A 3-year PhD position on the above mentioned topic is open. The project will be conducted at the CHEC (Combustion and Harmful Emission Control) Research Centre, Department of Chemical Engineering at the Technical University of Denmark.
Background
The use of biomass in large suspension fired boilers can ensure a renewable, efficient and CO2 neutral supply of electricity and heat. However, by changing fuel from coal to biomass on the power plants several technical issues such as combustion stability, ash deposit formation, emission minimization and fuel conversion have to be dealt with. A large research project (GREEN) dealing with biomass suspension combustion has been started and is managed by the Department of Chemical Engineering at DTU. The GREEN project includes collaboration with several companies, universities and research institutions, and as part of the project a PhD study will be started that deals with biomass particle combustion.
One of the problems by using biomass in suspension fired boilers is that the biomass particle size are relatively large compared to pulverized coal particles. Generally it is accepted that relatively large top size biomass particles (0.5 - 1.5 mm) compared to coal particles (top size 0.1 – 0.3 mm) has to be applied on boiler plants to prevent undue large energy consumption on biomass milling.The large biomass particle size may induce problems with ignition, flame stability and burn out. An improved biomass combustion modeling is wanted to make it possible to predict and solve problems related to biomass dust combustion.
Project objective
It is the objective of the project to provide an improved understanding of the behavior of relatively large biomass particles in dust fired power plants with respect to particle grinding and particle conversion in the boiler chamber. This will include a model that shall describe ignition, pyrolysis and char conversion of single biomass particles at typical local boiler conditions. The PhD project will be coordinated with other GREEN activities to provided tools that support the efforts of the power plant companies Vattenfall and DONG Energy to use an increased amount of biomass on Danish power plant boilers.
Project description
The final content of the PhD will be planned by the student, supervisors and power plant company project participants. The following topics may be a part of the project:
- Characterization of biomass particle size and morphology as a function of biomass type and pretreatment method
- Study on biomass particle ignition as a function of particle properties and local conditions
- Development of an experimentally based one-dimensional model that describes different types of biomass particles conversion in suspension fired boilers. The model, which needs to describe satisfactorily particle pyrolysis and char oxidation, should be in a form that allows implementation into a CFD model of a suspension fired boiler
Two advanced solid fuel combustion reactors are available for the experimental project work. A single particle combustion reactor where the combustion process is registered by video recordings and gas analysis and an entrained flow reactor where solid fuel combustion at high temperatures and short residence times can be investigated. The PhD project is part of the GREEN project and will be coordinated with other GREEN research activities.
PhD Scholarship in Fly Ash and Deposit Formation
