Emission standards types

Sulfur dioxide is generated in large quantities during the primary zinc refining process and sulfur fixation is carried out concurrently with the primary production process in order to meet CAA emission standards. Concentrations of sulfur dioxide in the off-gas vary with the type of roaster operation. Typical concentrations for multiple-hearth, suspension, and fluidized-bed roasters are 4.5 to 6.5%, 10 to 13%, and 7 to 12%, respectively. This sulfur dioxide is then converted into sulfuric acid. 

The final performance standard is for toxic metals. For RCRA combustion units, both carcinogenic and noncarcinogenic metals are regulated under the same type of tiered system as chlorine. The facility determines an appropriate tier for each regulated metal and assures that the facility meets these feed rate and emission standards. A different tier may be selected for each metal pollutant. 

BIFs are required to comply with strict air emission standards to ensure adequate protection of human health and the environment. These standards are divided into four contaminant categories organics, PM, metals, and HC1 and chlorine (Cl2). For each category or type of emission, the regulations establish compliance methods and alternatives. Each is addressed in Table 23.3. 

In most countries, environmental regulation of chemicals started with the introduction of emission standards. The air pollution control law and the water pollution control law were typical examples of this type. 

In our urban areas, we recognize two main types of pollution one coming from single sources—e.g., power plants and foundries, the other coming from multiple sources—e.g., the automobile. For the single, isolated sources, the ambient air standards are translated without too much difficulty into source emission standards. We have reasonably reliable mathematical formulae and empirical data to predict ground concentra-... 

North American emission requirements Two sets of US Federal emission standards are defined for cars and light-duty trucks, Tier 1 and Tier 2. Tier 1 requirements were published in 1991 and fully implemented in 1997. Tier 2 standards were adopted in 1999 and began to be phased in commencing in 2004. The emission targets for each vehicle depend upon its weight and service type. 

The characteristic modular construction of fuel cells is of utmost importance. With a number of standard type cells, coupled to each other in series or in parallel, almost every desired combination of voltage and capacity can be realized. One of the more attractive aspects of the fuel cell compared to more conventional methods of electricity generation is its environmental impact the fuel cell produces less waste, a lower level of emissions and almost no noise. 

For all other vehicles covered by the scope of the present directive, notably those of category Nj ("light duty trucks") it has been agreed to follow an approach analogous to that chosen for the private cars below 1.4 litres i.e. to introduce interim emission standards. These consist of the limit values of Directive 83/351/EEC, the application of which to the concerned vehicles will imply a reduction of their HC and NOx emissions in the order of 25% compared to the present situation. These interim standards will apply from 1 October 1989 to new vehicle types and from 1 October 1990 to all new vehicles put into service. 

Two types of catalytic converters are currently being used for meeting the passenger car emission standards in the U.S. three-way converters and dualbed converters. Both converters contain three-way catalysts, but with the dual-bed converter the three-way catalyst is followed by an air injection/ oxidation catalyst system. As for the earlier oxidation catalysts two forms of catalyst support are used pellets (thermally stable transitional alumina) and monoliths (cordierite honeycombs coated with a thin alumina washcoat). Figure 7 shows four catalytic converters currently being used by General Motors. 

U.S. emissions standards (LEV ULEV) in the late 1990 s will require catalysts with improved HC removal and probably at least some NOx reduction activity, as well. Emissions standards for diesel autos in Europe will require improved HC removal to meet EURO II levels for HC + NOx- Catalyst "C" has been reformulated with additional oxide components and varying precious metal loadings to address these needs. The new type of catalyst, designated Catalyst "D" in this paper, has been found to exhibit improved HC removal, especially at low exhaust temperatures. 

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