RWTÜV (Germany)

Fly ash and stack gases from municipal waste and industrial incinerators in the F.R.G. have been analyzed for dioxins (PCDD and PCDF). Most of the currently used procedures of stack gas sampling for PCDD/PCDF have been compared and were found to be equally effective. Differences are found, however, in the recovery of surrogates added to the sampling train before sampling, which makes it difficult to validate the sampling procedure. The analysis for PCDD/PCDF in stack gas or fly ash samples from municipal waste incinerators can no longer be considered an analytical problem. Thirty samples of stack gas from a single (old) municipal waste incinerator showed wide variation in PCDD/PCDF emission, indicating that single measurements are not useful in characterizing a plant for average PCDD/PCDF emission. It will be extremely difficult to correlate plant operating conditions to PCDD/PCDF stack gas emissions or PCDD/PCDF fly ash concentrations, because the effects produced by changing conditions are obscured by the variations which occur in PCDD/PCDF concentrations during steady conditions. The variations found under steady conditions can be explained by the proposed mechanisms of PCDD/PCDF formation and decomposition at low temperatures catalyzed by fly ash. Incineration of hospital waste and pyrolytic reclamation of copper in cables and aluminium produced significant emission of PCDD/PCDF. A major non-combustion source of higher chlorinated PCDD/PCDF (tetra- to octa-isomers) is pentachlorophenol, a widespread preservative which contributes to the PCDD/ PCDF concentrations found, for example, in sewage sludge, river sediments and house dust.

The non-relativistic motion of a particle in a central field with 1/r potential, e.g. the motion of an electron in the Coulomb field of a charged nucleus at rest, is described by the equation of motion (non-relativistic Kepler problem) m x″ = α · x /r3 with α = ez e (product of the charges of the central body ez and the electron e). From this equation of motion, three statements of conservation can be derived: in respect of the energy E, of the angular momentum L and of the Lenz vector Λ = m {x′× L + α ·x/r}. The geometric meaning of Λ is that of a vector pointing in the direction of the perihelion of the particle orbits (conic sections). It will be demonstrated that also at the relativistic Kepler problem, which is based on the equation of motion an analogous Lenz vector exists. It represents a quantity of conservation - in the same way as the relativistic energy and the relativistic angular momentum. For the transitional case → ∞, where the relativistic problem turns into the non-relativistic problem, the relativistic Lenz vector also turns into the non-relativistic Lenz vector. The generalised (relativistic) Lenz vector has also a geometric meaning. Its direction coincides with the oriented axis of symmetry of the orbits (rosettes, spirals, hyperbola-type curves etc.). The quantity of conservation Λ occupies a special position in respect of the quantities of conservation energy and angular momentum. Whereas the energy and the angular momentum correspond with a symmetry of time and space, the Lenz quantity of conservation corresponds with a symmetry of the orbits. The fact that the Lenz vector can relativistically be generalised touches thereby on principal aspects.

Abstract Bei der H2‐Oxidation an einem einzelnen Katalysatorkorn (Pt auf γ‐Al2O3) werden Zünd/Lösch‐Erscheinungen als einfache Beispiele thermisch verursachter Instabilitäten studiert. Unter geeigneten Reaktionsbedingungen tritt oszillatorisches Verhalten auf mit Amplituden der Kornüberhitzung bis zu 60 grd und Schwingungsdauern in der Größenordnung von Stunden. Bei der katalytischen CO‐Oxidation, deren Geschwindigkeit eine fallende Charakteristik aufweist, werden isotherme (kinetisch verursachte) Instabilitäten beobachtet. Dem Zünd/Lösch‐Phänomen entsprechen hier Sprünge zwischen aktiven und inaktiven Zuständen der Katalysatoroberfläche. Auch treten isotherme Oszillationen vom Charakter von Kippschwingungen und mit Periodendauern von Minuten auf.