Investigations On the Self Heating Potential of Garage Waste As Basis for the Hazard Evaluation of Bulk Storage Facilities

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

The self heating of bulk material is a major point to be considered in hazard analysis especially for waste management and waste treatment companies. The self heating potential for bulk material mainly depends on the composition of the material itself and on systemic influences like the geometry of the storage area, weather conditions or the storage temperature. The chemical oxidation at low temperatures is besides microbiological activity the main reason for the self heating and auto ignition of bulk material. Data from the measurement of the chemical and biological oxidation kinetics can be used as basis for the simulation of storage areas by computational fluid dynamics. The measurement of the low temperature oxidation kinetics is carried 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 oxidation reactions at low temperatures show very low turnover rates themselves, the experimental setup is laid out as a cycle process. The oxidation kinetics is measured by the analysis of the carbon monoxide (CO) and carbon dioxide (CO₂) production rate at different temperatures. Usually a temperature range from 40°C up to 120°C is investigated. Waste materials from workshops contain significant amounts of grease and oil as well as residuals of metal dusts or chips dispersed on the surface of paper or cloth material used for cleaning purposes. The large surface combined with the fine dispersion of grease and oil accelerates the chemical oxidation significantly. 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 a differential cycle reactor. For the investigations biological cutting oil and oil with a petrochemical origin was investigated. Furthermore the influence of metal dusts on the oxidation characteristics of the different materials was investigated. The results of the investigations were compared with the oxidation kinetics of garage waste material with a mean diameter of 0- 40mm.