Seongpil Joo

Effect of Hydrogen Content on the Gas Turbine Combustion Performance of Synthetic Natural Gas

This paper investigates the effect of hydrogen content on the gas turbine combustion performance of synthetic natural gases to determine whether they are adaptable to industrial gas turbines. Synthetic natural gases which are composed of methane, propane and varying amounts of hydrogen (0%, 1%, 3% and 5%), are tested in ambient pressure and high temperature conditions at the combustion test facility of a 60kWth industrial gas turbine. Combustion instabilities, flame structures, temperatures at nozzle, dump plane and turbine inlet, and emissions of NOx and CO are investigated for the power outputs from 35 to 60kWth. With increasing hydrogen content, combustion instabilities are slightly alleviated and the frequency of pressure fluctuation and heat release oscillation is increased. NOx and CO emissions are almost similar in trends and amounts for all tested fuels, and the undesirable phenomena from addition of hydrogen such as flashback, auto-ignition and overheating of fuel nozzle were not observed. Synthetic natural gas with less than 1% hydrogen showed no difference in gas turbine combustion characteristics, while synthetic natural gases containing hydrogen of over 3% showed a slight difference in combustion instability such as amplitude and frequency of pressure fluctuations and heat release oscillations. From these results, we conclude that the synthetic natural gas containing less than 1% hydrogen is adaptable without retrofitting any part of the combustor, and Korea coal-SNG Quality Standard Bureau is planning to establish the SNG quality standards, guaranteeing hydrogen content of up to 1%.Copyright

The Effect of Fuel Composition on Combustion Instability Mode Occurrence in a Model Gas Turbine Combustor

Recently, energy resource depletion and unstable energy prices have become global issues. Worldwide pressure to secure and make more gas and oil available to support global power needs has increased. To meet these needs, alternative fuels composed of various types of fuels have received attention, including biomass, dimethyl ether (DME), and low rank coal. For this reason, the fuel flexibility of the combustion system becomes more important. In this study, H2 and CH4 were selected as the main fuel composition variables and the OH-chemiluminescence measurement technique was also applied. This experimental study was conducted under equivalence ratio and fuel composition variations with a model gas turbine combustor to examine the relation between combustion instability and fuel composition. The combustion instability peak occurs in the H2/CH4 50:50 composed fuel and the combustion instability frequency shifted to higher harmonic of longitudinal mode based on the H2 concentration of the fuel. Based on instability mode and flame length calculation, the effect of the convection time during the instability frequency increasing phenomenon was found in a partially premixed gas turbine combustor. The time-lag analysis showed that the short convection time in a high H2 concentration fuel affects the feedback loop period reduction and, in these conditions, high harmonics of longitudinal mode instability occurs.This fundamental study on combustion instability frequency shifting characteristics was conducted for H2/CH4 composed fuel and the results contribute key information for the conceptual design of a fuel flexible gas turbine and its optimum operation conditions.© 2015 ASME

Experimental Study on Combustion Instability Characteristics of Model Gas Turbine Combustor at Various H2/CH4/CO Composition

ABSTRACT IGCC(Integrated Gasification Combined Cycle) system is candid ates which can solve the environmental problems including global warming, since it can b e easily combined with CCS(Carbon Capture System). In this research, combustion instability chara cteristics were studied at various fuel which are composed of H 2 /CH 4 /CO mixture. Mode analysis for instabilities observed experimen tally was conducted and the linearly increasing tendency of frequency was observed as the hydrogen content in fuel increases.초 록 IGCC(Integrated Gasification Combined Cycle) 의 경우 CCS(Carbon Capture System) 시스템과의 결합을 통하여 지구온난화와 같은 환경문제를 해결할 수 있는 발전 방식의 하나로 여겨진다. 따라서 합성가스 연소특성에 대한 연구가 중요하며 본 연구에서는 H 2 /CH 4 /CO로 구성된 합성가스 조성을 바꾸어가며 가스터빈 연소불안정 특성에 대한 실험적 연구를 수행하였다. 실험과정에서 발생한 연소불안정에 대한 모드 분석을 수행하였고 연료 중 수소 비율 증가에 따른 주파수 천이 현상 또한 확인하였다.Key Words: IGCC(석탄가스화 복합발전), Syngas(합성가스), Combustion Instability(연소불안정), Gas Turbine(가스터빈), Fuel Composition(연료조성)Received 1 June 2013 / Revised 7 November 2013 / Accepted 15 No vember 2013