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Energy and the environment
Published in Peter M. Schwarz, Energy Economics, 2023
Economists cheered the use of cap-and-trade as more efficient than CAC. Under technology standards, all firms must use a required technology to reduce emissions, such as a scrubber to reduce sulfur. Under performance standards, all firms must reduce emissions by the same percentage, although they have flexibility on the technology to achieve the standard. Emissions trading allows further efficiency gains by allowing producers capable of reducing emissions at low cost to sell permits to firms with higher marginal abatement costs (MACs). The result is that firms with lower MACS reduce their emissions by more than firms with higher MACs, which is a further efficiency gain. The 1990 Amendments first introduced emissions trading for sulfur followed by nitrous oxide (NOx). NOx emissions are an ingredient in ground-level ozone often referred to as smog.
Boiler controls
Published in Raymond F. Gardner, Introduction to Plant Automation and Controls, 2020
NOx emissions can be reduced with post combustion treatment using a selective catalytic reactor (SCR). The SCR can be of the dry type, using ammonia/urea in the presence of a ceramic catalytic filter to produce water and inert nitrogen, or in a non-SCR wet scrubbing process.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
This strategy involves modifying the combustion process so that fewer pollutants are generated in the first place. This is generally much less costly than removing the pollutants from the exhaust gases after they have been formed. Many combustion modification techniques have been used to reduce emissions from conventional burners, depending on the pollutant. Using NOx as an example pollutant, air staging fuel staging, flue gas recirculation, water or steam injection, reducing air preheat temperatures, ultralean premix, and pulsed combustion are some of the many ways that have been used to reduce emissions. In some cases, the performance of the overall system may be reduced by these techniques. For example, injecting water into the burner or combustor does reduce NOx but it also usually reduces thermal efficiency as well.
High-temperature determination of ammonia by tunable diode laser absorption spectroscopy (TDLAS)
Published in Instrumentation Science & Technology, 2023
H. Cui, J. Li, F. Wang, G. Lv, W. Wang, J. Fan
Environmental issues associated with pollutants generated by coal-fired power plants have garnered considerable attention.[1] Nitrogen oxides (NOx) generated during coal combustion are key pollutants and are significant contributors to acid rain and photochemical smog.[2] The United States Environmental Protection Agency (EPA) regulates NOx emissions under the authority of the Clean Air Act (CAA). These regulations were formulated to promote the development of post-combustion NOx reduction technologies, such as selective catalytic reduction (SCR)[3,4] that uses ammonia (NH3) as the reducing agent. To obtain the best denitration, the quantity of injected NH3 must be proportional to the quantity of NOx.[5] However, excessive NH3 may result in degradation in operation in coal-fired power plants.[6,7] Therefore, real-time and accurate determination of NH3 is crucial for operational optimization.
Nitric oxide and nitrite removal by partial denitrifying hollow-fiber membrane biofilm reactor coupled with nitrous oxide generation as energy recovery
Published in Environmental Technology, 2022
Khin Hnin Yu, Faruk Can, Pınar Ergenekon
Nitric oxide (NO) and nitrogen dioxide (NO2) emissions have become a serious environmental concern because of their impact on public health and the ecosystem. NO and NO2 (designated together as NOx) cause several environmental problems such as photochemical smog, tropospheric ozone formation, rise in particulate matter (PM) concentration, acidification, and eutrophication [1, 2]. In particular, NOx emissions in developing countries are expected to rise due to their increase in industrial activities and in fossil fuel use. As a result of the negative impact of increased NOx emissions on human health and ecosystem, the authorities have to regulate their environmental policy to tighten NOx emission standards, therefore, the development of cost-effective NOx control technologies is required. [3, 4].
A potential material for removal of nitrogen compounds in petroleum and petrochemical derivates
Published in Chemical Engineering Communications, 2021
Matheus Antoniel Félix de Carvalho, Deborah Victória Alves Aguiar, Boniek Gontijo Vaz, Maria Eugênia de Oliveira Ferreira, Laiane Alves de Andrade, Indianara Conceição Ostroski
In addition to the problems caused in oil refining due to the presence of nitrogeneous compounds, nitrogen is also a concern of the international community due to the emission of environmental pollutants during the combustion of refinery final products. The nitrogen compounds present in fuels are converted into nitrogen oxides (NOx) during the incomplete combustion of fossil fuels. These nitrogen oxides can promote the photochemical destruction of the ozone layer and the formation of acid rain, contributing to the degradation of the environment and city structures. Furthermore, it presents harmful effects on human health (Huang et al. 2017; Wei et al. 2009). In this sense, the legislation tend to be more restricted and limit the emission of NOx gases, for example, European emission standards define that the limit for NOx emission in petrol vehicles must be less than 0.06 g/km (EC 692/2008 2008).