Electrostatic ReCyclone® systems: Modelling and application to emission control from biomass boilers


The recent development of efficient electrostatic ReCyclone® systems allows their application to biomass boilers for strict legal limit compliance. The purpose of this paper is to present a model to predict in a more realistic way the collection efficiency of a gas cyclone with an electrostatic enhanced recirculation system. These systems consist in an optimized reverse-flow cyclone (col- lector) combined with partial recirculation of un-captured particles via a straight-through cyclone (concentrator). A DC electric field is applied to the concentrator to enhance particle recirculation to the cyclone collector, leading to very high collection efficiencies.

To model the system, a computer program (PACyc) was recently developed. The model, starts by estimating the collection efficiency of a system without agglomeration, building what is referred as the baseline grade-efficiency curve. To build this baseline curve, the PACyc model relies on previously published models to predict collection efficiency either for isolated cyclones, or for cyclones with mechanical/electrostatic recirculation.

After solving the particle trajectory in a turbulent flow field inside the cyclone, and by employing a fixed set of parameters, PACyc determines if a collision/agglomeration occurs. The result of this procedure is an altered grade-efficiency curve after agglomeration (a composite curve), since the initial particles will have a dynamic behavior inside the cyclone as a newly formed agglomerate. The calculated efficiency will significantly increase above theoretical predictions without agglomeration, and this can be observed in various experimental results, usually referred as “hook-like” grade- efficiency curves.

Some experimental results obtained in biomass boilers burning wood and coke are presented, together with the corresponding PACyc predictions on grade and global collection efficiencies.

Customer comments

  1. By dinkar vora on

    wow,good concept.when hot flue gas eminates with containing heavy doze of particualate, magnatic field cou;ld serve attracting.If it is true, it can be expanded to all coal based fuel.One does not need complicated equipment but some modifications. any way,idea is great, as and when commercialized DINKAR VORA MOTIVE POWERS INC MUMBAI INDIA