Faculty Profiles - FUJIWARA Takeshi

Papers - FUJIWARA Takeshi

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Study on Continuous Mercury Analyzer with Dry-type Reduction Process for Flue Gas Reviewed

TAKAOKA Masaki, SHIMAOKA Yutaka, HOSHINO Munehiro, TAKEDA Nobuo, FUJIWARA Takeshi

Journal of Japan Society for Atmospheric Environment 35 ( 6 ) 332 - 342 2000.11

Language：Japanese Publisher：Japan Society for Atmospheric Environment

In this study, dry-type reduction of mercury (II) chloride experiments were conducted using a packed bed with granular tin metal. The purpose of this study was to identify factors effecting the dry-type reduction process and to elucidate the reaction mechanism. In the reduction of mercury (II) chloride, the ratio of chlorinated surface area on tin was a vital factor. Precoating the surface of granular tin metal with 1N hydrochloric acid was effective in maintaining the reducibility. Marcury (II) chloride was reduced to mercury (0) vapor by the following two reactions on the chlorinated surface of tin metal. SnCl_2(s)+HgCl_2(g)→SnCl_4(g)+Hg(g) SnCl_2(s)+HgCl_2(g)+2H_20(g)→SnO_2(s)+Hg(g)+4HCl(g) Also, it is presumed that decreased reducibility was the result of the following oxidative reactions with tin (II) chloride. SnCl_2(s)+H_20(g)→SnO(s)+2HCl(g) SnCl_2(s)+H_20(g)+1/20_2(g)→Sn0_2(s)+2HCl(g)

Co-melting of Sediment from Lake Biwa and Sewage Sludge Incineration Ash Reviewed

TAKAOKA Masaki, TAKEDA Nobuo, OKAJIMA Shigenobu, HIRAOKA Masakatsu, FUJIWARA Takeshi

Journal of Japan Sewage Works Association 37 ( 453 ) 98 - 115 2000.7

PCDDs/DFs emissions from crematories in Japan Reviewed

Nobuo Takeda, Masaki Takaoka, Takeshi Fujiwara, Hisayuki Takeyama, Shoji Eguchi

Chemosphere 40 ( 6 ) 575 - 586 2000.3

Language：English Publishing type：Research paper (scientific journal)

Concentrations of PCDDs and PCDFs in emission gases from 10 crematories were measured. The relationship between PCDDs/DFs and several factors such as structure, equipment and operational state of the crematory is discussed. Furthermore, emission of PCDDs/DFs from all crematories in Japan is estimated. The following results are obtained: (1) total concentration of PCDDs/DFs was 2.2-290 ng/N m3, whose TEQ concentration was 0.0099-6.5 ng TEQ/N m3; (2) total concentration of PCDFs was higher than that of PCDDs; (3) T4CDFs was the highest in the homologue pattern and 2,3,7,8-T4CDF was the highest in the isomer pattern; (4) emission of PCDDs/DFs was the largest in the first 20 min of cremation; (5) concentration of PCDDs/DFs was related to the existence of a secondary combustion chamber and a dust collector, and the ratio of the numbers of main and secondary combustion chambers; (6) total emission of PCDDs/DFs from crematories in Japan was estimated to be 8.9 g TEQ/yr. (C) 2000 Elsevier Science Ltd.

DOI： 10.1016/S0045-6535(99)00232-5

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Experimental Studies on the Removal Mechanism of Mercury Vapor by Synthetic Fly Ash Reviewed

TAKAOKA Masaki, TAKEDA Nobuo, FUJIWARA Takeshi

Journal of Japan Society for Atmospheric Environment 35 ( 1 ) 51 - 62 2000.1

Language：Japanese Publisher：Japan Society for Atmospheric Environment

It is the goal of this study to identify substances that have critical role in the metallic mercury removal from incineration flue gas by the coexistence with activated carbon and to clarify the metallic mercury removal mechanism by the simulated synthetic fly ash. This synthetic fly ash, which consisted of calcium chloride with 5% activated carbon, showed very high efficiency of over 99% for mercury removal at the temperature of 120℃, the moisture of 20% and air atmosphere. It was found that metallic mercury changed into mercury (II) oxychlorate on the surface of activated carbon and an oxychlorination reaction occurred in the synthetic fly ash at the temperature of air pollution control device. The metallic mercury removal mechanism by the synthetic fly ash is considered to be a chemisorption through the following route; metallic mercury→mercury (II) oxide→mercury (II) chloride→mercury (II) oxychlorate. In order to evaluate the influence of quantity of activated carbon and calcium chloride on metallic mercury removal, the experiments were performed using the synthetic fly ash which consisted of activated carbon, calcium chloride and silicon dioxide. When the calcium chloride content was more than 0.5% in the synthetic fly ash with 5% activated carbon, mercury vapor was completely removed. Whereas, the highest removal efficiencies were obtained when the activated carbon content was ranged from 5 to 7% in the synthetic fly ash with 1% calcium chloride. The mercury removal ability was affected by temperature, if the activated carbon content was very small. Because these phenomena were also observed in the experiments using calcined fly ash with 5% activated carbon, it was supposed that the complex chemical action with activated carbon and calcium chloride was most significant for metallic mercury removal by actual fly ash.

Co-melting of Sediment from Lake Biwa and Sewage Sludge Incineration Ash. Reviewed

Masaki Takaoka, Masakatsu Hiraoka, Nobuo Takeda, Takeshi Fujiwara, Shigenobu Okajima

Journal of Japan Sewage Works Association 37 ( 453 ) 2000

Measurement of Gaseous Components from Batch Combustion of Solid Waste. Reviewed

Norikazu Iwata, Takeshi Fujiwara, Masaki Takaoka, Nobuo Takeda

Environmental Engineering Research 37 ( Pt.2 ) 2000

Application of X-ray Fluorescence Analysis to Determination of Elements in Fly Ash Reviewed

11 ( 6 ) 333 - 342 2000

Destruction of Polychorinated Biphenyls by Iron Compounds Reviewed

KAINUMA M.

Environmental Engineering Research 37 ( Pt.2 ) 477 - 485 2000

The Microwave-assisted Extraction of Chlorobenzenes and PCBs from Fly Ash Reviewed

TAKAOKA Masaki, TAKADA Junichi, TAKEDA Nobuo, FUJIWARA Takeshi

Journal of the Japan Society of Waste Management Experts 10 ( 6 ) 331 - 340 1999.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Material Cycles and Waste Management

A microwave-assisted extraction (MAE) method was used in the extraction of PCBs and chlorobenzenes from municipal solid waste incinerator fly ash. The highest extraction efficiency was obtained at the conditions of: 120°C of extraction temperature over 50 minutes of extraction time. At the most effective conditions, the efficiency and the precision of the MAE method were evaluated by comparing PCB and chlorobenzene levels to those of the soxhlet extraction and the supercritical fluid extraction (SFE) method, by using eight types of fly ash. MAE seems to be a viable alternative to soxhlet extraction and SFE. However, unburned carbon in the fly ash had a bad influence on the efficiency of the removal of PCBs and chlorobenzenes by MAE. The mutual relationship between chlorobenzenes and unburned carbon in fly ash was sufficiently estimated. As MAE has many advantages over soxhlet extraction, such as a shorter extraction time and a lower use of organic solvent, it is adequate for the extraction of PCBs and chlorobenzenes from fly ash.

DOI： 10.3985/jswme.10.331

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Effect of Heavy Metal Recovery from Fly Ash of Ash Melting Furnace on Energy Consumption and CO_2 Emission Reviewed

FUJIWARA Takeshi, TAKEDA Nobuo, KAWABATA Hiroaki, ITO Tadashi, KATAYAMA Manabu, KUNUGIDA Eiichi

Energy and resources 20 ( 5 ) 488 - 493 1999.9

Feasibility Study on Liquefaction of Plastic Wastes -An Application for Northern Shikoku- Reviewed

FUJIWARA Takeshi, TAKEDA Nobuo

Journal of the Japan Society of Waste Management Experts 10 ( 1 ) 25 - 34 1999.1

Authorship：Lead author Language：Japanese Publisher：Japan Society of Material Cycles and Waste Management

In the law for“Promotion of Sorted Collection and Recycling of Containers and Packaging”, liquefaction is outlined as one of the resource recovery methods for ‘plastic containers with the exception of PET bottles’. In this study, an evaluation method is proposed for the liquefaction of plastic wastes over a wide area involving several local governments from the stand points of energy consumption, environmental impacts, and running costs.<BR>The northern part of Shikoku has been selected and six simulated cases with variable plastic collection ratio, locations of pretreatment and liquefaction plants were calculated. The following results were concluded: 1) approximately four times of the energy which is invested in liquefaction is yielded, 2) environmental impacts of energy consumption (CO₂, NOx and consumption of landfill space) and‘transportation costs’are considerably lower than those for‘facilities’, 3) due to scale merits the larger plant is able to save more on energy consumption and costs than the smaller plant.

DOI： 10.3985/jswme.10.25

A Fundamental Study on Solid Waste Combustion. Reviewed

Miki Taniguchi, Takeshi Fujiwara, Nobuo Takeda

Environmental Engineering Research 36 1999

Optimization of Sludge Treatment System with Pre-Coagulation Process. Reviewed

Masaki Takaoka, Kazuhiro Ohshita, Nobuo Takeda, Takeshi Fujiwara

Environmental Engineering Research 36 1999

Removal of mercury in flue gas by the reaction with sulfide compounds Reviewed

Masaki Takaoka, Nobuo Takeda, Yutaka Shimaoka, Takeshi Fujiwara

Toxicological and Environmental Chemistry 73 ( 1-2 ) 1 - 16 1999

Language：English Publishing type：Research paper (scientific journal)

The difficulty in the removal of mercury in flue gas of combustion processes is mainly due to the high volatility of elemental mercury. Various sulfide compounds were tested to check which compounds can convert mercury into stable mercury sulfide and remove mercury from flue gas. The results indicate that lead, cadmium, copper, antimony, tungsten, molybdenum, and palladium sulfides removed more than 80% of mercury from synthetic gas with mercury. On the other hand, zinc, silver, barium, calcium, and nickel sulfides were not effective for mercury removal and their removal efficiencies were less than 20%. The surface analysis using X-ray photoelectron spectroscopy suggested that mercury which reacted with sulfide compounds was presumed to form black mercury sulfide.

DOI： 10.1080/02772249909358843

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Human Interface for the Operation of Waste Incineration Plant Reviewed

FUJIWARA Takeshi, TAKEDA Nobuo

Journal of Japan Society for Safety Enginennring 37 ( 2 ) 72 - 79 1998.4

Feature Extraction from Time-Series Data for Process Monitoring Reviewed

FUJIWARA Takeshi, NISHITANI Hirokazu

KAGAKU KOGAKU RONBUNSHU 22 ( 5 ) 1103 - 1110 1996.9

Language：Japanese Publisher：The Society of Chemical Engineers, Japan

A plant operator monitors time-series data of process variables to judge the state of process, diagnose abnormal states, and to identify failure origins. In this study, a new feature extraction method which extracts simultaneously both local features such as spikes and step changes, and the trend which characterizes global changes is provided from the viewpoint of process monitoring. In this method, the continuous function interpolated from the time-series data is represented by a series of inflection points first. Each time interval between two inflection points is called an episode. Then an approximation function of the time-series data is made iteratively by way of merging these episodes. This feature extraction method is also useful for compaction of a large number of process data.

DOI： 10.1252/kakoronbunshu.22.1103

Fault Detection Based On Functional Relationship Among Process Variables by Autoassociative Neural Networks Reviewed

FUJIWARA Takeshi, TSUSHI Takeshi, NISHITANI Hirokazu

KAGAKU KOGAKU RONBUNSHU 22 ( 4 ) 846 - 853 1996.7

Authorship：Lead author Language：Japanese Publisher：The Society of Chemical Engineers, Japan

Some process variables measured in a plant are strictly constrained by the material and heat balance equations, rate equations and correlations. In this study, we propose a method to judge whether the state of plant operation is normal or not, by examining whether a set of process variables maintains the functional relationship specified at normal operation. The functional relationship at normal operation is identified by an autoassociative neural network (AANN) which approximates the identity mapping for a set of measured values of process variables. An effective method to search for an adequate configuration of the AANN is also presented. Abnormal operation or fault is detected by the magnitude of discrepancy between the input vector and the output vector of the trained AANN. This fault detection method is applied to a continuous flow polymerization process and compared with the conventional 3 sigma fault detection method for a single process variable.

DOI： 10.1252/kakoronbunshu.22.846

Modelling of Overall CO₂ Emission from Industrial Activities on the Basis of Input-Output Analysis. Reviewed

Motoyuki Suzuki, Akiyoshi Sakota, Takeshi Fujiwara, Hideo Watanabe, Yasuhiro Sasaki

KAGAKU KOGAKU RONBUNSHU 19 ( 5 ) 1993

Analysis of municipal refuse incinerator system by use of auto regressive models. Reviewed

Takeshi Fujiwara, Kazushi Tsumura, Masakatsu Hiraoka

Environmental Engineering Research 25 1989

Control of dioxins from municipal solid waste incinerator Reviewed

M. Hiraoka, N. Takeda, K. Tsumura, T. Fujiwara, S. Okajima

Chemosphere 19 ( 1-6 ) 323 - 330 1989

Language：English Publishing type：Research paper (scientific journal)

The purpose of this study is to establish whether intermediate products, which are remained as unburned components and become the precursors to form the PCDD, can be reduced by improvement of the plant operation. The change of the PCDD levels was analyzed along the stream of the flue gas. Two test programs were conducted to reduce the emission levels of PCDD at municipal solid waste (MSW) incinerators. They were as follows; 1. (1) High temperature incineration to reduce unburned components. 2. (2) Investigation of the relationship between CO contents and PCDD levels at an incinerator which was operated by reductive two-step combustion mode to reduce NOx emission level. © 1989.

DOI： 10.1016/0045-6535(89)90331-7

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