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VOL.26 NO.2 (published in Dec-2018)

Photo in Cover :Imabari City Waste Management Center
VOL.26 NO.2 (published in Dec-2018)
Transition of Boiler Dust Removal Device and Future Issues
Hiromitsu TAKAHASHI*
(*Mechanical Design & Engineering Dept.)

(Abstract)

Since dust adhering to the heating surface of the boiler causes failures such as deterioration of heat transfer performance, closed gas passage, and corrosion of water tube, equipping a device capable of removing dust during operation is necessary, in addition to stopping and cleaning the boiler at regular intervals. In addition, since various types of dust removal devices are available, it is important to select a device suitable for the working environment conditions including temperature, dust property, etc., depending on the cases. In this paper, to explain the transition of boiler dust removal devices, the types and characteristics of representative dust removal devices that have been conventionally used are described and a new dust removal device introduced in recent years is presented ; then, the future issues are mentioned.

Report on Operation of Imabari City Waste Management Center
Nobuo AKAE*
(*Environmental Design Dept. 3)

(Abstract)

Imabari City Waste Management Center, established together with a combustible waste management facility and a recycling center, was completed in March 2018, by putting together the existing four facilities in Imabari City, including the island areas. This facility has been built on the concept of “facility that brings together people, communities, and generations through a safety and pease of mind,” and in case of emergencies, it also acts as a shelter by opening the administrative building to the public. As a waste management facility, it is operated according to the reference values which are stricter than those requested by Imabari City as the pollution control standards. This paper reports the results of the delivery performance test before completion and the start-up of the facility capable of efficiently generating power and acting as a shelter, which are the features of this facility

Co- combustion of Sludge at Municipal Solid Waste Incineration Plants
Tomokazu SHIBUYA*
(*Environmental Engineering Dept. 1)

(Abstract)

In recent years, at municipal solid waste incineration plants , co-combustion of human excreta and sludge discharged from sewage treatment plants has been increasingly carried out. Since sludge has a unique odor, receiving facilities should be designed with adequate consideration. Furthermore, since sludge contains higher moisture than combustible garbage, discharged from household , certain considerations should be given not to significantly lower the furnace temperature due to the oversupply of sludge. In addition, sludge has a high sulfur content in the combustible portions, and the exhaust gas generated by co-combustion of sludge contains high concentration of Sox. Therefore, considerations must also be given to exhaust gas treatment facilities, SOx . In this paper, we will introduce various ideas for co-combustion of sludge at municipal solid waste incineration plants , by providing examples of the latest plants that have recently started operation.

Report on the Operation Result of 2 MW- class Woody Biomass Power Plant
Hiroyuki HIKITA*
(*Energy Engineering Dept. 2)

(Abstract)

In the Feed-In Tariff Scheme under the Act on Special Measures Concerning Procurement of Renewable Electric Energy by Operators of Electric Utilities, a purchase price classification of 40 yen/kWh was newly set, in 2015, for unutilized woody biomass power plant of less than 2 MW. For this classification, we have commercialized a 2MW-class power plant applicable to the whole country except Hokkaido and Okinawa Prefecture. In this paper, the outline of a 2 MW-class power plant is provided, and the operation result of two facilities is reported, one of which was delivered to the Biomass Power Technologies Inc., which has started commercial operation in January 2018, and another one to the Kurihalant Co., Ltd., which has started commercial operation in March 2018.

Highly- efficient Nitrogen Removal Technology by the Fixed- Bed Anammox Process, Part 7
-Treatment Performance on High- load Operation-
Keita TAKAKI*,Tomoyuki DOI*,Kengo KISHI*,Kenichi SHISHIDA*
(*Sewerage Engineering Dept.)

(Abstract)

Using the full-scale demonstration plant for the fixed-bed anammox process, which was installed at the Kumamoto City Tobu WWTP as the B-DASH Project of the Ministry of Land, Infrastructure, Transport and Tourism, we have been giving considerations to further cost reduction and stabilization of the process, since FY 2014 when the B-DASH Project was finished. This paper reports the demonstration result of high-load operation as the research results in FY 2017. To increase the influent nitrogen load of the process, “high-load operation” was carried out, by increasing the quantity of influent from the initial design quantity of influent, and it was confirmed that the nitrogen conversion rate was increased in both of the nitritation tank and the anammox tank, following the increase of the influent nitrogen load. Almost no nitrate was generated in the nitritation tank even under high-load operation, and stable nitritation was maintained ; while, in the anammox tank, the nitrogen conversion efficiency of more than 90% was constantly obtained, without increasing of the concentrations of the effluent NH4-N and NO2-N, compared with the process water quality under normal load. From the above, the capacity of both of the nitritation tank and the anammox tank could be successfully reduced, thereby leading to a possibility of cost reduction in this process.

High Efficiency of Biogas Power Generation by Applying CO2 Separation Membrane
Kotaro KATO*,Shigetoshi TAKAHASHI*,Osamu OKADA**,Nobuaki HANAI**,
Nantan Wide Area Administrative Association***
(*Energy & Environmental Development Dept., Renaissance Energy Research Corporation**,
Nantan Wide Area Administrative Association***)

(Abstract)

A gas engine power generation system, fueled by biogas which is generated through methane fermentation of waste, can achieve higher power generation efficiency compared to a steam turbine power generation system, even at small- and medium-sized facilities with a capacity of less than 100 t/day. Since biogas is mainly composed of methane (CH4) and carbon dioxide (CO2), and the CH4 concentration is lower than that of city gas, power generation using a gas engine dedicated to biogas is carried out. The power generation efficiency of a gas engine based on the biogas specification is lower than that based on the city gas specification. However, by removing CO2 in biogas and increasing the CH4 concentration to approximately 90%, it becomes possible to apply a gas engine based on the city gas specification. This has enabled to build a higher efficiency power generation system, thereby leading to the reduction in CO2 emissions. For the purpose of developing a biogas power generation system in which a membrane is applied to separate CO2 contained in the biogas, this paper reports the findings that were obtained from the basic tests on CO2 separation membranes, calculations on the effect of reduction in CO2 and costs, and comparison with those found in the conventional systems for evaluation.