Thermal destruction conclusions

Surrounding atmosphere influences the formation of either decay product in the process of destruction. So in the work [193] it has been found that in nitrogen atmosphere at isothermal heating at 160 °C mainly benzoic acid and esters are formed. Since oxidative processes are absent at thermal destruction in nitrogen atmosphere then one may come to a conclusion that benzoic acid and esters are the products of thermal decay of PETP fibre. At thermal destruction of PETP-fibre thermal decay plays a very important role, especially at the beginning of the destruction process. 

Thus, information on modifying additives of polyfunctional action being used at present is represented mainly by patent works. Inorganic and organic compounds such as black, ultraviolet absorbers on the basis of benzophenone derivatives, inhibitors of radical processes-piperidines and stable nitroxyl radicals and so on - mainly colourless compounds, are recommended as modifying additives. However, problems of the effect of modifiers on photo- and thermal destruction of PETP are not completely interpreted in literature. Besides, different researchers come to different conclusions. 

It is my contention that the optical and physical properties and the optical structure produced during the destructive distillation or thermal decomposition of vitrinite is closely related to mode of carbonization and, in the case of pitch, is intimately related to the method of pitch preparation. For instance, a pitch may be produced from a high or low temperature tar, from a primary cooler tar, or from a flushing liquor tar. In addition, it may be air blown, thermally or chemically treated, straight distilled, or cut back, just to mention a few. Under similar carbonization conditions almost any one of these pitches will produce a coke which has certain characteristics that are related to the parent pitch. Even pitches similarly processed from the tar can differ in the content of quinoline- and benzene-insoluble material and P-resin, and can contain more than one distinct liquid phase. None of these points of difference has been discussed by Dr. Taylor or even recognized in the preparation. To interpret the structure of pitch coke divorced from a knowledge of the pitch source and/or carbonization conditions can lead to erroneous conclusions. These are pertinent data omitted by the authors. 

In contrast to polymerisates, polycondensates can not be depolymerized under inert conditions. Decomposition usually leads to the destruction of the chemical structure and the monomers. The thermal decomposition of PET starts at about 300°C in an inert atmosphere [25]. Between 320 and 380°C the main products are acetaldehyde, terephthalic acid, and carbon oxides under liquefaction conditions. The amounts of benzene, benzoic acid, acetophenone, C1-C4 hydrocarbons, and carbon oxides increase with the temperature. This led to the conclusion that a P-CH hydrogen transfer takes place as shown in Eigure 25.8 [26]. Today the P-CH-hydrogen transfer is replaced as a main reaction in PET degradation by several analytic methods to be described in the following sections. The most important are thermogravimetry (TG) and differential scanning calorimetry (DSC) coupled with mass spectroscopy and infrared spectroscopy. 

The Portable Unit has successfully demonstrated its capability for thermal treatment of hazardous wastes at the source of the material. This type of on-site treatment would eliminate the need of transportation of hazardous materials to a distant site of stationary treatment equipment. The Portable Unit also has demonstrated that it can be moved to a site and be ready to treat material very quickly, a capability which will be very important in operation of full scale equipment. The on-site treatment of the Times Beach dioxin contaminated soil resulted in no dioxin detected in any of the incinerator effluent streams. The product of the testing activity was soil with no detectable level of dioxin. Dioxin contaminated soil thermally treated in this manner will yield soil which can be disposed as non-hazardous material. The decontamination was performed without exceeding RCRA requirements for particulate emissions and with dioxin destruction efficiencies surpassing the required percentage. The overall conclusion was that the infrared incinerator can very effectively remove dioxin from contaminated... 

Section 2 presents the assumptions and requirements upon which the INEL concept was developed. Section 3 contains an overview of the reactor concept. Section 4 lists the conclusions and recommendations. Most of the technical details and discussions are contained in the appendices. The first task was to examine plutonium destruction rates and isotopics for different neutron spectra, as discussed in Appendix A. This study lead to the adoption of a thermal reactor concept instead of reactors with fast or epithermal neutron spectra. The second task was to study the addition of seed materials for selfprotection from materials diversion. Appendix B illustrates that fission products provide the best. self-protection, and seed materials are not needed for the INEL concept. Various fuel types were investigated and are described in Appendix C. The core neutronics studies presented in Appendix D and thermal-hydraulics studies pre.sented in Appendix E were performed concurrently. An evaluation of potential offsite radiation doses... 

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