VOL.21 NO.1 (published in Jun-2013)

Photo in Cover :Joso Environment Center

VOL.21 NO.1 (published in Jun-2013)

Energy Recovery from Sewage Sludge

Daisuke IWASAKI*
(*Sewerage Engineering Dept.)


Sewage sludge is a biomass resource expected to be effectively used, 80% of which has been recycled, but its energy recovery rate is only about 13% on the basis of organic substances (FY2010). In order to improve the energy recovery rate, various energy recovery promotion measures have been taken, including feed-in tariff scheme for renewable energy. On-going energy recovery is mostly utilization of digestion gases for power generation by anaerobic digestion, but a large amount of digestion gases are left unutilized, promoting development of new technologies such as utilization as urban gases by refinement. For fuel utilization in the existing coal-fired boilers by solid fuelization, multiple technologies, such as granulation drying, carbonization, have been developed and actual machines are running, but there are restrictions by location requirements and auxiliary fuel cost. Sludge incinerating power generation has been conventionally difficult to materialize except some large-scale facilities because of a sewage sludge property, that is, high water content. However, energy recovery from sewage sludge by sludge incinerating power generation will be enabled by recent establishment of sludge water content reduction technology and small-scale steam power generation technology.

Joso District Wide-Area Municipality Administrative Works Association
(Joso Environment Center)

(*Environmental Engineering Dept. Ⅱ)


The "Joso Environment Center" designed for the Joso District Wide-Area Municipality Administrative Works Association is the 4th facilities as our gasification and melting plant for municipality. After test operation since Jan. 2012, it was completely handed over in Jul. 2012 and has been operating successfully to date. Emphasizing the use of a sodium reagent as an exhaust gas treatment agent, optimum shape of the melting furnace, lower CO concentration by char blow rate control, and efficient energy recovery, the Center has established operation leading to higher economic efficiency.

Soma Houbu Eisei Kumiai "Koyo Clean Center"

(*Environmental Engineering Dept. Ⅱ)


Waste incineration equipment was delivered to Soma Houbu Eisei Kumiai at the end of November 2012. This equipment being a water spray type gas cooling facility, it has an air preheater and an air heater for prevention of white plume emission installed in the rear stage to recover heat, prevent white plume emission and supply hot water in the precincts, thus making use of waste heat. Also, a bag filter and a selective non-catalytic reduction facility are used as exhaust gas treatment equipment to eliminate harmful gases. After conducting test operation for about 5 months, a performance test satisfied predetermined incineration capacities and exhaust gas measurement values were lower than control values.

Development of On-Site Regeneration of NOx Removal Catalyst

Hiroshi MINOYA*, Masaru SUZUKI*, Masaaki KURATA* and Norio MAEDA*
(*Equipment Engineering Dept.)


For the purpose of reducing the maintenance and operation cost of a waste incineration plant, a basic test and on-site regeneration simulation test were conducted in order to establish an on-site activity restoration method without taking out an NOx removal catalyst from a selective catalyst reduction system. In the on-site regeneration simulation test, it was possible to regenerate the catalyst by increasing the temperature to approx. 380℃ required for resolution of acidic ammonium sulfate; regeneration was allowed 20 times without lowering NOx removal efficiency and compression strength (assuming regeneration once a year during 20-year operation). Also, regeneration was accomplished in a short time of about 20 hours including temperature increase. SO2 gas produced at the time of regeneration was able to be eliminated in a slaked lime pellet filled tank, and NH3 gas was able to be eliminated by being resolved into nitrogen and water by action of the NOx removal catalyst without using any special chemical agent.

Installation Report on Chicken litter Fuel Combustion Fluidized Bed Boiler Power Plant

Daisuke YAMAJI*, Norishige ONO* and Keiji MUKAI*
(*Energy Engineering Dept. Ⅰ)


We have a technology to combust a chicken litter fuel and recover its energy as steam and electricity as part of effective utilization of chicken litter.Making use of this technology, we installed a chicken litter fuel combustion fluidized bed boiler power plant to NANGOKU KOUSAN CO., LTD. in Mar. 2002. And then, in March 2012, we installed the second power plant to the same company for the purpose of further utilization of chicken litter. The Report outlines the chicken litter fuel combustion fluidized bed boiler power plant installed this time. This plant produces steam at a rate of 35 t/h by boiler, using the chicken litter fuel at a rate of 13.1 t/h, and supplies steam to the process at a maximum rate of 16.5 t/h and generates 1,580 kW. Realizing successful combustion of the chicken litter fuel in a performance test, we have confirmed this plant was capable of supplying steam and power as designed. And, we have also confirmed the requirements of the exhaust gas emissions regulations were satisfied completely.

Full-Scale Demonstration on High-Efficiency Nitrogen Removal Technology
by Fixed Bed Type Anammox Process ; Part 1

Keita TAKAKI*, Taro KURUSU*, Naoki IRIE* and Kenichi SHISHIDA*
(*Sewerage Engineering Dept.)


In the "Breakthrough by Dynamic Approach in Sewage High Technology Project (B-DASH Project)" implemented by the Ministry of Land, Infrastructure, Transport and Tourism, our company implemented "Full-Scale Demonstration on High-Efficiency Nitrogen Removal Technology by Fixed Bed Type Anammox Process" as a FY2012 project in collaboration with Kumamoto City and Japan Sewage Works Agency. Constructing and operating an anammox process-based nitrogen removal demonstration plant, which is designed to treat anaerobic digestion supernatant at a designed water treatment quantity of 50 m3/day, in the Kumamoto City Tobu Sewerage Center, this project demonstrated applicability and usefulness as a technology to remove ammonium- nitrogen contained in filtered water. The demonstration plant was constructed in July through November in 2012, and after subsequent test operation and acclimatization, started full-fledged operation from February 2012. Currently being under demonstrative operation, it is collecting various data for establishing an anammox process technology.

Report on Combustion Experiment of Sewage Sludge Dehydrated with Advanced Centrifugal Dehydrator, Using Step Grate Stoker Furnace

Yukiya ATSUMI*, Toru SASAKI*,Yuzuru NAKANISHI*, Takaaki MIZUNO*,
Naoki KABUTAN* and Kenichi SHISHIDA*

(*Sewerage Engineering Dept.)


Targeting lower-moisture content sewage sludge dehydrated with advanced centrifugal dehydrator (moisture content of approx. 70%) compared with conventional dewatered sludge, and for the purpose of building a incineration system inhibiting production of N2O and dispensing with a dryer and auxiliary fuel, a combustion experiment was conducted using a step grate stocker furnace. As a result of the experiment, the dewatered sludge was directly poured into the furnace at an air ratio of 1.3 to 1.4, and the furnace outlet temperature of 800℃ was successfully maintained without any auxiliary fuel, achieving N2O emission of 0.3 kg-N2O/t-wet (more than 50% lower than before). At this time, the CO concentration at the furnace outlet (O2-12% equivalent) was 15 ppm or less and an ignition loss of ash was 0.3% or less. A sludge supply method used in the experiment was a pressure method, but there was no adherence of sludge and a supply rate fluctuation range was about ±10%, allowing stable supply. Successful incineration was also confirmed without problems in a test subjected to ±20% fluctuations of an incineration rate.

Removal System of Radioactive Cesium in MSW Incineration : t-RECs

Takahiro IWAMOTO*, Muneharu FUJIKAWA* and Hiroki FUJIHIRA*
(*Energy and Environmental Development Dept.)


Removal technology of radioactive cesium has been investigated concerning fly ash of municipal solid waste (MSW) incineration since the Fukushima nuclear disaster, and we developed the system of the efficient removal of cesium. The developed system (t-RECs) is consisted of the following three processes:cesium extraction process in water, cesium adsorption and elution process, cesium concentration process. The molecule recognition technology of cesium selectivity is applied to the adsorption process. This system has the advantage of being highly efficient at both cyclical use of the adsorbent and minimization of final disposal volume.This paper reports the outline of total system, the evaluation result in performance test of the adsorption process.

Chlorine Content of Bottom Ash in MSW Incineration Facility and Possibility of Chlorine Reduction by Heat Treatment

Takashi KAWANO*, Takayuki SHIMAOKA*, Amirhonmayoun SAFFARZADEH** and Shuo YANG**
(*Energy and Environmental Development Dept., **Faculty of Engineering, Kyushu University)


Bottom ashes were collected from some MSW incineration facilities to examine the chlorine content and chlorine existence form. The chlorine content was 0.005 to 0.015 g-Cl/g-ash and soluble chlorine was 57 to 84%. The smaller the grain size, the higher the chlorine content ; 2 mm or smaller ashes contained about 60% of total chlorine. The form of insoluble chlorine was conceived to be crystalline chlorine in the wet ashes, but no crystalline chlorine was observed in the dry ashes. It was confirmed that the chlorine content of the bottom ashes was reduced due to volatilization of soluble chlorine by heating the dry and wet ashes. When the dry ashes were heated at 1,000℃, however, chlorine was partly taken into amorphous, and when the wet ashes were heated, a complicated behavior was detected such as recrystallization of crystalline chlorine.

Expansion of Scope of PLC Instrumentation System "TS-PAT1000"

Ichiro DOI*, and Yutaka KAMEYAMA*
(*Electrical Instrumentation Dept.)


More PLC instrumentation systems have been introduced in the environmental and energy fields. The PLC instrumentation system "TS-PAT1000" uniquely developed by our group company (TSC) has been introduced since 2009, and our company has also employed multiple systems such as an automatic combustion control system for a waste incineration plant and a control/monitoring system in the medium- or small-scale plant. For further introduction in the future, we have expanded the system scale of the TS-PAT1000, targeting the waste incineration plant with power boilers, thereby leading to expansion of the scope.

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