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Optimisation of cleaning efficiency of electrostatic precipitators

Objective



Electrostatic precipitators are extensively used to collect particulate emissions form a wide variety of industrial units, as power production plants, mining processes, cement industry etc. Although the performance of the modern precipitators is high, further increase of collection efficiency is strongly desired due to both the environmental regulations and the significant room for cost reduction.

The proposed research project intends to deepen the current knowledge of the electrohydrodynamic behaviour of the two-phase flow inside the precipitation chamber and to optimise the flow velocity profiles in order to increase the collection efficiency. Uniform velocity distribution across the precipitation domain is commonly adopted today, assuming a correspondingly uniform concentration of the discrete phase. However, particle reentrainment due to rapping action of the collection plates results in higher concentrations toward the lower part of the precipitator. Thus, the use of properly skewed velocity profiles, which is proposed here, can provide for longer residence time of flow stream-lines where the particle loading is higher.
The main objectives of the contract can be summarised as follows: Experimental investigation of electrostatic separation in laboratory-scaled facilities, using state-of-the-art measuring instrumentation and techniques.
- Construction of a data base of benchmark accuracy measurements for the validation of related CFD codes. Effects of fluid velocity distribution, particle size and shape, and particulate material type will be included in these data.
- Development and evaluation of an advanced computer code for the accurate simulation of the flow and all the separation mechanisms involved in the electrostatic separation process. The code will combine up-to-date numerical techniques with new models for the particular electro-physical mechanisms (particle charging, agglomeration, reentrainement etc.). - Development of a framework with optimisation guidelines for a real precipitator design, based on both experimental and numerical results. - Adaptation of the proposed modifications in a large-scale industrial precipitator and assessment of the obtained efficiency increase, under real operation conditions.

The research will be carried out in three main phases: During the first year of the project the laboratory facilities will be set-up and the measuring equipment will be prepared and calibrated. Also, an existed two-phase numerical code will be further developed and enriched with the new models required. Moreover, detailed measurements of the flow velocity and concentration at the inlet and the outlet section of a real precipitator in normal operation will be carried out. Detailed laboratory measurements will be performed during the second year and the results will be used for a comprehensive validation of the computer code in order to improve the physical and numerical modelling. Finally, during the third year the experimental and numerical findings will be applied to modify the design of an industrial precipitator in order to obtain the desired flow velocity profiles. Measurements will follow to examine the achieved efficiency improvement.

The expected reduction of uncollected particulates, which is estimated to 30-50% or more, will offer important environmental benefits, and at the same time significant saving of capital and operation cost of the electrostatic precipitators.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

National Technical University of Athens
Address
5,Heroon Polytechniou Avenue
15773 Zografou
Greece

Participants (2)

IMPERIAL COLLEGE OF SCIENCE, TECHNOLOGY AND MEDICINE
United Kingdom
Address
Exhibition Road
SW7 2BX London
PUBLIC POWER CORPORATION
Greece
Address
30,Chalkokondili Street 32
10432 Athens