ATZ Entwicklungszentrum Expose

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1 Our Objective Our Focus Our Scale Our Approach Processes & Materials for Energy Technology Energy from Biomass Wear an Corrosion Protection in Energy Technology Process Development up to Pilot Scale Plants Product Development up to Pilot Scale Production Know-how Creativity - Cooperation 09. Dezember 2004

2 Kropfersrichter Straße Sulzbach-Rosenberg Germany Phone Facsimile Internet ATZ is an independent research institution located in Sulzbach- Rosenberg, a town with a long steel-making tradition in eastern Bavaria. In the early years, ATZ worked mainly on energetic questions of the steel making process, metallurgy and new applications for steel making resources. Today, we develop innovative concepts for decentralized energy production from biomass and waste and on solutions for wear and corrosion problems in conversion systems for these materials. A team of experienced and innovative engineers, scientists and technicians develops processes and materials for energy technology in interdisciplinary working groups: PROCESS ENGINEERING processes for decentralized production of energy from biomass and waste - thermal process engineering, biological process engineering MATERIALS ENGINEERING wear and corrosion protection in energy technology - functional layers, powder materials Our services range from studies, technological consulting and process optimization to the development, engineering and construction of pilot-scale plants. 2

3 PROCESS ENGINEERING THERMAL PROCESS ENGINEERING The conversion of biomass and waste by combustion, gasification or pyrolysis is the task of the working group Thermal Process Engineering. The cleaning and treatment of hot off- and process-gases is also an objective of this team. One of the current key projects is the development of a process concept for generating power by using radial flow regenerative heat exchangers (Pebble-Heaters) and gas turbines. Figure 1 shows the principle of the system. Thermal energy from a biomass combustion system is transferred from the hot flue gas via Pebble-Heater-Technology to compressed air, which is subsequently used to generate electricity with a micro-gas turbine. Biological Waste Energy Storage Energy Release Chimney Biomass Combustion Heat Pebble-Heater Dust Collection Gas-Turbine Compressor Cooling Electrical Energy G Generator Air Figure 1: Energetic utilisation of biomass by thermal processes using Pebble-Heaters BIOLOGCIAL PROCESS ENGINEERING Biological Process Engineering deals with the production of biogas and bio-ethanol by fermentation of biomass. The activities of this working group comprise of technologies for the pre-treatment of biomass (thermal pressure hydrolysis (TPH) for the utilization of special waste material), optimization of fermenter and periphery (mixing, biomass feeding, heat exchanger, etc) gas cleaning (biological desulphurization of biogas BIOSULFEX) treatment of process water by standardized technologies and proprietary developments 3

4 CHPS Waste heat Biogas FERMENTER Gas cleaning Denaturalization of input feed pressure Fermentation residue about 20 bar temperature about 200 C Waste Incineration Figure 2: Energetic utilisation of biomass by biological processes thermal pressure hydrolysis (TPH) MATERIALS ENGINEERING In biological and thermal processes corrosion is a severe problem that often causes premature damage of components. The Materials Engineering Department of ATZ is active in the fields of surface modification, corrosion and erosion investigation. One success of investigating surface modification by laser is the improvement of cylinder liners. The project was done in cooperation with AUDI, the University of Bayreuth, and the University of Applied Sciences Amberg-Weiden. The technology developed in this project is now used in the direct-injection diesel engines 3.0 in the Audi cars A4, A6, A8 and was nomi nat edf ort he Deut scherzukunf t spr ei s2004 ( pr i cef ort hebestger mant echnol ogi cal innovation). FUNCTIONAL LAYERS The material choice for thermal and biological energy plants has to be based on a lot of requirements. Stability, material price, machinability, availability and resistance against corrosion and erosion are some of the important requirements. In general, the components of plants converting biomass and waste to energy are made of materials, which are not optimized according resistiveness. For corrosion protection and lifetime extension of these components coatings with more resistant materials (mainly nickel base alloys) are applied. Nowadays, cladding is the most usual process for the protective coatings. 4

5 a Coating alloy Coating alloy coated uncoated 50µm c b 50µm Substrat d Substrat Figure 3: Coating of pipes by thermal spraying (a: coating of pipes, b: partially coated pipe after 4100h use in an incineration plant, c: cut of the coating after fabrication, d: cut of the coating after 700h use in an incineration plant) Since cladding processes are costly, alternative processes have been researched during the last years. A promising and economic alternative is the technology of thermal spraying. The specific costs of thermal spraying are much lower than the specific costs of cladding. In addition, coating by thermal spraying reduces the risk of mixing up substrate and coating material. First practical results demonstrate that thermal spraying has the potential to create cost-efficient coatings to protect components in the critical zones of incineration plants. Until now, there are still not enough experiences in questions of quality assurance (porosity, oxides) and long run behaviour inside the incineration plants with sprayed coatings. For many years, ATZ has been involved in the development and advancement of materials, technologies and applications of thermal spraying for corrosion protection. In a current research project, ATZ investigates different coating strategies for applications in energy technology: pipes, coated with different materials (alloys, ceramics), using different technologies (HVOF, APS, wire arc spraying), are tested by different strategies (coated pipes in operation as part of the superheater of incineration plants, air cooled corrosion probes inside the hot gas area of an incineration plant, and corrosion tests under laboratory scale). Besides testing various coatings under real-life conditions, ATZ is also involved in the advancement of technologies and applications of thermal spraying itself. Thermal spraying represents a group of processes, which employs heat and velocity to coat the surface of one material with another, using powder or wire feedstock. These processes are characterized by zero dilution of the substrate as a result of mechanical bonding, the ability to apply thin coatings, and a high rate of area coverage compared to arc welding processes. The low deposit temperatures (as compared to welding) mean no distortion or metallurgical degradation of the substrate. Thermal spray processes are all positional and can be operated in air, thus offering great flexibility for a wide range of applications. 5

6 Substrate Heat-up and speed-up Spraygun Energy source - Flame - Arc - Plasma Sprayed layer Spray material - Powder - Wire - Bars Particle Figure 4: Thermal Spraying - Principle There are several important processes based on oxy-fuel flames and non-transferred arcs. The three processes of most commercial interest are twin wire electric arc spraying (EAS), high velocity oxygen fuel (HVOF), atmospheric plasma arc spraying (APS). The wide range of spraying temperatures and particle velocity characteristics of the various processes impart different coating attributes in terms of porosity and bond strength, and allow spraying of metals, cermets, and ceramics. POWDER MATERIALS To provide a wide spectrum of coating materials and to offer reproducibility, different fabrication lines for powder materials in laboratory and semi plant scale are available. ATZ has developed a unique hot-gas atomization technology, which allows the development and production of powders that are not available on the market. Atomization of melts using hot gases has advantages compared to conventional gas atomization techniques. Some of these advantages favour the hot gas technology for the powder production for thermal spraying: considerably higher output of fine powder, in particular within the important particle size range between 5 and 30 µm, due to strongly increased gas exit velocity and the higher overall temperatures inside the interaction zone of the gas and the melt droplets. Shear forces acting on the molten liquid are enhanced by higher gas velocities. This leads to a more efficient primary atomization. Simultaneously, the heat exchange between the atomized melt droplets and the surrounding gas is reduced. Thus, the liquid state of the atomized particles is prolonged, leading to an extended time interval for secondary atomization events. 6

7 prolongation of the liquid phase allows atomization of highly viscous melts, such as metal oxides. Furthermore, the extended time regime leads to a more spherical shape of the particles with good flowability. oxide or nitride powders can be generated directly from the molten metal by the usage of hot reactive gases or gas components for atomization. For the analysis of powders and coatings different visualisation and measurement systems are available (SEM/EDX, DSC/TG, metallography). a b c Figure 5: Fabrication of powder materials d (a: bronze powder, b SEM of a solder alloy powder, c cross section of a cryogenic liquid gas atomized hard magnetic NdFeB alloy particle, d atomisation unit) 7