Cheng Chih-Wen, Hua Jian, Hwang Daw-Shang
a Department of Marine Engineering , National Taiwan Ocean University , Keelung , Taiwan , ROC.
J Air Waste Manag Assoc. 2017 Oct;67(10):1146-1157. doi: 10.1080/10962247.2017.1356763. Epub 2017 Jul 19.
An important marine pollution issue identified by the International Maritime Organization (IMO) is NO emissions; however, the stipulated method for determining the NO certification value does not reflect the actual high emission factors of slow-speed two-stroke diesel engines over long-term slow steaming. In this study, an accurate method is presented for calculating the NO emission factors and total amount of NO emissions by using the actual power probabilities of the diesel engines in four types of bulk carriers. The proposed method is suitable for all types and purposes of diesel engines, is not restricted to any operating modes, and is highly accurate. Moreover, it is recommended that the IMO-stipulated certification value calculation method be modified accordingly to genuinely reduce the amount of NO emissions. The successful achievement of this level of reduction will help improve the air quality, especially in coastal and port areas, and the health of local residents.
As per the IMO, the NO emission certification value of marine diesel engines having a rated power over 130 kW must be obtained using specified weighting factor (WF)-based calculation. However, this calculation fails to represent the current actual situation. Effective emission reductions of 6.91% (at sea) and 31.9% (in ports) were achieved using a mathematical model of power probability functions. Thus, we strongly recommend amending the certification value of NO Technical Code 2008 (NTC 2008) by removing the WF constraints, such that the NO emissions of diesel engines is lower than the Tier-limits at any load level to obtain genuine NO emission reductions.
国际海事组织（IMO）确定的一个重要海洋污染问题是氮氧化物排放；然而，规定的确定氮氧化物认证值的方法并未反映低速二冲程柴油机在长期低速航行时的实际高排放因子。在本研究中，提出了一种通过使用四种类型散货船中柴油机的实际功率概率来计算氮氧化物排放因子和氮氧化物排放总量的准确方法。所提出的方法适用于所有类型和用途的柴油机，不受任何运行模式的限制，且精度很高。此外，建议相应修改IMO规定的认证值计算方法，以切实减少氮氧化物排放量。成功实现这一减排水平将有助于改善空气质量，特别是在沿海和港口地区，并有助于当地居民的健康。
根据IMO规定，额定功率超过130千瓦的船用柴油机的氮氧化物排放认证值必须使用基于特定加权因子（WF）的计算方法来获得。然而，这种计算方法无法反映当前的实际情况。使用功率概率函数的数学模型实现了6.91%（在海上）和31.9%（在港口）的有效减排。因此，我们强烈建议修改《2008年氮氧化物技术规则》（NTC 2008）的认证值，取消WF限制，以使柴油机的氮氧化物排放在任何负荷水平下都低于Tier限值，从而真正实现氮氧化物减排。
