JOULE JOR3-CT98-0278 Increased combustion stability in modulating biomass boilers for district heating systems

Contacts




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JOULE/THERMIE Programme : Solid Biofuels : Thermochemical Conversion

	Type of Project	Shared Cost
	Contract No	JOR3-CT98-0278
	EC Contribution	1,224,300 ECU
	Start Date	30/06/1998
	Duration	36 Months

Increased combustion stability in modulating biomass boilers for district heating systems

Objectives

The main objective of this project is to improve the combustion stability for small and medium sized biomass fired boilers aimed for small district heating networks. Investigated boilers in the thermal output range of 0.5 to 10 MW, show too high levels of harmful emissions at low and at varying loads and different ways to overcome this problem will be investigated within the project. This includes the development, design and construction of different combustion units to improve the conditions under which the combustion takes place. New means to monitor and control the combustion is included in the project and software will be developed to better describe the combustion process. The improvements will be verified by measurements and the different approaches compared by their impact efficiency and emissions of NO_x, VOC and particles over the entire load range.

Technical Approach

Three different combustion units will be designed and constructed in order to maintain high combustion stability at low and at varying load, namely:

• pulsating combustion with a 500 kW prototype boiler
• stationary vortex combustion with acoustic stimulation in a 150 kW boiler
• 500 kW boiler with partitioned combustion chamber and heat storage.

New and low-investment equipment to monitor the combustion process will be used together with simplified simulation software, fast enough to be utilised in the control system for boilers of actual size. Software to simulate the pyrolysis and gasification of fuels on the bed will be developed and the software CFX together with developed routines for the combustion of the gas phase will be used to predict the influence from geometry and boundary conditions on the formation of harmful emissions.

Expected Results

After completion of the project, different ways to overcome the problems identified when boilers are run at low and at varying loads will be demonstrated. New biomass fired boiler concepts, new and inexpensive control equipment and reliable simulation tools will be made available to boiler manufacturers and to energy utilities, thereby speeding up the changeover from fossil to biomass fuels and making it possible to reduce emissions of CO₂ without increasing other harmful emissions. It is expected that after the end of the project two years are needed to transform the results into fully developed industrial products for the market.

Contacts

Coordinator

• Roger HERMANSSON / Luleä University of Technology Department of Mechanical Engineering / SWEDEN

Participant

• Christian GAEGAUF / Foundation for Appropriate Technology and Social Ecology / SWITZERLAND
• Gernot STAUDINGER / Graz University of Technology (AMVT) AUSTRIA
• Technical Research Centre of Finland VTT Fuel Handling and Combustion / FINLAND
• Björn ZETHRAEUS / Växjö University Dept of Bioenergy Technology / SWEDEN