COOL FLAME EVAPORATION FOR DIESEL REFORMING TECHNOLOGY

摘要

The separation of evaporation from the high-temperature reaction zone is crucial for the reforming process. Unfavorable mixtures of liquid fuels, water, and air lead to degradation by local hot spots in the sensitive catalysts and formation of unwanted byproducts in the reformer. Furthermore, the evaporator has to work with dynamic changes in the heat transfer, residence times, and educts compositions. By using exothermal prereactions in the form of cool flames, it is possible to realize a complete and residue-free evaporation of liquid hydrocarbon mixtures. The conditions under whether cool flames can be stabilized or not are related to the heat release of the prereactions in comparison to the heat losses of the system.rnExaminations were conducted in a flow reactor at atmospheric pressure and changing residence times to investigate the conditions under which stable cool flame operation is possible and autoignition or quenching occurs. An energy balance of the evaporator should deliver the values of heat release by cool flames in comparison to the heat losses of the system.rnThe cool flame evaporation is applied in the design of several diesel reforming processes (thermal and catalytic partial oxidation, autothermal reforming) with different demands in the heat management and operation range (air ratio λ, steam to carbon ratio). The results are discussed at the end of the article.