• Journal of Information Processing Systems
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• 제15권1호
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• pp.189-202
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• 2019

During thermal power coal-fired boiler operation, it is very important to detect the pulverized coal concentration in the air pipeline for the boiler combustion stability and economic security. Because the current measurement methods used by power plants are often involved with large measurement errors and unable to monitor the pulverized coal concentration in real-time, a new method is needed. In this paper, a new method based on microwave circular waveguide is presented. High Frequency Electromagnetic Simulation (HFSS) software was used to construct a simulation model for measuring pulverized coal concentration in power plant pipeline. Theoretical analysis and simulation experiments were done to find the effective microwave emission frequency, installation angle, the type of antenna probe, antenna installation distance and other important parameters. Finally, field experiment in Jilin Thermal Power Plant proved that with selected parameters, the measuring device accurately reflected the changes in the concentration of pulverized coal.

• 한국연소학회지
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• 제19권3호
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• pp.8-17
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• 2014

The aims of this research were to evaluate effects of biomass co-firing to pulverized coal power plants and the variation of co-firing ratios on the plant efficiency related to power consumption of auxiliary system and flue gas characteristics such as production and component by process simulation based on the existing pulverized coal power plant. In this study, four kinds of biomass are selected as renewable fuel candidates for co-firing: wood pellet(WP), palm kernel shell(PKS), empty fruit bunch(EFB) and walnut shell(WS). Process simulation for various biomass fuels and co-firing ratios was performed using a commercial software. Gas side including combustion system and flue gas treatment system was considering with combination of water and steam side which contains turbines, condenser, feed water heaters and pumps. As a result, walnut shell might be the most suitable as co-firing fuel among four biomass since when 10% of walnut shell was co-fired with 90% of coal on thermal basis, flue gas production and power consumption of auxiliary systems were the smallest than those of other biomass co-firing while net plant efficiency was relatively higher than those of other biomass co-firing. However, with increasing walnut shell co-firing ratios, boiler efficiency and net plant efficiency were expected to decrease rather than coal combustion without biomass co-firing.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.967-972
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• 2001

The emission of $NO_{x}$ during coal combustion is a major reason of environment impact. $NO_{x}$ is an acid rain precursor and participates in the generation of smog through ozone production. $NO_{x}$ can be divided into thermal $NO_{x}$, fuel $NO_{x}$ and prompt $NO_{x}$. Thermal $NO_{x}$ is formed in a highly temperature condition dependent. Fuel $NO_{x}$ is dependent on the local combustion characteristics and initial concentration of nitrogen bound compound, while prompt $NO_{x}$ is formed in a significant quantity in some combustion environments, such as low temperature and short residence times. This paper presents numerical simulation of the flow and combustion characteristics in the furnace of a tangential firing boiler of 500MW with burners installed at the every comer of the furnace. The purpose of this paper is to investigate the reduction of $NO_{x}$ emission in a 500MW pulverized coal tangential firing boiler with different OFA's and burner angles. Calculations with different air flow rates of over fired air(OFA) and burner angles are performed.

• 한국연소학회지
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• 제20권3호
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• pp.35-42
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• 2015

Investigating coal combustion in a large-scale boiler using computational fluid dynamics (CFD) requires a combination of flow and reaction models. These models include a number of rate constants which are often difficult to determine or validate for particular coals or furnaces. Nonetheless, CFD plays an important role in developing new combustion technologies and improving the operation. In this study, the model selection and rate constants for coal devolatilization, char conversion, and turbulent reaction were evaluated for a commercial wall-firing boiler. The influence of devolatilization and char reaction models was found not significant on the overall temperature distribution and heat transfer rate. However, the difference in the flame shapes near the burners were noticeable. Compared to the coal conversion models, the rate constant used for the eddy dissipation rate of gaseous reactions had a larger influence on the temperature and heat transfer rate. Based on the operation data, a value for the rate constant was recommended.

• 한국정밀공학회지
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• 제25권1호
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• pp.92-98
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• 2008

The flame image observation and analysis has been investigated for combustion monitoring and management of the pulverized coal firing for thermal power plant, especially for lower nitrogen oxide generation and safer operation. We aimed at obtaining the relationship between burner flame image information and emissions of nitrogen oxide and unburned carbon in furnace utilizing the flame image processing methods, by which we quantitatively determine the conditions of combustion on the individual homers. Its feasibility test was undertaken with Samchonpo thermal power plant #4 unit which has 24 burners, through which the system was observed to be effective for evaluating the combustion conditions and continuous monitoring to prevent future loss of ignition.

• KEPCO Journal on Electric Power and Energy
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• 제2권4호
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• pp.525-529
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• 2016

바이오매스 혼소는 신재생 에너지의 비중을 늘리면서 석탄화력발전에서의 $CO_2$ 배출을 저감할 수 있는 단중기적으로 가장 효과적인 방법이다. 본 논문에서는 이 중 기존 화력발전소에 가장 적은 초기투자비로 적용할 수 있는 직접 혼소법에 대하여 주로 고찰을 수행하고, 국내외 현황 및 전망에 대해 기술하였다. 직접 혼소법은 바이오매스 전용 미분기를 사용하여 혼소율을 늘리는 방법과 저 혼소율에서 초기투자비를 최소화하는 기존 석탄 미분기 사용 바이오매스 혼소법으로 나눌 수 있다. 유럽 및 미국에서는 혼소율을 높이기 위해 많은 상용발전소에서 바이오매스 전용 미분기를 사용하여 10~20% 가량의 혼소율(열량 기준)로 운전을 수행하고 있으나, 국내의 경우에는 RPS 대응을 위해 3~5% 가량의 혼소율에서 기존 석탄 미분기를 그대로 사용하여 바이오매스 혼소를 수행하고 있다. 신기후체제가 시작되고 석탄화력발전에서의 $CO_2$ 저감 요구가 점점 더 증대될 것으로 예상되는 바, 향후 바이오매스 고혼소율이 수행될 수 있는 기술적/저책적 방안이 모색되어야 하며, 이 경우 발생할 수 있는 설비에의 악영향을 면밀히 고려한 연료 표준화 및 전처리 기술이 개발되어야 한다.

• Korean Chemical Engineering Research
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• 제44권5호
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• pp.489-497
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• 2006

국내 무연탄을 사용하는 미분탄 화력보일러(영동화력 2호기)를 대상으로 비교적 고효율, 저비용으로 전기를 생산하는 청정보일러인 순환유동층 보일러로의 전환 시 경제성 평가 및 민감도 분석을 수행하였다. 경제성 평가는 크게 순환 유동층 보일러로의 전환 시와 기존의 미분탄 보일러를 유지 시에 각각의 투자금액에 대한 경제성 평가와 이의 비교를수행하였으며, 더불어 전력시장의 상황 변화에 따른 경제성 민감도 분석을 수행하였다. 경제성 평가 결과, 현 상태에서는 전력산업기반기금이 지원을 받고 있는 무연탄 발전사업의 특성상 기존 보일러를 유지하는 것이 경제성 지표가 더 좋은 것으로 평가되었으나, 전력산업기반기금의 지원 형태 및 그 규모에 따라 순환유동층으로의 전환이 장기적 발전사업 및 기반기금의 효율적 집행 그리고 국가 에너지 이용률에 있어 더 좋은 경제 지표를 나타내는 것으로 평가되었다

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.337-339
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• 2012

This study investigates the combustion and heat transfer characteristics of a 100MWe pulverized coal boiler retrofitted for demonstration of oxy-coal combustion. By computational fluid dynamics (CFD), the flame temperature and wall heat flux were compared for air-fuel and oxy-fuel combustion with different $O_2$ concentration in the oxidizers. It was found that the oxy-fuel combustion requires an $O_2$ concentration higher than 27 vol.% for the boiler to achieve the similar value of wall heat flux with air-fuel combustion.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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• pp.19-20
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• 2013

The cofiring of renewable fuel in coal fired boilers is an attractive option to mitigate $CO_2$ emissions, since it is relatively low cost option for efficiently converting renewable fuel to electricity by adding biomass as partial substitute of coal. However, it would lead to reduce plant efficiency and flexibility in operation, and increase operation cost and capital cost associated with renewable fuels handling and firing equipment. The aim of this study is to investigate reduction of carbon dioxide at varying percentage of biomass in fuel blend to the boiler biomass, and estimate operation and capital cost. Wood pellet, PKS (palm kernel shell), EFB (empty fruit bunch) and sludge are considered as a renewable fuels for a cofiring with coal. Several approaches by the cofiring ratio are chosen from past plant demonstrations and commercial cofiring operation, and they are evaluated and discussed for CO2 reduction and cost estimation.

• 분석과학
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• 제5권4호
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• pp.433-441
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• 1992

국내의 23개 무연탄을 대상으로 석탄회의 화학분석 및 용융특성분석을 수행하여 석탄회의 화학조성과 용융온도와의 상관성을 고찰하였다. 또한 이들 무연탄을 미분탄 연소의 연료로 사용시 야기될 수 있는 slagging, fouling성을 예측하여 보았다. 국내 무연탄회는 대부분 $SiO_2$와 $Al_2O_3$를 80% 이상 함유하고 있는 반면 1% 이하의 적은 양의 $Na_2O$를 함유하고 있으며, 또한 비교적 높은 용융온도를 갖는다. 따라서 이 무연탄들을 미분탄 연소의 연료로 사용시 slagging 및 fouling 발생 가능성은 낮을 것으로 예측되었다. 국내 무연탄회의 용융특성은 base/acid ratio와 비교적 높은 상관성을 갖는 것으로 나타났다.