Entity

Time filter

Source Type


Song W.,East China University of Science and Technology | Sun Y.,East China University of Science and Technology | Wu Y.,East China University of Science and Technology | Zhu Z.,East China University of Science and Technology | Koyama S.,Japan Coal Energy Center
AIChE Journal | Year: 2011

The viscosities of 45 coal ash slag samples at high temperature have been measured under different temperatures and shear rates. The computer thermodynamic software package FactSage has been used to predict liquidus temperatures, volume fractions of crystallized solid particles (φ{symbol}), and the compositions of remaining liquid phase for 45 coal ash slag samples. The flow properties of completely liquid and partly crystallized coal ash slag samples have been predicted by three viscosity models. The Urbain formalism has been modified to describe the viscosities of fully liquid slag and homogeneous remaining liquid phase in coal ash slag samples. The modified Einstein equation and Einstein-Roscoe equation have been used to describe the viscosities of heterogeneous coal ash slag samples of φ{symbol} < 10.00 vol % and φ{symbol} ≥ 10.00 vol %, respectively. These three models provided a good description of the experimental data of fully liquid and heterogeneous coal ash slag samples. The new models also predicted flow properties of mixtures of coal ash slags with CaO, Fe2O3, MgO, SiO2, and Al2O3. Copyright © 2010 American Institute of Chemical Engineers (AIChE). Source


Lin S.,Japan Coal Energy Center
Energy Procedia | Year: 2013

In-situ CO2 capture in coal utilization captures CO2 during coal combustion or gasification such as Oxygen fuel combustion or Chemical looping coal gasification processes. Japan coal energy center (JCOAL) have proposed a chemical looping coal gasification method. This method utilizes a chemical looping with the calcium cycle, in which CaO (or Ca(OH)2) captures CO2 during coal gasification to form CaCO3 and release heat for gasification to produce hydrogen in one gasifier. This paper introduces the current developing status of the method, mainly including the experimental examination of the transition of sorbent particle size distribution, ash and sulfur concentration of materials at several locations of gasification and calcination system for the process. As results it is shown that, the product gases from the chemical looping coal gasification only contained nearly 80% H2 with 20% CH4 with dry base. It was also found that coal ash and sulfur concentrated highly in the process of calcination after cyclone. And the plant cold gas efficiency which should be affected by ash separation was also analyzed. If it is possible, separate and remove ash and sulfur by applying devices like filter or/and cyclone separator, the plant coal gas efficiency may raise 2 points than that in the previous study in which a part of recycled sorbent was rejected without separation. As an application of the chemical looping coal gasification, exergy regeneration type IGFC power generation was proposed. Exhaust heat of FC can be used for reforming of CH4 which produced by coal gasification. This system was analyzed by use AspenPlus. The result shown that, hydrogen cold gas efficiency was about 10% higher than the cold gas efficiency of the chemical looping coal gasification. © 2013 The Author. Source


Lin S.-Y.,Japan Coal Energy Center
Energy Procedia | Year: 2014

It is a prerequisite for the increasing use of biomass energy that its introduction and acceptance be increased. The technologies for biomass use face the challenge of overcoming the following issues: (1) Stable supply of gasification material; (2) Heat supply for biomass gasification; (3) Auxiliary facilities for post-gasification tar removal, gas composition adjustment, and desulfurization; (4) Use of various biomass; We proposed Ca looping three-tower biomass/coal co-gasification process. CaO circulates as the heat transfer material, catalyst and a CO2/H2S sorbent. Biomass and supplemental fuel coal are supplied to the gasification tower and generate volatile matter and char through the pyrolysis and gasification, as well as a part of CO2 in volatile matter are absorbed by CaO to form CaCO3 and release heat for the pyrolysis and gaisification. The volatile matter is then introduced to the reforming tower for the catalytic reforming of hydrocarbon (CH4, Tar et al.) by contact with the CaO particles. The char and CaCO3 are introduced to the combustion tower. The char is burnt using air to heat the CaO particle and CaCO3 for decomposition to CaO. The heated CaO particles return to the reforming tower and the gasification tower through a cyclone. The CaO particle heated in the combustion tower provides heat to the catalytic reforming of hydrocarbon as CH4, tar et al. in reforming tower. The catalytic action of CaO for hydrocarbon reforming was investigated by using a two stage fluidized bed reactor which upper stage is reforming reactor, and lower stage is gasification reactor. Biomass/coal were fed in to gasification reactor, and volatile matter produced by biomass/coal gasification was raised in to reforming reactor. It also shows that, with CaO catalysis in the reforming reactor, no tar remained in the cooling zone and condenser from biomass gasification 2.5hr. However without CaO addition, tar generated terribly after biomass supply only 3 minutes. Liquid products from reforming reactor for biomass and coal gasification were collected by using ice water and liquid nitrogen baths. Total carbon (TOC) contained in the liquid product was analyzed. Tar contained in product gas from biomass and coal gasification were estimated by the amount of total carbon. The results shown that, only 5.7 mg/m3 and 2.5 mg/m3 tar contained in products gas for biomass and coal gasification, respectively. In this study, we also built a small hot 3-T CFB facility, to investigate the particle circulating and fluidization. And, the effect of CaO catalysis on steam reforming of hydrocarbons as methane, tar produced by biomass or coal gasification also be investigated. First we tested silica sand and CaO particle circulating in the three-tower CFB. Results shown that, three-tower type CFB can make stability particle circulating not only under room temperature and also circulated well under high temperature 800°C. Control the differential pressure (δP) between exits of cyclone and reformer is much important for the stability of circulating of 3-T CFB. Particle circulating velocity, Gs was obtained about 100-200. © 2014 The Authors Published by Elsevier Ltd. Source


Kiyama T.,Hokkaido University of Science | Nishimoto S.,Japan Central Research Institute of Electric Power Industry | Fujioka M.,Japan Coal Energy Center | Xue Z.,Kyoto University | And 3 more authors.
International Journal of Coal Geology | Year: 2011

CO2 sequestration in deep unmineable coalbeds is regarded as a viable option for carbon storage. On the other hand, many uncertainties still remain due to the fact that coal interacts with CO2 in a variety of ways. In Japan, the first CO2 Enhanced Coalbed Methane Recovery field trials at Yubari were carried out. CO2 was injected from an injection well into a coalbed at a depth of 900m, and coalbed methane was collected from an observation well. Since the CO2 injection rate was an order of magnitude lower than that estimated by preliminary analyses, N2 was injected in an attempt to improve it. However, this caused only a temporary increase in the CO2 injection rate. To better understand the phenomena observed in the Yubari field tests, two laboratory experiments were conducted under stress-constrained conditions. In Test I, liquid CO2 was injected into a water-saturated coal specimen and then heated and injected as supercritical CO2. This was to simulate the initial stage of CO2 injection at Yubari when the coal seam was saturated with water. In Test II, supercritical CO2 was injected into a coal specimen saturated with N2, and then N2 and CO2 were repeatedly injected. This test was to simulate the case of N2 injection and CO2 re-injection at Yubari. In Test I, a volumetric swelling strain of 0.25 to 0.5% was observed after injecting liquid CO2. However, in Test II, the swelling strain was about 0.5 to 0.8% after injecting supercritical CO2. Following further injection of N2 in Test II, slow strain recovery was observed in the coal. At an effective stress of 2MPa, the permeability of the water-saturated coal specimen was 2×10-6darcy. In contrast, the permeability of the N2-saturated coal specimen was originally 5×10-4 to 9×10-4darcy, and after injection of supercritical CO2 it decreased to 2×10-4darcy. Further injections of N2 and supercritical CO2 caused little subsequent change in permeability. These results suggest that when liquid CO2 was injected into the water-saturated coal specimen, it did not completely displace the water in the coal matrix. To further investigate the coal swelling and permeability behavior during gas injection, elastic wave velocity measurements were carried out and the results were found to validate those obtained using strain gauges. The results indicate that coal swelling is likely to be the main cause for the permeability change in the Yubari field tests and thus provide useful information for modeling the field trial. © 2010 Elsevier B.V. Source


Makino K.,Japan Coal Energy Center
Cleaner Combustion and Sustainable World - Proceedings of the 7th International Symposium on Coal Combustion | Year: 2012

Needs for electricity is growing rapidly in many countries and it is expected the increase of electricity by 2030 is almost double. Fossil fuels, renewables, nuclear energy will play leading parts in the future, but fossil power generation will continue to play a major role. Especially, coal will be used continuously due to its stable supply and lower price. However, global warming countermeasures should be considered for large amount of coal use. High efficient systems and Carbon Capture and Storage (CCS) will be most applicable solution for the problems. USC, IGCC and A-USC have higher efficiencies, but costs are normally higher. So it is very important to evaluate the future trend of the plants, that is the cost, performance and the share of each plant. It is also essential to evaluate high efficient plants which will be constructed mainly and which system investment should be paid to. But no less important is to evaluate each system from the neutral position. So Japan Coal Energy Center (JCOAL) constructed its own program to expect the future trend of each plant. JCOAL made a basic concept and the programming was done by SRI International of the United States. The considered systems of coal fired power generation are Supercritical Unit, Ultra Supercritical Unit, Advanced- Supercritical Unit, Integrated Gasification Combined Cycle (IGCC) and Integrated Gasification Fuel Cell (IGFC). In order to compare with the natural gas case, Natural Gas Combined Cycle (NGCC) is included. Evaluation will be done for both without and with CCS cases.This program covers by the year of 2050. The results are trends of following items:- capital cost, operational and maintenance cost, levelized cost of electricity, etc. We can also expect the future share of high efficient coal fired systems by 2050. Here the share will be decided by the levelized cost of electricity. The plant that has the lowest cost will get more share under the scenario of this program. This paper summarizes the program and the results of the evaluation. © Tsinghua University Press, Beijing and Springer-Verlag Berlin Heidelberg 2012. Source

Discover hidden collaborations