【作者】

Yoshiyasu Murayama

【摘要】

论文已在中国上海举行的第27届CIMAC大会上发表。论文的版权归CIMAC所有。 In order to meet stringent emission standards for marine engines, we at NIlGATA continue the development of low emission technology for long period. Three emission control technologies exhaust after treatment, alternative fuels and combustion improvement were developed to meet upcoming IMO NOx regulation Tier ll, and these countermeasures can be selected due to required output, applications and ship design. First measure is exhaust after treatment by using the selective catalytic reduction (SCR).NlIGATA has started to provide the marine SCR sys-tem from middle of the 1990s, and have enough experience about performance design and operation. The key issue for marine SCR system is the installation size and control technology which handles suitable amount of reducing agent for each engine loads. On board tests were carried out to verify that performance of our newly-developed SCR system fulfills a required specification for Tier lll. The required injection amount of reducing agent is determined by using several ordinary sensors on engine. In addition, the effect ofatmospheric conditions on NO, emission is also con-sidered. Therefore the developed SCR system is useful not only for domestic vessel but also ocean vessel. The test system was operated to maintain 80%NO, reduction rate from Tier I condition through the on board test and it was successfully controlled without ammonia slip. Second measure is usage of alternative fuels. To date, the gas engine was employed for land-based power generation and cogeneration, several types of gas engine dual fuel, spark ignition and micro pilot engine are reliable, respec-tively. Due to lower adiabatic flame temperature with lean-burn combustion, the NOx emission is extremely low and the emission level is tenth of diesel engines.Consequently, gas engine has a potential to comply with Tier ll by itself. Third measure low NO, technology is the improvement of combustion for diesel en-gine. The Miller cycle is essential combustion technology to decrease NOx emission due to lower incylinder gas temperature and to improve cycle efficiency. This technology was employed on diesel engines to meet Tier ll, however, the magnitude of the effect is enhanced to achieve remarkable NO, emission reduction in this study. Since the extremely highboost pressure is required when stronger Miller cycle is applied, the 2-stage turbocharging system was em- ployed. The obtained NO, reduction from Tier Icondition was reached up to 50% due to double improvement effect regarding the turbocharger efficiency and the cycle efficiency. The EGR which is well known as low NOx emission technology is a good match the 2-stage turbocharging, then further NOx reduction is promising. In other words, the improvement of fuel consumption is possible by synergy effect of 2-stage turbocharging, stronger Miller cycle and EGR. In this paper, the characteristics of each emission control technologies are described respectively. Main part of this paper is SCR and Combustion improvement. Gas engine is also described, however, the detail technical report shall be described in another paper for this congress.

【会议名称】

第27届CIMAC会议

【会议地点】

上海

【下载次数】

1

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