Speciated hydrocarbon emissions from small utility engines

Partially speciated hydrocarbon (HC) emissions data from several small utility engines, as measured by a Fourier Transform Infrared analyzer, are presented. The engines considered have nominal horsepower ratings between 3.7 and 9.3 kW. Both side-valve and overhead-valve engines are studied, and four different fuels are used in the engines. The results indicate that the small HCs present in the exhaust tend to be in the form of either methane or unsaturated HCs. Other small alkanes, such as ethane and propane, are present in only relatively small concentrations. In terms of ozone formation potential, the HCs in the form of methane will lead to little ozone, but the distribution of the C2 and C3 species is not ideal from an ozone reduction stand-point. It is also found that the presence of oxygen in the fuels appears to lead to somewhat more complete combustion, although the effects are not large. Finally, the overhead-valve engines appear to have lower HC emissions than side-valve engines, which is primarily due to higher operating A/F ratios and the engine geometry.     

Emissions and demonstration of an emission control technology for small two-stroke utility engines

Small utility engines represent an important contribution to the emissions inventory and have been subjected to increasingly stringent regulations in recent years. For this project, a Tanaka two-stroke engine was tested in its original condition and with a modified fuel/oil injection system. The modified fuel/oil injection system applied to the Tanaka two-stroke engine resulted in significant emissions reductions of approximately 52% for carbon monoxide (CO), 70% for total hydrocarbons (THC), 70% for particulate matter (PM), and 67% for the regulated THC + nitrogen oxides metric. This technology met the California Air Resources Board's 2000 model-year regulations for all pollutants, with the exception of slightly higher PM emissions. Two additional two-stroke engines were tested under a new condition and after at least 100 hr of use to examine the effects of deterioration on in-use, two-stroke engines. For one engine, CO and PM emissions more than tripled after 162 hr of operation in the field, with smaller increases also observed for THC (20%). For the second engine, significant repairs were required throughout the 100 operating hours, which counteracted the effects of the emissions deterioration and resulted in lower CO and THC emissions.     

Catalyst Deterioration over the Lifetime of Small Utility Engines

Abstract

In this paper, the deterioration of catalysts in small, four-stroke, spark-ignition engines is described. The laboratory testing performed followed a proven test method that mimics the lifetime of a small air-cooled utility engine operating under normal field conditions. The engines used were single-cylinder, 6.5-hp, side-valve engines. These engines have a nominal 125-hr lifetime. The effectiveness of the catalysts was determined by testing exhaust emissions before and after the catalyst to determine the catalyst’s efficiency. This was done several times during the lifetime of the engines to determine the deterioration in the performance of the catalysts at lowering pollutant emissions. Additional testing was performed on the catalysts to determine wear patterns, contamination, and recoverable activity. The results indicate that considerable catalyst deterioration is occurring over the lifetime of the engine. The results reveal that soot buildup, poisons, and active surface loss appear to be the contributing factors to the deterioration. These results were determined after analyzing the exhaust emissions data, scanning electron microscope results analysis, and the impact of regeneration attempts. An ANOVA statistical analysis was performed, and it was determined that the emissions are also impacted, to some degree, by time and the engine itself.     

Simulation of atmospheric PAH emissions from diesel engines

Simulation of atmospheric PAH emissions in a typical European passenger car diesel engine at steady conditions or under a certification cycle is made using in-house software. It is based on neural fitting of experimental data from eight different fuels tested under five operating steady conditions (reproducing modes of the European transient urban/extraurban certification cycle). The software allows the determination of PAH emissions as a function of the fuel composition parameters (aromatic content, cetane index, gross heat power, nitrogen and sulphur content) and operation conditions (torque and engine speed). The mathematical model reproduces experimental data with a maximum error of 20%. This tool is very useful, since changes in parameters can be made without experimental cost and the trend in modifications in PAH emissions is immediately obvious.     

The role of the national recycling utility in the Korean economy

As the Korean national economy has continued to grow and the industrial structure has become increasingly advanced, the amount of wastes being generated is rapidly on the rise. Recycling to cope with the environmental problems caused by wastes has become an increasingly important policy issue in developing countries such as Korea, as well as in developed countries. To provide policy-makers with practical and responsible analysis regarding the role of the national recycling utility in the economy, this study employed input–output (I–O) analysis with specific application to Korea. The major goal was the development of a static I-O framework for examining the role of the national recycling utility in the short run. The second goal was to obtain at least a preliminary indication of the role of the national recycling utility. This paper also discusses the role of a public firm that was established with an objective of promoting and facilitating the reuse of recyclable wastes. The overall results indicate that the national recycling utility may have a significant influence on the standard of living and industrial production.     

Effectiveness of emission control technologies for auxiliary engines on ocean-going vessels

Large auxiliary engines operated on ocean-going vessels in transit and at berth impact the air quality of populated areas near ports. This paper presents new information on the comparison of emission ranges from three similar engines and the effectiveness of three control technologies: switching to cleaner burning fuels, operating in the low oxides of nitrogen (NOx) mode, and selective catalytic reduction (SCR). In-use measurements of gaseous (NOx, carbon monoxide [CO], carbon dioxide [CO2]) and fine particulate matter (PM2.5; total and speciated) emissions were made on three auxiliary engines on post-PanaMax class container vessels following the International Organization for Standardization-8178-1 protocol. The in-use NOx emissions for the MAN B&W 7L32/40 engine family vary from 15 to 21.1 g/kW-hr for heavy fuel oil and 8.9 to 19.6 g/kW-hr for marine distillate oil. Use of cleaner burning fuels resulted in NOx reductions ranging from 7 to 41% across different engines and a PM2.5 reduction of up to 83%. The NOx reductions are a consequence of fuel nitrogen content and engine operation; the PM2.5 reduction is attributed to the large reductions in the hydrated sulfate and organic carbon (OC) fractions. As expected, operating in the low-NOx mode reduced NOx emissions by approximately 32% and nearly doubled elemental carbon (EC) emissions. However, PM2.5 emission factors were nearly unchanged because the EC emission factor is only approximately 5% of the total PM2.5 mass. SCR reduced the NOx emission factor to less than 2.4 g/kW-hr, but it increased the PM2.5 emissions by a factor of 1.5-3.8. This increase was a direct consequence of the conversion of sulfur dioxide to sulfate emissions on the SCR catalyst. The EC and OC fractions of PM2.5 reduced across the SCR unit.     

Deactivation of the Vanadia Catalyst in the Selective Catalytic Reduction Process

Results are summarized of a comprehensive study of the effects on the SCR process of all major possible poisons encountered in the combustion gases from U.S. coals. A general rule evolved from this study Is that the effect of the additive on the catalyst activity Is directly related to the basicity of the additive; poisoning Is caused by the basicity. Quantitative effects are presented, while a qualitative summary is given as follows: strong poisons-alkali metal oxides; weak poisons-oxides of alkaline earth metals, arsenic, lead phosphorus and chlorides of strong alkaline metals. SO₂ is a promoter due to its acidity. HCI, although acidic, reacts with both NH₃ (forming NH₄CI) and V₂O₅ (forming VCI₂ and VCI₃) and consequently strongly deactivates the SCR reaction.

A summary is also given for a theoretical and experimental study of the monolithic honeycomb reactor using both undoped and poison-doped catalysts. The results showed that the reactor performance can be predicted directly from the intrinsic catalyst activity through a model.     

Kinetics of Catalytic Oxidation of Benzene,n-Hexane,and Emission Gas from a Refinery Oil/Water Separator over a Chromium Oxide Catalyst

ABSTRACT

With the advances made in the past decade, catalytic incineration of volatile organic compounds (VOCs) has become the technology of choice in a wide range of pollution abatement strategies. In this study, a test was undertaken for the catalytic incineration, over a chromium oxide (Cr₂O₃) catalyst, of n-hexane, benzene, and an emission air/vapor mixture collected from an oil/water separator of a refinery. Reactions were carried out by controlling the feed stream to constant VOC concentrations and temperatures, in the ranges of 1300–14,700 mg/m³ and 240–400 ° C, respectively. The destruction efficiency for each of the three VOCs as a function of influent gas temperature and empty bed gas residence time was obtained.

Results indicate that n-hexane and the oil vapor with a composition of straight- and branch-chain aliphatic hydrocarbons exhibited similar catalytic incineration effects, while benzene required a higher incineration temperature or longer gas retention time to achieve comparable results.

In the range of the VOC concentrations studied, at a given gas residence time, increasing the operating temperature of the catalyst bed increased the destruction efficiency. However, the much higher temperatures required for a destruction efficiency of over 99% may be not cost-effective and are not suggested. A first-order kinetics with respect to VOC concentration and an Arrhenius temperature dependence of the kinetic constant appeared to be an adequate representation for the catalytic oxidation of these volatile organics. Activation energy and kinetic constants were estimated for each of the VOCs. Low-temperature destruction of the target volatile organics could be achieved by using the Cr₂O₃ catalyst.     

Determination of polycyclic aromatic ketones in particulate emissions of internal combustion engines

Benzanthrone (7-H-benz(de)anthracene-7-one, MW 230) and another polycyclic aromatic ketone (6-H-benzo(cd)pyrene-6-one, MW 254) are identified in particulate emissions from both air-cooled and water-cooled automobile engines operating on gasoline. The concentrations of these compounds are roughly equal to [Formula: see text] in these sources. Determination is carried out by capillary gas chromatography using glass and fused silica columns coated with SE-54, OV-1 or Dexsil 300. Results are confirmed by GC/MS. GC/MS data indicate that other polycyclic aromatic ketones are present at much lower concentrations than the two compounds described above. This is different from PAHs, where a large number of isomeric compounds are present at similar concentrations.     

脱硝催化剂孔结构及其脱硝特性的研究

选择性催化还原脱硝技术(SCR)所采用的催化剂多数为多孔介质,其内部孔隙有助于提高催化剂的反应活性。文中采用浸渍负载法,通过改变制备温度制备出不同孔结构的催化剂样品,采用N2吸附法对其孔结构进行测定和分析,并对不同孔结构的催化剂样品进行了脱硝实验。研究表明:煅烧及干燥温度对催化剂孔结构有很大的影响,比表面积越大,其催化剂内的孔分布宽度越窄,平均孔径越小;在活性温度范围(360～390℃)内,脱硝过程中主要是属于化学反应过程控制,脱硝效果随着比表面积的增大而增强;在非活性温度范围内,脱硝过程同时受到气体扩散过程及化学反应过程控制。     

在用轻型汽油车排放随行驶里程劣化规律分析

基于佛山市3.5万条简易稳态工况(ASM)下的尾气排放检测数据,通过分类统计和线性拟合方法分析在用轻型汽油车的污染物排放浓度随行驶里程的劣化规律。分析结果表明,该地区轻型汽油车污染物排放浓度主要分布于低值区间,超过85%的样本数据低于最低排放限值;车辆排放劣化特征随行驶里程呈规律性变化,行驶里程在0~5万km时污染物排放缓慢增长,5万~16万km时呈快速线性增长,16万km后震荡缓慢增长;行驶里程在16万km前,不同车型的排放特征存在一定差异,其中轻型货车和轻型客车的排放浓度高、劣化速度快;CO、HC、NO随行驶里程的劣化规律可用线性增长模型表示。本研究结论可为预测机动车污染变化趋势、完善在用车检查/维护制度、高排放车辆识别和淘汰等方面提供理论支持。     

Techno-economic assessment of coconut biodiesel as a potential alternative fuel for compression ignition engines

Over the past years, there were dramatic improvements in identifying and assessing various feedstocks for the production of biodiesel fuels. To promote a particular feedstock as a renewable source of energy, it is important to analyze their energy, economic, and engine performance characteristics. The current work attempts to evaluate the net energy and economic indices for both fossil diesel and coconut-blended diesel (B20) considering the diesel consumption by the Indian railways. Further, we present the experimental results of a multi-cylinder diesel engine operated with neat coconut biodiesel (B100) and fossil diesel at various load and speed conditions. The engine experiments reveal that the coconut biodiesel exhibits leaner combustion and shorter ignition delay than fossil diesel. Lower amount of carbon monoxide, hydrocarbon, and smoke emission is observed in the case of coconut biodiesel, with higher levels of nitric oxide (14%) and fuel consumption than diesel. The coefficient of variation in indicated mean effective pressure is within the range of better driveability zone for both the fuels at all test conditions. Overall the engine performance, emission and combustion results with neat coconut biodiesel are favorable with a penalty in NO emission at high load conditions. The techno-economical study highlights higher production cost per liter of B20 than the cost of fossil diesel. However, the net energy ratio (NER) for B20 is 1.021, favoring higher output than diesel and thus lowers the dependency on crude oil.

     

Cost of lower NOx emissions: Increased CO2 emissions from heavy-duty diesel engines

This paper highlights the effect of emissions regulations on in-use emissions from heavy-duty vehicles powered by different model year engines. More importantly, fuel economy data for pre- and post-consent decree engines are compared.The objective of this study was to determine the changes in brake-specific emissions of NO_x as a result of emission regulations, and to highlight the effect these have had on brake-specific CO₂ emission; hence, fuel consumption. For this study, in-use, on-road emission measurements were collected. Test vehicles were instrumented with a portable on-board tailpipe emissions measurement system, WVU's Mobile Emissions Measurement System, and were tested on specific routes, which included a mix of highway and city driving patterns, in order to collect engine operating conditions, vehicle speed, and in-use emission rates of CO₂ and NO_x. Comparison of on-road in-use emissions data suggests NO_x reductions as high as 80% and 45% compared to the US Federal Test Procedure and Not-to-Exceed standards for model year 1995–2002. However, the results indicate that the fuel consumption; hence, CO₂ emissions increased by approximately 10% over the same period, when the engines were operating in the Not-to-Exceed region.     

Sampling and analysis of polycyclic aromatic hydrocarbons (PAH) from two-stroke chain-saw engines

A sampling and analysis method for PAH from two-stroke engines is described. The method, which uses a standard glass fiber filter with a back-up section of Amberlite XAD-2 for sampling and GC or GC-MS for analysis, is suitable for both emission studies and occupational studies during logging. Filters and XAD-2 are desorbed with cyclohexane in an ultrasonic bath. After separation on a silica-gel micro column, the samples are submitted to analyses by capillary GC. The method is simple and covers both gaseous and particulate PAH. Naphthalene and alkyl substituted naphthalenes are also quantified.     

Impact of banning of two-stroke engines on airborne particulate matter concentrations in Dhaka, Bangladesh

Vehicular air pollution is common in growing metropolitan areas throughout the world. Vehicular emissions of fine particles are particularly harmful because they occur near ground level, close to where people live and work. Two-stroke engines represented an important contribution to the motor vehicle emissions where they constitute approximately half of the total vehicle fleet in Dhaka city. Two-stroke engines have lower fuel efficiency than four-stroke engines, and they emit as much of an order of magnitude and more particulate matter (PM) than four-stroke engines of similar size. To eliminate their impact on air quality, the government of Bangladesh promulgated an order banning all two-stroke engines from the roads in Dhaka starting on December 31, 2002. The effect of the banning of two-stroke engines on airborne PM was studied at the Farm Gate air quality-monitoring station in Dhaka (capital of Bangladesh), a hot spot with very high-pollutant concentrations because of its proximity to major roadways. The samples were collected using a "Gent" stacked filter unit in two fractions of 0-2.2 microm and 2.2-10 microm sizes. Samples of fine and coarse fractions of airborne PM collected from 2000 to 2004 were studied. It has been found that the fine PM and black carbon concentrations decreased from the previous years because of the banning of two-stroke engine baby taxies.     

A study of extractive and remote-sensing sampling and measurement of emissions from military aircraft engines

Aircraft emissions contribute to the increased atmospheric burden of particulate matter (PM) that plays an important role in air quality, human health, visibility, contrail formation and climate change. Sampling and measurement of modern aircraft emissions at the engine exhaust plane (EEP) for engine and fuel certification remains challenging, as no agency-certified method is available. In this paper we summarize the results of three recent field studies devoted to investigate the consistency and applicability of “extractive” and “optical remote-sensing” (ORS) technologies in the sampling and measurement of gaseous and PM emitted by a number of military aircraft engines. Three classes of military engines were investigated; these include T56, TF33, and T700 & T701C types of engines, which consume 70–80% of the military aviation fuel each year. JP-8 and Fischer–Tropsch (FT)-derived paraffinic fuels were used to study the effect of fuels. It was found that non-volatile particles in the engine emissions were in the 20 nm range for the low power condition of new helicopter engines to 80 nm for the high power condition of legacy engines. Elemental analysis indicated little metals were present on particles, while most of the materials on the exhaust particles were carbon and sulfate based. Alkanes, carbon monoxide, carbon dioxide, nitrogen oxides, sulfur dioxide, formaldehyde, ethylene, acetylene and propylene were detected. The last five species were most noticeable only under low engine power. The emission indices calculated based on the ORS data deviate significantly from those based on the extractive data. Nevertheless, the ORS techniques were useful in the sense that it provided non-intrusive real-time detection of species in the exhaust plume, which warrants further development. The results obtained in this program help validate sampling methodology and measurement techniques used for non-volatile PM aircraft emissions as described in the SAE AIR6037 (2009).     

A Laboratory Method for the Simulation of Automobile Exhaust and Studies of Catalyst Poisoning

The expected use of catalytic converters on automobiles to meet the legislated automotive emission standards makes desirable a laboratory method that permits realistic testing of these catalysts. Such a method should be versatile enough to simulate a wide range of conditions which are applicable for catalysts designed to oxidize hydrocarbons and carbon monoxide, or to reduce nitric oxide, as the case may be. For this purpose, we have modified a pulse-flame combustor, based on a design by Meguerian. The output of this simulator very closely resembles engine exhaust with respect to composition, space velocity, and contaminants. The durability of a monolithic or pelleted catalyst can be evaluated by long term exposure to the simulated exhaust and by periodic measurement of the catalyst activity as a function of temperature. The apparatus and the range of conditions that can be achieved are described in detail. Poisoning of a Pt catalyst by fuels containing low concentrations of lead was studied with this exhaust simulator and compared with results obtained in engine dynamometer tests; a satisfactory correlation of catalyst deterioration was established.