两级增压废气再循环降低船用柴油机排放的试验研究

Experiment Investigate on Reducing Emissions of a Marine Diesel Engine with Two Stage Turbocharging and Exhaust Gas Recirculation System

关键词:  废气再循环  两级增压  柴油机  排放  试验

Key words:  EGR  Two stage turbocharging  Diesel engine  Emission  Experiment

摘要:

针对6CS21型船用发电柴油机，试验研究了两级增压废气再循环技术对柴油机排放性的影响。研究结果表明，应用两级增压结合废气再循环（Exhaust Gas Recirculation，EGR）系统，可以提高增压压力、实现较高的EGR率，通过提高EGR率、提前喷油正时、调整喷油压力，可同时实现燃油消耗率和NO_x排放的降低，低负荷采用弱米勒可以解决因强米勒循环带来的低负荷进气不足问题。面向IMO Tier III和CNII排放限值分别研究了低排放和低油耗两种运行模式，发现低排放模式下，在加权燃油消耗率与原机保持一致的同时，使NO_x排放降低77.8%，达标IMO Tier III法规；低油耗模式下，在加权燃油消耗率相比于原机降低2.9%的同时可使NO_x排放降低50.1%，且排放可满足CNII标准。

Abstract:

Through experiment on 6CS21 marine generator diesel engine， the effects of two stage turbocharging and exhaust gas recirculation technology on the emissions performance of marine diesel engine have been investigated. The research results show that the application of two stage turbocharging combined with an Exhaust Gas Recirculation（EGR） system can increase the boost pressure and achieve a higher EGR rate. By increasing the EGR rate， advancing the fuel injection timing， and adjusting the fuel injection pressure， the fuel consumption rate and NO_x emissions can be reduced at the same time. Using weak Miller at low load can solve the intake shortage problem caused by the strong Miller cycle. Aiming at satisfing IMO Tier III and CNII emission limits， two operating modes which named low emission and low fuel consumption model have been studied respectively. Among them， in the low emission mode， the weighted fuel consumption rate remains the same as original engine， and NO_x emissions are reduced by 77.8%， which can meet IMO Tier III emission regulation. In the low fuel consumption mode， the weighted fuel consumption rate is reduced by 2.9% compared with the original machine， while NO_x emissions can be reduced by 50.1%， and the emissions can meet the CNII standard.