Radical shower

The gas mixture containing the nitrogen oxides is very important as well. Experiments and modeling carried out for N2/NOx mixtures, or with addition of 02, H20, C02 and hydrocarbons will be discussed. Typical hydrocarbon additives investigated are ethane, propene, propane, 2-propene-l-ol, 2-propanol, etc. As compared to the case without hydrocarbons, NO oxidation occurs much faster when hydrocarbons are present. The reaction paths for NO removal change significantly, in fact the chemical mechanism itself is completely different from that of without hydrocarbon additives. Another additive investigated extensively is ammonia, used especially in corona radical shower systems. 

In corona radical shower systems, the high voltage electrode is a pipe with several nozzles and the ground electrodes are planar. A typical configuration for such a system is shown in Figure 12.4a. The discharge was usually operated in d.c. mode. 

Figure 12.4. (A). Schematic drawing of the corona radical shower system 1 - high voltage electrode (pipe with nozzles), 2 - nozzles, 3 - planar ground electrodes (B) Photograph of the discharge in a corona radical shower system with 10 nozzles [56] (C) CCD images of streamers in a corona radical shower system [57] (CCD exposure time 400 ns).

Two-dimensional distributions of ground-state NO were detected by planar laser-induced fluorescence during the process of NO removal in a corona radical shower system in NO/dry air mixtures [57,58], The authors observed that the density of NO molecules decreased not only in the plasma region formed by the corona streamers and the downstream region of the reactor, but also in the upstream region of the reactor. They explained this behaviour by oxidation with ozone, which is transported upstream by electrohydrodynamic flow. 

Chang et al. conducted pilot scale tests in a corona radical shower system with ammonia injection for simultaneous removal of NO and S02 from coal boiler flue gases [61]. The corona radical shower system used had dimensions of 2.1 x 1.8 x 2m3 and consisted of 20 parallel flow channels with five multiple nozzle corona electrodes per... 

Kanazawa, S., Sumi, T., Sato, N. et al. (2005) Wide-range two-dimensional imaging of NO density profiles by LIF technique in a corona radical shower reactor, IEEE Trans. Ind. Appl. 41, 200-5. 

Chang, J.-S., Urashima, K., Tong, Y.X. et al. (2003) Simultaneous removal of NOx and S02 from coal boiler flue gases by DC corona discharge ammonia radical shower systems Pilot plant tests, J. Electrostatics 57, 313-23. 

Kanazawa, S., Chang, J.S., Round, G. et al. (1997) Removal of NOx from flue gas by corona discharge activated methane radical showers, J. Electrostatics 40 41, 651-6. 

Les Actifs Marins Exfoliant Shower Gel (Belgium) Sarbec Microparticles, seaweed extracts, and antifree radicals Gently eliminates impurities and dead cells which may asphyxiate and dull die skin. Gently cleanses die skin, returning to it luster, softness, and firmness... 

Since electron energies of only lOOeV or less are required to break chemical bonds and to ionize or excite components of the coating system, the shower of scattered electrons produced in the coating leads to a uniform population of free radicals (excited... 

In fairness to Doc I must note that I have not yet given the final sentence of the alumnus story. But for that shower, he concluded, I most likely would have remembered neither the incident nor the valuable lesson it contained. However, this sentence was the calm and reasoned verdict of a mature engineer, looking back on the occasion many years later. At the time of the event, one can be sure, his feeling was radically different. 

For example, vinyl chloride is polymerized to form polyvinyl chloride (PVC), which is a very hard polymer used to make plumbing pipes. PVC can be softened if polymerization takes place in the presence of compounds called plasticizers, as we will explore in more detail in Chapter 27. PVC made with plasticizers is a bit more flexible (although durable and strong) and is used for a wide variety of purposes, such as garden hoses, plastic raincoats, and shower curtains. Table 11.3 shows a number of common polymers produced via a radical process. 

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