Gaseous emission standards

In March of 1985, in parallel with a significant tightening of gaseous emissions standards, Canada adopted the U.S. particulate standards for cars and light trucks (0.2 and 0.26 grams per mile, respectively) to go into effect in the 1988 Model Year. Since then, Canada has initiated a review of truck controls and is considering adoption of U.S. standards for these vehicles as well. 

Wood-fired power boilers are generally found at the mills where wood products are manufactured. They are fired with waste materials from the process, such as "hogged wood," sander dust, sawdust, bark, or process trim. Little information is available on gaseous emissions from wood-fired boilers, but extensive tests of particulate matter emissions are reported (19). These emissions range from 0.057 to 1.626 gm per dry standard cubic meter, with an average of 0.343 reported for 135 tests. Collection devices for particulate matter from wood-fired boilers are shown in Table 30-21. 

Emissions monitoring is essential in controlling industrial environments and processes to ensure good air quality standards are maintained. It is also required in order that the various regulations and guidelines related to air quality are met. In addition to gaseous emissions, such as sulfur dioxide, carbon monoxide, nitrogen oxides, hydrocarbons, and many others, the emissions of particulate material and heavy metals must also be controlled. 

The gaseous emissions from the FCC unit are CO, NOj, particulates, and SOj. All are either locally or nationally regulated. Table 10-7 shows the current allowable limits of the EPA New Source Performance Standards (NSPS) for the emissions of these airborne pollutants. NSPS levels can be triggered by one of the following conditions ... 

ERA S New Source Performance Standards (NSPS) for Gaseous Emissions from the FCC Regenerators... 

The Subpart O standards4 for hazardous waste incinerators set performance standards that limit the quantity of gaseous emissions an incinerator may release. Specifically, the regulations set limits on the emission of organics, HC1, and PM. The following section outlines the requirements for each of these substances. 

The last point is worth considering in more detail. Most hydrocarbon diffusion flames are luminous, and this luminosity is due to carbon particulates that radiate strongly at the high combustion gas temperatures. As discussed in Chapter 6, most flames appear yellow when there is particulate formation. The solid-phase particulate cloud has a very high emissivity compared to a pure gaseous system thus, soot-laden flames appreciably increase the radiant heat transfer. In fact, some systems can approach black-body conditions. Thus, when the rate of heat transfer from the combustion gases to some surface, such as a melt, is important—as is the case in certain industrial furnaces—it is beneficial to operate the system in a particular diffusion flame mode to ensure formation of carbon particles. Such particles can later be burned off with additional air to meet emission standards. But some flames are not as luminous as others. Under certain conditions the very small particles that form are oxidized in the flame front and do not create a particulate cloud. 

The concentrations of all chemicals to be discharged, including gaseous emissions, must be determined and measures taken to ensure that these levels conform to allowable legislative standards. The cost of clean-up can be high, e.g. scrubbing systems, filters, etc., and may affect... 

Table 15 shows a comparison of SCWO gaseous effluent with the U.S. hazardous waste incinerator air emission standards. While incinerators require multiple clean-up steps to meet the regulations. SCWO inherently meets all but the particulate standard. The SCWO particulate carryover is due to aerosols from the gas-liquid separator, and (assuming a SCWO system was required to meet the incinerator standards) should be readily removed through the use of a coalescing filter. Not shown in Table 15 is the fact that compared to incineration, SCWO produces far lower levels of the acid rain precursor SO2. 

Concerning heavy duty vehicles, table 2 takes into account Directive 91/542/EEC in two steps, aiming at new types of heavy vehicles (diesel and others weighing more than 3.5t) and replaces Directive 88/77/EEC for gaseous emissions and Directive 72/306/EEC for black smoke from diesel vehicles. This directive is the result of a revaluation following the Council of Ministers on 1 October 1991. New implementation dates, as well as new standards were established. Directive 91/542 EC is known under the term "clean lorry" directive. 

The limit value proposed for the type-approval of new car models, independent of the weight and engine size, is 1.3g per European test as defined in Directive 70/220/EEC. The limit value proposed for conformity of production, or otherwise, that which every new car must meet on its first registration, is 1.7g/test. These limit values are proposed to be implemented at the dates agreed at the Luxembourg Council for the implementation of the new European standards for gaseous emissions. By that means the Commission intends to assure that the motor industry can concentrate its resources on adapting its production to the new Community requrements as a whole and that the administrative procedures related to the type-approval of modified car models will be limited to what is strictly necessary. 

On the political level, initiatives are being taken to allow the "Luxembourg agreements" to become operational, to adopt the proposed particulate standards and the standards for gaseous emissions of commercial vehicles. 

Increased use of leaded gasoline in Canada may generate pressures to control automotive exhaust lead emissions, although there is no established health-based lead-in-air standard to serve as the basis for such control. If reduction of automotive lead emissions into the atmosphere should be required, controls should be placed on the amount of lead emitted from the tailpipe, similar to the manner by which gaseous emissions are controlled. Such action is more energy efficient than reducing the amount of lead used in gasoline. One effective way to control tailpipe lead emissions is the use of automotive exhaust lead trap that replaces the standard muffler (2). 

The test fleet consisted of eight identically-equipped 1974 four-door Chevrolet Biscaynes operated by the Department of National Defence, Canada. These cars were equipped with 5.74 litre V-8 engines having air pumps to supply secondary air to the exhaust manifolds to reduce gaseous emissions. Four vehicles were equipped with new standard muffler and exhaust pipe systems and were used as control cars. The standard mufflers and exhaust pipes of the second group of four cars were replaced with lead trap systems. 

Emission standards are govemmentally promulgated limits on the emission of a pollutant from a process. There are limits on the emission of specific gaseous, vapor, and particulate pollutants from any process and on their emission from specific processes. Some countries (e.g., the United States) officially promulgate and publish their emission standards for new sources for a number of processes and for hazardous pollutants from ary process (Table XI). In the United States, emission standards for existing sources are promulgated and published by state and local air pollution control authorities. Some countries (e.g., Russia) do not promulgate or publish emission standards. 

In Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), a gaseous, solid (as fine particles), or liquid (as an aerosol) sample is directed into the center of a gaseous plasma. The sample is vaporized, atomized, and partially ionized in the plasma. Atoms and ions are excited and emit light at characteristic wavelengths in the ultraviolet or visible region of the spectrum. The emission line intensities are proportional to the concentration of each element in the sample. A grating spectrometer is used for either simultaneous or sequential multielement analysis. The concentration of each element is determined from measured intensities via calibration with standards. 

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