Emissionen der Tierhaltung unterliegen verschiedenen Einflussparametern sowie jahreszeitlichen Schwankungen. Neben der Tierart spielen die Lebendmasse der Tiere, das Außenklima und die Verfahrensgestaltung - insbesondere der Lüftung - eine entscheidende Rolle. Besonders schwierig erweist sich die Bestimmung des Luftvolumenstromes bei frei gelüfteten Ställen. Im durchgeführten Projekt wurden dazu verschiedene Methoden verglichen. Gleichzeitig fand eine Erfassung emissionsrelevanter Konzentrationen von Gasen, Geruch und Staub in zwei Ställen mit unterschiedlichen Aufstallungsverfahren statt. Dabei wurde nachgewiesen, dass Unterschiede zwischen den beiden Systemen vorhanden sind.

This thesis is concerned with the implementation of Artificial Neural Networks (ANNs) to monitor and control chain grate stoker-fired coal boilers with a view to improving the combustion efficiency whilst minimising pollutant emissions. A novel Neural Network Based Controller (NNBC) was developed following a comprehensive set of experiments carried out on a stoker test facility at the Coal Research Establishment (CRE) Ltd., before being evaluated on an industrial chain grate stoker at Her Majesty's Prison Garth, Leyland. The NNBC mimicked the actions of an expert boiler operator, by providing 'near optimum' settings of coal feed and air flow, as well as taking into account the correct 'staging' sequence of these parameters during load following conditions, before subsequently fine tuning the combustion air under quasi steady- state conditions. Test results from the on-line implementation of the NNBC on both chain grate stoker plants have demonstrated that improved transient and steady state combustion conditions were attained without having any adverse effect on the pollutant emissions nor the integrity of the appliances. A novel combustion monitoring system was also developed during the course of the work that can be used to infer the stability of combustion on the fire bed, following a pilot study of the 'flame front' movement during boiler load changes on the stoker test facility at CRE. This novel low-cost flame front monitor was rigorously tested on the industrial stoker plant, and long hours of successful on-line operation were achieved. It was also demonstrated with the use of ANNs, that the data gathered from the novel flame front monitor can be processed to yield evidence concerning movement of the ignition plane over a short period of time (several minutes). The prototype controller and flame front monitor would thus provide both stoker manufacturers and users with a means of meeting future legislative limits on pollutant emissions as indicated by the European Commission, as well as improving the combustion efficiency of this type of coal firing equipment Finally, ANNs were also used as a simplistic means to represent the complex coal combustion process on the bed of the stoker test facility whilst burning a particular type of coal. The resultant 'black-box' models of the combustion derivatives were able to represent the dynamics of the process and delivered accurate one-step ahead predictions over a wide range of unseen data. The work demonstrated the complex functional mapping capability of ANNs and also addressed the deficiencies in mathematical modelling of the coal combustion process on fixed grate, as indicated in the literature.

Emissionen der Tierhaltung unterliegen verschiedenen Einflussparametern sowie jahreszeitlichen Schwankungen. Neben der Tierart spielen die Lebendmasse der Tiere, das Außenklima und die Verfahrensgestaltung - insbesondere der Lüftung - eine entscheidende Rolle. Besonders schwierig erweist sich die Bestimmung des Luftvolumenstromes bei frei gelüfteten Ställen. Im durchgeführten Projekt wurden dazu verschiedene Methoden verglichen. Gleichzeitig fand eine Erfassung emissionsrelevanter Konzentrationen von Gasen, Geruch und Staub in zwei Ställen mit unterschiedlichen Aufstallungsverfahren statt. Dabei wurde nachgewiesen, dass Unterschiede zwischen den beiden Systemen vorhanden sind.

The object of study in present diploma thesis is the plasmachemical reduction of corrosion layers on copper. This process is based on reductive properties of low pressure hydrogen plasma. In this case three series of copper samples were prepared and corroded in different corrosion environments in order to create three kinds of artificial corrosion layers. In the first step the copper coupons were properly grinded in order to achieve a defined surface roughness. In the next step the coupons corroded for 12 days in vapours of three concentrated acids – HCl, HNO3, and H2SO4. SEM/EDX analysis was carried out in order to characterise the grown corrosion layers on copper coupons, which showed us the presence of nitrogen, oxygen, chlorine and sulphur in different chemical forms in corrosion layers. The most significant part of this work was the plasmachemical treatment of corroded copper samples. Pure hydrogen was used as a reaction gas under the pressure of about 200 Pa and 50scc/m flow rate. The discharge was generated in quartz-glass reactor by using RF generator under the different power and mode settings. Optical emission spectroscopy was used to detect the intensity of plasma radiation. The value of integral intensity of OH radicals represented quantitative ablation of oxygen from a corrosion layer. OH radicals were the main products of reaction between hydrogen radicals (from plasma) and oxygen in corrosion layer. Time of increasing of OH radicals intensity was different for coupons from different corrosion environment and was also related to used power of generator and mode. The process was finished when the OH radicals intensity decreased to 10% of reached maximum. Sample temperature was an important indicator of sample protection against metallographic changes. The analyses XRD and SEM/EDX on corroded and treatment samples were performed. The analyses show that the decrease of main corrosion agents as chlorine and oxygen was achieved by hydrogen plasma treatment. The corrosions as well as their removal are a very complex problem and the plasmachemical treatment of metal objects is an efficient method for the removal of corrosion layers as compared to conventional conservations methods mainly due to a significant reduction of treatment time.

The thesis deal with applying low-pressure low-temperature plasma to corrosion products layers on bronze. Layers of corrosion products on samples were artificially prepared. As a result, they had the same composition and could be irreversibly destroyed during experiments, which would not be possible with real archeological artifacts. Bronze, copper and tin alloy, samples were cut with respect to the size of the plasma-chemical device. XRF was used to determine the bronze composition. Before being corroded by the active medium, each sample was washed with ethanol and dried with a hot air stream. Until now, the procedure was the same for all samples. During formation of corrosion products layers, two factors have to be taken into account: the time consumption and the corrosiveness of the active environment. By focusing on one or the other factor, several groups of samples with differently degraded surfaces were created. The fastest way was to place samples in a corrosion chamber where sodium chloride solution was applied at the elevated temperature. The samples were corroded within a few days there. Longer, but in terms of corrosion products layers compactness better way proved procedure where the samples were sealed in the desiccator. At the desiccator bottom the Petri dish with an inorganic acid was placed, in our case, with hydrochloric acid inside. This method corroded the samples within one month. The longest but the most closed to the real live method was the burial of samples into soil or compost. However, this method corroded the samples within two years. Final step after the samples were removed from any corrosive environment, were dried under low pressure and were placed in a barrier film made bag together with moisture and oxygen absorbers. So prepared samples with layers of corrosion products have been treated in a low-pressure low-temperature plasma. Treatment was carried out in the apparatus which is based on the reactor: cylinder of quartz glass having a diameter of 100 mm and a length of 900 mm. The reactor was supplied with a working gas or a mixture of working gases with a total flow rate of 50 sccm. In our case, one is pure hydrogen or a combination with argon. A rotary oil pump was used to provide vacuum. The reactor base pressure was 10 Pa before treatment, while during the treatment it was 150 Pa. High-frequency generator (13.54 MHz) was used for supply the system with energy through two copper electrodes located outside the reactor. According to the energy delivery method, the treatment was carried out in a continuous or pulse mode. The sample temperature was monitored during the experiment and were evaluated the emission spectra from OES. The sample temperature was one of the key factors. The measurement was first done with a thermocouple, later switched to a thermocouple with optical data transmission. A safe temperature was set and then the whole process was controlled through it. In addition, the effect of the energy delivery method, value of the delivered power, sample size, presence of incrusted layers and composition of working gas were studied. After application of plasma, samples were analyzed by SEM – EDX and XRD. After the evaluation of the acquired knowledge and experience, a real artifact - a bronze chisel from the site of Boskovice - was treated. This documentation lacked the artifact, so it could be used to verify the lessons learned about plasma chemical reduction.

M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology): Vaal University of Technology / Strict environmental regulation on flue gas emission has led to the implementation of FGD technologies in power stations. Wet FGD technology is commonly used because it has high SO2 removal efficiency, high sorbent utilization and due to availability of the sorbent (limestone) used. SO2 is removed by passing flue gas through the absorber where it reacts with the slurry containing calcium ions which is obtained by dissolution. This study presents the findings of the dissolution of a calcium-based material (limestone) for wet FGD process. This was done using a pH stat apparatus and adipic acid as acid titrant. Adipic acid was used because of its buffering effect in wet FGD process. The conditions used for this study are similar to what is encountered in a wet FGD process. The extent of dissolution was determined by analyzing the amount of calcium ions in solution at different dissolution periods. The dissolution kinetics were correlated to the shrinking core model and it was found out that chemical reaction at the surface of the particle is the rate controlling step. This study also investigated the dissolution of coal fly ash and bottom ash. Their dissolution kinetics showed that the diffusion through the product layer was the rate controlling step due to an ash layer formed around the particle. The formation of ash layer was attributed to pozzolanic reaction products which is calcium-alumino-silicate (anorthite) compounds were formed after dissolution. The effect of fly ash on the dissolution of rate of limestone was also studied using response surface methodology. Limestone reactivity was found to increase with increase in the amount of fly ash added and the pH was found to be strong function of the rate constant compared to other dissolution variables. The presence of silica and alumina in fly ash led to a significant increase in the specific surface area due to hydration products formed after dissolution. / Eskom