Nitrogen oxides environmental issues

A significant issue in combustors in the mid-1990s is the performance of the process in an environmentally acceptable manner through the use of either low sulfur coal or post-combustion clean-up of the flue gases. Thus there is a marked trend to more efficient methods of coal combustion and, in fact, a combustion system that is able to accept coal without the necessity of a post-combustion treatment or without emitting objectionable amounts of sulfur oxides, nitrogen oxides, and particulates is very desirable (51,52). 

The reduction of atmospheric concentrations of the sulfur and nitrogen oxides blamed for acid rain was a major issue in the debate that led to the 1990 Clean Ail-Act Amendments (CAAA). The final legislative action is one of the most complex and comprehensive pieces of environmental legislation ever written. 

Coke does not offer the same potential environmental issues as other petroleum products (Chapter 10 and above). It is used predominantly as a refinery fuel unless other uses for the production of a high-grade coke or carbon are desired. In the former case, the constituents of the coke that will release environmentally harmful gases such as nitrogen oxides, sulfur oxides, and particulate matter should be known. In addition, stockpiling coke on a site where it awaits use or transportation can lead to leachates as a result of rainfall (or acid rainfall) which are highly detrimental. In such a case, application of the toxicity characteristic leaching procedure... 

Carbon and hydrogen in coke can be determined by the standard analytical procedures for coal and coke (ASTM D3178, D3179). However, in addition to carbon, hydrogen, and metallic constituents, coke contains considerable amounts of nitrogen and sulfur that must be determined prior to sale or use. These elements will appear as their oxides (NO, SO ), respectively, when the coke is combusted, thereby causing serious environmental issues. 

In this chapter we discuss the detailed chemistry of selected high-temperature processes where gas-phase reactions are important. Most research on gas-phase reactions has been motivated by environmental issues in atmospheric chemistry or in combustion. Significant advances in the detailed understanding of fuel-oxidation chemistry, as well as nitrogen, sulphur, and chlorine chemistry, have allowed development of modeling tools that can be used for design purposes for a number of combustion and industrial processes. 

Concerns about the environmental effects of emissions resulting from the combustion of fossil fuels, particularly coal, continue to increase as the utilization of these fuels grows. The large amounts of sulfur dioxide and nitrogen oxides emitted into the atmosphere and the attempts to tie these fossil-fuel-derived pollutants directly to the undeniably difficult problem of acid rain have caused heated debates, numerous research studies, government actions, and serious efforts to reduce pollution. The issues are extremely complex, and our understanding of the origin, properties, behavior, and effects of these pollutants is incomplete. Often, theories are contradictory. 

In September, 1998 the United States Environmental Protection Agency (EPA) issued a rale (known as the NOx SIP Call) that required 22 states and the District of Columbia to submit State Implementation Plans (SIP s). These SIP s would reduce emissions of nitrogen oxides (NOx) - compounds that react with other chemicals in the atmosphere to form ozone (or smog). EPA required these reductions after determining that NOx and ozone are transported by the wind to downwind states, which results in unhealthy air quality in the downwind states156. 

Catalytic removal of nitrogen oxides [1] and sulfur oxides [2] is one of the most important issues in environmental problems. We have investigated supported ruthenium carbido-cluster catalysts derived from [RUjC(CO),J crystal. The supported cluster was... 

We must be able to hold a range of scenarios with regard to each possible application. Advanced fossil-fuel technologies, especially coal-based ones, must be able to meet increasingly stringent environmental requirements for critical air pollutants (sulfur dioxide, oxides of nitrogen), as well as other environmental issues (such as liquid and solid waste), and still remain cost competitive with other fossil fuels, especially natural gas [73]. 

Table 3.1. The links between sulfur dioxide and nitrogen oxide emissions, acidic deposition, and a range of environmental issues...

For example, the conversion of the coal-bound sulfur and nitrogen (in addition to any reactions or aerial nitrogen with aerial oxygen under the prevailing conditions) to their respective oxides during combustion is a major environmental issue ... 

This chapter covers the most significant areas where solvents can have an environmental impact, stratospheric ozone depletion (restricted to certain halogenates), tropospheric ozone creation in areas of nitrogen oxide pollution and solvents in water and solid waste. It gives an overview of these issues, and looks at the options available to reduce overall environmental impact. 

Acid rain is an environmental issue that crosses state and national boundaries. Conduct library research on this topic and write a brief report. Include a description of the areas in the United States affected by acid rain, and the geographical source of the sulfur and nitrogen oxides that are responsible for acid rain in each region. 

Environmental issues associated with oxides of sulfur and nitrogen are discussed more fully in later chapters. 

Air Pollution. Particulates and sulfur dioxide emissions from commercial oil shale operations would require proper control technology. Compliance monitoring carried out at the Unocal Parachute Creek Project for respirable particulates, oxides of nitrogen, and sulfur dioxide from 1986 to 1990 indicate a +99% reduction in sulfur emissions at the retort and shale oil upgrading faciUties. No violations for unauthorized air emissions were issued by the U.S. Environmental Protection Agency during this time (62). 

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