Technical informationTECHNOLOGY

VOL.23 NO.2 (published in Dec-2015)

Photo in Cover :On-site Regeneration of Denitrification Catalyst
VOL.23 NO.2 (published in Dec-2015)
Takuma's Latest Exhaust Gas Treatment Technology
Shinji AZUMA*,Masakazu KAMADA*,Akira TAGUCHI*
(*Mechanical Design & Engineering Dept.)


The following describes the five kinds of technologies recently developed by us as the methods for treating exhaust gases including harmful substances produced at the waste material incineration plants. They are (1) Fly ash circulation system, (2) Furnace internal NOx reduction technology, (3) Urea decomposition equipment, (4) On-site catalyst regeneration system, and (5) Intermittent activated carbon injection equipment for mercury. A combination of these technologies allows merits such as increased power generation, lower consumption of drugs (slaked lime, activated carbon), reduced facility costs and operation/maintenance costs for denitrification ammonia, and lower facility costs by compact denitrification equipment.

Operation Report on Steam Power Generation Facilities at Sapporo Western Sludge Center
(*Sewerage Engineering Dept.)


The Sapporo Western Sludge Center incinerates the produced sludge in a step grate stoker furnace and recovers heat energy of resultant exhaust as steam via a waste heat boiler to utilize it as a sludge drying heat source and for air preheating, heating and hot water supply. However, all the recovered steam had not been effectively utilized ; part of it had been discharged into the atmosphere as surplus steam.

In order to make effective use of this surplus steam which had been discharged into the atmosphere, they newly constructed small steam power generation facilities and confirmed stable power generation of 160 kW rated output without affecting the steam balance of the incineration facilities.

Result Report on On-site Regeneration of Denitrification Catalyst at "Clean Center Kashihara"
Masaru SUZUKI*1,Hiroshi MINOYA*2,Masakazu KAMADA*1,Akira TAGUCHI*1
(*1Mechanical Design & Engineering Dept., *2Energy & Engineering Development Dept.)


Municipal waste incineration facilities have installed catalyst denitrification equipment for the purpose of high-efficiency removal of nitrogen oxides. A catalyst loses its performance over time due to adhesion of ammonium sulfate or acid ammonium sulfate generated by sulfur oxide and ammonia contained in exhaust gas. Once the performance is reduced, the catalyst has to be replaced by new one or taken out of the catalyst denitrification equipment and regenerated at regeneration facilities. For this purpose, it is necessary to set a furnace non-operating period of 1 to 2 months. Because the catalyst may be damaged by shocks, etc. during regeneration processing, it is necessary to limit regeneration processing to a couple of times and purchase new one thereafter. As a system capable of regenerating the catalyst in a short period and 20 or more times without damaging it, we developed an "on-site regeneration system" capable of regenerating the catalyst while it is set in the catalyst denitrification equipment. In May 2014, the first machine of this system was introduced into the "Clean Center Kashihara." All 3 sets of catalyst denitrification equipment were regenerated one after another, using this system, and it was confirmed that all 3 sets of equipment were capable of recovering the denitrification performance of catalyst as good as new one, and that the concentration of dioxins and ammonia at the chimney inlet was lowered than before regeneration.

Application of NH3 and NaOH for Boiler Water Treatment in Waste Incineration Plant
Yasuki MORIOKA*,Junichi KUMAGAI*,Yasuyuki FUJITA*
(*Sewerage Engineering Dept.)


AVT(LO) for feed water and caustic treatment for boiler water was applied to a waste incineration plant in Japan for approx. 6 months test period. This water treatment utilizes ammonia for feed water and sodium hydroxide for boiler water. During the test period, pH and electrical conductivity of both feed water and boiler water were controlled within the set normal values. According to the water quality analysis results, a rise of iron and copper concentration was not observed, suggesting low corrosion tendency. As a result of the internal condition inspection after the test, no new occurrence of corrosion was observed and the surface condition was satisfactory. In analyzing the composition of sludge, test pieces, etc., magnetite and hematite were identified. The corrosion rate of the test pieces was 0.023 mm/year or less, which is sufficiently small. Based on these results, it is concluded that the waste incineration plant applied with this water treatment was able to be operated in a favorable condition. For the boilers of waste incineration plants in Japan, applicability of this water treatment was suggested.

Development and Demonstration Project of Recycling Technology of Woody Biomass Incineration Ashes
Munechika ITO*1,Takashi KAWANO*2,Norio MAEDA*1
(*1Energy & Engineering Development Dept., *2Energy Engineering Dept.1)


While woody biomass power generation is drawing attention and spreading in the society, most of incineration ashes discharged from a power plant are disposed of as a waste material. Technology making effective use of them is being demanded from viewpoints of cyclical use of resources and economic efficiency. Because woody biomass incineration ashes contain much potassium, they can be a substitute for potassium ore, which is 100% dependent on import, as well as promote cyclical utilization of waste material, contributing to the stabilized Japanese agricultural foundation, if they are effectively used as a fertilizer.

In this demonstration project, two woody biomass boilers were studied to understand incineration ashes and potassium discharge properties by tree species and incineration system. In addition, we developed a system, which separates and condenses potassium, an effective component of fertilizer, by a simple method called classification, and conducted a demonstration test at the existing woody biomass boiler plant to clarify separation and condensation properties. A fertilizer effect test was also conducted, using incineration ashes to confirm that they are as effective as conventional potassium fertilizers.

High-efficiency Construction Work by Opening/Closing Tent for Overhead Entrance of Building
(*Construction Dept. (Tokyo) )


Long-life construction work for Tamamura-machi by improvement of Tamamura-machi Clean Center Main Facilities was completed in March 2013. Life-extending construction work to be carried out at the already operating facilities is regulated by the Law concerning Special Measures against Dioxins. In order to reduce a discharge amount of air, etc. in the control area 1 (concentration of dioxins in the air=2.5 pg-TEQ/m3 or less), it is necessary to shorten carryin/- out time (=opening time of the opening) and minimize a discharge amount from an internal negative-pressure environment (pressure in the sealed space (measured value) is approx. 0.2% lower than the atmospheric pressure). Construction work was carried out in the conventional method which opens the ceiling of the building in accordance with the installation position of the renewal device for each furnace to carry in/out. A manually opening/closing bellows type tent method was employed for opening/closing of the ceiling. Satisfactory results were obtained as to safety for work at the opening end and durability for long-term use, and high cost effectiveness was confirmed.