Figure 1:  KIT- Institute for Technical Chemistry laboratory plant KLEAA

Deutsche Vereinigung für Verbrennungsforschung (DVV), IFRF’s German Flame Committee,  is a member of the German Federation of Industrial Research Associations (AiF). This is the leading national organisation promoting applied research and development benefiting Germany’s small and medium-sized businesses.  AiF provides public funds for research projects, with DVV carrying out such projects through its university and research organisation members.

Four further projects to those reported on previously by the IFRF have been added to the DVV portfolio as described below, with the full listing of current and previous projects provided on the DVV website.

1: Experimental investigations and simulation studies on the resistance of ceramic burner components to thermal stresses  (AiF number- 73 LBR)

Research partner: TU Dresden, Germany- Prof. Beckmann

Duration: Nov 2023- April 2026

Abstract: Industrial burners are primarily powered by natural gas, with other hydrocarbons such as propane, butane, ethylene or carbon monoxide also being used as fuel gases. Against the backdrop of reducing greenhouse gas emissions, the importance of alternative, non-fossil fuels is increasing. This includes hydrogen, which is intended to replace traditional energy carriers in the field of industrial burner applications. The conversion from natural gas to hydrogen requires technical changes to the previous burners as a result of changed fuel gas parameters and the resulting changed combustion conditions. In addition to design changes, there are also changed material requirements for the particularly stressed components of the burners, which result from the higher flame temperatures. With regard to increased thermal and corrosive loads, ceramic materials can contribute to higher reliability, increased efficiency and reduction of resource consumption in the production of burners.

This project is developing the basic technological knowledge for the production of ceramic burner components resulting from the effects of changing the fuel from natural gas to pure hydrogen. The focus of Sub-project 1, which is being carried out by the research institutions Fraunhofer Institute for Ceramic Technologies and Systems IKTS Dresden, Günter Köhler Institute for Joining Technology and Materials Testing GmbH Ifw Jena, is on the diffusion joining of ceramic foils and the material property adaptation for film composites. The aim of Sub-project 2 is experimental and theoretical investigation and evaluation of ceramic burner components under typical practical operating conditions. To this end, the structural design of demonstrator components for industrial hydrogen burners is developed on the basis of simulation and knowledge, as well as in coordination with the manufacturing requirements. Practical tests are then carried out with the manufactured demonstrator components and the need for optimisation identified.

2: Spray roasting – Influence of reactor parameters on oxide quality (AiF number- IGF 23117)

Research partner: Ruhr-University Bochum – Prof. Scherer 

Duration: Nov 2023- April 2026

Abstract: Spray roasting reactors are used for the thermal treatment of dissolved metal salts, which are converted into metal oxides by the thermal process of pyro-hydrolysis. Depending on the metal salt of interest, the process temperature is in the range of 350-600 °C. 

Although spray roasting reactors follow basic design principles, there is no general set of design rules that recommend specific measures for plant operators and plant builders.

The project aims to derive general causal relationships between the burners used for spray roasting reactors and the resulting product quality and to make them accessible to industry, especially SMEs. Since there are complex flow fields in spray roasting reactors and the facilities are usually not sufficiently accessible for invasive measurement technology, a combination of laboratory experiments and flow simulations (CFD) considering the drop/particle phase is used as a solution approach.

In addition to the material flows, important input variables of the simulation are the momentum transfer of the fuel gases to the reactor, but also the droplet size distribution of the injected solution. To determine the influence of the burners and combustion chambers on the particle formation process, they are simulated with high resolution, whereby a variation of the gases used (natural gas, hydrogen or ammonia) is provided. These results can then be incorporated into the simulation of complete spray roasting reactors with gas phase and reactive particles. To describe particle conversion, experiments with real nozzles (particle formation from iron chloride solutions) provide the basis for further adaptation of an existing numerical model. In addition to generic reactors, the simulation will also consider a pilot plant in which measurements will be carried out for comparison with the simulation. In addition to measuring the oxide properties (purity, specific surface area, particle size distribution), measurements of gas temperature and particle velocities are also possible here.

3: Oxyfuel Incineration of waste streams with electrolysis oxygen and analysis of usage pathways of captured CO2 with H2 (AiF number: IGF 23237)

Research partners: University Stuttgart, Germany- Prof. Reinmöller, and  Karlsruhe Institute of Technology (KIT), Germany- Prof. Stapf 

Duration: Feb 2023 – July 2026

Abstract:  The introduction of oxyfuel combustion technology in waste incineration can enable, among other topics, more efficient CO2 capture. Oxyfuel combustion uses a mixture of O2 and CO2, such as recycled flue gas, instead of air. In addition to a more concentrated CO2 material flow in the flue gas, ash qualities can be optimised and slagging/corrosion behaviour should be influenced depending on the combustion conditions in the system. The heat transfer in the boiler is also optimised by the CO2 increase in the flue gas.

This project aims to determine whether oxyfuel technology is suitable as a resource saving and energy efficient solution for grate firing systems. Therefore, tests are initially  carried out on a smaller scale at KIT’s Institute for Technical Chemistry laboratory plant KLEAA, as shown in figure 1. The results are then transferred to a pilot plant with a moving grate (ROFEA) at the University of Stuttgart, Institute of Combustion and Power Plant Technology. Finally, the project enables an economic study to be carried out with a process simulation based on the experimental data as well as reference measurements in a waste incineration plant.

4: Optimisation of the Clinker Burning Process in the Cement Industry: Prediction of the Flight Behavior of Refuse-Derived Fuels by Classifying Fuel Flows (AiF number: IGF 23609)

Research partners: Ruhr-University Bochum- Prof. Scherer, and VDZ Technology GmbH – Research Institute of the Cement Industry- Dr. Schneider 

Abstract: In the cement industry, refuse-derived fuels (RDF) are used to replace fossil fuels. RDF is more cost-effective and is partly burned in a CO2-neutral manner due to its biogenic content.

When injecting RDF, its flight characteristics are relevant, as they are directly coupled to the local heat release. If the deviation from operation with reference fuels is too large, this can lead to problems. For example, a change in the temperature profile shifts the zones for clinker phase formation and affects the clinker product, where incompletely burned RDF particles in the clinker bed can negatively change the clinker properties.

Full-scale experiments are too costly, whereas 3D combustion simulations (CFD simulations) offer an alternative lower-cost approach. However, there is a lack of experimentally validated models that describe the flight characteristics of converting EBS particles.

The aim of the project is therefore to develop a method to determine drag and buoyancy coefficients of RDF particles of different degrees of conversion quickly and on site. This is done through a combination of experiments, fluid mechanics considerations and tools from machine learning. The coefficients are incorporated into CFD models, which make it possible to calculate where RDF particles hit the clinker bed and with what degree of transformation. This can be used to predict the flight characteristics and implementation properties of different EBS batches. This enables corrective measures in operation and quality assurance in the plant.

The results could increase the use of RDF and thus increase the competitiveness of German cement production. The project is of great importance for the German cement industry and its often medium-sized suppliers. SMEs in the fields of fuel processing, CFD services and machine learning could benefit directly.