• Title/Summary/Keyword: 공기 다단

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A Case Study on Multiple-deck-charge Blasting with Electronic Detonators (전자뇌관과 다단장약을 이용한 발파 사례 연구)

  • Ko, Tae Young;Shin, Chang Oh;Lee, Hyo;Lee, Seung Cheol
    • Explosives and Blasting
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    • v.30 no.2
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    • pp.52-58
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    • 2012
  • A TBM launching shaft in DTL2 Contract 915 site is located in a typical hard Bukit Timah granite formation and lots of blasting work is required for shaft sinking. The original blast design used the electric detonator and ANFO blasts consisting of 30 holes per one blast with 1.5 m depth of drilling hole. However, significant delay of work and poor progress were expected due to the limitation of the number of blasting hole and strict vibration regulation on retaining systems. To overcome such constraints, an efficient new blasting method which can improve productivity and satisfy vibration limit was required. The revised blast design, using triple-deck blasts with electronic detonators and cartridge emulsion explosives, gives better construction performance and can reduce construction time. Such a new blasting technique can be effectively used for similar underground projects in the future where the volume of rock blasting is significant.

Onset and Propagation of Hydrogen-Air Premixed Flame with Multiple Kinetics (다단 반응을 고려한 수소-공기 예혼합 화염의 발생 및 전파)

  • Han Cho Young;Baek Seung Wook
    • Journal of computational fluids engineering
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    • v.9 no.1
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    • pp.25-33
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    • 2004
  • Flame onset and propagation within hydrogen premixed gas mixture are numerically investigated in an rectangular enclosure. A detailed chemistry for hydrogen reaction is applied to anticipate the thermochemical behavior of intermediate species appropriately. To facilitate computation, 10 species and 16 elementary reaction steps for hydrogen combustion are taken into account. On the basis of 30% of hydrogen concentration in hydrogen-air mixture, the effects of position and quantity of ignition sources on the flame evolution are analyzed. From the simulation results, the methods to decrease the potential hazard caused by the flame propagation are suggested.

An Experimental Study on the NOx Formation of Fuel Staged Combustor (연료다단 연소기의 NOx 발생특성에 관한 실험적 연구)

  • 정진도;안국영;한지웅
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.6
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    • pp.73-79
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    • 2003
  • The characteristics of NOx emission in multi fuel/air staged combustor have been experimentally studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel burns. Experiments were performed on a semi-industrial scale (thermal input 0.233 ㎿) in a laboratory furnace and Liquefied Petroleum Gas(LPG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, primary/secondary air ratio, primary swirl intensity and secondary swirl intensity for reducing NOx emission. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

An Experimental Study on the NOx Formation of LNG Flame in Fuel Staged Combustor (다단 연소기를 이용한 LNG 화염의 NOx 발생에 관한 실험적 연구)

  • Chung, Jin-Do;Han, Ji-Woong;Ahn, Kook-Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.4
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    • pp.389-394
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    • 2004
  • An experimental study on the NOx formation of LNG flame in fuel staged combustor has been studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is a act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel bums. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Natural Gas(LNG) was used as a primary and secondary fuels. This study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, and primary/secondary air ratio for reducing NOx emission with two types of nozzle. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

The experimental study on the NOx formation of fuel staged combustor (연료다단 연소기의 NOx 발생특성에 관한 실험적 연구)

  • Han, Ji-Woong;Ahn, Kook-Young;Kim, Han-Seok;Chung, Jin-Do
    • 한국연소학회:학술대회논문집
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    • 2001.06a
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    • pp.163-171
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    • 2001
  • The characteristics of NOx emission in multi fuel/air staged combustor have been experimentally studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot Dame for the secondary combustion stage combustion zone, where most of fuel bums. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Petroleum Gas(LPG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, primary/secondary air ratio, primary swirl intensity and secondary swirl intensity for reducing NOx emission. The test demonstrated that NOx emission can be reduced by ${>}$70% in accordance with operating conditions.

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Reduction of NO Emission by Two-Stage Combustion (2단 연소에 의한 NO 배출 저감에 관한 연구)

  • 유현석;최정환;오신규
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.2
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    • pp.591-596
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    • 1995
  • In order to investigate the reduction of NO emissions, natural gas was fueled for two-stage combustion apparatus. NO and CO emissions were described by five variables: total air ratio, primary air ratio, secondary air injection position, secondary air injection velocity, and swirl ratio. It was mainly observed that, as the primary air ratios of 0 and 0.4 NO emission decreased with increasing the secondary air injection position and secondary air injection velocity. The effect of weak swirl on NO emission was found to be insignificant.

An Experimental study on the NOx Formation of LNG Flame in Fuel Staged Combustor (다단 연소기를 이용한 LNG 화염의 NOx 발생에 관한 실험적 연구)

  • Han, Ji-Woong;Ahn, Kook-Young;Kim, Han-Seok;Chung, Jin-Do;Park, Kyung-Jin
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.161-166
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    • 2001
  • An Experimental study on the NOx formation of LNG flame in fuel staged combustor has been studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel burns. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Natural Gas(LNG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, and primary/secondary air ratio for reducing NOx emission with two types of nozzle. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

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Characteristics of NOB Formation in a Coaxial Multi-Air Staged LPG Flame (동축 공기다단 LPG화염의 NOx 생성특성에 관한 연구)

  • Kim, Han-Seok;Ahn, Kook-Young;Kim, Ho-Keun;Yu, Myung-Jong;Baek, Seung-Wook
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.2
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    • pp.215-226
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    • 2003
  • Experimental and numerical studies have been done to examine the effects of excess air ratio and tertiary air swirl number on the formation characteristics of NOx in a pilot scale combustor adopting a multi-air staged burner. In numerical calculation the mathematical models for turbulence, radiation and nitric oxide chemistry were taken into account. The radiative transfer equation was solved using the discrete ordinates method with the weighted sum of gray gases model. In the NOx chemistry model, the chemical reaction rates for thermal and prompt NOx were statistically averaged using a probability density function. The results were validated by comparison with measurements. For the experiment, a 0.2 MW pilot multi-staged air burner has been designed and fabricated. Using the numerical simulation developed here, a variation of thermal and prompt NOx formation was predicted by changing the excess air ratio and tertiary air swirl number. As the excess air ratio increased up to 1.9, the formation of the total as well as thermal NOx at exit increased while the prompt NOx decreased. The formation of thermal NOx was more affected by concentration of $O_2$ and $N_2$ than gas temperature. When the tertiary air swirl number increased, the formation of the total as well as the prompt NOx slightly decreased.

Characteristics of Multi staged Combustion on a Double-cone Partial Premixed Nozzle (이중 콘형 부분 예혼합 GT 노즐의 다단 연소특성)

  • Kim, Han Seok;Cho, Ju Hyeong;Kim, Min Kuk;Hwang, Jeongjae;Lee, Won June
    • Journal of the Korean Institute of Gas
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    • v.24 no.1
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    • pp.49-55
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    • 2020
  • Experimental investigations were conducted to understand the multi-staged combustion characteristics of a swirl-stabilized double cone premixed burner nozzle used for industrial gas turbines for power generation. Multi-staged combustion is implemented by injecting the fuel through the existing manifold of the side slots as well as through the apex of the cone with two fuel injection angles which are slanted or axial. NOx and CO emissions, and wall temperature distributions were measured for various fuel distributions and operating conditions. Results show that NOx emissions are decreased when the fuel distribution to the apex is 3% of the total amount of fuel, which is due to more uniform fuel distribution inside the nozzle, hence less hot spots at the flame. NOx emissions are rather increased when the fuel distribution to the apex is 8% of the total amount of fuel for axial fuel injection by occurrence of flash back in premixing zone of burner.

Experimental Research of Multi-Stage Axial Compressor Stability Enhancement by Air Injection (다단 축류압축기의 안정성 개선을 위한 실험적 연구)

  • Lim, Young-Cheon;Lim, Hyung-Soo;Song, Seung-Jin;Kang, Shin-Hyoung
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.11a
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    • pp.378-381
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    • 2009
  • A rotating stall, an instable phenomenon of compressor, brings about reducing the pressure rise, the efficiency of compressor and a mechanical demage. In order to improve instability and extend operating range, it was performed that a stability enhancement experiment applying air injection method at the 4-stage low-speed axial compressor. The coanda nozzle was used to inject air in axial direction at rotor tip and 8 injectors were set up at regular interval at the upstream of 1st stage rotor. At 80% speed, injectors were worked before rotating stall happened. As injecting the 5.4% air of mode inception flow rate, the stability of compressor operation enhanced about 4%.

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