The vehicle emission regulations have been driving forces for advancing the technologies of vehicle engines, and have led to the drastic reduction of pollutant emissions from each vehicle. However, the increasing number of vehicles in the world still causes many issues need to be solved, e.g. air quality, climate change, and energy consumption. Therefore, the emission limits and fuel economy standards are being tightened year by year. As recent topics, new regulations, such as particle number (PN) in EU countries and greenhouse gas (GHG) emission in US, have been enforced. In addition, the Worldwide harmonized Light vehicles Test Procedure (WLTP) has been issued by UNECE/WP.29. The test procedures and measurement conditions defined in EU regulations will be revised in the near future, in response to increasing interest in real-world emission (RDE). New procedures or regulations sometimes require updating measurement techniques. This article gives an outline of emission regulation trends for light-duty vehicles and introduces advanced emission measurement technologies from the view-point of relation with such regulations.
The rapid and precise element measurement technique of trace species, such as mercury, iodine, and strontium is important for various applications, especially for trace species analysis in exhausts. The trace elements such as mercury, iodine, arsenic, and strontium were measured by laser-induced breakdown spectroscopy (LIBS) and laser breakdown time-offlight mass spectrometry (LB-TOFMS) for comparison of the corresponding detection features. Emissions and ion signals are detected by LIBS and LB-TOFMS to evaluate elemental composition. Multi-photon ionization and electron impact ionization in the plasma generation process can be controlled by the pressure and laser pulse width. According to the experimental results, the detection limits of mercury and iodine in N2 were 3.5 ppb and 60 ppb using low pressure LIBS. The mercury and iodine detection limits using LB-TOFMS were 1.2 ppb and 9.0 ppb. The detection systems of LIBS and LB-TOFMS can be selected depending on the condition of each application.
Recently, small size once-through boilers are widely used in the industry as a source of heat due to their high level safety and simplicity of operation (It accounts for more than 95 % of the number of boilers shipped in Japan). As the interests in energy concerns and environmental problems increase throughout the world, the regulations related to the energy efficiency and the environmental footprint of the fuel burning equipment tend to be strengthened. Against this background, the performance of the once-through boiler improved considerably employing new technologies such as, higher thermal efficiency on the heat exchangers, combustion controls with smaller purge losses, improvement of the burner allowing low excess air operations, higher efficiency using the multiple-boiler control system, improvement of the condensate recovery system, etc… As far as the NOx emission is concerned, 65ppm (corrected to 0% O2) is achieved on oil (A-oil) fired boiler using the self-recirculation type burner, and 25ppm (corrected to 0% O2) on gas (natural gas) fired boiler using “Non-furnace low NOx combustion technique”. Lower NOx emission level can also be achieved combining other low NOx techniques to comply with more stringent regulations which can be found in some oversea countries.
Nitrogen oxides (NOx) from waste incinerator is one of the typical regulated toxic substances. In Europe and America, the emission control based on BAT (Best Available Techniques) which is unfamiliar in Japan is also adopted to strengthen NOx regulation. It is expected that the regulation of NOx from waste incinerator is becoming strict more and more in future. By the way, the emission of NOx can be reduced by two type technologies. The first technology is to prevent NOx production by well controlled combustion, and the other is to reduce NOx by flue gas treatment technology like SNCR (selective non-catalytic reduction process) and SCR (selective catalytic reduction process). In this paper, the trend of NOx regulation and emission control technologies adopted in waste incinerators are introduced. First, NOx regulation values in Japan and foreign countries are surveyed, and details of NOx control technologies actually used in our plants are explained together with our study results.
Coal is an important energy resource for meeting the further demand for electricity, as coal reserves are much more abundant than those of other fossil fuels. Coal contains heavy metal in a very small amount other than major components. Most of heavy metal which is called trace elements in coal is collected to flue gas treatment equipment such as electrostatic precipitator and flue gas desulfurization equipment. But emission ratio to air of the highly volatile elements such as mercury is higher than other element. Recently, emissions of trace elements from coal combustion have been viewed as a global environmental issue. Mercury, selenium, boron are highly volatile among trace elements included in the coal, and the behavior in the plant is very complicated. In this paper, for mercury, selenium and boron, an outline of a domestic environmental regulation trend, the behavior in coal combustion plant and measurement technology is explained.
Anhydrous liquid ammonia offers a considerable advantage over hydrogen in that it has a large volumetric energy density. The total amount of energy that would be expended for its production and transportation to consumers is estimated to be less than that for liquid hydrogen transportation, even if some lower heating value is lost through chemical conversion. From a storage viewpoint, the advantages of energy density would be particularly beneficial to automobiles carrying traveling energy with them. Ammonia has some attractive thermodynamic properties for internal combustion engines as well as higher ignition temperature to mitigate knocking. Although ammonia has a low flame velocity for use in internal combustion engines, an auto-thermal-cracker providing hydrogen helps the engine to run stably. A challenge in SIP program is promoting combustion to achieve as high combustion efficiency as current gasoline combustion with minimum auxiliary fuel.
To understand the high-pressure premixed combustion mechanism in a meso-scale packed porous bed, crosssectional visualization of propagating flames in a packed bed was performed at high pressure up to 1.0 MPa. For easy optical access to the interior, a two-dimensional pseudo packed bed combustor was developed, which has quartz-glass cylinders installed in a rectangular duct representing the network of meso-scale flow channels of the bed. Visualization of propagating flames in the 2-D packed bed was performed using both a visible-light high-speed photography and Planar Laser Induced Fluorescence (PLIF) method targeting OH radicals. Fast flame propagation through the 2-D packed bed with a broad chemiluminescence region was observed at high pressure, characteristics of which was presumed to be identical to the fast flame propagation in the packed bed of spheres in authors' previous research. Instantaneous cross-sectional visualization with OH-PLIF was subsequently conducted. Obtained PLIF images as well as the result of turbulence measurement in the 2-D packed bed showed that turbulent flames with concave and convex cusps can be formed even in meso-scale flow channels at high pressure, resulting in a high flame displacement speed. The mechanism of the turbulent flame formation in quite a narrow flow channel was subsequently explained by comparison among characteristic scales of turbulence, hydrodynamic flame instability combined with diffusive-thermal effect, and flow channels. OH-PLIF images also revealed the existence of multiple propagating flame fronts inside the broad chemiluminescence region, in which the leading flame front was presumed to be predominant on the flame propagation in the packed bed.