The objective of the project is to develop a basis for design of cyclone gasifiers to be used in a novel way for gas turbine cogeneration plants fuelled with powdered biomass. It is expected that the process to be studied will make it possible to reduce the investment required for building wood fuelled cogeneration plants in the capacity range 100 kW(e) to about 20 MW(e). An important objective is to find out which of three suggested cyclone designs is preferable and which of four fuels is the most suitable.
In the process that will be studied, the biomass is rapidly gasified in a pressurised cyclone, leaving a char residue with a significant portion of the sodium and potassium brought with the biomass fuel. The hot product gas is burned in an adapted combustion chamber without further gas cleaning. The hypothesis is that if the gasifier is operated under the right conditions, the Na- and K-compounds which do enter the gas turbine will have a melting temperature above 800 - 100K, i.e. above the material temperature of industrial gas turbines designed for moderate inlet temperatures. The char residue obtained from the cyclone gasifier can be used as fuel for a supplementary fired heat recovery boiler and will not be wasted. Both theoretical and experimental work will be required to increase the understanding of factors effecting the operational performance of gasification cyclones. Key problems to be studied are :
a) The controlled feeding of the powder into the cyclone;
b) Optimisation of cyclone design with respect to separation of Na- and K-compounds;
c) Adaptation of gas turbine combustors for burning of the product gas from the cyclone gasifier;
d) Dynamic behaviour of the system and;
e) Deposition of Na- and K-compounds in the turbine as functions of gas impurities and inlet temperature to the turbine.
The proposed joint research project is focused on experimental and theoretical studies of the performance of gasification cyclones. Three different basic geometries will be studied experimentally. The results will be used to validate numerical models for prediction of cyclone gasifier performance. In order to provide a basis for definition of performance requirements for the cyclone gasifier, the project also includes theoretical and experimental studies of gas turbine combustor performance with product gas from cyclone gasification and theoretical modelling of deposition of Na- and K-compounds in a gas turbine. Practical tests to study deposition in a small (40 kW) gas turbine operated on product gas from a cyclone gasifier will be carried out .
Expected achievements and exploitation
It is expected that the process will find a market in particular for plants in the small and medium capacity range, i.e. up to about 20 MW(e). The conditions under which gas turbine cogeneration plants using cyclone gasifiers for wood powder will be financially feasible in district heating systems and industrial cogeneration plants will be established by a financial feasibility evaluation, using performance data that have been established in the project. Experience from Sweden, where wood powder is a commercial fuel, demonstrates that the preparation of this up-graded bio-fuel is cost effective in many applications.
Funding SchemeCSC - Cost-sharing contracts
612 82 Finspang
941 28 Piteå
BS21 7TG Clevedon - Somerset
100 44 Stockholm
CF2 1XH Cardiff
162 87 Stockholm