Investigations on the self heating potential of garage waste as basisfor the hazard evaluation of bulk storage facilities

摘要

The self heating of bulk material is a major point to be considered in hazard analysis especiallyfor waste management and waste treatment companies. The self heating potential for bulkmaterial mainly depends on the composition of the material itself and on systemic influences likethe geometry of the storage area, weather conditions or the storage temperature. Besidesmicrobiological activity, chemical oxidation at low temperatures is the main reason for the selfheating and auto ignition of bulk material. Data from the measurement of the chemical andbiological oxidation kinetics can be used as basis for the simulation of storage areas bycomputational fluid dynamics. The measurement of the low temperature oxidation kinetics iscarried out in a differential reactor, which is characterized by a small amount of sample material,isothermal conditions and very low turnover rates. Due to the fact that chemical oxidationsreactions at low temperatures show very low turnover rates themselves, the experimental setup islaid out as a cycle process. The oxidation kinetics are measured by the analysis of the carbonmoNO_xide (CO) and carbon dioxide (CO_2) production rate at different temperatures. Usually atemperature range from 40°C up to 120°C is investigated. Waste materials from workshopscontain significant amounts of grease and oil as well as residuals of metal dusts or chipsdispersed on the surface of paper or cloth material used for cleaning purposes. The large surfacecombined with the fine dispersion of grease and oil accelerates the chemical oxidationsignificantly. To determine the influence of the oil and grease content on the oxidation kinetics,measurements of paper and cloth samples with different contents of oil were carried out in adifferential cycle reactor. For the investigations biological cutting oil and oil with apetrochemical origin was investigated. Furthermore the influence of metal dusts on the oxidationcharacteristics of the different materials was investigated. The results of the investigations werecompared with the oxidation kinetics of garage waste material with a mean diameter of 0- 40mm.