What we do in thermal technology

Here we describe some examples of ongoing research activities within the thermal technology programme. As described below, development is primarily concerned with making the power plants more efficient and improving environmental performance.

Ash related effects during co-combusting coal and biofuels 
Optimisation of Maintenance and Availability (OoMaA) 
Storage of biomass 
Fuel characterization 

Ash related effects during co-combusting coal and biomass fuels

Co-combustion of biomass and coal might lead to an increased risk of ash related problems. It will depend on type of biomass and share of biomass. In cooperation with a German university the ash related effects when co-firing different coals with different solid biomass fuels have been investigated by tests in a small scale fluidised bed reactor.

The results indicate an absence of fine mode particles in all experiments with mixtures of biomass and coals, which is of great relevance from a deposit formation point of view. The results also strongly indicate positive effects on ash melting behaviour from mixing of the fuels. It also shows the influence of the biomass used and share of biomass, as well as the quality of the coal.

Optimisation of Maintenance and Availability (OoMaA)

Planning of maintenance may be difficult since there is a number of factors (economic as well as technical and operational) affecting the optimal time for doing maintenance. In the OoMaA project a method is developed to be used for optimisation of the time interval between maintenance actions. An on-line method and a set of standardized software tools will be used for prediction of the optimal time for maintenance from an economical point of view. It is based on the present condition of specific plant components described as KPIs (Key Performance Indicators), and estimation of the future degradation of the components. The methodology is being demonstrated at one of Vattenfall’s plants in Germany Wedel Unit 1.

Storage of biomass

Storage of biomass is often associated with problems such as heat development with a risk of self-ignition, dry matter loss and reduction of fuel quality. This dry matter and energy loss has an economical impact for the heat and power plants, since more biomass than estimated needs to be purchased to attain the planned energy output. The output of the project is to supply heat and power plants with guidelines on how to store large amounts of biomass in an optimal way. Full-scale storage trials are running at the Vattenfall plant Idbäcken, in Nyköping Sweden.

Fuel characterization

There is an increased interest in making use of new biomass fuels, for example energy crops and different waste streams, thermally processed raw materials, as well as blending of different fuels; either coal and biomass or different biomasses, to reach better fuel properties. Vattenfall is working with improved laboratory methods for analyzing fuels and for predicting the behavior of the fuel / fuel blend in a plant. By using improved methods for fuel characterization the operation cost for the plants can be reduced.