Numerical simulation of nitrogen oxide formation in dust furnaces

Even though natural sources of air pollution account for over 50 % of sulphur compounds, 93 % of nitrogen oxide which are the most dangerous artificial anthropogenic sources of air pollution and primarily associated with the combustion of fossil fuel. Coal-fired thermal power plants and industrial fuel-burning plants that emit large quantities of nitrogen oxides (NО and NО2), solids (ash, dust, soot), as well as carbon oxides, aldehydes, organic acids into the atmosphere pollute the environment in majority. In the present work, a mathematical model and a scheme for calculating the formation of nitrogen oxide has been developed. Also, the dependence of the rate of release of fuel nitrogen from coal particles at the initial stage of gasification and content of volatiles has been obtained. The main regularities of the formation of NOx at the initial section of the flame in the ignition zone of the swirl burner flame during the combustion of Ekibastuz coal have been revealed. Modern environmental requirements for the modernization of existing and the creation of new heat and power facilities determine the exceptional relevance of the development of effective methods and constructions to reduce emissions of nitrogen oxides, sulfur oxides and ash to 200, 300, and 100 mg/nm3 at a=1.4. The dust consumption in all experiments was kept constant and amounted to 0.042 g/s, as well as with the results of calculating the thermal decomposition of the Ekibastuz coal dust, the recombination of atomic nitrogen into nitrogen molecules, and the kinetics of the formation of fuel nitric oxide. It was found that despite the presence of oxygen in Ekibastuz coal for gases Odaf=11.8 % in an inert atmosphere, nitrogen oxides are not formed

Kinetics, SOA yields and chemical composition of secondary organic aerosol from β-caryophyllene ozonolysis with and without nitrogen oxides between 213 and 313 K

β-caryophyllene (BCP) is one of the most important sesquiterpenes (SQTs) in the atmosphere, with a large potential contribution to secondary organic aerosol (SOA) formation mainly from reactions with ozone (O3) and nitrate radicals (NO3). In this work, we study the temperature dependence of the kinetics of BCP ozonolysis, SOA yields, and SOA chemical composition in the dark and in the absence and presence of nitrogen oxides including nitrate radicals (NO3). We cover a temperature range of 213 K – 313 K, representative of tropospheric conditions. The oxidized components in both gas and particle phases were characterized on a molecular level by a Chemical Ionization Mass Spectrometer equipped with a Filter Inlet for Gases and AEROsols using iodide as the reagent ion (FIGAERO-iodide-CIMS). The batch mode experiments were conducted in the 84.5 m3 aluminium simulation chamber AIDA at the Karlsruhe Institute of Technology (KIT). In the absence of nitrogen oxides, the temperature-dependent rate coefficient of the endocyclic double bond in BCP reacting with ozone between 243 – 313 K are negatively correlated with temperature, corresponding to the following Arrhenius equation: k = (1.6 ± 0.4) × 10−15 × exp((559 ± 97)/T). The SOA yields increase from 16 ± 5 % to 37 ± 11% with temperatures decreasing from 313 K to 243 K at a total organic particle mass of 10 µg m−3. The variation of the ozonolysis temperature leads to substantial impact on the abundance of individual organic molecules. In the absence of nitrogen oxides, monomers C14-15H22-24O3-7 (37.4 %), dimers C28-30H44-48O5-9 (53.7 %) and trimers C41-44H62-66O9-11 (8.6 %) are abundant in the particle phase at 213 K. At 313 K, we observed more oxidized monomers (mainly C14-15H22-24O6-9, 67.5 %) and dimers (mainly C27-29H42-44O9-11, 27.6 %), including highly oxidized molecules (HOMs, C14H22O7,9, C15H22O7,9 C15H24O7,9) which can be formed via hydrogen shift mechanisms, but no significant trimers. In presence of nitrogen oxides, the organonitrate fraction increased from 3 % at 213 K to 12 % and 49 % at 243 K and 313 K, respectively. Most of the organonitrates were monomers with C15 skeletons and only one nitrate group. Higher oxygenated organonitrates were observed at higher temperatures, with their signal-weighted O : C atomic ratio increasing from 0.41 to 0.51 from 213 K to 313 K. New dimeric and trimeric organic species without nitrogen atoms (C20, C35) were formed in presence of nitrogen oxides at 298–313 K indicating potential new reaction pathways. Overall, our results show that increasing temperatures lead to a relatively small decrease of the rate coefficient of the endocyclic double bond in BCP reacting with ozone, but to a strong decrease in SOA yields. In contrast, the formation of HOMs and organonitrates increases significantly with temperature.

Time-resolved in situ DRIFTS study on NH3–SCR of NO on CeO2/TiO2 catalyst

Ce–Ti catalysts were considered as promising replacement for V–Ti based catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NO and NO2) with NH3. In this work, CeO2/TiO2 catalyst was...

The Effects of Biodiesel on NOx Emissions for Automotive Transport

Automobiles with internal combustion engine using diesel fuel have large harmful emissions of nitrogen oxides and soot, which affect the health of the population and especially children and carbon dioxide, which is dangerous for the planet as a whole. Biodiesel is used in Europe as an additive to diesel fuel to reduce soot emissions (including carcinogens), as well as to improve the balance of carbon dioxide on the planet. Using the biodiesel in internal combustion engines tends to show higher nitrogen oxides emissions compared to diesel. In this paper, the impact of flame temperature, ignition delay and density on NOx formation of biodiesel and its component for both stationary engine and automotive engine were analysed. Emissions of nitrogen oxides increase with increasing load. In no-load modes, biodiesel shows lower emissions of nitrogen oxides than diesel.