BioMatNet Item: JOULE JOR3-CT97-0191 - Reduction of toxic emissions from co-combustion of coal, biomass and waste in fluidised bed

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JOULE JOR3-CT97-0191
Reduction of toxic emissions from co-combustion of coal, biomass and waste in fluidised bed

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JOULE/THERMIE Programme : Solid Biofuels : Thermochemical Conversion

	Type of Project	Shared Cost
	Contract No	JOR3-CT97-0191
	EC Contribution	893,500 ECU
	Start Date	01/12/1997
	Duration	36 Months

Reduction of toxic emissions from co-combustion of coal, biomass and waste in fluidised bed

Objectives

The project aims to significantly improve the potential to use waste for energy production through co-combustion with suitable main fuels in fluidised bed boilers. Four of the five waste types and two of the three main fuels are biomass. The objective will be met by identifying ways in which the concentrations of harmful components in flue gases can be reduced below the upper limits proposed by for EU legislation. At the same time methods for flue gas analysis of some important toxic metals will be improved.

Technical Approach

A boiler manufacturer, a power company, universities and a research centre participate in this project which is divided into four tasks. Fuels will be prepared, analysed and characterised in the first task. Wood, coal and a one to one mixture of coal and straw will be used as the main fuels. Sewage sludge, paper sludge, agricultural waste, pulp sludge and plastic waste will be used as additional fuels.

New on-line methods for analysis of Pb and Cd will be developed in the second task. The third task will concern scaling-up as well as development of improved methods for predicting the potential emissions of toxic metals, SO₂, NO_x and chlorine compounds. The fourth task concerns provision of information required to use sewage sludge and paper waste in a CFB power plant.

The scaling-up process will occur in three steps. First, the most hazardous blends will be determined using a laboratory-scale FB reactor. The less hazardous blends will also be combusted in bench- scale reactors. From these experiments the best blends for use in pilot-scale experiments will be selected. Finally, industrial scale experiments will be carried out to complete the whole scaling-up process.

Expected Results

The immediate effects of the project will be an extension of the spectra used in a Danish Grenå 79 MW_th CFB plant as well as improved potential for scale-up by a boiler manufacturer. The results will identify methods of reducing the emissions of toxic metals, SO₂, NO_x and chlorine compounds below the required upper limits for the fuels investigated. At the same time the maximum amount of waste that can be used in the blends investigated will be determined.

The achievements will include:

a new on-line method for analysis of Pb and Cd in flue gases of power plants
a new scaling-up procedure to predict the emissions of the harmful compounds studied in fluidised bed combustion, where the results from bench-scale reactors are important
clear guidelines of ways in which to keep the emissions of toxic metals, SO₂ and NO_x below the upper limits suggested by EU.

These guidelines and the new scaling-up procedure will be available for companies planning to widen their fuel spectrum in bubbling and circulated bed power plants.

Contacts

Coordinator

Martti Juhani AHO / VTT Technical Research Centre of Finland / FINLAND

Participant