Technical informationTECHNOLOGY

VOL.16 NO.2 (published in Dec-2008)

Photo in Cover :Beijing Gaoantun Waste to Energy Plant
VOL.16 NO.2 (published in Dec-2008)
Development of Biomass Gasification System (2nd Report)
-Progress of Wood Biomass Gasification-
Munechika ITO*and Kosaku OMORI**
(*Energy and Environment Development Dept.,**Energy Engineering Dept. Ⅰ)


We have been developing a gasification technology that achieves a high-efficiency energy conversion of biomass. This system employs the atmospheric air-blown gasification method, and adopts a circulating fluidized bed gasifier for its compatibility with wide range of fuels, having excellent mixing capability and good temperature-control.A set of ceramic filters of our own design is installed for the purpose of high-temperature dust filtration, and a catalytic tar-cracking unit is added, both downstream of the gasifier.

The development was initiated in 2001, and a pilot plant was built in 2002. By testing gasification of woodchips, each technical element such as the circulating fluidized bed, high-temperature filters and tar-cracking unit has been optimized, establishing integrity of the entire system.

Nitrogen Removal by Sand Filtration at an Operating Plant
-Effect of denitrification-type upflow moving bed sand filtration-
Masahiko OKUDA*
(*Sewerage Engineering Dept.)


Advanced water treatment technologies are being introduced to sewage treatment facilities. Existing technologies, however, require huge facilities expansion while the nitrogen removal rates are limited, proving to be insufficient for achieving the target in comprehensive basin-wide planning of sewage system. The new technology of the future should be retrofitted easily into existing facilities with reasonable cost, and should be able to adjust the quality of treated water according to the variety of feed sewage. We have made some improvement to a working upflow moving-bed sand filtration facility, and conducted denitrification tests. The demonstration was carried out using a pond of 10,000m3/day capacity, one of four working ponds with the total capacity of 40,000m3/day.

After conducting the Nitrogen removal test over a period of roughly a year and a half at the filtration speed of 200~450m/day, we have achieved the treated water T-N concentration under 5mg/L (NO3-N concentration : 2~3mg/L) that is stabilized despite seasonal changes, and fluctuations in sewage volume. We have also confirmed that the T-N concentration can be adjusted to a desired level by controlling the methanol injection rate. The test results enabled us to establish the designing format of this technology.

This research was conducted at the Yahagigawa sewage treatment plant as a joint undertaking (2006~2007) with Aichi Mizuto-Midori Public Utility Corporation.

Operation Report of Furnace #3 at Fujikoh Co. LTD.
Hidenobu NAKAGAWA*,Hiroaki OZAKI**and Makoto MOCHIZUKI*
(*Energy Engineering Dept.Ⅱ, **Energy Engineering Dept.Ⅰ)


The wood waste from construction and demolition waste is a biomass that is considered as one of the carbon-neutral sources of energy. The First Commitment Period of the Kyoto Protocol began in January of 2008, and the importance of power generation from waste as a new source of energy is growing steadily. The waste incinerator #3 (hereafter called furnace #3 ) we built for Fujikoh Co. Ltd. of Shirai City, Chiba (hereafter called Fujikoh) is equipped with a waste-heat boiler for power generation with the capacity of 1,800kW. It mainly burns wood waste that cannot be recycled as a building material. By adopting a single-drum vertical boiler with a combustion chamber consisting of water tubes, we have reduced the air ratio and the installation area. This report describes the outline of this plant, and reports on its test operation results.

Development of New Metal Level Measuring System for Plasma Type Ash Melting Furnace
Masaharu OUE*,Koutaro KATOU**,and Yoshihito KURAUCHI**
(Energy & Environmental Development Dept., **Mechanical Design & Engineering Dept.)


For the stable, continuous operation of a plasma type ash melting furnace that turns waste incineration residue into slag, the level of molten metal accumulated at the bottom of the furnace is measured periodically so that it can be discharged at suitable time. Currently, its measuring device uses disposable probes. This, however, complicates the arrangement around the furnace, requiring time-consuming installation of the probe, increasing the operation cost.

To solve this problem, we have developed a metal-level measuring system that uses the correlation between the head position of the main electrode (made by graphite) and the back pressure of the nitrogen that is injected from the tip. We have conducted tests using working facility, and have determined that the system can be applied to working facilities.

Circulating Fluidized-Bed Incinerator for Sewage Sludge at Sapporo-East Sludge Center
Takaaki MIZUNO*,Naoki KABUTAN*and Yuji FUJIWARA**
(*Sewerage Engineering Dept. **Energy Engineering Dept. Ⅰ)


For the incineration of sewage sludge, bubbling fluidized bed incinerator has been the mainstay. Recently, however, circulating fluidized bed incinerator are making inroad, as it is environmentally correct for lower power consumption, economy of space, and better accommodation of higher ratio of screenings. In September of 2007, we built and delivered a circulating fluidized-bed incinerator for sewage sludge of 150t/day capacity to Sapporo-East Sludge Center. This is the largest incinerator in the country that has a dewatered sludge direct feeding system. Since then, the facility has been performing smoothly to its specifications.

Operational Report of Sayama City Recycling Plaza
Hiroki UENO*
(*Environmental Engineering Dept. Ⅱ)


This facility meets the requirement of the "Law for the Promotion of Sorted Collection and Recycling of Containers and Packaging" (Container and Package Recycling Law) fully enacted in April 2000. It was ordered by the City of Sayama, Saitama Prefecture in 2005, and was completed on June 29, 2007.

The Recycling Plaza Plant has the throughput of 43ton/5h, and consists of four processing lines : Bulk Waste, Non-Combustibles, Recoverable Waste (bottles and cans) and Dust Collection. Hazardous items, non-crushable items and plastic packaging materials comingled in the non-combustible wastes are removed by the manual separation line. It also removes foreign matters and cullet from the recoverable wastes. Each line has a device to perform volume reduction and compacting of its specific product. This article reports on the outline of the facility and its operation.