Mechanical ReCyclone® MH system convertible to an electrostatic ReCyclone EH®.
This equipment is composed by 18 hurricane cyclones and 18 mechanical recirculators working at a flowrate of 50 400m3/h at 40ºC. System designed for product recovery and emission control of animal fertilizer dust.
Expected emissions: < 50mg/Nm3
Measured emissions: < 40mg/Nm3
Hurricane system and sedimentation chamber for mining machine for the recovery of leftover material in mining operations.
Hurricane geometries maximize powder collection for each different application, while minimizing reentrainment and keeping pressure drop at reasonable levels.
These high efficiency cyclones are the output of nonconvex nonlinear problems formulated and solved after years of work in partnership with the Faculty of Engineering of Porto.
A single Hurricane is more efficient than any other known cyclone available in the market for the same pressure drop, usually resulting in less than half of the emissions of other high efficiency cyclones available.
In order to obtain very high efficiencies and compliance with emission limits, an improve recirculation system has been designed to take advantage of the Hurricane cyclones. A mechanical ReCyclone®
(ReCyclone® MH) is made up of a Hurricane with a particle separator (straight-through cyclone), placed downstream of the cyclone - called the "recirculator".
The main purpose of the recirculator is to reintroduce the fine non captured particles into the cyclone after those have been driven to the outer walls of the recirculator by centrifugal forces. While this tangential gas stream is enriched in particles, the axial gas stream exhaust to the stack is clean of particles. Recirculation is achieved through an additional fan.
Since the recirculation system only serves the purpose of dust separation (and not collection), the particles are exclusively collected in the cyclone and the need of rapping mechanisms is thus avoided.
Efficiency increases due to recirculation and agglomeration of very small particles with larger ones coming directly from the process. A ReCyclone® MH decreases emissions of Hurricane cyclones alone by 40 to 60%. As with cyclone systems, ReCyclone® MH systems are very robust, do not have temperature limitations and do not have moving parts to be frequently changed. Finally, recirculation control provides the benefit of handling variable process flow rates.
The next figure exemplifies a ReCyclone® MH in stainless steel AISI 304L for particle recovery in drying process. Recirculators can be disposed vertically, as shown, or horizontally.
Recent adoption of electrostatic recirculation in the same cyclone system has successfully proven to further reduce particle emissions, even in the [1;5]µm particle size range, assuring future regulation compliance, particularly where legal limits are very tight, with the objective of bag filter redundancy.
A DC high voltage is applied in the concentrator, allowing the recirculation of very fin nanometric particles, more resistant to centrifugal forces, to the cyclone collector.
After having been separated in the recirculator and concentrated in the recirculation flow, electrically charged fine particles are attracted by the cyclone walls, while agglomerating with larger particles entering the system, both promoting their easier capture.
Since particles are not captured on the walls of the recirculator, contrary to ESPs, ReCyclone® systems avoid the problem of dust colmatation and condensation.
Additionally, ReCyclone® EH systems are also immune to either low or high dust electrical resistivity and the HV required power is only 10 to 15 % of that used in ESPs. Electrostatic recirculation for fine particle capture was the winner of the Portuguese Environmental Press Award in 2008 and nominee for the European Environmental Press Award 2008.
