Secondary emission temperature

Step 1 Determine primary emission heat content. This step should be taken early in the design stage to determine if the enclosure will capture both primary and secondary emissions. The heat content of furnace emissions and the temperature limitation on the fume collector are considered for this task. The off-gas heat content is calculated for furnace reactions during melting and refining periods. The maximum heat content should be used for design. Assuming a fabric... 

SCR systems at stationary diesel engines profit from the high exhaust gas temperatures of about 350-400 C, caused by the usually constant high load operation conditions of the diesel engine. In this temperature window nearly all known SCR catalysts are very active. Moreover, weight and size of the exhaust gas catalyst are usually not strictly limited, which results in a good NO, reduction efficiency (DeNOJ. However, DeNO, is not the only criterion for an SCR catalyst. Further requirements are excellent selectivities regarding NO and urea/ammonia as well as low ammonia slip, which is an undesired secondary emission of the SCR process. Therefore, all SCR catalysts exhibit surface acidity, which is necessary to store ammonia on the catalyst surface and, thus, to prevent ammonia slip. 

In testing the possibility of proton transfer as a quenching mechanism of tyrosine in oligopeptide/polynucleotide complexes, Brun et a/.(102) compared the fluorescence emission spectra of the tyrosine and O-methyltyrosine tripeptides. They noted that, in the complex, the O-methyltyrosine tripeptide had a unique secondary emission near 410 nm. Whether this emission is related to that observed by Libertini and Small(94) is an important question. While one must consider the possibility that two tyrosine side chains could be converted to dityrosine, (96) which has a fluorescence at 400 nm, another intriguing possibility is ambient temperature tyrosine phosphorescence. This could happen if the tyrosine side chain is in a rigid, protective environment, very effectively shielded from collisions with quenchers, particularly oxygen. 

If the chemical reactions leading to volatile chemicals are slower than the other steps in a secondary emission process, this formation of the chemicals may limit the emission rate. Temperature and availability of the reactants will influence the rate of reactions. 

Salt purity, density, chemical composition, and other properties. In the laboratory, high-temperature salt properties are measured by spectroscopy. Laser or other light is sent through the salt, and the transmission of the light is measured as a function of frequency. In more sophisticated systems, secondary emission lines are measured. Salt impurities that can be measured to very low concentrations include uranium, the actinides, iron, chromium, and nickel. The chemical valence state can also be measured. This is likely to be the preferred method for monitoring the concentration of impurities and the redox potential of the salt and thus the performance of the salt cleanup systems. It would be the equivalent of the instrumentation used to monitor water chemistry in an LWR. 

Because of the complexity of combustion kinetics, coupling kinetics and hydrodynamics into a single comprehensive model is not generally pursued. Instead, many successful hydrodynamic studies vary operational parameters and study the effect on combustion performance parameters. Moe et al. [22] characterized combustion performance with seven parameters (1) heat transfer, (2) combustion efficiency, (3) bottom ash/total ash, (4) bed grain size, (5) limestone utilization, sulfur capture, and Ca/S (6) CO emissions, and (7) NO and NjO emissions. Eight operational variables they listed that impact one or more of the performance parameters were (1) bed temperature—affects carbon burnout, emissions, sorbent utilization, and heat absorption (2) primary/secondary air split—impacts NO emissions, temperature distribution, and pressure drop (3) excess air—changes thermal efficiency, emissions, and carbon burnout (4) solids circulation rate—controls load, heat absorption pattern, heat transfer coefficient, and pressure drop (S) fuel size—determines carbon burnout, bed vs. fly ash split, and pressure drop (6) limestone size—determines Ca/S ratio required and bed vs. fly ash split (7) Ca/S ratio—impacts sulfur capture, limestone utilization, waste/disposal volumes, particulate generation, and emissions and, (8) load—effects heat absorption, emission, carbon burnout, thermal efficiency, and temperature distribution. 

The gain factor G is not constant, but shows fluctuations due to random variations of the secondary-emission coefficient q, which is a small integer. This contributes to the total noise and multiplies the rms shot noise voltage by a factor a > 1, which depends on the mean value of [4.131]. The Johnson noise of the load resistor R at the temperature T gives an rms-noise current... 

Some materials act as secondary sources when heated above ambient temperatures. This secondary emission has the same effect on peak intensity as scattered radiation. See Chapter 2, Sections 2.3A and 2.5 for a detailed discussion of this problem. 

In addition to short-term emission estimates, normally for hourly periods, the meteorological data include hourly wind direction, wind speed, and Pasquill stability class. Although of secondary importance, the hourly data also include temperature (only important if buoyant plume rise needs to be calculated from any sources) and mixing height. 

Nitrogen Dioxide (NO2) Is a major pollutant originating from natural and man-made sources. It has been estimated that a total of about 150 million tons of NOx are emitted to the atmosphere each year, of which about 50% results from man-made sources (21). In urban areas, man-made emissions dominate, producing elevated ambient levels. Worldwide, fossil-fuel combustion accounts for about 75% of man-made NOx emissions, which Is divided equally between stationary sources, such as power plants, and mobile sources. These high temperature combustion processes emit the primary pollutant nitric oxide (NO), which Is subsequently transformed to the secondary pollutant NO2 through photochemical oxidation. 

There are two principal sources of reliable partitioning data for any trace element glassy volcanic rocks and high temperature experiments. For the reasons outlined above, both sources rely on analytical techniques with high spatial resolution. Typically these are microbeam techniques, such as electron-microprobe (EMPA), laser ablation ICP-MS, ion-microprobe secondary ion mass spectrometry (SIMS) or proton-induced X-ray emission (PIXE). 

Low-temperature activity promotion is an issue in mobile (diesel) applications, but may not be a critical issue in several stationary applications, apart from those where the temperature of the emissions to be treated is below 200°C (for example, when a retrofitting SCR process must be located downstream from secondary exchangers, or in the tail gas of expanders in a nitric acid plant). In the latter cases, a plasmacatalytic process [91] could be interesting. In the other cases, the use of NTP together with the SCR catalyst is not economically viable. However, the synergetic combination of plasma and catalysts has been shown to significantly promote the conversion of hazardous chemicals such as dioxins [92], Although this field has not yet been explored, it may be considered as a new plasmacatalytic SCR process for the combined elimination of NO, CO and dioxins in the emissions from incinerators. 

Theory Collapse of gas/vapour cavities in an acoustic field produces extremely high pressures and temperatures capable of causing the emission of light from the core of the collapsing cavity (sonoluminescence) and also the formation of oxidising radical species that can react in the solution with molecules, such as luminol, to produce a secondary, chemical luminescence. 

A process is described [224] in which an exothermic reaction takes place in a semi-batch reactor at elevated temperatures and under pressure. The solid and liquid raw materials are both toxic and flammable. Spontaneous ignition is possible when the reaction mass is exposed to air. Therefore, the system must be totally enclosed and confined in order to contain safely any emissions arising from the loss of reactor control, and to prevent secondary combustion reactions upon discharge of the materials to the atmosphere. Further, procedures and equipment are necessary for the safe collection and disposal of solid, liquid, and gaseous emission products. 

The concept of intact emission of adsorbed molecular species for identifying reaction intermediates is also well illustrated in several recent studies. Benninghoven and coworkers (2-4,12) used SIMS to study the reactions of H2 with O2, C2H4 an< 2H2 on P°ly polycrystalline Ni. For the C2H /Ni interaction, for example, direct relationships could be established between characteristic secondary ions and the presence of specific surface complexes (12). In another study, Drechsler et al. (13) used SIMS to identify NH(ads) as the active intermediate during temperature-programmed decomposition of NH3 on Fe(110). 

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