Anlagen zur Herstellung von Synthesegas (CO·H2) aus kohlenstoffhaltigen Rohstoffen werden durch hohe Temperaturen bis zu 1600 °C und Drücken bis zu 50 bar beansprucht und benötigen daher Schutz durch eine feuerfeste Ausmauerung. Zur Steigerung der Effizienz und Lebensdauer solcher Vergasungsanlagen ist die Entwicklung neuer keramischer Hochtemperaturwerkstoffe erforderlich. Solch ein Material stellt eine Al2O3-reiche Gießmasse dar, welche durch den gezielten Einsatz verschiedener ZrO2- und TiO2-Gehalte optimiert wurde. Es hat sich gezeigt, dass bereits durch die Zugabe geringer Mengen an ZrO2 bzw. TiO2 sowohl die Temperaturwechselbeständigkeit als auch die Korrosionsbeständigkeit von Al2O3 gegenüber Kohleschlacken erheblich verbessert werden kann, was auf die Ausbildung einer Spinell-Schutzschicht während des Korrosionsvorgangs zurückzuführen ist.

Biomass gasification has attracted the interest of researchers because it produces zero carbon to the atmosphere. This technology does not only produce syngas but also the byproducts which can be used for various application depending on quality.The study conducted at Melani village in Alice in the Eastern Cape of South Africa was aimed at investigating the possible applications of the gasification byproducts instead of being thrown away. Pine wood was employed as the parent feedstock material for the gasifier. Biomass gasification by-products were then collected for further analysis. The studied by-products included tar(condensate), char, soot and resin. These materials were also blended to produce strong materials.The essence of the blending was to generate ideal material that is strong but light at the same time.The elemental analysis of the samples performed by CHNS analyser revealed that carbon element is in large quantities in all samples. The FTIR spectra showed almost similar results for all the studied samples, since the samples are end products of lignocellulosegasification. SEM gave the sticky images of resin as well as porous char structures. Char showed a higher heating value of 35.37MJ/Kg when compared to other by-products samples.

In der vorliegenden Arbeit werden verschiedene Methoden zur Bestimmung von Sintertemperaturen für Brennstoffaschen vorgestellt und verglichen, mit dem Ziel die Agglomerationsneigung von Aschen zu charakterisieren. Es wurden Untersuchungen an drei ausgewählten Kohleaschen unter inerten, oxidierenden und reduzierenden Bedingungen durchgeführt. Die Methoden Erhitzungsmikroskopie (ASV), Hochtemperatur-Röntgendiffraktometrie (HT-RDA), Thermogravimetrische Differenz-kalorimetrie (TG-DSC), Thermodynamische Gleichgewichtsberechnungen (GGW), Elektrochemische Impedanzspektroskopie (EIS), Untersuchung der Schereigenschaften (SV) und die Bestimmung der Kaltdruckfestigkeit (KDF) wurden angewendet. Die Kombination der Untersuchungen ließ eine umfangreiche analytische Charakterisierung der Sintervorgänge zu. Unter der Berücksichtigung einer guten Vergleichbarkeit hinsichtlich der ermittelten Sintertemperaturen, stellt die EIS eine Alternative zur etablierten aber zeitaufwändigen Bestimmung der KDF dar. In Abhängigkeit von der Aschezusammensetzung, der Korngröße und der Gasatmosphäre, ist bereits ab einer Temperatur von 650 °C eine Agglomeration von Aschepartikeln möglich.

The objective of this thesis is to provide an extensive description of the correlations in some of the most crucial sub-processes for hard coal fired IGCC with carbon capture (CC-IGCC). For this purpose, process simulation models are developed for four industrial gasification processes, the CO-shift cycle, the acid gas removal unit, the sulfur recovery process, the gas turbine, the water-/steam cycle and the air separation unit (ASU). Process simulations clarify the influence of certain boundary conditions on plant operation, performance and economics. Based on that, a comparative benchmark of CC-IGCC concepts is conducted. Furthermore, the influence of integration between the gas turbine and the ASU is analyzed in detail. The generated findings are used to develop an advanced plant configuration with improved economics. Nevertheless, IGCC power plants with carbon capture are not found to be an economically efficient power generation technology at present day boundary conditions.

Syngas consisting mainly of a mixture of carbon monoxide, hydrogen and other diluents, is an important fuel for power generation applications since it can be obtained from both biomass and coal gasification. Clean coal technologies require stable and efficient operation of syngas-fired gas turbines. The trapped vortex combustor (TVC) is a relatively new gas turbine combustor concept which shows tremendous potential in achieving stable combustion under wide operating conditions with low emissions. In the present work, combustion of low calorific value syngas in a TVC has been studied using in-situ laser diagnostic techniques and numerical modeling. Specifically, this work reports in-situ measurements of mixture fraction, OH radical concentration and velocity in a single cavity TVC, using state-of-the art laser diagnostic techniques such as Planar Laser-induced Fluorescence (PLIF) and Particle Image Velocimetry (PIV). Numerical simulations using the unsteady Reynolds-averaged Navier-Stokes (URANS) and Large Eddy Simulation (LES) approaches have also been carried out to complement the experimental measurements. The fuel-air momentum flux ratio (MFR), where the air momentum corresponds to that entering the cavity through a specially-incorporated flow guide vane, is used to characterize the mixing. Acetone PLIF experiments show that at high MFRs, the fuel-air mixing in the cavity is very minimal and is enhanced as the MFR reduces, due to a favourable vortex formation in the cavity, which is corroborated by PIV measurements. Reacting flow PIV measurements which differ substantially from the non-reacting cases primarily because of the gas expansion due to heat release show that the vortex is displaced from the centre of the cavity towards the guide vane. The MFR was hence identified as the controlling parameter for mixing in the cavity. Quantitative OH concentration contours showed that at higher MFRs 4.5, the fuel jet and the air jet stream are separated and a flame front is formed at the interface. As the MFR is lowered to 0.3, the fuel air mixing increases and a flame front is formed at the bottom and downstream edge of the cavity where a stratified charge is present. A flame stabilization mechanism has been proposed which accounts for the wide MFRs and premixing in the mainstream as well. LES simulations using a flamelet-based combustion model were conducted to predict mean OH radical concentration and velocity along with URANS simulations using a modified Eddy dissipation concept model. The LES predictions were observed to agree closely with experimental data, and were clearly superior to the URANS predictions as expected. Performance characteristics in the form of exhaust temperature pattern factor and pollutant emissions were also measured. The NOx emissions were found to be less than 2 ppm, CO emissions below 0.2% and HC emissions below 700 ppm across various conditions. Overall, the in-situ experimental data coupled with insight from simulations and the exhaust measurements have confirmed the advantages of using the TVC as a gas turbine combustor and provided guidelines for stable and efficient operation of the combustor with syngas fuel.

The objective of this thesis is to provide an extensive description of the correlations in some of the most crucial sub-processes for hard coal fired IGCC with carbon capture (CC-IGCC). For this purpose, process simulation models are developed for four industrial gasification processes, the CO-shift cycle, the acid gas removal unit, the sulfur recovery process, the gas turbine, the water-/steam cycle and the air separation unit (ASU). Process simulations clarify the influence of certain boundary conditions on plant operation, performance and economics. Based on that, a comparative benchmark of CC-IGCC concepts is conducted. Furthermore, the influence of integration between the gas turbine and the ASU is analyzed in detail. The generated findings are used to develop an advanced plant configuration with improved economics. Nevertheless, IGCC power plants with carbon capture are not found to be an economically efficient power generation technology at present day boundary conditions.