ECN publication
Early Agglomeration Recognition System - EARS: From bench-scale testing to industrial prototype
Korbee, R.; Lensselink, J.; Ommen, J.R. van; Nijenhuis, J.; Gemert, M. van; Haasnoot, K.
Published by: Publication date:
ECN 1-10-2004
ECN report number: Document type:
ECN-C--04-052 ECN publication
Number of pages: Full text:
51 Download PDF  


This report describes the development and testing of a method to monitor and control agglomeration in a bubbling fluidised-bed combustor. EARS - for Early Agglomeration Recognition System - detects agglomeration in an early stage and allows operating staff and engineers to control the agglomeration process and prevent defluidisation.


The project EARS-I was carried out between 15.11.2001 and 29.02.2004. The development was a joint effort of the Energy research Centre of the Netherlands and the Technical University of Delft. The project was carried out together with partner Essent Energie Productie, who installed and hosted the testing of the EARS system in a wood-fired, 80 MWth bubbling fluidised-bed combustor in Cuijk, the Netherlands.

EARS was extensively tested on different bench-scale facilities. EARS was demonstrated to be sensitive to changes in the size distribution as well as the stickiness of particles in the fluidised bed. Both are key parameters in bed agglomeration. For the bench-scale facility a method was developed to control the level of agglomeration in a fluidised bed by means of bed material make-up.

A prototype of the monitoring and control system was tested in the Essent wood-fired, 80 MWth bubbling fluidised-bed combustor in Cuijk, with the aim to develop solutions for typical industrial aspects such as scale-effects, disturbance of other process signals, equipment issues, and process control. A positive relation was found between the S-values calculated by EARS and the mass fraction of a particle size considered to be an indicator for the level of agglomeration in the bed. Under industrial conditions EARS is not disturbed by up to 10% variations in the fluidising velocity or bed height. The reliability of EARS was further increased by various techniques, e.g. filtering. Prior to a plant stop, EARS was tested and used to support a reduction of the sand make-up rate. A decrease of about 35% was established with minor changes in bed agglomeration. EARS successfully detected the observed changes in the particle size distribution.

Recently, a follow-up project EARS-II was initiated to finalise the design for bubbling fluidised-bed systems and to develop a prototype for circulating fluidised-bed systems.

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