Deutsche Vereinigung für Verbrennungsforschung (DVV) – IFRF’s German National Committee – is a member of the German Federation of Industrial Research Associations (AiF), 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. DVV’s industry members provide consultancy to the projects throughout their duration.
Currently, five projects are active:
Interplay of flow behaviour of granular material and gas flow in shaft kilns
The movement of particles in shaft kilns is influenced by the counter-flowing gases even below the minimum fluidisation velocity. The project examines this effect, employing experiments and CFD/Discrete Element simulations at different scales. Different particulate material is examined, e.g. iron ore sinter. The knowledge of particle movement is essential as it influences the residence time in shaft kilns and, therefore, the product quality.
Detailed CFD models for the combustion of Refuse Derived Fuel (RFD)
RDF is an important waste-based fuel, especially in the cement industry. The project derives detailed fraction-specific combustion and flight models for the complex shaped RDF particles. The statistical distribution of the physical and chemical properties of the RDF fractions are considered. The CFD models are validated against measurements of RDF trajectories measured by optical methods in a semi-industrial rotary kiln at the Institute for Technical Chemistry at Karlsruhe Institute of Technology (KIT).
Analysis of the influence of fines formation and humidity on the storage and conveying of wood pellets in domestic wood pellet storage
Fines formation and humidity create problems for domestic pellet storage. Fines accumulate in certain regions of the pellet storage and thereby reduce storage capacity and negatively influence the transport of the pellets from the storage to the combustion systems. Humidity leads to a deterioration of mechanical pellet properties. The project examines the fines formation and fines accumulation in a real pellet storage system by experiments and CFD/Discrete Element simulations. Storage design features and delivery operation parameters are varied. Humidity transport in pellet bulks is also examined by numerical and experimental methods.
Development of highly efficient grate combustion systems for wood chips with varying humidity
The standard system for the combustion of wood chips is the stoker grate. The humidity of the chips can vary in a wide range, making a simple and reliable combustion control difficult. The project develops a control system based on a variable control of primary and secondary air in combination with the stoking mode. Experimental work on a laboratory stoker grate, which allows the measurement of the rate of wood chip mass loss, is carried out. The experiments are accompanied by CFD/Discrete Element simulations.
Wood pellet degradation in different types of delivery trucks
The details of the degradation processes inside delivery trucks for pelletised fuels are currently unknown and are the topic of this project. Four different vehicles (varying manufacturers, systems, and components) covering the range of commonly used discharging systems will be assessed. The trucks will be equipped with measurement devices for pressure, force, volume and mass flows (air and pellets), temperature and other relevant operating characteristics which allow for time-resolved data acquisition during the discharging process. Measures to achieve a gentle pellet delivery will be identified. See IFRF blogpost from 22nd November for more information about this project.
In addition to these five ‘live’ projects, two further projects will be starting in 2021:
Improved drying of wood chips in convective drum dryers through optimisation of built-in agitation components
The drying of woody biomass in rotating drums is very common in industry. The drying media can be a hot exhaust gas or steam. The drum usually contains built-in components to agitate the bulk of woody biomass and thereby provide an intensive contact of the wood and the drying media. The project aims at a deeper understanding of the drying process in such devices and to provide the design guidelines for the lay-out of the agitation components. A mixture of experimental and numerical studies will be applied.
Development of flexible grid burner systems for the integration of process gases and hydrogen into industry processes
Grid burners are present in many industrial applications, for example for drying purposes in the wood industry or for the non-catalytic conversion of pollutants in exhaust gases. Compared to other type of burners, combustion does not take place in pure air, instead a tail gas of an industrial process is used as the oxidiser. The increasing importance of hydrogen poses new challenges to grid burner design. Therefore, the project addresses the design of fuel and load flexible grid burners. A combination of experimental and numerical studies will be used to improve the understanding on the phenomena in grid burners and based thereupon to define design criteria.