• Journal of the Korean Solar Energy Society
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• v.29 no.5
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• pp.45-52
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• 2009

Fossil power plants firing lower grade coals or equipped with modified system for $NO_x$ controls are challenged with maintaining good combustion conditions while maximizing generation and minimizing emissions. In many cases significant derate, availability losses and increase in unburned carbon levels can be attributed to poor combustion conditions as a result of poorly controlled local fuel and air distribution within the boiler furnace. In order to develop a on-line combustion tuning system, field test was conducted at operating power boiler. During the field test the exhaust gases' $O_2,\;NO_x$ and CO was monitored by using a spatially distributed monitoring grid located in the boiler's high temperature vestibule and upper convective rear pass region. At these locations, the flue gas flow is still significantly stratified, and air in-leakage is minimal which enables tracing of poor combustion zones to specific burners and over-fire air ports. using these monitored information we can improving combustion at every point within the furnace, therefore the boiler can operate at reduced excess $O_2$ and gas temperature deviation, reduced furnace exit gas temperature levels while also reducing localized hot spots, corrosive gas conditions, slag or clinker formation and UBC. Benefits include improving efficiency, reducing $NO_x$ emissions, increasing output and maximizing availability. Discussion concerning the reduction of greenhouse gases is prevalent in the world. When taking a practical approach to addressing this problem, the best way and short-term solution to reduce greenhouse gases on coal-fired power plants is to improve efficiency. From this point of view the real time optimized combustion tuning approach is the most effective and implemented with minimal cost.

• Resources Recycling
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• v.27 no.3
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• pp.39-47
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• 2018

According to Vietnam government establishes additional coal-fired power plants to secure generation capacity, emission of ashes is accelerating and processing them is urgent issue. This study targeted utilize fly ashes that occurred in circulating fluidized bed combusion (CFBC) power plant to use ground solidification materials. CFBC fly ashes are used to make solidification with ground granulated blast furnace slag (GGBFS), gypsum and cement. Then produced specimens by mixing with soft ground soil to confirm mixing effect of fly ash in solidification. As a result it was possible to find mixture design that is satisfied 3 MPa compressive strength in age 28 days and reduce weight loss rate over 50% in acid immersion test than plain specimens that using only ordinary portland cement.

• Journal of the Korea Institute of Building Construction
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• v.11 no.4
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• pp.363-370
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• 2011

This study considerated reject ash, wastes of coal-fired power plants, to use mineral admixtures for cement. The pozzolan activity selected the fineness of the efficient reject ash through comparison and it compared to the fly ash that are widely used for concrete mixed material. Cement composites was prepared replacing of slag cement by fineness reject ash and fly ash, and properties of cement composites was tested by paste(setting time, fluidity, instrumental analysis) and mortar(compressive strength). Instrumental analysis results showed hydration reaction of fineness reject ash was not different from fly ash, but had more dense micro structures. Results of physical properties showed fineness reject ash shorten setting time, increased compressive strength compared by fly ash. Therefore using fineness reject ash with $6,000cm^2$/g to concrete mineral admixtures or cement composites was might be possible and could contribute to improve properties of concrete.

• Resources Recycling
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• v.6 no.1
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• pp.29-34
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• 1997

The feasibility of using the industrial inorganic waste materials such as l~mestone sludge. Soundly sand. coal fly 'ash, and chemical glasses as a raw material for cement clinker by melting treatmeut was iovestigated. The slag wh~ch is obtained from thc melts of the mixtnres of waste materials is composed of P-C,S(ZCaO - SIOJ and C,AS(ZCaO . AI,O, . SiO,) phases. The effect of melting tempcrabre, coaling condition and CIS ratio on the fo~mation of P-C,S phasc was examed. In order to obtain thc P-CiS phase which is useful in thc utilhtion as a clinkcr malcrid, it B found that sudl considerations as low melting temperature as possible of the wastc mixhire, quenching the melts and law CIS ratio of the mlxhlre are necessary.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.128-135
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• 2011

In this study, in order to develop ultra rapid hardening mortar(URHM) for tunnel repairs using bottom ash of low recycle ratio and Admixture as Eco concept, fundamental properties of URHM on temperature condition of construction field were performed. Test result, URHM of three types for fluidity and setting time were as in the following : B > C > A. Those for low temperatures were later than the standard condition. Compressive, bending and bond strength were similar with three types as follow. In compressive strength, initial strength of the low were smaller than the standard but the low in the long-term were similar with the standard. On the contrary to this, bending strength were similar in initial strength but the low in the long-term were smaller than the standard. The low in bond strength was average 35% less than the standard. Length changes was as in the following : A > C > B. the low is two times much as the standard but the case using blast furnace slag particles noticeably reduced length changes. Water absorption coefficient and water vapor resistance were as in the following : C > A > B. In case of URHM added bottom ash, water absorption coefficient and water vapor resistance were increased because bottom ash is porous material.