한국폐기물자원순환학회지 제35권 제3호 (p.258-267)

가스터빈 효율 향상 핵심 이론연구와 LNG와 HHO 혼소에 의한 수치 해석적 검증

An Intensive Theoretical Study for the Increase of Gas Turbine Efficiency and Numerical Evaluation by the Co-burning of HHO with LNG in a Gas Turbine Combustor
키워드 :
Brayton cycle,Lean burn,Gas turbine efficiency,Turbulent mixing,HHO,H2

목차

Abstract
I. 서 론
II. 기술현황 분석 및 이론적 연구
III. 수치 해석적 연구방법
IV. 연구 결과
IV. 결 론
References

초록

The energy efficiency of gas turbine using LNG as a fuel has reached to less than about 40% even for the H class gas turbine. To increase the energy efficiency, in theoretical analysis, the maximum value of fuel efficiency can be obtained via the equally large value of the mixing rate and reaction rate in the harmonic-mean type overall reaction rate expression. Even if the delayed mixing rate can be overcome successfully by the strategy of the practically proved lean-burn method, however, the critical problem caused by the retarded reaction rate caused by the excess air has to be solved in order to make any breakthrough of the engine or gas turbine fuel efficiency. To do this, a series of systematic numerical calculation has been made for the evaluation of the lean-burn CH4 flame feature with the addition of small amount of H2 or HHO (H2+1/2O2, water electrolysis gas). To maintain lean burn state, the flow rate of methane was greatly reduced less than 50% of the standard flow rate. The addition of HHO or H2 heating value has increased steadily from 5, 10 and up to 20% of the 100% CH4 flow rate. And investigation of flame characteristics such as peak flame temperature and its location together with the temperature profile has been made through numerical calculation for a gas turbine combustor. For the standard case of 100% CH4 injection, the flame temperature profile was observed to increase steadily from the primary combustor region to gas turbine inlet. This is exactly corresponds to the temperature profile appeared in a heating process with constant pressure assumption in a typical Brayton cycle. However, for the case of co-burning with H2 or HHO with only 40 and 50% CH4 injection, the peak flame temperature appears near the upstream primary region and decreases significantly along the downstream toward turbine inlet. A detailed discussion further has been made for the flame characteristics with the change of added fuel amount and its type. In summary, the addition of the H2 and HHO gas with the reduced amount of the CH4 flow rate results in quite different temperature profile expected from the standard Brayton cycle. Further this kind of flame feature suggests the possibility of high fuel efficiency together with the reduction of the metallurgical thermal damage of the turbine blade due to the decreased gas temperature near turbine inlet.