【作者】

Masaaki Okubo,Takuya Kuwahara

【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。The regulations governing marine diesel engine NOx emission in the International maritime Or ganization(IMO)emission standards have become more stringent. Because it is difficult to fulfill these requirements by means of combustion improvement alone, effective aftertreatment technology is needed to achieve efficient NOx reduction. Here, we pro pose an effective PM and NOx simultaneous reduction aftertreatment system that employs a nonthermal plasma(NTP)hybrid process. Compared with selec tive catalytic reduction(SCR), the proposed technol-gy offers the advantage of treatment at a low tem-perature of less than 150.C, without the use of urea solution and harmful heavy-metal catalysts. First, laboratory-scale experiments are performed with a nerator(YDG200VS-6E, YANMAR Co, Ltd, Japan)(specifications: single cylinder; rotat ing speed, 3600 rpm; and maximum output power, 2.0kW). Marine diesel oil (MDO, sulfur=0.067 mass%)is used as a fuel. The system mainly consists of a ma-rine diesel engine, an adsorption chamber containing adsorbent pellets that can adsorb/desorb NOx in an exhaust gas by controlling their temperature, an NTP reactor, and a diesel particulate filter(DPF). Whole ex haust gas flows to the system at 300 NU/min.The aftertreatment comprises(a) adsorption, (b)desorp-ion, and (c) cooling processes. In the adsorption process, an exhaust gas first passes through a DPF where particulate matter is removed. Subsequently, the gas is cooled by an air-cooling radiator and then passes through an adsorption chamber where NOx is removed by adsorption. The mass flow rate of these gases is measured at the exit of the chamber by a NOx analyzer. The clean gas then flows out of the syst In the desorption process, the exhaust gas first passes through a heat exchanger integrated into the adsorp- tion chamber. where it heats the adsorbent pellets to induce thermal desorption of NOx. Simultaneously, N gas is supplied to the pellets at 10 NUmin. Then, NOx is eluted. The NOx +N2 gas is subsequently reduced P reactor. The oncentration is measured after the confluence of the exhaust gas and the reduced gas. In the cooling process the re-maining NOx in the pellets is desorbed by introducing air into the adsorption chamber at 50 Nu/min with the help of the residual heat. The desorbed NOx is recir culated into the intake of the engine to enhance total NOx reduction. Based on the measured nox concen-trations and the power consumptions for ntP gener ation, adsorbed NOx in the adsorption process, and desorbed NOx and treated NOx in the desorption and cooling processes are found. Considering these ob tained values, the energy efficiencies upon NOx re-moval are calculated and the performance of the sys tem is evaluated. The time-dependent NOx emission from the aftertreatment system is shown in Fig. 1The white circles indicate the mass flow rates of un treated NOx, and the black circles indicate those of the treated NOx. the shaded areas indicate the masses of NOx treated in processes(a)-(c). A series of pro cesses (a)-(c)are repeated. As a result, a NOre-moval of 437 g/kWh is achieved with significant en-ergy efficiency. Next, based on the above laboratory scale experiments, we developed the system pilot-scale aftertreatment. Pilot-scale experiments are performed for the first time with a marine diesel engine(6DK-20, Daihatsu Diesel MFG, Co, Ltd, Japan)(specifications: six cylinders, rotating speed, 900 rpm maximum output power, 1, 100 kW; mass flow rate of exhaust gas, 6, 815 Nm/h; and load, 100%). The system consists of a scale-up adsorption chamber, 48surface-discharge-type NTP reactors, DPFS, and cool ers. DPF regeneration using plasma-induced o3 is performed in parallel. An exhaust gas with a mass flow rate of 800 Nm/h is among the total emissions flowing to the system. The aftertreatment comprises(a)adsorption and(b) desorption processes. These processes are repeated alternatively. N2 gas at 200Umin is int

【会议名称】

第27届CIMAC会议

【会议地点】

上海

【下载次数】

1

返回