【作者】

Timo Murtonen

【摘要】

该论文已在赫尔辛基举行的第28届CIMAC大会上发表，论文的版权归CIMAC所有。The tightening exhaust gas emission limits for power plant and marine applications is a clear trend for the future. One approach to reduce emissions is the use of gaseous fuels like compressed or liquefied natural gas, shale gas or biogas. However, even with gas engines the engine manufactures need to use after treatment systems for meeting the most stringent emission limits. One of the challenges in developing these systems is the size of the final applications and R&D related measurements with full-size prototypes. Typically the catalyst R&D work is done in laboratory with miniature catalyst exposed to synthetic exhaust gas. The next step is to scale up the catalyst to real application which means catalyst sizes of even tens of cubic meters. With the size also the costs increase drastically, not only the cost of the catalyst but also the cost for performing needed measurements on final application. With large gas engines the testing of prototypes in real applications is even more challenging compared to large diesel engines, since the number suitable test facilities or sites is limited. In this study this challenge is noticed and actions have been taken to fulfil the gap in between the lab-scale catalyst development work and the full-scale applications. A research facility with a small spark ignited natural gas (NG) engine and a specially designed catalyst test bench has been build-up. The engine control parameters can be freely adjusted for achieving an exhaust gas matrix corresponding to e.g. power plant exhaust gas composition. A portion of the exhaust gas flow is lead through the catalyst test bench and the exhaust temperature and flow conditions can be varied without changing the exhaust gas composition. It is also possible to “fine tune” the exhaust gas composition by injecting gaseous compounds to the exhaust gas. In the current project “Controlling Emissions of Natural Gas Engine” (CENGE) the test facility has been used for mimicking the exhaust gas emission matrix of NG engine used for power production. A small spark ignited 2.0 litre NG engine was driven with lean air-to-fuel ratio for reaching the reference values which have been taken from a real application. Reference values included four different engine operating modes. The reference exhaust gas components included NOx, CO, THC, CH4, C3H8, C2H4, C2H6, O2 and H2O. The correct emission matrix has been achieved by adjusting engine parameters and injecting some of the hydrocarbon species to the exhaust gas. For example in one test point the measured NOx concentration was ca. 190 ppm (wet) and the reference value was 195 ppm (wet) and the corresponding value (reference value in parentheses) for CO were ca. 400 ppm (375 ppm). A typical challenge in small scale testing is achieving realistic H2O concentrations especially if synthetic exhaust gas is used. The presence of H2O is crucial for after treatment system studies as the materials may show hydrothermal aging in real applications. The use of a small NG engine as the main source of exhaust gas ensures that realistic levels of H2O and O2 are present in the exhaust matrix. The measured H2O and O2 levels were ca. 13.5 % (reference 10%) and ca. 7.5% dry (reference 11% dry).

【会议名称】

第28届CIMAC会议

【会议地点】

芬兰 赫尔辛基

【下载次数】

2

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