Reconstruction of Dynamics of SO2 Concentration in Troposphere Based on Results of Direct Measurements

A method for the reconstruction of the dynamics of processes with discrete time, developed in our previous papers, has been applied for study the dynamics of concentration of sulfur dioxide in lower troposphere. For the analysis, recordings of sulfur dioxide concentration from four measurement stations located in Poland (two of them has been located in huge cities and two in rarely inhabited regions) were used. We managed to obtain the deterministic and stochastic component of this dynamics. In result, we estimate the lifetime of sulfur dioxide in troposphere and the increase of sulfur dioxide concentration influenced by anthropogenic sources.

A Critical Review on Corrosion and Runoff from Zinc and Zinc-Based Alloys in Atmospheric Environments

This critical review aims at addressing important issues concerning zinc corrosion and zinc runoff processes of zinc or zinc alloyed with aluminum or magnesium exposed to atmospheric environments. The evolution of the corrosion product (patina) layer is very important for both processes. While corrosion largely is controlled by electrochemical reactions at the metal/patina interface, runoff is predominantly governed by chemical reactions at the patina/atmosphere interface. The gradual evolution of compounds in zinc patina follows one of two main routes: one in more sulfur-dominated and one in more chloride-dominated environments. Because of climatic changes and reduction of sulfur-containing atmospheric species in many parts of the world, the chloride-route is expected to dominate over the sulfur-route. Alloying with aluminum and magnesium results in substantial improvement in corrosion protection, whereby several mechanisms have been proposed. The released amount of zinc is highly dependent on the amount of rainfall, also on sulfur dioxide concentration or deposition, and to only a low extent on chloride deposition. Based on all runoff data, a model is presented which predicts 70% of all observed zinc runoff rates within 40% from their measured value.

CFD MODELING OF SO2 CAPTURE USING LIMESTONE IN INDUSTRIAL SCALE CIRCULATING FLUIDIZED BED BOILER

The unsteady state computational fluid dynamics model for gas-solid particle flow in industrial scale circulating fluidized bed boiler combining with combustion and desulfurization (using limestone solid sorbent) chemical reactions, both homogeneous and heterogeneous, was developed in this study. The effects of solid sorbent feeding position and solid sorbent particle size on sulfur dioxide concentration were investigated. The results showed that both the solid sorbent feeding position and solid sorbent particle size had an effect on the sulfur dioxide capture. Entering solid sorbent at the upper secondary air position gave lower sulfur dioxide concentration than the one at the lower secondary air position and fuel feed position, respectively. This can be explained by the influence of suitable temperature at the upper secondary air position for desulfurization chemical reaction. About the solid sorbent particle size, the sulfur dioxide capture was the lowest when using the largest solid sorbent particle size due to the system hydrodynamics.