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Combined pyrolysis / Combustion / Electricity production cycle

Objectif

To incorporate a pyrolysis step in a coal-fired fluidized bed electricity production plant in order to obtain non-polluting chars from high sulphur coals with the highest energy yields while retaining sufficient oxy-reactivity in the chars for them to be burned.

The project undertakes the non-polluting combustion of sulphur rich coals by combining a pyrolysis process and a fluidized bed combustion. These steps will be studied separately. Two coals differing in mineral matter content, predominant sulphur forms and macerate composition will be studied. It has been shown that chars from pyrolysis remain sufficiently oxy-reactive to be burnt if de-volatilisation of coal is limited to the most reactive fraction. The purpose of the pyrolysis step is to release from coal as much sulphur as possible in a non-polluting form, leading most of the coal's calorific value to char and gases and keeping the char reactive enough to be burnt. The experimental conditions affecting the process, i.e. pressure, temperature, residence time, gas flow and particle size will be studied at laboratory scale (100 g) in order to find a mathematical model and to optimize the process. The oxy-reactivity of chars will be measured on a thermal-balance. The kinetics and mechanism of char combustion ill be studied on a laboratory scale (1 g) fluid bed combustor with added EGA. Studies on recycling gases, the relation between coal characterization and pyrolysis behaviour and the role of mineral matter in sulphur distribution will be carried out. Semi-pilot scale pyrolysis operations will be done in order to obtain enough char for the semi-pilot scale combustion experimental. It will be carried out on a semi-pilot unit which works up to 4 MPa and 1273 K and produces up to 1 kg/h of char in the steady-state.

The fluid bed combustion experiments will be carried out on a semi-pilot atmospheric unit which burns up to 5 Kg/h of coal in the steady-state. The temperature of combustion is controlled by four variable-surface heat exchangers. Combustion gases are monitored for SO2, NOx, CO and CO2, evaluating the combustion and sulphur retaining efficiencies as a function of temperature, excess air, and air flow. A mathematical model will be developed for char combustion. Fragmentation and attrition phenomena will be studied at laboratory scale in order to evaluate the combustion efficiency losses by elutriation of unburnt char particles.

Thème(s)

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Appel à propositions

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Régime de financement

CSC - Cost-sharing contracts

Coordinateur

CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS
Contribution de l’UE
Aucune donnée
Adresse
1,Plaza del Praíso 1
50071 ZARAGOZA
Espagne

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Coût total
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Participants (1)