基于SCR技术的车用柴油机排放后处理的新技术

选择性还原(SCR,Selective Catalytic Reduction)技术是目前降低车用柴油机NOx排放最有效的后处理技术之一,但是由于其受到温度,催化剂活性,燃油品质等众多因素的影响,使其在某些工况下达不到排放标准。笔者介绍了Blue Tech技术、不同催化剂组合技术(VCCT,Various Catalyzer Combination Technology)、低温等离子辅助还原技术(LTPACR,Low Temperature Plasma Catalytic Reduction)几种基于SCR技术的车用柴油机排放后处理的新技术,对各种技术的理论基础、系统组成及工作原理做了详细描述。     

创民族名牌 做环保先锋——全国内燃机标准化技术委员会柴油发动机SCR汽车尾气后处理工作组在无锡凯龙汽车设备制造有限公司建成

日前,全国内燃机标准化技术委员会柴油发动机SCR汽车尾气后处理工作组在无锡市凯龙汽车设备制造有限公司正式成立,标志着我国柴油机SCR尾气后处理技术取得了创新突破,它将引领中国柴油机排放进入崭新的时代。国家环保部《关于实施国家第9阶段车用压燃式发动机与汽车污染物排放标准的公告》发布,柴油商用车国Ⅳ排放标准将于2013年7月1日起在全国范围内正式实施。如何应对全行业对国Ⅳ标准的实施,抓紧时间认真落实,专     

汽车发动机“十二五”发展规划目标

一．技术创新方面 1．传统车用发动机技术升级从欧Ⅲ到欧Ⅵ的技术跨越。需要重点突破一批关键技术：汽油机——涡轮增压技术、可变气门正时技术、缸内直喷技术等；柴油机——先进燃油喷射系统、可变截面涡轮增压、EGR、SCR及DPF等后处理技术、电控技术等。     

车用柴油机DOC应对不同细分市场的开发

中国车用柴油机已执行国六排放标准,需要使用柴油机氧化催化器(DOC)才能满足法规要求。本文以某款重型柴油机为基础,搭载多通道排放测试发动机台架,对比不同方案DOC对一氧化氮(NO)转化效率、碳氢(HC)起燃、选择性催化还原(SCR)转化效率等影响,得出DOC配方变化对催化器性能影响的规律。结合车用柴油机在不同细分市场的使用需求,给出满足车辆应用及成本最优的差异化DOC方案。     

沙漠环境对车用柴油机性能的影响及对策研究

综述了沙漠地区地理和气候环境特点,分析了沙漠环境对车用柴油机动力性及可靠性的影响,提出了改善车用柴油机沙漠适应性的技术措施,为提高车辆沙漠环境适应性提供技术支撑。     

车用柴油机常见故障维修技术研究

随着柴油机技术的不断成熟,部分车辆选配柴油机作为动力源,以满足车辆的日常运行动力需求。为保证车用柴油机的整体运行安全性与可靠性,需针对车用柴油机的常见故障进行维修处理,如核心零配件的损耗故障、高温故障、异响故障、起动故障等,选择针对性维修技术,快速高效处理车用柴油机故障。下文就车用柴油机常见故障维修技术分析探讨。     

车用尿素溶液一体化气动供给系统设计

针对柴油机Urea-SCR系统需求,设计开发了一种车用尿素溶液一体化气动供给系统,该系统集成了尿素溶液的存储、计量喷射、雾化等功能。利用汽车压缩空气作为尿素溶液的驱动力及辅助雾化的动力来源,该供给装置具有结构简单紧凑、工作可靠、计量精确等优点。详细分析了系统的组成、工作原理、设计要求等内容,阐述了气动式SCR系统的结构,制作了供给系统的样机,并与重型柴油机进行了ESC和ETC联合试验。试验结果表明,该供给系统能根据柴油机的运转工况,喷入雾化良好、计量精确的尿素溶液,显著降低排气中的NOx浓度,使柴油机排放水平达到国IV法规要求,对实现SCR系统国产化具有重要意义。     

试论基于SCR技术的船舶柴油机尾气处理系统

SCR技术在船舶柴油机尾气处理装置中有重要的应用,能够有效降低船舶氮氧化物的排放量。本文首先对SCR的应用发展现状,以及SCR技术在研究发展中存在的问题做简要的分析,从SCR技术的工作原理、结构的组成、SCR的工作流程、关键设备催化反应器几方面为出发点,探讨基于SCR技术的船舶柴油机尾气处理系统。     

满足欧Ⅲ及以上标准的重载车用柴油机排放控制技术

本文简要介绍了柴油机达到欧Ⅲ及以上排放标准的主要技术措施，并对重载车用直喷式柴油机加以重点说明。     

基于低摩擦的柴油机节能新方法研究

针对车用柴油机节能问题,提出一种基于低摩擦技术的柴油机综合节能方法。研究柴油机摩擦副低摩擦技术,采用涂层技术与润滑技术减少摩擦副磨损;搭建柴油机节能综合试验台,通过油耗仪和尾气分析仪检测节能减排效果。实验研究表明,采用涂层技术与耐磨润滑油,具有较好的节能效果,实现柴油机的节能,这为车用柴油机的节能减排提供了新的方法与思路。     

Experimental verification of optimized NOX reduction strategies in a decrepit Euro-3 diesel engine retrofitted with a cooled EGR system

Vehicle-produced NOx is among emissions that deteriorate human health and the environment. To regulate the NOx emissions from transport, especially from diesel-powered vehicles, various standards have been established globally, and regulations are becoming more stringent across the world. Considerable NOx from diesel vehicles are due to the compression ignition characteristics of engines. Accordingly, to meet the national and global standards, manifold advanced aftertreatment technologies, such as EGR, SCR and LNT, have been developed and widely adopted since introduction of the Euro-4 standards in 2006. In Korea, current allowable NOx standards have been greatly reinforced to one fourth of the permissible level in 2004 and one sixth in 2000. However, the percentage of diesel vehicles in Korea more than 10 years old, manufactured prior to Euro-4, is still significant, accounting for 29% of passenger vehicles, 32% of buses, and 45% of trucks in total registration. Against this backdrop, tremendous efforts are required to improve air quality, especially in metropolitan areas. Of all technical options currently available, installing a cooler to typical EGR systems is considered as a more efficient way for superannuated diesel vehicles to meet the Euro-4 than installing a SCR or LNT in terms of technical acceptability and costeffectiveness. In this study, NOx characteristics of a decrepit Euro-3 diesel engine are thoroughly analyzed before and after the installation of the EGR coolers with different cooling capacities. By applying real time control of EGR rate and exhaust backpressure in calibration procedures, optimized NOx reduction strategies are established.

     

选择性催化还原反应器数值模拟及仿真研究

以柴油机为动力装置排放的氮氧化物是大气的首要污染物,选择性催化还原技术(SCR)是控制氮氧化物的主流技术.文中建立了耦合计算流体动力学和化学动力学的实际柴油机尿素-SCR反应系统的三维数值模型,对SCR系统的内部工作过程进行了模拟仿真.分析各种参数的变化对尿素-SCR系统NOx转化率的影响,为优化尿素SCR反应器的结构指出研究方向,使其在各种环境下,氮氧化物的转化率都能达到比较理想值,以降低氮氧化物的排放,减小对环境的污染和破坏.     

Effects of insulation on exhaust temperature and subsequent SCR efficiency of a heavy-duty diesel engine

Journal of Mechanical Science and Technology - Ammonia/urea selective catalytic reduction (SCR) is an efficient technology to control NOx emission from diesel engines. One of the critical...     

柴油/乙醇混合燃料对发动机排放性能分析

介绍了在柴油中混合不同比例的乙醇对柴油机CH、NOx和碳烟排放的影响.采用柴油/乙醇制成不同比例乳化燃料在一台直喷、增压、中冷柴油机上进行试验.试验结果表明随着乙醇掺烧比例的增加,HC排放逐渐的增加,尤其在小负荷工况范围内,HC排放恶化严重;NOx排放在小负荷工况下有所改善;发动机碳烟排放逐渐的降低.     

柴油引燃甲醇双燃料发动机排放性能试验分析

介绍了柴油引燃甲醇双燃料燃烧对柴油机CH、NOx和碳烟排放的影响。采用柴油引燃甲醇双燃料在一台单缸、直喷、中冷柴油机上进行。随着甲醇质量分数的增加,HC排放迅速增加,NOx排放减少,发动机碳烟排放大幅度降低。     

The experimental investigations of recirculated exhaust gas on exhaust emissions in a diesel engine

The effects of recirculated exhaust gas on the characteristics of NOx and soot emissions under a wide range of engine loads were experimentally investigated by using a four-cycle, four-cylinder, swirl chamber type, water-cooled diesel engine operating at three engine speeds. The purpose of this study was to develop the EGR-control system for reducing NOx and soot emissions simultaneously in diesel engines. The EGR system is used to reduce NOx emissions, and a novel diesel soot removal device with a cylinder-type scrubber for the experiment system was specially designed and manufactured to reduce soot contents in the recirculated exhaust gas to the intake system of the engine. The experiments were performed at the fixed fuel injection timing of 4° ATDC regardless of experimental conditions. It was found that soot emissions in exhaust gases were reduced by 20 to 70% when the scrubber was applied in the range of the experimental conditions, and that NOx emissions decreased markedly, especially at higher loads, while soot emissions increased owing to the decrease in intake and exhaust oxygen concentrations, and the increase in equivalence ratio as the EGR rate is elevated.     

Experimental study on optimization of over-fire air in modified combustion condition with selective catalytic reduction

Recently, the use of NOx control retrofits is significantly increasing due to further tightening of regulations caused by worldwide environmental concerns. In order to reduce NOx emissions, most of the generators are equipped with SCR (Selective Catalytic Reduction) or OFA (Over-Fire Air) systems, while some generators being equipped with both systems. Here we present experimental evidence of higher boiler efficiency with efficient NOx control with consideration for influences on unburned carbon, under the condition that it should meet local and federal emissions requirements. The higher boiler efficiency has been achieved for a newly installed SCR system by optimizing OFA and reducing excess air quantity. The test was conducted over 6 months with a 500 MW coal-fired boiler. Stepwise closing of OFA dampers was carried out with and without simultaneous excess air optimization at a 500 MW nominal rating. We confirmed that our new operation leads to the following benefits: a) Reduction of UBC due to higher temperature in the furnace’s main combustion zone, b) Improved fly-ash recycling ratio, c) Reduction of spray water into re-heater due to lower temperatures in the second (upper) combustion zone, and d) Reduction of exhaust gas loss. As a result, the boiler efficiency has increased by up to 0.4% and UBC (unburned carbon) has decreased by 0.8%. In conclusion, we confirmed that our new operation mode yields better boiler efficiency for newly installed SCR systems and mixed coal firing operating conditions.     

Analysis on possibility of expanding low-load operation area for homogeneous charge compression ignition in CI engine with variable exhaust valve actuation

Various technologies are being studied for the advancement of diesel passenger cars and associated environmental regulations. Effective compression ignition combustion in diesel engines is highly dependent on the cylinder charging temperature, composition, and cylinder pressure during valve train operation. The application of variable valve control in diesel engines has several potential advantages. In this study, we applied the variable valve actuation system to a single-cylinder engine model using a GT-POWER simulation and analyzed the effects of the recompression and rebreathing valve profiles, and fuel-injection pressure on the combustion characteristics of a compression ignition engine. As a result, NOx emissions were reduced by more than 90 %, while those of indicated mean effective pressure were reduced by up to 35 %. The benefits of recompression strategies in terms of NOx emissions reduction were confirmed.

     

柴油机电动EGR控制执行机构运动仿真分析

在汽车排放出的几种污染物中,氮氧化物(NOx)是较难控制的一种.采用废气再循环技术(EGR)降低氮氧化物(NOx)排放已被证实是较有效的措施,而且技术改动小,设计自由度大,因而日益受到了人们的重视.EGR系统的作用是将部分废气引出排气系统再送人进气系统,并对废气量进行最佳的控制与调节,以降低NOx排放.使用Pro/E对...     

柴油机SCR瞬态参数采集处理与诊断系统

基于尿素SCR系统瞬态特性,开发了适合柴油机SCR瞬态参数的测试与诊断系统;采用DASYLab软件,编写了接口、标定与诊断程序,实现了SCR系统信号显示、存储与再现等功能;依据遍历跟踪与诊断程序,实现了对柴油机SCR系统瞬态特性参数的在线测试与诊断;依据柴油机瞬态测试循环法规,进行了柴油机SCR系统的NOx转化效率、尿素喷射量和NH3泄漏量等测试与诊断试验。结果表明:与标准的AVL测试系统(AVL CBE-Ⅱ气体排放分析与测试系统)相比,所研发的系统动态最大误差为2.05%,动态平均误差为0.82%,故障诊断精确率达到了98.6%,能满足柴油机SCR瞬态测试循环要求。