Technical informationTECHNOLOGY

VOL.26 NO.1 (published in Jun-2018)

Photo in Cover :Uwajima Public Association Environment Center
VOL.26 NO.1 (published in Jun-2018)
Local Production of Electric Power for Local Consumption
-Based on the Case Examples of TAKUMA Energy-
(*Project Administration Dept. 2)


Since the enforcement of feed-in tariff system (FIT system) for renewable energy in 2012, construction of so-called dispersion type power sources such as photovoltaic power plants and biomass power plants is being advanced. At the same time, due to the full liberalization of electricity retail business in 2016, competition among businesses in electricity retail who distribute electricity to consumers has become intensified, resulting in need for differentiation in elements other than price. As one such method, measures for local production of electric power for local consumption are being promoted, with case examples not only by the plant manufacturers and local businesses targeting synergistic effects with their main business but also municipalities trying to address regional vitalization appearing one after another. This article introduces the measures for local production of electric power for local consumption while taking the case example of TAKUMA Energy, a group company of ours.

Uwajima Public Association Environment Center Operation Report
(*Environmental Design Dept. 3)


Uwajima Public Association Environment Center was completed in September 2017. This Center was established by combining the 5 existing waste treatment facilities in one city and three towns in Nanyo Region, Ehime Prefecture, which are Uwajima City, Matsuno town, Kihoku town, and Ainan town, and it is a facility to treat the wastes and dewatered sludge from the wide area. The heat recovery facility of this Center operates at more strict standard values than the pollution prevention standard values of order specifications. In the delivery performance test implemented at completion, the results sufficiently satisfied the standard values for these items. This article reports on the results of delivery performance test as well as the operating conditions for high-efficiency waste incineration power generation and mixed sludge incineration, which are the features of this facility.

Hanno City Clean Center Operation Report
(*Environmental Design Dept. 3)


“Hanno City Clean Center,” a waste treatment facility for which our company received the order from Hanno City in April 2013, was completed in December 2017. This Center is comprised of a heat recovery facility and a recycling facility, and the heat recovery facility generates electric power with utilization of the waste heat from waste incineration. While the scale of the incineration facility is 40 ton/day×2 furnaces, it recovers the heat energy generated by waste incineration to generate electricity using steam turbine generator to cover the electricity consumption within the Center and sell the excess electricity if there is any. This article reports on the features and operating conditions of the heat recovery facility.

TAKUMAʼs Activities for Effective Waste- type Biomass Utilization
-Dry Methane Fermentation Technology of Municipal Solid Waste-
(*Environmental Engineering Dept. 1)


This article describes TAKUMAʼs activities on the methane fermentation technology of municipal solid waste (MSW), which is one of the effective waste-type biomass utilization technologies. For the methane fermentation of MSW, high-temperature dry fermentation, Kompogas® system, has advantages such as the faster decomposition speed of organic materials and robustness against foreign materials. Since the pilot plant was built in 1999, our company built three methane fermentation facilities including the pilot plant and two facilities are under engineering and construction phase. Nantan Clean Center, built in 2013, has been stably treating MSW and generating electricity for 5 years since its operation started. The waste treatment facility, which TAKUMA accepted an order from Machida city in 2016, introduced both bio-gas power generation and waste fired power generation to improve the total energy efficiency. It is expected that dry methane fermentation technology of MSW will be more widely used and developed, because it is an advanced technology in terms of effective waste-type biomass usage and greenhouse gas reduction.

Measures for Steam Temperature Increase in Waste Incineration Power Generation Boilers
Akinobu NAKAMOTO*,Keiji TATSUMI*,Hiromitsu TAKAHASHI*,Kiyoshi SHIBATA*
(*Mechanical Design & Engineering Dept.)


Conventionally, the steam conditions of boilers for domestic waste incineration power generation have been suppressed at 4 MPa, 400℃ or lower due to the issue of high-temperature corrosion of superheater tube. However, thanks to the studies on corrosion characteristics of materials, facilities whose steam temperatures exceed 400℃ have been constructed for higher power generation efficiency in the recent years. In this article, we conducted an exposure test of approximately 4 months on an operating waste incineration power generation boiler while using a SUS310S-type steel pipe, a high-Cr type and high-Mo type Ni-based overlay-welded pipe†, and a high-Cr type Ni-based self-fluxing alloy thermal sprayed pipe†† as specimens and setting the steam temperature to 450℃, and summarized our findings on the amount of thickness reduction and corrosion phenomenon on each specimen.

Development of Unutilized Heat Recovery Technology
Hirotaka DOHI*,Masayoshi KANO*,Takayuki KUDOH*
(*Energy & Environmental Development Dept.)


To effectively utilize the energy contained in sewage sludge, we developed a new power generation system with introduction into new small- to medium-scale sewage sludge incineration facilities that do not include power generation equipment and existing facilities that do not require dramatic modifications as our targets. This system combines the vacuum type heater which is capable of avoiding low-temperature corrosion by sulfur oxides contained in waste gas and the direct heat-exchange type binary power generation. We manufactured demonstration equipment in 1/3 scale of the actual scale of the facility, and conducted a demonstration to recover heat from the waste gas with the gas flow rate 1,000 to 2,000 m3 N/h and inlet temperature approximately 700℃ using the vacuum type heater and supply the heat to binary power generation. As a consequence, we were able to operate the vacuum type heater at the specified temperature and pressure, and also observed the low-temperature corrosion prevention effect. We conducted power generation operation for the net period of 24 days with the heat input range of 200 to 360 kW to the binary power generator, and confirmed the effectiveness of this system.