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本文研究第三代试验型柴油机氧化催化器(DOC)对一台2850kW EMD SD60M型USEPA(美国环保局)Tier0排放达标机车的排放性能的影响。该机车原造于1989年,柴油机于2005年完成最近一次大修,并达到US EPA Tier0排放标准。DOC系统位于涡轮前废气流内。在这台属于联合太平洋铁路的机车上按机车联邦试验程序(FTP)进行了氧化催化器安装前后的对比试验。然后,机车在加利福尼亚州投入商业运营,在分别完成6个月和14个月运营之后,再返回西南研究所进行排放测试和DOC检查。早先的两代DOC于2006年5月开始安装在同一台机车上。最初的试验结果表明,由MIRATECH公司制造并提供的V-CAT柴油机氧化催化器使机车在干线负荷循环的颗粒物(PM)排放率减少46%,在调车负荷循环中颗粒物减少32%。碳氢化合物(HC)和一氧化碳(CO)在US EPA干线循环分别减少57%和78%,在调车循环则分别减少55%和69%。V-CAT柴油机氧化催化器的初始试验也证明燃油效率损失甚微,机车带与不带V-CAT的对比试验表明,燃油消耗率在干线牵引循环仅增加0.5%,在调车循环则基本上无变化。在第6手柄位,由于发动机换气量的减少,烟度有所增大,但仍远低于Tier0烟度限值标准。装车运用6个月和14个月后的测试表明,排放性能和发动机性能均无明显恶化。在运用6个月和14个月后的V-CAT检查证明,耐久性没出现大的问题。在14个月验证期内,也没进行对排气后处理装置的维修。根据该试验计划所取得的结果,DOC也许会成为各种型号的EMD机车达到Tier0+PM标准的有效工具。为进一步验证长期可靠性,看来还需要对EMD机车加装任何“改型”的DOC进行进一步的现场运行考验,因为这些机车的柴油机在两次大修之间通常会运用7~10年。
This paper investigates the effect of the third generation Diesel Oxidation Catalysts (DOC) on the emission performance of a 2850kW EMD Model SD60M USEPA (U.S. Environmental Protection Agency) Tier0-compliant locomotive. Originally built in 1989, the diesel engine completed its last major overhaul in 2005 and met the US EPA Tier 0 emission standards. The DOC system is located in the turbine exhaust stream. On this locomotive belonging to the Union Pacific Railroad, a comparative test was carried out before and after the installation of the oxidation catalyst according to the locomotive federal test program (FTP). The locomotive was then put into commercial operation in California and returned to the Southwest Research Institute for emission testing and DOC inspection after completing six months and 14 months of operation respectively. The earlier two generations of DOC started installation on the same locomotive in May 2006. Initial test results showed that the V-CAT diesel oxidation catalyst manufactured and supplied by MIRATECH reduced locomotive PM emissions by 46% over the main load cycle and by 32% during the shunting load cycle. Hydrocarbons (HC) and carbon monoxide (CO) decreased by 57% and 78%, respectively, in the US EPA trunkline, and by 55% and 69% respectively during the shunting cycle. Initial tests of the V-CAT diesel oxidation catalyst also demonstrated little loss of fuel efficiency, and comparative tests between locomotive and without V-CAT showed that the fuel consumption rate increased only 0.5% during the main traction cycle, while the shunt cycle was essentially No change. At the 6th handle position, smoke levels increased due to reduced engine ventilation but still well below Tier 0 smoke limits. Tests performed 6 and 14 months after loading showed no significant deterioration in emissions and engine performance. V-CAT examinations at 6 months and 14 months after application demonstrated no major problems with durability. During the 14-month validation period, no servicing of the exhaust aftertreatment device was performed. Based on the results of this pilot program, the DOC may be an effective tool for meeting the Tier0 + PM standards for all types of EMD locomotives. To further validate long-term reliability, it would appear that a further on-site test of the EMD locomotive with additional “retrofit” DOCs is required as these locomotive diesels typically operate between seven and 10 years between major overhauls .