered to solve the temperature of catalyst bed . The tube diam e ter is changed to investi gate the effect on the hot spot formation. The results show that the diameter of the tube is an important factor in determining the tem perature profiles of the catalyst bed as well as reacting gas. The peak t emperature of the hot spot was decreased from 980 to 770K with decreasing the tube diame ter from 32 to 14mm at a GHSV=3428h-1.
Carbon dioxide capture and storage (CCS) is expected to play a role in combating global warming. Thus,
research and development are progressing around the world. However, there are limitations such as the
demonstration examples being limited to cases where the CO2 capture site and storage site are close. In recent years, Carbon dioxide Capture and Utilization (CCU) using captured CO2 has attracted attention.
This time, we will focus on technologies that reduce CO2 and convert it into fuels and chemicals, mainly focusing on methanation. Energy saving can be achieved by integrating the CO2 capture process and the CO2 utilization process.
In this paper, we report the results of energy calculation in the CO2 separation by the new process using the phase-separated type CO2 absorbent developed so far, and the experimental results of continuous operation using this process.
Currently, the proportion of fossil fuel in the primary energy supply in Japan is very high. So, the use of renewable energy is collecting a lot of attention as an alternative to fossil fuel. Biomass, a type of renewable energy, has the advantage of carbon neutral. On the other hand, Biomass has the disadvantage of low power generation efficiency when using power generation because of the low energy density. From these backgrounds, biomass co-combustion for coal fired power generation has been focused on. In this study, co-combustion experiments of pulverized coal and biomass samples were carried out, in order to investigate the effect of mixture ratios and types of biomass samples on co-combustion behaviors.
In this study, we investigated the catalytic activity of Ni catalysts supported on hydroxyapatite with different Ca/P (Ca/P=1.4 and 1.8 ) for decomposition of biomass tar. The Ni /HAP catalysts (Ni/HAP14 and 18) showed the high catalytic activity for decomposition of biomass tar derived from pyrolysis of Japanese Cypress. Furthermore, The introduction of steam during biomass pyrolysis reduced carbon deposition and increased H2 yield. Specifically, the higher Ca/P was effective to proceed the steam gasification of deposited carbon.
Ferro-coke is an innovative iron making process expected to achieve energy saving by low reduction agent ratio (RAR) operation in the blast furnace. Asphalt Pitch (ASP) was selected as one of appropriate binder to make high-strength ferro-coke. However, it is concerned that ASP will be short of supply in the phase of industrialization. Therefore, it is necessary to develop a new binder to respond to the demand. We have been developing the Hyper-coal (HPC) process, which produces a low ash coal by adopting solvent de-ashing technology. The binder effects between new binder (HPC) and ASP were compared by measuring strengths of ferro-coke in this study. It is considered that the new binder can be applied as the ferro-coke binder to enhance the strength.
Decreasing pushing force is one of the most important issues for extend coke oven life and stably operating at old coke oven. Especially, pushing force depends on clearance due to lateral shrinkage during carbonization in coke oven. In this study, quantifying lateral shrinkage of coke cake which is made of test coke oven is proposed by using photo-Images processing. It showed there is a high correlational between shrinkage factor (ER;ASTM) and lateral shrinkage rate. In addition, low temperature of coke decreases horizontal shrinkage rate, so narrow lateral shrinkage increases pushing forece.
In recent years, the need for CO2 reduction in blast furnaces has been increasing, and therefore steel companies have been making efforts to reduce reducing agent ratios. In order to realize the reduction of the reducing agent ratio, there is a method of reducing the amount of coke by using coke having higher reactivity than conventional coke. We expect that the addition of flyash to coal enables the production of highly reactive coke with catalytic effect. Therefore, We carbonized coal blended with flyash and measured coke strength, particle size, and reactivity. As a result , it was found that the strength was improved at addition of 3% and that it was possible to maintain the strength as the base at addition of 10%. It was also found that the coke particle size increased and the reactivity improved as the flyash additive rate increased.
To improve quality of sludge fuel, we proposed a carbonization process of sludge and coal. We conducted the co-carbonization experiment under various carbonization conditions. In carbonization experiment, we used dried sludge and coal as sample, and the sample ratio and carbonization temperature were changed. As a result, the interaction of both samples was not observed on char yield and tar yield in 673K and 873K temperature. However, these yields were lower than theoretical value in 1123K.
To develop a new blending technique which can control coal compatibility, we focused on surface tension of softening coals which probably affects adhesion phenomena between coal particles. However there is no method to measure the surface tension of coal a t softening temperature. In this study, to overcome this difficulty, we devised a method to measure surface tension of semi cokes obtained by heat treatment of coals at 500°C as a substitute for softening coals. We investigated the relationship between str ength of coke and standard deviation of the surface tension distribution which is a new proposed factor calculated from the surface tensions of single coal brands used in the coal blend. As a result, the larger standard deviation of the surface tension dis tribution among coal blend , the lower strength coke was produced.
Coal fluidity is an important parameter in coal blending techniques for coke making because it strongly influences coke qualities. On the other hand, the amount of high fluidity coal has been limited and generally expe nsive. To cope with this problem, caking additive method which improves fluidity of coal has been developed and commercialized. It is important for the development of more effective caking additives to clarify the effective chemical substances on coal fluidity. Therefore, in this study, we investigated effect of four kinds of aromatic amines on coal fluidity and coking property of coal . Coal fluidity ameliorated with increasing the molecular weight of aromatic amine, and N,N'-di-2-naphthyl-1,4-phenylenediam ine (DNPD) was the most effective aromatic amine in this study. Carbonization tests in an electric furnace were conducted to investigate an effect of DNPD on coke strength. As a result of adding only 1wt% DNPD, fluidity of blended coal and coke strength (D rum Index) were highly improved.
Changes in chemical structure of coal during carbonization are important factors to determine properties of softening and melting. It is believed that the caking properties are directly affected by transferable hydrogen, and its consumption lowers the degree of caking. Investigation of the fate of the hydrogen during carbonization is thus necessary for understanding the characteristics of caking. This work conducted quantitative analyses of the chemical structure of coke derived from caking and non-caking coal, together with an online gas analysis. As a result, the transferable hydrogen derived from the non-caking coal was partly consumed for decomposition of the functional groups such as ethers during carbonization, while that from the caking coal was little consumed.
To characterize the chemical structure of oxidi zed coal, solid state1 H and 13C NMR spectra were acquired for t wo kinds of coal Y and Z before and after estimation of their self-heating property by using R70 apparatus. It was found that coal Y with low er carbon concentration reached 70ºC in shorter time than coal Z. I t is indicated that some aldehyde and ketone were generated and aromatic carbnons combined to hydrogen consumed during the oxidation. Furthermore, measurement of gas species generated during oxidation at 80°C in 18O2 atomsphere by multi-turn tme-of-flight mass specrometer indicated that C16O and C16O2 were mainly released from coal Y. It is suggested that decomposition of aldehyde and carboxylic acid might competed with generation of aldehyde and ketone at less than 80°C.
Since April 2012, Osaki CoolGen Project has been being conducted as an ”Integrated coal Gasification Fuel Cell combined cycle (IGFC) demonstration project” with the support of Ministry of Economy, Trade and Industry (until 2015 FY), and New Energy and Industrial Technology Development Organization (from 2016 FY). This project consists of the following three steps. In the Step 1, oxygen blown IGCC (Integrated coal Gasification Combined Cycle) was demonstrated. In the Step 2, IGCC with CO2 capture is being demonstrated. In the Step 3, IGFC with CO2 capture will be demonstrated. Demonstration of the Step 1 was conducted from March 2017 to February 2019. Development targets of plant efficiency, environmental performance, reliability, operability, coal variety compatibility and economic efficiency were achieved. This paper describes progress of Osaki CoolGen Project.
Research and development on co-gasification of coal and biomass has been developed as an efficient biomass energy conversion process Inco-gasification the reactions of coal and biomass influence each other however there are few reports estimating the co gasification rate from the in dependent gasification rate of coal and biomass In this study thermogravimetric analysis was conducted and the gasific ation behavior of chars were compared By mixing the biomass and coal together the gasification behavior of mixing char was totally different and the biomass mixing promoted the gasification rate significantly
Coal pyrolysis is an important reaction that has much influence on initial situations in coal combustion and gasification processes. We have developed a pyrolysis model, Ex-CPD model that can determine specific light gas and tar molecules. However, the structure parameter of aromatic nucleus that the previous Ex-CPD used increased as decreasing aromaticity index, fa. Therefore, we modified the procedure of determining the structure parameters.
Furthermore, kinetic parameters of decomposition of a labile bridge were adjusted. As a result, the volatile matter calculated by the Ex-CPD model increased as heating rate increased. The Ex-CPD model was used to predict char, soot and light gas yield in coal gasification. The calculation results showed good agreement with the experimental results, especially soot yield tendency to each gasifying agent.
To induce discussions on coal utilization’s future by facing up to reality, coal phaseout issue is discussed. First, 2030-2050 scenario for decarbonization depending only commercialized technologies is examined to confirm that coal phaseout is indispensable. Second, some major technical possibilities including IGCC and CCS are examined to confirm their difficulty. To conclude, it is suggested that coal phaseout scenario should be developed from a wider perspective of East Asia and Oceania region with more concern on energy security and transition to RE100 in the future in this region.
Tar evolved from coal pyrolysis contains polycyclic aromatic hydrocarbons (PAHs) that grow to soot through further aromatization in parall el with its reforming during gasification. Understanding of the chemistry and kinetics in a gasifier is important for developing low-temperature gasification. This work focused on numerical simulation of PAH reforming and soot formation in various coal typ es and gasification modes. A detailed chemical kinetic model was used for simulating a reductor of a two stage entrained flow gasifier under the gas composition determined by combination of experimental molecular composition of coal and inorganic gas compo sition at chemical equilibrium. O2/CO2-and O2 /H2O-blown modes significantly reduced the yield of PAHs and the formation of soot. Growth of soot particle was dominated by acetylene addition above 1300°C, while nucleation of soot precursors and PAH condensat ion became dominant at lower temperature.
A numerical simulation of coal gasification coupled with a slag flow on a coal gasifier was performed to demonstrate the capability of the multi-physics and multi-scale modeling and simulation. For the gas-particle two-phase reacting flow simulation for the gasification reaction was based on the large-eddy simulation (LES) with the Eulerian-Lagrangian approach. For the gas-liquid two-phase flow simulation for the molten slag flow was based on the Volume of Fluid (VOF) method. A laboratory-scale coal gasifier was targeted and the numerical results were validated by comparing with the experimental data for the gasification reaction. The molten slag flow on the gasifier inner wall was observed precisely. It was confirmed that the present numerical procedure could predict qualitatively the gas-particle-liquid three-phase reacting flow within the entrained flow coal gasifier.
Ammonia is considered as one of promising energy careers in the future. One of applications using ammonia as fuel is introducing ammonia in coal fired boilers. To realize the utilization of ammonia in coal fired boilers as a fuel, it is necessary to clarify the mixing combustion characteristics of ammonia and coal. In this study, the turbulent spherical flame propagation characteristics of ammonia / coal particle cloud mixture were investigated. Under the various turbulence intensity and the types of coal, the spherical flame propagation experiments were conducted. Experimental results revealed that in some conditions, the flame propagation velocity of the mixture of ammonia / coal particle cloud / oxidizer is higher than that of the mixture of ammonia / oxidizer or that of the mixture of coal particle cloud / oxidizer. This means that there is an interaction mechanism between the ammonia / oxidizer flame and the coal particle cloud / oxidizer flame. The findings from this study can be utilized for establishment of the mixing combustion model of ammonia and coal particle cloud.
As a CFRP recycling method, CFRP is pyrolyzed to separate the resin and carbon fire d In this method , it has been empirically revealed that the p roperties of pyrolyzed CFRP affect the next firing of residual resin process . Therefore, in this study, CFRP was pyrolyzed under various pyrolysis conditions, and the properties of pyrolyzed CFR P were evaluated . As a result, it was revealed that the pyrolysis temperature and the heating speed conditio n s have a great influence on the properties of the product of pyrolyzed CFRP.
It is thought that displacement of coke oven wall caused by internal gas pressure decreases lateral shrinkage, and effect to coke pushing force. We measured internal gas pressure and displacement of oven wall and pushing force of commercial oven, under different gas pressure of coal blend. Wall displacement caused by internal gas pressure of plastic layer at oven center, but pushing force increased with increase in gas pressure. Decrease in lateral shrinkage of high gas pressure coal blend influenced increasing pushing force.
It has been reported that addition of organic compounds to a caking coal affected coal dilatation. However, the effects of organic compounds on coal dilatation has not been studied at the molecular level. In this presentation, the density of model coal structure with the various organic compounds were calculated using a molecular dynamics simulation. As a result, the simulation showed that the organic compounds added to the caking coal reduced the density of model coal structure. Furthermore, it was confirmed that there was a good correlation between the calculation results and the experimental results.
Since coal is a mixture of various aromatic rings, aliphatic chains, and functional groups, its fluidity could not be understood from a chemical point of view. We represented the average formula of coal by CHmOn and succeeded in estimating the enthalpy of formation of coal. It is noteworthy that m of CHm On is determined by the numbers of H and C atoms in aromatic ring and side chain of coal. We prepared a table that describe the values of H/C of carbon skeletons consist of various aromatic rings and side chains systematically. We searched for a value of H/C closest to m in this table and presume the number aromatic rings and the form side chain, followed by estimation of carbon skeleton model of the coal, and studied the relationship between the fluidity of coal and its structure of aromatic ring.
A subbituminous coal was treated with a non-polar solvent or polar solvent, for 1 hr or 2 hr at 673K or 693K under nitrogen, in order to chemically upgrade the low-rank coal. A 1-methyl naphthalene (MN) was used as non-polar solvent and wash oil (WO) and Super-Solvent (SS) which is the more polar solvent used as polar solvent. In case of polar solvent as the treated solvent, the extraction yield at 1 hr at 673K reached 66.0 and 62.3 mass%, daf in WO and SS respectively, however, some of polar solvent remained in the extract because the polar solvent contained polar compounds of 8.5 and 21.7 mass% in WO and SS respectively. The extraction yield with MN at 673 K was 41.2 mass%, daf and it decreased with an increase in the severity of the extraction condition; it was 36.3 mass%, daf at 693K for 2 hr. However, the H/C and O/C ratios of the MN upgraded coal became the similar level as those of caking coals at 693K for 2 hr. Decarboxylation and aromatization reactions might occur during the solvent treatment.
In this study, zeolite-alumina composite supports were prepared using alumina as a mesoporous matrix component. Nickel, molybdenum and platinum were added into the supports by a conventional impregnation method and then the catalysts were sulfi ded with hydrogen sulfide. We examined the effect of pore structure and acid site s on the activity and the selectivity of products in the dehydrocyclizatio n cracking reaction of soybean oil From FT-IR measurements of liquid products, all catalysts showed 100% conversion at 580°C even under the condition 0.5 MPa. Alumina was found to be optimal for the matrix component. Pt/NM/ β (11)75Al(sg) showed the lower gas selectivity of 19 wt%, the higher transport fuel (C5-C18) selectivity of 66 wt %, the aromatic yield of 13wt % under the condition 0.5 MPa and 580 °C
A TiO2-TeO2 glass prepared by adding titanium oxide to tellurium dioxide was prepared using a melt quenching method, and after the surface was crystallized, a Pt/TiO2-TeO2 photocatalyst was prepared by a conventional impregnation. Investigation of crystallization behavior during surface heat treatment and a photocatalytic degradation reaction of me thylene blue as a water soluble component model of coal were con ducted 0.1Pt(450)/25Ti75Te(600) 600), where 0.1wt% of Pt was supported at 450°C after crystallizing 25Ti75Te glass at 600°C, showed the highest decomposition rate. Moreover, when the integral strength of the crystal phases of major TiTe3O8 and α-TeO2 increased , the photocatalytic activity tended to increase.
Carbon-oxide-supported cobalt catalysts using ZrO2 and CeO2 were prepared by the sol-gel method using polyethylene glycol as a carbon source and zirconium alkoxide and their reactivity of steam reforming of ethanol was investigated. The hydrogen yield was improved by adding CeO2 to 16Co63C21Zr. When the amount of CeO2 added increased, the hydrogen yield increased and 16Co42C31.5Ce10.5Zr showed a hydrogen yield of 89% at a reaction temperature of 600°C.
If aromatics and hydrogen can be produced from fatty acid methyl esters (FAME), it will be an attract ive process. In this study, for the purpose of obtaining aromatics and hydrogen from FAME, mesoporous alumina with high diffusivity and microporous zeolite with high cracking activity were mixed by a kneading method. In this study, the effect of Pt added by impregnation and ion exchange methods was investigated in the dehydrocyclization-cracking of methyl oleate using Zn-exchanged ZSM-5 alumina composite oxide.
An average molecular structure analysis supporting program was designed using Excel for lignin solubilized product. It covers mono-aromatic rings with 2-5 substituents including phenols and ethers using tertiary and quaternary aromatic carbon distributions, which obtained by elemental analysis, number averaged molecular weight, 13C-NMR techniques including dept and quat pulse sequences. For an average molecule having 5 aromatic ring cores, the program picked up the core structures within 3 minutes.
In pulverized coal(PC) boilers, ash deposition can cause operational problems and heat transfer inhibition. However, it is difficult to predict ash deposition characteristics under co-combustion of low rank coal using general methods (e.g., base acid ratio or slagging factor). In this study, a new prediction of ash deposition characteristics from raw coals was evaluated with ash deposition measurement while co-combustion condition in PC boiler. Ash deposition characteristics of blending coal samples could be classified according to concentration of iron compounds in PC boiler ash samples. Furthermore, correlations of concentration of iron compounds were analyzed sulfur degradation with TG-MS, iron minerals in raw coals with CCSEM. It was confirmed that raw coals measurement with TG-MS and CCSEM could improve the prediction of ash deposition characteristics under co-combustion conditions.
In this study, the HCl absorption performance in simulated coal gasification fuel gases of cheap natural soda ash loaded on a honeycomb support as a hot gas cleanup method is investigated by using flow-type fixed-bed reactor. The HCl removal performance of the honeycomb-supported soda ash at 500°C in 1000ppm HCl/12-28%H2/N2 reveals that H2 does not affect the HCl absorption ability. On the other hand, the coexistence of 26-58%CO to 1000ppm HCl/12-28%H2/N2 decreases the HCl removal performance by carbon deposition from disproportionation reaction of CO. However, the addition of 2-10%CO2 to 1000ppm HCl/12-28%H2/26-58%CO/N2 improves the HCl absorption ability. In addition, the HCl removal performance of the honeycomb-supported soda ash in HCl/12%H2/26%CO/6%CO2/N2 depends on the HCl concentration (500-2000ppm) and reaction temperature (300-600°C).
Coal ash production is increasing year by year, but its application is very limited at present. Therefore, new applications of coal ash for its mass consumption is are needed. However, the use of coal ash requires both high safety and cost efficiency. We have reported at the last year's Coal Science Symposium that, the amount of elution of harmful elements from coal ash can be reduced below the environmental standard value by calcining a mixture of coal ash and two types of waste. In this research, we also found that phosphorus and calcium included in waste played an important role in reducing the elution of harmful elements. Based on this result, not only we can utilize a wide variety of wastes for mixing with coal ash, but we also can simultaneously insolubilize multiple wastes other than coal ash. Moreover, we found that the granulated material obtained by calcining waste could be utilize as soil improving material and promoted the growth of plants without increasing the concentration of harmful elements in the plants. In this lecture, we will report on the current state of technological development to prevent the elution of regulatory elements from coal ash using waste.
To reduce problems at the coal-fired thermal power plant caused by ash deposition, it is important to observe inside the boiler. We have developed an efficient new method to monitoring the phenomenon of ash deposition and clinker formation on the heat transfer surfaces in our pulverized coal-fired boiler in operation. Comparing ash area ratio, which indicated a degree of ash deposition obtained from the new method, with ash deposition level estimated by a human, it was shown to improve accuracy and efficiency of the observation. The proposed method can be applied to other coal-fired power plants worldwide to help improve operating conditions.